| quasilinear theory | <physics> A weakly nonlinear theory of plasma oscillations which uses perturbation theory and the random phase approximation to find the time-evolution of the plasma state. (09 Oct 1997) |
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| information theory | An interdisciplinary study dealing with the transmission of messages or signals, or the communication of information. Information theory does not directly deal with meaning or content, but with physical representations that have meaning or content. It overlaps considerably with communication theory and cybernetics. (12 Dec 1998) |
| instructive theory | Theory of antibody production, now considered untenable, in which antigen acted as template for the production of specific antibody as opposed to the clonal selection theory in which pre existing variation occurs and appropriate clones are selectively expanded. (18 Nov 1997) |
| Ollier's theory | A theory of compensatory growth; after resection of the articular extremity of a bone, the articular cartilage of the other bone entering into the structure of the joint takes on an increased growth. (05 Mar 2000) |
| omega-oxidation theory | That the oxidation of fatty acids commences at the CH3 group, i.e., the terminal or omega-group; beta-oxidation then proceeds at both ends of the fatty acid chain. (05 Mar 2000) |
| overproduction theory | The loss or destruction of a part or element in the organic world is likely to result in compensatory replacement and overproduction of tissue during the process of regeneration or repair (or both), as in the formation of callus when a fractured bone heals. Synonym: overproduction theory. (05 Mar 2000) |
| oxygen deprivation theory of narcosis | That narcotics inhibit oxidation, which causes the cell to be narcotised. (05 Mar 2000) |
| telephone theory | A theory of pitch perception which states that the cochlea possesses no faculty of sound analysis, but that the frequency of the impulses transmitted over the auditory nerve fibres corresponds to the frequency of the sound vibrations, and is the sole basis for pitch discrimination; a theory no longer tenable. (05 Mar 2000) |
| theory | In science, an explanation for some phenomenon which is based on observation, experimentation, and reasoning. In popular use, a theory is often assumed to imply mere speculation, but in science, something is not called a theory until it has been confirmed over the course of many independent experiments. Theories are more certain than hypotheses, but less certain than laws. (09 Oct 1997) |
| theory of electrolytic dissociation | The theory of electrolytic dissociation (1887) that became the basis of our modern understanding of electrolytes: in an electrically conductive solution (e.g., acid, base, or salt), free ions are present before electrolysis, and the proportion of molecules dissociated into ions can be calculated from measurements of electrical conductivity as well as of osmotic pressure. Synonym: Arrhenius law. (05 Mar 2000) |
| theory of medicine | The science, as distinguished from the art, or practice, of medicine. (05 Mar 2000) |
| thermodynamic theory of narcosis | That the interposition of narcotic molecules in nonaqueous cellular phase causes changes that interfere with facilitation of ionic exchange. (05 Mar 2000) |
| Ehrlich's theory | Ehrlich postulated that cells contained surface extensions or side chains (haptophores) that bind to the antigenic determinants of a toxin (toxophores); after a cell is stimulated, the haptophores are released into the circulation and become the antibodies. See: receptor. Synonym: Ehrlich's postulate. (05 Mar 2000) |
| emergency theory | A theory of the emotions, advanced by W.B. Cannon, that animal and human organisms respond to emergency situations by increased sympathetic nervous system activity including an increased catecholamine production with associated increases in blood pressure, heart and respiratory rates, and skeletal muscle blood flow. See: relaxation response. Synonym: Cannon's theory. (05 Mar 2000) |
| emigration theory | That neoplasms originate from various cell rests, i.e., embryonal cells thought to persist in various sites after the development of the foetal organs and tissues. Synonym: emigration theory. (05 Mar 2000) |