Main article: Sunglasses Sunglasses may be made with either prescription or non-prescription (i.e. plano) lenses that are darkened to provide protection against bright visible light. Good sunglasses should also protect against ultraviolet light. Due to changes in the atmosphere, ultraviolet levels are much higher than in the past and ultraviolet protection for eyes and skin is even more important. It is possible to have lenses that look very dark and yet offer little ultraviolet protection. Sunglasses vary greatly and ...

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Glasses, Glasses - History, Glasses - Corrective glasses, Glasses - Safety glasses, Glasses - Sunglasses, Glasses - Special glasses, Glasses - Conditions glasses are used to correct, Glasses - Variation in glasses, Glasses - Glasses as a fashion accessory, Glasses - Other names for glasses

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Sunglasses - Lens. The color of the lens can vary by style, fashion, and purpose, but for general use, green, grey, or brown is recommended to avoid or minimize color distortion, that could be dangerous when, for instance, driving a car. Grey lenses are considered neutral because they do not enhance contrast or distort colors. Brown and green lenses cause some minimal color distortion, but have contrast-enhancing properties. Red lenses are good for medium and lower light conditions because they are good at enhanc ...

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Sunglasses, Sunglasses - Uses, Sunglasses - Comfort, Sunglasses - Protection, Sunglasses - Construction, Sunglasses - Lens, Sunglasses - Frames, Sunglasses - Fashion, Sunglasses - Onassis glasses, Sunglasses - Mirrorshades, Sunglasses - Aviators, Sunglasses - History, Sunglasses - Other names for sunglasses, Sunglasses - Some celebrities predominantly seen wearing sunglasses, Sunglasses - Some fictional characters predominantly seen wearing sunglasses

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Glasses, spectacles, or eyeglasses are frames bearing lenses worn in front of the human eyes, sometimes for purely aesthetic reasons but normally for vision correction or eye protection. Special glasses are used for viewing three-dimensional images or experiencing virtual reality. Modern glasses are typically supported by pads on the bridge of the nose and by temples placed over the ears. Historical types ...

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• Glasses - History
• Glasses - Corrective glasses
• Glasses - Safety glasses
• Glasses - Sunglasses
• Glasses - Special glasses
• Glasses - Conditions glasses are used to correct
• Glasses - Variation in glasses
• Glasses - Glasses as a fashion accessory
• Glasses - Other names for glasses

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Glasses were possibly invented in northern Italy, most likely in the late 1280s. The identity of the original inventor is unknown, although a possible source is the Arabs, who may have had magnifying lenses in the 10th century. In 1676, Franciscus Redi, a professor of medicine at the University of Pisa, wrote that he possessed a 1289 manuscript whose author complains that he would be unable to read or write were it not for the recent invention of glasses, and a record of a sermon given in 1305, in which the speaker, a Dominican monk named Fr ...

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Glasses, Glasses - History, Glasses - Corrective glasses, Glasses - Safety glasses, Glasses - Sunglasses, Glasses - Special glasses, Glasses - Conditions glasses are used to correct, Glasses - Variation in glasses, Glasses - Glasses as a fashion accessory, Glasses - Other names for glasses

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Oxy-fuel welding is a welding process commonly called oxyacetylene welding since acetylene is the predominant choice for a fuel, or often simply gas welding. A virtually identical procedure, with a different type of gas torch, a blowtorch, is used for cutting metal and called oxy-fuel cutting. In gas welding and cutting, the heat energy and high temperature needed to melt the metal is obtained by the combustion of a fuel gas with oxygen in a torch. Oxy-fuel welding and cutting - Fuels. Including:

• Oxy-fuel welding and cutting - Fuels
• Oxy-fuel welding and cutting - Apparatus
• Oxy-fuel welding and cutting - Setting up the equipment
• Oxy-fuel welding and cutting - The flame
• Oxy-fuel welding and cutting - Blowlamps

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2000s - Technology. A huge jump in broadband internet usage, from 6% of U.S. internet users in June, 2000 to what one study predicts will be 62% by 2010. Boom in music downloading and the use of data compression to quickly transfer music over the Internet, with a corresponding rise of portable digital audio players typified by Apple Computer's iPod. Digital cameras become very popular due to rapid decreases in size and cost while photo resolution steadily increases. Sales of film reel came ...

