or pineal body

Endocrine gland in the brain that produces melatonin. It is large in children and begins to shrink at puberty. The gland may play a significant role in sexual maturation, circadian rhythm and sleep induction, and seasonal affective disorder and depression. In animals it is known to play a major role in sexual development, hibernation, and seasonal breeding.

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or graft

Partial or complete organ or other body part removed from one site and attached at another. It may come from the same or a different person or an animal. One from the same person—most often a skin graft—is not rejected. Transplants from another person or, especially, an animal are rejected unless they are unusually compatible or have no blood vessels (e.g., the cornea), or if the recipient's immune reaction is suppressed by lifelong drug treatment. Transplanted tissues must match (by blood tests) more closely than blood transfusions. Monoclonal antibodies targeting the cells that cause rejection hold great promise. Tests are now under way with monoclonal antibodies that react with antigens present only on T cells that are participating in rejection, sparing the rest. Rejection matters less in skin grafts, which may need to last only weeks, and bone grafts, whose structure remains after the cells die. In bone-marrow transplants, the donor's marrow cells may attack the recipient's tissues, often fatally. Lung transplants have greater chance of success as part of a heart-and-lung transplant. Seealso heart transplant, kidney transplant.

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or renal transplant

Replacement of a diseased or damaged kidney with one from a living relative or a legally dead donor. The former's tissue type is more likely to match, reducing the chance of rejection; but removal puts the donor at risk, and a kidney from a dead donor is more likely to be available. The new kidney is implanted and its blood vessels and ureter sewn in place. A near-normal life may be resumed within two months, but the drugs that prevent rejection leave the patient vulnerable to infection. Seealso transplant.

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Procedure to remove a diseased heart and replace it with a healthy one from a legally dead donor. The first was performed in 1967 by Christiaan Barnard. The diseased heart is removed (except for some atrial tissue to preserve nerve connections to the natural pacemaker). The new heart is put in place and connected to the recipient's blood vessels. Patients and donors are matched for tissue type, but the patient's immune system must still be suppressed to prevent rejection (see immunosuppression). A successful transplant can enable the recipient to have an active life for many years.

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Keyboard instrument in which pressurized air produces notes by means of a series of tuned pipes. The simplest organs consist of a single rank of pipes, each corresponding to a single key. They are arranged over a wind chest connected to the keys by a set of valves and fed with a supply of air by electrically or mechanically activated bellows. By pulling out knobs, called stops, the player engages new ranks of pipes. Two distinct types of pipes are used: flue pipes (both open and stopped) produce sound by directing air against the edge of an opening in the pipe, whereas reed pipes sound by means of a thin metal tongue inside the pipe that vibrates against a fixed projection next to it. A large organ may have five or more banked keyboards, or manuals, each of which controls a distinctive group of pipes. Most organs also have pedalboards played with the feet. A large organ's pipes may vary in length from about 1 in. to 32 ft (2.5 cm to 10 m), resulting in a huge nine-octave range. The earliest organ (circa 250 BC) was the Greek hydraulis, in which the wind was regulated by water pressure. The bellows-fed organ appeared about the 7th century AD. The organ became firmly associated with the church by the 10th century. As organs became widespread, different regions pursued different modes of construction and sought different tonal ideals. The Baroque German organ is ideally suited to polyphony, while the French taste for variety of timbres eventuated in Aristide Cavaillé-Coll's vast “orchestral” organs. Seealso harmonium.

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National monument, southwestern Arizona, U.S., at the Mexican border. It was established in 1937. With an area of 330,689 acres (133,929 hectares), it preserves segments of the mountainous Sonoran Desert and is named for the organ-pipe cactus. Wildlife includes Gila monsters, antelope, coyotes, and a variety of birds.

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(born Jan. 1, 1879, London, Eng.—died June 7, 1970, Coventry, Warwickshire) British writer. Forster was born into an upper-middle-class family. He attended the University of Cambridge and from roughly 1907 was a member of the informal Bloomsbury group. His early works include Where Angels Fear to Tread (1905), The Longest Journey (1907), A Room with a View (1908), and his first major success, Howards End (1910), novels that show his acute observation of middle-class life and its values. After periods in India and Alexandria, he wrote his finest novel, A Passage to India (1924), examining the failure of human understanding between ethnic and social groups under British rule. Maurice, a novel with a homosexual theme written in 1913, appeared posthumously. Aspects of the Novel (1927) is a classic discussion of aesthetics and the creative process. Awarded an honorary fellowship in 1946 at Cambridge, he lived there until his death.

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A melodeon (also known as a cabinet organ or American organ) is a type of 19th century reed organ with a foot-operated vacuum bellows, and a piano keyboard. It differs from the related harmonium, which uses a pressure bellows. Melodeons were manufactured in the United states from 1846 until the Civil War era. While it was sometimes used as a substitute for the pipe organ in small churches, it was primarily used in domestic settings.

In Ireland, the word is found in the commonly used phrase "cat melodeon". This simply means that something is awful. For example, if it is raining, one might say that the weather is cat melodeon.

See also

• Melodeon

Sources

• The Ultimate Encyclopedia of Musical Instruments, ISBN 1858681855, p140