• Ostenso, Martha (Canadian author)

    Canadian literature: Modern period, 1900–60: Martha Ostenso’s Wild Geese (1925), a tale of a strong young girl in thrall to her cruel father, and Frederick Philip Grove’s Settlers of the Marsh (1925) and Fruits of the Earth (1933), depicting man’s struggle for mastery of himself and his land, are moving…

  • ostensorium (liturgical vessel)

    monstrance, in the Roman Catholic Church and some other churches, a vessel in which the consecrated eucharistic host (the sacramental bread) is carried in processions and is displayed during certain devotional ceremonies. Both names, monstrance and ostensorium, are derived from Latin words

  • osteoarthritis (pathology)

    osteoarthritis, disorder of the joints characterized by progressive deterioration of the articular cartilage or of the entire joint, including the articular cartilage, the synovium (joint lining), the ligaments, and the subchondral bone (bone beneath the cartilage). Osteoarthritis is the most

  • osteoarthritis of the spine (pathology)

    spondylitis: Hypertrophic spondylitis, also known as osteoarthritis of the spine, is a degenerative disease seen mostly in individuals over the age of 50. It is characterized by the destruction of intervertebral disks and the growth of spurs on the vertebrae themselves. Treatment includes rest, the application…

  • osteoarthrosis (pathology)

    osteoarthritis, disorder of the joints characterized by progressive deterioration of the articular cartilage or of the entire joint, including the articular cartilage, the synovium (joint lining), the ligaments, and the subchondral bone (bone beneath the cartilage). Osteoarthritis is the most

  • osteoblast (cell)

    osteoblast, large cell responsible for the synthesis and mineralization of bone during both initial bone formation and later bone remodeling. Osteoblasts form a closely packed sheet on the surface of the bone, from which cellular processes extend through the developing bone. They arise from the

  • Osteoblepharon osborni (reptile)

    Osborn’s dwarf crocodile, (Osteolaemus osborni), small crocodile species that inhabits the tropical forests and wetlands of Africa’s Congo River basin. The geographic range of Osborn’s dwarf crocodile extends from southeastern Cameroon and southwestern Central African Republic southward to the

  • osteochondritis dissecans (pathology)

    joint disease: Aseptic necrosis: Osteochondritis dissecans is a similar disorder in which a piece of joint cartilage and of underlying bone breaks off and lodges in the joint cavity. Usually the person affected can remember having injured the joint. The knee is the most frequent site. The condition usually…

  • osteochondroma (medicine)

    osteochondroma, solitary benign tumour that consists partly of cartilage and partly of bone. Osteochondromas are common and may develop spontaneously following trauma or may have a hereditary basis. No treatment is required unless the tumour interferes with function, in which case it should be

  • osteochondromatosis (pathology)

    osteochondroma: Osteochondromatosis (also called hereditary multiple exostosis or diaphyseal aclasis) is a relatively common disorder of skeletal development in children in which bony protrusions develop on the long bones, ribs, and vertebrae. If severe, the lesions may halt bone growth, and dwarfing will result. Pressure on…

  • osteochondrosis (osteopathology)

    osteochondrosis, relatively common temporary orthopedic disorder of children in which the epiphysis (growing end) of a bone dies and then is gradually replaced over a period of years. The immediate cause of bone death is loss of blood supply, but why the latter occurs is unclear. The most common

  • osteoclast (cell)

    osteoclast, large multinucleated cell responsible for the dissolution and absorption of bone. Bone is a dynamic tissue that is continuously being broken down and restructured in response to such influences as structural stress and the body’s requirement for calcium. The osteoclasts are the

  • osteoclastoma (medicine)

    osteoclastoma, bone tumour found predominantly at the end of long bones in the knee region, but also occurring in the wrist, arm, and pelvis. The large multinucleated cells (giant cells) found in these tumours resemble osteoclasts, for which the tumour is named. Usually seen in female adults

  • osteocyte (cell)

    osteocyte, a cell that lies within the substance of fully formed bone. It occupies a small chamber called a lacuna, which is contained in the calcified matrix of bone. Osteocytes derive from osteoblasts, or bone-forming cells, and are essentially osteoblasts surrounded by the products they

  • Osteodontokeratic tool industry

    Osteodontokeratic tool industry, assemblage of fossilized animal bones found at Taung by Raymond Arthur Dart about 200 miles (320 km) from Johannesburg, S.Af., where the first specimen of Australopithecus africanus was found, and at Makapansgat, where other specimens of A. africanus were found.

