tag:blogger.com,1999:blog-88522811383375607812024-03-13T12:37:32.524-07:00Science NewsAnonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comBlogger138125tag:blogger.com,1999:blog-8852281138337560781.post-5995987248222178012012-08-01T00:51:00.002-07:002012-08-01T00:51:21.557-07:00Physicist Bends Light Waves On Surfboards<div dir="ltr" style="text-align: left;" trbidi="on">
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<a href="http://1.bp.blogspot.com/-UOVjJoUz6Cw/UBjf2iUvy2I/AAAAAAAAAFs/Kqrtd7K90c8/s1600/Dr+Matt+Lockyear.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="293" src="http://1.bp.blogspot.com/-UOVjJoUz6Cw/UBjf2iUvy2I/AAAAAAAAAFs/Kqrtd7K90c8/s400/Dr+Matt+Lockyear.jpg" width="400" /></a></div>
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Scientists beyond the apple are aggravating to advance
abstracts that can refract ablaze to actualize 'invisibility cloaks', which are
of accurate absorption to the aerospace industry. 'Invisibility cloaking'
agency architecture backdrop into a actual that acquiesce the accessory to
adviser ablaze after-effects about an object, authoritative it invisible.<o:p></o:p></div>
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Dr Matt Lock year grew up in Exeter and completed his
undergraduate Physics amount at the University of Exeter as a complete student.
He alternate for his PhD afterwards alive as an engineering administrator at
BNFL Sell afield, and now works as a Analysis Fellow in the Electromagnetic and
Acoustic Abstracts Accumulation in Physics. His analysis focuses on met
materials: abstracts that abide of accurately engineered 'pseudo-atoms' to
accommodate aggregate actual or interface backdrop that are not begin in nature.<o:p></o:p></div>
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For his work, Dr Lockyear bare to acquisition a actual that
is analogously dense, and in acknowledgment to electromagnetic radiation,
behaves in a agnate way to air. He apparent that the cream central his
surfboards was ideal for his experiments. Luckily, his acquaintance Tris Cokes
owns the Redruth-based surfboard bare accomplishment aggregation Homeblown.
Tris was able to accommodate him with samples of the material, and again lent
him the branch to analysis the loading of the foams with top refractive basis
powders.<o:p></o:p></div>
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Dr Lockyear has afresh congenital what he describes as a
'surface beachcomber atramentous hole' application the surfboard foam. He has
created a amphitheater of actual that has a radially graded basis (the college
the index, the slower the ablaze campaign through the medium), and placed it on
the apparent of a metamaterial. The radiation breeding beyond the metamaterial
is again refracted, ambagious inwards to an arresting core. Dr Lockyear is now
alive on the apparent beachcomber invisibility blind as a dispatch rock to his
accepted analysis project's ultimate goal, a chargeless amplitude 3D
invisibility cloak.<o:p></o:p></div>
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Dr Matt Lockyear said: "I never anticipation I'd be
able to amalgamate my affection for physics with my adulation of surfing --
usually one competes with the other. But the cream central the boards I've been
benumbed for all these years has accepted actually absolute for my research. I
was accepting a altercation with a aide apropos acceptable abstracts for the
activity whilst searching at one of Tris's cream blanks propped up adjoin the
appointment wall, which I had been acceptation to about-face into a 6ft 10
individual fin pintail. I am as well actual advantageous to accept an
appointment adverse the approach guys who, absolutely literally, wrote the book
on transformation optics."<o:p></o:p></div>
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The Electromagnetic and Acoustic Abstracts accumulation
undertakes beat studies with metamaterials and is developing new designs for
radio abundance identification, anti-counterfeiting, and complete proofing
technologies. The group's analysis is primarily congenital about the
development and consecutive abstraction of brownish surfaces with aberrant
backdrop and a ambit of applications.<o:p></o:p></div>
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Dr Lockyear's interests including stealth materials,
light-weight adjustable ultra-thin alarm absorbers, cloaking, axle steering,
acute antennas, cyber banking tagging and abundance careful wallpaper, and of
advance surfing.<o:p></o:p></div>
</div>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-7788744134429164462012-03-29T23:13:00.001-07:002012-03-29T23:13:50.640-07:00Costs of missing sleep<div dir="ltr" style="text-align: left;" trbidi="on"><div class="separator" style="clear: both; text-align: center;"><a href="http://2.bp.blogspot.com/-ByeJBClyeoQ/T3VPDYbct_I/AAAAAAAAAEg/5et3fmEu3IM/s1600/Long-Term-Effects-Resulting-From-Deprivation-Of-Sleep-273x300.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="400" src="http://2.bp.blogspot.com/-ByeJBClyeoQ/T3VPDYbct_I/AAAAAAAAAEg/5et3fmEu3IM/s400/Long-Term-Effects-Resulting-From-Deprivation-Of-Sleep-273x300.jpg" width="364" /></a></div>Not all fruit flies are born equal. Some can skip 12 hours of sleep without missing a beat; others need their beauty rest to keep buzzing. In recent experiments on these two varieties of flies, scientists found that the bugs that skip zzzz’s pay a price to stay awake: They don’t fare as well as well-rested flies when food supplies dwindle.<br />
Scientists often study fruit fly behavior to try to understand how the human brain works. The new fruit fly sleep study may suggest answers to one of the biggest questions among sleep researchers. “That is, ‘What is the core function of sleep?’ ” neuroscientist David Raizen told Science News. Raizen, who did not work on the new experiment, studies the brain and the nervous system at the University of Pennsylvania in Philadelphia.<br />
Genes, chemical features present on chromosomes inside cells, determine many properties of an organism. “Rovers” are fruit flies that can tolerate sleep deprivation, thanks to a change in one of their genes. Among fruit flies, a gene called foraging determines how well the animal can function with little sleep. Scientists refer to another group of fruit flies as “sitters” — insects that need more sleep. The difference in performance of rovers and sitters arises from their hosting different versions of the foraging gene. (Scientists often give fruit fly genes unusual or humorous names; other examples include tinman, maggie, hamlet, hairy and bazooka.)<br />
In the new study, scientists found that rovers could learn new things and keep their memories sharp even after a night without snoozing. The scientists were impressed by the bugs’ abilities. Paul Shaw, a neuroscientist from Washington University in St. Louis who worked on the study, described the insects to Science News as “über-duper super flies.” Sitter flies, on the other hand, had trouble learning if they went a night without sleep.<br />
The tables turned, however, once food entered the picture. When sleep-deprived sitter flies weren’t allowed to eat for 12 hours, their memories improved. Not sleeping made their brains fuzzy — but not eating sharpened their memories. When food was withheld from rovers, the opposite happened: The flies got loopy and were unable to remember. While sitter flies could survive for a few days without food, the rover flies died after 41 hours when deprived of food.<br />
The scientists found that even though rovers could survive sleep deprivation, they had a hard time with food shortages. That balance may explain why both rovers and sitters exist in nature. When food is abundant, rovers may dominate. But in times of shortage, their numbers probably drop off.<br />
Shaw told Science News that there’s a message for people in the fruit fly study. “All of us ‘weak’ people who need eight hours a night might take comfort in the fact that those who claim not to need as much won’t be as resilient to everything,” he said.</div>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-23480893784530865272012-03-07T22:23:00.001-08:002012-03-07T22:23:45.235-08:00Losing control over sugar<div dir="ltr" style="text-align: left;" trbidi="on"><div class="separator" style="clear: both; text-align: center;"><a href="http://2.bp.blogspot.com/-qHob1abmCf4/T1hQWM7kHsI/AAAAAAAAADY/n8uzhHLqWr4/s1600/Losing+control+over+sugar.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="253" src="http://2.bp.blogspot.com/-qHob1abmCf4/T1hQWM7kHsI/AAAAAAAAADY/n8uzhHLqWr4/s400/Losing+control+over+sugar.jpg" width="400" /></a></div> Many sodas contain a sweetener called fructose. Scientists have shown how fructose can cause the body to produce excess amounts of insulin, a hormone used to control sugar in the blood. Credit: Marlith/Wikimedia Commons<br />
Inside your body, sugar goes hand-in-hand with a substance called insulin. A type of hormone, insulin regulates the activity of cells and tissues. It calls the shots after you devour that delicious donut, helping organs pluck a type of sugar called glucose from the bloodstream. When insulin is missing or doesn’t do its job, sugar accumulates in the blood instead of getting into and feeding cells. This throws the body’s balance out of whack, causing a disease called diabetes.<br />
An organ called the pancreas, near the beginning of the large intestine, produces insulin. The more glucose that tickles the pancreas, the more insulin it produces to process the sugar. But new studies show that other things can also cause the pancreas to release insulin. In one study, a sugar called fructose boosted insulin levels; in another, a common pollutant called bisphenol A (BPA) caused the same reaction.<br />
Fructose gives fruit, honey and high-fructose corn syrup their sweetness. Nutritionists — backed by scientific studies — say we eat too much high-fructose corn syrup, found in foods from soft drinks to salad dressing. Scientists working on one of the new studies used human cells, mouse cells and live mice to study what happens when fructose meets the pancreas.<br />
The team found that cells in the pancreas can “taste” the fructose, in a process similar to how the tongue tastes sugar. The study, like many other recent discoveries, shows that taste buds can occur — and taste chemicals — far from the tongue. Fructose alone didn’t boost insulin levels. But in the study, when glucose and fructose appeared together, the pancreas produced more insulin than it did when it encountered glucose alone.<br />
“The system seems to be elegantly made to keep a balance,” Björn Tyrberg told Science News. Tyrberg, who led the new work, studies the biology of cells at Sanford-Burnham Medical Research Institute in Orlando, Fla.<br />
The body may have a hard time keeping that balance in the presence of BPA, too. This chemical, commonly found in plastics and cash register receipts, can imitate a hormone called estrogen. One of estrogen’s jobs is to keep track of insulin, telling the pancreas to produce more if it is needed.<br />
In the second new study, scientists found that BPA, like estrogen, can trigger insulin production. But because BPA is a pollutant, it stimulates the pancreas to create insulin when it’s not needed. The researchers also demonstrated that it doesn’t take much BPA to get the pancreas to pump out extra insulin. BPA and fructose may be radically different compounds, but both can throw off the body’s balance in similar ways.<br />
Angel Nadal of Miguel Hernández University in Elche, Spain, led the BPA study. He told Science News that extra insulin in the blood may cause other tissues to start ignoring this important hormone. Called “insulin resistance,” this condition can lead to the buildup of glucose in the blood indicative of type 2 diabetes. In experiments by Nadal and his colleagues, animals exposed to BPA ended up with insulin resistance more often than other animals did. Nadal thinks that BPA in the body may speed up the onset of type 2 diabetes in people with a family history of the disease.<br />
Franck Mauvais-Jarvis of Northwestern University’s Feinberg School of Medicine in Chicago told Science News that he doesn’t think BPA alone can cause diabetes. Lots of different chemicals can throw off the body’s balance. He says, “I suspect it’s a cocktail of these nasties” that can make a person more likely to develop the disease.<br />
<b>pancreas</b> A large gland located behind the stomach. It secretes digestive enzymes (proteins that stimulate or speed up chemical reactions) into the intestines. It also secretes the hormone insulin into the blood.<br />
<b>insulin</b> A hormone produced in the pancreas. It regulates the amount of glucose in the blood. A lack of insulin or a loss in the body’s responsiveness to it can both cause diabetes.<br />
<b>fructose</b> A simple sugar found in honey and fruit and the sugar that makes up half of each molecule of sucrose, or table sugar.<br />
<b>glucose</b> A simple sugar that is an important energy source in living organisms and a component of many carbohydrates. It also makes up half of each molecule of sucrose, or table sugar.<br />
