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  • Larus ridibundus (bird)

    charadriiform: Gulls (suborder Lari): …“hooded” gulls, exemplified by the black-headed gull (Larus ridibundus) and laughing gull (L. atricilla), have a striking “swoop-and-soar” aggressive flight display, and a ground display (called the “forward”) wherein the neck is lowered, the head withdrawn and angled upward, and the wings held out from the body.

  • larva (zoology)

    Larva, stage in the development of many animals, occurring after birth or hatching and before the adult form is reached. These immature, active forms are structurally different from the adults and are adapted to a different environment. In some species the larva is free-living and the adult is an

  • larva migrans, cutaneous (pathology)

    hookworm: Development: …aberrant infection, “creeping eruption” or cutaneous larva migrans. This disease is characterized by serpiginous tunnels in the skin caused by migrations of larvae that are unable to penetrate the innermost layers.

  • Larvacea (tunicate)

    Larvacean, any member of a group of transparent tunicates belonging to the class Appendicularia (subphylum Tunicata, phylum Chordata) that live in the open sea. The larvacean’s tadpolelike body is made up of a trunk and tail and resembles the larval form of a sea squirt, a related form from the

  • larvacean (tunicate)

    Larvacean, any member of a group of transparent tunicates belonging to the class Appendicularia (subphylum Tunicata, phylum Chordata) that live in the open sea. The larvacean’s tadpolelike body is made up of a trunk and tail and resembles the larval form of a sea squirt, a related form from the

  • Larvae (Roman religion)

    Lemures, in Roman religion, wicked and fearsome spectres of the dead. Appearing in grotesque and terrifying forms, they were said to haunt their living relatives and cause them injury. To propitiate these ghosts and keep them from the household, ritual observances called Lemuria were held yearly o

  • larvae (zoology)

    Larva, stage in the development of many animals, occurring after birth or hatching and before the adult form is reached. These immature, active forms are structurally different from the adults and are adapted to a different environment. In some species the larva is free-living and the adult is an

  • larval case (biology)

    caddisfly: Life cycle: In some species the larvae form webs of debris for protection, while others form a funnel-like web between stones in running water to catch food. Some protect their bodies with cases, whereas others spin protective lairs or are free-living. They produce silk from glands on the lower lip (labium),…

  • larval phase (zoology)

    Larva, stage in the development of many animals, occurring after birth or hatching and before the adult form is reached. These immature, active forms are structurally different from the adults and are adapted to a different environment. In some species the larva is free-living and the adult is an

  • larvas (zoology)

    Larva, stage in the development of many animals, occurring after birth or hatching and before the adult form is reached. These immature, active forms are structurally different from the adults and are adapted to a different environment. In some species the larva is free-living and the adult is an

  • Larvenformen der Dipteren (work by Hennig)

    Willi Hennig: …work in a monograph entitled Larvenformen der Dipteren (1952; “Dipterous Larvae”), which became the standard work on the subject. He later extended his studies on dipterans to include those species of the order found in New Zealand, which afforded him the opportunity to apply the principles of cladistic classification to…

  • Larwood, Harold (British cricketer)

    Harold Larwood, British cricketer (born Nov. 14, 1904, Nuncargate, Nottinghamshire, England—died July 22, 1995, Sydney, Australia), pummeled the Australian side with his fast, short-pitched bowling in the infamous "bodyline" tour of 1932-33. Larwood worked in the coal mines from age 14, but four y

  • laryngeal cancer

    Laryngeal cancer, malignant tumour of the larynx. There are two types of tumours found on the larynx that can be malignant. One is called a carcinoma; the other, called a papilloma, often is benign but occasionally becomes malignant. The papilloma is the most common tumour of the larynx. It is a

  • laryngeal consonant (linguistics)

    Anatolian languages: Phonological characteristics: …direct evidence for the “laryngeal” consonants reconstructed for Proto-Indo-European on purely internal grounds by linguist Ferdinand de Saussure in 1879. Study of the details of the development of these guttural (or pharyngeal) fricatives in Anatolian continues.

