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acetonitrile (chemical compound)
...are organic cyanides. They are named after the corresponding carboxylic acids by changing -ic acid to -onitrile, or -nitrile, whichever preserves a single letter o. Thus, CH3CN is acetonitrile (from acetic acid), whereas C6H5CN is benzonitrile (from benzoic acid)....
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acetophenetidin (drug)
drug used in the treatment of mild pain, such as headache and pain in joints and muscles, and to reduce fever. It is formed in the body as a metabolite of acetanilid or phenacetin, which were once commonly used drugs, and is responsible for their analgesic effects. Acetaminophen relieves pain by raising the body’s pain threshold, and it reduces fever by its action on the temperature-regulat...
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acetophenone (chemical compound)
an organic compound used as an ingredient in perfumes and as a chemical intermediate in the manufacture of pharmaceuticals, resins, flavouring agents, and a form of tear gas. It also has been used as a drug to induce sleep....
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acetyl coenzyme A (chemical compound)
...the carbon source. The most common pathways for synthesizing organic compounds from carbon dioxide are the reductive pentose phosphate (Calvin) cycle, the reductive tricarboxylic acid cycle, and the acetyl-CoA pathway (see photosynthesis: The process of photosynthesis: carbon fixation and reduction). The Calvin cycle, elucidated by American biochemist Melvin Calvin, is the most widely......
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acetyl coenzyme A carboxylase (enzyme)
...and fatty acids (Figure 2), the molecule first undergoes a carboxylation, forming malonyl coenzyme A, before participating in fatty acid synthesis. The carboxylation reaction is catalyzed by acetyl CoA carboxylase, an enzyme whose prosthetic group is the vitamin biotin. The biotin–enzyme first undergoes a reaction that results in the attachment of carbon dioxide to biotin; ATP is......
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acetyl transacylase (enzyme)
...as palmitic acid from acetyl coenzyme A and malonyl coenzyme A. The products of [63a] and [63b] are acetyl-S-ACP, malonyl-S-ACP, and coenzyme A. The enzymes catalyzing [63a] and [63b] are known as acetyl transacylase and malonyl transacylase, respectively. Acetyl-ACP and malonyl-ACP react in a reaction catalyzed by β-ketoacyl-ACP synthetase so that the acetyl moiety......
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acetyl-CoA (chemical compound)
...the carbon source. The most common pathways for synthesizing organic compounds from carbon dioxide are the reductive pentose phosphate (Calvin) cycle, the reductive tricarboxylic acid cycle, and the acetyl-CoA pathway (see photosynthesis: The process of photosynthesis: carbon fixation and reduction). The Calvin cycle, elucidated by American biochemist Melvin Calvin, is the most widely......
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acetyl-S-ACP (enzyme)
...ACP–SH is involved in all of the reactions leading to the synthesis of a fatty acid such as palmitic acid from acetyl coenzyme A and malonyl coenzyme A. The products of [63a] and [63b] are acetyl-S-ACP, malonyl-S-ACP, and coenzyme A. The enzymes catalyzing [63a] and [63b] are known as acetyl transacylase and malonyl transacylase, respectively. Acetyl-ACP and malonyl-ACP react in a......
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acetylaniline (drug)
synthetic organic compound introduced in therapy in 1886 as a fever-reducing drug. Its effectiveness in relieving pain was discovered soon thereafter, and it was used as an alternative to aspirin for many years in treating such common complaints as headache, menstrual cramps, and rheumatism. Excessive or prolonged use engenders toxic side effects: it interferes with the function of hemoglobin, th...
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acetylation (biochemistry)
Two types of conjugations, acetylations and methylation, do not enhance the excretion of the parent chemical. Acetylation and methylation decrease the water solubility of the parent chemical and mask the functional group of the parent chemical, preventing these functional groups from participating in conjugations that increase their excretion. Acetylation acts on chemicals with an amino group......
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acetylcellulose (ester)
...molecule is converted by this action to acetaldehyde, itself a highly toxic substance, but the acetaldehyde is immediately acted upon by another enzyme, aldehyde dehydrogenase, and converted to acetate, most of which enters the bloodstream and is ultimately oxidized to carbon dioxide and water. Considerable utilizable energy—200 calories per ounce of alcohol (about 7.1 calories per......
