poststructuralism, movement in literary criticism and philosophy begun in France in the late 1960s. Drawing upon the linguistic theories of Ferdinand de Saussure, the anthropology of Claude Lévi-Strauss (see structuralism), and the deconstructionist theories of Jacques Derrida (see deconstruction),

postsynaptic potential (PSP), a temporary change in the electric polarization of the membrane of a nerve cell (neuron). The result of chemical transmission of a nerve impulse at the synapse (neuronal junction), the postsynaptic potential can lead to the firing of a new impulse. When an impulse

dubbing, in filmmaking, the process of adding new dialogue or other sounds to the sound track of a motion picture that has already been shot. Dubbing is most familiar to audiences as a means of translating foreign-language films into the audience’s language. When a foreign language is dubbed, the

bridge: Concrete: A typical process, called post-tensioned prestressing, involves casting concrete beams with longitudinal holes for steel tendons—cables or bars—like reinforced concrete, but the holes for the tendons are curved upward from end to end, and the tendons, once fitted inside, are stretched and then anchored at the ends. The tendons,…

axiom: …listed in two categories, as postulates and as common notions. The former are principles of geometry and seem to have been thought of as required assumptions because their statement opened with “let there be demanded” (ētesthō). The common notions are evidently the same as what were termed “axioms” by Aristotle,…

General Foods Corporation, former American manufacturer of packaged grocery and meat products. Since 1989, General Foods product lines have been sold by Kraft Foods Inc. The company was incorporated in 1922, having developed from the earlier Postum Cereal Co. Ltd., founded by C.W. Post (1854–1914)

Postojna, city, western Slovenia, on the Pivka River northeast of Trieste (Italy). Long a local market centre, it is on the rail line and road from Trieste to Ljubljana, the capital of Slovenia. Its prime importance is as a tourist centre for its Postojna Cave, an internationally famous cave system

Marcus Cassianius Latinius Postumus was a Roman general who, by setting himself up as an independent emperor in Gaul about 258–268, became a rival to the emperor Gallienus. Postumus and another general, Silvanus, stayed behind in Colonia (Cologne) with Gallienus’ son Saloninus after the emperor had

Luis Carlos López: …villorio (1908; “Of My Village”), Posturas dificiles (1909; “Difficult Situations”), and Por el atajo (1928; “For the Short-Cut”).

African dance: Dance posture: There are three characteristic dance postures. An upright posture with a straight back is used as an expression of authority in the dance of chiefs and priests. In the second posture the dancer inclines forward from the hips, moving his attention and gestures toward…

Jean Rhys: …followed by such novels as Postures (1928), After Leaving Mr. Mackenzie (1931), Voyage in the Dark (1934), and Good Morning, Midnight (1939).

Paleo-Siberian languages: Phonological features: …of the Paleo-Siberian languages are postvelar consonants (i.e., sounds that are formed farther back in the mouth than /k/ and usually represented as q), vowel harmony of various kinds (e.g., the alternation of e and i in the form for ‘my’ in Nivkh ñe-řla ‘my harpoon’ and ñi-řly ‘my sky’),…

Lincoln, city, seat (1853) of Logan county, central Illinois, U.S. It lies about 30 miles (50 km) northeast of Springfield. Founded in 1853, the city was named for Abraham Lincoln, then a Springfield attorney, who handled the legalities of its founding and christened it with the juice of a

myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), complex condition characterized by persistent debilitating fatigue that has no identifiable cause. Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a remarkably complex illness and remains incompletely understood. These

Piešt’any, town, southwestern Slovakia, on the Váh River, approximately 48 miles (77 km) northeast of Bratislava. Piešt’any is a Carpathian health resort, known since the Middle Ages for its warm sulfur springs and mud baths. It has specialized since the 16th century in treating rheumatic and

Ukraine: Russification: …was joined in 1933 by Pavel Postyshev as second secretary, who was sent from Moscow with a large contingent of Russian cadres. A series of purges from 1929 to 1934 largely eliminated from the party the generation of revolutionaries, supporters of Ukrainization, and those who questioned the excesses of collectivization.…