  • laryngeal diphtheria

    diphtheria: Laryngeal diphtheria usually results from the spread of the infection downward from the nasopharynx to the larynx; the airway may become blocked and must be restored by inserting a tube or cutting an opening in the trachea (tracheotomy). Cutaneous diphtheria affects parts of the body…

  • laryngeal flap (anatomy)

    childhood disease and disorder: Respiratory disorders: …the larynx (voice box) or epiglottis (the plate of cartilage that shuts off the entrance into the larynx during the process of swallowing), most often caused by viral infection; it is encountered in infants and small children. Inflammation and swelling of the vocal cords lead to respiratory obstruction, particularly in…

  • laryngeal hemiplegia (equine disease)

    Laryngeal hemiplegia, in horses, partial or complete paralysis of muscles controlling the vocal fold and other components of the larynx as a result of degeneration of the recurrent laryngeal nerve. Laryngeal hemiplegia occurs in all breeds of horses, but mainly in large breeds, and it is probably

  • laryngeal pharynx (anatomy)

    pharynx: The third region is the laryngeal pharynx, which begins at the epiglottis and leads down to the esophagus. Its function is to regulate the passage of air to the lungs and food to the esophagus.

  • laryngectomy (surgery)

    Laryngectomy, surgical procedure to remove all or a portion of the larynx (voice box). The procedure most often is used to treat persons affected by cancer of the larynx when chemotherapy is unsuccessful. However, it may also be performed when gunshot wounds, severe fractures, or other trauma

  • laryngitis

    Laryngitis, inflammation of the larynx or voice box, caused by chemical or mechanical irritation or bacterial infection. Laryngitis is classified as simple, diphtheritic, tuberculous, or syphilitic laryngitis. Simple laryngitis is usually associated with the common cold or similar infections.

  • laryngology (medicine)

    Laryngology, a branch of medicine dealing with the larynx, nose, and pharynx. See

  • laryngoscope

    nasopharyngolaryngoscopy: …including the sinus openings, the larynx, and the vocal cords. The type of endoscope used for this procedure is called a nasopharyngolaryngoscope. This instrument enables a more thorough examination to be performed than is possible with indirect visualization with a mirror.

  • laryngostroboscope

    speech: Studies of register differences: Modern laryngostroboscopes employ the oscillating light of a high-power fluorescent light source that is monitored by the laryngeal vibrations through a throat microphone. Such devices, when they flash on and off at just the right rate, make the vocal cord movements appear much slower than they…

  • larynx (anatomy)

    Larynx, a hollow, tubular structure connected to the top of the windpipe (trachea); air passes through the larynx on its way to the lungs. The larynx also produces vocal sounds and prevents the passage of food and other foreign particles into the lower respiratory tracts. The larynx is composed of

  • LAS

    Arab League, regional organization of Arab states in the Middle East and parts of Africa, formed in Cairo on March 22, 1945, as an outgrowth of Pan-Arabism. The founding member states were Egypt, Syria, Lebanon, Iraq, Transjordan (now Jordan), Saudi Arabia, and Yemen. Other members are Libya

  • Las Alpujarras (district, Spain)

    Las Alpujarras, mountainous district spanning Granada and Almería provincias (provinces) in the Andalusia comunidad autónoma (autonomous community) of southern Spain, stretching northward from the towns of Motril and Almería to the foothills of the Sierra Nevada and forming a trough between the

  • Las Alpujarras Mountains (district, Spain)

    Las Alpujarras, mountainous district spanning Granada and Almería provincias (provinces) in the Andalusia comunidad autónoma (autonomous community) of southern Spain, stretching northward from the towns of Motril and Almería to the foothills of the Sierra Nevada and forming a trough between the

  • Las Bela (district, Pakistan)

