Genetics is the science of heredity and variation in living organisms.Knowledge that desired characteristics were present at birth has been implicitly used since prehistoric times for improving crop plants and animals through selective breeding. However, the modern science of genetics, which seeks to understand the mechanisms of inheritance, only began with the work of Gregor Mendel in the mid-1800s.
Mendel observed that inheritance is basically a discrete process with specific traits that are inherited in an independant manner. These basic units of inheritance is now known as "genes". In the cells of organisms, genes exist actually in the structure of the molecule DNA and the information genes contain is used to create and control the components of cells. Although genetics plays a large role in determining the appearance and behavior of organisms, it is the interaction of genetics with the environment an organism experiences that determines the ultimate outcome. For example, while genes play a role in determining a person's height, the nutrition and health that person experiences in childhood also have a large effect.
Monday, May 28, 2007
Thursday, May 24, 2007
Mental health
Mental health is a idea that refers to a human individual's emotional and psychological well-being. Merriam-Webster defines mental health as "A state of emotional and psychological well-being in which an individual is able to use his or her cognitive and emotional capabilities, function in society, and meet the ordinary demands of everyday life."
According to the World Health Organization (WHO), there is no one "official" definition of mental health. Cultural differences, subjective assessments, and competing professional theories all affect how "mental health" is defined. In general, most experts agree that "mental health" and "mental illness" are not opposites. In other words, the absence of a recognized mental disorder is not of necessity an indicator of mental health.
One way to think about mental health is by looking at how efficiently and successfully a person functions. Feeling capable and competent; being able to handle normal levels of stress, preserve satisfying relationships, and lead an independent life; and being able to "bounce back," or recover from difficult situations, are all signs of mental health.
Encompassing your emotional, social, and—most importantly—your mental well-being; All these aspects—emotional, physical, and social—must function jointly to achieve overall health.
According to the World Health Organization (WHO), there is no one "official" definition of mental health. Cultural differences, subjective assessments, and competing professional theories all affect how "mental health" is defined. In general, most experts agree that "mental health" and "mental illness" are not opposites. In other words, the absence of a recognized mental disorder is not of necessity an indicator of mental health.
One way to think about mental health is by looking at how efficiently and successfully a person functions. Feeling capable and competent; being able to handle normal levels of stress, preserve satisfying relationships, and lead an independent life; and being able to "bounce back," or recover from difficult situations, are all signs of mental health.
Encompassing your emotional, social, and—most importantly—your mental well-being; All these aspects—emotional, physical, and social—must function jointly to achieve overall health.
Sunday, May 20, 2007
Refrigerator
A typical refrigerator with its door open refrigerator is a cooling machine comprising a thermally insulated compartment and a mechanism to transfer heat from it to the outside environment, cooling the contents to a temperature below ambient. Refrigerators are widely used to store foods which deteriorate at ambient temperatures; spoilage due to bacterial growth and other processes is much slower at low temperatures. Devices described as "refrigerators" maintain a temperature a few degrees above the freezing point of water; similar devices which maintain temperatures below the freezing point of water are called "freezers". The refrigerator is a relatively modern creation amongst kitchen appliances. It replaced the common icebox which had been a household item for almost a century and a half prior, and is sometimes still called by the original name "icebox".
Tuesday, May 15, 2007
Color Television
100 Most television researchers respected the value of color image transmission, with an early patent application in Russia in 1889 for a mechanically-scanned color system showing how early the import of color was realized. John Logie Baird established the world's first color transmission on July 3, 1928, using scanning discs at the transmitting and receiving ends with three spirals of apertures, each spiral with filters of a different primary color; and three light sources at the receiving end, with a commentator to exchange their illumination.
Color television in the United States had a prolonged history due to incompatible technical systems vying for approval by the Federal Communications Commission for commercial use. Mechanically scanned color television was established by Bell Laboratories in June 1929 using three complete systems of photoelectric cells, amplifiers, glow-tubes, and color filters, with a series of mirrors to place over the red, green, and blue images into one full color image.
In the electronically scanned era, the first color television exhibition was on February 5, 1940, when RCA privately showed to members of the FCC at the RCA plant in Camden, New Jersey, a television receiver producing images in color by electronic and optical means without moving device. CBS began non-broadcast color experiments using film as early as August 28, 1940, and live cameras by November 12. The CBS "field sequential" color system was partly mechanical, with a disc made of red, blue, and green filters revolving inside the television camera at 1,200 rpm, and a similar disc spinning in synchronization in front of the cathode ray tube inside the receiver set. The RCA "dot sequential" color system had no moving parts, using a series of diachronic mirrors to separate and direct red, green, and blue light from the subject through three separate lenses into three scanning tubes, and electronic switching that allowed the tubes to send their signals in rotation, dot by dot. These signals were sorted by a second switching device in the receiver set and sent to red, green, and blue picture tubes, and combined by a second set of diachronic mirrors into a full color image.
