| field of fixation | In ophthalmology, the angular distance around which the line of fixation can be turned. (05 Mar 2000) |
|---|---|
| field of view | <microscopy> The extent of the visible image field that can be seen. (05 Aug 1998) |
| field planes | <microscopy> The set of planes in a microscope adjusted for Kohler illumination that are conjugate with the focused specimen. They include the plane of the specimen, the field diaphragm, the intermediate image plane, and the image on the retina, photographic emulsion, or the faceplate of the video pickup device. (05 Aug 1998) |
| field-reversed configuration | <radiobiology> A compact torus produced in a theta pinch and having (in principle) no toroidal field. The potential advantages for a fusion reactor include a simple (linear) machine geometry, an average plasma pressure close to the confining field pressure, and physical separation of formation and burn chambers. The are predicted to be violently unstable to tilting, but this is rarely observed. (09 Oct 1997) |
| field shaping coils | <radiobiology> Type of poloidal field coils (in a tokamak) which create magnetic fields which shape and control the plasma. Used to constrain horizontal and vertical displacements of the plasma, as well as (in some configurations) produce non-circular plasma cross-sections (poloidal cross-section) and/or create one or more divertor separatrices. (09 Oct 1997) |
| Field's rapid stain | <technique> A stain to permit rapid positive diagnosis of malaria in endemic areas by using thick films; it employs methylene blue and azure B in a phosphate buffer, with the preparation counterstained by eosin in a phosphate buffer. (05 Mar 2000) |
| field survey | The planned collection of data among noninstitutionalised persons in the general population. (05 Mar 2000) |
| field-vole | A species of field mouse (Microtus montebelloi), normal host of Leptospira hebdomadis, the cause of a type of leptospirosis resembling infectious mononucleosis. (05 Mar 2000) |
| free field | A field (three-dimensional space) in a homogeneous, isotropic medium free from boundaries; in practice, a field in which boundary effects are negligible. (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) |