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  • polyetheretherketone (chemical compound)

    major industrial polymers: Polyetherketone (PEK) and polyetheretherketone (PEEK): PEK and PEEK are high-strength, radiation-resistant engineering plastics whose structures combine both ether and ketone groups. Both are thermally stable and highly resistant to chemicals. Principal uses are in machine parts, nuclear power-plant equipment, automobile parts, aerospace components, cable insulation, and pump parts.

  • polyetherimide (chemical compound)

    major industrial polymers: Polyimides: …Torlon by Amoco Corporation) and polyetherimide (PEI; trademark Ultem); these two compounds combine the imide function with amide and ether groups, respectively.

  • polyetherketone (chemical compound)

    major industrial polymers: Polyetherketone (PEK) and polyetheretherketone (PEEK): PEK and PEEK are high-strength, radiation-resistant engineering plastics whose structures combine both ether and ketone groups. Both are thermally stable and highly resistant to chemicals. Principal uses are in machine parts, nuclear power-plant equipment, automobile parts, aerospace components, cable insulation,…

  • polyethyl acrylate (chemical compound)

    major industrial polymers: Polymethyl acrylate and polyethyl acrylate: These materials are polymers of acrylic esters (CH2=CHCO2R), which have the following repeating unit structure:

  • polyethylene (chemical compound)

    Polyethylene (PE), light, versatile synthetic resin made from the polymerization of ethylene. Polyethylene is a member of the important family of polyolefin resins. It is the most widely used plastic in the world, being made into products ranging from clear food wrap and shopping bags to detergent

  • polyethylene glycol (chemical compound)

    polyether: Polyethylene glycols are water-soluble liquids or waxy solids used in cosmetic and pharmaceutical preparations and in the manufacture of emulsifying or wetting agents and lubricants. Polypropylene glycols are liquids, mostly insoluble in water, used to suppress foaming in industrial processes and for making polyurethane resins,…

  • polyethylene oxide (chemical compound)

    polyether: Polyethylene glycols are water-soluble liquids or waxy solids used in cosmetic and pharmaceutical preparations and in the manufacture of emulsifying or wetting agents and lubricants. Polypropylene glycols are liquids, mostly insoluble in water, used to suppress foaming in industrial processes and for making polyurethane resins,…

  • polyethylene terephthalamide (chemical compound)

    man-made fibre: Polyesters and polyamides: This compound, polyethylene terephthalamide, can only be spun from solution, using costly solvents; therefore, it is not made into fibres.

  • polyethylene terephthalate (chemical compound)

    Polyethylene terephthalate (PET or PETE), a strong, stiff synthetic fibre and resin, and a member of the polyester family of polymers. PET is spun into fibres for permanent-press fabrics, blow-molded into disposable beverage bottles, and extruded into photographic film and magnetic recording tape.

  • Polyeucte (play by Corneille)

    Polyeucte, Neoclassical verse tragedy in five acts by Pierre Corneille, produced about 1641–42 and published in 1643. It is known in English as Polyeuctes. With Le Cid, Horace, and Cinna, Polyeucte forms Corneille’s classical tetralogy. The title character is a recent Christian convert who would

  • polyextremophile (biology)

    extremophile: …simultaneously to multiple stresses (polyextremophile); common examples include thermoacidophiles and haloalkaliphiles.

  • polyextremophilic organism (biology)

    extremophile: …simultaneously to multiple stresses (polyextremophile); common examples include thermoacidophiles and haloalkaliphiles.

  • Polyflon (chemical compound)

    Polytetrafluoroethylene (PTFE), a strong, tough, waxy, nonflammable synthetic resin produced by the polymerization of tetrafluoroethylene. Known by such trademarks as Teflon, Fluon, Hostaflon, and Polyflon, PTFE is distinguished by its slippery surface, high melting point, and resistance to attack

  • polyformaldehyde (chemical compound)

    polymer: The simplest polyacetal is polyformaldehyde. It has a high melting point and is crystalline and resistant to abrasion and the action of solvents. Acetal resins are more like metal than are any other plastics and are used in the manufacture of machine parts such as gears and bearings.

  • polyfunctional compound (chemical compound)

    monomer: …feature of a monomer is polyfunctionality, the capacity to form chemical bonds to at least two other monomer molecules. Bifunctional monomers can form only linear, chainlike polymers, but monomers of higher functionality yield cross-linked, network polymeric products.

