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Goggle Watch
Goggles, or safety glasses, are forms of protective eyewear that usually enclose or protect the area surrounding the eye in order to prevent particulates, water or chemicals from striking the eyes. They are used in chemistry laboratories and in woodworking. They are often used in snow sports as well, and in swimming. Goggles are often worn when using power tools such as drills or chainsaws to prevent flying particles from damaging the eyes. Many types of goggles are available as prescription goggles for those with vision problems. History The Inuit and Yupik peoples carved snow goggles from the antlers of caribou, wood, and shell to help prevent snow blindness. The goggles were curved to fit the user's face and had a large groove cut in the back to allow for the nose. A long thin slit was cut through the goggles to allow in a small amount of light, diminishing subsequent ultraviolet rays. The goggles were held to the head by a cord made of caribou sinew. In the early 2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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In Modern English, ''you'' is the second-person pronoun. It is grammatically plural, and was historically used only for the dative case, but in most modern dialects is used for all cases and numbers. History ''You'' comes from the Proto-Germanic demonstrative base *''juz''-, *''iwwiz'' from PIE *''yu''- (second person plural pronoun). Old English had singular, dual, and plural second-person pronouns. The dual form was lost by the twelfth century, and the singular form was lost by the early 1600s. The development is shown in the following table. Early Modern English distinguished between the plural '' ye'' and the singular ''thou''. As in many other European languages, English at the time had a T–V distinction, which made the plural forms more respectful and deferential; they were used to address strangers and social superiors. This distinction ultimately led to familiar ''thou'' becoming obsolete in modern English, although it persists in some English dialects. ''Yo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tendon
A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability to withstand significant amounts of tension. Tendons are similar to ligaments; both are made of collagen. Ligaments connect one bone to another, while tendons connect muscle to bone. Structure Histologically, tendons consist of dense regular connective tissue. The main cellular component of tendons are specialized fibroblasts called tendon cells (tenocytes). Tenocytes synthesize the extracellular matrix of tendons, abundant in densely packed collagen fibers. The collagen fibers are parallel to each other and organized into tendon fascicles. Individual fascicles are bound by the endotendineum, which is a delicate loose connective tissue containing thin collagen fibrils and elastic fibres. Groups of fascicles are bounded by the epi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seawater
Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approximately of dissolved salts (predominantly sodium () and chloride () ions). The average density at the surface is 1.025 kg/L. Seawater is denser than both fresh water and pure water (density 1.0 kg/L at ) because the dissolved salts increase the mass by a larger proportion than the volume. The freezing point of seawater decreases as salt concentration increases. At typical salinity, it freezes at about . The coldest seawater still in the liquid state ever recorded was found in 2010, in a stream under an Antarctic glacier: the measured temperature was . Seawater pH is typically limited to a range between 7.5 and 8.4. However, there is no universally accepted reference pH-scale for seawater and the difference between measu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Swimming
Swimming is the self- propulsion of a person through water, or other liquid, usually for recreation, sport, exercise, or survival. Locomotion is achieved through coordinated movement of the limbs and the body to achieve hydrodynamic thrust that results in directional motion. Humans can hold their breath underwater and undertake rudimentary locomotive swimming within weeks of birth, as a survival response. Swimming is consistently among the top public recreational activities, and in some countries, swimming lessons are a compulsory part of the educational curriculum. As a formalized sport, swimming is featured in a range of local, national, and international competitions, including every modern Summer Olympics. Swimming involves repeated motions known as strokes in order to propel the body forward. While the front crawl, also known as freestyle, is widely regarded as the fastest out of four primary strokes, other strokes are practiced for special purposes, such as for trainin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anti-fog
Anti-fog agents, also known as anti-fogging agents and treatments, are chemicals that prevent the condensation of water in the form of small droplets on a surface which resemble fog. Anti-fog treatments were first developed by NASA during Project Gemini, and are now often used on transparent glass or plastic surfaces used in optical applications, such as the lenses and mirrors found in glasses, goggles, camera lenses, and binoculars. The treatments work by minimizing surface tension, resulting in a non-scattering film of water instead of single droplets. This works by altering the degree of wetting. Anti-fog treatments usually work either by application of a surfactant film, or by creating a hydrophilic surface. Development Anti-fog agents were initially developed by NASA during the Project Gemini, for use on helmet visors. During Gemini 9A, in June 1966, Astronaut Eugene A. Cernan tested NASA's first space suit, and discovered during the space walk that his helmet visor fogged ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Vapor
(99.9839 °C) , - , Boiling point , , - , specific gas constant , 461.5 J/( kg·K) , - , Heat of vaporization , 2.27 MJ/kg , - , Heat capacity , 1.864 kJ/(kg·K) Water vapor, water vapour or aqueous vapor is the gaseous phase of water. It is one state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice. Water vapor is transparent, like most constituents of the atmosphere. Under typical atmospheric conditions, water vapor is continuously generated by evaporation and removed by condensation. It is less dense than most of the other constituents of air and triggers convection currents that can lead to clouds. Being a component of Earth's hydrosphere and hydrologic cycle, it is particularly abundant in Earth's atmosphere, where it acts as a greenhouse gas and warming feedback, contributing more to total greenhouse effect than non-condensable gases such as carbon diox ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lens (optics)
