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  • open vascular system (anatomy)
    ...distance from either the coelom or the outside. A muscular pump attached to muscular vessels has arisen in larger animals to move the interstitial fluid surrounding the cells. Most animals have open circulatory systems. Those few animals with closed circulatory systems have a continuous series of vessels to circulate fluid to the vicinity of all cells, whereas those with open systems have......
  • open vowel (linguistics)
    The Thai tones are as follows: level (using no diacritic), low (using a grave accent), falling (using a circumflex), high (using an acute accent), and rising (using a wedge, or haček); for example, maa (with no diacritic) ‘to come,’ màak (with a grave accent) ‘areca nut,’ mâak (with a circumflex)......
  • open web joist (construction)
    ...deep and 60 centimetres (24 inches) wide. They are usually welded to the supporting steel members and can span up to 4.5 metres (15 feet). The lightest and most efficient structural shape is the bar (or open web) joist, a standard truss made with angles for the top and bottom chords, joined by welding to a web made of a continuous bent rod. It is used almost exclusively to support roofs and......
  • open windrow composting
    Pulverized waste is ready for composting either by the open windrow method or in an enclosed mechanical facility. Windrows are long, low mounds of refuse. They are turned or mixed every few days to provide air for the microbes digesting the organics. Depending on moisture conditions, it may take five to eight weeks for complete digestion of the waste. Because of the metabolic action of aerobic......
  • Open Work, The (work by Eco)
    ...of Bologna. His initial studies and researches were in aesthetics, his principal work in this area being Opera aperta (1962; rev. ed. 1972, 1976; The Open Work), which suggests that in much modern music, Symbolist verse, and literature of controlled disorder (Franz Kafka, James Joyce) the messages are fundamentally ambiguous and invite......
  • open-air museum
    ...housing cultural material to which the public had access. Later, as museums continued to respond to the societies that created them, the emphasis on the building itself became less dominant. Open-air museums, comprising a series of buildings preserved as objects, and ecomuseums, involving the interpretation of all aspects of an outdoor environment, provide examples of this. In addition,......
  • Open-Air Theatre (theatre, Lahore, Pakistan)
    ...the centre of amateur theatre based on the tradition of the late directors A.S. Bokhari and G.D. Sondhi, both former principals of the Government College in Lahore. In 1942 G.D. Sondhi built the Open-Air Theatre, situated on a small artificial hillock in the Lawrence Gardens and perhaps the best in all of South Asia. It has remained the centre of dramatic contests and festivals and is a......
  • open-air theatre
    ...one end of the square with an inner stage at the back. Very little scenery was used, though there were trapdoors in the floor and machinery above for “flying” people or objects. The theatre was open to the sky, but an awning could be drawn over the audience to provide protection against sunlight and rain. It was a stage well adapted for rhetoric and poetry, where the imagination.....
  • open-bid buying (business)
    Government purchasing procedures fall into two categories: the open bid and the negotiated contract. Under open-bid buying, the government disseminates very specific information about the products and services required and requests bids from suppliers. Contracts generally are awarded to the lowest bidder. In negotiated-contract buying, a government agency negotiates directly with one or more......
  • open-billed stork (bird)
    Two open-billed storks, openbills, or shell storks, Anastomus lamelligerus of tropical Africa and A. oscitans of southern Asia, are small storks that eat water-snails. When the mandibles of these birds are closed, a wide gap remains except at the tips, probably an adaptation for holding snails....
  • open-centre system (horticulture)
    ...stem from which branches form. In the central-leader system of training, the trunk forms a central axis with branches distributed laterally up and down and around the stem. In the open-centre or vase system the main stem is terminated and growth forced through a number of branches originating close to the upper end of the trunk. An intermediate system is called the modified-leader system. In......
  • open-cycle gas-turbine engine
    Most gas turbines operate on an open cycle in which air is taken from the atmosphere, compressed in a centrifugal or axial-flow compressor, and then fed into a combustion chamber. Here, fuel is added and burned at an essentially constant pressure with a portion of the air. Additional compressed air, which is bypassed around the burning section and then mixed with the very hot combustion gases,......