    Las Bela, district of Kalāt division, Balochistān province, Pakistan. A former princely state, it has an area of 7,048 sq mi (18,254 sq km) and is bounded north by Khuzdār district, east by the Kīrthar Range (separating it from Sind), south by the Arabian Sea, and west by the Hāla Range. An

  • Las Campanas Observatory (observatory, Chile)

    Las Campanas Observatory (LCO), astronomical observatory established in 1969 in the Atacama desert of Chile at an altitude of 2,282 metres (7,487 feet). It is owned by the Carnegie Institution for Science, an American private research centre. The region is well known for its remarkably clear skies

  • Las Casas, Bartolomé de (Spanish historian and missionary)

    Bartolomé de Las Casas, early Spanish historian and Dominican missionary who was the first to expose the oppression of indigenous peoples by Europeans in the Americas and to call for the abolition of slavery there. His several works include Historia de las Indias (first printed in 1875). A prolific

  • Las Casas, Francisco de (Spanish conquistador)

    Central America: Appointment of Pedrarias: Cortés first sent Francisco de Las Casas to relieve the rebellious Olid but then marched to Honduras himself to reprimand Olid. Before he arrived, however, Las Casas and González had united against Olid and put him to death. Cortés’s difficult trip to Honduras thus turned out to be…

  • Las Cases, Emmanuel, comte de (French historian)

    Emmanuel, count de las Cases, French historian best known as the recorder of Napoleon’s last conversations on St. Helena, the publication of which contributed greatly to the Napoleonic legend in Europe. An officer of the royal navy, Las Cases in 1790 emigrated from France to England, where he wrote

  • Las Charcas culture (Mesoamerican history)

    pre-Columbian civilizations: The Maya in the Middle Formative: It was followed by Las Charcas, a Middle Formative culture known largely from the contents of bottle-shaped pits found dug into the subsoil on the western edge of the modern city. Extremely fine ceramics have been excavated from them, including red-on-white bowls with animal figures, effigy vessels, three-footed cups,…

  • Las Cruces (New Mexico, United States)

    Las Cruces, city, seat (1852) of Doña Ana county, southern New Mexico, U.S. It lies along the Rio Grande 38 miles (61 km) northwest of El Paso, Texas. It was founded in 1848 at the end of the Mexican-American War. There are many theories surrounding the naming of the town, but none of these legends

  • Las Cruces College (university, Las Cruces, New Mexico, United States)

    New Mexico State University, public, coeducational institution of higher learning in Las Cruces, New Mexico, U.S. It anchors the New Mexico State University system, which also includes two-year branches at Alamogordo, Las Cruces (Doña Ana Branch Community College), Carlsbad, and Grants. More than

  • Las Hurdes (region, Spain)

    Las Hurdes, region in Cáceres provincia (province), in the Extremadura comunidad autónoma (autonomous community), western Spain. The high plateau of Salamanca in the central Cordillera Ridge rises almost imperceptibly to the western ranges of the Sierra de Peña de Francia, which on their southern

  • Las Hurdes Mountains (region, Spain)

    Las Hurdes, region in Cáceres provincia (province), in the Extremadura comunidad autónoma (autonomous community), western Spain. The high plateau of Salamanca in the central Cordillera Ridge rises almost imperceptibly to the western ranges of the Sierra de Peña de Francia, which on their southern

  • Las Marismas (region, Spain)

    Las Marismas, coastal marshes along the Guadalquivir estuary in the comunidad autónoma (autonomous community) of Andalusia, southern Spain. The region extends for more than 1,100 square miles (3,000 square km), occupying part of the provinces of Sevilla, Huelva, and Cádiz. In Roman times Las

  • Las Palmas (Canary Islands, Spain)

    Las Palmas de Gran Canaria, city and port, capital of Las Palmas provincia (province) in the Canary Islands comunidad autónoma (autonomous community) of Spain. Located on the northeastern coast of Gran Canaria Island, it is the largest city of the island. Founded in 1478 at the mouth of a ravine,

