ratio of word probabilities predicted from brain for bed and refrigerator

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bed

refrigerator

top 10 words in brain distribution (in article):
people sexual woman build house world time refer form century
top 10 words in brain distribution (in article):
century time cut modern design metal type style allow hold
top 10 words in brain distribution (not in article):
city love god animal state store human female plant word
top 10 words in brain distribution (not in article):
wear church horse iron blade bishop head woman steel handle
times more probable under bed 30 20 10 6 4 2.5 1.25 1 1.25 2.5 4 6 10 20 30 times more probable under refrigerator
(words not in the model)
A bed'" is a piece of furniture (or a location) used as a place to sleep, and as a primary place for relaxation and sexual intercourse. To make beds more comfortable, mattresses are usually placed on top of them. The second layer is the box spring Inner-sprung Base. The box spring or "divan" is a large mattress-sized box containing wood and springs that provide additional support and suspension for the mattress. The box spring will typically lie on a bed frame(which lifts the mattress mattress-box spring off the ground) or on slats (usually made of 2" x 4" wood). A "headboard", "side rails", and "footboard" or "front rail" will complete the bed. "Headboard only" beds often incorporate a "dust ruffle", "bed skirt", or "valance sheet" to hide the bed frame. For greater head support, most people use a pillow, placed at the top of a mattress. Also used is some form of covering blanket to insulate the sleeper, often bed sheets, a quilt, or a duvet. Also, some people prefer to dispense with the box spring and bed frame, and replace it with a platform bed style. This is more common in Europe and Japan. The Ancient World. Early beds were little more than piles of straw or some other natural materials. An important change was raising them off the ground, to avoid draughts, dirt, and pests. The Egyptians had high bedsteads which were ascended by steps, with bolsters or pillows, and curtains to hang round. The elite of Egyptian society such as its pharaohs and queens even had beds made of wood and gilded with gold. Often there was a head-rest as well, semi-cylindrical and made of stone, wood or metal. Assyrians, Medes and Persians had beds of a similar kind, and frequently decorated their furniture with inlays or appliqués of metal, mother-of-pearl and ivory. The oldest account of a bed is probably that of Odysseus: a charpoy woven of rope, plays a role in the Odyssey. A similar bed can be seen at the St Fagans National History Museum in Wales. Odysseus also gives an account of how he crafted the nuptial bed for himself and Penelope, out of an ancient, huge olive tree trunk that used to grow on the spot before the bridal chamber was built. His detailed description finally persuades the doubting Penelope that the shipwrecked, aged man is indeed her long-lost husband. Homer also mentions the inlaying of the woodwork of beds with gold, silver and ivory.The Greek bed had a wooden frame, with a board at the head and bands of hide laced across, upon which skins were placed. At a later period the bedstead was often veneered with expensive woods; sometimes it was of solid ivory veneered with tortoise-shell and with silver feet; often it was of bronze. The pillows and coverings also became more costly and beautiful; the most celebrated places for their manufacture were Miletus, Corinth and Carthage. Folding beds, too, appear in the vase paintings. The Roman mattresses were stuffed with reeds, hay, wool or feathers; the last was used towards the end of the Republic, when custom demanded luxury. Small cushions were placed at the head and sometimes at the back. The bedsteads were high and could only be ascended by the help of steps. They were often arranged for two persons, and had a board or railing at the back as well as the raised portion at the head. The counterpanes were sometimes very costly, generally purple embroidered with figures in gold; and rich hangings fell to the ground masking the front. The bedsteads themselves were often of bronze inlaid with silver, and Elagabalus had one of solid silver. In the walls of some of the houses at Pompeii bed niches are found which were probably closed by curtains or sliding partitions. Ancient Romans had various kinds of beds for repose. These included: Medieval Europe. The ancient Germans lay on the floor on beds of leaves covered with skins, or in a kind of shallow chest filled with leaves and moss. In the early middle ages they laid carpets on the floor or on a bench against the wall, placed upon them mattresses stuffed with feathers, wool or hair, and used skins as a covering. They appear to have generally lain naked in bed, wrapping themselves in the large linen sheets which were stretched over the cushions. In the 13th century luxury increased, and bedsteads were made of wood much decorated with inlaid, carved and painted ornament. They also used folding beds, which served as couches by day and had cushions covered with silk laid upon leather. At night a linen sheet was spread and pillows placed, while silk-covered skins served as coverlets. Curtains were hung from the ceiling or from an iron arm projecting from the wall. The Carolingian manuscripts show metal bedsteads