<b>hormone</b> A regulatory substance produced in an organism and transported in tissue fluids such as blood to stimulate the activity of specific cells or tissues.</div>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-83578163739430909162012-01-22T15:21:00.000-08:002012-01-22T15:21:00.638-08:00Bloodsuckers get out of bed<P></P><br /><P>This story is being written by a person sitting in a bathtub. It doesn’t have water in it, because the person is fully dressed and typing on a laptop computer. This isn’t the most convenient place to work, with a file folder of notes propped on a soap dish and awkward conversations when someone else in the house thumps on the door and asks what’s taking so long.</P><br /><P>Bathtubs, however, are very comforting for people writing about tiny, crawling bugs that suck blood. After reading about bugs with needlelike mouthparts that stick into a person’s arm unnoticed (at first, before the itching starts), it’s easy to wonder if that little tickle was a bug tiptoeing on your neck. Or just over and under your sock. A bathtub doesn’t have a lot of places for bugs to hide. A person starting to scratch and twitch can just stand up and look at all the smooth white surfaces to check for anything dark and crawling. That’s why I’ve chosen a bathtub as a place to write about bedbugs, also known as Cimex lectularius</EM>.</P><br /><P>These insects had become rare in many parts of the world starting in the middle of the last century. That’s when powerful pesticides — or chemicals for killing pests — first came into widespread use. But bedbugs in just a few years developed ways to resist being killed by one of the more widely used early pesticides, DDT. Over more generations, the bugs developed ways to resist other pesticides. And so in the 1990s, bedbugs began to reemerge as a major scourge, and not just in the United States. They also began busting out as a big problem in Europe, Australia and parts of Asia.</P><br /><P>Bedbugs don’t kill people or — as far as we know — directly transmit diseases. In 2011, a scientific paper raised questions about whether bedbugs might transmit infections. Tests in Vancouver, Canada, found the bugs carry two kinds of harmful bacteria, nicknamed MRSA and VRE. These germs can cause deep, oozing sores and other infections that very few drugs will treat.</P> A grown-up bedbug (shown close up, thankfully) draws blood through its tubelike mouth. Still only about the size of an apple seed, adults are easy to overlook when they hide in mattress seams or slip into electrical outlets. Credit: Piotr Naskrecki<br /><P></P><br /><P>But a lot of people already have those bacteria on their skin. So it’s not clear whether bedbugs increase human infections with MRSA and VRE, points out Jody Gangloff-Kaufmann of Cornell University. She works on Long Island in New York.</P><br /><P><STRONG>Tiny bugs, big problems</STRONG></P><br /><P>Gangloff-Kaufmann specializes in insects common in towns and cities. Because bedbugs were rare when she was a kid, she had no experience with them. So to prepare for working with the returning menace, she found bedbugs and intentionally let them bite her.</P><br /><P>Even if bedbugs don’t increase infections, their bites are not fun, she notes. The insects spend the day clustered in small, dark crevices, such as the seams in a mattress or grooves in a bed’s wooden headboard. In the dark, they hike out, covering perhaps the length of a room, to stick those needlelike mouthparts into flesh for a good, warm drink. The bite doesn’t sting like a bee’s. Quite the opposite. A sleeping person usually keeps on sleeping while the bug slurps.</P><br /><P>The trouble comes from the bedbug’s spit. While feeding, some of the bug’s spit enters the little hole pierced into a person’s skin. Many people are allergic to several substances in the spit. So bites can swell into red bumps, often in clusters that can look like a spotty rash, and itch insanely.</P><br /><P>The problems don’t end there. Bites themselves may become infected, especially if the sufferer scratches the bump open. People can lose sleep and grow miserable and anxious in their own homes. Also, friends and family may avoid visiting the homes of bedbug sufferers for fear of picking up the bugs. And like many allergies, somebody’s response to bedbug bites tends to grow stronger with repeated bites. Gangloff-Kaufmann, for example, says that her first bite took days to swell into a slight bump. People who have been bitten often may start itching within hours.</P> The long sharp tube (colored purple in the magnified photo) on a bedbug’s mouth can stab sleeping people without waking them up. By the time people start to feel the itching caused by a bite, the bedbug has usually crawled away. Credit: Janice Haney Carr<br /><P></P><br /><P>“Bedbugs are not everywhere, but they can be anywhere,” Gangloff-Kaufmann says. The bugs can squeeze through very tiny cracks, which explains why pest control workers have discovered them in such places as a stereo, TV remote, clock radio — even in the chink in the bricks of a fireplace. In the past few years, reports have emerged of bedbugs having moved into hotels, movie theaters, ambulances, hospitals, college dormitories, airport lounges, clothing stores, government office buildings and lots of other places.</P><br /><P><STRONG>A blood-only diet</STRONG></P><br /><P>Bedbugs feed on more than just humans. On chicken farms, bedbugs attack chickens. Special species of the insects lurk where bats sleep. Other bedbugs thrive in the bird cities that cliff swallows build. Bedbugs don’t need beds. They just need blood.</P> A close-up of the frame of a lounge chair shows bedbugs of various ages and their dark poop spots and cast-off exoskeletons. The straight bars are staples. Credit: louento.pix/flickr<br /><P></P><br /><P>Not all blood-eating insects need all blood, all the time. Among mosquitoes, for example, blood is for females only. Males don’t touch the stuff, relying on other classic insect foods, such as nectar sipped from flowers. Bedbugs, however, really do live the vampire lifestyle. For them it’s blood and nothing else.</P><br /><P>A bedbug hatchling right out of the egg needs at least one hearty, warm, red meal to make it to the next stage of growth. As bedbugs reach adulthood and become about the size and color of an apple seed, they still need blood. A blood meal allows a bedbug to graduate to its next phase of life. For example, before mating, both males and females feed on blood to build up their strength.</P><br /><P>But these insects can survive a long time between meals. Just how long depends on the conditions. A study from the 1940s found that bedbugs lived up to 18 months with no blood in a cool (45 degrees Fahrenheit), humid place, but only about six months at 73º F. Experiments with modern bedbugs suggest they may not be as tough.</P><br /><P>The need for blood presents a puzzle for scientists who keep bedbugs in the lab to study. Stephen Kells, from the University of Minnesota in St. Paul, says that it took about a year for his lab to figure out how to get the insects to eat reliably. During one tough period when progress seemed to have stalled, one of Kells’ collaborators kept hope and the bugs alive by letting them bite him. Fortunately, the researchers worked out a less-painful system: feeding the insects human blood from blood banks.</P><br /><P>Harold Harlan, a retired military expert on the pests, kept his bugs alive by letting them bite him regularly for decades. He explains that he couldn’t find other volunteers, and his wife would have been too upset if he’d used their dog.</P><br /><P><STRONG>Battling the bloodsuckers</STRONG></P><br /><P>Researchers are starting to look at the tough problem of how to control bedbugs — both inside labs and homes. Pyrethroids, the main group of pesticides considered okay to use against bedbugs in people’s houses, no longer reliably kill these pests. Researchers at Ohio State University and elsewhere are now studying bedbugs’ DNA, a long molecule that carries genetic information and is found in nearly every cell of every living organism. The scientists are looking for genetic changes that have allowed the bugs to become immune to these poisons.</P><br /><P>With pesticides looking like an iffy solution, other researchers are trying to understand the world as bedbugs smell and taste it. This work, the scientists hope, might someday pinpoint chemicals that could improve bug traps or suggest other tricks for fighting back.</P> A pair of bedbugs in the act of mating has been flipped upside down to show the male’s position. He does not bother finding the opening to the tube in the female’s body that leads to her reproductive parts. Instead he just punches through her outer body covering. In bedbugs this method actually works. Credit: Rickard Ignell/Swedish University of Agricultural Sciences<br /><P></P><br /><P>Bedbugs find people in part by sniffing them — and the carbon dioxide that people breathe out appears to strongly attract the bugs. The insects also respond to human skin scents detected from more than twice a human arm’s length away. Whiffs of skin oils or earwax seem to be bug versions of “Mmm, what’s for dinner?” scents. The smell of human perspiration doesn’t appeal, though. Nor, oddly enough, does the smell of plain human blood, either fresh or dried.</P><br /><P>Bedbugs make their own chemicals, including some that draw the bugs together in their daytime hideaways. Researchers have also found a compound that males release if another male grabs them and tries to mate. It’s sort of a “Whoa, there, I’m a guy too” signal. It comes in handy, as male bedbugs do seem to grab anything that’s the right size and moving.</P><br /><P>Being grabbed by a male bedbug in a hopeful frame of mind looks like something not to take lightly. Males don’t look for a natural opening in the female’s body to insert sperm, their reproductive cells. Instead, males just use a sharp structure to punch a new hole through the female’s body wall. Luckily for bedbugs, the sperm do eventually manage to find their way to a female’s eggs.</P><br /><P><STRONG>Banishing bedbugs</STRONG></P><br /><P>For now, ridding one’s home of bedbugs is quite challenging. Treatments can involve heating all belongings, throwing away possessions that can’t be treated, steaming fabric surfaces and even heating whole rooms. So the best way to protect your own bed (or alarm clock or TV remote) is to learn what the bugs look like and check mattresses, sofas and fabric-covered chairs in homes, hotels and dormitories where you stay. Sometimes the easiest signs of these invaders are blood smears on sheets or the tiny black stains left by their poop.</P><br /><P>And bedbug specialists cringe at the idea of even thinking about adopting furniture or electronics left out on curbs for free. Gangloff-Kaufmann has taught her young son to shout “bedbugs” whenever they drive by any such temptation. True, it’s creepy to think about bedbugs so much, but watching for them is the best defense.</P><br /><P>And if that starts to creep you out, consider a nice sit in a dry tub to calm your nerves.</P><br /><P>POWER WORDS</P><br /><P><STRONG>Pesticide:</STRONG> A poison for killing some kind of pest, such as bedbugs or disease-carrying mosquitoes.</P><br /><P><STRONG>Pesticide resistance:</STRONG> The power to live through being sprayed or treated with pesticides.</P><br /><P><STRONG>Pheromone:</STRONG> A chemical made by an animal. Pheromones drift through the air and send messages to other animals, saying such things as “danger” or “I’m looking for a mate.”</P><br /><P><STRONG>Carbon dioxide:</STRONG> A colorless, odorless gas produced by burning carbon and organic compounds and by breathing. It is naturally present in air and is absorbed by plants in photosynthesis.</P><br /><P><STRONG>Scourge:</STRONG> Something that causes pain or unhappiness.</P><br /><P><STRONG>DNA, or deoxyribonucleic acid: </STRONG>A long molecule in nearly all living organisms that carries genetic information. Each molecule of DNA consists of two strands coiled around each other to form a double helix, a structure like a twisted ladder.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-52356328945370906882012-01-22T10:43:00.000-08:002012-01-22T10:43:00.131-08:00Distant ‘Goldilocks’ world Astronomers have discovered a small planet outside the solar system with a temperature that could be — but probably isn’t — hospitable to alien life. E.T., keep dialing. This is an artist’s interpretation of how the planet, called Kepler-22b, may appear. Credit: NASA, Ames, JPL-Caltech<br /><P></P><br /><P>On December 5, astronomers introduced a newly discovered planet that seemed habitable for extraterrestrial life. The faraway world is an exoplanet, or planet outside our solar system, called Kepler-22b. It looks E.T.-friendly because its temperature is neither too hot nor too cold for liquid water, which is essential to life as we know it. The planet orbits its star at just the right distance, sometimes called the “Goldilocks” zone.</P><br /><P>Early studies suggested that the average temperature on the new planet hovers around 72 degrees Fahrenheit, room temperature for many places on Earth. Kepler-22b’s host star is a bit cooler than the sun, and the planet’s 290-day year is a bit shorter than Earth’s. This news left the scientific world abuzz.</P><br /><P>“It’s a great gift,” space scientist Bill Borucki said at the conference introducing the planet. “We consider this sort of our Christmas planet.” Borucki works at NASA’s Ames Research Center, where he leads a team of scientists who look for planets using the Kepler Space Telescope.</P><br /><P>Using this telescope’s data, scientists found that the planet’s radius is about 2.4 times Earth’s. (Radius is the distance from a sphere’s surface to its center.) That means Kepler-22b is larger than our planet but much smaller than giants like Jupiter and Saturn. Scientists don’t yet know if the planet is rocky, like Earth and Mars, or gassy, like Neptune and Uranus.</P><br /><P>It didn’t take long after the discovery for other scientists to weigh in with doubts about the planet’s ability to support life. Planetary scientist Abel Mendez at the University of Puerto Rico in Arecibo studies and keeps track of possibly habitable planets. He told Science News </EM>that Kepler-22b doesn’t look promising.</P><br /><P>Using data relayed from the space telescope, Mendez and his colleagues tested different possible combinations of size and mass for the planet. Mass is a measure of how much stuff is in an object. On Earth, objects with more mass weigh more. The scientists hoped to use mass as an indication of whether Kepler-22b might be even remotely Earthlike, and therefore able to support life.</P><br /><P>Mendez thinks the new planet might support life if it were covered with water on its surface, like a giant ocean planet. But even then the chance of life is low, based on his team’s findings. “I’m not optimistic,” he said. “But I would love to be wrong.”</P><br /><P>Sara Seager is a planet-hunting astronomer at the Massachusetts Institute of Technology in Cambridge. She told Science News</EM> that if the planet has an atmosphere, it should be hot and steamy and “too hot at the surface for life to survive.” Seager suspects the planet is gassy, like a miniature version of Neptune.</P><br /><P>It’s still possible that the planet is rocky and surrounded by a thin atmosphere — or somewhat Earthlike. Scientists can’t know that, however, without further observations. But if Kepler-22b isn’t hospitable for E.T. or other life forms, that would be all right, too. Scientists have identified more than 2,000 possible planets using the new telescope’s data. Each planet has to be confirmed by follow-up studies, and 22b has already passed that second test. Perhaps another, more Earthlike planet is just waiting in the data.</P><br /><P>Scientist Natalie Batalha from San Jose State University in California works on the Kepler telescope mission. She told Science News</EM> that of the thousands of potential planets just identified, hundreds might be small. “Not only do we have Earth-size planets, we have planets that are significantly smaller than Earth.