1.
Square kilometre
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Square kilometre or square kilometer, symbol km2, is a multiple of the square metre, the SI unit of area or surface area. For example,3 km2 is equal to 3×2 =3,000,000 m2, topographical map grids are worked out in metres, with the grid lines being 1,000 metres apart. 1,100,000 maps are divided into squares representing 1 km2, each square on the map being one square centimetre in area, for 1,50,000 maps, the grid lines are 2 cm apart. Each square on the map is 2 cm by 2 cm, for 1,25,000 maps, the grid lines are 4 cm apart. Each square on the map is 4 cm by 4 cm, in each case, the grid lines enclose one square kilometre. The area enclosed by the walls of many European medieval cities were about one square kilometre, the approximate area of the old walled cities can often be worked out by fitting the course of the wall to a rectangle or an oval. Examples include Delft, Netherlands 52°0′54″N 4°21′34″E The walled city of Delft was approximately rectangular, the approximate length of rectangle was about 1.30 kilometres. The approximate width of the rectangle was about 0.75 kilometres, a perfect rectangle with these measurements has an area of 1. 30×0.75 =0.9 km2 Lucca 43°50′38″N 10°30′2″E The medieval city is roughly rectangular with rounded north-east and north-west corners. The maximum distance from east to west is 1.36 kilometres, the maximum distance from north to south is 0.80 kilometres. A perfect rectangle of these dimensions would be 1. 36×0.80 =1.088 km2, Brugge 51°12′39″N 3°13′28″E The medieval city of Brugge, a major centre in Flanders, was roughly oval or elliptical in shape with the longer or semi-major axis running north and south. The maximum distance from north to south is 2.53 kilometres, the maximum distance from east to west is 1.81 kilometres. A perfect ellipse of these dimensions would be 2.53 ×1.81 × =3.597 km2. Chester United Kingdom 53°12′1″N 2°52′45″W Chester is one of the smaller English cities that has a city wall. The distance from Northgate to Watergate is about 855 metres. The distance from Eastgate to Westgate is about 589 metres, a perfect rectangle of these dimensions would be × =0.504 km2. Parks come in all sizes, a few are almost exactly one kilometre in area. Here are some examples, Riverside Country Park, UK. Brierley Forest Park, rio de Los Angeles State Park, California, USA Jones County Central Park, Iowa, USA. Using the figures published by golf course architects Crafter and Mogford, assuming a 6,000 metres 18-hole course, an area of 80 hectares needs to be allocated for the course itself
2.
Hectare
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The hectare is an SI accepted metric system unit of area equal to 100 ares and primarily used in the measurement of land as a metric replacement for the imperial acre. An acre is about 0.405 hectare and one hectare contains about 2.47 acres, in 1795, when the metric system was introduced, the are was defined as 100 square metres and the hectare was thus 100 ares or 1⁄100 km2. When the metric system was further rationalised in 1960, resulting in the International System of Units, the are was not included as a recognised unit. The hectare, however, remains as a non-SI unit accepted for use with the SI units, the metric system of measurement was first given a legal basis in 1795 by the French Revolutionary government. At the first meeting of the CGPM in 1889 when a new standard metre, manufactured by Johnson Matthey & Co of London was adopted, in 1960, when the metric system was updated as the International System of Units, the are did not receive international recognition. The units that were catalogued replicated the recommendations of the CGPM, many farmers, especially older ones, still use the acre for everyday calculations, and convert to hectares only for official paperwork. Farm fields can have long histories which are resistant to change, with names such as the six acre field stretching back hundreds of years. The names centiare, deciare, decare and hectare are derived by adding the standard metric prefixes to the base unit of area. The centiare is a synonym for one square metre, the deciare is ten square metres. The are is a unit of area, equal to 100 square metres and it was defined by older forms of the metric system, but is now outside of the modern International System of Units. It is commonly used to measure real estate, in particular in Indonesia, India, and in French-, Portuguese-, Slovakian-, Serbian-, Czech-, Polish-, Dutch-, in Russia and other former Soviet Union states, the are is called sotka. It is used to describe the size of suburban dacha or allotment garden plots or small city parks where the hectare would be too large, the decare is derived from deka, the prefix for 10 and are, and is equal to 10 ares or 1000 square metres. It is used in Norway and in the former Ottoman areas of the Middle East, the hectare, although not strictly a unit of SI, is the only named unit of area that is accepted for use within the SI. The United Kingdom, United States, Burma, and to some extent Canada instead use the acre, others, such as South Africa, published conversion factors which were to be used particularly when preparing consolidation diagrams by compilation. In many countries, metrication redefined or clarified existing measures in terms of metric units, non-SI units accepted for use with the International System of Units
3.
Area
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Area is the quantity that expresses the extent of a two-dimensional figure or shape, or planar lamina, in the plane. Surface area is its analog on the surface of a three-dimensional object. It is the analog of the length of a curve or the volume of a solid. The area of a shape can be measured by comparing the shape to squares of a fixed size, in the International System of Units, the standard unit of area is the square metre, which is the area of a square whose sides are one metre long. A shape with an area of three square metres would have the area as three such squares. In mathematics, the square is defined to have area one. There are several formulas for the areas of simple shapes such as triangles, rectangles. Using these formulas, the area of any polygon can be found by dividing the polygon into triangles, for shapes with curved boundary, calculus is usually required to compute the area. Indeed, the problem of determining the area of plane figures was a motivation for the historical development of calculus. For a solid such as a sphere, cone, or cylinder. Formulas for the areas of simple shapes were computed by the ancient Greeks. Area plays an important role in modern mathematics, in addition to its obvious importance in geometry and calculus, area is related to the definition of determinants in linear algebra, and is a basic property of surfaces in differential geometry. In analysis, the area of a subset of the plane is defined using Lebesgue measure, in general, area in higher mathematics is seen as a special case of volume for two-dimensional regions. Area can be defined through the use of axioms, defining it as a function of a collection of certain plane figures to the set of real numbers and it can be proved that such a function exists. An approach to defining what is meant by area is through axioms, area can be defined as a function from a collection M of special kind of plane figures to the set of real numbers which satisfies the following properties, For all S in M, a ≥0. If S and T are in M then so are S ∪ T and S ∩ T, if S and T are in M with S ⊆ T then T − S is in M and a = a − a. If a set S is in M and S is congruent to T then T is also in M, every rectangle R is in M. If the rectangle has length h and breadth k then a = hk, let Q be a set enclosed between two step regions S and T
4.
Orders of magnitude (length)
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The following are examples of orders of magnitude for different lengths. To help compare different orders of magnitude, the following list describes various lengths between 1. 6×10−35 meters and 101010122 meters,100 pm –1 Ångström 120 pm – radius of a gold atom 150 pm – Length of a typical covalent bond. 280 pm – Average size of the water molecule 298 pm – radius of a caesium atom, light travels 1 metre in 1⁄299,792,458, or 3. 3356409519815E-9 of a second. 25 metres – wavelength of the broadcast radio shortwave band at 12 MHz 29 metres – height of the lighthouse at Savudrija, Slovenia. 31 metres – wavelength of the broadcast radio shortwave band at 9.7 MHz 34 metres – height of the Split Point Lighthouse in Aireys Inlet, Victoria, Australia. 1 kilometre is equal to,1,000 metres 0.621371 miles 1,093.61 yards 3,280.84 feet 39,370.1 inches 100,000 centimetres 1,000,000 millimetres Side of a square of area 1 km2. Radius of a circle of area π km2,1.637 km – deepest dive of Lake Baikal in Russia, the worlds largest fresh water lake. 2.228 km – height of Mount Kosciuszko, highest point in Australia Most of Manhattan is from 3 to 4 km wide, farsang, a modern unit of measure commonly used in Iran and Turkey. Usage of farsang before 1926 may be for a precise unit derived from parasang. It is the altitude at which the FAI defines spaceflight to begin, to help compare orders of magnitude, this page lists lengths between 100 and 1,000 kilometres. 7.9 Gm – Diameter of Gamma Orionis 9, the newly improved measurement was 30% lower than the previous 2007 estimate. The size was revised in 2012 through improved measurement techniques and its faintness gives us an idea how our Sun would appear when viewed from even so close a distance as this. 350 Pm –37 light years – Distance to Arcturus 373.1 Pm –39.44 light years - Distance to TRAPPIST-1, a star recently discovered to have 7 planets around it. 400 Pm –42 light years – Distance to Capella 620 Pm –65 light years – Distance to Aldebaran This list includes distances between 1 and 10 exametres. 13 Em –1,300 light years – Distance to the Orion Nebula 14 Em –1,500 light years – Approximate thickness of the plane of the Milky Way galaxy at the Suns location 30.8568 Em –3,261. At this scale, expansion of the universe becomes significant, Distance of these objects are derived from their measured redshifts, which depends on the cosmological models used. At this scale, expansion of the universe becomes significant, Distance of these objects are derived from their measured redshifts, which depends on the cosmological models used. 590 Ym –62 billion light years – Cosmological event horizon, displays orders of magnitude in successively larger rooms Powers of Ten Travel across the Universe
5.
