| selection (genetics) | Differential and non-random reproduction of different genotypes, operating to alter the gene frequencies within a population. (12 Dec 1998) |
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| selection bias | The introduction of error due to systematic differences in the characteristics between those selected and those not selected for a given study. In sampling bias, error is the result of failure to ensure that all members of the reference population have a known chance of selection in the sample. (12 Dec 1998) |
| selection coefficient | The proportion of progeny or potential progeny not surviving to sexual maturity; usually defined artificially by expressing the fitness of a phenotype as a fraction of the mean or optimal fitness to give the relative fitness, and subtracting this fraction from unity. If the mean size of family in the population is 3.2 and that for a particular genotype is 2.4 then the fitness of the phenotype is 2.4/3.2 =0.75 and the selection coefficient =1-0.75 =.25 = 5 (05 Mar 2000) |
| selection cutting | The periodic removal at short intervals of the oldest and largest trees in the stand, individually or in small groups. (05 Dec 1998) |
| selection pressure | Impact of effective reproduction due to environmental impact on the phenotype. (05 Mar 2000) |
| selective angiography | <procedure, radiology> Angiography in which visualization is improved by concentrating the contrast medium in the region to be studied by injection through a catheter positioned in a regional artery. (05 Mar 2000) |
| selective grinding | <dentistry> The modification of the occlusal forms of teeth by grinding according to a plan or by grinding at selected places marked by articulating ribbon or paper. (05 Mar 2000) |
| selective hypoaldosteronism | <endocrinology> Isolated hypoaldosteronism, aldosterone deficiency without a concomitant deficiency of glucocorticoid hormones. (05 Mar 2000) |
| selective immunoglobulin A deficiency | <immunology> An inherited disorder in which there is a markedly reduced or absent IgA, resulting in immature IgA-bearing B-cells. (05 Mar 2000) |
| selective inhibition | <chemistry> Inhibitor that occupies the active site of an enzyme or the binding site of a receptor and prevents the normal substrate or ligand from binding. at sufficiently high concentration of the normal ligand inhibition is lost: the Km is altered by the competitive inhibitor, but the Vmax remains the same. (05 Jan 1998) |
| selective injection | Injection of contrast medium following selective catheterization of a branch artery or vein for angiography. (05 Mar 2000) |
| selective medium | <cell culture> A medium which allows the growth of certain types of microorganisms in preference to others. For example: an antibiotic-containing medium allows the growth of only those microorganisms which are resistant to this antibiotic. (09 Oct 1997) |
| selective memory | <psychology> Reception or retrieval of only some of the events in an experience. (05 Mar 2000) |
| selective oestrogen-receptor modulator | <pharmacology> An antioestrogen which possesses some, but not all, of the actions of oestrogen. For example, raloxifene (evista) is classified as a SERM because it prevents bone loss (like oestrogen) and lowers serum cholesterol (like oestrogen) but (unlike oestrogen) does not stimulate the endometrial lining of the uterus. Acronym: SERM (17 Jul 2002) |
| selective reduction | <obstetrics> A technique for intrauterine termination of one or more foetuses while leaving one or more foetuses undisturbed, usually in pregnancies with foetal anomalies or with multiple gestations. (05 Mar 2000) |