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  • Pyrenees, Peace of the (France-Spain [1659])

    Peace of the Pyrenees, (Nov. 7, 1659), peace treaty between Louis XIV of France and Philip IV of Spain that ended the Franco-Spanish War of 1648–59. It is often taken to mark the beginning of French hegemony in Europe. During the years from the end of the Thirty Years’ War until 1659 Spain and

  • Pyrénées-Atlantiques (department, France)

    Aquitaine: Geography: The Basque coast in Pyrénées-Atlantique experienced a major development of leisure activity, centred on the towns of Saint-Jean-de-Luz and, especially, Biarritz. A number of small winter-sports resorts have been developed in the Pyrenees. In Dordogne many visitors travel to the valley of Vézère, one of the earliest known cradles…

  • Pyrénées-Orientales (department, France)

    Languedoc-Roussillon: Hérault, Aude, and Pyrénées-Orientales and was roughly coextensive with the former province of Languedoc. In 2016 the Languedoc-Roussillon région was joined with the région of Midi-Pyrénées to form the new administrative entity of Occitanie.

  • pyrenoid (biology)

    algae: The algal cell: The pyrenoid, a dense structure inside or beside chloroplasts of certain algae, consists largely of ribulose biphosphate carboxylase, one of the enzymes necessary in photosynthesis for carbon fixation and thus sugar formation. Starch, a storage form of glucose, is often found around pyrenoids. Microtubules, tubelike structures…

  • Pyrenulales (order of fungi)

    fungus: Annotated classification: Order Pyrenulales Parasitic, saprotrophic, or symbiotic with algae to form lichens; asci evanescent; ascospores may be pigmented; included in subclass Chaetothyriomycetidae; example genera include Pyrenula and Pyrgillus. Order Verrucariales Forms lichens on rocks and other substrates; perithecia (closed ascocarps with a pore in the top) have

  • Pyréolophore (engine)

    Nicéphore Niépce: …engine, which they called the Pyréolophore, explaining that the word was derived from a combination of the Greek words for “fire,” “wind,” and “I produce.” Working on a piston-and-cylinder system similar to 20th-century gasoline-powered engines, the Pyréolophore initially used lycopodium powder for fuel, and Niépce claimed to have used it…

  • pyrethrin (insecticide)

    poison: Insecticides: Pyrethrins are widely used insecticides in the home. They have a rapid “knockdown” for insects and have a low potential for producing toxicity in humans. The major toxicity of pyrethrins is allergy. Rotenone is a mild irritant and animal carcinogen (Table 1).

  • pyrethroid (synthetic chemical compound)

    pyrethrum: Insecticide: Synthetic pyrethrin compounds, known as pyrethroids, have been developed. Both synthetic and non-synthetic pyrethrins can accumulate in water and wetland sediments and are toxic to fish and aquatic invertebrates.

  • pyrethrum (plant)

    Pyrethrum, any of certain plant species of the aster family (Asteraceae) whose aromatic flower heads, when powdered, constitute the active ingredient in the insecticide called pyrethrin. The plants were formerly considered a separate genus, Pyrethrum, and the taxonomy remains contentious between

  • pyrethrum (insecticide)

    poison: Insecticides: Pyrethrins are widely used insecticides in the home. They have a rapid “knockdown” for insects and have a low potential for producing toxicity in humans. The major toxicity of pyrethrins is allergy. Rotenone is a mild irritant and animal carcinogen (Table 1).

  • pyrethrum daisy (plant)

    pyrethrum: Species: Dalmation pellitory, or pyrethrum daisy (Chrysanthemum cinerariifolium), is daisylike in appearance, with white ray flowers surrounding a yellow centre. The blue-gray leaves are deeply divided. The plant is native to the Balkans and is important commercially as a source of pyrethrin.

