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. Taxonomy See also list of beetles. About 6 mm (less than 0.25 inch) long, the potato beetle is

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: , Weavers and The Potato Eaters. Eventually, however, he felt too isolated in Nuenen.

Solanaceae, the nightshade, or potato, family of flowering plants (order Solanales), with 102 genera and about 2,280 species, many of considerable economic importance as food and drug plants. Members of the Solanaceae family are found throughout the world but are most abundant and widely

population: Modern mass migrations: …the failure of the potato crop in Ireland and in the lower Rhineland, where millions had become dependent upon this single source of nutrition. These flows eventually subsided, but in the 1880s a second and even larger wave of mass migration developed from eastern and southern Europe, again stimulated in…

cereal processing: Starch from tubers: Potato flour is also produced in Germany and other countries, slices of cleaned potatoes being dried, ground, and sieved. In Germany a “potato sago” is produced. The starch cake obtained from the potatoes is crumbled to produce reasonably uniform-size particles that are rounded by tumbling…

leafhopper: The potato leafhopper (Empoasca fabae) is a destructive potato pest that causes that plant’s leaves to turn brown and curl; the insect plugs the plant’s xylem and phloem vessels, thus interfering with the transportation of food products. Adult potato leafhoppers are green with white spots on…

Solanales, potato order of flowering plants, including five families with 165 genera and more than 4,080 species. Two of the families are large and contain some of the most highly cultivated plants: Solanaceae (nightshades) and Convolvulaceae (morning glories). Solanales belongs to the core asterid

gelechiid moth: The potato tuberworm (Phthorimaea operculella) attacks potatoes, tomatoes, tobacco, and related plants, boring into tubers, burrowing in stems, and mining leaves. Pupation occurs in silken, dirt-covered cocoons, often found in plant litter. The adults are a dark mottled grayish brown.

War of the Bavarian Succession, (1778–79), conflict in which Frederick II the Great of Prussia blocked an attempt by Joseph II of Austria to acquire Bavaria. After losing Silesia to the Prussians in the 1740s (see Austrian Succession, War of the), the Austrian emperor Joseph II and his chancellor

plant disease: Nematode diseases: The golden nematode of potatoes (Heterodera rostochiensis) is a menace of the European potato industry. Great efforts have been made to control it. The speck-sized golden cysts that dot infested plant roots are the remains of female bodies. Each cyst may contain up to 500 eggs,…

Potawatomi, Algonquian-speaking tribe of North American Indians who were living in what is now northeastern Wisconsin, U.S., when first observed by Europeans in the 17th century. Their name means “people of the place of the fire.” Like many other Native peoples, the Potawatomi had slowly moved west

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…

Potchefstroom, town, North West province, South Africa, on the Mooi River, southwest of Johannesburg. It was founded in 1838 as the first capital of the Transvaal and remained the capital until Pretoria displaced it in 1855. British troops held the town in the First Boer War (1880–81) and the South

Battleship Potemkin, Soviet silent film, released in 1925, that was director Sergey M. Eisenstein’s tribute to the early Russian revolutionaries and is widely regarded as a masterpiece of international cinema. The film is based on the mutiny of Russian sailors against their tyrannical superiors

Potemkin (Russian battleship), Russian battleship built for the Black Sea fleet of the Imperial Russian Navy. It is best remembered for a 1905 mutiny by its sailors, one of the events of the Russian Revolution in the same year. The mutineers took the ship to Odesa, Ukraine, but the mutiny

Potemkin village, in its original meaning, any of a number of fake villages designed to impress the Russian empress Catherine the Great. The term has also come to be used to describe an elaborate facade designed to hide an undesirable reality. The phrase “Potemkin village” bears the name of Russian

Grigory Potemkin was a Russian army officer and statesman, for two years Empress Catherine the Great’s lover and for 17 years the most powerful man in the empire. An able administrator, licentious, extravagant, loyal, generous, and magnanimous, he was the subject of many anecdotes. Educated at the

