viernes, 29 de mayo de 2009
Imagine being able to detect in just a few minutes whether someone is infected with a virus. This has now become a reality, thanks to a new ultra-sensitive detector that has been developed by Ostendum, a spin-off company of the University of Twente.
The company has just completed the first prototype and expects to be able to introduce the first version of the detector onto the market in late 2010. Not only does the detector carry out measurements many times faster than do standard techniques, it is also portable, so it can be used anywhere.
Ostendum’s Aurel Ymeti (R&D director), Alma Dudia (Senior Researcher) and Paul Nederkoorn (CEO) claim that if they had the right antibodies to the swine flu at their disposal, they would be able to highlight the presence of the virus within five minutes. In addition to viruses, the device is also able to pick up bacteria, proteins and DNA molecules.
Following the outbreak of swine flu, the issue of finding a means of detecting quickly and simply whether someone is infected with a virus is again very much on the agenda. It is important to be able to do so as soon as possible in order to prevent the virus from spreading further. However, the techniques that are currently available do not yield results for several hours or even days. Moreover, the tests cannot be carried out without a laboratory or trained personnel.
Researchers at Ostendum, a spin-off company of the University of Twente, have developed a portable device that can show in five minutes whether or not a person is infected with a particular virus. The system is able to detect not only viruses, but also specific bacteria, proteins and DNA molecules, an increased or reduced concentration of which in a person’s saliva may be an indication that they have one illness or another.
The only thing needed by the Ostendum detection method is a sample of saliva, blood or another body fluid from the person being tested and the availability of a specific receptor (i.e. a substance that binds with a specific micro-organism or biological substance). For example, in the case of a virus, a specific antibody served as a receptor on the chip and such antibody to that virus has to be available in order to be able to apply the underlying detection method.
Ymeti demonstrated during his doctoral research in 2007 that the principle behind the detector worked. At the time, he used a fairly sizeable laboratory set-up. The Ostendum company was subsequently founded, in 2008, in order to develop the principle into a marketable product.
The company has just completed the first prototype of the device, and it is presently working on two others. The three prototypes are undergoing practical tests, in a collaboration involving the Laboratorium Microbiologie Twente Achterhoek and the Zwanenberg Food Group. Ostendum will then make further improvements to the design of the device on the basis of the test results, and expects to have the first device ready for introduction to the marketplace in late 2010.
How it works
The device consists of two parts: a lab-on-a-chip-system and a portable detector. A lab-on-a-chip is a miniature laboratory the size of a chip. The chip contains tiny channels that are coated with receptors. The blood or saliva sample is transported to the channels with the help of a fluid system. Substances from the saliva or blood can then bind with the receptors on the chip. Light from a laser is guided through the channels. If any of the substances binds with the receptors in any of the channels, this will alter the phase of the light. Such a change will manifest itself in the interference pattern, and is a fingerprint of any viruses present, for example, or biomarkers. The method is highly sensitive: it is possible to measure the binding of a single virus particle.
An explosion of knowledge has been made in the last few years about the basic biology of corals, researchers say in a new report, helping to explain why coral reefs around the world are collapsing and what it will take for them to survive a gauntlet of climate change and ocean acidification.
Corals, it appears, have a genetic complexity that rivals that of humans, have sophisticated systems of biological communication that are being stressed by global change, and are only able to survive based on proper function of an intricate symbiotic relationship with algae that live within their bodies.
After being a highly successful life form for 250 million years, disruptions in these biological and communication systems are the underlying cause of the coral bleaching and collapse of coral reef ecosystems around the world, scientists report in the journal Science.
The research was funded in part by the National Science Foundation.
"We've known for some time the general functioning of corals and the problems they are facing from climate change," said Virginia Weis, a professor of zoology at Oregon State University. "But until just recently, much less has been known about their fundamental biology, genome structure and internal communication. Only when we really understand how their physiology works will we know if they can adapt to climate changes, or ways that we might help."
Corals are tiny animals, polyps that exist as genetically identical individuals, and can eat, defend themselves and kill plankton for food. In the process they also secrete calcium carbonate that becomes the basis for an external skeleton on which they sit. These calcified deposits can grow to enormous sizes over long periods of time and form coral reefs – one of the world's most productive ecosystems, which can harbor more than 4,000 species of fish and many other marine life forms.
But corals are not really self sufficient. Within their bodies they harbor highly productive algae – a form of marine plant life – that can "fix" carbon, use the energy of the sun to conduct photosynthesis and produce sugars.
"Some of these algae that live within corals are amazingly productive, and in some cases give 95 percent of the sugars they produce to the coral to use for energy," Weis said. "In return the algae gain nitrogen, a limiting nutrient in the ocean, by feeding off the waste from the coral. It's a finely developed symbiotic relationship."
What scientists are learning, however, is that this relationship is also based on a delicate communication process from the algae to the coral, telling it that the algae belong there, and that everything is fine. Otherwise the corals would treat the algae as a parasite or invader and attempt to kill it.
"Even though the coral depends on the algae for much of its food, it may be largely unaware of its presence," Weis said. "We now believe that this is what's happening when the water warms or something else stresses the coral – the communication from the algae to the coral breaks down, the all-is-well message doesn't get through, the algae essentially comes out of hiding and faces an immune response from the coral."
This internal communication process, Weis said, is not unlike some of the biological processes found in humans and other animals. One of the revelations in recent research, she said, is the enormous complexity of coral biology, and even its similarity to other life forms. A gene that controls skeletal development in humans, for instance, is the identical gene in corals that helps it develop its external skeleton – conserved in the different species over hundreds of millions of years since they parted from a common ancestor on their separate evolutionary paths.
There's still much to learn about this process, researchers said, and tremendous variation in it. For one thing, there are 1,000 species of coral and perhaps thousands of species of algae all mixing and matching in this symbiotic dance. And that variation, experts say, provides at least some hope that combinations will be found which can better adapt to changing conditions of ocean temperature, acidity or other threats.
The problems facing coral reefs are still huge, and increasing. They are being pressured by changes in ocean temperature, pollution, overfishing, sedimentation, acidification, oxidative stress and disease, and the synergistic effect of some of these problems may destroy reefs even when one cause by itself would not. Some estimates have suggested 20 percent of the world's coral reefs are already dead and an additional 24 percent are gravely threatened.
The predicted acidification of the oceans in the next century is expected to decrease coral calcification rates by 50 percent and promote the dissolving of coral skeletons, the researchers noted in their report.
"With some of the new findings about coral symbiosis and calcification, and how it works, coral biologists are now starting to think more outside the box," Weis said. "Maybe there's something we could do to help identify and protect coral species that can survive in different conditions. Perhaps we won't have to just stand by as the coral reefs of the world die and disappear."
Using new data from ESA's XMM-Newton spaceborne observatory, astronomers have probed closer than ever to a supermassive black hole lying deep at the core of a distant active galaxy.
The galaxy – known as 1H0707-495 – was observed during four 48-hr-long orbits of XMM-Newton around Earth, starting in January 2008. The black hole at its centre was thought to be partially obscured from view by intervening clouds of gas and dust, but these current observations have revealed the innermost depths of the galaxy.
"We can now start to map out the region immediately around the black hole," says Andrew Fabian, at the University of Cambridge, who headed the observations and analysis.
X-rays are produced as matter swirls into a supermassive black hole. The X-rays illuminate and are reflected from the matter before its eventual accretion. Iron atoms in the flow imprint characteristic iron lines on the reflected light. The iron lines are distorted in a number of characteristic ways: they are affected by the speed of the orbiting iron atoms, the energy required for the X-rays to escape the black hole's gravitational field, and the spin of the black hole. All these features show that the astronomers are tracking matter to within twice the radius of the black hole itself.
XMM-Newton detected two bright features of iron emission in the reflected X-rays that had never been seen together in an active galaxy. These bright features are known as the iron L and K lines, and they can be so bright only if there is a high abundance of iron. Seeing both in this galaxy suggests that the core is much richer in iron than the rest of the galaxy.
The direct X-ray emission varies in brightness with time. During the observation, the iron L line was bright enough for its variations to be followed.
A painstaking statistical analysis of the data revealed a time lag of 30 seconds between changes in the X-ray light observed directly, and those seen in its reflection from the disc. This delay in the echo enabled the size of the reflecting region to be measured, which leads to an estimate of the mass of the black hole at about 3 to 5 million solar masses.
The observations of the iron lines also reveal that the black hole is spinning very rapidly and eating matter so quickly that it verges on the theoretical limit of its eating ability, swallowing the equivalent of two Earths per hour.
