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Saturday, July 12, 2008

Hot super-Earths could host life after all

Rocky super-Earths may host life (Illustration: ESO)
Rocky super-Earths may host life (Illustration: ESO)

  • NewScientist.com news service
  • Ker Than
Massive, rocky worlds called 'super-Earths' – even those orbiting searingly close to their stars – may provide the right conditions for life, new research suggests.

At up to 15 times the mass of Earth, the rocky bodies are bigger and easier to spot than Earth-sized worlds, which have yet to be detected. In fact, technological advances recently led to the discovery of up to 45 new super-Earths, and astronomers say a third of all Sun-like stars may host the brawny planets.

But could they host life? "There's no reason why the different chemical cycles that are important for life on our planet wouldn't work on super-Earths," says Lisa Kaltenegger of the Harvard-Smithsonian Center for Astrophysics in Massachusetts, US.

Kaltenegger helped organise a recent conference session on the topic, and she says the consensus of attendees was similarly positive – even for those planets once dismissed as being too harsh for life.

Fire and ice

Super-Earths orbiting close to their stars, for example, experience gravitational tugs that keep them 'tidally locked' to their hosts. That means one side of such a planet always faces its star, the way the Moon always shows the same side to Earth.

Astronomers previously assumed such planets would be two-faced worlds of fire and ice, with one half molten and the other frozen.

Early models suggested the atmospheres of such worlds would quickly vanish, as water vapour and other atmospheric molecules on the planet's dark side would turn to ice and plunge to the ground. "It was thought that after the atmosphere on the dark side was completely iced out, then it would suck atmosphere from the hot side, freezing that out as well," Kaltenegger told New Scientist.

But new models show that if a tidally locked super-Earth has an atmosphere at least as dense as Earth's, strong winds could transport heat from its hot side to its cold side. Similarly, if the planet has a global ocean, its currents could help spread the warmth.

This effect still wouldn't offset the intense heat the planets would experience at close distances to Sun-like stars. But it means super-Earths could potentially host life as close as 0.05 astronomical units away from dim stars known as red dwarfs, which make up about 85% of the stars in the galaxy (for comparison, Mercury lies 0.38 AU away from the Sun).

Shifting plates

And in some ways, super-Earths might even be more likely to support life than their Earth-sized cousins, scientists say.

Recent research suggests that super-Earths will experience more plate tectonic activity than smaller rocky worlds.

On Earth, plate tectonics – the shifting and colliding of continental plates – is necessary for life.

It plays a crucial role in the carbon-silicate cycle, which releases carbon dioxide into the atmosphere, warming the planet. Plate tectonics also locks the greenhouse gas in surface rocks and sequesters it in Earth's interior so that the planet doesn't heat up too much.

"The way we have experienced life on Earth is enabled by plate tectonics," says Diana Valencia, a graduate student at Harvard.

Super-Earths should have larger molten cores and should generate more heat than Earth-sized worlds, Valencia told New Scientist. This could cause more vigorous convection in the planets' mantles and create thinner plates that slip and slide more easily.

Eventually, missions such as NASA's upcoming Kepler space telescope could find an Earth-sized planet in our galaxy. "But there's going to be a lot of super-Earths discovered before that," Valencia says. "If we're concerned about finding life, those are the planets we should be investigating right now."

Astrobiology - Learn more in our out-of-this-world special report.


Pluto Gets Respect: Dwarf Planets to Be Called 'Plutoids'

Who Needs Planets When You've Got Plutoids?
Who Needs Planets When You've Got Plutoids?

June 11, 2008 -- Pluto is finally getting its day in the sun, after being stripped of planetary status by astronomers two years ago.

From now on all similar distant bodies in the solar system will be called "plutoids." That's the decision by the International Astronomical Union, which met last week in Oslo, Norway, and announced the decision Wednesday.

The same group raised a cosmic fuss when it demoted the once-ninth planet to "dwarf" status in 2006. The new policy allows Pluto to be the standard for a whole new category of dwarf planets.

Pluto is one of only two plutoids, the other being Eris. Both are objects that circle the sun and are too small to be considered planets, but big enough to have a level of gravity that keeps them in a near spherical shape. Plutoids also must be farther from the sun than Neptune.