Color television in the United States had a prolonged history due to incompatible technical systems vying for approval by the Federal Communications Commission for commercial use. Mechanically scanned color television was established by Bell Laboratories in June 1929 using three complete systems of photoelectric cells, amplifiers, glow-tubes, and color filters, with a series of mirrors to place over the red, green, and blue images into one full color image.
In the electronically scanned era, the first color television exhibition was on February 5, 1940, when RCA privately showed to members of the FCC at the RCA plant in Camden, New Jersey, a television receiver producing images in color by electronic and optical means without moving device. CBS began non-broadcast color experiments using film as early as August 28, 1940, and live cameras by November 12. The CBS "field sequential" color system was partly mechanical, with a disc made of red, blue, and green filters revolving inside the television camera at 1,200 rpm, and a similar disc spinning in synchronization in front of the cathode ray tube inside the receiver set. The RCA "dot sequential" color system had no moving parts, using a series of diachronic mirrors to separate and direct red, green, and blue light from the subject through three separate lenses into three scanning tubes, and electronic switching that allowed the tubes to send their signals in rotation, dot by dot. These signals were sorted by a second switching device in the receiver set and sent to red, green, and blue picture tubes, and combined by a second set of diachronic mirrors into a full color image.
Friday, May 11, 2007
Key
A key is a device which is used to open a lock. It typically consists of a specially-shaped piece of flat metal, with cut notches (forming teeth), and/or milled grooves which fit the shape of the lock and can open the properly combinated lock by (usually) being turned in the lock housing. This portion of the key is referred to as the blade. The wider grip, referred to as the bow, is establish at the top of the key to facilitate turning. regularly, there are only a small number of keys which can work a certain lock. In some residential locks, all of the keys for a lock are given to the purchaser of the lock. Duplicates of the key can usually be made by anyone with the correct key blank and key machine. Some manufacturers assign an identification number to each lock and key combination. Knowing the identification number of such a lock allows a duplicate key to be made at certain places. Many residential keys are recognized by the key cuts stamped on the key bow.
Most people in modern society use keys on a daily basis, to secure their home, their vehicle, or to access their workplace, among other uses. Those that use a number of keys will typically place them on a ring or key chain, often with other items such as key fobs.
Most people in modern society use keys on a daily basis, to secure their home, their vehicle, or to access their workplace, among other uses. Those that use a number of keys will typically place them on a ring or key chain, often with other items such as key fobs.
Monday, May 07, 2007
Ancient Tamil gods and goddesses
The religion of the ancient Tamils directly followed Hinduism.although persisting with its roots of nature worship. The most popular deity was Murugan, who has from a very early date been recognized with Karthikeya, the son of Siva. Muruga might have been a different deity at first stemming from a local deity. According to the noted expert on Tamil culture Kamil V. Zvelebil, "Subrahmanya-Murugan is one of the most complicated and baffling deities for analysis". The worship of Amman or Mariamman, consideration to have been derived from Kotravai, an ancient mother goddess, also was very common. Kannagi, the heroine of the Cilappatikaram, was worshipped as Pathini by many Tamils, particularly in Sri Lanka. There were also many temples and devotees of Thirumaal, Siva, Ganapathi, and the other common Hindu deities.
Wednesday, May 02, 2007
Traffic calming
Traffic reassuring is a set of strategies used by urban planners and traffic engineers which aims to slow down traffic and improve safety for pedestrians and bicyclists, although some of these features can also be dangerous to cyclists. It is now relatively common in Europe, especially Northern Europe; less so in North America.
Traffic calming has traditionally been justified on the grounds of pedestrian security and reduction of noise and local air pollution which are side effects of the traffic. However, it has become increasingly apparent that streets have many social and recreational functions which are severely impaired by fast car traffic. For example, residents of streets with light traffic had, on average, three more friends and twice as many acquaintances as the people on streets with heavy traffic which were otherwise similar in dimensions, income, etc. For much of the twentieth century, streets were designed by engineers who were charged only with ensuring traffic flow and not with fostering the other functions of streets. The rationale for traffic calming is now broadening to include designing for these functions.
