# kb

id: perturbed-angular-correlation-20260505-5
file: data/en.wikipedia.org/wiki/Perturbed_angular_correlation-5.md
category: reference
title: Perturbed angular correlation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Perturbed_angular_correlation
date_saved: 2026-05-05T10:05:41.189355+00:00
instance: kb-cron
parent: perturbed-angular-correlation-20260505-0
summary:
W ( k → 1 , k → 2 ) = ∑ M i , M f , σ 1 , σ 2 | ∑ M ⟨ M f | H 2 | M ⟩ ⟨ M | H 1 | M i ⟩ | 2 {\displaystyle W({\vec {k}}_{1},{\vec {k}}_{2})=\sum _{M_{i},M_{f},\sigma _{1},\sigma _{2}}\left|\sum _{M}\langle M_{f}|{\mathcal {H}}_{2}|M\rangle \langle M|{\mathcal {H}}_{1}|M_{i}\rangle \right|^{2}} W ( k → 1 , k → 2 ) = W ( Θ ) = ∑ k g e r a d e k m a x A k ( 1 ) A k ( 2 ) P k ( cos ⁡ Θ ) {\displaystyle W({\vec {k}}_{1},{\vec {k}}_{2})=W(\Theta )=\sum _{k_{gerade}}^{k_{max}}A_{k}(1)A_{k}(2)P_{k}(\cos {\Theta })} 0 ≤ k ≤ {\displaystyle 0\leq k\leq } Minimum von ( 2 I , l 1 + l 1 ′ , l 2 + l 2 ′ ) {\displaystyle (2I,l_{1}+l_{1}',l_{2}+l_{2}')} W ( Θ , t ) = ∑ k = 2 , 4 A k k P k ( cos ⁡ Θ ) {\displaystyle W(\Theta ,t)=\sum _{k=2,4}A_{kk}P_{k}(\cos {\Theta })} | M a ⟩ → Λ ( t ) | M a = ∑ M b | M b ⟩ ⟨ M b | Λ ( t )


id: phase-shift-interferometry-20260505-0
file: data/en.wikipedia.org/wiki/Phase_Shift_Interferometry-0.md
category: reference
title: Phase Shift Interferometry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Phase_Shift_Interferometry
date_saved: 2026-05-05T10:05:42.390129+00:00
instance: kb-cron
parent: phase-shift-interferometry-20260505-0
summary:
Phase Shift Interferometry (PSI) is a technique for areal surface characterisation that focuses on digitising the interference data acquired during a controlled phase shift, usually introduced by the mechanical oscillation of an interference objective. The technique provides full 3D images with typical height measurement repeatability of less than 1 nm, independent of field size. It is a powerful method that allows analysing interferograms to recover phase information. Traditionally, interferograms were measured by locating the centre of a fringe and then tracing along it. Phase shift interferometry avoids the need to track the location of fringes and enables a point-by-point reconstruction of the wavefront. PSI offers significantly lower measurement noise, potentially as low as 0.01 nm. It is the preferred technique for measuring the surface roughness of super-smooth surfaces. == Principle of Operation == Interferometers utilize the wave properties of light to analyse surface characteristics, particularly surface height variations. For evaluating areal surface topography, interferometers separate the source light so that it follows two independent paths: one includes a reference surface and the other the object surface. The separated light beams then recombine and are directed to a digital camera that measures the resultant light intensity over multiple image points simultaneously.


id: photoactivated-localization-microscopy-20260505-0
file: data/en.wikipedia.org/wiki/Photoactivated_localization_microscopy-0.md
category: reference
title: Photoactivated localization microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photoactivated_localization_microscopy
date_saved: 2026-05-05T10:05:43.599525+00:00
instance: kb-cron
parent: photoactivated-localization-microscopy-20260505-0
summary:
Photo-activated localization microscopy (PALM or FPALM) and stochastic optical reconstruction microscopy (STORM) are widefield (as opposed to point scanning techniques such as laser scanning confocal microscopy) fluorescence microscopy imaging methods that allow obtaining images with a resolution beyond the diffraction limit. The methods were proposed in 2006 in the wake of a general emergence of optical super-resolution microscopy methods, and were featured as Methods of the Year for 2008 by the Nature Methods journal. The development of PALM as a targeted biophysical imaging method was largely prompted by the discovery of new species and the engineering of mutants of fluorescent proteins displaying a controllable photochromism, such as photo-activatible GFP. However, the concomitant development of STORM, sharing the same fundamental principle, originally made use of paired cyanine dyes. One molecule of the pair (called activator), when excited near its absorption maximum, serves to reactivate the other molecule (called reporter) to the fluorescent state. A growing number of dyes are used for PALM, STORM and related techniques, both organic fluorophores and fluorescent proteins. Some are compatible with live cell imaging, others allow faster acquisition or denser labeling. The choice of a particular fluorophore ultimately depends on the application and on its underlying


id: photoactivated-localization-microscopy-20260505-1
file: data/en.wikipedia.org/wiki/Photoactivated_localization_microscopy-1.md
category: reference
title: Photoactivated localization microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photoactivated_localization_microscopy
date_saved: 2026-05-05T10:05:43.599525+00:00
instance: kb-cron
parent: photoactivated-localization-microscopy-20260505-0
summary:
where N is the number of collected photons, a is the pixel size of the imaging detector, b 2 {\displaystyle b^{2}} is the average background signal and s i {\displaystyle s_{i}} is the standard deviation of the point spread function. The requirement of localizing at the same time multiple fluorophores simultaneously over an extended area determines the reason why these methods are wide-field, employing as a detector a CCD, EMCCD or a CMOS camera. The requirement for an enhanced signal-to-noise ratio to maximize localization precision determines the frequent combination of this concept with widefield fluorescent microscopes allowing optical sectioning, such as total internal reflection fluorescence microscopes (TIRF) and light sheet fluorescence microscopes. == Super-resolution image == The resolution of the final image is limited by the precision of each localization and the number of localizations, instead of by diffraction. The super resolution image is therefore a pointillistic representation of the coordinates of all the localized molecules. The super resolution image is commonly rendered by representing each molecule in the image plane as a two dimensional Gaussian with amplitude proportional to the number of photons collected, and the standard deviation depending on the localization precision. == Applications == === Multicolor PALM/STORM


id: photochemical-action-plots-20260505-0
file: data/en.wikipedia.org/wiki/Photochemical_action_plots-0.md
category: reference
title: Photochemical action plots
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photochemical_action_plots
date_saved: 2026-05-05T10:05:44.791207+00:00
instance: kb-cron
parent: photochemical-action-plots-20260505-0
summary:
Photochemical action plots are a scientific tool used to understand the effects of different wavelengths of light on photochemical reactions. The methodology involves exposing a reaction solution to the same number of photons at varying monochromatic wavelengths, monitoring the conversion or reaction yield of starting materials and/or reaction products. Such global high-resolution analysis of wavelength-dependent chemical reactivity has revealed that maxima in absorbance and reactivity often do not align. Photochemical action plots are historically connected to (biological) action spectra. == Historical development == The study of biological responses to specific wavelengths dates back to the late 19th century. Research primarily focused on assessing photodamage from solar radiation using broad-band lamps and narrow filters. These studies quantified effects such as cell viability, production of erythema, vitamin D3 degradation, DNA changes, and skin cancer appearance. The first biological action spectrum was recorded by Engelmann, who used a prism to produce different colors of light and then illuminated cladophora in a bacteria suspension. He discovered the effects of different light wavelengths on photosynthesis, marking the first recorded action spectrum of photosynthesis. Critical evaluations of active wavelength regions in these studies helped identify contributing chromophores to processes such as photosynthesis. These chromophores are key


id: photoconductive-atomic-force-microscopy-20260505-0
file: data/en.wikipedia.org/wiki/Photoconductive_atomic_force_microscopy-0.md
category: reference
title: Photoconductive atomic force microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photoconductive_atomic_force_microscopy
date_saved: 2026-05-05T10:05:46.030587+00:00
instance: kb-cron
parent: photoconductive-atomic-force-microscopy-20260505-0
summary:
Photoconductive atomic force microscopy (PC-AFM) is a variant of atomic force microscopy that measures photoconductivity in addition to surface forces. == Background == Multi-layer photovoltaic cells have gained popularity since mid 1980s. At the time, research was primarily focused on single-layer photovoltaic (PV) devices between two electrodes, in which PV properties rely heavily on the nature of the electrodes. In addition, single layer PV devices notoriously have a poor fill factor. This property is largely attributed to resistance that is characteristic of the organic layer. The fundamentals of pc-AFM are modifications to traditional AFM and focus on the use of pc-AFM in PV characterization. In pc-AFM the major modifications include: a second illumination laser, an inverted microscope and a neutral density filter. These components assist in the precise alignment of the illumination laser and the AFM tip within the sample. Such modifications must complement the existing principals and instrumental modules of pc-AFM so as to minimize the effect of mechanical noise and other interferences on the cantilever and sample. The original exploration of the PV effect can be accredited to research published by Henri Becquerel in 1839. Becquerel noticed the generation of a photocurrent after illumination when he submerged platinum


id: photoconductive-atomic-force-microscopy-20260505-1
file: data/en.wikipedia.org/wiki/Photoconductive_atomic_force_microscopy-1.md
category: reference
title: Photoconductive atomic force microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photoconductive_atomic_force_microscopy
date_saved: 2026-05-05T10:05:46.030587+00:00
instance: kb-cron
parent: photoconductive-atomic-force-microscopy-20260505-0
summary:
== Theory == The fundamental principles of photoconductive atomic force microscopy (pc-AFM) are based on those of traditional atomic force microscopy (AFM) in that an ultrafine metallic tip scans the surface of a material to quantify topological features. The working premises for all types of AFM techniques are largely dependent on the fundamentals of the AFM cantilever, metallic tip, scanning piezo-tube and the feedback loop that transfers information from lasers that guide the motion of the probe across the surface of a sample. The ultra-fine dimensions of the tip and the way the tip scans the surface produces lateral resolutions of 500 nm or less. In AFM, the cantilever and tip functions as a mass on a spring. When a force acts on the spring (cantilever), the spring response is directly related to the magnitude of the force. k is defined as the force constant of the cantilever. Hooke's law for cantilever motion: f = − k d {\displaystyle f=-kd} The forces acting on the tip are such that the spring (cantilever) remains soft but responds to the applied force, with a detectable resonant frequency, fo. In Hooke's law, k is the spring constant of the cantilever and mo is


id: photoconductive-atomic-force-microscopy-20260505-2
file: data/en.wikipedia.org/wiki/Photoconductive_atomic_force_microscopy-2.md
category: reference
title: Photoconductive atomic force microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photoconductive_atomic_force_microscopy
date_saved: 2026-05-05T10:05:46.030587+00:00
instance: kb-cron
parent: photoconductive-atomic-force-microscopy-20260505-0
summary:
The principles of the piezo-tube is dependent upon how the piezo-electric material reacts with an applied voltage to either the interior or exterior of the tube. When voltage is applied to the two electrodes connected to the scanner, the tube will expand or contract causing motion to the AFM tip in the direction of this movement. This phenomenon is illustrated as the piezo-tube becomes displaced by an angle, θ. As the tube is displaced, the sample that, in traditional AFM is fixed to the tube generates lateral translation and rotation relative to the AFM tip, thus movement of the tip is generated in the x and y directions When voltage is applied of the inside of the tube, movement in the z-direction is implemented. The relationship between the movement of the piezo-tube and the direction of the displacement of the AFM tip assumes that the tube is perfectly symmetric. When no voltage is applied to the tube the z-axis bisects the tube, sample and sample stage symmetrically. When a voltage is applied to the exterior of the tube (x and y motion), the expansion of the tube can be understood as a circular arc. In this equation, the r term


id: photoconductive-atomic-force-microscopy-20260505-3
file: data/en.wikipedia.org/wiki/Photoconductive_atomic_force_microscopy-3.md
category: reference
title: Photoconductive atomic force microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photoconductive_atomic_force_microscopy
date_saved: 2026-05-05T10:05:46.030587+00:00
instance: kb-cron
parent: photoconductive-atomic-force-microscopy-20260505-0
summary:
In traditional instrumentation, the stage is a cylindrical piezo-tube scanner that minimizes the effect of mechanical noise. Most cylindrical piezos are between 12 and 24 mm in length and 6 and 12 mm in diameter. The exterior of the piezo-tube is coated with a thin layer of conducting metal so that this region can sustain an electric field. The interior of the cylinder is divided into four regions (x and y regions) by non-conducting metallic strips. Electrical leads are fixed to one end and the exterior wall of the cylinder so that a current can be applied. When a voltage is applied to the exterior, the cylinder expands in x and y direction. Voltage along the interior of the tube causes cylinder expansion in the z-direction and thus movement of the tip in the z-direction. The placement of the piezo tube is dependent upon the type of AFM performed and the mode of analysis. However the z-piezo must always be fixed above the tip and cantilever to control the z-motion. This configuration is most often seen in the c-AFM and pc-AFM modifications to make room for additional instrumental components which are placed below the scanning stage. This is particularly true


id: photoconductive-atomic-force-microscopy-20260505-4
file: data/en.wikipedia.org/wiki/Photoconductive_atomic_force_microscopy-4.md
category: reference
title: Photoconductive atomic force microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photoconductive_atomic_force_microscopy
date_saved: 2026-05-05T10:05:46.030587+00:00
instance: kb-cron
parent: photoconductive-atomic-force-microscopy-20260505-0
summary:
The main components and instrumentation of c-AFM instrumentation are identical to that required for a pc-AFM module. The only modifications are the illumination source, filter and inverted microscope objective that are located beneath the sample substrate. In fact, most pc-AFM instruments are simply modified from existing cp-AFM instrumentation. The first report of this instrumental modification came in 2008. In that paper, Lee and coworkers implemented the aforementioned modifications to examine the resolution of photocurrent imaging. Their design consisted of three main units: a conductive mirror plate, steering mirror and laser source. The main difficulty with the previously existing c-AFM instrumentation is the inability of the technique for characterizing photonic devices. Specifically, it is difficult to measure changes in local and nano-scale electrical properties that result from the photonic effect. The optical illumination component (laser) was added to the c-AFM module in order to make such properties visible. Early in development, the main concerns regarding pc-AFM include: physical configuration, laser disturbance and laser alignment. Although many of these concerns have been resolved pc-AFM modules are still widely modified from c-AFM and traditional AFM instruments. The first main concern deals with component configuration and whether or not there is physically enough space


id: photoconductive-atomic-force-microscopy-20260505-5
file: data/en.wikipedia.org/wiki/Photoconductive_atomic_force_microscopy-5.md
category: reference
title: Photoconductive atomic force microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photoconductive_atomic_force_microscopy
date_saved: 2026-05-05T10:05:46.030587+00:00
instance: kb-cron
parent: photoconductive-atomic-force-microscopy-20260505-0
summary:
== Applications == Although there is significant insight as to how OPVs work, it is still difficult to relate the device's functionality to local film structures. This difficulty may be attributed to the minimal current generation at a given point within OPVs. Through pc-AFM, OPV devices can be probed at nano-scale level and can help to increase our fundamental knowledge of mechanisms involved in OPVs at nano-scale level. pc-AFM is capable of gathering information such as the mapping of photocurrents, differences in film morphology, determination of donor-acceptor domains, current density-voltage plots, quantum efficiencies, and approximate charge carrier mobilities. One of the other notable characteristics of pc-AFM is its ability to provide concurrent information regarding the topological and photocurrent properties of the device at nano-scale. Using this concurrent sampling method, the sample handling is minimized and can provide more accurate results. In a study by Pingree et al., pc-AFM was used to measure how spatial deviations in the photocurrent generation developed with different processing techniques. The authors were able to compare these photocurrent variations to the duration of the annealing process. They have concluded that lengthening the annealing time allows for improved nano-scale phase separation as well as created a more


id: photoconductive-atomic-force-microscopy-20260505-6
file: data/en.wikipedia.org/wiki/Photoconductive_atomic_force_microscopy-6.md
category: reference
title: Photoconductive atomic force microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photoconductive_atomic_force_microscopy
date_saved: 2026-05-05T10:05:46.030587+00:00
instance: kb-cron
parent: photoconductive-atomic-force-microscopy-20260505-0
summary:
Once the sample preparation is complete, the sample is placed onto the scanning stage of the pc-AFM module. This scanning stage is used for x-y piezo translation, completely independent of the z-direction while using a z-piezo scanner. The piezo-electric material within this scanner converts a change in the applied potential into mechanical motion which moves the samples with nanometer resolution and accuracy. There are two variations in which the z-piezo scanner functions; one is contact mode while the other is tapping mode. Many commercial AFM cantilever tips have pre-measured resonant frequencies and force constants which are provided to the customer. As sampling proceeds, the cantilever tip's position changes, which causes the scanning laser wavelength (650 nm) to deviate from its original position on the detector. The z-piezo scanner then recognizes this deviation and moves vertically to return the laser spot to its set position. This vertical movement by the z-piezo scanner is correlated to a change in voltage. Sampling in contact mode relies upon intermolecular forces between the tip and surface as depicted by Van der Waals force. As the sampling begins, the tip is moved close to the sample which creates a weakly attractive force between them. Another force


id: photoconductive-atomic-force-microscopy-20260505-7
file: data/en.wikipedia.org/wiki/Photoconductive_atomic_force_microscopy-7.md
category: reference
title: Photoconductive atomic force microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photoconductive_atomic_force_microscopy
date_saved: 2026-05-05T10:05:46.030587+00:00
instance: kb-cron
parent: photoconductive-atomic-force-microscopy-20260505-0
summary:
The range of bias commonly applied is usually limited to between −5 V to +5 V for most studies. This can be achieved by applying a forward bias or reverse bias to the sample through the spotted gold contact. By adjusting this bias, along with the current passing through the cantilever, one can adjust the repulsive/attractive forces between the sample and the tip. When a reverse bias is applied (tip is negative relative to the sample), the tip and the sample experience attractive forces between them. This current density measurement is then combined with the topographical information previously gathered from the AFM tip and cantilever. The resulting image displays the local variations in morphology with the current density measurements superimposed onto of them. Several methods have been employed to help reduce both mechanical and acoustic vibrations within the system. Mechanical vibrations are mainly attributed to traffic in and out of a building Other sources of mechanical vibrations have often been seen in the higher stories of a building due to reduced damping from building supports. This source of vibrational noise is easily controlled through the use of a vibration isolation table. Acoustical vibrations are far more common than mechanical vibrations.


id: photon-induced-near-field-electron-microscopy-20260505-0
file: data/en.wikipedia.org/wiki/Photon-Induced_Near-field_Electron_Microscopy-0.md
category: reference
title: Photon-Induced Near-field Electron Microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photon-Induced_Near-field_Electron_Microscopy
date_saved: 2026-05-05T10:05:47.220980+00:00
instance: kb-cron
parent: photon-induced-near-field-electron-microscopy-20260505-0
summary:
Photon-Induced Near-field Electron Microscopy (PINEM) is a variant of the Ultrafast Transmission Electron Microscopy technique and is based on the inelastic coupling between electrons and photons in presence of a surface or a nanostructure. This method allows one to investigate time-varying nanoscale electromagnetic fields in an electron microscope. For visible light, such inelastic coupling between electrons and light, i.e. direct absorption or emission of photons, is forbidden in free space (vacuum) since it is not possible to simultaneously conserve both energy and momentum. This constraint can be circumvented when photon momentum is broadened as a result of light being reflected or scattered from a surface or nanostructure. This process would then generate evanescently confined near-fields with a broad momentum distribution, reaching high intensities in a nanoconfined space and thus also boosting the cross section of electron-light coupling. Theoretically, the analytical description of the phenomenon has been provided by Park et al., Garcia de Abajo et al. and Feist et al. In these works the authors demonstrated that the strength of electron-light interaction depends on the linear coupling to the electric field projection along the electron propagation direction. In particular, Feist et al. also experimentally demonstrated that the interaction process results


id: photonic-force-microscope-20260505-0
file: data/en.wikipedia.org/wiki/Photonic_force_microscope-0.md
category: reference
title: Photonic force microscope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photonic_force_microscope
date_saved: 2026-05-05T10:05:48.403870+00:00
instance: kb-cron
parent: photonic-force-microscope-20260505-0
summary:
Photonic force microscopy (PFM) is an optical-tweezers-based microscopy technique. A small dielectric particle (20 nm to several micrometres) is held by a strongly focused laser beam. The forward scattered light, i.e. the light whose orientation is slightly changed while passing through the particle, and unscattered light are collected by a lens and projected onto a Quadrant Photo-Diode (QPD), i.e. a Position sensitive device (PSD). These two components interfere in the detector and produce signals, which permit the detection of the bead's position in three dimensions. The precision is very good (as low as 0.1 nm) and the recording speed is very high (up to 1 MHz). Brownian motion deflects the bead from the resting position. A time sequence of measured positions allows one to derive the optical potential in which the particle is held. The PFM is sensitive to the environment of the particle and has been used in a variety of different experiments that e.g. monitor space that can be filled by particles inside agarose or the fate of small latex beads captured by macrophages. A similar concept of scanning a bead with an optical trap over a surface was invented in 1993 by Ghislain and W. W. Webb.


id: porosimetry-20260505-0
file: data/en.wikipedia.org/wiki/Porosimetry-0.md
category: reference
title: Porosimetry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Porosimetry
date_saved: 2026-05-05T10:05:49.544741+00:00
instance: kb-cron
parent: porosimetry-20260505-0
summary:
Porosimetry is an analytical technique used to determine various quantifiable aspects of a material's porous structure, such as pore diameter, total pore volume, surface area, and bulk and absolute densities. The technique involves the intrusion of a non-wetting liquid (often mercury) at high pressure into a material through the use of a porosimeter. The pore size can be determined based on the external pressure needed to force the liquid into a pore against the opposing force of the liquid's surface tension. A force balance equation known as Washburn's equation for the above material having cylindrical pores is given as: P L − P G = − 4 σ cos ⁡ θ D P {\displaystyle P_{L}-P_{G}=-{\frac {4\sigma \cos \theta }{D_{P}}}} P L {\displaystyle P_{L}} = pressure of liquid P G {\displaystyle P_{G}} = pressure of gas σ {\displaystyle \sigma } = surface tension of liquid θ {\displaystyle \theta } = contact angle of intrusion liquid D P {\displaystyle D_{P}} = pore diameter Since the technique is usually performed within a vacuum, the initial gas pressure is zero. The contact angle of mercury with most solids is between 135° and 142°, so an average of 140° can be taken without much error.


id: protein-chemical-shift-prediction-20260505-0
file: data/en.wikipedia.org/wiki/Protein_chemical_shift_prediction-0.md
category: reference
title: Protein chemical shift prediction
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Protein_chemical_shift_prediction
date_saved: 2026-05-05T10:05:50.752609+00:00
instance: kb-cron
parent: protein-chemical-shift-prediction-20260505-0
summary:
Protein chemical shift prediction is a branch of biomolecular nuclear magnetic resonance spectroscopy that aims to accurately calculate protein chemical shifts from protein coordinates. Protein chemical shift prediction was first attempted in the late 1960s using semi-empirical methods applied to protein structures solved by X-ray crystallography. Since that time protein chemical shift prediction has evolved to employ much more sophisticated approaches including quantum mechanics, machine learning and empirically derived chemical shift hypersurfaces. The most recently developed methods exhibit remarkable precision and accuracy. == Protein chemical shifts == NMR chemical shifts are often called the mileposts of nuclear magnetic resonance spectroscopy. Chemists have used chemical shifts for more than 50 years as highly reproducible, easily measured parameters to map out the covalent structure of small organic molecules. Indeed, the sensitivity of NMR chemical shifts to the type and character of neighbouring atoms, combined with their reasonably predictable tendencies has made them invaluable for both deciphering and describing the structure of thousands of newly synthesized or newly isolated compounds The same sensitivity to a variety of important protein structural features has made protein chemical shifts equally valuable to protein chemists and biomolecular NMR spectroscopists. In particular, protein chemical shifts are sensitive not


id: qemscan-20260505-0
file: data/en.wikipedia.org/wiki/QEMSCAN-0.md
category: reference
title: QEMSCAN
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/QEMSCAN
date_saved: 2026-05-05T10:05:51.918183+00:00
instance: kb-cron
parent: qemscan-20260505-0
summary:
QEMSCAN is the name for an integrated automated mineralogy and petrography system providing quantitative analysis of minerals, rocks and man-made materials. QEMSCAN is an abbreviation standing for quantitative evaluation of materials by scanning electron microscopy, and a registered trademark owned by FEI Company since 2009. Prior to 2009, QEMSCAN was developed, marketed and sold by Intellection Pty Ltd (a company owned by CSIRO) and also marketed and sold by LEO (Leica electron optics, a company jointly owned by Leica and Zeiss). The integrated system comprises a scanning electron microscope (SEM) with a large specimen chamber, up to four light-element energy-dispersive X-ray spectroscopy (EDS) detectors, an electron backscatter detector, and proprietary software and hardware controlling automated data acquisition. The offline software package iDiscover provides data processing and reporting functionality. == Mineral identification and quantification == QEMSCAN creates phase assemblage maps of a specimen surface scanned by a high-energy accelerated electron beam along a predefined raster scan pattern. Low-count energy-dispersive X-ray spectra (EDX) are generated and provide information on the elemental composition at each measurement point. The elemental composition in combination with back-scattered electron (BSE) brightness and x-ray count rate information is converted into mineral phases. QEMSCAN data includes bulk mineralogy and


id: random-coil-index-20260505-0
file: data/en.wikipedia.org/wiki/Random_coil_index-0.md
category: reference
title: Random coil index
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Random_coil_index
date_saved: 2026-05-05T10:05:53.091599+00:00
instance: kb-cron
parent: random-coil-index-20260505-0
summary:
Random coil index (RCI) predicts protein flexibility by calculating an inverse weighted average of backbone secondary chemical shifts and predicting values of model-free order parameters as well as per-residue RMSD of NMR and molecular dynamics ensembles from this parameter. The key advantages of this protocol over existing methods of studying protein flexibility are it does not require prior knowledge of a protein's tertiary structure, it is not sensitive to the protein's overall tumbling and it does not require additional NMR measurements beyond the standard experiments for backbone assignments. The application of secondary chemical shifts to characterize protein flexibility is based on an assumption that the proximity of chemical shifts to random coil values is a manifestation of increased protein mobility, while significant differences from random coil values are an indication of a relatively rigid structure. Even though chemical shifts of rigid residues may adopt random coil values as a result of comparable contributions of shielding and deshielding effects (e.g. from torsion angles, hydrogen bonds, ring currents, etc.), combining the chemical shifts from multiple nuclei into a single parameter allows one to decrease the influence of these flexibility false positives. The improved performance originates from the different probabilities of random coil


id: recurrence-tracking-microscope-20260505-0
file: data/en.wikipedia.org/wiki/Recurrence_tracking_microscope-0.md
category: reference
title: Recurrence tracking microscope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Recurrence_tracking_microscope
date_saved: 2026-05-05T10:05:54.290181+00:00
instance: kb-cron
parent: recurrence-tracking-microscope-20260505-0
summary:
A recurrence tracking microscope (RTM) is a microscope that is based on the quantum recurrence phenomenon of an atomic wave packet. It is used to investigate the nano-structure on a surface. == History == In 2006, Farhan Saif used quantum recurrence phenomena of wave packet as a probe to study nano-structures on a surface, naming it Recurrence Tracking Microscope (RTM). == Background == The tunneling phenomenon is used as a probe to study nano-structure on a surface with the help of scanning tunneling microscope (STM). The STM is a powerful device for viewing surfaces at the atomic level. The STM can be used not only in an ultra-high vacuum, but also in air and a variety of other media and at temperatures ranging from nearly zero to hundreds of kelvin. This idea was enhanced to create the atomic force microscope (AFM), which is a very high-resolution type of scanning probe microscope with resolution of fractions of a nanometer. The AFM is one of the foremost tools for imaging, measuring and manipulating matter at the nanoscale. The application of RTM includes the visualization and measurement of surface features having sizes and dimensions as small as one nanometer in research and development


id: reflectance-difference-spectroscopy-20260505-0
file: data/en.wikipedia.org/wiki/Reflectance_difference_spectroscopy-0.md
category: reference
title: Reflectance difference spectroscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Reflectance_difference_spectroscopy
date_saved: 2026-05-05T10:05:55.479852+00:00
instance: kb-cron
parent: reflectance-difference-spectroscopy-20260505-0
summary:
Reflectance difference spectroscopy (RDS) is a spectroscopic technique which measures the difference in reflectance of two beams of light that are shone in normal incident on a surface with different linear polarizations. It is also known as reflectance anisotropy spectroscopy (RAS). It is calculated as: R D S = 2 r α − r β r α + r β , r ∈ C {\displaystyle RDS=2{\frac {r_{\alpha }-r_{\beta }}{r_{\alpha }+r_{\beta }}},r\in \mathbb {C} } r α {\displaystyle r_{\alpha }} and r β {\displaystyle r_{\beta }} are the reflectance in two different polarizations. The method was introduced in 1985 for the study optical properties of the cubic semiconductors silicon and germanium. Due to its high surface sensitivity and independence of ultra-high vacuum, its use has been expanded to in situ monitoring of epitaxial growth or the interaction of surfaces with adsorbates. To assign specific features in the signal to their origin in morphology and electronic structure, theoretical modelling by density functional theory is required. == References ==


id: reststrahlen-effect-20260505-0
file: data/en.wikipedia.org/wiki/Reststrahlen_effect-0.md
category: reference
title: Reststrahlen effect
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Reststrahlen_effect
date_saved: 2026-05-05T10:05:56.711908+00:00
instance: kb-cron
parent: reststrahlen-effect-20260505-0
summary:
The Reststrahlen effect (German: “residual rays”) is a reflectance phenomenon in which electromagnetic radiation within a narrow energy band cannot propagate within a given medium due to a change in refractive index concurrent with the specific absorbance band of the medium in question; this narrow energy band is termed the Reststrahlen band. As a result of this inability to propagate, normally incident Reststrahlen-band radiation experiences strong reflection or total reflection from that medium. The energies at which Reststrahlen bands occur vary and are particular to the individual compound. Numerous physical attributes of a compound will have an effect on the appearance of the Reststrahlen band. These include phonon band-gap, particle/grain size, strongly absorbing compounds, compounds with optically opaque bands in the infrared. == Appearance == The term Reststrahlen was coined following the observation by Heinrich Rubens in 1898 that repeated reflection of an infrared beam at the surface of a given material suppresses radiation at all wavelengths except for certain spectral intervals, and Rubens detected wavelengths of sizes around 60 μm. The measured intensity for these special intervals (the Reststrahlen range) indicates a reflectance of up to 80% or even more, while the maximum reflectance due to infrared bands of


id: rutherford-backscattering-spectrometry-20260505-0
file: data/en.wikipedia.org/wiki/Rutherford_backscattering_spectrometry-0.md
category: reference
title: Rutherford backscattering spectrometry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Rutherford_backscattering_spectrometry
date_saved: 2026-05-05T10:05:57.856664+00:00
instance: kb-cron
parent: rutherford-backscattering-spectrometry-20260505-0
summary:
Rutherford backscattering spectrometry (RBS) is an analytical technique used in materials science. Sometimes referred to as high-energy ion scattering (HEIS) spectrometry, RBS is used to determine the structure and composition of materials by measuring the backscattering of a beam of high energy ions (typically protons or alpha particles) impinging on a sample. == Geiger–Marsden experiment == Rutherford backscattering spectrometry is named after Lord Rutherford, a physicist sometimes referred to as the father of nuclear physics. Rutherford supervised a series of experiments carried out by Hans Geiger and Ernest Marsden between 1909 and 1914 studying the scattering of alpha particles through metal foils. While attempting to eliminate "stray particles" they believed to be caused by an imperfection in their alpha source, Rutherford suggested that Marsden attempt to measure backscattering from a gold foil sample. According to the then-dominant plum-pudding model of the atom, in which small negative electrons were spread through a diffuse positive region, backscattering of the high-energy positive alpha particles should have been nonexistent. At most small deflections should occur as the alpha particles passed almost unhindered through the foil. Instead, when Marsden positioned the detector on the same side of the foil as the alpha particle source, he


id: rutherford-backscattering-spectrometry-20260505-1
file: data/en.wikipedia.org/wiki/Rutherford_backscattering_spectrometry-1.md
category: reference
title: Rutherford backscattering spectrometry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Rutherford_backscattering_spectrometry
date_saved: 2026-05-05T10:05:57.856664+00:00
instance: kb-cron
parent: rutherford-backscattering-spectrometry-20260505-0
summary:
where Z 1 {\displaystyle Z_{1}} and Z 2 {\displaystyle Z_{2}} are the atomic numbers of the incident and target nuclei. This equation is written in the centre of mass frame of reference and is therefore not a function of the mass of either the projectile or the target nucleus. The scattering angle in the laboratory frame of reference θ 1 {\displaystyle \theta _{1}} is not the same as the scattering angle in the centre of mass frame of reference θ {\displaystyle \theta } (although for RBS experiments they are usually very similar). However, heavy ion projectiles can easily recoil lighter ions which, if the geometry is right, can be ejected from the target and detected. This is the basis of the Elastic Recoil Detection (ERD, with synonyms ERDA, FRS, HFS) technique. RBS often uses a He beam which readily recoils H, so simultaneous RBS/ERD is frequently done to probe the hydrogen isotope content of samples (although H ERD with a He beam above 1 MeV is not Rutherford: see http://www-nds.iaea.org/sigmacalc). For ERD the scattering angle in the lab frame of reference is quite different from that in the centre of mass frame of reference. Heavy ions cannot backscatter from light


id: rutherford-backscattering-spectrometry-20260505-2
file: data/en.wikipedia.org/wiki/Rutherford_backscattering_spectrometry-2.md
category: reference
title: Rutherford backscattering spectrometry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Rutherford_backscattering_spectrometry
date_saved: 2026-05-05T10:05:57.856664+00:00
instance: kb-cron
parent: rutherford-backscattering-spectrometry-20260505-0
summary:
An ion source, usually alpha particles (He2+ ions) or, less commonly, protons. A linear particle accelerator capable of accelerating incident ions to high energies, usually in the range 1-3 MeV. A detector capable of measuring the energies of backscattered ions over some range of angles. Two common source/acceleration arrangements are used in commercial RBS systems, working in either one or two stages. One-stage systems consist of a He+ source connected to an acceleration tube with a high positive potential applied to the ion source, and the ground at the end of the acceleration tube. This arrangement is simple and convenient, but it can be difficult to achieve energies of much more than 1 MeV due to the difficulty of applying very high voltages to the system. Two-stage systems, or "tandem accelerators", start with a source of He− ions and position the positive terminal at the center of the acceleration tube. A stripper element included in the positive terminal removes electrons from ions which pass through, converting He− ions to He++ ions. The ions thus start out being attracted to the terminal, pass through and become positive, and are repelled until they exit the tube at ground. This arrangement, though more


id: rutherford-backscattering-spectrometry-20260505-3
file: data/en.wikipedia.org/wiki/Rutherford_backscattering_spectrometry-3.md
category: reference
title: Rutherford backscattering spectrometry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Rutherford_backscattering_spectrometry
date_saved: 2026-05-05T10:05:57.856664+00:00
instance: kb-cron
parent: rutherford-backscattering-spectrometry-20260505-0
summary:
R = 2 Z 1 Z 2 e 2 L E 0 {\displaystyle R=2{\sqrt {\frac {Z_{1}Z_{2}e^{2}L}{E_{0}}}}} When an ion is scattered from deep inside a sample, it can then re-scatter off a second atom, creating a second blocked cone in the direction of the scattered trajectory. This can be detected by carefully varying the detection angle relative to the incident angle. Channeling is observed when the incident beam is aligned with a major symmetry axis of the crystal. Incident nuclei which avoid collisions with surface atoms are excluded from collisions with all atoms deeper in the sample, due to blocking by the first layer of atoms. When the interatomic distance is large compared to the radius of the blocked cone, the incident ions can penetrate many times the interatomic distance without being backscattered. This can result in a drastic reduction of the observed backscattered signal when the incident beam is oriented along one of the symmetry directions, allowing determination of a sample's regular crystal structure. Channeling works best for very small blocking radii, i.e. for high-energy, low-atomic-number incident ions such as He+. The tolerance for the deviation of the ion beam angle of incidence relative to the symmetry direction depends


id: rutherford-backscattering-spectrometry-20260505-4
file: data/en.wikipedia.org/wiki/Rutherford_backscattering_spectrometry-4.md
category: reference
title: Rutherford backscattering spectrometry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Rutherford_backscattering_spectrometry
date_saved: 2026-05-05T10:05:57.856664+00:00
instance: kb-cron
parent: rutherford-backscattering-spectrometry-20260505-0
summary:
=== Bibliography === Rhodes, Richard (1988) [1986]. The Making of the Atomic Bomb. Simon & Schuster. ISBN 978-0-684-81378-3. Oura, K.; Lifshits, V.G.; Saranin, A.A.; Zotov, A.V.; et al. (2003). Surface Science: An Introduction. Springer-Verlag. ISBN 3-540-00545-5. Feldman, L.C.; Mayer, J.W.; Picraux, S.T. (1982). Materials Analysis by Ion Channeling. Academic Press. Feldman, L.C.; Mayer, J.W. (1986). Fundamentals of Surface and Thin Film Analysis. Prentice-Hall. "RBS Theory Tutorial". Evans Analytical Group: Training. Retrieved 2007-10-10. "RBS Instrumentation Tutorial". Evans Analytical Group: Training. Retrieved 2007-10-10. Hobbs, C.P.; McMillan, J.W.; Palmer, D.W. (1988). "The effects of surface topography in nuclear microprobe Rutherford backscattering analysis". Nuclear Instruments and Methods in Physics Research B. 30 (3): 342–348. Bibcode:1988NIMPB..30..342H. doi:10.1016/0168-583X(88)90023-7. Frenken, J.W.M.; Maree, P.M.J.; van der Veen, J.F. (1986). "Observation of surface-initiated melting". Phys. Rev. B. 34 (11): 7506–7516. Bibcode:1986PhRvB..34.7506F. doi:10.1103/PhysRevB.34.7506. hdl:1887/71635. PMID 9939429. S2CID 27028634. Maragkos, F.; Dimitrakopoulos, N.; Georgali, E.; Kokkoris, M.; Lagogiannis, A.; Ntemou, E.; Patronis, N.; Tsakiris, Th.; Ziagkova, A. (2021-11-15). "Differential cross-section measurements for proton elastic scattering on natSi in the energy range Ep, lab = 3–5 MeV, suitable for EBS". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms. 507: 20–26. Bibcode:2021NIMPB.507...20M. doi:10.1016/j.nimb.2021.09.006. ISSN 0168-583X. S2CID


id: scanning-confocal-electron-microscopy-20260505-0
file: data/en.wikipedia.org/wiki/Scanning_confocal_electron_microscopy-0.md
category: reference
title: Scanning confocal electron microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scanning_confocal_electron_microscopy
date_saved: 2026-05-05T10:05:59.015556+00:00
instance: kb-cron
parent: scanning-confocal-electron-microscopy-20260505-0
summary:
Scanning confocal electron microscopy (SCEM) is an electron microscopy technique analogous to scanning confocal optical microscopy (SCOM). In this technique, the studied sample is illuminated by a focussed electron beam, as in other scanning microscopy techniques, such as scanning transmission electron microscopy or scanning electron microscopy. However, in SCEM, the collection optics are arranged symmetrically to the illumination optics to gather only the electrons that pass the beam focus. This results in superior depth resolution of the imaging. The technique is relatively new and is being actively developed. == History == The idea of SCEM logically follows from SCOM and thus is rather old. However, practical design and construction of scanning confocal electron microscope is a complex problem first solved by Nestor J. Zaluzec. His first scanning confocal electron microscope demonstrated the 3D properties of the SCEM, but have not realized the sub-nanometer lateral spatial resolution achievable with high-energy electrons (lateral resolution of only ~80 nm has been demonstrated). Several groups are currently working on construction of atomic resolution SCEM. In particular, atomically resolved SCEM images have already been obtained == Operation == The sample is illuminated by a focused electron beam, and the beam is re-focused on the detector,


id: scanning-electron-cryomicroscopy-20260505-0
file: data/en.wikipedia.org/wiki/Scanning_electron_cryomicroscopy-0.md
category: reference
title: Scanning electron cryomicroscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scanning_electron_cryomicroscopy
date_saved: 2026-05-05T10:06:00.207402+00:00
instance: kb-cron
parent: scanning-electron-cryomicroscopy-20260505-0
summary:
Scanning electron cryomicroscopy (CryoSEM) is a form of electron microscopy where a hydrated but cryogenically fixed sample is imaged on a scanning electron microscope's cold stage in a cryogenic chamber. The cooling is usually achieved with liquid nitrogen. CryoSEM of biological samples with a high moisture content can be done faster with fewer sample preparation steps than conventional SEM. In addition, the dehydration processes needed to prepare a biological sample for a conventional SEM chamber create numerous distortions in the tissue leading to structural artifacts during imaging. == See also == Electron microscopy Electron cryomicroscopy Transmission electron cryomicroscopy == References ==


id: scanning-electron-microscope-20260505-0
file: data/en.wikipedia.org/wiki/Scanning_electron_microscope-0.md
category: reference
title: Scanning electron microscope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scanning_electron_microscope
date_saved: 2026-05-05T10:06:01.397531+00:00
instance: kb-cron
parent: scanning-electron-microscope-20260505-0
summary:
A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that contain information about the surface topography and composition. The electron beam is scanned in a raster scan pattern, and the position of the beam is combined with the intensity of the detected signal to produce an image. In the most common SEM mode, secondary electrons emitted by atoms excited by the electron beam are detected using a secondary electron detector (Everhart–Thornley detector). The number of secondary electrons that can be detected, and thus the signal intensity, depends, among other things, on specimen topography. Some SEMs can achieve resolutions better than 1 nanometer. Specimens are observed in high vacuum in a conventional SEM, or in low vacuum or wet conditions in a variable pressure or environmental SEM, and at a wide range of cryogenic or elevated temperatures with specialized instruments. == History == An account of the early history of scanning electron microscopy has been presented by McMullan. Although Max Knoll produced a photo with a 50 mm object-field-width showing channeling contrast


id: scanning-electron-microscope-20260505-1
file: data/en.wikipedia.org/wiki/Scanning_electron_microscope-1.md
category: reference
title: Scanning electron microscope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scanning_electron_microscope
date_saved: 2026-05-05T10:06:01.397531+00:00
instance: kb-cron
parent: scanning-electron-microscope-20260505-0
summary:
SEM samples have to be small enough to fit on the specimen stage, and may need special preparation to increase their electrical conductivity and to stabilize them, so that they can withstand the high vacuum conditions and the high energy beam of electrons. Samples are generally mounted rigidly on a specimen holder or stub using a conductive adhesive. SEM is used extensively for defect analysis of semiconductor wafers, and manufacturers make instruments that can examine any part of a 300 mm semiconductor wafer. Many instruments have chambers that can tilt an object of that size to 45° and provide continuous 360° rotation. Nonconductive specimens collect charge when scanned by the electron beam, and especially in secondary electron imaging mode, this causes scanning faults and other image artifacts. For conventional imaging in the SEM, specimens must be electrically conductive, at least at the surface, and electrically grounded to prevent the accumulation of electrostatic charge. Metal objects require little special preparation for SEM except for cleaning and conductively mounting to a specimen stub. Non-conducting materials are usually coated with an ultrathin coating of electrically conducting material, deposited on the sample either by low-vacuum sputter coating, electroless deposition or by high-vacuum evaporation. Conductive


id: scanning-electron-microscope-20260505-2
file: data/en.wikipedia.org/wiki/Scanning_electron_microscope-2.md
category: reference
title: Scanning electron microscope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scanning_electron_microscope
date_saved: 2026-05-05T10:06:01.397531+00:00
instance: kb-cron
parent: scanning-electron-microscope-20260505-0
summary:
In a typical SEM, an electron beam is thermionically emitted from an electron gun fitted with a tungsten filament cathode. Tungsten is normally used in thermionic electron guns because it has the highest melting point and lowest vapor pressure of all metals, thereby allowing it to be electrically heated for electron emission, and because of its low cost. Other types of electron emitters include lanthanum hexaboride (LaB6) cathodes, which can be used in a standard tungsten filament SEM if the vacuum system is upgraded, or field emission guns (FEG), which may be of the cold-cathode type using tungsten single crystal emitters or the thermally assisted Schottky type, that use emitters of tungsten single crystals coated in zirconium oxide. The electron beam, which typically has an energy ranging from 0.2 keV to 40 keV, is focused by one or two condenser lenses to a spot about 0.4 nm to 5 nm in diameter. The beam passes through pairs of scanning coils or pairs of deflector plates in the electron column, typically in the final lens, which deflect the beam in the x and y axes so that it scans in a raster fashion over a rectangular area of the sample surface.


