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top 10 words in brain distribution (in article): water form light time animal cause surface type produce region |
top 10 words in brain distribution (in article): build city house material design state Unite town wood provide |
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top 10 words in brain distribution (not in article): ice rock drink river flow occur lamp sea wind soil |
top 10 words in brain distribution (not in article): power station store street line church train signal radio locomotive |
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times more probable under eye 30 20 10 6 4 2.5 1.25 1 1.25 2.5 4 6 10 20 30 times more probable under house (words not in the model) | |
| Eyes'" are organs that detect light, and send signals along the optic nerve to the visual and other areas of the brain. Complex optical systems with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system. Image-resolving eyes are present in cnidaria, mollusks, chordates, annelids and arthropods. The simplest "eyes", in even unicellular organisms, do nothing but detect whether the surroundings are light or dark, which is sufficient for the entrainment of circadian rhythms. From more complex eyes, retinal photosensitive ganglion cells send signals along the retinohypothalamic tract to the suprachiasmatic nuclei to effect circadian adjustment. Overview. Complex eyes can distinguish shapes and colors. The visual fields of many organisms, especially predators, involve large areas of binocular vision to improve depth perception; in other organisms, eyes are located so as to maximise the field of view, such as in rabbits and horses. The first proto-eyes evolved among animals 540 million years ago, about the time of the so-called Cambrian explosion. The last common ancestor of animals possessed the biochemical toolkit necessary for vision, and more advanced eyes have evolved in 96% of animal species in 6 of the thirty-something main phyla. In most vertebrates and some mollusks, the eye works by allowing light to enter it and project onto a light-sensitive panel of cells, known as the retina, at the rear of the eye. The cone cells (for color) and the rod cells (for low-light contrasts) in the retina detect and convert light into neural signals for vision. The visual signals are then transmitted to the brain via the optic nerve. Such eyes are typically roughly spherical, filled with a transparent gel-like substance called the vitreous humour, with a focusing lens and often an iris; the relaxing or tightening of the muscles around the iris change the size of the pupil, thereby regulating the amount of light that enters the eye, and reducing aberrations when there is enough light. The eyes of cephalopods, fish, amphibians and snakes usually have fixed lens shapes, and focusing vision is achieved by telescoping the lens — similar to how a camera focuses. Compound eyes are found among the arthropods and are composed of many simple facets which, depending on the details of anatomy, may give either a single pixelated image or multiple images, per eye. Each sensor has its own lens and photosensitive cell(s). Some eyes have up to 28,000 such sensors, which are arranged hexagonally, and which can give a full 360-degree field of vision. Compound eyes are very sensitive to motion. Some arthropods, including many Strepsiptera, have compound eyes of only a few facets, each with a retina capable of creating an image, creating vision. With each eye viewing a different thing, a fused image from all the eyes is produced in the brain, providing very different, high-resolution images. Possessing detailed hyperspectral color vision, the Mantis shrimp has been reported to have the world's most complex color vision system. Trilobites, which are now extinct, had unique compound eyes. They used clear calcite crystals to form the lenses of their eyes. In this, they differ from most other arthropods, which have soft eyes. The number of lenses in such an eye varied, however: some trilobites had only one, and some had thousands of lenses in one eye. In contrast to compound eyes, simple eyes are those that have a single lens. For example, jumping spiders have a large pair of simple eyes with a narrow field of view, supported by an array of other, smaller eyes for peripheral vision. Some insect larvae, like caterpillars, have a different type of simple eye (stemmata) which gives a rough image. Some of the simplest eyes, called ocelli, can be found in animals like some of the snails, which cannot actually "see" in the normal sense. They do have photosensitive cells, but no lens and no other means of projecting an image onto these cells. They can distinguish between light and dark, but no more. This enables snails to keep out of direct sunlight. In organisms dwelling near deep-sea vents, compound eyes have been secondarily simplified and adapted to spot the infra-red light produced by the hot vents in this way the bearers can spot hot springs and avoid being boiled alive. Evolution. Visual pigments appear to have a common ancestor and were probably involved in circadian