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 Talk Talk - Communication terms
Category: General technical and industrial
Date & country: 28/05/2010, UK
Words: 18630


archon
In ancient Greece, title of the chief magistrate in several city-states. In Athens there were originally three archons: the archon basilieus, or king archon, the eponymous archon, and the polemarch. Their numbers were increased to nine in 683 BC: the extra six thesmothetae keeping a record of judgements. The king archon was the elected ...

Aristophanes
Greek comedy dramatist. Of his 11 extant plays (of a total of over 40), the early comedies are remarkable for the violent satire with which he ridiculed the democratic war leaders. He also satirized contemporary issues such as the new learning of Socrates in The Clouds (423 BC) and the obsession with war, with the sex-strike ...

Arabia
Peninsula between the Gulf and the Red Sea, in southwest Asia; area 2,600,000 sq km/1,000,000 sq mi. The length from north to south is about 2,400 km/1,490 mi and the greatest width about 1,600 km/994 mi. The peninsula contains the world's richest gas reserves and half the world's oil reserves. It comprises the states of Bah...

artificial insemination
Introduction by instrument of semen from a sperm bank or donor into the female reproductive tract to bring about fertilization. Originally used by animal breeders to improve stock with sperm from high-quality males, in the 20th century it was developed for use in humans, to help the infertile. See in vitro fertilization

arrhythmia
Disturbance of the normal rhythm of the heart. There are various kinds of arrhythmia, some benign, some indicative of heart disease. In extreme cases, the heart may beat so fast as to be potentially lethal and surgery may be used to correct the condition. Extra beats between the normal ones are called extrasystoles; abnormal slowing is known as...

Ark of the Covenant
In the Old Testament, the chest that contained the Tablets of the Law as given to Moses. The holy ark is now the cupboard or enclosure in a synagogue in which the Torah scrolls are kept. It faces the Temple where the original Ark was kept in the holy of holies. The original Ark was built under Moses' direction when the Israelites were wandering...

Arab
Any of the Semitic (see Semite) people native to the Arabian peninsula, but now settled throughout North Africa and the nations of the Middle East

Arjan
Indian religious leader, fifth guru (teacher) of Sikhism 1581–1606. He built the Golden Temple in Amritsar and compiled the hymns of the four preceding gurus, and his own, in the Adi Granth, the first volume of Sikh scriptures. The collection later became the Guru Granth Sahib, the Sikh holy book. He died ...

arboretum
Collection of trees. An arboretum may contain a wide variety of species or just closely related species or varieties – for example, different types of pine tree

Argand diagram
In mathematics, a method for representing complex numbers by Cartesian coordinates (x, y). Along the x-axis (horizontal axis) are plotted the real numbers, and along the y-axis (vertical axis) the nonreal, or imaginary, numbers

Armistice Day
Click images to enlargeAnniversary of the armistice signed 11 November 1918, ending World War I

aromatherapy
In alternative medicine, use of oils and essences derived from plants, flowers, and wood resins. Bactericidal properties and beneficial effects upon physiological functions are attributed to the oils, which are sometimes ingested but generally massaged into the skin. Aromatherapy was first used in ancient Greece and Egypt, but became a forgotten ar...

are
Metric unit of area, equal to 100 square metres (119.6 sq yd); 100 ares make one hectare

arpeggio
In music, the sounding of a chord in a way that its notes are spread out and thus heard one after the other, usually from the bottom to the top. An example of arpeggios in early keyboard music can be found in Johann Sebastian Bach's Chromatic Fantasia and Fugue (1720, revised 1...

Arendt, Hannah
German-born US political philosopher. Her concerns included totalitarianism, the nature of evil, and the erosion of public participation in the political process. Her works include Eichmann in Jerusalem (1963) and On Violence (1972). In The Origins of Modern Totalitarianism (1951), she po...

architecture
Click images to enlargeArt of designing structures. The term covers the design of the visual appearance of structures; their internal arrangements of space; selection of external and internal building materials; design or selection of natural and artificial lighting systems, as well as mechanical, electrical, ...

arbor vitae
Any of several coniferous trees or shrubs belonging to the cypress family, with flattened branchlets covered in overlapping aromatic green scales. The northern white cedar (Thuja occidentalis) and the western red cedar (T. plicata) are found in North America. The Chinese or oriental species T. oriental...