  • osteodystrophy fibrosa (disease)

    osteogenesis imperfecta (OI), rare hereditary disease of connective tissue characterized by brittle bones that fracture easily. OI arises from a genetic defect that causes abnormal or reduced production of the protein collagen, a major component of connective tissue. There are four types of OI,

  • osteogenesis imperfecta (disease)

    osteogenesis imperfecta (OI), rare hereditary disease of connective tissue characterized by brittle bones that fracture easily. OI arises from a genetic defect that causes abnormal or reduced production of the protein collagen, a major component of connective tissue. There are four types of OI,

  • osteogenic sarcoma (medicine)

    osteosarcoma, most common bone cancer, primarily affecting the long bones, particularly those in the knee, hip, or shoulder regions. The cause of osteosarcoma is unknown, but genetic factors and radiation therapy may be involved in its development. Osteosarcoma occurs more often in males than in

  • Osteoglossidae (fish)

    bony tongue, any of several heavy-bodied tropical river fishes, family Osteoglossidae, covered with large, hard, mosaic-like scales except on the head. The largest member of the family, the arapaima, paiche, or pirarucu (Arapaima gigas) of South America, may be about 2.4 metres (8 feet) long and

  • Osteoglossiformes (fish order)

    fish: Annotated classification: Osteoglossomorpha Order Osteoglossiformes (bonytongues, freshwater butterfly fishes, mooneyes, knife fishes, mormyrs) A diverse group of freshwater fishes with a relatively primitive jaw suspension and shoulder girdle. The primary bite of the mouth between parasphenoid and tongue (basihyal and glossohyal); paired rods present,

  • Osteoglossoidei (fish suborder)

    osteoglossomorph: Annotated classification: Suborder Osteoglossoidei Swim bladder not connected with skull; semicircular canals and lower part of inner ear connected; electric organs absent. Family Osteoglossidae (bonytongues and arapaimas) Fishes of diverse body form; pectoral fins not greatly enlarged, pelvic fins abdominal in position. 6 genera, about 8

  • osteoglossomorph (fish)

    osteoglossomorph, (superorder Osteoglossomorpha), any member of what is widely believed to be the most primitive group of bony fishes. This reputation stems from their rudimentary caudal skeleton and the lack of a set of intermuscular bones throughout the abdominal and anterior caudal regions of

  • Osteoglossomorpha (fish)

    osteoglossomorph, (superorder Osteoglossomorpha), any member of what is widely believed to be the most primitive group of bony fishes. This reputation stems from their rudimentary caudal skeleton and the lack of a set of intermuscular bones throughout the abdominal and anterior caudal regions of

  • Osteoglossum bicirrhosum (fish)

    arawana, (species Osteoglossum bicirrhosum), freshwater fish of tropical South America in the family Osteoglossidae (order Osteoglossiformes). Arawanas seldom reach lengths of more than 60 cm (2 feet) but are regarded as superb sports fish and highly edible. In appearance they have large scales and

  • Ostéographie des Cétacés, vivants et fossiles (work by Beneden and Gervais)

    Pierre-Joseph van Beneden: …the Belgian anatomist Paul Gervais, Ostéographie des Cétacés, vivants et fossiles (1868–80; “The Osteology of Cetaceans, Living and Fossil”).

