arch |
carrot |
top 10 words in brain distribution (in article): build material wood structure form state type wall building surface |
top 10 words in brain distribution (in article): plant fruit produce seed grow leaf flower sugar type variety |
top 10 words in brain distribution (not in article): city house cell store street town home floor design Unite |
top 10 words in brain distribution (not in article): key lock switch tree machine light needle tube bicycle contain |
times more probable under arch 30 20 10 6 4 2.5 1.25 1 1.25 2.5 4 6 10 20 30 times more probable under carrot (words not in the model) | |
An arch'" is a structure that spans a space while supporting weight (e.g. a doorway in a stone wall). Arches appeared as early as the 2nd millennium BC in Mesopotamian brick architecture, but their systematic use started with the Ancient Romans who were the first to apply the technique to a wide range of structures. History. Arches were known by the Mesopotamian, Urartian, Harappan, Egyptian, Babylonian, Greek and Assyrian civilizations, but their use was infrequent and mostly confined to underground structures such as drains where the problem of lateral thrust is greatly diminished. The ancient Romans learned the arch from the Etruscans, refined it and were the first builders to tap its full potential for above ground buildings: "The Romans were the first builders in Europe, perhaps the first in the world, fully to appreciate the advantages of the arch, the vault and the dome." Throughout the Roman empire, their engineers erected arch structures such as bridges, aqueducts, and gates. They also introduced the triumphal arch as a military monument. Vaults began to be used for roofing large interior spaces such as halls and temples, a function which was also assumed by domed structures from the 1st century BC onwards. The Roman arch is semicircular, and built from an odd number of arch bricks (called "voussoirs"). An odd number of bricks is required for there to be a "capstone" or "keystone", the topmost stone in the arch. The Roman arch's shape is the simplest to build, but not the strongest. There is a tendency for the sides to bulge outwards, which must be counteracted by an added weight of masonry to push them inwards. The Romans used this type of semicircular arch freely in many of their secular structures such as aqueducts, palaces and amphitheaters. The semicircular arch was followed in Europe by the pointed Gothic arch or ogive (derived from the Islamic pointed arch in Moorish Spain), whose centreline more closely followed the forces of compression and which was therefore stronger. The semicircular arch can be flattened to make an elliptical arch as in the Ponte Santa Trinita. The parabolic and catenary arches are now known to be the theoretically strongest forms. Parabolic arches were introduced in construction by the Spanish architect Antoni Gaudí, who admired the structural system of Gothic style, but for the buttresses, which he termed “architectural crutches”. The catenary and parabolic arches carry all horizontal thrust to the foundation and so do not need additional elements. The horseshoe arch is based on the semicircular arch, but its lower ends are extended further round the circle until they start to converge. The first examples known are carved into rock in India in the first century AD, while the first known built horseshoe arches are known from Aksum (modern day Ethiopia and Eritrea) from around the 3rd–4th century, around the same time as the earliest contemporary examples in Syria, suggesting either an Aksumite or Syrian origin for the type of arch. It was used in Spanish Visigothic architecture, Islamic architecture and mudéjar architecture, as in the Great Mosque of Damascus and in later Moorish buildings. It was used for decoration rather than for strength. Across the ocean in Mexico and Central America, Mesoamerican civilizations created various types of corbelled arches, such as with the interior tunnels in the Great Pyramid of Cholula and the many styles of corbelled arches built by the Mayan civilization. In Peru, the Inca civilization used a trapezoidal arch in their architecture. The arch is still used today in some modern structures such as bridges. Construction. An arch requires all of its elements to hold it together, raising the question of how an arch is constructed. One answer is to build a frame (historically, of wood) which exactly follows the form of the underside of the arch. This is known as a centre or centring. The voussoirs are laid on it until the arch is complete and self-supporting. For an arch higher than head height, scaffolding would in any case be required by the builders, so the scaffolding can be combined with the arch support. Occasionally arches would fall down when the frame was removed if construction or planning had been incorrect. (The A85 bridge at Dalmally, Scotland suffered this fate on its first attempt, in the 1940s). The interior and lower line or curve of an arch is known as the "intrados". Old arches sometimes need reinforcement due to decay of the keystones, known as bald arch. The gallery shows arch forms displayed in roughly the order in which they were developed. Technical aspects. The arch is significant because, in theory at