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waxbill

(Encyclopedia)waxbill, common name for small, brightly colored weaver finches of the Estrildini tribe of the family Estrildidae. Most are African with the exception of two S Asian species of avadavats, and one Aust...

Weiss, Rainer

(Encyclopedia)Weiss, Rainer, 1932–, American physicist, b. Berlin, Germany, Ph.D. Massachusetts Institute of Technology, 1962. Weiss has been on the faculty of the Massachusetts Institute of Technology since 1964...

glacial periods

(Encyclopedia)glacial periods, times during which large portions of the earth's surface were covered with thick glacial ice sheets. In the Pleistocene epoch, in the Carboniferous and Permian periods of the Paleozoi...

breast cancer

(Encyclopedia)breast cancer, cancer that originates in the breast. Breast cancer is the second leading cause of cancer death in women (following lung cancer). Although the vast majority of the cases occur in women,...

Kaposi's sarcoma

(Encyclopedia)Kaposi's sarcoma käpˈəshēˌ, kəpōˈsē [key], a usually fatal cancer that was considered rare until its appearance in AIDS patients. First described by an Austro-Hungarian physician, Moritz Kapo...

Giacconi, Riccardo

(Encyclopedia)Giacconi, Riccardo, 1931–2018, Italian-American astrophysicist, b. Milan, Italy, Ph.D. Univ. of Milan 1954. He was a researcher at American Science and Engineering Corporation (1959–73), professor...

fallout

(Encyclopedia)fallout, minute particles of radioactive material produced by nuclear explosions (see atomic bomb; hydrogen bomb; Chernobyl) or by discharge from nuclear-power or atomic installations and scattered th...

plant breeding

(Encyclopedia)plant breeding, science of altering the genetic pattern of plants in order to increase their value. Increased crop yield is the primary aim of most plant-breeding programs; advantages of the hybrids a...

PET scan

(Encyclopedia)PET scan pŏzˈĭtrŏnˌ ĭmĭshˈən təmŏgˈrəfē [key], a medical imaging technique that monitors metabolic, or biochemical, activity in the brain and other organs by tracking the movement and co...

ultrasound

(Encyclopedia)ultrasound or sonography, in medicine, technique that uses sound waves to study and treat hard-to-reach body areas. In scanning with ultrasound, high-frequency sound waves are transmitted to the area ...