  • osteoid (anatomy)

    bone formation: … secrete a matrix material called osteoid, a gelatinous substance made up of collagen, a fibrous protein, and mucopolysaccharide, an organic glue. Soon after the osteoid is laid down, inorganic salts are deposited in it to form the hardened material recognized as mineralized bone. The cartilage cells die out and are…

  • osteoid osteoma (pathology)

    hamartoma: Bony tumours such as osteoid osteoma, an overgrowth of bone and immature bone tissue (osteoid), may cause pain and resorption of bone during growth. Hemangiomas, which are hamartomas composed of vascular tissue, may appear quite large at birth but are usually left untreated unless they threaten facial structures. Attempts…

  • Osteolaemus osborni (reptile)

    Osborn’s dwarf crocodile, (Osteolaemus osborni), small crocodile species that inhabits the tropical forests and wetlands of Africa’s Congo River basin. The geographic range of Osborn’s dwarf crocodile extends from southeastern Cameroon and southwestern Central African Republic southward to the

  • Osteolaemus tetraspis (reptile)

    dwarf crocodile, (Osteolaemus tetraspis), the world’s smallest living crocodile species, growing to a maximum length of 1.8 meters (5.9 feet) and a maximum weight of 45.4 kg (100 pounds). The species inhabits swamps and small freshwater streams in sub-Saharan western and central Africa, from Guinea

  • Osteolaemus tetraspis osborni (reptile)

    Osborn’s dwarf crocodile, (Osteolaemus osborni), small crocodile species that inhabits the tropical forests and wetlands of Africa’s Congo River basin. The geographic range of Osborn’s dwarf crocodile extends from southeastern Cameroon and southwestern Central African Republic southward to the

  • Osteolepis (fossil fish genus)

    Osteolepis, extinct genus of lobe-finned fishes from the Late Devonian; Osteolepiformes is a variation of this name that was given to a group of vertebrates that contained the closest relatives of the tetrapods. Osteolepis survived into later Devonian time. (The Devonian Period lasted from 416

  • osteology (medicine)

    Volcher Coiter: …established the study of comparative osteology and first described cerebrospinal meningitis. Through a grant from Groningen, he studied in Italy and France and was a pupil of Fallopius, Eustachius, Arantius, and Rondelet. He became city physician of Nürnberg (1569) and later entered military service as field surgeon to Johann Casimir,…

  • osteoma (pathology)

    osteoma, small, often solitary bone tumour found mainly on bones of the skull. Osteomas usually appear in late childhood or young adulthood; they are often asymptomatic. They do not become malignant, and treatment (by excision) is necessary only if the tumour interferes with normal

  • osteomalacia (pathology)

    osteomalacia, condition in which the bones of an adult progressively soften because of inadequate mineralization of the bone. (In children the condition is called rickets.) Osteomalacia may occur after several pregnancies or in old age, resulting in increased susceptibility to fractures. Symptoms

  • osteomyelitis (pathology)

    osteomyelitis, infection of bone tissue. The condition is most commonly caused by the infectious organism Staphylococcus aureus, which reaches the bone via the bloodstream or by extension from a local injury; inflammation follows with destruction of the cancellous (porous) bone and bone marrow,

  • osteon (anatomy)

    osteon, the chief structural unit of compact (cortical) bone, consisting of concentric bone layers called lamellae, which surround a long hollow passageway, the Haversian canal (named for Clopton Havers, a 17th-century English physician). The Haversian canal contains small blood vessels responsible

  • osteonecrosis (bone tissue death)

    osteonecrosis, death of bone tissue that may result from infection, as in osteomyelitis, or deprivation of blood supply, as in fracture, dislocation, Caisson disease (decompression sickness), or radiation sickness. In all cases, blood circulation in the affected area ceases, bone cells die, and the

  • osteonecrosis occurring in children (pathology)

    avascular necrosis: Other risk factors: …disease, and the second is osteonecrosis occurring in children, which is associated with a slipped capital femoral epiphysis.