  • Pyrex (glass and glassware)

    Pyrex, (trademark), a type of glass and glassware that is resistant to heat, chemicals, and electricity. It is used to make chemical apparatus, industrial equipment, including piping and thermometers, and ovenware. Chemically, Pyrex contains borosilicate and expands only about one-third as much as

  • pyrexia (pathology)

    Fever, abnormally high body temperature. Fever is a characteristic of many different diseases. For example, although most often associated with infection, fever is also observed in other pathologic states, such as cancer, coronary artery occlusion, and certain disorders of the blood. It also may

  • Pyrgi (ancient site, Italy)

    ancient Italic people: Language and writing: …of the ancient sanctuary of Pyrgi, the port city of Caere, provide two texts, one in Etruscan and the other in Phoenician, of significant length (about 40 words) and of analogous content. They are the equivalent of a bilingual inscription and thus offer substantial data for the elucidation of Etruscan…

  • Pyrgota undata (insect)

    June beetle: …the waved light fly (Pyrgota undata). The female fly lays an egg under the beetle’s elytra, where it hatches and feeds on the beetle, eventually killing it. Some small mammals, such as moles, are known to feed on the grubs, and June beetle larvae are considered excellent fish bait.

  • pyrheliometer (instrument)

    sunlight: The Eppley pyrheliometer measures the length of time that the surface receives sunlight and the sunshine’s intensity as well. It consists of two concentric silver rings of equal area, one blackened and the other whitened, connected to a thermopile. The sun’s rays warm the blackened ring more…

  • pyribole (mineral)

    amphibole: Crystal structure: Pyribole refers to any member of the biopyribole group, excluding the sheet silicates (i.e., the pyroxenes and amphiboles together).

  • pyridazine (chemical compound)

    heterocyclic compound: Five- and six-membered rings with two or more heteroatoms: The pyridazine derivative maleic hydrazide is a herbicide, and some pyrazines occur naturally—the antibiotic aspergillic acid, for example. The structures of the aforementioned compounds are:

  • pyridine (chemical compound)

    Pyridine, any of a class of organic compounds of the aromatic heterocyclic series characterized by a six-membered ring structure composed of five carbon atoms and one nitrogen atom. The simplest member of the pyridine family is pyridine itself, a compound with molecular formula C5H5N. Pyridine is

  • pyridine-3-carboxylic acid (vitamin)

    Niacin, water-soluble vitamin of the B complex. It is also called the pellagra-preventive vitamin because an adequate amount in the diet prevents pellagra, a chronic disease characterized by skin lesions, gastrointestinal disturbance, and nervous symptoms. Niacin is interchangeable in metabolism

  • pyridinium chlorochromate (chemical compound)

    aldehyde: Synthesis of aldehydes: …have been used, most notably pyridinium chlorochromate, PCC.

  • pyridostigmine (drug)

    cholinergic drug: Neostigmine and pyridostigmine are drugs that can access the neuromuscular junction, but they cannot enter the ganglia of the autonomic nervous system and thus do not cross the blood-brain barrier. Therefore, these agents prolong the action of acetylcholine specifically at the neuromuscular junction.

  • pyridoxal (chemical compound)

    Vitamin B6, water-soluble organic compound that is an essential micronutrient for microorganisms and animals. It occurs in three forms: pyridoxine (or pyridoxol), pyridoxal, and pyridoxamine. Pyridoxine was first isolated in 1938 and synthesized in 1939. Pyridoxal and pyridoxamine, which were

  • pyridoxamine (chemical compound)

    Vitamin B6, water-soluble organic compound that is an essential micronutrient for microorganisms and animals. It occurs in three forms: pyridoxine (or pyridoxol), pyridoxal, and pyridoxamine. Pyridoxine was first isolated in 1938 and synthesized in 1939. Pyridoxal and pyridoxamine, which were

  • pyridoxine (chemical compound)

    Vitamin B6, water-soluble organic compound that is an essential micronutrient for microorganisms and animals. It occurs in three forms: pyridoxine (or pyridoxol), pyridoxal, and pyridoxamine. Pyridoxine was first isolated in 1938 and synthesized in 1939. Pyridoxal and pyridoxamine, which were

  • pyridoxol (chemical compound)

    Vitamin B6, water-soluble organic compound that is an essential micronutrient for microorganisms and animals. It occurs in three forms: pyridoxine (or pyridoxol), pyridoxal, and pyridoxamine. Pyridoxine was first isolated in 1938 and synthesized in 1939. Pyridoxal and pyridoxamine, which were

  • pyrilamine (drug)

    Daniel Bovet: …one of Bovet’s own discoveries, pyrilamine, was produced as a drug.

