A fish is any gill-bearing aquatic vertebrate animal that lacks limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups. Because the term is defined negatively, and excludes the tetrapods which descend from within the same ancestry, it is paraphyletic. The traditional term pisces is considered a typological, but not a phylogenetic classification.
Most fish are "cold-blooded", or ectothermic, allowing their body temperatures to vary as ambient temperatures change. Fish are abundant in most bodies of water. They can be found in nearly all aquatic environments, from high mountain streams to the abyssal and even hadal depths of the deepest oceans . At 32,000 species, fish exhibit greater species diversity than any other class of vertebrates.
Fish, especially as food, are an important resource worldwide. Commercial and subsistence fishers hunt fish in wild fisheries or farm them in ponds or in cages in the ocean . They are also caught by recreational fishers, kept as pets, raised by fishkeepers, and exhibited in public aquaria. Fish have had a role in culture through the ages, serving as deities, religious symbols, and as the subjects of art, books and movies.
The term "fish" most precisely describes any non-tetrapod craniate that has gills throughout life and whose limbs, if any, are in the shape of fins. Unlike groupings such as birds or mammals, fish are not a single clade but a paraphyletic collection of taxa, including hagfishes, lampreys, sharks and rays, ray-finned fish, coelacanths, and lungfish. Indeed, lungfish and coelacanths are closer relatives of tetrapods than of other fish such as ray-finned fish or sharks, so the last common ancestor of all fish is also an ancestor to tetrapods. As paraphyletic groups are no longer recognised in modern systematic biology, the use of the term "fish" as a biological group must be avoided.
Many types of aquatic animals commonly referred to as "fish" are not fish in the sense given above; examples include shellfish, cuttlefish, starfish, crayfish and jellyfish. In earlier times, even biologists did not make a distinction – sixteenth century natural historians classified also seals, whales, amphibians, crocodiles, even hippopotamuses, as well as a host of aquatic invertebrates, as fish. However, according the definition above, all mammals, including Cetaceans like Whales and Dolphins, are not fish. In some contexts, especially in aquaculture, the true fish are referred to as fin fish to distinguish them from these other animals.
A typical fish is ectothermic, has a streamlined body for rapid swimming, extracts oxygen from water using gills or uses an accessory breathing organ to breathe atmospheric oxygen, has two sets of paired fins, usually one or two dorsal fins, an anal fin, and a tail fin, has jaws, has skin that is usually covered with scales, and lays eggs.
Each criterion has exceptions. Tuna, swordfish, and some species of sharks show some warm-blooded adaptations—they can heat their bodies significantly above ambient water temperature. Streamlining and swimming performance varies from fish such as tuna, salmon, and jacks that can cover 10–20 body-lengths per second to species such as eels and rays that swim no more than 0.5 body-lengths per second. Many groups of freshwater fish extract oxygen from the air as well as from the water using a variety of different structures. Lungfish have paired lungs similar to those of tetrapods, gouramis have a structure called the labyrinth organ that performs a similar function, while many catfish, such as Corydoras extract oxygen via the intestine or stomach. Body shape and the arrangement of the fins is highly variable, covering such seemingly un-fishlike forms as seahorses, pufferfish, anglerfish, and gulpers. Similarly, the surface of the skin may be naked, or covered with scales of a variety of different types usually defined as placoid , cosmoid, ganoid, cycloid, and ctenoid . There are even fish that live mostly on land. Mudskippers feed and interact with one another on mudflats and go underwater to hide in their burrows. The catfish Phreatobius cisternarum lives in underground, phreatic habitats, and a relative lives in waterlogged leaf litter.
Fish range in size from the huge 16-metre whale shark to the tiny 8-millimetre stout infantfish.
Tuesday, May 24, 2011
Monday, May 23, 2011
Hot Dogs
A hot dog is a sausage served in a sliced bun. They are commonly garnished with mustard, ketchup, onion, mayonnaise, relish or sauerkraut.
Claims about hot dog invention are difficult to assess, as stories assert the creation of the sausage, the placing of the sausage (or another kind of sausage) on bread or a bun as finger food, the popularization of the existing dish, or the application of the name "hot dog" to a sausage and bun combination most commonly used with ketchup or mustard and sometimes relish.
The word frankfurter comes from Frankfurt, Germany, where pork sausages served in a bun similar to hot dogs originated. These sausages, Frankfurter Würstchen, were known since the 13th century and given to the people on the event of imperial coronations, starting with the coronation of Maximilian II, Holy Roman Emperor as King. Wiener refers to Vienna, Austria, whose German name is "Wien", home to a sausage made of a mixture of pork and beef (cf. Hamburger, whose name also derives from a German-speaking city). Johann Georg Lahner, a 18th/19th century butcher from the Bavarian city of Coburg is said to have brought the Frankfurter Würstchen to Vienna, where he added beef to the mixture and simply called it Frankfurter. Nowadays, in German speaking countries, except Austria, hot dog sausages are called Wiener or Wiener Würstchen (Würstchen means "little sausage"), in differentiation to the original pork only mixture from Frankfurt. In Swiss German, it is called Wienerli, while in Austria the terms Frankfurter or Frankfurter Würstel are used.