  • osteopathic medicine (health care)

    osteopathy, health care profession that emphasizes the relationship between the musculoskeletal structure and organ function. Osteopathic physicians develop skill in recognizing and correcting structural problems through manipulative therapy and other treatments. Osteopathic medicine began in the

  • osteopathy (health care)

    osteopathy, health care profession that emphasizes the relationship between the musculoskeletal structure and organ function. Osteopathic physicians develop skill in recognizing and correcting structural problems through manipulative therapy and other treatments. Osteopathic medicine began in the

  • osteopenia

    bone disease: Metabolic bone disease: …the conditions are termed, respectively, osteopenia and osteosclerosis. These terms do not imply any specific disease but simply describe the amount of bone present.

  • osteopetrosis (disease)

    marble bone disease, rare disorder in which the bones become extremely dense, hard, and brittle. The disease progresses as long as bone growth continues; the marrow cavities become filled with compact bone. Because increased bone mass crowds the bone marrow, resulting in a reduced amount of marrow

  • osteophyte (pathology)

    arthritis: Osteoarthritis: …affected joints, called osteophytes (bone spurs), are common.

  • osteoporosis (medical condition)

    osteoporosis, disease characterized by the thinning of bones, with a consequent tendency to sustain fractures from minor stresses. Osteoporosis is the most common metabolic bone disease, and its name literally means “porous bone.” The disorder is most common in postmenopausal women over age 50. It

  • osteosarcoma (medicine)

    osteosarcoma, most common bone cancer, primarily affecting the long bones, particularly those in the knee, hip, or shoulder regions. The cause of osteosarcoma is unknown, but genetic factors and radiation therapy may be involved in its development. Osteosarcoma occurs more often in males than in

  • osteosclerosis (pathology)

    bone disease: Metabolic bone disease: …are termed, respectively, osteopenia and osteosclerosis. These terms do not imply any specific disease but simply describe the amount of bone present.

  • Osteostraci (fossil vertebrate order)

    agnathan: Form and function: Some Osteostraci, for example, possessed a flattened head shield and, although possessing a powerful swimming tail, appear to have been bottom dwellers. The size and shape of the mouth suggest that they were filter feeders. The laterally compressed, fishlike form of the anaspids (such as Pharyngolepis)…

  • osteosynthesis (medicine)

    bone disease: Therapeutic and corrective measures: Internal fixation (osteosynthesis) of bone is aimed at restoration of continuity and stability during healing of a fracture, arthrodesis, or osteotomy (see below). For this purpose a variety of metal screws, pins, plates, and wires have been developed. The metal used is either stainless steel…

  • osteotomy (medicine)

    avascular necrosis: Treatment: Osteotomy is a so-called joint-sparing technique that has been used to treat primarily avascular necrosis of the femoral head. The goal of this treatment is to redistribute the weight-bearing forces to healthy cartilage and bone. Overall, osteotomies have been successful in treating late-stage disease.

  • Osterberg, James Jewel (American musician)

    the Doors: Legacy and honors: …influence on singers such as Iggy Pop, Echo and the Bunnymen’s Ian McCulloch, and Pearl Jam’s Eddie Vedder. The Doors’ releases continued to sell in the millions, and The Doors, a 1991 movie directed by Oliver Stone and starring Val Kilmer as Morrison, was a critical and popular success. The…

  • Österbotten (plain, Finland)

    Pohjanmaa, lowland plain in western Finland, along the Gulf of Bothnia. Pohjanmaa is about 60 miles (100 km) wide and 160 miles (257 km) long. It consists of flat plains of sand and clay soil that are broken by rivers and bog areas. It is drained mainly by the Lapuan, Kyrön, and Iso rivers, which

  • Østerdalen (valley, Norway)

    Østerdalen, narrow valley, Hedmark fylke (county), southeastern Norway. It extends in a general north-south direction from the eastern flanks of the Dovre Mountains and is approximately 75 miles (120 km) long. The Glomma (Glåma), Norway’s longest river, flows through the valley. Lumbering,

  • Östergötland (county, Sweden)

    Östergötland, län (county) of southeastern Sweden, between Vättern (lake) and the Baltic Sea. It consists of the landskap (province) of Östergötland and a small part of that of Södermanland. Lakes dot the countryside, which is drained by the Motala and other rivers. Although partly wooded, the