Aryan
The hypothetical parent language of an ancient people believed to have lived between Central Asia and Eastern Europe and to have reached Persia and India in one direction and Europe in another, some time in the 2nd century BC, diversifying into the various Indo-European language speakers of later times. In Nazi Germany before the World War II, ...

armistice
Click images to enlargeCessation of hostilities while awaiting a peace settlement. The Armistice refers specifically to the end of World War I between Germany and the Allies on 11 November 1918. On 22 June 1940, following the German invasion of France, French representatives signed an armistice with Germany in the same ra...

arachnid
Type of arthropod of the class Arachnida, including spiders, scorpions, ticks, and mites. They differ from insects in possessing only two main body regions, the cephalothorax and the abdomen, and in having eight legs

Arizona
Click images to enlargeState in southwestern USA, bordered to the east by New Mexico, to the south by the Mexican state of Sonora, to the west by the Mexican state of Baja California and the US states of California and Nevada, and to the north by Utah and, at the `Four Corners` to the northeast, Colorado; ar...

Arkansas
State in southern central USA, bordered to the south by Louisiana, to the southwest by Texas, to the west by Oklahoma, to the north by Missouri, and to the east by Tennessee and Mississippi; area 134,856 sq km/52,068 sq mi; population (2006) 2,810,900; capital and largest city Little ...

artery
Click images to enlargeBlood vessel that carries blood from the heart to any part of the body. It is built to withstand considerable pressure, having thick walls that contain muscle and elastic fibres. As blood pulses out of the heart, arteries expand to allow for the increase in pressure – this elasticity helps the ...

Armani, Giorgio
Italian fashion designer. He launched his first menswear collection in 1974 and the following year started designing women's clothing. His work is known for understated styles and fine fabrics. He pioneered the `unstructured jacket` and the `power suit` for both men and women during the 1980s. His designs are marketed under ...

Armenian
Member of the largest ethnic group inhabiting Armenia. There are Armenian minorities in Azerbaijan (see Nagorno-Karabakh), as well as in Syria, Lebanon, Turkey, and Iran. Christianity was introduced to the ancient Armenian kingdom in the 3rd century. There are 4–5 million speakers of Armenian, which belongs to the Indo-European family ...

aromatic compound
Organic chemical compound in which some of the bonding electrons are delocalized (shared among several atoms within the molecule and not localized in the vicinity of the atoms involved in bonding). The commonest aromatic compounds have ring structures, the atoms comprising the ring being either all c...

arms trade
Sale of conventional weapons, such as tanks, combat aircraft, and related technology, from a manufacturing country to another nation. Arms exports are known in the trade as `arms transfers`. Most transfers take place between governments and can be accompanied by training and maintenance agreements. International agreements, such as the Nu...

artefact
Any object that has been used, modified, or manufactured by humans, such as a tool, weapon, or vessel. In art, an artefact is a product of human skill and creativity, while in archaeology, the object may be a simple item of importance and interest

Aristide, Jean-Bertrand
President of Haiti 1990–91, 1994–95, and 2001–04. A left-wing Catholic priest opposed to the right-wing regime of the Duvalier family, he relinquished his priesthood in 1994 to concentrate on the presidency. He initially campaigned for the National Front for Change and Democracy, representing a loose coalition of peasants, tr...

armed forces
State military organizations; the army, navy, and air force

arithmetic and logic unit
In computing, the part of the central processing unit (CPU) that performs the basic arithmetic and logic operations on data

arable farming
Click images to enlargeCultivation of crops, as opposed to the keeping of animals. Crops may be cereals, vegetables, or plants for producing oils or cloth. Arable farming generally requires less attention than livestock farming. In a mixed farming system, crops may therefore be found farther from the farm centre than anim...

arch
(earth science) In geomorphology (the study of landforms), any natural bridge-like land feature formed by erosion. Most sea arches are formed from the wave erosion of a headland where the backs of two caves have met and broken thr...

arid region
Click images to enlargeIn earth science, a region that is very dry and has little vegetation. Aridity depends on temperature, rainfall, and evaporation, and so is difficult to quantify, but an arid area is usually defined as one that receives less than 250 mm/10 in of rainfall each year. (By comparison, New York City ...

arithmetic mean
Average of a set of n numbers, obtained by adding the numbers and dividing by n. For example, the arithmetic mean of the set of 5 numbers 1, 3, 6, 8, and 12 is (1 + 3 + 6 + 8 + 12) ÷ 5 = 30 ÷ 5 = 6. The term average is often used to refer only to the arithmetic mean, even thoug...