Around 1870, on Coney Island, German immigrant Charles Feltman began selling sausages in rolls.
Others have supposedly invented the hot dog. The idea of a hot dog on a bun is ascribed to the wife of a German named Antonoine Feuchtwanger, who sold hot dogs on the streets of St. Louis, Missouri, in 1880, because his customers kept taking the white gloves handed to them for eating without burning their hands. Anton Ludwig Feuchtwanger, a Bavarian sausage seller, is said to have served sausages in rolls at the World's Fair–either the 1893 World's Columbian Exposition in Chicago or the 1904 Louisiana Purchase Exposition in St Louis–again allegedly because the white gloves he gave to customers so that they could eat his hot sausages in comfort began to disappear as souvenirs.
The association between hot dogs and baseball began as early as 1893 with Chris von der Ahe, a German immigrant who owned not only the St. Louis Browns, but also an amusement park.
Harry M Stevens Inc., founded in 1889, serviced major sports venues with hot dogs and other refreshments, making Stevens known as the "King of Sports Concessions" in the US.
In 1916, an employee of Feltman's named Nathan Handwerker was encouraged by celebrity clients Eddie Cantor and Jimmy Durante to go into business in competition with his former employe. Handwerker undercut Feltman's by charging five cents for a hot dog when his former employer was charging ten.
At an earlier time in food regulation the hot dog suspect, Handwerker made sure that men wearing surgeon's smocks were seen eating at Nathan's Famous to reassure potential customers.
Claims about hot dog invention are difficult to assess, as stories assert the creation of the sausage, the placing of the sausage (or another kind of sausage) on bread or a bun as finger food, the popularization of the existing dish, or the application of the name "hot dog" to a sausage and bun combination most commonly used with ketchup or mustard and sometimes relish.
The word frankfurter comes from Frankfurt, Germany, where pork sausages served in a bun similar to hot dogs originated. These sausages, Frankfurter Würstchen, were known since the 13th century and given to the people on the event of imperial coronations, starting with the coronation of Maximilian II, Holy Roman Emperor as King. Wiener refers to Vienna, Austria, whose German name is "Wien", home to a sausage made of a mixture of pork and beef (cf. Hamburger, whose name also derives from a German-speaking city). Johann Georg Lahner, a 18th/19th century butcher from the Bavarian city of Coburg is said to have brought the Frankfurter Würstchen to Vienna, where he added beef to the mixture and simply called it Frankfurter. Nowadays, in German speaking countries, except Austria, hot dog sausages are called Wiener or Wiener Würstchen (Würstchen means "little sausage"), in differentiation to the original pork only mixture from Frankfurt. In Swiss German, it is called Wienerli, while in Austria the terms Frankfurter or Frankfurter Würstel are used.
Around 1870, on Coney Island, German immigrant Charles Feltman began selling sausages in rolls.
Others have supposedly invented the hot dog. The idea of a hot dog on a bun is ascribed to the wife of a German named Antonoine Feuchtwanger, who sold hot dogs on the streets of St. Louis, Missouri, in 1880, because his customers kept taking the white gloves handed to them for eating without burning their hands. Anton Ludwig Feuchtwanger, a Bavarian sausage seller, is said to have served sausages in rolls at the World's Fair–either the 1893 World's Columbian Exposition in Chicago or the 1904 Louisiana Purchase Exposition in St Louis–again allegedly because the white gloves he gave to customers so that they could eat his hot sausages in comfort began to disappear as souvenirs.
The association between hot dogs and baseball began as early as 1893 with Chris von der Ahe, a German immigrant who owned not only the St. Louis Browns, but also an amusement park.
Harry M Stevens Inc., founded in 1889, serviced major sports venues with hot dogs and other refreshments, making Stevens known as the "King of Sports Concessions" in the US.
In 1916, an employee of Feltman's named Nathan Handwerker was encouraged by celebrity clients Eddie Cantor and Jimmy Durante to go into business in competition with his former employe. Handwerker undercut Feltman's by charging five cents for a hot dog when his former employer was charging ten.
At an earlier time in food regulation the hot dog suspect, Handwerker made sure that men wearing surgeon's smocks were seen eating at Nathan's Famous to reassure potential customers.
Wednesday, May 11, 2011
Cube
In geometry, a cube is a three-dimensional solid object bounded by six square faces, facets or sides, with three meeting at each vertex. The cube can also be called a regular hexahedron and is one of the five Platonic solids. It is a special kind of square prism, of rectangular parallelepiped and of trigonal trapezohedron. The cube is dual to the octahedron. It has cubical symmetry (also called octahedral symmetry). It is special by being a Cuboid and a Rhombohedron.
A cube is the three-dimensional case of the more general concept of a hypercube.
It has 11 nets. To colour the cube so that no two adjacent faces have the same colour, one would need at least 3 colours.