  • Las Palmas (province, Canary Islands, Spain)

    Las Palmas, provincia (province) in the comunidad autónoma (autonomous community) of the eastern Canary Islands, Spain. Las Palmas province consists of Gran Canaria, Fuerteventura, Lanzarote, and a few smaller islands. The city of Las Palmas, on the island of Gran Canaria, is the capital of the

  • Las Palmas de Gran Canaria (Canary Islands, Spain)

    Las Palmas de Gran Canaria, city and port, capital of Las Palmas provincia (province) in the Canary Islands comunidad autónoma (autonomous community) of Spain. Located on the northeastern coast of Gran Canaria Island, it is the largest city of the island. Founded in 1478 at the mouth of a ravine,

  • Las Peñas (Mexico)

    Puerto Vallarta, city and chief port of Jalisco estado (state), west-central Mexico. It lies on the Pacific coastal lowland 6 miles (10 km) south of the mouth of the Ameca River on Banderas Bay. In 1644 the Spanish established a rudimentary shipyard on Banderas Bay for expeditions bound for Baja

  • Las Piedras (Uruguay)

    Las Piedras, city, southern Uruguay. It is situated in a wine-growing district just north of Montevideo. It was the site of a decisive battle (1811) in Uruguay’s struggle for independence, in which the revolutionaries defeated Spanish forces. Las Piedras is among the largest cities in Uruguay. It

  • Las Pitiusas (islands, Spain)

    Balearic Islands: …group is known as the Pitiusas and includes the islands of Ibiza (Eivissa) and Formentera. The archipelago is an extension of the sub-Baetic cordillera of peninsular Spain, and the two are linked by a sill near Cape Nao in the province of Alicante. The Balearic Islands autonomous community was established…

  • Las Tablas (Panama)

    Las Tablas, town, southwestern Panama. It is situated on the coastal lowland of the Azuero Peninsula a few miles west of its port, Mensabé, on the Gulf of Panama. It was founded as a gold-mining centre. In addition to having administrative functions, Las Tablas is a marketing centre for the

  • Las Tunas (Cuba)

    Victoria de las Tunas, city, eastern Cuba. It is located about 45 miles (72 km) west of Holguín. The city is principally a commercial and manufacturing centre for a rich agricultural and pastoral hinterland, whose major yields are sugarcane, bananas, oranges, and cattle; beeswax and honey are also

  • Las Vacas (Mexico)

    Ciudad Acuña, city, northern Coahuila estado (state), northeastern Mexico. The city is on the Rio Grande (Río Bravo del Norte) just across the U.S.-Mexico border from Del Rio, Texas, and is a port of entry. Ciudad Acuña is also a commercial and manufacturing centre for the agricultural hinterland.

  • Las Vegas (Nevada, United States)

    Las Vegas, city, seat (1909) of Clark county, southeastern Nevada, U.S. The only major city in the American West to have been founded in the 20th century, Las Vegas grew from a tiny, desert-bound railroad service centre at the outset of the 20th century to the country’s fastest-growing metropolis

  • Las Vegas (New Mexico, United States)

    Las Vegas, city, seat (1862) of San Miguel county, north-central New Mexico, U.S. It lies along the Gallinas River, at an elevation of 6,435 feet (1,961 metres), in the Sangre de Cristo Mountains. The original settlement (1835) developed as the Mexican port of entry on the Santa Fe Trail. The city

  • Las Vegas Craps (dice game)

    Bank Craps, dice game, the variant of Craps most played in Nevada gambling houses. A special table and layout are used, and all bets are made against the house. A player signifies his bet by placing chips or cash on the appropriate part of the layout before any roll. It is invariably required t

  • Las Vegas Story, The (film by Stevenson [1952])

    Robert Stevenson: Early films: The Las Vegas Story (1952) was a disappointing film noir starring Victor Mature, Vincent Price, and Jane Russell. The movie was perhaps best remembered for the battle between the Screen Writers Guild and producer Howard Hughes, who refused to credit Paul

  • Lasa (China)

    Lhasa, capital of the Tibet Autonomous Region, southwestern China. It is located at an elevation of 11,975 feet (3,650 metres) in the Nyainqêntanglha Mountains of southern Tibet near the Lhasa River, a tributary of the Yarlung Zangbo (Tsangpo) River (the name of the Brahmaputra River in Tibet).