rhythms or reproductive timing in simple organisms. Complex vision, associated with dedicated visual organs, or eyes, evolved many times in different lineages. Types of eye. Nature has produced ten different eye layouts — indeed every way of capturing an image has evolved at least once in nature, with the exception of zoom and Fresnel lenses. Eye types can be categorized into "simple eyes", with one concave chamber, and "compound eyes", which comprise a number of individual lenses laid out on a convex surface. Note that "simple" does not imply a reduced level of complexity or acuity. Indeed, any eye type can be adapted for almost any behaviour or environment. The only limitations specific to eye types are that of resolution — the physics of compound eyes prevents them from achieving a resolution better than 1°. Also, superposition eyes can achieve greater sensitivity than apposition eyes, so are better suited to dark-dwelling creatures. Eyes also fall into two groups on the basis of their photoreceptor's cellular construction, with the photoreceptor cells either being cilliated (as in the vertebrates) or rhabdomic. These two groups are not monophyletic; the cnidaira also possess cilliated cells, Pit eyes. Pit eyes, also known as stemma, are eye-spots which may be set into a pit to reduce the angles of light that enters and affects the eyespot, to allow the organism to deduce the angle of incoming light. Found in about 85% of phyla, these basic forms were probably the precursors to more advanced types of "simple eye". They are small, comprising up to about 100 cells covering about 100 µm. The directionality can be improved by reducing the size of the aperture, by incorporating a reflective layer behind the receptor cells, or by filling the pit with a refractile material. Pinhole eye. The pinhole eye is an "advanced" form of pit eye incorporating these improvements, most notably a small aperture (which may be adjustable) and deep pit. It is only found in the nautiloids. Without a lens to focus the image, it produces a blurry image, and will blur out a point to the size of the aperture. Consequently, nautiloids can't discriminate between objects with an angular separation of less than 11°. Shrinking the aperture would produce a sharper image, but let in less light. Spherical lensed eye. The resolution of pit eyes can be greatly improved by incorporating a material with a higher refractive index to form a lens, which may greatly reduce the blur radius encountered — hence increasing the resolution obtainable. The most basic form, still seen in some gastropods and annelids, consists of a lens of one refractive index. A far sharper image can be obtained using materials with a high refractive index, decreasing to the edges — this decreases the focal length and thus allows a sharp image to form on the retina. This also allows a larger aperture for a given sharpness of image, allowing more light to enter the lens; and a flatter lens, reducing spherical aberration. Such an inhomogeneous lens is necessary in order for the focal length to drop from about 4 times the lens radius, to 2.5 radii. Heterogeneous eyes have evolved at least eight times — four or more times in gastropods, once in the copepods, once in the annelids and once in the cephalopods. No aquatic organisms possess homogeneous lenses; presumably the evolutionary pressure for a heterogeneous lens is great enough for this stage to be quickly "outgrown". This eye creates an image that is sharp enough that motion of the eye can cause significant blurring. To minimize the effect of eye motion while the animal moves, most such eyes have stabilizing eye muscles. The ocelli of insects bear a simple lens, but their focal point always lies behind the retina; consequently they can never form a sharp image. This capitulates the function of the eye. Ocelli (pit-type eyes of arthropods) blur the image across the whole retina, and are consequently excellent at responding to rapid changes in light intensity across the whole visual field — this fast response is further accelerated by the large nerve bundles which rush the information to the brain. Focussing the image would also cause the sun's image to be focussed on a few receptors, with the possibility of damage under the intense light; shielding the receptors would block out some light and thus reduce their sensitivity. This fast response has led to suggestions that the ocelli of insects are used mainly in flight, because they can be used to detect sudden changes in which way is up (because light, especially UV light which is absorbed by vegetation, usually comes from above). Weaknesses. One weakness of this eye construction is that chromatic aberration is still quite high — although for organisms without color vision, this is a very minor concern. A weakness of the vertebrate eye is the blind spot which results from a gap in the retina where the optic nerve exits at the back of the eye; the cephalopod eye has no blind spot as the retina is in the opposite orientation. Multiple lenses. Some marine organisms bear more than one lens; for instance the copeopod "Pontella" has three. The outer