Folding At Home: Fact of the Day Log

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Solid Smoke:

Ever wondered what is the least dense solid in the world? Well, it is the so called Solid Smoke aerogel developed decades ago by aerospace engineers and recently perfected to its newest, lightest formulation by NASA and JPL.

Solid Smoke is made of the same stuff glass is made of: silicon dioxide and sand; however it is more than a thousand times lighter than glass. The latest batch made by NASA/JPL that recently made the Guinness book of records weighed only 0.00011 pounds per cubic inch (3 milligrams per cubic centimeter). Essentially, Solid Smoke is 99.8% air!

Solid Smoke aerogel has some amazing properties unlike any other natural or man-made material. It is extremely durable, has a uniquely low thermal conductivity, refractive index, and sound speed, and can withstand extreme temperatures of up to 2,600 degrees F (1,400 degrees C). These properties make it a great insulator. Experimental samples have been flown on the Space Shuttle, the Mir space station and the Mars Pathfinder; however, in the near future, we may see this material used to insulate our homes, refrigerators, furnaces and car engines. Another amazing property of Solid Smoke is that it can efficiently capture fast-flying particles, such as those entering the Earth's atmosphere or those in the tails of comets. The NASA included a piece of this material on board the Stardust spacecraft which finished collecting interstellar dust, including recently discovered dust streaming into our Solar System from the direction of Sagittarius, on December 13, 2002. These samples will be returned to Earth in 2006 when the scientists will extract them from the Solid Smoke and study them.


Photograph

 

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How does a smoke detector 'know' when there is a fire? Smoke detectors use one of two different methods to do their job, and for both methods the basic operating assumption is the cliche 'where there's smoke there's fire'. Smoke is of course, essential to the operation of a smoke detector, and it is the physical interaction of smoke particles with either light or nuclear radiation that is the basis of a detector operation.

The principle by which an optical smoke detector works can be readily seen by shining a small laser pointer into a foggy sky. Rays of light can only be seen when they shine directly into one's eyes; they can not be seen from the side. The laser however, is clearly visible in the fog. As the light strikes the small suspended droplets of fog some are reflected away at angles to the original path, and these are what makes the beams of light visible from the side. In an optical smoke detector, light travels down a path from an emitter to a detector. This light must pass a tube positioned at right angles to the path that the light must follow. When smoke enters the light path, some of the light bounces off the suspended smoke particles and passes down this tube. It is detected there by a photocell, whose current triggers the alarm sound of the smoke detector.Optical smoke detectors are good, but they can be fairly easily fooled by other air-borne materials, leading to false alarms.

Ionizing smoke detectors use a very small amount of the radioactive element Americium-241 as a source of ionizing radiation. As the atoms of Am-241 break down they emit positively-charged alpha particles. These energetic, charged particles interact with nitrogen and oxygen molecules in the air to produce corresponding ions. The heart of an ionizing smoke detector is a set of electrically charged plates constructed in such a way that this constant flow of ions produces a measurable current. When even a small amount of smoke enters an ionizing smoke detector, the smoke particles interfere with the ionization process, causing an interruption in the flow of ions to the detector plates and a loss of current to the circuit. This loss of current allows another circuit to become active, and when this happens the alarm is sounded.Ionizing smoke detectors are more common than optical smoke detectors. They are not only considerably cheaper to build, but are more sensitive to smoke itself.

 

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How Does The Turtle Get Its Shell?

Many invertebrates, such as beetles and lobsters, have shells, but the turtle is the only living vertebrate with a shell (except for the armadillo or course). A turtle's top shell is called the 'carapace', and the matching bottom shell is called the 'plastron.' How does a turtle get his pair of protective shells? Why he grows them of course!

While still inside the egg, a turtle embryo begins to look different from other vertebrates. Instead of curving around to form the familiar rib cage, the turtle embryo's ribs grow straight out from its backbone to form the oval framework of the carapace. The rest of the carapace is formed from calcified tissue deep in the skin of the back. This hardened layer is called dermal bone, and it grows around and fuses to the framework of ribs.

The lower shell, or plastron, is also made of calcified dermal tissue. The front part of the plastron, under the neck, is formed from the shoulder bones, called clavicles (these are dermal too). The rest of the plastron is made of dermal bone. The picture shows that even before it hatches, a baby turtle has begun to form its shell. When it hatches it will look just like an adult turtle, shell and all, only smaller.

Turtle Embryo

 

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Uses Of Hydrocarbons

The hydrocarbons are the most broadly used organic compounds known, and are quite literally the driving force of western civilization. The greatest amounts of hydrocarbons are used as fuel for combustion, particularly in heating and motor fuel applications. The primary components of natural gas are methane and ethane. We are all familiar with the use of propane in gas barbecues, lanterns, and as a fuel for internal combustion engines and heating systems. Butane is also a readily available fuel, familiar to everyone in the form of the pocket lighter.