  • Lasa, Tassilo von Heydebrand und der (German chess player and author)

    chess: Origin of time controls: …a flexible system proposed by Tassilo von Heydebrand und der Lasa, a 19th-century German player and author. Lasa proposed that each player be allowed a bank of time in which to play a predetermined number of moves, such as two hours for 30 moves. This principle, adopted for the vast…

  • lasagna (food)

    pasta: Ribbon types include the wide lasagna and the narrow linguini. Farfels are ground, granulated, or shredded. The wide variety of special shapes includes farfalloni (“large butterflies”), lancette (“little spears”), fusilli (“spindles”), and riccioline (“little curls”).

  • LaSal Mountains (mountains, Utah, United States)

    LaSal Mountains, laccolithic segment of the Colorado Plateau, extending across San Juan and Grand counties in eastern Utah, U.S. Of volcanic origin, the peaks rise to Mount Peale (12,721 feet [3,877 metres]), the highest point in the Colorado Plateau. The region is largely embraced by a division of

  • Lasansky, Mauricio Leib (Argentine-born American artist)

    Mauricio Leib Lasansky, Argentine-born American artist (born Oct. 12, 1914, Buenos Aires, Arg.—died April 2, 2012, Iowa City, Iowa), primarily produced large-scale prints noted for their vivid expressiveness and technical mastery but was also known for The Nazi Drawings (completed 1966), a series

  • Lasbela (district, Pakistan)

    Las Bela, district of Kalāt division, Balochistān province, Pakistan. A former princely state, it has an area of 7,048 sq mi (18,254 sq km) and is bounded north by Khuzdār district, east by the Kīrthar Range (separating it from Sind), south by the Arabian Sea, and west by the Hāla Range. An

  • Lasca, Il (Italian writer)

    Anton Francesco Grazzini, Italian poet, playwright, and storyteller who was active in the linguistic and literary controversies of his day. Apparently educated in vernacular literature, Grazzini in 1540 took part in the founding of the Accademia degli Umidi (“Academy of the Humid”), the first

  • Lascarid dynasty (Byzantine history)

    Anatolia: Late Byzantine rule: … under the dynasty of the Lascarids. Centred in the Aegean region and Bithynia, the Lascarids established a modus vivendi with the Seljuq power and retook Constantinople from the Latins in 1261. The reconquest of Constantinople was, in fact, a disaster for the empire’s Anatolian possessions, since with the transfer of…

  • Lascaris, Constantine (Byzantine grammarian)

    Constantine Lascaris, Byzantine exile, primarily a grammarian and copyist, who taught Greek in Italy. After the fall of Constantinople (1453), Lascaris went to Milan, where he became tutor to the Duke of Milan’s daughter, Ippolita Sforza, and wrote for her his Erotemata (1476). Published in Milan,

  • Lascaris, John (emperor of Nicaea)

    Michael VIII Palaeologus: Early years: …regent for Theodore’s six-year-old son, John Lascaris. Gradually usurping more and more authority, Michael seized the throne and early in 1259 was crowned emperor after shunting aside and blinding the rightful heir, his charge, John. Faced with rebellion by Lascarid supporters in Asia Minor, Michael succeeded, in the eyes of…

  • Lascaris, John (Greek scholar)

    John Lascaris, Greek scholar and diplomat whose career shows the close connections that linked political interests and humanist effort before the Protestant Reformation. A librarian to Lorenzo de’ Medici, Lascaris toured the Levant (1489–92), and his records of the manuscripts he sought, examined,