</P><br /><P>POWER WORDS (adapted from the New Oxford American Dictionary)</P><br /><P><STRONG>exoplanet </STRONG>A planet that orbits a star outside the solar system.</P><br /><P><STRONG>mass </STRONG>The quantity of matter that a body contains.</P><br /><P><STRONG>radius </STRONG>A straight line from the center to the circumference of a circle or sphere.</P><br /><P><STRONG>atmosphere </STRONG>The envelope of gases surrounding a planet.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-71541192161016695762012-01-22T06:11:00.000-08:002012-01-22T06:11:00.486-08:00Electronic skin<P></P><br /><P>James Bond and his enemies would be interested in the goings-on at the laboratory of John Rogers. So would Batman, the Spy Kids, Darth Vader and their enemies. That’s because Rogers, a materials scientist at the University of Illinois at Urbana-Champaign, mixes electronics with the human body to create new devices not found even in science fiction.</P><br /><P>Make room, Lord Vader. There’s a new kind of cyborg in town.</P><br /><P>Rogers and his collaborators have built an electronic device that’s smaller than a postage stamp and sticks to the skin like a temporary tattoo. The device’s possible users — patients, athletes, doctors, secret agents, you — are limited only by their imaginations.</P><br /><P>Placed on a forehead, the device can record brainwaves; on the wrist, blood flow and muscle movement. On the skin of sick patients, it can track vital signs and watch for problems, replacing the bulky equipment usually found in hospitals. And stuck to the throat, it can function as a secret cell phone, activated by the movements of a person’s voice box.</P><br /><P>The scientists designed the device, about half as thick as an ordinary sheet of paper, with skin in mind. Like skin, the electronic material can be stretched and squashed in many ways but keep on working.</P> These skin-stuck devices mimic the properties of skin, which means they can stand up to poking, stretching and squeezing. Credit: Image courtesy John A. Rogers<br /><P></P><br /><P>Scientists who design devices for the body have to study how it functions, down to a tiny, cellular level.<STRONG> </STRONG>The body and the machine have to speak the same language.<STRONG> </STRONG>“We wanted to build devices that interact with the body,” Rogers says.<STRONG> </STRONG></P><br /><P>Last fall, Rogers and his colleagues demonstrated how their new device measures the body in different ways. The invention can record temperature, muscle motion or the electrical activity on a person’s skin. It may be outfitted with lights and a tiny power source, which means it can wirelessly transmit data to a nearby computer. This device may even change the way we think about medical tools and how doctors help their patients, inside and out.</P><br /><P><STRONG>Tattoos you can use</STRONG></P><br /><P>Rogers doesn’t have any permanent tattoos. But he says he’s been wearing “more and more” of the temporary kind to hide the stuck-on electronic circuits. (He even concealed one device behind a blue pirate tattoo.) Temporary tattoos use a simple and inexpensive way to adhere, or stick, to skin: a good sticky backing that stretches and flexes with skin’s natural motion.</P><br /><P>Rogers and his colleagues have been experimenting with their new devices in the lab, taking various measurements of and from different parts of the body.</P> Skin-based, or epidermal, electronic systems stick to the skin like temporary tattoos. Attached to the head, they can pick up electrical signals from the brain. Credit: Image courtesy John A. Rogers<br /><P></P><br /><P>“We’ve done extensive testing,” says Todd Coleman, an engineer who tackles the problem of getting the device, the body and the mind to “talk” to each other. “I put one [device] near my forearm and clenched my fist to see how it monitored my muscle signals and movements. If you put it on the surface of the head, it records brain waves. Near the heart, it picks up heartbeat information. It’s the same device, just in different places.”</P><br /><P>The device is so light that a wearer may forget it’s there, says Coleman, now at the University of California San Diego. “We were trying to develop a piece of electronic material that is also basically completely invisible to the user. You barely even feel that the device is on your body,” he says.</P><br /><P><STRONG class="size-thumbnail wp-image-11644" title=EES2>More than skin deep</STRONG></P><br /><P>The scientists have found a way to extend the technology deeper than the body’s surface. In 2010, they introduced an electrical plastic wrap that can be attached to a person’s heart during open-heart surgery. Electronic circuits and instruments record blood flow and electric current, which means the material can alert doctors to hidden problems with a patient’s ticker. The team has already shown that a device attached to the surface of the brain can capture the electrical signals of an epileptic seizure.</P><br /><P>Rogers, who says he’s always been drawn to science, regularly participated in science fairs as a kid. But as he got older, he realized that scientists’ work can create positive changes in the world.</P><br /><P>“Making devices that have real benefits to society has been a real focus of our team, especially in recent years,” he says. “We<STRONG> </STRONG>are aiming to create<STRONG> </STRONG>devices that bring new ways to address health problems and other grand challenges in society.”</P> An electroencephalograph, or EEG, detects and measures electrical signals from the brain. But the device, which requires a lot of wires and time, is ready for an upgrade. Credit: istockphoto<br /><P></P><br /><P>Spies and deep-sea divers might also take note of the new “skintronics”: Attached to the neck, for example, the devices could detect the throat movements of speaking. That means a person can mouth words — without making a peep — and the device would record the movements and relay the silent message. It would be perfect for covert operations.</P><br /><P>“It’s unbelievable how much fun we’ve had having conversations with others about the device,” Coleman says.</P><br /><P><STRONG>Silicon: The problem and the answer</STRONG></P><br /><P>Scientists have been attaching electrical gadgets to skin for more than 80 years. In 1929, a German doctor named Hans Berger invented a device that attaches to the scalp and measures the brain’s electrical activity. His invention, called an electroencephalograph (EEG), lets doctors “read” brain activity. An EEG can help doctors diagnose diseases like epilepsy or detect when a patient slips into a coma.</P><br /><P>But the EEG has a major drawback: It’s clunky. Technicians tape a complex web of small nodes and wires to the head to get a good read. And EEG’s need power, delivered through wires, which adds to the mess. That’s not just a problem for EEG’s; it’s a problem for almost every electrical device, even fictional bits of gadgetry used by Batman or James Bond.</P><br /><P>A lighter, bendable device would provide the same information as an EEG, but without the heft. That idea started to seem like a reality in the early 1990s, when scientists around the world were racing to create flexible electronics. Computers became popular during this time, but most looked like clunky boxes attached to a nest of wires. Researchers envisioned flexible screens and computing devices that would bend and fold like paper.</P><br /><P>Rogers wanted to go even further.</P><br /><P>“I thought a more challenging goal might be to make an electronic device that bends like a sheet of paper but stretches like a rubber band,” he says.</P><br /><P>A problem loomed. Computers depend on an element called silicon. In nature, silicon appears as a dark-gray crystal. Thin wafers of the material conduct electricity, and for decades silicon has been used to make computer chips and other electronic parts. Silicon is important, useful stuff. But silicon wafers are brittle, which means they break easily.</P><br /><P>Rogers and his colleagues thought silicon perhaps could be made to bend like skin and not shatter.<STRONG> </STRONG>There wasn’t much they could do to the silicon material itself. But they thought arranging silicon wires into just the right shape might give the material more flexibility.</P> An accordion player widens and narrows the instrument’s bellows (red in photo) to control the flow of air. Like bellows, electronic skin devices have a shape that allows material to compress and expand without breaking. Credit: Palmkvist Knudsen/Wikimedia<br /><P></P><br /><P>The scientists wanted silicon to expand like an accordion’s bellows, the part of the instrument that looks like a folded rubber sheet. When a person plays the accordion, the bellows unfold and move farther apart from each other without the material itself stretching. Rogers wanted to take a similar approach, designing the device so its wires could “unfold” — letting the silicon strands move — without shattering.</P><br /><P>After three years of building and experimenting, Coleman says, the researchers produced a working device. Up close, the silicon looks like tiny, twisty snakes that wind through the material in complicated patterns. These winding silicon shapes form the different parts of the device — the sensors, antennae and power supply — and they can withstand stretching, poking and squeezing.</P><br /><P><STRONG>Mixing bodies and machines</STRONG></P><br /><P>In the not-so-distant future, surgery patients may find themselves wearing smart temporary tattoos, rather than bulky devices covered with wires. Rogers’ work is part of the growing field of “biointegrated technology,” devices built with the body in mind. They bring together machines and living things to improve lives. In the future, Rogers wants to extend the technology to create tiny devices that may even be able to operate independently within the body, improving, for example, the health of the human heart<STRONG>. </STRONG></P><br /><P>“The most immediate opportunity for biointegrated technology is to redefine what a surgical tool is,” he says.<STRONG> </STRONG>“My hope is that [the devices] will really have a large impact on the way that people think about surgical operations.” The ultimate goal, he says, is for the devices to track body and brain activity and “eliminate the need for surgical interventions in the first place.”</P><br /><P>With his research group in San Diego, Coleman wants to create new ways for people to use their brains to talk to machines — or even each other. He imagines a world in which people can work together, or even think together, using the devices to transmit information directly from their minds. “You could interact with a friend in both the natural and virtual world, using not only your behavior but also your thoughts,” he says.</P> Tiny snakelike strands of silicon are key to electronic skin devices’ success, allowing them to be flexible like skin. Credit: Image courtesy of John A. Rogers<br /><P></P><br /><P>The idea of connecting brains with the devices has implications in the classroom, too. “If we can monitor the brain signals between teachers and students who are interacting, then maybe we can learn the extent to which they understand each other,” Coleman says. “That could revolutionize education and training. It’s easy to imagine the possibilities. And if we don’t imagine, then what are we doing?”</P><br /><P>POWER WORDS (adapted from the New Oxford American Dictionary and acs.org)</P><br /><P><STRONG>materials science </STRONG>The study of how a material’s structure is related to its properties.</P><br /><P><STRONG>electroencephalography </STRONG>The measurement of electrical activity in different parts of the brain and the recording of such activity as a visual trace.</P><br /><P><STRONG>epidermis </STRONG>The outer layer of skin.</P><br /><P><STRONG>silicon </STRONG>A nonmetal, semiconducting element used in making electronic circuits. Pure silicon exists in a shiny dark-gray crystalline form and as a shapeless powder.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-89753223097194135202012-01-22T03:10:00.000-08:002012-01-22T03:10:00.361-08:00Fins as early legs The ancestors of this speckle-bellied lungfish were related to species that evolved into walking, land-dwelling animals. Scientists have been studying lungfish to understand how ancient, aquatic animals learned to walk. Credit: Joel Abroad<br /><P></P><br /><P>You may not be familiar with the word tetrapod, </EM>but you know one when you see it. All tetrapods are vertebrates — animals with backbones — and most move on land. They also have four limbs — or their ancestors did, as in the case of snakes and whales, for example. Reptiles, birds and amphibians all count as tetrapods, as do mammals. You’re a tetrapod.</P><br /><P>By studying fossils, scientists know that tetrapods haven’t always roamed Earth. They evolved from animals called lobe-finned fishes, which are named for their thick, strong fins. That means that over many generations, the fishes grew features that helped them move onto land. These features, which included longer limbs and digits, began appearing in the animals about 400 million years ago. (Digits are structures like fingers and toes at the end of a limb.)</P><br /><P>While fossils provide evidence that tetrapods evolved from lobe-finned fishes, they don’t show how the animals learned to walk (or hop, or scuttle or fly). Now, a team of biologists has found evidence that animals were preparing to walk while still living underwater. In a new study, the researchers suggest that lobe-finned fishes pushed themselves around with fleshy fins long before they moved onto land and grew longer limbs and digits.</P><br /><P>In the new work, the scientists didn’t scrutinize the fossil record. Instead, they pointed video cameras at living lobe-finned fishes called African lungfish and watched the animals scoot around the floor of an aquarium. Because lungfish are so closely related to tetrapods, scientists study the creatures to learn more about how ancient aquatic animals made a transition to living on land.</P><br /><P>“The cool thing about the lungfish is that it’s walking underwater,” biologist Heather King told Science News</EM>. “And if lots of tetrapods were also doing this it could mean that the first step in the evolution of vertebrate walking took place underwater.”</P><br /><P>King, from the University of Chicago, worked on the new study. Using cameras aimed at different angles, she and her colleagues recorded video footage of individual lungfish. The cameras showed that the animals push themselves along using alternating fins, just as animals use alternate legs to walk or crawl.