attack aircraft: types were the Grumman A-6 Intruder, first flown in 1960; the U.S. Navy’s McDonnell Douglas A-4 Skyhawk, first flown in 1954; and the Ling-Temco-Vought A-7 Corsair, first flown in 1965. The Fairchild Republic A-10 Thunderbolt II (better known as the “Warthog”), a twin-engine aircraft first flown in 1972, became…

attack aircraft: …in 1954; and the Ling-Temco-Vought A-7 Corsair, first flown in 1965. The Fairchild Republic A-10 Thunderbolt II (better known as the “Warthog”), a twin-engine aircraft first flown in 1972, became in the mid-1970s the principal close-support attack aircraft of the U.S. Air Force. Its primary armament is a nose-mounted, seven-barreled,…

Korean music: Court instrumental music: …and Song Chinese music; and a’ak, Confucian ritual music. The instruments used for these ensembles were of Chinese derivation and included sets of tuned stones (in Korean p’yŏn’gyŏng) and bells (p’yŏnjong), mouth organ (saeng), and instruments in all the other eight categories of Chinese classical traditions (e.g., those based on…

Hiroshima Peace Memorial, ruins of a building that was destroyed by an atomic bomb in Hiroshima, Japan, and that is preserved as a memorial to those killed and as a reminder. At 8:15 AM on August 6, 1945, the U.S. B-29 bomber Enola Gay dropped the world’s first atomic bomb used in war on the city

Acheng, former city, central Heilongjiang sheng (province), far northeastern China. In 2006 it was incorporated into the city of Harbin, and it became a southeastern district of that city. It was originally named Ashihe, for the Ashi River that flows through the eastern part of the city. Acheng was

Central Asian arts: Performing arts: dance and theatre: …the Buddhist morality plays, called a-che-lha-mo (“older sister goddess”), were accompanied by a variety of instruments, especially drums and horns. There were large and small drums, short horns with fingering holes, and long horns, particularly the dung-chen (great conch shell) made of brass and extending many feet. The dung-chen with…

philosophy of mind: What it’s like: …theory of thought being considered, A-consciousness is the concept of some material’s being conscious by virtue of its being accessible to various mental processes, particularly introspection, and P-consciousness consists of the qualitative or phenomenal “feel” of things, which may or may not be so accessible. Indeed, the fact that material…

nucleic acid: Chemical structure: In A-DNA, which forms under conditions of high salt concentration and minimal water, the base pairs are tilted and displaced toward the minor groove. Left-handed Z-DNA forms most readily in strands that contain sequences with alternating purines and pyrimidines. DNA can form triple helices when two…

alienation effect, idea central to the dramatic theory of the German dramatist-director Bertolt Brecht. It involves the use of techniques designed to distance the audience from emotional involvement in the play through jolting reminders of the artificiality of the theatrical performance. Examples

Altun Mountains, mountain range in the southern part of the Uygur Autonomous Region of Xinjiang, northwestern China. Branching off from the Kunlun Mountains, the range runs for more than 400 miles (650 km) from southwest to northeast to form the boundary between the Tarim Basin to the north and the

Arkatag Mountains, one of the complex mountain chains that form the Kunlun Mountains in western China. The Arkatag range is in the east-central portion of the Kunluns. Mount Muztag (Muztagh), at its western end, reaches an elevation of 25,338 feet (7,723 metres) and is the tallest peak in both the

Altai Mountains, complex mountain system of Central Asia extending approximately 1,200 miles (2,000 km) in a southeast-northwest direction from the Gobi (Desert) to the West Siberian Plain, through China, Mongolia, Russia, and Kazakhstan. The jagged mountain ridges derive their name from the

thermoreception: Thermoreceptive elements: …predominantly served by thinly myelinated A-fibres that conduct impulses more rapidly than C-fibres. (Thus, a blockade of peripheral nerve conduction by maintained pressure will first interrupt touch, then cold, then finally sensations of warmth and pain, whereas blockade with a local anesthetic agent such as lidocaine will interrupt these sensations…

hand tool: Plumb line, level, and square: The Egyptians used an A-frame, on which a plumb line was suspended from the vertex of the A. When the feet of the A were set on the surface to be checked, if the plumb line bisected the crossbar of the A, the surface was horizontal. The A-frame level…