  • pyrimethamine (pharmacology)

    antiprotozoal drug: … sulfate, often in combination with pyrimethamine and sulfadoxine, or with artemisinin, in combination with agents such as mefloquine or amodiaquine. A high level of quinine in the plasma frequently is associated with cinchonism, a mild adverse reaction associated with such symptoms as a ringing noise in the ears (tinnitus), headache,…

  • pyrimidine (chemical compound)

    Pyrimidine, any of a class of organic compounds of the heterocyclic series characterized by a ring structure composed of four carbon atoms and two nitrogen atoms. The simplest member of the family is pyrimidine itself, with molecular formula C4H4N2. Several pyrimidine compounds were isolated

  • pyrimidine dimer (chemical structure)

    human genetic disease: Ultraviolet radiation: Such pyrimidine dimerization is mutagenic, but this damage can be repaired by an enzyme called photolyase, which utilizes the energy of longer wavelengths of light to cleave the dimers. However, people with a defect in the gene coding for photolyase develop xeroderma pigmentosum, a condition characterized…

  • pyrite (mineral)

    Pyrite, a naturally occurring iron disulfide mineral. The name comes from the Greek word pyr, “fire,” because pyrite emits sparks when struck by metal. Pyrite is called fool’s gold; to the novice its colour is deceptively similar to that of a gold nugget. Nodules of pyrite have been found in

  • pyrite structure (crystallography)

    sulfide mineral: …sodium chloride structure is the pyrite structure. This is a high-symmetry structure characteristic of the iron sulfide, pyrite (FeS2O). The second distinct structural type is that of sphalerite (ZnS), in which each metal ion is surrounded by six oppositely charged ions arranged tetrahedrally. The third significant structural type is that…

  • pyrobitumen (chemistry)

    Pyrobitumen, natural, solid hydrocarbon substance, distinguishable from bitumen (q.v.) by being infusible and insoluble. When heated, however, pyrobitumens generate or transform into bitumen-like liquid or gaseous petroleum compounds. Pyrobitumens may be either asphaltic or nonasphaltic. The

  • pyrocellulose (explosive)

    explosive: Nitrocellulosic explosives: …relatively low nitrogen content, called pyrocellulose, because that type is quite soluble in ether–alcohol. A small amount of diphenylamine was used as a stabilizer and, after forming the grains and removing the liquid, a coating of graphite was added. The smokeless powder most widely used in the United States at…

  • Pyrocephalus rubinus (bird species)

    tyrant flycatcher: A notable exception is species Pyrocephalus rubinus, found from the southwestern United States to Argentina, the male of which is fiery red with dark wings and back.

  • pyrochlore (mineral)

    Pyrochlore, a complex oxide mineral [(Na, Ca)2Nb2O6(OH,F)] composed of niobium, sodium, and calcium that forms brown to black, glassy octahedral crystals and irregular masses. Tantalum atoms replace niobium atoms in the chemical structure, so that pyrochlore forms a solid-solution series with the

  • Pyrochroidae (insect family)

    coleopteran: Annotated classification: Family Pyrochroidae (fire-coloured beetles) Adults large; found on foliage or flowers, under bark; about 100 species in north temperate region; example Pyrochroa Family Pythidae Few species widely distributed in Eurasia and America; example Pytho. Family Rhipiphoridae (

  • pyroclastic bomb (volcanic ejecta)

    Bomb, in volcanism, unconsolidated volcanic material that has a diameter greater than 64 mm (2.5 inches) and forms from clots of wholly or partly molten lava ejected during a volcanic eruption, partly solidifying during flight. The final shape is determined by the initial size, viscosity, and

  • pyroclastic breccia (geology)

    agglomerate: Upon accumulation, blocks form breccia, which are solid angular fragments larger than 64 mm.

  • pyroclastic cone (geology)

    volcano: Pyroclastic cones: Pyroclastic cones (also called cinder cones or scoria cones) such as Cerro Negro in Nicaragua are relatively small, steep (about 30°) volcanic landforms built of loose pyroclastic fragments, most of which are cinder-sized. The fragments cool sufficiently during their flight through the air…

  • pyroclastic flow (volcanism)

    Pyroclastic flow, in a volcanic eruption, a fluidized mixture of hot rock fragments, hot gases, and entrapped air that moves at high speed in thick, gray-to-black, turbulent clouds that hug the ground. The temperature of the volcanic gases can reach about 600 to 700 °C (1,100 to 1,300 °F). The

  • pyroclastic fragment (volcanism)

    mountain ecosystem: Environment: In volcanic regions tephra (erupted ash) may also contribute to soil depth and fertility.