id: scanning-electron-microscope-20260505-3
file: data/en.wikipedia.org/wiki/Scanning_electron_microscope-3.md
category: reference
title: Scanning electron microscope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scanning_electron_microscope
date_saved: 2026-05-05T10:06:01.397531+00:00
instance: kb-cron
parent: scanning-electron-microscope-20260505-0
summary:
Backscattered electrons (BSE) consist of high-energy electrons originating in the electron beam, that are reflected or back-scattered out of the specimen interaction volume by elastic scattering interactions with specimen atoms. Since heavy elements (high atomic number) backscatter electrons more strongly than light elements (low atomic number), and thus appear brighter in the image, BSEs are used to detect contrast between areas with different chemical compositions. The Everhart–Thornley detector, which is normally positioned to one side of the specimen, is inefficient for the detection of backscattered electrons because few such electrons are emitted in the solid angle subtended by the detector, and because the positively biased detection grid has little ability to attract the higher energy BSE. Dedicated backscattered electron detectors are positioned above the sample in a "doughnut" type arrangement, concentric with the electron beam, maximizing the solid angle of collection. BSE detectors are usually either of scintillator or of semiconductor types. When all parts of the detector are used to collect electrons symmetrically about the beam, atomic number contrast is produced. However, strong topographic contrast is produced by collecting back-scattered electrons from one side above the specimen using an asymmetrical, directional BSE detector; the resulting contrast appears as illumination


id: scanning-electron-microscope-20260505-4
file: data/en.wikipedia.org/wiki/Scanning_electron_microscope-4.md
category: reference
title: Scanning electron microscope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scanning_electron_microscope
date_saved: 2026-05-05T10:06:01.397531+00:00
instance: kb-cron
parent: scanning-electron-microscope-20260505-0
summary:
Conventional SEM requires samples to be imaged under vacuum, because a gas atmosphere rapidly spreads and attenuates electron beams. As a consequence, samples that produce a significant amount of vapour, e.g. wet biological samples or oil-bearing rock, must be either dried or cryogenically frozen. Processes involving phase transitions, such as the drying of adhesives or melting of alloys, liquid transport, chemical reactions, and solid-air-gas systems, in general cannot be observed with conventional high-vacuum SEM. In environmental SEM (ESEM), the chamber is evacuated of air, but water vapor is retained near its saturation pressure, and the residual pressure remains relatively high. This allows the analysis of samples containing water or other volatile substances. With ESEM, observations of living insects have been possible. The first commercial development of the ESEM in the late 1980s allowed samples to be observed in low-pressure gaseous environments (e.g. 1–50 Torr or 0.1–6.7 kPa) and high relative humidity (up to 100%). This was made possible by the development of a secondary-electron detector capable of operating in the presence of water vapour and by the use of pressure-limiting apertures with differential pumping in the path of the electron beam to separate the vacuum region (around the gun and


id: scanning-electron-microscope-20260505-5
file: data/en.wikipedia.org/wiki/Scanning_electron_microscope-5.md
category: reference
title: Scanning electron microscope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scanning_electron_microscope
date_saved: 2026-05-05T10:06:01.397531+00:00
instance: kb-cron
parent: scanning-electron-microscope-20260505-0
summary:
=== SEM image coloring === Very often, published SEM images are artificially colored. This may be done for aesthetic effect, to clarify structure or to add a realistic appearance to the sample and generally does not add information about the specimen. Coloring may be performed manually with photo-editing software, or semi-automatically with dedicated software using feature-detection or object-oriented segmentation. Alternately, when additional information from other detectors like EDX, EBSD, ECCI or cathodoluminescence is available, it can be merged as color channel(s) to provide rich material information in a single, high-resolution image. === Color built using multiple electron detectors === In some configurations more information is gathered per pixel, often by the use of multiple detectors. As a common example, secondary electron and backscattered electron detectors are superimposed and a color is assigned to each of the images captured by each detector, with a result of a combined color image where colors are related to the density of the components. This method is known as density-dependent color SEM (DDC-SEM). Micrographs produced by DDC-SEM retain topographical information, which is better captured by the secondary electrons detector and combine it to the information about density, obtained by the backscattered electron detector. === Analytical


id: scanning-electron-microscope-20260505-6
file: data/en.wikipedia.org/wiki/Scanning_electron_microscope-6.md
category: reference
title: Scanning electron microscope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scanning_electron_microscope
date_saved: 2026-05-05T10:06:01.397531+00:00
instance: kb-cron
parent: scanning-electron-microscope-20260505-0
summary:
=== Applications of 3D SEM === One possible application is measuring the roughness of ice crystals. This method can combine variable-pressure environmental SEM and the 3D capabilities of the SEM to measure roughness on individual ice crystal facets, convert it into a computer model and run further statistical analysis on the model. Other measurements include fractal dimension, examining fracture surface of metals, characterization of materials, corrosion measurement, and dimensional measurements at the nano scale (step height, volume, angle, flatness, bearing ratio, coplanarity, etc.). SEM is also used by art conservationists to discern threats to paintings' surface stability due to aging, such as the formations of complexes of zinc ions with fatty acids. Forensic scientists use SEM to detect art forgeries. == Gallery of SEM images == The following are examples of images taken using an SEM. == See also == == References == == External links == General HowStuffWorks – How Scanning Electron Microscopes Work Learn to use an SEM – An online learning environment for people wanting to use an SEM. Provided by Microscopy Australia Virtual SEM – sparkler – an interactive simulation of a scanning electron microscope (SEM) Multichannel color SEM imaging – and with BSE Video on


id: scanning-joule-expansion-microscopy-20260505-0
file: data/en.wikipedia.org/wiki/Scanning_joule_expansion_microscopy-0.md
category: reference
title: Scanning joule expansion microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scanning_joule_expansion_microscopy
date_saved: 2026-05-05T10:06:02.583665+00:00
instance: kb-cron
parent: scanning-joule-expansion-microscopy-20260505-0
summary:
In microscopy, scanning joule expansion microscopy (SJEM) is a form of scanning probe microscopy heavily based on atomic force microscopy (AFM) that maps the temperature distribution along a surface. Resolutions down to 10 nm have been achieved and 1 nm resolution is theoretically possible. Thermal measurements at the nanometer scale are of both academic and industrial interest, particularly in regards to nanomaterials and modern integrated circuits. == Basic Principles == Scanning joule expansion microscopy is based on the contact operation model of atomic force microscopy. During the operation, the tip on the cantilever is brought into contact with the surface of the sample. AC or pulsed electrical signal is applied to the sample creating Joule heating and resulting in periodic thermal expansion. At the same time, the laser, which is focused on the top surface of the cantilever and the photodiode of the equipment, detects the displacement of the cantilever. The detecting photodiode is composed of two segments, which normalizes the incoming signal deflected from the cantilever. This differential signal is proportional to the cantilever deflection. The deflection signals are caused not only by sample topography, but also by the thermal expansion caused by Joule heating. Since AFM has feedback


id: scanning-joule-expansion-microscopy-20260505-1
file: data/en.wikipedia.org/wiki/Scanning_joule_expansion_microscopy-1.md
category: reference
title: Scanning joule expansion microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scanning_joule_expansion_microscopy
date_saved: 2026-05-05T10:06:02.583665+00:00
instance: kb-cron
parent: scanning-joule-expansion-microscopy-20260505-0
summary:
=== Electrostatic force interaction === When a bias is applied to the sample for Joule heating, there is also an electrostatic force interaction between the tip and the sample. The tip-sample electrostatic force can be represented as F = 1 2 d ⁡ C d ⁡ z V 2 {\displaystyle F{=}{\frac {1}{2}}{\operatorname {d} C \over \operatorname {d} z}V^{2}} , in which C is the tip sample capacitance, and V is the voltage, Z is the tip and sample distance. This force also depends on V 2 {\displaystyle V^{2}} , the same as the expansion signal. Usually electrostatic force is small because the sample has been covered with a polymer layer. However, when applied voltage is large, this force needs to be considered. Electrostatic force does not depend on the frequency of the applied AC signal, therefore allowing for a simple method to differentiate and account for this contribution. === Thermal expansion === This is primary mode of signal and the main goal of SJEM. The substrate expands when Joule heated, resulting in change in the measured profile by the cantilever, resulting in a change in signal. However, thermal expansion coefficients can vary significantly. For example, the thermal expansion coefficients of


id: scanning-joule-expansion-microscopy-20260505-2
file: data/en.wikipedia.org/wiki/Scanning_joule_expansion_microscopy-2.md
category: reference
title: Scanning joule expansion microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scanning_joule_expansion_microscopy
date_saved: 2026-05-05T10:06:02.583665+00:00
instance: kb-cron
parent: scanning-joule-expansion-microscopy-20260505-0
summary:
=== Integrated circuit transistors === Understanding thermal properties of transistors are vital for the semiconductor industry as well. Similar to interconnects, repeated thermal stresses can eventually lead to device failure. However, more importantly, electrical behavior, and therefore device parameters change significantly with temperature. SJEM has been used to map local hotspots in thin film transistors. By determining the location of these hotspots, they can be better understood and reduced or eliminated. One disadvantage to this method is that, like AFM, only the surface can be mapped. Consequently, additional processing steps would be required in order to map buried features, such as most features in modern IC transistors. === Nanoscale materials === Nanoscale materials are becoming widely investigated for their many advantages in commercial electronics. In particular, these materials are known for excellent mobility as well as ability to carry high current densities. In addition, new applications have been realized for these materials including thermoelectrics, solar cells, fuel cells, etc. However, significant decrease in size scale in conjunction with increases in current density and device density leads to extreme temperature rises in these devices. These temperature fluctuations can influence electrical behavior and lead to device failure. Therefore, these thermal effects must


id: scanning-transmission-x-ray-microscopy-20260505-0
file: data/en.wikipedia.org/wiki/Scanning_transmission_X-ray_microscopy-0.md
category: reference
title: Scanning transmission X-ray microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scanning_transmission_X-ray_microscopy
date_saved: 2026-05-05T10:06:03.946842+00:00
instance: kb-cron
parent: scanning-transmission-x-ray-microscopy-20260505-0
summary:
Scanning transmission X-ray microscopy (STXM) is a type of X-ray microscopy in which a zone plate focuses an X-ray beam onto a small spot, a sample is scanned in the focal plane of the zone plate and the transmitted X-ray intensity is recorded as a function of the sample position. A stroboscopic scheme is used where the excitation is the pump and the synchrotron X-ray flashes are the probe. X-ray microscopes work by exposing a film or charged coupled device detector to detect X-rays that pass through the specimen. The image formed is of a thin section of specimen. Newer X-ray microscopes use X-ray absorption spectroscopy to heterogeneous materials at high spatial resolution. The essence of the technique is a combination of spectromicroscopy, imaging with spectral sensitivity, and microspectroscopy, recording spectra from very small spots. == Benefits of STXM == === Radiation damage === Electron energy loss spectroscopy (EELS) in combination with transmission electron microscopy has modest spectral resolution and is rather damaging to the sample material. STXM with variable X-ray energy gives high spectral resolution. Radiation damage effects are typically two orders of magnitude lower than for EELS. Radiation concerns are also relevant with organic materials. === Samples with


id: seec-microscopy-20260505-0
file: data/en.wikipedia.org/wiki/SEEC_microscopy-0.md
category: reference
title: SEEC microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/SEEC_microscopy
date_saved: 2026-05-05T10:06:05.131624+00:00
instance: kb-cron
parent: seec-microscopy-20260505-0
summary:
Surface-enhanced ellipsometric contrast microscopy (SEEC) uses an upright or inverted optical microscope in a crossed polarization configuration and specific supporting plates called surfs on which the sample is deposited for observation. It is described as an optical nanoscopy technique. SEEC relies on precise control of the reflection properties of polarized light on a surface, improving the axial sensitivity of an optical microscope by two orders of magnitude without reducing its lateral resolution. Applications could include real-time visualization of films as thin as 0.3 micrometers and isolated nano-objects in air and in water. == Principles == A 2006 study on polarized light coherence led to the development of new supports (the surfs) having contrast amplification properties for standard optical microscopy in cross-polarizer mode. Made of optical layers on an opaque or transparent substrate, these supports do not modify the light polarization after reflection even if the numerical aperture of the incident source is significant. This property is modified when a sample is present on a surf; a non-null light component is then detected after it has been analyzed, rendering the sample visible. The performance of these supports is evaluated by measuring the contrast (C) of the sample defined as: C =


id: single-cell-analysis-20260505-0
file: data/en.wikipedia.org/wiki/Single-cell_analysis-0.md
category: reference
title: Single-cell analysis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Single-cell_analysis
date_saved: 2026-05-05T10:06:06.277163+00:00
instance: kb-cron
parent: single-cell-analysis-20260505-0
summary:
In cell biology, single-cell analysis and subcellular analysis refer to the study of genomics, transcriptomics, proteomics, metabolomics, and cell–cell interactions at the level of an individual cell, as opposed to more conventional methods which study bulk populations of many cells. The concept of single-cell analysis originated in the 1970s. Before the discovery of heterogeneity, single-cell analysis mainly referred to the analysis or manipulation of an individual cell within a bulk population of cells under the influence of a particular condition using optical or electron microscopy. Due to the heterogeneity seen in both eukaryotic and prokaryotic cell populations, analyzing the biochemical processes and features of a single cell makes it possible to discover mechanisms which are too subtle or infrequent to be detectable when studying a bulk population of cells; in conventional multi-cell analysis, this variability is usually masked by the average behavior of the larger population. Technologies such as fluorescence-activated cell sorting allow the precise isolation of selected single cells from complex samples, while high-throughput single-cell partitioning technologies enable the simultaneous molecular analysis of hundreds or thousands of individual unsorted cells; this is particularly useful for the analysis of variations in gene expression between genotypically identical cells, allowing the definition


id: single-cell-analysis-20260505-1
file: data/en.wikipedia.org/wiki/Single-cell_analysis-1.md
category: reference
title: Single-cell analysis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Single-cell_analysis
date_saved: 2026-05-05T10:06:06.277163+00:00
instance: kb-cron
parent: single-cell-analysis-20260505-0
summary:
Controlled priming and PCR amplification: Adapter-Linker PCR WGA Random priming and PCR amplification: DOP-PCR, MALBAC Random priming and isothermal amplification: MDA The Adapter-Linker PCR WGA is reported in many comparative studies to be the best-performing technique for diploid single-cell mutation analysis, thanks to its very low Allelic Dropout effect, and for copy number variation profiling due to its low noise, both with aCGH and with NGS low Pass Sequencing. This method is only applicable to human cells, both fixed and unfixed. One widely adopted WGA technique is called degenerate oligonucleotide–primed polymerase chain reaction (DOP-PCR). This method uses the well established DNA amplification method PCR to try and amplify the entire genome using a large set of primers. Although simple, this method has been shown to have very low genome coverage. An improvement on DOP-PCR is Multiple displacement amplification (MDA), which uses random primers and a high fidelity enzyme, usually Φ29 DNA polymerase, to accomplish the amplification of larger fragments and greater genome coverage than DOP-PCR. Despite these improvements MDA still has a sequence-dependent bias (certain parts of the genome are amplified more than others because of their sequence, causing some parts to be overrepresented in the resulting genomic dataset). The


id: single-cell-analysis-20260505-2
file: data/en.wikipedia.org/wiki/Single-cell_analysis-2.md
category: reference
title: Single-cell analysis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Single-cell_analysis
date_saved: 2026-05-05T10:06:06.277163+00:00
instance: kb-cron
parent: single-cell-analysis-20260505-0
summary:
==== Antibody–based methods ==== The antibody based methods use designed antibodies to bind to proteins of interest, allowing the relative abundance of multiple individual targets to be identified by one of several different techniques. Imaging: Antibodies can be bound to fluorescent molecules such as quantum dots or tagged with organic fluorophores for detection by fluorescence microscopy. Since different colored quantum dots or unique fluorophores are attached to each antibody it is possible to identify multiple different proteins in a single cell. Quantum dots can be washed off of the antibodies without damaging the sample, making it possible to do multiple rounds of protein quantification using this method on the same sample. For the methods based on organic fluorophores, the fluorescent tags are attached by a reversible linkage such as a DNA-hybrid (that can be melted/dissociated under low-salt conditions) or chemically inactivated, allowing multiple cycles of analysis, with 3-5 targets quantified per cycle. These approaches have been used for quantifying protein abundance in patient biopsy samples (e.g. cancer) to map variable protein expression in tissues and/or tumors, and to measure changes in protein expression and cell signaling in response to cancer treatment. Mass Cytometry: rare metal isotopes, not normally found in


id: single-cell-analysis-20260505-3
file: data/en.wikipedia.org/wiki/Single-cell_analysis-3.md
category: reference
title: Single-cell analysis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Single-cell_analysis
date_saved: 2026-05-05T10:06:06.277163+00:00
instance: kb-cron
parent: single-cell-analysis-20260505-0
summary:
====== SIMS ====== Secondary-ion mass spectrometry (SIMS) is a technique similar to DESI, but while DESI is an ambient ionization technique, SIMS happens in vacuum. The solid sample surface is bombarded by a highly focused beam of primary ions. As they hit the surface, molecules are emitted from the surface and ionized. The choice of primary ions determines the size of the beam and also the extent of ionization and fragmentation. Pareek et al. performed metabolomics to trace how purines are synthesized within purinosomes and used isotope labeling and SIMS imaging to directly observe hotspots of metabolic activity within frozen HeLa cells. ====== MALDI ====== In matrix-assisted laser desorption and ionization (MALDI), the sample is incorporated in a chemical matrix that is capable of absorbing energy from a laser. Similar to SIMS, ionization happens in vacuum. Laser irradiation ablates the matrix material from the surface and results in charged gas phase matrix particles, with the analyte molecules ionized from this charged chemical matrix. Liu et al. used MALDI-MS to detect eight phospholipids from single A549 cells. MALDI MS imaging can be used for spatial metabolomics and single-cell analysis. === Purpose === The purpose of studying the proteome is to better


id: single-molecule-fret-20260505-0
file: data/en.wikipedia.org/wiki/Single-molecule_FRET-0.md
category: reference
title: Single-molecule FRET
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Single-molecule_FRET
date_saved: 2026-05-05T10:06:07.449461+00:00
instance: kb-cron
parent: single-molecule-fret-20260505-0
summary:
Single-molecule fluorescence (or Förster) resonance energy transfer (or smFRET) is a biophysical technique used to measure distances at the 1-10 nanometer scale in single molecules, typically biomolecules. It is an application of FRET wherein a pair of donor and acceptor fluorophores are excited and detected at a single molecule level. In contrast to "ensemble FRET" which provides the FRET signal of a high number of molecules, single-molecule FRET is able to resolve the FRET signal of each individual molecule. The variation of the smFRET signal is useful to reveal kinetic information that an ensemble measurement cannot provide, especially when the system is under equilibrium with no ensemble/bulk signal change. Heterogeneity among different molecules can also be observed. This method has been applied in many measurements of intramolecular dynamics such as DNA/RNA/protein folding/unfolding and other conformational changes, and intermolecular dynamics such as reaction, binding, adsorption, and desorption that are particularly useful in chemical sensing, bioassays, and biosensing. == Methodology == Single-molecule FRET measurements are typically performed on fluorescence microscopes, either using surface-immobilized or freely-diffusing molecules. Single FRET pairs are illuminated using intense light sources, typically lasers, in order to generate sufficient fluorescence signals to enable single-molecule detection. Wide-field multiphoton microscopy is


id: single-molecule-fret-20260505-1
file: data/en.wikipedia.org/wiki/Single-molecule_FRET-1.md
category: reference
title: Single-molecule FRET
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Single-molecule_FRET
date_saved: 2026-05-05T10:06:07.449461+00:00
instance: kb-cron
parent: single-molecule-fret-20260505-0
summary:
== Data analysis == Typical smFRET data of a two-dye system are time trajectories of the fluorescent emission intensities of the donor dye and the acceptor dye, called the two channels. Mainly two methods are used to obtain the emission of the two dyes: (1) accumulative measurement uses a fixed exposure time of the cameras for each frame, such as PMT, APD, EMCCD, and CMOS camera; (2) single-photon arriving time sequence measured using PMT or APD detectors. The principle is to use optical filters or dichroic mirrors to separate the emissions of the two dyes and measure them in two channels. For example, a setup using two halves of a charge-coupled device (CCD) camera is explained in the literature. For a two-dye system, the emission signals are then used to calculate the FRET efficiency between the dyes over time. The FRET efficiency is the number of photons emitted from the acceptor dye over the sum of the emissions of the donor and the acceptor dye. The time trajectories produced in every experiment may contain signals from incomplete or incorrect labeling or even aggregates. To account for this multiple research groups have developed sophisticated tools for the time trace selection based


id: single-molecule-fret-20260505-2
file: data/en.wikipedia.org/wiki/Single-molecule_FRET-2.md
category: reference
title: Single-molecule FRET
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Single-molecule_FRET
date_saved: 2026-05-05T10:06:07.449461+00:00
instance: kb-cron
parent: single-molecule-fret-20260505-0
summary:
The camera blurring signal comes from the discrete nature of the measurements. The emission signal has a mismatch with the real transition signal because one or both are stochastic (random). When a state transition happens between the readout of two emission reading intervals, the signal is the average of the two parts in the same measuring window, which then affects the state identification accuracy and eventually the rate constant analysis. This is less of a problem when the measuring frequency is much faster than the transition rate but becomes a real problem when they approach each other (figure on the right). In order to reflect the camera blurring effect in the simulated smFRET trajectories, one must simulate the data in a higher time resolution (e.g. 10 times faster) than the data collection time and then bin the data into the final trajectories. See GitHub (postFRET) for an example MATLAB codes to simulate smFRET time trajectories with a faster time resolution then bin it to the measuring time resolution (integration time) to simulate the camera blurring effect. === Photoblinking and photobleaching === The time trajectories also contain the photoblinking and photobleaching information of the two dyes. This information has to be


id: single-molecule-fret-20260505-3
file: data/en.wikipedia.org/wiki/Single-molecule_FRET-3.md
category: reference
title: Single-molecule FRET
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Single-molecule_FRET
date_saved: 2026-05-05T10:06:07.449461+00:00
instance: kb-cron
parent: single-molecule-fret-20260505-0
summary:
where i is the initial state, f is the final state of the transition, N is the number of these transitions in the time trajectories, n is the total number of states, k is the rate constant, t is the time of each state before the transition happens. For example, one measures 130 seconds (s) of smFRET time trajectories. The total time of a molecule stays on state one is t1 = 100 second (s), state two t2 = 20 s, and state three is t3 = 10 s. Among the 100 s the molecule stays state one, it transfers to state two 70 times and transfers to state three 30 times at the end of its dwell times, the rate constant of state 1 to state 2 is thus k12 = 70/100 = 0.7 s−1, the rate constant of state 1 to state 3 is k13 = 30/100 = 0.3 s−1. Typically the probabilities of the lengths of the 70 times or the 30 times transition (dwell times) are exponentially distributed (right figure). The average dwell times of the two distributions of state one, i.e. the two lifetimes, τ12 and τ13, are both the same at 1 s for


id: single-molecule-fret-20260505-4
file: data/en.wikipedia.org/wiki/Single-molecule_FRET-4.md
category: reference
title: Single-molecule FRET
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Single-molecule_FRET
date_saved: 2026-05-05T10:06:07.449461+00:00
instance: kb-cron
parent: single-molecule-fret-20260505-0
summary:
SmFRET allows for a more precise analysis of heterogeneous populations and has a few advantages when compared to ensemble FRET. One benefit of studying distances in single molecules is that heterogeneous populations can be studied more accurately with values specific for each molecule rather than computing an average based on an ensemble. This allows for the study of specific homogeneous populations within a heterogeneous population. For example, if two existing homologous populations within a heterogeneous population have different FRET values, an ensemble FRET analysis will produce a weighted averaged FRET value to represent the population as a whole. Thus, the obtained FRET value does not produce data on the two distinct populations. In contrast, smFRET would be able to differentiate between the two populations and would allow an analysis of the existing homologous populations. SmFRET also provides dynamic temporal resolution of an individual molecule that cannot be accomplished through ensemble FRET measurements. Ensemble FRET has the ability to detect well-populated transition states that accumulate in a population, but it lacks the ability to characterize intermediates that are short-lived and do not accumulate. This limit is addressed by smFRET which offers a direct way to observe the intermediates of single molecules


id: single-molecule-fret-20260505-5
file: data/en.wikipedia.org/wiki/Single-molecule_FRET-5.md
category: reference
title: Single-molecule FRET
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Single-molecule_FRET
date_saved: 2026-05-05T10:06:07.449461+00:00
instance: kb-cron
parent: single-molecule-fret-20260505-0
summary:
== Applications == A major application of smFRET is to analyze the minute biochemical nuances that facilitate protein folding. In recent years, multiple techniques have been developed to investigate single-molecule interactions that are involved in protein folding and unfolding. Force-probe techniques, using atomic force microscopy and laser tweezers, have provided information on protein stability. smFRET allows researchers to investigate molecular interactions using fluorescence. Forster resonance energy transfer (FRET) was first applied to single molecules by Ha et al. and applied to protein folding in work by Hochstrasser, Weiss, et al. The benefit that smFRET as a whole has afforded to analyze molecular interactions is the ability to test single molecule interactions directly without having to average ensembles of data. In protein folding analysis, ensemble experiments involve taking measurements of multiple proteins that are in various states of transition between their folded and unfolded state. When averaged, the protein structure that can be inferred from the ensemble of data only provides a rudimentary structural model of protein folding. However, a true understanding of protein folding requires deciphering the sequence of structural events along the folding pathways between the folded and unfolded states. It is this particular branch of research that smFRET


id: single-molecule-fret-20260505-6
file: data/en.wikipedia.org/wiki/Single-molecule_FRET-6.md
category: reference
title: Single-molecule FRET
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Single-molecule_FRET
date_saved: 2026-05-05T10:06:07.449461+00:00
instance: kb-cron
parent: single-molecule-fret-20260505-0
summary:
== Limitations == Despite making approximate estimates, a limitation of smFRET is the difficulty of obtaining the correct distance involved in energy transfer. Requiring an accurate distance estimate gives rise to a major challenge because the fluorescence of the donor and acceptor fluorophores, as well as the energy transfer, is dependent on the environment and how the dyes are oriented, which can vary depending on the flexibility of where the fluorophores are bound. In addition, the actual distance of a given state can be dynamic and the measured value represents the average distance within the collection time frame. This issue, however, is not particularly relevant when the distance estimation of the two fluorophores does not need to be determined with exact and absolute precision. Extracting kinetic information from a complicated biological system with a transition rate of around a few milliseconds or below remains challenging. The current time resolutions of such measurements are typically at the millisecond level with a few reports at the microsecond level. There is a theoretical limitation to dye photophysics. The lifetime of the excited state of a typical organic dye molecule is about 1 nanosecond. In order to obtain statistical confidence of the FRET values,


id: solid-state-nuclear-magnetic-resonance-20260505-0
file: data/en.wikipedia.org/wiki/Solid-state_nuclear_magnetic_resonance-0.md
category: reference
title: Solid-state nuclear magnetic resonance
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Solid-state_nuclear_magnetic_resonance
date_saved: 2026-05-05T10:06:08.691434+00:00
instance: kb-cron
parent: solid-state-nuclear-magnetic-resonance-20260505-0
summary:
Solid-state nuclear magnetic resonance (ssNMR) is a spectroscopy technique used to characterize atomic-level structure and dynamics in solid materials. ssNMR spectra are broader due to nuclear spin interactions which can be categorized as dipolar coupling, chemical shielding, quadrupolar interactions, and j-coupling. These interactions directly affect the lines shapes of experimental ssNMR spectra which can be seen in powder and dipolar patterns. There are many essential solid-state techniques alongside advanced ssNMR techniques that may be applied to elucidate the fundamental aspects of solid materials. ssNMR is often combined with magic angle spinning (MAS) to remove anisotropic interactions and improve the sensitivity of the technique. The applications of ssNMR further extend to biology and medicine. == Nuclear spin interactions == The resonance frequency of a nuclear spin depends on the strength of the magnetic field at the nucleus, which can be modified by isotropic (e.g. chemical shift, isotropic J-coupling) and anisotropic interactions (e.g. chemical shift anisotropy, dipolar interactions). In a classical liquid-state NMR experiment, molecular tumbling coming from Brownian motion averages anisotropic interactions to zero and they are therefore not reflected in the NMR spectrum. However, in media with no or little mobility (e.g. crystalline powders, glasses, large membrane vesicles, molecular aggregates),


id: solid-state-nuclear-magnetic-resonance-20260505-1
file: data/en.wikipedia.org/wiki/Solid-state_nuclear_magnetic_resonance-1.md
category: reference
title: Solid-state nuclear magnetic resonance
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Solid-state_nuclear_magnetic_resonance
date_saved: 2026-05-05T10:06:08.691434+00:00
instance: kb-cron
parent: solid-state-nuclear-magnetic-resonance-20260505-0
summary:
A powder pattern arises in powdered samples where crystallites are randomly oriented relative to the magnetic field so that all molecular orientations are present. In presence of a chemical shift anisotropy interaction, each orientation with respect to the magnetic field gives a different resonance frequency. If enough crystallites are present, all the different contributions overlap continuously and lead to a smooth spectrum. Fitting of the pattern in a static ssNMR experiment gives information about the shielding tensor, which are often described by the isotropic chemical shift δ i s o {\displaystyle \delta _{iso}} , the chemical shift anisotropy parameter Δ C S {\displaystyle \Delta _{CS}} , and the asymmetry parameter η {\displaystyle \eta } . === Dipolar pattern === The dipolar powder pattern (also Pake pattern) has a very characteristic shape that arises when two nuclear spins are coupled together within a crystallite. The splitting between the maxima (the "horns") of the pattern is equal to the dipolar coupling constant d {\displaystyle d} .: d = ℏ ( μ 0 4 π ) 1 r 3 γ 1 γ 2 {\displaystyle d=\hbar \left({\frac {\mu _{0}}{4\pi }}\right){\frac {1}{r^{3}}}\gamma _{1}\gamma _{2}} where γ1 and γ2 are the gyromagnetic ratios of the dipolar-coupled


id: solid-state-nuclear-magnetic-resonance-20260505-2
file: data/en.wikipedia.org/wiki/Solid-state_nuclear_magnetic_resonance-2.md
category: reference
title: Solid-state nuclear magnetic resonance
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Solid-state_nuclear_magnetic_resonance
date_saved: 2026-05-05T10:06:08.691434+00:00
instance: kb-cron
parent: solid-state-nuclear-magnetic-resonance-20260505-0
summary:
ξ ∝ ( γ H γ X ) 3 / 2 ( W X W H ) 1 / 2 ( Q H Q X ) 1 / 2 {\displaystyle \xi \propto \left({\frac {\gamma _{H}}{\gamma _{X}}}\right)^{3/2}\left({\frac {W_{X}}{W_{H}}}\right)^{1/2}\left({\frac {Q_{H}}{Q_{X}}}\right)^{1/2}} where γ {\displaystyle \gamma } are the gyromagnetic ratios, W {\displaystyle W} represent the NMR line widths, and Q {\displaystyle Q} represent the quality factor of the probe resonances. === MAS-Dynamic Nuclear Polarisation (MAS-DNP) === Magic angle spinning dynamic nuclear polarization (MAS-DNP) is a technique that increases the sensitivity of NMR experiments by several orders of magnitude. It involves transferring the very high electron polarisation from unpaired electrons to nearby nuclei. This is achieved at cryogenic temperatures through a continuous microwave irradiation from a klystron or a gyrotron, with a frequency close to the corresponding electron paramagnetic resonance (EPR) frequency. The development in the MAS-DNP instrumentation, and the improvement of polarising agents (TOTAPOL, AMUPOL, TEKPOL, etc. ) to achieve a more efficient transfer of polarisation has dramatically reduced experiments times which enabled the observation of surfaces, insensitive isotopes, and multidimensional experiments on low natural abundance nuclei, and diluted species. === Beta-Detected Nuclear Magnetic Resonance (β-NMR) === Beta-detected nuclear magnetic resonance (β-NMR) is


id: spectroscopy-20260505-0
file: data/en.wikipedia.org/wiki/Spectroscopy-0.md
category: reference
title: Spectroscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Spectroscopy
date_saved: 2026-05-05T10:06:09.862940+00:00
instance: kb-cron
parent: spectroscopy-20260505-0
summary:
Spectroscopy is the field of study that measures and interprets electromagnetic spectra as it interacts with matter. In narrower contexts, spectroscopy is the precise study of color as generalized from radiated visible light to all bands of the electromagnetic spectrum. Spectroscopy, primarily in the electromagnetic spectrum, is a fundamental exploratory tool in the fields of astronomy, chemistry, materials science, and physics, allowing the composition, physical and electronic structure of matter to be investigated at the atomic, molecular and macro scale, and over astronomical distances. Historically, spectroscopy originated as the study of the wavelength dependence of the absorption by gas phase matter of visible light dispersed by a prism. Current applications of spectroscopy include biomedical spectroscopy in the areas of tissue analysis and medical imaging. Matter waves and acoustic waves can be considered forms of radiative energy, and recently gravitational waves have been associated with a spectral signature in the context of the Laser Interferometer Gravitational-Wave Observatory (LIGO). == Introduction == Spectroscopy is a branch of science concerned with the spectra of electromagnetic radiation as a function of its wavelength or frequency, as measured by spectrographic equipment and other techniques, in order to obtain information concerning the structure and properties of


id: spectroscopy-20260505-1
file: data/en.wikipedia.org/wiki/Spectroscopy-1.md
category: reference
title: Spectroscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Spectroscopy
date_saved: 2026-05-05T10:06:09.862940+00:00
instance: kb-cron
parent: spectroscopy-20260505-0
summary:
where I 0 {\displaystyle I_{0}} is the light intensity before passing through the sample, I {\displaystyle I} is the output intensity, ε {\displaystyle \varepsilon } is the extinction coefficient, ℓ {\displaystyle \ell } is the path length through the sample, and c {\displaystyle c} is the concentration of the sample. The extinction coefficient depends on the wavelength selected and the molecule being sampled. Resonances by the frequency were first characterized in mechanical systems such as pendulums, which have a frequency of motion noted famously by Galileo. In quantum mechanical systems, the analogous resonance is a coupling of two quantum mechanical stationary states of a system, such as two atomic orbitals, via an oscillatory source of energy such as a photon. The coupling of the two states is strongest when the source energy matches the energy difference between the two states. That is, a photon at the right energy is more likely to cause an electron to jump between two orbitals, a process called electron excitation. The energy E of a photon is related to its frequency ν by E = hν where h is the Planck constant, and so a spectrum of the system response vs. photon frequency will peak


id: spectroscopy-20260505-2
file: data/en.wikipedia.org/wiki/Spectroscopy-2.md
category: reference
title: Spectroscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Spectroscopy
date_saved: 2026-05-05T10:06:09.862940+00:00
instance: kb-cron
parent: spectroscopy-20260505-0
summary:
Atomic spectroscopy was the first application of spectroscopy. Atomic absorption spectroscopy and atomic emission spectroscopy involve visible and ultraviolet light. These absorptions and emissions, often referred to as atomic spectral lines, are due to electronic transitions of outer shell electrons as they rise and fall from one electron orbit to another. Atoms have distinct X-ray spectra that are attributable to the excitation of inner shell electrons to excited states. Atoms of different elements have distinct spectra and therefore atomic spectroscopy allows for the identification and quantitation of a sample's elemental composition. After Robert Bunsen and Gustav Kirchhoff invented the spectroscope, Bunsen discovered cesium and rubidium by observing their emission spectra. Atomic absorption lines are observed in the solar spectrum and referred to as Fraunhofer lines after their discoverer. A comprehensive explanation of the hydrogen spectrum was an early success of quantum mechanics and explained the Lamb shift observed in the hydrogen spectrum, which further led to the development of quantum electrodynamics. Modern implementations of atomic spectroscopy for studying visible and ultraviolet transitions include flame emission spectroscopy, inductively coupled plasma atomic emission spectroscopy, glow discharge spectroscopy, microwave induced plasma spectroscopy, and spark or arc emission spectroscopy. Techniques for studying X-ray spectra


id: spectroscopy-20260505-3
file: data/en.wikipedia.org/wiki/Spectroscopy-3.md
category: reference
title: Spectroscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Spectroscopy
date_saved: 2026-05-05T10:06:09.862940+00:00
instance: kb-cron
parent: spectroscopy-20260505-0
summary:
Acoustic resonance spectroscopy is based on sound waves primarily in the audible and ultrasonic regions. Auger electron spectroscopy is a method used to study surfaces of materials on a micro-scale. It is often used in connection with electron microscopy. Cavity ring-down spectroscopy enables measurement of absolute optical extinction by samples that scatter and absorb light. Circular dichroism spectroscopy measures the differential absorption of left- and right-handed circularly polarized light. Coherent anti-Stokes Raman spectroscopy is a recent technique that has high sensitivity and powerful applications for in vivo spectroscopy and imaging. Cold vapour atomic fluorescence spectroscopy is a subclass of the atomic emission spectroscopy technique that measures trace amounts of volatile heavy metals in the air, such as mercury. Correlation spectroscopy encompasses several types of two-dimensional NMR spectroscopy. Deep-level transient spectroscopy measures concentration and analyzes parameters of electrically active defects in semiconducting materials. Dielectric spectroscopy measures the dielectric properties of a medium as a function of frequency. Dual-polarization interferometry measures the real and imaginary components of the complex refractive index. Electron energy loss spectroscopy in transmission electron microscopy. Electron phenomenological spectroscopy measures the physicochemical properties and characteristics of the electronic structure of multicomponent and complex molecular systems. Electron paramagnetic resonance spectroscopy