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acetylcholine (chemical compound)
(ACh), an ester of choline and acetic acid that is the transmitter substance at many neural, or nerve, synapses and at the motor end plate of vertebrate muscles (see end-plate potential). When a nerve impulse arrives at the nerve ending, ACh, which is stored there in vesicles, is released and combines with a receptor molecule in the postsynaptic membra...
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acetylcholine receptor (biology)
Acetylcholine receptors are ion channels that span the postsynaptic membrane, and they have extracellular, intramembranous, and cytoplasmic portions. They are located principally over the peaks of the postsynaptic folds, where they are present at high density. They consist of five subunits arranged around the central ion channel....
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acetylcholinesterase (enzyme)
...and a change in the nature of a generator potential results. The effects of successive nerve impulses accumulate if they arrive at a sufficiently high frequency. The ACh is destroyed by an enzyme, acetylcholinesterase, and thus is effective only briefly. Inhibitors of the enzyme, however, prolong the lifetime of ACh itself....
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acetylcholinesterase inhibitor (drug)
any of several drugs that prevent destruction of the neurotransmitter acetylcholine by the enzyme acetylcholinesterase within the nervous system. Acetylcholine acts to transmit nerve impulses within the parasympathetic nervous system—i.e., that part of the autonomic nervous system that tends to induce secretion, to ...
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acetylene (chemical compound)
the simplest and best-known member of the hydrocarbon series containing one or more pairs of carbon atoms linked by triple bonds, called the acetylenic series, or alkynes. It is a colourless, inflammable gas widely used as a fuel in oxyacetylene welding and cutting of metals and as raw material in the synthesis of many organic chemicals and plastics; its chemical formula is C...
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acetylene tetrachloride (chemical compound)
either of two isomeric colourless, dense, water-insoluble liquids belonging to the family of organic halogen compounds. One isomer, 1,1,2,2-tetrachloroethane, also called acetylene tetrachloride, is highly toxic. Almost the entire production of the compound is consumed in manufacturing chlorinated solvents, especially trichloroethylene and tetrachloroethylene; it has minor uses as a solvent......
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acetylene torch
...welding, arc welding, and resistance welding all appeared at the end of the 19th century. The first real attempt to adopt welding processes on a wide scale was made during World War I. By 1916 the oxyacetylene process was well developed, and the welding techniques employed then are still used. The main improvements since then have been in equipment and safety. Arc welding, using a consumable......
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acetylide (chemical compound)
The hydrogen atoms in acetylene can be replaced by metallic elements to form acetylides—e.g., acetylides of silver, copper, or sodium. The acetylides of silver, copper, mercury, and gold are detonated by heat, friction, or shock. In addition to its reactive hydrogen atom, the carbon–carbon triple bond can readily add halogens, halogen acids, hydrogen cyanide, alcohols,......
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acetylsalicylic acid (drug)
derivative of salicylic acid that is a mild, nonnarcotic analgesic useful in the relief of headache and muscle and joint aches. Aspirin is also effective in reducing fever, inflammation, and swelling and thus has been used for treatment of rheumatoid arthritis, rheumatic fever, and mild infection. In these instances, aspirin generally acts on the symptoms of disease and does not modify or shorten ...
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Acevedo Díaz, Eduardo (Uruguayan writer and politician)
writer and politician, considered Uruguay’s first novelist....
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acey-deucy (game)
In one version of red dog—also known as yablon, acey-deucey, and between the sheets—each player puts up an initial stake, and the banker deals two cards faceup. Unless the ranks of the cards are the same or consecutive, the bettors may increase their stakes by as much as the original amount of their wagers on the basis of their belief that the next card turned from the deck will be.....
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ACh (chemical compound)
(ACh), an ester of choline and acetic acid that is the transmitter substance at many neural, or nerve, synapses and at the motor end plate of vertebrate muscles (see end-plate potential). When a nerve impulse arrives at the nerve ending, ACh, which is stored there in vesicles, is released and combines with a receptor molecule in the postsynaptic membra...
