The research aims to produce valid information and must use reliable instruments that guarantee accurate and make it quantifiable and possible reproducibility. Allowing the exclusion or at least control prejudice of personal insights and trends that may distort the results.
martes, 15 de diciembre de 2009
Under Yellowstone, Magma Pocket 20% Larger Than Thought
Richard A. Lovett in San Francisco
The huge column of molten rock that feeds Yellowstone's "supervolcano" dives deeper and fills a magma chamber 20 percent bigger than previous estimates, scientists say.
The finding, based on the most detailed model yet of the region's geologic plumbing, suggests that Yellowstone's magma chamber contains even more fuel for a future "supereruption" than anyone had suspected.
The model shows that a 45-mile-wide (72-kilometer-wide) plume of hot, molten rock rises to feed the supervolcano from at least 410 miles (660 kilometers) beneath Earth's surface.
The deepest part of the plume actually sits beneath the town of Wisdom, Montana, about 150 miles (241 kilometers) from Yellowstone National Park (see map).
But the steady flow of hot rock in Earth's upper mantle causes the plume to drift to the southeast, where it fills a magma chamber that sits just 3.7 to 10 miles (5.9 to 16 kilometers) beneath Yellowstone.
Other new data show that Yellowstone's magma chamber extends 13 miles (21 kilometers) farther to the northeast than previously thought.
But that doesn't mean the region is on the verge of exploding, said study leader Robert Smith, a geophysicist at the University of Utah in Salt Lake City.
"This [plume] is the source of Yellowstone's volcanic system," he said. "It doesn't say anything about the probability of a big eruption. [That is] a very rare thing."
Scientists had already known that Yellowstone is a volcanic hot spot, and that within the past two million years, the region has seen three mammoth eruptions at intervals of about 700,000 years.
These supereruptions would have been very dramatic, noted Stephen Self, a volcanologist from Britain's Open University who was not involved in the study.
Such events can produce at least 77 cubic miles (360 cubic kilometers) of basalt: enough to bury Washington, D.C., under nearly 7,200 feet (2,200 meters) of solidified lava, Self said during an October meeting of the Geological Society of America.
Even the largest of the more modern eruptions can't compare, he said. "Supereruptions are very, very much larger. We're talking a factor of a thousand or so."
Luckily for us, eruptions on that scale are rare.
"Compared to our human lifespan, these systems have a very long … gestation period, if you will," Self told National Geographic News. "So we're not going to have an eruption immanently, almost certainly."
Furthermore, he said, magma needs to be relatively fluid and gas-rich before it can erupt.
Otherwise, "it's not going anywhere. … It could stay down there for a long time, or feed little eruptions, which these caldera systems like Yellowstone have done throughout their history."
Study leader Smith agrees, noting that, for Yellowstone, eruptions the size of Mount St. Helens's 1980 blast or Mount Pinatubo's 1991 explosion happen every few tens of thousands of years.
"They're much more probable, but much smaller," he said.
In addition, he said, about once every thousand years or so, Yellowstone's geyser fields explode in steam eruptions covering up to 250 acres (100 hectares). (See pictures and infrared images of Yellowstone's geysers erupting.)
Magma movements may also play a role in triggering major earthquakes in the Yellowstone area, he added. The most recent Yellowstone quake was a magnitude 7.3 in 1959, which killed 28 people.
Yellowstone Plume Even Deeper?
Smith's team has been studying the Yellowstone caldera for years, using ever-more-sensitive instruments to find the source of the magma that fuels all this activity.
The new model of the plume is largely based on data from an array of super-sensitive seismometers set out in a 400-mile-long (644-kilometer-long) pattern focused on the Yellowstone region.
"A seismometer network is just like an antenna," said Smith, who will be presenting his team's work this week during the 2009 fall meeting of the American Geophysical Union in San Francisco.
"You're listening for seismic waves that come into your antenna. You want it wide enough and long enough that you can detect these things coming up from the interior."
Supereruptions aside, Smith thinks the coolest part of the new study, published in the current issue of the Journal of Volcanology and Geothermal Research, is that the heat source for Yellowstone's famous geyser basins can be traced so deeply.
And Smith suspects that even more sensitive instruments will someday reveal that the magma source goes deeper yet.
"Ultimately," he said, "the plumbing from the geysers may go clear down to the [lower] mantle"—at least 466 miles (750 kilometers) beneath Earth's surface.
