| AEM | Academic Emergency Medicine [journal]; analytical electron microscopy; ambulatory electrocardiograph... |
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| AES | acetone-extracted serum; American Electroencephalographic Society; American Encephalographic Society... |
| ANAP | agglutination negative, absorption positive [reaction] |
| ANLI | antibody-negative with latent infection |
| ATEM | analytic transmission electron microscopy |
| negative taxis | The repulsion of protoplasm away from a stimulus. (05 Mar 2000) |
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| negative thermotaxis | Repulsion of a plant or animal from heat. (05 Mar 2000) |
| negative transference | Transference characterised by predominantly hostile feelings on the part of the patient toward the analyst. (05 Mar 2000) |
| eyepiece, negative | <microscopy> An ocular in which the real image of the object is formed between two lenses. The Huygens type. (05 Aug 1998) |
| false negative | <statistics> A term used to indicate a test showed an incorrect negative result. (16 Dec 1997) |
| false-negative reaction | <statistics> An erroneous or mistakenly negative response. Negative test results in subjects who possess the attribute for which the test is conducted. The labeling of diseased persons as healthy when screening in the detection of disease. (05 Mar 2000) |
| lens, negative | <microscopy> A lens that is thicker on the edges than in the centre, and which causes parallel light rays to diverge. Synonym: diverging lens. (05 Aug 1998) |
| lower body negative pressure | External decompression applied to the lower body. It is used to study orthostatic intolerance and the effects of gravitation and acceleration, to produce simulated haemorrhage in physiologic research, to assess cardiovascular function, and to reduce abdominal stress during childbirth. (12 Dec 1998) |
| 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) |
| Auger electron | An electron ejected from a lower energy orbital after a photoelectric interaction of an X-ray photon with a K-shell electron by the characteristic radiation photon; the Auger electron recoils with energy equal to the characteristic radiation less the difference in shell binding energies. See: photoelectric effect. (05 Mar 2000) |
| backscattered electron | <microscopy> Produced by an incident electron colliding with the nucleus of an atom in the specimen. The incident electron is then scattered backward about 180 degrees with no appreciable loss of energy, an elastic collision. (05 Aug 1998) |
| backscattered electron imaging | <microscopy> The production of backscattered electrons from a sample varies directly with the specimen's average atomic number, higher atomic number elements produce more backscattered electrons than lower atomic number ones. Detection of Backscattered Electrons is achieved by using a donut shaped solid state saemiconductor device mounted on the bottom of the objective lens. When Backscattered Electrons strike the detector electron-hole pairs are created which are then counted. This quantity is translated into a pixel intensity and displayed on the CRT, forming the image. By splitting the detector into halves (or quadrants) differences in the signal level on the individual detector segments provide surface topography information. (05 Aug 1998) |
| valence electron | One of the electron's that take part in chemical reactions of an atom. (05 Mar 2000) |
| Parallel Electron Energy Loss Spectroscopy | <technique> Electron energy loss spectroscopy analyses the inelastically scattered electrons present in the beam after it has been transmitted through the sample. An electron energy loss spectrum typically consists of a monatomic decreasing background on which are superimposed a number of peaks. Each peak is characteristic of the scattering process that has occurred in the sample. The peaks can be used to obtain information about the chemical composition and electronic structure of the sample. Electron energy loss spectra are acquired typically in a magnetic sector spectrometer located under the camera chamber of the transmission electron microscope. Spatial resolution is typically limited by the minimum probe diameter of the microscope. Electron energy loss spectroscopy tends to be complimentary to EDS in that it can be used to analyse very thin samples of low Z materials. Acronym: PEELS (05 Aug 1998) |
| reverse electron transport | <chemistry> The energy-dependent movement of electrons against the thermodynamic gradient to form a strong reductant from a weaker electron donor. (11 Jan 1998) |