| direct vision | Vision stimulated by an object imaged on the fovea centralis. Synonym: direct vision. (05 Mar 2000) |
|---|---|
| direct vision spectroscope | <instrument> A spectroscope consisting of a single tube containing a series of prisms; one end of the tube is placed in as close contact as possible with the substance to be examined while the observer places his eye at the opposite end; it can be used to make a spectroscopic examination of the blood in vivo, as in the ear lobe or web of the thumb. (05 Mar 2000) |
| direct zoonosis | A zoonosis transmitted between animal and humans from an infected to a susceptible host by contact, by airborne droplets or droplet nuclei, or by some vehicle of transmission; the agent requires a single vertebrate host for completion of its life cycle and does not develop or show significant change during transmission; may include anthropozoonoses (rabies), zooanthroponoses (amoebiasis), and amphixenoses (certain streptococcoses). (05 Mar 2000) |
| fluorescent antibody technique, direct | A form of fluorescent antibody technique utilizing a fluorochrome conjugated to an antibody, which is added directly to a tissue or cell suspension for the detection of a specific antigen. (12 Dec 1998) |
| lateral direct veins | One or more veins running a subependymal course in a coronal plane over the thalamus, terminating in the internal cerebral vein. Synonym: lateral direct veins, surface thalamic veins. (05 Mar 2000) |
| abscopal effect | A reaction produced following irradiation but occurring outside the zone of actual radiation absorption. (05 Mar 2000) |
| additive effect | <biochemistry, chemistry> An additive effect is the overall biological effect two chemicals acting together and which is the simple sum of the effects of the chemicals acting independently. Compare: antagonism. (15 Jan 1998) |
| adverse effect | This is an abnormal or harmful effect to an organism caused by exposure to a chemical. It is indicated by some result such as death, a change in food or water consumption, altered body and organ weights, altered enzyme levels, or visible illness. An effect may be classed as adverse if it causes functional or anatomical damage, causes irreversible change in the homeostasis of the organism, or increases the susceptibility of the organism to other chemical or biological stress. A non-adverse effect will usually be reversed when the organism is no longer being exposed to the chemical. (09 Oct 1997) |
| Anrep effect | A small transient positive inotropic effect of abrupt increases of systolic aortic and left ventricular pressures related to recovery from transient subendocardial ischemia (e.g., cold pressor test). (05 Mar 2000) |
| antagonistic effect | This is the consequence of one chemical (or group of chemicals) counteracting the effects of another chemical, the opposing chemicals cancel out each other's effects. (09 Oct 1997) |
| Arias-Stella effect | Focal, unusual, decidual changes in endometrial epithelium, consisting of intraluminal budding, and nuclear enlargement and hyperchromatism with cytoplasmic swelling and vacuolation; may be associated with ectopic or uterine pregnancy. Synonym: Arias-Stella effect, Arias-Stella reaction. (05 Mar 2000) |
| Auger effect | <physics> Transition of an electron in an atom from a discrete electronic level to an ionised continuous level with the same energy. Synonym: autoionisation. (13 Jan 1998) |
| autokinetic effect | In psychology, the apparent drifting about of a small, fixed, spot of light which is being observed in a dark room. (05 Mar 2000) |
| Bernoulli effect | <physics> The decrease in fluid pressure that occurs in converting potential to kinetic energy when motion of the fluid is accelerated, in accordance with Bernoulli's law. Applied in water aspirators, atomisers, and humidifiers in which a gas is accelerated across the end of a narrow, fluid-filled orifice. (05 Mar 2000) |
| Bohr effect | <physiology> Decrease in oxygen affinity of haemoglobin when pH decreases or concentration of carbon dioxide increases. (18 Nov 1997) |