  • polyfunctional heterogeneous catalysis (chemistry)

    catalysis: Other catalytic compounds: The term polyfunctional heterogeneous catalysis is applied to a group of catalysts in which more than one component of the surface is active in the processes under study. One example of a bifunctional heterogeneous catalyst is the catalyst of metal (platinum or nickel) deposited on a silica-alumina…

  • polygamy (botany)

    flower: Form and types: …plant, the plant is termed polygamous.

  • polygamy (animal behaviour)

    animal social behaviour: Social interactions involving sex: Although polygamy also involves mating with multiple partners, it often refers to cases in which individuals form relatively stable associations with two or more mates. Most such species exhibit polygyny, in which males have multiple partners. Some examples include the red-winged blackbird (Agelaius phoeniceus) and house…

  • polygamy (marriage)

    Polygamy, marriage to more than one spouse at a time. The most typical forms of polygamy have been polygyny, in which cowives share a husband, or polyandry, in which cohusbands share a wife. However, same-sex marriage may instigate new forms of polygamy. The term polygamy is often used as a synonym

  • polygene (genetics)

    heredity: Polygenic inheritance: The greatest difficulties of analysis and interpretation are presented by the inheritance of many quantitative or continuously varying traits. Inheritance of this kind produces variations in degree rather than in kind, in contrast to the inheritance of discontinuous traits resulting from single genes…

  • polygenetic landform (geology)

    continental landform: The concept of periodic random dominance: …with it the implication of polygenetic landforms and landscapes where geomorphic system dominance fails to develop. Indeed, dominance becomes the special case because it is dependent on a particular juxtaposition of tectonic and/or climatic elements over a protracted interval in a given area. One estimate places polygenetic landforms over approximately…

  • polygenic character (biology)

    plant breeding: Quantitative characters: In other cases, however, plant traits grade gradually from one extreme to another in a continuous series, and classification into discrete classes is not possible. Such variability is termed quantitative. Many traits of economic importance are of this type; e.g., height, cold and…

  • polygenic inheritance (biology)

    plant breeding: Quantitative characters: In other cases, however, plant traits grade gradually from one extreme to another in a continuous series, and classification into discrete classes is not possible. Such variability is termed quantitative. Many traits of economic importance are of this type; e.g., height, cold and…

  • polygenism (natural science theory)

    race: Transforming race into species: Agassiz converted from monogenism to polygenism after moving to the United States from Switzerland in 1846. It was then that he saw blacks for the first time. He was also impressed with Morton’s work with skulls, and eventually he became the most important advocate of polygenism, conveying it in public…

  • polyglandular autoimmune syndrome (pathology)

    Polyglandular autoimmune syndrome, either of two familial syndromes in which affected patients have multiple endocrine gland deficiencies. Some patients produce serum antibodies that react with, and presumably damage, multiple endocrine glands and other tissues, and other patients produce

  • polyglot Bible

    Polyglot Bible, any of several editions of the Bible in which the text consists of translations in various languages arranged in parallel columns. This arrangement allows scholars to compare ancient and modern versions, as well as to examine closely the translation from one language to another.

  • Polyglotta Africana (work by Koelle)

    Niger-Congo languages: Classification of Niger-Congo languages: …Leone), produced his monumental work, Polyglotta Africana, in 1854. He obtained lists of 283 words in 156 languages and grouped them so as to reflect what he considered to be the relationships between the languages. Many of his language groups correspond closely to the current classification of these languages.

  • polyglycolic acid (chemical compound)

    major industrial polymers: Degradable polyesters: These include polyglycolic acid (PGA), polylactic acid (PLA), poly-2-hydroxy butyrate (PHB), and polycaprolactone (PCL), as well as their copolymers:

  • polygnathiform (paleontology)

    Polygnathiform, conodont, or small toothlike fossil of uncertain relationship found widely in ancient marine rocks, that resembles or may be derived from the genus Polygnathus, a genus found in rocks of Early Devonian to Early Carboniferous age (the Devonian Period lasted from 408 to 360 million

  • Polygnathus (conodont)

    polygnathiform: …be derived from the genus Polygnathus, a genus found in rocks of Early Devonian to Early Carboniferous age (the Devonian Period lasted from 408 to 360 million years ago and was followed by the Carboniferous Period). Polygnathus is clearly a key conodont genus; from this form a wide variety of…