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ACH (finance)
The automated clearinghouse (ACH) is the third alternative means of making deposits and paying bills. ACH networks transfer existing deposit balances, avoid the use of checks, and speed payments and settlement. In addition, many large payments (such as those to settle securities or foreign exchange transactions between financial institutions) are made through electronic transfer systems that......
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Achab (king of Israel)
seventh king of the northern kingdom of Israel (reigned c. 874–c. 853 bc), according to the Old Testament, and son of King Omri....
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Achaea (region, Greece)
nomós (department) and historic region of Greece on the north coast of the Peloponnese, south of the Gulf of Corinth. In ancient times it was bounded on the west by Elis (modern Ilía), on the south by Mount Erymanthus and Arcadia, and on the east by Sicyon (modern Sikión). The hilly ...
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Achaean (people)
any of the ancient Greek people, identified in Homer, along with the Danaoi and the Argeioi, as the Greeks who besieged Troy. Their area as described by Homer—the mainland and western isles of Greece, Crete, Rhodes, and adjacent isles, except the Cyclades—is precisely that covered by the activities of the Mycenaeans in the 14th–13th century bc,...
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Achaean Confederacy (ancient Greek history)
3rd-century-bc confederation of the towns of Achaea in ancient Greece. The 12 Achaean cities of the northern Peloponnese had organized a league by the 4th century bc to protect themselves against piratical raids from across the Corinthian Gulf, but this league fell apart after the death of Alexander the Great. The 10 surviving citie...
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Achaean League (ancient Greek history)
3rd-century-bc confederation of the towns of Achaea in ancient Greece. The 12 Achaean cities of the northern Peloponnese had organized a league by the 4th century bc to protect themselves against piratical raids from across the Corinthian Gulf, but this league fell apart after the death of Alexander the Great. The 10 surviving citie...
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Achaemenes (Persian governor of Egypt)
son of the Achaemenid king Darius I of Persia....
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Achaemenes (Persian ruler of Parsumash)
eponymous ancestor of the Persian Achaemenid dynasty; he was the father of Teispes (Chishpish) and an ancestor of Cyrus II the Great and Darius I the Great. Although Achaemenes probably ruled only Parsumash, a vassal state of the kingdom of Media, many scholars believe that he led armies from Parsumash and Anshan (Anzan, northwest of Susa in...
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Achaemenian dynasty (Iranian dynasty)
(559–330 bc), ancient Iranian dynasty whose kings founded and ruled the Achaemenian Empire. Achaemenes (Persian Hakhamanish), the Achaemenians’ eponymous ancestor, is presumed to have lived early in the 7th century bc, but little is known of his life. From his son Teispes two lines of kings descended. The kings of the older line were Cyrus I...
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Achaemenid dynasty (Egyptian dynasty)
the Persian 27th dynasty of Egypt (525–404 bc), founded by Cambyses II of Persia and named after his family of the Achaemenids....
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Achaemenid dynasty (Iranian dynasty)
(559–330 bc), ancient Iranian dynasty whose kings founded and ruled the Achaemenian Empire. Achaemenes (Persian Hakhamanish), the Achaemenians’ eponymous ancestor, is presumed to have lived early in the 7th century bc, but little is known of his life. From his son Teispes two lines of kings descended. The kings of the older line were Cyrus I...
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Achaeus (governor of Asia Minor)
The son of Seleucus II, Antiochus succeeded his brother Seleucus III as king. He retained from the previous administration Hermias as chief minister, Achaeus as governor of Asia Minor, and Molon and his brother Alexander as governors of the eastern provinces, Media and Persis. In the following year, when Molon rebelled and assumed the title of king, Antiochus abandoned a campaign against Egypt......
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Achagua (people)
South American Indian people of Venezuela and eastern Colombia. They speak a language of the Maipurean Arawakan group. Traditionally, the Achagua had typical tropical-forest economies, living in large villages and growing bitter cassava and other crops. The Achagua were warlike; they were one of the few native South American people to use arrows poisoned with curare....
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Achaia (region, Greece)
nomós (department) and historic region of Greece on the north coast of the Peloponnese, south of the Gulf of Corinth. In ancient times it was bounded on the west by Elis (modern Ilía), on the south by Mount Erymanthus and Arcadia, and on the east by Sicyon (modern Sikión). The hilly ...