Armenia
Click images to enlargeCountry in western Asia, bounded east by Azerbaijan, north by Georgia, west by Turkey, and south by Iran. Government Armenia has a multiparty presidential political system. There is a directly-elected executive president, who serves a four-year term. Candidates must secure over 50% of th...

Arab Maghreb Union
Association formed in 1989 by Algeria, Libya, Mauritania, Morocco, and Tunisia to formulate common policies on military, economic, international, and cultural issues

Archipelago de las Perlas
Group of 227 largely uninhabited islands in the Gulf of Panama, Central America, 64 km/40 mi southeast of Panama, to which republic the islands belong. The main islands are San Miguel (the largest), San José, and Pedro González. The main industries are deep-sea fishing, and sea angling by tourists

Arsacid dynasty
Rulers of ancient Parthia c. 250 BC–AD 226, who took their titles from their founder Arsaces. At its peak the dynasty controlled a territory from eastern India to western Mesopotamia, with a summer capital at Ecbatana and a winter palace at Ctesiphon. Claiming descent from the Persian Achaemenids, but adopting Hellenistic Gr...

aristocracy
Social elite or system of political power associated with landed wealth, as in Western Europe; with monetary wealth, as in Carthage and Venice; or with religious superiority, as were the Brahmans in India. Aristocracies are also usually associated with monarchy but have frequently been in conflict with the sovereign over their respective ri...

arabesque
(art) In the visual arts and architectural design, a linear decoration based on plant forms. Arabesque motifs are complicated, intertwined, flowing designs first found in ancient Arabic art – hence the term. They are a feature of ancient Greek and Roman art, and are particularly common in...

art for art's sake
Artistic theory; see aestheticism

archetype
Typical or perfect specimen of its kind. In the psychology of Carl Jung, it refers to one of the basic roles or situations, received from the collective unconscious, in which people tend to cast themselves – such as the Hero, the Terrible Mother (stepmother, witch); death, and rebirth. Archetypes are recurring motifs in myth, art, and lite...

arti
In Hinduism, a primary ritual for worship of the sacred image in a temple. A ghee (clarified butter) lamp, incense, flowers, and water are offered before the deity, using circular hand motions, to the accompaniment of bells and recitation of mantras

ARPANET
Early US network that forms the basis of the Internet. It was set up in 1969 by ARPA to provide services to US academic institutions and commercial organizations conducting computer science research. ARPANET pioneered many of today's networking techniques. It was renamed DARPANET when ARPA changed its name to Defense Advanced Research Projects ...

Arapaho
Member of an American Indian people who moved from Minnesota and North Dakota to the upper Missouri River area in the 17th century, where they became close allies of the Cheyenne. Their language belongs to the Algonquian family. Originally a farming people in the eastern woodlands, they acquired horses and adopted the nomadic existence of the Plain...

arcade
Series of arches carried on piers or columns. The earliest examples are found in Rome, dating from the 1st century BC. Rows of arches were frequently used as decoration, internally or externally, in Early Christian, Lombard, and other forms of Romanesque architecture, and less commonly in Gothic. They are described as `arcading`. In moder...

Argyll and Bute
Click images to enlargeUnitary authority in western Scotland, created in 1996 from the district of the same name and part of Dumbarton district, which were both parts of Strathclyde region; it includes the islands of Gigha, Bute, Mull, Islay, Jura, Tiree, Coll, Colonsay, Iona, and Staffa. Area 7,016 sq km/2,709 sq...

art brut
Term coined by the French artist Jean Dubuffet to describe various types of art produced outside the conventional art world. Literally the term means `raw art`, but it is sometimes translated into English as outsider art. The outsiders who practise such art include people in prison or psychiatric hospital. Dubuffet believed that the work ...

argali
Wild sheep from the mountains of Central Asia. It is the largest species of sheep with a shoulder height of up to 1.2 m/4 ft. Argali Ovis ammon is in family Bovidae, order Artiodactyla

Arthur
Semi-legendary Romano-British warleader who led British resistance against the Saxons, Picts, and Scots in the first half of the 6th century. He was probably a warlord rather than a king. He operated throughout Britain, commanding a small force of mobile warriors, reminiscent of the late Roma...