  • Osterman Weekend, The (novel by Ludlum)

    Sam Peckinpah: Later films: …based on a Robert Ludlum best seller. The thriller featured an intricate plot, which was undermined by studio cuts, but the strong cast—which included Burt Lancaster, Dennis Hopper, Rutger Hauer, and John Hurt—was able to hold viewers’ interest. Peckinpah was about to take on a crime film with a script…

  • Osterman Weekend, The (film by Peckinpah [1983])

    Sam Peckinpah: Later films: …to the big screen with The Osterman Weekend (1983), which was based on a Robert Ludlum best seller. The thriller featured an intricate plot, which was undermined by studio cuts, but the strong cast—which included Burt Lancaster, Dennis Hopper, Rutger Hauer, and John Hurt—was able to hold viewers’ interest. Peckinpah…

  • Osterman, Andrey Ivanovich, Graf (Russian statesman)

    Andrey Ivanovich, Count Osterman was a statesman who dominated the conduct of Russia’s foreign affairs from 1725 to 1740. Having come to Russia in 1703, Osterman was appointed by Peter I the Great to be an interpreter for the Russian Foreign Office (1708) and was given the rank of secretary in

  • Ostermann, Heinrich Johann Friedrich (Russian statesman)

    Andrey Ivanovich, Count Osterman was a statesman who dominated the conduct of Russia’s foreign affairs from 1725 to 1740. Having come to Russia in 1703, Osterman was appointed by Peter I the Great to be an interpreter for the Russian Foreign Office (1708) and was given the rank of secretary in

  • Ostermeyer, Micheline (French athlete and pianist)

    Micheline Ostermeyer was a French athlete who won gold medals in the shot put and the discus throw at the 1948 Olympic Games in London. She was also an accomplished concert pianist. Ostermeyer’s first love was music, and at age 14 she enrolled at the Paris Conservatory of Music. After World War II

  • Österreich

    Austria, largely mountainous landlocked country of south-central Europe. Together with Switzerland, it forms what has been characterized as the neutral core of Europe, notwithstanding Austria’s full membership since 1995 in the supranational European Union (EU). A great part of Austria’s prominence

  • Österreich unter der Enns (state, Austria)

    Niederösterreich, Bundesland (federal state), northeastern Austria. It is bordered by the Czech Republic on the north, Slovakia on the east, and by Bundesländer Burgenland on the southeast, Steiermark (Styria) on the south, and Oberösterreich (Upper Austria) on the west. Niederösterreich Bundesland

  • Österreich-Ungarn (historical empire, Europe)

    Austria-Hungary, the Habsburg empire from the constitutional Compromise (Ausgleich) of 1867 between Austria and Hungary until the empire’s collapse in 1918. A brief treatment of the history of Austria-Hungary follows. For full treatment, see Austria: Austria-Hungary, 1867–1918. The empire of

  • Österreichisch-Ungarische Monarchie (historical empire, Europe)

    Austria-Hungary, the Habsburg empire from the constitutional Compromise (Ausgleich) of 1867 between Austria and Hungary until the empire’s collapse in 1918. A brief treatment of the history of Austria-Hungary follows. For full treatment, see Austria: Austria-Hungary, 1867–1918. The empire of

  • Österreichisch-Ungarisches Reich (historical empire, Europe)

    Austria-Hungary, the Habsburg empire from the constitutional Compromise (Ausgleich) of 1867 between Austria and Hungary until the empire’s collapse in 1918. A brief treatment of the history of Austria-Hungary follows. For full treatment, see Austria: Austria-Hungary, 1867–1918. The empire of

  • Österreichische Galerie (art museum, Vienna, Austria)

    Belvedere Museum, art museum based in Vienna. It comprises two palaces, the Lower and Upper Belvedere, on the grounds of a building and garden complex that was the onetime summer residence of Eugene of Savoy, and a third site, the Belvedere 21, located a short distance away. The Lower Belvedere and

  • Österreichische Galerie Belvedere (art museum, Vienna, Austria)