  • pyroclastic material (volcanism)

    mountain ecosystem: Environment: In volcanic regions tephra (erupted ash) may also contribute to soil depth and fertility.

  • pyroclastic rock

    igneous rock: Clastic structures: …as such, they characterize the pyroclastic rocks. Among the plutonic rocks, they appear chiefly as local to very extensive zones of pervasive shearing, dislocation, and granulation, commonly best recognized under the microscope. Those developed prior to final consolidation of the rock are termed protoclastic; those developed after final consolidation, cataclastic.

  • pyroclastic surge (volcanism)

    pyroclastic flow: Pyroclastic surges are low-density flows that leave thin but extensive deposits with cross-bedded layering. Ash flows leave deposits known as tuff, which are made up mainly of ash-sized fragments. Nuée ardente deposits are confined mainly in valleys, while ignimbrites form plateaulike deposits that bury the…

  • pyroclastic texture (geology)

    igneous rock: Important textural types: Pyroclastic texture results from the explosive fragmentation of volcanic material, including magma (commonly the light, frothy pumice variety and glass fragments called shards), country rock, and phenocrysts. Fragments less than 2 millimetres in size are called ash, and the rock formed of these is called…

  • Pyrodictium (archaea genus)

    bacteria: Temperature: The archaea in the genus Pyrodictium thrive in the temperature range of 80 to 110 °C (176 to 230 °F), temperatures at which the water remains liquid only because of the extremely high pressures.

  • pyroelectricity (physics)

    Pyroelectricity, development of opposite electrical charges on different parts of a crystal that is subjected to temperature change. First observed (1824) in quartz, pyroelectricity is exhibited only in crystallized nonconducting substances having at least one axis of symmetry that is polar (that

  • pyrogallic acid (chemical compound)

    Pyrogallol, an organic compound belonging to the phenol family, used as a photographic film developer and in the preparation of other chemicals. Pyrogallol was first obtained in 1786 from gallic acid, obtainable from galls and barks of various trees. It is converted to pyrogallol by heating with

  • pyrogallol (chemical compound)

    Pyrogallol, an organic compound belonging to the phenol family, used as a photographic film developer and in the preparation of other chemicals. Pyrogallol was first obtained in 1786 from gallic acid, obtainable from galls and barks of various trees. It is converted to pyrogallol by heating with

  • pyrogen (biochemistry)

    human disease: Disease: signs and symptoms: …protein and polysaccharide substances called pyrogens, released either from bacteria or viruses or from destroyed cells of the body, are capable of raising the thermostat and causing a rise in body temperature. Fever is a highly significant indicator of disease.

  • Pyrola (plant)

    wintergreen: …some 12 species, commonly called shinleaf, native to the North Temperate Zone. They are creeping perennials with leaves that usually grow in a rosette at the base of the stem. Several to numerous flowers are borne in a terminal spike. The calyx (sepals, collectively) is 5-lobed; there are 5 petals…

  • Pyrola americana (plant)

    wintergreen: The flowers of round-leaved wintergreen (P. americana) are white, with widely spread petals.

  • Pyrola media (plant)

    wintergreen: The pinkish globular flowers of intermediate wintergreen (P. media) grow in a rather elongated cylindrical cluster. The flowers of round-leaved wintergreen (P. americana) are white, with widely spread petals.

  • pyroligneous acid (chemical compound)

    wood tar: Hardwood tars are obtained from pyroligneous acid, either as a deposit from the acid or as a residue from the distillation of the acid. Crude pyroligneous acid is the condensed, volatile product of wood distillation. Resinous wood tars differ from hardwood tar in containing the pleasant-smelling mixture of terpenes known…

  • pyrolite (rock)

    Pyrolite, rock consisting of about three parts peridotite and one part basalt. The name was coined to explain the chemical and mineralogic composition of the upper mantle of the Earth. The relative abundances of the principal metallic element components (except iron) are similar to those in

  • Pyrolobus fumarii (prokaryote)

    archaea: Members of the archaea include: Pyrolobus fumarii, which holds the upper temperature limit for life at 113 °C (235 °F) and was found living in hydrothermal vents; species of Picrophilus, which were isolated from acidic soils in Japan and are the most acid-tolerant organisms known—capable of growth at around pH…

  • pyrolusite (mineral)

    Pyrolusite, common manganese mineral, manganese dioxide (MnO2), that constitutes an important ore. Always formed under highly oxidizing conditions, it forms light-gray to black, metallic, moderately heavy coatings, crusts, or fibres that are alteration products of other manganese ores (e.g.,

  • pyrolysis (chemical reaction)

    Pyrolysis, the chemical decomposition of organic (carbon-based) materials through the application of heat. Pyrolysis, which is also the first step in gasification and combustion, occurs in the absence or near absence of oxygen, and it is thus distinct from combustion (burning), which can take place

  • pyromancy (occult practice)

    augury: …(geomancy), fire and smoke (pyromancy), the shoulder blades of animals (scapulimancy), entrails of sacrificed animals (haruspicy), or their livers, which were considered to be the seat of life (hepatoscopy).

