tool or device for imparting a desired shape, form, or finish to a material. Examples include a perforated block through which metal or plastic is drawn or extruded, the hardened steel forms for producing the patterns on coins and medals ...
forming metal objects by injecting molten metal under pressure into dies, or molds. An early and important use of the technique was in the Mergenthaler Linotype machine (1884) to give line-long combinations of letters, but the appearance of the mass-production ...
common symptom or name of disease, especially of woody plants, characterized by progressive death of twigs, branches, shoots, or roots, starting at the tips. Staghead is a slow dieback of the upper branches of a tree; the dead, leafless limbs ...
coral atoll, largest and southernmost member of the Chagos Archipelago, in the central Indian Ocean. Occupying an area of about 10.5 square miles (27 square km), it consists of a V-shaped, sand-fringed cay, about 15 miles (24 km) in length ...
a group of Yuman-speaking Indians who originally inhabited large areas extending on both sides of what is now the U.S.-Mexican border in California and Baja California. They were named after the mission of San Diego.
genus of extinct brachiopods, or lamp shells, that occur as fossils in rocks deposited in marine environments of Carboniferous to Permian age (between 360 and 245 million years old). The two small, rather smooth valves of the shell of Dielasma ...
insulating material or a very poor conductor of electric current. When dielectrics are placed in an electric field, practically no current flows in them because, unlike metals, they have no loosely bound, or free, electrons that may drift through the ...
property of an electrical insulating material (a dielectric) equal to the ratio of the capacitance of a capacitor filled with the given material to the capacitance of an identical capacitor in a vacuum without the dielectric material. The insertion of ...
method by which the temperature of an electrically nonconducting (insulating) material can be raised by subjecting the material to a high-frequency electromagnetic field. The method is widely employed industrially for heating thermosetting glues, for drying lumber and other fibrous materials, ...
German organic chemist who with Kurt Alder was awarded the Nobel Prize for Chemistry in 1950 for their joint work in developing a method of preparing cyclic organic compounds.
the decisive engagement in the first Indochina War (1946-54). It consisted of a struggle between French and Viet Minh (Vietnamese Communist and nationalist) forces for control of a small mountain outpost on the Vietnamese border near Laos. The Viet Minh ...
father and son, members of a large family of German architects, who were among the leading builders in Bohemian Baroque. Among their joint works are the Church of St. Nicholas (1703-11, 1732-52) and the Brevnov Monastery (1708-21), both in Prague. ...
town and seaport, northern France, Seine-Maritime departement, Haute-Normandie region, on the English Channel, north of Rouen and northwest of Paris. It stands at the mouth of the Arques River in a valley bordered on each side by steep white cliffs.
(Latin: "Day of Wrath"), the opening words of a Latin hymn on the Last Judgment, ascribed to Thomas of Celano (d. c. 1256) and forming part of the office for the dead and requiem mass.
any internal-combustion engine in which air is compressed to a temperature sufficiently high to ignite fuel injected into the cylinder, where combustion and expansion actuate a piston. It converts the chemical energy stored in the fuel into mechanical energy, which ...
German thermal engineer who invented the internal-combustion engine that bears his name. He was also a distinguished connoisseur of the arts, a linguist, and a social theorist.
meeting of the Diet (assembly) of the Holy Roman Empire held at Worms, Germany, in 1521 that was made famous by Martin Luther's appearance before it to respond to charges of heresy. Because of the confused political and religious situation ...
any of the prescriptions as to what may or may not be eaten under particular conditions. These prescriptions and proscriptions are sometimes religious; often they are secular; frequently, they are both.
synthetic anthelmintic drug effective against certain parasitic filarial worms, which are endemic throughout most of the subtropical and tropical regions of the world. These parasites infect the blood and lymph channels in humans, causing the debilitating disease filariasis. Diethylcarbamazine is ...
nonsteroidal synthethic estrogen used as a drug and formerly used to promote growth of livestock. Unlike natural estrogens, DES remains active following oral administration. It is also administered as vaginal suppositories and by injection. DES breaks down more slowly in ...
regulating one's food intake for the purpose of improving one's physical condition, especially for the purpose of reducing obesity, or what is conceived to be excess body fat. Dieting plans are based on the reduction of any of the macronutrients ...
German-American motion-picture actress whose beauty, voice, aura of sophistication, and languid sensuality made her one of the world's most glamorous film stars.
French archaeologist and civil engineer who excavated the palaces of the ancient Persian kings Darius I the Great and Artaxerxes II at Susa (modern Shush, Iran) in 1885 and gathered a large collection of archaeological fragments, which were placed in ...
in Baltic religion, the sky god. Dievs and Laima, the goddess of human fate, determine human destiny and world order. Dievs is a wooer of Saule, the sun. As pictured by the pre-Christian Balts, he is an Iron Age Baltic ...
German-born language scholar who made the first major analysis of the Romance languages and thus founded an important branch of comparative linguistics.
mathematical equality involving the differences between successive values of a function of a discrete variable. A discrete variable is one that is defined or of interest only for values that differ by some finite amount, usually a constant and often ...
in mathematics, an expression based on the derivative (q.v.) of a function, useful for approximating certain values of the function. The derivative of a function at the point x0, written as f'(x0), is defined as the limit as Deltax approaches ...
mathematical statement containing one or more derivatives, that is, terms representing the relationships between the rates of change of continuously varying quantities. Differential equations are very common in science and engineering, other fields of quantitative study. The solution of a ...
in automotive mechanics, gear arrangement that permits power from the engine to be transmitted to a pair of driving wheels, dividing the force equally between them but permitting them to follow paths of different lengths, as when turning a corner ...
branch of mathematics that studies the geometry of curves, surfaces, and manifolds (the higher-dimensional analogs of surfaces). The discipline owes its name to its use of ideas and techniques from differential calculus, though the modern subject often uses algebraic and ...
branch of psychology that deals with individual and group differences in behaviour. Charles Darwin's studies of the survival capabilities of different species and Sir Francis Galton's researches on individual visual and auditory skills, as well as more recent experiments, have ...
in analytical chemistry, a technique for identifying and quantitatively analyzing the chemical composition of substances by observing the thermal behaviour of a sample as it is heated. The technique is based on the fact that as a substance is heated, ...
in mathematics, process of finding the derivative (q.v.), or rate of change, of a function. In contrast to the abstract nature of the theory behind it, the practical technique of differentiation can be carried out by purely algebraic manipulations, using ...
a device or set of components for performing the mathematical operation of differentiation-i.e., supplying an output proportional to the derivative of the input with respect to one or more variables. The many common examples of mechanical differentiators in which a ...