much higher at the head than at the feet, and this shape continued in use until the 13th century in France, many cushions being added to raise the body to a sloping position. In the 12th-century manuscripts the bedsteads appear much richer, with inlays, carving and painting, and with embroidered coverlets and mattresses in harmony. Curtains were hung above the bed, and a small hanging lamp is often shown. In the 14th century the woodwork became of less importance, being generally entirely covered by hangings of rich materials. Silk, velvet and even cloth of gold were much used. Inventories from the beginning of the 14th century give details of these hangings lined with fur and richly embroidered. Then it was that the tester bed made its first appearance, the tester being slung from the ceiling or fastened to the walls, a form which developed later into a room within a room, shut in by double curtains, sometimes even so as to exclude all drafts. The space between bed and wall was called the "ruelle", and very intimate friends were received there. In the 15th century beds became very large, reaching to 7 or 8 feet by 6 or 7 feet. The mattresses were often filled with pea-shucks, straw or feathers. At this time great personages were in the habit of carrying most of their property about with them, including beds and bed-hangings, and for this reason the bedsteads were for the most part mere frameworks to be covered up; but about the beginning of the 16th century bedsteads were made lighter and more decorative, since the lords remained in the same place for longer periods. Renaissance and Modern Europe. In the 17th century, which has been called "the century of magnificent beds," the style "a la duchesse", with tester and curtains only at the head, replaced the more enclosed beds in France, though they lasted much longer in England. Louis XIV had an enormous number of sumptuous beds, as many as 413 being described in the inventories of his palaces. Some of them had embroideries enriched with pearls, and figures on a silver or golden ground. The great bed at Versailles had crimson velvet curtains on which "The Triumph of Venus" was embroidered. So much gold was used that the velvet scarcely showed. In the 18th century feather pillows were first used as coverings in Germany, which in the fashions of the bed and the curious etiquette connected with the bedchamber followed France for the most part. The beds were "a la duchesse", but in France itself there was great variety both of name and shape. The custom of the "bed of justice" upon which the king of France reclined when he was present in parliament, the princes being seated, the great officials standing, and the lesser officials kneeling, was held to denote the royal power even more than the throne. Louis XI is credited with its first use, and the custom lasted till the end of the monarchy. In the "chambre de parade", where the ceremonial bed was placed, certain persons, such as ambassadors or great lords, whom it was desired to honour, were received in a more intimate fashion than the crowd of courtiers. At Versailles women received their friends in their beds, both before and after childbirth, during periods of mourning, and even directly after marriage; in fact in any circumstances which were thought deserving of congratulation or condolence. During the 17th century this curious custom became general, perhaps to avoid the tiresome details of etiquette. Portable beds were used in high society in France till the end of the "ancien regime". The earliest of which mention has been found belonged to Charles the Bold. They had curtains over a light framework, and were in their way as fine as the stationary beds. Iron beds appear in the 18th century; the advertisements recommend them as free from the insects which sometimes infested wooden bedsteads. Elsewhere, there was also the closed bed with sliding or folding shutters, and in England, where beds were commonly quite simple in form, the four poster was the usual citizen's bed until the middle of the 19th century. Bed sizes. Beds come in a wide array of shapes and sizes. Most countries have a standard set of four sizes of mattresses. While the "Double" size appears to be standard among English speaking countries, based on the imperial measurement of 4 ft 6 in by 6 ft 3 in, the sizes for other bed types tend to vary. The European sizes differ; they are based on the metric system. A king-sized bed differs from the other sizes in implementation, as it is not common to have a king-sized box spring; rather, two smaller box-springs are used under a king-sized mattress. It is a common misconception that on a U.S. "Standard" or "Eastern King", the box springs are identical in size to a "Twin Extra-Long," however "Twin Extra-Long" mattresses next to each other add up to 78 inches wide instead of the 76 inch width that is standard for an "Eastern King." Standard sizes. Modern manufacturing conventions have resulted in a limited number of standard sizes of commercial bedding for mattresses and box springs. They vary by country of origin. The sizes in the UK and Ireland, other than the "Double", vary compared to the U.S. sizes, being generally smaller. The U.S. "Queen" corresponds to UK "King" and "King" to "Super King". The European or continental basic sizes are similar to the UK but have a set length of 2 metres. The denominations