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calcite ... Calepino, Ambrogio

calcite the most common form of natural calcium carbonate (CaCO3), a widely distributed mineral known for the beautiful development and great variety of its crystals. It is polymorphous (same chemical formula but different crystal structure) with the minerals aragonite and vaterite and with several forms that apparently exist only under rather ... calcite compensation depth in oceanography, the depth at which the rate of carbonate accumulation equals the rate of carbonate dissolution. The input of carbonate to the ocean is through rivers and deep-sea hydrothermal vents. The CCD intersects the flanks of the world's oceanic ridges, and as a result these are mostly blanketed by ... calcitonin a protein hormone secreted in humans and other mammals by parafollicular cells (C cells) in the thyroid gland and secreted in birds, fishes, and other nonmammalian vertebrates by cells of the glandular ultimobranchial bodies. calcium chemical element, one of the alkaline-earth metals of Group 2 (IIa) of the periodic table. It is the most abundant metallic element in the human body and the fifth most abundant element in Earth's crust. calcium deficiency condition in which calcium is insufficient or is not utilized properly. Calcium is the mineral that is most likely to be deficient in the average diet. It is the chief supportive element in bones and teeth. Calcium salts make up about 70 percent of bone by weight and give that ... calcrete calcium-rich duricrust, a hardened layer in or on a soil. It is formed on calcareous materials as a result of climatic fluctuations in arid and semiarid regions. Calcite is dissolved in groundwater and, under drying conditions, is precipitated as the water evaporates at the surface. Rainwater saturated with carbon dioxide ... Calculating Clock the earliest known calculator, built in 1623 by the German astronomer and mathematician Wilhelm Schickard. He described it in a letter to his friend the astronomer Johannes Kepler, and in 1624 he wrote again to explain that a machine that he had commissioned to be built for Kepler was, apparently ... calculator machine for automatically performing arithmetical operations and certain mathematical functions. Modern calculators are descendants of a digital arithmetic machine devised by Blaise Pascal in 1642. Later in the 17th century, Gottfried Wilhelm Leibniz created a more advanced machine, and, especially in the late 19th century, inventors produced calculating machines that ... calculus branch of mathematics concerned with the calculation of instantaneous rates of change (differential calculus) and the summation of infinitely many small factors to determine some whole (integral calculus). Two mathematicians, Isaac Newton of England and Gottfried Wilhelm Leibniz of Germany, share credit for having independently developed the calculus in the ... Calculus of Variations Pioneers of calculus, such as Pierre de Fermat and Gottfried Wilhelm Leibniz, saw that the derivative gave a way to find maxima (maximum values) and minima (minimum values) of a function f(x) of a real variable x, since f'(x)=0 at all such points. However, real variable optimization problems were not ... calculus of variations branch of mathematics concerned with the problem of finding a function for which the value of a certain integral is either the largest or the smallest possible. Many problems of this kind are easy to state, but their solutions commonly involve difficult procedures of the differential calculus and differential equations. Calcutta, University of state-controlled institution of higher learning founded by the British in India in 1857. Modeled on the University of London, Calcutta was originally a purely affiliating university that offered no actual instruction but was the examining and degree-granting authority for colleges scattered over most of northern India. Since 1904 it has ... Caldas departamento, west-central Colombia. It is situated in the Cordillera Central of the Andes Mountains and is bounded by the Magdalena River on the east and the Cauca River on the west. Penetrated by Spaniards early in the 16th century, Caldas gained prominence as a gold-mining region. It was created a ... Caldecott Medal annual prize awarded "to the artist of the most distinguished American picture book for children." It was established in 1938 by Frederic G. Melcher, chairman of the board of the R.R. Bowker Publishing Company, and named for the 19th-century English illustrator Randolph Caldecott. It is presented at the annual conference ... Caldecott, Randolph English artist chiefly known for the gently satirical drawings and coloured book illustrations that won him great popularity. Calder, Alexander American sculptor best known as the originator of the mobile, a type of kinetic sculpture the delicately balanced or suspended components of which move in response to motor power or air currents; by contrast, Calder's stationary sculptures are called stabiles. He also produced numerous wire figures, notably for a vast ... caldera large bowl-shaped volcanic depression more than one kilometre in diameter and rimmed by infacing scarps. Calderas usually, if not always, form by the collapse of the top of a volcanic cone or group of cones because of removal of the support formerly furnished by an underlying body of magma (molten ... Calderdale westernmost metropolitan borough, metropolitan county of West Yorkshire, England. The metropolitan borough is part of the historic county of Yorkshire, except for a small area west of Todmorden that belongs to the historic county of Lancashire. The bleak gritstone Pennine moorlands, with scattered sheep farms and reservoirs, rise to an ... Calderon de la Barca, Pedro dramatist and poet who succeeded Lope de Vega as the greatest Spanish playwright of the Golden Age. Among his best-known secular dramas are El medico de su honra (1635; The Surgeon of His Honour), La vida es