The team are continuing to track the galaxy using their new technique. There is a lot for them to study. Far from being a steady process, like water slipping down a plughole, a feeding black hole is a messy eater. "Accretion is a very messy process because of the magnetic fields that are involved," says Fabian.
Their new technique will enable the astronomers to map out the process in all its glorious complexity, taking them to previously unseen regions at the very edges of this and other supermassive black holes.
Using data from NASA's THEMIS mission, a team of University of Alberta researchers has pinpointed the impact epicenter of an earthbound space storm as it crashes into the atmosphere, and given an advance warning of its arrival.
The team's study reveals that magnetic blast waves can be used to pinpoint and predict the location where space storms dissipate their massive amounts of energy. These storms can dump the equivalent of 50 gigawatts of power, or the output of 10 of the world's largest power stations, into Earth's atmosphere.
The energy that drives space storms originates on the sun. The stream of electrically charged particles in the solar wind carries this energy toward Earth. The solar wind interacts with Earth's magnetic field. Scientists call the process that begins with Earth's magnetic field capturing energy and ends with its release into the atmosphere a geomagnetic substorm.
"Substorm onset occurs when Earth's magnetic field suddenly and dramatically releases energy previously captured by the solar wind," said David Sibeck, project scientist for the Time History of Events and Macroscale Interactions During Substorms (THEMIS) mission at NASA Goddard Spaceflight Center in Greenbelt, Md.
Physicists Jonathan Rae and Ian Mann lead the University of Alberta research team that recently located a substorm's epicenter of the impact. The team uses ground-based observatories spread across northern Canada and the five satellites of the THEMIS mission to detect magnetic disturbances as storms crash into the atmosphere. Using a technique the researchers call "space seismology," they look for the eye of the storm hundreds of thousands of miles above Earth.
"We see the benevolent side of space storms in the form of the Northern Lights," said Mann. "When electrically charged particles speed toward Earth and buffet the atmosphere, the result is often a dancing, shimmering light over the polar region." But there is also a hazardous side. Earth's atmosphere protects us from the damaging direct effects of the radiation from space storms, but in space there is nowhere to hide. High-energy, electrically charged particles released by space storms can damage spacecraft. On Earth, disturbances caused by the particles and the electrical currents they carry can interrupt radio communications and global positioning system (GPS) navigation, and damage electric power grids.
Rae and Mann's team has also determined that the magnetic tremors show that the space storm impact into the atmosphere has a unique epicenter, with the eye of the storm located in space beyond the low-Earth orbits of most communication satellites.
Guided by Earth's magnetic field, the magnetic tremors rocket through space toward Earth. These geomagnetic substorms trigger magnetic sensors on the ground as they impact the atmosphere. The effects of these storms, and the most spectacular displays of the Northern Lights, follow a few minutes later.
The objective of NASA's pioneering multi-spacecraft THEMIS mission is to determine what causes geomagnetic substorms. In addition to a well-instrumented fleet of five spacecraft, THEMIS operates a network of ground observatories stretching across Canada and the United States to place the spacecraft observations in their global context. All night long, every night, the observatories take 3-second time resolution snapshots of the aurora and measure corresponding variations in Earth's magnetic field strength and direction every half second.
An analysis of the auroral movies and magnetic variations by Dr. Jonathan Rae from the University of Alberta pinpointed just when and where one substorm explosively released its magnetic energy. "Undulating auroral features and ripples in Earth's magnetic field began at the same time and propagated away from Sanikulaq, Nunavut, Canada at speeds on the order of 60,000 miles per hour, much like the blast wave from a gigantic explosion," said Sibeck. Dr. Rae and his team presented the results on May 25 at the American Geophysical Union meeting in Toronto.
Probing the eye of a space storm and recognizing the advance warning signs are crucial for researchers trying to understand and predict space weather. Key questions about when and how space storms start are still challenging researchers on the THEMIS team. Like forecasters on Earth who predict severe weather, the University of Alberta researchers are using their "space seismology" technique to investigate methods to forecast space storms.
THEMIS is a NASA-funded mission and involves scientists from Canada, the United States, and Europe. Current Canadian activity is funded by the Canadian Space Agency.
Research led by the University of Leicester suggests people today and in future generations should look to the past in order to mitigate the worst effects of climate change.
The dangers of rising sea levels, crop failures and extreme weather were all faced by our ancestors who learnt to adapt and survive in the face of climate change.
Dr Jago Cooper, of the School of Archaeology and Ancient History at the University of Leicester, has been studying the archaeology of climate change in the Caribbean as part of a Leverhulme Early Career Fellowship.
The international study involvess researchers from Britain, Cuba and Canada. Dr Cooper said: “Populations in the Caribbean, from 5000 BC to AD 1492, successfully lived through a 5m rise in relative sea levels, marked variation in annual rainfall and periodic intensification of hurricane activity.
“This research examines the archaeological lessons that can inform current responses to the impacts of climate change in the Caribbean. I have examined the relationship between long and short-term effects of climate change and past human engagement with the geographical, ecological and meteorological consequences.”
“A key focus of the research has been to investigate past mitigation of the impacts of climate change through the analysis of changes in settlement structures, food procurement strategies and household architecture.”
The study is part of a long term project, begun in 1997, that includes a wide-ranging study of archaeological and paleoenvironmental data. Key to the research has been to understand how the past can inform the future.
Said Dr Cooper: “We have acquired archaeological information that has then been closely correlated in space and time with the long and short-term impacts of climate change. It has then been possible to evaluate the relative advantages and disadvantages of past cultural practices in the face of environmental change and establish lessons that will contribute to contemporary mitigation strategies. “
Following the end of the last Ice Age, the people of the Caribbean have had to cope with a relative sea level rise of 5m over 5,000 years. Hurricanes led to storm surges that reached inland more than ever. Groundwater became contaminated with salt and the land was waterlogged.
But the researchers found that far from abandoning life by the coast and moving further inland, people continued to live by the shore- and even built houses on stilts over a lagoon.
An ancient site in Cuba, Los Buchillones, that is currently out to sea “represents a way of living that capitalises on hundreds or even thousands of years of experience.”
Dr Cooper warns that modern settlements are more at risk of flooding because they are constructed in more vulnerable places. In fact, indigenous settlement locations over water could make homes less at risk of flooding as floodwater could flow beneath the homes and inland rather than pour into the houses.
This ongoing research has looked at past mitigation strategies, assessed how pre-Colombian settlements were located close to cave complexes that acted as refuges during times of past hurricanes, how the architecture of homes were constructed from local resources allowing people to rebuild them easily upon their return. It also reveals how local populations diversified their food production to mitigate against resource scarcity.
The research is described in this week’s New Scientist and is available on their online magazine at http://www.newscientist.com/article/mg20227096.600-rising-sea-levels-survival-tips-from-5000-bc.html
When this new species of gigantic tree on Madagascar blossoms, its flowers and fruits may as well form a funeral bouquet: Betting its line's survival on one season's worth of seeds, the Tahina spectabilis palm blossoms only once, then dies.
The self-destructing palm is one of an estimated 15,000 to 20,000 new species discovered annually. Of these, scientists from around the world--working with International Institute for Species Exploration at Arizona State University and using undisclosed criteria--name the "top ten" each year.
"We know so few of the species on Earth," said the institute's founding director Quentin Wheeler. "Life is probably the biggest and most complex scientific story we'll ever explore."
Until last year no one had found microbacteria in artificial chemicals or other man-made products. So the 2008 documentation of a new microbacterial species in off-the-shelf hair spray was a step toward the biosphere's brave new postindustrial future.
It's probably safe to assume that M. hatanonis lived in some natural environment before turning up in beauty aids. Though unknown in nature, the microbug "presumably ... just turned up here as a contaminant," said Quentin Wheeler, director of the institute that put M. hatanonis on the 2009 top ten list of new species.
A previously unproven tool in the planet-hunting arsenal has finally netted its quarry—and it's found an unusual cosmic duo.
Using a technique called astrometry, scientists have spotted an extrasolar planet that's thought to be the same size as its parent star.
By contrast, Jupiter, the largest planet in our solar system, is only a tenth the width of the sun.
The newfound gas giant, called VB 10b, orbits a red dwarf star, a relatively cool, small star less than half the mass of the sun. Although both are roughly the size of Jupiter, the planet orbits the star because the star is much more massive.
VB 10b's discovery is the culmination of a 12-year search using an instrument at California's Palomar Observatory.
The telescope attachment specializes in astrometry, a technique first tried 50 years ago that measures the minute back-and-forth motions of a star created by the gravitational tug of an unseen planet.
Most of the previous planet-hunting attempts have had more luck with the radial velocity—or Doppler wobble—method, which measures stellar movement toward and away from Earth.