Grigory Potemkin was a Russian army officer and statesman, for two years Empress Catherine the Great’s lover and for 17 years the most powerful man in the empire. An able administrator, licentious, extravagant, loyal, generous, and magnanimous, he was the subject of many anecdotes. Educated at the

gravity: Potential theory: …Newton was the development of potential theory, which provides the mathematical representation of gravitational fields. It allows practical as well as theoretical investigation of the gravitational variations in space and of the anomalies due to the irregularities and shape deformations of Earth.

principles of physical science: Potential: A potential function ϕ(r) defined by ϕ = A/r, where A is a constant, takes a constant value on every sphere centred at the origin. The set of nesting spheres is the analogue in three dimensions of the contours of height on a map,…

analog computer: …mid-20th century operated by manipulating potential differences (voltages). Their basic component was an operational amplifier, a device whose output current was proportional to its input potential difference. By causing this output current to flow through appropriate components, further potential differences were obtained, and a wide variety of mathematical operations, including…

potential energy, stored energy that depends upon the relative position of various parts of a system. A spring has more potential energy when it is compressed or stretched. A steel ball has more potential energy raised above the ground than it has after falling to Earth. In the raised position it

chemical bonding: The quantum mechanics of bonding: …used to construct a molecular potential energy curve, a graph that shows how the energy of the molecule varies as bond lengths and bond angles are changed. A typical curve for a diatomic molecule, in which only the internuclear distance is variable, is shown in Figure 10. The energy minimum…

hydrologic sciences: Evapotranspiration: The concept of potential evapotranspiration—the possible rate of loss without any limits imposed by the supply of water—has been an important one in the development of hydrology. Most direct measurements of rates of potential evapotranspiration are made using standard evapotranspiration pans with an open water surface. Such measurements…

fluid mechanics: Potential flow: This section is concerned with an important class of flow problems in which the vorticity is everywhere zero, and for such problems the Navier-Stokes equation may be greatly simplified. For one thing, the viscosity term drops out of it. For another, the nonlinear…

principles of physical science: Potential: A potential function ϕ(r) defined by ϕ = A/r, where A is a constant, takes a constant value on every sphere centred at the origin. The set of nesting spheres is the analogue in three dimensions of the contours of height on a map,…

pH, quantitative measure of the acidity or basicity of aqueous or other liquid solutions. The term, widely used in chemistry, biology, and agronomy, translates the values of the concentration of the hydrogen ion—which ordinarily ranges between about 1 and 10−14 gram-equivalents per litre—into

efficiency: A system is called Kaldor-Hicks efficient if resources are put in the hands of those that value them the most, measured by whether one person could theoretically compensate another for the same resources at a cost that would be worth it to them but worth more than the traded…

electrochemical reaction: Experimental studies: A third method, called the potentiodynamic, or potential sweep, method involves observations of the current as a function of the potential, while the latter is varied at a constant, known rate.

isentropic chart: …also a surface of constant potential temperature (the temperature a parcel of dry air would have if brought from its initial state to a standard pressure [1,000 millibars] without exchange of heat with its environment). The isentropic surface varies in height from place to place over the Earth, the variation…

gravity: Potential theory: …Newton was the development of potential theory, which provides the mathematical representation of gravitational fields. It allows practical as well as theoretical investigation of the gravitational variations in space and of the anomalies due to the irregularities and shape deformations of Earth.

quantum mechanics: Tunneling: …inner region of a one-dimensional potential well V(x), as shown in Figure 1. (A potential well is a potential that has a lower value in a certain region of space than in the neighbouring regions.) In classical mechanics, if E < V0 (the maximum height of the potential barrier), the…

electric potential, the amount of work needed to move a unit charge from a reference point to a specific point against an electric field. Typically, the reference point is Earth, although any point beyond the influence of the electric field charge can be used. The diagram shows the forces acting on

ethics: Aristotle: …things, Aristotle held, have inherent potentialities, which it is their nature to develop. This is the form of life properly suited to them and constitutes their goal. What, however, is the potentiality of human beings? For Aristotle this question turns out to be equivalent to asking what is distinctive about…