Publicado por Nathaniel en 15:39 No hay comentarios:
Ten Environmental Losses of 2009
Global Warming Not Going Gently
2009 saw vast patches of the planet protected and world leaders pledge to fight global warming, but the climate continued to change dramatically--putting it in the "loss" column for the environment this year, according to experts .
Joshua Reichert, managing director of the Pew Environment Group in Washington, D.C., said the "overarching problem of climate" is one of many environmental challenges that have worsened.
Conservationist Stuart Pimm added, "This isn't just some gentle sort of warming process, we are in major ways disrupting the climate. The debates now on climate change are whether the consensus is too mild. Many people think the Antarctic and Arctic ice is melting a lot faster than the consensus.
"I think [global warming] would probably be my pick for the gloomiest story" of 2009, added Pimm, a conservation biologist at Duke University.
Oceans Begin to Lose Appetite for Carbon
As the world's greenhouse gas emissions continued to rise this year and further disrupt the global climate, the oceans appeared to lose some of their appetite to absorb carbon dioxide, a key gas implicated in the planet's warming, according to a November study.
The study spanned the years between 2000 and 2007. In that time the amount of carbon from human activity absorbed by the oceans fell from 27 to 24 percent. Why the oceans are less hungry for carbon is unclear, but it may be related to the acidification of the oceans due to too much carbon, according to the study, led by Samar Khatiwala, an oceanographer at Columbia University's Lamont-Doherty Earth Observatory.
Drought-Stricken Kenya Loses Out on Rain, Again
Tens of elephants and hundreds of other animals have perished so far amid the worst drought to hit Kenya in more than a decade, conservationists announced this past summer. The so-called long rains, which usually bring relief to the region in March and April, never arrived this year, extending the drought into its third year for parts of the East African country.
Why the drought is occurring is unknown. Some people blame global climate change. Others say it's due to long-term weather cycles.
Whatever the cause, the drought has driven cattle herders to illegally bring their animals deep into Kenya's parks and reserves in search of water, where they outcompete wildlife for a drink. "It's really been a body blow to our animals," Paul Udoto, a spokesperson for the Kenya Wildlife Service.
Wolves Lose Protection, Hunts Begin
In May the U.S. Fish and Wildlife Service formally removed the gray wolf in the northern Rockies from protection under the federal Endangered Species Act, which some conservationists saw as a loss for the environment. A few months late, wildlife managers in Idaho and Montana approved the first wolf hunts in decades.
Hunters began legally pursuing wolves on September 1 in Idaho. As of November 30, 114 wolves had been killed in Idaho. Montana's season closed November 16 with 74 killed.
A coalition of conservation groups, including Defenders of Wildlife and the Center for Biological Diversity, had lost a court appeal to halt the hunts. The groups argue that the hunts will likely genetically isolate subgroups of the wolf population, threatening its ability to recover to sustainable levels.
"Although the court's decision to leave wolves unprotected is a setback for recovery, we hope it is a temporary one," Noah Greenwald, endangered species program director for the Center for Biological Diversity, said in a media statement.
Caribbean Loses Sharks, Barracudas
Some sharks and barracuda species no longer roam the reefs of the Caribbean, scientists announced in May. Fishers have wiped reefs clean of the big predators.
Smaller predators, such as invasive Pacific lionfish that escaped from aquariums, have begun to fill in the niches left by the bigger fish, sending the coral reef community into flux.
"Healthy and intact coral reefs need large predatory fish in order to continue to provide human societies with food and with beauty," study author Chris Stallings, a researcher at Florida State University's Coastal and Marine Laboratory.
The loss of predators is part of the "litany of doom and despair" that Duke University's Pimm said befalls the environmental movement every year. "We are still chopping down the forest, we are still dumping a lot of greenhouse gases in the atmosphere, we are still overfishing," he said.
Hope Lost for the Arctic Ice Sheet?
The Arctic ice cap has been on a steady, staggered march toward its summer-time death for more than a decade. This year the idea of an Arctic Sea devoid of ice in summers resonated with the public, according to Bill Eichbaum, a vice president with the international conservation group WWF.
The loss of the ice "puts at risk iconic figures like the polar bear, the walrus--and it also puts at risk the people that live sustainably with that wildlife in their regions," Eichbaum said. "I think we realize that that is happening in the Arctic and that it is a huge loss."
Carbon Monitoring Satellite Crashes
A satellite meant to orbit the Earth and monitor global carbon dioxide emissions suffered a glitch at takeoff in February and crashed into the ocean near Antarctica.