Radial velocity and other techniques are better at finding very massive worlds in tight orbits around their stars.
Astrometry, on the other hand, could open the door to finding a whole new class of planets that were difficult to spot before, said study author Stuart Shaklan of NASA's Jet Propulsion Laboratory (JPL) in California.
"It allows you to see planets further from their stars," Shaklan said, because the greater the distance between the two bodies, the more a star seems to shift. "It's also a technique that works well on [spotting] very faint stars.
That aspect of the technique, however, remains unproven. VB 10b, which lies about 20 light-years away in the constellation Aquila, orbits its tiny star at the same distance at which Mercury orbits our sun.
VB 10b is called a "cold Jupiter," because its star is small and dim enough that the planet is not scorched despite its close proximity.
Astronomers think planetary systems with cold Jupiters might be miniature versions of our own, with rocky inner planets and outer gas giants.
It's conceivable that VB 10b has rocky neighbors, Shaklan said, but this would have to be verified with other telescopes.
"This is an exciting discovery, because it shows that planets can be found around extremely lightweight stars," Wesley Traub, a planet hunter at JPL who was not involved in the study, said in a statement.
"This is a hint that nature likes to form planets, even around stars very different from the sun.
By 2100 visitors to Boston could be parking their boats, not their cars, in Harvard Yard.
Major cities in the northeastern U.S. and eastern Canada "are directly in the path of the greatest rise" in sea level if Greenland continues to melt due to global warming, a new study says.
Scientists believe that the influx of fresh water from the disintegrating ice sheets will disrupt a circulation pattern in the Atlantic Ocean, causing seas to expand.
The new projections call for an extra 4 to 12 inches (10.2 to 30.5 centimeters) on top of the rise of 8 inches (20.3 centimeters) previously estimated in the journal Nature Geoscience in March.
That previous study found that, if global warming continues, sea levels around New York City would rise by twice as much as in other parts of the United States within this century.
In the new study, researchers considered three scenarios: that Greenland's present melt rate of 7 percent would continue, or a drop to either one or 3 percent a year—viewed by many as more likely, as the rate is actually expected to slow in coming decades.
"We hope the high end wouldn't happen," said study lead author Aixue Hu of the National Center for Atmospheric Research in Boulder, Colorado.
But "we should be aware that there's a potential the melt of the Greenland ice sheet could be faster than we expected."
Of the three scenarios, the two lower melt rates are more realistic, according to computer models of future ice sheet melting, Hu said.
A 3 percent melt rate would mean an extra 12 inches (30.5 centimeters) on top of the predicted global sea level rise of 21 inches (54 centimeters), and a one percent rate would mean an extra 8 inches (20.3 centimeters) for the region. But if the current 7 percent rate were to persist, up to 20 inches (50 centimeters) of extra water would inundate cities such as New York and Halifax, Nova Scotia.
Still, Waleed Abdalati, a glaciologist at the University of Colorado, Boulder, said that the 7 percent scenario is really a worst case, particularly because "melt rate" is sometimes a misnomer, he said.
When glaciers break off into the ocean, they don't immediately melt, so scientists can't really say that all of Greenland's ice loss is due to melting, he explained.
But the finding is still important, he added, because "a few inches [of sea-level rise], depending on the time frame on which this occurs, makes a significant amount of difference," especially when it impacts heavily populated coastal areas.
What's more, previous studies had not taken into account how Greenland's melt might interact with an oceanic "conveyor belt" in the Atlantic Ocean, which transports water north from the tropics.
Normally in the belt tropical water gets cooler and becomes a deep layer of dense, cold water in the North Atlantic.
But the freshwater flow from Greenland slows down this conveyor belt and prevents the deep, dense water from accumulating. This would make deep water warmer and less dense, causing surface waters to expand throughout the North Atlantic.
It's for this reason that the northeast coast of North America is particularly vulnerable to rising seas, said Hu, whose research will appear May 29 in the journal Geophysical Research Letters.
Such predictions, and the study of ice sheets in general, is often plagued with uncertainties.
For instance, scientists still don't understand ice sheet dynamics, such as how fast an unstable ice sheet will melt.
And data from the Intergovernmental Panel on Climate Change (IPCC)—which many researchers depend on as the gold standard in climate change predictions—can become easily outdated.
The 2007 IPCC assessment, for example, projected a sea-level rise of up to 23 inches (59 centimeters) this century. But the rapid decline of the world's ice sheets has led many researchers to believe the rise will be even greater.
"The more we know," said the University of Colorado's Abdalati, "the more we're finding things are more severe than we thought."
Like a dune-rippled desert, the skin of a human foot (shown in an undated picture) is just one of the body's "habitats." Each skin region boasts a unique and surprisingly diverse array of microbes, according to a "topographic" skin map released in May 2009.
Long considered a source of odor and embarrassment, the humble armpit may be coming up in the world.
On the microbial level, a person's underarms are akin to lush rain forests brimming with diversity—and that's a good thing—according to a new "topographic map" of human skin.
Most of our skin is like an arid desert, said study co-author Julia Segre, of the National Human Genome Research Institute in Bethesda, Maryland.
"But as you walk through this desert you encounter an oasis, which is the inside of your nose," she said. "You encounter a stream, which is a moist crease. [These] areas are like habitats rich in diversity."
And like the "friendly" bugs in the human digestive system, these native bacteria of the epidermis promote skin health and could even help scientists find new ways to treat skin diseases.
The study, published this week in the journal Science, has revealed that human skin hosts a much more diverse set of bacteria than previously thought.
Samples of skin bacteria grown in the lab had suggested that a single genus, Staphylococcus, was dominant on human skin.
But by looking at the microbes' genes, Segre's team found at least 18 different phyla of bacteria dwelling in 20 different skin habitats. (In biology, a phylum is a group of animals that are similar enough that they likely share a common origin.)
What's more, these microbes are adapted to their habitats rather than to individual humans, Segre said.
"The bacteria in my underarm are more similar to those in your underarm than they are to those on my forearm," she said.
The map presents a new way of looking at various skin conditions, the study authors note.
For example, researchers could compare the map of the body's "normal" bacteria with one accompanying a wound or a disease such as eczema. This could reveal how these ailments—and our treatments of them—act on good and bad skin bacteria.
No Cause for Alarm
Germophobes needn't freak out. Serge stresses that many of the microbes are "healthy bacteria" that keep our largest organ in good condition.
For example, germs that live in naturally oily regions, such as the outside of the nose, feed on the skin's lipids and produce natural moisturizers to prevent skin from becoming chapped.
"People are eating probiotic yogurts to promote [beneficial] bacteria growth in the gut, but we want to sterilize the skin," Serge noted.
"We should think about proper sanitation with the skin, but not sterilization. There are good bacteria that really promote healthy skin."
Doomed lovers Cleopatra and Mark Antony have been missing since they committed suicide in 31 B.C. Now archaeologists plan to excavate three sites in Egypt that could contain their tombs.
The celebrated queen of Egypt and the Roman general could have been buried in a deep shaft in a temple near the Mediterranean Sea, Egypt's Supreme Council of Antiquities said in a statement Wednesday.
Excavation work on the sites will begin next week.
Archaeologists last year unearthed the alabaster head of a Cleopatra statue, 22 coins bearing Cleopatra's image, and a mask believed to belong to Mark Antony at the temple.
The three sites were identified last month during a radar survey of the temple of Taposiris Magna, the council's statement said. The temple is located near the northern coastal city of Alexandria, and was built during the reign of King Ptolemy II (282-246 B.C.)Teams from Egypt and the Dominican Republic have been excavating the temple for the last three years. They found a number of deep shafts inside the temple, three of which were possibly used for burials. The lovers could be buried in a similar shaft, the statement said.
The lovers committed suicide after being defeated in the battle of Actium.
Zahi Hawass, Egypt's top archaeologist, said the Cleopatra statue and coins -- which show an attractive face -- debunk a recent theory that the queen was "quite ugly."
"The finds from Taposiris reflect a charm ... and indicate that Cleopatra was in no way unattractive," said Hawass, according to the statement.
Academics at Britain's University of Newcastle concluded in 2007 that the queen was not especially attractive. Their conclusion was based on Cleopatra's depiction on a Roman coin which shows her as a sharp-nosed, thin-lipped woman with a protruding chin.
The Greenland Ice Sheet is melting -- and that could spell trouble for the northeast coast of the United States and eastern Canada.
Sea level in those regions might rise by as much as a foot more than current projections, according to a new study. Possible consequences include flooding and damage to both cities and ecosystems.
While experts say it's too soon to know how big the effects will be, lead researcher Aixue Hu said it's probably worth bracing for the worst-case scenario.
