| clasp-knife effect | Initial increased resistance to stretch of the extensor muscles of a joint that give way rather suddenly allowing the joint then to be easily flexed; the rigidity is due to an exaggeration of the stretch reflex. See: lengthening reaction. Synonym: clasp-knife effect, clasp-knife rigidity. (05 Mar 2000) |
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| photechic effect | The ability of an agent, other than light, to make a developable latent image in a photographic film emulsion. Synonym: Russell effect. (05 Mar 2000) |
| photoelectric effect | <chemistry, radiobiology> The interaction of a photon with an atom, resulting in the absorption of the incident photon and the release of a bound electron from that atom with energy equal to the photon energy less the electron binding energy. (16 Dec 1997) |
| mirror effect | <physics> A charged particle travelling into an increasing magnetic field will (if the field becomes strong enough) reverse direction and be reflected back. This is a direct result of the adiabatic invariance of the magnetic moment. Plasmas can be confined by devices which utilise this effect. The effect also occurs in some toroidal plasmas, since the toroidal magnetic field is stronger on the inboard side than on the outboard side, in this case it gives rise to so-called neoclassical effects. The strength of the mirror is determined by the mirror ratio. (09 Oct 1997) |
| piezoelectric effect | The property of certain crystalline or ceramic materials to emit electricity when deformed and to deform when an electric current is passed across them, a mechanism of interconverting electrical and acoustic energy; an ultrasound transducer sends and receives acoustic energy using this effect. (05 Mar 2000) |
| cohort effect | Variation in health status arising from different causal factors to which each birth cohort in a population is exposed as environment and society change. (12 Dec 1998) |
| Wedensky effect | A relatively long enhancing effect following application of a maximal shock or stimulus to a neuromuscular preparation during which a subthreshold stimulation, otherwise too small to evoke a response, will produce a response; a relatively prolonged lowered threshold of excitability following a maximal shock. (05 Mar 2000) |
| placebo effect | An effect usually, but not necessarily, beneficial that is attributable to an expectation that the regimen will have an effect, i.e., the effect is due to the power of suggestion. (12 Dec 1998) |
| common ion effect | <chemistry> The influence on an equilibrium by the presence of a substance which contains ions that participate in the equilibrium. (09 Oct 1997) |
| compton effect | <radiobiology> An attenuation process observed for x and gamma radiation in which an incident photon interacts with an orbital electron of an atom to produce a recoil electron and a scattered photon of energy less than the incident photon. (16 Dec 1997) |
| concentration-effect curve | <pharmacology> This is a graph produced to show the relationship between the exposure concentration of a drug or other foreign chemical and the magnitude of the graded effect that it produces. (05 Jan 1998) |
| Wolff-Chaikoff effect | Blocking of the organic binding of iodine and its incorporation into hormone caused by large doses of iodine; usually a transient effect, but in large doses in susceptible individuals it can be prolonged and cause iodine myxoedema. Synonym: Wolff-Chaikoff effect. (05 Mar 2000) |
| Cotton effect | The positive and negative displacement from zero of the rotation of plane polarised monochromatic light and the change of monochromatic circularly polarised light into elliptically polarised light in the immediate vicinity of the absorption band of the substance through which the light passes. See: optical rotatory dispersion, circular dichroism. (05 Mar 2000) |
| Crabtree effect | Inhibition of cellular respiration of isolated systems by high concentrations of glucose; a "reciprocal" of Pasteur's effect; due, in part, to the inhibition of hexokinase by elevated glucose-6-phosphate. Compare: Pasteur's effect. (05 Mar 2000) |
| position effect | A change in the phenotypic expression of one or more genes due to a change in its physical location with respect to other genes; may result from change in chromosome structure or from crossing-over. (05 Mar 2000) |