Researchers had hoped the Orbiting Carbon Observatory would provide new insights into the distribution of the greenhouse gases around the globe—data that could have improved climate predictions.
NASA officials called the U.S. $270 million mission, under development for nine years, a total loss.
Lemurs Added to Bush-meat Menu
Until a March coup d'etat stirred up political unrest on the African island nation of Madagascar>, lemurs had largely escaped the fate of other primates hunted as bush meat. That has changed, conservationists reported in August.
Criminal gangs are now fueling demand for the primates among well-to-do restaurant patrons.
The turn of events is one of the more visible conservation setbacks since President Marc Ravalomanana was ousted from office and all foreign funding to keep the nation's national parks running was cut off.
"More than anything else, these poachers are killing the goose that laid the golden egg, wiping out the very animals that people most want to see and undercutting the country and especially local communities by robbing them of future conservation revenue," Russell Mittermeier, President of Conservation International, said in media statement.
NASA Satellite Highlights India Groundwater Loss
NASA scientists used a pair of tandem orbiting satellites called the Gravity Recovery and Climate Experiment, or GRACE, to get a read on how quickly the groundwater is disappearing under northern India's heavily irrigated fields of wheat, rice, and barley.
The findings, reported in August in the journal Nature, show that 26 cubic miles (109 cubic kilometers) vanished between 2002 and 2008. The discovery suggests that current water use rates are unsustainable and, if continued, will eventually impact the nation's food supply, said Sandra Postel, director of the Global Water Policy Project.
"We are already beginning to see this happen in parts of India where wells have already been taken out of production because it has either gotten too expensive to pump the water from deeper down or the wells are just too salty or dry," she said.
Health Care, Economy Steal Environment's U.S. Political Momentum
Environmental issues were in the spotlight this year when U.S. President Barack Obama appointed leading scientists to top government posts, such as Secretary of Energy Steven Chu and National Oceanic and Atmospheric Association Administrator Jane Lubchenco.
But that light dimmed as the administration tackled a faltering economy, debated a national health care policy, and delayed action on an energy bill that would have curbed domestic greenhouse gas emissions.
"They've been able to devote less of their time and attention than much of the conservation community would have liked to see on the issue of climate," said Joshua Reichert, the managing director of the Pew Environment Group, a Washington, D.C.-based international environmental policy group.
Publicado por Nathaniel en 15:17 No hay comentarios:
Like a silver spear
Like a silver spear cast from the heavens, the bright streak of a Geminid meteor pierces the night sky over California's Mojave Desert during the annual meteor shower's 2009 peak.
Geminids are slower than other shooting stars and are known to make beautiful long arcs across the sky. This could be because they're born of debris from a dormant comet and so are made mostly of hard, sun-baked rock that takes longer to burn up in Earth's atmosphere, experts suggest.
Publicado por Nathaniel en 15:16 No hay comentarios:
The fennec fox is the smallest of all the world's foxes, but its large ears, measuring 6 inches (15 centimeters), appear to be on loan from a bigger relative.
Fennec foxes dwell in the sandy Sahara Desert and elsewhere in North Africa. Their nocturnal habits help them deal with the searing heat of the desert environment, and some physical adaptations help as well.
Their distinctive, batlike ears radiate body heat and help keep the foxes cool. They also have long, thick hair that insulates them during cold nights and protects them from hot sun during the day. Even the fox's feet are hairy, which helps them perform like snowshoes and protects them from extremely hot sand. The fox's feet are also effective shovels for frequent digging—fennec foxes live in underground dens.
These foxes dwell in small communities, each inhabited by perhaps ten individuals. Like other canids, male fennecs mark their territory with urine and become aggressive competitors when mating season arrives each year.
Fennec foxes are opportunistic eaters. They forage for plants but also eat rodents, eggs, reptiles, and insects. Like most desert dwellers, the fennec fox has developed the ability to go for long periods without water.
These foxes are cream-colored with black-tipped tails. Their adorable appearance makes them favorites of the captive pet trade, and local peoples also hunt the fennec fox for its fur. Little is known about the status of wild fennec fox populations.
Publicado por Nathaniel en 15:14 No hay comentarios:
martes, 8 de diciembre de 2009
New Mexico Spaceport Designs Unveiled
Architects and officials last week unveiled the planned design for Spaceport America's 100,000-square-foot (9,300-square-meter) main terminal, pictured above.
The southern New Mexico facility will serve as home base for Virgin Galactic, a space-tourism company started by Virgin Atlantic Airways founder Richard Branson.