has a parabolic surface, countering the effects of spherical aberration while allowing a sharp image to be formed. "Copilla'"s eyes have two lenses, which move in and out like a telescope. Such arrangements are rare and poorly understood, but represent an interesting alternative construction. An interesting use of multiple lenses is seen in some hunters such as eagles and jumping spiders, which have a refractive cornea (discussed next): these have a negative lens, enlarging the observed image by up to 50% over the receptor cells, thus increasing their optical resolution. Refractive cornea. In the eyes of most terrestrial vertebrates (along with spiders and some insect larvae) the vitreous fluid has a higher refractive index than the air, relieving the lens of the function of reducing the focal length. This has freed it up for fine adjustments of focus, allowing a very high resolution to be obtained. As with spherical lenses, the problem of spherical aberration caused by the lens can be countered either by using an inhomogeneous lens material, or by flattening the lens. Flattening the lens has a disadvantage: the quality of vision is diminished away from the main line of focus, meaning that animals requiring all-round vision are detrimented. Such animals often display an inhomogeneous lens instead. As mentioned above, a refractive cornea is only useful out of water; in water, there is no difference in refractive index between the vitreous fluid and the surrounding water. Hence creatures which have returned to the water — penguins and seals, for example — lose their refractive cornea and return to lens-based vision. An alternative solution, borne by some divers, is to have a very strong cornea. Reflector eyes. An alternative to a lens is to line the inside of the eye with mirrors", and reflect the image to focus at a central point. The nature of these eyes means that if one were to peer into the pupil of an eye, one would see the same image that the organism would see, reflected back out. Many small organisms such as rotifers, copeopods and platyhelminths use such organs, but these are too small to produce usable images. Some larger organisms, such as scallops, also use reflector eyes. The scallop "Pecten" has up to 100 millimeter-scale reflector eyes fringing the edge of its shell. It detects moving objects as they pass successive lenses. Compound eyes. A compound eye may consist of thousands of individual photoreception units. The image perceived is a combination of inputs from the numerous ommatidia (individual "eye units"), which are located on a convex surface, thus pointing | A house'" generally refers to a or building that is a dwelling or place for habitation by humans. The term includes many kinds of dwellings ranging from rudimentary huts of nomadic tribes to high-rise apartment buildings. However, the word can also be used as a verb ("to house"), and can have adjectival formations as well. In some contexts, "house" may mean the same as dwelling, residence, home, abode, accommodation, housing, lodging, among other meanings. The social unit that lives in a house is known as a household. Most commonly, a household is a family unit of some kind, though households can be other social groups, such as single persons, or groups of unrelated individuals. Settled agrarian and industrial societies are composed of household units living permanently in housing of various types, according to a variety of forms of land tenure. English-speaking people generally call any building they routinely occupy "home". Many people leave their houses during the day for work and recreation but typically return to them to sleep or for other activities. History. The oldest house in the world is approximately from 10,000 BC and was made of mammoth bones, found at Mezhirich near Kiev in Ukraine. It was probably covered with mammoth hides. The house was discovered in 1965 by a farmer digging a new basement six feet below the ground. Architect Norbert Schoenauer, in his book "6,000 Years of Housing", identifies three major categories of types of housing: the "Pre-Urban" house, the "Oriental Urban" house, and the "Acidental Urban" house. Types of Pre-Urban houses include temporary dwellings such as the Inuit igloo, semi-permanent dwellings such as the pueblo, and permanent dwellings such as the New England homestead. "Oriental Urban" houses include houses of the ancient Greeks and Romans, and traditional urban houses in China, India, and Islamic cities. "Occidental Urban" houses include medieval urban houses, the Renaissance town house, and the houses, tenements and apartments of the 19th and 20th centuries. Houses of that time were generally made of simple and raw materials. Structure. The developed world in general features three basic types of house that have their own ground-level entry and private open space, and usually on a separately titled parcel of land: In addition, there are various forms of attached housing where a number of dwelling units are co-located within the same structure, which share a ground-level entry and may or may not have any private open space, such as apartments (a.k.a. flats) of