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polyp and medusa

(Encyclopedia)CE5 Polyp and medusa stages in the life cycle of Obelia, representative of the phylum Cnidaria polyp and medusa, names for the two body forms, one nonmotile and one typically free swimming, found ...

population I and II

(Encyclopedia)population I and II, in astronomy: see stellar populations. ...

oxidation and reduction

(Encyclopedia)oxidation and reduction, complementary chemical reactions characterized by the loss or gain, respectively, of one or more electrons by an atom or molecule. Originally the term oxidation was used to re...

acids and bases

(Encyclopedia)acids and bases, two related classes of chemicals; the members of each class have a number of common properties when dissolved in a solvent, usually water. Another theory that provides a very broad ...

permutations and combinations

(Encyclopedia)permutations and combinations: see probability. ...

orchestra and orchestration

(Encyclopedia)CE5 Typical seating plan of a symphony orchestra orchestra and orchestration, an orchestra is a musical ensemble of mixed instruments based on strings and winds, under the direction of a conductor...

visit and search

(Encyclopedia)visit and search: see search, right of. ...

monitorial system

(Encyclopedia)monitorial system, method of elementary education devised by British educators Joseph Lancaster and Andrew Bell during the 19th cent. to furnish schooling to the underprivileged even under conditions ...

Thorne, Kip Stephen

(Encyclopedia)Thorne, Kip Stephen, 1940–, American theoretical physicist, b. Logan, Utah. Ph.D. Princeton, 1965. Thorne has been a professor (emeritus from 2009) at the California Institute of Technology since 19...

pacemaker, artificial

(Encyclopedia)pacemaker, artificial, device used to stimulate a rhythmic heartbeat by means of electrical impulses. Implanted in the body when the heart's own electrical conduction system (natural pacemaker) does n...