With pentane, the saturated hydrocarbons enter the realm of room-temperature liquids. This makes them useful as organic solvents, cleaners, and transport fuels. Gasoline for internal combustion engines in cars, trucks, tractors, lawnmowers, and so on, is rated in combustion properties relative to octane. It is in fact a combination of liquid hydrocarbons ranging from hexanes to decanes. Slightly larger hydrocarbons are known as kerosene or jet fuel, diesel fuel and heating oil. Still larger hydrocarbon molecules serve as lubricating oils, and greases. Eventually a point is reached at which the materials are solids at room temperature. These are the waxes. Hydrocarbon molecules larger than those of the waxes are the heavy greases and the tars commonly used in roofing applications and highway construction.

Most hydrocarbons are generated from the thermal 'cracking' and fractional distillation of crude oil. Another major source is the industrial alteration of ethanol to produce ethylene. The ethylene so produced becomes a feedstock for the industrial synthesis of other hydrocarbons up to and including polyethylene.

 

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Established in 1911 by presidential proclamation, Devils Postpile National Monument protects and preserves the Devils Postpile formation, the 101-foot Rainbow Falls, and the pristine mountain scenery. The Devils Postpile formation is a rare sight in the geologic world and ranks as one of the world's finest examples of columnar basalt. Its columns tower 60-feet high and display an unusual symmetry. Another wonder is in store just downstream from the Postpile at Rainbow Falls, once called 'a gem unique and worthy of its name'. When the sun is overhead, a bright rainbow highlights the spectacular Falls.

Fewer than 100,000 years ago, basalt lava erupted two miles upstream from today's postpile. The lava flowed into the valley and pooled to a depth of 400 feet. The mass of molten lava then began to cool uniformly from top to bottom. As it cooled and contracted, stresses built up in the basalt rock causing it to fracture. Each crack branched when it reached a length of about 10 inches, joining other cracks to form a pattern on the surface of the flow. Under ideal conditions, surface cracks deepened to create the vertical, hexagonal columns you see today. Some 10,000 years ago a glacier flowed down the Middle Fork of the San Joaquin River and overrode the Postpile formation. The moving ice quarried away one side of the postpile, exposing a sheer wall of columns 60 feet high. Evidence of the glacier - the polishing and scratches of glacial ice - remains atop the postpile.

The monument is also a portal to the High Sierra backcountry, with some 75% included in the Ansel Adams Wilderness. At 800 acres, Devils Postpile National Monument may be considered small by some, yet its natural and recreational values abound.

 

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Devils Postpile National Monument Devils Postpile National Monument


Established in 1911 by presidential proclamation, Devils Postpile National Monument protects and preserves the Devils Postpile formation, the 101-foot Rainbow Falls, and the pristine mountain scenery. The Devils Postpile formation is a rare sight in the geologic world and ranks as one of the world's finest examples of columnar basalt. Its columns tower 60-feet high and display an unusual symmetry. Another wonder is in store just downstream from the Postpile at Rainbow Falls, once called 'a gem unique and worthy of its name'. When the sun is overhead, a bright rainbow highlights the spectacular Falls.

Fewer than 100,000 years ago, basalt lava erupted two miles upstream from today's postpile. The lava flowed into the valley and pooled to a depth of 400 feet. The mass of molten lava then began to cool uniformly from top to bottom. As it cooled and contracted, stresses built up in the basalt rock causing it to fracture. Each crack branched when it reached a length of about 10 inches, joining other cracks to form a pattern on the surface of the flow. Under ideal conditions, surface cracks deepened to create the vertical, hexagonal columns you see today. Some 10,000 years ago a glacier flowed down the Middle Fork of the San Joaquin River and overrode the Postpile formation. The moving ice quarried away one side of the postpile, exposing a sheer wall of columns 60 feet high. Evidence of the glacier - the polishing and scratches of glacial ice - remains atop the postpile.

The monument is also a portal to the High Sierra backcountry, with some 75% included in the Ansel Adams Wilderness. At 800 acres, Devils Postpile National Monument may be considered small by some, yet its natural and recreational values abound.

 

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Pluto: The Eighth Planet of Our Solar System


Did I catch you? Pluto is the 9th planet, not the 8th. Right? Depends. Pluto takes 248 years to orbit the Sun. Most of that time Pluto's orbit makes it the 9th planet, outside the orbit of Neptune. But, for 20 years out of each orbit cycle, Pluto's orbit brings it closer to the Sun than Neptune. For those 20 years it becomes the 8th planet. Most recently, Pluto was in 8th place from February, 1979 until February, 1999. Now, it's back in 9th place, and will stay there for the next 200 years.