"In some sense, I think we should be alarmed and prepared that something could happen in the future," said Hu, a climate scientist at the National Center for Atmospheric Research in Boulder, Colo. "Right now, we're not sure which scenario is going to happen. Hopefully, the worst case will not happen." The Greenland Ice Sheet, a large mass of ice that covers most of Greenland, has been melting at an increasing rate since the early 1990s. In recent years, melting has accelerated at a rate of 7 percent each year. Scientists estimate that the ice sheet wonâ€™t disappear completely for another 3,000 years, but effects of melting could happen far sooner than that.
Every drop of water that melts from the ice flows into the ocean, raising sea levels. The input of relatively light freshwater also alters circulation patterns that cycle water between Greenland and northern North America, which could lead to more water on the North American end.
Without factoring in the melting of Greenland ice, warmer surface waters are already expected to shift currents, sending about 8 inches of water above the average global rise to the Northeast by 2100, Hu said.
To find out what melting in Greenland would add to the equation, he and colleagues used a computer model to consider three scenarios, in which melting increased at a rate of 7 percent, 3 percent, or 1 percent each year. The team projected out to the year 2100. Given the best-case scenario, the researchers report today in the journal Geophysical Research Letters, the east coasts of Canada and New England would get another four inches of water. In the worst-case scenario, sea level would rise by an extra foot in coastal areas from New York to Halifax.
"In the East Coast region, there are many big cities," Hu said. "If sea levels rise, it means some parts of land will submerge under water."
Water could surge over levies and flood estuaries, where organisms depend on a careful balance between salt and freshwater.
Other researchers warn against jumping to conclusions. For now, Greenland's melting contributes less than half a millimeter of water to the oceans each year, said Mike Winton, an oceanographer at the Geophysical Fluid Dynamics Laboratory in Princeton, N.J. That's a tiny amount.
Whether acceleration of melting from the Greenland Ice Sheet will continue, he added, is a big question mark. The Arctic has experienced wide swings in climate variability.
"I don't think we need to get particularly alarmed about this particular phenomenon," Winton said. "It's just part of the mix."
More important will be figuring out how sea level rise is going to vary from one region to the next around the world -- and what we're going to do about it, said glaciologist Eric Rignot.
It can take 30 or 40 years for polar ice to respond to our efforts to reduce emissions of carbon dioxide and other greenhouse gases, said Rignot, of the Jet Propulsion Laboratory in Pasadena, Calif. That means we need to start thinking about the distant future today.
"Even the most conservative people agree that Greenland is doomed," Rignot said. "Sea level is not going to stop rising after 2100. Instead of being scared, we need to take it seriously and plan ahead."
This placid view of Gouchang, Guizhou, China belies the region's violent history. New evidence uncovered from ancient lava deposits there suggests a supervolcano eruption was the direct cause of the mid-Permian extinction, which killed massive amounts of marine life, 260 million years ago.
Carbon from a massive volcanic eruption caused a mass extinction on Earth 260 million years ago, according to a new study. It's the first definitive link between a volcano and extinction.
The study strengthens the case that so-called supervolcano eruptions lead to massive climate change and may be responsible for many of the most devastating mass murders in Earth's history.
Although not one of the "big five" mass extinctions, the mid-Permian extinction has long been considered an important, if puzzling, event. Scientists have eyed massive lava deposits in the Emeishan region of southwestern China as the murder weapon, but they've been unable to show a connection.
Now Paul Wignall of the University of Leeds and a team of researchers have found that a host of algae and other marine species died out suddenly, along with many land-dwelling animals, right after a huge eruption. Chemical evidence also revealed a sharp up-tick in atmospheric carbon at the time, possibly spewed into the atmosphere when lava infiltrated and cooked pre-existing coal seams. The team's work is published in the current issue of the journal Science.
Compared to some of the largest volcanic cataclysms in geologic history -- called Large Igneous Provinces (LIP)s -- Emeishan is small; its lavas cover "only" around 250,000 square kilometers (96,526 square miles), an area about the size of Colorado.
Still, it was enough to have a global impact on life and climate. And the team's discovery adds credence to the idea that several major mass extinctions may have been caused by LIPs.
"Every crisis in the past 300 million years coincides with a LIP eruption," Wignall said. "So there's clearly some connection." Researchers suspect that the Siberian Traps eruption, which occurred just 10 million years later, was responsible for the Permian-Triassic extinction, the worst mass dying of all time. And though they agree that the huge eruptions disrupted climate, views are split over whether it was global warming from the excess carbon, or global cooling from large amounts of sulfur dioxide (SO2), that did the killing.
"This is an important study, as it tries to link basaltic eruptions directly to the extinction," Henrik Svensen of the University of Oslo said. "It is difficult to know exactly what the organisms died from, if judging from the fossils themselves."
A Russian Soyuz capsule carrying three new space station residents docked at the orbiting complex Friday. With three astronauts there to greet them, the space station now has a full staff of six for the first time in its 10-year history.
What's more, each of the major space station partners is represented on board for the first time. The combined crew, all men, now includes two Russians and one American, Japanese, Canadian and Belgian.
"There is so much potential in this beginning, in this historic milestone," Steve MacLean, president of the Canadian Space Agency and a former astronaut, said at the Russian control center outside Moscow. It represents "what we will be able to achieve with future programs ... and what we as a combined series of countries can do for the future exploration of space."
Having all these countries represented on board is "a great way to kick off a six-person crew," NASA's deputy space station program manager, Kirk Shireman, said on the eve of the linkup.
The Soyuz spacecraft blasted off from Kazakhstan on Wednesday. It pulled in at the space station as the two vessels soared 217 miles above the China coast.
When shuttle Endeavour and its crew of seven arrives in another few weeks, a record 13 people will be at the space station, but that will be only temporary.Ever since the first space station crew arrived in 2000, two years after the first part was launched, no more than three people have lived up there at a time. The crew size dropped to two following the 2003 Columbia disaster because of the lengthy grounding of NASA's remaining space shuttles.
Those major supply runs will end when the shuttles are retired at the end of next year. NASA hopes to stockpile big spare parts at the space station before that happens; Endeavour, in fact, will carry up some on the next shuttle mission.
NASA also will have to rely on the Russian Space Agency to transport all its astronauts up and down, once shuttles are no longer flying.
The ride will cost $51 million per American astronaut. That's considerably more than the $35 million paid by the latest space tourist, Charles Simonyi, an American software entrepreneur who flew last month.
A NASA spokesman said Thursday that the space agency did not take part in the space tourist contract negotiations and therefore could not comment on the difference in price. But the spokesman, Kelly Humphries, noted that Soyuz seats purchased by NASA in 2008 were $47 million apiece and the newest price reflects general increases.
As for the next shuttle flight to the space station, Endeavour is scheduled to blast off June 13 with an American who will replace the Japanese on board, and the final components for the Japanese laboratory that's already up there. That mission, however, could be bumped into July. Stormy weather at NASA's launching site has delayed launch preparations.
Carrots might not scream when pulled from the ground, but new technology is giving vegetables a voice in how they are raised. Microchipped plants can now send text messages to a farmer's cell phone and ask for water.
"It's akin to a clip on earring, very thin and smaller than a postage stamp, and is affixed to the plant leaf," said Richard Stoner, President of AgriHouse, a company marketing the technology.
"The farmer would just need their regular cell phone service, and the plant would send a text message when it needed water."
For areas that receive regular and plentiful rainfall, such detailed crop monitoring might not be useful or economical. But in the western United States, where much of the water comes from underground aquifers, conserving water, and more importantly, conserving the electricity that pumps it to the surface and across fields, could save farmers hundreds of thousands of dollars each year.
Water in the open spaces of the west is valuable, but it's virtually worth its weight in gold in outer space. The original cell phone for plants was developed years ago by scientists working with NASA on future manned missions to the moon and Mars.
"You need plants on future space missions," said Hans-Dieter Seelig, a scientist at the University of Colorado at Boulder who worked on the original NASA project.
"They take out waste carbon dioxide, produce breathable oxygen, and the astronauts can use them as food," said Seelig.
During their research, the NASA scientists concluded that astronauts wouldn't be able to take anywhere near enough food and supplies for an estimated two-year mission to Mars. The pilots and Ph.D.'s selected for the trip would have to spend most of their time as celestial subsistence farmers.
To reduce the amount of time and supplies necessary to grow crops, scientists clipped sensors, wired to a central computer, to plants so astronauts would know exactly when and how much water to give them.
During the initial NASA tests the scientists were able to reduce the amount of water necessary to grow plants by 10 percent to 40 percent.
Sustainability in space might keep astronauts alive, and on Earth it's likely to save farmers time and money."We are talking about saving hundreds of thousands of dollars each year for farmers," using the existing wired system, said Stoner.