</P><br /><P>Neil Shubin, another University of Chicago biologist who worked on the study, said the recordings clearly show the animals’ motions. “If you asked me to tell you what those fins do just by looking at them, I’d give you a thousand functions, and walking wouldn’t be one of them,” he told Science News</EM>. “But that’s what they do.”</P><br /><P>POWER WORDS (adapted from the New Oxford American Dictionary)</P><br /><P><STRONG>evolve</STRONG> To develop gradually over successive generations.</P><br /><P><STRONG>tetrapod</STRONG> A four-limbed animal, including amphibians, reptiles, birds and mammals.</P><br /><P><STRONG>digit</STRONG> A structure, like a finger or toe, at the end of the limbs of many vertebrates.</P><br /><P><STRONG>lobe</STRONG> A rounded and somewhat flat projection.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-80532559230549411152012-01-21T23:34:00.000-08:002012-01-21T23:34:00.063-08:00Glowing, gutsy hitchhikers Many organisms, from bacteria to fireflies to this deep-sea creature, emit light from chemical reactions inside the body. Scientists recently showed that animals are attracted to the light, gobbling up glowing bacteria that hitchhike around the ocean in the animal’s guts. Credit: NOAA<br /><P></P><br /><P>To hungry humans, glow-in-the-dark food may seem suspicious and unappetizing. To creatures that swim, slither and crawl in the darkest depths of the ocean, however, a glowing bug may be a welcome and easy snack.</P><br /><P>Scientists have come up with many ideas about why organisms light up. New experiments on tiny, glow-in-the-dark bacteria that live in the sea support the idea that a microbe’s glow isn’t just for show. Hungry animals are attracted to the light and eat the microbes, which then cruise around the ocean inside the animal’s guts. The idea is more than 30 years old, but new research from scientists in Israel and Germany boosts confidence in the theory.</P><br /><P>“It’s terrific to see this experiment,” J. Woodland Hastings told Science News</EM>. Hastings, a biologist at Harvard University who specializes in studying critters that glow, was not involved in the study. “It’s nice to see these ideas confirmed.”</P><br /><P>Lots of animals, from squid to fish, light up in the deep ocean. Inside their bodies, chemical reactions cause the glow, which is called bioluminescence.</P><br /><P>To test the idea that the light helps bacteria attract the attention of animals and hitch a ride, Margarita Zarubin studied bacteria from 2,000 feet beneath the surface of the Red Sea. Zarubin, who is now finishing her doctorate at the Interuniversity Institute for Marine Sciences in Eilat, Israel, conducted the experiments while a student at the University of Germany in Oldenburg.</P><br /><P>She began by placing brine shrimp in a tank with two kinds of deep-sea bacteria. One type glowed, the other didn’t. Hungry shrimp devoured the lighted bugs, but left the others alone. After eating the glowing bacteria, the shrimp also lit up — the bacteria glowed through the animals’ bodies.</P><br /><P>“We could see the luminescence from inside their guts,” Zarubin told Science News</EM>.</P><br /><P>Next, Zarubin and her colleagues took a step up the food chain. The team offered hungry fish glowing shrimp and nonglowing shrimp. Fish gobbled only the glowing shrimp; the other shrimp swam by in safety.</P><br /><P>Finally, Zarubin and her team studied poop from the fish. The scientists found the bacteria alive and well, which meant they had survived the journey through shrimp and fish guts. Zarubin told Science News </EM>that this unusual mode of transport, hitching rides in intestines, spreads bacteria faster than natural movements of the ocean will.</P><br /><P>Marine biologist Michael Latz of the Scripps Institution of Oceanography in La Jolla, Calif., told Science News</EM> that studying the gutsy journey of these bacteria may also help researchers understand how other germs spread through the sea.</P><br /><P>POWER WORDS (adapted from the New Oxford American Dictionary)</P><br /><P><STRONG>bioluminescence </STRONG>The emission of light by living organisms such as fireflies and deep-sea fishes.</P><br /><P><STRONG>marine </STRONG>From or of the sea.</P><br /><P><STRONG>bacteria</STRONG> Members of a large group of single-celled microorganisms, including some that can cause disease.</P><br /><P><STRONG>food chain </STRONG>A series of organisms where each depends on the next as a source of food.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-89791724271372969152012-01-21T19:59:00.000-08:002012-01-21T19:59:00.641-08:00New dangers from bird flu Bird flu travels fast among fowl, and the virus can be deadly to both birds and humans. Scientists have found a way to make the bird flu virus H5N1 more infectious among mammals. As a result, the U.S. government has asked scientists to not make public methods that could be dangerous if they fell into the wrong hands. Credit: Andrei Niemimäki<br /><P></P><br /><P>The viruses that cause “bird flu” spread easily among chickens, ducks and turkeys, often causing serious illness and sometimes death. These viruses don’t usually spread to humans, but it happens. And when it does, the results can be deadly. According to the Centers for Disease Control and Prevention, based in Atlanta, about 6 of every 10 people infected with the bird flu virus called H5N1 have died. If the virus ever did pass easily between people, it would cause widespread harm around the world.</P><br /><P>Understandably, scientists want to know more about the virus and how it spreads to try to prevent a disaster. In two recent studies, scientists demonstrated how the virus could be changed to pass more easily between mammals, making it more infectious. (In the experiments, the scientists tested the virus on ferrets.)</P><br /><P>In the hands of a bioterrorist who wants to cause harm on a large scale, such studies might be dangerous. They show how to turn H5N1 into a deadly biological weapon. That’s the concern of a committee organized by the National Institutes of Health (NIH), which is part of the U.S. government and the world’s largest medical research agency. The committee studied the new H5N1 papers and concluded that the virus could be made very dangerous, and that the new papers show how to do it.</P><br /><P>An NIH statement from December 20, 2011, acknowledges that this kind of research can benefit the public. On the other hand, according to the statement, “Certain information obtained through such studies has the potential to be misused for harmful purposes.” The NIH argues that some of the information in the studies should be kept under lock and key — and only shared with certain scientists on a demonstrated need-to-know basis. If terrorists created an H5N1 virus that spreads easily, they could start a global health threat. The NIH panel has therefore recommended that the scientists and scientific journals publishing the studies release the conclusions of the experiments — but withhold the methods used to make the germ more infectious.</P><br /><P>The U.S. government agrees with the panel’s recommendation. The government has formally requested, but not demanded, that scientists and journals hold back some of their new bird flu data. The editors of the journals are considering the request.</P><br /><P>The U.S. government already has rules in place that permit only some people to know secrets about nuclear weapons. Scientists need access to information, but the same information should be kept away from people with the intent to harm. The question is: Who gets to decide which people can see the science, and how much of it?</P><br /><P>The tricky part of this decision-making process is “drawing the line at which aspects of science are too risky to share,” Janet Raloff wrote in an article for Science News</EM>. Shrouding too much scientific research in secrecy may slow the advance of important scientific fields. But if studies like the recent H5N1 experiments always become public knowledge, they could offer terrorists easy access to dangerous new weapons.</P><br /><P>This back-and-forth between the government and the scientific community over bird-flu data shows that both sides are struggling to find the right answer. It also shows that medical research has moved into sensitive terrain, where there are no easy answers.</P><br /><P>POWER WORDS (adapted from the New Oxford American Dictionary)</P><br /><P><STRONG>flu, or influenza</STRONG> A highly contagious viral infection of the respiratory passages that causes fever, swelling and severe aching.</P><br /><P><STRONG>virus</STRONG> An infection-causing agent that typically has genetic material surrounded by a protein coat. A virus is too small to be seen under the microscope and is able to multiply only within the living cells of a host organism.</P><br /><P><STRONG>infectious</STRONG> Likely to be transmitted to people, organisms, etc., through the environment.</P><br /><P><STRONG>bioterrorism</STRONG> Terrorism involving the release of toxic biological agents.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-66012847306392315422012-01-21T15:49:00.000-08:002012-01-21T15:49:00.074-08:00Self-cleaning clothes Scientists in China have developed cotton fabric that uses sunlight to rid clothes of stains and smells. Credit: istockphoto<br /><P></P><br /><P>Cleaning clothes usually requires soap and water to remove stains and smells, and a tumble in the dryer or an afternoon on the clothesline to dry. The time and energy needed to turn a heap of dirty laundry into a pile of clean clothes might make people wish for clothes that just clean themselves.</P><br /><P>That wish is a step closer to coming true. Recent experiments show that cotton fabric coated with the right mixture of chemicals can dissolve stains and remove odors after only a few hours in the sun.</P><br /><P>“The technology can be applied to all kinds of fabrics and their related products,” says materials scientist Mingce Long. He helped develop the treated cotton with his colleague Deyong Wu, both of China’s Shanghai Jiao Tong University.</P><br /><P>The handy fabric gets its self-cleaning abilities from a chemical mixture that coats the cotton threads. The coating includes substances known as photocatalysts, which trigger chemical reactions in light. One of those photocatalysts, called titanium dioxide, helps sunscreen block the sun and is used as tattoo ink. Another, called silver iodide, is used for developing photographs.</P><br /><P>Researchers have previously shown that titanium dioxide mixtures could remove stains in clothes — but with exposure to ultraviolet, not visible, light. (The waves of ultraviolet light are more energetic and shorter than those of visible light.) Other studies have demonstrated that silver iodide can speed up chemical reactions in sunlight.</P><br /><P>“We knew that self-cleaning cotton fabrics with titanium dioxide coating had already been developed, but they cannot work, or they work weakly, under sunlight,” Long says. “If we want to use the fabrics in daily life, we must develop cotton that cleans itself under daylight.”</P><br /><P>Long and Wu created just such a fabric, working for years to perfect the recipe for a liquid dip that left cotton coated with the titanium dioxide mixture. Then they added particles of silver iodide, which boosted the fabric’s self-cleaning ability in the sun. In laboratory tests, their creation was nearly seven times better at removing stains (and killing bacteria lurking in the clothing) than titanium dioxide alone.</P><br /><P>The scientists can’t start selling their self-cleaning cotton just yet; scientists still need to make sure the coated cotton won’t harm those who wear it. Although titanium dioxide is used in some foods, recent experiments have shown that it can cause health problems if it gets in the lungs. So before the material can be worn, scientists need to find a way to make it safe.</P><br /><P>Still, Long says that he hopes to wear self-cleaning clothes one day — and avoid having to do laundry. “Someday in the future, when I walk on the street,” he says, “I hope people are wearing self-cleaning clothes that originated from my technology.”</P><br /><P>POWER WORDS (adapted from the New Oxford American Dictionary)</P><br /><P><STRONG>photocatalyst </STRONG>A substance that starts a chemical reaction when exposed to light.</P><br /><P><STRONG>chemical reaction </STRONG>A process that involves rearrangement of the molecules or structure of a substance, as opposed to a change in physical form.</P><br /><P><STRONG>titanium dioxide</STRONG> A white, unreactive, solid material that occurs naturally as a mineral and is used extensively as a white pigment.</P><br /><P><STRONG>silver iodide </STRONG>A yellow powder that darkens with exposure to light. It is used in photography and artificial rainmaking.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-8453534823215838902012-01-21T11:45:00.000-08:002012-01-21T11:45:00.056-08:00The brain behind the game Playing basketball feels physical, but the brain is hard at work too. Here, President Barack Obama works on his game. Credit: Official White House Photo by Pete Souza<br /><P></P><br /><P>With March Madness right around the corner, basketball-watching season is in full swing. People who play or watch the sport know that the right shot can make or break a game. A swoosh through the hoops may bring the thrill of victory; a backboard bounce may give a team another chance.</P><br /><P>Devoted fans aren’t the only ones watching pro basketball players and other athletes. Though top jocks may be well known for using their bodies, scientists have found that athletes’ brains also work hard while playing. Researchers are finding that during critical moments of the game, a player’s brain uses information differently than a fan’s, coach’s or other onlooker’s. These differences can help athletes make crucial decisions at breakneck speeds.</P><br /><P>Salvatore Aglioti, a neuroscientist at Sapienza University of Rome, studies how the human brain processes images of the body. He’s interested in the differences and similarities between the real, physical world and the virtual one created and used by the brain to help a person understand his or her surroundings. Aglioti thinks that brain cells called mirror neurons might be particularly important among athletes.</P><br /><P>Mirror neurons become active when a person does an action or when a person watches someone else do an action. These neurons behave the same whether you’re brushing your teeth or watching your friend brush her teeth. A basketball player’s mirror neurons fire when he’s playing and when he’s watching someone else play.