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Achaios (people)
any of the ancient Greek people, identified in Homer, along with the Danaoi and the Argeioi, as the Greeks who besieged Troy. Their area as described by Homer—the mainland and western isles of Greece, Crete, Rhodes, and adjacent isles, except the Cyclades—is precisely that covered by the activities of the Mycenaeans in the 14th–13th century bc,...
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Achaius (king of Scotland)
As with many orders of chivalry, its origins lie much further back in time. Tradition has it that at the end of the 8th century Achaius, King of Scots, founded a chivalric order and introduced the veneration of St. Andrew into Scotland, but few scholars accept this. More probable is that the Order of the Thistle relates to an order founded by King David I of Scots in the 12th century, as that......
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achalasia (pathology)
Disorders of the esophagus include ulceration and bleeding; heartburn, caused by gastric juices in the esophagus; achalasia, an inability to swallow or to pass food from the esophagus to the stomach, caused by destruction of the nerve endings in the walls of the esophagus; scleroderma, a collagen disease; and spasms of the esophageal muscles....
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Achariaceae (plant family)
Achariaceae contains 30 genera and 145 species of shrubs to trees, or rarely climbing herbs, which are scattered throughout the tropics. The Indo-Malesian Hydnocarpus (40 species) is the largest genus in the family. Ryparosa (18 species) is Malesian, and Lindackeria (14 species) grows in the Americas and Africa. Most species of Achariaceae were previously included in......
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“Acharneis” (play by Aristophanes)
This is the earliest of the 11 comedies of Aristophanes that have survived intact. Acharnians (425 bc; Greek Acharneis) is a forthright attack on the folly of the war. Its farmer-hero, Dicaeopolis, is tired of the Peloponnesian War and therefore secures a private peace treaty with the Spartans for himself in spite of the violent opposition of a chorus of embittered and ...
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Acharnians, The (play by Aristophanes)
This is the earliest of the 11 comedies of Aristophanes that have survived intact. Acharnians (425 bc; Greek Acharneis) is a forthright attack on the folly of the war. Its farmer-hero, Dicaeopolis, is tired of the Peloponnesian War and therefore secures a private peace treaty with the Spartans for himself in spite of the violent opposition of a chorus of embittered and ...
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Achatina (snail genus)
In some places, introductions of Achatina and Helix have resulted in damage to crops and gardens by these rapidly multiplying snails. On the other hand, habitat degradation, the introduction of predatory rats and land snails, and shell collecting by humans have caused the extinction of about 50 percent of all Achatinella species in Hawaii. Eighteen of the remaining 19......
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Achatina achatina (snail)
...and forest-litter snails (Stenopylis, Punctum) are less than one millimetre (0.04 inch) in diameter. At the other extreme, the largest land snail, the African Achatina achatina, forms a shell that is almost 20 centimetres (eight inches) long. The largest freshwater snails, Pomacea from South America, reach nearly 10 centimetres in diameter, and......
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Achatina fulica (gastropod)
In the 20th century, misguided individuals on a number of the Pacific islands introduced an African land snail, Achatina fulica, for food. It became a pest. So, like the song about the old woman who swallowed a fly, and then a spider to catch it, and so forth, a predatory snail, Euglandina rosea, was released to control the Achatina.......
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Achatinacea (gastropod superfamily)
...altered in sluglike forms; about 18,000 species.Suborder HolopodopesA group of 4 superfamilies.Superfamily AchatinaceaBesides the giant African snail, 4 families, including many species spread by commerce throughout the world.Superfamilies......
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Achatinellacea (gastropod superfamily)
...into mantle cavity (part of the viscera) near anterior margin of lung after ureter passes forward from anterior kidney margin; about 6,000 species.Superfamily AchatinellaceaMinute to medium-sized Pacific land snails with multicuspid radular denticles; many Hawaiian species highly coloured and......
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Achaz (king of Judah)
king of Judah (c. 735–720 bc) who became an Assyrian vassal (2 Kings 16; Isaiah 7–8)....