  • open-cycle MHD power-generating system (energy technology)
    ...the MHD generator (a process known as topping) and then on to the turbogenerator of a conventional steam plant (the bottoming phase). An MHD power plant employing such an arrangement is known as an open-cycle, or once-through, system....
  • open-cycle OTEC system (energy technology)
    Some researchers have centred their attention on an open-cycle OTEC system that employs water vapour as the working fluid and dispenses with the use of a refrigerant. In this kind of system warm surface seawater is partially vaporized as it is injected into a near vacuum. The resultant steam is expanded through a low-pressure steam turbogenerator to produce electric power. Cold seawater is used......
  • open-die forging (metallurgy)
    Open-die forging is usually done by hammering a part between two flat faces. It is used to make parts that are too big to be formed in a closed die or in cases where only a few parts are to be made and the cost of a die is therefore unjustified. The earliest forging machines lifted a large hammer that was then dropped on the work, but now air- or steam-driven hammers are used, since these allow......
  • open-end trust (finance)
    company that invests the funds of its subscribers in diversified securities and in return issues units representing shares in those holdings. It differs from the investment trust, which issues shares in its own capital. In contrast to closed-end investment companies, which have a fixed capitalization and whose shares are bought and sold by the investor in the market, mutual fund...
  • open-end wrench (tool)
    ...a pull on the wrench at right angles to the axes of the lever and the bolt or nut. Some wrenches have ends with straight-sided slots that fit over the part being tightened; these tools are known as open-end wrenches and are made in various sizes to fit specific bolt and nut sizes....
  • open-face-wheel mole (tunnel machine)
    The open-face-wheel type is probably the most common. In the wheel the cutter arm rotates in one direction; in a variant model it oscillates back and forth in a windshield-wiper action that is most suitable in wet, sticky ground. While suitable for firm ground, the open-face mole has sometimes been buried by running or loose ground....
  • open-field system (agriculture)
    basic community organization of cultivation in European agriculture for 2,000 years or more. Its best-known medieval form consisted of three elements: individual peasant holdings in the form of strips scattered among the different fields; crop rotation; and common grazing. Crop rotation was by the two-field system in the earlier age and by the three-...
  • open-heart surgery
    any surgical procedure that requires an incision into the heart, thus exposing one or more of the cardiac chambers, or requires the use of a heart-lung machine, a device that allows circulation and oxygenation of the blood to be maintained outside the patient’s body. The most-common open-heart procedures are for repair of valvular disease and for correc...
  • open-hearth furnace (metallurgy)
    ...or 1,600° C) was high enough to permit melting steel for the first time, producing a homogeneous metal of uniform composition that he used to manufacture watch and clock springs. After 1870 the Siemens regenerative gas furnace replaced the coke-fire furnace; it produced even higher temperatures. The Siemens furnace had a number of combustion holes, each holding several crucibles, and hea...
  • open-hearth process (metallurgy)
    steelmaking technique that for most of the 20th century accounted for the major part of all steel made in the world. William Siemens, a German living in England in the 1860s, seeking a means of increasing the temperature in a metallurgical furnace, resurrected an old proposal for using the waste heat given off by the furnace; directing the fumes from the furnace through a brick ...
  • open-market operation (economics)
    any of the purchases and sales of government securities and sometimes commercial paper by the central banking authority for the purpose of regulating the money supply and credit conditions on a continuous basis. Open-market operations can also be used to stabilize the prices of government securities, an aim that conflicts at times with the credit policies of the central bank. W...
  • open-ocean polynya (oceanography)
    ...They are thought to be caused chiefly by persistent local offshore winds, such as the foehn, or katabatic (downward-driving), winds typically found off the coasts of Greenland and Antarctica. Open-ocean polynyas, the larger and longer-lasting of the two types, form within the ice cover and are believed to be caused by the upwelling of deep warmer water. This type is best exemplified by......
