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Post by Racer10 on Dec 21, 2006 14:05:33 GMT 9.5
Electron Microscopes Electron microscopes do not use light, and can show objects in much greater detail than any conventional light microscope. The detail is better because electrons are much smaller than light waves, and can be sent and detected with extreme precision. There are several different kinds of electron microscopes. Two of the most frequently used types are transmission electron microscopes and scanning electron microscopes. A transmission electron microscope (TEM) sends electrons through an extremely thin cross-section (slice) of an object and projects an image of the specimen onto a screen. Many organelles (the small structures which make up cells) were discovered with the help of transmission electron microscopes. A scanning electron microscope (SEM) bounces electrons off a solid object in order to generate an image of that object's surface. The object is coated, placed in a vacuum chamber, and electrons are fired at it. The fired electrons "excite" electrons in the coating, causing them to be released. Sensors detect the ejected electrons, and a picture is constructed on a monitor screen. Back to Top
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Post by Racer10 on Dec 21, 2006 14:06:23 GMT 9.5
Evaporated Sea Millions of years ago, the land at what is now the Straits Of Gibraltar rose up, blocking off the connection between the Mediterranean Sea and the Atlantic Ocean. Slowly, the sun did its work, and the Mediterranean Sea evaporated, leaving behind vast layers of salt and a few shallow salt lakes. Geological changes continued at their slow pace. One day about five million years ago, the Atlantic Ocean finally burst through again, and a torrent of seawater began refilling the basin. Centuries later, the Mediterranean Sea was full again. A very similar event happened around 5650 BC at the mouth of what is now the Black Sea. Once a freshwater lake, that body of water is now much larger, containing salt water that flooded in through the Bosporus. Back to Top
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Post by Racer10 on Dec 21, 2006 14:06:54 GMT 9.5
Expanding Lizard When a desert chuckwalla (Sauromalus obesus) is disturbed, it runs into a rock crevice. If the threat persists, it puffs itself up with air, inflating its lungs up to three times their normal volume. It becomes tightly wedged in place, and almost impossible to remove from the rocks. Chuckwallas are large lizards, closely related to iguanas, which can be up to 18 inches (46 centimeters) long. They are herbivores, with a special preference for yellow flowers. They are common in the southwestern US, where their favorite habitat (rocky hillsides) is still relatively undisturbed by humans. Back to Top
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Post by Racer10 on Dec 21, 2006 14:07:59 GMT 9.5
Giant Antlers The largest antlers ever were those of the now extinct Irish elk. Their huge racks grew as large as 3.6 meters (12 feet) across, weighing more than 40 kilograms (88 lbs). Every year, they grew a whole new set from nubs on their heads. These very large deer roamed across the northern hemisphere until about 10,000 years ago, when there was a sudden cold period called the Younger Dryas. When the climate got cold, the forests were replaced by tundra. Recent studies suggest that although the Irish elk were still able to grow their huge antlers during the Younger Dryas, doing so depleted them of calcium and phosphorus. Unable to find enough food to restore themselves, they died out. The largest antlers on living deer are found on the moose. Their antlers can get as large as two meters (over six feet) across. Back to Top
Giant Construction Project There has never been a construction project as massive and expensive as China's Three Gorges Dam. This gigantic dam, which will be sixty stories high and 2.3 kilometers long (1.4 miles), will create a reservoir longer than Lake Superior. Scheduled for completion in 2009, the Three Gorges Dam is expected to cost $27 billion and will generate as much electricity as would 18 nuclear power plants. The massive construction project is also highly controversial, and has generated domestic and international opposition. The reservoir it will create will drown many towns and villages, beautiful valleys, and historic sites. The ecosystem of the Yangtze River downstream of the dam will be permanently changed and some species may become extinct. Back to Top
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Post by Racer10 on Dec 21, 2006 14:08:41 GMT 9.5