Queen, King and Super King are not used in continental Europe, and "Double" refers to 140cm or any higher width. Instead of these US UK denominations, the bed width is given in centimetres. These dimensions are for the mattress—the actual bed frame will be a little bigger in order to fully encompass and support the mattress. The thickness of the mattress may vary considerably. Other European sizes. Modern continental Europe practice is to refer to a bed by explicit width or size ("80 cm bed" or "80x200 cm bed"). Other sizes found include: In France, Spain and Mexico, the length of older beds is sometimes 1.9 metres instead of 2 metres. Most mattress sizes in the Netherlands are also available in extra long, meaning 2.2 m instead of 2.0 m. In the Scandinavian countries, standards vary from one country to another. In Norway, these sizes are used: Small single: 0.75 x 2m (30 x 79 inches) Single: 0.90 x 2m (35.5 x 79 inches) Large Single: 1.2m x 2m (47 x 79 inches) Queen: 1.50 x 2m (60 x 79 inches, equal to two small single mattresses) King: 1.80 x 2m (71 x 79 inches, equal to two single mattresses) Beds mattresses are often available also in "extra long" (2.2m or 86.6 inches length). Some older beds are only 1.9m (75 inches) long, while antique beds often are even shorter (since they in older times often slept in a reclined position rather than the close to supine position which is common today). Other New Zealand sizes. The following bed sizes are available in New Zealand: Types of beds. There are many varieties of beds: Bed frames. Bed frames, also called bed steads, are made of wood or metal. The frame is made up of head, foot, and side rails. For heavy duty or larger frames (such as for queen- and king-sized beds), the bed frame also includes a center support rail. These rails are assembled to create a box for the mattress or mattress box spring to sit on. Though not truly parts of a bed frame, many people include headboards, footboards, and bed rails in their definition of bed frames. Headboards and footboards can be wood or metal. They can be stained, painted, or covered in fabric or leather. Bed rails are made of wood or metal and are attached to a headboard and footboard. Wooden slats are placed perpendicular to the bed rails to support the mattress mattress box spring. Bed rails and frames are often attached to the bed post using knock-down fittings. A knock-down fitting enables the bed to be easily dismantled for removal. Primary knock-down fittings for bed rails are as follows: Safety rails can be added to the sides of a bed (normally a children's bed) to stop anyone falling out of the sides of the bed. A safety rail is normally a piece of wood that attaches to the side rails on one or both sides of the bed. They are made so that they can be easily removed when no longer required. A refrigerator'" (often called a "'fridge'" for short) is a cooling appliance comprising a thermally insulated compartment and a heat pump: a mechanism to transfer heat from it to the external environment, cooling the contents to a temperature below ambient. Refrigerators are extensively used to store foods which deteriorate at ambient temperatures; spoilage from bacterial growth and other processes is much slower at low temperatures. A device described as a "refrigerator" maintains a temperature a few degrees above the freezing point of water; a similar device which maintains a temperature below the freezing point of water is called a "'freezer'". The refrigerator is a relatively modern invention among kitchen appliances. It replaced the icebox, which had been a common household appliance for almost a century and a half prior. For this reason, a refrigerator is sometimes referred to as an "icebox". Freezers keep their contents frozen. They are used both in households and for commercial use. Most freezers operate around minus 18 °C (0 °F). Domestic freezers can be included as a compartment in a refrigerator, sharing the same mechanism or with a separate mechanism, or can be standalone units. Domestic freezers are generally upright units, resembling refrigerators, or chests, resembling upright units laid on their backs. Many modern freezers come with an icemaker. Commercial fridge and freezer units, which go by many other names, were in use for almost 40 years prior to the common home models. They used toxic ammonia gas systems, making them unsafe for home use. Practical household refrigerators were introduced in 1915 and gained wider acceptance in the United States in the 1930s as prices fell and non-toxic, non-flammable synthetic refrigerants such as Freon or R-12 were introduced. It is notable that while 60% of households in the US owned a refrigerator by the 1930s, it was not until 40 years later, in the 1970s, that the refrigerator achieved a similar level of penetration in the United Kingdom. History. Before the invention of the refrigerator, icehouses were used to provide cool storage for most of the year. Placed near freshwater lakes or packed with snow and ice during the winter, they were once very common. Using the environment to cool foodstuffs is still common today. On mountainsides, runoff from melting snow higher up is a convenient way to cool drinks, and during the winter months simply placing milk outside is sufficient to greatly extend its useful life. In the 11th century, the Persian physicist and chemist, Ibn Sina (Avicenna), invented the refrigerated coil, which condenses aromatic vapours. This was a breakthrough in distillation technology and he made use of it in his steam distillation process, which requires refrigerated tubing, to produce essential oils. The first known artificial refrigeration was demonstrated by William Cullen at the University of Glasgow in 1748. Between 1805, when Oliver Evans designed the first refrigeration machine that used vapor instead of liquid, and 1902 when Willis Haviland Carrier demonstrated the first air conditioner, scores of inventors contributed many small advances in cooling machinery. In 1850 or 1851, Dr. John Gorrie demonstrated an ice maker. In 1857, Australian James Harrison introduced vapor-compression refrigeration to the brewing and meat packing industries. Ferdinand Carré of France developed a somewhat more complex system in 1859. Unlike earlier compression-compression machines, which used air as a coolant, Carré's equipment contained rapidly expanding ammonia. The absorption refrigerator was invented by Baltzar von Platen and Carl Munters in 1922, while they were still students at the Royal Institute of Technology in Stockholm, Sweden. It became a worldwide success and was commercialized by Electrolux. Other pioneers included Charles Tellier, David Boyle, and Raoul Pictet. At the start of the 20th Century, about half of households in the United States relied on melting ice (in an icebox) to keep food cold, while the remaining half had no cooled storage at all. The ice used for household storage was expensive because ice had to be cut from winter ponds (or mechanically produced), stored centrally until needed, and delivered regularly. In a few exceptional cases, mechanical refrigeration systems had been adapted by the start of the 20th century for use in the homes of the very wealthy, and might be used for cooling both living and food storage areas. One early system was installed at the mansion of Walter Pierce, an oil company executive. Marcel Audiffren of France championed the idea of a refrigerating machine for cooling and preserving foods at home. His U.S. patents, issued in 1895 and 1908, were purchased by the American Audiffren Refrigerating Machine Company. Machines based on Audiffren's sulfur dioxide process were manufactured by General Electric in Fort Wayne, Indiana and marketed by the Johns-Manville company. The first unit was sold in 1911. Audiffren machines were expensive, selling for about $1,000 about twice as much as the cost of an automobile at that time. General Electric sought to develop refrigerators of its own, and in 1915 the first "Guardian" unit was assembled in a back yard wash house as a predecessor to the Frigidaire. In 1916 Kelvinator and Servel introduced two units among a field of competing models. This number increased to 200 by 1920. In 1918, Kelvinator had a model with automatic controls. These home units usually required the installation of the mechanical parts, motor and compressor, in the basement or an adjacent room while the cold box was located in the kitchen. There was a 1922 model that consisted of a wooden cold box, water-cooled compressor, an ice cube tray and a 9 cubic foot compartment for $714. (A 1922 Model-T Ford cost about $450.) In 1923 Frigidaire introduced the first self-contained unit. About this same time porcelain covered metal cabinets began to appear. Ice cube trays were introduced more and more during the 1920s; up to this time freezing was not a function of the modern refrigerator. The first refrigerator to see widespread use was the General Electric "Monitor-Top" refrigerator introduced in 1927. The compressor assembly, which emitted a substantial amount of heat, was placed above the cabinet, and surrounded with a decorative ring. Over 1,000,000 units were produced. As the refrigerating medium, these refrigerators used either sulfur dioxide, which is corrosive to the eyes and may cause loss of vision, painful skin burns and lesions, or methyl formate, which is highly flammable, harmful to the eyes, and toxic if inhaled or ingested. Many of these units are still functional today. These cooling systems cannot be recharged with the hazardous original refrigerants if they leak or break down. The introduction of freon expanded the refrigerator market during the 1930s, and freezer units became more common during the 1940s. Home units did not go into mass production until after WWII. The 1950s and 1960s saw technical advances like automatic defrosting and automatic ice making. Developments of the 1970s and 80s brought about more efficient refrigerators, and environmental issues banned the use of CFC (freon) refrigerants used in sealed systems. Early refrigerator models (1916 and on) featured a cold compartment for ice cube trays. Successful processing of fresh vegetables through freezing began in the late 1920s by the Postum Company (the forerunner of General Foods) which had acquired the technology when it bought the rights to Clarence Birdseye's successful fresh freezing methods. The first successful example of the benefits of frozen foods occurred when General Foods heiress Marjorie Merriweather Post (then wife of Joseph E. Davies, United States Ambassador to the Soviet Union) deployed commercial-grade freezers to Spaso House, the US Embassy in Moscow in advance of the Davies’ arrival. Post, fearful of the food processing