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2000s, 2000s - The decade as a whole, 2000s - Names of the decade, 2000s - Criticisms of the Decade, 2000s - Events and trends, 2000s - Technology, 2000s - Science, 2000s - War peace and politics, 2000s - Economics, 2000s - Culture and religion, 2000s - Other, 2000s - Trends and Fashion, 2000s - United States, 2000s - Music, 2000s - United States and Canada, 2000s - Europe, 2000s - Latin America/Caribbean, 2000s - Film, 2000s - Video Games, 2000s - Television and Radio, 2000s - Sports, 2000s - People, 2000s - World leaders, 2000s - Entertainers, 2000s - Sports figures

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This article is about the decade starting at the beginning of 2000 and ending at the end of 2009. For the century or millennium starting in 2001, see the links below. 2000s - The decade as a whole. The 2000s decade refers to the years from 2000 to 2009, inclusive. Informally, it can also include a few years at the end of the preceding decade or the beginning of the following decade. So far, the 2000s has been marked generally with an escalation of the social issues a ...

Including:

• 2000s - The decade as a whole
• 2000s - Names of the decade
• 2000s - Criticisms of the Decade
• 2000s - Events and trends
• 2000s - Technology
• 2000s - Science
• 2000s - War peace and politics
• 2000s - Economics
• 2000s - Culture and religion
• 2000s - Other
• 2000s - Trends and Fashion
• 2000s - United States
• 2000s - Music
• 2000s - United States and Canada
• 2000s - Europe
• 2000s - Latin America/Caribbean
• 2000s - Film
• 2000s - Video Games
• 2000s - Television and Radio
• 2000s - Sports
• 2000s - People
• 2000s - World leaders
• 2000s - Entertainers
• 2000s - Sports figures

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Glasses are often regarded as unattractive, and many people prefer to wear contact lenses for that reason. Contact lenses also provide much improved peripheral vision. On the other hand, many people are attracted to people who wear glasses, and glasses are available in a wide range of styles, materials, and even designer labels. Glasses can be a major part of personal expression, from the extravagance of Elton John and Dame Edna Everage, from Groucho Marx to John Denver to Lisa Loeb all the way to the varied pr ...

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Glasses, Glasses - History, Glasses - Corrective glasses, Glasses - Safety glasses, Glasses - Sunglasses, Glasses - Special glasses, Glasses - Conditions glasses are used to correct, Glasses - Variation in glasses, Glasses - Glasses as a fashion accessory, Glasses - Other names for glasses

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Glasses can be very simple. Magnifying lenses for reading that are used to treat mild hypermetropia and presbyopia can be bought off the shelf, but most glasses are made to a particular prescription, based on degree of myopia or hypermetropia combined with astigmatism. Lenses can be ground to specific eyes, but in most cases standard off-the-shelf prescriptions suffice, but require custom-fitting to particular frames. As people age, their ability to focus is lessened and many decide to use multiple-focus lenses, bifocal or even trifoc ...

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Glasses, Glasses - History, Glasses - Corrective glasses, Glasses - Safety glasses, Glasses - Sunglasses, Glasses - Special glasses, Glasses - Conditions glasses are used to correct, Glasses - Variation in glasses, Glasses - Glasses as a fashion accessory, Glasses - Other names for glasses

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The illusion of three dimensions on a two dimensional surface can be created by providing each eye with different visual information. Classic 3D glasses create the illusion of three dimensions when viewing specially prepared images. The classic 3D glasses have one red lens and one blue lens. 3D glasses made of cardboard and plastic are distributed at 3D movies. Another kind of 3D glasses uses polarized filters. One kind of electronic 3D spectacles uses electronic shutters. Virtual reality glasses and helmets have separate video screens for each eye and a method for de ...

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Glasses, Glasses - History, Glasses - Corrective glasses, Glasses - Safety glasses, Glasses - Sunglasses, Glasses - Special glasses, Glasses - Conditions glasses are used to correct, Glasses - Variation in glasses, Glasses - Glasses as a fashion accessory, Glasses - Other names for glasses

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Safety glasses are usually made with shatter-resistant plastic lenses to protect the eye from flying debris. Although safety lenses may be constructed from a variety of materials that vary in impact resistance, certain standards suggest that they maintain a minimum 1mm thickness at the thinest point regardless of material. Safety glasses can vary in the level of protection they provide. For example, those used in medicine may be expected to protect against blood splatter while safety glasses in a factory might have stronger lenses and a stro ...