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Achdar, Gebel el- (mountains, Libya)
mountain range of northeastern Libya that extends along the Mediterranean coast for about 100 miles (160 km) in an east-northeasterly direction between the towns of al-Marj and Darnah. Rising sharply in two steps, the first reaching 985 feet (300 m) and the second about 1,800 feet (550 m), the limestone range (about 20 miles [32 km] wide) then blends into a plateau crowned by hills attaining eleva...
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Aché (people)
nomadic South American Indian people living in eastern Paraguay. The Aché speak a Tupian dialect of the Tupi-Guaranian language family. They live in the densely forested, hilly region between the Paraguay and Paraná rivers. In pre-Spanish times, the Aché lived a more settled, agricultural life in a less harsh environment, but the activities of the Spanish a...
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Acheampong, Ignatius Kutu (chief of state, Ghana)
Ghanaian army officer, who, after leading a military revolt that overthrew the government of Kofi Busia, became Ghana’s chief of state in 1972. In July 1978 he was forced to resign, and the following June he and his successor, Lieut. Gen. F.W.K. Akuffo, were executed after a coup led by young officers, whose Armed Forces Revolutionary Council returned Ghana to civilian rule in September 197...
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Achebe, Albert Chinualumogu (Nigerian author)
prominent Igbo (Ibo) novelist acclaimed for his unsentimental depictions of the social and psychological disorientation accompanying the imposition of Western customs and values upon traditional African society. His particular concern was with emergent Africa at its moments of crisis; his novels range in subject matter from the first contact of an African village with the white man to the educated...
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Achebe, Chinua (Nigerian author)
prominent Igbo (Ibo) novelist acclaimed for his unsentimental depictions of the social and psychological disorientation accompanying the imposition of Western customs and values upon traditional African society. His particular concern was with emergent Africa at its moments of crisis; his novels range in subject matter from the first contact of an African village with the white man to the educated...
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Acheh (province, Indonesia)
semiautonomous province of Indonesia, forming the northern extremity of the island of Sumatra. Aceh is surrounded by water on three sides: the Indian Ocean to the west and north and the Strait of Malacca to the east. Its boundary with Sumatera Utara (North Sumatra) province to the southeast extends north-south from Salahaji on the northeaste...
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Acheiropoietos, Church of the (church, Thessaloníki, Greece)
The ecclesiastical architecture of the East is more varied, partly as a result of differences in the liturgies. The monastery of St. John the Baptist of Studium in Constantinople (463) and the church of the Acheiropoietos at Thessalonica (470) were basilicas with tribunes and narthexes, which, in their proportions, approached those of centrally planned structures. The large central aisle,......
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Achelous River (river, Greece)
one of the longest rivers in Greece, rising in the Pindus Mountains of central Epirus (Ípiros) and dividing Aetolia from Acarnania. It debouches into the Ionian Sea after a course of 140 mi (220 km), mostly through gorges. Well above Agrínion two hydroelectric dams were built to harness the waters of the river and its tributaries. One is at Kastraki; the other, at Kremasta, is the hi...
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Achen Pass (mountain pass, Europe)
...to the north its gentle slopes allow the grazing of cattle. The mountains hold lignite mines and petroleum deposits and are crossed at Scharnitz Pass (3,133 feet [955 m]) by road and railway and at Achen Pass (3,087 feet [941 m]) by road. Tourism and winter sports are the region’s main activities. A large national park preserves the original Alpine landscape, plants, and animals from the...
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Achenbach, Andreas (German painter)
landscape painter, a pioneer of the German realist school. He studied at the Düsseldorf academy under Johann Wilhelm Schirmer, but emancipated himself from the contemporary school of landscapists that delighted in the representation of romantic scenery. He was the first artist of the Düsseldorf school to paint nature for its own sake. His pictures of the stormy North Sea, of Dutch ca...
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Achenbach, Oswald (German painter)
landscape painter of the Düsseldorf school who is distinguished for his colourful renderings of the Bay of Naples, of Rome, and of Venice. He broke away from the traditional classicist interpretation of these scenes and revelled in strong and glowing colour effects. His more famous brother, Andreas, influenced his work....
