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tropism

(Encyclopedia)tropism trōpˈĭzəm [key], involuntary response of an organism, or part of an organism, involving orientation toward (positive tropism) or away from (negative tropism) one or more external stimuli. ...

Trans-Dniester Region

(Encyclopedia)Trans-Dniester Region or Transnistria, region (2004 preliminary pop. 555,000), E Moldova, between the Dniester River and the Ukrainian border. A narrow territory some 120 mi (195 km) long but barely 2...

Ruthenia

(Encyclopedia)Ruthenia ro͞othēˈnēə [key], Latinized form of the word Russia. The term was applied to Ukraine in the Middle Ages when the princes of Halych briefly assumed the title kings of Ruthenia. Later, in...

cluster munitions

(Encyclopedia)cluster munitions or cluster bombs, air-dropped or ground-launched weapons that open in mid-air and scatter dozens, hundreds, or thousands of smaller submunitions (or bomblets) over a wide area. Such ...

Iran hostage crisis

(Encyclopedia)Iran hostage crisis, in U.S. history, events following the seizure of the American embassy in Tehran by Iranian students on Nov. 4, 1979. The overthrow of Muhammad Reza Shah Pahlevi of Iran by an Isla...

free energy

(Encyclopedia)free energy or Gibbs free energy, quantity derived from the relationships between heat and work studied in thermodynamics and used as a measure of the relative stability of a physical or chemical syst...

Meiji restoration

(Encyclopedia)Meiji restoration, The term refers to both the events of 1868 that led to the “restoration” of power to the emperor and the entire period of revolutionary changes that coincided with the Meiji emp...

rayon

(Encyclopedia)rayon, synthetic fibers made from cellulose or textiles woven from such fibers; more rayon is manufactured than any other synthetic fiber. The name was adopted (1924), in preference to “artificial s...

solar wind

(Encyclopedia)solar wind, stream of ionized hydrogen—protons and electrons—with an 8% component of helium ions and trace amounts of heavier ions that radiates outward from the sun at high speeds. The continuous...

Safavid

(Encyclopedia)Safavid säfäˈwēd [key], Iranian dynasty (1499–1736), that established Shiite Islam in Iran as an official state religion. The Safavid state provided both the territorial and societal foundations...