| LDF | laser Doppler flux, laser Doppler fluxometry; limit dilution factor |
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| NAA | N-acetyl aspartate; naphthaleneacetic acid; neutral amino acid; neutron activation analysis; neutrop... |
| NAF | nafcillin; National Amputation Foundation; National Ataxia Foundation; net acid flux |
| PBNA | partial body neutron activation |
| f | Greek letter phi; magnetic flux; osmotic coefficient |
| flux, light | <microscopy> Sometimes called luminous flux, the visible portion of the radiant energy emitted by a light source. It is measured in lumens per solid angle. In electrical engineering, it is analogous to the lines of force in a magnetic field, spoken of as magnetic flux. (05 Aug 1998) |
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| flux ratio | The ratio of the two unidirectional fluxes through a particular boundary layer or membrane. (05 Mar 2000) |
| luminous flux | The quantity of light emitted from a point source in a given time; its unit is the lumen. (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) |
| 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) |
| 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) |
| count 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) |
| population density | <epidemiology> Number of individuals in a population relative to space. (12 Dec 1998) |
| current density | <radiobiology> Amount of current flowing through a substance, per unit area perpendicular to the direction of current flow. (See also density) (09 Oct 1997) |
| high density lipoprotein | <biochemistry> These lipoproteins acts to carry cholesterol in the bloodstream. Raised high density lipoprotein levels have been correlated with a lower risk for heart disease. Less than 35 mg/dl is considered a positive risk factor for coronary artery disease, over 60 mg/dl is considered a negative risk factor (reduces your risk of heart disease). Recent studies show a low high density lipoprotein level is the strongest predictor of cardiovascular death in women. Acronym: HDL (18 Nov 1997) |
| spin density | The number of nuclear dipoles per unit volume. (05 Mar 2000) |