According to the designers, the facility will blend into its dusty surroundings to resemble a rise in the desert floor. Groundbreaking on the low-lying structure—a collaboration between the URS corporation and the Foster and Partners architecture firm, is scheduled for early 2008.
Funding in the amount of 198 million U.S. dollars has been in place since April, when residents of New Mexico's Dona Ana County approved a tax to finance the project. (Read "Spaceport Plan Divides New Mexico Voters" [April 3, 2007].)
A computer rendering shows the planned Spaceport America terminal and hangar from above.
The terminal building, is estimated to cost approximately 31 million U.S. dollars. It is supposed to be model of eco-design, developers say, with few energy requirements and minimal "embodied carbon"—the amount of carbon dioxide emitted during the production of the building.
Much of the structure will be dug into the landscape, helping to buffer the interior from the extremes of the hot and sunny New Mexico climate. The building will also feature electricity-producing photovoltaic cells and a system for storing and reusing water.
The designers hope to achieve a platinum Leadership in Energy and Environmental Design (LEED) rating from the U.S. Green Building Council—the group's highest certification.
The passageway into the planned Spaceport America terminal, shown here, will have museum-like displays of New Mexico's place in the history of space exploration, dating back to Robert Goddard's rocket experiments in Roswell in the 1920s.
The developers of the spaceport hope to create a major tourist destination on a desolate pocket of land 45 miles (72 kilometers) northeast of Las Cruces that will draw architecture buffs as well as space enthusiasts.
Publicado por Nathaniel en 10:15 No hay comentarios:
Virgin Galactic Unveils First Tourist Spaceship
Aspiring space tourists got a first look at their future ride late Monday, when Virgin Galactic unveiled the first of its long-awaited SpaceShipTwo planes (pictured with wings folded upward, suspended from the middle of its twin-fuselage launch vehicle).
After years of teases, the world's only commercial spacecraft rolled out onto the tarmac at the Mojave Air and Space Port in California. There, California Governor Arnold Schwarzenegger and New Mexico Governor Bill Richardson christened the Virgin Galactic craft with the customary smashing of champagne bottles.
Virgin Galactic leader Sir Richard Branson's daughter, Holly, announced the first SpaceShipTwo plane's name: V.S.S. Enterprise, short for Virgin Space Ship Enterprise, said Virgin Galactic President Will Whitehorn.
Virgin Galactic chose "Enterprise" for its long tradition in maritime and aviation history, he said.
"It was the name of the first [NASA] space shuttle, and it has dominated science fiction as a kind of watchword for human spaceflight in the future," Whitehorn said.
Virgin Galactic Holds a Wedding
V.S.S. Enterprise is based on SpaceShipOne, a reusable manned spacecraft designed by aviation designer Burt Rutan, which won the U.S. $10-million Ansari X Prize in 2004. (Related: fast facts on Virgin Galactic's SpaceShipOne.)
Whitehorn said the Enterprise had recently been "married" to EVE, the twin-fuselage mother ship that will ferry it to launch altitude, about 50,000 feet (15,200 meters)—the space shuttle, by contrast, separates from its booster rockets at about 150,000 feet (45,700 meters). (See pictures of Virgin Galactic's Richard Branson unveiling EVE last year.)
Enterprise is the first of five planned SpaceShipTwo planes. It measures 60 feet (18 meters) long and is intended to carry two pilots and six passengers, who will pay handsomely for two-and-a-half-hour flights into suborbital space, where they'll experience weightlessness and see the curvature of the Earth.
Monday's unveiling was attended by some of the 300 or so potential passengers who have already put down at least a deposit on a U.S. $200,000 Virgin Galactic ticket.
"We've all been patiently waiting to see exactly what the vehicle is going to look like," Virgin Galactic ticket holder Peter Cheney of Seattle said in a statement. "It would be nice to see it in the flesh."
Virgin Galactic ticket holder Adrian Reynard—an Indy-car designer, vehicle-engineering consultant, and in a joint venture with Branson's Virgin Atlantic airline, a supplier to airliner builders—called Enterprise an "awesome sight."
"The first thing that strikes you is its size," Reynard said. "It's far bigger than SpaceShipOne. This is a massive vehicle, and I can fully understand how [six passengers] will be able to float around in the cabin area."
Reynard added that the space plane is "aerodynamically beautiful."
"I know you can't always say that if it looks right, it's going to fly right, but I can see that there's been a lot of development put into the shape," he said.