Krasnoarmiysk, city, eastern Ukraine. It is an old coal-mining centre of the Donets Basin coalfield, and mining began there in 1884. Other industries have included railway servicing and the production of construction materials. It is the centre of a significant agricultural area. Pop. (2001)

snake: Vertebrae: …at two projections (prezygapophyses and postzygapophyses) from the centra, with articulating surfaces that lie above and below; and finally the zygosphenes and zygantra, found almost exclusively in snakes, the zygosphene being a projecting shelf on the upper part of the vertebra and the zygantrum being a pocket into which the…

evolution: Reproductive isolation: …take effect before fertilization, and postzygotic, those that take effect afterward. Prezygotic RIMs prevent the formation of hybrids between members of different populations through ecological, temporal, ethological (behavioral), mechanical, and gametic isolation. Postzygotic RIMs reduce the viability or fertility of hybrids or their progeny.

evolution: Reproductive isolation: …take effect before fertilization, and postzygotic, those that take effect afterward. Prezygotic RIMs prevent the formation of hybrids between members of different populations through ecological, temporal, ethological (behavioral), mechanical, and gametic isolation. Postzygotic RIMs reduce the viability or fertility of hybrids or their progeny.

nosegay, small, hand-held bouquet popular in mid- 19th-century Victorian England as an accessory carried by fashionable ladies. Composed of mixed flowers and herbs and edged with a paper frill or greens, the arrangement was sometimes inserted into a silver filigree holder. When supplied by an

ring: …effigy of a deceased person; posy rings, upon which were engraved an inscription or a few lines of verse; occult rings, which functioned as talismans or amulets and were supposed to have magical powers; and poison rings, whose hollow bezels contained a poison for purposes of suicide or homicide. Rings…

marijuana, crude drug composed of the leaves and flowers of plants in the genus Cannabis. The term marijuana is sometimes used interchangeably with cannabis; however, the latter refers specifically to the plant genus, which comprises C. sativa and, by some classifications, C. indica and C.

cottage cheese: …soft fresh cheese, usually called pot cheese, is produced in the same manner, but the curds are strained to remove most of the whey; thus, it is drier and less creamy than cottage cheese. The name pot cheese is sometimes used to refer to cottage cheese.

industrial glass: Glass melting: …brought in the development of pot furnaces, which have remained almost unchanged even to this day. The pot furnaces were made of a plastic mixture of raw clay mixed well to remove bubbles. The pot floor was made first, before the sidewalls and the cover with a side opening were…

military technology: Mail: … with nasal evolved into the pot helm, or casque. This was an involved process, with the crown of the helmet losing its pointed shape to become flat and the nasal expanding to cover the entire face except for small vision slits and breathing holes. The late 12th-century helm was typically…

poker: Pot limit: In pot-limit contests, a player may bet or raise by no more than the amount in the pot at the time the bet or raise is made. When raising, the player may first put in the pot the number of chips required to…

calendula: Major species and uses: The pot marigold (Calendula officinalis) is grown especially for ornamental purposes and is commonly found in herbal products and cosmetics. The petal-like ray flowers are edible and are sometimes used in salads. Field marigold (C. arvensis) is native to Europe and is used similarly. Sea marigold,…

marjoram: Related species: Pot marjoram (O. onites) is also cultivated for its aromatic leaves and is used to flavor food. Oregano, or wild marjoram (O. vulgare), is a popular culinary herb native to Europe and Asia.

distilled spirit: The pot still: The simple pot still is a large enclosed vessel, heated either by direct firing on the bottom or by steam coils within the vessel, with a cylindrical bulb at its top leading to a partially cooled vapour line. The bulb and vapour line separate…

pho: …or “fire”—the French beef stew pot-au-feu is the most obvious precursor to the Vietnamese dish. However, it appears just as likely that the dish’s name evolved from the Vietnamese pronunciation of the Chinese fen, which means “flat rice noodle.”

stove: Its design influenced the potbellied stove, which was a familiar feature in some homes well into the 20th century. The first round cast-iron stoves with grates for cooking food on them were manufactured by Isaac Orr at Philadelphia, Pa., in 1800. The base-burning stove for burning anthracite coal was…

braising: …of meat is sometimes called pot-roasting.