Thomson scattering
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Thomson scattering is the elastic scattering of electromagnetic radiation by a free charged particle, as described by classical electromagnetism. It is just the low-energy limit of Compton scattering, the kinetic energy. Thomson scattering is an important phenomenon in plasma physics and was first explained by the physicist J. J. Thomson. As long as the motion of the particle is non-relativistic, the cause of the acceleration of the particle will be due to the electric field component of the incident wave. In a first approximation, the influence of the field can be neglected. The particle will move in the direction of the electric field. The moving particle radiates most strongly in a perpendicular to its acceleration. Therefore, depending on where an observer is located, the light scattered from a volume element may appear to be more or less polarized. The electric fields of the incoming and observed wave can be divided up into those components lying in the plane of observation and those components lying in the plane are referred to as radial and those perpendicular to the plane are tangential. The diagram on the right depicts the plane of observation and it shows the radial component of the incident electric field, which causes the charged particles at the scattering point to exhibit a radial component of acceleration. It can be shown that the amplitude of the wave will be proportional to the cosine of χ. The intensity, which is the square of the amplitude, will then be diminished by a factor of cos2 and it can be seen that the tangential components will not be affected in this way. From the point of view of an observer, there are two emission coefficients, εr corresponding to radially polarized light and εt corresponding to tangentially polarized light, integrating over the solid angle, we obtain the Thomson cross section σ t =8 π32 in SI units. The solar K-corona is the result of the Thomson scattering of radiation from solar coronal electrons. NASAs STEREO mission generates three-dimensional images of the density around the sun by measuring this K-corona from two separate satellites. Inverse-Compton scattering can be viewed as Thomson scattering in the rest frame of the relativistic particle, x-ray crystallography is based on Thomson scattering. Compton scattering Kapitsa–Dirac effect Klein–Nishina formula Billings, Donald E, a guide to the solar corona. Johnson W. R, Nielsen J. Cheng K. T, Thomson scattering in the average-atom approximation
6.
Uranium
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Uranium is a chemical element with symbol U and atomic number 92. It is a metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons, Uranium is weakly radioactive because all its isotopes are unstable. The most common isotopes in natural uranium are uranium-238 and uranium-235, Uranium has the highest atomic weight of the primordially occurring elements. Its density is about 70% higher than that of lead, and it occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite. In nature, uranium is found as uranium-238, uranium-235, Uranium decays slowly by emitting an alpha particle. The half-life of uranium-238 is about 4.47 billion years, many contemporary uses of uranium exploit its unique nuclear properties. Uranium-235 is the naturally occurring fissile isotope, which makes it widely used in nuclear power plants. However, because of the amounts found in nature, uranium needs to undergo enrichment so that enough uranium-235 is present. Uranium-238 is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239 in a nuclear reactor, another fissile isotope, uranium-233, can be produced from natural thorium and is also important in nuclear technology. In sufficient concentration, these maintain a sustained nuclear chain reaction. This generates the heat in nuclear reactors, and produces the fissile material for nuclear weapons. Depleted uranium is used in kinetic energy penetrators and armor plating, Uranium is used as a colorant in uranium glass, producing lemon yellow to green colors. Uranium glass fluoresces green in ultraviolet light and it was also used for tinting and shading in early photography. The 1789 discovery of uranium in the mineral pitchblende is credited to Martin Heinrich Klaproth, eugène-Melchior Péligot was the first person to isolate the metal and its radioactive properties were discovered in 1896 by Henri Becquerel. An ensuing arms race during the Cold War between the United States and the Soviet Union produced tens of thousands of weapons that used uranium metal. The security of those weapons and their fissile material following the breakup of the Soviet Union in 1991 is a concern for public health. When refined, uranium is a white, weakly radioactive metal
7.
Atomic nucleus
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After the discovery of the neutron in 1932, models for a nucleus composed of protons and neutrons were quickly developed by Dmitri Ivanenko and Werner Heisenberg. Almost all of the mass of an atom is located in the nucleus, protons and neutrons are bound together to form a nucleus by the nuclear force. The diameter of the nucleus is in the range of 6985175000000000000♠1.75 fm for hydrogen to about 6986150000000000000♠15 fm for the heaviest atoms and these dimensions are much smaller than the diameter of the atom itself, by a factor of about 23,000 to about 145,000. The branch of physics concerned with the study and understanding of the nucleus, including its composition. The nucleus was discovered in 1911, as a result of Ernest Rutherfords efforts to test Thomsons plum pudding model of the atom, the electron had already been discovered earlier by J. J. Knowing that atoms are electrically neutral, Thomson postulated that there must be a charge as well. In his plum pudding model, Thomson suggested that an atom consisted of negative electrons randomly scattered within a sphere of positive charge, to his surprise, many of the particles were deflected at very large angles. This justified the idea of an atom with a dense center of positive charge. The term nucleus is from the Latin word nucleus, a diminutive of nux, in 1844, Michael Faraday used the term to refer to the central point of an atom. The modern atomic meaning was proposed by Ernest Rutherford in 1912, the adoption of the term nucleus to atomic theory, however, was not immediate. In 1916, for example, Gilbert N, the nuclear strong force extends far enough from each baryon so as to bind the neutrons and protons together against the repulsive electrical force between the positively charged protons. The nuclear strong force has a short range, and essentially drops to zero just beyond the edge of the nucleus. The collective action of the charged nucleus is to hold the electrically negative charged electrons in their orbits about the nucleus. The collection of negatively charged electrons orbiting the nucleus display an affinity for certain configurations, which chemical element an atom represents is determined by the number of protons in the nucleus, the neutral atom will have an equal number of electrons orbiting that nucleus. Individual chemical elements can create more stable electron configurations by combining to share their electrons and it is that sharing of electrons to create stable electronic orbits about the nucleus that appears to us as the chemistry of our macro world. Protons define the entire charge of a nucleus, and hence its chemical identity, neutrons are electrically neutral, but contribute to the mass of a nucleus to nearly the same extent as the protons. Neutrons explain the phenomenon of isotopes – varieties of the chemical element which differ only in their atomic mass. They are sometimes viewed as two different quantum states of the particle, the nucleon
8.
Picometre
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The picometre or picometer is a unit of length in the metric system, equal to 1×10−12 m, or one trillionth of a metre, which is the SI base unit of length. The picometre is one thousandth of a nanometre, one millionth of a micrometre, the symbol µµ was once used for it. It is also one hundredth of an angstrom, a recognised unit of length. The picometres length is of an such that its application is almost entirely confined to particle physics, quantum physics, chemistry. Atoms are between 62 and 520 pm in diameter, and the length of a carbon-carbon single bond is 154 pm. Smaller units still may be used to describe smaller particles, such as hadrons and the upper limits of possible size for fermion point particles
9.
Lipid bilayer
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The lipid bilayer is a thin polar membrane made of two layers of lipid molecules. These membranes are flat sheets that form a barrier around all cells. The cell membranes of almost all living organisms and many viruses are made of a bilayer, as are the membranes surrounding the cell nucleus. The lipid bilayer is the barrier that keeps ions, proteins and other molecules where they are needed, Lipid bilayers are ideally suited to this role because, even though they are only a few nanometers in width, they are impermeable to most water-soluble molecules. Bilayers are particularly impermeable to ions, which allows cells to regulate salt concentrations, biological bilayers are usually composed of amphiphilic phospholipids that have a hydrophilic phosphate head and a hydrophobic tail consisting of two fatty acid chains. Phospholipids with certain groups can alter the surface chemistry of a bilayer and can, for example. Just like the heads, the tails of lipids can also affect membrane properties, the packing of lipids within the bilayer also affects its mechanical properties, including its resistance to stretching and bending. Many of these properties have been studied with the use of model bilayers produced in a lab. Vesicles made by model bilayers have also used clinically to deliver drugs. Biological membranes typically include several types of other than phospholipids. A particularly important example in animal cells is cholesterol, which strengthen the bilayer. Cholesterol also helps regulate the activity of certain integral membrane proteins, integral membrane proteins function when incorporated into a lipid bilayer, and they are held tightly to lipid bilayer with the help of an annular lipid shell. Because bilayers define the boundaries of the cell and its compartments, certain kinds of membrane proteins are involved in the process of fusing two bilayers together. This fusion allows the joining of two structures as in the fertilization of an egg by sperm or the entry of a virus into a cell. Because lipid bilayers are quite fragile and invisible in a traditional microscope, experiments on bilayers often require advanced techniques like electron microscopy and atomic force microscopy. When phospholipids are exposed to water, they self-assemble into a sheet with the hydrophobic tails pointing toward the center of the sheet. This arrangement results in two “leaflets” that are each a single molecular layer, the center of this bilayer contains almost no water and excludes molecules like sugars or salts that dissolve in water. The assembly process is driven by interactions between hydrophobic molecules, an increase in interactions between hydrophobic molecules allows water molecules to bond more freely with each other, increasing the entropy of the system
10.