Pluto is the only planet in our solar system to have this orbital characteristic. This is caused by its very elongated orbital path. Most planets travel around the Sun in an elliptical orbit that is closer in shape to a circle. They pretty much remain the same distance from the Sun during their annual trip. This is true of Neptune. But Pluto's orbital distance from the Sun varies by over 1.86 billion miles (about 3 billion km), enough to cause its orbital anomaly.

Don't worry about Pluto colliding with Neptune though. Pluto's different in that respect as well. Rather than orbiting on a relatively flat plane as the other planets do, Pluto's orbit brings it above and over the orbit of Neptune. Their paths don't cross.

 

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CALIPSO in 2004


From reports of increasing temperatures, thinning mountain glaciers and rising sea level, scientists know that Earth's climate is changing. But the processes behind these changes are not as clear. Two of the biggest uncertainties in understanding and predicting climate change are the effects of clouds and aerosols (airborne particles). The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite mission, currently under development, will help scientists answer significant questions about climatic processes by providing new information on these important atmospheric components.

Scientists use computer programs called climate models to understand the behavior of and make predictions about climate. Climate models are mathematical representations of natural processes. While they are invaluable tools, more scientific studies are necessary to gain a greater confidence in their predictions. Clouds and aerosols are important variables in these models. Researchers need to learn more about how they help cool and warm the Earth, how they interact with each other and how human activities will change them and their effect on the climate in the future. The CALIPSO satellite will give scientists a highly advanced research tool to study the Earth's atmosphere and will provide the international science community with a data set that is essential for a better understanding of the Earths climate. With more confidence in climate model predictions, international and national leaders will be able to make more informed policy decisions about global climate change.

NASA's Langley Research Center in Hampton ,Va., leads and manages CALIPSO for the NASA Earth System Science Pathfinder (ESSP) program and collaborates with the French space agency Centre National d'Etudes Spatiales (CNES), Ball Aerospace and Technologies Corporation, Hampton University and the Institut Pierre Simon Laplace in France. CALIPSO, scheduled for launch in 2004, is designed to operate for three years.

 

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Nature's Exceptions to Our Rules

We all learned in grade school that animals are classified into different categories: Mammals have fur, are warm blooded, give birth to their young and feed their babies milk. Birds have feathers, lay eggs and don't have teeth. Reptiles are cold blooded and lay eggs. Fish have gills and are cold blooded. Seems pretty simple, right?

Well, when you actually go out and look at all of the different animals out there, things get pretty complicated. For example, in what category do you put the platypus? A platypus has a duck-shaped bill that is made of soft leathery skin. It has fur, lays eggs, and has webbed feet. When the young are hatched, milk oozes out if the skin of the mother for the young to eat. The male platypus has one half inch long spurs on each hind leg connected to venom glands. The venom is strong enough to kill a dog. If that isn't enough, consider the echidna or spiny anteater. This animal has a long pointy snout and a sticky tongue to eat ants similar to an anteater, has spiny fur like a porcupine, and develops a pouch for it's young to live in after it's eggs hatch! With all of these anomalies, they both are still considered mammals, and belong to the same sub family called the Monotrens. They are the only animals in this sub family.

Scientists like to categorize all living things, but there always seems to be exceptions to the rule. The platypus and echidna seem to fall into almost all categories, but were defined as mammals because they have fur, are warm blooded and lactate milk.

 

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The Seven Sisters?



The Pleiades cluster, named by the ancient Greeks, is easily seen as a small grouping of stars lying near the shoulder of Taurus, the Bull, in the winter sky. Although it might be expected that the distance to this well-studied cluster would be well established, there has been an ongoing controversy among astronomers about its distance for the past seven years. The mystery began in 1997, when the European Space Agency's satellite Hipparcos measured the distance to the Pleiades and found it is 10 percent closer to Earth than traditional estimates, which were based on comparing the Pleiades to nearby stars. If the Hipparcos measurements were correct, then the stars in the Pleiades are peculiar because they are fainter than Sun-like stars would be at that distance. This finding, if substantiated, would challenge our basic understanding of the structure of stars.

But measurements made by the Hubble telescope's Fine Guidance Sensors show that the distance to the Pleiades is about 440 light-years from Earth, essentially the same as past distance estimates and differing from the Hipparcos results by more than 40 light-years. The new results agree with recent measurements made by astronomers at the California Institute of Technology and NASA's Jet Propulsion Laboratory, both in Pasadena, Calif. Those astronomers used interferometer measurements from Mt. Wilson and Palomar observatories in California, reporting that the star cluster is between 434 and 446 light-years from Earth.

