| CCD | calibration curve data; central core disease; charge-coupled device; childhood celiac disease; cleid... |
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| DCV | distribution of conduction velocities |
| DF | decapacitation factor; decontamination factor; deferoxamine; deficiency factor; defined flora [anima... |
| dist | distal; distill, distillation, distilled; distance; distribution; disturbance, disturbed |
| DR | degeneration reaction; delivery room; deoxyribose; diabetic retinopathy; diagnostic radiology; digit... |
| sex distribution | The number of males and females in a given population. The distribution may refer to how many men or women or what proportion of either in the group. The population is usually patients with a specific disease but the concept is not restricted to humans and is not restricted to medicine. (12 Dec 1998) |
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| skew distribution | An asymmetrical frequency distribution; in biology and medicine it is usually a lognormal distribution. (05 Mar 2000) |
| negative binomial distribution | <epidemiology> A distribution which is parameterised by a mean m and an aggregation parameter k which is large when aggregation is small; in fact as k becomes large, the negative binomial distribution approximates the Poisson distribution. (05 Dec 1998) |
| Nernst equation | <physics> A basic equation of biophysics that describes the relationship between the equilibrium potential difference across a semipermeable membrane and the equilibrium distribution of the ionic permeant species. It is described by: E = (RT/zF).ln[C1/C2 Where E is the potential on side 2 relative to side 1 in volts), R is the gas constant (8.314 J Kexp 1 molexp 1), T is the absolute temperature, z is the charge on the permeant ion, f is the Faraday constant (96500 C molexp 1) and C1 and C2 are the concentrations (more correctly activities) of the ions on sides 1 and 2 of the membrane. It can be seen that this equation is a solution of the more general equation of electrochemical potential, for the special case of equilibrium. The equation described the voltage generated by ion selective electrodes, like the laboratory pH electrode and approximates the behaviour of the resting plasma membrane (see resting potential). (13 Nov 1997) |
| Nernst's equation | The equation relating the equilibrium potential of electrodes to ion concentrations; the equation relating the electrical potential and concentration gradient of an ion across a permeable membrane at equilibrium: E = [RT / nF Origin: Ln (C1/C 2)], where E = potential, R = absolute gas constant, T = absolute temperature, n = valence, F = the Faraday, ln = the natural logarithm, and C1 and C2 are the ion concentrations on the two sides; in nonideal solutions, concentration should be replaced by activity. See: Nernst's theory, activity. (05 Mar 2000) |
| nitrogen distribution | Determination of the distribution of nitrogen in the urine among the various constituents. Synonym: nitrogen distribution. (05 Mar 2000) |
| normal distribution | Continuous frequency distribution of infinite range. Its properties are as follows: 1) continuous, symmetrical distribution with both tails extending to infinity; 2) arithmetic mean, mode, and median identical; and 3) shape completely determined by the mean and standard deviation. (12 Dec 1998) |
| Svedberg equation | See: sedimentation constant. (05 Mar 2000) |
| dermatomal distribution | The area of skin innervated by a single posterior spinal nerve (sensory nerve). (27 Sep 1997) |
| difference equation | <epidemiology> The mathematical formulation corresponding to a discrete time model. (05 Dec 1998) |
| differential equation | <epidemiology> The mathematical formulation corresponding to a continuous model; an equation involving derivatives. (05 Dec 1998) |
| distribution | 1. The specific location or arrangement of continuing or successive objects or events in space or time. 2. The extent of a ramifying structure such as an artery or nerve and its branches. 3. The geographical range of an organism or disease. 4. Probability. Origin: L. Distributio (11 Jan 1998) |
| distribution coefficient | The ratio of concentrations of a substance in two immiscible phases at equilibrium; the basis of many chromatographic separation procedures. Synonym: partition coefficient. (05 Mar 2000) |
| distribution curve | A systematic grouping of data into classes or categories according to the frequency of occurrence of each successive value or ranges of such values, resulting in a graph of a frequency distribution. Synonym: frequency curve. (05 Mar 2000) |
| distribution function | <radiobiology> Function characterising the density of particles located at a given point in phase space (a combination of velocity and/or position coordinates) at a given time. The velocity-space distribution function gives the number of particles with a particular velocity, the position-space distribution function is synonymous with the particle density in position-space. Different combinations of position and spatial coordinates are useful in different problems. (09 Oct 1997) |