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string theory

(Encyclopedia)string theory, description of elementary particles based on one-dimensional curves, or “strings,” instead of point particles. Superstring theory, which is string theory that contains a kind of sym...

spectroscope

(Encyclopedia)spectroscope, optical instrument for producing spectral lines and measuring their wavelengths and intensities, used in spectral analysis (see spectrum). When a material is heated to incandescence it e...

Carey, Mathew

(Encyclopedia)Carey, Mathew, 1760–1839, American publisher, bookseller, and economist, b. Dublin. In his Dublin journal he violently attacked English rule of Ireland, was imprisoned for a month, fled to France, w...

carbon dioxide

(Encyclopedia)carbon dioxide, chemical compound, CO2, a colorless, odorless, tasteless gas that is about one and one-half times as dense as air under ordinary conditions of temperature and pressure. It does not bur...

atmosphere

(Encyclopedia)CE5 Atmosphere atmosphere [Gr.,=sphere of air], the mixture of gases surrounding a celestial body with sufficient gravity to maintain it. Although some details about the atmospheres of other plane...

mountain beaver

(Encyclopedia)mountain beaver, stout, short-limbed North American rodent, Aplodontia rufa, not closely related to the true beaver. Also called sewellel beaver after the Chinook word for a robe made from its pelts, ...

function

(Encyclopedia)function, in mathematics, a relation f that assigns to each member x of some set X a corresponding member y of some set Y; y is said to be a function of x, usually denoted f(x) (read “f of x ”)....

hypothalamus

(Encyclopedia)hypothalamus hīˌpəthălˈəməs [key], an important supervisory center in the brain, rich in ganglia, nerve fibers, and synaptic connections. It is composed of several sections called nuclei, each ...

antifreeze

(Encyclopedia)antifreeze, substance added to a solvent to lower its freezing point. The solution formed is called an antifreeze mixture. Antifreeze is typically added to water in the cooling system of an internal-c...

thermionic emission

(Encyclopedia)thermionic emission thûrmˌīŏnˈĭk [key], emission of electrons or ions by substances that are highly heated, the charged particles being called thermions. The number of thermions emitted increase...