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gnat

(Encyclopedia)gnat, common name for any one of a number of small, fragile-looking two-winged flies of the suborder Nematocera, order Diptera, which includes the families Tipulidae (crane flies), Bibionidae (hairfli...

stroboscope

(Encyclopedia)stroboscope strŏbˈəskōp [key], optical instrument for making a moving object appear to be slowed down or stationary. This effect is created by interrupting the observer's view so that the object i...

Karlin, John Elias

(Encyclopedia)Karlin, John Elias, American industrial psychologist and human-factors engineering pioneer, b. Johannesburg, South Africa, grad. Univ. of Cape Town (B.A., M.A.), Univ. of Chicago (Ph.D., 1942). With a...

Newcastle disease

(Encyclopedia)Newcastle disease, pneumoencephalitis, acute viral disease of domestic poultry. Newcastle disease is characterized by sneezing, coughing, and nervous behavior. Affected birds may show tremors, circlin...

Andromeda, in astronomy

(Encyclopedia)Andromeda, in astronomy, northern constellation located to the NE of Pegasus and to the S of Cassiopeia. Its brightest star, Alpheratz (Alpha Andromedae), marks the northeast corner of the Great Squar...

suspension, in chemistry

(Encyclopedia)suspension, in chemistry, mixture of two substances, one of which is finely divided and dispersed in the other. Common suspensions include sand in water, fine soot or dust in air, and droplets of oil ...

photoelectric cell

(Encyclopedia)CE5 Photoelectric cell: Light causes a photosensitive surface to emit electrons, which flow as current to the positive terminal. A galvanometer measures the current and thus indicates light intensi...

Mohammadi, Narges

(Encyclopedia)Narges Mohammadi, 1972– , b. Zanjan, Iran, Iranian human rights activist and author, studied at Imam Khomeini International University, also known as ...

Brunhes, Jean

(Encyclopedia)Brunhes, Jean brün [key], 1869–1932, French geographer. He was a leading exponent of French systematic, as opposed to regional, geography. He studied human artifacts in the context of environment. ...

illusionism

(Encyclopedia)illusionism, in art, a kind of visual trickery in which painted forms seem to be real. It is sometimes called trompe l'oeil [Fr.,=fool the eye]. The development of one-point perspective in the Renaiss...