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The world's most accurate clock has neatly shown how right Albert Einstein was 100 years ago, when he proposed that time is a relative concept and the higher you live above sea level the faster you should age.

Einstein's theory of relativity states that time and space are not as constant as everyday life would suggest. He suggested that the only true constant, the speed of light, meant that time can run faster or slower depending on how high you are, and how fast you are travelling.

Now scientists have demonstrated the true nature of Einstein's theory for the first time with an incredibly accurate atomic clock that is able to keep time to within one second in about 3.7 billion years – roughly the same length of time that life has existed on Earth.

James Chin-Wen Chou and his colleagues from the US National Institute of Standards and Technology in Boulder, Colorado, found that when they monitored two such clocks positioned just a foot apart in height above sea level, they found that time really does run more quickly the higher you are – just has Einstein predicted.

"These precise clocks reveal the effects of gravitational pull, so if we position one clock closer to a planet, you also increase the gravitational pull and time actually runs slower than for another, similar clock positioned higher up," Dr Chou said. "No one has seen such effects before with clocks which is why we wanted to see if these effects are there. We would say our results agree with Einstein's theory – we weren't expecting any discrepancies and we didn't find any," he explained.

The atomic clocks used in the study are based on the tiny vibrations of aluminium atoms trapped in an electric field. These vibrations are in the same frequency range of ultraviolet light, detected by lasers, which effectively means that the atomic timepieces are optical clocks, accurate enough to measure billionths of a second and to keep time accurately over millions of years.

It means that the clocks were able to perceive the dilation of time with height above ground that was first predicted by Einstein. For every foot above ground, for instance, the clocks showed that someone would age about 90 billionths of a second faster over a 79-year lifetime, Dr Chou said.

The time dilation experiment, published in the journal Science, is vivid proof of how time is not what we think it is. The researchers also demonstrated that when the atomic clocks were altered in a way that mimics the effect of travelling through space, time began to slow down, as the theory of relativity says it should.

This is a practical demonstration of the "twin paradox", a thought experiment of Einstein's special theory of relativity which states that an identical twin sibling who travels through space in a rocket will actually age more slowly than the other twin living on terra firma.

Marcus Chown, author of the best-selling We Need to Talk about Kelvin, which is shortlisted for this year's Science Book Prize, said that the results of the atomic clock experiments were a remarkable demonstration of Einstein's theories.

"What's really remarkable is that these studies show these incredibly small effects of relativity over such short distances," he said. "They have demonstrated graphically that although we think of relativity as an esoteric theory of no relevance to everyday life, we can in fact show that it is really true that you will grow old marginally faster if you stand just one step higher on a staircase.

"It's a very small effect, but it brings these esoteric effects into the everyday world. It shows that if you want to live longer, buy a bungalow," he added.

drive from www.independent.co.uk

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A genetic test has been developed that can predict whether someone is likely to live an extremely long life, but scientists have warned that society is still not ready for such predictions.

The test is based on a scan of a person's entire genome; so far it can predict whether someone is likely to live to 100 with an accuracy of 77 per cent. However, refinements to the test will improve its precision, raising the prospect that it could one day be used to predict whether someone is genetically predisposed to extreme longevity.

Commercial organisations are likely to market the test within a few years. But the scientists behind the research warn that there should be a public debate on the ethical implications behind such testing.
Researchers developed the test by analysing the genomes of 1,055 centenarians from different parts of the world and comparing slight variations in their DNA with the genetic makeup of a set of people younger than 100. The scientists found that by concentrating on just 150 individual mutations in the human genome, they could predict with 77 per cent accuracy whether someone belonged to the group of centenarians. Although the test is still at a rudimentary stage, scientists said that they could foresee it being developed commercially within a few years to identify people with an inherited predisposition to live a long life that is likely, until the final years, to be largely free of age-related disorders such as cancer and heart disease.

Thomas Perls of the Boston University School of Medicine, who led the study published in the journal Science, said the aim of the research was to understand the genetic reasons why some people live longer than others despite having similar lifestyles.

"We embarked on the study to understand the genetics of exceptional longevity," Professor Perls said. "Clearly we realise that this is a very complex genetic puzzle. Exceptional longevity is not the vacuous entity that some people make it out to be. This really opens the door to understanding the genetic and lifestyle determinants of longevity."

Professor Perls said that a predictive accuracy of 77 per cent is "fairly unprecedented" and there is nothing to stop biotechnology companies from using this information, which is now freely available in the public domain, to develop commercial tests for extreme longevity. But he warned: "I for one don't think we're ready from a social point of view, but I think that won't stop companies from trying to market this."