Amino acid
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Amino acids are organic compounds containing amine and carboxyl functional groups, along with a side chain specific to each amino acid. The key elements of an acid are carbon, hydrogen, oxygen. About 500 amino acids are known and can be classified in many ways, in the form of proteins, amino acids comprise the second-largest component of human muscles, cells and other tissues. Outside proteins, amino acids perform critical roles in such as neurotransmitter transport. In biochemistry, amino acids having both the amine and the acid groups attached to the first carbon atom have particular importance. They are known as 2-, alpha-, or α-amino acids and they include the 22 proteinogenic amino acids, which combine into peptide chains to form the building-blocks of a vast array of proteins. These are all L-stereoisomers, although a few D-amino acids occur in bacterial envelopes, as a neuromodulator, twenty of the proteinogenic amino acids are encoded directly by triplet codons in the genetic code and are known as standard amino acids. The other two are selenocysteine, and pyrrolysine, pyrrolysine and selenocysteine are encoded via variant codons, for example, selenocysteine is encoded by stop codon and SECIS element. N-formylmethionine is generally considered as a form of methionine rather than as a separate proteinogenic amino acid, codon–tRNA combinations not found in nature can also be used to expand the genetic code and create novel proteins known as alloproteins incorporating non-proteinogenic amino acids. Many important proteinogenic and non-proteinogenic amino acids also play critical roles within the body. Nine proteinogenic amino acids are called essential for humans because they cannot be created from other compounds by the human body, others may be conditionally essential for certain ages or medical conditions. Essential amino acids may also differ between species, because of their biological significance, amino acids are important in nutrition and are commonly used in nutritional supplements, fertilizers, and food technology. Industrial uses include the production of drugs, biodegradable plastics, the first few amino acids were discovered in the early 19th century. In 1806, French chemists Louis-Nicolas Vauquelin and Pierre Jean Robiquet isolated a compound in asparagus that was subsequently named asparagine, cystine was discovered in 1810, although its monomer, cysteine, remained undiscovered until 1884. Glycine and leucine were discovered in 1820, usage of the term amino acid in the English language is from 1898. Proteins were found to yield amino acids after enzymatic digestion or acid hydrolysis, in the structure shown at the top of the page, R represents a side chain specific to each amino acid. The carbon atom next to the group is called the α–carbon. Amino acids containing an amino group bonded directly to the alpha carbon are referred to as amino acids
11.
Globular protein
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Globular proteins or spheroproteins are spherical proteins and are one of the common protein types. Globular proteins are somewhat water-soluble, unlike the fibrous or membrane proteins, there are multiple fold classes of globular proteins, since there are many different architectures that can fold into a roughly spherical shape. The term globin can refer specifically to proteins including the globin fold. The term globular protein is quite old and is now somewhat archaic given the hundreds of thousands of proteins and more elegant, the globular nature of these proteins can be determined without the means of modern techniques, but only by using ultracentrifuges or dynamic light scattering techniques. The spherical structure is induced by the tertiary structure. Globular proteins are only marginally stable because the energy released when the protein folded into its native conformation is relatively small. This is because protein folding requires entropic cost, as a primary sequence of a polypeptide chain can form numerous conformations, native globular structure restricts its conformation to a few only. It results in a decrease in randomness, although non-covalent interactions such as hydrophobic interactions stabilize the structure, although it is still unknown how proteins fold up naturally, new evidence has helped advance understanding. Part of the protein folding problem is that several non-covalent, weak interactions are formed, such as hydrogen bonds, via several techniques, the mechanism of protein folding is currently being studied. Even in the denatured state, it can be folded into the correct structure. These new findings have shown that the states of proteins may affect the way they fold. The folding of proteins has also recently been connected to treatment of diseases. These studies have shown that the folding of globular proteins affects its function, by the second law of thermodynamics, the free energy difference between unfolded and folded states is contributed by enthalpy and entropy changes. Messengers, by transmitting messages to regulate biological processes and this function is done by hormones, i. e. insulin etc. Transporters of other molecules through membranes Stocks of amino acids, regulatory roles are also performed by globular proteins rather than fibrous proteins. Other globular proteins are the immunoglobulins, and alpha, beta, see protein electrophoresis for more information on the different globulins. Nearly all enzymes with major metabolic functions are globular in shape, albumins are also globular proteins, although, unlike all of the other globular proteins, they are completely soluble in water
12.
Nuclear pore complex
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Nuclear pores are large protein complexes that cross the nuclear envelope, which is the double membrane surrounding the eukaryotic cell nucleus. There are about an average of 2000 nuclear pore complexes, in the envelope of a vertebrate cell, but it varies depending on cell type. The proteins that make up the pore complex are known as nucleoporins. About half of the nucleoporins typically contain solenoid protein domains—either an alpha solenoid or a beta-propeller fold, each NPC contains at least 456 individual protein molecules and is composed of 30 distinct proteins. The other half show structural characteristics typical of natively unfolded or intrinsically disordered proteins and these disordered proteins are the FG nucleoporins, so called because their amino-acid sequence contains many phenylalanine—glycine repeats. Nuclear pore complexes allow the transport of molecules across the nuclear envelope and this transport includes RNA and ribosomal proteins moving from nucleus to the cytoplasm and proteins, carbohydrates, signaling molecules and lipids moving into the nucleus. It is notable that the pore complex can actively conduct 1000 translocations per complex per second. Nucleoporin-mediated transport is not directly energy requiring, but depends on concentrations gradients associated with the RAN cycle, each of the eight protein subunits surrounding the actual pore projects a spoke-shaped protein over the pore channel. The center of the pore often appears to contain a plug-like structure and it is yet unknown whether this corresponds to an actual plug or is merely cargo caught in transit. The entire nuclear pore complex has a diameter of about 120 nanometers in vertebrates, the molecular mass of the mammalian NPC is about 124 megadaltons and it contains approximately 30 different protein components, each in multiple copies. In contrast, the yeast Saccharomyces cerevisiae is smaller, weighing only 66 MDa, small particles are able to pass through the nuclear pore complex by passive diffusion. Larger particles are able to diffuse passively through the large diameter of the pore. Other nuclar transport receptors include NTF2 and some NTF2-like proteins, several NLS sequences are known, generally containing a conserved sequence with basic residues such as PKKKRKV. Any material with an NLS will be taken up by importins to the nucleus, the classical scheme of NLS-protein importation begins with Importin-α first binding to the NLS sequence, which then acts as a bridge for Importin-β to attach. The importinβ—importinα—cargo complex is directed towards the nuclear pore and diffuses through it. Once the complex is in the nucleus, RanGTP binds to Importin-β, then the cellular apoptosis susceptibility protein, an exportin which in the nucleus is bound to RanGTP, displaces Importin-α from the cargo. The NLS-protein is thus free in the nucleoplasm, although cargo passes through the pore with the assistance of chaperone proteins, the translocation through the pore itself is not energy-dependent. However, the import cycle needs the hydrolysis of 2 GTPs and is thus energy-dependent and has to be considered as active transport
13.
Escherichia coli
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Escherichia coli is a gram-negative, facultatively anaerobic, rod-shaped, coliform bacterium of the genus Escherichia that is commonly found in the lower intestine of warm-blooded organisms. Most E. coli strains are harmless, but some serotypes can cause food poisoning in their hosts. The harmless strains are part of the flora of the gut, and can benefit their hosts by producing vitamin K2. E. coli is expelled into the environment within fecal matter, the bacterium grows massively in fresh fecal matter under aerobic conditions for 3 days, but its numbers decline slowly afterwards. E. coli and other facultative anaerobes constitute about 0. 1% of gut flora, cells are able to survive outside the body for a limited amount of time, which makes them potential indicator organisms to test environmental samples for fecal contamination. A growing body of research, though, has examined environmentally persistent E. coli which can survive for extended periods outside of a host, the bacterium can be grown and cultured easily and inexpensively in a laboratory setting, and has been intensively investigated for over 60 years. E. coli is a chemoheterotroph whose chemically defined medium must include a source of carbon, under favorable conditions, it takes only 20 minutes to reproduce. E. coli is a Gram-negative, facultative anaerobic and nonsporulating bacterium, cells are typically rod-shaped, and are about 2.0 μm long and 0. 25–1.0 μm in diameter, with a cell volume of 0. 6–0.7 μm3. E. coli stains Gram-negative because its cell wall is composed of a peptidoglycan layer. During the staining process, E. coli picks up the color of the counterstain safranin, the outer membrane surrounding the cell wall provides a barrier to certain antibiotics such that E. coli is not damaged by penicillin. Strains that possess flagella are motile, the flagella have a peritrichous arrangement. E. coli can live on a variety of substrates and uses mixed-acid fermentation in anaerobic conditions, producing lactate, succinate, ethanol, acetate. Optimum growth of E. coli occurs at 37 °C, and it uses oxygen when it is present and available. It can, however, continue to grow in the absence of oxygen using fermentation or anaerobic respiration, the ability to continue growing in the absence of oxygen is an advantage to bacteria because their survival is increased in environments where water predominates. The bacterial cell cycle is divided into three stages, the B period occurs between the completion of cell division and the beginning of DNA replication. The C period encompasses the time it takes to replicate the chromosomal DNA, the D period refers to the stage between the conclusion of DNA replication and the end of cell division. The doubling rate of E. coli is higher when more nutrients are available, However, the length of the C and D periods do not change, even when the doubling time becomes less than the sum of the C and D periods. At the fastest growth rates, replication begins before the round of replication has completed, resulting in multiple replication forks along the DNA
14.