id: spectroscopy-20260505-4
file: data/en.wikipedia.org/wiki/Spectroscopy-4.md
category: reference
title: Spectroscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Spectroscopy
date_saved: 2026-05-05T10:06:09.862940+00:00
instance: kb-cron
parent: spectroscopy-20260505-0
summary:
Determining the atomic structure of a sample Studying spectral emission lines of the sun and distant galaxies Space exploration Cure monitoring of composites using optical fibers. Estimating weathered wood exposure times using near infrared spectroscopy Measurement of different compounds in food samples by absorption spectroscopy both in visible and infrared spectrum Measurement of toxic compounds in blood samples Non-destructive elemental analysis by X-ray fluorescence Electronic structure research with various spectroscopes Redshift to determine the speed and velocity of a distant object Determining the metabolic structure of a muscle Monitoring dissolved oxygen content in freshwater and marine ecosystems Altering the structure of drugs to improve effectiveness Characterization of proteins Respiratory gas analysis in hospitals Finding the physical properties of a distant star or nearby exoplanet using the Relativistic Doppler effect. In-ovo sexing: spectroscopy allows to determine the sex of the egg while it is hatching. Developed by French and German companies, both countries decided to ban chick culling, mostly done through a macerator, in 2022. Process monitoring in Industrial process control == History == The history of spectroscopy began with Isaac Newton's optics experiments (1666–1672). According to Andrew Fraknoi and David Morrison, "In 1672, in the first paper that he submitted


id: spin-echo-20260505-0
file: data/en.wikipedia.org/wiki/Spin_echo-0.md
category: reference
title: Spin echo
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Spin_echo
date_saved: 2026-05-05T10:06:10.999636+00:00
instance: kb-cron
parent: spin-echo-20260505-0
summary:
In magnetic resonance, a spin echo or Hahn echo is the refocusing of spin magnetisation by a pulse of resonant electromagnetic radiation. Modern nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) make use of this effect. The NMR signal observed following an initial excitation pulse decays with time due to both spin relaxation and any inhomogeneous effects which cause spins in the sample to precess at different rates. The first of these, relaxation, leads to an irreversible loss of magnetisation. But the inhomogeneous dephasing can be removed by applying a 180° inversion pulse that inverts the magnetisation vectors. Examples of inhomogeneous effects include a magnetic field gradient and a distribution of chemical shifts. If the inversion pulse is applied after a period t of dephasing, the inhomogeneous evolution will rephase to form an echo at time 2t. In simple cases, the intensity of the echo relative to the initial signal is given by e–2t/T2 where T2 is the time constant for spin–spin relaxation. The echo time (TE) is the time between the excitation pulse and the peak of the signal. Echo phenomena are important features of coherent spectroscopy which have been used in fields other than magnetic resonance including


id: spin-echo-small-angle-neutron-scattering-20260505-0
file: data/en.wikipedia.org/wiki/Spin_echo_small_angle_neutron_scattering-0.md
category: reference
title: Spin echo small angle neutron scattering
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Spin_echo_small_angle_neutron_scattering
date_saved: 2026-05-05T10:06:12.163464+00:00
instance: kb-cron
parent: spin-echo-small-angle-neutron-scattering-20260505-0
summary:
Spin echo small angle neutron scattering (SESANS) measures structures from around 20 to 2000 nm in size. The information is presented as a real-space (similar to g(r)) as opposed to a reciprocal space (q(r)) mapping. This can simplify the interpretation for some systems. SESANS is useful for studying processes that occur over relatively long time scales, as data collection is often slow, but large length scales. Aggregation of colloids, block copolymer micelles, Stöber silica particles being a prime examples. The technique offers some advantages over SANS but there are fewer SESANS instruments available than SANS instruments. Facilities for SESANS exist at TUDelft (Netherlands) and Rutherford Appleton Laboratory (UK). == References ==


id: spin-polarized-electron-energy-loss-spectroscopy-20260505-0
file: data/en.wikipedia.org/wiki/Spin-polarized_electron_energy_loss_spectroscopy-0.md
category: reference
title: Spin-polarized electron energy loss spectroscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Spin-polarized_electron_energy_loss_spectroscopy
date_saved: 2026-05-05T10:06:13.330154+00:00
instance: kb-cron
parent: spin-polarized-electron-energy-loss-spectroscopy-20260505-0
summary:
Spin-polarized electron energy loss spectroscopy or SPEELS is a technique mainly used to measure the dispersion relation of the collective excitations, over the whole Brillouin zone. Spin waves are collective perturbations in a magnetic solid. Their properties depend on their wavelength (or wave vector). For long wavelength (short wave vector) spin waves, the resulting spin precession has a very low frequency and the spin waves can be treated classically. Ferromagnetic resonance (FMR) and Brillouin light scattering (BLS) experiments explain the long wavelength spin waves in ultrathin magnetic films and nanostructures. If the wavelength is comparable to the lattice constant, the spin waves are governed by the microscopic exchange coupling and a quantum mechanical description is needed. Therefore, experimental information on these short wavelength (large wave vector) spin waves in ultrathin films is highly desired and may lead to fundamentally new insights into the spin dynamics in reduced dimensions in the future. SPEELS is one of the few techniques that can be used to measure the dispersion of such short wavelength spin waves in ultrathin films and nanostructures. == The first experiment == For the first time Kirschner's group in Max Planck institute of Microstructure Physics showed that the signature of


id: staining-20260505-0
file: data/en.wikipedia.org/wiki/Staining-0.md
category: reference
title: Staining
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Staining
date_saved: 2026-05-05T10:06:14.460722+00:00
instance: kb-cron
parent: staining-20260505-0
summary:
Staining is a technique used to enhance contrast in samples, generally at the microscopic level. Stains and dyes are frequently used in histology (microscopic study of biological tissues), in cytology (microscopic study of cells), and in the medical fields of histopathology, hematology, and cytopathology that focus on the study and diagnoses of diseases at the microscopic level. Stains may be used to define biological tissues (highlighting, for example, muscle fibers or connective tissue), cell populations (classifying different blood cells), or organelles within individual cells. In biochemistry, it involves adding a class-specific (DNA, proteins, lipids, carbohydrates) dye to a substrate to qualify or quantify the presence of a specific compound. Staining and fluorescent tagging can serve similar purposes. Biological staining is also used to mark cells in flow cytometry, and to flag proteins or nucleic acids in gel electrophoresis. Light microscopes are used for viewing stained samples at high magnification, typically using bright-field or epi-fluorescence illumination. Staining is not limited to only biological materials, since it can also be used to study the structure of other materials; for example, the lamellar structures of semi-crystalline polymers or the domain structures of block copolymers. == In vivo vs In vitro == In vivo


id: staining-20260505-1
file: data/en.wikipedia.org/wiki/Staining-1.md
category: reference
title: Staining
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Staining
date_saved: 2026-05-05T10:06:14.460722+00:00
instance: kb-cron
parent: staining-20260505-0
summary:
=== Negative staining === A simple staining method for bacteria that is usually successful, even when the positive staining methods fail, is to use a negative stain. This can be achieved by smearing the sample onto the slide and then applying nigrosin (a black synthetic dye) or India ink (an aqueous suspension of carbon particles). After drying, the microorganisms may be viewed in bright field microscopy as lighter inclusions well-contrasted against the dark environment surrounding them. Negative staining is able to stain the background instead of the organisms because the cell wall of microorganisms typically has a negative charge which repels the negatively charged stain. The dyes used in negative staining are acidic. Note: negative staining is a mild technique that may not destroy the microorganisms, and is therefore unsuitable for studying pathogens. === Positive staining === Unlike negative staining, positive staining uses basic dyes to color the specimen against a bright background. While chromophore is used for both negative and positive staining alike, the type of chromophore used in this technique is a positively charged ion instead of a negative one. The negatively charged cell wall of many microorganisms attracts the positively charged chromophore which causes the specimen to


id: staining-20260505-2
file: data/en.wikipedia.org/wiki/Staining-2.md
category: reference
title: Staining
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Staining
date_saved: 2026-05-05T10:06:14.460722+00:00
instance: kb-cron
parent: staining-20260505-0
summary:
Papanicolaou staining, or PAP staining, was developed to replace fine needle aspiration cytology (FNAC) in hopes of decreasing staining times and cost without compromising quality. This stain is a frequently used method for examining cell samples from a variety of tissue types in various organs. PAP staining has endured several modifications in order to become a “suitable alternative” for FNAC. This transition stemmed from the appreciation of wet fixed smears by scientists preserving the structures of the nuclei opposed to the opaque appearance of air dried Romanowsky smears. This led to the creation of a hybrid stain of wet fixed and air dried known as the ultrafast papanicolaou stain. This modification includes the use of nasal saline to rehydrate cells to increase cell transparency and is paired with the use of alcoholic formalin to enhance colors of the nuclei. The papanicolaou stain is now used in place of cytological staining in all organ types due to its increase in morphological quality, decreased staining time, and decreased cost. It is frequently used to stain Pap smear specimens. It uses a combination of haematoxylin, Orange G, eosin Y, Light Green SF yellowish, and sometimes Bismarck Brown Y. === PAS === Periodic acid-Schiff


id: staining-20260505-3
file: data/en.wikipedia.org/wiki/Staining-3.md
category: reference
title: Staining
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Staining
date_saved: 2026-05-05T10:06:14.460722+00:00
instance: kb-cron
parent: staining-20260505-0
summary:
=== Acridine orange === Acridine orange (AO) is a nucleic acid selective fluorescent cationic dye useful for cell cycle determination. It is cell-permeable, and interacts with DNA and RNA by intercalation or electrostatic attractions. When bound to DNA, it is very similar spectrally to fluorescein. Like fluorescein, it is also useful as a non-specific stain for backlighting conventionally stained cells on the surface of a solid sample of tissue (fluorescence backlighted staining). === Bismarck brown === Bismarck brown (also Bismarck brown Y or Manchester brown) imparts a yellow colour to acid mucins and an intense brown color to mast cells. One default of this stain is that it blots out any other structure surrounding it and makes the quality of the contrast low. It has to be paired with other stains in order to be useful. Some complementing stains used alongside Bismark brown are Hematoxylin and Toluidine blue which provide better contrast within the histology sample. === Carmine === Carmine is an intensely red dye used to stain glycogen, while Carmine alum is a nuclear stain. Carmine stains require the use of a mordant, usually aluminum. === Coomassie blue === Coomassie brilliant blue nonspecifically stains proteins a strong blue colour.


id: staining-20260505-4
file: data/en.wikipedia.org/wiki/Staining-4.md
category: reference
title: Staining
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Staining
date_saved: 2026-05-05T10:06:14.460722+00:00
instance: kb-cron
parent: staining-20260505-0
summary:
=== Methyl green === Methyl green is used commonly with bright-field, as well as fluorescence microscopes to dye the chromatin of cells so that they are more easily viewed. === Methylene blue === Methylene blue is used to stain animal cells, such as human cheek cells, to make their nuclei more observable. Also used to stain blood films in cytology. === Neutral red === Neutral red (or toluylene red) stains Nissl substance red. It is usually used as a counterstain in combination with other dyes. === Nile blue === Nile blue (or Nile blue A) stains nuclei blue. It may be used with living cells. === Nile red === Nile red (also known as Nile blue oxazone) is formed by boiling Nile blue with sulfuric acid. This produces a mix of Nile red and Nile blue. Nile red is a lipophilic stain; it will accumulate in lipid globules inside cells, staining them red. Nile red can be used with living cells. It fluoresces strongly when partitioned into lipids, but practically not at all in aqueous solution. === Osmium tetroxide (formal name: osmium tetraoxide) === Osmium tetraoxide is used in optical microscopy to stain lipids. It dissolves in fats, and is


id: thermally-stimulated-depolarization-current-20260505-0
file: data/en.wikipedia.org/wiki/Thermally_stimulated_depolarization_current-0.md
category: reference
title: Thermally stimulated depolarization current
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Thermally_stimulated_depolarization_current
date_saved: 2026-05-05T10:06:15.643505+00:00
instance: kb-cron
parent: thermally-stimulated-depolarization-current-20260505-0
summary:
Thermally stimulated depolarization current (TSDC) is a scientific technique used to measure dielectric properties of materials. It can be used to measure the thermally stimulated depolarization of molecules within a material. One method of doing so is to place the material between two electrodes, cool the material in the presence of an external electric field, remove the field once a desired temperature has been reached, and measure the current between the electrodes as the material warms. The external electric field must be applied at a sufficiently high temperature to allow the molecular dipoles time to align with the field. Because the dielectric relaxation time increases exponentially on cooling, the polarization caused by their alignment with the field gets "frozen-in". So when the field is removed and the material begins to warm the dipoles begin to "thaw" whereby losing their net alignment and thus the material become depolarized. This depolarization can be measured if the material is sandwiched between two ohmic electrodes and the current is measured on warming. As the material depolarizes, charges are pulled to (or pushed away from) the electrodes which causes a current through the measuring device. == References ==


id: thermomechanical-analysis-20260505-0
file: data/en.wikipedia.org/wiki/Thermomechanical_analysis-0.md
category: reference
title: Thermomechanical analysis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Thermomechanical_analysis
date_saved: 2026-05-05T10:06:16.802929+00:00
instance: kb-cron
parent: thermomechanical-analysis-20260505-0
summary:
Thermomechanical analysis (TMA) is a technique used in thermal analysis, a branch of materials science which studies the properties of materials as they change with temperature. Thermomechanical analysis is a subdiscipline of the thermomechanometry (TM) technique. == Related techniques and terminology == Thermomechanometry is the measurement of a change of a dimension or a mechanical property of the sample while it is subjected to a temperature regime. An associated thermoanalytical method is thermomechanical analysis. A special related technique is thermodilatometry (TD), the measurement of a change of a dimension of the sample with a negligible force acting on the sample while it is subjected to a temperature regime. The associated thermoanalytical method is thermodilatometric analysis (TDA). TDA is often referred to as zero force TMA. The temperature regime may be heating, cooling at a rate of temperature change that can include stepwise temperature changes, linear rate of change, temperature modulation with a set frequency and amplitude, free (uncontrolled) heating or cooling, or maintaining a constant increase in temperature. The sequence of temperatures with respect to time may be predetermined (temperature programmed) or sample controlled (controlled by a feedback signal from the sample response). Thermomechanometry includes several variations according to the


id: thermomechanical-analysis-20260505-1
file: data/en.wikipedia.org/wiki/Thermomechanical_analysis-1.md
category: reference
title: Thermomechanical analysis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Thermomechanical_analysis
date_saved: 2026-05-05T10:06:16.802929+00:00
instance: kb-cron
parent: thermomechanical-analysis-20260505-0
summary:
==== Cross-linking ==== Cross-linking will restrict the molecular response to temperature change since degree of freedom for segmental motions are reduced as molecules become irreversibly linked. Cross-linking chemically links molecules, while crystallinity and fillers introduce physical constraints to motion. Mechanical properties such as derived from stress-strain testing are used to calculate crosslink density that is usually expressed as the molar mass between crosslinks (Mc). The sensitivity of zero stress TMA to crosslinking is low since the structure receives minimum disturbance. Sensitivity to crosslinks requires high strain such that the segments between crosslinks become fully extended. Zero force TM will only be sensitive to changes in the bulk that are expressed as a change in a linear dimension of the material. The measured change will be the resultant of all processes occurring as the temperature is changed. Some of the processes will be reversible, others irreversible, and others time-dependent. The methodology must be chosen to best detect, distinguish and resolve the thermal expansion or contractions observable. The TM instrument need only apply sufficient stress to keep the probe in contact with the specimen surface, but it must have high sensitivity to dimensional change. The experiment must be conducted at a temperature


id: thermomechanical-analysis-20260505-2
file: data/en.wikipedia.org/wiki/Thermomechanical_analysis-2.md
category: reference
title: Thermomechanical analysis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Thermomechanical_analysis
date_saved: 2026-05-05T10:06:16.802929+00:00
instance: kb-cron
parent: thermomechanical-analysis-20260505-0
summary:
== Static force thermomechanometry experimental == Creep and stress relaxation measures the elasticity, viscoelasticity and viscous behaviour of materials under a selected stress and temperature. Tensile geometry is the most common for creep measurements. A small force is initially imparted to keep the specimen aligned and straight. The selected stress is applied rapidly and held constant for the required time; this may be 1 h or more. During application of force the elastic property is observed as an immediate elongation or strain. During the constant force period the time dependent elastic response or viscoelasticity, together with the viscous response, result in further increase in strain. The force is removed rapidly, though the small alignment force is maintained. The recovery measurement time should be four times the creep time, so in this example the recovery time should be 4 h. Upon removal of the force the elastic component results in an immediate contraction. The viscoelastic recovery is exponential as the material slowly recovers some of the previously imparted creep strain. After recovery there is a permanent unrecovered strain due to the viscous component of the properties. Analysis of the data is performed using the four component viscoelastic model where the elements


id: time-resolved-mass-spectrometry-20260505-0
file: data/en.wikipedia.org/wiki/Time-resolved_mass_spectrometry-0.md
category: reference
title: Time-resolved mass spectrometry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Time-resolved_mass_spectrometry
date_saved: 2026-05-05T10:06:34.290244+00:00
instance: kb-cron
parent: time-resolved-mass-spectrometry-20260505-0
summary:
Time-resolved mass spectrometry (TRMS) is a strategy in analytical chemistry that uses mass spectrometry platform to collect data with temporal resolution. Implementation of TRMS builds on the ability of mass spectrometers to process ions within sub-second duty cycles. It often requires the use of customized experimental setups. However, they can normally incorporate commercial mass spectrometers. As a concept in analytical chemistry, TRMS encompasses instrumental developments (e.g. interfaces, ion sources, mass analyzers), methodological developments, and applications. == Applications == An early application of TRMS was in the observation of flash photolysis process. It took advantage of a time-of-flight mass analyzer. TRMS currently finds applications in the monitoring of organic reactions, formation of reactive intermediates, enzyme-catalyzed reactions, convection, protein folding, extraction, and other chemical and physical processes. == Temporal resolution == TRMS is typically implemented to monitor processes that occur on second to millisecond time scale. However, there exist reports from studies in which sub-millisecond resolutions were achieved. == References ==


id: total-internal-reflection-fluorescence-microscope-20260505-0
file: data/en.wikipedia.org/wiki/Total_internal_reflection_fluorescence_microscope-0.md
category: reference
title: Total internal reflection fluorescence microscope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Total_internal_reflection_fluorescence_microscope
date_saved: 2026-05-05T10:06:35.424390+00:00
instance: kb-cron
parent: total-internal-reflection-fluorescence-microscope-20260505-0
summary:
A total internal reflection fluorescence microscope (TIRFM) is a type of microscope with which a thin region of a specimen, usually less than 200 nanometers can be observed. TIRFM is an imaging modality which uses the excitation of fluorescent cells in a thin optical specimen section that is supported on a glass slide. The technique is based on the principle that when excitation light is totally internally reflected in a transparent solid coverglass at its interface with a liquid medium, an electromagnetic field, also known as an evanescent wave, is generated at the solid-liquid interface with the same frequency as the excitation light. The intensity of the evanescent wave exponentially decays with distance from the surface of the solid so that only fluorescent molecules within a few hundred nanometers of the solid are efficiently excited. Two-dimensional images of the fluorescence can then be obtained, although there are also mechanisms in which three-dimensional information on the location of vesicles or structures in cells can be obtained. == History == Widefield fluorescence was introduced in 1910 which was an optical technique that illuminates the entire sample. Confocal microscopy was then introduced in 1960 which decreased the background and exposure time of the


id: total-internal-reflection-fluorescence-microscope-20260505-1
file: data/en.wikipedia.org/wiki/Total_internal_reflection_fluorescence_microscope-1.md
category: reference
title: Total internal reflection fluorescence microscope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Total_internal_reflection_fluorescence_microscope
date_saved: 2026-05-05T10:06:35.424390+00:00
instance: kb-cron
parent: total-internal-reflection-fluorescence-microscope-20260505-0
summary:
== Overview == The idea of using total internal reflection to illuminate cells contacting the surface of glass was first described by E.J. Ambrose in 1956. This idea was then extended by Daniel Axelrod at the University of Michigan, Ann Arbor in the early 1980s as TIRFM. A TIRFM uses an evanescent wave to selectively illuminate and excite fluorophores in a restricted region of the specimen immediately adjacent to the glass-water interface. The evanescent electromagnetic field decays exponentially from the interface, and thus penetrates to a depth of only approximately 100 nm into the sample medium. Thus the TIRFM enables a selective visualization of surface regions such as the basal plasma membrane (which are about 7.5 nm thick) of cells. Note, however, that the region visualized is at least a few hundred nanometers wide, so the cytoplasmic zone immediately beneath the plasma membrane is necessarily visualized in addition to the plasma membrane during TIRF microscopy. The selective visualization of the plasma membrane renders the features and events on the plasma membrane in living cells with high axial resolution. TIRF can also be used to observe the fluorescence of a single molecule, making it an important tool of biophysics and quantitative


id: total-internal-reflection-fluorescence-microscope-20260505-2
file: data/en.wikipedia.org/wiki/Total_internal_reflection_fluorescence_microscope-2.md
category: reference
title: Total internal reflection fluorescence microscope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Total_internal_reflection_fluorescence_microscope
date_saved: 2026-05-05T10:06:35.424390+00:00
instance: kb-cron
parent: total-internal-reflection-fluorescence-microscope-20260505-0
summary:
=== Excitation beam === For complex fluoroscope microscopy techniques, lasers are the preferred light source as they are highly uniform, intense, and near-monochromatic. However, it is noted that ARC LAMP light sources and other types of sources may also work. Typically the wavelength of excitation beam is designated by the requirements of the fluorophores within the sample, with most common excitation wavelengths being in the 400–700 nm range for biological samples. In practice, a lightbox will generate a high intensity multichromatic laser, which will then be filtered to allow the desired wavelengths through to excite the sample. For objective-based TIRFM, the excitation beam and fluoresced emission beam will be captured via the same objective lens. Thus, to split the beams, a dichromatic mirror is used to reflect the incoming excitation beam towards the objective lens, and allow the emission beam to pass through into the detector. Additional filtering may be required to further separate emission and excitation wavelengths. === Emission beam === When excited with specific wavelengths of light, fluorophore dyes will reemit light at longer wavelengths (which contain less energy). In the context of TIRFM, only fluorophores close to the interface will be readily excited by the evanescent field,


id: total-internal-reflection-fluorescence-microscope-20260505-3
file: data/en.wikipedia.org/wiki/Total_internal_reflection_fluorescence_microscope-3.md
category: reference
title: Total internal reflection fluorescence microscope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Total_internal_reflection_fluorescence_microscope
date_saved: 2026-05-05T10:06:35.424390+00:00
instance: kb-cron
parent: total-internal-reflection-fluorescence-microscope-20260505-0
summary:
=== Image artifact and noise === Most fluorescence imaging techniques exhibit background noise due to illuminating and reconstructing large slices (in the z-direction) of the samples. Since TIRFM uses an evanescent wave to fluoresce a thin slice of the sample, there is inherently less background noise and artifacts. However, there are still other noises and artifacts such as poisson noise, optical aberrations, photobleaching, and other fluorescence molecules. Poissonian noise are fundamental uncertainties with the measurement of light. This will cause uncertainties during the detection of fluorescence photons. If N photons are measured in a particular measurement, there is a 63% probability that the true average value is in the range between N +√N and N −√N. This noise may cause misrepresentation of the object at incorrect pixel locations. Optical aberrations can arise from diffraction of fluorescence light or microscope and objective misalignment. Diffraction of light on the sample slide can spread the fluorescence signal and result in blurring in the convoluted images. Similarly, if there is a misalignment between the objective lens, filter, and detector, the excitation or emission beam may not be in focus and can cause blurring in the images. Photobleaching can occur when the covalent or noncovalent


id: transmission-electron-microscopy-20260505-0
file: data/en.wikipedia.org/wiki/Transmission_electron_microscopy-0.md
category: reference
title: Transmission electron microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Transmission_electron_microscopy
date_saved: 2026-05-05T10:06:36.644553+00:00
instance: kb-cron
parent: transmission-electron-microscopy-20260505-0
summary:
Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a grid. An image is formed from the interaction of the electrons with the sample as the beam is transmitted through the specimen. The image is then magnified and focused onto an imaging device, such as a fluorescent screen, a layer of photographic film, or a detector such as a scintillator attached to a charge-coupled device or a direct electron detector. Transmission electron microscopes are capable of imaging at a significantly higher resolution than light microscopes, owing to the smaller de Broglie wavelength of electrons. This enables the instrument to capture fine detail—even as small as a single column of atoms, which is thousands of times smaller than a resolvable object seen in a light microscope. Transmission electron microscopy is a major analytical method in the physical, chemical and biological sciences. TEMs find application in cancer research, virology, and materials science as well as pollution, nanotechnology and semiconductor research, but also in other fields such as paleontology and palynology. TEM


id: transmission-electron-microscopy-20260505-1
file: data/en.wikipedia.org/wiki/Transmission_electron_microscopy-1.md
category: reference
title: Transmission electron microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Transmission_electron_microscopy
date_saved: 2026-05-05T10:06:36.644553+00:00
instance: kb-cron
parent: transmission-electron-microscopy-20260505-0
summary:
=== Improving resolution === At the time, electrons were understood to be charged particles of matter; the wave nature of electrons was not fully realized until the PhD thesis of Louis de Broglie in 1924. Knoll's research group was unaware of this publication until 1932, when they realized that the de Broglie wavelength of electrons was many orders of magnitude smaller than that for light, theoretically allowing for imaging at atomic scales. (Even for electrons with a kinetic energy of just 1 electronvolt the wavelength is already as short as 1.18 nm.) In April 1932, Ruska suggested the construction of a new electron microscope for direct imaging of specimens inserted into the microscope, rather than simple mesh grids or images of apertures. With this device successful diffraction and normal imaging of an aluminium sheet was achieved. However the magnification achievable was lower than with light microscopy. Magnifications higher than those available with a light microscope were achieved in September 1933 with images of cotton fibers quickly acquired before being damaged by the electron beam. At this time, interest in the electron microscope had increased, with other groups, such as that of Paul Anderson and Kenneth Fitzsimmons of Washington State University


id: transmission-electron-microscopy-20260505-2
file: data/en.wikipedia.org/wiki/Transmission_electron_microscopy-2.md
category: reference
title: Transmission electron microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Transmission_electron_microscopy
date_saved: 2026-05-05T10:06:36.644553+00:00
instance: kb-cron
parent: transmission-electron-microscopy-20260505-0
summary:
From the top down, the TEM consists of an emission source or cathode, which may be a tungsten filament, a lanthanum hexaboride (LaB6) single crystal or a field emission gun. The gun is connected to a high voltage source (typically ~100–300 kV) and emits electrons either by thermionic or field electron emission into the vacuum. In the case of a thermionic source, the electron source is mounted in a Wehnelt cylinder to provide preliminary focus of the emitted electrons into a beam while also stabilizing the current using a passive feedback circuit. A field emission source uses instead electrostatic electrodes called an extractor, a suppressor, and a gun lens, with different voltages on each, to control the electric field shape and intensity near the sharp tip. The combination of the cathode and these first electrostatic lens elements is collectively called the "electron gun". After it leaves the gun, the beam is typically accelerated until it reaches its final voltage and enters the next part of the microscope: the condenser lens system. These upper lenses of the TEM then further focus the electron beam to the desired size and location on the sample. Manipulation of the electron beam is performed using


id: transmission-electron-microscopy-20260505-3
file: data/en.wikipedia.org/wiki/Transmission_electron_microscopy-3.md
category: reference
title: Transmission electron microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Transmission_electron_microscopy
date_saved: 2026-05-05T10:06:36.644553+00:00
instance: kb-cron
parent: transmission-electron-microscopy-20260505-0
summary:
A TEM is composed of several components, which include a vacuum system in which the electrons travel, an electron emission source for generation of the electron stream, a series of electromagnetic lenses, as well as electrostatic plates. The latter two allow the operator to guide and manipulate the beam as required. Also required is a device to allow the insertion into, motion within, and removal of specimens from the beam path. Imaging devices are subsequently used to create an image from the electrons that exit the system. === Vacuum system === To increase the mean free path of the electron gas interaction, a standard TEM is evacuated to low pressures, typically on the order of 10−4 Pa. The need for this is twofold: first the allowance for the voltage difference between the cathode and the ground without generating an arc, and secondly to reduce the collision frequency of electrons with gas atoms to negligible levels—this effect is characterized by the mean free path. TEM components such as specimen holders and film cartridges must be routinely inserted or replaced requiring a system with the ability to re-evacuate on a regular basis. As such, TEMs are equipped with multiple pumping systems and


id: transmission-electron-microscopy-20260505-4
file: data/en.wikipedia.org/wiki/Transmission_electron_microscopy-4.md
category: reference
title: Transmission electron microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Transmission_electron_microscopy
date_saved: 2026-05-05T10:06:36.644553+00:00
instance: kb-cron
parent: transmission-electron-microscopy-20260505-0
summary:
TEM specimen stage designs include airlocks to allow for insertion of the specimen holder into the vacuum with minimal loss of vacuum in other areas of the microscope. The specimen holders hold a standard size of sample grid or self-supporting specimen. Standard TEM grid sizes are 3.05 mm diameter, with a thickness and mesh size ranging from a few to 100 μm. The sample is placed onto the meshed area having a diameter of approximately 2.5 mm. Usual grid materials are copper, molybdenum, gold or platinum. This grid is placed into the sample holder, which is paired with the specimen stage. A wide variety of designs of stages and holders exist, depending upon the type of experiment being performed. In addition to 3.05 mm grids, 2.3 mm grids are sometimes, if rarely, used. These grids were particularly used in the mineral sciences where a large degree of tilt can be required and where specimen material may be extremely rare. Electron transparent specimens have a thickness usually less than 100 nm, but this value depends on the accelerating voltage. Once inserted into a TEM, the sample has to be manipulated to locate the region of interest to the beam, such as


id: transmission-electron-microscopy-20260505-5
file: data/en.wikipedia.org/wiki/Transmission_electron_microscopy-5.md
category: reference
title: Transmission electron microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Transmission_electron_microscopy
date_saved: 2026-05-05T10:06:36.644553+00:00
instance: kb-cron
parent: transmission-electron-microscopy-20260505-0
summary:
where A is the Richardson's constant, Φ is the work function and T is the temperature of the material. This equation shows that in order to achieve sufficient current density it is necessary to heat the emitter, taking care not to cause damage by application of excessive heat. For this reason materials with either a high melting point, such as tungsten, or those with a low work function (LaB6) are required for the gun filament. Furthermore, both lanthanum hexaboride and tungsten thermionic sources must be heated in order to achieve thermionic emission, this can be achieved by the use of a small resistive strip. To prevent thermal shock, there is often a delay enforced in the application of current to the tip, to prevent thermal gradients from damaging the filament, the delay is usually a few seconds for LaB6, and significantly lower for tungsten. === Electron lens === Electron lenses are designed to act in a manner emulating that of an optical lens, by focusing parallel electrons at some constant focal distance. Electron lenses may operate electrostatically or magnetically. The majority of electron lenses for TEM use electromagnetic coils to generate a convex lens. The field produced for the lens


id: transmission-electron-microscopy-20260505-6
file: data/en.wikipedia.org/wiki/Transmission_electron_microscopy-6.md
category: reference
title: Transmission electron microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Transmission_electron_microscopy
date_saved: 2026-05-05T10:06:36.644553+00:00
instance: kb-cron
parent: transmission-electron-microscopy-20260505-0
summary:
The figure on the right shows the two basic operation modes of TEM – imaging and diffraction modes. In both cases the specimen is illuminated with the parallel beam, formed by electron beam shaping with the system of Condenser lenses and Condenser aperture. After interaction with the sample, on the exit surface of the specimen two types of electrons exist – unscattered (which will correspond to the bright central beam on the diffraction pattern) and scattered electrons (which change their trajectories due to interaction with the material). In Imaging mode, the objective aperture is inserted in a back focal plane (BFP) of the objective lens (where diffraction spots are formed). If using the objective aperture to select only the central beam, the transmitted electrons are passed through the aperture while all others are blocked, and a bright field image (BF image) is obtained. If we allow the signal from a diffracted beam, a dark field image (DF image) is received. The selected signal is magnified and projected on a screen (or on a camera) with the help of Intermediate and Projector lenses. An image of the sample is thus obtained. In Diffraction mode, a selected area aperture may be used


id: transmission-electron-microscopy-20260505-7
file: data/en.wikipedia.org/wiki/Transmission_electron_microscopy-7.md
category: reference
title: Transmission electron microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Transmission_electron_microscopy
date_saved: 2026-05-05T10:06:36.644553+00:00
instance: kb-cron
parent: transmission-electron-microscopy-20260505-0
summary:
Samples can exhibit diffraction contrast, whereby the electron beam undergoes diffraction which in the case of a crystalline sample, disperses electrons into discrete locations in the back focal plane. By the placement of apertures in the back focal plane, i.e. the objective aperture, the desired reciprocal lattice vectors can be selected (or excluded), thus only parts of the sample that are causing the electrons to scatter to the selected reflections will end up projected onto the imaging apparatus. If the reflections that are selected do not include the unscattered beam (which will appear up at the focal point of the lens), then the image will appear dark wherever no sample scattering to the selected peak is present, as such a region without a specimen will appear dark. This is known as a dark-field image. Modern TEMs are often equipped with specimen holders that allow the user to tilt the specimen to a range of angles in order to obtain specific diffraction conditions, and apertures placed above the specimen allow the user to select electrons that would otherwise be diffracted in a particular direction from entering the specimen. Applications for this method include the identification of lattice defects in crystals. By


id: transmission-electron-microscopy-20260505-8
file: data/en.wikipedia.org/wiki/Transmission_electron_microscopy-8.md
category: reference
title: Transmission electron microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Transmission_electron_microscopy
date_saved: 2026-05-05T10:06:36.644553+00:00
instance: kb-cron
parent: transmission-electron-microscopy-20260505-0
summary:
As TEM specimen holders typically allow for the rotation of a sample by a desired angle, multiple views of the same specimen can be obtained by rotating the angle of the sample along an axis perpendicular to the beam. By taking multiple images of a single TEM sample at differing angles, typically in 1° increments, a set of images known as a "tilt series" can be collected. This methodology was proposed in the 1970s by Walter Hoppe. Under purely absorption contrast conditions, this set of images can be used to construct a three-dimensional representation of the sample. The reconstruction is accomplished by a two-step process, first images are aligned to account for errors in the positioning of a sample; such errors can occur due to vibration or mechanical drift. Alignment methods use image registration algorithms, such as autocorrelation methods to correct these errors. Secondly, using a reconstruction algorithm, such as filtered back projection, the aligned image slices can be transformed from a set of two-dimensional images, Ij(x, y), to a single three-dimensional image, I′j(x, y, z). This three-dimensional image is of particular interest when morphological information is required, further study can be undertaken using computer algorithms, such as isosurfaces and


id: transmission-electron-microscopy-20260505-9
file: data/en.wikipedia.org/wiki/Transmission_electron_microscopy-9.md
category: reference
title: Transmission electron microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Transmission_electron_microscopy
date_saved: 2026-05-05T10:06:36.644553+00:00
instance: kb-cron
parent: transmission-electron-microscopy-20260505-0
summary:
Before sectioning, biological tissue is often embedded in an epoxy resin block and first trimmed using a razor blade into a trapezoidal block face. Thick sections are then cut from the block face. The thick sections are crudely stained with toluidine blue and examined for specimen and block orientation before thin sectioning. Biological tissue is then thinned to less than 100 nm on an ultramicrotome. The resin block is fractured as it passes over a glass or diamond knife edge. This method is used to obtain thin, minimally deformed samples that allow for the observation of tissue ultrastructure. Inorganic samples, such as aluminium, may also be embedded in resins and ultrathin sectioned in this way, using either coated glass, sapphire or larger angle diamond knives. To prevent charge build-up at the sample surface when viewing in the TEM, tissue samples need to be coated with a thin layer of conducting material, such as carbon. === Sample staining === TEM samples of biological tissues need high atomic number stains to enhance contrast. The stain absorbs the beam electrons or scatters part of the electron beam which otherwise is projected onto the imaging system. Compounds of heavy metals such as osmium, lead,


id: transmission-electron-microscopy-20260505-10
file: data/en.wikipedia.org/wiki/Transmission_electron_microscopy-10.md
category: reference
title: Transmission electron microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Transmission_electron_microscopy
date_saved: 2026-05-05T10:06:36.644553+00:00
instance: kb-cron
parent: transmission-electron-microscopy-20260505-0
summary:
A TEM can be modified into a scanning transmission electron microscope (STEM) by the addition of a system that rasters a convergent beam across the sample to form the image, when combined with suitable detectors. Scanning coils are used to deflect the beam, such as by an electrostatic shift of the beam, where the beam is then collected using a current detector such as a Faraday cup, which acts as a direct electron counter. By correlating the electron count to the position of the scanning beam (known as the "probe"), the transmitted component of the beam may be measured. The non-transmitted components may be obtained either by beam tilting or by the use of annular dark field detectors. Fundamentally, TEM and STEM are linked via Helmholtz reciprocity. A STEM is a TEM in which the electron source and observation point have been switched relative to the direction of travel of the electron beam. See the ray diagrams in the figure on the right. The STEM instrument effectively relies on the same optical set-up as a TEM, but operates by flipping the direction of travel of the electrons (or reversing time) during operation of a TEM. Rather than using an aperture


id: transmission-electron-microscopy-20260505-11
file: data/en.wikipedia.org/wiki/Transmission_electron_microscopy-11.md
category: reference
title: Transmission electron microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Transmission_electron_microscopy
date_saved: 2026-05-05T10:06:36.644553+00:00
instance: kb-cron
parent: transmission-electron-microscopy-20260505-0
summary:
High resolution of TEM allows for monitoring the sample in question on a length scale ranging from hundreds of nanometres to several angstroms. This allows for the visualization of both elastic and plastic deformation via strain fields as well as the motion of crystallographic defects such as lattice distortions and dislocation motion. By simultaneously observing deformation phenomena and measuring mechanical response in situ, it is possible to connect nano-mechanical testing information to models that describe both the subtlety and complexity of how materials respond to stress and strain. The material properties and data accuracy obtained from such nano-mechanical tests is largely determined by the mechanical straining holder being used. Current straining holders have the ability to perform tensile tests, nano-indentation, compression tests, shear tests and bending tests on materials. ==== Classical mechanical holders ==== One of the pioneers of classical holders was Heinz G.F. Wilsdorf, who conducted a tensile test inside a TEM in 1958. In a typical experiment, electron transparent TEM samples are cut to shape and glued to a deformable grid. Advances in micromanipulators have also enabled the tensile testing of nanowires and thin films. The deformable grid attaches to the classical tensile holder which stretches the sample


id: transmission-electron-microscopy-20260505-12
file: data/en.wikipedia.org/wiki/Transmission_electron_microscopy-12.md
category: reference
title: Transmission electron microscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Transmission_electron_microscopy
date_saved: 2026-05-05T10:06:36.644553+00:00
instance: kb-cron
parent: transmission-electron-microscopy-20260505-0
summary:
It is possible to reach temporal resolution far beyond that of the readout rate of electron detectors with the use of pulsed electrons. Pulses can be produced by either modifying the electron source to enable laser-triggered photoemission or by installation of an ultrafast beam blanker. This approach is termed ultrafast transmission electron microscopy when stroboscopic pump-probe illumination is used: an image is formed by the accumulation of many ultrashort electron pulses (typically of hundreds of femtoseconds) with a fixed time delay between the arrival of the electron pulse and the sample excitation. On the other hand, the use of single or a short sequence of electron pulses with a sufficient number of electrons to form an image from each pulse is called dynamic transmission electron microscopy. Temporal resolution down to hundreds of femtoseconds and spatial resolution comparable to that available with a Schottky field emission source is possible in ultrafast TEM. Using the Photon-gating approach, the temporal resolution in ultrafast electron microscope reaches to 30-fs allowing the imaging of ultrafast atomic and electron dynamics of matter. However, the technique can only image reversible processes that can be reproducibly triggered millions of times. Dynamic TEM can resolve irreversible processes down to


id: transmission-electron-microscopy-dna-sequencing-20260505-0
file: data/en.wikipedia.org/wiki/Transmission_electron_microscopy_DNA_sequencing-0.md
category: reference
title: Transmission electron microscopy DNA sequencing
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Transmission_electron_microscopy_DNA_sequencing
date_saved: 2026-05-05T10:06:37.867972+00:00
instance: kb-cron
parent: transmission-electron-microscopy-dna-sequencing-20260505-0
summary:
Transmission electron microscopy DNA sequencing is a single-molecule sequencing technology that uses transmission electron microscopy techniques. The method was conceived and developed in the 1960s and 70s, but lost favor when the extent of damage to the sample was recognized. In order for DNA to be clearly visualized under an electron microscope, it must be labeled with heavy atoms. In addition, specialized imaging techniques and aberration corrected optics are beneficial for obtaining the resolution required to image the labeled DNA molecule. In theory, transmission electron microscopy DNA sequencing could provide extremely long read lengths, but the issue of electron beam damage may still remain and the technology has not yet been commercially developed. == History == Only a few years after James Watson and Francis Crick deduced the structure of DNA, and nearly two decades before Frederick Sanger published the first method for rapid DNA sequencing, Richard Feynman, an American physicist, envisioned the electron microscope as the tool that would one day allow biologists to "see the order of bases in the DNA chain". Feynman believed that if the electron microscope could be made powerful enough, then it would become possible to visualize the atomic structure of any and all