  • Polygnathus costatus partitus (conodont)

    Eifelian Stage: …first occurrence of the conodont Polygnathus costatus partitus, known worldwide from Eifelian strata in Morocco, Spain, Germany, Austria, the Czech Republic, Central Asia, China, Malaysia, Australia, the U.S. states of Nevada

  • Polygnotus (Greek artist)

    Polygnotus, painter famed for his large monumental wall paintings in a severely Classical style, none of which is extant. He lived in Athens and eventually acquired citizenship. The Greek traveler Pausanias left an account of two paintings in the hall of the Cnidian at Delphi: the Iliupersis (“Sack

  • polygon (game)

    number game: Puzzles involving configurations: …popular under the name of polygon. It was invented independently in the United States in 1948 by John Nash, and a few years later one version was marketed under the name of hex.

  • polygon (mathematics)

    Polygon, In geometry, any closed curve consisting of a set of line segments (sides) connected such that no two segments cross. The simplest polygons are triangles (three sides), quadrilaterals (four sides), and pentagons (five sides). If none of the sides, when extended, intersects the polygon, it

  • Polygonaceae (plant family)

    Caryophyllales: Polygonaceae: The smartweed or buckwheat family, Polygonaceae, consists of popular vegetables and cultivated ornamentals. The most notable species is buckwheat (Fagopyrum esculentum); its edible seeds are used sometimes in flour, particularly for buckwheat pancakes, and portions of the plant are frequently included in animal feed.…

  • polygonal ground (geology)

    glacial landform: Permafrost, patterned ground, solifluction deposits, and pingos: …to their sizes to produce patterned ground. Circular arrangements of the larger rocks are termed stone rings. When neighbouring stone rings coalesce, they form polygonal stone nets. On steeper slopes, stone rings and stone nets are often stretched into stone stripes by slow downhill motion of the soggy active layer…

  • polygonal number

    number game: Polygonal and other figurate numbers: Among the many relationships of numbers that have fascinated man are those that suggest (or were derived from) the arrangement of points representing numbers into series of geometrical figures. Such numbers, known as figurate or polygonal numbers, appeared in 15th-century…

  • polygonal virus

    virus: The protein capsid: Polygonal viruses vary greatly in size, from 20 to 150 nm in diameter, essentially proportional to the size of the nucleic acid molecule coiled up inside the virion. Most, if not all, of the polygonal viruses are icosahedral; like a geodesic dome, they are formed…

  • Polygonatum (plant)

    Solomon’s seal, any plant of the genus Polygonatum of the family Ruscaceae, consisting of about 25 species of herbaceous perennials with thick, creeping underground stems and tall, drooping stems, distributed throughout the Northern Hemisphere. The plants are particularly common in the eastern

  • Polygonia interrogationis (insect)

    brush-footed butterfly: Adult anglewings show seasonal dimorphism, with the autumnal generation being hairy and lighter-coloured. Some also exhibit sexual dimorphism, with the female being less conspicuous than the male. Most species have a silvery spot on the undersurface of each hindwing. The spiny larvae feed on elm and…

  • Polygonum type (plant)

    angiosperm: Ovules: …megasporogenesis and megagametogenesis, called the Polygonum type, occurs in 70 percent of the angiosperms in which the life cycle has been charted. Variations found in the remaining 30 percent represent derivations from the Polygonum type of seed development.

  • Polygordiida (polychaete order)

    annelid: Annotated classification: by some (Nerillida, Dinophilida, Polygordiida, Protodrilida); genera include Dinophilus and Polygordius. Order Myzostomida Body disk-shaped or oval without external segmentation; external or internal commensals or parasites of echinoderms, especially crinoids; size, minute to 1 cm; genera include

  • Polygordius (polychaete genus)

    annelid: Annotated classification: genera include Dinophilus and Polygordius. Order Myzostomida Body disk-shaped or oval without external segmentation; external or internal commensals or parasites of echinoderms, especially crinoids; size, minute to 1 cm; genera include Myzostoma. Order Poeobiida Body

  • polygraph

    Lie detector, instrument for recording physiological phenomena such as blood pressure, pulse rate, and respiration of a human subject as he answers questions put to him by an operator; these data are then used as the basis for making a judgment as to whether or not the subject is lying. Used in