various scales. Another type of housing is movable, such as houseboats, caravans, and trailer homes. In the United Kingdom, 27% of the population live in terraced houses and 32% in semi-detached houses, as of 2002. In the United States as of 2000, 61.4% of people live in detached houses and 5.6% in semi-detached houses, 26% in row houses or apartments, and 7% in mobile homes. Shape. Archaeologists have a particular interest in house shape: they see the transition over time from round huts to rectangular houses as a significant advance in optimizing the use of space, and associate it with the growth of the idea of a personal area (see personal space). Function. Some houses transcend the basic functionality of providing "a roof over one's head" or of serving as a family "hearth and home". When a house becomes a display-case for wealth and or fashion and or conspicuous consumption, we may speak of a "great house". The residence of a feudal lord or of a ruler may require defensive structures and thus turn into a fort or a castle. The house of a monarch may come to house courtiers and officers as well as the royal family: this sort of house may become a palace. Moreover, in time the lord or monarch may wish to retreat to a more personal or simple space such as a villa, a hunting lodge or a dacha. Compare the popularity of the holiday house or cottage, also known as a crib. In contrast to a relatively upper class or modern trend to ownership of multiple houses, much of human history shows the importance of multi-purpose houses. Thus the house long served as the traditional place of work (the original cottage industry site or "in-house" small-scale manufacturing workshop) or of commerce (featuring, for example, a ground floor "shop-front" shop or counter or office, with living space above). During the Industrial Revolution there was a separation of manufacturing and banking from the house, though to this day some shopkeepers continue (or have returned) to live "over the shop". Layout. Ideally, architects of houses design rooms to meet the needs of the people who will live in the house. Such designing, known as "interior design", has become a popular subject in universities. Feng shui, originally a Chinese method of situating houses according to such factors as sunlight and micro-climates, has recently expanded its scope to address the design of interior spaces with a view to promoting harmonious effects on the people living inside the house. Feng shui can also mean the 'aura' in or around a dwelling. Compare the real-estate sales concept of "indoor-outdoor flow". The square footage of a house in the United States reports the area of "living space", excluding the garage and other non-living spaces. The "square meters" figure of a house in Europe reports the area of the walls enclosing the home, and thus includes any attached garage and non-living spaces. Parts. Many houses have several rooms with specialized functions. These may include a living eating area, a sleeping area, and (if suitable facilities and services exist) washing and lavatory areas. In traditional agriculture-oriented societies, domestic animals such as chickens or larger livestock (like cattle) often share part of the house with human beings. Most conventional modern houses will at least contain a bedroom, bathroom, kitchen (or kitchen area), and a living room. A typical "foursquare house" (as pictured) occurred commonly in the early history of the United States of America, with a staircase in the center of the house, surrounded by four rooms, and connected to other sections of the house (including in more recent eras a garage). The names of parts of a house often echo the names of parts of other buildings, but could typically include: Construction. In the United States, modern house-construction techniques include light-frame construction (in areas with access to supplies of wood) and adobe or sometimes rammed-earth construction (in arid regions with scarce wood-resources). Some areas use brick almost exclusively, and quarried stone has long provided walling. To some extent, aluminum and steel have displaced some traditional building materials. Increasingly popular alternative construction materials include insulating concrete forms (foam forms filled with concrete), structural insulated panels (foam panels faced with oriented strand board or fiber cement), and light-gauge steel framing and heavy-gauge steel framing. More generally, people often build houses out of the nearest available material, and often tradition and or culture govern construction-materials, so whole towns, areas, counties or even states countries may be built out of one main type of material. For example, a large fraction of American houses use wood, while most British and many European houses utilize stone or brick. In the 1900s, some house designers started using prefabrication. Sears, Roebuck & Co. first marketed their Houses by Mail to the general public in 1908. Prefab techniques became popular after World War II. First small inside rooms framing, then later, whole walls were prefabricated and carried to the construction site. The