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achene (plant anatomy)
dry, one-seeded fruit lacking special seams that split to release the seed. The seed coat is attached to the thin, dry ovary wall (husk) by a short stalk, so that the seed is easily freed from the husk, as in buckwheat. The fruits of many plants in the buttercup family and the rose family are achenes. ...
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Acheng (China)
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....
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Acheron (Greek religion)
in Greek mythology, one of the rivers of the underworld. The word styx literally means “shuddering” and expresses loathing of death. In Homer’s Iliad and Odyssey, the gods swear by the water of the Styx as their most binding oath. According to Hesiod’s Theogony, if a god ...
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Acheron (river, Greece)
river in Thesprotía in Epirus, Greece, that was thought in ancient times to go to Hades because it flowed through dark gorges and went underground in several places; an oracle of the dead was located on its bank. In Greek mythology it is a river in Hades, and the name sometimes refers to the lower world generally. Several other rivers in Greece are also called Acheron, which traditionally ...
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Acherontia atropos (insect)
The common name for Acherontia atropos, death’s head moth, derives from the fancied facsimile of a human skull on the upper surface of the body. Common in Europe and Africa, these moths have a short proboscis and often feed on honey from beehives. They produce loud chirping or squeaking sounds by forcing air out through the proboscis. In the larval stage they ma...
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Acherusian Swamp (lagoon, Italy)
coastal lagoon in Napoli provincia, Campania regione, southern Italy, west of Naples. The lagoon is separated from the sea on the west by sand dunes. As the ancient Palus Acherusia (“Acherusian Swamp”), it may have been the harbour of nearby Cumae in antiquity. In the first century ad, an outlet was dug at its southern end, with a tunnel under the hill of ...
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Achery, Jean-Luc d’ (French scholar)
...code. About 800 the Hadriana and the Hispana were developed into a systematic whole, the Dacheriana (canonical collection named for its 17th-century publisher, French scholar Jean-Luc d’Achéry)—the principal source of the collections before 850—which was of influence until the Gregorian reform in the 11th century....
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Acheson, Archibald (governor of British North America)
governor-in-chief of British North America in 1835–37, who alienated English- and French-speaking colonists in Canada....
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Acheson, Dean (United States statesman)
U.S. secretary of state (1949–53) and adviser to four presidents, who became the principal creator of U.S. foreign policy in the Cold War period following World War II; he helped to create the Western alliance in opposition to the Soviet Union and other communist nations....
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Acheson, Dean Gooderham (United States statesman)
U.S. secretary of state (1949–53) and adviser to four presidents, who became the principal creator of U.S. foreign policy in the Cold War period following World War II; he helped to create the Western alliance in opposition to the Soviet Union and other communist nations....
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Acheson, Edward Goodrich (American inventor)
American inventor who discovered the abrasive Carborundum and perfected a method for making graphite....
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Acheson, Lila Bell (American publisher and philanthropist)
American publisher and philanthropist who, with her husband, DeWitt Wallace, created and published Reader’s Digest, one of the most widely circulated magazines in the world....
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Acheson process (technology)
Silicon carbide (SiC) ceramics are made by a process referred to as reaction bonding, invented by the American Edward G. Acheson in 1891. In the Acheson process, pure silica sand and finely divided carbon (coke) are reacted in an electric furnace at temperatures in the range of 2,200°–2,480° C (4,000°–4,500° F). SiC ceramics have outstanding high-temperatu...
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Acheson–Lilienthal Report (American publication)
...press, Congress, and the military against any giveaway of atomic secrets, Byrnes appointed a committee in January 1946 to draft proposals for international control of atomic energy. The resulting (Dean) Acheson–(David) Lilienthal Report called for a UN authority to survey and control all uranium deposits and ensure that atomic research was conducted for peaceful purposes only. Once......
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Acheta domesticus (insect)
The field cricket (genus Gryllus) and the house cricket (Acheta, formerly Gryllus, domesticus) of the subfamily Gryllinae are stout-bodied and black or brown and often dig shallow burrows. They may feed on plants, animals, clothes, and each other. The field cricket (also called the black cricket) is common in fields and yards and sometimes enters buildings. The house......