  • open-pit mining
    surface mining to obtain minerals other than coal....
  • open-plan teaching (education)
    ...available, including library and laboratory facilities and various educational hardware (see below Instructional media). In the infant and primary schools, similar ideas are introduced in the open-plan system. At both the primary and the secondary levels, however, there is insufficient evidence on the effectiveness of the systems. The attitude and action of the teacher remains the......
  • open-range zoo
    A number of open-range zoos have been established since the early 1930s in rural surroundings. The prototype is Whipsnade Park, established by the Zoological Society of London in 1932. Fewer species of animals are exhibited in such zoos than in urban zoos, but they are kept in more natural conditions in large paddocks. Animals are confined by a variety of methods including water-filled moats,......
  • open-reel recorder (audio equipment)
    The principal tape-recording formats are the open reel and cassette. Open-reel recorders, which were the first to be developed, are now used most commonly for professional recording. They operate at several speeds and have great flexibility, including the ability to record up to 24 separate tracks. A cassette consists of a feed reel of tape and a take-up hub enclosed in a sealed rectangular......
  • open-system pingo (geology)
    ...to latitudes of 65° to 75° N. Rupture of the overlying material at the top of the pingo exposes the ice to melting and may create a smaller crater and lake. Two types are recognized, the open-system pingo and the closed-system pingo....
  • open-top car (railroad vehicle)
    ...completely replaced the wooden variety. Modern freight cars vary widely in shape and size, but virtually all of them evolved from three basic types that had been in use since the early 1800s: the open-top car, the boxcar, and the flatcar....
  • open-tubular column (instrument)
    ...same time, detectors with extremely low limits of detection became available, which could sense the small sample sizes required by these new columns. These capillary, or Golay, columns, now called open-tubular columns and characterized by their open design and an internal diameter of less than one millimetre, had an explosive impact on chromatographic methodology. It is now possible to......
  • open-wire pair (communications)
    In order to overcome the insufficiencies of single-wire transmission, the early telephone industry shifted to a two-wire system called the open-wire pair. In an open-wire pair the forward and return conductors are copper wires that run in parallel and in a common plane. The parallel arrangement produces a balanced transmission circuit that has low sensitivity to faraway interference sources......
  • open-wire transmission line (communications)
    In order to overcome the insufficiencies of single-wire transmission, the early telephone industry shifted to a two-wire system called the open-wire pair. In an open-wire pair the forward and return conductors are copper wires that run in parallel and in a common plane. The parallel arrangement produces a balanced transmission circuit that has low sensitivity to faraway interference sources......
  • openbill (bird)
    Two open-billed storks, openbills, or shell storks, Anastomus lamelligerus of tropical Africa and A. oscitans of southern Asia, are small storks that eat water-snails. When the mandibles of these birds are closed, a wide gap remains except at the tips, probably an adaptation for holding snails....
  • opencast mining
    surface mining to obtain minerals other than coal....
  • opencut mining
    surface mining to obtain minerals other than coal....
  • OpenGL (computer science)
    Computer graphics relies heavily on standard software packages. The OpenGL (open graphics library) specifies a standard set of graphics routines that may be implemented in computer programming languages such as C or Java. PHIGS (programmer’s hierarchical interactive graphics system) is another set of graphics routines. VRML (virtual reality modeling language) is a graphics description langu...
  • opening (chess)
    At the heart of Hypermodernism was a new approach to the opening. The two leading members of the new school, Réti and Nimzowitsch, attacked Tarrasch’s emphasis on building a solid centre in the first dozen moves, starting with 1 e4 or 1 d4. Réti often began a game with 1 Nf3 and did not advance more than one pawn past the third before the middlegame had begun. Instead, he and ...
  • opening of the mouth (Egyptian religious ceremony)
    ...of a dead person to Osiris and the ritual enacting of what the gods had done would achieve a similar miracle of resurrection. One of the most significant of these ritual transactions was the “opening of the mouth,” which was designed to restore to the mummified body its ability to see, breathe, and take nourishment....