  • Lascaris, Theodore I (emperor of Nicaea)

    Theodore I Lascaris, first emperor of Nicaea, which was recognized as the Byzantine government-in-exile and as the legitimate successor of the Byzantine Empire during the Crusaders’ occupation of Constantinople. He was a son-in-law and heir of the Byzantine emperor Alexius III Angelus. After the

  • Lascaux (cave, Dordogne, France)

    Lascaux, cave containing one of the most outstanding displays of prehistoric art yet discovered. Located above the Vézère River valley near Montignac, in Dordogne, France, the cave is a short distance upstream from the Eyzies-de-Tayac series of caves. Lascaux, together with some two dozen other

  • Lascaux Grotto (cave, Dordogne, France)

    Lascaux, cave containing one of the most outstanding displays of prehistoric art yet discovered. Located above the Vézère River valley near Montignac, in Dordogne, France, the cave is a short distance upstream from the Eyzies-de-Tayac series of caves. Lascaux, together with some two dozen other

  • Lasch, Christopher (American social critic)

    Christopher Lasch, U.S. social critic and academic (born June 1, 1932, Omaha, Neb.—died Feb. 14, 1994, Pittsford, N.Y.), penned stinging indictments of contemporary American culture as the author of several books, most notably the 1979 best-seller The Culture of Narcissism, in which he decried a s

  • Lasco, Johannes à (Polish theologian and noble)

    Thomas Cranmer: Achievements under Edward VI: …1547, as either the Pole Jan Laski the Younger or the Englishman Nicholas Ridley, both men possessed of a more determined and unquestioning temper than was the archbishop. The ferment of those years also produced Cranmer’s Forty-two Articles (1553), a set of doctrinal formulas defining the dogmatic position of the…

  • Lasdun, Sir Denys Louis (British architect)

    Sir Denys Louis Lasdun, British architect (born Sept. 8, 1914, London, Eng.—died Jan. 11, 2001, London), was one of Great Britain’s most prominent New Brutalist architects, noted for his controversial use of vast concrete-slab exteriors. Lasdun’s designs included the award-winning Royal College o

  • laser (instrument)

    Laser, a device that stimulates atoms or molecules to emit light at particular wavelengths and amplifies that light, typically producing a very narrow beam of radiation. The emission generally covers an extremely limited range of visible, infrared, or ultraviolet wavelengths. Many different types

  • laser (ancient cuisine)

    cooking: Ancient Rome: …Roman seasonings was laserpitium, or laser, the extract of a wild giant fennel (silphium), which the Romans loved so much that they ate the plant to extinction. Laser not only was a versatile culinary ingredient but was used for medicinal purposes as well (primarily as a digestive aid); it may…

  • laser ablation

    advanced ceramics: Film deposition: PVD methods include laser ablation, in which a high-energy laser blasts material from a target and through a vapour to a substrate, where the material is deposited. Another PVD approach involves sputtering, in which energetic electrons bombard the surface of a target, removing material as a vapour that…

  • laser absorption spectrometer (instrument)

    spectroscopy: Doppler-limited spectroscopy: The design of a laser absorption spectrometer (Figure 10) is advantageous in that no monochromator is needed since the absorption coefficient of a transition can be measured directly from the difference in the photodiode current generated by the radiation beam passing through the sample (I1) and the current generated…

  • laser altimetry radar (scientific technique)

    Lidar, technique for determining the distance to an object by transmitting a laser beam, usually from an airplane, at the object and measuring the time the light takes to return to the transmitter. The word lidar is derived from light detection and ranging. The first attempts to measure distance by

  • laser beam

    lidar: …an object by transmitting a laser beam, usually from an airplane, at the object and measuring the time the light takes to return to the transmitter. The word lidar is derived from light detection and ranging.

