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elasmobranch

(Encyclopedia)elasmobranch ĭlăsˈməbrăngk [key], cartilaginous fish, member of the subclass Elasmobranchii of the vertebrate class Chondrichthyes (see Chordata). This group includes sharks, skates, and rays. ...

pentimento

(Encyclopedia)pentimento pĕnˌtəmĕnˈtō [key], painter's term for the evidence in a work that the original composition has been changed. Often the opaque pigment with which the artist covered a mistake or unwan...

pulsar

(Encyclopedia)pulsar, in astronomy, a neutron star that emits brief, sharp pulses of energy instead of the steady radiation associated with other natural sources. The study of pulsars began when Antony Hewish and h...

gamma radiation

(Encyclopedia)gamma radiation, high-energy photons emitted as one of the three types of radiation resulting from natural radioactivity. It is the most energetic form of electromagnetic radiation, with a very short ...

electric fish

(Encyclopedia)electric fish, name for various fish that produce electricity by means of organs usually developed from modified muscle tissue. The electric eels of South America are freshwater knifefish unrelated to...

sextant

(Encyclopedia)CE5 Sextant sextant, instrument for measuring the altitude of the sun or another celestial body; such measurements can then be used to determine the observer's geographical position or for other n...

Kendrew, John Cowdery

(Encyclopedia)Kendrew, John Cowdery, 1917–97, British biochemist, grad. Cambridge (Ph.D. 1949). He was a fellow of Peterhouse College at Cambridge from 1947 to 1975 and was scientific adviser to the British minis...

Hevesy, Georg von

(Encyclopedia)Hevesy, Georg von gāˈôrkh fən hĕˈvĕshē [key], 1885–1966, Hungarian physicist and chemist. He received the 1943 Nobel Prize in Chemistry for his work on the use of isotopes as tracers in stud...

gaillardia

(Encyclopedia)gaillardia gālärˈdēə [key], any plant of the genus Gaillardia of the Asteaceae family (aster family), including annual, biennial, and perennial herbs with showy heads of red and/or yellow ray flo...

Huber, Robert

(Encyclopedia)Huber, Robert ho͞oˈbər [key], 1937–, German biochemist. After receiving his doctorate at Munich Technical Univ., he worked both there and at the Max Planck Institute for Biochemistry. With Hartmu...