  • Opening, The (Ohio, United States)
    city, seat (1840) of Lake county, northeastern Ohio, U.S., near the mouth of the Grand River and Lake Erie, 25 miles (40 km) northeast of Cleveland. The site, first settled permanently by Gen. Edward Paine with a party of 66, was laid out around 1805; it was known variously as The Opening, Oak Openings, and Champion (for Henry Champion, original owner of the plot). In 1816 the c...
  • Openluchtmuseum (museum, Arnhem, The Netherlands)
    ...display structures and customs of their more recent past. Examples, following Sweden’s pioneering reerection of significant buildings, include the open-air museums at Arnhem in The Netherlands (the Open Air Museum, opened in 1912) and at Cardiff, Wales (the Welsh Folk Museum, opened in 1947). The preservation and restoration of buildings or entire settlements in situ also began; particul...
  • “Oper und Drama” (work by Wagner)
    ...the Future), Eine Mitteilung an meine Freunde (A Communication to My Friends), and Oper und Drama (Opera and Drama). The latter outlined a new, revolutionary type of musical stage work—the vast work, in fact, on which he was engaged. By 1852 he had added to the poem of ......
  • Opéra (opera house, Paris, France)
    Parisian opera house designed by Charles Garnier. The building, considered one of the masterpieces of the Second Empire style, was begun in 1861 and opened with an orchestral concert on Jan. 5, 1875. The first opera performed there was Fromental Halévy’s work La Juive on Jan. 8, 1875. A second Parisian opera house, the Opéra Bastille, was inaugurated in 1989. Both opera...
  • opera (music)
    a drama set to music and made up of vocal pieces with orchestral accompaniment and with orchestral overtures and interludes. In some operas, such as those by Richard Wagner, the music is continuous throughout an act; in others, it is broken up either by recitative (which is more like sung speech) or by dialogue. This article focuses on opera in the Western tra...
  • Opera and Drama (work by Wagner)
    ...the Future), Eine Mitteilung an meine Freunde (A Communication to My Friends), and Oper und Drama (Opera and Drama). The latter outlined a new, revolutionary type of musical stage work—the vast work, in fact, on which he was engaged. By 1852 he had added to the poem of ......
  • “Opera aperta” (work by Eco)
    ...of Bologna. His initial studies and researches were in aesthetics, his principal work in this area being Opera aperta (1962; rev. ed. 1972, 1976; The Open Work), which suggests that in much modern music, Symbolist verse, and literature of controlled disorder (Franz Kafka, James Joyce) the messages are fundamentally ambiguous and invite......
  • opéra bouffe (French music)
    ...in opera buffa. The earliest opera buffa still regularly performed is Giovanni Battista Pergolesi’s La serva padrona (1733; The Maid as Mistress). Opera buffa is distinct from French opéra-bouffe, a general term for any light opera....
  • opera buffa (Italian music)
    genre of comic opera originating in Naples in the mid-18th century. It developed from the intermezzi, or interludes, performed between the acts of serious operas. Opera buffa plots centre on two groups of characters: a comic group of male and female personages and a pair (or more) of lovers. The dialogue is sung. The operatic finale, a long, formally organized conclusion to an opera act, including...
  • Opera Company of Boston (American opera company)
    ...Riders to the Sea in 1947. She headed the Boston University Opera Workshop from 1952 to 1960, and in 1957 she founded a permanent opera group, which eventually became known as the Opera Company of Boston, for that city; the company closed in the early 1990s owing to financial difficulties....
  • Opera dei Congressi (Italian organization)
    ...forbade Catholics to vote in parliamentary elections or to become candidates, and appointed a new generation of “intransigent” bishops. New laymen’s organizations were founded; the Opera dei Congressi, with committees at parish level, became the focus of Catholic resistance to the new state. It organized cooperatives, welfare insurance, credit banks and mutual aid societies...