The discrepancy in the distance to the Pleiades is more than an arcane argument over details. Astronomers have only one direct means for gauging distances to stars, called the parallax method. With current telescopes, this method gives accurate results only for distances up to about 500 light-years. Distances beyond that limit must be determined by indirect methods, based on comparing the brightness of distant stars with those of nearer ones of the same type, and making the assumption that both objects have the same intrinsic, or true, brightness. Astronomers can thus build up a distance ladder, based on ever more-distant objects, ultimately leading to the use of supernovae as 'standard candles' for the most distant reaches of the universe.




The Pleiades cluster, named by the ancient Greeks, is easily seen as a small grouping of stars lying near the shoulder of Taurus, the Bull, in the winter sky. Although it might be expected that the distance to this well-studied cluster would be well established, there has been an ongoing controversy among astronomers about its distance for the past seven years. The mystery began in 1997, when the European Space Agency's satellite Hipparcos measured the distance to the Pleiades and found it is 10 percent closer to Earth than traditional estimates, which were based on comparing the Pleiades to nearby stars. If the Hipparcos measurements were correct, then the stars in the Pleiades are peculiar because they are fainter than Sun-like stars would be at that distance. This finding, if substantiated, would challenge our basic understanding of the structure of stars.

But measurements made by the Hubble telescope's Fine Guidance Sensors show that the distance to the Pleiades is about 440 light-years from Earth, essentially the same as past distance estimates and differing from the Hipparcos results by more than 40 light-years. The new results agree with recent measurements made by astronomers at the California Institute of Technology and NASA's Jet Propulsion Laboratory, both in Pasadena, Calif. Those astronomers used interferometer measurements from Mt. Wilson and Palomar observatories in California, reporting that the star cluster is between 434 and 446 light-years from Earth.

The discrepancy in the distance to the Pleiades is more than an arcane argument over details. Astronomers have only one direct means for gauging distances to stars, called the parallax method. With current telescopes, this method gives accurate results only for distances up to about 500 light-years. Distances beyond that limit must be determined by indirect methods, based on comparing the brightness of distant stars with those of nearer ones of the same type, and making the assumption that both objects have the same intrinsic, or true, brightness. Astronomers can thus build up a distance ladder, based on ever more-distant objects, ultimately leading to the use of supernovae as 'standard candles' for the most distant reaches of the universe.


The Seven Sisters Giant Photograph

 

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Introduction To Jupiter (Not Fords Answer to Saturn )

With its numerous moons and several rings, the Jupiter system is a 'mini-solar system.' Jupiter is the most massive planet in our solar system, and in composition it resembles a small star. In fact, if Jupiter had been between fifty and one hundred times more massive, it would have become a star rather than a planet.

At first glance, Jupiter appears striped. These stripes are dark belts and light zones created by strong east-west winds in Jupiter's upper atmosphere. Within these belts and zones are storm systems that have raged for years. The southern hemisphere's Great Red Spot has existed for at least 100 years, and perhaps longer, as Galileo reported seeing a similar feature nearly 400 years ago. Three Earths could fit across the Great Red Spot. Jupiter's core is probably not solid but a dense, hot liquid with a consistency like thick soup. The pressure inside Jupiter may be 30 million times greater than the pressure at Earth's surface.

As Jupiter rotates, a giant magnetic field is generated in its electrically conducting liquid interior. Trapped within Jupiter's magnetosphere - the area in which magnetic field lines encircle the planet from pole to pole - are enough charged particles to make the inner portions of Jupiter's magnetosphere the most deadly radiation environment of any of the planets, both for humans and for electronic equipment. The 'tail' of Jupiter's magnetic field - that portion stretched behind the planet as the solar wind rushes past - has been detected as far as Saturn's orbit. Jupiter's rings and moons are embedded in an intense radiation belt of electrons and ions trapped in the magnetic field. The Jovian magnetosphere, which comprises these particles and fields, balloons one to three extending more than one billion kilometers behind Jupiter - as far as Saturn's orbit.

 

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Leap years are years with 366 days, instead of the usual 365. Leap years are necessary because the actual length of a year is 365.242 days, not 365 days, as commonly stated. Basically, leap years occur every 4 years, and years that are evenly divisible by 4 (2004, for example) have 366 days. This extra day is added to the calendar on February 29th. However, there is one exception to the leap year rule involving century years, like the year 1900. Since the year is slightly less than 365.25 days long, adding an extra day every 4 years results in about 3 extra days being added over a period of 400 years. For this reason, only 1 out of every 4 century years is considered as a leap year. Century years are only considered as leap years if they are evenly divisible by 400. Therefore, 1700, 1800, 1900 were not leap years, and 2100 will not be a leap year. But 1600 and 2000 were leap years, because those year numbers are evenly divisible by 400.