Nubia: …the world: rulers of the A-Group culture—who were buried in a cemetery at Qustul, excavated by the Oriental Institute of the University of Chicago in the 1960s—adopted symbols of kingship similar to those of contemporary kings of Egypt of the Naqādah II–III period. With the rise of the 1st dynasty…

Miao: … people of west Hunan, the A-Hmao people of Yunnan, and the Hmong people of Guizhou, Sichuan, Guangxi, and Yunnan (see China: People). There are some nine million Miao in China, of whom the Hmong constitute probably one-third, according to the French scholar Jacques Lemoine, writing in the Hmong Studies Journal…

Hmong-Mien languages: Writing systems: …the Pollard script for writing A-Hmao, a Hmongic language spoken in northeast Yunnan and northwest Guizhou provinces. The Pollard system uses primary symbols to represent consonants and smaller secondary symbols to represent vowels. The placement of the vowel symbols in relation to the consonant symbols (above, to the right, and…

Aksu River, river formed near Aksu town in the Uygur Autonomous Region of Xinjiang, China, by headstreams rising in the Tien (Tian) Shan (“Heavenly Mountains”). It flows about 60 miles (100 km) southeastward to form (with the Yarkand and other rivers) the Tarim

Agui was a Chinese general and government official during the middle years of the Qing dynasty in China. The scion of a noble family, Agui directed Chinese military expeditions that quelled uprisings in the western provinces of Sichuan and Gansu. He also conquered Ili and Chinese Turkistan, areas

Alxa Plateau, southernmost portion of the Gobi (desert), occupying about 400,000 square miles (1,000,000 square km) in north-central China. Covering the western portions of the Inner Mongolia Autonomous Region and the northern part of Gansu province, it is bounded by the Huang He (Yellow River) and

artificial life, computer simulation of life, often used to study essential properties of living systems (such as evolution and adaptive behaviour). Artificial life became a recognized discipline in the 1980s, in part through the impetus of American computer scientist Christopher Langton, who named

electronic artificial life game, electronic game genre in which players nurture or control artificial life (A-life) forms. One of the earliest examples is The Game of Life, a cellular automaton created by the English mathematician John Conway in the 1960s. Following a few simple rules, various

Nyainqêntanglha Mountains: …comprises a northern range, the Nganglong (A-ling) Mountains, and a southern range, the Kailas Range, which is much more rugged and heavily glaciated. The highest peak of the Nganglong Mountains is 21,637 feet (6,595 metres) above sea level, and the highest peak in the Kailas Range rises to 22,028 feet…

Xi’an monument: … received the Nestorian Persian monk A-lo-pen in his capital city of Chang’an (modern Xi’an) in 625 and looked with favour upon him and the writings of the “luminous doctrine” (Christianity) he brought with him. By 638 a monastery for this monk and 20 others had been constructed at the expense…

A-mdo, one of three historical regions of Central Asia (the other two being Dbus-Gtsang and Khams) into which Tibet was once divided. Between the 7th and 9th centuries ce, the Tibetan kingdom was extended until it reached the Tarim Basin to the north, China to the east, India and Nepal to the

radio range: The older “A–N” type, dating from 1927, operates at low and medium frequencies. The only equipment needed in the aircraft is an ordinary radio receiver. Each station transmits International Morse Code letters A (· —) and N (— ·) in alternate lobes of its radiation pattern. In…

Abhidharmakosha, encyclopaedic compendium of Abhidharma (scholasticism). Its author, Vasubandhu, who lived in the 4th or 5th century in the northwestern part of India, wrote the work while he was still a monk of the Sarvastivada (Doctrine That All Is Real) order, before he embraced Mahayana, on

Abaoji was a leader of the nomadic Mongol-speaking Khitan tribes who occupied the northern border of China. Elected to a three-year term as great khan of the Khitans, Abaoji refused to resign at the end of his term but made himself king of the Khitan nation. After the collapse in 907 of Tang rule

Issey Miyake: …to maintain its form,” and A-POC (“A Piece of Cloth”), which was made from a single thread with the aid of an industrial knitting or weaving machine programmed by a computer. Miyake had begun experimenting on A-POC more than 10 years earlier with textile expert Dai Fujiwara before launching it…

Chinese literature: May Fourth period: His “A-Q zhengzhuan” (1921; “The True Story of Ah Q”), a damning critique of early 20th-century conservatism in China, is the representative work of the May Fourth period and has become an international classic.