</P><br /><P>Mirror neurons may help a player predict what’s going to happen in a game. When a player’s brain uses mirror neurons to track the actions of an opponent, the player might be able to anticipate his opponent’s next move and quickly respond in the best way.</P><br /><P>Aglioti designed a test to see if pro players were better than novices and spectators at anticipating another player’s moves. He showed each group time-lapse photographs of a player shooting, including the ball leaving the player’s hands. He compared the groups’ abilities to predict the success or failure of the shot.</P><br /><P>“Compared to novices and scouts, elite athletes were better at predicting the outcome of a shot after watching the body motion of basketball players,” Aglioti told Science News</EM>.</P><br /><P>A recent study of cricket athletes also showed that expert players take cues from body language to predict how the game will play out. And expert cricket players could better guess where a ball was headed if they were allowed to swing a bat while making their prediction — suggesting that imitating the action helps with anticipation.</P><br /><P>Novice cricket players’ predictions did not get better with a bat in hand. The study suggests that an athlete’s ability may rely on a strong connection between the real world and the virtual one conjured in his or her brain.</P><br /><P>Basketball fans waiting on the edges of their seats for the swoosh! </EM>or thwack!</EM> may not be thinking about mirror neurons and the science of imitation. But on the courts, imitating the moves of favorite players may put fans one step closer to their own three-pointers.</P><br /><P>POWER WORDS (adapted from the New Oxford American Dictionary)</P><br /><P><STRONG>neuroscience </STRONG>Any of the sciences that deal with the structure or function of the nervous system and brain.</P><br /><P><STRONG>neuron </STRONG>A specialized cell transmitting nerve impulses; a nerve cell.</P><br /><P><STRONG>cricket </STRONG>An open-air game played on a large grass field with a ball, bats and two wickets, between teams of eleven players. The object of the game is to score more runs than the opposition.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-4407121938579080482012-01-21T07:20:00.000-08:002012-01-21T07:21:02.314-08:00Water, water, not everywhere Twin satellites nicknamed Tom and Jerry (illustrated here) chase each other around Earth, measuring the planet’s gravitational field. Scientists say the satellites’ recordings suggest people may be using too much groundwater, and the resource could run dry. Credit: NASA<br /><P></P><br /><P>Keeping track of water makes for tricky science. It drains through soil, slips through cracks in rocks and refills underwater reserves. It bubbles up through springs and runs in rivers. Water evaporates and forms clouds; rain brings it back to earth, where it keeps plants alive and drains into the soil again.</P><br /><P>Scientists who study water’s movements recently reported that levels of groundwater — water found in soil or pooled in underground reservoirs — have been dropping for the last nine years in many places. Part of that decrease is probably due to human activities. People drill wells and pump water from deep underground pools, especially in dry areas, to grow crops and supply drinking water. The new study suggests we’re pumping out too much.</P><br /><P>“People are using groundwater faster than it can be naturally recharged,” hydrologist Matthew Rodell told Science News</EM>. By recharged, he means faster than rains and snowmelt can replace withdrawn groundwater. When a resource is used faster than it’s replaced, its use is said to be unsustainable. Hydrologists like Rodell, from NASA’s Goddard Space Flight Center in Greenbelt, Md., study the ways water moves around Earth. Sooner or later, at the rates measured by Rodell and his colleagues, the resource could run dry.</P><br /><P>The unsustainable groundwater-pumping pattern shows up all around the world, especially in places where agriculture has increased. Scientists detected declining water under the ground in India, southern Argentina, western Australia and some parts of the United States. Hydrologist Jay Famiglietti told Science News </EM>that underground water reserves in the world’s driest areas have been severely affected. Famiglietti, who also participated in the new study, works at the University of California Center for Hydrologic Modeling in Irvine.</P><br /><P>The scientists’ measurements came from a surprising source: two satellites orbiting Earth. Nicknamed Tom and Jerry after the cartoon cat and mouse, they constantly chase each other around the planet. Instead of teasing and tormenting each other, though, the twin satellites track changes in groundwater by measuring gravity.</P><br /><P>Gravity attracts anything with mass — the amount of stuff in something — to anything else with mass. It keeps Earth in orbit around the sun, and the moon in orbit around Earth. Thanks to gravity, people can walk on the ground instead of drifting off into space. Objects with more mass have a stronger gravitational pull on objects around them. The gravitational pull of a solid rock mountain on a satellite flying over it may be different from the ocean’s pull on the spacecraft.</P><br /><P>Because of these changes in gravity, Tom and Jerry move farther apart or closer together as they fly over different parts of Earth. The two satellites constantly send signals to each other, keeping track of the distance between them. Like other masses, groundwater’s gravity tugs on the satellites. But as water flows, its mass moves around, changing its gravitational pull.</P><br /><P>Tom and Jerry recorded these changes every month for nine years. The satellites, part of a mission called GRACE, began taking measurements in 2002. GRACE stands for Gravity Recovery and Climate Experiment, a collaboration between NASA and the German Aerospace Center.</P><br /><P>Recent droughts may explain the drop in groundwater in some places, like Argentina and the southeastern United States. The main reason, however, is farming. To grow crops in places like northern India and the western United States, farmers pump enormous quantities of water from the ground. In the Middle East, farmers use groundwater that probably came from rain that fell thousands of years ago. In this dry area, groundwater isn’t likely to be replaced by more rain any time soon.</P><br /><P>Scientists don’t know how serious the falling groundwater levels are. While Tom and Jerry show changes in the amount of water, they don’t show how much total water remains. Some of the reserves may meet water demand for hundreds of years; others might not. Some scientists, like hydrologist Leonard Konikow at the U.S. Geological Survey in Reston, Va., say people need to find ways to manage groundwater more responsibly.</P><br /><P>“There are too many areas in the world where groundwater development far exceeds a sustainable level,” he told Science News</EM>. “Something will have to change.”</P><br /><P>POWER WORDS (adapted from the New Oxford American Dictionary)</P><br /><P><STRONG>hydrology </STRONG>The science concerned with the properties of Earth’s water, especially its movement in relation to land.</P><br /><P><STRONG>gravity </STRONG>The natural force of attraction between any two massive bodies. The greater the mass and the smaller the distance between two objects, the greater the gravitational attraction.</P><br /><P><STRONG>satellite </STRONG>An artificial body placed in orbit around the moon, Earth or another planet in order to collect information or for communication.</P><br /><P><STRONG>mass </STRONG>The amount of matter, or stuff, that something contains.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-55994449653598628502011-12-29T23:07:00.000-08:002011-12-29T23:07:00.127-08:00For every road there is a tire<P>Life is complicated enough, so you can forgive the pioneers of DNA biology for glossing over transcriptional elongation control by RNA polymerase II, the quick and seemingly bulletproof penultimate step in the process that copies the information encoded in our DNA into protein-making instructions carried by messenger RNA. In a new report appearing in the Dec. 23, 2011, issue of Molecular Cell</EM>, researchers at the Stowers Institute for Medical Research add not just a new layer, but a whole new dimension to transcriptional elongation control with evidence that for each class of genes transcribed by RNA polymerase II (Pol II), there exists a specific class of elongation factors.</P><br /><P>The Stowers team, led by investigator Ali Shilatifard, Ph.D., discovered that ELL, short for eleven-nineteen lysine-rich leukemia, not only belongs to an assemblage of transcription elongation factors, which Shilatifard's lab had identified as the "Super Elongation Complex" (SEC) a few years ago, but also that ELL is part of a distinct "Little Elongation Complex" (LEC), which acts on a completely different class of genes transcribed by Pol II. Their findings illustrate that the elongation stage of transcription is a much more specific regulator of gene expression than previously believed.</P><br /><P>"About fifteen years ago, transcriptional elongation control was not considered all that important for the regulation of gene expression," says Shilatifard of the standard biology textbook descriptions of RNA transcription, which assume that the molecular machinery that supported transcription elongation was one-size-fits-all. "Once RNA polymerase II departed from the promoter regions, it didn't matter all that much what happened next," he says.</P><br /><P>Transcriptional elongation is the step following promoter clearance and the step before termination, and was considered to be largely unregulated. The old metaphor was a train running on tracks. "Polymerase is the train. It sat at the promoter -- which would correspond to the station," Shilatifard explains. "The polymerase train would leave the promoter/station and before long would arrive at the end of the gene. The process of the train traveling between the station and the endpoint of the gene -- is considered elongation."</P><br /><P>The latest findings derail the train metaphor. "We have shown that there are specific classes of elongation factors for different classes of genes. Therefore, much more is involved than a train simply following a predestined track," he says. "Years ago, B.F. Goodrich (the tire company) advertised that, 'for every road, there is a tire'. What we are learning is that for every class of genes, there seems to be a specific class of elongation factors. The specificity of the complexes seems to control which classes of genes are transcriptionally regulated," says Shilatifard.</P><br /><P>Edwin Smith, Ph.D., a research scientist in Shilatifard's lab, identified LEC in Drosophila</EM> cells while biochemically dissecting the proteins associated with theDrosophila</EM> homolog of the ELL protein. In human cells, where ELL is found within the SEC, it is required to induce the expression of a class of genes specific for the pathogenesis of a subtype of genes involved in acute leukemia.</P><br /><P>This type of leukemia results when, through a process known as translocation, the mixed lineage leukemia (MLL) gene becomes fused to any of a number of seemingly unrelated genes. In earlier studies, Shilatifard's group found that many of MLL's fusion partners, including ELL, belong to the SEC. When MLL fuses with any of these unrelated partners, the whole SEC, much like an entourage, now follows MLL to its normal target genes misregulating their elongation and ultimately causing leukemia.</P><br /><P>While humans have three ELL genes, fruit flies have only one ELL, but its structural similarity to the human ELLs suggested an evolutionarily conserved and vital function. To find out more about ELL's function in both creatures, Smith searched forDrosophila</EM> interaction partners in collaboration with Michael Washburn, Ph.D., and Laurence Florens, Ph.D., who head proteomics at the Stowers. They used their multi-dimensional protein identification technology, or MudPIT, to identify a set of relatively uncharacterized proteins in Drosophila</EM> that associate with the C-terminus of ELL in a complex the Shilatifard lab named the "Little Elongation Complex" or LEC.</P><br /><P>When Smith knocked down LEC subunits in fruit flies and analyzed the global expression pattern defect with Alexander Garrett, Ph.D., a bioinformatician in the Shilatifard lab, they found that the expression levels of small nuclear RNA (snRNA) genes plummeted. Unlike other RNAs transcribed by RNA pol II, these snRNA molecules are not translated into proteins, instead they team up with proteins to form small nuclear ribonucleoproteins (snRNPs) known by the cheerful name of "snurps." They form the spliceosome, which edits messenger RNA after it is transcribed from DNA. Smith, Garrett, and Chengqi Lin, a graduate student in Shilatifard's laboratory, also demonstrated that this function of LEC is highly conserved from Drosophila</EM> to mammals.</P><br /><P>"The specialization of the SEC and LEC complexes for mRNA and snRNA-containing genes, respectively, suggests the presence of specific classes of elongation factors for each class of genes transcribed by RNA polymerase II, which is of fundamental significance," says Smith.</P><br /><P>"The next step is to figure out what other classes of genes use other classes of elongation factors. And what are the differential mechanisms of recruitment to RNA Polymerase II on different classes of genes? Once we get a handle on these distinct classes of genes, we hope to be able to modify different classes of genes by modifying these elongation factors." This would be new perspective regarding basic biology and clinical intervention, Shilatifard believes.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-21770197945762593242011-12-29T18:11:00.000-08:002011-12-29T18:11:00.205-08:00Genetic study of black chickens shed light on mechanisms causing rapid evolution in domestic animals<P>The genetic changes underlying the evolution of new species are still poorly understood. Genetic studies in domestic animals can shed light on this process due to the rapid evolution they have undergone over the last 10,000 years. A new study describes how a complex genomic rearrangement causes a fascinating phenotype in chickens. In the study published in PLoS Genetics</EM> researchers at Uppsala University, Swedish University of Agricultural Sciences, North Carolina State University and National Chung-Hsing University have investigated the genetic basis of fibromelanosis, a breed characteristic of the Chinese Silkie chicken (image on left). This trait involves a massive expansion of pigment cells that not only makes the skin and comb black but also causes black internal organs. Chickens similar in appearance to the Silkie were described by Marco Polo when he visited China in the 13th century and Silkie chickens have a long history in Chinese cuisine and traditional Chinese medicine.