| absolute viscosity | Force per unit area applied tangentially to a fluid, causing unit rate of displacement of parallel planes separated by a unit distance; units in CGS system: poise. (05 Mar 2000) |
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| absolute zero | <chemistry, physics> This is the lowest possible temperature (0 Kelvin, -273.15 degrees Celsius, -459.67 degrees Fahrenheit). at this temperature, all molecular motion stops. (15 Jan 1998) |
| atmosphere absolute | <physics> A unit of absolute pressure (also known as barometric pressure) expressed in atm. (05 Mar 2000) |
| CD4 count, absolute | The number of helper T-lymphocytes in a cubic millimeter of blood. With HIV, the absolute CD4 count declines as the infection progresses. The absolute CD4 count is frequently used to monitor the extent of immune suppression in persons with HIV. Also called a T4 count. (12 Dec 1998) |
| accommodative convergence-accommodation ratio | The amount of convergence (measured in prism diopters of convergence) divided by the amount of accommodation (measured in diopters) required to direct both eyes upon an object. (05 Mar 2000) |
| A/G ratio | <abbreviation> Albumin-globulin ratio. (05 Mar 2000) |
| albumin-globulin ratio | The ratio of albumin to globulin in the serum or in the urine in kidney disease; the normal ratio in the serum is approximately 1.55. (05 Mar 2000) |
| ALT:AST ratio | The ratio of serum alanine aminotransferase to serum aspartate aminotransferase; elevated serum levels of both enzymes characterise hepatic disease; when both levels are abnormally elevated and the ALT:AST ratio is greater than 1.0, severe hepatic necrosis or alcoholic hepatic disease is likely; when the ratio is less than 1.0, an acute non-alcoholic hepatic condition is favoured. (05 Mar 2000) |
| amylase-creatinine clearance ratio | A test for the diagnosis of acute pancreatitis; it is determined by measuring amylase and creatinine in serum and urine in apparently healthy individuals the renal clearance of amylase is less than 5% that of creatinine; in acute pancreatitis the ratio is said to be greater than 0.05 or 5%. (05 Mar 2000) |
| aspect ratio | <radiobiology> In toroidal geometry, the ratio of the major diameter (total width of the torus) to the minor diameter (width of a slice taken through one side of the ring). In inertial-confinement fusion, aspect ratio refers to the ratio of a fuel pellet's radius to its wall thickness. (09 Oct 1997) |
| at/gc ratio | <molecular biology> The ratio of adenine-thymine base pairs to guanine-cytosine base pairs on a DNA molecule. (09 Oct 1997) |
| basic reproductive rate, ratio | <epidemiology> See Reproductive Ratio. (05 Dec 1998) |
| body-weight ratio | Body weight (in grams) divided by stature (in centimeters). (05 Mar 2000) |
| branching ratio | <radiobiology> In a fusion reaction involving two nuclei, there are typically a variety of possible sets of products which can form. The branching ratio for a particular set of products is the probability that that set of products will be produced. (09 Oct 1997) |
| cardiothoracic ratio | The ratio of the horizontal diameter of the heart to the inner diameter of the rib cage at its widest point as determined on a chest roentgenogram. (05 Mar 2000) |