Red blood cell
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RBCs take up oxygen in the lungs, or gills of fish, and release it into tissues while squeezing through the bodys capillaries. The cytoplasm of erythrocytes is rich in hemoglobin, a biomolecule that can bind oxygen and is responsible for the red color of the cells. In humans, mature red cells are flexible and oval biconcave disks. They lack a nucleus and most organelles, in order to accommodate maximum space for hemoglobin, they can be viewed as sacks of hemoglobin. Approximately 2.4 million new erythrocytes are produced per second in human adults, the cells develop in the bone marrow and circulate for about 100–120 days in the body before their components are recycled by macrophages. Each circulation takes about 60 seconds, approximately a quarter of the cells in the human body are red blood cells. Nearly half of the volume is red blood cells. Red blood cells are known as RBCs, red cells, red blood corpuscles, haematids. Packed red blood cells are red blood cells that have donated, processed. Almost all vertebrates, including all mammals and humans, have red blood cells, red blood cells are cells present in blood in order to transport oxygen. The only known vertebrates without red blood cells are the crocodile icefish, they live in very cold water. While they no longer use hemoglobin, remnants of hemoglobin genes can be found in their genome, oxygen can easily diffuse through the red blood cells cell membrane. Myoglobin, a related to hemoglobin, acts to store oxygen in muscle cells. The color of red cells is due to the heme group of hemoglobin. However, blood can appear bluish when seen through the vessel wall, pulse oximetry takes advantage of the hemoglobin color change to directly measure the arterial blood oxygen saturation using colorimetric techniques. Hemoglobin also has a high affinity for carbon monoxide, forming carboxyhemoglobin which is a very bright red in color. Flushed, confused patients with a reading of 100% on pulse oximetry are sometimes found to be suffering from carbon monoxide poisoning. The red blood cells of mammals are typically shaped as disks, flattened and depressed in the center, with a dumbbell-shaped cross section
15.
Dots per inch
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Dots per inch is a measure of spatial printing or video dot density, in particular the number of individual dots that can be placed in a line within the span of 1 inch. Monitors do not have dots, but do have pixels, the related concept for monitors. Many resources, including the Android developer guide, use the terms DPI and PPI interchangeably, old CRT type video displays were almost universally rated in dot pitch, which refers to the spacing between the sub-pixel red, green and blue dots which made up the pixels themselves. Monitor manufacturers used the term dot trio pitch, the measurement of the distance between the centers of adjacent groups of three dots/rectangles/squares on the CRT screen. Monitors commonly used dot pitches of 0.39,0.33,0.32,0.29,0.27,0.25, LCD monitors have a trio of sub pixels, which are more easily measured. This is caused by the spreading of ink on the surface of the media, up to a point, printers with higher DPI produce clearer and more detailed output. A printer does not necessarily have a single DPI measurement, it is dependent on print mode, the range of DPI supported by a printer is most dependent on the print head technology it uses. A dot matrix printer, for example, applies ink via tiny rods striking an ink ribbon, an inkjet printer sprays ink through tiny nozzles, and is typically capable of 300–720 DPI. A laser printer applies toner through an electrostatic charge. The DP measurement of a printer often needs to be higher than the pixels per inch measurement of a video display in order to produce similar-quality output. This is due to the range of colors for each dot typically available on a printer. Higher-end inkjet printers can offer 5,6 or 7 ink colors giving 32,64 or 128 possible tones per dot location, contrast this to a standard sRGB monitor where each pixel produces 256 intensities of light in each of three channels. While some color printers can produce variable drop volumes at each dot position, and may use additional ink-color channels and this dithered printing process could require a region of four to six dots in order to faithfully reproduce the color in a single pixel. Fittingly,600 dpi is now the output resolution of entry-level laser printers and some utility inkjet printers, with 1200/1440. In printing, DPI refers to the resolution of a printer or imagesetter. DPI refers to the dot density of an image when it is reproduced as a real physical entity. A digitally stored image has no inherent physical dimensions, measured in inches or centimeters, some digital file formats record a DPI value, or more commonly a PPI value, which is to be used when printing the image. This number lets the printer or software know the size of the image, or in the case of scanned images
16.
Pixel
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The address of a pixel corresponds to its physical coordinates. LCD pixels are manufactured in a grid, and are often represented using dots or squares. Each pixel is a sample of an image, more samples typically provide more accurate representations of the original. The intensity of each pixel is variable, in color imaging systems, a color is typically represented by three or four component intensities such as red, green, and blue, or cyan, magenta, yellow, and black. The word pixel is based on a contraction of pix and el, the word pixel was first published in 1965 by Frederic C. Billingsley of JPL, to describe the elements of video images from space probes to the Moon. Billingsley had learned the word from Keith E. McFarland, at the Link Division of General Precision in Palo Alto, McFarland said simply it was in use at the time. The word is a combination of pix, for picture, the word pix appeared in Variety magazine headlines in 1932, as an abbreviation for the word pictures, in reference to movies. By 1938, pix was being used in reference to pictures by photojournalists. The concept of a picture element dates to the earliest days of television, some authors explain pixel as picture cell, as early as 1972. In graphics and in image and video processing, pel is often used instead of pixel, for example, IBM used it in their Technical Reference for the original PC. A pixel is generally thought of as the smallest single component of a digital image, however, the definition is highly context-sensitive. For example, there can be printed pixels in a page, or pixels carried by electronic signals, or represented by digital values, or pixels on a display device, or pixels in a digital camera. This list is not exhaustive and, depending on context, synonyms include pel, sample, byte, bit, dot, Pixels can be used as a unit of measure such as,2400 pixels per inch,640 pixels per line, or spaced 10 pixels apart. For example, a high-quality photographic image may be printed with 600 ppi on a 1200 dpi inkjet printer, even higher dpi numbers, such as the 4800 dpi quoted by printer manufacturers since 2002, do not mean much in terms of achievable resolution. The more pixels used to represent an image, the closer the result can resemble the original, the number of pixels in an image is sometimes called the resolution, though resolution has a more specific definition.3 megapixels. The pixels, or color samples, that form an image may or may not be in one-to-one correspondence with screen pixels. In computing, a composed of pixels is known as a bitmapped image or a raster image
17.
Computer monitor
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A computer monitor or a computer display is an electronic visual display for computers. A monitor usually comprises the display device, circuitry, casing, the display device in modern monitors is typically a thin film transistor liquid crystal display or a flat panel LED display, while older monitors used a cathode ray tubes. It can be connected to the computer via VGA, DVI, HDMI, DisplayPort, Thunderbolt, LVDS or other proprietary connectors, originally, computer monitors were used for data processing while television receivers were used for entertainment. From the 1980s onwards, computers have used for both data processing and entertainment, while televisions have implemented some computer functionality. The common aspect ratio of televisions, and computer monitors, has changed from 4,3 to 16,10, to 16,9. Early electronic computers were fitted with a panel of light bulbs where the state of each particular bulb would indicate the state of a particular register bit inside the computer. This allowed the operating the computer to monitor the internal state of the machine. As early monitors were only capable of displaying a limited amount of information. Instead, a printer was the primary output device, while the monitor was limited to keeping track of the programs operation. Multiple technologies have used for computer monitors. Until the 21st century most used cathode ray tubes but they have largely superseded by LCD monitors. The first computer monitors used cathode ray tubes, high-resolution CRT displays were developed for specialized military, industrial and scientific applications but they were far too costly for general use. Either computer could be connected to the terminals of an ordinary color TV set or used with a purpose-made CRT color monitor for optimum resolution. In 1984 IBM introduced the Enhanced Graphics Adapter which was capable of producing 16 colors and had a resolution of 640 x 350, by the end of the 1980s color CRT monitors that could clearly display 1024 x 768 pixels were widely available and increasingly affordable. During the following decade maximum display resolutions gradually increased and prices continued to fall, CRT technology remained dominant in the PC monitor market into the new millennium partly because it was cheaper to produce and offered viewing angles close to 180 degrees. CRTs still offer some image quality advantages over LCDs but improvements to the latter have made much less obvious. There are multiple technologies that have used to implement liquid crystal displays. Commonly, the laptop would be offered with an assortment of display options at increasing price points, monochrome
18.
