| PSIL | preferred frequency speech interference level |
|---|---|
| RFI | radiofrequency interference; recurrence-free interval; renal failure index |
| RI | radiation intensity; radioactive isotope; radioimmunology; recession index; recombinant inbred [stra... |
| SIL | soluble interleukin; speech interference level |
| SQUID | superconducting quantum interference device |
| aperture for electron microscopy | <technique> Anode aperture: The opening in the accelerating voltage anode shield of the electron gun through which the electrons must pass to irradiate the specimen. Condenser aperture: An opening in the condenser lens controlling the number of electrons entering the lens and the angular aperture of the electron beam. The angular aperture can also be controlled by the condenser lens current. Physical objective aperture: A metallic diaphragm, with a small central hole, used to limit the cone of electrons accepted by the objective lens. This improves image-contrast since highly scattered electrons are prevented from arriving at the Gaussian image plane and therefore cannot contribute to background fog. Aplanatic. Free from spherical aberration and coma. (05 Aug 1998) |
|---|---|
| bright field microscopy | <technique> Optical microscopy, in which absorption to a great extent and diffraction to a minor extent give rise to the image, as opposed to phase contrast or interference methods of microscopy. (18 Nov 1997) |
| ratio imaging fluorescence microscopy | <procedure> A method of measurement of intracellular pH or intracellular calcium levels, using a fluorescent probe molecule (see fura-2), in which the two different excitation wavelengths are used and the emitted light levels compared. If emission at one wavelength is sensitive to the intracellular ion level and emission at the other wavelength is not, then standardisation for intracellular probe concentration, efficiency of light collection, inactivation of probe and thickness of cytoplasm can all be performed automatically. (17 Dec 1997) |
| reflection X-ray microscopy | <technique> A method of producing enlarged images by means of X rays. In this method the radiation is totally reflected at glancing incidence from polished concave mirrors or from the curved surfaces of single crystals by Bragg reflection. The problem of aberration corrections still limits the resolution obtainable. (05 Aug 1998) |
| video microscopy | <technique> Microscopy that takes advantage of video as an imaging, image processing, analysing, or controlling device. (05 Aug 1998) |
| phase contrast microscopy | <investigation> A simple nonquantitative form of interference micoscopy of great utility in visualising live cells. Small differences in optical path length due to differences in refractive index and thickness of structures are visualised as differences in light intensity. (18 Nov 1997) |
| microscopy | <technique> The science of the interpretive use, and applications of microscopes. (05 Aug 1998) |
| microscopy, atomic force | Microscopy in which a probe systematically rides across the surface of a sample being scanned in a raster pattern. The vertical position is recorded as a spring attached to the probe rises and falls in response to peaks and valleys on the surface. A microcomputer keeps track of the vertical excursions as a function of the position of the probe in the horizontal plane and presents the sample's image. (12 Dec 1998) |
| microscopy, confocal | A light microscopic technique in which only a small spot is illuminated and observed at a time. An image is constructed through point-by-point scanning of the field in this manner. Light sources may be conventional or laser, and fluorescence or transmitted observations are possible. (12 Dec 1998) |
| microscopy, electron | Visual and photographic microscopy in which electron beams with wavelengths thousands of times shorter than visible light are used in place of light, thereby allowing much greater magnification. (12 Dec 1998) |
| microscopy, electron, scanning | Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point, giving the surface image a three-dimensional quality. (12 Dec 1998) |
| microscopy, electron, scanning transmission | A type of electron microscopy which scans with an extremely narrow beam that is transmitted through the sample. The detection apparatus produces an image whose brightness depends on the atomic number of the sample. It should not be confused with microscopy, electron scanning nor with microscopy, electron, transmission (see microscopy, electron). (12 Dec 1998) |
| microscopy, fluorescence | Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilises antibodies that are labelled with fluorescent dye. (12 Dec 1998) |
| microscopy, immunoelectron | Microscopy in which the samples are first stained immunocytochemically and then examined using an electron microscope. Immunoelectron microscopy is used extensively in diagnostic virology as part of very sensitive immunoassays. (12 Dec 1998) |
| 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) |