The scientists found that 90 per cent of the centenarians in the study possessed a definite "genetic signature" of extreme longevity, denoted by the particular combination of genetic mutations they carried. The researchers also found that 45 per cent of the oldest centenarians – those over the age of 110 – had a genetic signature with the highest proportion of longevity-associated mutations.

Professor Perls said: "These genetic signatures are a new advance towards personalised genomics and predictive medicine, where this analytic method may prove to be generally useful in prevention and screening of numerous diseases, as well as in the tailored uses of medications."

drive from www.independent.co.uk

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Dean Stevenson has farmed the plains of south-central Idaho most of his forty-seven years. Like all farmers, he worries about things like the price of sugar beets and malt barley or the cost of gasoline, but most of all, he worries about water.

He is right to worry. The 4,000 acres he farms with his father and brother receive on average a scant 10 inches of rain per year. The water that sustains the sugar beets, barley, wheat, and potatoes growing on Stevenson land is pumped from the Snake River Plain aquifer. Every drop is rationed.

Stevenson is part of a water district—the Magic Valley Ground Water—that helps manage water taken from the aquifer.In 2006, another irrigation district on the Snake River Plain, A&B, believed that some of the farms in its district had run short on water, resulting in a poor harvest. Because A&B has senior (older) water rights, Idaho law allowed them to issue a water call, a demand that junior water right holders, including Stevenson, draw less water from the aquifer.

The agency with the unenviable task of sorting out water calls is the Idaho Department of Water Resources. The agency keeps track of how much water is in the state’s rivers and ground water to ensure that Idaho has a viable water supply for all of its users—farmers, cities and towns, and natural ecosystems.

Idaho uses more water than any other U.S. state except California and Texas, the two most populous states. More than 90 percent of the water consumed in Idaho goes to irrigate 3.4 million acres of farmland, providing the economic base for the state. In recent years, some of the department’s most detailed information on how much water farmers consume has come not from water meters on the ground, but from innovative space-based estimates of the evaporation of water from soil and plants.
The new method holds enough promise for Western water management—a challenge that population growth and climate change are likely to intensify in coming decades—that it influenced the design of the next satellite in NASA’s decades-old Landsat program, now jointly managed by NASA and the United States Geological Survey.

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Best time to see Mars in 2010 is January and February
The 2010 opposition of Mars happens on January 29. You want to see the planet Mars, right? Sure! Everyone does! About every two years, Mars suddenly becomes much more noticeable. That’s already happening as I write this, in mid-January of 2010. Mars’ brightness has increased, and it is appearing in the sky for more hours of the night now than it has for the past couple of years. In late January of 2010, Mars will be at its best for this two-year period. The chart below shows Mars on January 29, when it will be near the full moon. You’ll find Mars every evening now in the east by the time true darkness falls. By late January, Mars will be ascending in the east immediately after sunset. In February, it will be in the east already when the sun goes down. Mars is reddish. It shines steadily. Look in the east any evening now, and you’re likely to notice it!

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It is considered, in North America, to be one of the four sub-fields of anthropology. A modern archaeological project often begins with a survey.

Regional survey is the attempt to systematically locate previously unknown sites in a region.

Site survey is the attempt to systematically locate features of interest, such as houses and middens, within a site.

Each of these two goals may be accomplished with largely the same methods. Archaeological excavation existed even when the field was still the domain of amateurs, and it remains the source of the majority of data recovered in most field projects.

It can reveal several types of information usually not accessible to survey, such as stratigraphy, three-dimensional structure, and verifiably primary context. Modern excavation techniques require that the precise locations of objects and features, known as their provenance or provenience, be recorded.

This always involves determining their horizontal locations, and sometimes vertical position as well.

Similarly, their association, or relationship with nearby objects and features, needs to be recorded for later analysis.

This allows the archaeologist to deduce what artefacts and features were likely used together and which may be from different phases of activity.

For example, excavation of a site reveals its stratigraphy; if a site was occupied by a succession of distinct cultures, artefacts from more recent cultures will lie above those from more ancient cultures..

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Dean Stevenson has farmed the plains of south-central Idaho most of his forty-seven years. Like all farmers, he worries about things like the price of sugar beets and malt barley or the cost of gasoline, but most of all, he worries about water.