    Belvedere Museum, art museum based in Vienna. It comprises two palaces, the Lower and Upper Belvedere, on the grounds of a building and garden complex that was the onetime summer residence of Eugene of Savoy, and a third site, the Belvedere 21, located a short distance away. The Lower Belvedere and

  • Österreichische Industrieholding AG (Austrian company)

    Austria: Economy: …the Republic of Austria, the Österreichische Industrieverwaltungs-Aktiengesellschaft (ÖIAG; Austrian Industrial Administration Limited-Liability Company). In 1986–89 ÖIAG was restructured to give it powers to function along the lines of a major private industry, and it was renamed Österreichische Industrieholding AG. During the 1990s, particularly after Austria joined the EU in 1995,…

  • Österreichische Industrieverwaltungs-Aktiengesellschaft (Austrian company)

    Austria: Economy: …the Republic of Austria, the Österreichische Industrieverwaltungs-Aktiengesellschaft (ÖIAG; Austrian Industrial Administration Limited-Liability Company). In 1986–89 ÖIAG was restructured to give it powers to function along the lines of a major private industry, and it was renamed Österreichische Industrieholding AG. During the 1990s, particularly after Austria joined the EU in 1995,…

  • Österreichische Nationalbank (bank, Austria)

    Austria: Finance of Austria: …the Austrian National Bank (Österreichische Nationalbank), founded in 1922. Austria was among the first group of countries to adopt the single currency of the EU, the euro, in 1999; it made the complete switch from schillings to euro notes and coins in 2002.

  • österreichische Revolution, Die (work by Bauer)

    Otto Bauer: …his Die österreichische Revolution (1923; The Austrian Revolution). He resigned in July 1919, but he remained his party’s guiding personality for the next two decades. A member of the Austrian National Council from 1929 to 1934, he went into exile after the abortive Viennese socialist revolt in 1934, first to…

  • österreichische Staats- und Reichsproblem, Das (work by Redlich)

    Joseph Redlich: …on Austria was his uncompleted Das österreichische Staats- und Reichsproblem (1920–26; “Austrian State and Imperial Problems”), a valuable history of Austrian domestic policy after 1848. His political diaries, entitled Schicksalsjahre Österreichs, 1908–1919 (“Austria’s Fateful Years, 1908–1919”), were published in 1953–54; also important is his biography of the emperor Francis Joseph…

  • Österreichische Volkspartei (political party, Austria)

    Austria: Political process: The center-right Austrian People’s Party (Österreichische Volkspartei; ÖVP), which describes itself as a “progressive center party,” is the successor of the Christian Social Party founded in the 1890s. A Christian Democratic party, it is a member of the European Union of Christian Democrats and represents a combination…

  • Österreichischer Rundfunk (Austrian corporation)

    Austria: Media and publishing: …were the monopoly of the Österreichischer Rundfunk (ORF), a state-owned corporation that enjoys political and economic independence. Several private local and regional radio stations have been licensed, although ORF still operates the country’s main radio stations. ORF also operates a number of television channels, and Austria’s terrestrial television signal was…

  • Österreichischer Werkbund (Austrian artists organization)

    Deutscher Werkbund: …grew up in Austria (Österreichischer Werkbund, 1912) and in Switzerland (Schweizerischer Werkbund, 1913). Sweden’s Slöjdföreningen was converted to the approach by 1915, and England’s Design and Industries Association (1915) also was modeled on the Deutscher Werkbund.

  • Östersjöar (work by Tranströmer)

    Tomas Tranströmer: …the setting for Östersjöar (1974; Baltics). His later works include Sanningsbarriären (1978; The Truth Barrier), Det vilda torget (1983; The Wild Marketplace), and För levande och döda (1989; For the Living and the Dead).

