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gamma-ray astronomy

(Encyclopedia)gamma-ray astronomy, study of astronomical objects by analysis of the most energetic electromagnetic radiation they emit. Gamma rays are shorter in wavelength and hence more energetic than X rays (see...

deafness

(Encyclopedia)deafness, partial or total lack of hearing. It may be present at birth (congenital) or may be acquired at any age thereafter. A person who cannot detect sound at an amplitude of 20 decibels in a frequ...

Clay, Henry

(Encyclopedia)Clay, Henry, 1777–1852, American statesman, b. Hanover co., Va. In 1828, Clay again supported Adams for President, and Jackson's success bitterly disappointed him. Although he intended to retir...

Declaration of Independence

(Encyclopedia)Declaration of Independence, full and formal declaration adopted July 4, 1776, by representatives of the Thirteen Colonies in North America announcing the separation of those colonies from Great Brita...

Roosevelt, Franklin Delano

(Encyclopedia)Roosevelt, Franklin Delano rōˈzəvĕlt [key], 1882–1945, 32d President of the United States (1933–45), b. Hyde Park, N.Y. Apart from extending diplomatic recognition to the USSR (1933), th...

Hinduism

(Encyclopedia)Hinduism hinˈdo͞oĭzəm [key], Western term for the religious beliefs and practices of the vast majority of the people of India. One of the oldest living religions in the world, Hinduism is unique a...

vitamin

(Encyclopedia)vitamin, group of organic substances that are required in the diet of humans and animals for normal growth, maintenance of life, and normal reproduction. Vitamins act as catalysts; very often either t...

British Empire

(Encyclopedia)British Empire, overseas territories linked to Great Britain in a variety of constitutional relationships, established over a period of three centuries. The establishment of the empire resulted primar...

Iowa, state, United States

(Encyclopedia)CE5 Iowa īˈəwə [key], midwestern state in the N central United States. It is bounded by the Mississippi River, across which lie Wisconsin and Illinois (E); Missouri (S); Nebraska and South Dako...

American art

(Encyclopedia)American art, the art of the North American colonies and of the United States. There are separate articles on American architecture, North American Native art, pre-Columbian art and architecture, Mexi...