He is right to worry. The 4,000 acres he farms with his father and brother receive on average a scant 10 inches of rain per year. The water that sustains the sugar beets, barley, wheat, and potatoes growing on Stevenson land is pumped from the Snake River Plain aquifer. Every drop is rationed.

Stevenson is part of a water district—the Magic Valley Ground Water—that helps manage water taken from the aquifer.In 2006, another irrigation district on the Snake River Plain, A&B, believed that some of the farms in its district had run short on water, resulting in a poor harvest. Because A&B has senior (older) water rights, Idaho law allowed them to issue a water call, a demand that junior water right holders, including Stevenson, draw less water from the aquifer.

The agency with the unenviable task of sorting out water calls is the Idaho Department of Water Resources. The agency keeps track of how much water is in the state’s rivers and ground water to ensure that Idaho has a viable water supply for all of its users—farmers, cities and towns, and natural ecosystems.

Idaho uses more water than any other U.S. state except California and Texas, the two most populous states. More than 90 percent of the water consumed in Idaho goes to irrigate 3.4 million acres of farmland, providing the economic base for the state. In recent years, some of the department’s most detailed information on how much water farmers consume has come not from water meters on the ground, but from innovative space-based estimates of the evaporation of water from soil and plants.
The new method holds enough promise for Western water management—a challenge that population growth and climate change are likely to intensify in coming decades—that it influenced the design of the next satellite in NASA’s decades-old Landsat program, now jointly managed by NASA and the United States Geological Survey.

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Researchers at the University of California, Davis, recently identified a powerful scent produced by both humans and birds that apparently lures Culex mosquitoes to their next blood meal.

The source, a substance called nonanal, emits a fruity or floral odor and also is made commercially, used in manufacturing perfumes and flavors. When given off in the air, nonanal works synergistically with carbon dioxide, another known mosquito attractant, to send a strong message to the biting insects. Mosquitoes detect smells with the olfactory receptor neurons of their antennae.
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“Nonanal is how they find us,” said Walter Leal, a professor of entomology and leader of the research team.

“Mosquitoes are very sensitive to this compound,” he added. “It’s a very common chemical produced by humans and animals, and also industry. It’s everywhere.”

The discovery ultimately could lead to new ways of controlling mosquitoes, which carry disease-causing viruses, including West Nile virus. A West Nile infection can result in serious neurological illness. Mosquitoes from the Culex family--the focus of this study--carry West Nile.

Birds, the main host of mosquitoes, are a reservoir for West Nile. The insects transmit viruses to humans--as well as to birds, horses, dogs, cats, bats, chipmunks, squirrels and domestic rabbits--when they bite and take a blood meal.

“If you can decrease the biting of mosquitoes, you can decrease the incidence of disease,” Leal said.

Leal and postdoctoral researcher Zain Syed screened hundreds of naturally occurring compounds emitted by multiracial and multiethnic humans, and multiple species of birds, including chickens and pigeons. They collected chemical odors from 16 human subjects, including two African Americans, two Chinese, eight Caucasians, three Latinos and one East Indian, who ranged in age from 20 to 55.

They found varying amounts of the substance among the individuals, but everyone produced it. “We didn’t find anybody in our samples who was completely depleted of the compound,” Leal said.

They also baited mosquito traps with a combination of nonanal and carbon dioxide. “We were drawing in as many as 2,000 a night in Yolo County, near Davis,” Syed said. “Nonanal, in combination with carbon dioxide, increased trap captures by more than 50 percent, compared to traps baited with carbon dioxide alone.”

The researchers believe that nonanal results from the breakdown of dietary fatty acids. Eliminating the intake of fatty acids, however, is not the answer to preventing mosquito bites, Leal said. “You can’t get rid of fatty acids,” he said. “We need them.”

Moreover, finding ways to block nonanal may not be the route to mosquito control. First, humans produce varying levels of the substance and scientists do not yet know the effects of different amounts on mosquito behavior. In fact, in some cases insects are drawn by small amounts of attractants, while repelled by high amounts.

“We know there are variations in how much nonanal humans produce, but we don’t know whether they are related to more or less attraction,” Leal said. “We want to go back to the field and try different doses of nonanal to see if mosquitoes are attracted by more levels - or whether there is a point where the attraction starts to decline.”

Furthermore, researchers also need to learn more about the body’s natural repellants, since these, too, likely play a role in controlling mosquito bites. “It’s very common to hear stories about people who go into the field and one gets lots of mosquito bites, while another person doesn’t get any,” Leal said.