Alex Rodriguez is an American professional baseball player, a noted power hitter who was considered one of the greatest talents in the history of the sport but whose career was in many ways overshadowed by his use of performance-enhancing drugs. Rodriguez and his family moved to his father’s native

ultrasonics: Diagnosis: The A-scan technique uses a single transducer to scan along a line in the body, and the echoes are plotted as a function of time. This technique is used for measuring the distances or sizes of internal organs. The M-scan mode is used to record the…

Mr. T: …in the TV action series The A-Team (1983–87). He is frequently associated with his signature catchphrase, “I pity the fool,” which originated in the film Rocky III (1983).

star: Classification of spectral types: …attaining their maximum intensities in A-type stars, in which the surface temperature is about 9,000 K. Thereafter, these absorption lines gradually fade as the hydrogen becomes ionized.

pacemaker: …patch of conductive tissue, the atrioventricular node, initiating a second discharge along an assembly of conductive fibres called the bundle of His, which induces the contraction of the ventricles. When electrical conduction through the atrioventricular node or bundle of His is interrupted, the condition is called heart block. An artificial…

Dalkon Shield: It was manufactured by the A.H. Robins Company. Sales of the Dalkon Shield were suspended at the request of the Food and Drug Administration (FDA) in October 1974. In 1985, after 9,500 cases had been litigated or settled, the company filed for bankruptcy and set up a $2.3 billion fixed-asset…

Turing Award, annual award given by the Association for Computing Machinery (ACM), a professional computing society founded in 1947, to one or more individuals “selected for contributions of a technical nature made to the computing community.” The Turing Award is often referred to as the computer

degree: …American universities customarily grant the bachelor’s as the first degree in arts or sciences. After one or two more years of coursework, the second degree, M.A. or M.S., may be obtained by examination or the completion of a piece of research. At the universities of Oxford and Cambridge, holders of…

A.C. Nielsen: …his fraternity brothers, he founded A.C. Nielsen Co., which eventually became the largest market-research concern in the world. In the early years the company had difficulties, almost going bankrupt twice, but it finally established a business foothold by analyzing retail food and drug sales, which thereafter remained the company’s largest…

Jane Lynch: …The Three Stooges (2012), and A.C.O.D. (2013) and had recurring roles in a number of TV series, including Party Down (2009–10). She also lent her voice to the animated movies Wreck-It Ralph (2012) and its sequel, Ralph Breaks the Internet (2018). In 2017 Lynch portrayed Janet Reno in the miniseries…

Australian Capital Territory (A.C.T.), political entity of the Commonwealth of Australia consisting of Canberra, the national and territorial capital, and surrounding land. Most of the Australian Capital Territory lies within the Southern Tablelands district of New South Wales in southeastern

Steven Spielberg: The 2000s: A.I. Artificial Intelligence (2001), based on a short story by British author Brian Aldiss, was a project conceived in the 1970s by Stanley Kubrick, who some 20 years later, with the movie still in its planning stages, began to think Spielberg was a more likely…

chatbot: A.L.I.C.E. and Jabberwacky: …1995 a chatbot known as A.L.I.C.E. (Artificial Linguistic Internet Computer Entity) was released by developer Richard Wallace. In creating A.L.I.C.E., Wallace improved upon the AI used by Eliza after monitoring its conversations. After A.L.I.C.E. was presented with a sentence or phrase that it could not recognize, Wallace would add a…

dictionary: From 1604 to 1828: …a Dutchman known only as A.M. translated from Latin into English a famous medical work by Oswald Gabelkhouer, The Boock of Physicke, published at Dort, in the Netherlands. As he had been away from England for many years and had forgotten much of his English, A.M. sometimes merely put English…

