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barograph

(Encyclopedia)barograph, instrument used to make a continuous recording of atmospheric pressure. The pressure-sensitive element, a partially evacuated metal cylinder, is linked to a pen arm in such a way that the v...

pitot static system

(Encyclopedia)pitot static system pētōˈ [key], device for measuring the rate at which a fluid flows. Among the principal applications of the device are an airspeed indicator for aircraft and a distance and speed...

spleen

(Encyclopedia)spleen, soft, purplish-red organ that lies under the diaphragm on the left side of the abdominal cavity. The spleen acts as a filter against foreign organisms that infect the bloodstream, and also fil...

space medicine

(Encyclopedia)space medicine, study of the medical and biological effects of space travel on living organisms. The principal aim is to discover how well and for how long humans can withstand the extreme conditions ...

boiling point

(Encyclopedia)boiling point, temperature at which a substance changes its state from liquid to gas. A stricter definition of boiling point is the temperature at which the liquid and vapor (gas) phases of a substanc...

anxiety

(Encyclopedia)anxiety, anticipatory tension or vague dread persisting in the absence of a specific threat. In contrast to fear, which is a realistic reaction to actual danger, anxiety is generally related to an unc...

quinine

(Encyclopedia)quinine kwīˈnīnˌ, kwĭnēnˈ [key], white crystalline alkaloid with a bitter taste. Before the development of more effective synthetic drugs such as quinacrine, chloroquine, and primaquine, quinin...

rhythm, biological

(Encyclopedia)rhythm, biological, or biorhythm, cyclic pattern of physiological changes or changes in activity in living organisms, most often synchronized with daily, monthly, or annual cyclical changes in the env...

nitric oxide

(Encyclopedia)nitric oxide or nitrogen monoxide, a colorless gas formed by the combustion of nitrogen and oxygen as given by the reaction: energy + N2 + O2 → 2NO; m.p. −163.6℃; b.p. −151.8℃. Nitric oxide ...

Black Hawk War

(Encyclopedia)Black Hawk War, conflict between the Sac and Fox and the United States in 1832. After the War of 1812, whites settling the Illinois country exerted pressure on the Native Americans. A treaty of 1804, ...