  • Opera Geometrica (work by Torricelli)
    ...because he was too deeply involved in the study of pure mathematics—including calculations of the cycloid, a geometric curve described by a point on the rim of a turning wheel. In his Opera Geometrica (1644; “Geometric Works”), Torricelli included his findings on fluid motion and projectile motion....
  • opera glass (optical instrument)
    Opera glasses and field glasses are binoculars with simple, often inexpensive lens systems and narrow fields of view and are usually made with magnifications of 2.5× to 5×. The lenses used in most binoculars are coated on some or all of their air-to-glass surfaces to reduce reflections....
  • Opera House (building, East Berlin, Berlin, Germany)
    The new Opera House (Deutsche Oper Berlin) was opened in West Berlin in 1961, and it quickly established a position as one of the leading opera houses of the Western world. The Opera House in East Berlin, destroyed in World War II, was rebuilt in 1951; it is home to the long-established Deutsche Staatsoper (German National Opera). East Berlin’s Comic Opera also gained fame. Classical music ...
  • opera house (building)
    There were two kinds of public theatre in the 18th century. One was a logical development of the earlier private court theatres, reflecting a sophisticated, urban, aristocratic demand for theatre as entertainment. The Teatro alla Scala (1776–78) in Milan is a good example of the numerous theatres erected by 18th-century nobility in the capitals of Europe. Public theatres such as La Scala......
  • Opera House (building, West Berlin, Berlin, Germany)
    The new Opera House (Deutsche Oper Berlin) was opened in West Berlin in 1961, and it quickly established a position as one of the leading opera houses of the Western world. The Opera House in East Berlin, destroyed in World War II, was rebuilt in 1951; it is home to the long-established Deutsche Staatsoper (German National Opera). East Berlin’s Comic......
  • Opera House (building, Cairo, Egypt)
    ...also the site of the region’s major religious and cultural institutions. During the 19th century a number of European cultural institutions, such as theatres, were introduced. The original Baroque Opera House, situated on Opera Square in downtown Cairo, was destroyed by fire in 1971; it was replaced by a modern structure on the southern tip of Jazīrah, completed in 1988....
  • Opera House (opera house, Paris, France)
    Parisian opera house designed by Charles Garnier. The building, considered one of the masterpieces of the Second Empire style, was begun in 1861 and opened with an orchestral concert on Jan. 5, 1875. The first opera performed there was Fromental Halévy’s work La Juive on Jan. 8, 1875. A second Parisian opera house, the Opéra Bastille, was inaugurated in 1989. Both opera...
  • Opera Orchestra of New York (orchestra, New York City, New York, United States)
    In order to gain the opportunity to conduct professionally, Queler organized in 1967 the Opera Orchestra of New York, which also provided experience to instrumentalists and young singers. Their performances of L’incoronazione di Poppea and Belfagor in 1971, William Tell and L’Africana in 1972, and other works established the orchestra and Queler as fixture...
  • Opera Philosophica et Mineralia (work by Swedenborg)
    ...European journey in 1733, it became obvious that these years had been filled with reading and reflection in addition to his ordinary work as a civil servant. In 1734 he published in Leipzig his Opera Philosophica et Mineralia (“Philosophical and Logical Works”) in three folio volumes, the first of which, the Principia Rerum Naturalium (“Principles of Natural.....
  • Opera Selecta (work by Hardouin)
    After the unauthorized publication in Amsterdam of his Opera Selecta (1708; “Selected Works”), Hardouin was compelled publicly to disavow the theory of a forged antiquity, but a similar theory appeared in his masterwork. This was his edition of the texts of the church councils, from New Testament times onward, Conciliorum Collectio Regia Maxima: Acta Conciliorum. . . .....
  • opera seria (Italian music)
    (Italian: “serious opera”), style of Italian opera dominant in 18th-century Europe. It emerged in the late 17th century, notably in the work of Alessandro Scarlatti and other composers working in Naples, and is thus frequently called Neapolitan opera. The primary musical emphasis of opera seria was on the solo voice and on bel canto, the florid vocal style of the period. Chorus and ...
