| | - Acheson process
- (from the article "refractory") 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 ...
- Acheson, Dean
- 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 ... [4 Related Articles]
- Acheson, Edward Goodrich
- American inventor who discovered the abrasive Carborundum and perfected a method for making graphite. [3 Related Articles]
- Acheson, Lila Bell
- 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. [2 Related Articles]
- Acheson-Lilienthal Report
- (from the article "international relations") ...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 ...
- Acheulean industry
- first standardized tradition of toolmaking of Homo erectus and early Homo sapiens. Named for the type site, Saint-Acheul, in Somme departement, in northern France, Acheulean tools were made of stone with good fracture characteristics, including chalcedony, jasper, and flint; in ... [16 Related Articles]
- achievement
- (from the article "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 ...
- achievement motivation
- (from the article "motivation") 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 ...
- achievement test
- (from the article "psychological testing") ...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 ...
- Achill Island
- 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 ...
- Achillas
- (from the article "Arsinoe IV") ...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 ...
- Achilles
- 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 ... [12 Related Articles]
- Achilles
- (from the article "Troilus and Cressida") ...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 ...
- Achilles
- (from the article "Wolf, Max") ...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 ...
- 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 ...
- Achilles paradox
- 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 ... [5 Related Articles]
- Achilles Tatius
- 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"). ...
- Achilles tendon
- 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 ... [1 Related Articles]
- Achillini, Alessandro
- Italian philosopher and physician, an advocate of the teachings of William of Ockham.
- Achinsk
- city, Krasnoyarsk kray (region), south-central Russia. It lies along the Chulym River, which is a tributary of the Ob. It was founded in 1621 and chartered in 1782. Important as a river-road transfer point until rail lines were constructed, it ...
- Achinstein, Peter
- (from the article "science, philosophy of") ...strategy began by questioning the Hempelian proposal that ordinary explanations consist in explanation sketches whose force derives from an unarticulated ideal explanation. Philosophers such as Peter Achinstein and Bas van Fraassen offered pragmatic theories, according to which what counts as ...
- Achlya
- (from the article "fungus") ...in the other. In Allomyces (order Blastocladiales) a pheromone named sirenin, secreted by the female gametes, attracts the male gametes, which swim toward the former and fuse with them. In Achlya (phylum Oomycota, kingdom Chromista) a sterol pheromone called antheridiol ...
- Acholi
- ethnolinguistic group of northern Uganda and southernmost Sudan. Numbering more than one million at the turn of the 21st century, they speak a Western Nilotic language of the Eastern Sudanic branch of the Nilo-Saharan family and are culturally and historically ... [3 Related Articles]
- achondrite
- any stony meteorite containing no chondrules (small, roughly spherical objects that formed in the solar nebula). The only exclusions are carbonaceous chondrites of the CI group, which, though they are clearly chondrites, are so heavily altered by water that any ... [4 Related Articles]
- achondroplasia
- genetic disorder characterized by an abnormality in the conversion of cartilage into bone. As a consequence, bones that depend on cartilage models for development, particularly long bones such as the femur and humerus, cannot grow. Achondroplasia is the most common ... [3 Related Articles]
- Achong, Larry
- (from the article "Trinidad and Tobago") Trinidad and Tobago's labour minister, Larry Achong, resigned from Prime Minister Patrick Manning's cabinet in March 2004 because of the government's failure to enact a special minimum wage for the heavy construction (energy) sector, which had been opposed by business ...
- Achoris
- (from the article "Egypt, ancient") ...independence, 4th-century Egypt was characterized by continual internal struggle for the throne. After a long period of fighting in the delta, a 29th dynasty (399-380 BC) emerged at Mendes. Achoris (ruled 393-380 BC), its third and final ruler, was especially ...
- achroite
- (from the article "tourmaline") ...usually recognized: iron tourmaline (schorl), black in colour; magnesium tourmaline (dravite), brown; and alkali tourmaline, which may be pink (rubellite), green (Brazilian emerald), or colourless (achroite). Some crystals are pink at one end and green at the other; concentric colour ...
- achromatic lens
- (from the article "biology") ...microscope languished for nearly 200 years, mainly because the early lenses tended to break up white light into its constituent parts. This technical problem was not solved until the invention of achromatic lenses, which were introduced about 1830. In 1878 ...
- achromatic point
- (from the article "colour") ...closed curve, as shown in the standard chromaticity diagram. Points along the circumference correspond to saturated colours; pale unsaturated colours appear closer to the centre of the diagram. The achromatic point is the central point at x = 13, y = 13 (shown as ...
- Achromatium
- (from the article "bacteria") ...Some bacteria are relatively large, such as Azotobacter, which has diameters of 2 to 5 mum or more; the cyanobacterium Synechococcus, which averages 6 mum by 12 mum; and Achromatium, which has a minimum width of 5 mum and a ...
- achromatopsia
- (from the article "colour blindness") Acquired colour blindness is usually of the blue-yellow type and can be due to retinal diseases, glaucoma, or optic nerve diseases. Total colour blindness (achromatopsia) is an extremely rare congenital affliction that is typically associated with poor vision, nystagmus (rapid, ...
