| shear rate | The change in velocity of parallel planes in a flowing fluid separated by unit distance; its units expressed in seconds-1. (05 Mar 2000) |
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| slew rate | In electronic pacemaker function, the maximum rate of change of an amplifier output voltage; important variable affecting heart function as controlled by an electronic pacemaker. Sensing circuits in the pacemaker often respond to the slew rate rather than to the absolute amplitude of the voltage pulse. (05 Mar 2000) |
| steady-state rate | The velocity of an enzyme-catalyzed reaction in which, over the time course of the study, the concentration of any enzyme species is constant (i.e., for an enzyme-substrate binary complex, ES, d[ES]/dt&apprxeq;00; for this to hold true, the total enzyme concentration must be much less than the initial substrate concentration. Synonym: steady-state rate. (05 Mar 2000) |
| steroid metabolic clearance rate | A measure of the rate of metabolism of a given steroid within the body, usually expressed as liters of body fluid that contain the amount of steroid metabolised per day. (05 Mar 2000) |
| steroid production rate | The total quantity of a given steroid formed in the body, usually expressed as milligrams per day; represents the sum of the glandular secretion of the steroid and extraglandular formation of it from various steroid precursors. (05 Mar 2000) |
| steroid secretory rate | The rate of glandular secretion of a given steroid, usually expressed as milligrams per day; does not include any amount of the steroid that might be formed extraglandularly. (05 Mar 2000) |
| stillbirth rate | The number of foetal deaths divided by the sum of live births and foetal deaths occurring in the same population during the same time period. Synonym: stillbirth rate. (05 Mar 2000) |
| death rate | The number of deaths in the population divided by the average population (or the population at midyear) is the crude death rate. In 1994, for example, the crude death rate per 1,000 population was 8.8 in the United States, 7.1 in Australia, etc. A death rate can also be tabulated according to age or cause. (12 Dec 1998) |
| survival rate | The proportion of survivors in a group, e.g., of patients, studied and followed over a period, or the proportion of persons in a specified group alive at the beginning of a time interval who survive to the end of the interval. It is often studied using life table methods. (12 Dec 1998) |
| discount rate | A rate used to convert future costs or benefits to their present value. (05 Dec 1998) |
| inception rate | The rate at which new spells of illness or cases of a condition occur in a population. (05 Mar 2000) |
| incidence rate | The rate at which new events occur in a population. The numerator is the number of new events occurring in a defined period; the denominator is the population at risk of experiencing the event during this period. (05 Mar 2000) |
| initial rate | The rate of a reaction, e.g., an enzyme-catalyzed reaction, at the early stages of the reaction such that the product(s) concentrations have not risen to a level to significantly affect the observable rate; typically, initial velocities are observed when less than 10% of the reaction's approach toward equilibrium has occurred. Synonym: initial rate. (05 Mar 2000) |
| instantaneous rate | <epidemiology> In a short time interval (e.g a week), the number of events (e.g. Births in the UK) taking place during the interval is approximately proportional to the length of the interval. The constant of proportionality is the rate at which these events occur. This argument becomes more and more exact as the length of the time interval becomes shorter and shorter. When the time interval has shrunk to an instant, the rate has become an `instantaneous rate'. A bad term; just call it a rate. (05 Dec 1998) |
| integrated rate expression | An equation of a chemical or enzyme-catalyzed reaction for the entire progress curve. (05 Mar 2000) |