Glass Shells Diatoms (Bacillariophyta) are tiny, floating, one-celled life forms that build intricate shells out of silicon dioxide, the compound found in glass, sand, and rock crystal. Their minute shells are beautiful structures with very tiny details, and there are thousands of varieties. The shell of a diatom has two halves called frustules. One of the frustules is slightly larger than the other, and they fit together tightly. Most diatom frustules are decorated with hundreds of tiny holes, grooves, or bumps, arranged in regular patterns. Diatoms have been around for hundreds of millions of years. They are very important to Earth's ecology, producing about a quarter of all the free oxygen in the atmosphere. Although they may seem like plants, they have recently been assigned to a new kingdom, the Chromista, along with some other related life forms. Back to Top
Halogen Light Bulbs Hot-burning "halogen bulbs" can last two or three times longer than regular bulbs because they are filled with chemically active halogen gases that preserve the filament. The filament of an ordinary light bulb burns out because atoms of tungsten evaporate from its surface, so that it becomes thinner and thinner until it breaks. The evaporated tungsten is deposited on the inside surface of the bulb, where it forms a dark deposit. The gas inside a halogen bulb combines with the tungsten atoms that condense on the glass, removing the deposit. When the combined molecules touch the hot filament, the tungsten is redeposited there, and the gas is released to do the same trick again. Halogen bulbs don't last forever, though. Although the filament does not evaporate as fast, it does eventually develop thin spots, and the bulb burns out. Back to Top
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Post by Racer10 on Dec 21, 2006 14:09:28 GMT 9.5
Heavy Ice Ice cubes made out of "heavy water" will not float in ordinary water. Normal water is made of molecules containing one atom of oxygen and two atoms of hydrogen. Both of the hydrogen atoms in heavy water have been replaced by deuterium. An atom of deuterium is different from an atom of hydrogen in that it contains an extra neutron in its nucleus, making the whole atom almost twice as heavy. Normal ice floats in water because its density is lower than that of water -- a result of its more open molecular structure. The extra mass of the deuterium atoms in heavy water adds enough weight that a heavy water ice cube sinks in ordinary water, although it still floats in heavy water. Heavy water is used in nuclear reactors, where it slows down the fast neutrons emitted by the core and carries away the heat created there. Back to Top
Hops in Beer The sharp bite of beer is partly a result of flavor elements that come from the conelike female flower of the hop vine (Humulus lupulus), also known as the "spices" of beer. But hops do much more than add flavor to beer. Brewers began adding hops to beer in the fourteenth century, when it was discovered that not only was the flavor better, but the beer also held its head better (the foam lasted longer) and it was less likely to go bad during the brewing process. Female hops flowers contain glands that produce resins vital to the brewing process. They change the surface tension of the liquid, so the head is firmer, and they also interfere with the growth of undesirable bacteria. Many complex compounds in the hops also contribute to the distinctive flavor of beer. Back to Top
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Post by Racer10 on Dec 21, 2006 14:10:22 GMT 9.5
Human Genome Size You may have heard of the recently completed "human genome project," a monumental project undertaken to decode the entire DNA sequence of a human being (the human genome). Just how big is that sequence? Each human cell contains 46 chromosomes, each of which is a DNA molecule wrapped around proteins called histones. If all the DNA molecules in one cell were unwrapped from the histones and stretched out end-to-end, the total length would be about six feet (2 meters). Almost every cell in your body contains six feet of DNA, wrapped up into a very compact space. If all the information in the human genome were printed in small type, it would fill a thousand thick telephone directories. The whole sequence contains about three billion base pairs (the genetic equivalent of alphabet letters), including some 50,000 - 100,000 genes, each of which codes for a specific protein. Back to Top
Humming Fish In the Pacific Ocean there are fish that make a loud humming sound. Sometimes the sound is so loud that it can be heard by people in boats on the surface. The sound is emitted in the spring and summer by thousands of male midshipman fish, who sit in rocky nests at the bottom. The humming chorus is their way of attracting a mate, but not all male midshipman fish are hummers. There are two kinds. The larger kind are the ones who hum. The smaller ones, who are called "sneaker males," silently sneak into the nests of the hummers, depositing sperm there. When a female midshipman fish visits the nest of a hummer male, she deposits her eggs, which are fertilized by sperm from the hummer male and from any sneaker males who have visited. The hummer male raises the brood, which may include several batches of young at different ages, from eggs deposited by different females. Back to Top