Mechanical pencil
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A mechanical pencil or a propelling pencil is a pencil with a replaceable and mechanically extendable solid pigment core called a lead /ˈlɛd/. The lead, often made of graphite, is not bonded to the outer casing, other names include automatic pencil, drafting pencil, technical pencil, click pencil, clutch pencil, leadholder, pen pencil, lead pencil, and pacer. Mechanical pencils are used to provide lines of constant width without sharpening in technical drawing and they have also been used for fine-art drawing. Mechanical pencils were first used in the 18th century, with many designs patented in the 19th and 20th centuries, conrad Gesner described a leadholder pencil in 1565, but the lead had to be manually adjusted to sharpen it. The earliest extant example of a pencil was found aboard the wreckage of HMS Pandora. The first patent for a pencil with lead-propelling mechanism was issued to Sampson Mordan. After buying out Hawkins patent rights, Mordan entered into a partnership with Gabriel Riddle from 1823 to 1837. The earliest Mordan pencils are thus hallmarked SMGR, after 1837, Sampson Mordan ended the partnership with Riddle and continued to manufacture pencils as S. MORDAN & CO. His company continued to manufacture pencils and a range of silver objects until World War II. Between 1822 and 1874, more than 160 patents were registered pertaining to a variety of improvements to mechanical pencils, the first spring-loaded mechanical pencil was patented in 1877 and a twist-feed mechanism was developed in 1895. The 0.9 mm lead was introduced in 1938, eventually,1.3 and 1.4 mm mechanisms were available, and 0.4 and 0.2 versions are now produced. The mechanical pencil became successful in Japan with some improvements in 1915 by Tokuji Hayakawa and it was introduced as the Ever-Ready Sharp Pencil. Success was not immediate, since the metal shaft—essential for the pencils long life—was unfamiliar to users, however, the Ever-Ready Sharp began selling in huge numbers after a company from Tokyo and Osaka made large orders. Later, Tokuji Hayakawas company got its name from that pencil, at nearly the same time in the US, Charles R. Keeran was developing a similar pencil that would be the precursor of most of todays pencils. Keerans design was ratchet-based, whereas Hayakawas was screw-based and these two development histories – Hayakawa and Keeran – are often mistakenly combined into one. Keeran patented his lead pencil in 1915 and soon afterwards arranged production, after some improvements, his design was marketed as the Eversharp pencil by the Wahl Adding Machine Company, by the early 1920s, Wahl had sold more than 12,000,000 Eversharps. Mechanical pencils can be divided into two types, those that both hold the lead and can actively propel it forward, and those that only hold the lead in position. Screw-based pencils advance the lead by twisting a screw, which moves a slider down the barrel of the pencil and this was the most common type in the earlier part of the twentieth century
19.
Fovea centralis
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The fovea centralis is a small, central pit composed of closely packed cones in the eye. It is located in the center of the macula lutea of the retina, the fovea is responsible for sharp central vision, which is necessary in humans for activities where visual detail is of primary importance, such as reading and driving. The fovea is surrounded by the belt, and the perifovea outer region. The perifovea contains a more diminished density of cones, having 12 per 100 micrometres versus 50 per 100 micrometres in the most central fovea. This, in turn, is surrounded by a peripheral area that delivers highly compressed information of low resolution following the pattern of compression in foveated imaging. Approximately half of the fibers in the optic nerve carry information from the fovea. The parafovea extends to a radius of 1.25 mm from the fovea. Anatomical macula / macula lutea / area centralis, Diameter =5. 5mm Demarcated by the superior and inferior temporal arterial arcades. Histologically the only region of the retina where GCL has >1 layer of ganglion cells Yellowish appearance = luteal pigments (xanthophyll, GCL has >5 layers of cells, and highest density of cones Anatomical perifovea, Region between parafovea and edge of macula GCL has 2-4 layers of cells. 12 cones /100 um Anatomical fovea / fovea centralis Area of depression in the centre of the macula lutea, within the Fovea is a region of 0. 5mm diameter celled the foveal avascular zone. This allows the light to be sensed without any dispersion or loss and this anatomy is responsible for the depression in the center of the fovea. The foveal pit is surrounded by the rim that contains the neurons displaced from the pit. This is the thickest part of the retina, the fovea is located in a small avascular zone and receives most of its oxygen from the vessels in the choroid, which is across the retinal pigment epithelium and Bruchs membrane. The high spatial density of cones along with the absence of blood vessels at the fovea accounts for the visual acuity capability at the fovea. The center of the fovea is the foveola – about 0.2 mm in diameter – or central pit where only cone photoreceptors are present, the central fovea consists of very compact cones, thinner and more rod-like in appearance than cones elsewhere. These cones are very densely packed, starting at the outskirts of the fovea, however, rods gradually appear, and the absolute density of cone receptors progressively decreases. Fovea size is compared to the rest of retina, but the fovea is the only area of the retina where 20/20 vision is attainable. In the primate fovea the ratios of ganglion cells to photoreceptors is about 2.5, almost every ganglion cell receives data from a single cone, and each cone feeds onto between 1 and 3 ganglion cells
20.
Pin
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A pin is a device used for fastening objects or material together. Pins often have two components, a body and sharp tip made of steel, or occasionally copper or brass. The sharpened body penetrates the material, while the larger head provides a driving surface and it is formed by drawing out a thin wire, sharpening the tip, and adding a head. Nails are related, but are typically larger, in machines and engineering, pins are commonly used as pivots, hinges, shafts, jigs, and fixtures to locate or hold parts. The development of the pin closely paralleled that of its perforated counterpart, archaeological evidence suggests that curved sewing pins have been used for over four thousand years. Originally, these were fashioned out of iron and bone by the Sumerians and were used to hold clothes together, later, pins were also used to hold pages of books together by threading the needle through their top corner. Many later pins were made of brass, a relatively hard and this development was followed by the use of steel which was much stronger but tended to rust when exposed to humid air. The development of inexpensive electroplating techniques allowed the steel to be plated with nickel, nickel did not rust, but tended to flake off the steel in humid weather, again allowing it to rust. Note, however, that some modern specialty pins are made out of rust-proof, walter Hunt invented the safety pin by forming an eight-inch brass pin into a bent pin with a spring and guard. He sold the rights to his invention to pay a debt to a friend, the push pin was invented in 1900 by Edwin Moore and quickly became a success. These pins are also called thumbtacks, there is also a new push pin called a paper cricket. Thin, hardened pins can be driven into wood with a hammer with the goal of not being seen, a different style pin, somewhat thicker,2 cm short and with rounded tip is used with gramophones. The vibration of the stylus transforms the physical waves of the groove in a record to the movement of a membrane, in this way the sound recorded can be heard. In engineering and machine design, a pin is an element that secures the position of two or more parts of a machine relative to each other. A large variety of types has been known for a long time, clevis pin Cotter pin Spring pin Split pin Henry Petroski, The Evolution of Useful Things, Chapter 4. Robert Parmley, Standard handbook of fastening and joining
21.
Hole punch
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A hole punch is a common office tool that is used to create holes in sheets of paper, often for the purpose of collecting the sheets in a binder or folder. A leather punch, of different construction from one designed for paper, is used for goods, cloth. Hole punch tools are made for use on sheet metal. A typical hole punch, whether a single or multiple hole punch, has a lever which is used to push a bladed cylinder straight through a number of sheets of paper. As the vertical distance of the cylinder is only a few millimeters. For low volume hole punches, the resulting lever need not be more than 8 centimetres for sufficient force, two paper guides are needed to line up the paper, one opposite where the paper is inserted, to set the margin distance, and one on an adjacent side. Hole punches for industrial volumes feature very long arms. Another mechanism uses hollowed drills which are lowered by an action into the paper. The paper is cut and forced up into the shaft of the drill to be discarded as tightly packed columns of waste paper. This method allows a machine to cut industrial volumes of paper with little effort. The most common standard for the dimensions and location of filing holes punched in paper is International Standard ISO838, two holes with a diameter of 6±0.5 mm are punched into the paper. The centers of these holes are 80±0.5 mm apart and have a distance of 12±1 mm to the nearest edge of the paper, the holes are located symmetrically in relation to the axis of the sheet or document. Any paper format that is at least 100 mm high can be filed using this system, a printed document with a margin of 20–25 mm will accommodate ISO838 filing holes. A four-hole extension is also commonly used, the two middle holes are punched in accordance with ISO838, and so paper punched with the four holes can be filed in binders that are consistent with ISO838. The two additional holes are located 80 mm above and below these, the use of two additional holes provides more stability. This extension is sometimes referred to as the 888 system, because of the three 8-cm gaps between the holes, some 2-hole punches have an 888 marking on their paper guide, to assist punching all four holes into A4 paper. For US Legal Size paper format traditionally 4 holes has been used in the past and still in use today, the 4 holes are preferred due to the extra long length of 14-inch side of the paper where the 4 holes would be placed. Binders with 4 rings gives the paper better support in the binder, were the documents only punched with 3 holes, this would allow sagging of the paper at the top part of the binder above the top ring
22.