  • opéra-ballet (dance)
    ...One major influence was the commedia dell’arte, in which words count significantly less than gestures, a theatre linked to the actor, who brings his own routines with him. Another influence was the opéra ballet, with its grand display of fleeting images embodied by the dance, the singing, the costumes, and the decorations. Watteau belonged to a period of reaction against the class...
  • Opéra-Comique (French theatrical company)
    ...in Turin, Italy, early in 1879. In May of that year she made her London debut in Vincenzo Bellini’s La sonnambula (The Sleepwalker). Her Paris debut followed in March 1880 in an Opéra-Comique production of Ambrose Thomas’s Mignon. Her performance there won her a five-year contract, and she attained popular stardom with dizzying speed. The height of her ...
  • opéra-comique (music)
    French form of opera in which spoken dialogue alternates with self-contained musical numbers. The earliest examples of opéra-comique were satiric comedies with interpolated songs, but the form later developed into serious musical drama distinguished from other opera only by its spoken dialogue....
  • operant conditioning (psychology)
    Instrumental, or operant, conditioning involves creating a relationship between a response and a stimulus. If the experiment described above is changed so that after the tone is heard, the infant is required to turn his head to the right in order to receive the sweetened water, the infant will learn to turn his head when the tone sounds. The infant learns a relation between the response of......
  • Óperas portuguesas (work by Silva)
    light and sentimental Portuguese song popular in the 18th and 19th centuries. Some of the earliest examples of modinhas are in the Óperas Portuguesas (1733–41) by António José da Silva, who interspersed the songs into the prose dialogue of his dramas. Originally simple melodies, modinhas often were embellished with intricate and elaborate musical......
  • operatic aria (music)
    a drama set to music and made up of vocal pieces with orchestral accompaniment and with orchestral overtures and interludes. In some operas, such as those by Richard Wagner, the music is continuous throughout an act; in others, it is broken up either by recitative (which is more like sung speech) or by dialogue. This article focuses on opera in the Western tra...
  • Operatic Dancing of Great Britain, Association of (British organization)
    ...and enforce standards in ballet teaching. Following the grant of a royal charter in 1936, the Association of Operatic Dancing of Great Britain, as the organization was originally called, became the Royal Academy of Dancing, at the helm of which Genée remained as founder-president until 1954. In 1950 she was made a Dame of the British Empire, the first member of the dance profession to be...
  • operating (vehicle operation)
    ...ship is heavily influenced by the environment at the time of the attempted maneuver. Wave actions, tides, and currents all result in water movement around the ship, which must be considered by the pilot in directing the vessel. Wind also can strongly influence ship movement, both for sailing vessels that use wind for power, and for motorized vessels. Limitations in visibility posed by......
  • operating standard (telecommunications)
    Modems operate in part by communicating with each other, and to do this they must follow matching protocols, or operating standards. Worldwide standards for voiceband modems are established by the V-series of recommendations published by the International Telecommunication Union’s Telecommunication Standardization sector (ITU-T; formerly the International Telegraph and Telephone Consultativ...
  • operating system (computing)
    program that manages a computer’s resources, especially the allocation of those resources among other programs. Typical resources include the central processing unit (CPU), computer memory, file storage, input/output (I/O) devices, and network connections. Management tasks include scheduling resource use to avoid conflicts and interference between progr...
  • Operating Thetan level (scientology)
    ...by many practices to find the pathway to salvation. He has held the imperishable hope that someday in some way he would be free.” Consequently, the most sacred teachings of Scientology (the Operating Thetan, or OT, levels) are concerned with assisting the individual to operate as a fully conscious and functioning thetan....
  • operating-characteristic curve (statistics)
    ...= 0.01. Although most applications of hypothesis testing control the probability of making a type I error, they do not always control the probability of making a type II error. A graph known as an operating-characteristic curve can be constructed to show how changes in the sample size affect the probability of making a type II error....
  • Operation Desert Storm (speech by Bush)
    ...
