lysine \'ll-,sen\ One of the essential amino acids, present in many com¬ mon proteins. Its proportion in the proteins of some important food plants (including wheat and com) is so small that populations dependent on these grains as the sole source of dietary protein suffer from lysine deficiency, affecting growth in chil¬ dren and general well-being in adults. It is used in biochemical and nutritional research, in pharmaceuti¬ cals, in fortified foods, and as a nutri¬ tional supplement and feed additive.
Lysippus \ll-'si-p3s\ or Lysippos
(fl. 4th century bc, Sicyon, Greece)
Greek sculptor. He was famous for the new and slender proportions of his figures and for their lifelike naturalism. He reportedly made more than 1,500 works, most in bronze. None survive, but some copies may be reli¬ ably ascribed to him, including Apoxyomenos, a young athlete scraping oil from his skin. Another key work is the colossal Heracles at Sicyon. He made many portrait busts of Alexander the Great from boyhood on; it was said that Alexander would have no other sculptor portray him.
lysogeny Ml-'sa-jo-neX Type of life cycle that takes place in a bacte¬ riophage after it infects certain types of bacteria. The bacteriophage’s genome (entire collection of genes) enters the chromosome of the host bacterium and replicates together with it. No offspring viruses are pro¬ duced; instead, the infecting virus lies dormant within the host’s chro¬ mosome until the host is exposed to certain stimuli, such as ultraviolet light. At that point, the virus genome is removed from the host chromo¬ some and begins to multiply, forming new viruses. Finally, the bacterial host is destroyed (lysed), releasing virus particles into the environment to infect new bacterial cells.
lysosome \H-s3-,som\ Membrane-enclosed organelle found in all eukaryotic cells (see eukaryote) that is responsible for the cell’s digestion of macromolecules, old cell parts, and microorganisms. Lysosomes con¬ tain a wide variety of enzymes that break down macromolecules such as nucleic acids, proteins, and polysaccharides. Many of the products of lysosomal digestion, including amino acids and nucleotides, are recycled back to the cell for use in synthesizing new cellular components.
Apoxyomenos, Roman marble copy of Greek bronze by Lysippus, c. 310 bc; in the Vatican Museum, Rome.
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1156 I Ml6 rifle ► macadamia
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Ml6 rifle or AR-15 Assault rifle adopted as a standard weapon by the U.S. Army in 1967. The M16, designed by Eugene M. Stoner in the 1950s for the ArmaLite Division of Fairchild Engine and Airplane Corp., has both semiautomatic and automatic capabilities. It weighs less than 9 lbs (3.6 kg) when equipped with a 30-round magazine, is 39 in. (99 cm) long, and fires a high-velocity .223-inch (5.56-mm) round. It can be fitted with a 40-mm grenade launcher. The M4 is a compact carbine version of the Ml6. See also Springfield rifle; AK-47.
M31 See Andromeda Galaxy
Ma, Yo-Yo (b. Oct. 7, 1955, Paris, France) French-born U.S. cellist. Born to Chinese parents in France, he made his cello debut at age five. He attended the Juilliard School and then Harvard University. Praised for his extraor¬ dinary technique and rich tone, Ma per¬ formed and recorded the standard cello repertoire and received a large number of commissions from contemporary composers. He is known for his many recordings with the pianist Emanuel Ax (b.
1949), for his collaborations with an unusual range of other musicians and artists, and for his energetic work on behalf of music programs for young people and a variety of international causes. In 1998 he founded the Silk Road Project, an arts organization that explores the historical and current exchange of ideas between Asian and Western cultures.