12-hour clock: …as am, which stands for ante meridiem, “before midday” in Latin, while the second is referred to using pm, meaning post meridiem, or “after midday.” This nomenclature is based on the position of the Sun in relation to the meridian. In writing, periods can be added or omitted and lowercase…

master of arts, degree and title conferred by colleges and universities to indicate the completion of a course of study in the humanities (such as philosophy, arts, or languages). Candidates are often required to take an exam and to complete a thesis or creative project. Programs usually take an

French literature: The legacy of the 19th century: Barnabooth: son journal intime (1913; A.O. Barnabooth: His Diary) depicts the slow discovery of the self after an initial liberation. An enormously successful exercise in nostalgia, Le Grand Meaulnes (1913; Le Grand Meaulnes: The Land of Lost Content) by Alain-Fournier (pseudonym of Henri-Alban Fournier) explored the new theme of adolescence;…

French literature: The legacy of the 19th century: Barnabooth: son journal intime (1913; A.O. Barnabooth: His Diary) depicts the slow discovery of the self after an initial liberation. An enormously successful exercise in nostalgia, Le Grand Meaulnes (1913; Le Grand Meaulnes: The Land of Lost Content) by Alain-Fournier (pseudonym of Henri-Alban Fournier) explored the new theme of adolescence;…

construction: Use of steel and other metals: …glass curtain wall was the A.O. Smith Research Building (1928) in Milwaukee by Holabird and Root; in it the glass was held by aluminum frames, an early use of this metal in buildings. But these were rare examples, and it was not until the development of air conditioning, fluorescent lighting,…

Lorne Michaels: Among his later shows were A.P. Bio (2018–21) and Miracle Workers (2019– ). His film-producing credits include Wayne’s World (1992), Tommy Boy (1995), Mean Girls (2004), Baby Mama (2008), and Whiskey Tango Foxtrot (2016). Many of the projects Michaels produced involved former SNL

The Baltimore Sun: …with their corporate owner, the A.S. Abell Company, were bought by the Times Mirror Company in 1986. In 2000 the Times Mirror merged with the Tribune Company, and The Baltimore Sun thereby became a subsidiary of the latter. An Internet version of the paper was launched in 1996. In 2014…

Sir Alliott Verdon Roe: Roe founded A.V. Roe and Company, Ltd., with his brother Humphrey in 1910. Of his early planes, the Avro 504 was the most successful: more than 17,000 were manufactured. It was used on bombing missions in the early part of World War I and served as a…

telecommunication: Analog-to-digital conversion: In transmission of speech, audio, or video information, the object is high fidelity—that is, the best possible reproduction of the original message without the degradations imposed by signal distortion and noise. The basis of relatively noise-free and distortion-free telecommunication is the

conductive ceramics: Oxygen sensors: … to monitor and control the air-to-fuel (A/F) ratio in the internal combustion engine. A prominent sensor material is zirconia, which, as noted above, can be an excellent high-temperature oxygen conductor if suitably doped with Ca2+ or Y3+. A tube or thimble made of zirconia can be exposed on its exterior…

A24, independent film and television production and distribution company based in New York City and founded in 2012 by film executives Daniel Katz, David Fenkel, and John Hodges. The company first gained recognition for critically acclaimed films such as Spring Breakers (2013), The Spectacular Now

A24, independent film and television production and distribution company based in New York City and founded in 2012 by film executives Daniel Katz, David Fenkel, and John Hodges. The company first gained recognition for critically acclaimed films such as Spring Breakers (2013), The Spectacular Now

Airbus Industrie: The A300 was developed to fill the market niche for a short- to medium-range, high-capacity aircraft. It was the first wide-body jetliner to be equipped with only two engines for better operating economics. The A300 prototype made its first flight in 1972, and the aircraft entered…

