| time constant | That part of a circuit that determines the time interval over which the rate of electrical events will be averaged; in pulmonary physiology, the factors determining rate of flow in the airways. (05 Mar 2000) |
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| transformation constant | <physics, radiobiology> The fraction of the amount of a radionuclide that undergoes transition per unit time. Formally: Lamda=dP/dt Where dP is the probability of a given nucleus undergoing spontaneous nuclear transition in the time interval dt. (16 Dec 1997) |
| equilibrium constant | <chemistry> The ratio of the reverse and forward rate constants for a reaction of the type: A + B = AB at equilibrium the equilibrium constant (K) equals the product of the concentrations of reactants divided by the concentration of product and has dimensions of concentration. Kd = (concentration A.concentration B) / (concentration AB). The affinity constant (Ka) is the reciprocal of the equilibrium constant. Dimension: moles per litre. In general the concept of Kd is more readily understood than that of Ka, for example: in considering the conversion of A to AB by the binding of ligand B, the Kd = B when A = AB. Thus Kd is equal to the ligand concentration which produces half maximal conversion (response). (10 Jan 1998) |
| universal gas constant | <radiobiology> R = 8.314 x 10^7 ergs per degree C per mole. (09 Oct 1997) |
| flotation constant | Characteristic sedimentation behaviour of a lipoprotein fraction of plasma in a centrifugal field in a medium of appropriate density, achieved by adding a salt or D2O to the plasma. Synonym: negative S, Svedberg of flotation. (05 Mar 2000) |
| law of constant numbers in ovulation | The number of ova discharged at each ovulation is nearly constant for any given species. (05 Mar 2000) |
| anal region | The posterior portion of the perineal region through which the anal canal opens; bounded by a line through both isehial tuberosities, the sacrotuberous ligaments and the coccyx. Synonym: regio analis, anal region. (05 Mar 2000) |
| ankle region | The region of the lower limb between the leg (crus) and the foot (pes). Synonym: regio talocruralis. (05 Mar 2000) |
| anterior antebrachial region | The area between the radial and ulnar borders of the forearm anteriorly. Synonym: facies antebrachialis anterior, regio antebrachialis anterior, anterior antebrachial region, anterior surface of forearm, facies anterior antebrachii. (05 Mar 2000) |
| anterior brachial region | The anterior region of the arm. (05 Mar 2000) |
| anterior carpal region | The anterior part of the wrist. Synonym: regio carpalis anterior. (05 Mar 2000) |
| anterior crural region | The anterior surface of the inferior limb between the knee and the ankle. Synonym: facies cruralis anterior, regio cruralis anterior, anterior crural region, anterior surface of leg, facies anterior cruris. (05 Mar 2000) |
| anterior cubital region | The area in front of the elbow, including the cubital fossa. Synonym: facies cubitalis anterior, regio cubitalis anterior, anterior cubital region, anterior surface of elbow. (05 Mar 2000) |
| anterior hypothalamic region | The rostral portion of the hypothalamus that includes preoptic, supraoptic, paraventricular and anterior hypothalamic nuclei; the hypothalamic structures located internally in the general area of the optic chiasm. (05 Mar 2000) |
| anterior knee region | The anterior region of the knee. Synonym: regio genus anterior. (05 Mar 2000) |