If the original cube has edge length 1, its dual octahedron has edge length
For a cube centered at the origin, with edges parallel to the axes and with an edge length of 2, the Cartesian coordinates of the vertices are
As the volume of a cube is the third power of its sides a×a×a, third powers are called cubes, by analogy with squares and second powers.
A cube has the largest volume among cuboids (rectangular boxes) with a given surface area. Also, a cube has the largest volume among cuboids with the same total linear size (length + width + height).
The cube is the cell of the only regular tiling of Euclidean space. It is also unique among the Platonic solids in having faces with an even number of sides and, consequently, it is the only member of that group that is a zonohedron (every face has point symmetry).
The cube can be cut into 6 identical square pyramids. If these square pyramids are then attached to the faces of a second cube, a rhombic dodecahedron is obtained (with pairs of coplanar triangles combined into rhombic faces.)
The analogue of a cube in four-dimensional Euclidean space has a special name—a tesseract or (rarely) hypercube.
The analogue of the cube in n-dimensional Euclidean space is called a hypercube or n-dimensional cube or simply n-cube. It is also called a measure polytope.
There are analogues of the cube in lower dimensions too: a point in dimension 0, a segment in one dimension and a square in two dimensions.
The vertices of a cube can be grouped into two groups of four, each forming a regular tetrahedron; more generally this is referred to as a demicube. These two together form a regular compound, the stella octangula. The intersection of the two forms a regular octahedron. The symmetries of a regular tetrahedron correspond to those of a cube which map each tetrahedron to itself; the other symmetries of the cube map the two to each other.
One such regular tetrahedron has a volume of ⅓ of that of the cube. The remaining space consists of four equal irregular tetrahedra with a volume of 1/6 of that of the cube, each.
The rectified cube is the cuboctahedron. If smaller corners are cut off we get a polyhedron with 6 octagonal faces and 8 triangular ones. In particular we can get regular octagons (truncated cube). The rhombicuboctahedron is obtained by cutting off both corners and edges to the correct amount.
A cube can be inscribed in a dodecahedron so that each vertex of the cube is a vertex of the dodecahedron and each edge is a diagonal of one of the dodecahedron's faces; taking all such cubes gives rise to the regular compound of five cubes.
If two opposite corners of a cube are truncated at the depth of the 3 vertices directly connected to them, an irregular octahedron is obtained. Eight of these irregular octahedra can be attached to the triangular faces of a regular octahedron to obtain the cuboctahedron.
A cube is the three-dimensional case of the more general concept of a hypercube.
It has 11 nets. To colour the cube so that no two adjacent faces have the same colour, one would need at least 3 colours.
If the original cube has edge length 1, its dual octahedron has edge length
For a cube centered at the origin, with edges parallel to the axes and with an edge length of 2, the Cartesian coordinates of the vertices are
- (±1, ±1, ±1)
As the volume of a cube is the third power of its sides a×a×a, third powers are called cubes, by analogy with squares and second powers.
A cube has the largest volume among cuboids (rectangular boxes) with a given surface area. Also, a cube has the largest volume among cuboids with the same total linear size (length + width + height).
The cube is the cell of the only regular tiling of Euclidean space. It is also unique among the Platonic solids in having faces with an even number of sides and, consequently, it is the only member of that group that is a zonohedron (every face has point symmetry).
The cube can be cut into 6 identical square pyramids. If these square pyramids are then attached to the faces of a second cube, a rhombic dodecahedron is obtained (with pairs of coplanar triangles combined into rhombic faces.)
The analogue of a cube in four-dimensional Euclidean space has a special name—a tesseract or (rarely) hypercube.
The analogue of the cube in n-dimensional Euclidean space is called a hypercube or n-dimensional cube or simply n-cube. It is also called a measure polytope.
There are analogues of the cube in lower dimensions too: a point in dimension 0, a segment in one dimension and a square in two dimensions.
The vertices of a cube can be grouped into two groups of four, each forming a regular tetrahedron; more generally this is referred to as a demicube. These two together form a regular compound, the stella octangula. The intersection of the two forms a regular octahedron. The symmetries of a regular tetrahedron correspond to those of a cube which map each tetrahedron to itself; the other symmetries of the cube map the two to each other.
One such regular tetrahedron has a volume of ⅓ of that of the cube. The remaining space consists of four equal irregular tetrahedra with a volume of 1/6 of that of the cube, each.
The rectified cube is the cuboctahedron. If smaller corners are cut off we get a polyhedron with 6 octagonal faces and 8 triangular ones. In particular we can get regular octagons (truncated cube). The rhombicuboctahedron is obtained by cutting off both corners and edges to the correct amount.
A cube can be inscribed in a dodecahedron so that each vertex of the cube is a vertex of the dodecahedron and each edge is a diagonal of one of the dodecahedron's faces; taking all such cubes gives rise to the regular compound of five cubes.
If two opposite corners of a cube are truncated at the depth of the 3 vertices directly connected to them, an irregular octahedron is obtained. Eight of these irregular octahedra can be attached to the triangular faces of a regular octahedron to obtain the cuboctahedron.
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