  • Operation Reinhard (Nazi campaign)
    ...extermination camp for Jews as part of the “final solution to the Jewish question,” or the Holocaust. The Nazis established this camp—along with Belzec and Sobibor—as part of Operation Reinhard, an effort to exterminate the Jews of occupied Poland....
  • Operation Sea Lion (work by Kiefer)
    ...photographic images to deal ironically with 20th-century German history. Beuys also encouraged Kiefer to paint, and in such huge paintings as “Germany’s Spiritual Heroes” (1973) and “Operation Sea Lion” (1975) Kiefer was able to develop an array of visual symbols by which he could comment with irony and sarcasm on certain tragic aspects of German history and c...
  • operational amplifier (electronics)
    Most present-day electronic analog computers operate by manipulating potential differences (voltages). Their basic component is an operational amplifier, a device whose output current is proportional to its input potential difference. By causing this output current to flow through appropriate components, further potential differences are obtained, and a wide variety of mathematical operations,......
  • operational experiment (industrial engineering)
    In situations where it is not possible to isolate the effects of individual variables by analysis of operating data, it may be necessary to resort to operational experiments to determine which variables are relevant and how they affect system performance....
  • operational fatigue (psychology)
    a neurotic disorder caused by the stress involved in war. This anxiety-related disorder is characterized by (1) hypersensitivity to stimuli such as noises, movements, and light accompanied by overactive responses that include involuntary defensive jerking or jumping (startle reactions), (2) easy irritability progressing even to acts of violence, and (3) sleep disturbances includ...
  • operational gaming (industrial engineering)
    A simulation in which decision making is performed by one or more real decision makers is called “operational gaming.” Such simulations are commonly used in the study of interactions of decision makers as in competitive situations. Military gaming has long been used as a training device, but only relatively recently has it been used for research purposes. There is still considerable....
  • operational intelligence
    ...called national), tactical, and counterintelligence. The broadest of these levels is strategic intelligence, which includes information about the capabilities and intentions of foreign countries. Tactical intelligence, sometimes called operational or combat intelligence, is information required by military field commanders. Because of the enormous destructive power of modern weaponry, the......
  • operational knowledge
    The propositional sense of knowing (i.e., knowing that something or other is the case), rather than the operational sense of knowing (i.e., knowing how something or other is done), is generally taken as the starting point for a logical theory of knowing. Accordingly, the logician may begin with a person x and consider a set of propositions Kx to represent......
  • operational research (industrial engineering)
    application of scientific methods to the management and administration of organized military, governmental, commercial, and industrial processes....
  • Operational Research Club (British organization)
    Societies were organized, beginning with the Operational Research Club of Britain, formed in 1948, which in 1954 became the Operational Research Society. The Operations Research Society in America was formed in 1952. Many other national societies appeared; the first international conference on operations research was held at Oxford University in 1957. In 1959 an International Federation of......
  • “Operational Research Quarterly” (British magazine)
    The first scholarly journal, the Operational Research Quarterly, published in the United Kingdom, was initiated in 1950; in 1978 its name was changed to the Journal of the Operational Research Society. It was followed in 1952 by the Journal of the Operations Research Society of America, which was renamed Operations Research in 1955. The International Federation of......
  • Operational Research Society (British organization)
    Societies were organized, beginning with the Operational Research Club of Britain, formed in 1948, which in 1954 became the Operational Research Society. The Operations Research Society in America was formed in 1952. Many other national societies appeared; the first international conference on operations research was held at Oxford University in 1957. In 1959 an International Federation of......
  • Operations, Directorate of (United States government)
    The Directorate of Operations is responsible for the clandestine collection of intelligence (i.e., espionage) and special covert operations. Clandestine activities are carried out under various covers, including the diplomatic cloak used by virtually every intelligence service, as well as corporations and other “front” companies that the CIA creates or acquires. Despite the......