  • polygynandry (animal behaviour)

    animal social behaviour: Social interactions involving sex: …pattern is referred to as cooperative polygamy or polygynandry. Examples of this type of mating system include the acorn woodpecker (Melanerpes formicivorus) in western North America, the dunnock (Prunella modularis) in Europe, a few primate societies including chimpanzees (Pan troglodytes), and at least one human society, the

  • polygyny (marriage)

    Polygyny, marriage in which two or more women share a husband. Sororal polygyny, in which the cowives are sisters, is often the preferred form because sisters are thought to be more mutually supportive and less argumentative than nonsiblings. A typical rule for sororal polygyny is that the eldest

  • polygyny (animal behaviour)

    animal social behaviour: Social interactions involving sex: Most such species exhibit polygyny, in which males have multiple partners. Some examples include the red-winged blackbird (Agelaius phoeniceus) and house wren (Troglodytes aedon) in North America and the great reed warbler (Acrocephalus arundinaceus) in Europe. In a few polygamous species, however, females mate with and accept care from…

  • Polygyracea (gastropod superfamily)

    gastropod: Classification: Superfamily Polygyracea Common woodland snails of eastern North America (Polygyridae), plus a Neotropical group (Thysanophoridae) and a relict group of Asia (Corillidae). Superfamily Oleacinacea Carnivorous (Oleaciniidae) and herbivorous (

  • Polygyridae (gastropod family)

    gastropod: Classification: …of eastern North America (Polygyridae), plus a Neotropical group (Thysanophoridae) and a relict group of Asia (Corillidae). Superfamily Oleacinacea Carnivorous (Oleaciniidae) and herbivorous (Sagdidae) snails of the Neotropical region.

  • polyhalite (mineral)

    Polyhalite, a sulfate mineral in evaporite deposits [K2Ca2Mg(SO4)4·2H2O] that often occurs with anhydrite and halite. Its name, from the Greek words meaning “many salts,” reflects its composition, hydrated sulfates of potassium, calcium, and magnesium. It makes up 7 percent of the rock in the salt

  • polyhedron (geometry)

    Polyhedron, In Euclidean geometry, a three-dimensional object composed of a finite number of polygonal surfaces (faces). Technically, a polyhedron is the boundary between the interior and exterior of a solid. In general, polyhedrons are named according to number of faces. A tetrahedron has four

  • polyHEMA (chemical compound)

    PolyHEMA, a soft, flexible, water-absorbing plastic used to make soft contact lenses. It is a polymer of 2-hydroxyethyl methacrylate (HEMA), a clear liquid compound obtained by reacting methacrylic acid (CH2=C[CH3]CO2H) with ethylene oxide or propylene oxide. HEMA can be shaped into a contact lens

  • polyhexamethylene adipamide

    Nylon, any synthetic plastic material composed of polyamides of high molecular weight and usually, but not always, manufactured as a fibre. Nylons were developed in the 1930s by a research team headed by an American chemist, Wallace H. Carothers, working for E.I. du Pont de Nemours & Company. The

  • polyhexamethylene adipate (chemical compound)

    man-made fibre: Polyesters and polyamides: …a very low-melting polyester called polyhexamethylene adipate, unsuitable for fibres, is obtained. When X represents an amine group, however, a useful polyamide, polyhexamethylene adipamide (nylon 6,6), is obtained. With a melting point of 265 °C (509 °F), nylon 6,6 can be melt-spun readily into fibres employed in apparel, carpets, and…

  • Polyhistor, Lucius Cornelius Alexander (Roman philosopher, geographer, and historian)

    Alexander Polyhistor, philosopher, geographer, and historian whose fragmentary writings provide valuable information on antiquarian and Jewish subjects. Imprisoned by the Romans in the war of the Roman general Sulla against King Mithradates VI of Pontus, Alexander was sold as a slave to a patrician

  • polyhydramnios (pathology)

    Hydramnios, excess of amniotic fluid, the liquid that surrounds the fetus in the uterus. Chronic hydramnios, in which fluid accumulates slowly, is fairly common, occurring as often as once in 200 or 300 deliveries. Acute hydramnios, in which fluids collect quickly and cause rapid distention of t

  • polyhydroxybutyrate (chemical compound)

    major industrial polymers: Degradable polyesters: acid (PGA), polylactic acid (PLA), poly-2-hydroxy butyrate (PHB), and polycaprolactone (PCL), as well as their copolymers:

  • polyhydroxyether (chemical compound)

    polyether: Phenoxy resins are polyethers similar to those used in epoxies, but the polymers are of higher molecular weight and do not require curing; they are used mostly as metal primers. Polyphenylene oxide resins, such as Noryl, possess great resistance to water and to high temperatures…

  • Polyhymnia (Greek Muse)

    Polymnia, in Greek religion, one of the nine Muses, patron of dancing or geometry. She was said in some legends to have been the mother of Triptolemus, the first priest of Demeter and the inventor of agriculture, by Cheimarrhus, son of Ares, god of war, or by Celeus, king of Eleusis. In other

  • Polyhymnia caduceatrix & panegyrica (concertos by Praetorius)

    concerto: The Baroque vocal-instrumental concerto (c. 1585–1650): …several pertinent collections by Praetorius, Polyhymnia caduceatrix & panegyrica (named after the muse Polyhymnia), “containing 40 concertos of solemn peace and joy” for one to 21 or “more voices, arranged in” two to six choirs, “to be performed and used with all sorts of instruments and human voices, also trumpets…

  • polyimide (chemical compound)

    major industrial polymers: Polyimides: Polyimides are polymers that usually consist of aromatic rings coupled by imide linkages—that is, linkages in which two carbonyl (CO) groups are attached to the same nitrogen (N) atom. There are two categories of these polymers, condensation and addition. The former are made by…

  • polyisobutylene (chemical compound)

    Butyl rubber (IIR), a synthetic rubber produced by copolymerizing isobutylene with small amounts of isoprene. Valued for its chemical inertness, impermeability to gases, and weatherability, butyl rubber is employed in the inner linings of automobile tires and in other specialty applications. Both

  • polyisoprene (chemical compound)

    Polyisoprene, polymer of isoprene (C5H8) that is the primary chemical constituent of natural rubber, of the naturally occurring resins balata and gutta-percha, and of the synthetic equivalents of these materials. Depending on its molecular structure, polyisoprene can be a resilient, elastic polymer

  • Polykleitos (Greek sculptor)

    Polyclitus, Greek sculptor from the school of Árgos, known for his masterly bronze sculptures of young athletes; he was also one of the most significant aestheticians in the history of art. Polyclitus’s two greatest statues were the Diadumenus (430 bce; “Man Tying on a Fillet”) and the Doryphoros

  • Polykrikos (dinoflagellate genus)

    algae: Annotated classification: Peridinium, and Polykrikos. Division Euglenophyta Taxonomy is contentious. Primarily unicellular flagellates; both photosynthetic and heterotrophic. Class Euglenophyceae Chlorophylls a and b; paramylon stored outside chloroplasts; mitochondria with paddle-shaped cristae;

  • polylactic acid (chemical compound)

    major industrial polymers: Degradable polyesters: These include polyglycolic acid (PGA), polylactic acid (PLA), poly-2-hydroxy butyrate (PHB), and polycaprolactone (PCL), as well as their copolymers:

  • polymastigote (protist)
  • Polymatype (printing)

    Didot Family: …producing type he invented the Polymatype, which consisted of a long bar of matrices into which hot metal was poured. As many as 200 pieces of type could be cast in one operation. Léger (1767–1829) invented a papermaking machine, and the third son, called Didot le jeune, followed Henri as…

  • polymer (chemistry)

    Polymer, any of a class of natural or synthetic substances composed of very large molecules, called macromolecules, that are multiples of simpler chemical units called monomers. Polymers make up many of the materials in living organisms, including, for example, proteins, cellulose, and nucleic

  • Polymer Research Institute (American organization)

    Herman Francis Mark: …later became known as the Polymer Research Institute (the first of its kind in the United States) and continued as its director until he retired in 1964.