A leap second is a second added to Coordinated Universal Time (UTC) to make it agree with astronomical time to within 0.9 second. UTC is an atomic time scale, based on the performance of atomic clocks. Astronomical time is based on the rate of rotation of the earth. Since atomic clocks are more stable than the rate at which the earth rotates, leap seconds are needed to keep the two time scales in agreement. The first leap second was added on June 30, 1972, and they occur at a rate of slightly less than one per year, on average.

Although it is possible to have a negative leap second (a second removed from UTC), so far, all leap seconds have been positive (a second has been added to UTC). Based on what we know about the earth's rotation, it is unlikely that we will ever have a negative leap second. Leap seconds are needed so that users of the astronomical time scale (UT1) can use UTC and know that the difference between the two time scales is never greater than 0.9 seconds. Currently the difference between UT1 and UTC is changing at a rate of about 2 to 3 milliseconds per day, which makes a leap second necessary at an average interval of slightly more than 1 year. Historically, leap seconds have only been implemented on June 30th or December 31st.

 

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How Much Coffee Will Kill You?

With the spread of Starbucks franchises all the way from Portland to Poughkeepsie, Americans are getting used to paying $3 or more for a proverbial ten-cent beverage. Of course, you get a bigger cup, and what's inside tastes better than sock juice. But it's not just the price, size, and quality of a cup of coffee that are going up. The caffeine content of a 5-ounce cup of American coffee has traditionally been estimated at about 85 mg. Starbucks has declined to post caffeine content for its beverages on its Website, but a 2003 University of Florida Medical School study found that a 16-ounce cup of Starbucks regular brewed coffee had a caffeine content anywhere from 259 mg. to 594 mg. (A 16-ounce Dunkin' Donuts coffee had 143 mg.) A Starbucks spokeswoman provided a figure of 200 mg. per 8 ounces.

Caffeine is an alkaloid, one of a group of bitter-tasting organic compounds including quinine, cocaine, nicotine, and strychnine. All have effects known as 'pharmaceutical': some are poisonous, while others are medically useful as, for example, pain relievers. In moderation, caffeine can serve as a useful motivator. But all alkaloids can be toxic in sufficient quantity, and caffeine is no exception. Overdo it and you'll suffer the effects of caffeine intoxication: irritability, agitation, mental confusion, anxiety, tachycardia (rapid heart beat) and heart arrhythmia.

In rare cases, caffeine intoxication has led to death. How much caffeine will kill you? Fatalities have usually involved quantities on the order of about 10 grams. If you assume 200 mg. caffeine per cup, that translates into 50 cups of coffee drunk all at once. No wonder fatal overdoses are rare. But one recent case in Australia involved a young woman who died after drinking a single can of a health drink containing guarana. Guarana, often sold as a 'natural' herbal ingredient, contains significant quantities of caffeine. The drink, which was subsequently withdrawn from the market, turned out to contain a concentration of caffeine about 60 times the concentration in a cola drink (about 40-50 mg. per 12 ounces).

 

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Red Tide

Red tides occur in oceans. They are not caused by herbicides or pollutants, but by a microscopic alga. Karenia brevis, when in higher than normal concentrations, causes a red tide. This bacterium actually produces toxins within its body, which cause fish to become paralyzed and die. This results in large fish kills on many shorelines. So, why is it called 'red tide'? Well, large blooms or colonies of the algae give off a reddish appearance in the ocean.

Red tides are naturally occurring events. Nothing that humans do can help or stop the red tides. Winds can wash the blooms up on shore leading to the tides. Most red tides occur between August and February. A certain set of environmental conditions must be met to have a red tide. These conditions are not well understood.

Red tides can affect more than just fish. People in the water during a red tide can experience allergy-like symptoms such as eye and throat irritation. When boat propellers send the microscopic algae into the air, they can be breathed in by people on the shoreline, causing the same symptoms. These are known to appear within 24 hours. Filter feeding shellfish, such as oysters, are not affected by the red tides and can be readily eaten. Fish exposed to red tide die from the toxin in Karenia brevis and should not be eaten.

 

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Why does popcorn pop?

Popcorn is the most amazing food! It all starts with a kernel only several millimeters in diameter which explodes into a 40-50 times bigger fluffy, tasty, white wonder. The kernel is made of three parts: the pericarp, the endosperm and the germ. The pericarp is the outer shell, which is air-tight and extremely tough. The endosperm is mostly carbohydrate in the form of starch, with smaller amounts of protein, fat, minerals, and water. The germ is the part that sprouts and is not important in the process of popping.