  • Östersjön (sea, Europe)

    Baltic Sea, arm of the North Atlantic Ocean, extending northward from the latitude of southern Denmark almost to the Arctic Circle and separating the Scandinavian Peninsula from the rest of continental Europe. The largest expanse of brackish water in the world, the semienclosed and relatively

  • Østersøen (sea, Europe)

    Baltic Sea, arm of the North Atlantic Ocean, extending northward from the latitude of southern Denmark almost to the Arctic Circle and separating the Scandinavian Peninsula from the rest of continental Europe. The largest expanse of brackish water in the world, the semienclosed and relatively

  • Östersund (Sweden)

    Östersund, town and capital of the län (county) of Jämtland, northwestern Sweden, on the west shore of Lake Stor. It was founded in 1786 by King Gustav III. It was subordinate, however, to Levanger in Norway as a trading centre for Jämtland, until the coming of the railway in 1862. Although

  • Ostfriesische Inseln (islands, Germany)

    Frisian Islands: The East Frisian Islands (German: Ostfriesische Inseln) belong to Germany and extend from the Ems River estuary eastward to Jade Channel, the outer part of Jade Bay, with two small islands, Scharhörn and Neuwerk, lying near the estuary of the Elbe River. Smaller than most of…

  • Ostfriesland (cultural region, Germany)

    East Friesland, cultural region bordering the North Sea and encompassing the coastal marshlands and East Frisian Islands (Ostfriesische Inseln) of northwestern Lower Saxony Land (state), north-central Germany. The region includes the Lower Saxony Wadden Sea National Park. East Friesland has close

  • Ostia (Italy)

    Ostia, seaport of ancient Rome, originally on the Mediterranean coast at the mouth of the Tiber River but now, because of the natural growth of the river delta, about 4 miles (6 km) upstream, southwest of the modern city of Rome, Italy. The modern seaside resort, Lido di Ostia, is about 3 miles (5

  • ostia (anatomy)

    human cardiovascular system: Blood supply to the heart: The ostium, or opening, of the right coronary artery is in the right aortic sinus and that of the left coronary artery is in the left aortic sinus, just above the aortic valve ring. There is also a non-coronary sinus of Valsalva, which lies to the…

  • Ostia Antica (Italy)

    Ostia, seaport of ancient Rome, originally on the Mediterranean coast at the mouth of the Tiber River but now, because of the natural growth of the river delta, about 4 miles (6 km) upstream, southwest of the modern city of Rome, Italy. The modern seaside resort, Lido di Ostia, is about 3 miles (5

  • ostinato (music)

    ostinato, in music, short melodic phrase repeated throughout a composition, sometimes slightly varied or transposed to a different pitch. A rhythmic ostinato is a short, constantly repeated rhythmic pattern. Ostinatos appear in Western composition from the 13th century onward, as in the motet

  • ostium (anatomy)

    human cardiovascular system: Blood supply to the heart: The ostium, or opening, of the right coronary artery is in the right aortic sinus and that of the left coronary artery is in the left aortic sinus, just above the aortic valve ring. There is also a non-coronary sinus of Valsalva, which lies to the…

  • Ostland (historical province, Europe)

    Baltic states: German occupation: …into a new territorial unit, Ostland, for which outright Germanization and eventual incorporation into the Reich was envisaged. Baltic cooperation became less forthright or ceased altogether.

  • Østlandet (region, Norway)

    Østlandet, geographic region of Norway. Encompassing the southeastern portion of the country, it ranges from the highest mountains in Norway, the Jotunheim Mountains, to coastal lowlands adjacent to the Skagerrak and Oslo Fjord. The region is quite mountainous, especially in the western and

  • Ostler, Andreas (German athlete)

    Olympic Games: Oslo, Norway, 1952: Bobsledders Andreas Ostler and Lorenz Nieberl of Germany each claimed two titles. However, their victory in the four-man was marred by controversy. The total weight of the German team in the event was over 1,000 pounds (454 kg), and other teams complained that size and momentum,…

  • Ostoih (Montenegrin literature)

    Montenegro: The arts: In that year the Ostoih (“Book of Psalms”) was printed; it is believed to be the first book printed in Cyrillic from the South Slavic region. Without question the greatest poet of the region is Petar Petrović Njegoš (Peter II), who also is celebrated widely among Serbs.