id: transmission-electron-microscopy-dna-sequencing-20260505-1
file: data/en.wikipedia.org/wiki/Transmission_electron_microscopy_DNA_sequencing-1.md
category: reference
title: Transmission electron microscopy DNA sequencing
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Transmission_electron_microscopy_DNA_sequencing
date_saved: 2026-05-05T10:06:37.867972+00:00
instance: kb-cron
parent: transmission-electron-microscopy-dna-sequencing-20260505-0
summary:
Annular dark-field imaging measures the scattering of electrons as they deflect off the nuclei of the atoms in the transmission electron microscopy sample. This is best suited to samples containing heavy atoms, as they cause more scattering of electrons. The technique has been used to image atoms as light as boron, nitrogen, and carbon; however, the signal is very weak for such light atoms. If annular dark-field microscopy is put to use for transmission electron microscopy DNA sequencing, it will certainly be necessary to label the DNA bases with heavy atoms so that a strong signal can be detected. Annular bright-field imaging detects electrons transmitted directly through the sample, and measures the wave interference produced by their interactions with the atomic nuclei. This technique can detect light atoms with greater sensitivity than annular dark-field imaging methods. In fact, oxygen, nitrogen, lithium, and hydrogen in crystalline solids have been imaged using annular bright-field electron microscopy. Thus, it is theoretically possible to obtain direct images of the atoms in the DNA chain; however, the structure of DNA is much less geometric than crystalline solids, so direct imaging without prior labeling may not be achievable. === Step 5 – Data analysis === Dark


id: transmission-electron-microscopy-dna-sequencing-20260505-2
file: data/en.wikipedia.org/wiki/Transmission_electron_microscopy_DNA_sequencing-2.md
category: reference
title: Transmission electron microscopy DNA sequencing
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Transmission_electron_microscopy_DNA_sequencing
date_saved: 2026-05-05T10:06:37.867972+00:00
instance: kb-cron
parent: transmission-electron-microscopy-dna-sequencing-20260505-0
summary:
== Strengths and weaknesses == Compared to other second- and third-generation DNA sequencing technologies, transmission electron microscopy DNA sequencing has a number of potential key strengths and weaknesses, which will ultimately determine its usefulness and prominence as a future DNA sequencing technology. === Strengths === Longer read lengths: ZS Genetics has estimated potential read lengths of transmission electron microscopy DNA sequencing to be 10,000 to 20,000 base pairs with a rate of 1.7 billion base pairs per day. Such long read lengths would allow easier de novo genome assembly and direct detection of haplotypes, among other applications. Lower cost: Transmission electron microscopy DNA sequencing is estimated to cost just US$5,000-US$10,000 per human genome, compared to the more expensive second-generation DNA sequencing alternatives. No dephasing: Dephasing of the DNA strands due to loss in synchronicity during synthesis is a major problem of second-generation sequencing technologies. For transmission electron microscopy DNA sequencing and several other third-generation sequencing technologies, synchronization of the reads is unnecessary as only one molecule is being read at a time. Shorter turnaround time: The capacity to read native fragments of DNA renders complex template preparation an unnecessary step in the general workflow of whole genome sequencing. Consequently, shorter


id: transmission-kikuchi-diffraction-20260505-0
file: data/en.wikipedia.org/wiki/Transmission_Kikuchi_diffraction-0.md
category: reference
title: Transmission Kikuchi diffraction
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Transmission_Kikuchi_diffraction
date_saved: 2026-05-05T10:06:39.042429+00:00
instance: kb-cron
parent: transmission-kikuchi-diffraction-20260505-0
summary:
Transmission Kikuchi diffraction (TKD), also sometimes called transmission electron backscatter diffraction (t-EBSD), is a method for orientation mapping at the nanoscale. It’s used for analysing the microstructures of thin transmission electron microscopy (TEM) specimens in the scanning electron microscope (SEM). This technique has been widely utilised in the characterization of nano-crystalline materials, including oxides, superconductors, and metallic alloys. TKD offers improved spatial resolution, enabling effective characterization of nanocrystalline materials and heavily deformed samples where high dislocation densities can prevent successful characterization using conventional Electron backscatter diffraction. Many studies have reported sub-10 nm resolution using TKD. The main difference between diffraction spots and Kikuchi bands is that in TEM, discrete diffraction spots arise from coherent scattering of the incident beam, while the formation of Kikuchi bands is described as a two-step process consisting of incoherent scattering of the primary beam followed by coherent scattering of these forward biased electrons. TKD has also been applied to analyse fine-grained ultramylonite peridotite samples in a scanning electron microscope. The preparation of TKD samples can be done with standard methods used for transmission electron microscopy (TEM). == Description == Transmission Kikuchi diffraction (TKD or t-EBSD) is an Electron backscatter diffraction (EBSD) technique that is used


id: two-dimensional-correlation-analysis-20260505-0
file: data/en.wikipedia.org/wiki/Two-dimensional_correlation_analysis-0.md
category: reference
title: Two-dimensional correlation analysis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Two-dimensional_correlation_analysis
date_saved: 2026-05-05T10:06:40.213046+00:00
instance: kb-cron
parent: two-dimensional-correlation-analysis-20260505-0
summary:
Two dimensional correlation analysis is a mathematical technique that is used to study changes in measured signals. As mostly spectroscopic signals are discussed, sometime also two dimensional correlation spectroscopy is used and refers to the same technique. In 2D correlation analysis, a sample is subjected to an external perturbation while all other parameters of the system are kept at the same value. This perturbation can be a systematic and controlled change in temperature, pressure, pH, chemical composition of the system, or even time after a catalyst was added to a chemical mixture. As a result of the controlled change (the perturbation), the system will undergo variations which are measured by a chemical or physical detection method. The measured signals or spectra will show systematic variations that are processed with 2D correlation analysis for interpretation. When one considers spectra that consist of few bands, it is quite obvious to determine which bands are subject to a changing intensity. Such a changing intensity can be caused for example by chemical reactions. However, the interpretation of the measured signal becomes more tricky when spectra are complex and bands are heavily overlapping. Two dimensional correlation analysis allows one to determine at which positions in


id: two-dimensional-correlation-analysis-20260505-1
file: data/en.wikipedia.org/wiki/Two-dimensional_correlation_analysis-1.md
category: reference
title: Two-dimensional correlation analysis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Two-dimensional_correlation_analysis
date_saved: 2026-05-05T10:06:40.213046+00:00
instance: kb-cron
parent: two-dimensional-correlation-analysis-20260505-0
summary:
Ψ is the 2D asynchronous spectrum ν1 en ν2 are two spectral channels yν is the vector composed of the signal intensities in E in column ν n the number of signals in the original dataset N the Noda-Hilbert transform matrix The values of N, Nj, k are determined as follows: 0 if j = k 1 π ( k − j ) {\displaystyle {\frac {1}{\pi (k-j)}}} if j ≠ k where: j the row number k the column number == Interpretation == Interpretation of two-dimensional correlation spectra can be considered to consist of several stages. === Detection of peaks of which the intensity changes in the original dataset === As real measurement signals contain a certain level of noise, the derived 2D spectra are influenced and degraded with substantial higher amounts of noise. Hence, interpretation begins with studying the autocorrelation spectrum on the main diagonal of the 2D synchronous spectrum. In the 2D synchronous main diagonal signal on the right 4 peaks are visible at 10, 20, 30, and 40 (see also the 4 corresponding positive autopeaks in the 2D synchronous spectrum on the right). This indicates that in the original dataset 4 peaks of changing intensity are present.


id: ultraviolet-visible-spectroscopy-20260505-0
file: data/en.wikipedia.org/wiki/Ultraviolet–visible_spectroscopy-0.md
category: reference
title: Ultraviolet–visible spectroscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ultraviolet–visible_spectroscopy
date_saved: 2026-05-05T10:06:41.378064+00:00
instance: kb-cron
parent: ultraviolet-visible-spectroscopy-20260505-0
summary:
Ultraviolet–visible spectrophotometry (UV–Vis or UV-VIS) refers to absorption spectroscopy or reflectance spectroscopy in part of the ultraviolet and the full, adjacent visible regions of the electromagnetic spectrum. Being relatively inexpensive and easily implemented, this methodology is widely used in diverse applied and fundamental applications. The only requirement is that the sample absorb in the UV–Vis region, i.e. be a chromophore. Absorption spectroscopy is complementary to fluorescence spectroscopy. Parameters of interest, besides the wavelength of measurement, are absorbance (A) or transmittance (%T) or reflectance (%R), and its change with time. A UV–Vis spectrophotometer is an analytical instrument that measures the amount of ultraviolet (UV) and visible light that is absorbed by a sample. It is a widely used technique in chemistry, biochemistry, and other fields, to identify and quantify compounds in a variety of samples. UV–Vis spectrophotometers work by passing a beam of light through the sample and measuring the amount of light that is absorbed at each wavelength. The amount of light absorbed is proportional to the concentration of the absorbing compound in the sample. == Optical transitions == Most molecules and ions absorb energy in the ultraviolet or visible range, i.e., they are chromophores. The absorbed photon excites an


id: ultraviolet-visible-spectroscopy-20260505-1
file: data/en.wikipedia.org/wiki/Ultraviolet–visible_spectroscopy-1.md
category: reference
title: Ultraviolet–visible spectroscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ultraviolet–visible_spectroscopy
date_saved: 2026-05-05T10:06:41.378064+00:00
instance: kb-cron
parent: ultraviolet-visible-spectroscopy-20260505-0
summary:
A = log 10 ⁡ ( I 0 / I ) = ε c L {\displaystyle A=\log _{10}(I_{0}/I)=\varepsilon cL} , where A is the measured absorbance (formally dimensionless but generally reported in absorbance units (AU)), I 0 {\displaystyle I_{0}} is the intensity of the incident light at a given wavelength, I {\displaystyle I} is the transmitted intensity, L the path length through the sample, and c the concentration of the absorbing species. For each species and wavelength, ε is a constant known as the molar absorptivity or extinction coefficient. This constant is a fundamental molecular property in a given solvent, at a particular temperature and pressure, and has units of 1 / M ∗ c m {\displaystyle 1/M*cm} . The absorbance and extinction ε are sometimes defined in terms of the natural logarithm instead of the base-10 logarithm. The Beer–Lambert law is useful for characterizing many compounds but does not hold as a universal relationship for the concentration and absorption of all substances. A 2nd order polynomial relationship between absorption and concentration is sometimes encountered for very large, complex molecules such as organic dyes (xylenol orange or neutral red, for example). UV–Vis spectroscopy is also used in the semiconductor industry


id: ultraviolet-visible-spectroscopy-20260505-2
file: data/en.wikipedia.org/wiki/Ultraviolet–visible_spectroscopy-2.md
category: reference
title: Ultraviolet–visible spectroscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ultraviolet–visible_spectroscopy
date_saved: 2026-05-05T10:06:41.378064+00:00
instance: kb-cron
parent: ultraviolet-visible-spectroscopy-20260505-0
summary:
Stray light in a UV spectrophotometer is any light that reaches its detector that is not of the wavelength selected by the monochromator. This can be caused, for instance, by scattering of light within the instrument, or by reflections from optical surfaces. Stray light can cause significant errors in absorbance measurements, especially at high absorbances, because the stray light will be added to the signal detected by the detector, even though it is not part of the actually selected wavelength. The result is that the measured and reported absorbance will be lower than the actual absorbance of the sample. The stray light is an important factor, as it determines the purity of the light used for the analysis. The most important factor affecting it is the stray light level of the monochromator. Typically a detector used in a UV–VIS spectrophotometer is broadband; it responds to all the light that reaches it. If a significant amount of the light passed through the sample contains wavelengths that have much lower extinction coefficients than the nominal one, the instrument will report an incorrectly low absorbance. Any instrument will reach a point where an increase in sample concentration will not result in an increase


id: ultraviolet-visible-spectroscopy-20260505-3
file: data/en.wikipedia.org/wiki/Ultraviolet–visible_spectroscopy-3.md
category: reference
title: Ultraviolet–visible spectroscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ultraviolet–visible_spectroscopy
date_saved: 2026-05-05T10:06:41.378064+00:00
instance: kb-cron
parent: ultraviolet-visible-spectroscopy-20260505-0
summary:
The UV–visible spectrophotometer can also be configured to measure reflectance. In this case, the spectrophotometer measures the intensity of light reflected from a sample ( I {\displaystyle I} ), and compares it to the intensity of light reflected from a reference material ( I o {\displaystyle I_{o}} ) (such as a white tile). The ratio I / I o {\displaystyle I/I_{o}} is called the reflectance, and is usually expressed as a percentage (%R). The basic parts of a spectrophotometer are a light source, a holder for the sample, a diffraction grating or a prism as a monochromator to separate the different wavelengths of light, and a detector. The radiation source is often a tungsten filament (300–2500 nm), a deuterium arc lamp, which is continuous over the ultraviolet region (190–400 nm), a xenon arc lamp, which is continuous from 160 to 2,000 nm; or more recently, light emitting diodes (LED) for the visible wavelengths. The detector is typically a photomultiplier tube, a photodiode, a photodiode array or a charge-coupled device (CCD). Single photodiode detectors and photomultiplier tubes are used with scanning monochromators, which filter the light so that only light of a single wavelength reaches the detector at one time. The


id: ultraviolet-visible-spectroscopy-20260505-4
file: data/en.wikipedia.org/wiki/Ultraviolet–visible_spectroscopy-4.md
category: reference
title: Ultraviolet–visible spectroscopy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ultraviolet–visible_spectroscopy
date_saved: 2026-05-05T10:06:41.378064+00:00
instance: kb-cron
parent: ultraviolet-visible-spectroscopy-20260505-0
summary:
== Microspectrophotometry == UV–visible spectroscopy of microscopic samples is done by integrating an optical microscope with UV–visible optics, white light sources, a monochromator, and a sensitive detector such as a charge-coupled device (CCD) or photomultiplier tube (PMT). As only a single optical path is available, these are single beam instruments. Modern instruments are capable of measuring UV–visible spectra in both reflectance and transmission of micron-scale sampling areas. The advantages of using such instruments is that they are able to measure microscopic samples but are also able to measure the spectra of larger samples with high spatial resolution. As such, they are used in the forensic laboratory to analyze the dyes and pigments in individual textile fibers, microscopic paint chips and the color of glass fragments. They are also used in materials science and biological research and for determining the energy content of coal and petroleum source rock by measuring the vitrinite reflectance. Microspectrophotometers are used in the semiconductor and micro-optics industries for monitoring the thickness of thin films after they have been deposited. In the semiconductor industry, they are used because the critical dimensions of circuitry is microscopic. A typical test of a semiconductor wafer would entail the acquisition of


id: weisz-prater-criterion-20260505-0
file: data/en.wikipedia.org/wiki/Weisz–Prater_criterion-0.md
category: reference
title: Weisz–Prater criterion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Weisz–Prater_criterion
date_saved: 2026-05-05T10:06:42.548723+00:00
instance: kb-cron
parent: weisz-prater-criterion-20260505-0
summary:
The Weisz–Prater criterion is a method used to estimate the influence of pore diffusion on reaction rates in heterogeneous catalytic reactions. If the criterion is satisfied, pore diffusion limitations are negligible. The criterion is N W − P = R R p 2 C s D e f f ≤ 3 β {\displaystyle N_{W-P}={\dfrac {{\mathfrak {R}}R_{p}^{2}}{C_{s}D_{eff}}}\leq 3\beta } Where R {\displaystyle {\mathfrak {R}}} is the reaction rate per volume of catalyst, R p {\displaystyle R_{p}} is the catalyst particle radius, C s {\displaystyle C_{s}} is the reactant concentration at the particle surface, and D e f f {\displaystyle D_{eff}} is the effective diffusivity. Diffusion is usually in the Knudsen regime when average pore radius is less than 100 nm. For a given effectiveness factor, η {\displaystyle \eta } , and reaction order, n, the quantity β {\displaystyle \beta } is defined by the equation: η = 3 R p 3 ∫ 0 R p [ 1 − β ( 1 − r / R p ) n ] r 2 d r {\displaystyle \eta ={\dfrac {3}{R_{p}^{3}}}\int _{0}^{R_{p}}[1-\beta (1-r/R_{p})^{n}]r^{2}\ dr} for small values of beta this can be approximated using the binomial theorem: η = 1 − n β 4 {\displaystyle


id: x-ray-crystal-truncation-rod-20260505-0
file: data/en.wikipedia.org/wiki/X-ray_crystal_truncation_rod-0.md
category: reference
title: X-ray crystal truncation rod
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/X-ray_crystal_truncation_rod
date_saved: 2026-05-05T10:06:43.719814+00:00
instance: kb-cron
parent: x-ray-crystal-truncation-rod-20260505-0
summary:
X-ray crystal truncation rod scattering is a powerful method in surface science, based on analysis of surface X-ray diffraction (SXRD) patterns from a crystalline surface. For an infinite crystal, the diffracted pattern is concentrated in Dirac delta function like Bragg peaks. Presence of crystalline surfaces results in additional structure along so-called truncation rods (linear regions in momentum space normal to the surface). Crystal Truncation Rod (CTR) measurements allow detailed determination of atomic structure at the surface, especially useful in cases of oxidation, epitaxial growth, and adsorption studies on crystalline surfaces. == Theory == A particle incident on a crystalline surface with momentum K 0 {\displaystyle K_{0}} will undergo scattering through a momentum change of Q {\displaystyle \mathbf {Q} } . If x {\displaystyle x} and y {\displaystyle y} represent directions in the plane of the surface and z {\displaystyle z} is perpendicular to the surface, then the scattered intensity as a function of all possible values of Q {\displaystyle \mathbf {Q} } is given by Where α {\displaystyle \alpha } is the penetration coefficient, defined as the ratio of x-ray amplitudes scattered from successive planes of atoms in the crystal, and a x {\displaystyle a_{x}} , a y {\displaystyle a_{y}}


id: x-ray-fluorescence-20260505-0
file: data/en.wikipedia.org/wiki/X-ray_fluorescence-0.md
category: reference
title: X-ray fluorescence
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/X-ray_fluorescence
date_saved: 2026-05-05T10:06:44.876284+00:00
instance: kb-cron
parent: x-ray-fluorescence-20260505-0
summary:
X-ray fluorescence (XRF) is the emission of characteristic "secondary" (or fluorescent) X-rays from a material that has been excited by being bombarded with high-energy X-rays or gamma rays. When a material is illuminated with high-energy X-rays, its atoms can become excited and emit their own unique, characteristic X-rays—a process similar to how a blacklight makes certain colors fluoresce. By measuring the energy and intensity of these emitted "secondary" X-rays, scientists can identify which elements are present in the sample and in what quantities. Thus, XRF is the basis of a non-destructive analytical technique widely used for elemental analysis and chemical analysis, particularly in the investigation of metals, glass, ceramics and building materials, and for research in geochemistry, forensic science, archaeology and art objects such as paintings. == Underlying physics == When materials are exposed to short-wavelength X-rays or to gamma rays, ionization of their component atoms may take place. Ionization consists of the ejection of one or more electrons from the atom, and may occur if the atom is exposed to radiation with an energy greater than its ionization energy. X-rays and gamma rays can be energetic enough to expel tightly held electrons from the inner orbitals of the atom.


id: x-ray-fluorescence-20260505-1
file: data/en.wikipedia.org/wiki/X-ray_fluorescence-1.md
category: reference
title: X-ray fluorescence
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/X-ray_fluorescence
date_saved: 2026-05-05T10:06:44.876284+00:00
instance: kb-cron
parent: x-ray-fluorescence-20260505-0
summary:
In energy-dispersive analysis, dispersion and detection are a single operation, as already mentioned above. Proportional counters or various types of solid-state detectors (PIN diode, Si(Li), Ge(Li), silicon drift detector SDD) are used. They all share the same detection principle: An incoming X-ray photon ionizes a large number of detector atoms with the amount of charge produced being proportional to the energy of the incoming photon. The charge is then collected and the process repeats itself for the next photon. Detector speed is obviously critical, as all charge carriers measured have to come from the same photon to measure the photon energy correctly (peak length discrimination is used to eliminate events that seem to have been produced by two X-ray photons arriving almost simultaneously). The spectrum is then built up by dividing the energy spectrum into discrete bins and counting the number of pulses registered within each energy bin. EDXRF detector types vary in resolution, speed and the means of cooling (a low number of free charge carriers is critical in the solid state detectors): proportional counters with resolutions of several hundred eV cover the low end of the performance spectrum, followed by PIN diode detectors, while the Si(Li), Ge(Li) and


id: x-ray-fluorescence-20260505-2
file: data/en.wikipedia.org/wiki/X-ray_fluorescence-2.md
category: reference
title: X-ray fluorescence
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/X-ray_fluorescence
date_saved: 2026-05-05T10:06:44.876284+00:00
instance: kb-cron
parent: x-ray-fluorescence-20260505-0
summary:
==== Processing ==== Considerable computer power is dedicated to correcting for pulse-pile up and for extraction of data from poorly resolved spectra. These elaborate correction processes tend to be based on empirical relationships that may change with time, so that continuous vigilance is required in order to obtain chemical data of adequate precision. Digital pulse processors are widely used in high performance nuclear instrumentation. They are able to effectively reduce pile-up and base line shifts, allowing for easier processing. A low pass filter is integrated, improving the signal to noise ratio. The digital pulse processor requires a significant amount of energy to run, but it provides precise results. ==== Usage ==== Energy-dispersive X-ray (EDX) spectrometers are different from wavelength dispersive X-ray (WDX) spectrometers in that they are smaller, simpler in design and have fewer engineered parts; however, the accuracy and resolution of EDX spectrometers are lower than for WDX. EDX spectrometers can also use miniature X-ray tubes or gamma sources, which makes them cheaper and allows miniaturization and portability. This type of instrument is commonly used for portable quality control screening applications, such as testing toys for lead (Pb) content, sorting scrap metals, and measuring the lead content of residential


id: x-ray-fluorescence-20260505-3
file: data/en.wikipedia.org/wiki/X-ray_fluorescence-3.md
category: reference
title: X-ray fluorescence
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/X-ray_fluorescence
date_saved: 2026-05-05T10:06:44.876284+00:00
instance: kb-cron
parent: x-ray-fluorescence-20260505-0
summary:
===== Flat crystal with Söller collimators ===== A Söller collimator is a stack of parallel metal plates, spaced a few tenths of a millimeter apart. To improve angular resolution, one must lengthen the collimator, and/or reduce the plate spacing. This arrangement has the advantage of simplicity and relatively low cost, but the collimators reduce intensity and increase scattering, and reduce the area of sample and crystal that can be "seen". The simplicity of the geometry is especially useful for variable-geometry monochromators. ===== Curved crystal with slits ===== The Rowland circle geometry ensures that the slits are both in focus, but in order for the Bragg condition to be met at all points, the crystal must first be bent to a radius of 2R (where R is the radius of the Rowland circle), then ground to a radius of R. This arrangement allows higher intensities (typically 8-fold) with higher resolution (typically 4-fold) and lower background. However, the mechanics of keeping Rowland circle geometry in a variable-angle monochromator is extremely difficult. In the case of fixed-angle monochromators (for use in simultaneous spectrometers), crystals bent to a logarithmic spiral shape give the best focusing performance. The manufacture of curved crystals to acceptable tolerances


id: x-ray-fluorescence-20260505-4
file: data/en.wikipedia.org/wiki/X-ray_fluorescence-4.md
category: reference
title: X-ray fluorescence
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/X-ray_fluorescence
date_saved: 2026-05-05T10:06:44.876284+00:00
instance: kb-cron
parent: x-ray-fluorescence-20260505-0
summary:
==== Detectors ==== Detectors used for wavelength dispersive spectrometry need to have high pulse processing speeds in order to cope with the very high photon count rates that can be obtained. In addition, they need sufficient energy resolution to allow filtering-out of background noise and spurious photons from the primary beam or from crystal fluorescence. There are four common types of detector: gas flow proportional counters sealed gas detectors scintillation counters semiconductor detectors Gas flow proportional counters are used mainly for detection of longer wavelengths. Gas flows through it continuously. Where there are multiple detectors, the gas is passed through them in series, then led to waste. The gas is usually 90% argon, 10% methane ("P10"), although the argon may be replaced with neon or helium where very long wavelengths (over 5 nm) are to be detected. The argon is ionized by incoming X-ray photons, and the electric field multiplies this charge into a measurable pulse. The methane suppresses the formation of fluorescent photons caused by recombination of the argon ions with stray electrons. The anode wire is typically tungsten or nichrome of 20–60 μm diameter. Since the pulse strength obtained is essentially proportional to the ratio of the detector


id: x-ray-fluorescence-20260505-5
file: data/en.wikipedia.org/wiki/X-ray_fluorescence-5.md
category: reference
title: X-ray fluorescence
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/X-ray_fluorescence
date_saved: 2026-05-05T10:06:44.876284+00:00
instance: kb-cron
parent: x-ray-fluorescence-20260505-0
summary:
X-ray absorption X-ray enhancement sample macroscopic effects All elements absorb X-rays to some extent. Each element has a characteristic absorption spectrum which consists of a "saw-tooth" succession of fringes, each step-change of which has wavelength close to an emission line of the element. Absorption attenuates the secondary X-rays leaving the sample. For example, the mass absorption coefficient of silicon at the wavelength of the aluminium Kα line is 50 m2/kg, whereas that of iron is 377 m2/kg. This means that fluorescent X-rays generated by a given concentration of aluminium in a matrix of iron are absorbed about seven times more (that is 377/50) compared with the fluorescent X-rays generated by the same concentration of aluminium, but in a silicon matrix. That would lead to about one seventh of the count rate, once the X-rays are detected. Mass absorption coefficients are well known and can be calculated. However, to calculate the absorption for a multi-element sample, the composition must be known. For analysis of an unknown sample, an iterative procedure is therefore used. To derive the mass absorption accurately, data for the concentration of elements not measured by XRF may be needed, and various strategies are employed to estimate these. As


id: x-ray-telescope-20260505-0
file: data/en.wikipedia.org/wiki/X-ray_telescope-0.md
category: reference
title: X-ray telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/X-ray_telescope
date_saved: 2026-05-05T10:06:46.164760+00:00
instance: kb-cron
parent: x-ray-telescope-20260505-0
summary:
An X-ray telescope (XRT) is a telescope that is designed to observe remote objects in the X-ray spectrum. X-rays are absorbed by the Earth's atmosphere, so instruments to detect X-rays must be taken to high altitude by balloons, sounding rockets, and satellites. The basic elements of the telescope are the optics (focusing or collimating), that collects the radiation entering the telescope, and the detector, on which the radiation is collected and measured. A variety of different designs and technologies have been used for these elements. Many X-ray telescopes on satellites are compounded of multiple small detector-telescope systems whose capabilities add up or complement each other, and additional fixed or removable elements (filters, spectrometers) that add functionalities to the instrument. == History of X-ray telescopes == X-ray telescopes were first used for astronomy to observe the Sun, which was the only source in the sky bright enough in X-rays for those early telescopes to detect. Because the Sun is so bright in X-rays, early X-ray telescopes could use a small focusing element and the X-rays would be detected with photographic film. The first X-ray picture of the Sun from a rocket-borne telescope was taken by John V. Lindsay of the NASA


id: x-ray-telescope-20260505-1
file: data/en.wikipedia.org/wiki/X-ray_telescope-1.md
category: reference
title: X-ray telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/X-ray_telescope
date_saved: 2026-05-05T10:06:46.164760+00:00
instance: kb-cron
parent: x-ray-telescope-20260505-0
summary:
a high resolution imaging a high telescope sensitivity: since radiation is focused on a small area, Signal-to-noise ratio is much higher for this kind of instruments. The mirrors can be made of ceramic or metal foil coated with a thin layer of a reflective material (typically gold or iridium). Mirrors based on this construction work on the basis of total reflection of light at grazing incidence. This technology is limited in energy range due to the fact that the critical angle for total reflection is inversely proportional to the X-ray photon energy, meaning that higher energy photons require smaller incidence angles and therefore longer telescope designs. The limit in the early 2000s with Chandra and XMM-Newton X-ray observatories was about 15 kilo-electronvolt (keV) light. Using new multi-layered coated mirrors, the X-ray mirror for the NuSTAR telescope pushed this up to 79 keV light. To reflect at this level, glass layers were multi-coated with tungsten (W)/silicon (Si) or platinum (Pt)/silicon carbide(SiC). === Collimating optics === While earlier X-ray telescopes were using simple collimating techniques (e.g. rotating collimators, wire collimators), the technology most used in the present day employs coded aperture masks. This technique uses a flat aperture patterned grille in front


id: x-ray-telescope-20260505-2
file: data/en.wikipedia.org/wiki/X-ray_telescope-2.md
category: reference
title: X-ray telescope
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/X-ray_telescope
date_saved: 2026-05-05T10:06:46.164760+00:00
instance: kb-cron
parent: x-ray-telescope-20260505-0
summary:
A scintillator is a material which exhibits the property of luminescence when excited by ionizing radiation. Luminescent materials, when struck by an incoming particle, such as an X-ray photon, absorb its energy and scintillate, i.e. reemit the absorbed energy in the form of a small flash of light, typically in the visible range. The scintillation X-ray detector were used on Vela 5A and its twin Vela 5B; the X-ray telescope onboard OSO 4 consisted of a single thin NaI(Tl) scintillation crystal plus phototube assembly enclosed in a CsI(Tl) anti-coincidence shield. OSO 5 carried a CsI crystal scintillator. The central crystal was 0.635 cm thick, had a sensitive area of 70 cm2, and was viewed from behind by a pair of photomultiplier tubes. The PHEBUS had two independent detectors, each detector consisted of a bismuth germinate (BGO) crystal 78 mm in diameter by 120 mm thick. The KONUS-B instrument consisted of seven detectors distributed around the spacecraft that responded to photons of 10 keV to 8 MeV energy. They consisted of NaI(Tl) scintillator crystals 200 mm in diameter by 50 mm thick behind a Be entrance window. Kvant-1 carried the HEXE, or High Energy X-ray Experiment, which employed a phoswich of


id: scientific-theory-20260505-0
file: data/en.wikipedia.org/wiki/Scientific_theory-0.md
category: reference
title: Scientific theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scientific_theory
date_saved: 2026-05-05T10:06:47.725273+00:00
instance: kb-cron
parent: scientific-theory-20260505-0
summary:
A scientific theory is an explanation of an aspect of the natural world that can be or that has been repeatedly tested and has corroborating evidence in accordance with the scientific method, using accepted protocols of observation, measurement, and evaluation of results. Where possible, theories are tested under controlled conditions in an experiment. In circumstances not amenable to experimental testing, theories are evaluated through principles of abductive reasoning. Established scientific theories have withstood rigorous scrutiny and embody scientific knowledge. A scientific theory differs from a scientific fact: a fact is an observation, while a theory connects and explains multiple observations. Furthermore, a theory is expected to make predictions which could be confirmed or refuted with additional observations. Stephen Jay Gould wrote that: "...facts and theories are different things, not rungs in a hierarchy of increasing certainty. Facts are the world's data. Theories are structures of ideas that explain and interpret facts." A theory differs from a scientific law in that a law is an empirical description of a relationship between facts and/or other laws. For example, Newton's Law of Gravity is a mathematical equation that can be used to predict the attraction between bodies, but it is not a theory


id: scientific-theory-20260505-1
file: data/en.wikipedia.org/wiki/Scientific_theory-1.md
category: reference
title: Scientific theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scientific_theory
date_saved: 2026-05-05T10:06:47.725273+00:00
instance: kb-cron
parent: scientific-theory-20260505-0
summary:
It can be subjected to minor adaptations to account for new data that do not fit it perfectly, as they are discovered, thus increasing its predictive capability over time. It is among the most parsimonious explanations, economical in the use of proposed entities or explanatory steps as per Occam's razor. This is because for each accepted explanation of a phenomenon, there may be an extremely large, perhaps even incomprehensible, number of possible and more complex alternatives, because one can always burden failing explanations with ad hoc hypotheses to prevent them from being falsified; therefore, simpler theories are preferable to more complex ones because they are more testable. === Definitions from scientific organizations === The United States National Academy of Sciences defines scientific theories as follows: The formal scientific definition of theory is quite different from the everyday meaning of the word. It refers to a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence. Many scientific theories are so well established that no new evidence is likely to alter them substantially. For example, no new evidence will demonstrate that the Earth does not orbit around the Sun (heliocentric theory), or that living things


id: scientific-theory-20260505-2
file: data/en.wikipedia.org/wiki/Scientific_theory-2.md
category: reference
title: Scientific theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scientific_theory
date_saved: 2026-05-05T10:06:47.725273+00:00
instance: kb-cron
parent: scientific-theory-20260505-0
summary:
== Modification and improvement == If experimental results contrary to a theory's predictions are observed, scientists first evaluate whether the experimental design was sound, and if so they confirm the results by independent replication. A search for potential improvements to the theory then begins. Solutions may require minor or major changes to the theory, or none at all if a satisfactory explanation is found within the theory's existing framework. Over time, as successive modifications build on top of each other, theories consistently improve and greater predictive accuracy is achieved. Since each new version of a theory (or a completely new theory) must have more predictive and explanatory power than the last, scientific knowledge consistently becomes more accurate over time. If modifications to the theory or other explanations seem to be insufficient to account for the new results, then a new theory may be required. Since scientific knowledge is usually durable, this occurs much less commonly than modification. Furthermore, until such a theory is proposed and accepted, the previous theory will be retained. This is because it is still the best available explanation for many other phenomena, as verified by its predictive power in other contexts. For example, it has been


id: scientific-theory-20260505-3
file: data/en.wikipedia.org/wiki/Scientific_theory-3.md
category: reference
title: Scientific theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scientific_theory
date_saved: 2026-05-05T10:06:47.725273+00:00
instance: kb-cron
parent: scientific-theory-20260505-0
summary:
=== Theories and facts === A scientific theory does not turn into a fact. Scientific facts are observations that theories organize and explain. As new facts appear, a theory may be revised or new theories may emerge that encompass these additional facts. While American vernacular speech uses "theory" as similar to a "guess" in opposition to a "fact", in science the word "theory" means a model that is expected to explain a wide range of facts. == About theories == === Theories as axioms === The logical positivists thought of scientific theories as statements in a formal language. First-order logic is an example of a formal language. The logical positivists envisaged a similar scientific language. In addition to scientific theories, the language also included observation sentences ("the sun rises in the east"), definitions, and mathematical statements. The phenomena explained by the theories, if they could not be directly observed by the senses (for example, atoms and radio waves), were treated as theoretical concepts. In this view, theories function as axioms: predicted observations are derived from the theories much like theorems are derived in Euclidean geometry. However, the predictions are then tested against reality to verify the predictions, and the "axioms"


id: scientific-theory-20260505-4
file: data/en.wikipedia.org/wiki/Scientific_theory-4.md
category: reference
title: Scientific theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scientific_theory
date_saved: 2026-05-05T10:06:47.725273+00:00
instance: kb-cron
parent: scientific-theory-20260505-0
summary:
...it is incorrect to speak of an assumption as either true or false, since there is no way of proving it to be either (If there were, it would no longer be an assumption). It is better to consider assumptions as either useful or useless, depending on whether deductions made from them correspond to reality...Since we must start somewhere, we must have assumptions, but at least let us have as few assumptions as possible. Certain assumptions are necessary for all empirical claims (e.g. the assumption that reality exists). However, theories do not generally make assumptions in the conventional sense (statements accepted without evidence). While assumptions are often incorporated during the formation of new theories, these are either supported by evidence (such as from previously existing theories) or the evidence is produced in the course of validating the theory. This may be as simple as observing that the theory makes accurate predictions, which is evidence that any assumptions made at the outset are correct or approximately correct under the conditions tested. Conventional assumptions, without evidence, may be used if the theory is only intended to apply when the assumption is valid (or approximately valid). For example, the special theory of relativity


id: scientific-theory-20260505-5
file: data/en.wikipedia.org/wiki/Scientific_theory-5.md
category: reference
title: Scientific theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scientific_theory
date_saved: 2026-05-05T10:06:47.725273+00:00
instance: kb-cron
parent: scientific-theory-20260505-0
summary:
It is easy to obtain confirmations, or verifications, for nearly every theory—if we look for confirmations. Confirmations should count only if they are the result of risky predictions; that is to say, if, unenlightened by the theory in question, we should have expected an event which was incompatible with the theory—an event which would have refuted the theory. Every "good" scientific theory is a prohibition: it forbids certain things from happening. The more a theory forbids, the better it is. A theory which is not refutable by any conceivable event is non-scientific. Irrefutability is not a virtue of a theory (as people often think) but a vice. Every genuine test of a theory is an attempt to falsify it or to refute it. Testability is falsifiability; but there are degrees of testability: some theories are more testable, more exposed to refutation, than others; they take, as it were, greater risks. Confirming evidence should not count except when it is the result of a genuine test of the theory, and this means that it can be presented as a serious but unsuccessful attempt to falsify the theory. (I now speak in such cases of "corroborating evidence".) Some genuinely testable theories, when


id: scientific-theory-20260505-6
file: data/en.wikipedia.org/wiki/Scientific_theory-6.md
category: reference
title: Scientific theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scientific_theory
date_saved: 2026-05-05T10:06:47.725273+00:00
instance: kb-cron
parent: scientific-theory-20260505-0
summary:
A theory is something other than myself. It may be set out on paper as a system of rules, and it is the more truly a theory the more completely it can be put down in such terms. Mathematical theory reaches the highest perfection in this respect. But even a geographical map fully embodies in itself a set of strict rules for finding one's way through a region of otherwise uncharted experience. Indeed, all theory may be regarded as a kind of map extended over space and time. A scientific theory can also be thought of as a book that captures the fundamental information about the world, a book that must be researched, written, and shared. In 1623, Galileo Galilei wrote: Philosophy [i.e. physics] is written in this grand book—I mean the universe—which stands continually open to our gaze, but it cannot be understood unless one first learns to comprehend the language and interpret the characters in which it is written. It is written in the language of mathematics, and its characters are triangles, circles, and other geometrical figures, without which it is humanly impossible to understand a single word of it; without these, one is wandering around in a


id: decompression-theory-20260505-0
file: data/en.wikipedia.org/wiki/Decompression_theory-0.md
category: reference
title: Decompression theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decompression_theory
date_saved: 2026-05-05T10:06:49.112339+00:00
instance: kb-cron
parent: decompression-theory-20260505-0
summary:
Decompression theory is the study and modelling of the transfer of the inert gas component of breathing gases from the gas in the lungs to the tissues and back during exposure to variations in ambient pressure. In the case of underwater diving and compressed air work, this mostly involves ambient pressures greater than the local surface pressure, but astronauts, high altitude mountaineers, and travellers in aircraft which are not pressurised to sea level pressure, are generally exposed to ambient pressures less than standard sea level atmospheric pressure. In all cases, the symptoms caused by decompression occur during or within a relatively short period of hours, or occasionally days, after a significant pressure reduction. The term "decompression" derives from the reduction in ambient pressure experienced by the organism and refers to both the reduction in pressure and the process of allowing dissolved inert gases to be eliminated from the tissues during and after this reduction in pressure. The uptake of gas by the tissues is in the dissolved state, and elimination also requires the gas to be dissolved, however a sufficient reduction in ambient pressure may cause bubble formation in the tissues, which can lead to tissue damage and the symptoms


id: decompression-theory-20260505-1
file: data/en.wikipedia.org/wiki/Decompression_theory-1.md
category: reference
title: Decompression theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decompression_theory
date_saved: 2026-05-05T10:06:49.112339+00:00
instance: kb-cron
parent: decompression-theory-20260505-0
summary:
=== Dissolved phase gas dynamics === Solubility of gases in liquids is influenced by the nature of the solvent liquid and the solute, the temperature, pressure, and the presence of other solutes in the solvent. Diffusion is faster in smaller, lighter molecules of which helium is the extreme example. Diffusivity of helium is 2.65 times faster than nitrogen. The concentration gradient, can be used as a model for the driving mechanism of diffusion. In this context, inert gas refers to a gas which is not metabolically active. Atmospheric nitrogen (N2) is the most common example, and helium (He) is the other inert gas commonly used in breathing mixtures for divers. Atmospheric nitrogen has a partial pressure of approximately 0.78 bar at sea level. Air in the alveoli of the lungs is diluted by saturated water vapour (H2O) and carbon dioxide (CO2), a metabolic product given off by the blood, and contains less oxygen (O2) than atmospheric air as some of it is taken up by the blood for metabolic use. The resulting partial pressure of nitrogen is about 0,758 bar. At atmospheric pressure the body tissues are therefore normally saturated with nitrogen at 0.758 bar (569 mmHg). At increased ambient