- Achterberg, Gerrit
- Dutch poet whose use of surreal language and imagery influenced a generation of post-World War II poets known as the Experimentalists. His verse, traditional in form, is characterized as romantic and metaphysical. He was a linguistic innovator, often coining new ...
- Achterhoek
- (from the article "Gelderland") ...with sandy soil; south is fertile clay alluvium. The northern portion is divided by the broad valley (Gelderse) of the IJssel into the Veluwe ("Bad Land") region on the west and the Achterhoek on the east. The hill plateau of ...
- Achyuta Deva Raya
- (from the article "India") Krishna Deva had passed over his infant son and his young nephew and picked his half brother Achyuta Deva Raya (reigned 1529-42) to succeed him. Following a brief succession dispute, Achyuta Deva Raya was able to reach the capital from ...
- acicular texture
- (from the article "mineral") ...flat, platelike individuals arranged in layers; bladed, elongated crystals flattened like a knife blade; fibrous, an aggregate of slender fibres, parallel or radiating; acicular, slender, needlelike crystals; radiating, individuals forming starlike or circular groups; globular, radiating individuals forming small spherical ...
- acid
- any substance that in water solution tastes sour, changes the colour of certain indicators (e.g., reddens blue litmus paper), reacts with some metals (e.g., iron) to liberate hydrogen, reacts with bases to form salts, and promotes certain chemical reactions (acid ... [17 Related Articles]
- acid anhydride
- (from the article "chemical compound") Esters have an alkoxy (OR) fragment attached to the acyl group; amides have attached amino groups (&singlehorzbond;NR2); acyl halides have an attached chlorine or bromine atom; and anhydrides have an attached carboxyl group. Each type of acid derivative has a ...
- acid bite
- (from the article "printmaking") The acid bite of the plate is a critical stage in the making of an etching. The printmaker must be familiar with the characteristics of the materials that are being used. On a zinc plate nitric acid is used. In ...
- Acid Black 1
- (from the article "dye") ...groups direct in weakly acidic media. H-acid (8-amino-1-naphthol-3,6-disulfonic acid) has both functional groups and can be selectively coupled to two diazo components in a two-step process. C.I. Acid Black 1 is formed by coupling first to diazotized p-nitroaniline in weakly ...
- acid dye
- any bright-coloured synthetic organic compound whose molecule contains two groups of atoms-one acidic, such as a carboxylic group, and one colour-producing, such as an azo or nitro group. Acid dyes are usually applied in the form of their sodium salts, ... [1 Related Articles]
- acid halide
- neutral compound that reacts with water to produce an acid and a hydrogen halide. Acid halides are ordinarily derived from acids or their salts by replacement of hydroxyl groups by halogen atoms. The most important organic acid halides are the ... [1 Related Articles]
- acid house
- (from the article "house") ...such as Frankie Knuckles and Marshall Jefferson, house reached Europe by 1986, with tracks on Chicago labels Trax and DJ International penetrating the British pop charts. In 1988 the subgenre called acid house catalyzed a British youth culture explosion, when ...
- acid hydrolase
- (from the article "lysosome") ...and microorganisms. Each lysosome is surrounded by a membrane that maintains an acidic environment within the interior via a proton pump. Lysosomes contain a wide variety of hydrolytic enzymes (acid hydrolases) that break down macromolecules such as nucleic acids, proteins, ...
- acid leaching
- (from the article "uranium processing") Acid leaching is commonly performed by agitating an ore-leach mixture for 4 to as long as 48 hours at ambient temperature. Except in special circumstances, sulfuric acid is the leachant used; it is supplied in amounts sufficient to obtain a ...
- acid lead
- (from the article "lead processing") ...for piping and as a lining material. Common lead is fully refined and desilvered lead, with low copper content; it is widely used wherever high corrosion resistance is not necessary. Acid lead, made by adding copper to fully refined lead, ...
- acid phosphatase
- (from the article "enzyme analysis") ...usually shows elevated serum values in such conditions as Paget's disease (inflammation of the bone) and osteomalacia (softening of the bone), as well as in hepatitis and obstructive jaundice; (4) acid phosphatase, an enzyme found in most body tissue but ...
- acid rain
- form of precipitation containing a heavy concentration of sulfuric and nitric acids. The term is also commonly applied to snow, sleet, and hail that manifest similar acidification. Such precipitation has become an increasingly serious environmental problem in many areas of ... [10 Related Articles]
- acid-base catalysis
- acceleration of a chemical reaction by the addition of an acid or a base, the acid or base itself not being consumed in the reaction. The catalytic reaction may be acid-specific (acid catalysis), as in the case of decomposition of ...
- acid-base equilibrium
- (from the article "acid-base reaction") Certain general principles apply to any solvent with both acidic and basic properties-for example, water, alcohols, ammonia, amines, and acetic acid. Denoting the solvent molecule by SH, proton transfer can give rise to the ions SH2+ and S−, sometimes called ...
- acid-base reaction
- a type of chemical process typified by the exchange of one or more hydrogen ions, H+, between species that may be neutral (molecules, such as water, H2O; or acetic acid, CH3CO2H) or electrically charged (ions, such as ammonium, NH4+; hydroxide, ... [12 Related Articles]
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