| gate-control theory | A theory to explain the mechanism of pain; small fibre afferent stimuli, particularly pain, entering the substantia gelatinosa can be modulated by large fibre afferent stimuli and descending spinal pathways so that their transmission to ascending spinal pathways is blocked (gated). Synonym: gate-control hypothesis. (05 Mar 2000) |
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| gate | 1. A way; a path; a road; a street (as in Highgate). "I was going to be an honest man; but the devil has this very day flung first a lawyer, and then a woman, in my gate." (Sir W. Scott) 2. Manner; gait. Origin: Icel. Gata; akin to SW. Gata street, lane, Dan. Gade, Goth. Gatwo, G. Gasse. Cf. Gate a door, Gait. 1. A large door or passageway in the wall of a city, of an inclosed field or place, or of a grand edifice, etc.; also, the movable structure of timber, metal, etc, by which the passage can be closed. 2. An opening for passage in any inclosing wall, fence, or barrier; or the suspended framework which closes or opens a passage. Also, figuratively, a means or way of entrance or of exit. "Knowest thou the way to Dover? Both stile and gate, horse way and footpath." (Shak) "Opening a gate for a long war." (Knolles) 3. A door, valve, or other device, for stopping the passage of water through a dam, lock, pipe, etc. 4. The places which command the entrances or access; hence, place of vantage; power; might. "The gates of hell shall not prevail against it." (Matt. Xvi. 18) 5. In a lock tumbler, the opening for the stump of the bolt to pass through or into. 6. The channel or opening through which metal is poured into the mold; the ingate. The waste piece of metal cast in the opening; a sprue or sullage piece. Alternative forms: geat and git] Gate chamber, a recess in the side wall of a canal lock, which receives the opened gate. Gate channel. See Gate. Gate hook, the hook-formed piece of a gate hinge. Gate money, entrance money for admission to an inclosure. Gate tender, one in charge of a gate, as at a railroad crossing. Gate valva, a stop valve for a pipe, having a sliding gate which affords a straight passageway when open. <anatomy> Gate vein, to enter a college inclosure after the hour to which a student has been restricted. To stand in the gate, or gates, to occupy places or advantage, power, or defense. Origin: OE. Et, eat, giat, gate, door, AS. Geat, gat, gate, door; akin to OS, D, & Icel. Gat opening, hole, and perh. To E. Gate a way, gait, and get, v. Cf. Gate a way in the wall, 3d Get. Source: Websters Dictionary (01 Mar 1998) |
| gate-control hypothesis | A theory to explain the mechanism of pain; small fibre afferent stimuli, particularly pain, entering the substantia gelatinosa can be modulated by large fibre afferent stimuli and descending spinal pathways so that their transmission to ascending spinal pathways is blocked (gated). Synonym: gate-control hypothesis. (05 Mar 2000) |
| flap gate | <ecology, equipment> A device which allows water to flow in only one direction through a culvert, can be used to allow water to drain out of a wetland during low tide while preventing water from entering the wetland during high tide. (09 Oct 1997) |
| Abbe theory of image formation | <optics, physics> Abbe's theory is based on the fact that a non-self-luminous particle, which is illuminated by an extraneous source, gives rise to diffracted light rays, in addition to the dioptric pencil. He stated that to form a good microscopical image as many of the diffracted rays as possible should be intercepted by the objective. With closely ruled lines, his theory is easily demonstrated by observing the back lens of the objective, for here the diffracted rays can be observed directly if the aperture diaphragm is closed. It can be shown that, when the illumination is arranged to exclude the diffracted images, resolution is lost. (11 Mar 1998) |
| adsorption theory of narcosis | That a drug becomes concentrated at the surface of the cell as a result of adsorption, and thus alters permeability and metabolism. (05 Mar 2000) |
| Altmann's theory | A theory that protoplasm consists of granular particles (called bioblasts) that are clustered and enclosed in indifferent matter. (05 Mar 2000) |
| Arrhenius-Madsen theory | That the reaction of an antigen with its antibody is a reversible reaction, the equilibrium being determined according to the law of mass action by the concentrations of the reacting substances. (05 Mar 2000) |
| atomic theory | That chemical compounds are formed by the union of atoms in certain definite proportions; in its modern form, first advanced in 1803 by John Dalton. (05 Mar 2000) |
| Baeyer's theory | That carbon bonds are set at fixed angles (109 |
| balance theory | In social psychology, a theory which assumes that steady and unsteady states can be specified for cognitive units, such as an individual and his or her attitudes or acts, and that such units tend to seek steady states (balance); e.g., balance exists when both parts of a unit are evaluated the same, but disequilibrium arises when both parts are not evaluated the same, which causes either cognitive reevaluation of the parts or their segregation. See: cognitive dissonance theory, consistency principle. (05 Mar 2000) |
| beta-oxidation-condensation theory | <biochemistry> That the two carbon fragments split from the fatty acid molecule by beta-oxidation are converted to acetic acid and then condensed to acetoacetic acid. (05 Mar 2000) |
| Bohr's theory | That spectrum lines are produced 1) by the quantised emission of radiant energy when electrons drop from an orbit of a higher to one of a lower energy level, or 2) by absorption of radiation when an electron rises from a lower to a higher energy level. (05 Mar 2000) |
| Bordeau theory | That each organ of the body manufactured a specific humor which it secreted into the bloodstream. (05 Mar 2000) |
| Bowman's theory | That the urine is formed by passive filtration through the glomeruli and secretion by the epithelium of the tubules, the water and salts being separated from the plasma in the former situation, the urea and other urinary constituents in the latter. Parts of this theory are now known to be wrong. (05 Mar 2000) |