| GRASS | Gradient Recalled Acquisition at Steady State |
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| 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 |
| 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) |
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| mitral gradient | The diastolic pressure difference between the left atrium and left ventricle. (05 Mar 2000) |
| concentration gradient | <chemistry> A column of liquid in which the density varies continually with position, usually as a consequence of variation of concentration of a solute. Such gradients may be established by progressive mixing of solutions of different density as for example: sucrose gradients) or by centrifuge induced redistribution of solute (as for caesium chloride gradients). Density gradients are widely used for centrifugal and gravity induced separations of cells, organelles and macromolecules. The separations may exploit density differences between particles or primarily differences in size, in which latter case the function of the gradient is chiefly to stabilise the liquid column against mixing. (12 Jan 1998) |
| critical gradient | <botany> The maximum stable inclination of an unsupported slope under the most adverse conditions that it will likely experience, as determined by current engineering technology. (09 Oct 1997) |
| pseudospatial gradient sensing | <cell biology> Mechanism for sensing a gradient of a diffusible chemical in which the cell sends protrusions out at random, up gradient protrusions are stabilised by positive feedback (because receptor occupancy is rising with time) and others are transitory because of adaptation. Possibly the mechanism by which neutrophils sense chemotactic gradients. (18 Nov 1997) |
| systolic gradient | The difference in pressure during systole between two communicating cardiovascular chambers, e.g., between the left ventricle and aorta in aortic stenosis. (05 Mar 2000) |
| electrochemical gradient | A measure of the tendency of an ion to move passively from one point to another, taking into consideration the differences in its concentration and in the electrical potentials between the two points; commonly expressed as the additional voltage needed to achieve equilibrium. (05 Mar 2000) |
| ficoll gradient | A density gradient of ficoll (synthetic sucrose polymer) in solution, where concentration of the ficoll varies continuously through the solution. It is often used to separate different types of cells from each other during the process of sedimentation. (09 Oct 1997) |
| 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) |
| bone density | Bone density is the amount of bone tissue in a certain volume of bone. It can be measured using a special X-ray called a quantitative computed tomogram. (12 Dec 1998) |
| bulk density | Weight per unit of volume, usually specified in pounds per cubic foot. (05 Dec 1998) |
| buoyant density | The density that allows a substance to float in some standard fluid. (05 Mar 2000) |
| vapor density | The mass per unit volume of a vapor; since the vapor density changes with temperature and pressure, it is commonly expressed as a specific gravity, i.e., the weight of the vapor divided by the weight of an equal volume of a reference gas (e.g., oxygen or hydrogen) at the same temperature and pressure. (05 Mar 2000) |
| very low density lipoprotein | <biochemistry> A lipoprotein substances (combination of a fat and a protein) which acts as a carrier for cholesterol and fats (particularly triglycerides) in the bloodstream. Elevations in very low density lipoprotein in the bloodstream are associated with an increased risk of atherosclerosis and coronary artery disease. Acronym: VLDL (18 Nov 1997) |
| photon density | The number of counted events recorded in scintigraphy per square centimeter or per square inch of imaged area. Synonym: count density. (05 Mar 2000) |