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Acheulean industry (prehistoric toolmaking)
first standardized tradition of toolmaking of Homo erectus and early Homo sapiens. Named for the type site, Saint-Acheul, in Somme département, in northern France, Acheulean tools were made of stone with good fracture characteristics, including chalcedony, jasper, and flint; in regions lacking these, quartzite might be used. During ...
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Acheulian industry (prehistoric toolmaking)
first standardized tradition of toolmaking of Homo erectus and early Homo sapiens. Named for the type site, Saint-Acheul, in Somme département, in northern France, Acheulean tools were made of stone with good fracture characteristics, including chalcedony, jasper, and flint; in regions lacking these, quartzite might be used. During ...
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Achi language
an American Indian language of the Mayan family, spoken in the western highlands of Guatemala. It is most closely related to the Cakchiquel, Tzutujil, Sacapultee, and Sipacapa languages of central Guatemala and more distantly related to Uspantec, Pocomam, Pocomchí, Kekchí, and other languages of the Eastern Mayan group (see Maya languages). The name Ach...
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achievement (heraldry)
The term achievement, properly armorial achievement, means the whole display showing shield, helmet, crest, mantling, wreath, and, if appropriate, additaments such as a motto and supporters. In addition, an achievement may include representations of various knightly orders or companionships of knightly orders to which the owner of the arms is entitled. For example,......
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Achievement (Academy Award)
Writing: Hans Kraly for The PatriotCinematography: Clyde De Vinna for White Shadows in the South SeasArt Direction: Cedric Gibbons for The Bridge of San Luis Rey and other pictures...
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achievement motivation (psychology)
Achievement was initially recognized as an important source of human motivation by the American psychologist Henry Murray in the late 1930s. Although Murray identified achievement motivation as important to the behaviour of many people, it was the American psychologists David McClelland and John Atkinson who devised a way of measuring differences in achievement motivation. These researchers......
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Achievement of Samuel Johnson, The (work by Bate)
...Language Association published Bate’s Stylistic Development of Keats; his full-length biography John Keats (1963) was awarded the Pulitzer Prize for Biography in 1964. In 1955 The Achievement of Samuel Johnson was awarded the Gauss Prize for literary history and criticism. Samuel Johnson (1977), a colourful account of Johnson’s personality and a vivid p...
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achievement test (psychology)
...distant future behaviour (e.g., success in school), such a device is called an aptitude test. When used to evaluate the individual’s present academic or vocational skill, it may be called an achievement test. In such settings as guidance offices, mental-health clinics, and psychiatric hospitals, tests of ability and personality may be helpful in the diagnosis and detection of trou...
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Achievements of the Divine Augustus (work by Augustus)
...and financial resources of the empire (breviarium totius imperii) and his political testament, known as the “Res Gestae Divi Augusti” (“Achievements of the Divine Augustus”). The best-preserved copy of the latter document is on the walls of the Temple of Rome and Augustus at Ankara, Turkey (the Monumentum Ancyranum). In ...
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Achill Island (island, Ireland)
mountainous island off the west coast of Ireland. It is part of County Mayo, joined to the mainland by a bridge across Achill Sound. The island is Ireland’s largest, with an area of 56 square miles (145 square km), and its highest points are the quartzite peaks of Slieve Croaghaun (2,182 feet [665 metres]) and Slieve More (2,201 feet [671 metres]). The landscape is domina...
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Achillas (Egyptian military officer)
...landing in Alexandria in 48, Caesar captured the members of the Ptolemaic royal family, but Arsinoe managed to escape with the aid of Ganymedes, her mentor, and joined the Egyptian army headed by Achillas. Following a feud between Ganymedes and the Egyptian commander, Arsinoe ordered Achillas executed. Ganymedes pressed Caesar’s forces hard and negotiated an exchange of Arsinoe for Ptole...
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Achille Lauro (Italian ship)
...attention. In October 1985 members of the Palestine Liberation Front, a small faction within the PLO headed by Abū ʿAbbās, hijacked an Italian cruise ship, the Achille Lauro, and murdered one of its passengers. Following an Israeli bombing attack on PLO headquarters near Tunis several days before the hijacking, ʿArafāt moved some...