safety observed in the USSR, then fully stocked the freezers with products from General Foods' Birdseye unit. The frozen food stores allowed the Davies to lavishly entertain and serve fresh frozen foods that would otherwise be out of season. Upon returning from Moscow, Post (who resumed her maiden name after divorcing Davies) directed General Foods to market frozen product to upscale restaurants. Introduction of home freezer units occurred in the United States in 1940, and frozen foods began to make the transition from luxury to necessity. Design. Refrigerators work by the use of heat pumps operating in a refrigeration cycle. An industrial refrigerator is simply a refrigerator used in an industrial setting, usually in a restaurant or supermarket. It may consist of either a cooling compartment only (a larger refrigerator) or a freezing compartment only (a freezer) or both. The industry sometimes refers to such units as a “cold box” or a “walk-in.” The dual compartment was introduced commercially by General Electric in 1939. The vapor compression cycle is used in most household refrigerators. In this cycle, a circulating refrigerant such as R134a enters the compressor as a low-pressure vapor at its boiling point. The vapor is compressed and exits the compressor as a superheated high-pressure vapor. The superheated vapor travels through part of the condenser which removes the superheat by cooling the vapor. The vapor travels through the remainder of the condenser and is condensed into a liquid at its boiling point. Before the refrigerant leaves the condenser it will have been subcooled (i.e. below its boiling point). The subcooled liquid refrigerant passes through the metering (or throttling) device where its pressure abruptly decreases. The decrease in pressure results in the flash evaporation and auto-refrigeration of a portion of the liquid (typically, less than half of the liquid flashes). The cold and partially vaporized refrigerant travels through the coil or tubes in the evaporator. There, a fan circulates room air across the coil or tubes, and the refrigerant is totally vaporized, extracting heat from the air which is then returned to the food compartment. The refrigerant vapor, now slightly superheated, returns to the compressor inlet to continue the thermodynamic cycle. An absorption refrigerator works differently from a compressor refrigerator, using a source of heat, such as combustion of liquefied petroleum gas, or solar thermal energy. These heat sources are much quieter than the compressor motor in a typical refrigerator. The Peltier effect uses electricity directly to pump heat; refrigerators using this effect are sometimes used for camping, or where noise is not acceptable. They are totally silent, but less energy-efficient than other methods. Other uses of an absorption refrigerator (or "chiller") would include large systems used in office buildings or complexes such as hospitals and universities. These large systems are used to chill a brine solution that is circulated through the building. Other alternatives to the vapor-compression cycle but not in current use include thermionic, vortex tube, air cycle, magnetic cooling, Stirling cycle, Malone refrigeration, acoustic cooling, pulse tube and water cycle systems. Features. Early freezer units accumulated ice crystals around the freezing units. This was a result of humidity introduced into the units when the doors to the freezer were opened. This frost buildup required periodic thawing ("defrosting") of the units to maintain their efficiency. Advances in automatic defrosting eliminating the thawing task were introduced in the 1950s. Also, early units featured freezer compartments located within the larger refrigerator, and accessed by opening the refrigerator door, and then the smaller internal freezer door; units featuring entirely separate freezer compartment were introduced in the early 1960s, becoming the industry standard by the middle of that decade. Later advances included automatic ice units and self compartmentalized freezing units. An increasingly important environmental concern is the disposal of old refrigerators- initially because of the freon coolant damaging the ozone layer, but as the older generation of refrigerators disappears it is the destruction of CFC-bearing insulation which causes concern. Modern refrigerators usually use a refrigerant called HFC-134a (1,2,2,2-tetrafluoroethane), which has no ozone layer depleting properties, in place of freon. Disposal of discarded refrigerators is regulated, often mandating the removal of doors: children playing hide-and-seek have been asphyxiated while hiding inside a discarded refrigerator. This was particularly true for the older models that had latching doors. More modern units use a magnetic door gasket to hold the door sealed but can be pushed open from the inside. This gasket was invented by a man named Herman C. Ells Sr. Who didn't want children to lose their lives. He never gained recognition for his work, being a humble man only wanting to save lives. However, children can be unwittingly harmed by hiding inside any discarded refrigerator. Types of domestic refrigerators. Domestic refrigerators and freezers for food storage are made in a range of sizes. Among the smallest is a 4 L Peltier fridge advertised as being able to hold 6 cans of beer. A large domestic fridge stands as tall as