shimming
| hyperchromic effect | An increase in absorptivity (or extinction) at a particular wavelength of light by a solution or substance due to structural changes in a molecule. (05 Mar 2000) |
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| sigma 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) |
| hypochromic effect | A phenomenon in which an individual molecule, containing several chromophores, has a certain absorptivity (or optical density) at a given wavelength that is less than the sum of the optical densities of the individual chromophores (at that same wavelength). (05 Mar 2000) |
| Somogyi effect | In diabetes, a rebound phenomenon of reactive hyperglycaemia in response to a preceding period of relative hypoglycaemia that has increased secretion of hyperglycaemic agents (epinephrine, norepinephrine, glucagon, cortisol, and growth hormone); described in diabetic patients given too much insulin who developed unrecognised nocturnal hypoglycaemia that made them hyperglycaemic (suggesting insufficient insulin) when tested the next morning. (05 Mar 2000) |
| stark effect | <radiobiology> The effect an electric field has on the spectral lines emitted from excited atoms. The effect may arise from externally-applied electric fields, from internal fields due to the presence of neighboring ions or atoms (pressure), or from the electric field associated with the Lorentz (v cross B) force (motional stark effect). Spectroscopic measurements of plasmas using the pressure-based and motional Stark effects are useful for diagnostic purposes. (09 Oct 1997) |
| Staub-Traugott effect | In normal persons, a drop in blood glucose which follows a second oral dose of glucose given 30 minutes or so after the first. (05 Mar 2000) |
| Stiles-Crawford effect | Light that enters through the centre of the pupil produces a greater visual effect than light that enters obliquely. (05 Mar 2000) |
| no-observed-adverse-effect level | The highest dosage administered that does not produce toxic effects. The noael will depend on how closely dosages are spaced (lowest-observed-adverse-effect level and no-observed-effect level) and the number of animals examined. The ultimate objective is usually to determine not the "safe" dosage in laboratory animals but the "safe" dosage for humans. Therefore, the extrapolation most often required of toxicologists is from high-dosage studies in laboratory animals to low doses in humans. (casarett and doull's toxicology: the basic science of poisons, 4th ed) (12 Dec 1998) |
| nuclear Overhauser effect | <enzyme> An enzyme seen in nuclear magnetic resonance in which there is a through-space nearest neighbor interaction. (05 Mar 2000) |
| synergistic effect | The doctrine or theory, attributed to Melanchthon, that in the regeneration of a human soul there is a cooperation, or joint agency, on the part both of God and of man. See: Synergetic. Source: Websters Dictionary (01 Mar 1998) |
| doppler effect | <radiobiology> Variation in the frequency of a wave (as measured by an observer) due to relative motion between the observer and the source of the wave. (The observed frequency increases if the source is moving towards the observer and vice versa.) The equation can be found in most optics texts and many introductory physics texts. (09 Oct 1997) |
| dosage effect | The alteration of a phenotype by an increased dosage, or amount, of the product of the gene. (09 Oct 1997) |
| dose-effect curve | This is a graph drawn to show the relationship between the dose of a drug or other chemical and the magnitude of the graded effect that it produces. (09 Oct 1997) |
| 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) |
| oxygen effect | Enhancement of radiosensitivity of cells in a high concentration of oxygen. (05 Mar 2000) |