Thomas Robert Cech: …“protection of telomeres protein” (POT1) that caps the end of a chromosome, protecting it from degradation and ensuring the maintenance of appropriate telomere length. These discoveries had major implications in understanding the underlying mechanisms of cancer, as the disease was thought to be due in large part to the…

gardening: Herb and vegetable gardens: The old French potager, the prized vegetable garden, was grown to be decorative as well as useful; the short rows with little hedges around and the high standard of cultivation represent a model of the art of vegetable growing. The elaborate parterre vegetable garden at the Château de…

Panayotis Potagos was a physician and traveler attached to the Egyptian Service who explored the Uele River system in northern Congo (Kinshasa). Potagos began his travels in 1867, visiting Iraq, Iran, Afghanistan, the Gobi (desert, in China), and India. He arrived in Egypt in 1876 and began his

Potala Palace, immense religious and administrative complex in Lhasa, southern Tibet Autonomous Region, southwestern China. It is situated atop Mar-po-ri (Red Mountain), 425 feet (130 metres) above the Lhasa River valley, and rises up dramatically from its rocky base. Potrang Karpo (completed 1648;

Gentianales: Gentianaceae: …gentians, and some species of Potalia in South America are credited with strong medicinal powers, such as remedies for poisonous snake bites.

gastropod: Classification: …families, including worm shells (Vermetidae), horn shells (Potamididae), and button shells (Modulidae). Superfamily Strombacea Foot and operculum greatly modified and move with a lurching motion; feed on algae and plants; some species used for human food; conchs (Strombidae) of tropical oceans and the pelican’s foot shells (Aporrhaidae

bush pig, (Potamochoerus porcus), African member of the family Suidae (order Artiodactyla), resembling a hog but with long body hair and tassels of hair on its ears. The bush pig lives in groups, or sounders, of about 4 to 20 animals in forests and scrub regions south of the Sahara. It is

red river hog, African hoofed mammal, a subspecies of bush pig

otter shrew: The giant otter shrew (Potamogale velox) has the body form, fur texture, and coloration of a river otter but is smaller. It weighs less than 400 grams (0.9 pound) and has a body 27 to 33 cm (11 to 13 inches) long and a slightly shorter…

otter shrew, (subfamily Potamogalinae), any of three species of amphibious and carnivorous tropical African insectivores that are not “true” shrews (family Soricidae). All are nocturnal and den in cavities and burrows in stream banks; tunnel entrances are underwater. Otter shrews have small eyes

pondweed: …Europe and southern Asia, and P. crispus, of Europe but naturalized in the eastern United States and California. Cape pondweed, or water hawthorn (Aponogeton distachyos), of the family Aponogetonaceae, is native to South Africa and is grown as an ornamental in pools and greenhouses. Many species of those families serve…

pondweed: Potamogetonaceae includes frog’s lettuce (Potamogeton densus), of Europe and southern Asia, and P. crispus, of Europe but naturalized in the eastern United States and California. Cape pondweed, or water hawthorn (Aponogeton distachyos), of the family Aponogetonaceae, is native to South Africa and is grown as an ornamental…

crab: Distribution and variety: …crab of southern Europe (the Lenten crab, Potamon fluviatile) is an example of the freshwater crabs abundant in most of the warmer regions of the world. As a rule, crabs breathe by gills, which are lodged in a pair of cavities beneath the sides of the carapace, but in the…

chondrichthyan: Annotated classification: Family Potamotrygonidae (freshwater stingrays) Like Urolophidae in most respects. 3 genera, 20 species; freshwater rivers and streams of tropical South America. Family Myliobatidae (eagle rays) Distinguished from other myliobatoids by the forepart of the head projecting

Mikhail Prokhorov: There he met Vladimir Potanin, who had worked for the foreign trade ministry and was eager to capitalize on the rapid privatization occurring as the Soviet Union collapsed in 1991.