Ma-fa-mu-ts'o See Mapam Yumco
Ma Yuan or Ma Yuan (b. c. 1160/65,
Qiantang, Zhejiang province—d. 1225)
Chinese landscape painter. Bom into a family of court painters, Ma Yuan began his career under the emperor Xiaozong, became daizhao (“painter- in-attendance”) under Emperor Guangzong, and received the highest honour, the Golden Belt, under Emperor Ningzong. Apart from these facts, little is known about Ma’s life. He occasionally painted flowers and figure subjects, but it was in landscape painting that his genius lay. He executed a number of large landscape screens, all of which are now lost. He also painted tall hanging scrolls depicting steep mountains with streams, waterfalls, and vigorously yet elegantly rendered pine trees. In many of his works, the mountains are pushed to one side, creating a “one comer” composition; between the distant mountains and the foreground rocks, where a scholar may be sitting, lies an expanse of empty space with a suggestion of mist or water. Ma’s style was popular with late Song paint¬ ers, and it is often difficult to distinguish his works from those of his fol¬ lowers. The romantic landscape style of Ma and his contemporary Xia Gui inspired a school of painting that came to be known as the Ma-Xia school, characterized by asymmetrical compositions with simplified ink tones and angular brushstrokes.
maa-alused Vma- , a-lu- l sed\ In Estonian folk religion, mysterious elves living under the earth. These small folk had suitably tiny possessions, and their world was differently oriented from the mortal world above them (up was down and right was left). People came in contact with them either by chance or at the elves’ wish. Legends tell of distraught elves seeking help from humans in cases of difficult childbirth or illness. A human could marry an elf, but such marriages eventually dissolved. In Finland, such elves were called maahiset.
Maasai See Masai
Maastricht \ma-'strikt,\ English Vma-strikt\ Treaty officially Treaty on European Union Agreement that established the European Union (EU) as successor to the European Community. It bestowed EU citizenship on every national of its member states, provided for the introduction of a central banking system and a common currency (see euro), and commit¬ ted the member states to work toward a common foreign and security policy. Signed in 1992, it was ratified and took effect in 1993. See also European Court of Justice, European Parliament, Treaties of Rome.
Ma'at \'ma-,at\ In ancient Egyptian religion, the personification of truth, justice, and the cosmic order. Ma'at was the daughter of Re, the sun god, and she stood at the head of his bark as it traveled through the sky and the underworld. She was also associated with Tfioth, the god of wisdom. The judgment of the dead was believed to be determined by the weigh¬ ing of the heart of the deceased on a scale she balanced. In its abstract
sense, ma'at was the divine order established at creation and reaffirmed at the accession of each new king of Egypt.
Maathai, Wangari (b. April 1, 1940, Nyeri, Kenya) Kenyan politi¬ cian and environmental activist. Maathai was educated in the U.S. and later earned a Ph.D. (1971) at the University of Nairobi, where she then taught veterinary anatomy. In 1977, as a way of conserving land and empowering women, she founded the Green Belt Movement, which recruited women to plant trees in deforested areas; by the early 21st cen¬ tury, it was responsible for the planting of some 30 million trees. Over time the organization also came to include programs in civic and envi¬ ronmental education, advocacy, and job training. Maathai, an outspoken critic of government corruption and sup¬ porter of debt cancellation for poor African countries, was elected to Kenya’s National Assembly in 2002 and later served as assistant minister of environment, natural resources, and wildlife (2003-05). In 2004 she received the Nobel Prize for Peace, becoming the first black African woman to win a Nobel Prize.
Mabinogion \ma-be-'nog-y3n,\ English \,ma- b3-'no-ge-3n\ Collection of 11 medieval Welsh tales based on mythology, folklore, and heroic legends. The tales have multiple authors and are versions of stories told and retold through the cen¬ turies. Among the finest are four stories known as “The Four Branches of the Mabinogi,” written in the late 11th century. Some show Celtic, Norman, and French influence; “Peredur Son of Efrawg,” for example, parallels Chretien de Troyes’s Perceval. Four other tales show little continental influence: “Kulhwch and Olwen,” “Lludd and Llefelys,” “The Dream of Macsen,” and “The Dream of Rhonabwy.”