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Post by Racer10 on Dec 21, 2006 14:11:02 GMT 9.5
Insect Sweat If you've ever lived where there are cicadas, you know that these extremely noisy insects make the most racket when it's blistering hot. How do they keep cool while remaining so active in the hot sun? The secret is that cicadas sweat. These finger-long, winged insects have pores through which they secrete a watery liquid derived from the tree sap they drink. While they sing (by vibrating ridged membranes against their bodies), they sweat profusely, thus dissipating the heat of their efforts. Those efforts result in the loudest sounds made by any insect. In Missouri in the summer of 1999, the din reached 85 decibels at some locations, louder than a large diesel truck at full power. Outdoor cafes had to close because the noise was too much for the customers. Back to Top
Largest Eyes The eyes of the giant squid (Architeuthis dux) can be up to 25 centimeters (ten inches) across, about the size of a volleyball. Those large, sensitive eyes are useful in the dark waters where the giant squid lives, 200-700 meters (660-2,300 feet) below the surface of the ocean. Giant squids are among the world's most mysterious megafauna (large animals). So far, no live specimen has been captured. They live in deep oceans all around the world, along with at least ten other species of very large squid. Like other cephalopods such as octopi, giant squids have complex, well-developed brains. They are ferocious predators, but they are also pursued and eaten by large cetaceans such as sperm whales, some of which show the obvious scars of giant squid sucker disks. Back to Top
Largest Star The largest known star is VV Cephei, a "red supergiant" in the constellation Cepheus. VV Cephei's diameter is 17.7 times the size of Earth's orbit. If it were put in the center of our solar system in place of the sun, it would extend almost to the orbit of Saturn, and it would swallow up Mercury, Venus, Earth, Mars, and Jupiter. Like other supergiant stars, VV Cephei is a deep red color. It's also known as the "garnet star." It has a small companion star that circles it every 20.4 years. During one part of its orbit, the companion is hidden for about 1,000 days, and accurate measurement of that time makes it possible to calculate the main star's diameter. VV Cephei is a massive star near the end of its life cycle. Astronomers believe that one day in the next million years or so it will explode into a supernova, releasing vast amounts of energy and leaving behind a tiny but massive black hole or neutron star. Back to Top
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Post by mannhursthurst6 on Mar 3, 2012 18:27:05 GMT 9.5
thousands upon thousands of cars, trucks, SUVs, and motorcycles are seized or repossessed by government law enforcement agencies, the IRS, local law enforcement, and banks from people who can no longer afford the payments or those involved in criminal activities.
There are limited storage facilities for all these vehicles so to save money the government and private companies involved auction them off to recoup some of the money needed for processing and storage. As long as these costs are covered with the sale of the car they don't really care what the final sale price is. In many cases vehicles will start being bid at just a few hundred dollars.
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Post by mannhursthurst6 on Apr 12, 2012 19:48:58 GMT 9.5
The present approach to rainforest cultivation produces wealth for a few, but only for a short time, because farming burned-off tracts of Amazon rainforest seldom works for long. Less than 10 percent of Amazonian soils are suitable for sustained conventional agriculture. However lush they look, rainforests often flourish on such nutrient-poor soils that they are essentially "wet deserts," easier to damage and harder to cultivate than any other soil. Most are exhausted by the time they have produced three or four crops. Many of the thousands of homesteaders who migrated from Brazil's cities to the wilds of the rainforest, responding to the government's call of "land without men for men without land," have already had to abandon their depleted farms and move on, leaving behind fields of baked clay dotted with stagnant pools of polluted water. Experts agree that the path to conservation begins with helping these local residents meet their own daily needs. Because of the infertility of the soil, and the lack of knowledge of sustainable cultivation practices, this type of agriculture strips the soil of nutrients within a few harvests, and the farmers continue to move farther into the rainforest in search of new land. They must be helped and educated to break free of the need to continually clear rainforest in search of fresh, fertile land if the rainforest is to be saved. Printed Clothing, Sports & Lesurewear Indian Stone and Paving Slabs
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