id: decompression-theory-20260505-2
file: data/en.wikipedia.org/wiki/Decompression_theory-2.md
category: reference
title: Decompression theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decompression_theory
date_saved: 2026-05-05T10:06:49.112339+00:00
instance: kb-cron
parent: decompression-theory-20260505-0
summary:
=== Bubble mechanics === Equilibrium of forces on the surface is required for a bubble to exist. The sum of the Ambient pressure and pressure due to tissue distortion, exerted on the outside of the surface, with surface tension of the liquid at the interface between the bubble and the surroundings must be balanced by the pressure on the inside of the bubble. This is the sum of the partial pressures of the gases inside due to the net diffusion of gas to and from the bubble. The force balance on the bubble may be modified by a layer of surface active molecules which can stabilise a microbubble at a size where surface tension on a clean bubble would cause it to collapse rapidly, and this surface layer may vary in permeability, so that if the bubble is sufficiently compressed it may become impermeable to diffusion. If the solvent outside the bubble is saturated or unsaturated, the partial pressure will be less than in the bubble, and the surface tension will be increasing the internal pressure in direct proportion to surface curvature, providing a pressure gradient to increase diffusion out of the bubble, effectively "squeezing the gas out of the


id: decompression-theory-20260505-3
file: data/en.wikipedia.org/wiki/Decompression_theory-3.md
category: reference
title: Decompression theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decompression_theory
date_saved: 2026-05-05T10:06:49.112339+00:00
instance: kb-cron
parent: decompression-theory-20260505-0
summary:
=== Isobaric counterdiffusion (ICD) === Isobaric counterdiffusion is the diffusion of gases in opposite directions caused by a change in the composition of the external ambient gas or breathing gas without change in the ambient pressure. During decompression after a dive this can occur when a change is made to the breathing gas, or when the diver moves into a gas filled environment which differs from the breathing gas. While not strictly speaking a phenomenon of decompression, it is a complication that can occur during decompression, and that can result in the formation or growth of bubbles without changes in the environmental pressure. Two forms of this phenomenon have been described by Lambertsen: Superficial ICD (also known as Steady State Isobaric Counterdiffusion) occurs when the inert gas breathed by the diver diffuses more slowly into the body than the inert gas surrounding the body. An example of this would be breathing air in an heliox environment. The helium in the heliox diffuses into the skin quickly, while the nitrogen diffuses more slowly from the capillaries to the skin and out of the body. The resulting effect generates supersaturation in certain sites of the superficial tissues and the formation of inert


id: decompression-theory-20260505-4
file: data/en.wikipedia.org/wiki/Decompression_theory-4.md
category: reference
title: Decompression theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decompression_theory
date_saved: 2026-05-05T10:06:49.112339+00:00
instance: kb-cron
parent: decompression-theory-20260505-0
summary:
Vascular bubbles formed in the systemic capillaries may be trapped in the lung capillaries, temporarily blocking them. If this is severe, the symptom called "chokes" may occur. If the diver has a patent foramen ovale (or a shunt in the pulmonary circulation), bubbles may pass through it and bypass the pulmonary circulation to enter the arterial blood. If these bubbles are not absorbed in the arterial plasma and lodge in systemic capillaries they will block the flow of oxygenated blood to the tissues supplied by those capillaries, and those tissues will be starved of oxygen. Moon and Kisslo (1988) concluded that "the evidence suggests that the risk of serious neurological DCI or early onset DCI is increased in divers with a resting right-to-left shunt through a PFO. There is, at present, no evidence that PFO is related to mild or late onset bends." Bubbles form within other tissues as well as the blood vessels. Inert gas can diffuse into bubble nuclei between tissues. In this case, the bubbles can distort and permanently damage the tissue. As they grow, the bubbles may also compress nerves as they grow causing pain. Extravascular or autochthonous[a] bubbles usually form in slow tissues such as


id: decompression-theory-20260505-5
file: data/en.wikipedia.org/wiki/Decompression_theory-5.md
category: reference
title: Decompression theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decompression_theory
date_saved: 2026-05-05T10:06:49.112339+00:00
instance: kb-cron
parent: decompression-theory-20260505-0
summary:
Two rather different concepts have been used for decompression modelling. The first assumes that dissolved gas is eliminated while in the dissolved phase, and that bubbles are not formed during asymptomatic decompression. The second, which is supported by experimental observation, assumes that bubbles are formed during most asymptomatic decompressions, and that gas elimination must consider both dissolved and bubble phases. Early decompression models tended to use the dissolved phase models, and adjusted them by more or less arbitrary factors to reduce the risk of symptomatic bubble formation. Dissolved phase models are of two main groups. Parallel compartment models, where several compartments with varying rates of gas absorption (half time), are considered to exist independently of each other, and the limiting condition is controlled by the compartment which shows the worst case for a specific exposure profile. These compartments represent conceptual tissues and are not intended to represent specific organic tissues, merely to represent the range of possibilities for the organic tissues. The second group uses serial compartments, where gas is assumed to diffuse through one compartment before it reaches the next. A recent variation on the serial compartment model is the Goldman interconnected compartment model (ICM). More recent models attempt


id: decompression-theory-20260505-6
file: data/en.wikipedia.org/wiki/Decompression_theory-6.md
category: reference
title: Decompression theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decompression_theory
date_saved: 2026-05-05T10:06:49.112339+00:00
instance: kb-cron
parent: decompression-theory-20260505-0
summary:
=== Tissue compartments === One attempt at a solution was the development of multi-tissue models, which assumed that different parts of the body absorbed and eliminated gas at different rates. These are hypothetical tissues which are designated as fast and slow to describe the rate of saturation. Each tissue, or compartment, has a different half-life. Real tissues will also take more or less time to saturate, but the models do not need to use actual tissue values to produce a useful result. Models with from one to 16 tissue compartments have been used to generate decompression tables, and dive computers have used up to 20 compartments. For example: Tissues with a high lipid content can take up a larger amount of nitrogen, but often have a poor blood supply. These will take longer to reach equilibrium, and are described as slow, compared to tissues with a good blood supply and less capacity for dissolved gas, which are described as fast. Fast tissues absorb gas relatively quickly, but will generally release it quickly during ascent. A fast tissue may become saturated in the course of a normal recreational dive, while a slow tissue may have absorbed only a small part of


id: decompression-theory-20260505-7
file: data/en.wikipedia.org/wiki/Decompression_theory-7.md
category: reference
title: Decompression theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decompression_theory
date_saved: 2026-05-05T10:06:49.112339+00:00
instance: kb-cron
parent: decompression-theory-20260505-0
summary:
==== The critical supersaturation approach ==== J.S. Haldane originally used a critical pressure ratio of 2 to 1 for decompression on the principle that the saturation of the body should at no time be allowed to exceed about double the air pressure. This principle was applied as a pressure ratio of total ambient pressure and did not take into account the partial pressures of the component gases of the breathing air. His experimental work on goats and observations of human divers appeared to support this assumption. However, in time, this was found to be inconsistent with incidence of decompression sickness and changes were made to the initial assumptions. This was later changed to a 1.58:1 ratio of nitrogen partial pressures. Further research by people such as Robert Workman suggested that the criterion was not the ratio of pressures, but the actual pressure differentials. Applied to Haldane's work, this would suggest that the limit is not determined by the 1.58:1 ratio but rather by the critical pressure difference of 0.58 atmospheres between tissue pressure and ambient pressure. Most Haldanean tables since the mid 20th century, including the Bühlmann tables, are based on the critical difference assumption. The M-value is the maximum


id: decompression-theory-20260505-8
file: data/en.wikipedia.org/wiki/Decompression_theory-8.md
category: reference
title: Decompression theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decompression_theory
date_saved: 2026-05-05T10:06:49.112339+00:00
instance: kb-cron
parent: decompression-theory-20260505-0
summary:
A saturation exposure is where the time exposed to pressure is sufficient for all tissues to reach equilibrium with the inert gases in the breathing mixture. For practical purposes this is usually taken as 6 times the half time of the slowest tissue in the model. === No-stop limits === A no-stop limit, also called no decompression limit (NDL) is the theoretical maximum dissolved gas content of each tissue compartment of the whole body, which can be decompressed directly to surface pressure at the chosen ascent rate used by the model, without a need to stop to outgas at any depth, which has an acceptable risk of developing symptomatic decompression sickness. No decompression limit is a misnomer as the ascent at the specified ascent rate is decompression, but the term has historical inertia and continues to be used. === Decompression ceiling, floor and window === Once the gas loading of one or more tissue compartments exceeds the maximum level accepted for the no-stop limit, there is a minimum depth to which the diver can ascend at the appropriate ascent rate, at an acceptable risk for decompression sickness. This depth is known as the decompression ceiling. It may be considered a


id: decompression-theory-20260505-9
file: data/en.wikipedia.org/wiki/Decompression_theory-9.md
category: reference
title: Decompression theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decompression_theory
date_saved: 2026-05-05T10:06:49.112339+00:00
instance: kb-cron
parent: decompression-theory-20260505-0
summary:
=== Residual inert gas === Gas bubble formation has been experimentally shown to significantly inhibit inert gas elimination. A considerable amount of inert gas will remain in the tissues after a diver has surfaced, even if no symptoms of decompression sickness occur. This residual gas may be dissolved or in sub-clinical bubble form, and will continue to outgas while the diver remains at the surface. If a repetitive dive is made, the tissues are preloaded with this residual gas which will make them saturate faster. In repetitive diving, the slower tissues can accumulate gas day after day, if there is insufficient time for the gas to be eliminated between dives. This can be a problem for multi-day multi-dive situations. Multiple decompressions per day over multiple days can increase the risk of decompression sickness because of the build up of asymptomatic bubbles, which reduce the rate of off-gassing and are not accounted for in most decompression algorithms. Consequently, some diver training organisations make extra recommendations such as taking "the seventh day off". == Decompression models in practice == === Deterministic models === Deterministic decompression models are a rule based approach to calculating decompression. These models work from the idea that "excessive"


id: decompression-theory-20260505-10
file: data/en.wikipedia.org/wiki/Decompression_theory-10.md
category: reference
title: Decompression theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decompression_theory
date_saved: 2026-05-05T10:06:49.112339+00:00
instance: kb-cron
parent: decompression-theory-20260505-0
summary:
==== Perfusion limited tissues and parallel tissue models ==== The assumption that perfusion is the limiting mechanism leads to a model comprising a group of tissues with varied rates of perfusion, but supplied by blood of approximately equivalent gas concentration. It is also assumed that there is no gas transfer between tissue compartments by diffusion. This results in a parallel set of independent tissues, each with its own rate of ingassing and outgassing dependent on the rate of blood flowing through the tissue. Gas uptake for each tissue is generally modelled as an exponential function, with a fixed compartment half-time, and gas elimination may also be modelled by an exponential function, with the same or a longer half time, or as a more complex function, as in the exponential-linear elimination model. The critical ratio hypothesis predicts that the development of bubbles will occur in a tissue when the ratio of dissolved gas partial pressure to ambient pressure exceeds a particular ratio for a given tissue. The ratio may be the same for all tissue compartments or it may vary, and each compartment is allocated a specific critical supersaturation ratio, based on experimental observations. John Scott Haldane introduced the concept of


id: decompression-theory-20260505-11
file: data/en.wikipedia.org/wiki/Decompression_theory-11.md
category: reference
title: Decompression theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decompression_theory
date_saved: 2026-05-05T10:06:49.112339+00:00
instance: kb-cron
parent: decompression-theory-20260505-0
summary:
For example, a diver ascends from a maximum depth of 60 metres (200 ft), where the ambient pressure is 7 bars (100 psi), to a decompression stop at 20 metres (66 ft), where the pressure is 3 bars (40 psi). The first Pyle stop would take place at the halfway pressure, which is 5 bars (70 psi) corresponding to a depth of 40 metres (130 ft). The second Pyle stop would be at 30 metres (98 ft). A third would be at 25 metres (82 ft) which is less than 9 metres (30 ft) below the first required stop, and therefore is omitted. The value and safety of deep stops additional to the decompression schedule derived from a decompression algorithm is unclear. Decompression experts have pointed out that deep stops are likely to be made at depths where ingassing continues for some slow tissues, and that the addition of deep stops of any kind should be included in the hyperbaric exposure for which the decompression schedule is computed, and not added afterwards, so that such ingassing of slower tissues can be taken into account. Deep stops performed during a dive where the decompression is calculated in real-time are simply part


id: decompression-theory-20260505-12
file: data/en.wikipedia.org/wiki/Decompression_theory-12.md
category: reference
title: Decompression theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decompression_theory
date_saved: 2026-05-05T10:06:49.112339+00:00
instance: kb-cron
parent: decompression-theory-20260505-0
summary:
In contrast to the independent parallel compartments of the Haldanean models, in which all compartments are considered risk bearing, the Goldman model posits a relatively well perfused "active" or "risk-bearing" compartment in series with adjacent relatively poorly perfused "reservoir" or "buffer" compartments, which are not considered potential sites for bubble formation, but affect the probability of bubble formation in the active compartment by diffusive inert gas exchange with the active compartment. During compression, gas diffuses into the active compartment and through it into the buffer compartments, increasing the total amount of dissolved gas passing through the active compartment. During decompression, this buffered gas must pass through the active compartment again before it can be eliminated. If the gas loading of the buffer compartments is small, the added gas diffusion through the active compartment is slow. The interconnected models predict a reduction in gas washout rate with time during decompression compared with the rate predicted for the independent parallel compartment model used for comparison. The Goldman model differs from the Kidd-Stubbs series decompression model in that the Goldman model assumes linear kinetics, where the K-S model includes a quadratic component, and the Goldman model considers only the central well-perfused compartment to


id: decompression-theory-20260505-13
file: data/en.wikipedia.org/wiki/Decompression_theory-13.md
category: reference
title: Decompression theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decompression_theory
date_saved: 2026-05-05T10:06:49.112339+00:00
instance: kb-cron
parent: decompression-theory-20260505-0
summary:
=== Probabilistic models === Probabilistic decompression models, also referred to as evidence-based decompression models, are designed to calculate the risk (or probability) of decompression sickness (DCS) occurring on a given decompression profile, based on actual outcomes of a statistically robust set of data. Statistical analysis is well suited to compressed air work in tunneling operations due to the large number of subjects undergoing similar exposures at the same ambient pressure and temperature, with similar workloads and exposure times, with the same decompression schedule. Large numbers of decompressions under similar circumstances have shown that it is not reasonably practicable to eliminate all risk of DCS, so it is necessary to set an acceptable risk, based on the other factors relevant to the application. For example, easy access to effective treatment in the form of hyperbaric oxygen treatment on site, or greater advantage to getting the diver out of the water sooner, may make a higher incidence acceptable, while interfering with work schedule, adverse effects on worker morale or a high expectation of litigation would shift acceptable incidence rate downward. Efficiency is also a factor, as decompression of employees occurs during working hours. These methods can vary the decompression stop depths and


id: decompression-theory-20260505-14
file: data/en.wikipedia.org/wiki/Decompression_theory-14.md
category: reference
title: Decompression theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decompression_theory
date_saved: 2026-05-05T10:06:49.112339+00:00
instance: kb-cron
parent: decompression-theory-20260505-0
summary:
Saturation decompression is a physiological process of transition from a steady state of full saturation with inert gas at raised pressure to standard conditions at normal surface atmospheric pressure. It is a long process during which inert gases are eliminated at a very low rate limited by the slowest affected tissues, and a deviation can cause the formation of gas bubbles which can produce decompression sickness. Most operational procedures rely on experimentally derived parameters describing a continuous slow decompression rate, which may depend on depth and gas mixture. In saturation diving all tissues are considered saturated and decompression which is safe for the slowest tissues will theoretically be safe for all faster tissues in a parallel model. Direct ascent from air saturation at approximately 7 msw produces venous gas bubbles but not symptomatic DCS. Deeper saturation exposures require decompression to saturation schedules. The safe rate of decompression from a saturation dive is controlled by the partial pressure of oxygen in the inspired breathing gas. The inherent unsaturation due to the oxygen window allows a relatively fast initial phase of saturation decompression in proportion to the oxygen partial pressure and then controls the rate of further decompression limited by the half-time


id: decompression-theory-20260505-15
file: data/en.wikipedia.org/wiki/Decompression_theory-15.md
category: reference
title: Decompression theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decompression_theory
date_saved: 2026-05-05T10:06:49.112339+00:00
instance: kb-cron
parent: decompression-theory-20260505-0
summary:
==== Effects of inert gas component changes ==== Gas switching during decompression on open circuit is done primarily to increase the partial pressure of oxygen to increase the oxygen window effect, while keeping below acute toxicity levels. It is well established both in theory and practice, that a higher oxygen partial pressure facilitates a more rapid and effective elimination of inert gas, both in the dissolved state and as bubbles. In closed circuit rebreather diving the oxygen partial pressure throughout the dive is maintained at a relatively high but tolerable level to reduce the ongassing as well as to accelerate offgassing of the diluent gas. Changes from helium-based diluents to nitrogen during ascent are desirable for reducing the use of expensive helium, but have other implications. It is unlikely that changes to nitrogen based decompression gas will accelerate decompression in typical technical bounce dive profiles, but there is some evidence that decompressing on helium-oxygen mixtures is more likely to result in neurological DCS, while nitrogen based decompression is more likely to produce other symptoms if DCS occurs. However, switching from helium rich to nitrogen rich decompression gas is implicated in inner ear DCS, connected with counter-diffusion effects. This risk can


id: decompression-theory-20260505-16
file: data/en.wikipedia.org/wiki/Decompression_theory-16.md
category: reference
title: Decompression theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decompression_theory
date_saved: 2026-05-05T10:06:49.112339+00:00
instance: kb-cron
parent: decompression-theory-20260505-0
summary:
=== Practical effectiveness of models === Bubble models for decompression were popular among technical divers in the early 2000s, although there was little data to support the effectiveness of the models in practice. Since then, several comparative studies have indicated relatively larger numbers of venous gas emboli after decompression based on bubble models, and one study reported a higher rate of decompression sickness. The deeper decompression stops earlier in the ascent appear to be less effective at controlling bubble formation than the hypotheses suggested. This failure may be due to continued ingassing of slower tissues during the extended time at greater depth, resulting in these tissues being more supersaturated at shallower depths. The optimal decompression strategy for deep bounce dives remains unknown (2016). The practical efficacy of gas switches from helium-based diluent to nitrox for accelerating decompression has not been demonstrated convincingly. These switches increase risk of inner ear decompression sickness due to counterdiffusion effects. Besides the basic dive profile and gas mixes, and the residual gas load from previous dives, three groups of factors are considered likely to have significant influence on decompression stress, the evolution of bubbles in the diver, and development of symptoms. These are exercise, before,


id: disease-theory-of-alcoholism-20260505-0
file: data/en.wikipedia.org/wiki/Disease_theory_of_alcoholism-0.md
category: reference
title: Disease theory of alcoholism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Disease_theory_of_alcoholism
date_saved: 2026-05-05T10:06:50.381723+00:00
instance: kb-cron
parent: disease-theory-of-alcoholism-20260505-0
summary:
The modern disease theory of alcoholism states that problem drinking is sometimes caused by a disease of the brain, characterized by altered brain structure and function. Today, alcohol use disorder (AUD) is used as a more scientific and suitable approach to alcohol dependence and alcohol-related problems. The largest association of physicians – the American Medical Association (AMA) – declared that alcoholism was an illness in 1956. In 1991, the AMA further endorsed the dual classification of alcoholism by the International Classification of Diseases under both psychiatric and medical sections. == Theory == Under the model of alcoholism, alcohol use disorder is viewed as chronic problem for which abstinence is required. A brain disease model of addiction, based on the extent of neuroadaptation and impaired control, is main position advanced for proposing a disease model of alcohol use disorder. However, if managed properly, damage to the brain can be stopped and to some extent reversed. In addition to problem drinking, the disease is characterized by symptoms including an impaired control over alcohol, compulsive thoughts about alcohol, and distorted thinking. Alcoholism can also lead indirectly, through excess consumption, to physical dependence on alcohol, and diseases such as cirrhosis of the liver. The


id: disease-theory-of-alcoholism-20260505-1
file: data/en.wikipedia.org/wiki/Disease_theory_of_alcoholism-1.md
category: reference
title: Disease theory of alcoholism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Disease_theory_of_alcoholism
date_saved: 2026-05-05T10:06:50.381723+00:00
instance: kb-cron
parent: disease-theory-of-alcoholism-20260505-0
summary:
My observations authorize me to say, that persons who have been addicted to them, should abstain from them suddenly and entirely. 'Taste not, handle not, touch not' should be inscribed upon every vessel that contains spirits in the house of a man, who wishes to be cured of habits of intemperance. Rush argued that "habitual drunkenness should be regarded not as a bad habit but as a disease", describing it as "a palsy of the will". Rush expounded his views in a book published in 1808. His views are described by Valverde, Levine Spode, and Perkins-McVey. Already in 1802 the prominent German physician Christoph Wilhelm Hufeland had published a book on the "brandy plague" stating that the "infection" with spirits makes it "inevitably necessary to drink ever more." Later he wrote an enthusiastic preface to the book On the addiction to drink and a rational cure of it by German-Russian physician C. von Brühl-Cramer. As Spode points out, this study marked the birth of a consistent "paradigm" of addiction as a mental illness, although it took many decades until this view was accepted. Perkins-McVey argues that Rush, Trotter, and Brühl-Cramer each independently developed their own disease theories of alcoholism as


id: disease-theory-of-alcoholism-20260505-2
file: data/en.wikipedia.org/wiki/Disease_theory_of_alcoholism-2.md
category: reference
title: Disease theory of alcoholism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Disease_theory_of_alcoholism
date_saved: 2026-05-05T10:06:50.381723+00:00
instance: kb-cron
parent: disease-theory-of-alcoholism-20260505-0
summary:
== Controlled drinking == The disease theory is often interpreted as implying that problem drinkers are incapable of returning to 'normal' problem free drinking, and therefore that treatment should focus on total abstinence. Some critics have used evidence of controlled drinking in formerly dependent drinkers to dispute the disease theory of alcoholism. The first major empirical challenge to this interpretation of the disease theory followed a 1962 study by Dr. D. L. Davies. Davies' follow-up of ninety-three problem drinkers found that seven of them were able to return to "controlled drinking" (less than seven drinks per day for at least seven years). Davies concluded that "the accepted view that no alcohol addict can ever again drink normally should be modified, although all patients should be advised to aim at total abstinence"; After the Davies study, several other researchers reported cases of problem drinkers returning to controlled drinking. In 1976, a major study commonly referred to as the RAND report, published evidence of problem drinkers learning to consume alcohol in moderation. The publication of the study renewed controversy over how people with a disease which reputedly leads to uncontrollable drinking could manage to drink controllably. Subsequent studies also reported evidence of


id: disease-theory-of-alcoholism-20260505-3
file: data/en.wikipedia.org/wiki/Disease_theory_of_alcoholism-3.md
category: reference
title: Disease theory of alcoholism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Disease_theory_of_alcoholism
date_saved: 2026-05-05T10:06:50.381723+00:00
instance: kb-cron
parent: disease-theory-of-alcoholism-20260505-0
summary:
== Current acceptance == Alcoholism is a disease with a known pathology and an established biomolecular signal transduction pathway which culminates in ΔFosB overexpression within the D1-type medium spiny neurons of the nucleus accumbens; when this overexpression occurs, ΔFosB induces the addictive state. In 2004, the World Health Organization published a detailed report on alcohol and other psychoactive substances entitled "Neuroscience of psychoactive substance use and dependence". It stated that this was the "first attempt by WHO to provide a comprehensive overview of the biological factors related to substance use and dependence by summarizing the vast amount of knowledge gained in the last 20-30 years. The report highlights the current state of knowledge of the mechanisms of action of different types of psychoactive substances, and explains how the use of these substances can lead to the development of dependence syndrome." The report states that "dependence has not previously been recognized as a disorder of the brain, in the same way that psychiatric and mental illnesses were not previously viewed as being a result of a disorder of the brain. However, with recent advances in neuroscience, it is clear that dependence is as much a disorder of the brain as any


id: effective-theory-20260505-0
file: data/en.wikipedia.org/wiki/Effective_theory-0.md
category: reference
title: Effective theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Effective_theory
date_saved: 2026-05-05T10:06:51.573632+00:00
instance: kb-cron
parent: effective-theory-20260505-0
summary:
In science, an effective theory is a deliberately limited scientific theory applicable under specific circumstances. In practice, all theories are effective theories, with the name "effective theory" being used to signal that the limitations are built in by design. == Examples == An early example is Galileo Galilei's theory of falling bodies. Using observed values, Galileo deduced that the height of a falling body can be accounted for by constant acceleration, written here in modern notation: d 2 z d t 2 = − g , {\displaystyle {\frac {d^{2}z}{dt^{2}}}=-g,} where t is the time, z is the vertical position of an object and g is gravitational acceleration near the surface of Earth. Within the scope of objects falling on Earth, this theory works well. However, as Isaac Newton discovered in his Newton's law of universal gravitation, a more elaborate but still effective theory, has more scope at the expense of additional complications. The next layer was Albert Einstein's general relativity, with more scope but even more complications. == Effective field theory == Effective field theory is a method used to describe physical theories when there is a hierarchy of scales. Effective field theories in physics can include quantum field theories


id: expectancy-theory-20260505-0
file: data/en.wikipedia.org/wiki/Expectancy_theory-0.md
category: reference
title: Expectancy theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_theory
date_saved: 2026-05-05T10:06:52.715379+00:00
instance: kb-cron
parent: expectancy-theory-20260505-0
summary:
Expectancy theory (or expectancy theory of motivation) proposes that an individual will behave or act in a certain way because they are motivated to select a specific behavior over others due to what they expect the result of that selected behavior will be. In essence, the motivation of the behavior selection is determined by the desirability of the outcome. However, at the core of the theory is the cognitive process of how an individual processes the different motivational elements. This is done before making the ultimate choice. The outcome is not the sole determining factor in making the decision of how to behave. Expectancy theory is a motivation theory concerned with mental processes regarding choice, or choosing. First proposed by Victor Vroom of the Yale School of Management in 1964, it aims to explain the processes that an individual undergoes to make choices. In relation to the study of organizational behavior, the theory stresses "the need for organizations to relate rewards directly to performance and to ensure that the rewards provided are deserved and wanted by the recipients". Vroom defines motivation as a process governing choices among alternative forms of voluntary activities, a process controlled by the individual. The individual


id: expectancy-theory-20260505-1
file: data/en.wikipedia.org/wiki/Expectancy_theory-1.md
category: reference
title: Expectancy theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_theory
date_saved: 2026-05-05T10:06:52.715379+00:00
instance: kb-cron
parent: expectancy-theory-20260505-0
summary:
=== Management === Victor Vroom's expectancy theory is one such management theory focused on motivation. According to Holdford and Lovelace-Elmore, Vroom asserts, "intensity of work effort depends on the perception that an individual's effort will result in a desired outcome". In order to enhance the performance-outcome tie, managers should use systems that tie rewards very closely to performance. Managers also need to ensure that the rewards provided are deserved and wanted by the recipients. In order to improve the effort-performance tie, managers should engage in training to improve their capabilities and improve their belief that added effort will in fact lead to better performance. Emphasizes self-interest in the alignment of rewards with employee's wants. Emphasizes the connections among expected behaviors, rewards and organizational goals Expectancy Theory, though well known in work motivation literature, is not as familiar to scholars or practitioners outside that field. === Computer users === Lori Baker-Eveleth and Robert Stone, University of Idaho in 2008 conducted an empirical study on 154 faculty members' reactions to the use of new software. It was found that ease of system use affects both self-efficacy (self-confidence) and anticipated usefulness. These in turn influenced the decision, or anticipated decision, to use the


id: expectancy-theory-20260505-2
file: data/en.wikipedia.org/wiki/Expectancy_theory-2.md
category: reference
title: Expectancy theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_theory
date_saved: 2026-05-05T10:06:52.715379+00:00
instance: kb-cron
parent: expectancy-theory-20260505-0
summary:
== Criticisms == Critics of the expectancy model include Graen, Lawler and Porter. Their criticisms of the theory were based upon the expectancy model being too simplistic in nature; these critics started making adjustments to Vroom's model. Edward Lawler claims that the simplicity of expectancy theory is deceptive because it assumes that if an employer makes a reward (such as a financial bonus or promotion) enticing enough, employees will increase their productivity to obtain the reward. However, this only works if the employees believe the reward is beneficial to their immediate needs. For example, a $2 increase in salary may not be desirable to an employee if the increase pushes him into a tax bracket in which he believes his net pay is actually reduced (a belief that is typically fallacious, especially in the United States). Similarly, a promotion that provides higher status but requires longer hours may be a deterrent to an employee who values evening and weekend time with their children. As an additional example, if a person in the armed forces or security agencies is promoted, there is the possibility that he or she will be transferred to other locations. In such cases, if the new posting


id: expectancy-violations-theory-20260505-0
file: data/en.wikipedia.org/wiki/Expectancy_violations_theory-0.md
category: reference
title: Expectancy violations theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_violations_theory
date_saved: 2026-05-05T10:06:53.972000+00:00
instance: kb-cron
parent: expectancy-violations-theory-20260505-0
summary:
Expectancy violations theory (EVT) is a theory of communication that analyzes how individuals respond to unanticipated violations of social norms and expectations. The theory was proposed by Judee K. Burgoon in the late 1970s and continued through the 1980s and 1990s as "nonverbal expectancy violations theory", based on Burgoon's research studying proxemics. Burgoon's work initially analyzed individuals' allowances and expectations of personal distance and how responses to personal distance violations were influenced by the level of liking and relationship to the violators. The theory was later changed to its current name when other researchers began to focus on violations of social behavior expectations beyond nonverbal communication. This theory sees communication as an exchange of behaviors, where one individual's behavior can be used to violate the expectations of another. Participants in communication will perceive the exchange either positively or negatively, depending upon an existing personal relationship or how favorably the violation is perceived. Violations of expectancies cause arousal and compel the recipient to initiate a series of cognitive appraisals of the violation. The theory predicts that expectancies influence the outcome of the communication interaction as either positive or negative and predicts that positive violations increase the attraction of the violator and


id: expectancy-violations-theory-20260505-1
file: data/en.wikipedia.org/wiki/Expectancy_violations_theory-1.md
category: reference
title: Expectancy violations theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_violations_theory
date_saved: 2026-05-05T10:06:53.972000+00:00
instance: kb-cron
parent: expectancy-violations-theory-20260505-0
summary:
=== Communicator reward valence === The communicator reward valence is an evaluation one makes about the person who committed a violation of expectancy. Em Griffin summarizes the concept behind communicator reward valence as "the sum of positive and negative attributes brought to the encounter plus the potential to reward or punish in the future". The social exchange theory explains that individuals seek to reward some and seek to avoid punishing others. When one individual interacts with another, Burgoon believes he or she will assess the "positive and negative attributes that person brings to the encounter". If the person has the ability to reward or punish the receiver in the future, then the person has a positive reward valence. Rewards simply refer to the person's ability to provide a want or need. It can be represented by several features, such as communicators with high social class, reputation, knowledge, positive emotional support, physical attractiveness, and so on. The term 'communicator reward valence' is used to describe the results of this assessment. For example, people will feel encouraged during conversation when the listener is nodding, making eye contact, and responding actively. Conversely, if the listener is avoiding eye contact, yawning, and texting, it


id: expectancy-violations-theory-20260505-2
file: data/en.wikipedia.org/wiki/Expectancy_violations_theory-2.md
category: reference
title: Expectancy violations theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_violations_theory
date_saved: 2026-05-05T10:06:53.972000+00:00
instance: kb-cron
parent: expectancy-violations-theory-20260505-0
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=== Propositions === After assessing expectancy, violation valence, and communicator reward valence of a given situation, it becomes possible to make rather specific predictions about whether the individual who perceived the violation will reciprocate or compensate the behavior in question. Guerrero and Burgoon noticed that predictable patterns develop when considering reward valence and violation valence together. Specifically, if the violation valence is perceived as positive and the communicator reward valence is also perceived as positive, the theory predicts individuals will reciprocate the positive behavior. Similarly, if one perceives the violation valence as negative and the communicator reward valence as negative, the theory again predicts that one will reciprocate the negative behavior. Thus, if a disliked coworker is grouchy and unpleasant, people will likely reciprocate and be unpleasant in return. Conversely, if one perceives a negative violation valence but views the communicator reward valence as positive, it is likely that the person will compensate for his or her partner's negative behavior. For example, imagine a supervisor appears sullen and throws a stack of papers in front of an employee. Rather than grunt back, EVT predicts that the employee will compensate for the boss's negativity, perhaps by asking if everything is okay.


id: expectancy-violations-theory-20260505-3
file: data/en.wikipedia.org/wiki/Expectancy_violations_theory-3.md
category: reference
title: Expectancy violations theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_violations_theory
date_saved: 2026-05-05T10:06:53.972000+00:00
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parent: expectancy-violations-theory-20260505-0
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Intimate distance: (0–18 inches) – This distance is for close, intimate encounters. Normally core family, close friends, lovers, or pets. People will normally share a unique level of comfort with one another. Personal distance: (18 inches – 4 feet) – Reserved for conversations with friends, extended family, associates, and group discussions. The personal distance will give each person more space compared with the intimate distance, but is still close enough to involve touching one another. Social distance: (4–10 feet) – This distance is reserved for newly formed groups, and new acquaintances and colleagues one may have just met. People generally do not engage physically with one another within this section. Public distance: (10 feet to infinity) – Reserved for a public setting with large audiences, strangers, speeches, and theaters. Many different cultures are influenced by proxemics in different ways and respond differently to the same situation. In some cultures, those who have not formed close relationships may greet each other with kisses on the cheek, engaging one another well within the intimate range of proxemics. In other cultures, a custom greeting is a handshake which maintains a physical separation but is well within personal distance. Across the proxemic zones, actions


id: expectancy-violations-theory-20260505-4
file: data/en.wikipedia.org/wiki/Expectancy_violations_theory-4.md
category: reference
title: Expectancy violations theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_violations_theory
date_saved: 2026-05-05T10:06:53.972000+00:00
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parent: expectancy-violations-theory-20260505-0
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==== Friendship ==== Expectations with friends formulate over time and are usually brought together by a series of observations of behavior and predictions on how that friend will act in the future. When these expectations are violated, it often can be damaging and dangerous for a close friendship. It can cause an end to the friendship and create a strong negative experience in that person's life. Over time, people might expect friends to act consistently around them until a violation to this expectation takes place. For example, when they begin "breaking promises or even acting in an inauthentic manner to impress others, can have aversive consequences for close relationships" (Cohen 2010). People expect their friends to act in a social manner and adhere to all of our personal rules they set in their minds, such as being nice, kind, considerate, and refraining from any comment that puts another down. This is a part of the personal rules with a personal friendship, though in a different setting with that individual around different people, the rules may be broken. While this might be an offense in one's eyes, it may not be offensive in the others. Each negative experience can deteriorate the


id: expectancy-violations-theory-20260505-5
file: data/en.wikipedia.org/wiki/Expectancy_violations_theory-5.md
category: reference
title: Expectancy violations theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_violations_theory
date_saved: 2026-05-05T10:06:53.972000+00:00
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parent: expectancy-violations-theory-20260505-0
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Expectancy violations happen frequently in romantic relationships. In relationships there is an unspoken expectation when interacting and that is the significant other will give their full undivided attention when in the presence of their significant other. As the new generation evolves, the face to face contact has changed. With the access use of phones and social media the attention of individuals has shifted to their devices and continues to become worse. Since there is access to many mobile devices, there has been an increase of lack of communication face to face. This has made it difficult for some relationships to grow and has created conflict because the expectation of attention has been shifted. "Individuals expect conversational partners to be moderately involved in an interaction (Burgoon, Newton, Walther, & Baesler, 1989). Within existing relationships, partners rely on one another to show interest and immediacy in interactions (White, 2008). However, the presence of cell phones and the expectation to be constantly available (Ling, 2012) impacts partners' abilities to give full attention to one another" (Miller-Ott, A., & Kelly, L. 2015). Regardless of where the romantic relationship takes place, people are likely to have negative valence about cell phone usage, including texting, viewing


id: expectancy-violations-theory-20260505-6
file: data/en.wikipedia.org/wiki/Expectancy_violations_theory-6.md
category: reference
title: Expectancy violations theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_violations_theory
date_saved: 2026-05-05T10:06:53.972000+00:00
instance: kb-cron
parent: expectancy-violations-theory-20260505-0
summary:
==== Stereotypes, Gender and Sexuality ==== A study on personality traits and gender-based stereotypes in perceived negotiation skills was conducted in 2024. The study found that women tend to perform better in same-sex negotiations than in opposite-sex negotiations, while no significant differences were observed for men-pointing to the detrimental effect of gender in negotiation. Negotiation outcomes were mostly one-sided in favor of high-powered negotiators when stereotypical masculine traits were displayed, whereas stereotypically feminine traits tended to produce win-win outcomes. When negotiators' behaviors counter gender-specific beliefs, negative expectancy violations occur, generating backlash and negatively affecting negotiators' outcomes. When facing an unexpected negotiation partner, the impact of a hiring manager's gender-role violation on job candidates become evident. Job candidate believed that hiring managers were more extreme in characteristics that violated gender-role expectations: agentic female hiring managers were seen as more agentic than their male peers, while communal male hiring managers were perceived as more communal than their female counterparts. Job candidates were also less comfortable with an agentic female hiring manager than with an agentic male hiring manager. Further negotiating with an agentic female hiring manager would result in the least favorable outcomes, whereas those negotiating with a communal hiring manager would


id: expectancy-violations-theory-20260505-7
file: data/en.wikipedia.org/wiki/Expectancy_violations_theory-7.md
category: reference
title: Expectancy violations theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_violations_theory
date_saved: 2026-05-05T10:06:53.972000+00:00
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parent: expectancy-violations-theory-20260505-0
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=== Human-Technology Interaction with AI and Chatbots === Researchers found that the communication style of chatbots can influence consumers' satisfaction, trust, and engagement in the context of service failure. This is demonstrated through interactions with social-oriented communication-style chatbots, which elevate the level of consumers' interaction satisfaction and behavioral intention. This study examined how the communication style of chatbots influences consumers' satisfaction, trust, and engagement in the context of service failure. Additionally, when consumers' expectations are violated to a higher level, chatbots using a socially oriented (vs. task-oriented) communication style are more likely to incite higher interaction satisfaction, trust, and patronage intention. Another study about chatbot interactions examined the opposing effects of response time in human-chatbot interaction. It was found that experienced users may find a delayed response time irritating because they are aware that a chatbot can answer instantly. The results also reveal that social presence, or the feeling of being there, mediates the effect of chatbot response time on usage intentions (the willingness of a person to use a particular product, service, or system). It was also found that when perceived social presence is low, skilled users have a higher usage intention than novice users. This means that users


id: expectancy-violations-theory-20260505-8
file: data/en.wikipedia.org/wiki/Expectancy_violations_theory-8.md
category: reference
title: Expectancy violations theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_violations_theory
date_saved: 2026-05-05T10:06:53.972000+00:00
instance: kb-cron
parent: expectancy-violations-theory-20260505-0
summary:
=== Computer-mediated communication and social media === As has previously been addressed, EVT has evolved tremendously over the years, expanding beyond its original induction when it focused on FtF communication and proxemics. The advancement of information and communications technology has provided tools for expressing oneself and conveying messages beyond just typing in text. As already discussed, arousal can divert one's attention or interest from a message to the source of the arousal. Virtual realities created online through computer-mediated communication (CMC), especially those which evoke strong visual presence through media, can increase arousal levels, such as those with high violent or sexual content. Just as people may use television viewing to increase or decrease arousal levels, people may use media in online communication to increase or decrease arousal levels. People may interact with others online by assuming the identities of avatars which may take on completely different, alternate personalities. The differences in perceived intimateness, co-presence, and emotionally-based trust can very significantly between avatar communication and other communication modalities such as text chat, audio, and audio-visual. The media options available to users when communicating with others online present a host of potential expectancy violations unique to CMC. The introduction of social media


id: expectancy-violations-theory-20260505-9
file: data/en.wikipedia.org/wiki/Expectancy_violations_theory-9.md
category: reference
title: Expectancy violations theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_violations_theory
date_saved: 2026-05-05T10:06:53.972000+00:00
instance: kb-cron
parent: expectancy-violations-theory-20260505-0
summary:
""Don't stalk' – and when you do, don't talk about it" Though an understanding exists among Facebook participants that users will use the site to keep track of the behavior of others in a number of ways, excessive monitoring is likely to be perceived as an expectancy violation. "Don't embarrass me with bad pictures" Users may have the ability to control which pictures they post on their own Facebook page, but they do not have the ability to control what others post. Posting and "tagging" unflattering pictures of others may create expectancy violations. "Don't mess up my profile" Several participants expressed annoyance of others who alter their profiles knowing that their alterations could be perceived negatively, though they did not mention changing their passwords or protecting themselves in other ways. "Choose an appropriate forum for messages" Messages can be sent between Facebook participants through 'Facebook messages', which are not public, or 'wall postings', which can be viewed by anyone specified in the user's privacy controls. Posting messages which may be perceived as private, embarrassing, or inappropriate to a wall posting can create expectancy violations. "Don't compete over number of friends" Facebook users maintain a running total of 'friends' on their


id: expectancy-violations-theory-20260505-10
file: data/en.wikipedia.org/wiki/Expectancy_violations_theory-10.md
category: reference
title: Expectancy violations theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_violations_theory
date_saved: 2026-05-05T10:06:53.972000+00:00
instance: kb-cron
parent: expectancy-violations-theory-20260505-0
summary:
=== In educational contexts === EVT posits that deviations from expected behavior can influence social judgments. In the context of teacher dress, formal attire aligns with expectations of a teacher's role, and such congruence typically results in favorable credibility assessments. The impact of clothing on expectations, where attire considered appropriate to the teaching context bolstered perceptions of a teacher's potential for student academic success. A mixed method study conducted in 2023 followed first generation college students and their social expectations for their transition to college. Overall students reported negative violations when it came to partying, making new friends, and strengthening new bonds. They also experienced positive violations when it came to stress and workload. Students who reported more negative violations also reported an overall more difficult transition period. Students who reported more positive violations reported an easier transition period. === Implications for teacher dress code === The implications of these studies are twofold: they reaffirm the importance of attire as a component of nonverbal communication within educational settings, and they highlight the potential for teacher attire to align with institutional norms and expectations to enhance educational outcomes. While the preference for formality in attire may vary by educational context, the


id: expectancy-violations-theory-20260505-11
file: data/en.wikipedia.org/wiki/Expectancy_violations_theory-11.md
category: reference
title: Expectancy violations theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_violations_theory
date_saved: 2026-05-05T10:06:53.972000+00:00
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parent: expectancy-violations-theory-20260505-0
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==== Student disclosures in college classroom ==== In 2013, Frisby and Sidelinger conducted a research about student disclosures in college classroom to examine what kinds of student disclosures would violate peers' expectations and their perceptions about the disclosers. According to the study, those who make inappropriate disclosures violate others' expectations most in a classroom environment. Inappropriate disclosures are described as high frequent, negative, offensive and irrelevant topics. Disclosers of inappropriate information are more likely to be described as incompetent students, and they are less likeable than students who disclose appropriate information that are related to course materials. ==== Students' expectations towards instructors in online classes ==== Taking EVT as a lens, Renee Bourdeaux and Lindsie Schoenack investigate students' reasons for taking online classes, their expectations towards instructors, and the derivation of expectations of instructors' behaviors. Research shows that students expect clarity, respect, and well-designed course accommodating to the online environment. Participants consider effective communication and improving learning as behaviors bringing positive results. However, unprofessional behaviors, such as lack of use of teaching tools decreasing the productivity of classes, lead to negative results. === Business communication crisis === EVT can also apply to everyday business interaction between long-term partners, new partners,


id: expectancy-violations-theory-20260505-12
file: data/en.wikipedia.org/wiki/Expectancy_violations_theory-12.md
category: reference
title: Expectancy violations theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_violations_theory
date_saved: 2026-05-05T10:06:53.972000+00:00
instance: kb-cron
parent: expectancy-violations-theory-20260505-0
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==== Business/Workplace Behaviors ==== In another study conducted in 2025, researchers examined the aftermath of an ethical violation and how family firms suffer more than non-family firms, as well as the reasons behind this. The presence of family firm information leads individuals to perceive the firm as more trustworthy. Although family firms may be seen as more trustworthy, the opposite effect can also be greater. effects as well. An identity threat could lead to a loss of benevolence beliefs and an avoidant reaction. Similarly, a decrease in perceived integrity and benevolence was significantly greater for family firms than for non-family firms. A 2024 study investigated the effects of greenwashing effects on corporate reputation and brand hate through environmental performance and green perceived risk. The findings show that consumer perceptions of greenwashing can damage a brand's image. Additionally, the study found that greenwashing negatively affects on corporate reputation through perceived environmental performance and green perceived risk. Reducing greenwashing practices can improve consumers' perceptions of corporate environmental performance. In 2024, another study explored whether religion mattered to angel investors specifically, the influence of religion on entrepreneurial investor decision-making. The results showed that religion contributes to social trust across multiple levels of analysis.