Displaced traffic is not fully pushed onto other routes, as some travelers may begin to walk or use other modes such as public transit and bicycles to get where they are going. Still, in most cases the affected motorists have few alternatives aside from either navigating the newly erected obstacles or finding a more palatable route. This happens because high traffic tends to be generated by motorists passing through the area and not by the local residents.
It should be noted the some of these measures have a tendency to irritate and annoy drivers rather than calm them and others can actually increase traffic throughput. Some drivers who slow down at calming points, however, accelerate and speed after passing them in order to "catch up for lost time". For this reason, more advanced methods integrated into the design of the street, which make slower speeds seem more natural to drivers and less of an artificial imposition, are now preferred - the goal is to slow down the driver through psychological, at least partly subconscious means instead of simply forcing him to do so.
One major side effect of traffic reassuring is the impedance to emergency services. A police car can easily navigate most traffic reassuring measures. The same cannot be said for fire trucks and ambulances, however. They often have to slow down to safely cross speed bumps or chicanes. In some locales, the law prohibits traffic calming measures along the routes used by the urgent situation services.
There are 3 "E"'s that traffic engineers refer to when discussing traffic reassuring: engineering, education, and enforcement. Because neighborhood traffic management studies have shown that often it is the residents themselves that are largely contributing to the perceived speeding problem within the neighborhood, it is strained that the most effective traffic calming plans will entail all three components, and that engineering measures alone will not produce satisfactory results.
Traffic calming has traditionally been justified on the grounds of pedestrian security and reduction of noise and local air pollution which are side effects of the traffic. However, it has become increasingly apparent that streets have many social and recreational functions which are severely impaired by fast car traffic. For example, residents of streets with light traffic had, on average, three more friends and twice as many acquaintances as the people on streets with heavy traffic which were otherwise similar in dimensions, income, etc. For much of the twentieth century, streets were designed by engineers who were charged only with ensuring traffic flow and not with fostering the other functions of streets. The rationale for traffic calming is now broadening to include designing for these functions.
Displaced traffic is not fully pushed onto other routes, as some travelers may begin to walk or use other modes such as public transit and bicycles to get where they are going. Still, in most cases the affected motorists have few alternatives aside from either navigating the newly erected obstacles or finding a more palatable route. This happens because high traffic tends to be generated by motorists passing through the area and not by the local residents.
It should be noted the some of these measures have a tendency to irritate and annoy drivers rather than calm them and others can actually increase traffic throughput. Some drivers who slow down at calming points, however, accelerate and speed after passing them in order to "catch up for lost time". For this reason, more advanced methods integrated into the design of the street, which make slower speeds seem more natural to drivers and less of an artificial imposition, are now preferred - the goal is to slow down the driver through psychological, at least partly subconscious means instead of simply forcing him to do so.
One major side effect of traffic reassuring is the impedance to emergency services. A police car can easily navigate most traffic reassuring measures. The same cannot be said for fire trucks and ambulances, however. They often have to slow down to safely cross speed bumps or chicanes. In some locales, the law prohibits traffic calming measures along the routes used by the urgent situation services.
There are 3 "E"'s that traffic engineers refer to when discussing traffic reassuring: engineering, education, and enforcement. Because neighborhood traffic management studies have shown that often it is the residents themselves that are largely contributing to the perceived speeding problem within the neighborhood, it is strained that the most effective traffic calming plans will entail all three components, and that engineering measures alone will not produce satisfactory results.
Sunday, April 29, 2007
Lightning
Lightning is an influential natural electrostatic release produced during a thunderstorm. Lightning's abrupt electric release is accompanied by the emission of visible light and other forms of electromagnetic radiation. The electric current passing through the release channels quickly heats and expands the air into plasma, producing acoustic shock waves in the atmosphere.
Early lightning investigate
During early investigations into electricity via Leyden jars and other instruments, a number of people planned that small scale sparks shared some similarity with lightning.
Benjamin Franklin, who also imaginary the lightning rod, endeavored to test this theory by using a spire which was being erected in Philadelphia. Whilst he was waiting for the spire completion some others conducted at Marly in France, what became to be known as the Philadelphia experiments that Franklin had optional in his book?
Franklin typically gets the credit for being the first to perform this research. The Franklin myth goes like this:
Whilst coming up for completion of the spire, he got the idea of using a flying object, such as a kite in its place. During the next shower, in June 1752, he raised a kite, accompanied by his son as an assistant. On his end of the string he emotionally involved a key and tied it to a post with a silk thread. As time passed Franklin noticed the loose fibers on the string stretching out; he then brought his hand close enough to the key and a flash jumped the gap. The rain which had fallen during the storm had covered with water the line and made it conductive.