A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), usually arranged along a common axis. Lenses are made from materials such as glass or plastic, and are ground and polished or molded to a desired shape. A lens can focus light to form an image, unlike a prism, which refracts light without focusing. Devices that similarly focus or disperse waves and radiation other than visible light are also called lenses, such as microwave lenses, electron lenses, acoustic lenses, or explosive lenses. Lenses are used in various imaging devices like telescopes, binoculars and cameras. They are also used as visual aids in glasses to correct defects of vision such as myopia and hypermetropia. History The word ''lens'' comes from '' lēns'', the Latin name of the lentil (a seed of a lent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wilmer Stultz
Wilmer Lower Stultz (April 11, 1900 – July 1, 1929) was an aviator who made the first non-stop flight between New York City and Havana, Cuba. He died in a crash in 1929. Biography He was born in Williamsburg, Pennsylvania, on April 11, 1900. Stultz joined the United States Army Air Force on 22 August 1917 and was assigned to the 634th Aero Supply Squadron, reaching the rank of Sergeant. He was discharged on 31 March 1919. Stultz then joined the United States Naval Air Service in December that year, training at Pensacola, Florida. He served at Hampton Roads, Virginia, testing the F5L flying boat. He married Mildred Botts of Middletown, Pennsylvania, on August 4, 1919. On March 5, 1928, Stultz, Oliver Colin LeBoutillier, and Mabel Boll on an improvised seat, made the first non-stop flight in the ''Columbia'' between New York City and Havana, Cuba (c. 1300 mi.). Stultz was the pilot of the Fokker Trimotor "Friendship" on June 18, 1928, when Amelia Earhart became the firs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polar Bear
The polar bear (''Ursus maritimus'') is a hypercarnivorous bear whose native range lies largely within the Arctic Circle, encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is the largest extant bear species, as well as the largest extant land carnivore. A boar (adult male) weighs around , while a sow (adult female) is about half that size. Although it is the sister species of the brown bear, it has evolved to occupy a narrower ecological niche, with many body characteristics adapted for cold temperatures, for moving across snow, ice and open water, and for hunting seals, which make up most of its diet. Although most polar bears are born on land, they spend most of their time on the sea ice. Their scientific name means "maritime bear" and derives from this fact. Polar bears hunt their preferred food of seals from the edge of sea ice, often living off fat reserves when no sea ice is present. Because of their dependence on the sea ice, pola ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Safety Helmet
A hard hat is a type of helmet predominantly used in workplace environments such as industrial or construction sites to protect the head from injury due to falling objects, impact with other objects, debris, rain, and electric shock. Suspension bands inside the helmet spread the helmet's weight and the force of any impact over the top of the head. A suspension also provides space of approximately 30 mm (1.2 inches) between the helmet's shell and the wearer's head, so that if an object strikes the shell, the impact is less likely to be transmitted directly to the skull. Some helmet shells have a mid-line reinforcement ridge to improve impact resistance. The rock climbing helmet fulfills a very similar role in a different context and has a very similar design. A bump cap is a lightweight hard hat using a simplified suspension or padding and a chin strap. Bump caps are used where there is a possibility of scraping or bumping one's head on equipment or structure projections ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blowtorch
A blowtorch, also referred to as a blowlamp, is an ambient air fuel-burning gas lamp used for applying flame and heat to various applications, usually metalworking. Early blowtorches used liquid fuel, carried in a refillable reservoir attached to the lamp. This is distinct from modern gas-fueled torches burning fuel such as a butane torch or a propane torch. Their fuel reservoir is disposable or refillable by exchange. Liquid-fueled torches are pressurized by a piston hand pump, while gas torches are self-pressurized by the fuel evaporation. The term 'blowtorch' is commonly misused as a name for any metalworking torch but properly describes the pressurized liquid fuel torches that predate the common use of pressurized fuel gas cylinders. Torches are available in a vast range of size and output power. The term blowtorch applies to the obsolescent style of smaller liquid fuel torches. Blowtorches are typically a single hand-held unit, with their draught supplied by a natural ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nenets People
The Nenets ( yrk, ненэй ненэче, ''nenəj nenəče'', russian: ненцы, ''nentsy''), also known as Samoyed, are a Samoyedic ethnic group native to northern Arctic Russia, Russian Far North. According to the latest census in 2010, there were 44,857 Nenets in the Russian Federation, most of them living in the Yamalo-Nenets Autonomous Okrug, Nenets Autonomous Okrug and Taymyrsky Dolgano-Nenetsky District stretching along the coastline of the Arctic Ocean near the Arctic Circle between Kola and Taymyr peninsulas. The Nenets people speak either the Tundra or Forest Nenets languages, which are mutually unintelligible. In the Russian Federation they have a status of indigenous small-numbered peoples. Today, the Nenets people face numerous challenges from the state and oil and gas companies that threaten the environment and their way of life. As a result, many cite a rise in locally based activism. Name The literal morphs ''samo'' and ''yed'' in Russian convey the mea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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