It was the 2003 discovery of Eris -- a body bigger and farther from the sun than Pluto -- that eventually led to Pluto's demotion. But the astronomers expect more plutoids to be discovered in the future.

When Pluto was demoted, the astronomical union always planned on naming the new category of objects after the former planet, but had to find the right name, said IAU president Catherine Cesarsky, a French astrophysicist. Their first choice, pluton, was already used by geologists.

The astronomers' action makes Pluto more important, Cesarsky said. Instead of being a "puny" outer planet, Pluto is now a "prototype of a new type of fascinating objects," she said.

"It doesn't really roll off the tongue very well," said Mike Brown, the California Institute of Technology astronomer who discovered Eris. "Maybe it'll make it."

It was not enough to satisfy leading Pluto-as-a-planet advocate Alan Stern, a former NASA space sciences chief and principal investigator on a mission to Pluto. Stern said a rival group could be formed to the IAU, which he said was too secretive in its decision-making.

"It's just some people in a smoke-filled room who dreamed it up," Stern said. "Plutoids or hemorrhoids, whatever they call it. This is irrelevant."

Another Pluto supporter was at least partially pleased.

"It's going in the right direction," laughed Ralph McNutt, a planetary scientist at Johns Hopkins University. "I'd still rather have it just be known as a planet."

"I grew up with nine planets, I'm sorry," McNutt said.

For those of you keeping score at home, the solar system now stands at: Planets 8, Plutoids 2.

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The "Great Attractor": What is the Milky Way Speeding Towards at 14 Million MPH?

Milky_way Astronomers have known for years that something seems to be pulling our Milky Way and tens of thousands of other galaxies toward itself at a breakneck 22 million kilometers (14 million miles) per hour. But they couldn’t pinpoint exactly what or where it is.

A huge volume of space that includes the Milky Way and super-clusters of galaxies is flowing towards a mysterious, gigantic unseen mass named mass astronomers have dubbed "The Great Attractor," some 250 million light years from our Solar System.

The Milky Way and Andromeda galaxies are the dominant structures in a galaxy cluster called the Local Group which is, in turn, an outlying member of the Virgo supercluster. Andromeda--about 2.2 million light-years from the Milky Way--is speeding toward our galaxy at 200,000 miles per hour.

This motion can only be accounted for by gravitational attraction, even though the mass that we can observe is not nearly great enough to exert that kind of pull. The only thing that could explain the movement of Andromeda is the gravitational pull of a lot of unseen mass--perhaps the equivalent of 10 Milky Way-size galaxies--lying between the two galaxies.

Meanwhile, our entire Local Group is hurtling toward the center of the Virgo cluster at one million miles per hour.

The Milky Way and its neighboring Andromeda galaxy, along with some 30 smaller ones, form what is known as the Local Group, which lies on the outskirts of a “super cluster”—a grouping of thousands of galaxies—known as Virgo, which is also pulled toward the Great Attractor. Based on the velocities at these scales, the unseen mass inhabiting the voids between the galaxies and clusters of galaxies amounts to perhaps 10 times more than the visible matter.

Even so, adding this invisible material to luminous matter brings the average mass density of the universe still to within only 10-30 percent of the critical density needed to "close" the universe. This phenomena suggests that the universe be "open." Cosmologists continue to debate this question, just as they are also trying to figure out the nature of the missing mass, or "dark matter."

It is believed that this dark matter dictates the structure of the Universe on the grandest of scales. Dark matter gravitationally attracts normal matter, and it is this normal matter that astronomers see forming long thin walls of super-galactic clusters.

Recent measurements with telescopes and space probes of the distribution of mass in M31 -the largest galaxy in the neighborhood of the Milky Way- and other galaxies led to the recognition that galaxies are filled with dark matter and have shown that a mysterious force—a dark energy—fills the vacuum of empty space, accelerating the universe's expansion.

Astronomers now recognize that the eventual fate of the universe is inextricably tied to the presence of dark energy and dark matter.The current standard model for cosmology describes a universe that is 70 percent dark energy, 25 percent dark matter, and only 5 percent normal matter.

