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tobogganing

(Encyclopedia)tobogganing, sport of coasting down snowy hillsides or chutes on a toboggan, a flat-bottomed vehicle made of hard wood. The toboggan, typically measuring 1.5 ft by 6–8 ft (.46 m by 1.8–2.4 m), is ...

Carruthers, George Richard

(Encyclopedia) Carruthers, George Richard, 1939-2020, African-American astrophysicist, b. Cincinnati, OH, Univ. of Illinois at Urbana-Champaign (BS, 1961; MS, nuclear...

sudden infant death syndrome

(Encyclopedia)sudden infant death syndrome (SIDS) or crib death, sudden, unexpected, and unexplained death of an apparently healthy infant under one year of age (usually between two weeks and eight months old). SID...

spring, in mechanics

(Encyclopedia)spring, in mechanics, any of several elastic devices used variously to store and to furnish energy, to absorb shock, to sustain the pressure between contacting surfaces, and to resist tensional or com...

butyric acid

(Encyclopedia)butyric acid byo͞otənōˈĭk [key], CH3CH2CH2CO2H, viscous, foul-smelling, liquid carboxylic acid; m.p. about −5℃; b.p. 163.5℃. It is miscible with water, ethanol, and ether. It is a low molec...

artificial limb

(Encyclopedia)artificial limb, mechanical replacement for a missing limb. An artificial limb, called a prosthesis, must be light and flexible to permit easy movement, but must also be sufficiently sturdy to support...

fireproofing

(Encyclopedia)fireproofing, method of making normally combustible materials as nearly noncombustible as possible. Fireproofing generally applies to textiles and construction materials that are treated with a soluti...

Day, Dorothy

(Encyclopedia)Day, Dorothy, 1897–1980, American journalist and social activist, b. New York City. After studying at the Univ. of Illinois (1914–16), where she joined the Socialist party, she returned to New Yor...

Richter, Burton

(Encyclopedia)Richter, Burton rĭkˈtər [key], 1931–2018, American physicist, b. New York City, Ph.D. Massachusetts Institute of Technology, 1956. A professor at Stanford, Richter designed and built a particle a...

X-ray crystallography

(Encyclopedia)X-ray crystallography, the study of crystal structures through X-ray diffraction techniques. When an X-ray beam bombards a crystalline lattice in a given orientation, the beam is scattered in a defini...