The existing sensors have to be connected to a power source to take readings and transmit them over commercial cell phone towers. Stoner hopes that future sensors can be equipped with batteries, solar panels or even piezoelectric generators to generate the power necessary to run the sensors and transmitters.
Adding more sensors across wider areas will enable more detailed management of farms, saving farmers even more, says Stoner.
Water in the western United States might be relatively cheap, but the electric bills to pump the water from underground aquifers do add up. And there is no guarantee that the water will remain cheap either. Being sustainable could end up being good business.
"We can't be sustainable just in outer space," said Seelig. "That same principle has to be applied here on Earth as well."
jueves, 28 de mayo de 2009
There was a major earthquake offshore of Honduras today. At 7.1 magnitude, it packed enough punch to endanger lives and warranted a brief tsunami watch for Belize, Honduras anHonduras7-1Mquaked Guatemala -- the countries with coastlines closest to the epicenter. It's an interesting quake in other ways.
The Caribbean is a complicated place when it comes to earthquakes. I'm no expert on the matter, but a look at a geologic map shows that it's crisscrossed with faults of all kinds, which form the edges of a jumble of broken plates in Earth's crust there. All these shards of plates are crammed together and jostling for space by the much larger, more powerful plates all around them, which are going about their much larger-scale tectonic business.
The most dangerous of the faults tend to be those created by plates colliding in a frontal assault -- where one is pushed under another in what's called subduction. This is the sort of situation you see in Sumatra and southern Alaska -- among the world's most quaky places. There is some of this going on in the northeastern Caribbean, but that's not what caused this quake way over in the western part of that sea.
W-carib-map The culprit today is more like the infamous San Andreas Fault in California, created by two pieces of the Earth's crust grinding side-by-side and in opposite directions. You can see which fault it was on this GSA geologic map I just pulled out and photographed (at left). I inserted a little "X" at the epicenter near the center of the image. The black lines are the faults.
Among other things, the side-wise movement of the plates in this corner of the Caribbean is the cause of that deep purple spreading center in the upper right-hand side of the map image. The crust is being pulled apart in that area. Just another complicated day in the Caribbean.
Some three million years ago, eel-like sharks snaked through the region that now supports Tuscany's finest vineyards, suggest fossils recently found in the clay soil of the Chianti region.
Hundreds of fossilized teeth belonging to primitive shark-like creatures have been uncovered by amateur paleontologists near the village of Castelnuovo Berardenga, not far from Siena.
"It all started in 2001. We were poking around the Crete Senesi [in the Tuscany region], in a landscape made of green vine waves and ridges of clay, when we saw a tooth cropping out of the soil," Simone Casati, president of the Mineralogy and Paleontology Group of Scandicci, told Discovery News.
"Since then, we have found an exceptional number of fossilized fish teeth from the Pliocene epoch. Indeed, about three million years ago, before the sea started to retreat to its current location some 100 kilometres [62 miles] away, the site was a sort of underwater canyon populated by hundreds of deep-water creatures," Casati said. Studied by Franco Cigala Fulgosi, from the Department of Earth Sciences of Parma University, the teeth turned out to belong to Chlamydoselachus lawleyi, a species which strongly resembles the living frilled shark Chlamydoselachus anguineus.
With a snake-like body, flat head and large toothy mouth, the shark has changed little since prehistoric times. Like primitive sharks, it has six gills, whereas most modern sharks have five.
Living at depths of about 2,000 feet, these five-foot sharks seem to prefer the cold waters of deep and upwelling regions. Making great vertical migrations at night, they have been often captured in Japan's Suruga Bay. "The teeth unearthed in Tuscany belong to a species which differs from the living frilled shark only by its larger size," Cigala Fulgosi, an authority on fossil sharks, told Discovery News. "The teeth suggest an animal approximately 2.5 metres [8.2 feet] in length."
Reporting the finding in the latest issue of the journal Cainozoic Research, Cigala Fulgosi traced the discovery of identical fossilized shark teeth back to 1876.
At that time the naturalist Robert Lawley published the first pictures of a fossil teeth of Chlamydoselachus -- nine of which he had collected in a village some 50 miles from Castelnuovo Berardenga.
Along with the Chlamydoselachus shark teeth, Casati and his team unearthed other fossils which included otoliths (ear stones which in fish play a role in hearing and balance) and teeth from other deep-water sharks.
According to Cigala Fulgosi, these fossil remains indicate that the site had a sufficiently deep connection with the Atlantic Ocean through the Gibaltrar Strait.
"What's really important in this discovery is the great abundance of Chlamydoselachus teeth, all concentrated in such a small area. We can't say why they all ended up there. We cannot exclude that they died because of currents, sea bottom depressions or traps. Everything can happen underwater," Cigala Fulgosi said.
The idea that, beneath the vines that today produce the renowned Chianti Classico red wine, there was once a world populated by sharks, delights winegrowers in the area.
According to Albiera Antinori, whose family has made wine for more than 600 years, the finding shows once again the special nature of the Chianti soil.
"We know that million-year-old minerals and deposits enrich this region. It's this special earth that makes our wines really unique," Antinori told Discovery News.
A day-old panda cub whose birth surprised Thai zoo officials is a healthy female that appears to be bonding well with its much larger mother, Chinese experts concluded Thursday.
Officials at the Chiang Mai Zoo in northern Thailand had tried unsuccessfully for years to breed the rare mammal and did not know the mother was pregnant. Thailand joins the United States and Japan as the only countries outside of China to breed a panda in captivity.
"The panda experts from China said the baby is in good health and strong," said Sophon Damnui, director of the Zoological Park Organization, which oversees all zoos in Thailand. "She cries very loudly and she breast-feeds from her mother very well."
The birth was featured on the front pages of many Thai newspapers, which carried photos of the pinkish cub so tiny that it could be held in the hands of a zoo staffer. Others pictures showed the hulking mother Lin Hui gently holding her baby.
Zoo officials had resorted to sometimes-comical strategies to get its two pandas on loan from China to mate over the past six years. They held a mock wedding for the pair, separated them to spark a little romance and then put the male, Chuang Chuang, on a diet to entice Lin Hui.When that didn't work, they started showing Chuang Chuang "porn" videos of pandas mating, and finally turned to artificial insemination.
Zoo staff artificially inseminated the 7-year-old Lin Hui on Feb. 18, Chiang Mai Zoo director Thananpat Pongamorn said.
Staff had been monitoring her hormone levels in recent weeks and noticed they were rising. But an ultrasound image on May 11 was not clear and they couldn't make out a fetus. Panda births are difficult to predict and reports of false pregnancies are common.
"She's been anxious since yesterday. She did not want to get close to caretakers or any other people, but we didn't know what the problem was," Thananpat told The Associated Press late Wednesday.
Lin Hui started licking her backside and exhibiting pain in her stomach early in the morning and then gave birth to the cub, which immediately began screeching loudly, Thananpat said.
"It is an ultimate happiness to see the baby panda," Thananpat said. "We are so happy that we can breed a panda from artificial insemination. Every staff at the zoo is proud and I think every Thai will be proud too."
Sophon told Channel 3 television Wednesday that Lin Hui was "very fond of her baby.""She cuddles, licks and holds the baby very carefully all the time," he said. "She knows how to be a mother even though she has never been one before."
Breeding pandas is a common practice in China, where dozens are born by artificial insemination each year. But it is a rare occurrence outside of the country.
Pandas are threatened by loss of habitat, poaching and a low reproduction rate. Females in the wild normally have a cub once every two to three years. The fertility of captive giant pandas is even lower, experts said.
Only about 1,600 pandas live in the wild, mostly in China's southwestern Sichuan province, which was hit by an earthquake last year that killed nearly 70,000 people. An additional 120 are in Chinese breeding facilities and zoos, and about 20 live in zoos outside China.
Suzanne Braden, the director of the Colorado-based conservation group Pandas International, called the cub's birth in Thailand "superb news and important to the preservation of the species."
"With such small numbers, every panda birth is extremely significant -- especially after the devastation following the 2008 (earthquake in) Sichuan province," Braden said in an e-mail interview.
'Glowing' Transgenic Monkeys Carrying Green Fluorescent Protein Gene Pave Way For New Disease Models
Five transgenic marmoset offspring are born, (a) Hisui, (b) Wakaba, (c) Banko, (d) Kei (left) and Kou (right). When observed in UV, the skin on the soles of the feet glow green. (Credit: E. Sasaki et al 2009)
A transgenic line of monkeys carrying a gene encoding green fluorescent protein fully integrated into their DNA has been created for the first time. The research, published in the journal Nature, marks the first such feat in non-human primates and paves the way for developing new models of human diseases.