Virgin Galactic in a "Race With Safety"
In the coming months Enterprise will undergo a battery of ground and flight tests designed to test the craft's safety.
The exact date of the first suborbital passenger flight has not been set yet but is expected to occur sometime in 2011.
"We're looking at a test program that will stretch for at least 18 months," Whitehorn said.
"This is a unique project and we're not in a race with anyone. We're only in a race with safety."
Roger Launius is a spaceflight historian at the National Air and Space Museum in Washington, D.C.
Launius said he's less concerned about the safety of Virgin Galactic's space plane than he is about the company's ability to make money off its suborbital venture.
"I hope they succeed, but I'm not sure they'll be able to," Launius said.
"The problem is, what's the market? There is a community of very wealthy adventurers who want to do this, but how large is it?"
If too few people decide to book a ticket, the V.S.S. Enterprise could end up being for Branson what the supersonic Concord jet was to British Airways and Air France in the 1970s, Luanius said.
"The Concord was never commercially viable. They flew it for almost 30 years as a money-loss operation," he said.
"Sir Richard might conceivably want to do the same thing."
Publicado por Nathaniel en 10:13 No hay comentarios:
At a settlement in what is now southern Germany, the menu turned gruesome 7,000 years ago. Over a period of perhaps a few decades, hundreds of people
To save the world from the real threat of a major asteroid impact, one engineer has imagined a scheme similar to George Bailey’s wish to lasso the moon for his sweetheart in “It’s a Wonderful Life.”
The plan is to attach a gigantic weight to an Earth-bound asteroid using an enormous cord. This crazy-sounding contraption would change the asteroid’s center of mass and subsequently its trajectory, averting a potentially catastrophic scenario.
neodeflection1Aerospace engineer Major David French of the Air Force Research Labs mathematically modeled how different weights and lengths of tether would affect a killer asteroid’s orbit over time. The results are in the December issue of Acta Astronautica.
He found that, in general, longer tethers and larger masses would more significantly change the asteroid’s orbit. The alteration would occur slowly, taking anywhere from 10 to 50 years.
The technique would require no simple mission. The cosmic counterweight would weigh a few million pounds, about the mass of a Saturn V rocket. And even more impressively, the rope would range anywhere from six miles (about the height of Mount Everest), to 60,000 miles (long enough to wrap around Earth two and a half times).
This solution may sound unrealistic, but the threat is real. To date, NASA’s Near Earth Object Program, which tracks asteroids and comets that could approach the planet, has cataloged more than 5,500 objects. About 1,000 of these are classified as “potentially hazardous,” meaning they could wipe out a city, spawn giant tsunamis or, in the worst case, eradicate life with a planet-shrouding cloud of debris.
To guard against this, scientists have produced many dramatic proposals, each with its own merits. French thinks his technique stands out for its relative ease.
“What interested me was that there is no active control system needed,” he said. Once the rope and weight were installed, the asteroid would get nudged through nothing but the laws of gravity.
However, the method is not lacking critics.
“This tether-deflection idea is an interesting intellectual exercise,” said astronomer David Morrison of the Asteroid and Comet Impact Hazards Group at NASA’s Ames Research Center. “But it is of no practical value.”
Morrison points out that putting enormous objects, such as a heavy tether and ballast, in space is far beyond the entire human race’s launch capability. Furthermore, the cost of designing and building a strong enough rope makes the solution intractable.
“From a practical point of view, the technique is a mess,” agreed Russell Schweickart, former Apollo astronaut and co-founder of the B612 Foundation, a group dedicated to protecting the Earth from asteroid strikes. He is concerned that no one knows how to hook a tether to a spinning asteroid and, once attached, there is no guarantee the line won’t get tangled up.
Schweickart and Morrison offer a much simpler idea that uses current technology: Change the asteroid’s orbit by crashing something into it. Even a relatively small satellite would alter the orbit enough to stave off certain doom, if we did it far enough in advance.
French understands these criticisms and thinks they are well-founded. But, he said Earth will still need protection from asteroids in the next century, and the next millennium. If our technology and expertise isn’t enough to lasso an asteroid right now, we have time.
“The last extinction-level asteroid strike was 65 million years ago,” he said, “I think it’s important to take the long view and maybe dig into technology that is not quite ready.”
Editor’s note: This story was updated Dec. 7 to say that a weight of a few million pounds would be enough for the counterbalance.
