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semaphore

(Encyclopedia)CE5 Positions of a railroad semaphore: (A) clear, (B) caution, (C) stop semaphore sĕmˈəfôrˌ [key], device for the visible transmission of messages. The marine semaphore, used by day between s...

adaptive radiation

(Encyclopedia)CE5 Adaptive radiation in Hawaiian honey-creepers adaptive radiation, in biology, the evolution of an ancestral species, which was adapted to a particular way of life, into many diverse species, e...

quadratic

(Encyclopedia)quadratic, mathematical expression of the second degree in one or more unknowns (see polynomial). The general quadratic in one unknown has the form ax2+bx+c, where a, b, and c are constants and x is t...

3D printer

(Encyclopedia)3D printer, computerized device that produces a three-dimensional object by creating it as a series of thin layers. The object is created from a model stored in computer-aided design file; the model i...

sundial

(Encyclopedia)sundial, instrument that indicates the time of day by the shadow, cast on a surface marked to show hours or fractions of hours, of an object on which the sun's rays fall. Although any object whose sha...

leaf

(Encyclopedia)CE5 Microscopic cross section of the leaf blade CE5 Types of leaves leaf, chief food-manufacturing organ of a plant, a lateral outgrowth of the growing point of stem. The typical leaf consist...

semiconductor

(Encyclopedia)CE5 N-type and P-type crystals: In a pure silicon crystal each silicon atom (Si) is surrounded by four valence electrons. In the N-doped semiconductor, illustrated in the left-hand figure, some sil...

Fitzgerald, Ella

(Encyclopedia)Fitzgerald, Ella, 1917–96, American jazz singer, b. Newport News, Va. Probably the most celebrated jazz vocalist of her generation, Fitzgerald was reared in Yonkers, N.Y., moving after her mother's ...

needlefish

(Encyclopedia)needlefish, common name for members of the family Belonidae, which comprises species of elongated, surface-swimming predaceous fish abundant in warm seas. They have beaklike jaws armed with sharp teet...

oilbird

(Encyclopedia)oilbird, common name for an owllike, cave-dwelling bird, Steatornis caripensis, belonging to the family Steatornithidae. It spends its days in dark caves, maneuvering by means of a batlike sonar devic...