“All of us make natural repellants and attractants, so we could be dealing with more than one compound,” he added. “Some of us may be very attractive to mosquitoes--not necessarily because we generate nonanal, but because we don’t generate the natural repellent. We don’t know all the chemicals yet. People are saying: ‘now you can mask nonanal and everything will be solved.’ It’s very appealing to say that, but it’s not that simple.”

In 2008 Leal and his team discovered how the insecticide DEET repels mosquitoes. Scientists had long thought that DEET, an insect repellent developed more than 50 years ago by the U.S. Department of Agriculture, works by masking a human’s smell or by jamming the insect’s senses, interfering with its ability to locate a host. But Leal showed that mosquitoes can smell DEET--and hate it. They avoid it simply because they dislike its odor.

The nonanal study, which was published in the Proceedings of the National Academy of Sciences, was funded by the National Science Foundation, the National Institutes of Health, and through a cooperative agreement with Bedoukian Research, a supplier of specialty aroma and flavor ingredients headquartered in Connecticut.

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Scientists are developing mind-to-machine technology that could enable people who cannot speak to communicate using their own brain waves and a computer screen.

Recently, neuroscientists at the Mayo Clinic campus in Jacksonville, Fla., demonstrated that brain waves, focusing on a matrix of letters, can project letters onto a monitor - with the goal of eventually typing out words and sentences. For example, by concentrating on the letter "q," that "q" will appear on the screen.
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The technique requires a craniotomy - that is, a surgical incision into the skull - to place electrodes directly onto the surface of the brain. The implanted devices then record electrical activity produced by the firing of nerve cells.

The research is preliminary. However,  it potentially could help millions of people with disorders that result in speech loss, such as, Amyotrophic Lateral Sclerosis - Lou Gehrig's disease - a progressive deterioration of voluntary muscle movement; spinal cord injuries that require a breathing tube;  and "locked-in syndrome," where patients are awake and aware - but are paralyzed everywhere but the eyes. Even certain stroke patients could benefit, the researchers said.

"We want to emphasize that this really is at the beginning," said Jerry Shih, MD, the Mayo scientist who, with Dean Krusienski, PhD., of the University of North Florida, studied the technology in six epilepsy patients.  Still, "I think the potential applications are wide-ranging," he added. "We want to make this a practical type of device that will have an impact on their function, and quality of life."

While researchers have used the technology in the past to see whether such signals could control prosthetic devices, such as arms, this  is believed to be the first research that examines its potential for language.

The researchers studied the technique in epilepsy patients with existing electrodes that had been implanted earlier to monitor their seizures. "These people already had electrodes in their brains, so we didn't have to subject them or anyone else to invasive brain surgery," Shih said.

The scientists wanted to see whether the process was more effective when electrodes were implanted directly onto the surface of the brain - electrocorticography (ECoG) - compared with those placed only on the scalp, known as electroencephalography (EEG.)  The ECoG technique proved faster and more accurate.

"There was a big difference in the quality of information," Shih said. "With EEG, the electrical signals are significantly distorted as they pass through the skin, the scalp fat, the bony skull - all those layers. There just wasn't as clear a signal, compared to ECoG.  Imagine someone with Lou Gehrig's disease trying for five minutes to type out a word, and finding errors in that word. The accuracy wasn't optimal."

In the study, patients sat in front of a monitor that was hooked to a computer running the researchers' software, which was designed to interpret electrical signals coming from the electrodes. The patients looked at the screen, which contained a 6-by-6 matrix with a single letter inside each square. Each time the square with a certain letter flashed, and the patient focused on it, the computer recorded the brain's response to the flashing letter. Then the patients focused a specific letters and the computer software recorded the information.

The computer then calibrated the system with the individual patient's specific brain wave and - when the patient then focused on a letter - the letter appeared on the screen.

If perfected, the technology could help people "with any neurologic disease that impacts a person's ability to effectively communicate, as long as they can attend to the task," Shih said, adding: "It won't work, for example, in people who are demented."

Even certain stroke patients - those whose attack occurred in the brain stem - could benefit, Shih said. "Those patients can't talk because the pathway to the speech area has been interrupted by the stroke, but the actual center that produces language - the cerebral cortex -  is not involved," he said.

It might even be possible to apply the technology to stroke victims whose language center has been injured. Other areas of the brain may be able to compensate, Shih said. "We actually found that these types of signals can be reported not only from the language center, but from other portions of the brain," he said. "So this still might work even for people whose language area has been destroyed."

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