id: expectancy-violations-theory-20260505-13
file: data/en.wikipedia.org/wiki/Expectancy_violations_theory-13.md
category: reference
title: Expectancy violations theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_violations_theory
date_saved: 2026-05-05T10:06:53.972000+00:00
instance: kb-cron
parent: expectancy-violations-theory-20260505-0
summary:
=== Evaluation of media figures === Expectancy violations are tightly related to the changes of people's evaluation on their relationships with media figures. In 2010, Cohen made comparisons between relationships with friends and media figures in order to find similarities and differences of people's reactions when their expectations are violated in these two relationships. Violations were generally divided in three categories: social violations such as making offensive comments, trust violations such as making up stories about their life experience, and moral violations such as cheating in a marital relationship or drunk driving. Research indicated that in both friendships and relationships with media figures, social and trust violations are more offensive than moral violations. Specifically, people are more intolerable about moral violations from media figures than from their friends. According to the study, the reason for the intolerance is because relationships with media figures are relatively weak that people invest less on the relationships with media figures than on friendships. The type of media figures is also an important factor to determine the changes of closeness with media figures. People have different expectations to various types of media figures. Research discussed that moral violations negatively influence relationships with athletes, damaging their


id: expectancy-violations-theory-20260505-14
file: data/en.wikipedia.org/wiki/Expectancy_violations_theory-14.md
category: reference
title: Expectancy violations theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_violations_theory
date_saved: 2026-05-05T10:06:53.972000+00:00
instance: kb-cron
parent: expectancy-violations-theory-20260505-0
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=== Expectations of adults with autism === Expectancy violations theory has been applied in studies to determine whether people judge adults with autism as violating their expectations since people with autism can exhibit little-to-no eye contact, or facial expression, not recognize certain nonverbal cues, or utilize tones that non-autistic people may perceive as abnormal. In one manuscript replying to another study, Bishop describes communication deficits in autistic individuals as potentially violating one's expectations for social communication, thus being a form of expectation violation since people with autism can struggle with social communication. One study by Lim, Young, and Brewer hypothesized that people can incorrectly perceive autistic adults as having no credibility or being deceptive. They believed that due to expectancy violations theory, people will judge those who violate their expectations unfavorably in a negative light. They recorded videos of autistic and non autistic adults attempting to persuade the interviewer that they did not steal an envelope of money and the participants of the study were to judge whether they believed the individuals in the interview were lying or telling the truth. The results showed that the autistic people were perceived as deceptive and less credible than non autistic people in


id: expectancy-violations-theory-20260505-15
file: data/en.wikipedia.org/wiki/Expectancy_violations_theory-15.md
category: reference
title: Expectancy violations theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_violations_theory
date_saved: 2026-05-05T10:06:53.972000+00:00
instance: kb-cron
parent: expectancy-violations-theory-20260505-0
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=== Predictability and testability === EVT has undergone scrutiny for its attempt to provide a covering law for certain aspects of interpersonal communication. Some critics of EVT believe most interactions between individuals are extremely complex and there are many contingencies to consider within the theory. This makes the prediction of behavioral outcomes of a particular situation virtually impossible to consistently predict. Another critique of the theory is the assumption that expectancy violations are mostly highly consequential acts, negative in nature, and cause uncertainty to increase between communicators. In actuality, research shows expectancy violations vary in frequency, seriousness, and valence. While it is true that many expectancy violations carry a negative valence, numerous are positive and actually reduce uncertainty because they provide additional information within the parameters of the particular relationship, context, and communicators. ==== A First Look at Communication ==== Emory Griffin, the author of A First Look at Communication Theory, analyzed unpredictability in EVT. His test consisted in analyzing his interaction with four students who made various requests from him. The students were given the pseudonyms Andre, Belinda, Charlie and Dawn. They start with the letters A, B, C and D to represent the increasing distance between them and


id: expectancy-violations-theory-20260505-16
file: data/en.wikipedia.org/wiki/Expectancy_violations_theory-16.md
category: reference
title: Expectancy violations theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy_violations_theory
date_saved: 2026-05-05T10:06:53.972000+00:00
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parent: expectancy-violations-theory-20260505-0
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== Further use and development of the theory == The concept of social norms marketing follows expectancy violation in that it is based upon the notion that messages containing facts that vary from perception of the norm will create a positive expectancy violation. Advertising, strategic communications, and public relations base social norms campaigns on this position. Interaction adaptation theory further explores expectancy violations. Developed by Burgoon to take a more comprehensive look at social interaction, IAT posits that people enter into interactions with requirements, expectations, and desires. These factors influence both the initial behavior as well as the response behavior. When faced with behavior that meets an individual's needs, expectations, or desires, the response behavior will be positive. When faced with behavior that does not meet an individual's needs, expectations, or desires, he or she can respond either positively or negatively depending on the degree of violation and positive or negative valence of the relationship. Expectancies exert significant influence on people's interaction patterns, on their impressions of one another, and on the outcomes of their interactions. People who can assume that they are well regarded by their audience are safer engaging in violations and more likely to profit from doing


id: expectancy-value-theory-20260505-0
file: data/en.wikipedia.org/wiki/Expectancy-value_theory-0.md
category: reference
title: Expectancy-value theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy-value_theory
date_saved: 2026-05-05T10:06:55.181654+00:00
instance: kb-cron
parent: expectancy-value-theory-20260505-0
summary:
Expectancy–value theory has been developed in many different fields including education, health, communications, marketing and economics. Although the model differs in its meaning and implications for each field, the general idea is that there are expectations as well as values or beliefs that affect subsequent behavior. == Education model == === History and model overview === John William Atkinson developed the expectancy–value theory in the 1950s and 1960s in an effort to understand the achievement motivation of individuals. In the 1980s, Jacquelynne Eccles expanded this research into the field of education. According to expectancy–value theory, students' achievement and achievement related choices are most proximally determined by two factors: expectancies for success, and subjective task values. Expectancies refer to how confident an individual is in his or her ability to succeed in a task whereas task values refer to how important, useful, or enjoyable the individual perceives the task. Theoretical and empirical work suggests that expectancies and values interact to predict important outcomes such as engagement, continuing interest, and academic achievement. Other factors, including demographic characteristics, stereotypes, prior experiences, and perceptions of others' beliefs and behaviors affect achievement related outcomes indirectly through these expectancies and values. This model has most widely


id: expectancy-value-theory-20260505-1
file: data/en.wikipedia.org/wiki/Expectancy-value_theory-1.md
category: reference
title: Expectancy-value theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Expectancy-value_theory
date_saved: 2026-05-05T10:06:55.181654+00:00
instance: kb-cron
parent: expectancy-value-theory-20260505-0
summary:
=== History === Dr. Martin Fishbein is credited with developing the expectancy–value theory (EVT) in the early to mid-1970s. It is sometimes referred to as Fishbein's expectancy–value theory or simply expectancy–value model. The primary work typically cited by scholars referring to EVT is Martin Fishbein and Icek Ajzen's 1975 book called Belief, Attitude, Intention, and Behavior: An Introduction to Theory and Research. The seed work of EVT can be seen in Fishbein's doctoral dissertation, A Theoretical and Empirical Investigation of the Interrelation between Belief about an Object and the Attitude toward that Object (1961, UCLA) and two subsequent articles in 1962 and 1963 in the journal Human Relations. Fishbein's work drew on the writings of researchers such as Ward Edwards, Milton J. Rosenberg, Edward Tolman, and John B. Watson. === Concepts === EVT has three basic components. First, individuals respond to novel information about an item or action by developing a belief about the item or action. If a belief already exists, it can and most likely will be modified by new information. Second, individuals assign a value to each attribute that a belief is based on. Third, an expectation is created or modified based on the result of a


id: language-expectancy-theory-20260505-0
file: data/en.wikipedia.org/wiki/Language_expectancy_theory-0.md
category: reference
title: Language expectancy theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Language_expectancy_theory
date_saved: 2026-05-05T10:06:56.372148+00:00
instance: kb-cron
parent: language-expectancy-theory-20260505-0
summary:
Language expectancy theory (LET) is a theory of persuasion. The theory assumes language is a rules-based system, in which people develop expected norms as to appropriate language usage in given situations. Furthermore, unexpected linguistic usage can affect the receiver's behavior resulting from attitudes towards a persuasive message. == Background == Created by Michael Burgoon, a retired professor of medicine from the University of Arizona, and Gerald R. Miller, the inspiration for LET was sparked by Brooks' work on expectations of language in 1970. Burgoon, Jones and Stewart furthered the discussion with the idea of linguistic strategies and message intensity in an essay published in 1975. The essay linked linguistic strategies, or how a message is framed, to effective persuasive outcomes. The original work for the language expectation theory was published in 1978. Titled "An empirical test of a model of resistance to persuasion", it outlined the theory through 17s. == Expectations == The theory views language expectancies as enduring patterns of anticipated communication behavior which are grounded in a society's psychological and cultural norms. Such societal forces influence language and enable the identification of non-normative use; violations of linguistic, syntactic and semantic expectations will either facilitate or inhibit an audience's


id: language-expectancy-theory-20260505-1
file: data/en.wikipedia.org/wiki/Language_expectancy_theory-1.md
category: reference
title: Language expectancy theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Language_expectancy_theory
date_saved: 2026-05-05T10:06:56.372148+00:00
instance: kb-cron
parent: language-expectancy-theory-20260505-0
summary:
== The role of intensity == These propositions give rise to the impact of language intensity—defined by John Waite Bowers as a quality of language that "indicates the degree to which the speaker's attitude toward a concept deviates from neutrality"—on persuasive messages. Theorists have concentrated on two key areas: (1) intensity of language when it comes to gender roles and (2) credibility. The perceived credibility of a source can greatly affect a message's persuasiveness. Researchers found that credible sources can enhance their appeal by using intense language; however, less credible speakers are more persuasive with low-intensity appeals. Similarly, females are less persuasive than males when they use intense language because it violates the expected behavior, but are more persuasive when they use low-intensity language. Males, however, are seen as weak when they argue in a less intense manner. Theorists argue further that females and speakers perceived as having low credibility have less freedom in selecting message strategies and that the use of aggressive language negatively violates expectations. == Example == To better explain the theory we look at the expectations and societal norms for a man and a woman on their first date. If the man pushed for further physical


id: the-limits-of-individual-plasticity-20260505-0
file: data/en.wikipedia.org/wiki/The_Limits_of_Individual_Plasticity-0.md
category: reference
title: The Limits of Individual Plasticity
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/The_Limits_of_Individual_Plasticity
date_saved: 2026-05-05T10:06:57.512199+00:00
instance: kb-cron
parent: the-limits-of-individual-plasticity-20260505-0
summary:
"The Limits of Individual Plasticity" is a short essay written by the science fiction author H. G. Wells (21 September 1866 – 13 August 1946) in 1895. In it, Wells speculates his theories on the plasticity of animals, explaining that the default biological form of an animal may be altered in a way that it would continue to survive even if it, in any way, no longer resembles its inherent form. This could, according to Wells, theoretically be achieved through surgical or chemical modification. Wells was fully aware that surgical modification is only a physical change, and would not alter an animal's genetic blueprint. He made note that should an animal be surgically modified, its offspring would most likely retain its parent creature's original physical form. == Incorporation in novels == Wells presented many of his ideas from "The Limits of Individual Plasticity" in his 1896 science fiction novel, The Island of Doctor Moreau. In the novel, a shipwrecked Englishman named Edward Prendick is rescued from the sea and brought to a secluded island by a man named Montgomery, who reveals the island is owned and operated by an eminent British physiologist named Dr. Moreau. Moreau was shunned from the


id: membrane-theory-of-shells-20260505-0
file: data/en.wikipedia.org/wiki/Membrane_theory_of_shells-0.md
category: reference
title: Membrane theory of shells
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Membrane_theory_of_shells
date_saved: 2026-05-05T10:06:58.715178+00:00
instance: kb-cron
parent: membrane-theory-of-shells-20260505-0
summary:
The membrane theory of shells, or membrane theory for short, describes the mechanical properties of shells when twisting or under bending and assumes that bending moments are small enough to be negligible. The spectacular simplification of membrane theory makes possible the examination of a wide variety of shapes and supports, in particular, tanks and shell roofs. There are heavy penalties paid for this simplification, and such inadequacies are apparent through critical inspection, remaining within the theory, of solutions. However, this theory is more than a first approximation. If a shell is shaped and supported so as to carry the load within a membrane stress system it may be a desirable solution to the design problem, i.e., thin, light and stiff. == See also == Theory of plates and shells Stress resultants in plates and shells == References == == Literature == Ventsel, Eduard; Krauthammer, Theodor (24 August 2001). "Chapter 13. The Membrane Theory Of Shells". Thin Plates and Shells - Theory: Analysis, and Applications. CRC Press. pp. 349–372. doi:10.1201/9780203908723.ch13 (inactive 12 July 2025). ISBN 978-0-8247-0575-6. Retrieved 5 October 2014.{{cite book}}: CS1 maint: DOI inactive as of July 2025 (link) Practical industry example for plates and shell analysis - animated video


id: mosquito-malaria-theory-20260505-0
file: data/en.wikipedia.org/wiki/Mosquito-malaria_theory-0.md
category: reference
title: Mosquito-malaria theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mosquito-malaria_theory
date_saved: 2026-05-05T10:06:59.882762+00:00
instance: kb-cron
parent: mosquito-malaria-theory-20260505-0
summary:
Mosquito-malaria theory (or sometimes mosquito theory) was a scientific theory developed in the latter half of the 19th century that solved the question of how malaria was transmitted. The theory proposed that malaria was transmitted by mosquitoes, in opposition to the centuries-old medical dogma that malaria was due to bad air, or miasma. The first scientific idea was postulated in 1851 by Charles E. Johnson, who argued that miasma had no direct relationship with malaria. Although Johnson's hypothesis was forgotten, the arrival and validation of the germ theory of diseases in the late 19th century began to shed new lights. When Charles Louis Alphonse Laveran discovered that malaria was caused by a protozoan parasite in 1880, the miasma theory began to subside. An important discovery was made by Patrick Manson in 1877 that mosquitos could transmit human filarial parasite. Inferring from such novel discovery, Albert Freeman Africanus King proposed the hypothesis that mosquitoes were the source of malaria. In the early 1890s Manson himself began to formulate the complete hypothesis, which he eventually called the mosquito-malaria theory. According to Manson, malaria was transmitted from human to human by a mosquito. The theory was scientifically proved by Manson's confidant Ronald Ross


id: mosquito-malaria-theory-20260505-1
file: data/en.wikipedia.org/wiki/Mosquito-malaria_theory-1.md
category: reference
title: Mosquito-malaria theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mosquito-malaria_theory
date_saved: 2026-05-05T10:06:59.882762+00:00
instance: kb-cron
parent: mosquito-malaria-theory-20260505-0
summary:
=== Discovery of mosquito as disease vector === In the early 1880s, Laveran's germ theory of malaria was generally accepted by the science community. However pivotal problems still remained, such as what transmit the malarial parasites and how. The scientific clue emerged when a British medical officer Patrick Manson discovered for the first time that parasites were transmitted by mosquitoes. In 1877 while working in Amoy, a coastal town in China, he found that the mosquito Culex fatigans (now Culex quinquefasciatus) was the vector of the filarial roundworm that he called Filaria sanguinis hominis (but now Wuchereria bancrofti). His findings were published in the China Customs Medical Report in 1878, and relayed by Spencer Cobbold to the Linnean Society in London. This was the first direct evidence that mosquitoes could transmit microscopic parasites in humans, further suggesting that the same could be true in case of malaria. == King's theory == Based on the report of Manson's discovery, an American physician Albert Freeman Africanus King developed a proposition that malaria is transmitted by mosquitoes. He revealed his idea in 1881 to his colleagues C.V. Riley and L.O. Howard, who did not share the same opinion. Unfettered he developed the theory


id: mosquito-malaria-theory-20260505-2
file: data/en.wikipedia.org/wiki/Mosquito-malaria_theory-2.md
category: reference
title: Mosquito-malaria theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mosquito-malaria_theory
date_saved: 2026-05-05T10:06:59.882762+00:00
instance: kb-cron
parent: mosquito-malaria-theory-20260505-0
summary:
In 1894 Patrick Manson devised an ingenious procedure for detecting malarial parasites at different developmental stages from blood samples. This would later prove to be the tool for experimental proof of his theory. Manson demonstrated to and taught Ronald Ross the technique from which Ross became convinced of Laveran's germ theory. Trained and mentored by Manson, Ross returned to India in March 1895 to start his investigation. But to the dismay of Ross it was not an easy task. His first detection of malarial parasite from patients came only after two months of hard work. The disappointed Ross had to be encouraged by Manson calling the study as the "Holy Grail" of malaria research, and that Ross was the "Sir Galahad". After one and half years he made no significant progress. On 20 August 1897 he made a momentous discovery that some mosquitoes had malarial parasites in them. He had fed the blood of a malarial patient (Husein Khan) to different groups of mosquitoes four days before, and found that only one type (which he called "brown type" or more commonly "dappled-winged mosquitoes", not knowing the species, which in fact was Anopheles) acquired the malarial parasites in its stomach. This


id: nonequilibrium-theory-20260505-0
file: data/en.wikipedia.org/wiki/Nonequilibrium_theory-0.md
category: reference
title: Nonequilibrium theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Nonequilibrium_theory
date_saved: 2026-05-05T10:07:01.047591+00:00
instance: kb-cron
parent: nonequilibrium-theory-20260505-0
summary:
Nonequilibrium theory refers to the idea that ecosystems are not in a stable state, but instead are fluctuating from disturbances and pressures. Disturbances like disease, predators, climate change, fires, and others lead to shifts in ecosystem characteristics and prevent the return to equilibrium. Once shifted to an altered state, it can be difficult to return to an original state. This theory challenges traditional ideas of stability. Ecosystems are dynamic, ever changing structures that can be influenced by numerous characteristics.This perspective has important implications for conservation, prompting a shift toward strategies that embrace change, resilience, and adaptability rather than trying to preserve a single state. == Disturbance driven dynamics == Ecosystems are frequently influenced by a large variety of different disturbances. These disturbances can be periodic, unpredictable, with very different intensities. Disturbances may arise from natural events or human activities, each having the potential to drastically alter ecosystem structure and function. === Natural disturbance === Wildfire Hurricanes Tornadoes Floods and droughts Extreme temperature fluctuations === Human disturbance === Land use change (urbanization, crop land, deforestation) Pollution Invasive species introduction Overexploitation of resources == Multiple stable states == Depending on external pressures, ecosystems can exist under alternate stable states. Even under equal


id: scientific-socialism-20260505-0
file: data/en.wikipedia.org/wiki/Scientific_socialism-0.md
category: reference
title: Scientific socialism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Scientific_socialism
date_saved: 2026-05-05T10:07:02.303293+00:00
instance: kb-cron
parent: scientific-socialism-20260505-0
summary:
Scientific socialism in Marxism is the application of historical materialism to the development of socialism, as not just a practical and achievable outcome of historical processes, but the only possible outcome. It contrasts with utopian socialism by basing itself upon material conditions instead of concoctions and ideas, where "the final causes of all social changes and political revolutions are to be sought, not in men's brains, not in men's better insights into eternal truth and justice, but in changes in the modes of production and exchange. They are to be sought, not in the philosophy, but in the economics of each particular epoch." Fredrich Engels, who developed it alongside Karl Marx, described: To accomplish this act of universal emancipation [proletarian revolution and communism] is the historical mission of the modern proletariat. To thoroughly comprehend the historical conditions and thus the very nature of this act, to impart to the now oppressed proletarian class a full knowledge of the conditions and of the meaning of the momentous act it is called upon to accomplish, this is the task of the theoretical expression of the proletarian movement, scientific Socialism. The term's modern meaning is based almost totally on Engels's book Socialism: Utopian


id: youngest-toba-eruption-20260505-0
file: data/en.wikipedia.org/wiki/Youngest_Toba_eruption-0.md
category: reference
title: Youngest Toba eruption
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Youngest_Toba_eruption
date_saved: 2026-05-05T10:07:17.793231+00:00
instance: kb-cron
parent: youngest-toba-eruption-20260505-0
summary:
The Toba eruption (also called the Toba supereruption and the Youngest Toba eruption) was a large eruption that occurred around 74,000 years ago, during the Late Pleistocene, at the site of present-day Lake Toba, in Sumatra, Indonesia. It was the last in a series of at least four caldera-forming eruptions there, the earlier known caldera having formed about 1.2 million years ago. This, the last eruption, had an estimated volcanic explosivity index of 8, making it the largest known explosive volcanic eruption in the Quaternary, and one of the largest known explosive eruptions in the Earth's history. == Eruption == === Chronology of the Toba eruption === The exact date of the eruption is unknown, but the pattern of ash deposits suggests that it occurred during the northern summer because only the summer monsoon could have deposited Toba ashfall in the South China Sea. The eruption lasted perhaps 9 to 14 days. The most recent two high-precision argon–argon datings dated the eruption to 73,880 ± 320 and 73,700 ± 300 years ago. Five distinct magma bodies were activated within a few centuries before the eruption. The eruption commenced with small and limited air-fall and was directly followed by the main


id: youngest-toba-eruption-20260505-1
file: data/en.wikipedia.org/wiki/Youngest_Toba_eruption-1.md
category: reference
title: Youngest Toba eruption
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Youngest_Toba_eruption
date_saved: 2026-05-05T10:07:17.793231+00:00
instance: kb-cron
parent: youngest-toba-eruption-20260505-0
summary:
==== Possible climate records of the eruption ==== While the Toba eruption occurred in the backdrop of the rapid climate transitions of GS20 and MIS 4, triggered by changes in ocean currents and insolation, whether the eruption played any role in accelerating these events is much more heavily debated. South China Sea marine records of climate, sampled at every centennial interval, shows 1 °C (1.8 °F) cooling above the Toba ash layer for a thousand years but the authors concede that it may just be GS20. Arabian Sea marine records confirm that Toba ash occurred after the onset of GS20 but also that GS20 is not colder than GS21 in the records, from which authors conclude that the eruption did not intensify GS20 cooling. Dense sampling of environmental records, at every 6–9-year interval, in Lake Malawi, show no cooling-induced change in lake ecology and in grassy woodlands after the deposition of Toba ash, but cooling-forced aridity killed high-elevation afromontane forests. The Lake Malawi studies concluded that the environmental effects of the eruption were mild and limited to less than a decade in East Africa, but these studies are questioned due to sediment mixing which would have diminished the cooling signal.


id: youngest-toba-eruption-20260505-2
file: data/en.wikipedia.org/wiki/Youngest_Toba_eruption-2.md
category: reference
title: Youngest Toba eruption
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Youngest_Toba_eruption
date_saved: 2026-05-05T10:07:17.793231+00:00
instance: kb-cron
parent: youngest-toba-eruption-20260505-0
summary:
==== Human demographic history ==== Recent analyses apply Markov models to the complete set of genetic material to infer human population history. In non-African populations, studies recover a long-term steep decline in numbers starting 200 kyr and reaching the lowest point around 40–60 kyr. During this bottleneck non-African populations experienced 5- to 15-fold reduction, with an effective population size of only 1,000–3,000 individuals by 50 kyr, consistent with the earliest mtDNA studies. This severe non-African contraction is consistent with a founder effect caused by Out-of-Africa dispersal. As a small group with a size of a few thousand people migrated from the African continent into the Near East, the drastic reduction in numbers imprinted on non-African genomic diversity. Genetic analysis identified 56 selective sweeps related to cold adaptations in non-African populations, of which 31 sweeps occurred during 72–97 kyr. This event of closely timed selections is named the "Arabian Standstill" and may have been caused by the severe cold arid conditions from the onset of MIS 4 and exacerbated by the Toba super-eruption. African populations experienced a slightly earlier, milder bottleneck and recovered earlier. Estimated effective population size based on samples from the Luhya and Maasai people attained their lowest numbers


id: youngest-toba-eruption-20260505-3
file: data/en.wikipedia.org/wiki/Youngest_Toba_eruption-3.md
category: reference
title: Youngest Toba eruption
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Youngest_Toba_eruption
date_saved: 2026-05-05T10:07:17.793231+00:00
instance: kb-cron
parent: youngest-toba-eruption-20260505-0
summary:
Population Bottlenecks and Volcanic Winter "Toba Volcano by George Weber". Archived from the original on April 22, 2011. Retrieved June 1, 2006. "The proper study of mankind" – Article in The Economist Homepage of Professor Stanley H. Ambrose, including bibliographic information on the two papers he has published on the Toba catastrophe theory Mount Toba: Late Pleistocene human population bottlenecks, volcanic winter, and differentiation of modern humans by Professor Stanley H. Ambrose, Department of Anthropology, University Of Illinois, Urbana, USA; Extract from "Journal of Human Evolution" [1998] 34, 623–651 Journey of Mankind by The Bradshaw Foundation – includes discussion on Toba eruption, DNA and human migrations Geography Predicts Human Genetic Diversity ScienceDaily (Mar. 17, 2005) – By analyzing the relationship between the geographic location of current human populations in relation to East Africa and the genetic variability within these populations, researchers have found new evidence for an African origin of modern humans. Out of Africa – Bacteria, As Well: Homo Sapiens And H. Pylori Jointly Spread Across The Globe ScienceDaily (Feb. 16, 2007) – When man made his way out of Africa some 60,000 years ago to populate the world, he was not alone: He was accompanied by the bacterium


id: skepticism-20260505-0
file: data/en.wikipedia.org/wiki/Skepticism-0.md
category: reference
title: Skepticism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Skepticism
date_saved: 2026-05-05T10:07:19.331375+00:00
instance: kb-cron
parent: skepticism-20260505-0
summary:
Skepticism (US) or scepticism (UK) is a questioning attitude or doubt toward knowledge claims that are seen as mere belief or dogma. For example, if a person is skeptical about claims made by their government about an ongoing war then the person doubts that these claims are accurate. In such cases, skeptics normally recommend not disbelief but suspension of belief, i.e. maintaining a neutral attitude that neither affirms nor denies the claim. This attitude is often motivated by the impression that the available evidence is insufficient to support the claim. Formally, skepticism is a topic of interest in philosophy, particularly epistemology. More informally, skepticism as an expression of questioning or doubt can be applied to any topic, such as politics, religion, or pseudoscience. It is often applied within restricted domains, such as morality (moral skepticism), atheism (skepticism about the existence of God), or the supernatural. Some theorists distinguish "good" or moderate skepticism, which seeks strong evidence before accepting a position, from "bad" or radical skepticism, which wants to suspend judgment indefinitely. Philosophical skepticism is one form of skepticism. It rejects knowledge claims that seem certain from the perspective of common sense. Radical forms of philosophical skepticism deny that "knowledge or


id: skepticism-20260505-1
file: data/en.wikipedia.org/wiki/Skepticism-1.md
category: reference
title: Skepticism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Skepticism
date_saved: 2026-05-05T10:07:19.331375+00:00
instance: kb-cron
parent: skepticism-20260505-0
summary:
== Types == Various types of skepticism have been discussed in the academic literature. Skepticism is usually restricted to knowledge claims on one particular subject, which is why its different forms can be distinguished based on the subject. For example, religious skeptics distrust religious doctrines and moral skeptics raise doubts about accepting various moral requirements and customs. Skepticism can also be applied to knowledge in general. However, this attitude is usually only found in some forms of philosophical skepticism. A closely related classification distinguishes based on the source of knowledge, such as skepticism about perception, memory, or intuition. A further distinction is based on the degree of the skeptical attitude. The strongest forms assert that there is no knowledge at all or that knowledge is impossible. Weaker forms merely state that one can never be absolutely certain. Some theorists distinguish between a good or healthy form of moderate skepticism in contrast to a bad or unhealthy form of radical skepticism. On this view, the "good" skeptic is a critically minded person who seeks strong evidence before accepting a position. The "bad" skeptic, on the other hand, wants to "suspend judgment indefinitely... even in the face of demonstrable truth". Another categorization


id: skepticism-20260505-2
file: data/en.wikipedia.org/wiki/Skepticism-2.md
category: reference
title: Skepticism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Skepticism
date_saved: 2026-05-05T10:07:19.331375+00:00
instance: kb-cron
parent: skepticism-20260505-0
summary:
There were two major schools of skepticism in the ancient Greek and Roman world. The first was Pyrrhonism, founded by Pyrrho of Elis (c. 360–270 BCE). The second was Academic Skepticism, so-called because its two leading defenders, Arcesilaus (c. 315–240 BCE) who initiated the philosophy, and Carneades (c. 217–128 BCE), the philosophy's most famous proponent, were heads of Plato's Academy. Pyrrhonism's aims are psychological. It urges suspension of judgment (epoche) to achieve mental tranquility (ataraxia). The Academic Skeptics denied that knowledge is possible (acatalepsy). The Academic Skeptics claimed that some beliefs are more reasonable or probable than others, whereas Pyrrhonian skeptics argue that equally compelling arguments can be given for or against any disputed view. Nearly all the writings of the ancient skeptics are now lost. Most of what we know about ancient skepticism is from Sextus Empiricus, a Pyrrhonian skeptic who lived in the second or third century CE. His works contain a lucid summary of stock skeptical arguments. Ancient skepticism faded out during the late Roman Empire, particularly after Augustine (354–430 CE) attacked the skeptics in his work Against the Academics (386 CE). There was little knowledge of, or interest in, ancient skepticism in Christian Europe during the


id: skepticism-20260505-3
file: data/en.wikipedia.org/wiki/Skepticism-3.md
category: reference
title: Skepticism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Skepticism
date_saved: 2026-05-05T10:07:19.331375+00:00
instance: kb-cron
parent: skepticism-20260505-0
summary:
A scientific or empirical skeptic is one who questions beliefs on the basis of scientific understanding and empirical evidence. Scientific skepticism may discard beliefs pertaining to purported phenomena not subject to reliable observation and thus not systematic or empirically testable. Most scientists, being scientific skeptics, test the reliability of certain kinds of claims by subjecting them to systematic investigation via the scientific method. As a result, a number of ostensibly scientific claims are considered to be "pseudoscience" if they are found to improperly apply or to ignore the fundamental aspects of the scientific method. === Auditing === Professional skepticism is an important concept in auditing. It requires an auditor to have a "questioning mind", to make a critical assessment of evidence, and to consider the sufficiency of the evidence. == See also == == Notes == == Sources == Butchvarov, Panayot (1998). Skepticism About the External World. Oxford University Press. Hönigswald, Richard (2008) [1914]. Die Skepsis in Philosophie und Wissenschaft. Göttingen: Edition Ruprecht. ISBN 978-3767530560. Keeton, Morris T. (1962). "skepticism". In Runes, Dagobert D. (ed.). Dictionary of Philosophy. Totowa, N.J.: Littlefield, Adams, and Company. pp. 277–278. Le Morvan, P. (March 2011). "Healthy Skepticism and Practical Wisdom" (PDF). Logos & Episteme.


id: betteridge-s-law-of-headlines-20260505-0
file: data/en.wikipedia.org/wiki/Betteridge's_law_of_headlines-0.md
category: reference
title: Betteridge's law of headlines
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Betteridge's_law_of_headlines
date_saved: 2026-05-05T10:07:20.500979+00:00
instance: kb-cron
parent: betteridge-s-law-of-headlines-20260505-0
summary:
Betteridge's law of headlines is an adage that states: "Any headline that ends in a question mark can be answered by the word no." It is based on the assumption that if the publishers were confident that the answer was yes, they would have presented it as an assertion; by presenting it as a question, they are not accountable for whether it is correct or not. The law is named after Ian Betteridge, a British technology journalist who wrote about it in 2009. The maxim has been cited by other names since 1991, when a published compilation of Murphy's law variants called it "Davis's law", a name that also appears online without any explanation of who Davis was. It has also been referred to as the "journalistic principle" and in 2007 was referred to in commentary as "an old truism among journalists". == History == Betteridge's name became associated with the concept after he discussed it in a February 2009 article, which examined a previous TechCrunch article that carried the headline "Did Last.fm Just Hand Over User Listening Data to the RIAA?": This story is a great demonstration of my maxim that any headline which ends in a question mark


id: betteridge-s-law-of-headlines-20260505-1
file: data/en.wikipedia.org/wiki/Betteridge's_law_of_headlines-1.md
category: reference
title: Betteridge's law of headlines
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Betteridge's_law_of_headlines
date_saved: 2026-05-05T10:07:20.500979+00:00
instance: kb-cron
parent: betteridge-s-law-of-headlines-20260505-0
summary:
== Question headlines == Phrasing headlines as questions is a tactic employed by newspapers that do not "have the facts required to buttress the nut graph". Roger Simon characterized the practice as justifying "virtually anything, no matter how unlikely", giving "Hillary to Replace Biden on Ticket?" and "Romney to Endorse Gay Marriage Between Corporations?" as hypothetical examples of such a practice. Many question headlines were used, for example, in reporting of Bharatiya Janata Party in-fighting in 2004, because no politicians went on record to confirm or deny facts, such as "Is Venkaiah Naidu on his way out?" Because this implication is known to readers, guides giving advice to newspaper editors state that so-called "question heads" should be used sparingly. Freelance writer R. Thomas Berner calls them "gimmickry". Grant Milnor Hyde observed that they give the impression of uncertainty in a newspaper's content. When Linton Andrews worked at the Daily Mail after the First World War, one of the rules set by Lord Northcliffe was to avoid question headlines, unless the question itself reflected a national issue. Question headlines are not legally sound when it comes to avoiding defamation. The Supreme Court of Oklahoma held in 1913, in its decision in


id: doubting-antiquity-school-20260505-0
file: data/en.wikipedia.org/wiki/Doubting_Antiquity_School-0.md
category: reference
title: Doubting Antiquity School
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Doubting_Antiquity_School
date_saved: 2026-05-05T10:07:21.630643+00:00
instance: kb-cron
parent: doubting-antiquity-school-20260505-0
summary:
The Doubting Antiquity School or Yigupai (Chinese: 疑古派; pinyin: Yígǔpài; Wade–Giles: I-ku-p'ai) refers to a group of scholars and writers in Chinese academia, starting during the New Culture Movement (mid-1910s to 1920s), who applied a critical historiographical approach to Chinese historical sources. They put forward theories doubting the authenticity of texts and narratives that, in traditional Chinese historiography, were often accepted as authentic. Hu Shih studied in the West and was deeply influenced by Western thought. He then argued in Peking University that Chinese written history was not credible before the Eastern Zhou period without critical examination. This view was accepted by his students Fu Sinian and especially Gu Jiegang, who further advanced the position that "our traditional knowledge of Chinese antiquity was built up in successive strata, but in an order exactly the reverse of the actual occurrence." Most of their criticism concerns the authenticity of pre-Qin texts and deals with questions put forward by the past dynastic writers, as well as other subjects. Hu Shih initiated the critical movement, with his pupil Gu Jiegang and his friend Qian Xuantong continuing this school of thought. Their writings also had influence on many western sinologists, including Bernhard Karlgren and Samuel


id: doubting-antiquity-school-20260505-1
file: data/en.wikipedia.org/wiki/Doubting_Antiquity_School-1.md
category: reference
title: Doubting Antiquity School
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Doubting_Antiquity_School
date_saved: 2026-05-05T10:07:21.630643+00:00
instance: kb-cron
parent: doubting-antiquity-school-20260505-0
summary:
== Criticism == The Doubting Antiquity School's opinion and claims were not universally accepted by other schools in the 1920s. Major critics of the Doubting Antiquity School were historians from the Historiography and Geography School (史地學派) of the National Central University in Nanjing and the academics associated with the academic journal Critical Review, termed the Xueheng School. The major opposition included Chu Coching, Liu Yizheng, Liang Qichao, Wang Guowei, Chen Yinque, and Miao Fenglin. These historians claimed that the many hypotheses of the Doubting Antiquity School were radical nationalist revisionism influenced by the May Fourth Movement and New Culture Movement, which aimed to abolish Chinese tradition, as well as that some claims of the Doubting Antiquity School, such as Sino-Babylonianism, were based on assumptions without any archaeological evidence. Chinese writer Lu Xun dismissed the Doubting Antiquity School and their publication Gushibian (古史辨, Debates on Ancient History). He argued that the real intention behind the Doubting Antiquity School was to aggressively demolish the Chinese imperial legacy, so much so that they would reject real historiography. Much archaeological evidence discovered in the 20th century, such as Yinxu and Taosi, proved some of the Doubting Antiquity School's claims to be incorrect. Zhang Guoan