Scientists reported the first transgenic monkeys last year — a model of Huntington’s disease — but in these animals, the gene did not fully integrate into the monkey’s own DNA and was not passed down to their offspring. In this report, Erika Sasaki and colleagues used viral DNA as a delivery vehicle to introduce the gene for GFP into the DNA of the common marmoset Callithrix jacchus. They show that the gene integrated into the monkey’s DNA and was successfully passed down to their offspring, which were healthy and all expressed the new gene.
Transgenic mice have contributed immensely to biomedical research, but for many diseases they are too dissimilar from humans for the results to be meaningful. Non-human primates hold great promise for the study of several human diseases, particularly neurological disorders, for which there are currently no appropriate experimental models. This study marks an important milestone on the road to developing the means to investigate these diseases.
In an accompanying news story, Nature News reporter David Cyranoski explains why other transgenic monkeys have failed to reproduce so far, and describes the 5-year Japanese project to develop alternative animal models of which Sasaki’s research is a part. Also in this issue, an editorial calls for researchers working on transgenic primates to go much further than they have so far in articulating the ethical aspects both of their research and its potential applications. Engagement in public discussion is essential to avoid inappropriate regulation.
A third species of Palaeopropithecus, an extinct group of large lemurs, has just been uncovered in the northwest of Madagascar by a Franco-Madagascan team. Dubbed Palaeopropithecus kelyus, this new specimen is smaller than the two species of these 'large sloth lemurs' already known and its diet made up of harder-textured foodstuffs. This discovery supports the idea of a richer biodiversity in recent prehistory (late Pleistocene and beginning of the Holocene).
Madagascar, where natural environments show a high level of endemism, is one of the last great biodiversity sanctuaries in the world. The island is home to a special group of primates, the lemurs. There are presently 15 genera and 71 species of these small mammals on Madagascar.
The genus Palaeopropithecus is a group of subfossil giant lemurs(2). Up until now, two species had been described: P. ingens (in 1898) and P. maximus (in 1903). Palaeopropithecus have very specific adaptations, notably for locomotion, as they moved from branch to branch using all four limbs, with their head downwards, in a similar way to today's South American sloths.
Recent discoveries by the MAPPM(1) on sites in northwest Madagascar have established the existence of a third species of Palaeopropithecus, which has been dubbed P. kelyus. Scientists have suspected the existence of this species for more than 20 years. P. kelyus, whose weight is estimated around 35 kg, is smaller than the two known Palaeopropithecus species, but is very large in comparison with the largest living lemur, the Indri, which weighs only 10 kg.
The other main difference of this new species is that its teeth are smaller. Its dental characteristics could be described from the P. kelyus subfossil maxilla fragment, showing a crista obliqua, a parastyle and a highly developed mesostyle. This morphology is reminiscent of the present day Propithecus genus. While other Palaeopropithecus must have fed on leaves and fruit, the differences in the teeth of P. kelyus suggest that this animal could chew much tougher foods (notably seeds) compared with the other two known species. P. kelyus was found in an area of northwest Madagascar (Boeny region, Mahajanga province) with the particularity of being situated between large bays and rivers. This topography could have isolated P. kelyus from the other two species of Palaeopropithecus, one of which lived more in the south or centre, and the other in the north of Madagascar.
In the ‘evolution laboratory' that Madagascar represents, the discovery of this third Palaeopropithecus contributes to our understanding of the subfossil fauna species. More broadly, such work also includes the study of the island's human population.
(1) The project ‘Mission archéologique et paléontologique dans la province de Mahajanga' (MAPPM) is a Franco-Madagascan collaboration between CNRS UPR 2147 (Dynamique de l'Évolution Humaine: Individus, Populations, Espèces) and UFR Mozea Akiba of Université de Mahajanga, funded by the Sous-direction de l'archéologie et de la recherche en sciences sociales of the French Ministry of Foreign and European Affairs, CNRS and Université de Mahajanga.
(2) Subfossils are species that died out during the historic or prehistoric eras and overlapped present-day species. Unlike classic fossils, their bones are not completely mineralised.
The results, currently available online, will be published in the Comptes Rendus Palevol (Académie des Sciences), July-August 2009.
Famous depictions of the largest of all known dinosaurs, from film and television to museum skeletons, have almost certainly got it wrong, according to new research.
Sauropods are the most iconic of prehistoric creatures. They were up to 30 metres long, weighed as much as 10 elephants, and are instantly recognisable by their very long necks and small heads. They are the centrepieces in most natural history museums worldwide.
Recent depictions such as the BBC's Walking With Dinosaurs show them with their long necks held horizontal and their heads near the ground. But now scientists are saying the low-necked sauropod pose is a mistake: new evidence indicates that they held their necks aloft like giraffes and all other living land vertebrates, making them up to 15 metres tall.
Dr Mike Taylor and Dr Darren Naish, of the University of Portsmouth, and Dr Matt Wedel, of Western University of Health Sciences in California, argue that while sauropods could hold their necks low, it was not their habitual posture.
They studied X-rays of members of 10 different vertebrate groups and found that while the neck is only gently inclined in salamanders, turtles, lizards and crocodilians, it is vertical in mammals and birds – the only modern groups that share the upright leg posture of dinosaurs.
Dr Taylor said: “Like the animals we have with us today, they would have spent most of their time with their necks elevated, except when drinking or browsing at low levels.”
Modern vertebrates, from cats and humans to sauropods’ closest living relatives, the birds, hold their necks aloft in a vertical or near-vertical position.
Dr Wedel said: “We can’t just study fossil bones by themselves. Dinosaurs were living animals and to understand how they lived, we need to look at animals that are alive today. In this case, our evidence shows the present is the key to the past.”
The neck vertebrae of sauropods fit together mainly by way of ball and socket joints. In addition, the top part of each vertebra has a pair of facets, two at the front and two at the back, which glide past each other when the neck bends.
Dr Taylor said: “Scientists have assumed that each pair of facets must maintain at least a 50 percent overlap at all times; but looking at what ostriches and giraffes do, we see that their facets can slide much further, until they hardly overlap at all. This means that sauropods would have had a far greater range of neck movement than has been thought in recent times.
“Unless sauropods carried their heads and necks differently from every living vertebrate, we have to assume that the base of their neck was curved strongly upwards. In some sauropods this would have meant a graceful swan-like S-curve to the neck, and a look quite different from the recreations we are used to seeing today.”
Low necked poses for sauropods have been used for countless plastic toys and have become part of mainstream culture, thanks in part to the BBC’s Walking with Dinosaurs, and to new museum exhibits such as one at the American Museum of Natural History in New York.
Professor Mike Benton at Bristol University’s Department of Earth Sciences, said: “It's hugely important to understand how sauropod dinosaurs functioned. They were so huge – ten times the size of an elephant – and yet they were successful animals. This new work provides plausible evidence that sauropods held their necks elevated, rather than horizontally, as had been assumed.
“The new work is based on studies of living animals, but the next step will be to carry out engineering studies to see whether the new or old neck positions are energetically more efficient. If you have a long neck that weighs a tonne or more you must hold it in a neutral position where stresses and strains are minimised.”
The Universe was a more fertile place soon after it was formed than has previously been suspected. A team of French and Italian astronomers  made indeed the surprising discovery of a large and unknown population of distant galaxies observed when the Universe was only 10 to 30% its present age.
This breakthrough is based on observations made with the Visible Multi-Object Spectrograph (VIMOS) as part of the VIMOS VLT Deep Survey (VVDS). The VVDS started early 2002 on Melipal, one of the 8.2-m telescopes of ESO's Very Large Telescope Array .
In a total sample of about 8,000 galaxies selected only on the basis of their observed brightness in red light, almost 1,000 bright and vigorously star forming galaxies were discovered that were formed between 9 and 12 billion years ago (i.e. about 1,500 to 4,500 million years after the Big Bang).
"To our surprise, says Olivier Le Fèvre, from the Laboratoire d'Astrophysique de Marseille (France) and co-leader of the VVDS project, "this is two to six times higher than had been found previously. These galaxies had been missed because previous surveys had selected objects in a much more restrictive manner than we did. And they did so to accommodate the much lower efficiency of the previous generation of instruments."
While observations and models have consistently indicated that the Universe had not yet formed many stars in the first billion years of cosmic time, the discovery announced today by scientists calls for a significant change in this picture. The astronomers indeed find that stars formed two to three times faster than previously estimated.
"These observations will demand a profound reassessment of our theories of the formation and evolution of galaxies in a changing Universe", says Gianpaolo Vettolani, the other co-leader of the VVDS project, working at INAF-IRA in Bologna (Italy).
