| field lens | <physics> The lower lens in an ocular, the lens nearest the object field. (05 Aug 1998) |
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| field lines | <radiobiology> Lines in space along which a field is either changing or not changing (depends on the kind of field) but which help to create diagrams which characterise the behaviour and effects of the field. For instance, electric field lines run in the direction that the electric field will push charged particles, the strength of the field is proportional to the density of the field lines. On the other hand, the magnetic force pushes particles in a direction perpendicular to both the particle's velocity and the direction of the magnetic field line. (09 Oct 1997) |
| field of consciousness | The content of awareness at any given moment. (05 Mar 2000) |
| 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) |