Publicado por Nathaniel en 10:07 No hay comentarios:
Controversial Signs of Mass Cannibalism
At a settlement in what is now southern Germany, the menu turned gruesome 7,000 years ago. Over a period of perhaps a few decades, hundreds of people were butchered and eaten before parts of their bodies were thrown into oval pits, a new study suggests.
sciencenewsCannibalism at the village, now called Herxheim, may have occurred during ceremonies in which people from near and far brought slaves, war prisoners or other dependents for ritual sacrifice, propose anthropologist Bruno Boulestin of the University of Bordeaux 1 in France and his colleagues. A social and political crisis in central Europe at that time triggered various forms of violence, the researchers suspect.
“Human sacrifice at Herxheim is a hypothesis that’s difficult to prove right now, but we have evidence that several hundred people were eaten over a brief period,” Boulestin says. Skeletal markings indicate that human bodies were butchered in the same way as animals.
Herxheim offers rare evidence of cannibalism during Europe’s early Neolithic period, when farming first spread, the researchers report in the December Antiquity. Artifacts found at Herxheim come from the Linear Pottery Culture, which flourished in western and central Europe from about 7,500 to 7,000 years ago.
Two archaeologists who have studied human bones unearthed a decade ago at Herxheim reject the new cannibalism hypothesis. In a joint statement to Science News, Jörg Orschiedt of the University of Leipzig in Germany and Miriam Haidle of Senckenberg Research Institute and Natural History Museum in Frankfurt say that Boulestin’s evidence better fits a scenario in which the dead were reburied at Herxheim following dismemberment and removal of flesh from bones. Evidence of ceremonial reburial practices has been reported for many ancient societies.
Publicado por Nathaniel en 10:05 No hay comentarios:
3 Bets the DOE Is Placing on Science to Break the Climate Stalemate
The Advanced Research Projects Agency for energy put out its second call for new ideas, and this time, the agency has narrowed its focused to three research fields.
The new arm of the Department of Energy, which is dedicated to high-risk, high-reward innovations, is betting $100 million on batteries for cars, new materials for capturing carbon, and microorganisms that can convert sunlight and carbon dioxide directly into fuels.
“This solicitation focuses on three cutting-edge technology areas which could have a transformational impact,” said Energy Secretary Steven Chu, in a release.
Energy gets used in a lot of different ways, so no single technology can make all the difference. That said, a few key pieces of technology would provide the political world with better clean-energy options. We use coal to make half the nation’s electricity. Fossil fuels, mostly oil, burned for transportation account for roughly one-third of American emissions. Finding cheaper, cleaner solutions to the key problems of baseload generation and fuel for cars would be major steps toward reducing carbon emission and dependence on foreign oil.
This is the second call for proposals the DOE outfit has issued. ARPA is modeled after the military’s Defense Advanced Research Projects Agency. This new request is as narrow as the last was wide. In the first grants announced in October, ARPA-E spread the first $150 million from its coffers broadly on 37 different technologies across the energy landscape from building efficiency to biomass conversion to waste heat capture. Each endeavor received between $500,000 and $9 million
Publicado por Nathaniel en 9:53 No hay comentarios:
Wired Science News for Your Neurons Printable, Moldable Batteries Made From Paper and Nanotubes
Those who are quick to dismiss paper as old-fashioned should hold off on the trash talk. Scientists have made batteries and supercapacitors with little more than ordinary office paper and some carbon and silver nanomaterials. The research, published online December 7 in Proceedings of the National Academy of Sciences, brings scientists closer to lightweight printable batteries that may one day be molded into computers, cell phones or solar panels.
sciencenews“Power storage is one of the very important aspects of solving the energy issue,” comments Robert Linhardt of Rensselaer Polytechnic Institute in Troy, N.Y. The paper-based devices show excellent performance.
That performance is largely due to paper’s porous nature: at the nano scale, paper is a tangled matrix of fibers. This vast surface area helps inks stick, says Yi Cui of Stanford University, coauthor of the new work. This holds true for carbon nanotube ink as well. When carbon-nanotube ink touches paper, the nanotubes “get caught very tightly to the cellulose,” says Cui, probably just via good old electrostatic forces.
The paper acts as a scaffold, and the carbon nanotubes act as electrodes that electrolytes in solution react with. This nanotube-paper combination offers a lightweight alternative to traditional energy storage devices that rely on metals.
Publicado por Nathaniel en 9:40 No hay comentarios:
jueves, 3 de diciembre de 2009
"Shangri-La" Caves Yield Treasures, Skeletons
ON TV Lost Cave Temples of the Himalayas and Secrets of Shangri-La premiere Wednesday, November 18, on PBS (check local listings.).