a person and may be about 1 m wide with a capacity of 600 L. Some models for small households fit under kitchen work surfaces, usually about 86 cm high. Fridges may be combined with freezers, either stacked with fridge or freezer above, below, or side by side. A fridge without a true freezer may have a small compartment to make ice. Freezers may have drawers to store food in, or they may have no divisions (chest freezers). Fridges and freezers may be free-standing, or built into a kitchen. Refrigeration units for commercial and industrial applications can be made any size, shape or style to fit customer needs. Energy efficiency. An auto-defrost unit uses a blower fan to keep moisture out of the unit. It also has a heating coil beneath the evaporator that periodically heats the freezer compartment and melts any ice buildup. Some units also have heaters in the side of the door to keep the unit from "weeping." Manual defrost units are available in used-appliance shops or by special order. Refrigerators used to consume more energy than any other home appliance, but in the last twenty years great strides have been made to make refrigerators more energy efficient. In the early 1990s a competition was held among the major manufacturers to encourage energy efficiency. Current models that are Energy Star qualified use 50 percent less energy than models made before 1993. The most energy-efficient unit made in the US is designed to run on 12 or 110 volts, and consumes about half a kilowatt-hour per day. But even ordinary units are quite efficient; some smaller units use little more than one kilowatt-hour per day. Larger units, especially those with large freezers and icemakers, may use as much as 4 kWh per day. Among the different styles of refrigerators, top-freezer models are more efficient than bottom-freezer models of the same capacity, which are in turn more efficient than side-freezer models. Models with through-the-door ice units are less efficient than those without. Dr. Tom Chalko in Australia has developed an external thermostat to convert any chest freezer into a chest fridge using only about 0.1kWh per day--the amount of energy used by a 100 watt light bulb in one hour. Scientists at Oxford University have reconstructed a refrigerator invented in 1930 by Albert Einstein in their efforts to replace current technologies with energy efficient green technology. The Einstein refrigerator operates without electricity and uses no moving parts or greenhouse gases. Impact on lifestyle. The invention of the refrigerator has allowed the modern family to purchase, store, freeze, prepare and preserve food products in a fresh state for much longer periods of time than was previously possible. For the majority of families without a sizeable garden in which to grow vegetables and raise animals, the advent of the refrigerator along with the modern supermarket led to a vastly more varied diet and improved health resulting from improved nutrition. Dairy products, meats, fish, poultry and vegetables can be kept refrigerated in the same space within the kitchen (although raw meat should be kept separate from other foodstuffs for reasons of hygiene). The refrigerator allows families to consume more salads, fresh fruits and vegetables during meals without having to own a garden or an orchard. Exotic foodstuffs from far-off countries that have been imported by means of refrigeration can be enjoyed in the home because of the availability of domestic refrigeration. The luxury of freezing allows households to purchase more foods in bulk that can be eaten at leisure while the bulk purchase provides cost savings (see economies of scale). Ice cream, a popular commodity of the 20th century, was previously only available by traveling long distances to where the product was made fresh and had to be eaten on the spot. Now it is a common food item. Ice on-demand not only adds to the enjoyment of cold drinks, but is useful in first-aid applications, not to mention cold packs that can be kept frozen for picnics or in case of emergency. Temperature zones and ratings. Some refrigerators are now divided into four zones to store different types of food: The capacity of a refrigerator is measured in either litres or cubic feet (US). Typically the volume of a combined fridge-freezer is split to 100 litres (3.53 cubic feet) for the freezer and 140 litres (4.94 cubic feet) for the refrigerator, although these values are highly variable. Temperature settings for refrigerator and freezer compartments are often given arbitrary numbers (for example, 1 through 9, warmest to coldest) by manufacturers, but generally 2 to 8 °C (36 to 46 °F) is ideal for the refrigerator compartment and -18 °C (0 °F) for the freezer. Some refrigerators require a certain external temperature (60 °F) to run properly. This can be an issue when placing a refrigerator in an unfinished area such as a garage. European freezers, and refrigerators with a freezer compartment, have a four star rating system to grade freezers. Although both the three and four star ratings specify the same minimum temperature of -18°C, only a four star freezer is intended to be used for freezing fresh food. Three (or fewer) stars are used for frozen food compartments which are only suitable for storing frozen food; introducing fresh food into such a compartment is likely to result in unacceptable temperature rises.