| coefficient of inbreeding | A statistical way of gauging how close two people are as to the genes. The coefficient of inbreeding (symbolised as F) is the probability that a person with two identical genes received both genes from an identical ancestor. Take first cousins who by definition share a set of grandparents. So for any particular allele (gene) in the father, the chance that the mother inherited the same allele from the same source is 1/8. Further, for any gene the father passes to his child, the chance is 1/8 that the mother has the same gene and 1/2 that she transmits that gene to the child so 1/8 X 1/2 = 1/16. Thus, a first-cousin marriage has a coefficient of inbreeding F =1/16. The added risks to the offspring of first cousins depend not only upon this coefficient of inbreeding but also upon the genetic family history and, in some cases, upon test results (for example, for beta thalassaemia for first cousins of Italian descent). However, there are always added risks from the mating of closely related persons and those risks are not negligible. (12 Dec 1998) |
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| coefficient of kinship | The probability that two genes at the same locus, picked at random from each of two individuals, are identical by descent. (05 Mar 2000) |
| coefficient of relationship | The probability that a gene present in one mate is also present in the other and is derived from the same source. (05 Mar 2000) |
| coefficient of variation | The ratio of the standard deviation to the mean. (05 Mar 2000) |
| coefficient of viscosity | The value of the force per unit area required to maintain a unit relative velocity between two parallel planes a unit distance apart. (05 Mar 2000) |
| Wright's inbreeding coefficient | <genetics> The percentage of homozygous alleles an individual has. The probability that any two genes in an individual have the same ancestral origin (which is shared by both parents). (09 Oct 1997) |
| Poiseuille's viscosity coefficient | An expression of the viscosity as determined by the capillary tube method; the coefficient η = (πPr4t/8vl), where P is the pressure difference between the inlet and outlet of the tube, r the radius of the tube, l its length, and v the volume of liquid delivered in the time t. If volume is in cm3, time is in seconds, and l and r are in cm, then n will be in poise. (05 Mar 2000) |
| correlation coefficient | A measure of association that indicates the degree to which two variables have a linear relationship; this coefficient, represented by the letter r, can vary between +1 and -1; when r = +1, there is a perfect positive linear relationship in which one variable relates directly with the other; when r = -1, there is a perfect negative linear relationship between the variables. (05 Mar 2000) |
| population diffusion coefficient | <cell biology> Coefficient that describes the tendency of a population of motile cells to diffuse through the environment. Its use presupposes that the cells move in a random walk. (18 Nov 1997) |
| creatinine coefficient | The number of milligrams of creatinine excreted daily per kilogram of body weight. (05 Mar 2000) |
| Hill coefficient | A measure of cooperativity in a binding process. A Hill coefficient of 1 indicates independent binding, a value of greater than 1 shows positive cooperativity binding of one ligand facilitates binding of subsequent ligands at other sites on the multimeric receptor complex. Worked out originally for the binding of oxygen to haemoglobin (Hill coefficient of 2.8). (18 Nov 1997) |
| sedimentation coefficient | <physics> The ratio of the velocity of sedimentation of a molecule to the centrifugal force required to produce this sedimentation. It is a constant for a particular species of molecule and the value is given in Svedberg units that, it should be noted, are nonadditive. (18 Nov 1997) |
| 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) |
| hygienic laboratory coefficient | A figure expressing the disinfecting power of any substance; it is obtained by dividing the figure indicating the degree of dilution of the disinfectant that kills a microorganism in a given time by that indicating the degree of dilution of phenol which kills the organism in the same space of time under similar conditions. Synonym: hygienic laboratory coefficient, phenol coefficient. (05 Mar 2000) |
| diffusion coefficient | For the translational diffusion of solutes, diffusion is described by Fick's First Law, that states that the amount of a substance crossing a given area is proportional to the spatial gradient of concentration and the diffusion constant (D), that is related to molecular size and shape. A useful derived relationship is that the mean square distance moved by molecules in time t is 6Dt. (18 Nov 1997) |