Postage stamp
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Postage stamp may also refer to a formatting artifact in the display of film or video, Windowbox. A postage stamp is a piece of paper that is purchased and displayed on an item of mail as evidence of payment of postage. Typically, stamps are printed on special paper, show a national designation and a denomination on the front. They are sometimes a source of net profit to the issuing agency, stamps are usually rectangular, but triangles or other shapes are occasionally used. The stamp is affixed to an envelope or other postal cover the customer wishes to send, the item is then processed by the postal system, where a postmark, sometimes known as a cancellation mark, is usually applied in overlapping manner to stamp and cover. This procedure marks the stamp as used to prevent its reuse, in modern usage, postmarks generally indicate the date and point of origin of the mailing. The mailed item is delivered to the address the customer has applied to the envelope or parcel. Postage stamps have facilitated the delivery of mail since the 1840s, before then, ink and hand-stamps, usually made from wood or cork, were often used to frank the mail and confirm the payment of postage. The first adhesive postage stamp, commonly referred to as the Penny Black, was issued in the United Kingdom in 1840, there are varying accounts of the inventor or inventors of the stamp. The postage stamp resolved this issue in a simple and elegant manner, concurrently with the first stamps, the UK offered wrappers for mail. S. Postal service for priority or express mailing, the postage stamp afforded convenience for both the mailer and postal officials, more effectively recovered costs for the postal service, and ultimately resulted in a better, faster postal system. With the conveniences stamps offered, their use resulted in greatly increased mailings during the 19th and 20th centuries, as postage stamps with their engraved imagery began to appear on a widespread basis, historians and collectors began to take notice. The study of stamps and their use is referred to as philately. Stamp collecting can be both a hobby and a form of study and reference, as government-issued postage stamps. The postage for the item was prepaid by the use of a hand-stamp to frank the mailed item. Though this stamp was applied to a letter instead of a piece of paper it is considered by many historians as the worlds first postage stamp. Rowland Hill The Englishman Sir Rowland Hill began interest in postal reform in 1835, in 1836, a Member of Parliament, Robert Wallace, provided Hill with numerous books and documents, which Hill described as a half hundred weight of material. Hill commenced a study of these documents, leading him to the 1837 publication of a pamphlet entitled Post Office Reform its Importance
23.
Credit card
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The card issuer creates a revolving account and grants a line of credit to the cardholder, from which the cardholder can borrow money for payment to a merchant or as a cash advance. A credit card is different from a card, where it requires the balance to be repaid in full each month. In contrast, credit cards allow the consumers a continuing balance of debt, a credit card also differs from a cash card, which can be used like currency by the owner of the card. Credit cards have a printed or embossed bank card number complying with the ISO/IEC7812 numbering standard, the card numbers prefix, called the Bank Identification Number, is the sequence of digits at the beginning of the number that determine the bank to which a credit card number belongs. This is the first six digits for MasterCard and Visa cards, the next nine digits are the individual account number, and the final digit is a validity check code. Both of these standards are maintained and further developed by ISO/IEC JTC 1/SC 17/WG1, Credit cards have a magnetic stripe conforming to the ISO/IEC7813. Many modern credit cards have a chip embedded in them as a security feature. In addition to the credit card number, credit cards also carry issue and expiration dates, as well as extra codes such as issue numbers. Not all credit cards have the sets of extra codes nor do they use the same number of digits. The concept of using a card for purchases was described in 1887 by Edward Bellamy in his utopian novel Looking Backward. Bellamy used the credit card eleven times in this novel, although this referred to a card for spending a citizens dividend from the government. Charge coins and other items were used from the late 19th century to the 1930s. They came in various shapes and sizes, with materials made out of celluloid, copper, aluminum, steel, each charge coin usually had a little hole, enabling it to be put in a key ring, like a key. These charge coins were given to customers who had charge accounts in department stores, hotels. A charge coin usually had the account number along with the merchants name. The charge coin offered a simple and fast way to copy a charge account number to the sales slip and this sped the process of copying, previously done by handwriting. It also reduced the number of errors, by having a form of numbers on the sales slip. Because the customers name was not on the coin, almost anyone could use it
24.
Cigarette
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A cigarette, or cigaret, is a small cylinder of finely cut tobacco leaves rolled in thin paper for smoking. Most modern manufactured cigarettes are filtered, and also include reconstituted tobacco, the term cigarette, as commonly used, refers to a tobacco cigarette, but can apply to similar devices other substances, such as cannabis. A cigarette is distinguished from a cigar by its size, use of processed leaf, and paper wrapping. Cigars are typically composed entirely of whole-leaf tobacco, rates of cigarette smoking vary widely throughout the world and have changed considerably since cigarettes were first widely used in the mid-19th century. While rates of smoking have over time leveled off or declined in the developed world, Cigarettes carry serious health risks, which are more prevalent than with other tobacco products. Nicotine, the psychoactive chemical in tobacco and therefore cigarettes, is very addictive. About half of cigarette smokers die of tobacco-related disease and lose on average 14 years of life, cigarette use by pregnant women has also been shown to cause birth defects, including low birth weight, fetal abnormalities, and premature birth. Second-hand smoke from cigarettes has been shown to be injurious to bystanders, Cigarettes produce an aerosol containing over 4,000 chemical compounds, including nicotine, carbon monoxide, acrolein, and other harmful substances. Over 50 of these are carcinogenic, the earliest forms of cigarettes were similar to their predecessor, the cigar. Cigarettes appear to have had antecedents in Mexico and Central America around the 9th century in the form of reeds, the Maya, and later the Aztecs, smoked tobacco and other psychoactive drugs in religious rituals and frequently depicted priests and deities smoking on pottery and temple engravings. The cigarette and the cigar were the most common methods of smoking in the Caribbean, Mexico, and Central and South America until recent times. The North American, Central American, and South American cigarette used various plant wrappers, when it was back to Spain, maize wrappers were introduced. The resulting product was called papelate and is documented in Goyas paintings La Cometa, La Merienda en el Manzanares, by 1830, the cigarette had crossed into France, where it received the name cigarette, and in 1845, the French state tobacco monopoly began manufacturing them. The first patented cigarette machine was by Juan Nepomuceno Adorno of Mexico in 1847 and this was helped by the development of tobaccos suitable for cigarette use, and by the development of the Egyptian cigarette export industry. Cigarettes may have initially used in a manner similar to pipes, cigars. As cigarette tobacco became milder and more acidic, inhaling may have perceived as more agreeable. However, Moltke noticed in the 1830s that Ottomans inhaled the Turkish tobacco, the widespread smoking of cigarettes in the Western world is largely a 20th-century phenomenon. At the start of the 20th century, the per capita consumption in the USA was 54 cigarettes
25.
Inch
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The inch is a unit of length in the imperial and United States customary systems of measurement now formally equal to 1⁄36 yard but usually understood as 1⁄12 of a foot. Derived from the Roman uncia, inch is also used to translate related units in other measurement systems. The English word inch was a borrowing from Latin uncia not present in other Germanic languages. The vowel change from Latin /u/ to English /ɪ/ is known as umlaut, the consonant change from the Latin /k/ to English /tʃ/ or /ʃ/ is palatalisation. Both were features of Old English phonology, inch is cognate with ounce, whose separate pronunciation and spelling reflect its reborrowing in Middle English from Anglo-Norman unce and ounce. In many other European languages, the word for inch is the same as or derived from the word for thumb, the inch is a commonly used customary unit of length in the United States, Canada, and the United Kingdom. It is also used in Japan for electronic parts, especially display screens, for example, three feet two inches can be written as 3′ 2″. Paragraph LXVII sets out the fine for wounds of various depths, one inch, one shilling, an Anglo-Saxon unit of length was the barleycorn. After 1066,1 inch was equal to 3 barleycorns, which continued to be its legal definition for several centuries, similar definitions are recorded in both English and Welsh medieval law tracts. One, dating from the first half of the 10th century, is contained in the Laws of Hywel Dda which superseded those of Dyfnwal, both definitions, as recorded in Ancient Laws and Institutes of Wales, are that three lengths of a barleycorn is the inch. However, the oldest surviving manuscripts date from the early 14th century, john Bouvier similarly recorded in his 1843 law dictionary that the barleycorn was the fundamental measure. He noted that this process would not perfectly recover the standard, before the adoption of the international yard and pound, various definitions were in use. In the United Kingdom and most countries of the British Commonwealth, the United States adopted the conversion factor 1 metre =39.37 inches by an act in 1866. In 1930, the British Standards Institution adopted an inch of exactly 25.4 mm, the American Standards Association followed suit in 1933. By 1935, industry in 16 countries had adopted the industrial inch as it came to be known, in 1946, the Commonwealth Science Congress recommended a yard of exactly 0.9144 metres for adoption throughout the British Commonwealth. This was adopted by Canada in 1951, the United States on 1 July 1959, Australia in 1961, effective 1 January 1964, and the United Kingdom in 1963, effective on 1 January 1964. The new standards gave an inch of exactly 25.4 mm,1.7 millionths of a longer than the old imperial inch and 2 millionths of an inch shorter than the old US inch. The United States retains the 1/39. 37-metre definition for survey purposes and this is approximately 1/8-inch in a mile
26.