However, in his memoirs, Franklin obviously states that he only performed this research after those made in France.
As news of the research and its specifics spread, it was met with attempts at duplication. Experiments involving lightning are always risky and commonly fatal. The most well known death during the rash of Franklin-imitators was Professor George Richman, of Saint Petersburg, Russia. He had shaped a setup similar to Franklin's, and was attending a meeting of the Academy of Sciences, when he heard thunder. He ran home with his engraver to capture the event for posterity. While the research was underway, a large ball lightning showed up, collided with Richman's head, and killed him, leaving a red spot. His shoes were blown open, parts of his clothes singed, the engraver knocked out, the doorframe of the room was split, and the door itself ragged off its hinges.
Early lightning investigate
During early investigations into electricity via Leyden jars and other instruments, a number of people planned that small scale sparks shared some similarity with lightning.
Benjamin Franklin, who also imaginary the lightning rod, endeavored to test this theory by using a spire which was being erected in Philadelphia. Whilst he was waiting for the spire completion some others conducted at Marly in France, what became to be known as the Philadelphia experiments that Franklin had optional in his book?
Franklin typically gets the credit for being the first to perform this research. The Franklin myth goes like this:
Whilst coming up for completion of the spire, he got the idea of using a flying object, such as a kite in its place. During the next shower, in June 1752, he raised a kite, accompanied by his son as an assistant. On his end of the string he emotionally involved a key and tied it to a post with a silk thread. As time passed Franklin noticed the loose fibers on the string stretching out; he then brought his hand close enough to the key and a flash jumped the gap. The rain which had fallen during the storm had covered with water the line and made it conductive.
However, in his memoirs, Franklin obviously states that he only performed this research after those made in France.
As news of the research and its specifics spread, it was met with attempts at duplication. Experiments involving lightning are always risky and commonly fatal. The most well known death during the rash of Franklin-imitators was Professor George Richman, of Saint Petersburg, Russia. He had shaped a setup similar to Franklin's, and was attending a meeting of the Academy of Sciences, when he heard thunder. He ran home with his engraver to capture the event for posterity. While the research was underway, a large ball lightning showed up, collided with Richman's head, and killed him, leaving a red spot. His shoes were blown open, parts of his clothes singed, the engraver knocked out, the doorframe of the room was split, and the door itself ragged off its hinges.
Monday, April 23, 2007
Northern Mockingbird
The Northern Mockingbird, Mimus polyglottos, is the mockingbird commonly originate in North America.Adults are grey on the head and upperparts with pale yellow eyes and a slim black bill with a slight downward curve; the underparts are light. They have a long dark tail by means of white edges and long dark legs. They have white wing bars and show white wing patches in flight.Their breeding habitat is areas with a mix of open areas and dense shrubs from southern Canada to Mexico, but is most common in the southern United States. They build a twig nest in a dense shrub or tree. This bird forcefully defends its nest against other birds and animals, including humans. When a predator is persistent mockingbirds from adjacent territories, summoned by a distinct call, may join the attack. Other birds may gather to watch as the mockingbirds harass the intruder.
They are usually permanent residents; northern birds may move south during harsh weather. However, this species has occurred in Europe as an extreme rarity.These birds forage on the ground or in vegetation; they also fly down from a perch to capture food. They mainly eat insects and berries. While foraging they will regularly spread their wings in a peculiar two-step motion to display the white patches underneath. The purpose of this behavior is disputed. Some ornithologists claim this is merely a territorial display, while others say that flashing the white patches startles hiding insects and forces them into the open. Both theories seem to have some merit.
This bird imitates the calls of other birds, animal sounds and yet machine noises. It is often found in urban areas. They often call through the night and may continue year-round apart from for the summer moulting season. Mockingbirds usually sing the loudest in the twilight of the early morning when the sun is on the horizon. While singing on a high perch they will often bolt more than a few feet into the air in a looping motion, with wings outstretched to display their white underside, then land back on the perch without breaking a note. That serves as a territorial display.Mockingbirds have a strong preference for certain trees, such as maple, sweet gum (green 5-pointed leaves and prickly porous balls), and sycamore. They normally avoid pine trees. In urban areas, mockingbirds rarely come down to the ground, unlike most birds. Also, they have a particular preference for high places, such as the topmost branches of trees and the tops of telephone poles.
They are usually permanent residents; northern birds may move south during harsh weather. However, this species has occurred in Europe as an extreme rarity.These birds forage on the ground or in vegetation; they also fly down from a perch to capture food. They mainly eat insects and berries. While foraging they will regularly spread their wings in a peculiar two-step motion to display the white patches underneath. The purpose of this behavior is disputed. Some ornithologists claim this is merely a territorial display, while others say that flashing the white patches startles hiding insects and forces them into the open. Both theories seem to have some merit.