</P><br /><P>"We have shown that the genetic change causing fibromelanosis is a complex rearrangement that leads to increased expression of Endothelin 3, a gene which is known for promoting the growth of pigment cells," explains Ben Dorshorst the post-doctoral researcher responsible for the work.</P><br /><P>The research group led by Leif Andersson has by now characterized a number of traits in domestic animals, and a clear trend is emerging, namely that genomic rearrangements have contributed significantly to the rapid evolution of domestic animals. Other examples include Greying with age in horses and mutations affecting the size and shape of the comb in chickens.</P><br /><P>"We have good reason to believe that such rearrangements have also played a significant role in the evolution of other species, including ourselves," concludes Leif Andersson.</P><br /><P>The researchers also studied other chicken breeds where fibromelanosis occurs, including the Bohuslän-Dals svarthöna breed (image on right) from Sweden, and they found that all fibromelanotic breeds carried the exact same very unusual mutation. This finding is consistent with anecdotal evidence suggesting that this Swedish breed of chicken inherited their black skin and internal connective tissue color from Asian chickens that were first brought to Norway by a sailor on the East Asian trade routes centuries ago. This is a nice example of how humans have distributed a single novel mutation with an interesting effect when they developed breeds of domestic animals around the world. -- It is obvious that humans have had a strong affection for biological diversity in their domestic animals, says Leif Andersson.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-61321943439956899902011-12-29T14:26:00.000-08:002011-12-29T14:26:01.204-08:00How bacteria fight flouride<P>Yale researchers have uncovered the molecular tricks used by bacteria to fight the effects of fluoride, which is commonly used in toothpaste and mouthwash to combat tooth decay. In the Dec. 22 online issue of the journal Science</EM> Express, the researchers report that sections of RNA messages called riboswitches -- which control the expression of genes -- detect the build-up of fluoride and activate the defenses of bacteria, including those that contribute to tooth decay.</P><br /><P>"These riboswitches are detectors made specifically to see fluoride," said Ronald Breaker, the Henry Ford II Professor and chair of the Department of Molecular, Cellular and Developmental Biology and senior author of the study.</P><br /><P>Fluoride in over-the-counter and prescription toothpastes is widely credited with the large reduction in dental cavities seen since these products were made available beginning in the 1950s. This effect is largely caused by fluoride bonding to the enamel of our teeth, which hardens them against the acids produced by bacteria in our mouths. However, it has been known for many decades that fluoride at high concentrations also is toxic to bacteria, causing some researchers to propose that this antibacterial activity also may help prevent cavities.</P><br /><P>The riboswitches work to counteract fluoride's effect on bacteria. "If fluoride builds up to toxic levels in the cell, a fluoride riboswitch grabs the fluoride and then turns on genes that can overcome its effects," said Breaker.</P><br /><P>Since both fluoride and some RNA sensor molecules are negatively charged, they should not be able to bind, he notes.</P><br /><P>"We were stunned when we uncovered fluoride-sensing riboswitches" said Breaker. "Scientists would argue that RNA is the worst molecule to use as a sensor for fluoride, and yet we have found more than 2000 of these strange RNAs in many organisms."</P><br /><P>By tracking fluoride riboswitches in numerous species, the research team concluded that these RNAs are ancient -- meaning many organisms have had to overcome toxic levels of fluoride throughout their history. Organisms from at least two branches of the tree of life are using fluoride riboswitches, and the proteins used to combat fluoride toxicity are present in many species from all three branches.</P><br /><P>"Cells have had to contend with fluoride toxicity for billions of years, and so they have evolved precise sensors and defense mechanisms to do battle with this ion," said Breaker, who is also an investigator with the Howard Hughes Medical Institute. Now that these sensors and defense mechanisms are known, Breaker said, it may be possible to manipulate these mechanisms and make fluoride even more toxic to bacteria. Fluoride riboswitches and proteins common in bacteria are lacking in humans, and so these fluoride defense systems could be targeted by drugs. For example, the Yale team discovered protein channels that flush fluoride out of cells. Blocking these channels with another molecule would cause fluoride to accumulate in bacteria, making it more effective as a cavity fighter.</P><br /><P>Fluoride is the 13th most common element in Earth's crust, and it is naturally present in high concentrations throughout the United States and elsewhere. Its use in toothpaste and its addition to city water supplies across the United States sparked a controversy 60 years ago, and the dispute continues to this day. In the United Kingdom, and in other European Union countries, fluoride is used to a much lesser extent due to fierce public opposition.</P><br /><P>The new findings from Yale only reveal how microbes overcome fluoride toxicity. The means by which humans contend with high fluoride levels remains unknown, Breaker notes. He adds that the use of fluoride has had clear benefits for dental health and that these new findings do not indicate that fluoride is unsafe as currently used.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-47217724910525489662011-12-29T09:51:00.000-08:002011-12-29T09:51:00.256-08:00Millipede border control better than ours<P>A mysterious line where two millipede species meet has been mapped in northwest Tasmania, Australia. Both species are common in their respective ranges, but the two millipedes cross very little into each other's territory. The 'mixing zone' where they meet is about 230 km long and less than 100 m wide where carefully studied. The mapping was done over a two-year period by Dr Bob Mesibov, who is a millipede specialist and a research associate at the Queen Victoria Museum and Art Gallery in Launceston, Tasmania. His results have been published in the open access journal ZooKeys</EM></EM>.</P><br /><P>'I have no idea why the line is so sharp', said Dr Mesibov. 'The boundary runs up and down hills, crosses rivers and different bedrocks and soils, and ignores vegetation type and climate differences. Its position and its sharpness seem to be the result of an unexplained biological arrangement between the two millipede species.'</P><br /><P>Biogeographers use the term 'parapatry' for the case where two species ranges meet but do not overlap, or overlap very little. Dr Mesibov said that parapatry has been reported before in other species of millipedes and in other terrestrial invertebrate animals, in Tasmania and elsewhere in the world. However, parapatric boundaries often parallel a geographical feature, such as a ridgeline, or a steep rainfall gradient.</P><br /><P>'There does not seem to be an ecological or a geographic explanation for this particular boundary, or for any part of it. It is also longer than any other parapatric boundary I know about. At 230 km, it is 50% longer than the boundary between England and Scotland, and the 'border control' is a lot better than what we humans can do.'</P><br /><P>The two millipede species, Tasmaniosoma compitale</EM></EM> and T. hickmanorum</EM></EM>, are in the same genus and thought to be closely related. They were first scientifically described in 2010, by the same author and again in ZooKeys</EM>. The parapatric boundary was mapped as a background study for later investigations of speciation in this group of millipedes, and of the mechanism of parapatry.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-35686101889302665512011-12-29T05:07:00.000-08:002011-12-29T05:07:00.460-08:00MSU chemists become the first to solve an 84-year-old theory<P>The same principle that causes figure skaters to spin faster as they draw their arms into their bodies has now been used by Michigan State University researchers to understand how molecules move energy around following the absorption of light. Conservation of angular momentum is a fundamental property of nature, one that astronomers use to detect the presence of satellites circling distant planets. In 1927, it was proposed that this principle should apply to chemical reactions, but a clear demonstration has never been achieved.</P><br /><P>In the current issue of Science, MSU chemist Jim McCusker demonstrates for the first time the effect is real and also suggests how scientists could use it to control and predict chemical reaction pathways in general.</P><br /><P>"The idea has floated around for decades and has been implicitly invoked in a variety of contexts, but no one had ever come up with a chemical system that could demonstrate whether or not the underlying concept was valid," McCusker said. "Our result not only validates the idea, but it really allows us to start thinking about chemical reactions from an entirely different perspective."</P><br /><P>The experiment involved the preparation of two closely related molecules that were specifically designed to undergo a chemical reaction known as fluorescence resonance energy transfer, or FRET. Upon absorption of light, the system is predisposed to transfer that energy from one part of the molecule to another.</P><br /><P>McCusker's team changed the identity of one of the atoms in the molecule from chromium to cobalt. This altered the molecule's properties and shut down the reaction. The absence of any detectable energy transfer in the cobalt-containing compound confirmed the hypothesis.</P><br /><P>"What we have successfully conducted is a proof-of-principle experiment," McCusker said. "One can easily imagine employing these ideas to other chemical processes, and we're actually exploring some of these avenues in my group right now."</P><br /><P>The researchers believe their results could impact a variety of fields including molecular electronics, biology and energy science through the development of new types of chemical reactions.</P><br /><P>Dong Guo, a postdoctoral researcher, and Troy Knight, former graduate student and now research scientist at Dow Chemical, were part of McCusker's team. Funding was provided by the National Science Foundation.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-85162703553696448782011-12-29T01:17:00.000-08:002011-12-29T01:17:00.206-08:00New device could bring optical information processing<P>Researchers have created a new type of optical device small enough to fit millions on a computer chip that could lead to faster, more powerful information processing and supercomputers. The "passive optical diode" is made from two tiny silicon rings measuring 10 microns in diameter, or about one-tenth the width of a human hair. Unlike other optical diodes, it does not require external assistance to transmit signals and can be readily integrated into computer chips.</P><br /><P>The diode is capable of "nonreciprocal transmission," meaning it transmits signals in only one direction, making it capable of information processing, said Minghao Qi (pronounced Chee), an associate professor of electrical and computer engineering at Purdue University.</P><br /><P>"This one-way transmission is the most fundamental part of a logic circuit, so our diodes open the door to optical information processing," said Qi, working with a team also led by Andrew Weiner, Purdue's Scifres Family Distinguished Professor of Electrical and Computer Engineering.</P><br /><P>The diodes are described in a paper to be published online Dec. 22 in the journal Science</EM>. The paper was written by graduate students Li Fan, Jian Wang, Leo Varghese, Hao Shen and Ben Niu, research associate Yi Xuan, and Weiner and Qi.</P><br /><P>Although fiberoptic cables are instrumental in transmitting large quantities of data across oceans and continents, information processing is slowed and the data are susceptible to cyberattack when optical signals must be translated into electronic signals for use in computers, and vice versa.</P><br /><P>"This translation requires expensive equipment," Wang said. "What you'd rather be able to do is plug the fiber directly into computers with no translation needed, and then you get a lot of bandwidth and security."</P><br /><P>Electronic diodes constitute critical junctions in transistors and help enable integrated circuits to switch on and off and to process information. The new optical diodes are compatible with industry manufacturing processes for complementary metal-oxide-semiconductors, or CMOS, used to produce computer chips, Fan said.</P><br /><P>"These diodes are very compact, and they have other attributes that make them attractive as a potential component for future photonic information processing chips," she said.</P><br /><P>The new optical diodes could make for faster and more secure information processing by eliminating the need for this translation. The devices, which are nearly ready for commercialization, also could lead to faster, more powerful supercomputers by using them to connect numerous processors together.</P><br /><P>"The major factor limiting supercomputers today is the speed and bandwidth of communication between the individual superchips in the system," Varghese said. "Our optical diode may be a component in optical interconnect systems that could eliminate such a bottleneck."</P><br /><P>Infrared light from a laser at telecommunication wavelength goes through an optical fiber and is guided by a microstructure called a waveguide. It then passes sequentially through two silicon rings and undergoes "nonlinear interaction" while inside the tiny rings. Depending on which ring the light enters first, it will either pass in the forward direction or be dissipated in the backward direction, making for one-way transmission. The rings can be tuned by heating them using a "microheater," which changes the wavelengths at which they transmit, making it possible to handle a broad frequency range.