When you heat a popcorn kernel, water inside (about 13-14% by mass) begins to expand. When the temperature reaches 100 deg C (212 deg F), the water tries to evaporate but the pericarp is so strong that it can't. Instead, pressure begins building inside the kernel just like in a pressure cooker. The pericarp is so strong and air-tight to preserve the water inside the kernel for the germ when it begins sprouting. Some 4,000 year old popcorn kernels discovered in Bat Cave, NM still pop, which means that their pericarp has managed to maintain this water inside for all this time.

As the temperature continues rising, so does the pressure. At approximately 175 deg C (347 deg F) the pressure is as high as 9 atmospheres, and the kernel explodes. If the pericarp has even a tiniest hole in it, the pressure inside the kernel will not be able to build up and it will not pop. The water content is also very important; if the kernel has been dried up (it was left out in the sun or heat for a long time), it will not pop. The expanding water and steam drive the endosperm out. The endosperm starch forms jelly-like bubbles, which quickly dry and solidify into a three-dimensional network - which is the white stuff we like to eat. Mmm ? I am getting hungry now. How about you? Let's pop a bag.

 

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One of the world's most recognizable insects is the ladybug. Ladybugs belong to a family of insects called Coccinellid, with about 5,000 species identified. But this little insect is more than just another pretty face, for the ladybug has been enlisted to fight in the front lines in our eternal war against insect predators. And with a reported 15% of all food and ornamental crops damaged or destroyed by insect pests, we can use all the help we can get.

Biological control is nothing new. For centuries farmers have sought the help of not only ladybugs, but praying mantis, wasps and mites as well. With recent concerns about the overuse of pesticides, there has been a renewed focus on fighting insects with their natural predators. The ladybug is well equipped for the job. In both the larval and adult stages, they prey on many soft-bodied bugs, including aphids and scales.

Like anything else though, you can have too much of a good thing. Nature is a balance, not only on a global, but also on a regional and local level. If the balance is thrown off, unexprected consequences may result. With this in mind, many farmers are using a combination of pesticides and natural insect control. And one of their favorites is the ladybug. Need help getting rid of those aphids? Send in the lady.

 

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SARS, short for Severe Acute Respiratory Syndrome, is big news this spring. By the middle of April 2003, over 2000 people had been diagnosed with it in China and Hong Kong, another few hundred in the rest of Asia, and over a hundred in the US and Canada. Over 100 victims had died.

SARS is a 'new' disease, which feels like a bad case of flu (fever, headache, bad cough). But it's not caused by the flu virus. Scientists aren't sure what causes it, but at present the most likely culprit is a new kind of coronavirus. Well-known coronaviruses cause colds in humans and severe illnesses in cats and dogs, but this is the first to cause severe illness in people. SARS is not the first new disease in recent memory, nor is it the worst. AIDS was first found in humans in the 1980s, and now infects millions. Modern airplane travel makes it easy to spread new diseases to all corners of the world in just a few weeks.

How does a 'new' virus happen? A virus is nothing but DNA in a protein capsule, hardly even worth being called alive. In order to make you sick, it must enter the cells in your body, splice itself into your DNA, and take over running the infected cell, forcing the cell to make more virus copies instead of going about its usual business. At various times in their travels from one host to another, viruses can pick up extra genes, including some that enable them to make people sick (when they couldn't before). This is Mother Nature at work, always coming up with something new!

 

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The Truth About Atomic And Hydrogen Bombs


In the 1930's Enrico Fermi and other scientists studying the properties of radioactive materials observed an interesting phenomenon. They found that the readings taken with a Geiger counter were lower when taken through water than when taken through air. It wasn't immediately obvious what this meant, but soon they realized that the medium of water moderated the radioactive decay process by slowing down the subatomic particles emitted by the radioactive material. This observation eventually allowed the construction of the first 'atomic pile', in which a chain reaction of decaying radioactive nuclei could be maintained in a controlled manner. In a nuclear chain reaction, a particle emitted from one atomic nucleus strikes other nuclei, causing them to split apart and emit particles that in their turn strike other nuclei, and so on in a continuing process.

Without the intervention of a moderating medium, the process can go on in an uncontrolled manner. Each instance of a nucleus splitting apart and emitting a particle releases a certain amount of energy. When the amount of material present is more than a certain threshold quantity, or 'critical mass', so many particles and so much energy are released that the chain reaction runs wild. This is the process of 'nuclear fission' that defines an atomic bomb. The same process, but using a good moderating medium, allows the controlled release and capture of the same energy, which is the basis of the nuclear power generating station. The incident at Chernobyl some years ago stands as a grim reminder of the close kinship between the destructive force of the atomic bomb and the constructive generation of electricity in the nuclear reactor.