Armitage, Simon
English poet. He uses the honest, no-nonsense language and rhythms of the village where he lives, Marsden, near Huddersfield, England. He explores themes of belief, trust, creation, sacrifice, and identity in everyday life, with subjects as wide-ranging as cricket matches, love affairs, and astronomy. He won an Eric Gregory Award in 1988 fo...

Armstrong, Lance
US cyclist, who won a record seven consecutive Tour de France titles. His first Tour victory in 1999 came just 18 months after returning to competition following a life-threatening battle against cancer. In 2004 he won his sixth consecutive Tour to break the record set by Miguel Indurain in 1995. On winning his seventh Tour in 2005, he retired ...

Archangel
(port) English name for Arkhangelsk, a port in the north of the Russian Federation

Arbil
Alternative name for Irbil, a governate in northern Iraq; and Irbil, its capital

Archipel des Tuamotu
French name for Tuamotu Archipelago, part of French Polynesia

Ar Riyad
Arabic name for Riyadh, the capital of Saudi Arabia

Archipel de la Société
French name for the Society Islands, an archipelago in French Polynesia

article
(piece of writing) Prose piece of writing, discussing or describing a topic or issue, often written for a specific publication. For example, this is a very short article. For more information on style and structure see essay

Ardas
In Sikh worship, a prayer said at the end of communal worship or at home. It was developed in the 18th century. Ardas is performed after morning and evening prayers, and on special occasions such as a naming ceremony (Nam Karan), Amrit Sanskar (baptism into the Khalsa), marriage (Anand Karaj), or funeral. In the gurdwara (Sikh temple) it is followe...

aspidistra
Any of several Asiatic plants of the lily family. The Chinese Aspidistra elatior has broad leaves which taper to a point and, like all aspidistras, grows well in warm indoor conditions. (Genus Aspidistra, family Liliaceae.)

asphodel
Either of two related Old World plants of the lily family. The white asphodel or king's spear (Asphodelus albus) is found in Italy and Greece, sometimes covering large areas, and providing grazing for sheep. The other asphodel is the yellow asphodel (Asphodeline lutea). (Genera Asphodelus...

aster
Any plant of a large group belonging to the same subfamily as the daisy. All asters have starlike flowers with yellow centres and outer rays (not petals) varying from blue and purple to white. Asters come in many sizes. Many are cultivated as garden flowers, including the Michaelmas daisy (Aster nova-belgii). (Genus ...

asparagus
Any of a group of plants with small scalelike leaves and many fine, feathery branches. Native to Europe and Asia, Asparagus officinalis is cultivated and the tender young shoots (spears) are greatly prized as a vegetable. (Genus Asparagus, family Liliaceae.)

aspen
Any of several species of poplar tree. The European quaking aspen (Populus tremula) has flattened leafstalks that cause the leaves to flutter in the slightest breeze. The soft, light-coloured wood is used for matches and paper pulp. (Genus Populus.)

ash
Any tree of a worldwide group belonging to the olive family, with winged fruits. The mountain ash or rowan, which resembles the ash, belongs to the family Rosaceae. (Genus Fraxinus, family Oleaceae.)

astrophysics
Study of the physical nature of stars, galaxies, and the universe. It began with the development of spectroscopy in the 19th century, which allowed astronomers to analyse the composition of stars from their light. Astrophysicists view the universe as a vast natural laboratory in which they can study ...

astrometry
Measurement of the precise positions of stars, planets, and other bodies in space. Such information is needed for practical purposes including accurate timekeeping, surveying and navigation, and calculating orbits and measuring distances in space. Astrometry is not concerned with the surface features or the physical nature of the body under study. ...

astrolabe
Ancient navigational instrument, forerunner of the sextant. Astrolabes usually consisted of a flat disc with a sighting rod that could be pivoted to point at the Sun or bright stars. From the altitude of the Sun or star above the horizon, the local time could be estimated

astatine
Non-metallic, radioactive element, atomic number 85, relative atomic mass 210. It is a member of the halogen group, and is found at the bottom of Group 7 of the periodic table of the elements. It is very rare in nature. Astatine is highly unstable, with at least 19 isotopes; the longest lived has a half-life of about eight hours

assay
In chemistry, the determination of the quantity of a given substance present in a sample. Usually it refers to determining the purity of precious metals. In biochemistry, it refers to quantitative measurements, for example of enzyme activity. The assay may be carried out by `wet` methods, when the sample is wholly or partially dissolved i...