A treasure trove of Tibetan art and manuscripts uncovered in "sky high" Himalayan caves could be linked to the storybook paradise of Shangri-La, says the team that made the discovery.
The 15th-century religious texts and wall paintings were found in caves carved into sheer cliffs in the ancient kingdom of Mustang—today part of Nepal. (See pictures of the "Shangri-La" caves and their treasures.)
Few have been able to explore the mysterious caves, since Upper Mustang is a restricted area of Nepal that was long closed to outsiders. Today only a thousand foreigners a year are allowed into the region.
In 2007 a team co-led by U.S. researcher and Himalaya expert Broughton Coburn and veteran mountaineer Pete Athans scaled the crumbling cliffs on a mission to explore the human-made caves.
Inside the caves, the team found ancient Tibetan Buddhist shrines decorated with exquisitely painted murals, including a 55-panel depiction of Buddha's life. (See a picture of one of the Buddhist murals.)
A second expedition in 2008 discovered several 600-year-old human skeletons and recovered reams of precious manuscripts, some with small paintings known as illuminations.
Publicado por Nathaniel en 14:47 No hay comentarios:
Biggest Star Explosion Seen; Was Rare, "Clean" Death
The biggest star explosion yet seen may be the best known example of a rare type of star death that leaves no "body" behind, astronomers say.
The unusual blast, dubbed SN 2007bi, appears to be a textbook example of a pair-instability supernova, a theoretical type of explosion proposed for very massive stars—those more than 140 times the mass of the sun.
Although most supernovae leave behind black holes or dense stellar corpses called neutron stars, pair-instability explosions would be so intense that the whole star would be obliterated.
Pair-instability supernovae have been hard to spot, however, because stars more than a hundred times the sun's mass are extremely rare.
Spied in images of a distant dwarf galaxy taken by an automated telescope, SN 2007bi was about 40 times brighter than a typical supernova, and it took about three times longer to reach its maximum brightness.
"Anything that takes that long to rise and is that bright has to have a lot of mass," said study co-author Peter Nugent, an astrophysicist at the Lawrence Berkley National Laboratory in California.
Hot Core, Unstable Star
Massive stars normally die when they run out of material to sustain nuclear fusion, and all that's left in their cores is inert iron.
This means the core is no longer producing a steady stream of photons, which in a living star creates outward pressure, keeping the star from being crushed by its own gravity.
Without this stable outward pressure, the star collapses, generating a supernova in which the core gets crunched down to form a black hole or a neutron star.
But for even more massive stellar titans, astronomers think the cores quickly get so hot that their photons start to split apart into pairs of electrons and positrons.
This leads to an instability between the star's temperature and pressure, sparking a devastating explosion that flings the star's remains into space.
The star effectively vanishes, although a lingering cloud of expanding gas can remain visible for a while.
Big Star Explosions Seeded Early Universe?
Pair-instability supernovae were first predicted more than 30 years ago. But evidence from previous candidates—including a bright explosion seen in 1999 and another in 2006—were inconclusive, Nugent said.
By contrast, SN 2007bi seems to fit the bill almost perfectly. If confirmed, studies of the newfound supernova could have major implications for computer models of star formation in the early universe, Nugent said.
That's because pair-instability supernovae were likely much more frequent in the early universe, when stars with masses several hundred times that of our sun are thought to have existed.
When these megastars exploded, the ancient, powerful outbursts scattered debris that might have sown the seeds for future stars.
A pair-instability supernova "may be a one-in-a-trillion type of event," Nugent said, "but they may actually be very important" in understanding the evolution of the universe.
Findings detailed in the December 3 issue of the journal Nature.
Publicado por Nathaniel en 14:45 No hay comentarios:
World's Smallest Orchid Discovered (By Accident)
December 3, 2009--The world's smallest known orchid (pictured)—just over 2 millimeters (0.08 inch) across and nearly see-through—has been discovered nestled in the roots of another flower in Ecuador, scientists announced this week.
Lou Jost, an ecologist with the EcoMinga plant-conservation foundation, has studied the plants of the South American country's mountainous forests for 15 years.
Earlier this year he'd collected an orchid of a larger species to study in his greenhouse. "Several months later I saw this tiny plant," he said.
Ecuador's mountains are havens of biodiversity, where plants on one mountain may be entirely different from those on a neighboring peak.