In 1953, people watched the testing of the first hydrogen bomb with some fear. For the first time in history, a force was to be purposely unleashed over which man had no control whatsoever and that served no purpose other than destruction. There was a fear that the detonation of that first bomb would also initiate the destruction of the world. This fear was based on the exceedingly small but finite probability that the explosion of this bomb would initiate an unstoppable chain reaction in the most common element in the world: hydrogen. Their fears were perhaps not totally unfounded, as a rumor persists that the energy liberated by that bomb exceeded the very best theoretical calculations by as much as twenty percent, begging the question 'where did it come from?'. And yet, this amazingly destructive force also presents a source of hope for mankind. Research continues to look for a way to harness the incredible power produced by the nuclear fusion process. Success would mean abundant cheap energy for the whole world to use.

 

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Stopping In Thin Air

Imagine you're going very fast -- much faster than a race car. In fact, imagine you're going 100 or 200 times faster than a race car. When you reach your destination, you need to stop relatively quickly. How would you do it? It wouldn't take a rocket scientist to think of using the brakes. But, it might take a rocket scientist to skip the brakes, and use nothing but thin air to slow down.That's the idea behind aerocapture, a technology currently being researched by NASA scientists. While a lot of spaceflight research being performed now deals with better and faster ways of reaching destinations in space, aerocapture is part of a field of research looking at better ways of stopping once you get there.

Traditionally, putting a spacecraft into orbit around another planet or landing a probe has required that the craft carry extra fuel to help it stop once it arrived at its destination. Given the concerns of cost and mass involved in launching a spacecraft, having to carry extra fuel for braking could place some major limitations on proposed science research missions--limiting the amount of scientific equipment that could be carried on some flights and ruling some missions out entirely. Aerocapture is a braking method that requires no extra fuel, but instead involves the use of a planet's atmosphere to slow down a spacecraft. Use of this technique could reduce the typical mass of an interplanetary spacecraft by half or more, allowing for a craft that is smaller and cheaper, but also better equipped to conduct long-term science research at its destination.

NASA researchers are currently developing technologies required to make aerocapture in interplanetary flight a reality, and are considering use of the technique for possible missions to Mars, Neptune, and Saturn's moon Titan. When the research is completed, and if those missions, or others similar to them, are successful, then some of the biggest challenges in interplanetary flight could disappear--into thin air.

Fact Credit:
NASA Aerospace Technology Enterprise

 

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Warmer Hands (And Toes) Through Chemistry


A popular item for skiers and snowboarders, hunters and people who have to work outside in cold areas, and found in many outdoors shops, are disposable hand warmers. If you haven't used them before, you're missing out on a cool way to keep your fingers and toes nice and warm. Warmers come in various shapes and sizes but all work about the same way. One simply rips open the cellophane bag, exposing the warmer to air and -- instant warmth, warmth lasting for hours. Put one in each pocket and keep those fingers from getting numb. They even have ones that fit in the soles of your boots. And some people even use them to combat the aches and pains of arthritis.

A check of the U.S. Patent Office reveals citations to warmers going back all the way to 1924. During the Korean war, Japanese soldiers used the same process to help keep soldiers warm in the bitter cold of the wartime battlefield. Metal canisters with warming powder were shipped to the battlefield where they were mixed with water to generate heat. After the war and after some refinement and product design, Japan became a mass producer of hand warmers. By 1988 they were producing 450 million units annually. So just how do warmers work?

Most warmers work through a simple chemical reaction similar to rusting that occurs when warmers are exposed to air. That is why keeping them under wraps until needed is a must. The warmer is a mixture of iron, water, cellulose, vermiculite, activated carbon and salt. When the iron in the warmer is exposed to oxygen in the air, it oxidizes. In the process of doing so, heat is created. The salt acts as a catalyst and the carbon helps disperse the heat through the warmer. The vermiculite acts as an insulator, keeping the heat from dissipating too rapidly, while the polypropylene helps the air to mix with the ingredients while holding in moisture. The chemical reaction occurs slowly enough to allow the warmer to last for hours. But eventually all the iron is converted to iron oxide and the process stops. So don't expect to see hand warmers replacing central heating anytime soon. But for a cold day, this simple chemical reaction can do the trick.

 

[Googer]

What Is a Spinal Cord Injury?


Although the hard bones of the spinal column protect the soft tissues of the spinal cord, vertebrae can still be broken or dislocated in a variety of ways and cause traumatic injury to the spinal cord. Injuries can occur at any level of the spinal cord. The segment of the cord that is injured, and the severity of the injury, will determine which body functions are compromised or lost. Because the spinal cord acts as the main information pathway between the brain and the rest of the body, a spinal cord injury can have significant physiological consequences. Catastrophic falls, being thrown from a horse or through a windshield, or any kind of physical trauma that crushes and compresses the vertebrae in the neck can cause irreversible damage at the cervical level of the spinal cord and below.