Airbus Industrie: That aircraft, the A310, first flew in 1982 and entered service three years later. With the addition of the A310 to its product line, Airbus Industrie was able to offer to operators the advantages and savings of an aircraft family—for example, similarity of flight decks, commonality of parts,…

aerospace industry: Internationalization: Its third product, the A320 (1988), was the first subsonic commercial aircraft to be designed with fly-by-wire (electric rather than mechanical) primary controls and the first commercial aircraft to feature the so-called glass cockpit, which used electronic rather than mechanical displays. Through its innovations and the growing range of…

Airbus Industrie: …assembly began of the first A350, an aircraft intended to fly long-distance routes with great economy and minimal damage to the environment. The twin-engine A350 featured new fuel-efficient Rolls-Royce engines and a lightweight airframe made largely of titanium, aluminum, and carbon-fiber-reinforced plastic.

Airbus Industrie: …long-distance market with the “ultralong-range” A380, the world’s largest airliner. Built with two passenger decks extending the full length of the aircraft, it offered a standard seating capacity of 555 and a maximum capacity of 853 in an all-economy class configuration. In 2012 final assembly began of the first A350,…

A:Shiwi, Indigenous North American group in what is now west-central New Mexico, on the Arizona border. The A:Shiwi are a Pueblo people and speak Shiwi’ma, an isolate language in the Penutian language grouping. They are believed to be descendants of the prehistoric Ancestral Pueblo (Anasazi).

Alcoholics Anonymous (AA), voluntary fellowship of alcoholic persons who seek to get sober and remain sober through self-help and the help of other recovered alcoholics. Although general conventions meet periodically and Alcoholics Anonymous World Services, Inc., is headquartered in New York City,

automobile club: …Royal Automobile Club (RAC) and Automobile Association (AA) pioneered nationwide patrols, first by bicycle and later on motorbikes. The first roadside telephone box for motorist assistance was installed by the RAC in 1919. After World War II, insurance companies, oil companies, and national retailers formed auto clubs. Clubs were also…

Aa, the name of many small European rivers. The word is derived from the Old High German aha, cognate to the Latin aqua (“water”). Among the streams of this nature are: a river in northern France flowing through St. Orner and Gravelines and a river of Switzerland, in the cantons of Lucerne and

lava: …the Hawaiian names pahoehoe and aa (or a’a). Pahoehoe lava flows are characterized by smooth, gently undulating, or broadly hummocky surfaces. The liquid lava flowing beneath a thin, still-plastic crust drags and wrinkles it into tapestry-like folds and rolls resembling twisted rope. Pahoehoe lava flows are fed almost wholly internally…

rocket and missile system: Air-to-air: …in the 1960s with the AA-1 Alkali, a relatively primitive semiactive radar missile, the AA-2 Atoll, an infrared missile closely modeled after the Sidewinder, and the AA-3 Anab, a long-range, semiactive radar-homing missile carried by air-defense fighters. The AA-5 Ash was a large, medium-range radar-guided missile, while the AA-6 Acrid…

rocket and missile system: Air-to-air: The AA-10 Alamo, a medium-range missile similar to the Amos, apparently had passive radar guidance designed to home onto carrier-wave emissions from U.S. aircraft firing the semiactive radar-homing Sparrow. The AA-11 Archer was a short-range missile used in combination with the Amos and Alamo.

rocket and missile system: Air-to-air: The AA-11 Archer was a short-range missile used in combination with the Amos and Alamo.

rocket and missile system: Air-to-air: …primitive semiactive radar missile, the AA-2 Atoll, an infrared missile closely modeled after the Sidewinder, and the AA-3 Anab, a long-range, semiactive radar-homing missile carried by air-defense fighters. The AA-5 Ash was a large, medium-range radar-guided missile, while the AA-6 Acrid was similar to the Anab but larger and with…

rocket and missile system: Air-to-air: …after the Sidewinder, and the AA-3 Anab, a long-range, semiactive radar-homing missile carried by air-defense fighters. The AA-5 Ash was a large, medium-range radar-guided missile, while the AA-6 Acrid was similar to the Anab but larger and with greater range. The AA-7 Apex, a Sparrow equivalent, and the AA-8 Aphid,…

