Columbia Encyclopedia

Search results

500 results found

radar astronomy

(Encyclopedia)radar astronomy, application of radar to the determination of distances and planetary features within the solar system, such as rotation rates. A short burst of radio waves is transmitted in the direc...

radio astronomy

(Encyclopedia)radio astronomy, study of celestial bodies by means of the electromagnetic radio frequency waves they emit and absorb naturally. Radio waves also come from outside the Milky Way. These extragalact...

synchrotron radiation

(Encyclopedia)synchrotron radiation, in physics, electromagnetic radiation emitted by high-speed electrons spiraling along the lines of force of a magnetic field (see magnetism). Depending on the electron's energy ...

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...

X-ray astronomy

(Encyclopedia)X-ray astronomy, study of celestial objects by means of the X rays they emit, in the wavelength range from 0.01 to 10 nanometers. X-ray astronomy dates to 1949 with the discovery that the sun emits X ...

tamoxifen

(Encyclopedia)tamoxifen təmŏkˈsĭfĕnˌ [key], synthetic hormone used in the treatment of breast cancer. Introduced in 1978, tamoxifen is used to prevent recurrences of cancer in women who have already undergone...

In

(Encyclopedia)In, symbol for the element indium. ...

Allison, James Patrick

(Encyclopedia)Allison, James Patrick, 1948–, American immunologist, b. Alice, Tex., Ph.D. Univ. of Texas, Austin, 1973. Allison was a researcher at the Univ. of Texas System Cancer Center in Houston from 1977 to ...

sarcoma

(Encyclopedia)sarcoma särkōˈmə [key], highly malignant tumor arising in connective- and muscle-cell tissue. It is the result of oncogenes (the cancer causing genes of some viruses) and proto-oncogenes (cancer c...

mammography

(Encyclopedia)mammography, diagnostic procedure that uses low-dose X rays to detect abnormalities in the breasts. Tomosynthesis, also known as 3D mammography, is form of mammography that combines X-ray images taken...