original impetus was to use the labor force inside a shelter during inclement weather. More recently builders have begun to collaborate with structural engineers who use computers and finite element analysis to design prefabricated steel-framed homes with known resistance to high wind-loads and seismic forces. These newer products provide labor savings, more consistent quality, and possibly accelerated construction processes. Lesser-used construction methods have gained (or regained) popularity in recent years. Though not in wide use, these methods frequently appeal to homeowners who may become actively involved in the construction process. They include: Energy-efficiency. In the developed world, energy-conservation has grown in importance in house-design. Housing produces a major proportion of carbon emissions (30% of the total in the UK, for example). Development of a number of types and techniques continues. They include the zero-energy house, the passive solar house, superinsulated and houses built to the "Passivhaus" standard. Earthquake protection. One tool of earthquake engineering is base isolation which is increasingly used for earthquake protection. Base isolation is a collection of structural elements of a building that should substantially decouple it from the shaking ground thus protecting the building's integrity and enhancing its seismic performance. This technology, which is a kind of seismic vibration control, can be applied both to a newly designed building and to seismic upgrading of existing structures. Normally, excavations are made around the building and the building is separated from the foundations. Steel or reinforced concrete beams replace the connections to the foundations, while under these, the isolating pads, or "base isolators", replace the material removed. While the "base isolation" tends to restrict transmission of the ground motion to the building, it also keeps the building positioned properly over the foundation. Careful attention to detail is required where the building interfaces with the ground, especially at entrances, stairways and ramps, to ensure sufficient relative motion of those structural elements. Legal issues. Buildings with historical importance have restrictions. United Kingdom. New houses in the UK are not covered by the Sale of Goods Act. When purchasing a new house the buyer has less legal protection than when buying a new car. New houses in the UK may be covered by a NHBC guarantee but some people feel that it would be more useful to put new houses on the same legal footing as other products. United States and Canada. In the US and Canada, many new houses are built in housing tracts, which provide homeowners a sense of "belonging" and the feeling they have "made the best use" of their money. However, these houses are often built as cheaply and quickly as possible by large builders seeking to maximize profits. Many environmental health issues are ignored or minimized in the construction of these structures. In one case in Benicia, California, a housing tract was built over an old landfill. Home buyers were never told, and only found out when some began having reactions to high levels of lead and chromium. Identifying houses. With the growth of dense settlement, humans designed ways of identifying houses and or parcels of land. Individual houses sometimes acquire proper names; and those names may acquire in their turn considerable emotional connotations: see for example the house of "Howards End" or the castle of "Brideshead Revisited". A more systematic and general approach to identifying houses may use various methods of house numbering. Animal houses. Humans often build "houses" for domestic or wild animals, often resembling smaller versions of human domiciles. Familiar animal houses built by humans include bird-houses, hen-houses chicken-coops and doghouses (kennels); while housed agricultural animals more often live in barns and stables. However, human interest in building houses for animals does not stop at the domestic pet. People build bat-houses, nesting-sites for wild ducks and other birds, bee houses, giraffe houses, kangaroo houses, worm houses, hermit crab houses, as well as shelters for many other animals. Shelter. Forms of (relatively) simple shelter may include: Houses and symbolism. Houses may express the circumstances or opinions of their builders or their inhabitants. Thus a vast and elaborate house may serve as a sign of conspicuous wealth, whereas a low-profile house built of recycled materials may indicate support of energy conservation. Houses of particular historical significance (former residences of the famous, for example, or even just very old houses) may gain a protected status in town planning as examples of built heritage and or of streetscape values. Plaques may mark such structures. House-ownership provides a common measure of prosperity in economics. Contrast the importance of house-destruction, tent dwelling and house rebuilding in the wake of many natural disasters. Peter Olshavsky's provides a 'pataphysical variation on the house. Heraldry. The house occurs as a rare charge in heraldry. |