Guyana: Drainage: …tributaries of the Essequibo, the Potaro, the Mazaruni, and the Cuyuni drain the northwest, and the Rupununi drains the southern savanna. The coast is cut by shorter rivers, including the Pomeroon, the Mahaica, the Mahaicony, and the Abary.

potash, various potassium compounds, chiefly crude potassium carbonate. The names caustic potash, potassa, and lye are frequently used for potassium hydroxide (see potassium). In fertilizer terminology, potassium oxide is called potash. Potash soap is a soft soap made from the lye leached from wood

alum: …aluminum sulfate, also known as potassium alum or potash alum, has a molecular formula of K2(SO4)·Al2(SO4)3·24H2O or KAl(SO4)2·12H2O.

hydrous mica, any of the illite group of clay minerals, including illite, bramallite (a sodium illite), and glauconite. They are structurally related to the micas; glauconite is also a member of the common-mica group. The hydrous micas predominate in shales and mudstones, but they also occur in

potassium: …element (1807) by decomposing molten potassium hydroxide (KOH) with a voltaic battery.

muscovite, abundant silicate mineral that contains potassium and aluminum. Muscovite is the most common member of the mica group. Because of its perfect cleavage, it can occur in thin, transparent, but durable sheets. Sheets of muscovite were used in Russia for windowpanes and became known as

potassium chloride (KCl), ionic compound whose molecules consist of one potassium atom and one chlorine atom. It is a white-to-colourless face-centred cubic crystal. Potassium chloride can be extracted from sylvinite, a mineral mixture of sodium chloride (halite) and potassium chloride (sylvite),

Ricky Jay was an American magician, actor, author, and historian, widely regarded as the most gifted sleight-of-hand artist of his generation. (Read Harry Houdini’s 1926 Britannica essay on magic.) He made his performing debut at age four during a backyard barbecue held by his grandfather Max Katz,

Yiddish literature: Writers in Israel: Rikudah Potash was born in Poland and moved to Palestine in 1934. She published poetry in Poland and in Israel, including the volume Moyled iber Timna (1959; “New Moon over Timna”). Both her sense of fantasy and her knowledge of art history enrich this collection…

igneous rock: Classification of volcanic and hypabyssal rocks: …subdivided into the sodic and potassic series.

potassium (K), chemical element of Group 1 (Ia) of the periodic table, the alkali metal group, indispensable for both plant and animal life. Potassium was the first metal to be isolated by electrolysis, by the English chemist Sir Humphry Davy, when he obtained the element (1807) by decomposing

alum: …aluminum sulfate, also known as potassium alum or potash alum, has a molecular formula of K2(SO4)·Al2(SO4)3·24H2O or KAl(SO4)2·12H2O.

alkali feldspar: of sodium aluminosilicate (NaAlSi3O8) and potassium aluminosilicate (KAlSi3O8). Both the sodium and potassium aluminosilicates have several distinct forms, each form with a different structure. The form stable at high temperatures is sanidine (a sodium aluminosilicate), which has a random distribution of aluminum and silicon atoms in its crystal structure. Low-temperature…

inorganic polymer: Borates: …chains of B2O42− units, whereas potassium borate, K[B5O6(OH)4] · 2H2O (commonly written as KB5O8 · 4H2O), consists of two B3O3 rings linked through a common four-coordinated boron atom. The tetraborates, B4O5(OH)42−, contain both three- and four-coordinated boron surrounded trigonally and tetrahedrally, respectively, by oxygen (O) atoms. Commercially, the

bromine: Production and use: Traces of potassium bromate (KBrO3) are added to wheat flour to improve baking. Other bromine compounds of significance include hydrogen bromide (HBr), a colorless gas used as a reducing agent and a catalyst in organic reactions. A solution of the gas in water is called hydrobromic acid,…

spectroscopy: Infrared instrumentation: … (ZnSe), cesium iodide (CsI), or potassium bromide (KBr), coated with silicon or germanium are employed. Below 200 cm−1 Mylar films of varying thickness are used to cover narrow portions of the region. Thermal detection of infrared radiation is based on the conversion of a temperature change, resulting from such radiation…

nervous system: Potassium channels: There are several types of voltage-dependent potassium channels, each having its own physiological and pharmacological properties. A single neuron may contain more than one type of potassium channel.

