| thermal sense | The ability to distinguish differences of temperature. Synonym: temperature sense, thermal sense, thermic sense, thermesthesia. Origin: thermo-+ G. Aisthesis, sensation (05 Mar 2000) |
|---|---|
| thermal sensors | Sensors that detect tiny changes in heat or temperature. (14 Nov 1997) |
| thermal spectrum | The part of the invisible spectrum of wave length just longer than that of visible red light. Synonym: thermal spectrum. (05 Mar 2000) |
| thermal velocity | <radiobiology> Average speed (magnitude of velocity) of a particle at a given temperature (in a Maxwellian velocity distribution). (09 Oct 1997) |
| ambipolar diffusion | <radiobiology> Diffusion process in which buildup of spatial charge creates electric fields which cause electrons and ions to leave the plasma at the same rate. (Such electric fields are self-generated by the plasma and act to preserve charge neutrality.) (09 Oct 1997) |
| anomalous diffusion | <radiobiology> Diffusion in most plasma devices, particularly tokamaks, is higher than what one would predict from understood causes. The observed, typical diffusion is referred to as anomalous because it has not yet been explained. Anomalous diffusion includes all diffusion which is not due to collisions and geometric effects. While such effects were not understood when the term was coined, and most still are not, diffusion due to well-understood wave phenomena is still 'anomalous'. Classical diffusion and Neo-classical diffusion are the two well-understood diffusion theories, although neither is adequate to fully explain the observed anomalous diffusion. See: entries for classical diffusion and neoclassical diffusion. Anomalous resistivity (09 Oct 1997) |
| bohm diffusion | <radiobiology> A rapid loss of plasma across magnetic field lines caused by microinstabilities. Theory formulated by the physicist David Bohm. Semiempirical formula for the diffusion coefficient given by Bohm in 1946 (noted by Bohm, Burhop, and Massey, who were developing a magnetic arc for use in uranium isotope separation). Bohm diffusion was proposed (not derived from first principles) to scale as 1/B rather than the 1/B^2 scaling predicted by classical diffusion. A 1/B scaling results from assuming that particles diffuse across field lines at an optimum rate (effective collision frequency=cyclotron frequency). The 1/B scaling is observed (approximately) in most reactors. See: diffusion, microinstabilities, field lines. (09 Oct 1997) |
| gel diffusion | Diffusion in a gel, as in the case of gel diffusion precipitin tests in which the immune reactants diffuse in agar. See: immunodiffusion. (05 Mar 2000) |
| gel diffusion precipitin tests | Precipitin test's in which the immune precipitate forms in a gel medium (usually agar) into which one or both reactants have diffused; generally classified in two types, in one dimension, and in two dimensions. Synonym: gel diffusion reactions. (05 Mar 2000) |
| gel diffusion precipitin tests in one dimension | Precipitin test's in which antigen solution and antibody incorporated in agar are layered in tubes, permitting effective diffusion in the vertical dimension; the antibody-containing agar may be overlaid directly with antigen solution (single (gel) diffusion in one dimension). (05 Mar 2000) |
| gel diffusion precipitin tests in two dimensions | Precipitin test's made in a layer of agar that permits radial diffusion, in both of the horizontal dimensions, of one or both reactants. Double (gel) diffusion in two dimensions (Ouchterlony test, technique, or method) incorporates antigen and antibody solutions placed in separate wells in a sheet of plain agar, permitting radial diffusion of both reactants; this method is widely used to determine antigenic relationships; the bands of precipitate that form where the reactants meet in optimal concentration are of three patterns, referred to as reaction of identity, reaction of partial identity (cross-reaction), and reaction of nonidentity. (05 Mar 2000) |
| gel diffusion reactions | Precipitin test's in which the immune precipitate forms in a gel medium (usually agar) into which one or both reactants have diffused; generally classified in two types, in one dimension, and in two dimensions. Synonym: gel diffusion reactions. (05 Mar 2000) |
| passive diffusion | See: facilitated transport. (05 Mar 2000) |
| classical diffusion | <radiobiology> In plasma physics, diffusion due solely to scattering (collisions) of charged particles (with unlike charges) via electrical (Coulomb) interactions. (See also diffusion.) (09 Oct 1997) |
| population diffusion coefficient | <cell biology> Coefficient that describes the tendency of a population of motile cells to diffuse through the environment. Its use presupposes that the cells move in a random walk. (18 Nov 1997) |