id: escaping-the-rabbit-hole-20260505-0
file: data/en.wikipedia.org/wiki/Escaping_the_Rabbit_Hole-0.md
category: reference
title: Escaping the Rabbit Hole
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Escaping_the_Rabbit_Hole
date_saved: 2026-05-05T10:07:22.876404+00:00
instance: kb-cron
parent: escaping-the-rabbit-hole-20260505-0
summary:
Escaping the Rabbit Hole: How to Debunk Conspiracy Theories Using Facts, Logic, and Respect is a non-fiction book by Mick West that describes a method for helping people disengage from conspiratorial beliefs through patient dialogue, clear evidence, and an emphasis on trust building. Skyhorse Publishing released the first edition in 2018. A revised and updated edition appeared in 2023 with new case material on the COVID-19 pandemic, election fraud narratives, QAnon, and contemporary UFO claims. The work combines practical communication tactics with case studies drawn from West's investigations on the Metabunk forum. == Background == West is a science writer and investigator who founded Metabunk, an online forum focused on analyzing extraordinary claims. The book emerged from a decade of moderating and documenting conversations with believers and former believers, which shaped the focus on respectful engagement, calibration of claims to evidence, and attention to the social dynamics around conspiracist communities. An excerpt from the book appeared in Salon before publication, outlining steps for approaching a friend who believes a conspiracy theory, including establishing common ground, isolating specific points of disagreement, and agreeing on shared standards of evidence. == Contents == The first edition sets out a communication framework that prioritizes


id: local-skepticism-20260505-0
file: data/en.wikipedia.org/wiki/Local_skepticism-0.md
category: reference
title: Local skepticism
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Local_skepticism
date_saved: 2026-05-05T10:07:24.030944+00:00
instance: kb-cron
parent: local-skepticism-20260505-0
summary:
Local skepticism is the view that one cannot possess knowledge in some particular domain. It contrasts with global skepticism (also known as absolute skepticism or universal skepticism), the view that one cannot know anything at all. == Examples of local skepticism == Moral skepticism is the belief that moral knowledge is either nonexistent or unattainable. Metaphysical skepticism, often called external world skepticism, is the denial of metaphysical knowledge. This belief is generally said to follow from the argument that material knowledge can only be attained through our perception of the world, and that our senses which constitute that perception do not necessarily correspond with any actual state of affairs. See also: subjective idealism. Theological skepticism it is the view that we cannot know for certain whether one or more deities exist. A theological skeptic may be an atheist, theist, or agnostic. == Notes == == Further reading == The Impossibility of Local Skepticism by Stephen Maitzen -- a critique of the possibility of local skepticism Theory of Knowledge, notes by Richard Feldman, University of Rochester


id: reasonable-doubt-20260505-0
file: data/en.wikipedia.org/wiki/Reasonable_doubt-0.md
category: reference
title: Reasonable doubt
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Reasonable_doubt
date_saved: 2026-05-05T10:07:25.218620+00:00
instance: kb-cron
parent: reasonable-doubt-20260505-0
summary:
Beyond (a) reasonable doubt is a legal standard of proof required to reach a criminal conviction in most adversarial legal systems. It is a higher standard of proof than the standard of balance of probabilities (US English: preponderance of the evidence) commonly used in civil cases. The prosecution bears the burden of presenting compelling evidence that establishes guilt beyond a reasonable doubt; if the trier of fact is not convinced to that standard, the accused is entitled to an acquittal. The standard is now widely accepted in criminal justice systems throughout common law jurisdictions. == In practice == Because the defendant is presumed innocent, prosecutors must prove each element of the crime charged beyond a reasonable doubt in order to obtain a conviction. This means the evidence must leave little actual doubt in the mind of the judge or jury that the defendant committed the alleged offense. Unreasonable or purely speculative doubts are excluded, whereas doubts grounded in tangible conflicts within the evidence or its sufficiency warrant an acquittal. In many jurisdictions, the phrase "reasonable doubt" remains purposefully undefined in jury instructions to reduce confusion, although critics argue that the lack of a clear definition may itself cause confusion. Academic


id: anita-superson-20260505-0
file: data/en.wikipedia.org/wiki/Anita_Superson-0.md
category: reference
title: Anita Superson
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Anita_Superson
date_saved: 2026-05-05T10:07:26.369349+00:00
instance: kb-cron
parent: anita-superson-20260505-0
summary:
Anita Superson is an American philosopher who is a professor of philosophy at the University of Kentucky. She was also the visiting Churchill Humphrey and Alex P. Humphrey Professor of Feminist Philosophy at the University of Waterloo during the winter term of 2013. == Education and career == Superson received a bachelor's in biology from DePaul University in 1981 and went on to receive a master's in philosophy (with a concentration in medical ethics) from the University of Tennessee, Knoxville in 1985 and a doctorate in philosophy from the University of Illinois at Chicago in 1989. Superson is currently a professor of philosophy at the University of Kentucky, where she has held an appointment since 1992. She is an affiliated faculty member of the Gender and Women's Studies Department at the University of Kentucky. She also holds the visiting Churchill Humphrey and Alex P. Humphrey Professorship in Feminist Philosophy at the University of Waterloo for the winter of 2013. She also held a visiting professorship at the University of Michigan, Ann Arbor in 2008. Before her current appointments, she held an assistant professorship at Kansas State University, and also taught at the University of Illinois at Chicago and the University


id: am-d-e-all-on-20260505-0
file: data/en.wikipedia.org/wiki/Amédée_Alléon-0.md
category: reference
title: Amédée Alléon
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Amédée_Alléon
date_saved: 2026-05-05T10:07:28.293449+00:00
instance: kb-cron
parent: am-d-e-all-on-20260505-0
summary:
Count Jean Gérard Amédée Alléon (8 October 1838 – 16 January 1904) was a French nobleman, naturalist, taxidermist and artist who lived in the Ottoman Empire. He noted the migrations of birds of prey in the Bosporus Straits and wrote on the birds of the region. == Biography == Alléon was born in Buyuk-Déré, near Istanbul (Constantinople), the son of Count Jacques Alléon (1792–1876), a Galata banker in the Ottoman Empire, and Marie Marion. He took an interest in nature and art at an early age with a talent for music and drawing. The family owned land and real estate and he became a shareholder of the English railroad company. He produced a number of artworks, and also made a collection of mounted bird specimens. In 1863 he married Madeleine Asselin de Villequier-Alléon (1844–1911) and they had five children including Maurice and Abel who were involved in natural history. He worked with Jules Vian of the French zoological society, sending many specimens to France. The English naturalist H. J. Elwes stayed with Alléon when he passed through Constantinople in 1870. In 1864, he donated a large set of his collections to the Ottoman government and in 1899, some to the


id: tamara-awerbuch-friedlander-20260505-0
file: data/en.wikipedia.org/wiki/Tamara_Awerbuch-Friedlander-0.md
category: reference
title: Tamara Awerbuch-Friedlander
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Tamara_Awerbuch-Friedlander
date_saved: 2026-05-05T10:07:29.465606+00:00
instance: kb-cron
parent: tamara-awerbuch-friedlander-20260505-0
summary:
Tamara Eugenia Awerbuch-Friedlander (Hebrew: תמרה אוורבוך-פרידלנדר; 1941–2021) was an Uruguay-born Israeli-American biomathematician and public health scientist who worked at the Harvard School of Public Health (HSPH) in Boston, Massachusetts. Her primary research and publications focus on biosocial interactions that cause or contribute to disease. She also is believed to be the first female Harvard faculty member to have had a jury trial for a lawsuit filed against Harvard University for sex discrimination. == Early life == Tamara Eugenia Friedlander was born in Uruguay, lived until the age of 12 in Buenos Aires, Argentina, then moved to Israel with her parents, where her grandparents and parents had lived after they had escaped Nazi Germany just before the Holocaust began. She studied and completed two degrees at Hebrew University in Jerusalem. She studied chemistry and minored in biochemistry and completed the BSc degree in 1965. In 1967, she completed both the Master of Science (MSc) in Physiology and the Master of Education (MEd) degree from Hebrew University. She was certified to teach grades K–12 in Israel, where she lectured and appeared on panels and in workshops, as she did also in the United States and elsewhere. She also served for two years


id: tamara-awerbuch-friedlander-20260505-1
file: data/en.wikipedia.org/wiki/Tamara_Awerbuch-Friedlander-1.md
category: reference
title: Tamara Awerbuch-Friedlander
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Tamara_Awerbuch-Friedlander
date_saved: 2026-05-05T10:07:29.465606+00:00
instance: kb-cron
parent: tamara-awerbuch-friedlander-20260505-0
summary:
=== Sex-discrimination suit against Harvard === Although Theda Skocpol had alleged gender bias in denial of tenure as early as 1980, Awerbuch-Friedlander was believed to be the first female Harvard Faculty member to file a lawsuit against Harvard University for sex discrimination. The suit was "filed with the Middlesex County Superior Court in June 1997." Encouraged by her mentors, Richard Levins and Marvin Zelen, Awerbuch-Friedlander sought "nearly $1 million in lost wages and benefits, as well as a promotion at the HSPH" and argued "that Fineberg refused to promote her to a tenure-track position because she is a woman, despite the positive recommendation of the HSPH's selection committee of appointment and re-appointment (SCARP)." Intermittently from 1998 through 2007, the gender discrimination case was covered by the Harvard Crimson (campus media), The Boston Globe (local media), and Science magazine (professional and scientific print media). Science documented the case developments of the sex-discrimination case in its "News of the Week: Women in Science" section. and in Science's SCIENCESCOPE two months later. Her sex discrimination lawsuit was based upon Harvard's denial of tenure to her, despite her significant accomplishments in her fields of expertise, biomathematics, epidemiology, biostatistics and public health. The University argued


id: j-nas-hallgr-msson-20260505-0
file: data/en.wikipedia.org/wiki/Jónas_Hallgrímsson-0.md
category: reference
title: Jónas Hallgrímsson
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Jónas_Hallgrímsson
date_saved: 2026-05-05T10:07:30.606913+00:00
instance: kb-cron
parent: j-nas-hallgr-msson-20260505-0
summary:
Jónas Hallgrímsson (16 November 1807 – 26 May 1845) was an Icelandic poet, writer and naturalist. He was one of the founders of the Icelandic journal Fjölnir, which was first published in Copenhagen in 1835. The magazine was used by Jónas and his fellow Fjölnismenn to promote Icelandic nationalism, in the hope of giving impetus to the Icelandic Independence Movement. Jónas remains one of Iceland's most beloved poets, penning some of the best-known Icelandic poems about Iceland and its people. Since 1996, Jónas's birthday has been officially recognised in Iceland as the Day of the Icelandic Language. On 16 November each year, the Jónas Hallgrímsson Award is awarded to an individual for their outstanding contribution to the Icelandic Language. == Biography == Jónas was born in the north of Iceland, in Öxnadalur in Eyjafjörður. He was the son of Hallgrímur Þorsteinsson, a curate, and Rannveig Jónasdóttir. He was the third of their four children; his siblings were Þorsteinn (born 1800), Rannveig (born 1802) and Anna Margrét (born 1815). In 1816 Jónas' father drowned in a lake and Jónas was sent to live with his aunt. In 1821 he returned home to Öxnadalur to be confirmed, before going away to a


id: yonetar-kikuchi-20260505-0
file: data/en.wikipedia.org/wiki/Yonetarō_Kikuchi-0.md
category: reference
title: Yonetarō Kikuchi
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Yonetarō_Kikuchi
date_saved: 2026-05-05T10:07:32.100533+00:00
instance: kb-cron
parent: yonetar-kikuchi-20260505-0
summary:
Yonetaro Kikuchi (菊池 米太郎; 1869 – 1921) was a Japanese zoologist and naturalist. He was born in Miyazaki Prefecture, Empire of Japan, and is best known for his extensive collection and study of birds, mammals, and reptiles in Taiwan during the Japanese colonial period. == Biography == In 1906, Kikuchi traveled to Taiwan to work for the Taiwan Government-General under the Bureau of Productive Industries. Over the following decade, he conducted extensive fieldwork across the island, including Mount Niitaka (now Yushan), Green Island, the Alishan Range, Orchid Island, and the Penghu archipelago. His collections of Taiwanese birds, mammals, and reptiles were large in scale and scientifically significant. Kikuchi is particularly known for being the first person to successfully capture the Mikado pheasant (Syrmaticus mikado) in 1906, after being commissioned by a British specimen dealer. In 1918, by order of Governor-General Akashi Motojirō, Kikuchi again captured Mikado pheasants and personally presented them to Emperor Taishō, accompanied by the Governor-General. The birds were subsequently kept in the Shinjuku Gyoen National Garden. In addition to his field expertise, Kikuchi was a highly skilled taxidermist. A large proportion of the zoological specimens currently held by the National Taiwan Museum were prepared by him. Kikuchi


id: josef-menges-20260505-0
file: data/en.wikipedia.org/wiki/Josef_Menges-0.md
category: reference
title: Josef Menges
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Josef_Menges
date_saved: 2026-05-05T10:07:33.294691+00:00
instance: kb-cron
parent: josef-menges-20260505-0
summary:
Jakob Josef Menges (7 October 1850– 4 January 1910) was a German explorer, naturalist, zoologist, cartographer, trader and author. During the 1870s and until the end of the 19th century, Menges undertook commercial and scientific expeditions in Northeast Africa and the Horn of Africa. His routes took him through the Turco-Egyptian Sudan, the interior of British Somaliland and Abyssinia in modern-day Ethiopia. To fund his journeys, Menges published travel and research reports on the region's geography, zoology and ethnology in German scientific journals. Later in life, he focused on animal trading, supplying exotic animals to European zoos, as well as facilitating human shows of Somali people in Europe. == Biography == === Early life and education === Josef Menges was the son of Joseph Menges and his wife Maria Josepha Diefenbach. His father was the last Thurn-und-Taxis postmaster of Limburg an der Lahn, actively involved in local politics and elected mayor in 1877. Josef Menges attended the Realgymnasium in Limburg and completed training as a railway official in Frankfurt am Main. === Travels === After the opening of the Suez Canal in 1869, the coastal regions of the Horn of Africa drew growing attention from foreign governments, companies, and private


id: josef-menges-20260505-1
file: data/en.wikipedia.org/wiki/Josef_Menges-1.md
category: reference
title: Josef Menges
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Josef_Menges
date_saved: 2026-05-05T10:07:33.294691+00:00
instance: kb-cron
parent: josef-menges-20260505-0
summary:
In addition to English, French and Italian, Menges learned several African dialects. To obtain information and establish his position, he depended largely on the support of local inhabitants. In a letter of 11 April 1883 to the editors of Petermanns Geographische Mitteilungen, he wrote:Nor did I fail to ask the accompanying natives, who knew every detail about the land, in order to be able to write down the names of the various localities, so that I believe I have made as accurate a sketch as is at all possible of a hunting expedition that had no scientific purpose. === Animal trading === To support his expeditions financially, Menges formed a professional association in 1876 with the Hamburg circus manager and animal trainer Carl Hagenbeck. This included providing Hagenbeck with information about animal populations, possibilities for capture and logistics to transport animals to the coast and further to Europe. Menges played a central role in establishing early contacts between Somali intermediaries and Hagenbeck’s enterprise. Besides Hamburg, the Frankfurt Zoological Garden became the main hub for animal collections imported by Menges to Europe. When Adalbert Seitz became director of the Frankfurt Zoo on 1 April 1893, he provided Menges with temporary storage


id: antonio-pineda-20260505-0
file: data/en.wikipedia.org/wiki/Antonio_Pineda-0.md
category: reference
title: Antonio Pineda
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Antonio_Pineda
date_saved: 2026-05-05T10:07:34.423278+00:00
instance: kb-cron
parent: antonio-pineda-20260505-0
summary:
Antonio Pineda (January 17, 1751 – June 23, 1792) was a Spanish naturalist and military officer. He participated in the Malaspina Expedition as leader of the natural history team which included Thaddäus Haenke and Luis Née. His scientific exploration and collecting covered a significant portion of the Pacific basin including the coast of South America, Mexico, and the Philippines. Before his untimely death in the Philippines, Pineda had amassed a huge volume of documents including scientific reports, diaries, and logbooks as well as a significant collection of natural history specimens. == Biography == Pineda was born on January 17, 1751, in Guatemala City, New Spain. His Spanish father, José de Pineda, was a knight in the Order of Santiago and served as a judge in the Royal Audiencia of Guatemala. His mother, María Josefa Ramírez, was a native of Lucena, Spain and held estates in Laxa. When Pineda was six years old the family returned to Spain where his father served the Royal Chancellery in Granada. Antonio was first educated at the "Colegio de Nobles" in Madrid. When he turned seventeen he enrolled in the Spanish Military Academy and was accepted as a cadet in the distinguished Spanish Royal Guard.


id: natural-history-museum-20260505-0
file: data/en.wikipedia.org/wiki/Natural_history_museum-0.md
category: reference
title: Natural history museum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Natural_history_museum
date_saved: 2026-05-05T10:07:35.990276+00:00
instance: kb-cron
parent: natural-history-museum-20260505-0
summary:
A natural history museum or museum of natural history is a scientific institution with natural history collections that include current and historical records of animals, plants, fungi, ecosystems, geology, paleontology, climatology, and more. == History == The primary role of a natural history museum is to provide the scientific community with current and historical specimens for their research, which is to improve our understanding of the natural world. Some museums have public exhibits to share the beauty and wonder of the natural world with the public; these are referred to as 'public museums'. Some museums feature non-natural history collections in addition to their primary collections, such as ones related to history, art, and science. Renaissance cabinets of curiosities were private collections that typically included exotic specimens of national history, sometimes faked, along with other types of object. The first natural history museum was possibly that of Swiss scholar Conrad Gessner, established in Zürich in the mid-16th century. The National Museum of Natural History, established in Paris in 1635, was the first natural history museum to take the form that would be recognized as a natural history museum today. Early natural history museums offered limited accessibility, as they were generally private


id: cabinet-of-curiosities-20260505-0
file: data/en.wikipedia.org/wiki/Cabinet_of_curiosities-0.md
category: reference
title: Cabinet of curiosities
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cabinet_of_curiosities
date_saved: 2026-05-05T10:07:37.214770+00:00
instance: kb-cron
parent: cabinet-of-curiosities-20260505-0
summary:
Cabinets of curiosities (German: Kunstkammer [ˈkʊnstˌkamɐ] and Kunstkabinett [ˈkʊnstkabiˌnɛt]), also known as wonder-rooms (German: Wunderkammer [ˈvʊndɐˌkamɐ] ), were encyclopedic collections of objects whose categorical boundaries were, in Renaissance Europe, yet to be defined. Although more rudimentary collections had preceded them, the classic cabinets of curiosities emerged in the sixteenth century. The term cabinet originally described a room rather than a piece of furniture. Modern terminology would categorize the objects included as belonging to natural history (sometimes faked), geology, ethnography, archaeology, religious or historical relics, works of art (including cabinet paintings), and antiquities. In addition to the most famous and best documented cabinets of rulers and aristocrats, members of the merchant class and early practitioners of science in Europe formed collections that were precursors to museums. Cabinets of curiosities served not only as collections to reflect the particular interests of their curators but also as social devices to establish and uphold rank in society. There are said to be two main types of cabinets. As R. J. W. Evans notes, there could be "the princely cabinet, serving a largely representational function, and dominated by aesthetic concerns and a marked predilection for the exotic," or the less grandiose, "the more modest collection


id: cabinet-of-curiosities-20260505-1
file: data/en.wikipedia.org/wiki/Cabinet_of_curiosities-1.md
category: reference
title: Cabinet of curiosities
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cabinet_of_curiosities
date_saved: 2026-05-05T10:07:37.214770+00:00
instance: kb-cron
parent: cabinet-of-curiosities-20260505-0
summary:
Two of the most famously described seventeenth-century cabinets were those of Ole Worm, known as Olaus Wormius (1588–1654) (illustration, above right), and Athanasius Kircher (1602–1680). These seventeenth-century cabinets were filled with preserved animals, horns, tusks, skeletons, minerals, as well as other interesting man-made objects: sculptures wondrously old, wondrously fine or wondrously small; clockwork automata; ethnographic specimens from exotic locations. Often they would contain a mix of fact and fiction, including apparently mythical creatures. Worm's collection contained, for example, what he thought was a Scythian Lamb, a woolly fern thought to be a plant/sheep fabulous creature. However he was also responsible for identifying the narwhal's tusk as coming from a whale rather than a unicorn, as most owners of these believed. The specimens displayed were often collected during exploring expeditions and trading voyages. Cabinets of curiosities would often serve scientific advancement when images of their contents were published. The catalog of Worm's collection, published as the Museum Wormianum (1655), used the collection of artifacts as a starting point for Worm's speculations on philosophy, science, natural history, and more. Cabinets of curiosities were limited to those who could afford to create and maintain them. Many monarchs, in particular, developed large collections. A


id: cabinet-of-curiosities-20260505-2
file: data/en.wikipedia.org/wiki/Cabinet_of_curiosities-2.md
category: reference
title: Cabinet of curiosities
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cabinet_of_curiosities
date_saved: 2026-05-05T10:07:37.214770+00:00
instance: kb-cron
parent: cabinet-of-curiosities-20260505-0
summary:
Sloane meticulously cataloged and created extensive records for most of the specimens and objects in his collection. He also began to acquire other collections by gift or purchase. Herman Boerhaave gave him four volumes of plants from Boerhaave's gardens at Leiden. William Charleton, in a bequest in 1702, gave Sloane numerous books of birds, fish, flowers, and shells and his miscellaneous museum consisting of curiosities, miniatures, insects, medals, animals, minerals, precious stones and curiosities in amber. Sloane purchased Leonard Plukenet's collection in 1710. It consisted of twenty-three volumes with over 8,000 plants from Africa, India, Japan and China. Mary Somerset, Duchess of Beaufort (1630–1715), left him a twelve-volume herbarium from her gardens at Chelsea and Badminton upon her death in 1714. Reverend Adam Buddle gave Sloane thirteen volumes of British plants. In 1716, Sloane purchased Engelbert Kaempfer's volume of Japanese plants and James Petiver's virtual museum of approximately one hundred volumes of plants from Europe, North America, Africa, the Near East, India, and the Orient. Mark Catesby gave him plants from North America and the West Indies from an expedition funded by Sloane. Philip Miller gave him twelve volumes of plants grown from the Chelsea Physic Garden. Sloane acquired approximately


id: cabinet-of-curiosities-20260505-3
file: data/en.wikipedia.org/wiki/Cabinet_of_curiosities-3.md
category: reference
title: Cabinet of curiosities
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cabinet_of_curiosities
date_saved: 2026-05-05T10:07:37.214770+00:00
instance: kb-cron
parent: cabinet-of-curiosities-20260505-0
summary:
=== United States === Thomas Dent Mutter (1811–1859) was an early American pioneer of reconstructive plastic surgery. His specialty was repairing congenital anomalies, cleft lip and palates, and club foot. He also collected medical oddities, tumors, anatomical and pathological specimens, wet and dry preparations, wax models, plaster casts, and illustrations of medical deformities. This collection began as a teaching tool for young physicians. Just prior to Mütter's death in 1859, he donated 1,344 items to the American College of Physicians in Philadelphia, along with a $30,000 endowment for the maintenance and expansion of his museum. Mütter's collection was added to ninety-two pathological specimens collected by Doctor Isaac Parrish between 1849 and 1852. The Mütter Museum began to collect antique medical equipment in 1871, including Benjamin Rush's medical chest and Florence Nightingale's sewing kit. In 1874 the museum acquired one hundred human skulls from Austrian anatomist and phrenologist, Joseph Hyrtl (1810–1894); a nineteenth-century corpse, dubbed the "soap lady"; the conjoined liver and death cast of Chang and Eng Bunker, the Siamese twins; and in 1893, Grover Cleveland's jaw tumor. The Mütter Museum is an excellent example of a nineteenth-century grotesque cabinet of medical curiosities. P. T. Barnum established Barnum's American Museum


id: cabinet-of-curiosities-20260505-4
file: data/en.wikipedia.org/wiki/Cabinet_of_curiosities-4.md
category: reference
title: Cabinet of curiosities
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cabinet_of_curiosities
date_saved: 2026-05-05T10:07:37.214770+00:00
instance: kb-cron
parent: cabinet-of-curiosities-20260505-0
summary:
== Further reading == Under the Sign: John Bargrave as Collector, Traveler, and Witness, Stephen Bann, Michigan, 1995 Beßler, Gabriele, Chambers of Art and Wonders, EGO - European History Online, Mainz: Institute of European History, 2015, retrieved: March 8, 2021 (pdf). The Origins of Museums: The Cabinet of Curiosities in Sixteenth- and Seventeenth-Century Europe, ed. Oliver Impey and Arthur MacGregor, 2001, paperback, 431 pages, ISBN 1-84232-132-3 Cabinets for the curious: looking back at early English museums, Ken Arnold, Ashgate, 2006, ISBN 0-7546-0506-X. Mr. Wilson's Cabinet Of Wonder: Pronged Ants, Horned Humans, Mice on Toast, and Other Marvels of Jurassic Technology, Lawrence Weschler, 1996, trade paperback, 192 pages, ISBN 0-679-76489-5 (see website link above) The Cabinet of Curiosities (novel), Douglas Preston and Lincoln Child, Warner Books, 2003, paperback, ISBN 0-446-61123-9. Helmar Schramm et al. (ed.). Collection, Laboratory, Theater. Scenes of Knowledge in the 17th Century, Berlin/New York 2005, ISBN 978-3-11-017736-7 The Lure of Antiquity and the Cult of the Machine: The Kunstkammer and the Evolution of Nature, Art and Technology Horst Bredekamp (Allison Brown, translator) (Princeton: Marcus Weiner) 1995. Steven Lubar, "Cabinets of Curiosity: What they were, why they disappeared, and why they’re so popular now" == External links == Historic


id: list-of-natural-history-museums-20260505-0
file: data/en.wikipedia.org/wiki/List_of_natural_history_museums-0.md
category: reference
title: List of natural history museums
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/List_of_natural_history_museums
date_saved: 2026-05-05T10:07:38.436193+00:00
instance: kb-cron
parent: list-of-natural-history-museums-20260505-0
summary:
This is a list of natural history museums whose exhibits focus on the subject of natural history, including such topics as animals, plants, ecosystems, geology, paleontology, and climatology. Some museums feature natural-history collections in addition to other collections, such as ones related to history, art and science. In addition, nature centers often include natural history exhibits. == Africa == === Algeria === Beni Abbes Museum (Musee de Beni-Abbes), Béni Abbès === Angola === National Museum of Natural History of Angola (Museu Nacional de História Natural de Angola), Luanda === Botswana === Botswana National Museum, Gaborone === Egypt === Egyptian Geological Museum, Cairo Alexandria Aquarium Museum, Alexandria === Ethiopia === Zoological Natural History Museum, Addis Ababa === Kenya === Kitale Museum, Kitale National Museums of Kenya, Nairobi === Mozambique === Museu de História Natural de Moçambique, Maputo === Namibia === National Earth Science Museum, Geological Survey of Namibia, Windhoek === Nigeria === Natural History Museum, OAU, Ifẹ, located at the Obafemi Awolowo University === South Africa === Albany Museum, Grahamstown Amathole Museum, King William's Town Bleloch Geological Museum, University of the Witwatersrand, Johannesburg Wits Life Sciences Museum, University of the Witwatersrand, Johannesburg CP Nel Museum, Oudtshoorn Natural Science Museum, Durban Iziko


id: list-of-natural-history-museums-20260505-1
file: data/en.wikipedia.org/wiki/List_of_natural_history_museums-1.md
category: reference
title: List of natural history museums
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/List_of_natural_history_museums
date_saved: 2026-05-05T10:07:38.436193+00:00
instance: kb-cron
parent: list-of-natural-history-museums-20260505-0
summary:
=== Singapore === Science Centre Singapore Lee Kong Chian Natural History Museum === Taiwan === Insect Science Museum, Taipei National Museum of Natural Science, Taichung National Museum of Taiwan History, Tainan City National Taiwan Museum, Taipei City National Chiayi University Insect Museum, Chiayi City === Thailand === Thailand National Science Museum, Pathum Thani Chulalongkorn University Museum of Natural History, Bangkok Chulalongkorn University's Geological Museum, Bangkok Chulalongkorn University's Traditional Medicine Museum, Bangkok Mahidol University's Mollusk Museum, Bangkok Mahidol University's Mosquito Museum, Bangkok Mahidol University's Bio-Geo Path, Bangkok Rattanakosin Natural History Museum, Kasetsart University, Bangkok Veterinarical Anatomy Museum, Kasetsart University, Bangkok Pathology Museum, Kasetsart University, Bangkok Kasetsart University's Ant Museum, Bangkok Kasetsart University's Zoological Museum, Bangkok Kasetsart University Museum of Fisheries (Natural History), Bangkok Kasetsart University's 60th Anniversary Museum and Park of Insects, Bangkok Lichen Museum, Ramkhamhaeng University, Bangkok Bangkok Butterfly and Insect Park, Bangkok Dusit Zoo Museum, Bangkok Soil Museum, Bangkok Geological Museum, Bangkok Horn and Antler Museum, Bangkok Biological Science Museum at Faculaty of Science, Chiang Mai University, Chiang Mai Chiang Mai University's Geological Museum, Chiang Mai Museum of World Insects and Natural Heritages, Chiang Mai Lignite Learning Centre Museum, Lampang King Mongkut Memeorail Park of Science and Technology, Prachuap


id: list-of-natural-history-museums-20260505-2
file: data/en.wikipedia.org/wiki/List_of_natural_history_museums-2.md
category: reference
title: List of natural history museums
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/List_of_natural_history_museums
date_saved: 2026-05-05T10:07:38.436193+00:00
instance: kb-cron
parent: list-of-natural-history-museums-20260505-0
summary:
=== Croatia === Croatian Natural History Museum, Zagreb (Hrvatski prirodoslovni muzej) Dubrovnik Natural History Museum, Dubrovnik Hunting Museum, Zagreb Karlovac Municipal Museum, Karlovac Museum of Evolution and Prehistoric Human Habitation, Krapina Museum of Slavonia, Osijek Mushroom Museum, Zagreb Natural History Museum, Rijeka Natural History Museum and Zoo, Split Ornithological Collection, Metković Senj City Museum, Senj Varazdin Municipal Museum: The Herzer Palace, Varaždin Zoological Museum of Baranja – Kopačevo, Baranja – Kopačevo === Czech Republic === Moravian Museum, Brno National Museum (Prague), Prague Chlupáč's Museum of the History of Earth, Prague Městské muzeum Čáslav, Čáslav === Denmark === Copenhagen Amber Museum, Copenhagen Natural History Museum of Denmark, Copenhagen Fossil and Mo-clay Museum, near Sejerslev (northern Mors Island) Fur Museum, Nederby (on Fur Island) GeoCenter Møns Klint, Borre (eastern Møn) Gram Natural History Museum, Gram Museum of Evolution at Knuthenborg Safaripark, Bandholm NaturBornholm, Aakirkeby Naturhistorisk Museum, Aarhus Naturama, Svendborg Stevns Klint Experience, Rødvig Wadden Sea Centre, Vester Vedsted (near Ribe) === Estonia === Estonian Museum of Natural History, Tallinn Ice Age Centre, Tartu University of Tartu Natural History Museum, Tartu === Finland === Finnish Museum of Natural History, Helsinki Geological Museum, University of Oulu, Oulu Mineralogical Museum of the Geological Survey of


id: list-of-natural-history-museums-20260505-3
file: data/en.wikipedia.org/wiki/List_of_natural_history_museums-3.md
category: reference
title: List of natural history museums
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/List_of_natural_history_museums
date_saved: 2026-05-05T10:07:38.436193+00:00
instance: kb-cron
parent: list-of-natural-history-museums-20260505-0
summary:
=== Italy === Museo Civico Scienze Naturali Enrico Caffi, Bergamo University Museums, University of Bologna, Bologna Museo della Preistoria Luigi Donini, San Lazzaro di Savena, Bologna Museo del Fossile del Monte Baldo, Brentonico, Trentino-Alto Adige/Südtirol Museo Civico di Storia Naturale, Carmagnola, Piedmont Museo Civico Comunale di Comiso, Sicily Museo Civico di Storia Naturale di Ferrara, Ferrara Museo di Storia Naturale di Firenze, University of Florence, Florence Museo Civico di Storia Naturale Giacomo Doria, Genoa Museo di Storia Naturale della Maremma, Grosseto Museo di Storia Naturale del Mediterraneo, Livorno Museo di Scienze Naturali, Lodi, Lombardy Museo Civico di Storia Naturale di Milano, Milan Zoological Museum of Naples, Naples Museo di Geologia e Paleontologia, University of Padua, Padua Museo per la Storia dell'Università, University of Pavia, Pavia Museo di Storia Naturale, University of Pavia, Pavia Museo di Archeologia, University of Pavia, Pavia Museo di Mineralogia, University of Pavia, Pavia Natural History Museum, Pisa Museo Geologico delle Dolomiti, Predazzo, Trentino-Alto Adige/Südtirol Museo Civico di Zoologia di Roma, Rome Geological Museum, Rome Museo Civico Rovereto, Rovereto Museo Regionale di Scienze Naturali, Saint-Pierre Museo di Storia Naturale, Sulmona Museo di Storia Naturale Bios Taras, Taranto Museo Tridentino di Scienze Naturali, Trento Museo Civico di Storia


id: list-of-natural-history-museums-20260505-4
file: data/en.wikipedia.org/wiki/List_of_natural_history_museums-4.md
category: reference
title: List of natural history museums
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/List_of_natural_history_museums
date_saved: 2026-05-05T10:07:38.436193+00:00
instance: kb-cron
parent: list-of-natural-history-museums-20260505-0
summary:
=== Spain === Cau del Cargol Conquilles del Món (Shells of the World Museum, malacology), Catalonia Institut Paleontològic Dr. M. Crusafont, Sabadell Museo de Ciencias de Arnedo (Museum of Science Arnedo), Arnedo Museo de Ciencias Naturales, Álava Museu de Ciències Naturals, Barcelona Museo de Ciencias Naturales (Guadalcazar) and Mocha Tower, Córdoba Museo Geominero, Madrid Museo Municipal de Ciencias Naturales (Municipal Museum of Natural Science), Valencia Museo Nacional de Ciencias Naturales, Madrid Museo Paleontologico de la Universidad de Zaragoza, Zaragoza Museu de Ciencies Naturals de Costix, Mallorca Museu de Granollers Ciències Naturals, Granollers Museu de les Papallones de Catalunya, Lleida Museu Geològic del Seminari de Barcelona, Barcelona Museu Montsia, Amposta Museu Valencià d'Història Natural – Fundación Entomológica Torres Sala, Valencia Museum of Zoology, University of Navarra, Pamplona === Sweden === Biologiska Museet (Biological Museum), Djurgården, Stockholm Gotland Museum (Gotlands museum), Visby Geological Museum Villa Heidelberg, Klimpfjäll Göteborg Natural History Museum (Göteborgs Naturhistoriska Museum), Gothenburg Malmö Museums – Natural History Museum, Malmö Lund University Zoology Museum (Lunds Universitet Zoologiska museet), Lund Museum of Evolution, Uppsala University (Evolutions Museet Uppsala Universitet), Uppsala Swedish Museum of Natural History (Naturhistoriska riksmuseet), Stockholm Swedish Amber Museum, Höllviken === Switzerland === Musée cantonal de géologie (Cantonal Museum


id: list-of-natural-history-museums-20260505-5
file: data/en.wikipedia.org/wiki/List_of_natural_history_museums-5.md
category: reference
title: List of natural history museums
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/List_of_natural_history_museums
date_saved: 2026-05-05T10:07:38.436193+00:00
instance: kb-cron
parent: list-of-natural-history-museums-20260505-0
summary:
==== Ontario ==== 1000 Islands History Museum, Gananoque Aquatarium, Brockville Arkona Lions Museum, Arkona Ball's Falls Centre for Conservation, Ball's Falls, Ontario Bonnechere Museum, Bonnechere Canadian Museum of Nature, Ottawa Dynamic Earth, Sudbury Entomica Insectarium, Sault Ste. Marie Royal Ontario Museum, Toronto The Earth Sciences Museum, University of Waterloo, Waterloo The Miller Museum of Geology, Queen's University at Kingston Museum of Northern History, Kirkland Lake The Niagara Falls Museum, Niagara Falls Pelee Island Heritage Centre, Pelee Science North, Greater Sudbury Stones 'N Bones Museum, Sarnia ==== Quebec ==== Lake Timiskaming Fossil Centre, Quebec City Montreal Biosphere, Montreal Montreal Insectarium, Montreal Musée de la Nature et des Sciences, Sherbrooke Musee du Fjord, La Baie Musée de Paléontologie et de l'Evolution, Montreal Musée Minéralogique d'Asbestos, Asbestos Musée minèralogique et minier de Thetford Mines, Thetford Mines Redpath Museum, Montreal Sherbrooke Nature and Science Museum, Sherbrooke ==== Saskatchewan ==== Abernethy Nature-Heritage Museum, Abernethy Ancient Echoes Interpretive Center, Herschel Museum of Natural Sciences, University of Saskatchewan, Saskatoon Royal Saskatchewan Museum, Regina T.rex Discovery Centre, Eastend ==== Yukon ==== Kluane Museum of Natural History, Burwash Landing Yukon Beringia Interpretive Centre, Whitehorse === Mexico === Caracol, Museo de Ciencias de Ensenada, Ensenada Museo de Geología UNAM, Mexico


id: list-of-natural-history-museums-20260505-6
file: data/en.wikipedia.org/wiki/List_of_natural_history_museums-6.md
category: reference
title: List of natural history museums
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/List_of_natural_history_museums
date_saved: 2026-05-05T10:07:38.436193+00:00
instance: kb-cron
parent: list-of-natural-history-museums-20260505-0
summary:
=== Brazil === Museu de Arqueologia e Etnologia – USP, São Paulo, SP Museu de Ciências Naturais – PUC MINAS, Belo Horizonte, MG Museu Entomológico Fritz Plaumann, Santa Catarina Museu Geológico Valdemar Lefèvre, São Paulo, SP Museu de Geociências – USP, São Paulo, SP Museu de História Natural de Taubaté, Taubaté Museu de Historia Natural Capão da Imbuia Wood, Curitiba Museu Nacional, UFRJ, Rio de Janeiro, RJ Museu Paraense Emílio Goeldi, Belém Museu de Rochas, Minerais e Minérios – USP, São Paulo, SP Museum of Veterinary Anatomy FMVZ USP, São Paulo Museu de Zoologia da Universidade Estadual de Campinas, Campinas, São Paulo state Museu de Zoologia da Universidade de São Paulo, São Paulo === Chile === Chilean National Museum of Natural History, Santiago Museo de Historia Natural de Valparaiso, Región de Valparaiso Museo de Historia Natural de Concepción, Región del Biobío === Colombia === Museo de Historia Natural, Popayán Museo La Salle, Bogotá Museo Prehistórico National University of Colombia, Bogotá: Museo de Historia Natural (Museum of Natural History) Museo Entomológico (Museum of Entomology) Museo Paleontológico (Museum of Paleontology) Botanic Garden Medellín === Ecuador === Gustavo Orcés V. Natural History Museum, Quito === Guyana === Guyana National Museum, Georgetown === Paraguay


id: alaska-museum-of-science-and-nature-20260505-0
file: data/en.wikipedia.org/wiki/Alaska_Museum_of_Science_and_Nature-0.md
category: reference
title: Alaska Museum of Science and Nature
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Alaska_Museum_of_Science_and_Nature
date_saved: 2026-05-05T10:07:39.618711+00:00
instance: kb-cron
parent: alaska-museum-of-science-and-nature-20260505-0
summary:
The Alaska Museum of Science and Nature (AKSCI) is a natural history museum in Anchorage, Alaska. It is known for its collection of fossils. == History == The museum initially opened in 1994, in a shopping mall in the Eagle River community of Anchorage. By 2015, it had moved to its own building in the Mountain View neighborhood. == Exhibits == The museum has six main exhibits: Dinosaurs of Darkness, Alaska Marine Life, Birds of a Feather, Bare Bones, Ice Age Alaska, and Rocks & Minerals. The Dinosaurs exhibit contains skeletons and reproductions of dinosaurs such as Hadrosaurs, Ceratopsians, Albertosaurus, and raptors. The Marine Life exhibit shows off whalebones and skulls and a full skeleton of a beluga whale. The birds exhibit contains a rookery with a variety of bird species, and the bones exhibit contains replicas of human bones and compares them to animal ones. The Ice Age exhibit displays models of animals from the Pleistocene, such as American lions and saber-toothed tigers. The rocks exhibit shows off fluorescent and multi-colored minerals, meteorites, and fossils from the prehistoric forest in Sutton. The museum contains several life-sized dinosaur paintings by local artist James Haven. == References == == External links


id: anthropos-pavilion-20260505-0
file: data/en.wikipedia.org/wiki/Anthropos_Pavilion-0.md
category: reference
title: Anthropos Pavilion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Anthropos_Pavilion
date_saved: 2026-05-05T10:07:40.809214+00:00
instance: kb-cron
parent: anthropos-pavilion-20260505-0
summary:
Anthropos (or Anthropos Pavilion, from the Greek Άνθρωπος, human or man) is a museum located in the city of Brno, South Moravia, Czech Republic. The museum is a part of the Moravské zemské muzeum (Moravian Museum). It focuses on exhibitions presenting the oldest history of Europe and mankind. In a 2009 exhibition, the museum presented the most important art works of the Paleolithic era, such as Venus of Willendorf (exhibited for the first time outside of Austria) and Venus of Dolní Věstonice. == Basic characteristics == The museum is situated on the right bank of the river Svratka, in the cadastral municipality of Pisárky in the western part of Brno. It consists of a permanent, three-part exhibition presenting the oldest history of human settlement in Moravia and Europe and of temporary exhibitions. The permanent exhibition includes a life-size model of mammoth. == History == In 1928, during an exhibition of the contemporary culture held at the Brno Exhibition Centre, the archaeologist Karel Absolon presented the findings of the oldest history of human settlements in a solo exhibition called Člověk a jeho rod (Man and his Ancestry). The exhibition was supported by the first Czechoslovak president Tomáš Garrigue Masaryk and by