rocket and missile system: Air-to-air: The AA-5 Ash was a large, medium-range radar-guided missile, while the AA-6 Acrid was similar to the Anab but larger and with greater range. The AA-7 Apex, a Sparrow equivalent, and the AA-8 Aphid, a relatively small missile for close-in use, were introduced during the 1970s.…

rocket and missile system: Air-to-air: …medium-range radar-guided missile, while the AA-6 Acrid was similar to the Anab but larger and with greater range. The AA-7 Apex, a Sparrow equivalent, and the AA-8 Aphid, a relatively small missile for close-in use, were introduced during the 1970s. Both used semiactive radar guidance, though the Aphid was apparently…

rocket and missile system: Air-to-air: The AA-7 Apex, a Sparrow equivalent, and the AA-8 Aphid, a relatively small missile for close-in use, were introduced during the 1970s. Both used semiactive radar guidance, though the Aphid was apparently produced in an infrared-homing version as well. The long-range, semiactive radar-guided AA-9 Amos appeared…

rocket and missile system: Air-to-air: …a Sparrow equivalent, and the AA-8 Aphid, a relatively small missile for close-in use, were introduced during the 1970s. Both used semiactive radar guidance, though the Aphid was apparently produced in an infrared-homing version as well. The long-range, semiactive radar-guided AA-9 Amos appeared in the mid-1980s; it was associated with…

rocket and missile system: Air-to-air: The long-range, semiactive radar-guided AA-9 Amos appeared in the mid-1980s; it was associated with the MiG-31 Foxhound interceptor, much as the U.S. Phoenix was associated with the F-14. The Foxhound/Amos combination may have been fitted with a look-down/shoot-down capability, enabling it to engage low-flying targets while looking downward against…

Agricultural Adjustment Act, in U.S. history, legislation signed in May 1933 by Pres. Franklin D. Roosevelt as part of the Hundred Days phase of his New Deal domestic program. The Agricultural Adjustment Act was designed to provide immediate economic relief to farmers during the Great Depression

Amateur Athletic Association (AAA), British national governing organization for the sport of track and field (athletics). Founded in 1880, it took over as the governing power from the Amateur Athletic Club, founded in 1866. The association was the first such organization in the world. The AAA was

Agricultural Adjustment Administration (AAA), in U.S. history, major New Deal program to restore agricultural prosperity during the Great Depression by curtailing farm production, reducing export surpluses, and raising prices. The Agricultural Adjustment Act (May 1933) was an omnibus farm-relief

automobile club: The American Automobile Association (AAA) was established in 1902, consolidating nine earlier auto clubs. By the last quarter of the century there were more than 100 national auto clubs and associations affiliated throughout the world, linked by reciprocal agreements.

Euclidean geometry: Similarity of triangles: …may be reformulated as the AAA (angle-angle-angle) similarity theorem: two triangles have their corresponding angles equal if and only if their corresponding sides are proportional. Two similar triangles are related by a scaling (or similarity) factor s: if the first triangle has sides a, b, and c, then the second…

Tedros Adhanom: …in drafting part of the Addis Ababa Action Agenda (AAAA), a framework for advancing Africa’s economic, social, and political progress, and in coordinating a response to the 2013–16 Ebola outbreak in western Africa.

American Academy of Addiction Psychiatry (AAAP), professional organization founded in 1985 that seeks to educate the public and influence public policy with regard to addictive illness while increasing the overall effectiveness of psychiatric care in the United States related to addictions.