least, it provides a structure which eliminates tensile stresses in spanning an open space. All the forces are resolved into compressive stresses. This is useful because several of the available building materials such as stone, cast iron and concrete can strongly resist compression but are very weak when tension, shear or torsional stress is applied to them. By using the arch configuration, significant spans can be achieved. This is because all the compressive forces hold it together in a state of equilibrium. This even applies to frictionless surfaces. However, one downside is that an arch pushes outward at the base, and this needs to be restrained in some way, either with heavy sides and friction or angled cuts into bedrock or similar. This same principle holds when the force acting on the arch is not vertical such as in spanning a doorway, but horizontal, such as in arched retaining walls or dams. Even when using concrete, where the structure may be monolithic, the principle of the arch is used so as to benefit from the concrete's strength in resisting compressive stress. Where any other form of stress is raised, it has to be resisted by carefully placed reinforcement rods or fibres. (See Arch bridge.) Other types. The Delicate Arch, a natural arch in Moab, UtahA blind arch is an arch infilled with solid construction so it cannot function as a window, door, or passageway. A dome is a three-dimensional application of the arch, rotated about the center axis. Igloos are notable vernacular structures making use of domes. Natural rock formations may also be referred to as arches. These natural arches are formed by erosion rather than being carved or constructed by man. See Arches National Park for examples. A special form of the arch is the triumphal arch, usually built to celebrate a victory in war. A famous example is the Arc de Triomphe in Paris, France. A vault is an application of the arch extended horizontally in two dimensions; the groin vault is the intersection of two vaults. | The carrot'" ("Daucus carota" subsp. "sativus", Etymology: Middle French "carotte", from Late Latin "carōta", from Greek "karōton", originally from the Indoeuropean root "ker-" (horn), due to its horn-like shape) is a root vegetable, usually orange or white, or red-white blend in colour, with a crisp texture when fresh. The edible part of a carrot is a taproot. It is a domesticated form of the wild carrot "Daucus carota", native to Europe and southwestern Asia. It has been bred for its greatly enlarged and more palatable, less woody-textured edible taproot, but is still the same species. It is a biennial plant which grows a rosette of leaves in the spring and summer, while building up the stout taproot, which stores large amounts of sugars for the plant to flower in the second year. The flowering stem grows to about 1 metre (3 ft) tall, with an umbel of white flowers that produce a fruit called a mericarp by botanists, which is a type of schizocarp. Uses and nutrition. Carrots can be eaten in a variety of ways. The simplest way is raw as carrots are perfectly digestible without requiring cooking. Alternatively they may be chopped and boiled, fried or steamed, and cooked in soups and stews, as well as baby and pet foods. A well known dish is "carrots julienne". Grated carrots are used in carrot cakes, as well as carrot puddings, an old English dish thought to have originated in the early 1800s. The greens are edible as a leaf vegetable, but are rarely eaten by humans, as they are mildly toxic. Together with onion and celery, carrots are one of the primary vegetables used in a "mirepoix" to make various broths. Ever since the late 1980s, baby carrots or mini-carrots (carrots that have been peeled and cut into uniform cylinders) have been a popular ready-to-eat snack food available in many supermarkets. Carrot juice is also widely marketed, especially as a health drink, either stand-alone or blended with fruits and other vegetables. The carrot gets its characteristic and bright orange colour from β-carotene, which is metabolised into vitamin A in humans when bile salts are present in the intestines. Massive overconsumption of carrots can cause hypercarotenemia, a condition in which the skin turns orange (although hypercarotenemia is not itself dangerous unlike overdose of vitamin A, which can cause liver damage). Carrots are also rich in dietary fibre, antioxidants, and minerals. Lack of Vitamin A can cause poor vision, including night vision, and vision can be restored by adding Vitamin A back into the diet. The urban legend that says eating large amounts of carrots will allow one to see in the dark developed from stories of British gunners in World War II who were able to shoot down German planes in the darkness of night. The legend arose during the Battle of Britain when the RAF circulated a story about their pilots' carrot consumption as an attempt to cover up the discovery and effective use of radar technologies in engaging enemy planes. It reinforced existing German folklore and helped to encourage Britons—looking to improve their night vision during the blackouts—to grow and eat the vegetable. Ethnomedically, the roots are used to treat digestive problems, intestinal parasites, and tonsillitis or constipation. History. The wild