  • operations management (industrial engineering)
    planning and control of industrial processes to ensure that they move smoothly at the required level. Techniques of production management are employed in service as well as in manufacturing industries. It is a responsibility similar in level and scope to other specialties such as marketing or human resource and financial management. In manufacturing operations, production management includes respo...
  • operations research (industrial engineering)
    application of scientific methods to the management and administration of organized military, governmental, commercial, and industrial processes....
  • Operations Research (American magazine)
    ...published in the United Kingdom, was initiated in 1950; in 1978 its name was changed to the Journal of the Operational Research Society. It was followed in 1952 by the Journal of the Operations Research Society of America, which was renamed Operations Research in 1955. The International Federation of Operational Research Societies initiated the International......
  • Operationskreis des Logikkalkus, Der (work by Schröder)
    ...was cultivated by two other major figures in the 19th century. The tradition of Hermann Grassmann was continued by the German mathematician and algebraist Ernst Schröder. His first work, Der Operations-kreis des Logikkalkuls (1877; “The Circle of Operations of the Logical Calculus”), was an equational algebraic logic influenced by Boole and Grassmann but presented in...
  • operative sepsis (disease)
    ...applicants. In August 1861 he was appointed surgeon to the Glasgow Royal Infirmary, where he was in charge of wards in the new surgical block. The managers hoped that hospital disease (now known as operative sepsis—infection of the blood by disease-producing microorganisms) would be greatly decreased in their new building. The hope proved vain, however. Lister reported that, in his Male....
  • operator (mathematics and logic)
    in mathematics, any symbol that indicates an operation to be performed. Examples are x (which indicates the square root is to be taken) and ddx (which indicates differentiation with respect to x is to be performed). An operator may be regarded as a function...
  • operator gene (genetics)
    ...the trans situation is that more C antigen is detectable on the red cells from CDe/cde donors than on those of CDe/cDE people. The inheritance of the Rh system probably depends on the existence of operator genes, which turn the activity of closely linked structural genes on or off. The operator genes are themselves controlled by regulator genes. The operator genes are responsible for the......
  • operator, linear
    ...in 1911. His first work was on the theory of determinants of infinite matrices, a topic initiated by the French mathematician Henri Poincaré. This work now forms part of the theory of linear operators, which are fundamental in the study of quantum mechanics. He also worked on the Riemann hypothesis (see Riemann zeta function) and the prime number theorem....
  • operator ring (mathematics)
    Motivated by a continuing desire to develop mathematical techniques suited to quantum phenomena, von Neumann introduced a theory of rings of operators, now known as von Neumann algebras (1929 through the 1940s). Other achievements include a proof of the quasi-ergodic hypothesis (1932) and important work in lattice theory (1935–37). It was not only the new physics that commanded von......
  • operculate barnacle (crustacean)
    There are two types of sessile barnacle: symmetrical and asymmetrical. The two symmetrical sessile barnacles are the extinct suborder Brachylepadomorpha (Brachylepas) and the extant suborder Balanomorpha, or acorn barnacles (e.g., Balanus, Semibalanus, and Chthamalus). An acorn barnacle is a conical, sessile animal whose soft body is contained within a cavity......
  • operculum (plant anatomy)
    The moss sporangium usually opens by way of an apical lid (the operculum). When the operculum falls, there is exposed a ring of teeth that controls the release of the spores over an extended period of time. These teeth usually respond to slight moisture changes and pulsate inward and outward, carrying spores out of the sporangium on their jagged inner surfaces. In the moss subclass......
  • operculum (zoology)
    ...to low-frequency sound. Also unique to lissamphibians is the columella-opercular complex, a pair of elements associated with the auditory capsule that transmit airborne (columella) or seismic (operculum) signals....
  • Opere Matematiche (work by Beltrami)
    ...of non-Euclidean geometry, and it was soon taken up by the German Felix Klein, who showed that non-Euclidean geometry was a special case of projective geometry. Beltrami’s four-volume work, Opere Matematiche (1902–20), published posthumously, contains his comments on a broad range of physical and mathematical subjects, including thermodynamics, elasticity, magnetism,....
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