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-61115961537826315162011-12-28T22:12:00.000-08:002011-12-28T22:12:00.078-08:00New technique makes it easier to etch semiconductors<P>Creating semiconductor structures for high-end optoelectronic devices just got easier, thanks to University of Illinois researchers. The team developed a method to chemically etch patterned arrays in the semiconductor gallium arsenide, used in solar cells, lasers, light emitting diodes (LEDs), field effect transistors (FETs), capacitors and sensors. Led by electrical and computer engineering professor Xiuling Li, the researchers describe their technique in the journal Nano Letters.</EM></P><br /><P>A semiconductor's physical properties can vary depending on its structure, so semiconductor wafers are etched into structures that tune their electrical and optical properties and connectivity before they are assembled into chips.</P><br /><P>Semiconductors are commonly etched with two techniques: "Wet" etching uses a chemical solution to erode the semiconductor in all directions, while "dry" etching uses a directed beam of ions to bombard the surface, carving out a directed pattern. Such patterns are required for high-aspect-ratio nanostructures, or tiny shapes that have a large ratio of height to width. High-aspect-ratio structures are essential to many high-end optoelectronic device applications.</P><br /><P>While silicon is the most ubiquitous material in semiconductor devices, materials in the III-V (pronounced three-five) group are more efficient in optoelectronic applications, such as solar cells or lasers.</P><br /><P>Unfortunately, these materials can be difficult to dry etch, as the high-energy ion blasts damage the semiconductor's surface. III-V semiconductors are especially susceptible to damage.</P><br /><P>To address this problem, Li and her group turned to metal-assisted chemical etching (MacEtch), a wet-etching approach they had previously developed for silicon. Unlike other wet methods, MacEtch works in one direction, from the top down. It is faster and less expensive than many dry etch techniques, according to Li. Her group revisited the MacEtch technique, optimizing the chemical solution and reaction conditions for the III-V semiconductor gallium arsenide (GaAs).</P><br /><P>The process has two steps. First, a thin film of metal is patterned on the GaAs surface. Then, the semiconductor with the metal pattern is immersed in the MacEtch chemical solution. The metal catalyzes the reaction so that only the areas touching metal are etched away, and high-aspect-ratio structures are formed as the metal sinks into the wafer. When the etching is done, the metal can be cleaned from the surface without damaging it.</P><br /><P>"It is a big deal to be able to etch GaAs this way," Li said. "The realization of high-aspect-ratio III-V nanostructure arrays by wet etching can potentially transform the fabrication of semiconductor lasers where surface grating is currently fabricated by dry etching, which is expensive and causes surface damage."</P><br /><P>To create metal film patterns on the GaAs surface, Li's team used a patterning technique pioneered by John Rogers, the Lee J. Flory-Founder Chair and a professor of materials science and engineering at the U. of I. Their research teams joined forces to optimize the method, called soft lithography, for chemical compatibility while protecting the GaAs surface. Soft lithography is applied to the whole semiconductor wafer, as opposed to small segments, creating patterns over large areas -- without expensive optical equipment.</P><br /><P>"The combination of soft lithography and MacEtch make the perfect combination to produce large-area, high-aspect-ratio III-V nanostructures in a low-cost fashion," said Li, who is affiliated with the Micro and Nanotechnology Laboratory, the Frederick Seitz Materials Research Laboratory and the Beckman Institute for Advanced Science and Technology at the U. of I.</P><br /><P>Next, the researchers hope to further optimize conditions for GaAs etching and establish parameters for MacEtch of other III-V semiconductors. Then, they hope to demonstrate device fabrication, including distributed Bragg reflector lasers and photonic crystals.</P><br /><P>"MacEtch is a universal method as long as the right condition for deferential etching with and without metal can be found," Li said.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-63418658416321662112011-12-28T17:47:00.000-08:002011-12-28T17:47:00.319-08:00Penn scientists pioneer new method for watching proteins fold<P>A protein's function depends on both the chains of molecules it is made of and the way those chains are folded. And while figuring out the former is relatively easy, the latter represents a huge challenge with serious implications because many diseases are the result of misfolded proteins. Now, a team of chemists at the University of Pennsylvania has devised a way to watch proteins fold in "real-time," which could lead to a better understanding of protein folding and misfolding in general. The research was conducted by Feng Gai, professor in the Department of Chemistry in the School of Arts and Sciences, along with graduate students Arnaldo Serrano, also of Chemistry, and Robert Culik of the Department of Biochemistry and Molecular Biophysics at Penn's Perelman School of Medicine. They collaborated with Michelle R. Bunagan of the College of New Jersey's Department of Chemistry.</P><br /><P>Their research was published in the international edition of the journal Angewandte Chemie</EM>, where it was featured on the cover and bestowed VIP (very important paper) status.</P><br /><P>"One of the reasons that figuring out what happens when proteins fold is difficult is that we don't have the equivalent of a high-speed camera that can capture the process, " Gai said. "If the process were slow, we could take multiple 'pictures' over time and see the mechanism at work. Unfortunately, no one has this capability; the folding occurs faster than the blink of an eye."</P><br /><P>Gai's team uses infrared spectroscopy -- a technique that measures how much light different parts of a molecule absorbs -- to analyze proteins' structure and how this changes. In this case, the researchers looked at a model protein known as Trp-cage with an infrared laser setup.</P><br /><P>In this experiment, Gai's team used two lasers to study structural changes as a function of time. The first laser acts as the starting gun; by heating the molecule, it causes its structure to change. The second laser acts as the camera, following the motions of the protein's constituent amino acids.</P><br /><P>"The protein is made of different groups of atoms, and the different groups can be thought of as springs," Gai said. "Each spring has a different frequency with which it moves back and forth, which is based on the mass of the atom on either end. If the mass is bigger, the spring oscillates slower. Our 'camera' can detect the speed of that motion and we can relate it to the atoms it is made of and how that segment of the protein chain moves."</P><br /><P>Even in a simple protein like Trp-cage, however, there are many identical bonds, and the researchers need to be able to distinguish one from another in order to see which of them are moving while the protein folds. One strategy they used to get around this problem was to employ the molecular equivalent of a tracking device.</P><br /><P>"We use an amino acid with a carbon isotope marker," Culik said. "If it's incorporated into the protein correctly, we'll know where it is."</P><br /><P>With a single carbon atom of the Trp-cage slightly heavier than the others, the research team can use its signature to infer the position of the other atoms as they fold. The researchers could then "tune" the frequency of their laser to match different parts of the protein, allowing them to isolate them in their analyses.</P><br /><P>Similar isotopes could be inserted in more complicated molecules, allowing their folds to also be viewed with infrared spectroscopy.</P><br /><P>"This technique enhances our structural resolution. It allows us to see which part is moving," Gai said. "That would allow us to see exactly how a protein is misfolding in a disease, for example."</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-16617274683395909712011-12-28T13:09:00.000-08:002011-12-28T13:09:00.265-08:00'Rare' brain disorder may be more common than thought, say Mayo Clinic scientists<P>A global team of neuroscientists, led by researchers at Mayo Clinic in Florida, has found the gene responsible for a brain disorder that may be much more common than once believed. In the Dec. 25 online issue of Nature Genetics, the researchers say they identified 14 different mutations in the gene CSF1R that lead to development of hereditary diffuse leukoencephalopathy with spheroids (HDLS). This is a devastating disorder of the brain's white matter that leads to death between ages 40 and 60. People who inherit the abnormal gene always develop HDLS. Until now, a definite diagnosis of HDLS required examination of brain tissue at biopsy or autopsy. The finding is important because the researchers suspect that HDLS is more common than once thought and a genetic diagnosis will now be possible without need for a brain biopsy or autopsy. According to the study's senior investigator, neurologist Zbigniew K. Wszolek, M.D., a significant number of people who tested positive for the abnormal gene in this study had been diagnosed with a wide range of other conditions. These individuals were related to a patient known to have HDLS, and so their genes were also examined.</P><br /><P>"Because the symptoms of HDLS vary so widely -- everything from behavior and personality changes to seizures and movement problems -- these patients were misdiagnosed as having either schizophrenia, epilepsy, frontotemporal dementia, Parkinson's disease, multiple sclerosis, stroke, or other disorders," says Dr. Wszolek. "Many of these patients were therefore treated with drugs that offered only toxic side effects.</P><br /><P>"Given this finding, we may soon have a blood test that can help doctors diagnose HDLS, and I predict we will find it is much more common than anyone could have imagined," he says.</P><br /><P>Dr. Wszolek is internationally known for his long-term efforts to bring together researchers from around the world to help find cases of inherited brain disorders and discover their genetic roots.</P><br /><P>Dr. Wszolek's interest in HDLS began when a severely disabled young woman came to see him in 2003 and mentioned that other members of her family were affected. The diagnosis of HDLS was made by his Mayo Clinic colleague, Dennis W. Dickson, M.D., who reviewed the autopsy findings of the patient's uncle, who had previously been misdiagnosed as multiple sclerosis, and subsequently, Dr. Wszolek's patient and her father. All members of the family had HDLS.</P><br /><P>Dr. Dickson had identified other cases of HDLS from Florida, New York, Oregon and Kansas in the Mayo Clinic Florida brain bank and knew of a large kindred in Virginia with similar pathology, based upon a presentation at the annual meeting of the American Association of Neuropathologists. With concerted efforts, Dr. Wszolek and collaborators at University of Virginia were able to obtain DNA samples from the Virginia kindred. Dr. Wszolek also sought other cases, particularly those that had been reported in the neuropathology literature, and he was able to obtain samples from Norway, the United Kingdom, Germany and Canada, and other sites in the U.S. He and his team of investigators and collaborators have since published studies describing the clinical, pathologic and imaging characteristics of the disorder, and they have held five international meetings on HDLS.</P><br /><P>In this study, which included 38 researchers from 12 institutions in five countries, the study's first author, Rosa Rademakers, Ph.D., led the effort to find the gene responsible for HDLS. Her laboratory studied DNA samples from 14 families in which at least one member was diagnosed with HDLS and compared these with samples from more than 2,000 disease-free participants. The gene was ultimately found using a combination of traditional genetic linkage studies and recently developed state-of-the art sequencing methods. Most family members studied -- who were found to have HDLS gene mutations -- were not diagnosed with the disease, but with something else, thus emphasizing the notion that HDLS is an underdiagnosed disorder.</P><br /><P>The CSF1R protein is an important receptor in the brain that is primarily present in microglia, the immune cells of the brain. "We identified a different CSF1R mutation in every HDLS family that we studied," says Dr. Rademakers. "All mutations are located in the kinase domain of CSF1R, which is critical for its activity, suggesting that these mutations may lead to deficient microglia activity. How this leads to white matter pathology in HDLS patients is not yet understood, but we now have an important lead to study."</P><br /><P>"With no other disease have we found so many affected families so quickly," says Dr. Wszolek. "That tells me this disease is not rare, but quite common." He adds, "It is fantastic that you can start an investigation with a single case and end up, with the help of many hands, in what we believe to be a world-class gene discovery."</P><br /><P>The study was funded by a Mayo benefactor and the Mayo Foundation. Additionally, Mayo Clinic in Florida is a Morris K. Udall Parkinson's Disease Research Center of Excellence supported by the National Institute of Neurological Disorders and Stroke.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-43929813478844909142011-12-28T08:37:00.000-08:002011-12-28T08:37:00.250-08:00Severe congenital disorder successfully treated in a mouse model for the first time<P>Using a mouse model, Heidelberg University Hospital researchers have for the first time successfully treated a severe congenital disorder in which sugar metabolism is disturbed. The team headed by Prof. Christian Körner, group leader at the Center for Child and Adolescent Medicine, demonstrated that if female mice are given mannose with their drinking water prior to mating and during pregnancy, their offspring will develop normally even if they carry the genetic mutation for the congenital disorder. The team's outstanding work will contribute to better understanding of the molecular processes of this metabolic disease, along with the key stages in embryonic development, and may offer a therapeutic approach for the first time. The Heidelberg-based researchers also collaborated with colleagues working with Prof. Hermann-Josef Gröne of the German Cancer Research Center (DKFZ)'s Division of Cellular and Molecular Pathology in Heidelberg. Their results have now been published online in the journal Nature Medicine</EM> in advance of their publication in the print edition.