ancestors of the carrot are likely to have come from Afghanistan, which remains the centre of diversity of "D. carota", the wild carrot. Selective breeding over the centuries of a naturally-occurring subspecies of the wild carrot, "Daucus carota" subsp. "sativus" reducing bitterness, increasing sweetness and minimizing the woody core, has produced the familiar garden vegetable. In early use, carrots were grown for their aromatic leaves and seeds, not their roots. Some relatives of the carrot are still grown for these, such as parsley, fennel, dill and cumin. The first mention of the root in classical sources is in the 1st century CE. The modern carrot appears to have been introduced to Europe in the 8-10th centuries; Ibn al-Awam, in Andalusia, describes both red and yellow carrots; Simeon Seth also mentions both colours in the 11th century. Orange-coloured carrots appeared in the Netherlands in the 17th century. These, the modern carrots, were intended by the antiquary John Aubrey (1626-1697) when he noted in his memoranda "Carrots were first sown at Beckington in Somersetshire Some very old Man there [in 1668] did remember their first bringing hither." In addition to wild carrot, these alternative (mostly historical) names are recorded for "Daucus carota": Bee's-nest, Bee's-nest plant, Bird's-nest, Bird's-nest plant, Bird's-nest root, Carota, Carotte (French), Carrot, Common carrot, Crow's-nest, Daucon, Dawke, Devil's-plague, Fiddle, Gallicam, Garden carrot, Gelbe Rübe (German), Gingidium, Hill-trot, Laceflower, Mirrot, Möhre (German), Parsnip (misapplied), Queen Anne's lace, Rantipole, Staphylinos, and Zanahoria. The parsnip is a close relative of the carrot, as is parsley. Cultivars. Carrot cultivars can be grouped into two broad classes, eastern carrots'" and "'western carrots'". More recently, a number of novelty cultivars have been bred for particular characteristics. The world's largest carrot was grown in Palmer, Alaska by John Evans in 1998, weighing 8.6 kg (19 lb). The city of Holtville, California promotes itself as "Carrot Capital of the World", and holds an annual festival devoted entirely to the carrot. Eastern carrots. Eastern carrots were domesticated in Central Asia, probably in modern-day Afghanistan in the 10th century, or possibly earlier. Specimens of the eastern carrot that survive to the present day are commonly purple or yellow, and often have branched roots. The purple colour common in these carrots comes from anthocyanin pigments. Western carrots. The western carrot emerged in the Netherlands in the 17th century, its orange colour making it popular in those countries as an emblem of the House of Orange and the struggle for Dutch independence. The orange colour results from abundant carotenes in these cultivars. While orange carrots are the norm in the West, other colours do exist, including white, yellow, red, and purple. These other colours of carrot are raised primarily as novelty crops. The Vegetable Improvement Center at Texas A&M University has developed a purple-skinned, orange-fleshed carrot, the "BetaSweet" (also known as the Maroon Carrot), with substances to prevent cancer, which has recently entered very limited commercial distribution, through J&D Produce of Edinburg TX. This variety of carrot is also known to be high in β-carotene which is an essential nutrient. The high concentrations of this nutrient give the carrot its maroon shade. Western carrot cultivars are commonly classified by their root shape: While any carrot can be harvested before reaching its full size as a more tender "baby" carrot, some fast-maturing cultivars have been bred to produce smaller roots. The most extreme examples produce round roots about 2.5 centimetres (1 in) in diameter. These small cultivars are also more tolerant of heavy or stony soil than long-rooted cultivars such as 'Nantes' or 'Imperator'. The "baby carrots" sold ready-to-eat in supermarkets are, however, often not from a smaller cultivar of carrot, but are simply full-sized carrots that have been sliced and peeled to make carrot sticks of a uniform shape and size. Carrot flowers are pollinated primarily by bees. Seed growers use honeybees or mason bees for their pollination needs. Carrots are used as food plants by the larvae of some Lepidoptera species, including Common Swift, Garden Dart, Ghost Moth, Large Yellow Underwing and Setaceous Hebrew Character. Novelty carrots. Food enthusiasts and researchers have developed other varieties of carrots through traditional breeding methods. Novelty carrots are also grown throughout Western Europe in flower pots and are noted for their distinctly minty flavour. One particular variety lacks the usual orange pigment from carotenes, owing its white colour to a recessive gene for tocopherol (Vitamin E). Derived from "Daucus carota" L. and patented (US patent #6,437,222) at the University of Wisconsin-Madison, the variety is intended to supplement the dietary intake of Vitamin E. Production trends. In 2005, China was the largest producer of carrots and turnips, according to the FAO. China accounted for at least one third of the global output, followed by Russia and the United States. In 2005, a poll of 2,000 people revealed that the carrot was Britain's third favourite culinary vegetable. |