match: …(1) oxidizing agents, such as potassium chlorate, which supply oxygen to the igniting agent and the other combustible materials; (2) binders, such as animal glue, starches and gums, and synthetics, which bind the ingredients and are oxidized during combustion; post-combustion binders, such as ground glass, which fuse and hold the…

potassium chloride (KCl), ionic compound whose molecules consist of one potassium atom and one chlorine atom. It is a white-to-colourless face-centred cubic crystal. Potassium chloride can be extracted from sylvinite, a mineral mixture of sodium chloride (halite) and potassium chloride (sylvite),

titration: …be done is by employing potassium chromate as indicator. Potassium chromate reacts with the first slight excess silver ion to form a red precipitate of silver chromate. Another method involves the use of an adsorption indicator, the indicator action being based on the formation on the surface of the precipitate…

wet-collodion process: …of sodium thiosulfate, for which potassium cyanide was later substituted. Immediate developing and fixing were necessary because, after the collodion film had dried, it became waterproof and the reagent solutions could not penetrate it. The process was valued for the level of detail and clarity it allowed. A modification of…

gold: Compounds: Potassium cyanoaurate, K[Au(CN)2], is the basis for most gold-plating baths (the solution employed when gold is plated). Several organic compounds of gold have industrial applications. For example, gold mercaptides, which are obtained from sulfurized terpenes, are dissolved in certain organic solutions and used for decorating…

potassium deficiency, condition in which potassium is insufficient or is not utilized properly. Potassium is a mineral that forms positive ions (electrically charged particles) in solution and is an essential constituent of cellular fluids. The relationship between potassium and the metabolism of

electricity: Electro-optic phenomena: …for its Pockels effect is potassium dihydrogen phosphate, which has good optical properties and low dielectric losses even at microwave frequencies.

xanthate: …in reference to the compound potassium ethyl xanthate (C2H5OCS2K), which gives a yellow precipitate when combined with copper sulfate. The most important group of xanthates are the sodium salts produced from cellulose; these materials are processed to form the synthetic fibre rayon or the transparent film cellophane, then reconverted to…

feldspar: Chemical composition: Microcline and orthoclase are potassium feldspars (KAlSi3O8), usually designated Or in discussions involving their end-member composition. Albite (NaAlSi3O8—usually designated Ab) and anorthite (CaAl2Si2O8—An) are end-members of the plagioclase series. Sanidine, anorthoclase, and the perthites are alkali feldspars whose chemical compositions lie between Or and Ab.

blueprint: …of ferric ammonium citrate and potassium ferricyanide, which is then exposed to light. In the areas of the sensitized paper not obscured by the lines of the drawing, the light reduces the ferric salt to the ferrous state, in which it reacts with the potassium ferricyanide to form insoluble prussian…

coordination compound: History of coordination compounds: …of a sparingly soluble compound, potassium hexachloroplatinate(2−), K2[PtCl6], to refine the element platinum.

potassium: …element (1807) by decomposing molten potassium hydroxide (KOH) with a voltaic battery.

fluid: Potassium intoxication, which may follow upon kidney failure, causes reduction in the volume of urine excreted, producing symptoms much like those of potassium depletion. Treatment is by elimination of potassium-rich foods (especially fruits) and protein from the diet.

chemical compound: Binary ionic compounds: In the formulas of ionic compounds, simple ions are

potassium nitrate (KNO3), an ionic white crystalline salt made up of potassium ions and nitrate ions. Uses of potassium nitrate include the manufacture of fertilizers, pesticides, glass, fireworks, explosives, and rocket fuels. It is also used as a food preservative, and when added to meat it

ham: Sodium or potassium nitrite, which inhibits the growth of the botulism-causing bacterium Clostridium botulinum and fixes the colour of the meat, is also used in curing; these additives became the subject of controversy in the late 20th century when studies linked them to a possible carcinogen-forming process…

ozonide: …ion O-3; an example is potassium ozonide (KO3), an unstable, orange-red solid formed from potassium hydroxide and ozone that, upon heating, decomposes into oxygen and potassium superoxide (KO2).

carboxylic acid: Oxidation: …common being chromic acid (H2CrO4), potassium permanganate (KMnO4), and nitric acid (HNO3). Aldehydes are oxidized to carboxylic acids more easily (by many oxidizing agents), but this is not often useful, because the aldehydes are usually less available than the corresponding acids. Also important is the oxidation of alkyl side chains…

potassium: Principal compounds and reactions with other elements: …leather and dyeing textiles; and potassium sulfate, K2SO4, which is used in the production of fertilizers and potassium alums.