  • pyromania (psychological disorder)

    Pyromania, impulse-control disorder characterized by the recurrent compulsion to set fires. The term refers only to the setting of fires for sexual or other gratification provided by the fire itself, not to arson for profit or revenge. Pyromania is usually a symptom of underlying psychopathology,

  • Pyromania (album by Def Leppard)

    Def Leppard: …it was the metal classic Pyromania (1983), with hits such as “Photograph” and “Rock of Ages” and sales of more than 10 million copies, that assured the group’s place in rock history.

  • pyrometallurgy

    Pyrometallurgy, extraction and purification of metals by processes involving the application of heat. The most important operations are roasting, smelting, and refining. Roasting, or heating in air without fusion, transforms sulfide ores into oxides, the sulfur escaping as sulfur dioxide, a gas.

  • pyrometamorphism (geology)

    rock: Rock types: …to meteorite impact events and pyrometamorphism taking place near burning coal seams ignited by lightning strikes.

  • pyrometer (measurement device)

    Pyrometer, device for measuring relatively high temperatures, such as are encountered in furnaces. Most pyrometers work by measuring radiation from the body whose temperature is to be measured. Radiation devices have the advantage of not having to touch the material being measured. Optical

  • pyromorphite (mineral)

    Pyromorphite, a phosphate mineral, lead chloride phosphate, [Pb5(PO4)3Cl], that is a minor ore of lead. It occurs with galena, cerussite, and limonite in the oxidized zone of lead deposits, where it forms very brightly coloured, heavy, barrel-shaped crystals or globular masses. For properties, see

  • Pyromys (rodent)

    mouse: General features: At one extreme are the spiny-furred species in the subgenus Pyromys, whose upperparts and undersides are covered with flat, channeled spines nestled in soft underfur (juveniles are not spiny). At the other extreme are the shrew-mice from Sumatra (M. crociduroides) and Java (M. vulcani), whose soft, short, and dense coat…

  • Pyronema (fungus genus)

    cup fungus: …name for two genera (Pyronema and Anthracobia) of the order that grow on burned wood or steamed soil.

  • pyrope (gemstone)

    Pyrope, magnesium aluminum garnet (Mg3Al2), the transparent form of which is used as a gemstone. Its colour varies from brownish red to purplish red. A beautiful, deep-red pyrope is often called ruby, in combination with the locality of occurrence, as Cape ruby from South Africa. It is also used

  • pyrophoric substance

    organometallic compound: Reduction: …spontaneously flammable in air (pyrophoric). Accordingly, techniques have been developed to handle these and other pyrophoric compounds. Glass reaction vessels sealed from the atmosphere and purged with nitrogen gas are commonly used for handling air-sensitive organometallic compounds in the laboratory. Large quantities of pyrophoric compounds such as Al2(C2H5)6 are…

  • Pyrophorus (insect genus)

    click beetle: The genus Pyrophorus, which occurs in the tropical areas of the Western Hemisphere, is luminescent, giving off a greenish and red-orange light. Several of these species can provide light sufficient for reading, and they have even been used as emergency light sources during surgery.

  • pyrophosphatase (enzyme)

    metabolism: Formation of fatty acyl coenzyme A molecules: …most tissues contain highly active pyrophosphatase enzymes [21a], which catalyze the virtually irreversible hydrolysis of inorganic pyrophosphate (PPi) to two molecules of inorganic phosphate (Pi), reaction [21] proceeds overwhelmingly to completion—i.e., from left to right.

