| 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) |
| abdominal pressure | Pressure surrounding the bladder; estimated from rectal, gastric, or intraperitoneal pressure. (05 Mar 2000) |
| absolute pressure | Pressure measured with respect to zero pressure. Compare: gauge pressure. (05 Mar 2000) |
| acoustic pressure | In ultrasound, the instantaneous value of the total pressure minus the ambient pressure; unit is pascal (Pa). (05 Mar 2000) |
| air pressure | The force per unit area that the air exerts on any surface in contact with it. Primarily used for articles pertaining to air pressure within a closed environment. (12 Dec 1998) |
| atmospheric pressure | The pressure at any point in an atmosphere due solely to the weight of the atmospheric gases above the point concerned. (12 Dec 1998) |
| back pressure | Pressure exerted upstream in the circulation as a result of obstruction to forward flow, as when congestion in the pulmonary circulation results from stenosis of the mitral valve or failure of the left ventricle. (05 Mar 2000) |
| back-pressure renal atrophy | <radiology> Caliectasis without obstruction, due to repeated episodes of obstruction, gradual loss of renal pyramids (12 Dec 1998) |
| barometric pressure | The absolute pressure of the ambient atmosphere, varying with weather, altitude, etc.; expressed in millibars (meteorology) or mm Hg or torr (respiratory physiology); at sea level, one atmosphere (atm, 760 mm Hg or torr) is equivalent to: 14.69595 lb/sq in, 1013.25 millibars, 1013.25 × 106 dynes/cm2, and, in SI units, 101,325 pascals (Pa). Synonym: atmospheric pressure. (05 Mar 2000) |
| bile duct pressure | <radiology> Normal: 15-20 cm H2O (12 Dec 1998) |
| biting pressure | Any force exerted upon the occlusal surfaces of teeth. Synonym: biting pressure. (05 Mar 2000) |
| blood pressure | <cardiology, physiology> The force that the circulating blood exerts on the walls of the arteries. This measurement is divided into systolic (pressure during contraction of the heart) and diastolic (pressure during relaxation phase). Blood pressure varies with age and sex of the individual. A rough rule of thumb for normal systolic pressure is 100 + Age of individual. In children 2 x (age) + 80 = systolic BP The diastolic pressure should be roughly 2/3 the systolic pressure. (27 Sep 1997) |
| blood pressure determination | Techniques for measuring blood pressure. (12 Dec 1998) |