  • laser diode (electronics)

    electronics: Optoelectronic functions: Laser diodes, also made of III-V compounds, are used in digital audio and video disc players to read the minuscule tracks molded into the disc and containing the digitally recorded information. Lasers are employed because laser light can be focused into an extremely tiny spot…

  • laser disc (recording)

    Compact disc (CD), a molded plastic disc containing digital data that is scanned by a laser beam for the reproduction of recorded sound and other information. Since its commercial introduction in 1982, the audio CD has almost completely replaced the phonograph disc (or record) for high-fidelity

  • laser fusion (physics)

    fusion reactor: Principles of inertial confinement: …accomplished by focusing an intense laser beam or a charged particle beam, referred to as the driver, upon the small pellet (typically 1 to 10 mm in diameter). For efficient thermonuclear burn, the time allotted for the pellet to burn must be less than the disassembly time. This means that,…

  • Laser Geodynamic Satellite

    geoid: The contribution of orbiting satellites: …geodetic purposes was Lageos (Laser Geodynamic Satellite), launched by the United States on May 4, 1976, into a nearly circular orbit at a height of approximately 6,000 kilometres. It consisted of an aluminum sphere 60 centimetres (23.6 inches) in diameter that carried 426 reflectors suitable for reflecting laser beams…

  • laser glazing (material science)

    amorphous solid: Other preparation techniques: In laser glazing, a brief intense laser pulse melts a tiny spot, which is swiftly quenched by the surrounding material into a glass. In sol-gel synthesis, small molecules in a liquid solution chemically link up with each other, forming a disordered network. It is possible to…

  • laser holography (optics)

    Holography, means of creating a unique photographic image without the use of a lens. The photographic recording of the image is called a hologram, which appears to be an unrecognizable pattern of stripes and whorls but which—when illuminated by coherent light, as by a laser beam—organizes the light

  • laser infrared radar (scientific technique)

    Lidar, technique for determining the distance to an object by transmitting a laser beam, usually from an airplane, at the object and measuring the time the light takes to return to the transmitter. The word lidar is derived from light detection and ranging. The first attempts to measure distance by

  • Laser Interferometer Gravitational-Wave Observatory (astronomical observatory, Hanford, Washington and Livingston, Louisiana, United States)

    Laser Interferometer Gravitational-Wave Observatory (LIGO), astronomical observatory located in Hanford, Washington, and in Livingston, Louisiana, that in 2015 made the first direct detection of gravitational waves. Construction began on LIGO in 1999, and observations began in 2001. Gravitational

  • Laser Interferometer Space Antenna (spacecraft)

    Laser Interferometer Space Antenna (LISA), joint U.S.-European group of three spacecraft that are designed to search for gravitational radiation. LISA is scheduled for launch in 2015 and will be one of the National Aeronautics and Space Administration’s (NASA’s) series of Beyond Einstein Great

  • laser machining (industrial process)

    machine tool: Laser machining (LM): LM is a method of cutting metal or refractory materials by melting and vaporizing the material with an intense beam of light from a laser. Drilling by laser, although costly in energy since material must be melted and vaporized to be removed, is…

  • laser magnetic resonance spectroscopy (physics)

    spectroscopy: Laser magnetic resonance and Stark spectroscopies: Because of the nature of laser-signal generation, most lasers are not tunable over an appreciable frequency range and even those that can be tuned, such as dye lasers, must be driven by a pump laser and for a given…

  • laser photography (optics)

    Holography, means of creating a unique photographic image without the use of a lens. The photographic recording of the image is called a hologram, which appears to be an unrecognizable pattern of stripes and whorls but which—when illuminated by coherent light, as by a laser beam—organizes the light

  • laser printer (device)

    information processing: Printers: The most popular type, the laser printer, uses a beam of laser light and a system of optical components to etch images on a photoconductor drum from which they are carried via electrostatic photocopying to paper. Light-emitting diode (LED) printers resemble laser printers in operation but direct light from energized…