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Glasses, Glasses - History, Glasses - Corrective glasses, Glasses - Safety glasses, Glasses - Sunglasses, Glasses - Special glasses, Glasses - Conditions glasses are used to correct, Glasses - Variation in glasses, Glasses - Glasses as a fashion accessory, Glasses - Other names for glasses

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The most commonly used fuel gas is acetylene. Other gases used are propylene, liquified petroleum gas (LPG), natural gas, hydrogen, and MAPP gas. Most, perhaps all, of these fuels are also burned with atmospheric oxygen. Torches that do not combine pure oxygen with the fuel while still in the torch, do not count as oxy-fuel torches. These torches can be identified by their single tank. (Oxy-fuel welding requires two tanks, fuel and oxygen.) In addition, most metals cannot be melted with such single-tank torches, so they ca ...

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Oxy-fuel welding and cutting, Oxy-fuel welding and cutting - Fuels, Oxy-fuel welding and cutting - Apparatus, Oxy-fuel welding and cutting - Setting up the equipment, Oxy-fuel welding and cutting - The flame

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2000s - Technology. A huge jump in broadband internet usage, from 6% of U.S. internet users in June, 2000 to what one study predicts will be 62% by 2010. Boom in music downloading and the use of data compression to quickly transfer music over the Internet, with a corresponding rise of portable digital audio players typified by Apple Computer's iPod. Digital cameras become very popular due to rapid decreases in size and cost while photo resolution steadily increases. Sales of film reel came ...

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2000s, 2000s - The decade as a whole, 2000s - Names of the decade, 2000s - Criticisms of the decade, 2000s - Events and trends, 2000s - Technology, 2000s - Science, 2000s - War peace and politics, 2000s - Economics, 2000s - Culture and religion, 2000s - Other, 2000s - Trends and Fashion, 2000s - United States, 2000s - Music, 2000s - United States and Canada, 2000s - Europe, 2000s - Latin America/Caribbean, 2000s - Film, 2000s - Internet, 2000s - Video Games, 2000s - Television and Radio, 2000s - Sports, 2000s - People, 2000s - World leaders, 2000s - Entertainers, 2000s - Sports figures

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After this preparation, set the regulators at the desired pressure. For acetylene, this should never be more than 103 kPa (15 lbs/in²). Open the fuel valve open less than one quarter of a turn, light with a flint striker. After the flame is adjusted to the proper size, open the oxygen valve and adjust it to give the desired balance of fuel and oxygen. Usually a neutral flame is used: this is a flame where the fuel and oxygen supplied to the torch tip are both completely combined with each other. An oxidizing flame has an excess of oxygen an ...

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Oxy-fuel welding and cutting, Oxy-fuel welding and cutting - Fuels, Oxy-fuel welding and cutting - Apparatus, Oxy-fuel welding and cutting - Setting up the equipment, Oxy-fuel welding and cutting - The flame, Oxy-fuel welding and cutting - Blowlamps

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2000s - United States. Fashion slowly becomes less grungy and more excessive as the wearing of flannel by people under 30 declines and acid-washed jeans and shaggy hair become again commonplace for boys and men. For girls and women hoop earrings, originally popular in the 1980s and early 1990s, return to style circa 2004. Wearing baseball caps backwards peacefully falls out of style, in favor of wearing them sideways or forwards. Sunglasses begin to become less widespread as a fashion statement, un ...

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2000s, 2000s - The decade as a whole, 2000s - Names of the decade, 2000s - Criticisms of the Decade, 2000s - Events and trends, 2000s - Technology, 2000s - Science, 2000s - War peace and politics, 2000s - Economics, 2000s - Culture and religion, 2000s - Other, 2000s - Trends and Fashion, 2000s - United States, 2000s - Music, 2000s - United States and Canada, 2000s - Europe, 2000s - Latin America/Caribbean, 2000s - Film, 2000s - Video Games, 2000s - Television and Radio, 2000s - Sports, 2000s - People, 2000s - World leaders, 2000s - Entertainers, 2000s - Sports figures

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The apparatus used in gas welding consists basically of a torch, two pressure regulators and twin flexible hoses. The torch is the part that the welder holds and manipulates to make the weld. It has two valves and two connections, one each for the fuel gas and the oxygen, a handle for the welder to grasp, a mixing chamber where the fuel gas and oxygen mix, and a tip where the flame issues from. The regulators are attached to the fuel and to the oxygen sources. The oxygen regulator is attached to the oxygen tank and drops the pr ...

