| RCM | radial contour model; radiographic contrast medium; red cell mass; reinforced clostridial medium; re... |
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| RD | radial deviation; radiology department; rate difference; Raynaud disease; reaction of degeneration; ... |
| REAR | renal, ear, anal, and radial [malformation syndrome] |
| RF | radial fiber; radio frequency; receptive field; regurgitant fraction; Reitland-Franklin [unit]; rela... |
| RID | radial immunodiffusion; remission-inducing drug; ruptured intervertebral disc |
shelf force
| electrostatic force | <radiobiology> Like charges in close proximity produce forces of repulsion between them. Consequently if two surfaces bear appreciable and approximately equal densities of charged groups on their surfaces appreciable forces of repulsion may occur between them. The range of these forces is determined in the main by the ionic strength of the intervening medium, forces being of minimal range at high ionic strength. The forces are effective over approximately twice the double layer thickness. See: DLVO theory. (18 Nov 1997) |
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| unit of force | CGS system: dyne, FPS system: poundal, MKS system: newton,SI: newton. (05 Mar 2000) |
| force | <physics> Rate of change of momentum with time. Forces are said to cause accelerations via f = ma (Newton's law). There are four primary forces known presently: the gravitational, electromagnetic, weak nuclear, and strong nuclear forces. The gravitational and electromagnetic forces are long-range (dropping as 1/distance^2), while the nuclear forces are short range (effective only within nuclei, distances on the order of 10^-15 metres). The electromagnetic force is much stronger than the gravitational force, but is generally cancelled over large distances because of the balance of positive and negative charges. See: momentum. (04 Apr 1998) |
| force of infection | <epidemiology> The per capita rate at which susceptibles are infected. (05 Dec 1998) |
| force of mastication | The motive force created by the dynamic action of the muscles during the physiologic act of mastication. Synonym: biting strength, masticatory force. (05 Mar 2000) |
| force platform | A device used to measure the strength, symmetry, and latency of compensatory postural movements when visual, vestibular, and somatosensory stimuli are varied. (05 Mar 2000) |
| force pump | <machinery> A pump having a solid piston, or plunger, for drawing and forcing a liquid, as water, through the valves; in distinction from a pump having a bucket, or valved piston. A pump adapted for delivering water at a considerable height above the pump, or under a considerable pressure; in distinction from one which lifts the water only to the top of the pump or delivers it through a spout. Source: Websters Dictionary (01 Mar 1998) |
| force-velocity curve | The relationship between isotonic velocity of shortening and afterload for a contracting muscle. (05 Mar 2000) |
| lorentz force | <physics> Total electromagnetic force on a charged particle moving in electric & magnetic fields. F = q(E + (v/c)xB). See: force, cross product, charge, velocity, and relevant variable symbols. (09 Oct 1997) |
| radial | <botany> Of or pertaining to a radius or ray; consisting of, or like, radii or rays; radiated; as, the radial artery. Radial symmetry. <biology> See Symmetry. Origin: Cf. F. Radial. See Radius. Source: Websters Dictionary (01 Mar 1998) |
| radial acceleration | The centripetal acceleration of a particle or vehicle moving along a curved path at a constant velocity; e.g., turning a curve in an automobile, pulling out of a dive, or performing a loop manoeuvre in an aircraft. In aviation, acceleration varies directly with the square of the air speed and inversely with the radius of the turn (a = V2/r, where V is air speed and r is radius of turn). (05 Mar 2000) |
| radial aplasia-thrombocytopenia syndrome | <syndrome> Aplasia (absence) of the radius (the long bone on the thumb-side of the forearm) and thrombocytopenia (low blood platelets) are key features characterizing this syndrome. There is phocomelia (flipper-limb) with the thumbs always present. The fibula (the smaller bone in the lower leg) is often absent. The risk of bleeding from too few platelets is high in early infancy but lessens with age. The condition is inherited in an autosomal recessive trait with one gene (on a non-sex chromosome) coming from each parent to the child affected with the disease. Alternative names include thrombocytopenia-absent radius syndrome, tar syndrome, and tetraphocomelia-thrombocytopenia syndrome. (12 Dec 1998) |
| radial artery | <anatomy, artery> The direct continuation of the brachial trunk, originating at the bifurcation of the brachial artery opposite the neck of the radius. Its branches may be divided into three groups corresponding to the three regions in which the vessel is situated, the forearm, wrist, and hand. (12 Dec 1998) |
| radial border of forearm | An imaginary line running along the outermost extent of the forearm separating anterior and posterior surfaces laterally. Synonym: margo lateralis antebrachii, margo radialis antebrachii, radial border of forearm. (05 Mar 2000) |
| radial bursa | <anatomy> The synovial sheath that envelops the tendon of the flexor pollicis longus in its course through the carpal canal; it is continuous with the digital sheath of the thumb, the two generally being considered as one sheath. Synonym: vagina tendinis musculi flexoris pollicis longi, radial bursa. (05 Mar 2000) |