This bird imitates the calls of other birds, animal sounds and yet machine noises. It is often found in urban areas. They often call through the night and may continue year-round apart from for the summer moulting season. Mockingbirds usually sing the loudest in the twilight of the early morning when the sun is on the horizon. While singing on a high perch they will often bolt more than a few feet into the air in a looping motion, with wings outstretched to display their white underside, then land back on the perch without breaking a note. That serves as a territorial display.Mockingbirds have a strong preference for certain trees, such as maple, sweet gum (green 5-pointed leaves and prickly porous balls), and sycamore. They normally avoid pine trees. In urban areas, mockingbirds rarely come down to the ground, unlike most birds. Also, they have a particular preference for high places, such as the topmost branches of trees and the tops of telephone poles.
Wednesday, April 18, 2007
Motorcycle racing
There are a range of sports involving racing motorcycles. FIM is the international sanctioning body for many such events.As motorcycles vary very much in design, there are several different types of motorcycle racing contest, including:Road racing in its purest form is racing on public roads, such as the Isle of Man TT course, the Macau Grand Prix and some courses in Ireland. Due to the inherent dangers that these street venues often carry such as narrow lanes, curbs, and adjacent walls, most road racing is now carried out on purpose-built tracks.Circuit racing where specially designed racing bikes or modified "production" bikes race each other on particularly designed road circuits. MotoGP and Superbike are the top level racing and production classes.Classic Racing is where participants race heavily customized bikes from an earlier era - usually pre mid '70s bikes.
Motocross and its cousin supercross are held on dirt courses, characteristically featuring large jumps in which motorcycles are launched over considerable distances. Supermoto is a crossover motorcycle racing between road racing and motocross. The motorcycles are primarily motocross types with road racing tires. The racetrack is also mixed between road and dirt courses, mostly handcrafted.
Motorcycle speedway and ice speedway are held on oval circuits where riders slide their machines around turns.
Motocross and its cousin supercross are held on dirt courses, characteristically featuring large jumps in which motorcycles are launched over considerable distances. Supermoto is a crossover motorcycle racing between road racing and motocross. The motorcycles are primarily motocross types with road racing tires. The racetrack is also mixed between road and dirt courses, mostly handcrafted.
Motorcycle speedway and ice speedway are held on oval circuits where riders slide their machines around turns.
Monday, April 09, 2007
Radio
Radio is the wireless transmission of signals, by modulation of electromagnetic waves with frequencies below those of light.
Radio waves.Radio waves are a form of electromagnetic radiation, formed whenever a charged object accelerates by a frequency that lies in the radio frequency (RF) portion of the electromagnetic spectrum. This is the variety from a few tens of hertz to a few hundred gigahertz.Electromagnetic radio spectrum
Other types of electromagnetic radiation, with frequencies above the RF range are infrared, visible light, ultraviolet, X-rays and gamma rays. Since the energy of an individual photon of radio frequency is too low to remove an electron from an atom, radio waves are classified as non-ionizing radiation.Radio transmission diagram and electromagnetic waves.Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space equally well, and does not need a medium of transport induces an alternating current and voltage in the conductor. This can be transformed into audio or other signals that carry information. Although the word 'radio' is used to explain this phenomenon, the transmissions which we know as television, radio, radar, and cell phone are all classed as radio frequency emissions.
Radio waves.Radio waves are a form of electromagnetic radiation, formed whenever a charged object accelerates by a frequency that lies in the radio frequency (RF) portion of the electromagnetic spectrum. This is the variety from a few tens of hertz to a few hundred gigahertz.Electromagnetic radio spectrum
Other types of electromagnetic radiation, with frequencies above the RF range are infrared, visible light, ultraviolet, X-rays and gamma rays. Since the energy of an individual photon of radio frequency is too low to remove an electron from an atom, radio waves are classified as non-ionizing radiation.Radio transmission diagram and electromagnetic waves.Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space equally well, and does not need a medium of transport induces an alternating current and voltage in the conductor. This can be transformed into audio or other signals that carry information. Although the word 'radio' is used to explain this phenomenon, the transmissions which we know as television, radio, radar, and cell phone are all classed as radio frequency emissions.