</P><br /><P><STRONG>Rare disease: Approx. 1,000 children affected</STRONG></P><br /><P>So far 1,000 children worldwide are affected by congenital disorders of glycosylation (CDG), which are classified as rare diseases. Affecting around 800 children, type CDG-Ia is most frequent. The number of unreported cases is high, however. Children with CDG are severely physically and mentally disabled, with approx. 20 percent dying before the age of two. To date, no therapy has been available to treat the disorder.</P><br /><P>CDG-Ia is caused by mutations in the genetic information for the enzyme Phosphomannomutase 2 which is involved in important glycosylation processes: Mannose-1-phosphate is not produced in sufficient quantities. As a result, glycosylation malfunctions, meaning that sugar chains that normally aid in form, stability and function of the glycoproteins are not completely attached to the body's proteins or in some cases, are not attached at all. The lack of oligosaccharide chains leads to impairment of neurological, growth and organ development. The disorder only manifests if the baby inherits a mutated gene from both the mother and the father. The parents, who each carry one mutated and one "healthy" copy of the gene, do not exhibit any symptoms.</P><br /><P><STRONG>Mice take up mannose in drinking water</STRONG></P><br /><P>The mouse model developed by Prof. Körner and his team is characterized by mutations in the Phosphomannomutase 2 gene and demonstrates reduced enzyme activity, comparable to CDG-Ia in man. In their current study, the scientists exploited the ability of mannose to cross the placental barrier. This means that if the pregnant mouse takes up mannose, it also reaches the embryos in the uterus.</P><br /><P>"One week prior to mating, we began giving the female mice mannose with their drinking water," explained biochemist Prof. Körner. The additional mannose supply up to birth increased the mannose levels in the embryos' blood. "The mice were born without defects and also after they were born, developed without any symptoms of the disorder, even if they no longer took up any mannose," Körner added. The successful studies performed by the Heidelberg University Hospital researchers clearly show the key role played by the supply of proteins with sugar chains during embryonic development.</P><br /><P><STRONG>New therapeutic approach</STRONG></P><br /><P>"Clinical studies in the U.S. and Germany have already been performed in which children with CDG-Ia were given mannose after they were born, either orally or by intravenous infusion. Unfortunately, these attempts have not been successful," explained Dr. Christian Thiel, head of the laboratory. "This means that the critical point at which it is possible to influence development must be during development in the uterus." For women with a risk of CDG-Ia, administering mannose during pregnancy may serve as a new therapeutic approach.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-46050407592015944162011-12-28T05:36:00.000-08:002011-12-28T05:36:00.213-08:00Shearing triggers odd behavior in microscopic particles<P>Microscopic spheres form strings in surprising alignments when suspended in a viscous fluid and sheared between two plates -- a finding that will affect the way scientists think about the properties of such wide-ranging substances as shampoo and futuristic computer chips. A team of scientists at Cornell University and the University of Chicago have imaged this behavior and have explained the forces causing it for the first time. Its findings appear in the Dec. 19-23 early edition of the Proceedings of the National Academy of Sciences</EM>.</P><br /><P>"The experimental breakthrough revealed that these string structures were perpendicular to the shear instead of parallel to it, contrary to what many in the field were expecting," said Aaron Dinner, associate professor in chemistry at UChicago and a study co-author.</P><br /><P>The experiment was led by Itai Cohen, associate professor of physics at Cornell, who custom-built a device that would enable him simultaneously to exert shearing forces on suspended colloids (the spheres) and image the resulting motion at 100 frames per second with a confocal microscope. Imaging speed was critical to the experiment because the string-like structures appear only at certain shear rates.</P><br /><P>"This issue of strings has been pretty controversial. I'm not sure that we've solved all the controversies associated with them, but at least we've made a step forward," Cohen said.</P><br /><P>Shearing forces affect the dynamic behavior of paint, shampoo and other viscous household products, but an understanding of these and related phenomena at the microscopic level has largely eluded a detailed scientific understanding until the last decade, Dinner noted.</P><br /><P>Futuristically speaking, these forces potentially could be harnessed to produce microscopic patterns on computer chips or biosensors via special paints that flow easily when layered in one direction, but becomes hard when layered in another direction.</P><br /><P>Cohen's objective was more scientifically immediate: to devise an experiment that would overcome the technical difficulties associated with measuring the mechanical properties of the colloidal strings while also imaging their formation. "The holy grail is to be able to understand how the structure leads to the mechanical properties and then to be able to control the mechanical properties by influencing the structure," Cohen explained.</P><br /><P>Cohen, PhD'01, received his doctorate in physics at UChicago, as did lead author Xiang Cheng, PhD'09, a postdoctoral associate at Cornell who assembled the team; and co-author Xinliang Xu, PhD'07, a postdoctoral scholar at UChicago. The study co-authors also included Stuart Rice, the Frank P. Hixon Distinguished Service Professor Emeritus in Chemistry at UChicago and a 1999 recipient of the National Medal of Science.</P><br /><P>As members of UChicago's Materials Research Science and Engineering Center, Rice and Dinner are part of a larger effort to determine how materials behave under the influence of various dynamic forces. Some of their physics colleagues analyze forces operating on macroscopic scales, while chemists such as Rice and Dinner attempt to assess how those findings might apply to microscopic phenomena.</P><br /><P>Rice and his UChicago co-authors used computer simulations to develop a precise explanation for the string-like colloidal structures that formed in the Cornell experiment. "The previous simulations all left out the consequences of the flow created in the supporting fluid as the particles move, the so-called hydrodynamic forces," Rice said.</P><br /><P>"A very large fraction of the work in the field neglects hydrodynamic forces because it's hard. You try and get away with what you can," Rice noted with amusement. "But in this case it turns out that the inclusion of those forces is the crucial element."</P><br /><P>The simulations allowed the UChicago team to control various experimental parameters to assess their relative importance. "You can play God," Rice said. "The important finding is the overwhelming role of the lubrication forces and the anti-intuitive result that they create."</P><br /><P>The lubrication force comes into play when two colloids come together to behave much like macroscopic ball bearings soaking in a reservoir of goopy fluid.</P><br /><P>"Pulling them apart would be working against the fluid and so it would be very hard," Dinner said. "So actually, when you get a collision in these colloidal systems, those lubrication forces hold them together much longer, and that actually allows for some of the unique dynamics that give rise to the structure. That was specifically what the simulations showed."</P><br /><P>Xu, the UChicago postdoctoral scholar, adapted a mathematical formula developed by John Brady at the California Institute of Technology to simplify the simulations, which ran for days and weeks at a time. "Every time you rearrange the particles, the interactions are different," Rice said. "If you were to calculate that directly, it would be extremely tedious."</P><br /><P>But Xu's adapation of Brady's formula enabled him to generate a table of hydrodynamic interactions that listed each particle configuration. Xu found that he could accurately simplify the simulation by focusing on just two of the experiment's seven layers of colloids.</P><br /><P>The simulations and the experiment showed that even after three centuries of study, the field of hydrodynamics continues to yield surprising discoveries. "We are still discovering novel behavior that is fundamentally determined by the hydrodynamics," Rice noted.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-72995984941043472042011-12-28T01:03:00.000-08:002011-12-28T01:03:00.435-08:00UTHealth researchers link multiple sclerosis to different area of brain<P>Radiology researchers at The University of Texas Health Science Center at Houston (UTHealth) have found evidence that multiple sclerosis affects an area of the brain that controls cognitive, sensory and motor functioning apart from the disabling damage caused by the disease's visible lesions. The thalamus of the brain was selected as the benchmark for the study conducted by faculty at the UTHealth Medical School. Lead researchers include Khader M. Hasan, Ph.D., associate professor, and Ponnada A. Narayana, Ph.D., professor and director of Magnetic Resonance Imaging (MRI) in the Department of Diagnostic and Interventional Imaging; and Jerry S. Wolinsky, M.D., the Bartels Family and Opal C. Rankin Professor in the Department of Neurology.</P><br /><P>Results of the research were published in a recent edition of The Journal of Neuroscience</EM>.</P><br /><P>"The thalamus is a central area that relates to the rest of the brain and acts as the 'post office,' " said Hasan, first author of the paper. "It also is an area that has the least amount of damage from lesions in the brain but we see volume loss, so it appears other brain damage related to the disease is also occurring."</P><br /><P>Researchers have known that the thalamus loses volume in size with typical aging, which accelerates after age 70. The UTHealth multidisciplinary team's purpose was to assess if there was more volume loss in patients with multiple sclerosis, which could explain the dementia-related decline associated with the disease.</P><br /><P>"Multiple sclerosis patients have cognitive deficits and the thalamus plays an important role in cognitive function. The lesions we can see but there is subclinical activity in multiple sclerosis where you can't see the changes," said senior author Narayana. "There are neurodegenerative changes even when the brain looks normal and we saw this damage early in the disease process."</P><br /><P>For the study, researchers used precise imaging by the powerful 3 Tessla MRI scanner to compare the brains of 109 patients with the disease to 255 healthy subjects. The patients were recruited through the Multiple Sclerosis Research Group at UTHealth, directed by Wolinsky, and the healthy controls through the Department of Pediatrics' Children's Learning Institute.</P><br /><P>Adjusting for age-related changes in the thalamus, the patients with multiple sclerosis had less thalamic volume than the controls. The amount of thalamic loss also appeared to be related to the severity of disability.</P><br /><P>"This is looking at multiple sclerosis in a different way," Hasan said. "The thalami are losing cellular content and we can use this as a marker of what's going on. If we can find a way to detect the disease earlier in a more vulnerable population, we could begin treatment sooner."</P><br /><P>The research was funded by a grant from the National Institutes of Health. The title of the article is "Multimodal Quantitative Magnetic Resonance Imaging of Thalamic Development and Aging Across the Human Lifespan: Implications to Neurodegeneration in Multiple Sclerosis."</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.comtag:blogger.com,1999:blog-8852281138337560781.post-1164374592770779172011-12-27T21:27:00.000-08:002011-12-27T21:27:00.146-08:00Viagra against heart failure: Researchers at the RUB and from Rochester throw light on the mechanism<P>How sildenafil, the active ingredient in Viagra, can alleviate heart problems is reported by Bochum's researchers in cooperation with colleagues from the Mayo Clinic in Rochester (Minnesota) in the journal Circulation. They studied dogs with diastolic heart failure, a condition in which the heart chamber does not sufficiently fill with blood. The scientists showed that sildenafil makes stiffened cardiac walls more elastic again. The drug activates an enzyme that causes the giant protein titin in the myocardial cells to relax. "We have developed a therapy in an animal model that, for the first time, also raises hopes for the successful treatment of patients" says Prof. Dr. Wolfgang Linke of the RUB Institute of Physiology.</P><br /><P><STRONG>"Rubber band proteins" can be influenced</STRONG></P><br /><P>Sildenafil inhibits a specific enzyme (phosphodiesterase 5 A), which causes the increased formation of a messenger substance (cGMP). The messenger substance activates the enzyme protein kinase G, which attaches phosphate groups to certain proteins. This so-called phosphorylation causes blood vessels to relax, which was why the "potency pill" Viagra originally came onto the market. The Bochum and Rochester researchers found that the cardiac muscle protein titin is also phosphorylated through the same mechanism. "The titin molecules are similar to rubber bands" explains the Bochum physiologist. "They contribute decisively to the stiffness of the cardiac walls." The activity of the protein kinase G causes titin to relax. This makes the cardiac walls more elastic. The effect occurs within minutes of administering the drug.</P><br /><P><STRONG>Heart failure drugs currently not sufficient </STRONG></P><br /><P>"Of all the patients aged over 60 who are in hospital because of a weak heart, half suffer from diastolic heart failure" explains Linke. "Although we know that the decreased distensibility of the cardiac walls is the cause, the disease cannot be treated properly with today's medicines." In the so-called "Relax" study of the Heart Failure Network, the efficacy of sildenafil in people is already being tested. "If, for the first time, the drug is found to have a positive effect on heart failure, we would already have a molecular mechanism on hand to explain the effect" says Linke.</P>Anonymoushttp://www.blogger.com/profile/16462870011217311780noreply@blogger.com