| PRVEP | pattern reversal visual evoked potential |
|---|---|
| CIDEP | chemically induced dynamic electron polarization |
| CIDNP | chemically induced dynamic nuclear polarization |
| DEPT | distortionless enhancement by polarization transfer |
| FP | false positive; family physician; family planning; family practice; family practitioner; Fanconi pan... |
| CP | Cross-polarization |
|---|---|
| DNP | Dynamic nuclear polarization |
| FP | FLuorescence polarization |
| GP | Generalized Polarization |
| PREP | Pattern Reversal Evoked Potential |
| angle of polarization | <optics> The angle of incidence at which the reflected light is all polarised. (05 Mar 2000) |
|---|---|
| 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) |
| polarization | 1. The act of polarizing; the state of being polarized, or of having polarity. 2. <optics> A peculiar affection or condition of the rays of light or heat, in consequence of which they exhibit different properties in different directions. If a beam of light, which has been reflected from a plate of unsilvered glass at an angle of about 56 deg, be received upon a second plate of glass similar to the former, and at the same angle of incidence, the light will be readily reflected when the two planes of incidence are parallel to each other, but will not be reflected when the two planes of incidence are perpendicular to each other. The light has, therefore, acquired new properties by reflection from the first plate of glass, and is called polarized light, while the modification which the light has experienced by this reflection is called polarization. The plane in which the beam of light is reflected from the first mirror is called the plane of polarization. The angle of polarization is the angle at which a beam of light must be reflected, in order that the polarization may be the most complete. The term polarization was derived from the theory of emission, and it was conceived that each luminous molecule has two poles analogous to the poles of a magnet; but this view is not now held. According to the undulatory theory, ordinary light is produced by vibrations transverse or perpendicular to the direction of the ray, and distributed as to show no distinction as to any particular direction. But when, by any means, these, vibrations are made to take place in one plane, the light is said to be plane polarized. If only a portion of the vibrations lie in one plane the ray is said to be partially polarized. Light may be polarized by several methods other than by reflection, as by refraction through most crystalline media, or by being transmitted obliquely through several plates of glass with parallel faces. If a beam of polarized light be transmitted through a crystal of quartz in the direction of its axis, the plane of polarization will be changed by an angle proportional to the thickness of the crystal. This phenomenon is called rotatory polarization. A beam of light reflected from a metallic surface, or from glass surfaces under certain peculiar conditions, acquires properties still more complex, its vibrations being no longer rectilinear, but circular, or elliptical. This phenomenon is called circular or elliptical polarization. 3. <physics> An effect produced upon the plates of a voltaic battery, or the electrodes in an electrolytic cell, by the deposition upon them of the gases liberated by the action of the current. It is chiefly due to the hydrogen, and results in an increase of the resistance, and the setting up of an opposing electromotive force, both of which tend materially to weaken the current of the battery, or that passing through the cell. Origin: Cf. F. Polarization. Source: Websters Dictionary (01 Mar 1998) |
| polarization colours | <microscopy> Interference colours produced by anisotropic substances placed between two polarizing elements and examined by transmitted white light. See: Michel-Levy scale of retardation colours. (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) |
| fluorescence polarization | Measurement of the polarization of fluorescent light from solutions or microscopic specimens. It is used to provide information concerning molecular size, shape, and conformation, molecular anisotropy, electronic energy transfer, molecular interaction, including dye and coenzyme binding, and the antigen-antibody reaction. (12 Dec 1998) |
| fluorescence polarization immunoassay | Fluoroimmunoassay where detection of the hapten-antibody reaction is based on measurement of the increased polarization of fluorescence-labelled hapten when it is combined with antibody. The assay is very useful for the measurement of small haptenic antigens such as drugs at low concentrations. (12 Dec 1998) |
| adrenaline reversal | The fall in blood pressure produced by epinephrine when given following blockage of alpha-adrenergic receptors by an appropriate drug such as phenoxybenzamine; the vasodilation reflects the ability of epinephrine to activate beta-adrenergic receptors which, in vascular smooth muscle, are inhibitory; in the absence of alpha-receptor blockade, the beta-receptor activation by epinephrine is masked by its predominant action on vascular alpha-receptors, which causes vasoconstriction. Synonym: adrenaline reversal. (05 Mar 2000) |
| relaxant reversal | Use of acetylcholinesterase inhibitors to terminate the action of nondepolarising neuromuscular relaxants. (05 Mar 2000) |
| reversal | 1. The act of reversing; the causing to move or face in an opposite direction, or to stand or lie in an inverted position; as, the reversal of a rotating wheel; the reversal of objects by a convex lens. 2. A change or overthrowing; as, the reversal of a judgment, which amounts to an official declaration that it is false; the reversal of an attainder, or of an outlawry, by which the sentence is rendered void. Origin: From Reverse. Source: Websters Dictionary (01 Mar 1998) |
| reversal learning | Any situation where an animal or human is trained to respond differentially to two stimuli (e.g., approach and avoidance) under reward and punishment conditions and subsequently trained under reversed reward values (i.e., the approach which was previously rewarded is punished and vice versa). (12 Dec 1998) |
| reversal of organs, total | This condition (medically called situs inversus totalis) involves complete transposition (right to left reversal) of the thoracic and abdominal organs. The heart is not in its usual position in the left chest but is on the right. Specifically related to the heart, this is referred to as dextrocardia (literally, right-hearted). And the stomach, which is normally in the left upper abdomen, is on the right. In patients with situs inversus totalis, all of the chest and abdominal organs are reversed and appear in mirror image when examined or visualised by tests such as X-ray filming. Situs inversus totalis has been estimated to occur once in about 6-8,000 births. Situs inversus occurs in a rare abnormal condition that is present at birth (congenital) called kartagener's syndrome. (12 Dec 1998) |
| pressure reversal | Cessation of anaesthesia by hyperbaric pressure; of major importance in understanding the mode of action of anaesthetics. (05 Mar 2000) |
| sex reversal | A process whereby the sexual identity of an individual is changed from one sex to the other (e.g., by a combination of surgical, pharmacologic, and psychiatric procedures); it may also occur in the life history of pseudohermaphroditic individuals whose sex at birth was uncertain; initially reared as members of one gender or sex role, such individuals may, upon subsequent medical examination and advice, be reared thereafter as members of the opposite gender or sex role. (05 Mar 2000) |
| sex reversal, gonadal | Change from one sex to another with regard to gonadal development; may be induced or occurs naturally in some invertebrates. (12 Dec 1998) |
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