We don't know what dark energy is, or why it exists. On the other hand, particle theory tells us that, at the microscopic level, even a perfect vacuum bubbles with quantum particles that are a natural source of dark energy. But a naïve calculation of the dark energy generated from the vacuum yields a value 10120 times larger than the amount we observe. Some unknown physical process is required to eliminate most, but not all, of the vacuum energy, leaving enough left to drive the accelerating expansion of the universe.

A new theory of particle physics is required to explain this physical process.

The universe as we see it contains only the stable relics and leftovers of the big bang: unstable particles have decayed away with time, and the perfect symmetries have been broken as the universe has cooled, but the structure of space remembers all the particles and forces we can no longer see around us.

Discovering what it is that makes up the heart of the Great Attractor -- will surely rank as one of the greatest discoveries in the history of science.

Recent findings suggest these motions are the result of gravitational forces from not one, but two things: the Great Attractor, and a conglomerate of galaxies far beyond it.

The location of the Great Attractor was finally determined in 1986 and lies at a distance of 250 million light years from the Milky Way, in the direction of the Hydra and Centaurus constellations. That region of space is dominated by the Norma cluster, a massive cluster of galaxies, and contains a preponderance of large, old galaxies, many of which are colliding with their neighbors, and or radiating large amounts of radio waves.

Major concentration of galaxies lies beyond the Great Attractor, near the so-called Shapley Supercluster, 500 million light-years away—the most massive known super-cluster. Mapping X-ray luminous galaxy clusters in the Great Attractor region has shown that the pull our galaxy is experiencing is most likely due to both the nearby Great Attractor and these more distant structures.

In the 1987, a group of astronomers known as the "Seven Samurai," at Cal Tech uncovered this coordinated motion of the Milky Way and our several million nearest galactic neighbors. They found that galaxies are very unevenly distributed in space, with galactic super-clusters separated by incredibly huge voids of visible ordinary matter. The place towards which we all appear headed was originally called the New Supergalactic Center or the Very Massive Object until one of the discoverers, Alan Dressler, decided they needed a more evocative name and came up with "The Great Attractor."

The motion of local galaxies indicated there was something massive out there that are pulling the Milky Way, the Andromeda Galaxy, and other nearby galaxies towards it. For a while, nobody could see what it was, because it lies behind the plane of our Galaxy --- that means the gas and dust in our Galaxy obscures the light from the Great Attractor, and it is outshone by the stars and other objects in our Galaxy.

The Great Attractor is a diffuse concentration of matter some 400 million light-years in size located around 250 million light-years away within the so-called "Centaurus Wall" of galaxies , about seven degrees off the plane of the Milky Way. X-ray observations with the ROSAT satellite then revealed that Abell 3627 is at the center of the Great Attractor. It lies in the so-called Zone of Avoidance, where the dust and stars of the Milky Way's disk obscures as much as a quarter of the Earth's visible sky.

Posted by Casey Kazan. Image credit: Wally Pacholtz

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Rare 'Star-Making Machine' Found In Distant Universe


The green and red splotch in this image is the most active star-making galaxy in the very distant universe. (Credit: NASA/JPL-Caltech/Subaru)

Astronomers have uncovered an extreme stellar machine -- a galaxy in the very remote universe pumping out stars at a surprising rate of up to 4,000 per year. In comparison, our own Milky Way galaxy turns out an average of just 10 stars per year.

The discovery, made possible by several telescopes including NASA's Spitzer Space Telescope, goes against the most common theory of galaxy formation. According to the theory, called the Hierarchical Model, galaxies slowly bulk up their stars over time by absorbing tiny pieces of galaxies -- and not in one big burst as observed in the newfound "Baby Boom" galaxy.

"This galaxy is undergoing a major baby boom, producing most of its stars all at once," said Peter Capak of NASA's Spitzer Science Center at the California Institute of Technology, Pasadena. "If our human population was produced in a similar boom, then almost all of the people alive today would be the same age." Capak is lead author of a new report detailing the discovery in the July 10th issue of Astrophysical Journal Letters.