ascorbic acid
Relatively simple organic acid found in citrus fruits and vegetables. It is soluble in water and destroyed by prolonged boiling, so soaking or overcooking of vegetables reduces their vitamin C content. Lack of ascorbic acid results in scurvy. In the human body, ascorbic acid is necessary for the correct synthesis of collagen. Lack of vitamin C caus...

Asyut
Commercial centre in southern Egypt, near the west bank of the Nile, 322 km/200 mi south of Cairo; population (1996) 343,500, (2007 calc) 438,400. It is the capital of the governorate (area 1,600 sq km/618 sq mi; population (1996) 2,802,185) of the same name. One of the Nile dams is located here. An ancient Graeco-Egyptian city,...

asthenosphere
Layer within Earth's mantle lying beneath the lithosphere, typically beginning at a depth of approximately 100 km/63 mi and extending to depths of approximately 260 km/160 mi. Sometimes referred to as the `weak sphere`, it is characterized by being weaker and more elastic than the surrounding mantle. The asthenosphere's el...

asterisk
Starlike punctuation mark (*) used to link the asterisked word with a footnote at the bottom of a page, and in place of certain letters in a word (usually a taboo word)

astronomical unit
Unit equal to the mean distance of the Earth from the Sun: 149.6 million km/92.96 million mi. It is used to describe planetary distances. Light travels this distance in approximately 8.3 minutes

assembly language
Low-level computer-programming language closely related to a computer's internal codes. It consists chiefly of a set of short sequences of letters (mnemonics), which are translated, by a program called an assembler, into machine code for the computer's central processing unit (CPU) to follow directly. In assembly language, for examp...

Asturias
(autonomous community) Autonomous community and province of northern Spain; area 10,565 sq km/4,079 sq mi; population (2001 est) 1,075,300. The region is crossed by the well-forested Cantabrian Mountains and drained by numerous swift rivers. The mountain climate favours a large...

Asunción
Capital and chief port of Paraguay, situated on the east bank of the Paraguay River, near its confluence with the River Pilcomayo; population (2002 est) 513,400 (metropolitan area 1,620,500); there are textile, footwear, furniture, tobacco, and food-processing industries. The climate is subtropical, and cattle are raised in the surround...

Asti
(town) Town in Piedmont, southeast of Turin, Italy; population (2001) 71,300. Asti province is famed for its sparkling wine. Other products include chemicals, textiles, and glass. The town has annual jousting and gastronomic festivals

Astor
Prominent US and British family. John Jacob Astor (1763–1848) emigrated from Germany to the USA in 1783, and became a millionaire. His great-grandson Waldorf Astor, 2nd Viscount Astor (1879–1952), was a British politician, and served as Conservative member of Parliament for Plymouth from 1910 to 1919, when he succeeded to the peerage....

asthma
Chronic condition characterized by difficulty in breathing due to spasm of the bronchi (air passages) in the lungs. Attacks may be provoked by allergy, infection, and stress. The incidence of asthma may be increasing as a result of air pollution and occupational hazard. Treatment is with bronchodilators to relax the bronchial muscles and thereby ea...

assassination
Murder, usually of a political, royal, or public person. The term derives from the order of the Assassins, a Muslim sect that, in the 11th and 12th centuries, murdered officials to further its political ends

Assam
State of northeast India; area 78,523 sq km/30,318 sq mi; population (2001 est) 26,638,400. The state includes 12 million Assamese (Hindus), 5 million Bengalis (chiefly Muslim immigrants from Bangladesh), Nepalis, and 2 million indigenous people (Christian and traditional religions). Assamese is the official language. Half of India'...

