gull: …the smallest gull is the little gull (L. minutus), a black-headed species of Europe and occasionally North America.

gull: The Pacific gull (L. pacificus) breeds in the region of Tasmania and southern Australia. The ring-billed gull (L. delawarensis) is common on inland lakes in North America and often gathers in large flocks to feed on plowed fields. The sooty gull (L. hemprichi) of the western…

gull: Bonaparte’s gull (L. philadelphia), of North America, has a black head and bill, a gray mantle, and pinkish to reddish legs. It builds a stick nest in trees and hunts for insects over ponds. In the winter it may plunge into the sea for fish.…

gull: Franklin’s gull (L. pipixcan) breeds in large colonies on inland marshes of North America and winters on the Pacific coast of South America.

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aggressive flight display, and a ground display (called the “forward”) wherein the neck is lowered, the head withdrawn and angled upward, and the wings held out from the body.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, 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

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.

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, 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

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

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 on

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),…

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, 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

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…

laryngeal cancer, malignant tumour of the larynx (voice box). 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. Squamous cell carcinoma is the most common malignancy

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.

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…

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, 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

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

pepsin: gastroesophageal reflux disease and laryngopharyngeal reflux (or extraesophageal reflux). In the latter, pepsin and acid travel all the way up to the larynx, where they can cause damage to the laryngeal mucosa and produce symptoms ranging from hoarseness and chronic cough to laryngospasm (involuntary contraction of the vocal cords)…

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.

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, 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

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, 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, 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 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 (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

Bartolomé de Las Casas was an 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

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…

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

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, 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

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 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, 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, 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 Meninas, oil painting created in 1656 by iconic Spanish artist Diego Velázquez. Las Meninas shows Velázquez late in his career and at the height of his powers. Its complex composition creates an unparallelled illusion of reality and is a reason that it is one of the most important paintings in

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, 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 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,

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, 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

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 Posadas, religious festival celebrated in Mexico and some parts of the United States between December 16 and 24. Las Posadas commemorates the journey that Joseph and Mary made from Nazareth to Bethlehem in search of a safe refuge where Mary could give birth to the baby Jesus. When they were

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

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

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, 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, 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 Aces, American professional basketball team that plays in the Western Conference of the Women’s National Basketball Association (WNBA). For the first six years of its existence, the franchise was based in Salt Lake City, Utah, and was named the Utah Starzz. In 2003 the team relocated to

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 that

Las Vegas Raiders, American professional gridiron football team based in Las Vegas, Nevada, that plays in the National Football League (NFL). The Raiders have won three Super Bowl championships (1977, 1981, and 1984), one American Football League (AFL) championship (1967), and four American

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

Santa Clara: The Central University of Las Villas was founded in Santa Clara in 1952. The city is situated near the geographic centre of the island, on the country’s Central Highway, and is the junction point of Cuba’s main rail lines. Pop. (2002) 210,220; (2011 est.) 205,812.

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).

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, pasta dish of Italian origin, made with broad often ruffled noodles and a tomato or white sauce. Lasagna, in the singular, is a southern Italian variation of what northern Italians call lasagne, in the plural. The name is believed to come from a Latin word for cooking pot, lasanum, though

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

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

Anton Francesco Grazzini was an 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

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…

Constantine Lascaris was a 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

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…

John Lascaris was a 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,

Theodore I Lascaris was the 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

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, 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

Christian Democratic Union: History: …emerged to anoint CDU leader Armin Laschet as her designated successor. Merkel’s endorsement may have brought some wavering CDU-CSU supporters to the polls, but it was ultimately not enough. The CDU-CSU won less than a quarter of the vote, its worst performance in a federal election in the postwar era.

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…

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

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…

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…

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…

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

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.

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…

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

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,…

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…

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…

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

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 (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 (LISA), European group of three spacecraft that are designed to search for gravitational radiation. LISA is scheduled for launch in 2034. Funded by the European Space Agency, LISA will consist of three identical spacecraft that will trail Earth in its orbit around

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…

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…

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

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…

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: 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…

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…

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…

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…

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…