The Baby Boom galaxy, which belongs to a class of galaxies called starbursts, is the new record holder for the brightest starburst galaxy in the very distant universe, with brightness being a measure of its extreme star-formation rate. It was discovered and characterized using a suite of telescopes operating at different wavelengths. NASA's Hubble Space Telescope and Japan's Subaru Telescope, atop Mauna Kea in Hawaii, first spotted the galaxy in visible-light images, where it appeared as an inconspicuous smudge due to is great distance.

It wasn't until Spitzer and the James Clerk Maxwell Telescope, also on Mauna Kea in Hawaii, observed the galaxy at infrared and submillimeter wavelengths, respectively, that the galaxy stood out as the brightest of the bunch. This is because it has a huge number of youthful stars. When stars are born, they shine with a lot of ultraviolet light and produce a lot of dust. The dust absorbs the ultraviolet light but, like a car sitting in the sun, it warms up and re-emits light at infrared and submillimeter wavelengths, making the galaxy unusually bright to Spitzer and the James Clerk Maxwell Telescope.

To learn more about this galaxy's unique youthful glow, Capak and his team followed up with a number of telescopes. They used optical measurements from Keck to determine the exact distance to the galaxy -- a whopping12.3 billion light-years. That's looking back to a time when the universe was 1.3 billion years old (the universe is approximately 13.7 billion years old today).

"If the universe was a human reaching retirement age, it would have been about 6 years old at the time we are seeing this galaxy," said Capak.

The astronomers made measurements at radio wavelengths with the National Science Foundation's Very Large Array in New Mexico. Together with Spitzer and James Clerk Maxwell data, these observations allowed the astronomers to calculate a star-forming rate of about 1,000 to 4,000 stars per year. At that rate, the galaxy needs only 50 million years, not very long on cosmic timescales, to grow into a galaxy equivalent to the most massive ones we see today.

While galaxies in our nearby universe can produce stars at similarly high rates, the farthest one known before now was about 11.7 billion light-years away, or a time when the universe was 1.9 billion years old.

"Before now, we had only seen galaxies form stars like this in the teenaged universe, but this galaxy is forming when the universe was only a child," said Capak. "The question now is whether the majority of the very most massive galaxies form very early in the universe like the Baby Boom galaxy, or whether this is an exceptional case. Answering this question will help us determine to what degree the Hierarchical Model of galaxy formation still holds true."

"The incredible star-formation activity we have observed suggests that we may be witnessing, for the first time, the formation of one of the most massive elliptical galaxies in the universe," said co-author Nick Scoville of Caltech, the principal investigator of the Cosmic Evolution Survey, also known as Cosmos. The Cosmos program is an extensive survey of a large patch of distant galaxies across the full spectrum of light.

"The immediate identification of this galaxy with its extraordinary properties would not have been possible without the full range of observations in this survey," said Scoville.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA.

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How NASA Might Find Rock-Eating Microbes on Mars

By Michael Schirber, Astrobiology Magazine

Signs of life on Mars may be hiding under its rocks, or perhaps hiding inside those rocks. A new study offers a simplified technique for detecting biological and pre-biotic molecules that become trapped inside minerals.

Studying seven samples of the mineral jarosite collected from various places on Earth, a group of researchers was able to identify amino acids, the basic components of proteins, that had presumably been incorporated into the mineral's crystal structure.

Although not the first time biological compounds have been detected inside rock, the new method has the advantage that it works "at very low concentration without prior sample preparation," said Nancy Hinman of the University of Montana.

Hinman and her colleagues believe their technique would be perfect for looking at martian samples brought back from a future mission.

Minerals and microbes

Jarosite is a yellowish-brown sulfate mineral containing iron, potassium and hydroxide. It is found in places around the world such as southern California beaches and volcanic fields in New Zealand. It forms only in the presence of highly acidic water.

In 2004, jarosite was discovered on Mars by Opportunity, one of NASA's Mars Exploration Rovers. Scientists immediately heralded it as clear evidence for past water on the red planet.

But there is something else about jarosite that makes it interesting. One of the steps in its formation involves combining pyrite (ferrous sulfide) with oxygen. This oxidation reaction can be performed by certain "rock-eating" microorganisms.

"The rate of the jarosite formation would be extremely slow without microbes and the presence of water," Hinman said.

Whether jarosite can form without the assistance of these microbes is very difficult to say, since every corner of Earth is occupied by little bugs of some sort or another.

