conjoined twins or Siamese twins Identical twins (see multiple birth) whose embryos did not separate completely. Conjoined twins are physically joined (typically along the trunk or at the front, side, or back of the head) and often share some organs. Symmetrical conjoined twins usually have no birth anomalies except at the areas of fusion and can sometimes be separated by surgery. In asymmetrical conjoined twins, one is fairly well developed, but the other is severely underdeveloped and dependent on the larger twin for nutrition. The underdeveloped twin may have to be surgically separated to save the larger twin. The term origi¬ nally referred to Chang and Eng, bom in 1811 in Siam, who were joined by a ligament from breastbone to navel. Widely exhibited, they married two sisters and fathered several children.
conjugation Interaction of adjacent bonds in a chemical compound having alternating single and double covalent bonds. The conjugated bonds show modified characteristics because of increased electron delo¬ calization and sharing. Conjugation occurs, for example, within a mol¬ ecule containing a chain of carbon atoms linked by alternating single and double bonds. Such a conjugated system often gives rise to substances with intense colours—e.g., the biological pigments called carotenes. Another example is the carboxyl group (see carboxylic acid; functional group), in which the double bond of the carbonyl group (—C=0) is adjacent to the single bond attaching the hydroxyl group (—OH) to the carbon atom.
conjunctivitis Inflammation of the conjunctiva, the delicate lining of the eyelids and the front of the white of the eye. It may be caused by infec¬ tion (when it is commonly called “pink eye”), chemical burn, physical injury, or allergy. Often the cornea is also inflamed (keratoconjunctivitis). Infectious causes include several viruses and bacteria, including those that cause trachoma and gonorrhea, both of which can lead to blindness. Con¬ junctivitis from erythema multiforme, a skin eruption, can also cause blindness.
conjuring Art of entertaining by giving the illusion of performing impossible feats. The conjurer is an actor who combines psychology, manual dexterity, and mechanical aids to effect the desired illusion. The form was established by the medieval era, when traveling conjurers per¬ formed at fairs and in the homes of the nobility. In the 19th-20th centuries, conjuring was performed on stage by magicians such as Jean-Eugene Robert-Houdin, Harry Houdini, and Harry Blackstone. In the late 20th cen¬ tury magicians such as Doug Henning and David Copperfield performed colourful spectacles on television, while the postmodern team Penn and Teller offered a quieter brand of magic that emphasized irony and illusion.
Conkling, Roscoe (b. Oct. 30, 1829, Albany, N.Y., U.S.—d. April 18, 1888, New York, N.Y.) U.S. politician. He was a lawyer, orator, and leader of the Whig Party. He served in the U.S. House of Representatives (1859— 65) and Senate (1867-81). As a leader of the Radical Republicans, he sup¬ ported severe Reconstruction measures. Resisting efforts by Pres. Rutherford B. Hayes to achieve civil service reform, he retained control of New York state’s patronage system. At the 1880 Republican convention, he led the Stalwart faction in supporting former Pres. Ulysses S. Grant. In 1881 he resigned from the Senate in a patronage dispute with Pres. James Garfield.
Connacht or Connaught Vka-,n6t\ Province (pop., 2002 prelim.: 464,050), northwestern Ireland. It is composed of the counties of Galway, Leitrim, Mayo, Roscommon, and Sligo and has an area of 6,611 sq mi (17,122 sq km). An ancient kingdom, Connacht was Christianized by St. Patrick in the 5 th century. Dominated from the 11th century by the O’Connors of Roscommon, it endured an Anglo-Norman invasion in the 12th century.
Connecticut State (pop., 2000: 3,405,565), northeastern U.S. The south¬ ernmost of the New England states, it lies on Long Island Sound and is bor¬ dered by Massachusetts, Rhode Island, and New York. It covers 5,006 sq mi (12,966 sq km); its capital is Hartford. The original inhabitants were Algonquian- speaking Indians. The area was colonized by English Puritans from the Massachusetts Bay Colony during the 1630s. One of the original states of the Union, it was the fifth to ratify the U.S. Constitution. It was an agricultural region until the early 19th century, when textile factories were established, and by 1850 employment in manufacturing exceeded agricul¬ ture; the state remains a manufacturing centre. New Haven, home of Yale University, is one of New England’s largest ports, while Stamford is the headquarters for some of the U.S.’s largest corporations. New London is home to the U.S. Coast Guard Academy. Highways and railways traverse Connecticut and serve the densely settled coastal and Connecticut River val¬ ley regions. The state abounds with historical sites and memorials, and there are numerous state forests and state parks.
Connecticut River River, New England, northeastern U.S. Rising in the Connecticut Lakes in northern New Hampshire, it flows south for a course of 407 mi (655 km) to empty into Long Island Sound. It forms the entire boundary between Vermont and New Hampshire. The lower 60 mi (97 km) of the river are tidal. The longest river in New England, it is extensively developed for hydroelectric power.
connectionism In cognitive science, an approach that proposes to model human information processing in terms of a network of interconnected units operating in parallel. The units are typically classified as input units, hidden units, or output units. Each unit has a default activation level that can vary as a function of the strength of (1) the inputs it receives from other units, (2) the different weights associated with its connections to the other units, and (3) its own bias. Connectionism, unlike traditional com¬ putational models in cognitive science, holds that information is distrib¬ uted throughout entire networks instead of being localized in functionally discrete, semantically interpretable states.
connective tissue Tissue in the body that maintains the form of the body and its organs and provides cohesion and internal support, includ¬ ing BONE, LIGAMENTS, TENDONS, CARTILAGE, ADIPOSE TISSUE, and aponeuroses. Its major components are different kinds of cells and extracellular fibres and ground substance, which varies in consistency from thin gel to rigid struc¬ ture. Various combinations of these elements make up the different kinds of connective tissue. Connective tissue diseases are either genetic disor¬ ders, attacking one of its elements (e.g., Marfan syndrome), or acquired inflammatory or immune-system diseases (e.g., rheumatoid arthritis, OSTEOARTHRITIS, systemic LUPUS ERYTHEMATOSUS, and RHEUMATIC FEVER).
Connelly, Marc(us Cook) (b. Dec. 13, 1890, McKeesport, Pa., U.S.—d. Dec. 21, 1980, New York, N.Y.) U.S. playwright, screenwriter, and director. He covered theatrical news as a journalist in Pittsburgh and New York City. He collaborated with George S. Kaufman on the play Dulcy (1921), which they followed with the comedies To the Ladies (1922) and Beggar on Horseback (1924) and the librettos for the musi¬ cals Helen of Troy, New York (1923) and Be Yourself ( 1924). Connelly went on to write Green Pastures (1930, Pulitzer Prize; film, 1936), his best-known work, and The Farmer Takes a Wife (1934; film, 1935).