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Oxy-fuel welding and cutting, Oxy-fuel welding and cutting - Fuels, Oxy-fuel welding and cutting - Apparatus, Oxy-fuel welding and cutting - Setting up the equipment, Oxy-fuel welding and cutting - The flame

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The 2000s are so far not a highly regarded decade by most people in the world as many find the 1990s to have been a much more prosperous time and look fondly upon earlier decades such as the 1960s and 1980s. While not a criticism per se as many people still love the 1990s, some others look down on the decade for upholding so many tired 1990s fads, fashions, and music genres. Quite interestly, many people who are fond of the 1990s dislike the 2000s because they perceive them as similar to the 1980s for various reasons, mostly relating to politics but also to the 1980s nostalgia wave tha ...

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2000s, 2000s - The decade as a whole, 2000s - Names of the decade, 2000s - Criticisms of the decade, 2000s - Events and trends, 2000s - Technology, 2000s - Science, 2000s - War peace and politics, 2000s - Economics, 2000s - Culture and religion, 2000s - Other, 2000s - Trends and Fashion, 2000s - United States, 2000s - Music, 2000s - United States and Canada, 2000s - Europe, 2000s - Latin America/Caribbean, 2000s - Film, 2000s - Internet, 2000s - Video Games, 2000s - Television and Radio, 2000s - Sports, 2000s - People, 2000s - World leaders, 2000s - Entertainers, 2000s - Sports figures

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In contrast to the decades from 1920 to 1999, which are called "The Twenties", "The Nineties", and the like; the '00s have had no generally-accepted name. The term "The Two Thousands" is fairly common, but many still find its use awkward and incorrect for a number of reasons, notably the fact that formally, the "Two Thousands" will last for a thousand years and not just the ten years of the "00" decade. It is occasionally termed, in historical contexts, the "turn of the millennium" or "turn of the century" (or "turn of the new ...

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2000s, 2000s - The decade as a whole, 2000s - Names of the decade, 2000s - Criticisms of the decade, 2000s - Events and trends, 2000s - Technology, 2000s - Science, 2000s - War peace and politics, 2000s - Economics, 2000s - Culture and religion, 2000s - Other, 2000s - Trends and Fashion, 2000s - United States, 2000s - Music, 2000s - United States and Canada, 2000s - Europe, 2000s - Latin America/Caribbean, 2000s - Film, 2000s - Internet, 2000s - Video Games, 2000s - Television and Radio, 2000s - Sports, 2000s - People, 2000s - World leaders, 2000s - Entertainers, 2000s - Sports figures

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2000s - United States. Fashion slowly becomes less grungy and more excessive as the wearing of flannel by people under 30 declines and acid-washed jeans and shaggy hair become again commonplace for boys and men. For girls and women hoop earrings, originally popular in the 1980s and early 1990s, return to style circa 2004. Wearing baseball caps backwards peacefully falls out of style, in favor of wearing them sideways or forwards. Sunglasses begin to become less widespread as a fashion statement, un ...

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2000s, 2000s - The decade as a whole, 2000s - Names of the decade, 2000s - Criticisms of the decade, 2000s - Events and trends, 2000s - Technology, 2000s - Science, 2000s - War peace and politics, 2000s - Economics, 2000s - Culture and religion, 2000s - Other, 2000s - Trends and Fashion, 2000s - United States, 2000s - Music, 2000s - United States and Canada, 2000s - Europe, 2000s - Latin America/Caribbean, 2000s - Film, 2000s - Internet, 2000s - Video Games, 2000s - Television and Radio, 2000s - Sports, 2000s - People, 2000s - World leaders, 2000s - Entertainers, 2000s - Sports figures

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When using fuel and oxygen tanks they should be fastened securely to a wall, a post or a portable cart in an upright position. An oxygen tank is especially dangerous for the reason that the oxygen is at a pressure of 21 MPa (3000 lbs/in² = 200 atmospheres) when full and if the tank falls over and the valve strikes something and is knocked off, the tank will become an unguided and unpredictable missile powered by the compressed oxygen. It is for this reason that an oxygen ...

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Oxy-fuel welding and cutting, Oxy-fuel welding and cutting - Fuels, Oxy-fuel welding and cutting - Apparatus, Oxy-fuel welding and cutting - Setting up the equipment, Oxy-fuel welding and cutting - The flame

Read more here: » Oxy-fuel welding and cutting: Encyclopedia II - Oxy-fuel welding and cutting - Setting up the equipment