id: bangladesh-national-museum-20260505-0
file: data/en.wikipedia.org/wiki/Bangladesh_National_Museum-0.md
category: reference
title: Bangladesh National Museum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bangladesh_National_Museum
date_saved: 2026-05-05T10:07:41.955974+00:00
instance: kb-cron
parent: bangladesh-national-museum-20260505-0
summary:
The Bangladesh National Museum (Bengali: বাংলাদেশ জাতীয় জাদুঘর, romanized: Bānlādēśa Jātīẏa Jādughara) is the national repository of Bangladesh's cultural and historical artifacts, located in the Shahbag area of Dhaka. The museum was established on 20 March 1913, under the name Dhaka Museum, and was formally inaugurated on 7 August 1913. With an initial collection of 379 objects, it was opened to the public on 25 August 1914. After the independence of Bangladesh in 1971, the institution was reorganized under the name Bangladesh National Museum, incorporating various parts of the former Dhaka Museum, and was formally inaugurated in its present form in 1983. The museum has departments of ethnography and decorative art, history and classical art, natural history, and world civilization. Artifacts from the prehistoric era to contemporary history are displayed here, which include over 50,000 ancient and medieval coins, Buddhist sculptures from the Gandhara period, and exhibits related to the 1971 Liberation War. == History == In 1855, the Asiatic Society of Bengal proposed establishing a museum in Dhaka, but it was postponed due to logistical constraints. Later, in 1907, this initiative re-emerged among the elite class of Dhaka. Following this, on 20 March 1913, the Dhaka Museum was formally


id: belarusian-nature-and-environment-museum-20260505-0
file: data/en.wikipedia.org/wiki/Belarusian_Nature_and_Environment_Museum-0.md
category: reference
title: Belarusian Nature and Environment Museum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Belarusian_Nature_and_Environment_Museum
date_saved: 2026-05-05T10:07:43.122911+00:00
instance: kb-cron
parent: belarusian-nature-and-environment-museum-20260505-0
summary:
The Museum of Nature and Environment of the Republic of Belarus (Belarusian: Музей прыроды і экалогіі Рэспублікі Беларусь, romanized: Muzey pryrody i ekalogii Respubliki Byelarus) is a museum in Minsk, Belarus, founded in 1991 at Minsk on the basis of the nature of Belarusian National History and Culture Museum. There are more than 40 thousand exhibits inside an exposition area of 350 m2. In the 6 thematic rooms (mineralogical, fenalagichny, nature, river, lake, forest) exhibits tell about the natural riches of the evolution of flora and fauna from antiquity to the present day. == Gallery == == External links == Official website


id: beni-abbes-museum-20260505-0
file: data/en.wikipedia.org/wiki/Beni_Abbes_Museum-0.md
category: reference
title: Beni Abbes Museum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Beni_Abbes_Museum
date_saved: 2026-05-05T10:07:44.315522+00:00
instance: kb-cron
parent: beni-abbes-museum-20260505-0
summary:
Beni Abbes Museum, also known as Béni Abbès Museum (Arabic: متحف بني عباس, romanized: Matḥaf Banī ʻAbbās) is an art museum located in oasis town of Beni Abbes, Béchar Province, Algeria. It is "a resource dedicated to desert fauna, fossils and Algerian arts and crafts." == Displays == Béni Abbès Museum is popular in Algeria. It is supported by the Saharan Research Center. The museum houses displays desert fauna, fossils and traditional arts and crafts, such as carpets, wall hangings, ceramic items, woodcarvings and jewelry. The museum, which is supported by the Saharan Research Center, displays an extensive range of different types of dates. Dates are one of the mainstay crops of oasis towns and villages in Algeria. == Myth == The oasis of Beni Abbes has its own myth. Local people claim that: “The spring which waters this lush oasis came about as a miracle. It is said that a traveler pushed his walking-stick into the ground, declaring that if he should die in this place, water would come out of the ground. He apparently died the following night, possibly due to lack of water, and the spring began to flow, continuing to do so to this day”. ==


id: biblical-museum-of-natural-history-20260505-0
file: data/en.wikipedia.org/wiki/Biblical_Museum_of_Natural_History-0.md
category: reference
title: Biblical Museum of Natural History
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Biblical_Museum_of_Natural_History
date_saved: 2026-05-05T10:07:45.519755+00:00
instance: kb-cron
parent: biblical-museum-of-natural-history-20260505-0
summary:
The Biblical Museum of Natural History (Hebrew: מוזיאון הטבע התנ"כי, romanized: Muzeyum haTeva haTanakhi), currently located in Hartuv at the entrance to Beit Shemesh, Israel, was founded in 2014 by Rabbi Dr. Natan Slifkin, affectionately referred to as the "Zoo Rabbi." == Vision and purpose == The establishment describes itself as "part natural history museum, part zoo" and is meant to "enhance the appreciation and understanding of biblical scripture and Jewish tradition via the natural world." Visitors are able to gain insight into the animals that lived in Israel during biblical times even if they no longer exist there now, such as bears and crocodiles. Visitors to the museum are currently directed by special tour by appointment only. Features include live animal, taxidermy and skeleton exhibits, as well as audio/visual presentations. Tour topics include unraveling incidents of misidentification of animals by biblical scholars of species mentioned in both the Five Books of Moses and the Talmud due to their lack of familiarity with different families that are not represented in places like Europe, where much of the Jewish medieval biblical commentary was written. == History == In 2017 the Museum held a "Feast of Exotic Curiosities," at which foods including


id: biomuseo-20260505-0
file: data/en.wikipedia.org/wiki/Biomuseo-0.md
category: reference
title: Biomuseo
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Biomuseo
date_saved: 2026-05-05T10:07:46.661955+00:00
instance: kb-cron
parent: biomuseo-20260505-0
summary:
Biomuseo is a museum focused on the natural history of Panama, whose isthmus was formed very recently in geologic time, with major impact on the ecology of the Western Hemisphere. Located on the Amador Causeway in Panama City, Panama, it was designed by renowned architect Frank Gehry. This is Gehry's first design for Latin America. The design was conceived in 1999 and the museum opened on 2 October 2014. The Biomuseo highlights Panama's natural and cultural history, emphasizing the role of humans in the 21st century. Its galleries tell the story of how the rise of the isthmus of Panama changed the world. == Location == Biomuseo is located in Amador, also known as Causeway, at the south entrance of the Panama Canal. Visitors can get there via taxi or bus. == The building and its galleries == With 4,000 square meters, the Biomuseo has eight galleries for its permanent exhibits, designed in sequence by Bruce Mau Design. The museum also has a public atrium, a space for temporary exhibits, a gift store, a coffee shop and exterior exhibits in a botanical garden designed by Edwina von Gal. On October 2, 2014, the Biomuseo opened the first five galleries to


id: b-tov-castle-20260505-0
file: data/en.wikipedia.org/wiki/Bítov_Castle-0.md
category: reference
title: Bítov Castle
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bítov_Castle
date_saved: 2026-05-05T10:07:47.958468+00:00
instance: kb-cron
parent: b-tov-castle-20260505-0
summary:
Bítov Castle (Czech: Hrad Bítov, German: Schloss Vöttau) is a castle on a steep promontory towering above the meandering River Želetavka, near the Vranov reservoir, in the village of Bítov, some 25 kilometres (16 mi) northwest of Znojmo, Czech Republic. Built in the 11th century, Bítov is one of the oldest and largest Moravian castles. == History == A Přemyslid fortified settlement originally stood on the site and included the Chapel of Our Lady (Kostelík Panny Marie). The fort was rebuilt in the first half of the 13th century as an impregnable Gothic castle guarding the southern boundaries of the Přemyslid lands. In the 14th century a new inner ward was built along with Late Gothic fortifications. The Lords of Bítov became the new owners of the castle and based themselves here for four centuries. They carried out further improvements to the defensive capabilities of the castle. Bítov finally underwent Baroque remodelling, and gained its present form at the beginning of the 19th century, when it passed into the hands of the Counts of Daun. The descendants of Marshal Daun, the famous military leader, rebuilt the castle in the spirit of the Romantic style. Between 1811 and 1845 the richly


id: botanical-garden-and-zoo-of-asunci-n-20260505-0
file: data/en.wikipedia.org/wiki/Botanical_Garden_and_Zoo_of_Asunción-0.md
category: reference
title: Botanical Garden and Zoo of Asunción
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Botanical_Garden_and_Zoo_of_Asunción
date_saved: 2026-05-05T10:07:49.175308+00:00
instance: kb-cron
parent: botanical-garden-and-zoo-of-asunci-n-20260505-0
summary:
The Botanical Garden and Zoo of Asunción (Spanish: Jardín Botánico y Zoológico de Asunción) is a botanical garden and zoo located in Asunción, capital of the Republic of Paraguay. The Botanical Garden and Zoo is one of the principal open spaces of the city of Asunción, set in natural forest covering 110 hectares (270 acres) to the north of the city. The zoo is home to nearly seventy species of wildlife including birds, mammals and reptiles, mostly representing the fauna of South America. The botanical garden is home to native species, exhibiting, in particular, the variety and beauty of its lush trees. == History == This sprawling property was the former country house and estate of Carlos Antonio López, president of Paraguay between 1842 and 1862. Lopez ordered the construction of "Casa Lopez" as his home in the 1840s. Besides its historical value, the main building is very representative of the era in which it was built, in terms of technology, architecture and decoration, and is registered in the "Catalogue of Buildings and Sites of Urban Planning, architectural, Historical and Artistic Heritage of the city of Asunción", and specially protected by Law 946/82 "Protection of Cultural Property". In 1896, Lopez's


id: botanical-garden-and-zoo-of-asunci-n-20260505-1
file: data/en.wikipedia.org/wiki/Botanical_Garden_and_Zoo_of_Asunción-1.md
category: reference
title: Botanical Garden and Zoo of Asunción
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Botanical_Garden_and_Zoo_of_Asunción
date_saved: 2026-05-05T10:07:49.175308+00:00
instance: kb-cron
parent: botanical-garden-and-zoo-of-asunci-n-20260505-0
summary:
African lion (Panthera leo ) Bengal tiger (Panthera tigris tigris) Jaguar (Panthera onca) Puma (Puma concolor) Geoffroy's cat (Leopardus geoffroyi ) Ocelot (Leopardus pardalis) Crab-eating fox (Cerdocyon thous) Crab-eating raccoon (Procyon cancrivorus) Ring-tailed coati (Nasua nasua) Tayra (Eira barbara) Fallow deer (Dama dama) Gray brocket deer (Mazama gouazoubira) Domestic goat (Capra aegagrus hircus) White-lipped peccary (Tayassu pecari) Collared peccary (Tayassu tajacu) Tapir (Tapirus terrestris) Common hippopotamus (Hippopotamus amphibius) African savannah elephant (Loxodonta africana) Capybara (Hydrochoerus hydrochaeris) Giant anteater (Myrmecophaga tridactyla) southern tamandua (Tamandua tetradactyla) Common chimpanzee (Pan troglodytes) Black-headed spider monkey (Ateles fusciceps) Azara's night monkey(Aotus azarae) Black howler monkey (Alouatta caraya)) Azaras's capuchin (Sapajus cay paraguayanus) ==== Birds ==== Birds at the zoo include: Chaco eagle or Crowned solitary eagle (Harpyhaliaetus coronatus) Common rhea (Rhea americana) Red-and-green macaw (Ara chloroptera) Monk parakeet (Myiopsitta monachus) Great horned owl (Bubo virginianus) Aplomado falcon (Falco femoralis) Jabiru (Jabiru mycteria) southern crested caracara (Caracara plancus) Southern screamer (Chauna torquata) Nanday parakeet (Aratinga nenday) black vulture or American black vulture(Coragyps atratus) Barn owl (Tyto (sp.)) Burrowing parrot or Patagonian conure (Cyanoliseus patagonus) Blue-fronted amazon (Amazona aestiva) Blue-winged macaw (Primolius maracana) Vinaceous-breasted amazon (Amazona vinacea) Striped owl (Asio clamator) Spectacled owl (Pulsatrix perspicillata) Toco toucan


id: bournemouth-natural-science-society-20260505-0
file: data/en.wikipedia.org/wiki/Bournemouth_Natural_Science_Society-0.md
category: reference
title: Bournemouth Natural Science Society
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bournemouth_Natural_Science_Society
date_saved: 2026-05-05T10:07:50.347678+00:00
instance: kb-cron
parent: bournemouth-natural-science-society-20260505-0
summary:
Bournemouth Natural Science Society is a historic museum in Bournemouth, Dorset, England. == History == The building was constructed circa 1865. The museum holds collections covering Natural History, Geology, Egyptology and Archaeology. In 2019, a project began to restore a lantern roof light. == See also == List of museums in Dorset == References ==


id: croatian-natural-history-museum-20260505-0
file: data/en.wikipedia.org/wiki/Croatian_Natural_History_Museum-0.md
category: reference
title: Croatian Natural History Museum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Croatian_Natural_History_Museum
date_saved: 2026-05-05T10:07:51.545007+00:00
instance: kb-cron
parent: croatian-natural-history-museum-20260505-0
summary:
The Croatian Natural History Museum (Croatian: Hrvatski prirodoslovni muzej) is the oldest and biggest natural history museum and the main body for natural history research, preservation and collection in Croatia. Located on Dimitrije Demeter Street in Gornji Grad, one of the oldest neighbourhoods of the Croatian capital Zagreb, it owns one of the biggest museum collections in Croatia, with over 2 million artefacts, including over 1.1 million animal specimens. It was founded in 1846 as the "National Museum". The National Museum was later split up into five museums, three of which were in 1986 merged as departments of the newly named Croatian Natural History Museum. The museum contains a large scientific library open to the public, and publishes the first Croatian natural history scientific journal, Natura Croatica. The permanent display of the Croatian Natural History Museum consists of mineralogical, petrographical and zoological collections, as well as two permanent exhibits in the atrium: the Rock Map of Croatia and the Geological Pole. It is home to the remains of the Neanderthal from Krapina. In 2021, the museum was closed pending the completion of reconstruction following the 2020 Zagreb earthquake, and then reopened in 2024. == History == The history of the


id: croatian-natural-history-museum-20260505-1
file: data/en.wikipedia.org/wiki/Croatian_Natural_History_Museum-1.md
category: reference
title: Croatian Natural History Museum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Croatian_Natural_History_Museum
date_saved: 2026-05-05T10:07:51.545007+00:00
instance: kb-cron
parent: croatian-natural-history-museum-20260505-0
summary:
The museum is divided into Mineralogical–Petrographical, Geological–Palaeontological, Zoological and Botanical Departments. The first three are successors to the National Museum's 19th-century offspring museums, while the Botanical Department was established in 1990. The museum's holdings number over 2 million rocks, minerals, fossils, and other artefacts collected all over the country. The zoological collection consists of 1,135,000 animal specimens, including a tissue bank for DNA analysis. It also holds the remains of the Neanderthal man found near Krapina by Dragutin Gorjanović-Kramberger, a former director of the National Museum. The original remains are held in the museum's vault, while a replica is being exhibited in the Krapina museum. The museum's permanent display encompasses mineralogical and petrographical collections, as well as a collection of animals, the bulk of which dates back to the 19th century. The zoological collection is on the second floor of the museum. It includes the skeleton of a Mediterranean monk seal, a basking shark native to the Adriatic Sea and an Atlantic puffin, a bird today native to the Arctic area, which is believed to have nested in the Adriatic in the 19th century. The mineralogical and petrographical collections are divided into three exhibitions. "From a Collection to a Museum"


id: cyprus-museum-of-natural-history-20260505-0
file: data/en.wikipedia.org/wiki/Cyprus_Museum_of_Natural_History-0.md
category: reference
title: Cyprus Museum of Natural History
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cyprus_Museum_of_Natural_History
date_saved: 2026-05-05T10:07:52.711815+00:00
instance: kb-cron
parent: cyprus-museum-of-natural-history-20260505-0
summary:
The Cyprus Museum of Natural History (Greek: Κυπριακό Μουσείο Φυσικής Ιστορίας, romanized: Kypriakó Mouseío Fysikís Istorías) is a natural history museum on the outskirts of Nicosia, Cyprus. The museum was founded by the Photos Photiades Charity, Scientific and Cultural Foundation, and is the largest museum of its kind in Cyprus. Its approximately 2,500 exhibits include various embalmed animals including mammals, birds, fish, reptiles, and insects. It also includes rocks, minerals, semi-precious stones, shells, and fossils, showcasing the region's geological history and evolution over millions of years. == References == == External links == Museum website


id: dead-sea-museum-20260505-0
file: data/en.wikipedia.org/wiki/Dead_Sea_Museum-0.md
category: reference
title: Dead Sea Museum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dead_Sea_Museum
date_saved: 2026-05-05T10:07:53.867630+00:00
instance: kb-cron
parent: dead-sea-museum-20260505-0
summary:
The Dead Sea Museum (Arabic: متحف البحر الميت, romanized: Matḥaf al-Baḥr al-Mayyit) is a history and natural history museum located in the Maeen subdistrict, Jordan. The museum is dedicated to showing the history of the Dead Sea and how civilizations developed around it. == History == Among the intentions for the creation was to promote tourism, and to facilitate the public to learn more about how the Dead Sea is constituted. The museum aims to raise awareness about the conservation of the Dead Sea. The construction of the museum was funded by the Japan International Cooperation Agency. The museum first opened in 2006, and is Jordan's first natural history museum. In 2015, for International Museum Day, educational activities for students from the South Jordan Valley were organized in this place. == Collections == The museum contains collections of rocks and minerals The museum exhibits are divided into four sections First section: The geology of the Dead Sea, as well as its formation. Second section: The study of the Dead Sea ecosystem. Third section: The human impact on the Dead Sea as well as the benefits that the existence of this sea has brought to the civilizations of the Middle East.


id: dippy-20260505-0
file: data/en.wikipedia.org/wiki/Dippy-0.md
category: reference
title: Dippy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dippy
date_saved: 2026-05-05T10:07:55.062702+00:00
instance: kb-cron
parent: dippy-20260505-0
summary:
Dippy is a composite Diplodocus skeleton. The original skeleton is in Pittsburgh's Carnegie Museum of Natural History, and the holotype of the species Diplodocus carnegii. It is considered the most famous single dinosaur skeleton in the world, due to the numerous plaster casts donated by Andrew Carnegie to several major museums around the world at the beginning of the 20th century. One well known cast in the United Kingdom was displayed at the Natural History Museum in London from 1905 until 2017. The casting and distribution of the skeleton made the word dinosaur a household word; for millions of people it became the first dinosaur they had ever seen. It was also responsible for the subsequent popularity of the entire genus Diplodocus, since the skeleton has been on display in more places than any other sauropod dinosaur. Its discovery was catalyzed by the announcement of the excavation of a large thigh bone (unrelated to Dippy) by William Reed near Medicine Bow, Wyoming in December 1898. On a return trip financed by Carnegie, Reed excavated Sheep Creek Quarry D in which he found the first part of Dippy's skeleton, a toe bone, on July 4, 1899. Its discovery on Independence Day,


id: dippy-20260505-1
file: data/en.wikipedia.org/wiki/Dippy-1.md
category: reference
title: Dippy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dippy
date_saved: 2026-05-05T10:07:55.062702+00:00
instance: kb-cron
parent: dippy-20260505-0
summary:
=== Early history === The London cast of Dippy came about when King Edward VII, then a keen trustee of the British Museum, saw a sketch of the bones at Carnegie's Scottish home, Skibo Castle, in 1902, and Carnegie agreed to donate a cast to the Natural History Museum as a gift. Carnegie paid £2,000 for the casting in plaster of paris, copying the original fossil bones held by the Carnegie Museum (not mounted until 1907, as a new museum building was still being constructed to house it).The 292 cast pieces of the skeleton were sent to London in 36 crates, and the 25.6 metres (84 ft) long exhibit was unveiled on May 12, 1905, to great public and media interest, with speeches from the museum director Professor Ray Lankester, Andrew Carnegie, Lord Avebury on behalf of the trustees, the director of the Carnegie Museum William Jacob Holland, and finally the geologist Sir Archibald Geikie. The cast was mounted in the museum's Reptile Gallery to the left of the main hall (until recently the gallery of Human Biology) as it was too large to display in the Fossil Marine Reptile Gallery (to the right of the main hall). Dippy was


id: estonian-museum-of-natural-history-20260505-0
file: data/en.wikipedia.org/wiki/Estonian_Museum_of_Natural_History-0.md
category: reference
title: Estonian Museum of Natural History
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Estonian_Museum_of_Natural_History
date_saved: 2026-05-05T10:07:56.201383+00:00
instance: kb-cron
parent: estonian-museum-of-natural-history-20260505-0
summary:
The Estonian Museum of Natural History (EMNH; Estonian: Eesti Loodusmuuseum) is the Estonian national museum for natural history. It is situated in Tallinn's Old Town. The museum focuses on natural history and nature education, offering its visitors a tour in the wilderness of Estonia. == History == The origins of the museum goes back to the Estonian Literary Society's museum founded in 1842 and renamed to the Provincial Museum in 1864. This museum was active in exploring the natural sciences, an area that increased in significance at the museum in 1872 when Alexander von der Pahlen (1820–1895) began to contribute to the collection. Pahlen was later elected chairman and under his leadership the collection continued to grow. As the collection grew, a new building on Kohtu Street was purchased in 1911 to house it. During World War I, due to passive resistance, the museum's collection were not moved to Russia. The Provincial Museum continued to operate under the Arts and Heritage Department of the Minister of Education and Research but changed its name to the Museum of the Estonian Literary Society in 1926. After the Molotov–Ribbentrop Pact, Baltic-German institutions, including the Estonian Literary Society, were closed. In 1940, through the


id: gozo-nature-museum-20260505-0
file: data/en.wikipedia.org/wiki/Gozo_Nature_Museum-0.md
category: reference
title: Gozo Nature Museum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Gozo_Nature_Museum
date_saved: 2026-05-05T10:07:57.428881+00:00
instance: kb-cron
parent: gozo-nature-museum-20260505-0
summary:
The Gozo Nature Museum, formerly known as the Natural Science Museum, is a museum in Victoria, on the island of Gozo, Malta. Open to public since 1991, the museum is housed in a group of houses in the Cittadella, the oldest part of the city. These houses date back to various ages: the older one, which was an inn, to 1495; the other to the 17th century. The Natural Science Museum shows collections "relating to the Island’s geology, minerals, marine life, insects, local habitats and ecosystems" as well as national plants (including the Maltese Rock Centaury), human and animal evolution. During later years, this building was used as an inn for visitors, and is mentioned in Thomas McGill’s “Handbook, or Guide, for Strangers visiting Malta” of 1839, and described as: an excellent house of entertainment offering clean and comfortable beds and reasonably-priced dinners. During World War II the building served as a shelter for families during aerial bombings. The buildings which house the museum are listed on the National Inventory of the Cultural Property of the Maltese Islands. == See also == List of museums in Malta == References == == External links == Official website museum on Official Malta


id: guatemalan-national-natural-history-museum-20260505-0
file: data/en.wikipedia.org/wiki/Guatemalan_National_Natural_History_Museum-0.md
category: reference
title: Guatemalan National Natural History Museum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Guatemalan_National_Natural_History_Museum
date_saved: 2026-05-05T10:07:58.616369+00:00
instance: kb-cron
parent: guatemalan-national-natural-history-museum-20260505-0
summary:
The Guatemalan National Natural History Museum (Spanish: Museo de Historia Natural 'Jorge A. Ibarra') is a national natural history museum in Guatemala City, Guatemala. It was founded in 1950 and moved to its present facility in 1986. It was renamed in honor of its founder and long-term director, Jorge A. Ibarra. == References == == External links == Official website


id: gustavo-orc-s-v-natural-history-museum-20260505-0
file: data/en.wikipedia.org/wiki/Gustavo_Orcés_V._Natural_History_Museum-0.md
category: reference
title: Gustavo Orcés V. Natural History Museum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Gustavo_Orcés_V._Natural_History_Museum
date_saved: 2026-05-05T10:07:59.747039+00:00
instance: kb-cron
parent: gustavo-orc-s-v-natural-history-museum-20260505-0
summary:
Gustavo Orcés V. Natural History Museum (Spanish: Museo de Historia Natural Gustavo Orcés V.) is a natural history museum in Quito, Ecuador. It was established in 2005. == Background == From the eighteenth century European naturalists came to Ecuador for scientific expeditions, during which they collected specimens of flora, fauna, rocks and fossils. In the early twentieth century, Franz Spillmann brought together a collection of fossils, which formed the "Cabinet of Natural Sciences" of the Central University. Later, in 1946, Robert Hoffstetter and Gustavo Orcés founded the Department of Biology at the National Polytechnic School, and made numerous paleontological expeditions, particularly in the Santa Elena peninsula. Hoffstetter’s extensive work and organization formed the basis of the modern museum. == References ==


id: hasanbey-zardabi-natural-history-museum-20260505-0
file: data/en.wikipedia.org/wiki/Hasanbey_Zardabi_Natural_History_Museum-0.md
category: reference
title: Hasanbey Zardabi Natural History Museum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hasanbey_Zardabi_Natural_History_Museum
date_saved: 2026-05-05T10:08:00.908048+00:00
instance: kb-cron
parent: hasanbey-zardabi-natural-history-museum-20260505-0
summary:
The Hasanbey Zardabi Natural History Museum (Azerbaijani: Həsən bəy Zərdabi adına Təbiət Tarixi Muzeyi) is a natural history museum in Baku, Azerbaijan. The museum bears the name of Hasan bey Zardabi, an Azerbaijani journalist and intellectual, and founder of the first Azeri-language newspaper Akinchi ("The Ploughman") in 1875. The museum has two departments: a geology department that has samples of metallic and nonmetallic natural resources and minerals and rocks of Azerbaijan and a zoology department. The general collection of the museum numbers more than 1400 different items. The biological department exhibits numerous skeletons and fragments of animal bones found during field work and treated by researchers. The oldest exhibit is the teeth of an ichthyosaur from the Cretaceous period, more than 120 million years old. The research activities of the Natural History Museum have developed in several directions, focused especially on paleontological sites. The main research focuses on the study of the Binagadi quaternary and the Eldar late Sarmatian hipparion faunas, Pirekishkuli Maykop vertebrate fauna, numerous sites of primitive people, as well as Azokh cave and others. In the collection of the quaternary fauna of Binagadi, there are 41 species of mammals, 110 species of birds, 2 reptiles, 1 amphibian,


id: international-inventories-programme-20260505-0
file: data/en.wikipedia.org/wiki/International_Inventories_Programme-0.md
category: reference
title: International Inventories Programme
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/International_Inventories_Programme
date_saved: 2026-05-05T10:08:02.043688+00:00
instance: kb-cron
parent: international-inventories-programme-20260505-0
summary:
The International Inventories Programme (IIP) is an international research and database project for investigating objects pertaining to the cultural heritage of Kenya that are held in cultural institutions like ethnographic museums across the globe. The programme is jointly run by the National Museums of Kenya in Nairobi, the Rautenstrauch-Joest Museum in Cologne and the Weltkulturen Museum in Frankfurt a. M., both in Germany. To establish a direct relation to contemporary cultural activities both in Kenya and in Germany, the multi-disciplinary arts groups The Nest Collective (Kenya) and SHIFT Collective in Germany and France are further members of the IIP. - The programme and its projects are supported by the Goethe-Institut - German cultural centre in Kenya - and the German Federal Cultural Foundation. == Background and international cooperation == The IIP was publicly launched in 2018, and was described by Quartz Africa magazine as "a movement to investigate the cultural artifacts stolen and kept outside the country’s borders (...) exploring where in the West they are actually housed, who holds the agency to demand their repatriation, and how their historical and cultural legacy can be harnessed for sustainable and creative development.” As much of Kenya's cultural heritage is inaccessible both


id: kitale-museum-20260505-0
file: data/en.wikipedia.org/wiki/Kitale_Museum-0.md
category: reference
title: Kitale Museum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Kitale_Museum
date_saved: 2026-05-05T10:08:03.196256+00:00
instance: kb-cron
parent: kitale-museum-20260505-0
summary:
The Kitale Museum is a regional museum located in Kitale, Trans-Nzoia County, Kenya. Operating under the National Museums of Kenya (NMK) network, it holds the distinction of being the first regional museum to be integrated into the national system. In February 2024, it became the first national museum in the country to transition to the management of a county government under the Kenya devolution framework. While it maintains a technical partnership with the NMK, the facility is currently managed by the Trans-Nzoia County Government, which oversees its daily operations, budget, and staff. The museum originated from the private collection of Lieutenant Colonel Hugh Stoneham established in 1926 and was officially nationalized in 1974. It features natural history exhibitions and ethnographic displays including traditional Kenyan homesteads. Following Stoneham's death in 1966, the collection was bequeathed to the Kenyan government on the condition that a permanent museum be established in Kitale. In 1974, the facility was officially nationalized and opened to the public as the first regional branch of the NMK. Today, the museum is notable for its outdoor exhibits of traditional homesteads representing the Luhya, Maasai, and Kalenjin cultures, as well as a nature trail through a protected riverine known as


id: latvian-museum-of-natural-history-20260505-0
file: data/en.wikipedia.org/wiki/Latvian_Museum_of_Natural_History-0.md
category: reference
title: Latvian Museum of Natural History
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Latvian_Museum_of_Natural_History
date_saved: 2026-05-05T10:08:04.336595+00:00
instance: kb-cron
parent: latvian-museum-of-natural-history-20260505-0
summary:
The Latvian National Museum of Natural History (Latvian: Latvijas Nacionālais dabas muzejs) is a natural history museum in Riga, Latvia. It was founded in 1845 as the Riga Naturalist Society (German: Naturforscherverein zu Riga). The museum contains the following Departments: Custodial Botany Zoology Geology and Palaeontology Technological Support Communications Administration == External links == Official site


id: lebanese-marine-and-wildlife-museum-20260505-0
file: data/en.wikipedia.org/wiki/Lebanese_Marine_and_Wildlife_Museum-0.md
category: reference
title: Lebanese Marine and Wildlife Museum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Lebanese_Marine_and_Wildlife_Museum
date_saved: 2026-05-05T10:08:05.545747+00:00
instance: kb-cron
parent: lebanese-marine-and-wildlife-museum-20260505-0
summary:
The Lebanese Marine and Wildlife Museum (Arabic: المتحف اللبناني للحياة البحرية و البرية, al-matḥaf al-lubnani lil-hayat al-bahriya wa al-bariya) is a zoological museum in Jeita. Its goals are to study Lebanon's ecosystem, encourage preservation, and maintain a scientific archive of Lebanon's wildlife and the Mediterranean marine life. == History == The Museum was first opened in Tyre in 2001. == Collections == The Lebanese Marine and Wildlife Museum has over 2000 species with over 5000 specimen. The museum currently contains 6 Exhibits: === Mammals === Displaying over 30 of Lebanon's mammals which once roamed freely the forests of Lebanon, most of which are now critically endangered, due to deforestation, indiscriminate hunting and habitat destruction. === Birds === The Museum Has over 200 species of birds === Reptiles === over 20 species of lizards and 30 species of snakes === Minerals, Gems and Fossils === over 300 specimens of minerals and gems === Seashells === The seashell collections contains over 200 seashell species from the Mediterranean and over 300 of the largest seashells from around the world. === Marine life === This display contains over 40 species sharks, in additions to fish, crabs, cephalopods, crustaceans, sea turtles, dolphins and a monk


id: lee-kong-chian-natural-history-museum-20260505-0
file: data/en.wikipedia.org/wiki/Lee_Kong_Chian_Natural_History_Museum-0.md
category: reference
title: Lee Kong Chian Natural History Museum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Lee_Kong_Chian_Natural_History_Museum
date_saved: 2026-05-05T10:08:06.718966+00:00
instance: kb-cron
parent: lee-kong-chian-natural-history-museum-20260505-0
summary:
The Lee Kong Chian Natural History Museum (LKCNHM; Malay: Muzium Sejarah Alamiah Lee Kong Chian, Chinese: 李光前自然历史博物馆; pinyin: Lǐguāngqián zìrán lìshǐ bówùguǎn) is a museum of natural history at the Kent Ridge Campus of the National University of Singapore. It is named after Lee Kong Chian, a prominent Chinese businessman and philanthropist active in Malaya and Singapore between the 1930s and the 1960s. It was officially opened on 18 April 2015. The idea for a natural history collection was first mooted by Sir Stamford Raffles, and the collection of Southeast Asian biodiversity was begun in 1849 at the Raffles Museum (now the National Museum of Singapore). In 1972, the Government of Singapore removed the natural history collections from the National Museum and gave them to the Zoology Department of what was then the University of Singapore. They were housed in various temporary premises, including the Nanyang Technological University for seven years. Subsequently, they were returned to the NUS and housed in the Raffles Museum of Biodiversity Research. LKCNHM inherited the natural history collections from the Raffles Museum of Biodiversity Research. The Museum currently has more than 560,000 catalogued lots in its collection and over a million specimens from throughout the


id: list-of-sites-and-monuments-in-kenya-20260505-0
file: data/en.wikipedia.org/wiki/List_of_sites_and_monuments_in_Kenya-0.md
category: reference
title: List of sites and monuments in Kenya
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/List_of_sites_and_monuments_in_Kenya
date_saved: 2026-05-05T10:08:07.992336+00:00
instance: kb-cron
parent: list-of-sites-and-monuments-in-kenya-20260505-0
summary:
This is a list of sites and monuments of historic value that are maintained by the National Museums of Kenya. == Historic sites == == See also == List of museums in Kenya == References == == External links == Hassan, Mohamed (27 April 2019). "NMK Seek More Funds To Protect Historical Sites, Monuments". Kenya News Agency. Retrieved 11 October 2010. "Overview". Kenya Wildlife Service. Retrieved 11 October 2010.


id: national-museum-of-natural-history-luxembourg-20260505-0
file: data/en.wikipedia.org/wiki/National_Museum_of_Natural_History,_Luxembourg-0.md
category: reference
title: National Museum of Natural History, Luxembourg
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/National_Museum_of_Natural_History,_Luxembourg
date_saved: 2026-05-05T10:08:09.168043+00:00
instance: kb-cron
parent: national-museum-of-natural-history-luxembourg-20260505-0
summary:
The National Museum of Natural History (Luxembourgish: Nationalmusée fir Naturgeschicht, French: Musée national d'histoire naturelle, German: Nationalmuseum für Naturgeschichte) is a natural history museum in Luxembourg City, in southern Luxembourg. The museum is located in the Grund quarter on the eastern bank of the Alzette river, next to the Neumünster Abbey cultural centre. The museum is composed of eight separate scientific sections, spanning the natural sciences: botany, ecology, geology and mineralogy, geophysics and astrophysics, palaeontology, vertebrate zoology, and invertebrate zoology. == History == The Society of the Natural Sciences was established in 1850, under the patronage of Prince Henry, the newly appointed Governor of Luxembourg representing Grand Duke William III. The society's primary aim was the promotion of the natural sciences and natural history to the general population. To achieve this, the government put at the society's disposal a section of the city Athenaeum, now the National Library. Opening its doors in 1854, this area hosted a number of cabinets displaying fossil specimens, spread across three rooms. After almost four decades of this arrangement, pressure for display area caused the museum to move into its own premises, at the Vauban Barracks in Pfaffenthal, in 1892. However, these were criticised for


id: national-museum-malaysia-20260505-0
file: data/en.wikipedia.org/wiki/National_Museum_(Malaysia)-0.md
category: reference
title: National Museum (Malaysia)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/National_Museum_(Malaysia)
date_saved: 2026-05-05T10:08:10.309796+00:00
instance: kb-cron
parent: national-museum-malaysia-20260505-0
summary:
The National Museum (Malay: Muzium Negara) is a public museum in Kuala Lumpur, Malaysia dedicated to Malaysian art, culture, and history. Located on Jalan Damansara close to Perdana Lake Gardens across KL Sentral station. Its façade comprises elements from both traditional Malay and modern features. It was inaugurated on 31 August 1963. The National Museum is a three-story structure, 109.7 metres (359 ft 11 in) long and 15.1 metres (49 ft 6 in) wide, which is 37.6 metres (123 ft 4 in) high at the central point. The museum houses four main galleries allotted to ethnology and natural history (geology). The displays range from free-standing tableaux showing cultural events like weddings, festivals and costumes; to traditional weapons, musical instruments, arts and crafts, ceramics, and flora and fauna. == History == === The Old Selangor Museum === Selangor Museum was the de facto national museum pre-independence. Selangor Museum was established in 1887 as an amateur affair by colonial civil servants. It was taken over by the colonial government, and following the formation of the Federated Malay States in 1896, in 1904 it was administratively merged with the Perak Museum in Taiping as the Federated Malay States Museums under director Leonard Wray


id: national-museum-malaysia-20260505-1
file: data/en.wikipedia.org/wiki/National_Museum_(Malaysia)-1.md
category: reference
title: National Museum (Malaysia)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/National_Museum_(Malaysia)
date_saved: 2026-05-05T10:08:10.309796+00:00
instance: kb-cron
parent: national-museum-malaysia-20260505-0
summary:
Other galleries include the National Sports Gallery and the Natural History Gallery. In the vicinity of the museum building, there are a number of outdoor displays of transportation in Malaysia, past and present. The Melaka Bullock Cart exhibit closely resembles the early American horse-drawn wagon. Of unparalleled interest are the Steam Locomotive made by Kitson & Co, England, which was put into service in 1921 until it ceased operation in 1969. It covered 1.5 million rail miles; a Tin Dredge which resembles a floating factory, on a natural or artificial lake. Also on display are motorized vehicles, including antiqued civic vehicles and private vehicles, including an early 1.3 liter Proton Saga, the first national car launched on July 9, 1985. In addition, there are two monuments in the grounds: a bronze bust of King Edward VII, and a statue of Sir Frank Swettenham. National Museum also holds regular thematic exhibitions featuring specific aspects of life and world culture. === Central Hall === Adorning the floor of the Central Hall are blue geometric-design mosaic tiles from Pakistan, with intricate carved panels on the ceiling of the hall. The Central Hall houses temporary exhibitions, and thematic and special exhibitions are held at


id: marine-exhibition-center-of-punta-culebra-20260505-0
file: data/en.wikipedia.org/wiki/Marine_Exhibition_Center_of_Punta_Culebra-0.md
category: reference
title: Marine Exhibition Center of Punta Culebra
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Marine_Exhibition_Center_of_Punta_Culebra
date_saved: 2026-05-05T10:08:11.477332+00:00
instance: kb-cron
parent: marine-exhibition-center-of-punta-culebra-20260505-0
summary:
The Punta Culebra Nature Center (Spanish: Centro de Exhibiciones Marinas de Punta Culebra) is a visitor center located in Panama City, on one of the islands connected by the Amador Causeway. It is operated by the Smithsonian Tropical Research Institute, also located in Panama. The center focuses mainly on marine and terrestrial science and education, conservation and interpretation of marine coastal environments in the tropics. Among its attractions, the Fabulous Frogs of Panama, a touch tank with equinoderms and turtles are some of the exhibits found in Punta Culebra. A trail to a stretch of tropical dry forest is also part of the attractions where free roaming animals such as raccoons, sloths, green iguanas and beautiful birds and butterflies can be found. == References == == External links == Punta Culebra Nature Center official site


id: mongolian-natural-history-museum-20260505-0
file: data/en.wikipedia.org/wiki/Mongolian_Natural_History_Museum-0.md
category: reference
title: Mongolian Natural History Museum
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mongolian_Natural_History_Museum
date_saved: 2026-05-05T10:08:12.622406+00:00
instance: kb-cron
parent: mongolian-natural-history-museum-20260505-0
summary:
The Natural History Museum (Mongolian: Байгалийн түүхийн музей, romanized: Baigaliin tüükhiin muzyei) is a repository and research institution located in Chingeltei, Ulaanbaatar, Mongolia. The museum was previously known as the Mongolian National Museum or State Central Museum. The museum includes Departments of Geology, Geography, Flora and Fauna, Paleontology, and Anthropology encompassing the natural history of Mongolia. The museum's holdings include more than 15000 specimens, 45% of which were on permanent public display. The museum is particularly well known for its dinosaur and other paleontological exhibits, among which the most notable are a nearly complete skeleton of a late Cretaceous Tarbosaurus tyrannosaurid and broadly contemporaneous nests of Protoceratops eggs. == History == The museum was established in 1924 as the National Museum (Mongolian: Үндэсний музей). In 1940–1941, it became known as the Rural Research Museum (Mongolian: Орон нутаг судлах музей) and in 1956 as the State Central Museum (Mongolian: Улсын төв музей). It received its current designation after 1991. Authorities deemed the museum's 1953 building to be highly susceptible to natural disasters such as earthquakes in a study made in 2013. The museum was closed in June 2013, with its exhibits put into storage or displayed at other venues. Initial plans


