mental disorder Any illness with a psychological origin, manifested either in symptoms of emotional distress or in abnormal behaviour. Most mental disorders can be broadly classified as either psychoses or neuro¬ ses (see neurosis; psychosis). Psychoses (e.g., schizophrenia and bipolar dis¬ order) are major mental illnesses characterized by severe symptoms such as delusions, hallucinations, and an inability to evaluate reality in an objec¬ tive manner. Neuroses are less severe and more treatable illnesses, includ¬ ing DEPRESSION, ANXIETY, and PARANOIA as well as OBSESSIVE-COMPULSIVE DISORDERS
and post-traumatic stress disorders. Some mental disorders, such as Alzhe¬ imer disease, are clearly caused by organic disease of the brain, but the causes of most others are either unknown or not yet verified. Schizophre¬ nia appears to be partly caused by inherited genetic factors. Some mood disorders, such as mania and depression, may be caused by imbalances of certain neurotransmitters in the brain; they are treatable by drugs that act to correct these imbalances (see psychopharmacology). Neuroses often appear to be caused by psychological factors such as emotional depriva¬ tion, frustration, or abuse during childhood, and they may be treated through psychotherapy. Certain neuroses, particularly the anxiety disorders known as phobias, may represent maladaptive responses built up into the human equivalent of conditioned reflexes.
mental hygiene Science of maintaining mental health and preventing disorders to help people function at their full mental potential. It includes all measures taken to promote and preserve mental health: rehabilitation of the mentally disturbed, prevention of mental illness, and aid in coping in a stressful world. Community mental health acknowledges the relation
between mental health, population pressures, and social unrest. It also deals with social problems, from drug addiction to suicide prevention. Treatment of the mentally ill through the ages has ranged from neglect, ill treatment, and isolation to active treatment and integration into the community, often in response to crusading reformers. Prevention of men¬ tal illness includes prenatal care, child-abuse awareness programs, and counseling for crime victims. Treatment includes psychotherapy, drug therapy, and support groups. One of the most important efforts is public education to combat the stigma still attached to mental illness and encour¬ age those affected to seek treatment.
mental retardation Subaverage intellectual ability that is present from birth or infancy and is manifested by abnormal development, learn¬ ing difficulties, and problems in social adjustment. A standardized intel¬ ligence test is a common method of identification. Individuals with IQ scores of 53-70 are usually classified as mildly retarded and are able to learn academic and pre-vocational skills with some special education. Those with scores of 36-52 are classified as moderately retarded and are able to learn functional academic skills and undertake semiskilled work under supervised conditions. Those in the severe (21-35) and profound (below 21) ranges require progressively more supervision or full-time custodial care. Mental retardation can be caused by genetic disorders (such as Down's syndrome), infectious diseases (such as meningitis), meta¬ bolic disorders, poisoning from lead, radiation, or other toxic agents, inju¬ ries to the head, and malnutrition.
menthol Crystalline organic compound of the isoprenoid family. It has a strong, minty, cooling odour and taste. It is obtained from the oil of the Japanese mint or made synthetically and is used in cigarettes, cosmetics, chest rubs, cough drops, toothpastes, and flavourings. Of its two optical isomers (see optical activity; isomerism), only 1-menthol has the desirable cooling effect.
Menuhin Vmen-yo-wonX, Yehudi, Lord Menuhin of Stoke d'Abernon (b. April 22, 1916, New York, N.Y., U.S.—d. March 12, 1999, Berlin, Ger.) U.S.-born British violinist and conductor. Raised in San Francisco, he made his debut at age seven. In 1927 he studied with George Enescu (1881-1955) in Paris; he returned to perform to tremen¬ dous acclaim in New York the same year and went on to astound audi¬ ences worldwide with his precocious depth and proficiency. From 1959 he lived in London, but he did not become a British citizen until 1985. He directed the Bath Festival (1958-68) and the Gstaad Festival from 1956. In 1958 he founded his own chamber orchestra. Often accompa¬ nied by his pianist sister, Hephzibah (1920-81), he also made recordings with the sitarist Ravi Shankar.
Menzies Vmen- I zez\, Sir Robert (Gordon) (b. Dec. 20, 1894, Jeparit, Victoria. Austl.—d. May 16, 1978, Melbourne) Australian states¬ man and prime minister (1939-41, 1949-66). A successful lawyer, he served as Australia’s attorney general (1934-39). Leader of the United Australia Party, he served as prime minister (1939—41). He organized the Liberal Party in 1944 and again became premier in 1949. In the 1950s he fostered industrial growth in Australia and immigration from Europe. He strengthened military ties with the U.S. and encouraged the ANZUS Pact and Australia’s membership in the Southeast Asia Treaty Organization. He retired in 1966 after the longest ministry in Australian history.
mer \'mer\ Among the Cheremi and Udmurt peoples of Russia, a sacred grove where people of several villages gathered periodically to hold reli¬ gious festivals and sacrifice animals to nature gods. The groves where the mer festivals were held were not fenced (see lud) and did not have per¬ manent altars. Mer festivals were infrequent; five years or more might elapse between them.
mercantile agency Specialized organization that supplies informa¬ tion on the creditworthiness and financial strength of business firms. The first such agency, the Mercantile Agency, was founded in New York City in 1841. It provided information to businesses that were expanding nation¬ ally and were unable to assess the credit history of prospective custom¬ ers in distant locations. It changed its name to R. G. Dun & Co. after 1859 and merged with the Bradstreet Co. in 1933 to form Dun & Brad- street, Inc., the best-known mercantile agency. Mercantile agencies may provide information on all types of business firms or may limit their investigations to firms in a particular line of trade or a particular region. Most agencies provide both general and special reports. General reports, issued periodically on all firms investigated by the agency, assign a rat-
L_
M
N
© 2006 Encyclopaedia Britannica, Inc.
1238 I mercantile law ► Mercury
L_
N
ing to the firm’s financial statement and creditworthiness. Special reports containing more detailed information are issued to clients of the agency on request. See also credit bureau.
mercantile law See business law
mercantilism Economic theory and policy influential in Europe from the 16th to the 18th century that called for government regulation of a nation’s economy in order to increase its power at the expense of rival nations. Though the theory existed earlier, the term was not coined until the 18th century; it was given currency by Adam Smith in his Wealth of Nations (1776). Mercantilism’s emphasis on the importance of gold and silver holdings as a sign of a nation’s wealth and power led to policies designed to obtain precious metals through trade by ensuring “favourable” trade balances (see balance of trade), meaning an excess of exports over imports, especially if a nation did not possess mines or have access to them. In a favourable trade balance, payments for the goods or services had to be made with gold or silver. Colonial possessions were to serve as markets for exports and as suppliers of raw materials to the mother coun¬ try, a policy that created conflict between the European colonial powers and their colonies, in particular fanning resentment of Britain in the North American colonies and helping bring about the American Revolution. Mercantilism favoured a large population to supply labourers, purchasers of goods, and soldiers. Thrift and saving were emphasized as virtues because they made possible the creation of capital. Mercantilism provided a favourable climate for the early development of capitalism but was later severely criticized, especially by advocates of laissez-faire, who argued that all trade was beneficial and that strict government controls were counter¬ productive.