Columbia Encyclopedia

Search results

321 results found

cosmic rays

(Encyclopedia)cosmic rays, charged particles moving at nearly the speed of light reaching the earth from outer space. Primary cosmic rays consist mostly of protons (nuclei of hydrogen atoms), some alpha particles (...

death

(Encyclopedia)death, cessation of all life (metabolic) processes. Death may involve the organism as a whole (somatic death) or may be confined to cells and tissues within the organism. Causes of death in human bein...

ultraviolet astronomy

(Encyclopedia)ultraviolet astronomy, study of celestial objects by means of the ultraviolet radiation they emit, in the wavelength range from about 90 to about 350 nanometers. Ultraviolet (UV) line spectrum measure...

ozone layer

(Encyclopedia)ozone layer or ozonosphere, region of the stratosphere containing relatively high concentrations of ozone, located at altitudes of 12–30 mi (19–48 km) above the earth's surface. Ozone in the ozone...

horseshoe crab

(Encyclopedia)horseshoe crab, large, primitive marine arthropod of the family Limulidae, related to the spider and scorpion and sometimes called a king crab (a name also used for the largest of the edible true crab...

infarction

(Encyclopedia)infarction, blockage of blood circulation to a localized area or organ of the body resulting in tissue death. Infarctions commonly occur in the spleen, kidney, lungs, brain, and heart. The acute emerg...

iodine

(Encyclopedia)iodine īˈədīn, –dĭn [key] [Gr.,=violet], nonmetallic chemical element; symbol I; at. no. 53; at. wt. 126.90447; m.p. 113.5℃; b.p. 184.35℃; sp. gr. 4.93 at 20℃; valence −1, +1, +3, +5, o...

anemia

(Encyclopedia)anemia ənēˈmēə [key], condition in which the concentration of hemoglobin in the circulating blood is below normal. Such a condition is caused by a deficient number of erythrocytes (red blood cell...

steel industry

(Encyclopedia)steel industry, the business of processing iron ore into steel, which in its simplest form is an iron-carbon alloy, and in some cases, turning that metal into partially finished products or recycling ...

carbon cycle

(Encyclopedia)CE5 Carbon cycle carbon cycle, in biology, the exchange of carbon between living organisms and the nonliving environment. Inorganic carbon dioxide in the atmosphere is converted by plants into sim...