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Achillea (plant)
any of about 115 species of perennial herbs constituting the genus Achillea in the family Asteraceae, and native primarily to the North Temperate Zone. They have toothed, often finely cut leaves that are sometimes aromatic. The many small white, yellow, or pink flowers often are grouped into flat-topped clusters....
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Achillea millefolium (plant)
Some species are cultivated as garden ornamentals. The dried leaves of sneezewort (A. ptarmica) are used to make a sneezing powder, and parts of yarrow or milfoil (A. millefolium) have been used for snuff and tea....
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Achillea ptarmica (plant)
Some species are cultivated as garden ornamentals. The dried leaves of sneezewort (A. ptarmica) are used to make a sneezing powder, and parts of yarrow or milfoil (A. millefolium) have been used for snuff and tea....
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Achilleid (work by Statius)
Statius completed one epic, the 12-book Thebaid, but only two books of another, the Achilleid. The Thebaid, a more ambitious work, describes the struggle of the brothers Polyneices and Eteocles for the throne of the ancient Greek city of Thebes. It has many features borrowed from Virgil, but suffers from overstatement and exaggeration. The work begins and ends, however,......
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Achilles (Greek mythology)
in Greek mythology, son of the mortal Peleus, king of the Myrmidons, and the Nereid, or sea nymph, Thetis. He was the bravest, handsomest, and greatest warrior of the army of Agamemnon in the Trojan War. According to Homer, Achilles was brought up by his mother at Phthia with his cousin and inseparable companion Patroclus. One of the non-Ho...
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Achilles (ship)
...ships in the Atlantic, the Graf Spee was sighted on Dec. 13, 1939, off the Río de la Plata estuary by a British search group consisting of the cruisers Exeter, Ajax, and Achilles, commanded by Commodore H. Harwood. At 6:14 am Harwood’s three ships attacked, but in a little more than an hour the Graf Spee had damaged the Exeter and d...
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Achilles (asteroid)
...to use the stereocomparator (a type of stereoscopic viewer), which greatly helps in the discovery and identification of variable or moving objects in celestial photographs. In 1906 he discovered Achilles, the first of the Trojan Planets, two groups of asteroids that move around the Sun in Jupiter’s orbit: one group 60° ahead of Jupiter, the other 60° behind....
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Achilles (fictional character)
...of Sparta but now the mistress of the Trojan prince Paris. Their one scene together presents Helen and Paris as vapid and self-centred. Other figures fare no less well. The legendary Greek hero Achilles is depicted as petulant and greedy for honour, so much so that he brutally massacres the great Hector when that warrior is unarmed. Hector, for his part, is at once the wisest of the Trojans......
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Achilles and Briseis (painting by Achilles Painter)
Athenian vase painter known by and named for an amphora attributed to him with a painting of “Achilles and Briseis.” The amphora is now in the Vatican Museums. His period of activity coincides with the Parthenon sculptures and with the administration of Pericles....
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Achilles Painter (Greek painter)
Athenian vase painter known by and named for an amphora attributed to him with a painting of “Achilles and Briseis.” The amphora is now in the Vatican Museums. His period of activity coincides with the Parthenon sculptures and with the administration of Pericles....
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Achilles paradox (logic)
in logic, an argument attributed to the 5th-century bc Greek philosopher Zeno, and one of his four paradoxes described by Aristotle in the treatise Physics. The paradox concerns a race between the fleet-footed Achilles and a slow-moving tortoise. The two start moving at the same moment, but if the tortoise is initially ...
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Achilles Tatius (Greek author)
author of Leucippe and Cleitophon, one of the Greek prose romances that influenced the development of the novel centuries later. Nothing certain is known of Achilles’ life. Some Byzantine sources called him a rhetor (“teacher of rhetoric”). In the Suda lexicon of the 10th century ad, he ...
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Achilles tendon (anatomy)
strong tendon at the back of the heel that connects the calf muscles to the heel. The tendon is formed from the gastrocnemius and soleus muscles (the calf muscles) and is inserted into the heel bone. The contracting calf muscles lift the heel by this tendon, thus producing a foot action that is basic to walking, running, and jumping. The Achilles tendon is the thickest and most powerful tendon in ...
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