Ilumquh \i-Tum-ku\ Arabian god of the moon. Deemed superior to the gods associated with the sun and Venus, he was the protector of cities and patron god of the capital cities of southern Arabia. Pilgrimages were made to his temples, where worshipers often sought divine guidance from oracles. He had many different names and epithets, including Wadd, Amm, and Sin.
image processing Set of computational techniques for analyzing, enhancing, compressing, and reconstructing images. Its main components are importing, in which an image is captured through scanning or digital photography; analysis and manipulation of the image, accomplished using various specialized software applications; and output (e.g., to a printer or monitor). Image processing has extensive applications in many areas,
including astronomy, medicine, industrial robotics, and remote sensing by satellites. See also pattern recognition.
imaginary number Any number of the form bi where b is a real number, i is the square root of -1, and b is not zero. See also complex NUMBER.
Imagism Vim-i-Jiz-omX Movement in U.S. and English poetry charac¬ terized by the use of concrete language and figures of speech, modern subject matter, metrical freedom, and avoidance of romantic or mystical themes. It grew out of the Symbolist movement and was initially led by Ezra Pound, who, inspired by the criticism of T. E. Hulme (1883-1917), for¬ mulated its credo c. 1912; Hilda Doolittle was also among the founders. Around 1914 Amy Lowell largely took over leadership of the group. Imag¬ ism influenced the works of Conrad Aiken, T. S. Eliot, Marianne Moore, D. H. Lawrence, Wallace Stevens, and others.
imam \i-'mam\ Head of the Muslim community. In Sunnite Islam the imam was identical with the caliph, designating the political successor of Muhammad. The Sunnites held the imam to be a man capable of error but deserving obedience provided he maintained the ordinances of Islam. In ShTite Islam the imam became a figure of absolute religious authority, possessed of unique insights into the Qur’an and divinely appointed and preserved from sin. With the historical disappearance of the last imam, there arose a belief in the hidden imam, who is identified with the mahdi. The term imam is also given to Muslims who lead prayers in mosques and has been used as an honorary title.
Imam Bondjol Vbon-joL (b. 1772, Kampung Tandjung Bunga, Sumatra—d. Nov. 6, 1864, Manado, Celebes) Leader in a religious war that divided the Minangkabau people of Sumatra. A convert to reformist Wahhabi Islam, known in Sumatra as the Padri sect, he established the fortified community of Bondjol, from which he took his name, as a cen¬ tre from which to wage holy war. The secular government called on the Dutch to help, but the Dutch were preoccupied with the Java War (1825— 30), and Imam Bondjol’s forces expanded the area under their control. The Dutch eventually turned their attention to the Padris and defeated them; Imam Bondjol surrendered (1837), and the Minangkabau territory was added to the Dutch colonial holdings.
imamis See Ithna Ashariya
Imeni Ismail Samani Peak formerly Communism Peak or Stalin Peak Peak, western Pamirs, northeastern Tajikistan. Located in the Akademiya Nauk Range, it rises to 24,590 ft (7,495 m) and is the highest point in Tajikistan and in the range. It was first climbed by a Rus¬ sian team in 1933.
IMF See International Monetary Fund
Imhotep \im-'ho-,tep\ Greek Imouthes (fl. 27th century bc, Memphis, Egypt) Egyptian sage and astrologer, later worshiped as the god of medi¬ cine. In Greece he was identified with Asclepius. Imhotep was chief min¬ ister to the Egyptian king Djoser and is remembered as a skilled physician as well as the architect of the step-pyramid at Saqqara in Memphis. Dei¬ fied around the time of the Persian conquest in 525 bc, he was said to be the son of Ptah and the war goddess Sekhmet. The cult of Imhotep reached its zenith in Greco-Roman times, when sick people slept in his temples with the hope that the god would reveal remedies to them in dreams.
Immaculate Conception In Roman Catholicism, the dogma that Mary was not tainted by original sin. Early exponents included St. Justin Mar¬ tyr and St. Irenaeus; St. Bonaventure and St. Thomas Aquinas were among those who opposed it. In 1439 the Council of Basel stated that the belief was in accordance with Catholic faith, and in 1709 Pope Clement XI made the feast of the Immaculate Conception a holy day of obligation. In 1854 Pius IX issued a papal bull making it official church dogma. See also Vir¬ gin Birth.
immune system Cells, cell products, organs, and structures of the body involved in the detection and destruction of foreign invaders, such as bacteria, viruses, and cancer cells. Immunity is based on the system’s ability to launch a defense against such invaders. For the system to func¬ tion properly, it must be able to distinguish between the material of its own body (self) and material that originates outside of it (nonself). Fail¬ ure to make this distinction can result in autoimmune diseases. An exagger¬ ated or inappropriate response by the immune system to nonharmful substances (e.g., pollen, animal dander) can result in allergies. The sys¬ tem’s principal cells include lymphocytes that recognize antigens and
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930 I immunity ► impala
related accessory cells (such as phagocytic macrophages, which engulf and destroy foreign material). Lymphocytes arise in the bone marrow from stem cells, with T lymphocytes (T cells) migrating to the thymus to mature and B lymphocytes (B cells) maturing in the bone marrow. Mature lym¬ phocytes enter the bloodstream, and many become lodged, along with accessory cells, in various body tissues, including the spleen, lymph nodes, tonsils, and intestinal lining. Organs or tissues containing such concen¬ trations are termed lymphoid. Within these organs and tissues the lym¬ phocytes are confined within a delicate network of connective tissue that channels them so they come into contact with antigens. T cells and B cells can mature and multiply further in lymphoid tissue when suitably stimu¬ lated. Fluid (lymph) draining from lymphoid tissues is conveyed to the blood through lymphatic vessels. Lymph nodes distributed along these vessels filter the lymph, exposing macrophages and lymphocytes con¬ tained within to any antigen present. The spleen plays a similar role, sam¬ pling the blood for the presence of antigens. The capability of lymphocytes to pass between lymphoid tissue, the blood, and lymph is an important element in the system’s functioning. See also immunodeficiency; IMMUNOLOGY.
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Acquired immunity depends on the activities of T and B lymphocytes (T and B cells). One part of acquired immunity, humoral immunity, involves the production of anti¬ bodies by B cells. The other part, cell-mediated immunity, involves the actions of T cells. When an antigen (such as a bacterium) enters the body, it is attacked and engulfed by macrophages, which process and display parts of it on their cell sur¬ face. A helper T cell, recognizing the antigen displayed, initiates maturation and proliferation of other T cells. Cytotoxic (killer) T cells develop and attack foreign and infected cells. B cells stimulated by the presence of antigen are activated by helper T cells to divide and form antibody-producing cells (plasma cells). Released antibody binds to antigen, marking the cell for destruction. Helper T cells also induce the development of memory T and B cells needed to mount future immune responses on reinfection with the same pathogen.