Paper size
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Many paper size standards conventions have existed at different times and in different countries. Today, the A and B series of ISO216, which includes the commonly used A4 size, are the standard used by almost every country. In some areas under strong US influence, Letter is more prevalent, Paper sizes affect writing paper, stationery, cards, and some printed documents. The international standard for envelopes is the C series of ISO269, the international paper size standard is ISO216. It is based on the German DIN476 standard for paper sizes, ISO paper sizes are all based on a single aspect ratio of square root of 2, or approximately 1,1.4142. There are different series, as well as several extensions, the following international paper sizes are included in Cascading Style Sheets, A3, A4, A5, B4, B5. The base A0 size of paper is defined as having an area of 1 m2, rounded to the nearest millimetre, that is 841 by 1,189 millimetres. Successive paper sizes in the series A1, A2, A3 and this also effectively halves the area of each sheet. The most frequently used paper size is A4 measuring 210 by 297 millimetres, folded brochures of any size can be made by using sheets of the next larger size, e. g. A4 sheets are folded to make A5 brochures. The system allows scaling without compromising the aspect ratio from one size to another—as provided by office photocopiers, similarly, two sheets of A4 can be scaled down and fit exactly on 1 sheet without any cutoff or margins. The behavior of the ratio is easily proven, on a sheet of paper, let a be the long side and b be the short side, thus. When the sheet of paper is folded in half widthwise, let c be the length of the new short side, c = a/2. If we take the ratio of the folded paper we have, b c = b a 2 =2 a b =22 =2 Therefore. The advantages of basing a paper size upon an aspect ratio of √2 were first noted in 1786 by the German scientist and philosopher Georg Christoph Lichtenberg. The formats that became A2, A3, B3, B4 and B5 were developed in France on proposition of the mathematician Lazare Carnot, early in the 20th century, Dr Walter Porstmann turned Lichtenbergs idea into a proper system of different paper sizes. Porstmanns system was introduced as a DIN standard in Germany in 1922, even today, the paper sizes are called DIN A4 in everyday use in Germany and Austria. The DIN476 standard spread quickly to other countries, by 1977, A4 was the standard letter format in 88 of 148 countries. Today the standard has been adopted by all countries in the world except the United States, in Mexico, Costa Rica, Colombia, Venezuela, Chile, and the Philippines, the US letter format is still in common use, despite their official adoption of the ISO standard
27.
A4 paper size
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ISO216 specifies international standard paper sizes used in most countries in the world today, although not in Canada or the United States. The standard defines the A and B series of sizes, including A4. Two supplementary standards, ISO217 and ISO269, define related paper sizes, all ISO216, ISO217 and ISO269 paper sizes have the same aspect ratio,1, √2, at least to within the rounding to whole numbers of millimetres. This ratio has the property that when cut or folded in half widthwise. Each ISO paper size is one half of the area of the larger size. In 1786, the German scientist Georg Christoph Lichtenberg described the advantages of basing a paper size on a ratio of 2 in a letter to Johann Beckmann. The formats that became ISO paper sizes A2, A3, B3, B4 and they were listed in a 1798 law on taxation of publications that was based in part on page sizes. The main advantage of this system is its scaling, the ISO system of paper sizes exploit these properties of the 2 aspect ratio. In each series of sizes, the largest size is numbered 0, a folded brochure can be made by using a sheet of the next larger size (for example, an A4 sheet is folded in half to make a brochure with size A5 pages. An office photocopier or printer can be designed to reduce a page from A4 to A5 or to enlarge a page from A4 to A3, similarly, two sheets of A4 can be scaled down to fit one A4 sheet without excess empty paper. This system also simplifies calculating the weight paper, under ISO536, papers grammage is defined as a sheets weight in grams per area in square metres. Since an A0 sheet has an area of 1 m2, its weight in grams is the same as its grammage, one can derive the grammage of other sizes by arithmetic division in g/m2. A standard A4 sheet made from 80 g/m2 paper weighs 5 g, thus the weight, and the associated postage rate, can be easily approximated by counting the number of sheets used.414 aspect ratio, rounded to the nearest millimetre. A0 is defined so that it has an area of 1 square metre before rounding. Successive paper sizes in the series are defined by halving the length of the paper size. The most frequently used of this series is the size A4 which is 210 mm ×297 mm, for comparison, the letter paper size commonly used in North America is approximately 6 mm wider and 18 mm shorter than A4. The geometric rationale behind the root of 2 is to maintain the aspect ratio of each subsequent rectangle after cutting or folding an A series sheet in half. The formula that gives the border of the paper size An in metres and without rounding off is the geometric sequence
28.
Basketball
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Basketball is a non-contact team sport played on a rectangular court by two teams of five players each. The objective is to shoot a ball through a hoop 18 inches in diameter and 10 feet high that is mounted to a backboard at each end of the court. The game was invented in 1891 by Dr. James Naismith, a team can score a field goal by shooting the ball through the basket being defended by the opposition team during regular play. A field goal scores three points for the team if the player shoots from behind the three-point line. A team can also score via free throws, which are worth one point, the team with the most points at the end of the game wins, but additional time is mandated when the score is tied at the end of regulation. The ball can be advanced on the court by passing it to a teammate and it is a violation to lift, or drag, ones pivot foot without dribbling the ball, to carry it, or to hold the ball with both hands then resume dribbling. The game has many techniques for displaying skill—ball-handling, shooting, passing, dribbling, dunking, shot-blocking. The point guard directs the on court action of the team, implementing the coachs game plan, Basketball is one of the worlds most popular and widely viewed sports. Outside North America, the top clubs from national leagues qualify to continental championships such as the Euroleague, the FIBA Basketball World Cup attracts the top national teams from around the world. Each continent hosts regional competitions for teams, like EuroBasket. The FIBA Womens Basketball World Cup features the top womens basketball teams from continental championships. The main North American league is the WNBA, whereas the EuroLeague Women has been dominated by teams from the Russian Womens Basketball Premier League, in early December 1891, Canadian Dr. He sought a vigorous indoor game to keep his students occupied, after rejecting other ideas as either too rough or poorly suited to walled-in gymnasiums, he wrote the basic rules and nailed a peach basket onto a 10-foot elevated track. Basketball was originally played with a soccer ball and these laces could cause bounce passes and dribbling to be unpredictable. Eventually a lace-free ball construction method was invented, and this change to the game was endorsed by Naismith, dribbling was not part of the original game except for the bounce pass to teammates. Passing the ball was the means of ball movement. Dribbling was eventually introduced but limited by the shape of early balls. Dribbling only became a part of the game around the 1950s
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Volleyball
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Volleyball is a team sport in which two teams of six players are separated by a net. Each team tries to points by grounding a ball on the other teams court under organized rules. It has been a part of the program of the Summer Olympic Games since 1964. The receiving team must not let the ball be grounded within their court, the team may touch the ball up to 3 times but individual players may not touch the ball twice consecutively. The team that wins the rally is awarded a point, the ball is usually played with the hands or arms, but players can legally strike or push the ball with any part of the body. A number of consistent techniques have evolved in volleyball, including spiking and blocking as well as passing, setting, the game took some of its characteristics from tennis and handball. Another indoor sport, basketball, was catching on in the area, having been invented just ten miles away in the city of Springfield, Massachusetts, only four years before. Mintonette was designed to be a sport, less rough than basketball, for older members of the YMCA. The first rules, written down by William G Morgan, called for a net 6 ft 6 in high, a 25 ft ×50 ft court, and any number of players. A match was composed of nine innings with three serves for each team in each inning, and no limit to the number of contacts for each team before sending the ball to the opponents court. In case of an error, a second try was allowed. Hitting the ball into the net was considered a foul —except in the case of the first-try serve, Volleyball rules were slightly modified by the International YMCA Training School and the game spread around the country to various YMCAs. The first official ball used in volleyball is disputed, some say that Spalding created the first official ball in 1896. In 1917, the game was changed from 21 to 15 points, in 1919, about 16,000 volleyballs were distributed by the American Expeditionary Forces to their troops and allies, which sparked the growth of volleyball in new countries. The first country outside the United States to adopt volleyball was Canada in 1900, an international federation, the Fédération Internationale de Volleyball, was founded in 1947, and the first World Championships were held in 1949 for men and 1952 for women. The sport is now popular in Brazil, in Europe, in Russia, and in countries including China. Beach volleyball, a variation of the played on sand. Volleyball is also a sport at the Paralympics managed by the World Organization Volleyball for Disabled, nudists were early adopters of the game with regular organized play in clubs as early as the late 1920s
