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Hot Springs National Park

(Encyclopedia)Hot Springs National Park, 5,549 acres (2,247 hectares), W central Ark.; est. 1921; nearly surrounded by the city of Hot Springs. Visited by Spanish explorer Hernando De Soto in 1541, the springs, lon...

Hertzsprung, Ejnar

(Encyclopedia)Hertzsprung, Ejnar īˈnär hĕrtsˈspro͞ong [key], 1873–1967, Danish astronomer. Although trained as a chemical engineer, Hertzsprung made his career in astronomy, specializing in exacting photogr...

Anderson, Philip Warren

(Encyclopedia)Anderson, Philip Warren, 1923–2020, American physicist, b. Indianapolis, Ind., Ph.D. Harvard, 1949. After graduation he worked at Bell Laboratories until 1984. From 1967 he also was on the faculty a...

ammonium nitrate

(Encyclopedia)ammonium nitrate, chemical compound, NH4NO3, that exists as colorless, rhombohedral crystals at room temperature but changes to monoclinic crystals when heated above 32℃. It is extremely soluble in ...

nastic movement

(Encyclopedia)nastic movement, in botany, the movement of plant parts in response either to certain external stimuli or to internal growth stimuli. Nastic movements, which are generally slow, can be observed by tim...

Mather, John Cromwell

(Encyclopedia)Mather, John Cromwell, 1946–, American astrophysicist, b. Roanoke, Va., Ph.D. Univ. of California, Berkeley, 1974. He has been a researcher at NASA's Goddard Space Flight Center in Greenbelt, Md., s...

pasteurization

(Encyclopedia)pasteurization păsˌcho͝orĭzāˈshən, –rīzāˈshən [key], partial sterilization of liquids such as milk, orange juice, wine, and beer, as well as cheese, to destroy disease-causing and other u...

Réaumur, René Antoine Ferchault de

(Encyclopedia)Réaumur, René Antoine Ferchault de rāˈəmyo͝or, Fr. rənāˈ äNtwänˈ fĕrshōˈ də rāōmürˈ [key], 1683–1757, French physicist and naturalist. He invented an alcohol thermometer (1731) a...

actinometer

(Encyclopedia)actinometer ăkˌtənŏmˈətər [key], instrument used to measure the heating power of radiation. Actinometers are used chiefly in meteorology to measure solar radiation as transmitted directly by th...

Termez

(Encyclopedia)Termez tyĭrmyĕsˈ [key], city (1991 pop. 99,000), capital of Surkhandaryo region, S Uzbekistan, a port on the Amu Darya River, near the Afghanistan border. It is the center of an agricultural region...