  • laser pulse (instrument)

    holography: Pulsed-laser holography: A moving object can be made to appear to be at rest when a hologram is produced with the extremely rapid and high-intensity flash of a pulsed ruby laser. The duration of such a pulse can be less than 1/10,000,000 of a second;…

  • laser radar (optics)

    laser: Surveying: Pulsed laser radar can measure distance in the same manner as microwave radar by timing how long it takes a laser pulse to bounce back from a distant object. For instance, in 1969 laser radar precisely measured the distance from the Earth to the Moon, and…

  • laser range finder (instrument)

    range finder: …ranging instrument known as the laser range finder. It has largely replaced coincidence range finders for surveying and radar in certain military applications. The laser range finder, like radar, measures distance by timing the interval between the transmission and reception of electromagnetic waves, but it employs visible or infrared light…

  • laser scanner (instrument)

    barcode: …read by an optical (laser) scanner that is part of a computer system. A handheld scanner or barcode pen is moved across the code, or the code itself is moved by hand across a scanner built into a checkout counter or other surface. The computer then stores or immediately…

  • laser scanning confocal microscope (instrument)

    microscope: Confocal microscopes: In a laser scanning confocal microscope (LSCM), the focal point of a laser is scanned across a specimen to build up a two-dimensional optical section. Three-dimensional images can be reconstructed by taking a series of two-dimensional images at different focal depths in the specimen (known as a…

  • laser separation (nuclear enrichment process)

    nuclear reactor: Enrichment: …with much commercial potential is laser separation. This process is based on the principle that isotopes of different molecular weight absorb light of different frequencies. Once a specific isotope has absorbed radiation and has reached an excited state, its properties may become quite different from the other isotopes; it is…

  • laser spectroscopy (science)

    spectroscopy: Laser spectroscopy: As mentioned above, the invention and subsequent development of the laser opened many new areas of spectroscopy. Although the basic processes investigated remain those of rotational, vibrational, and electronic spectroscopies, this tool has provided many new ways to investigate such phenomena and has…

  • laser surgery

    therapeutics: Laser surgery: A laser is a device that produces an extremely intense monochromatic, nondivergent beam of light capable of generating intense heat when focused at close range. Its applications in the medical field include the surgical welding of a detached retina and the stanching of…

  • Laser Writer (computer printer)

    Adobe Inc.: Desktop publishing revolution: …first Macintosh-compatible PostScript printer, the LaserWriter, based on a laser-print engine developed by Canon Inc. The LaserWriter included PostScript renditions of several classic typefaces and a PostScript interpreter—in effect, a built-in computer dedicated to the task of translating PostScript commands into marks on each page.

  • laser-assisted in situ keratomileusis (ophthalmology)

    LASIK, laser-based eye surgery commonly used to correct nearsightedness (myopia), farsightedness (hyperopia), and astigmatism. LASIK eye surgery was developed in the early 1990s, when ophthalmologists combined the technique of keratomileusis, in which the cornea is removed, frozen, reshaped, and

  • laser-guided bomb (weapon)

    smart bomb: …the laser-guidance system, commonly called laser-guided bombs, the target is illuminated by a laser beam from the releasing aircraft, another target-control aircraft, or a ground force unit. Sensors in the bomb’s nose lock onto the reflections of the laser beam and follow them down to the target. Bombs equipped with…

  • laserdisc (electronics)

    Videodisc, rigid circular plate of either metal or plastic used to record video and audio signals for playback. It resembles a phonograph record and can be played on a disc machine attached to a conventional television receiver. There are two major classes of videodiscs: magnetic and nonmagnetic.

  • laserpitium (ancient cuisine)

    cooking: Ancient Rome: …Roman seasonings was laserpitium, or laser, the extract of a wild giant fennel (silphium), which the Romans loved so much that they ate the plant to extinction. Laser not only was a versatile culinary ingredient but was used for medicinal purposes as well (primarily as a digestive aid); it may…

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