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1. respiration; right; roentgen. 2. In chemistry, a radical. It is an atom, ion or molecule with unpaired electrons. R is an abbreviation for that entity in a larger formula. 3. In the ideal gas equation, PV = nRT, R is the gas constant. Its value is 0.082 liter-atmospheres per degree per mole. 4. An abbreviation for the transmissibility of a contagious illness. An R = 1 implies that a single infected person (on average) transmits a given infection to one additional person. A disease with an R = 10 would be more contagious; one infected individual would on average transmit the infection to ten others.


1. Abbr. used in organic chemistry to indicate part of a molecule. 2. Rinne negative. SEE: Rinne test.


Rinne positive. SEE: Rinne test.


Symbol for boosted (enhanced with) ritonavir, used for antiretroviral therapies for HIV/AIDS that enhance the effect of protease inhibition with a small dose of ritonavir.


basic reproductive number; complete resection (of a tumor in surgical oncology).


rheumatoid arthritis; right atrium; robot-assisted; room air.


Symbol for the element radium.


Renin-angiotensin-aldosterone system.


(rab′ă-vĕrt′) Rabies vaccine.


(rab′ĕt-ing) Interlocking of the jagged edges of a fractured bone.


(rab′ĭt-poks″) An acute viral disease of laboratory rabbits.


(rab′ĭd) Pert. to or affected with rabies.


(rā′bēz) [L. rabies, rage] A fatal infection of the central nervous system (CNS) caused by the rabies virus. Human infection occurs as the result of a bite from a wild animal in which the virus is present. It may occasionally be transmitted by inhalation of infectious aerosol particles or contamination of conjunctiva or other mucous membranes by the saliva of an infected animal. The long incubation period, before signs of rabies appear, is 3 to 12 weeks; this means that wild animals that are displaying no signs of the disease may still be infected, thereby increasing the risk of human infection. SYN: hydrophobia (1). SEE: immune globulin; rabies vaccine.

 INCIDENCE: In 2013, the WHO estimated that 61,000 deaths from rabies occur each year. Most cases are in Asia or Africa, and almost all result from dog bites. Deaths caused by rabies are rare in the U.S., where the disease is identified in one or two people annually.

 CAUSES: Rabies is found almost exclusively in wild animals ...

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