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- Number of terms: 178089
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McGraw Hill Financial, Inc. is an American publicly traded corporation headquartered in Rockefeller Center in New York City. Its primary areas of business are financial, publishing, and business services.
A type of electrical conduction that generally occurs at or near atmospheric pressure in gases. A relatively strong electric field is needed. External manifestations are the emission of light and a hissing sound. The particular characteristics of the discharge are determined by the shape of the electrodes, the polarity, the size of the gap, and the gas or gas mixture.
Industry:Science
A type of electric-discharge lamp in which an electric current flows between electrodes through a gas or vapor. In most arc lamps the light results from the luminescence of the gas; however, in the carbon arc lamp a major portion of the light is produced by the incandescence of one or both electrodes. The color of the arc depends upon the electrode material and the surrounding atmosphere. Most lamps have a negative resistance characteristic so that the resistance decreases after the arc has been struck. Therefore some form of current-limiting device is required in the electric circuit. For other electric-discharge lamps
Industry:Science
A type of embryological study in which the history of individual blastomeres (cells formed during division of the zygote) or meristem cells is traced to their ultimate differentiation into tissues and organs.
Industry:Science
A type of flow pattern exhibited by superfluids, such as liquid <sup>4</sup>He below 2.17 K. The term vortex designates the familiar whirlpool pattern where the fluid moves circularly around a central line and the velocity diminishes inversely proportionally to the distance from the center. The strength of a vortex is determined by the circulation <i>k</i>, which is the line integral of the velocity around any path enclosing the central line.
For an ordinary vortex, <i>k</i> can possess any value; for a superfluid vortex, <i>k</i> is restricted to a quantized multiple of Planck's constant <i>h</i> divided by <i>m</i>, the mass of the helium atom. Hence the expression quantized vortex line. Although <i>h</i> and <i>m</i> are microscopic (that is, atomic) quantities, their ratio <i>h</i>/<i>m</i> is rather large, being equal to 10<sup>−3</sup> cm<sup>2</sup> · s<sup>−1</sup>.
Industry:Science
A type of ground squirrel belonging to the family Sciuridae in the order Rodentia. These stout, short-tailed, short-legged ground squirrels inhabit open plains, short-grass prairies, and plateaus in the western part of North America from Canada to Mexico. The short coarse fur is grayish-brown. They have small beady eyes, pouched cheeks, and a short flat tail. Adults have a head-body length of 280–330 mm (11–13 in.), a tail length of 30–115 mm (1–4.5 in.), and weigh 0.7–1.4 kg (1.5–3 lb).
Industry:Science
A type of hot, luminous star that is distinguished by its extremely dense and fast wind. The spectacularly bright, discrete bands of atomic emission from these winds greatly facilitated their discovery with the aid of a visual spectroscope by the French astronomers Charles Wolf and Georges Rayet at the Paris Observatory in 1867.
Industry:Science
A type of hydrothermal wall-rock alteration and a class of tin-tungsten deposits (so-called greisen deposits). Hydrothermal wall-rock alteration is the process whereby rocks on the margins of hydrothermal flow channels are changed from an original assemblage of minerals to a different one. This change occurs because of heat and mass exchange between water and rock. The term greisen was originally used by miners in Saxony with reference to relatively coarse-grained aggregates of quartz and muscovite found on the borders of tin veins in granite of the Erzegebirge.
Industry:Science
A type of instrument used to measure vacuum by application of the principle of Boyle's law.
Industry:Science
A type of intelligent control system which can emulate the reasoning procedures of a human expert in order to generate the necessary control action. Expert control systems seek to incorporate knowledge about control system design, practical operations, and abnormal system recovery plans to automate tasks normally performed by experienced control engineers (the experts). Techniques relating to the field of artificial intelligence are usually used for the purpose of acquiring and representing knowledge and for generating control decisions through an appropriate reasoning mechanism. As it operates essentially on a knowledge base, an expert control system is often referred to as a knowledge-based control system. One of the most important benefits associated with the use of an expert control system is the inherent capability of the system to deal with uncertainty in information. Information provided to these systems need not be complete or precise. It can be general, qualitative, or vague. These properties do not cause difficulty because, like humans, expert control systems possess functionalities to perceive, reason, infer, and deduce new information. They can learn, gain new knowledge, and improve their performance through experience.
Industry:Science
A type of magnetic fluid that consists of a colloidal suspension of nanoscopic magnetic particles in a carrier liquid. A ferrofluid behaves as a fluid that is attracted to an external magnetic field without a large change in its viscosity.
Industry:Science