In the region where the tiny orchid was found, Jost also recently discovered 28 new orchids in the Teagueia genus, a group previously thought to contain only 6 species. Ecuador as a whole is home to 4,000 known orchid species—a thousand of them discovered in the past 12 years alone.
The newfound orchid, part of the Platystele genus, hasn't yet had the type of scientific review that would lead to its official designation as a new species. But, Jost said, orchid expert Carl Luer, a researcher affiliated with the Missouri Botanical Garden, agrees that the plant is a unique species.
The bloom has, for now, no name. "It's just sitting here with lots of others that need to be described," Jost said. "These forests are just filled with new things."
Publicado por Nathaniel en 14:43 No hay comentarios:
Whale-Eaters Surprise Scientists
-A member of a species likely new to science, the Osedax yellow-collared worm feasts on whale bones in 2008. Named for the thin yellow ring that runs around the base of the worm's feathery structures--thought to be used for respiration--the species lives below 3,280 feet (1,000 meters).
The first known Osedax worms, which tend to feed on whale remains, were first scientifically described in 2004. A short five years later, new types of the bone-eating worms are turning up as fast as scientists can study them. (See "New Worms Eat (and Eat and Eat) Only on Dead Whales.")
So far, scientists have confirmed five Osedax species, which live between 82 feet to 9,842 feet (25 to 3,000 meters) deep in the Pacific and Atlantic Oceans. And in November researchers from the Monterey Bay Aquarium Research Institute revealed evidence of 12 more potentially new species, including the yellow-collar, all found in the undersea canyon off Monterey, California.
All the potential new bone-eating worms announced in November by Monterey Bay scientists were found on whale carcasses the scientists dragged out to sea. Whale bones, like this skull pictured 1.1 miles (1,800 meters) underwater in 2006, present a remarkable feeding opportunity for bone-eating worms, but the feast isn't for everyone.
While female worms can readily attach to the bone and begin feeding, male worms are too small to do so. Instead, they tend to dwell inside gelatinous tubes surrounding the bodies of females and do little more than produce sperm.
At roughly two millimeters long, the bone-eating worm species pictured above in 2009, is among the smallest known.
The minuscule Osedax variety, which has yet to be formally named, has "probably been overlooked in the past because they are nearly invisible," said marine biologist Robert Vrijenhoek, who led the Monterey Bay Aquarium Research Institute study. The worms' bodies are transparent and lack the showy, feathery, plumes that make many of their bone-eating kin comparatively easy to spot.
An Osedax orange-collar worm--another of the potential new species announced in November 2009--releases barely visible, speck-like eggs in Monterey Canyon in 2008.
"We are really lucky at the Monterey Bay Aquarium Research Institute to have robotic submarines equipped with high-definition cameras that can capture images like this at 1,000 meters [0.6 mile] depth," study leader Vrijenhoek said.
The newfound undersea worms--such as this still-unnamed variety pictured after it had been separated from its bone perch for study in 2009--likely eat by absorbing bone nutrients through their bulbous roots.
"They have no anus, no mouth, no digestive tract that we can detect, so we think the roots are the only ways for them to feed," Vrijenhoek said. Under normal circumstances, when embedded in bone, the roots are invisible.
As yet unnamed--but nicknamed Osedax spiral--this potentially new species of worm lives in mud near bones, rather than directly on bones. When the Monterey Bay team excavated the worms, the researchers found that their long roots penetrated buried bone shards.
"This is particularly exciting to us, because it suggests an answer to the question of why [there are] so many species of bone-feeding worms," Vrijenhoek said. "They appear to be filling different roles in the bone-consumption process. We never expected to find this level of diversity among these animals."
Publicado por Nathaniel en 14:39 No hay comentarios:
A jet of high-energy particles shooting from a black hole (left) ignites stars in a nearby galaxy in an artist's rendering. Two new studies based on data from the European Southern Observatory suggest that the nearby active black hole HE0450-2958 is creating its future home by "zapping" a nearby galaxy, triggering rapid star formation.
Most large galaxies are thought to have supermassive black holes in their middles, although scientists haven't been sure which comes first, the galaxy or the black hole. HE0450-2958 has no identified host galaxy of its own. But the black hole's jet is feeding a companion galaxy, which is forming stars at a rate of about 350 suns a year--a hundred times the rate of a typical galaxy. Astronomers think the two objects will eventually merge, creating a full-fledged galaxy with a black hole at its heart.
Publicado por Nathaniel en 14:38 No hay comentarios:
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