potassium: Properties, occurrence, and uses: …combustion in dry air to potassium superoxide, KO2, which is used in respiratory equipment because it liberates oxygen and removes carbon dioxide and water vapour. (The superoxide of potassium is a yellow solid consisting of K+and O2− ions. It also can be formed by oxidation of potassium amalgam with dry…

Bartter syndrome, any of several rare disorders affecting the kidneys and characterized primarily by the excessive excretion of potassium in the urine. Bartter syndrome is named after American endocrinologist Frederic Bartter, who described the primary characteristics of the disorder in the early

radioactivity: Calculation and measurement of energy: …of naturally occurring but radioactive potassium-40 is measured to be 39.964008 amu. Potassium-40 decays predominantly by β-emission to calcium-40, having a measured mass 39.962589. Through Einstein’s equation, energy is equal to mass (m) times velocity of light (c) squared, or E = mc2, the energy release (Q) and the mass…

potassium-argon dating, method of determining the time of origin of rocks by measuring the ratio of radioactive argon to radioactive potassium in the rock. This dating method is based upon the decay of radioactive potassium-40 to radioactive argon-40 in minerals and rocks; potassium-40 also decays

potassium: Properties, occurrence, and uses: …exists in the potassium-rubidium and potassium-cesium binary systems. The latter system forms an alloy melting at approximately −38 °C (−36 °F). Modification of the system by the addition of sodium results in a ternary eutectic melting at approximately −78 °C (−108 °F). The composition of this alloy is 3 percent…

drug: Renal system drugs: The potassium-sparing diuretics block the exchange processes in the distal tubule and thus prevent potassium loss. Sometimes a mixture of diuretics is used in which a thiazide is taken together with a potassium-sparing diuretic to prevent excess potassium loss. In other instances, the potassium loss may…

Māori: The rise of the King Movement: …Te Wherowhero, who reigned as Pōtatau I. In addition to electing a king, they established a council of state, a judicial system, and a police organization, all of which were intended to support Māori resolve to retain their land and to stop the intertribal warfare over the issue. Not all…

potato, (Solanum tuberosum), annual plant in the nightshade family (Solanaceae), grown for its starchy edible tubers. The potato is native to the Peruvian-Bolivian Andes and is one of the world’s main food crops. Potatoes are frequently served whole or mashed as a cooked vegetable and are also

aphid: Types of aphids: The potato aphid (Macrosiphum euphorbiae) begins as black eggs on rose plants, which hatch into pink and green young that feed on rosebuds and leaves. In early spring they migrate to potatoes, which are the summer host. One generation occurs every two to three weeks. It…

groundnut: …nut; Apois americana, also called wild bean and potato bean, the tubers of which are edible; and Lathyrus tuberosa, also called earth-nut pea. Cyperus esculentus, nut sedge or yellow nut grass, is a papyrus relative (family Cyperaceae) that also bears edible tubers, especially in the variety called chufa or earth…

potato beetle, (Lema daturaphila), species of leaf beetle that was one of the most destructive potato pests until the spread of the related Colorado potato beetle (Leptinotarsa decemlineata) in the 1850s. About 6 mm (less than 0.25 inch) long, the potato beetle is yellow with three black stripes on

late blight, disease of potato and tomato plants that is caused by the water mold Phytophthora infestans. The disease occurs in humid regions with temperatures ranging between 4 and 29 °C (40 and 80 °F). Hot dry weather checks its spread. Potato or tomato plants that are infected may rot within two

baking: Potato bread: Potato bread, another variety that can be leavened with a primary ferment, was formerly made with a sourdough utilizing the action of wild yeasts on a potato mash and producing the typical potato-bread flavour. It is now commonly prepared from a white bread…

Colorado potato beetle, (Leptinotarsa decemlineata), species of leaf beetle that is an economically important pest of potato plants. It is native to western North America and originally fed on buffalo bur, a wild plant of the potato family abundant in the Rocky Mountain region. It began feeding on

potato chip, a thin slice of potato fried in oil or baked in an oven until crisp. It may be salted or flavoured after cooking. The invention of the potato chip is attributed to George Crum, who was born George Speck in 1824, the son of an African American father and a Native American mother who was

Vincent van Gogh: The productive decade of Vincent van Gogh: (1884) and The Potato Eaters (1885). Eventually, however, he felt too isolated in Nuenen.