  • polymer-matrix composite material

    aerospace industry: Working of materials: Polymer-matrix composites are valued in the aerospace industry for their stiffness, lightness, and heat resistance (see materials science: Polymer-matrix composites). They are fabricated materials in which carbon or hydrocarbon fibres (and sometimes metallic strands, filaments, or particles) are bonded together by polymer resins in either…

  • polymerase chain reaction (biochemistry)

    Polymerase chain reaction ( PCR), a technique used to make numerous copies of a specific segment of DNA quickly and accurately. The polymerase chain reaction enables investigators to obtain the large quantities of DNA that are required for various experiments and procedures in molecular biology,

  • Polymerida (trilobite order)

    Cambrian Period: Correlation of Cambrian strata: …on members of the order Polymerida. Such trilobites usually have more than five segments in the thorax, and the order includes about 95 percent of all trilobite species. Most polymeroids, however, lived on the seafloor, and genera and species were mostly endemic to the shelves of individual Cambrian continents. Therefore,…

  • polymerization (chemical reaction)

    Polymerization, any process in which relatively small molecules, called monomers, combine chemically to produce a very large chainlike or network molecule, called a polymer. The monomer molecules may be all alike, or they may represent two, three, or more different compounds. Usually at least 100

  • polymeroid (trilobite order)

    Cambrian Period: Correlation of Cambrian strata: …on members of the order Polymerida. Such trilobites usually have more than five segments in the thorax, and the order includes about 95 percent of all trilobite species. Most polymeroids, however, lived on the seafloor, and genera and species were mostly endemic to the shelves of individual Cambrian continents. Therefore,…

  • polymethanal (chemical compound)

    polymer: The simplest polyacetal is polyformaldehyde. It has a high melting point and is crystalline and resistant to abrasion and the action of solvents. Acetal resins are more like metal than are any other plastics and are used in the manufacture of machine parts such as gears and bearings.

  • polymethyl acrylate (chemical compound)

    major industrial polymers: Acrylic polymers: Kahlbaum prepared polymethyl acrylate, and in 1901 the German chemist Otto Röhm investigated polymers of acrylic esters in his doctoral research. A flexible acrylic ester, polymethyl acrylate, was produced commercially by Rohm & Haas AG in Germany beginning in 1927 and by the Rohm and Haas Company…

  • polymethyl methacrylate (chemical compound)

    Polymethyl methacrylate (PMMA), a synthetic resin produced from the polymerization of methyl methacrylate. A transparent and rigid plastic, PMMA is often used as a substitute for glass in products such as shatterproof windows, skylights, illuminated signs, and aircraft canopies. It is sold under

  • polymethylene (chemical compound)

    major industrial polymers: Polyethylene (PE): …Bamberger and Friedrich Tschirner as polymethylene ([CH2]n), a polymer that is virtually identical to polyethylene. In 1935 the British chemists Eric Fawcett and Reginald Gibson obtained waxy, solid PE while trying to react ethylene with benzaldehyde at high pressure. Because the product had little potential use, development was slow. As…

  • polymictic lake (ecology)

    inland water ecosystem: Permanent bodies of standing fresh water: …single thermal stratification event, and polymixis, in which frequent periods of stratification occur.

  • Polymixia (fish)

    Beardfish, any of the five species of fishes in the genus Polymixia constituting the family Polymixiidae (order Polymixiiformes). Beardfishes are restricted primarily to deep-sea marine habitats in tropical and temperate regions of the Atlantic and Pacific oceans. They generally are found at depths

  • Polymixia nobilis (fish)

    beardfish: …particularly large; the widely distributed stout beardfish (P. nobilis) attains a length of less than 20 centimetres (8 inches).

  • Polymixiiformes (fish order)

    fish: Annotated classification: Polymixiomorpha Order Polymixiiformes (barbudos or beardfishes) Barbels suspended from the hypohyal bones (anterior part of the gill arches); spines on the dorsal and anal fins; pelvic fins subthoracic. Retain some primitive characters, such as an antorbital bone, a free 2nd ural centrum, 6 autogenous hypurals, 2 uroneurals,…

  • Polymixiomorpha (fish superorder)

    fish: Annotated classification: Superorder Polymixiomorpha Order Polymixiiformes (barbudos or beardfishes) Barbels suspended from the hypohyal bones (anterior part of the gill arches); spines on the dorsal and anal fins; pelvic fins subthoracic. Retain some primitive characters, such as an antorbital bone, a free 2nd ural centrum, 6 autogenous hypurals,…

  • Polymnia (Greek Muse)

    Polymnia, in Greek religion, one of the nine Muses, patron of dancing or geometry. She was said in some legends to have been the mother of Triptolemus, the first priest of Demeter and the inventor of agriculture, by Cheimarrhus, son of Ares, god of war, or by Celeus, king of Eleusis. In other

  • Polymnis (Greek Muse)

