| RI | radiation intensity; radioactive isotope; radioimmunology; recession index; recombinant inbred [stra... |
|---|---|
| RF | radial fiber; radio frequency; receptive field; regurgitant fraction; Reitland-Franklin [unit]; rela... |
| RR | radiation reaction; radiation response; rate ratio; rational recovery [group]; recovery room; relati... |
| RSA | rabbit serum albumin; regular spiking activity; relative specific activity; relative standard accura... |
| VAS | Valvular Aortic Stenosis |
| relative accommodation | Quantity of accommodation required for single binocular vision for any specified distance, or for any particular degree of convergence. (05 Mar 2000) |
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| relative afferent pupillary defect | An asymmetry of the pupillomotor input between the two eyes; tested by alternating the light from one eye to the other and comparing the direct light reactions. (05 Mar 2000) |
| relative aperture | <microscopy> The ratio of the focal length of a lens to the diameter of its entrance pupil. This gives a number known as the f-number, usually written f:8, f:16, etc. Thus, if the focal length is divided by the number 8, 16, etc., the result will be the diameter of the entrance pupil of the lens, or if the diaphragm of the lens is wide open it will be very nearly the diameter of the free aperture of the lens. See: F-number. (05 Aug 1998) |
| relative basal area | An estimate of basal area for trees, such as produced by the Bitterlich sampling technique. (09 Oct 1997) |
| relative biological effectiveness | The ratio of radiation dosages required to produce identical change based on a formula comparing other types of radiation with that of gamma or roentgen rays. (12 Dec 1998) |
| relative dehydration | Water deficit relative to content of solutes contributing effective osmotic pressure; a state of increased effective osmotic pressure of body fluids. (05 Mar 2000) |
| relative immunity | A modified, not completely effective resistance that results when there is a sort of "fluctuating equilibrium" between the defense mechanisms of the host and the infective agent. (05 Mar 2000) |
| relative incompetence | Imperfect closure of a cardiac valve, in consequence of excessive dilation of the corresponding cavity of the heart. (05 Mar 2000) |
| relative leukocytosis | An increased proportion of one or more types of leukocytes in the circulating blood, without an actual increase in the total number of white blood cells. (05 Mar 2000) |
| relative molecular mass | The sum of the atomic weight's of all the atoms constituting a molecule; the mass of a molecule relative to the mass of a standard atom, now 12C (taken as 12.000). Relative molecular mass (Mr) is the mass relative to the dalton and has no units. See: atomic weight. Synonym: molecular mass, molecular weight ratio, relative molecular mass. (05 Mar 2000) |
| relative polycythemia | A relative increase in the number of red blood cells as a result of loss of the fluid portion of the blood. (05 Mar 2000) |
| relative refractory period | The period between the effective refractory period and the end of the refractory period; fibres then respond only to high intensity stimuli and the impulses conduct more slowly than normally. (05 Mar 2000) |
| relative risk | <epidemiology> The proportion of diseased people amongst those exposed to the relevant risk factor divided by the proportion of diseased people amongst those not exposed to the risk factor. This should be used in those cohort studies where those with and without disease are followed to observe which individuals become diseased. (05 Dec 1998) |
| relative scotoma | A scotoma in which there is visual depression but not complete loss of light perception. (05 Mar 2000) |
| relative sensitivity | The sensitivity of a medical screening test as determined by comparison with the same type of test; e.g., sensitivity of a new serological test relative to sensitivity of an established serological test. (05 Mar 2000) |