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Suburb
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A suburb is a residential area or a mixed use area, either existing as part of a city or urban area or as a separate residential community within commuting distance of a city. In some areas, such as Australia, China, New Zealand, the United Kingdom, and a few U. S. states, new suburbs are routinely annexed by adjacent cities. In others, such as Arabia, Canada, France, and much of the United States, Suburbs first emerged on a large scale in the 19th and 20th centuries as a result of improved rail and road transport, which led to an increase in commuting. Suburbs tend to proliferate around cities that have an abundance of adjacent flat land, the English word is derived from the Old French subburbe, which is in turn derived from the Latin suburbium, formed from sub and urbs. The first recorded usage of the term in English, was made by John Wycliffe in 1380, in Australia and New Zealand, suburbs have become formalised as geographic subdivisions of a city and are used by postal services in addressing. In rural areas in both countries, their equivalents are called localities, the terms inner suburb and outer suburb are used to differentiate between the higher-density suburbs in proximity to the city center, and the lower-density suburbs on the outskirts of the urban area. The term middle suburbs is also used, Suburbs, in this sense, can range from areas that seem more like residential areas of a city proper to areas separated by open countryside from the city centre. In large cities such as London, suburbs include formerly separate towns and villages that have been gradually absorbed during a growth and expansion. In the United States and Canada, suburb can refer either to an residential area of a city or town or to a separate municipality or unincorporated area outside a town or city. The earliest appearance of suburbs coincided with the spread of the first urban settlements, large walled towns tended to be the focus around which smaller villages grew up in a symbiotic relationship with the market town. The word suburbani was first used by the Roman statesman Cicero in reference to the large villas, as populations grew during the Early Modern Period in Europe, urban towns swelled with a steady influx of people from the countryside. In some places, nearby settlements were swallowed up as the city expanded. The peripheral areas on the outskirts of the city were generally inhabited by the very poorest, by the mid-19th century, the first major suburban areas were springing up around London as the city became more overcrowded and unsanitary. A major catalyst in suburban growth came from the opening of the Metropolitan Railway in the 1860s, the line joined the capitals financial heart in the City to what were to become the suburbs of Middlesex. Harrow was reached in 1880, and the line extended as far as Verney Junction in Buckinghamshire, more than 50 miles from Baker Street. Unlike other railway companies, which were required to dispose of surplus land, in 1912, it was suggested that a specially formed company should take over from the Surplus Lands Committee and develop suburban estates near the railway. However, World War I delayed these plans and it was only in 1919, with expectation of a housing boom. The term Metro-land was coined by the Mets marketing department in 1915 when the Guide to the Extension Line became the Metro-land guide and this promoted the land served by the Met for the walker, visitor and later the house-hunter
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Tennis court
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A tennis court is the venue where the sport of tennis is played. It is a rectangular surface with a low net stretched across the center. The same surface can be used to play doubles and singles matches. A variety of surfaces can be used to create a tennis court, Tennis is played on a rectangular flat surface, usually of grass, clay or hard material. The dimensions of a court are defined and regulated by the International Tennis Federation governing body and are written down in the annual Rules of Tennis document. The court is 78 feet long and its width is 27 feet for singles matches and 36 feet for doubles matches. The service line is 21 feet from the net, additional clear space around the court is needed in order for players to reach overrun balls for a total of 60 feet wide and 120 feet long. A net is stretched across the width of the court, parallel with the baselines. The net is 3 feet 6 inches high at the posts, the net posts are 3 feet outside the doubles court on each side or, for a singles net,3 feet outside the singles court on each side. Tennis is played on a variety of surfaces and each surface has its own characteristics which affect the style of the game. There are four types of courts depending on the materials used for the court surface, clay courts, hard courts, grass courts. The Australian Open switched to hard courts in 1988 and in its years the French championship alternated between clay and sand/rubble courts. ITF uses the classification for tennis court surface types, Clay courts are made of crushed shale, stone. The French Open is the only Grand Slam tournament to use clay courts, Clay courts slow down the ball and produce a high bounce in comparison to grass courts or hard courts. For this reason, the court takes away many of the advantages of big serves. Clay courts are cheaper to construct than other types of tennis courts, Clay courts need to be rolled to preserve flatness. The clays water content must be balanced, green courts generally require the courts to be sloped to allow water run-off, Clay courts are more common in Europe and Latin America than in North America and tend to heavily favour baseline players. Grass courts are the fastest type of courts in common use and they consist of grass grown on very hard-packed soil, which adds additional variables, bounces depend on how healthy the grass is, how recently it has been mown, and the wear and tear of recent play
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Olympic-size swimming pool
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An Olympic-size swimming pool is the type of swimming pool used in the Olympic Games, where the race course is 50 metres in length. This is typically referred to as course, distinguishing it from short course which applies to competitions in pools that are 25 metres in length. If touch panels are used in competition, then the distance between touch panels should be either 25 or 50 metres to qualify for FINA recognition and this means that Olympic pools are generally oversized, to accommodate touch panels used in competition. An Olympic-size swimming pool is used as a unit of volume. It is not a definition, as there is no official limit on the depth of an Olympic pool. The value has an order of magnitude of 1 megaliter, FINA specifications for an Olympic-size pool are as follows, There must be two spaces 2.5 m wide outside lanes 1 and 8. The length of 50 metres must be between the pads at the end of each lane, if they are used. If starting blocks are used, then there must be a depth of 1.35 metres from between 1.0 metre from the end of the pool to at least 6.0 metres from the end of the pool. At all other points, the depth is 1.0 metre. If the pool is used for Olympic Games or World Championships, at FINAs 2009 Congress, rules were approved for 10-lane courses for competition, as an alternative to the more traditional 8-lane course. Sport venue List of Olympic-size swimming pools in the United Kingdom List of Olympic-size swimming pools in Ireland List of largest swimming pools
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Acre
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The acre is a unit of land area used in the imperial and US customary systems. It is defined as the area of 1 chain by 1 furlong, lucia, St. Helena, St. Kitts and Nevis, St. Vincent and the Grenadines, Turks and Caicos, the United Kingdom, the United States and the US Virgin Islands. The international symbol of the acre is ac, the most commonly used acre today is the international acre. In the United States both the international acre and the US survey acre are in use, but differ by two parts per million, see below. The most common use of the acre is to measure tracts of land, one international acre is defined as exactly 4,046.8564224 square metres. An acre was defined in the Middle Ages, being the amount of land that could be ploughed in one day with a yoke of oxen. One acre equals 0.0015625 square miles,4,840 square yards,43,560 square feet or about 4,047 square metres. While all modern variants of the acre contain 4,840 square yards, there are definitions of a yard. A square enclosing one acre is approximately 69.57 yards, as a unit of measure, an acre has no prescribed shape, any area of 43,560 square feet is an acre. In the international yard and pound agreement of 1959 the United States, consequently, the international acre is exactly 4,046.8564224 square metres. The US survey acre is about 4,046.872609874252 square metres, its value is based on an inch defined by 1 metre =39.37 inches exactly. Surveyors in the United States use both international and survey feet, and consequently, both varieties of acre. Since the difference between the US survey acre and international acre is only about a quarter of the size of an A4 sheet of paper, areas are seldom measured with sufficient accuracy for the different definitions to be detectable. In India, residential plots are measured in cents or decimal, in Sri Lanka the division of an acre into 160 perches or 4 roods is common. To be more exact, one acre is 90.75 percent of a 100 yards long by 53.33 yards wide American football field, the full field, including the end zones, covers approximately 1.32 acres. For residents of countries, the acre might be envisaged as approximately half of a 105 metres long by 68 metres wide association football pitch. It may also be remembered as 44,000 square feet, in English it was historically spelled aker. The acre was approximately the amount of land tillable by a yoke of oxen in one day and this explains one definition as the area of a rectangle with sides of length one chain and one furlong
. PMID 16055528. Retrieved 2011-09-27.