These results are reported in the September 22 issue of the journal Nature (Le Fèvre et al., "A large population of galaxies 9 to 12 billion years back in the life of the Universe").
The BLAST telescope produced these images of Star formation toward the constellation Vela. (Credit: BLAST collaboration)
People have always wondered where we, our Earth, our galaxy, come from. A group of scientist has now driven that quest one step further and taken a peak at how the stars that gave rise to most of the material found on our universe formed over cosmic history.
University of Miami professor of physics in the College of Arts and Sciences, Joshua Gundersen is part of an international research team that built an innovative new telescope called BLAST (Balloon-borne Large-Aperture Sub-millimeter Telescope) and launched it to the edge of the atmosphere, where it discovered previously unidentified dust-obscured, star-forming galaxies that could help illuminate the origins of the universe.
"BLAST has given us a unique picture into the development of other galaxies and the earliest stages of star formation of our own Milky Way," Gundersen explains. "The light we're getting from these submillimeter galaxies is from a time when they were first forming. In a sense, it's like getting a baby picture."
The data analyzed over the past two years reveals close to a thousand of these "starburst" galaxies that lie five to ten billion light years from Earth, produce stars at an incredible rate, and hide about half of the starlight in the cosmos. The findings were recently published in the journal Nature.
Until BLAST came along, most of the galaxies in the universe have been detected at optical wavelengths visible to the naked eye. The "starburst" galaxies identified by Gundersen and his colleagues however are a new class of galaxies, enshrouded by dust that absorbs most of their starlight and then re-emits it at far-infrared wavelengths.
During an 11-day flight in 2006, the telescope, while tethered to a balloon 120,000 feet above Antarctica, took measurements in three different submillimeter wavelengths that are nearly impossible to observe from the ground. "By going to balloon altitudes, we got a nice, crystal-clear picture of these things," Gundersen said. "It is these far-infrared and submillimeter wavelengths that we're able to detect with BLAST," Gundersen explains.
Graduate student Nick Thomas spent seven weeks at the McMurdo scientific research station in Antarctica, where he helped assemble the device and worked on some of its electronic systems.
"Having worked in a project of this magnitude and in the company of a superb group of scientists has been one of the highlights of my career thus far," said Thomas. "Collaborating on this project has been an incredible learning experience both at the personal and the professional level."
The data from BLAST is being combined with information from other NASA observatories like the Spitzer Space Telescope and the Chandra X-ray Observatory, helping astronomers and cosmologists to better understand the evolutionary history of these "starburst" galaxies and how they may be associated with larger-scale structures in the universe.
The work on BLAST has helped pave the wave for one of the European Space Agency's most ambitious missions to study the cosmos: The Herschel telescope, which launched into orbit earlier this month from a space center in French Guiana. Herschel will peer into the dustiest and earliest stages of planet, star, and galaxy growth, using the same detector system that flew aboard BLAST.
"The idea with BLAST was that we could test a new detector system on a much cheaper, faster platform, namely a balloon payload," Gundersen says. "Herschel has an identical detector system to BLAST, along with other important instruments. "It will do a lot more than BLAST did, but we achieved some of the important goals first."
Peering behind the dusty veil of a nearby galaxy, astronomers have found a new supernova, the closest seen in the past five years.
The stellar explosion happened in the galaxy M82, which lies a mere 12 million light-years from Earth. Visible-light images of the galaxy—such as the Hubble Space Telescope picture at left—make M82 look as if it's exploding, due to a plethora of supernovae happening deep inside.
Thick dust and gas shroud the explosions from view, but instruments that can see in radio wavelengths had previously revealed the vast number of supernova remnants, so astronomers were sure that a new supernova would be due anytime.
Sure enough, an international team of astronomers using radio telescopes spotted the recent supernova in M82 on April 8 (bottom-right inset).
"I then looked back into older data we had from March and May last year [middle insets], and there it was as well, outshining the entire galaxy!" team member Andreas Brunthaler, of the Max Planck Institute for Radio Astronomy in Germany, said in a statement.
Combining data from several telescopes, the team revealed that the supernova had created a ring of debris, which is expanding at more than 25 million miles (40 million kilometers) an hour. Working backward, the study authors estimate that the star exploded in late January or early February 2008.
The explosion happened close enough that, if it hadn't been for its surroundings of dense material, the bright flash would have been visible from Earth via backyard telescopes, noted team member Heino Falcke from Radboud University Nijmegen in the Netherlands.
"This cosmic catastrophe," Falcke said, "shows that, using our radio telescopes, we have a front-row seat to observe the otherwise hidden universe."
Findings published this week in the journal Astronomy & Astrophysics.
For the first time, astronomers have mapped the phases of a planet outside our solar system (top)—just as Italian astronomer Galileo Galilei drew the phases of Venus (bottom) almost 400 years ago.
The extrasolar planet, or exoplanet, COROT-1b orbits a star about 1,600 light-years from Earth.
The planet is known as a "hot Jupiter," a class of exoplanets similar in size to Jupiter but orbiting very close to their host stars—usually less than an eighth of the distance between Mercury and the sun.
Astronomers had suspected that hot Jupiters would be what's known as tidally locked to their hosts—with one side always facing the star, just as one side of the moon always faces Earth.
Using the COROT satellite, Ignas Snellen of the Netherlands' Leiden University and colleagues collected visible light readings from COROT-1b over the course of 36 of its orbits.
The team observed a contrast in brightness between the two sides that creates phases as the planet orbits its star. These phases are similar to the phases of the planets Mercury and Venus as seen from Earth.
"This is a very exciting new result, in that astronomers have been searching for a decade to try and detect [visible] starlight reflected from the day sides of hot Jupiters," Andrew Collier Cameron, an astronomer at the University of St. Andrews in Scotland, commented via email.
But while Galileo used the phases of Venus as evidence that the planets orbit the sun, Snellen and colleague's findings confirm that COROT-1b is in fact tidally locked to its star, with one side of the planet in permanent darkness and the other illuminated all the time.
The team also took new measurements of COROT-1b's temperature, which showed that the planet experiences huge temperature differences, ranging from about 4,082°F (2,250°C) on the day side to 2,282°F (1,250°C) on the night side.
Not having a more balanced heat distribution indicates that the planet's atmosphere doesn't mix very fast, the study authors say. (Related: "Half-Hot, Half-Cold Planets Have Supersonic Jet Streams.")
"Wind speeds are probably not high enough to allow the energy to be transported from the day side to the night side before it is radiated back into space," said Ernst de Mooij, a study co-author.
Furthermore, the atmosphere must contain chemicals, such as titanium oxide, that rapidly absorb heat for it to reach the searing temperatures observed.
Findings published this week in the journal Nature.
miércoles, 27 de mayo de 2009
New fossil findings discovered by scientists at UC Santa Barbara challenge prevailing views about the effects of "Snowball Earth" glaciations on life, according to an article in the June issue of the journal Nature Geoscience.
By analyzing microfossils in rocks from the bottom of the Grand Canyon, the authors have challenged the view that has been generally assumed to be correct for the widespread die-off of early life on Earth.
"Snowball Earth" is the popular term for glaciations that occurred between approximately 726 and 635 million years ago and are hypothesized to have entombed the planet in ice, explained co-author Susannah Porter, assistant professor of earth science at UCSB. It has long been noted that these glaciations are associated with a big drop in the fossil diversity, suggesting a mass die-off at this time, perhaps due to the severity of the glaciations. However, the authors of the study found evidence suggesting that this drop in diversity occurred some 16 million or more years before the glaciations. And, they offer an alternative reason for the drop.
A location called the Chuar Group in the Grand Canyon serves as "one of the premier archives of mid-Neoproterozoic time," according to the article. This time period, before Snowball Earth, is preserved as a sort of "snapshot" in the canyon walls.
The scientists found that diverse assemblages of microscopic organic-walled fossils called acritarchs, which dominate the fossil record of this time, are present in lower rocks of the Chuar Group, but are absent from higher strata. In their place, there is evidence for the bacterial blooms that, the authors hypothesize, most likely appeared because of an increase in nutrients in the surface waters. This process is known as eutrophication, and occurs today in coastal areas and lakes that receive abundant runoff from fertilizers used in farming.
"One or a few species of phytoplankton monopolizes nutrients at the expense of others," said Porter, explaining the die-off of diverse acritarchs. "In addition, the algal blooms result in high levels of organic matter production, which we see evidence of in the high organic carbon content in upper Chuar Group rocks. In fact, the organic carbon content is so high in the upper Chuar Group, oil companies were interested in the Chuar Group as a possible source of oil and natural gas." As a result of high levels of organic matter, oxygen levels in the water can become depleted, resulting in widespread "dead zones." Porter and colleagues also found evidence for extreme anoxia in association with the bacterial blooms.