  • pyrophosphate (chemical compound)

    isoprenoid: Tail-to-tail coupling of isoprenoids: …enzymatic reaction patterns of the pyrophosphate units (see below Biosynthesis of isoprenoids). Tail-to-tail coupling does not appear to follow expected reaction patterns. Squalene, which has the most notable example of tail-to-tail coupling, is formed by the joining of two equivalents of farnesyl pyrophosphate. In the 1960s the British chemist John…

  • pyrophyllite (mineral)

    Pyrophyllite, very soft, pale-coloured silicate mineral, hydrated aluminum silicate, Al2(OH)2 Si4O10, that is the main constituent of some schistose rocks. The most extensive commercial deposits are in North Carolina, but pyrophyllite is also mined in California, China, India, Thailand, Japan,

  • pyroracemic acid (chemical compound)

    Pyruvic acid, (CH3COCOOH), is an organic acid that probably occurs in all living cells. It ionizes to give a hydrogen ion and an anion, termed pyruvate. Biochemists use the terms pyruvate and pyruvic acid almost interchangeably. Pyruvic acid is a key product at the crossroads between the catabolism

  • Pyroscaphe (steamboat)

    Claude-François-Dorothée, marquis de Jouffroy d'Abbans: …River near Lyon in his Pyroscaphe, the first really successful steamboat.

  • pyrosilicate (mineral)

    Sorosilicate, any member of a group of compounds with structures that have two silicate tetrahedrons (each consisting of a central silicon atom surrounded by four oxygen atoms at the corners of a tetrahedron) linked together. Because one oxygen atom is shared by two tetrahedrons, the chemical

  • Pyrosoma (tunicate genus)

    bioluminescence: The range and variety of bioluminescent organisms: The genus Pyrosoma includes several species that account for the brilliant luminescence among macroplanktons of the seas, giving rise to the name “fire body.” Pyrosoma is a floating colonial form, pelagic and translucent. The colonies usually reach a length of 3 to 10 cm (about 1 to…

  • pyrosome (tunicate order)

    tunicate: Annotated classification: Order Pyrosomida Zooids embedded in a tube open at one end. Order Doliolida Complex alternation of generations between a solitary, asexually and sexually reproducing gonozooid and colonial, asexually reproducing oozooids; gill with several to many stigmata. Order Salpida

  • Pyrosomida (tunicate order)

    tunicate: Annotated classification: Order Pyrosomida Zooids embedded in a tube open at one end. Order Doliolida Complex alternation of generations between a solitary, asexually and sexually reproducing gonozooid and colonial, asexually reproducing oozooids; gill with several to many stigmata. Order Salpida

  • pyrotechnics

    arsenic: Commercial production and uses: …used in bronzing and in pyrotechnics.Very highly purified arsenic finds applications in semiconductor technology, where it is used with silicon and germanium, as well as in the form of gallium arsenide, GaAs, for diodes, lasers, and transistors.

  • pyroxene (mineral)

    Pyroxene, any of a group of important rock-forming silicate minerals of variable composition, among which calcium-, magnesium-, and iron-rich varieties predominate. Pyroxenes are the most significant and abundant group of rock-forming ferromagnesian silicates. They are found in almost every variety

  • pyroxene quadrilateral (crystallography)

    pyroxene: Chemical composition: …join is known as the pyroxene quadrilateral. Ferrous iron and magnesium substitute freely since they have similar ionic sizes and identical charges. Complete substitution exists between enstatite (Mg2Si2O6) and ferrosilite (Fe2Si2O6), and complete solid solution of iron for magnesium exists between diopside (CaMgSi2O6) and

  • pyroxene-hornfels facies (geology)

    metamorphic rock: Pyroxene-hornfels facies: Rocks of the pyroxene-hornfels facies are characteristically formed near larger granitic (granite) or gabbroic (gabbro) bodies at depths of a few kilometres or at pressures of a few hundred bars. The mineral assemblages are again largely anhydrous, but, unlike the

  • pyroxenite (rock)

    Pyroxenite, dark-coloured, intrusive igneous rock that consists chiefly of pyroxene. Pyroxenites are not abundant; they occur in discrete inclusions, in layered sills (tabular bodies inserted between other rocks) and lopoliths (laccoliths with basin-shaped bases), in branching veins, in narrow

  • pyroxylin (chemical compound)

    nitrocellulose: Chronology of development and use: …composition eventually found use as collodion, employed through the 19th century as a photographic carrier and antiseptic wound sealant.

  • Pyrrha (legendary Greek figure)

    Deucalion: …in Thessaly, and husband of Pyrrha; he was also the father of Hellen, the mythical ancestor of the Hellenic race.

