| AMR | acoustic muscle reflex; activity metabolic rate; acute mitral stenosis; alopecia-mental retardation ... |
|---|---|
| AN | acanthosis nigricans; acne neonatorum; acoustic neuroma; adult, normal; ala nasi; amyl nitrate; aneu... |
| ANT | acoustic noise test; adenine nucleotide translocator; aminonitrothiazole; anterior |
| ART | absolute retention time; Accredited Record Technician; acoustic reflex test; algebraic reconstructio... |
| EAM | episodic ataxia with myokymia; external acoustic meatus |
| microscopy, phase-contrast | A form of interference microscopy in which variations of the refracting index in the object are converted into variations of intensity in the image. This is achieved by the action of a phase plate. (12 Dec 1998) |
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| microscopy, polarization | Microscopy using polarised light in which phenomena due to the preferential orientation of optical properties with respect to the vibration plane of the polarised light are made visible and correlated parameters are made measurable. (12 Dec 1998) |
| microscopy, scanning tunneling | Electron microscopy in which a very sharp conducting needle is swept just a few angstroms above the surface of a sample. The tiny tunneling current that flows between the sample and the needle tip is measured and from this are produced three-dimensional topographs, with a lateral resolution often as good as 1-2 angstroms and a vertical resolution of less than 1 angstrom. Due to their composition, biological samples are usually coated with a conductive layer, e.g., by depositing a thin metal or carbon film on top of the sample, to enhance their conductivity. (12 Dec 1998) |
| microscopy, ultraviolet | Microscopy in which the image is formed by ultraviolet radiation and is displayed and recorded by means of photographic film. (12 Dec 1998) |
| microscopy, video | Microscopy in which television cameras are used to brighten magnified images that are otherwise too dark to be seen with the naked eye. It is used frequently in telepathology. (12 Dec 1998) |
| confocal microscopy | <procedure> A system of (usually) epifluorescence light microscopy in which a fine laser beam of light is scanned over the object through the objective lens. The technique is particularly good at rejecting light from outside the plane of focus and so produces higher effective resolution than is normally achieved. (18 Nov 1997) |
| Conventional Transmission Electron Microscopy | <technique> A term applied to 'normal' transmission electron microscopy imaging. The electron beam is passed through a thin film sample (typically ~1-200 nm thick). Bright field diffraction contrast images are formed with the direct (undiffracted) beam. Dark field images are formed with a selected diffracted beam. CTEM imaging is used in the general observation of samples and careful selection of the diffracting conditions of the sample will allow the analysis of defect structures within the sample. (05 Aug 1998) |
| polarization microscopy | <procedure> Any form of microscopy capable of detecting birefringent objects. Usually performed with a polarizing element below the stage to produce plane polarized light and an analyser that is set to give total extinction of the background and thus to detect any birefringence. (18 Nov 1997) |
| scanning electron microscopy | <procedure> Technique of electron microscopy in which the specimen is coated with heavy metal and then scanned by an electron beam. The image is built up on a monitor screen (in the same way as the raster builds a conventional television image). The resolution is not so great as with transmission electron microscopy, but preparation is easier (often by fixation followed by critical point drying), the depth of focus is relatively enormous, the surface of a specimen can be seen (though not the interior unless the specimen is cracked open) and the image is aesthetically pleasing. (18 Nov 1997) |
| Scanning Probe Microscopy | <technique> Initially called Atomic Force Microscopy, this technique is now more typically termed Scanning Force Microscopy or Scanning Probe Microscopy. This instrument is essentially an extremely high resolution profilometre. A sharp tip, typically fabricated from silicon nitride, is scanned across the surface of a sample at a constant force by three piezoelectric ceramics. The piezoelectric ceramics are computer controlled via a feedback loop which monitors the position of the tip by means of an optical lever. (A laser is focused on the top of the tip support and the beam reflected into a position sensitive detector). The changes in height of the tip are used to form an image as the tip is scanned across the sample. Acronym: SPM (26 Mar 1998) |
| scanning transmission electron microscopy | <procedure> Method of electron microscopy in which image formation depends upon analysis of the pattern of energies of electrons that pass through the specimen. Has comparable resolving power to conventional transmission EM. (18 Nov 1997) |
| scanning tunnelling microscopy | <procedure> A form of ultra high resolution microscopy of a surface in which a very small current is passed through a surface and is detected by a microprobe of atomic dimnensions at its tip that scans the surface by use of a piezodrive. In the simplest form the current transferred to the probe is recorded as an indication of the contours of molecules on the surface above the local plane. In more complex forms feedback is used to hold the probe at a constant difference and the signal in the feedback loop indicates the contours of the molecule. Capable of resolving single atoms and known to work for nonconducting molecules as well as conducting ones. (18 Nov 1997) |
| high extinction microscopy | <technique> Polarized-light, interference, fluorescence, and other modes of microscopy using polarization rectifiers and other devices to achieve a high degree of back- ground extinction in order to bring out the signal originating from a very small degree of birefringence, optical path difference, fluorescence etc. (05 Aug 1998) |
| holographic microscopy | <technique> A mode of light microscopy in which a highly coherent, laser beam is split into a reference and main beam, with the reference beam (usually travelling outside of the microscope) being made to interfere with the main beam that has passed through the specimen. The interference of the two mutually coherent beams forms a hologram. The depth of field gained by viewing the hologram is essentially infinitely great, and the contrast mode or observation can be switched to dark field, phase contrast, interference contrast, etc., after the hologram has been formed by the microscope in bright field. (05 Aug 1998) |
| nanovid microscopy | <procedure> Technique of bright field light microscopy using electronic contrast enhancement and maximum numerical aperture. (18 Nov 1997) |