American Association for the Advancement of Science (AAAS), the largest general scientific society in the United States. It was founded in 1847 in Boston, Mass., by a number of geologists and naturalists and held its first meeting in Philadelphia, Pa., in 1848. Its goals are to further the work of

United States v. Thomas: …they had created, named the Amateur Action Bulletin Board Service (AABBS). The service was operated from a dedicated computer and phone line, which allowed dial-in access (using modems) to the BBS from individuals’ homes. Once connected, individuals could read and post messages as well as download any materials (such as…

Åbenrå, city, southeastern Jutland, Denmark, at the head of Åbenrå Fjord. First mentioned in the 12th century when attacked by the Wends, it was granted a charter (1335) and grew from a fishing village into a thriving port in the 17th and 18th centuries. Medieval landmarks include the St. Nicholas

density current: Density currents originating from marginal seas: …and this water forms the Antarctic Bottom Water (AABW). Alternatively, an intermediate layer is created if the density difference with the surrounding waters reaches zero before the density current arrives at the bottom of the ocean. In this scenario, the current spreads horizontally at an intermediate depth. Such intermediate layers…

athletics: Modern development: …amateurs, and in 1866 the Amateur Athletic Club (AAC) was founded and conducted the first English championships. The emphasis in all these meets was on competition for “gentlemen amateurs” who received no financial compensation. In 1880 the AAC yielded governing power to the Amateur Athletic Association (AAA).

augmentative and alternative communication (AAC), form of communication used in place of or in addition to speech. Augmentative and alternative communication (AAC) includes the use of communication aids, such as alphabet boards and electronic communication devices that speak, as well as unaided

Aachen, city, North Rhine–Westphalia Land (state), western Germany. Its municipal boundaries coincide on the west with the frontiers of Belgium and the Netherlands. It was a royal residence of the emperor Charlemagne, and it served as the principal coronation site of Holy Roman emperors and of

Aachen Cathedral, cathedral in Aachen, Germany, that was commissioned by the Holy Roman emperor Charlemagne and designed by the architect Odo of Metz. It was constructed 793–813 and incorporates the Palatine Chapel, considered to be a masterpiece of Carolingian architecture. The evolution of church

St. Gregory VII: Early life: …which Hildebrand harshly criticized the Aachen Rule for Canons ratified under Emperor Louis the Pious (814–840) at the Aachen council of 816. He pointed out in particular that this rule permitted canons to own private property and was thus in conflict with the declarations of the ancient Church Fathers and…

Louis I: The challenges of empire: Aachen (now in Germany), where his father had established his palace, was cleared of its prostitutes; Louis’s unmarried sisters, who had consorted sexually with court palatines, were sent to monasteries. Louis also tackled wider issues. In his first year as emperor the chancery dispatched nearly…

Mannerism: Hans von Aachen became important Mannerist painters. Although the Dutch cities of Haarlem and Amsterdam became centers of the new style, the most ambitious patronage was practiced at Prague by the Emperor Rudolf II; Spranger and others who worked for Rudolf evolved a Mannerism that…

Association for the Advancement of Creative Musicians (AACM), cooperative organization of musicians, including several major figures of free jazz. The musical innovations of the AACM members became important influences on the idiom’s development. Of the approximately three dozen Chicago musicians

library: Anglo-American Cataloguing Rules: The second edition of Anglo-American Cataloguing Rules (AACR2) is the most widely used cataloging code, designed for use in the construction of catalogs and other lists in general libraries of all sizes. It is published jointly by the American Library Association, the…

aids for activities of daily living (AADLs), products, devices, and equipment used in everyday functional activities by the disabled or the elderly. A form of assistive technology, aids for activities of daily living (AADLs) include a wide range of devices. Potential categories of equipment may

African American English (AAE), a language variety that has also been identified at different times in dialectology and literary studies as Black English, black dialect, and Negro (nonstandard) English. Since the late 1980s, the term has been used ambiguously, sometimes with reference to only

United States Air Force: …units were merged into the Army Air Forces (AAF) under a single commander, General Henry H. Arnold. From its headquarters in Washington, D.C., the AAF directed the expansion of the air arm into a powerful organization composed of 16 air forces (12 of them overseas), 243 combat groups, 2,400,000 officers…

American football: Birth and early growth of professional football: Finally, the All-America Football Conference (1946–1949) seriously challenged the existing league and contributed the Cleveland Browns, San Francisco 49ers, and a first version of the Baltimore Colts to an expanded NFL in 1950. Yet professional football could offer the public nothing comparable to the compelling rivalries, youthful