    Polymnia, in Greek religion, one of the nine Muses, patron of dancing or geometry. She was said in some legends to have been the mother of Triptolemus, the first priest of Demeter and the inventor of agriculture, by Cheimarrhus, son of Ares, god of war, or by Celeus, king of Eleusis. In other

  • polymorph (crystals)

    Polymorphism, in crystallography, the condition in which a solid chemical compound exists in more than one crystalline form; the forms differ somewhat in physical and, sometimes, chemical properties, although their solutions and vapours are identical. The existence of different crystalline or

  • polymorphic variation (biology)

    Polymorphism, in biology, a discontinuous genetic variation resulting in the occurrence of several different forms or types of individuals among the members of a single species. A discontinuous genetic variation divides the individuals of a population into two or more sharply distinct forms. The

  • polymorphism (biology)

    Polymorphism, in biology, a discontinuous genetic variation resulting in the occurrence of several different forms or types of individuals among the members of a single species. A discontinuous genetic variation divides the individuals of a population into two or more sharply distinct forms. The

  • polymorphism (crystals)

    Polymorphism, in crystallography, the condition in which a solid chemical compound exists in more than one crystalline form; the forms differ somewhat in physical and, sometimes, chemical properties, although their solutions and vapours are identical. The existence of different crystalline or

  • polymorphonuclear leukocyte (biology)

    Granulocyte, any of a group of white blood cells (leukocytes) that are characterized by the large number and chemical makeup of the granules occurring within the cytoplasm. Granulocytes are the most numerous of the white cells and are approximately 12–15 micrometres in diameter, making them larger

  • polymyalgia rheumatica (pathology)

    Polymyalgia rheumatica, joint disease that is fairly common in people over the age of 50, with an average age of onset of about 70. Out of 100,000 people over the age of 50, approximately 700 will exhibit signs of polymyalgia rheumatica. It tends to affect women twice as often as men. The syndrome

  • polymyositis (pathology)

    Polymyositis, chronic, progressive inflammation of skeletal muscles, particularly the muscles of the shoulders and pelvis. Initially muscles may be swollen slightly, and the first symptoms to appear are usually muscle weakness and sometimes pain. A weakening of muscles close to the torso is common.

  • polymyxin (drug)

    Polymyxin, any of five polypeptide antibiotics derived from various species of soil bacterium in the genus Bacillus that are active against gram-negative bacteria such as Escherichia coli and Pseudomonas aeruginosa. Polymyxins disrupt the cell membranes of bacteria, destroying their ability to

  • polymyxin B (drug)

    polymyxin: Only polymyxins B and E are used clinically. Their chief therapeutic use is in the treatment of infections involving gram-negative bacteria that are resistant to penicillin and other broad-spectrum antibiotics. Polymyxin B is applied topically to treat infections such as those of the eye, the ear,…

  • polymyxin E (drug)

    polymyxin: Only polymyxins B and E are used clinically. Their chief therapeutic use is in the treatment of infections involving gram-negative bacteria that are resistant to penicillin and other broad-spectrum antibiotics. Polymyxin B is applied topically to treat infections such as those of the eye, the ear, the skin, and…

  • Polyneices (Greek mythology)

    Antigone: …city and his crown, and Polyneices, who was attacking Thebes. Both brothers, however, were killed, and their uncle Creon became king. After performing an elaborate funeral service for Eteocles, he forbade the removal of the corpse of Polyneices, condemning it to lie unburied, declaring him to have been a traitor.…

  • Polynemidae (fish)

    Threadfin, any of about 41 species of marine fishes of the family Polynemidae (order Perciformes), widely distributed along warm seashores, often over sand. Threadfins have two well-separated dorsal fins and a forked tail, and are usually silvery in colour. Their name refers to their pectoral

  • Polynesia (cultural region, Pacific Ocean)

    Polynesian culture, the beliefs and practices of the indigenous peoples of the ethnogeographic group of Pacific Islands known as Polynesia (from Greek poly ‘many’ and nēsoi ‘islands’). Polynesia encompasses a huge triangular area of the east-central Pacific Ocean. The triangle has its apex at the

  • Polynesia Farani

    French Polynesia, overseas collectivity of France consisting of five archipelagoes in the south-central Pacific Ocean. Included are some 130 islands scattered across the Pacific between latitudes 7° and 27° S and longitudes 134° and 155° W—a total land area roughly equivalent to that of

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