| E(X) | expected value of the random variable X |
|---|---|
| MRF | Markov random field; medical record file; melanocyte-[stimulating hormone]-releasing factor; mesence... |
| RAM | random-access memory; rapid alternating movements; rectus abdominis muscle; rectus abdominis myocuta... |
| RBS | random blood sugar; Roberts syndrome; Rutherford backscattering |
| RDB | random double-blind [trial] |
| sexual selection | A form of natural selection in which, according to Darwin's theory, the male or female is attracted by certain characteristics, form, colour, behaviour, etc., in the opposite sex; thus modifications of a special nature are brought about in the species. (05 Mar 2000) |
|---|---|
| natural selection | The hypothesis that genotype environment interactions occurring at the phenotypic level lead to differential reproductive success of individuals and hence to modification of the gene pool of a population. (18 Nov 1997) |
| insurance selection bias | Adverse of favourable selection bias exhibited by insurers or enrollees resulting in disproportionate enrollment of certain groups of people. (12 Dec 1998) |
| k selection | <zoology> In evolution, the selection of traits that aid an organisms competitive capability when the population is at or near its carrying capacity. (21 Mar 1998) |
| random | 1. Force; violence. "For courageously the two kings newly fought with great random and force." (E. Hall) 2. A roving motion; course without definite direction; want of direction, rule, or method; hazard; chance; commonly used in the phrase at random, that is, without a settled point of direction; at hazard. "Counsels, when they fly At random, sometimes hit most happily." (Herrick) "O, many a shaft, at random sent, Finds mark the archer little meant !" (Sir W. Scott) 3. Distance to which a missile is cast; range; reach; as, the random of a rifle ball. 4. <chemical> The direction of a rake-vein. Origin: OE. Randon, OF. Randon force, violence, rapidity, a randon, de randon, violently, suddenly, rapidly, prob. Of German origin; cf. G. Rand edge, border, OHG. Rant shield, edge of a shield, akin to E. Rand, n. See Rand. Going at random or by chance; done or made at hazard, or without settled direction, aim, or purpose; hazarded without previous calculation; left to chance; haphazard; as, a random guess. "Some random truths he can impart." (Wordsworth) "So sharp a spur to the lazy, and so strong a bridle to the random." (H. <medicine> Spencer) Random courses, stonework consisting of stones of unequal sizes fitted together, but not in courses nor always with flat beds. Source: Websters Dictionary (01 Mar 1998) |
| random allocation | A process involving chance used in therapeutic trials or other research endeavor for allocating experimental subjects, human or animal, between treatment and control groups, or among treatment groups. It may also apply to experiments on inanimate objects. (12 Dec 1998) |
| random amplification of polymorphic DNA | <molecular biology> A term originally invented by polymer chemists to describe a disordered tangle of a linear polymer chain with curved sections. In DNA parlance the random coil refers to the structure that results from melting or other forms of separation of the double helix, i.e. Helix coil transition. (18 Nov 1997) |
| random amplified polymorphic DNA technique | Technique that utilises low-stringency polymerase chain reaction (pcr) amplification with single primers of arbitrary sequence to generate strain-specific arrays of anonymous DNA fragments. Rapd technique may be used to determine taxonomic identity, assess kinship relationships, analyze mixed genome samples, and create specific probes. (12 Dec 1998) |
| random coil | A structure of a macromolecule (typically, a biopolymer) which changes with time. (05 Mar 2000) |
| random mating | Totally haphazard mating with no regard to the genetic makeup (genotype) of the mate so that any sperm has an equal chance of fertilizing any egg. This rarely, if ever, occurs but the concept is impoortant in population genetics. Also called panmixus. (12 Dec 1998) |
| random mating equilibrium | <genetics> In a population containing the genotypes of AA, aa, and Aa, the frequency of AA will be p2, the frequency of aa will be q2, and the frequency of Aa will be 2 pq at equilibrium, where p is the frequency of A and q is the frequency of a. By the Hardy-Weinberg law, a ramdonly-mating population will eventually reach these frequencies and be at this equilibrium as long as there are no selection pressures on the population. (09 Oct 1997) |
| random mechanism | A scheme for substrate binding and product release for a multisubstrate enzyme; for a two-substrate two-product enzyme with this mechanism, either substrate can bind first and, after the reaction has taken place, either product can be the first to dissociate from the enzyme. Brain hexokinase has a random mechanism. More complex random mechanisms exist for enzymes having more than two substrates. (05 Mar 2000) |
| random pattern flap | A flap in which the pedicle blood supply is derived randomly from the network of vessels in the area, rather than from a single longitudinal artery as in an axial pattern flap. (05 Mar 2000) |
| random sample | A group selected randomly, solely by chance. (12 Dec 1998) |
| random sampling | A selection of elements by a formal randomizing device for purposes of inference about a population of inference from that population in such a way that the probability of each possible outcome may be precisely specified in advance; the inferences are necessarily stochastic. (05 Mar 2000) |