Thursday, April 05, 2007
Transistor
The transistor is a solid state semiconductor device which can be used for amplification, switching, voltage stabilization, signal modulation and many other functions. It acts as a changeable valve which, based on its input current (BJT) or input voltage (FET), allows a precise amount of current to flow through it from the circuit's voltage supply.In essence, a transistor has three terminals. A current or voltage applied through/across two terminals controls a larger current through the other terminal and the common terminal. In analog circuits, transistors are used in amplifiers. Analog circuits include audio amplifiers, stabilised power supplies and radio frequency amplifiers. In digital circuits, transistors function basically as electrical switches. Digital circuits include logic gates, RAM (random access memory) and microprocessors.Transistor was also the common name in the sixties for a transistor radio, a portable radio that used transistors (rather than vacuum tubes) as its active electronic components. This is still one of the dictionary definitions of transistor.
Sunday, April 01, 2007
Sugarcane
Sugarcane or Sugar cane (Saccharum) is a type of between 6–37 species of tall grasses (family Poaceae, tribe Andropogoneae), native to warm temperate to tropical regions of the Old World. They have stout, jointed fibrous stalks 2–6 m tall and sap rich in sugar. All the species interbreed, and the major commercial cultivars are complex hybrids.
Saccharum officinarum grown in Hawaii. There are 13 million hectares (32 million acres) of sugar cane plantations worldwide, with over 100 countries growing the crop. The top twenty producing countries harvested 1200 million metric tons of sugar cane in 2002 (more than 6 times the amount of sugar beet produced). The largest producers are Brazil, India, and China.
Raw sugar has a yellow to brown color. If a white product is preferred, sulfur dioxide may be bubbled through the cane juice prior to evaporation. This bleaches many color-forming impurities into colorless ones. Sugar bleached white by this sulfitation process is called mill white, plantation white or crystal sugar. This form of sugar is the most usually consumed form of sugar in sugarcane-producing countries.
Saccharum officinarum grown in Hawaii. There are 13 million hectares (32 million acres) of sugar cane plantations worldwide, with over 100 countries growing the crop. The top twenty producing countries harvested 1200 million metric tons of sugar cane in 2002 (more than 6 times the amount of sugar beet produced). The largest producers are Brazil, India, and China.
Raw sugar has a yellow to brown color. If a white product is preferred, sulfur dioxide may be bubbled through the cane juice prior to evaporation. This bleaches many color-forming impurities into colorless ones. Sugar bleached white by this sulfitation process is called mill white, plantation white or crystal sugar. This form of sugar is the most usually consumed form of sugar in sugarcane-producing countries.
Tuesday, March 27, 2007
Lens
A lens is a device for either concentrating or diverging light, normally formed from a piece of shaped glass. Analogous devices used with other types of electromagnetic radiation are also called lenses: for instance, a microwave lens can be made from paraffin wax.
The earliest records of lenses date to Ancient Greece, with Aristophanes' play The Clouds (424 BC) mentioning a burning-glass (a convex lens used to focus the sun's rays to produce fire). The writings of Pliny the Elder also show that burning-glasses were recognized to the Roman Empire, and mentions what is possibly the first use of a corrective lens: Nero was known to watch the gladiatorial games throughout a concave-shaped emerald (presumably to correct for myopia). Seneca the Younger (3 BC--65) described the magnifying effect of a glass globe filled with water.Widespread use of lenses did not happen until the invention of spectacles, probably in Italy in the 1280s.
The earliest records of lenses date to Ancient Greece, with Aristophanes' play The Clouds (424 BC) mentioning a burning-glass (a convex lens used to focus the sun's rays to produce fire). The writings of Pliny the Elder also show that burning-glasses were recognized to the Roman Empire, and mentions what is possibly the first use of a corrective lens: Nero was known to watch the gladiatorial games throughout a concave-shaped emerald (presumably to correct for myopia). Seneca the Younger (3 BC--65) described the magnifying effect of a glass globe filled with water.Widespread use of lenses did not happen until the invention of spectacles, probably in Italy in the 1280s.
Thursday, March 22, 2007
Ship
A ship is a large, sea-going watercraft, sometimes with multiple decks. A ship generally has enough size to carry its own boats, such as lifeboats, dinghies, or runabouts. A rule of thumb saying goes: "a boat can fit on a ship, but a ship can't fit on a boat". Often local law and regulation will define the exact size which a boat requires to become a ship. During the age of sail, ship signified a ship-rigged vessel, that is, one with three or more masts, generally three, all square-rigged. Such a vessel would usually have one fore and aft sail on her aftermost mast which was usually the mizzen. Almost invariably she would also have a bowsprit but this was not part of the definition. The same economic pressures which increased sizes to the point of carrying four or five masts, also introduced the fore and aft rig to larger vessels, so few ship-rigged vessels were built with more than three masts. The five-masted Preussen was the outstanding example but the big German ships and barques were built partly for prestige reasons.