Paralysis of most of the body including the arms and legs, called quadriplegia, is the likely result. Automobile accidents are often responsible for spinal cord damage in the middle back (the thoracic or lumbar area), which can cause paralysis of the lower trunk and lower extremities, called paraplegia. Other kinds of injuries that directly penetrate the spinal cord, such as gunshot or knife wounds, can either completely or partially sever the spinal cord and create life-long disabilities. Most injuries to the spinal cord don't completely sever it. Instead, an injury is more likely to cause fractures and compression of the vertebrae, which then crush and destroy the axons, extensions of nerve cells that carry signals up and down the spinal cord between the brain and the rest of the body. An injury to the spinal cord can damage a few, many, or almost all of these axons. Some injuries will allow almost complete recovery. Others will result in complete paralysis.

Until World War II, a serious spinal cord injury usually meant certain death, or at best a lifetime confined to a wheelchair and an ongoing struggle to survive secondary complications such as breathing problems or blood clots. But today, improved emergency care for people with spinal cord injuries and aggressive treatment and rehabilitation can minimize damage to the nervous system and even restore limited abilities. Advances in research are giving doctors and patients hope that all spinal cord injuries will eventually be repairable. With new surgical techniques and exciting developments in spinal nerve regeneration, the future for spinal cord injury survivors looks brighter every day.

XRAY #1
XRAY #2

 

[Googer]

Mission: Gather Comet Dust; Return To Earth


One of the most imaginative NASA missions of recent years is the Stardust mission. Its main purpose: to gather dust and particles from comet P/Wild 2 and return them to Earth for study. Think about that for a second. We build a spacecraft, send it out past the orbit of Mars, a round trip of over seven years, to rendezvous with a comet only 4 km across, that itself is moving. The spacecraft flies through the comet's tail and uses super gel to collect specks of dust millions of years old, and then it returns to Earth. Wow!

Stardust was launched on February 7, 1999 from Cape Canaveral. It will reach comet P/Wild 2 on January 2, 2004, 2.6 AU from the Earth, and fly as close to it as 93 miles (150 km) at about 4 miles per second (6 km/s) collecting samples. Its trip will end in January, 2006. Scientists are interested in comets because they formed at the same time as the solar system, and their makeup, despite numerous trips around the Sun, is still relatively unchanged from the time of their birth. It may tell scientists about the early universe.

The actual collecting will be done by a blue silica-based substance called aerogel. Aerogel, which means 'air gel', was chosen because it will have almost no interaction with the particles collected and is highly porous. The aerogel, which starts out in a gelatin form is dried onto a disc. The disc is then deployed to collect the samples. Particles are expected to be no larger than a micron in size. After all samples are gathered, the spacecraft will seal the Aerogel disc for its trip through Earth's atmosphere. Then eager scientists, after a six year wait, will have their hands on some comet dust.

Photograph

 

[Googer]

The Self-less Gene?



The dictionary defines altruism as 'an unselfish concern for the welfare of others.' That's the kind of behavior that rescue workers showed in the 9-11 attack on the World Trade Center, and many of those rescuers sacrificed their lives so that the lives of others could be saved. Every culture has altruists. But altruistic behavior has long posed an interesting challenge to evolutionary theorists. How could an 'altruism gene' be passed through the generations if it led to behavior that benefited others at one's own expense? Wouldn't your chances of survival, and of the perpetuation of your genes, be greater if you simply placed priority on your own welfare?

One theory is that altruism can be advantageous as long as you direct it towards the right people, those who share many of your own genes. Your parents, children, and siblings share half your genes on average; your grandchildren and grandparents, one quarter; your cousins, one eighth. Evolution, then, might act according to a relatively simple cost-benefit analysis: as long as the cost to you of your altruistic behavior is less than, say, one half its benefit to your sister, it is advantageous in the sense of resulting in a net gain in the chances of ensuring the perpetuation of your genes. In fact, if the beneficiary also has the gene for altruism, all that matters for the perpetuation of that gene is that its benefit to that person is greater than its cost to you. As far as this kind of algorithm is concerned, it makes no difference whether or not you die in the process. From a genes-eye view, the body that houses it is just a temporary means for replicating itself.

So if people with an altruism gene were selective about behaving altruistically, that right there would enhance the survival value of the gene. You can quickly see another advantage of this selective strategy: if you just help out people who are also cooperative and unselfish, they're more likely to help you out at another time. That results in 'reciprocal altruism' an ethic of 'I'll help you if you help me,' which could hardly be called unselfish. Even altruism, it seems, has to be at least a little self-serving in order to survive.