  • Pyrrharctia isabella (insect)

    tiger moth: A typical arctiid, the Isabella tiger moth (Isia isabella), emerges in spring and attains a wingspan of 37 to 50 mm (1.5 to 2 inches). Black spots mark its abdomen and yellow wings. The larva, known as the banded woolly bear, is brown in the middle and black at…

  • pyrrhic foot (literature)

    prosody: Syllable-stress metres: …spondaic foot (′ ′) and pyrrhic foot (˘˘) into their scansions; however, spondees and pyrrhics occur only as substitutions for other feet, never as determinants of a metrical pattern:

  • Pyrrhic War (Roman history)

    ancient Rome: The Pyrrhic War, 280–275 bc: Rome spent the 280s bc putting down unrest in northern Italy, but its attention was soon directed to the far south as well by a quarrel between the Greek city of Thurii and a Samnite tribe. Thurii called upon the assistance…

  • pyrrhiche (dance)

    Western dance: Dance in Classical Greece: …flourished in Greece was the pyrrhichē, a weapon dance. Practiced in Sparta as part of military training, it was a basis for the claim of the philosopher Socrates that the best dancer is also the best warrior. Other choral dances that came to Athens from Crete include two dedicated to…

  • Pyrrho of Elis (Greek philosopher)

    Pyrrhon Of Elis, Greek philosopher from whom Pyrrhonism takes its name; he is generally accepted as the father of Skepticism. Pyrrhon was a pupil of Anaxarchus of Abdera and in about 330 established himself as a teacher at Elis. Believing that equal arguments can be offered on both sides of any

  • Pyrrhocorax graculus (bird)

    chough: …Isles to China, and the alpine chough (P. graculus), of high mountains from Morocco and Spain to the Himalayas. Both are about 38 cm (15 inches) long and glossy blue-black; the former is red-billed, the latter yellow-billed. These choughs are gregarious, have whistling calls, and are aerial acrobats. In the…

  • Pyrrhocorax pyrrhocorax (bird)

    chough: …Corvidae (order Passeriformes) are the common chough (Pyrrhocorax pyrrhocorax), of sea cliffs and rocky uplands from the British Isles to China, and the alpine chough (P. graculus), of high mountains from Morocco and Spain to the Himalayas. Both are about 38 cm (15 inches) long and glossy blue-black; the former…

  • pyrrhocorid bug (insect)

    Red bug, any insect of the family Pyrrhocoridae (order Heteroptera), which contains more than 300 species. The red bug—a fairly common, gregarious, plant-feeding insect found mostly in the tropics and subtropics—is oval in shape and brightly coloured with red. It ranges in length from 8 to 18 mm

  • Pyrrhocoridae (insect)

    Red bug, any insect of the family Pyrrhocoridae (order Heteroptera), which contains more than 300 species. The red bug—a fairly common, gregarious, plant-feeding insect found mostly in the tropics and subtropics—is oval in shape and brightly coloured with red. It ranges in length from 8 to 18 mm

  • Pyrrhon of Elis (Greek philosopher)

    Pyrrhon Of Elis, Greek philosopher from whom Pyrrhonism takes its name; he is generally accepted as the father of Skepticism. Pyrrhon was a pupil of Anaxarchus of Abdera and in about 330 established himself as a teacher at Elis. Believing that equal arguments can be offered on both sides of any

  • Pyrrhonian Discourses (work by Aenesidemus)

    Aenesidemus: In his Pyrrhonian Discourses Aenesidemus formulated 10 tropes in defense of Skepticism, four suggesting arguments that arise from the nature of the perceiver, two dealing with the thing perceived, and four concerning the relationship between the perceiver and the thing perceived.

  • Pyrrhonian Skepticism (philosophy)

    Pyrrhonism, philosophy of Skepticism derived from Pyrrho of Elis (c. 370–c. 272 bce), generally regarded as the founder of ancient Skepticism. He identified as wise men those who suspend judgment (practice epochē) and take no part in the controversy regarding the possibility of certain knowledge.

  • Pyrrhonism (philosophy)

    Pyrrhonism, philosophy of Skepticism derived from Pyrrho of Elis (c. 370–c. 272 bce), generally regarded as the founder of ancient Skepticism. He identified as wise men those who suspend judgment (practice epochē) and take no part in the controversy regarding the possibility of certain knowledge.

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