Nautical means connected to sailors, particularly customs and practices at sea. Naval is the adjective pertaining to ships though in common usage, it has come to be more mainly associated with the noun 'navy'.
Nautical means connected to sailors, particularly customs and practices at sea. Naval is the adjective pertaining to ships though in common usage, it has come to be more mainly associated with the noun 'navy'.
Friday, March 16, 2007
White flight
White flight is a colloquial term for the demographic tendency of upper and middle class white people moving away from (predominantly non-white) inner cities, finding new homes in nearby suburbs or even moving to new locales completely, e.g. from the Rust Belt to the Sun Belt. In some of the United States' largest cities, the trend reversed itself in the 1990s
White flight in the United States
White flight has been taking place in many American cities and regions, particularly in the Northeastern, Midwestern, and Western sections of the United States since the 1950s.
The effects of white flight have been important for the cities that have been hit by this phenomenon, in particular Detroit, Michigan and St. Louis, Missouri, which lost more than half of their peak populations mainly due to white flight. In New York City many whites have moved from parts of the Bronx and Brooklyn to Staten Island, suburban Long Island, and suburban New Jersey. Other U.S. cities that have been obviously affected by white flight include Philadelphia, Pennsylvania, Cleveland, Ohio, the West and South Sides of Chicago, Illinois, the Greater Los Angeles Area, Baltimore, Maryland, Newark, New Jersey, and numerous smaller cities.
White flight in the United States
White flight has been taking place in many American cities and regions, particularly in the Northeastern, Midwestern, and Western sections of the United States since the 1950s.
The effects of white flight have been important for the cities that have been hit by this phenomenon, in particular Detroit, Michigan and St. Louis, Missouri, which lost more than half of their peak populations mainly due to white flight. In New York City many whites have moved from parts of the Bronx and Brooklyn to Staten Island, suburban Long Island, and suburban New Jersey. Other U.S. cities that have been obviously affected by white flight include Philadelphia, Pennsylvania, Cleveland, Ohio, the West and South Sides of Chicago, Illinois, the Greater Los Angeles Area, Baltimore, Maryland, Newark, New Jersey, and numerous smaller cities.
Monday, March 12, 2007
Quinzhee
A quinzhee, or quinzee, is a kind of snow shelter made by making a pile of snow, waiting for it to settle together, then hollowing out the inside. In difference, an igloo is made by carefully stacking cut blocks of snow.
It is not easy to make a quinzhee, although it will be warmer and stronger if certain techniques are carefully followed. For strength, the quinzhee needs to be a dome and the lower walls must not support too much weight. The walls should be very thick at the base and get slightly thinner towards to the top of the dome.
For warmth, the entrance of the quinzhee should be a tunnel with an upward sloping floor such that the floor is somewhat higher than the top of the entrance.
Caution: Care must be taken when camping conditions are marginal, such as at temperatures near freezing, or when it is raining. Under these conditions the ceiling of the quinzhee may collapse gradually because the snow is soft. Moreover, the entrance tunnel may become too narrow to permit escape. Hence, under these conditions it is unsafe to spend too much time inside the structure because you may become trapped.
It is not easy to make a quinzhee, although it will be warmer and stronger if certain techniques are carefully followed. For strength, the quinzhee needs to be a dome and the lower walls must not support too much weight. The walls should be very thick at the base and get slightly thinner towards to the top of the dome.
For warmth, the entrance of the quinzhee should be a tunnel with an upward sloping floor such that the floor is somewhat higher than the top of the entrance.
Caution: Care must be taken when camping conditions are marginal, such as at temperatures near freezing, or when it is raining. Under these conditions the ceiling of the quinzhee may collapse gradually because the snow is soft. Moreover, the entrance tunnel may become too narrow to permit escape. Hence, under these conditions it is unsafe to spend too much time inside the structure because you may become trapped.
Wednesday, March 07, 2007
Graphic design
Graphic design is a type of communicating visually using text and/or images to present information, or promote a message. The art of graphic design embraces a range of cognitive skills and crafts with typography, image development and page layout. Graphic design is applied in communication design and fine art. Like other forms of communication, graphic design often refers to both the process (designing) by which the communication is created, and the products (designs) such as creative solutions, imagery and multimedia compositions. Graphic design is usually applied to static media, such as books, magazines and brochures. Additionally, since the arrival of computers, graphic design is utilized in electronic media - often referred to as interactive design, or multimedia design.
