| GRASS | Gradient Recalled Acquisition at Steady State |
|---|---|
| AAG | 3-alkaladenine deoxyribonucleic acid glycosylase; allergic angiitis and granulomatosis; alpha-1-acid... |
| CGGE | constant gradient gel electrophoresis |
| DGGE | denaturating gradient gel electrophoresis |
| ECPOG | electrochemical potential gradient |
| selection pressure | Impact of effective reproduction due to environmental impact on the phenotype. (05 Mar 2000) |
|---|---|
| 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) |
| atrioventricular gradient | The diastolic pressure difference between the atrium and ventricle. (05 Mar 2000) |
| magnetic field gradient | In magnetic resonance imaging, a magnetic field that varies with location, superimposed on the uniform field of the magnet, to alter the resonant frequency of nuclei and allow recovery of their spatial position. Synonym: field gradient. (05 Mar 2000) |
| ventricular gradient | The algebraic sum of (i.e., the net electrical difference between) the area enclosed within the QRS complex and that within the T wave in the electrocardiogram. (05 Mar 2000) |
| voltage gradient | <physiology> Literally, the electric field in a region, defined as the potential difference between two points divided by the distance between them. Used more loosely, the potential difference across a plasma membrane. (18 Nov 1997) |
| centrifugation, density gradient | Separation of particles according to density by employing a gradient of varying densities. at equilibrium each particle settles in the gradient at a point equal to its density. (12 Dec 1998) |
| cesium chloride gradient centrifugation | A type of density gradient centrifugation, a lab technique used to separate or purify nucleic acids. It involves putting cesium chloride and the nucleic acids into a centrifuge to be spun for hours or days. The cesium chloride forms a density gradient (highly dense at the bottom, thinnest at the top), and the different nucleic acids separate along the gradient according to their buoyancies in different densities. (09 Oct 1997) |
| gradient | <physics> Mathematical term for the operator which determines the magnitude and direction of the greatest rate-of-change of a given function with position. Similarly used to describe such a rate-of-change. For instance, at a given point on a hill, the slope of the hill in the steepest uphill direction is the gradient of the altitude function for the hill. (09 Oct 1997) |
| gradient elution | Elution in column chromatography in which a changing pH or ionic strength is used to separate substances. (05 Mar 2000) |
| gradient encoding | In magnetic resonance imaging, the technique of inducing a gradient in the magnetic field in the Y-axis to induce phase differences with location. Synonym: gradient encoding. (05 Mar 2000) |
| gradient perception | <cell biology> Problem faced by a cell that is to respond directionally to a gradient of, for example: a diffusible attractant chemical. In a spatial mechanism the cell would compare receptor occupancy at different sites on the cell surface, a temporal mechanism would involve comparison of concentrations at different times, the cell moving randomly between readings. In pseudospatial sensing, the cell would detect the gradient as a consequence of positive feedback to protrusive activity if receptor occupancy increased with time as the protrusion moved up gradient. Few cell types have been unambiguously shown to detect gradients. (18 Nov 1997) |