sueno (1635; Life Is a Dream), El alcalde de Zalamea (c. 1640; The ... Calderon, Felipe politician who served as president of Mexico (2006-12). Calderon, Rodrigo, conde de Oliva, marques de Siete Iglesias Spanish royal favourite who enjoyed considerable authority during the ascendancy of Francisco Gomez, duque de Lerma in the reign of Philip III. Calderon, Sila Maria Puerto Rican politician and governor of Puerto Rico (2001-05), the first woman to hold the post. Calderone, Mary Steichen American physician and writer who, as cofounder and head of the Sexuality Information and Education Council of the United States (SIECUS), crusaded for the inclusion of responsible sex education in the public-school curriculum. Calderwood, David Scottish Presbyterian minister and historian of the Church of Scotland. Caldey Island island in Carmarthen Bay of the Bristol Channel, Pembrokeshire (Sir Benfro) county, Wales. It lies 2.3 miles (3.7 km) south of the port of Tenby. The island is 1.5 miles (2.4 km) long and 1 mile (1.6 km) across at its widest. From at least the 6th century, when it ... Caldicott, Helen Broinowski Australian-born American physician and activist whose advocacy focused on the medical and environmental hazards of nuclear weapons. Caldwell city, seat (1892) of Canyon county, southwestern Idaho, U.S., on the Boise River. It originated (1883) as a construction camp for the Oregon Short Line Railroad and was named for Alexander Caldwell, the railroad president. Lake Lowell (formerly Deer Flat Reservoir), a unit in the Boise Irrigation Project, is to ... Caldwell borough (township), Essex county, northeastern New Jersey, U.S. It lies 9 miles (14 km) northwest of Newark. Settled in the 1780s and incorporated in 1892, it is known as the birthplace of Grover Cleveland, the only American president born (1837) in New Jersey. His birthplace, a clapboarded Presbyterian parsonage, is ... Caldwell, Erskine American author whose unadorned novels and stories about the rural poor of the American South mix violence and sex in grotesque tragicomedy. His works achieved a worldwide readership and were particularly esteemed in France and the Soviet Union. Caldwell, Sarah American opera conductor, producer, and impresario, noted for her innovative productions of challenging and difficult works. Caldwell, Taylor highly popular American novelist, known for her family sagas and historical fiction. Caleb in the Old Testament, one of the spies sent by Moses from Kadesh in southern Palestine to spy out the land of Canaan. Only Caleb and Joshua advised the Hebrews to proceed immediately to take the land; for his faith Caleb was rewarded with the promise that he and his ... Caledon River tributary of the Orange River in southeastern Africa. It rises in the Drakensberg, on the Lesotho-South Africa border, and flows generally southwest, forming most of the boundary between Lesotho and Free State province, South Africa. Maseru, capital of Lesotho, lies on the river. The Caledon leaves Lesotho near Wepener, Free ... Caledonia historical area of north Britain beyond Roman control, roughly corresponding to modern Scotland. It was inhabited by the tribe of Caledones (Calidones). The Romans first invaded the district under Agricola about AD 80 and later won a decisive battle at Mons Graupius. They established a legionary fortress at Inchtuthil (near ... Caledonia county, northeastern Vermont, U.S., bounded on the southeast by New Hampshire, the Connecticut River constituting the border. Piedmont terrain occupies most of the county except the northeastern corner, which lies in a highland region. The principal waterways are the Passumpsic, Lamoille, Wells, and Moose rivers, as well as Lake Groton, ... Caledonian Canal waterway running southwest to northeast across the Glen Mor fault of northern Scotland and connecting the North Sea with the North Atlantic Ocean. In 1773 James Watt was employed by the British government to make a survey for such a canal, which would link together a chain of freshwater lakes ... Caledonian orogenic belt range of mountains situated in northwestern Europe, developed as a result of the opening, closure, and destruction of the Iapetus Ocean in the period from the start of the Cambrian (542 million years ago) to the end of the Silurian (about 416 million years ago). The final collision was between ... calendar any system for dividing time over extended periods, such as days, months, or years, and arranging such divisions in a definite order. A calendar is convenient for regulating civil life and religious observances and for historical and scientific purposes. The word is derived from the Latin calendarium, meaning "interest register" ... Calendar of 1993: Year in Review 1994 Calendar of 1994: Year in Review 1995 Calendar of 1995: Year in Review 1996 Calendar of 1996: Year in Review 1997 Calendar of 1997: Year in Review 1998 Calendar of 1998: Year in Review 1999 Calendar of 2000: Year in Review 2001 Calendar of 2001: Year in Review 2002 Calendar of 2002: Year in Review 2003 Calendar of 2003: Year in Review 2004 calendering process of smoothing and compressing a material (notably paper) during production by passing a single continuous sheet through a number of pairs of heated rolls. The rolls in combination are called calenders. Calender rolls are constructed of steel with a hardened surface, or steel covered with fibre; in paper production, ... calendula Any herbaceous plant of the small genus Calendula, in the Asteraceae family, found in temperate regions. Calendulas produce yellow-rayed flowers. The pot marigold (C. officinalis) is grown especially for ornamental purposes. Calepino, Ambrogio one of the earliest Italian lexicographers, from whose name came the once-common Italian word calepino and English word calepin, for "dictionary." He became an Augustinian monk and compiled a dictionary of Latin and several other languages, published at Reggio nell'Emilia (1502). Later other languages were added until, in an edition ...