There are varying degrees of graphic design. Graphic designer participation may range from verbally communicated ideas, to visual rough drafts, to final production. In commercial art, client edits, technical preparation and mass production are generally required, but regularly not considered to be within the scope of graphic design unless the client is also a graphic designer.
There are varying degrees of graphic design. Graphic designer participation may range from verbally communicated ideas, to visual rough drafts, to final production. In commercial art, client edits, technical preparation and mass production are generally required, but regularly not considered to be within the scope of graphic design unless the client is also a graphic designer.
Friday, March 02, 2007
Tourism in New York City
40 million foreign and American tourists visit New York City each year.Major destinations comprise of the Empire State Building, the Statue of Liberty, Broadway productions, scores of museums from the El Museo del Barrio to the Intrepid Sea-Air-Space Museum (closed until 2008 for repairs), Washington Square Park, the Bronx Zoo and New York Botanical Garden, luxury shopping along Fifth and Madison Avenues, and events such as the Halloween Parade in Greenwich Village, the Tribeca Film Festival, and free performances in Central Park at Summer stage. Many of the city's ethnic enclaves, such as Jackson Heights, Flushing, and Brighton Beach are major shopping destinations for first and second generation Americans up and down the East Coast.
New York City has 28,000 acres (113 km²) of parkland and 14 miles (22 km) of public beaches. Manhattan's Central Park, intended by Frederick Law Olmsted and Calvert Vaux, is the most visited city park in the United States.Prospect Park in Brooklyn, also planned by Olmsted and Vaux, has a 90 acre (36 Hectare) meadow. Flushing Meadows Park in Queens, the city's third largest, was the setting for the 1939 World's Fair and 1964 World's Fair.
New York's food culture, influenced by the city's immigrants and large number of dining patrons, is diverse. Jewish and Italian immigrants made the city famous for bagels and New York style pizza. Some 4,000 mobile food vendors approved by the city, many immigrant-owned, have made Middle Eastern foods such as falafels and kebabs standbys of contemporary New York street food.The city is also home to many of the finest haute cuisine restaurants in the United States.
New York City has 28,000 acres (113 km²) of parkland and 14 miles (22 km) of public beaches. Manhattan's Central Park, intended by Frederick Law Olmsted and Calvert Vaux, is the most visited city park in the United States.Prospect Park in Brooklyn, also planned by Olmsted and Vaux, has a 90 acre (36 Hectare) meadow. Flushing Meadows Park in Queens, the city's third largest, was the setting for the 1939 World's Fair and 1964 World's Fair.
New York's food culture, influenced by the city's immigrants and large number of dining patrons, is diverse. Jewish and Italian immigrants made the city famous for bagels and New York style pizza. Some 4,000 mobile food vendors approved by the city, many immigrant-owned, have made Middle Eastern foods such as falafels and kebabs standbys of contemporary New York street food.The city is also home to many of the finest haute cuisine restaurants in the United States.
Monday, February 26, 2007
Space term-In geography
Geographical space is called land, and has a related to ownership. While some cultures assert the rights of the individual in terms of ownership, other cultures will identify with a communal approach to land ownership, while still other cultures, rather than asserting ownership rights to land, invert the relationship and consider that they are in fact owned by the land. Spatial planning is a way of regulating the use of space at land-level, with decisions made at regional, national and international levels. Space can also impact on human and cultural behaviour, being an important factor in architecture, where it will impact on the design of buildings and structures, and on farming.
Ownership of space is not limited to land. Ownership of airspace and of waters is determined internationally. Other forms of ownership have been newly asserted to other spaces — for example to the radio bands of the electromagnetic spectrum or to cyberspace.
Public space is a word used to define areas of land is collectively owned by the community, and managed in their name by delegated establishment. Such spaces are open to all, while private property is the land owned by an individual or company, for their own use and happiness.
Abstract space is a word used in geography to refer to a hypothetical space characterized by complete homogeneity. When modeling movement or behavior, it is a conceptual tool used to limit extraneous variables such as terrain.
Ownership of space is not limited to land. Ownership of airspace and of waters is determined internationally. Other forms of ownership have been newly asserted to other spaces — for example to the radio bands of the electromagnetic spectrum or to cyberspace.
Public space is a word used to define areas of land is collectively owned by the community, and managed in their name by delegated establishment. Such spaces are open to all, while private property is the land owned by an individual or company, for their own use and happiness.
Abstract space is a word used in geography to refer to a hypothetical space characterized by complete homogeneity. When modeling movement or behavior, it is a conceptual tool used to limit extraneous variables such as terrain.
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