| DAF | decay-accelerating factor; delayed auditory feedback; drug-adulterated food |
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| DAS | dead air space; Death Anxiety Scale; delayed anovulatory syndrome; dextroamphetamine sulfate; digita... |
| DAT | delayed-action tablet; dementia Alzheimer's type; dental aptitude test; diacetylthiamine; diet as to... |
| DCH | delayed cutaneous hypersensitivity; Diploma in Child Health |
| DCN | data collection network; deep cerebral nucleus; delayed conditioned necrosis; depressed, cognitively... |
| delayed reaction experiment | A method of measuring memory: a stimulus is presented and removed before the organism is permitted to respond to it; the interval during which the stimulus is absent, providing the organism responds correctly, is an indication of the length of memory. (05 Mar 2000) |
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| delayed rectifier channel | <physiology> The potassium selective ion channels of axons, so called because they change the potassium conductance with a delay after a voltage step. The name is used to denote any axon like K channel. Various roles for example regulation of pacemaker potentials, generation of bursts of action potentials or generation of long plateaus on action potentials. (18 Nov 1997) |
| delayed reflex | A reflex in which a little time elapses between stimulus and response. See: trace conditioned reflex. (05 Mar 2000) |
| delayed sensation | A sensation that is not perceived until the lapse of an appreciable interval following the application of the stimulus. General sensation, a sensation referred to the body as a whole rather than to any particular part. (05 Mar 2000) |
| delayed suture | A suturing of a wound after an interval of days. (05 Mar 2000) |
| delayed type hypersensitivity | <immunology> Hypersensitivity (increased reaction by the body to a foreign substance such as an antigen or allergen) that does not appear until 24 to 48 hours after the body is exposed to the foreign substance. (09 Oct 1997) |
| ovum implantation, delayed | Delay of embryonal development whereby the blastocyst remains in the uterine cavity for a variable period of time before attaching to the endometrium and continuing its development. (12 Dec 1998) |
| Abbe theory of image formation | <optics, physics> Abbe's theory is based on the fact that a non-self-luminous particle, which is illuminated by an extraneous source, gives rise to diffracted light rays, in addition to the dioptric pencil. He stated that to form a good microscopical image as many of the diffracted rays as possible should be intercepted by the objective. With closely ruled lines, his theory is easily demonstrated by observing the back lens of the objective, for here the diffracted rays can be observed directly if the aperture diaphragm is closed. It can be shown that, when the illumination is arranged to exclude the diffracted images, resolution is lost. (11 Mar 1998) |
| accidental image | Continuation of visual impression after cessation of stimuli causing the original image. (12 Dec 1998) |
| body image | A term for the concept which each individual has of his own body as an object in and bound by space, independently and apart from all other objects. (12 Dec 1998) |
| radiographic image enhancement | Improvement in the quality of an X-ray image by use of an intensifying screen, tube, or filter and by optimum exposure techniques. Digital processing methods are often employed. (12 Dec 1998) |
| radiographic image interpretation, computer-assisted | Computer systems or networks designed to provide radiographic interpretive information. (12 Dec 1998) |
| real image | An image formed by the convergence of the actual rays of light from an object. Synonym: inverted image. (05 Mar 2000) |
| catatropic image | <ophthalmology, physiology> The two images formed by the anterior and posterior surfaces of the cornea and the two images formed by the anterior and posterior surfaces of the lens. Synonym: catatropic image, Purkinje images, Sanson's images. (05 Mar 2000) |
| virtual image | <microscopy> Such as seen in a mirror or through a magnifier. A virtual image has no real existence in space as does a real image from a lens. It does have a definite location, however, caused by the angles of divergence of the rays received by the eye. This can be shown by the common school experiment of placing a pin coincident with its mirror image behind a sheet of glass acting as a partial mirror. Its location can also be placed in design by extrapolating backwards to a focus. If a magnifier is used as it should be, with the object at its focus, the virtual image is at infinity. The same is true for a microscope focused for the relaxed eye. See: distance of virtual image. (05 Aug 1998) |