| Orbeli effect | The fatigue of a muscle stimulated by its nerve (i.e., indirectly) is reduced by concurrent stimulation of sympathetic fibres to the muscle; thought to be caused by norepinephrine diffusing from adrenergic fibres which innervate blood vessels in the muscle. (05 Mar 2000) |
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| oxygen effect | Enhancement of radiosensitivity of cells in a high concentration of oxygen. (05 Mar 2000) |
| effect | The result produced by an action. (18 Nov 1997) |
| effect, founder | A population group with an unusual frequency of a gene due to there having been only a small number of original members ( founders ) one or more of whom had that gene. For example, the gene for Huntington disease was introduced into the Lake Maracaibo region of Venezuela early in the 19th century, so there are now over a hundred persons with Huntington disease and at least 900 persons at risk for that deadly disease in that region, the largest known aggregation known in the world with the Huntington gene. (12 Dec 1998) |
| effect modifier | A factor that modifies the effect of a putative causal factor under study; e.g., age is an effect modifier for many conditions. (05 Mar 2000) |
| effect modifiers | <epidemiology> Factors that modify the effect of the putative causal factor(s) under study. (12 Dec 1998) |
| electrophonic effect | The sensation of hearing produced when an alternating current of suitable frequency and magnitude is passed from an external source through a person. (05 Mar 2000) |
| toxic effect | <physiology> The physiologic, physical or laboratory manifestations or derangement that can be attributed to the presence of a substance within the body. (12 Jan 1998) |
| enhancement effect | Property of higher plant photosynthesis, discovered by Robert Emerson. The quantum yield of red light (less than 680nm) and far red light (700nm), when shone simultaneously on a plant, is greater than the sum of the yields of the light of the two wavelengths separately. This effect provides evidence for the cooperative interaction of two photosystems in photosynthesis. (18 Nov 1997) |
| tunneling effect | <radiobiology> In quantum mechanics, a particle approaching a potential energy barrier of finite extent has a chance (usually small) of tunneling through the barrier, even though it lacks the energy to go over the barrier. Tunneling plays a strong role in fusion reactions: particles which do not have enough energy to climb over the electrostatic energy barrier (into the region where nuclear attractions dominate) can still fuse by tunneling through. (09 Oct 1997) |
| Tyndall effect | The visibility of floating particles in gases or liquids when illuminated by a ray of sunlight and viewed at right angles to the illuminating ray. Synonym: Tyndall effect. (05 Mar 2000) |
| extrapyramidal effect | A combination of neurologic effects which includes tremors, chorea, athetosis and dystonia. A common side effect of neuroleptic agents (phenothiazines). Other medications known to cause these reactions include haloperidol, molindone, perphenazine & amitriptyline, loxapine, pimozide and rarely, benzodiazepines. (27 Sep 1997) |
| Fahraeus-Lindqvist effect | The decrease in apparent viscosity that occurs when a suspension, such as blood, is made to flow through a tube of smaller diameter; observed in tubes less than about 0.3 mm in diameter. Synonym: sigma effect. (05 Mar 2000) |
| Zeeman effect | The splitting of spectral lines into three or more symmetrically placed lines when the light source is subjected to a magnetic field. (05 Mar 2000) |
| Fenn effect | The increased liberation of heat in a stimulated muscle when it is allowed to do mechanical work; the amount of heat liberated is increased in proportion to the distance the muscle is allowed to shorten and in proportion to the tension it must develop (e.g., the weight it lifts) during shortening; thus increased chemical energy is consumed both to liberate increased heat and to do increased mechanical work. (05 Mar 2000) |