multinational corporation Any corporation registered and operat¬ ing in more than one country at a time, usually with its headquarters in a single country. A firm’s advantages in establishing itself multinationally include both vertical and horizontal economies of scale (reductions in cost that result from an expanded level of output). Critics usually regard the multinational corporation as destructive of local economies abroad and as prone to monopolistic practices. See also conglomerate.
multiple birth Birth of more than one child from one pregnancy. Twins are most common, born in 1 of about every 80 pregnancies. Identical twins develop from a single fertilized egg, which splits into two genetically identical embryos (though physical traits may be modified during their development); they occur randomly but are more likely in older mothers. Incomplete or late division results in conjoined twins. Fraternal twins develop from two eggs fertilized by two sperm and are no more geneti¬ cally alike than are other siblings. Most common among persons of Afri¬ can ancestry and least common among those of Asian ancestry, fraternal twins seem to run in families. Repeated twinning produces triplets, qua¬ druplets, and so on; these multiples may be identical, fraternal, or a com¬ bination. The use of fertility drugs has increased the number of high-order multiple births. Medical and psychological “twin studies” compare fra¬ ternal and identical twins to learn about genetic influences on various characteristics and diseases.
multiple integral In calculus, the integral of a function of more than one variable. As the integral of a function of one variable over an inter¬ val results in an area, the double integral of a function of two variables calculated over a region results in a volume. Functions of three variables have triple integrals, and so on. Like the single integral, such construc¬ tions are useful in calculating the net change in a function that results from changes in its input values.
multiple personality disorder See dissociative identity disorder
multiple sclerosis \skl3-'ro-s9s\ Disease of the brain and spinal cord in which gradual, patchy destruction of the myelin sheath of nerve fibres
Brian Mulroney, 1993.
RICK FRIEDMAN/BLACK STAR
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multiplexing ► Munch I 1309
causes interruption or disordered transmission of nerve impulses. Its early symptoms may include limb weakness or trembling, visual problems, sensory disturbances, unsteady walking, and defective bladder control, which come and go irregularly. Attacks grow more severe, and some symptoms become permanent, sometimes with eventual complete paraly¬ sis. Average survival from onset is about 25 years, but a rare acute form progresses over months. The cause remains uncertain and treatment unsat¬ isfactory. Corticosteroids may ease symptoms. MS may be due to a delayed immune response that attacks the myelin sheaths; suggested causes include various common viruses. Dietary causes have also been suggested.
multiplexing Process of transmitting multiple (but separate) signals simultaneously over a single channel or line. Because the signals are sent in one complex transmission, the receiving end has to separate the indi¬ vidual signals. The two main types of multiplexing methods are time- division multiplexing (TDM) and frequency-division multiplexing (FDM). In TDM (typically used for digital signals) a device is given a specific time slot during which it can use the channel. In FDM (typically used for analog signals) the channel is subdivided into subchannels, each with a different frequency width that is assigned to a specific signal. Optical-fibre networks can use DWDM (dense wavelength-division mul¬ tiplexing), in which different data signals are sent in different wavelengths of light in the fibre-optic medium.
multiplier In economics, a numerical coefficient showing the effect of a change in one economic variable on another. One macroeconomic mul¬ tiplier, the autonomous expenditures multiplier, relates the impact of a change in total national investment on the nation’s total income; it equals the ratio of the change in total income to the change in investment. If, for example, the total investment in an economy is increased by $1 million, a chain reaction of increases in consumption is set off. Producers of raw materials used in the investment projects and workers employed in the projects gain $1 million in income. If they spend on average three-fifths of that income, $600,000 will be added to the incomes of others. The makers of the goods they buy will in turn spend three-fifths of their new income on consumption. The process continues such that the amount by which total income increases may be computed by an algebraic formula. In this case, the multiplier equals 1/(1 - 3/5), or 2.5. This means that a $1 million increase in investment creates a $2.5 million increase in total income. Other multipliers include the money multiplier, which measures money creation resulting from a change in monetary policy; the govern¬ ment spending multiplier, which measures the change in national income resulting from changes in fiscal policy; and the tax multiplier, which mea¬ sures the changes in national income resulting from a change in taxes. The concept of the multiplier process was popularized in the 1930s by John Maynard Keynes as a means of measuring the effect of government spending.
multiprocessing Mode of computer operation in which two or more processors (see CPU) are connected and are active at the same time. In such a system, each processor is executing a different program or set of instructions, thus increasing computation speed over a system that has only one processor (which means only one program can be executed at a time). Because the processors must sometimes access the same resource (as when two processors must write to the same disk), a system program called the task manager has to coordinate the processors’ activities.
multitasking Mode of computer operation in which the computer works on multiple tasks at the same time. A task is a computer program (or part of a program) that can be run as a separate entity. On a single-processor system, the CPU can perform preemptive (also called time slicing or time sharing) multitasking, where it executes part of one program, then switches to another program, and then returns to the first one. On multi¬ processing systems, each processor can handle a separate task.
Mumbai Vmom-.bl \ formerly Bombay City (pop., 2001 prelim.: city, 11,914,398; metro, area, 16,368,084), capital of Maharashtra state, west¬ ern India. Located partly on Mumbai Island, it is flanked by Mumbai Har¬ bour and the Arabian Sea. It is India’s principal port on that sea and one of the largest and most densely populated cities in the world. The town was acquired by the Portuguese in 1534. It was ceded to the English as part of the dowry of Catherine of Braganza, who married Charles II in 1661. Granted to the British East India Company in 1668, it became the compa¬ ny’s headquarters in 1672, and in 1708 it was made the centre of British authority in India. After the opening of the Suez Canal in 1869, Mumbai
grew to be the largest distributing entrepot in India. It remains India’s economic hub and the heart of financial and commercial activity, its cul¬ tural and education centre, and headquarters of its film industry.
Mumford, Lewis (b. Oct. 19, 1895, Flushing, N.Y., U.S.—d. Jan. 26, 1990, Amenia, N.Y.) U.S. architectural critic, urban planner, and cultural historian. After studying at the City College of New York and at the New School for Social Research, he taught at various universities and wrote for The New Yorker, The Dial, and other magazines. In works such as Technics and Civilization (1934), The City in History (1961), and The Myth of the Machine (3 vol., 1967-70), Mumford analyzed the effects of technology and urbanization on human societies, criticizing the dehuman¬ izing tendencies of modern technological society and urging that it be brought into harmony with humanistic goals and aspirations. See also URBAN PLANNING.