Asquith, Herbert Henry
British Liberal politician, prime minister 1908–16. As chancellor of the Exchequer, he introduced old-age pensions in 1908. He limited the powers of the House of Lords and attempted to give Ireland home rule

Assad, Hafez al
Syrian Ba'athist politician, president 1971–2000. He became prime minister after a bloodless military coup in 1970. The following year he became the first president to be elected by popular vote. Having suppressed dissent, he was re-elected in 1978, 1985, 1991, and 1999. He was a Shia (Alawite) Muslim. He ruthlessly suppressed domestic...

aspirin
Acetylsalicylic acid, a popular pain-relieving drug (analgesic) developed in the late 19th century as a household remedy for aches and pains. It relieves pain and reduces inflammation and fever. It is the world's most widely used drug. Aspirin was first refined from salicylic acid by German chemist Felix Hoffman, and marketed in 1899. Altho...

Asoka
Mauryan emperor of India c. 268–232 BC, the greatest of the Mauryan rulers. He inherited an empire covering most of north and south-central India which, at its height, had a population of at least 30 million, with its capital at Pataliputra. A devout Buddhist, he renounced militarism and concentrated on establishing an e...

Asmara
Capital of Eritrea, 64 km/40 mi southwest of the port of Massawa on the Red Sea and 2,300 m/7,546 ft above sea level; population (2002 est) 392,500. Products include beer, clothes, leather goods, cement, and textiles. The University of Asmara is here, together with a naval school, a cathedral and many modern buildings. The population is...

Asian Republics, Central
See Central Asian Republics

Ash Wednesday
First day of Lent, the period of fasting in the Christian calendar leading up to Easter. Christians used to cover their heads with ashes to show repentance, a custom continued today by some Christians, including Roman Catholics, who mark their foreheads with a cross in ash, as a sign of penitence (sorrow for sins)

Ashley, Laura
Welsh textile designer who established, and gave her name to, a neo-Victorian country style in clothes and furnishings using natural materials, manufactured by her company. Her first shop became a model for an internationally successful retailing chain. Ashley began the business in 1953 with her husband, and soon after she began experimenting w...

Ashgabat
Capital of Turkmenistan; population (2001 est) 695,300. Industries include the manufacture of glass, carpets (handwoven `Bukhara` carpets and rugs are made here), cotton goods, and metalworking. The city is in a spectacular natural setting, between the Kara-Kum Desert and the Kopet-Dag mountain range. History A settlement on t...

Ashkenazy, Vladimir Davidovich
Russian-born pianist and conductor. He was principal conductor of the Royal Philharmonic, London, 1987–94 and of the Czech Philharmonic Orchestra 1988–2003. He excels in his interpretations of pieces by Rachmaninov, Prokofiev, and Liszt. Other positions include music director of the Deutsches Symphonie-Orchester Berlin 1989–9...

Ashcroft, Peggy
English actor. Her Shakespearean roles included Desdemona in Othello (1930) (with Paul Robeson) and Juliet in Romeo and Juliet (1935) (with Laurence Olivier and John Gielgud), and she appeared in the British TV play Caught on a Train (1980; BAFTA award), the series The Jewel in t...

Ashcan School
Group of US realist painters active about 1908–14. So-called because of their chosen subject matter, the School's central figures were Robert Henri, George Luks, William Glackens, Everett Shinn, and John Sloan, all former members of The Eight (a group of realist painters who exhibited together in 1908 outside of the official circuit). ...

Ascension
British island of volcanic origin in the South Atlantic, a dependency of St Helena since 1922; area 88 sq km/34 sq mi; population (2001 est) 1,100 (excluding military personnel). The chief settlement is Georgetown. A Portuguese navigator landed on the island on Ascension Day in 1501, but it remained uninhabited until occupied by Britain...

Asclepius
In Greek mythology, the god of medicine (Roman Aesculapius); son of Apollo; father of Panacea and Hygieia, goddess of health. His emblem was the caduceus, a winged staff encoiled by two snakes; the creatures appear to renew life by shedding their skin. His worship originated in Thessaly in northern Greece, but the major sanctuary of the...

Asturias, Miguel Ángel
Guatemalan author and diplomat. He published poetry, Guatemalan legends, and novels, such as El señor presidente/The President (1946), Men of Corn (1949), and Strong Wind (1950), attacking Latin-American dictatorships and `Yankee imperialism`. He was awarded the Nobel P...

astronomy
Click images to enlargeScience of the celestial bodies: the Sun, the Moon, and the planets; the stars and galaxies; and all other objects in the universe. It is concerned with their positions, motions, distances, and physical conditions and with their origins and evolution. Astronomy thus divides into fields s...