In an accompanying article describing the process of discovering the microfossils, Porter described a highlight of the trip, "…when we rode through the rapids and descended into 'Powell's bowels' –– where the oldest rocks in the Grand Canyon frame the river passage. These rocks formed deep in the Earth approximately 1.8 billion years ago, and are very different in appearance from the overlying rocks."
The scientists braved extreme sun, rattlesnakes, scorpions, and dehydration to gather their data. They traveled by foot, helicopter, and river rafts, the last of which capsized on one occasion –– although the samples remained intact.
The first author on the paper is former UCSB graduate student Robin Nagy, who did the research as part of her work to obtain her master's degree. Nagy now teaches seventh and eighth grade science at Williams Elementary Middle School in Williams, Arizona. Other co-authors are Carol M. Dehler of Utah State University, and Yanan Shen of the University of Quebec.
NUI Galway researchers, during a recent deep-water expedition, have confirmed the existence of a major new coral reef province on the southern end of the Porcupine Bank off the west coast of Ireland. The province covers an area of some 200 sq. km and contains in the order of 40 coral reef covered carbonate mounds. These underwater hills rise as high as 100m above the seafloor.
The deep-water research expedition took place earlier this month aboard the Marine Institute research vessel, the RV Celtic Explorer. The research used the new national Remotely Operated Vehicle (ROV) Holland I to survey the seafloor and capture unique video footage. The expedition, led by Dr Anthony Grehan, was a collaboration between NUI Galway and the Institut Français de Recherche pour l’Exploitation de la Mer (IFREMER) and involved researchers and students from both institutions.
Dr Anthony Grehan, NUI Galway, said: “These are by far the most pristine, thriving and hence spectacular examples of cold-water coral reefs that I’ve encountered in almost ten years of study in Irish waters. There is also evidence of recent recruitment of corals and many other reef animals in the area suggesting this area is an important source of larvae supply to other areas further along the Porcupine Bank”. Dr Grehan suggested that given the rugged terrain, its unsuitability for trawling and its well defined boundaries, that the area would be an excellent additional candidate to the four existing off-shore coral Special Areas of Conservation (SAC). He said that NUI Galway’s Department of Earth and Ocean Sciences would in due course provide a copy of all video footage to the National Parks and Wildlife Service to facilitate them in their work of further SAC designations to comply with the European Union's Habitat Directive.
The expedition began in French waters with a series of ROV dives in previously unexplored canyons in the Bay of Biscay which confirmed the presence of coral and geogenic reefs that will be notified to the new French Marine Protected Area Agency. Dr Brigitte Guillaumont from the newly established agency, said: “The video and images obtained from the high definition video camera of the Irish ROV are very impressive and will greatly assist us in our work of designating areas for the protection of corals”.
Moving into Irish waters, the use of high resolution bathymetry charts, provided by the Irish National Seabed Survey, a collaboration between the Geological Survey of Ireland and the Marine Institute, enabled the identification of new areas likely to support coral reefs. The ROV was then used to dive on one of these areas, the Archipelagos Mounds (or Arc Mounds), to reveal a seascape of spectacular coral reefs. Anna Rensdorf, a Griffith Geoscience PhD student in the Department of Earth and Ocean Sciences, NUI Galway, who had previously worked on tropical corals, said: “I can’t believe that coral reefs like these can be found in the cold waters of Ireland. On many of the mounds surveyed, living coral thickets stood up to 2m high where ordinarily they are less than half a metre in height”.
The NUI Galway study is part of a larger pan-European project funded by the European Commission’s 7th research Framework Programme, called ‘CoralFISH’ that is studying in detail the interactions between corals, fish and fisheries. Dr Grehan, coordinator of the European study, said: “At the recent International Council for the Exploration of the Sea (ICES) deep-sea symposium delegates expressed increasing concern about the level of bottom fishing related damage sustained by vulnerable marine ecosystems (VMEs) in the High Seas (i.e. areas beyond national jurisdiction). Because cold-water corals remain the best example of VMEs, much research is focused on them. One of the key areas in the management of fisheries now appears to be improving our understanding of how fish use habitat. We need to understand what effect damage or removal of that habitat will have on fish stocks and communicating that knowledge to fishermen”.
Dr Grehan noted that vulnerable marine ecosystems such as coral reefs represent one of the last untapped reservoirs of potentially useful bio-compounds that might support the development of new anti-viral or anti-bacterial pharmaceuticals. Currently, there is a major biodiscovery programme underway at NUI Galway funded through the Marine Institute under Sea Change – A Marine Knowledge, Research and Innovation Strategy for Ireland 2007-2013.
Brain-computer interfaces offer liberating possibilities like faster 'thought typing'. (Credit: Copyright Presenccia)
Light switches, TV remote controls and even house keys could become a thing of the past thanks to brain-computer interface (BCI) technology being developed in Europe that lets users perform everyday tasks with thoughts alone.
The technology, which was demonstrated at CeBIT in Hannover in March, provides an innovative way of controlling the interconnected electronic devices that will populate the smart homes of the future, granting increased autonomy to people with physical disabilities as well as pleasing TV channel-surfing couch potatoes.
“The BCI lets people turn on lights, change channels on the TV or open doors just by thinking about it,” explains Christoph Guger, the CEO of Austrian medical engineering company g.tec that developed the application.
g.tec teamed up with a group of international universities and research institutes as part of the EU-funded Presenccia project to incorporate its BCI technology into virtual environments. As part of the project a fully functioning smart home was created in virtual reality (VR).
“It has a kitchen, bathroom, living room… everything a normal home would have. People are able to move through it just by thinking about where they wanted to go,” Guger says.
Electroencephalogram (EEG) equipment is used to monitor electrical activity in a user’s brain via electrodes attached to their scalp. After a period of training, the system learns to identify the distinctive patterns of neuronal activity produced when they imagine walking forwards, flicking on a light switch or turning up the radio.
Liberating possibilities for people with disabilities
Being able to move and control objects in virtual reality solely by the power of thought could offer new and liberating possibilities for people with physical disabilities. It could help amputees learn how to use a prosthetic limb, for example, or allow people confined to a wheelchair to experience walking in virtual reality, as one experiment conducted by the Presenccia researchers showed.
“A virtual environment could be used to train a disabled person to control an electric wheelchair through a brain-computer interface,” explains Mel Slater, the coordinator of the Presenccia project. “It is much safer for them to learn in VR than in the real world, where mistakes could have physical consequences.”
One application developed by g.tec lets people control a small robot with their thoughts, though the same system could easily be adapted to control a wheelchair instead. Four lights on a small box set to flicker at different frequencies provided the control mechanism using a method known as Steady State Visual Evoked Potentials (SSVEP).
“The top light, for example, was set to flicker at 10 hertz so, when the user stared at it, the EEG equipment registered that particular frequency in the user’s brain and instructed the robot to move forward. Looking at another light flickering at a different frequency would tell the robot to go left and so on,” Guger explains.
g.tec has adopted a different approach to allow people to type with their thoughts. Users sit in front of a grid of letters and numbers on a computer screen which flash in sequence and are told to stare at the character they want to type. The system registers their brain activity when the letter they are looking at is illuminated.
“With experience people can learn to type quite fast. I can average about one letter every eight-tenths of a second, a rate similar to typing with one finger,” Guger says.
Better hardware, software and a deeper understanding of EEG data has now made typing by thought power a practical application, particularly for paralysed people suffering from so-called locked-in syndrome who have few means of communication.
“Just two years ago, it took up to a minute to type a single letter and a whole day to train someone to do it. Now most people can learn to use the system in five minutes,” Guger says.
The accuracy of BCI technology has also greatly improved: g.tec was involved in a study that showed 82 percent of people could achieve 100 percent accuracy. “Five years ago there was only one person in the world known to be able to do that,” Guger notes.
Where will such rapid progress lead?
The g.tec CEO initially expects BCI technology to continue to gain ground in medical applications for the disabled and for rehabilitation, helping people who have suffered a stroke, for example, to regain use of their limbs. However, he believes it could become common in everyday environments. Having been tested in virtual reality, g.tec’s smart home application will soon be deployed in a real smart home being built as part of the SM4all project, which has received funding under the EU’s Seventh Framework Programme.
g.tec, which was founded by Christoph Guger and Günter Edlinger in 1999 as a spin-off from the Graz University of Technology, sells its award-winning technology to companies, universities and research institutes in 55 countries.
This is the second of a two-part special feature on virtual reality and the Presenccia project funded under the FET Pro-active scheme of the EU’s Sixth Framework Programme for research.