  • Ostojić, Stjepan Tomaš (ruler of Bosnia)

    Bosnia and Herzegovina: Ancient and medieval periods: …support of the Bosnian king, Stjepan Tomaš Ostojić, who summoned the clergy of the Bosnian church and ordered them to convert to Roman Catholicism or leave the kingdom. When most of the clergy converted, the back of the Bosnian church was broken.

  • ostomy (surgery)

    ostomy, (from Latin ostium, “mouth”), any procedure in which an artificial stoma, or opening, is surgically created; the term is also used for the opening itself. Usually ostomies are created through the abdominal wall to allow the discharge of bodily wastes when disease or injury has incapacitated

  • Ostorius Scapula (Roman governor of Britain)

    United Kingdom: The conquest: …succeeded as commanding officer by Ostorius Scapula, a frontier had been established from Exeter to the Humber, based on the road known as the Fosse Way; from this fact it appears that Claudius did not plan the annexation of the whole island but only of the arable southeast. The intransigence…

  • Ostpolitik (West German foreign policy)

    Ostpolitik, (German: “Eastern Policy”) West German foreign policy begun in the late 1960s. Initiated by Willy Brandt as foreign minister and then chancellor, the policy was one of détente with Soviet-bloc countries, recognizing the East German government and expanding commercial relations with

  • Ostpreussen (former province, Germany)

    East Prussia, former German province bounded, between World Wars I and II, north by the Baltic Sea, east by Lithuania, and south and west by Poland and the free city of Danzig (now Gdańsk, Poland). After World War II its territory was divided between the Soviet Union and Poland. The name Prussia is

  • ostraca (inscribed pottery fragments)

    Parthian language: …language are more than 2,000 ostraca (inscribed pottery fragments), largely records of wine deliveries dating from the 1st century bce, which were discovered in excavations (1949–58) at Nisa, an Arsacid capital near modern Ashgabat in Turkmenistan. Parthian is also attested by inscriptions of the first Sāsānian kings (224–303), which were

  • Ostraciidae (fish)

    boxfish, any of a small group of shallow-water marine fishes of the family Ostraciontidae (or Ostraciidae), distinguished by a hard, boxlike, protective carapace covering most of the body. The alternative name cowfish refers to the hornlike projections on the heads of some species. The members of

  • Ostracioidea (fish superfamily)

    tetraodontiform: Annotated classification: Superfamily Ostracioidea No dorsal spines, body encased in a turtlelike cuirass (carapace) of sutured platelike scales. Family Ostraciidae (boxfishes, trunkfishes, cowfishes) Taxonomic characteristics as per superfamily. 14 genera, about 33 species; marine, tropical. Atlantic, Pacific, and Indian oceans.

  • Ostraciontidae (fish)

    boxfish, any of a small group of shallow-water marine fishes of the family Ostraciontidae (or Ostraciidae), distinguished by a hard, boxlike, protective carapace covering most of the body. The alternative name cowfish refers to the hornlike projections on the heads of some species. The members of

  • ostracism (ancient Greek politics)

    ostracism, political practice in ancient Athens whereby a prominent citizen who threatened the stability of the state could be banished without bringing any charge against him. (A similar device existed at various times in Argos, Miletus, Syracuse, and Megara.) At a fixed meeting in midwinter, the

  • Ostracoberyx (fish genus)

    perciform: Annotated classification: 1 genus (Ostracoberyx), 3 species. Family Callanthidae Lateral line runs along dorsal fin base and ends near the tip of dorsal fin or caudal peduncle. 2 genera with 12 species. Marine, eastern Atlantic, Indian, and Pacific oceans. Families Pseudochromidae, Grammatidae, and

  • ostracod (crustacean)

    mussel shrimp, any of a widely distributed group of crustaceans belonging to the subclass Ostracoda (class Crustacea) that resemble mussels in that the body is enclosed within a bivalved (two-valved) shell. Mussel shrimp differ from most other crustaceans in having a very short trunk that has lost