"I don't know of any environment devoid of microorganisms," Hinman said. "Earth is not a good test bed for abiotic processes."

But perhaps Mars is. There are theories for how jarosite might form in the absence of life.

"It's a very oxidizing environment on Mars," explained co-author Michelle Kotler, also from the University of Montana. Jarosite could therefore arise from chemical weathering of the planet's abundant basalt rocks.

Garbage can

And yet, there remains the tantalizing possibility that martian jarosite owes its existence to the martian version of rock-eating microbes. If so, remnants of these organisms may be locked in the mineral.

This is because jarosite on Earth is known to let all sorts of foreign elements incorporate into its crystal structure.

"It's a bit of a garbage can mineral," Hinman said.

Among the foreign substances are organic compounds. However, previous techniques for detecting them required that the jarosite be dissolved in a solution or mixed in with some other medium, which dilutes the sample and runs the risk of introducing contamination.

"We are very concerned about contamination," Hinman said.

Hinman and her colleagues have a technique that requires no sample preparation. They use a laser-based optical and chemical imager (LOCI), located in co-author Jill Scott's lab at the Idaho National Laboratory. A single laser shot vaporizes a small portion of the crystal surface into individual ions. These pass through a mass spectrometer, which can identify each ion by how much mass and charge it has.

In four of the seven samples, the scientists detected glycine, the smallest of the amino acids required for making proteins.

Sample return

"This study shows that a molecule basic to life can be detected in an important martian mineral using an instrument that might fly on a future spacecraft," said Carlton Allen, Astromaterials Curator at NASA Johnson Space Center.

But the method probably will not be suitable for any near-term missions because of the mass and complexity of the LOCI instrument, said David Beaty, chief scientist of the Mars Exploration Directorate at the Jet Propulsion Laboratory.

Instead, the technique could be used for sample return missions that NASA researchers are currently planning for.

"The advantage of our method is that it doesn't need sample preparation," Kotler said. "We just put the rock in the machine and shoot it."

Not only can their technique identify organics, but it can also measure the isotope ratios of carbon and other elements. If the accuracy can be improved, this measurement could potentially tell researchers whether the organic molecules they find came from living things or not.

"There's an advantage for organisms to use the lighter isotopes," Kotler explained. This shows up, for example, as a higher percentage of the isotope carbon-12 versus carbon-13 in biological samples.

Although jarosite possibly may have provided martian biomolecules safe haven from the planet's harsh UV radiation, astrobiologists are interested in studying a whole list of martian minerals.

"One thing that is becoming clear is that the total scientific return on [a sample return] mission would be dependent on the diversity of the sample collection, and it is important to plan for ways to optimize that diversity," Beaty said.

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Your Skin Produces Marijuana-Like Substance

By Robin Nixon, Special to LiveScience

Marijuana-like substances made by the skin are necessary for a healthy complexion, a new study concludes.

Back up. We've got pot growing out of our skin?

Essentially, yes. The skin has joined the growing club of organs that is known to produce "endocannabinoids" — the body's own reefer. The biggest producer of endogenous pot is the brain.

Significantly, the new study pins down long-suspected connections between brain and skin and between stress and zits.

Your thinking skin

In the skin, explained lead researcher Tamás Bíró of the University of Debrecen, Hungary, these compounds help the sebaceous glands protect us from harsh outer elements, such as the drying effects of wind and sun. Cannabinoids are thought to have a similar role in the leaves of the marijuana plant.

Among its protective functions, "endo-pot" stimulates oil production and tells hair follicles to stop producing hair. Whether this explains the plethora of pimples and receding hairlines at Grateful Dead concerts (or those of former band members) has not yet been determined.

The research, funded mostly by the Hungarian and German governments, will be detailed in the October 2008 issue of The Federation of American Societies for Experimental Biology (FASEB) Journal.

Why is a psycho-stimulant working outside the brain?

Dermatologists have long suggested that mental states affect the skin, having observed flare-ups of acne, psoriasis, hair loss and other conditions that coincide with stress. Now, they are finding that the skin responds to, and produces, compounds called neuropeptides previously thought to exist exclusively in the brain. This is said to prove the brain-skin connection by nailing down the mechanism.

"It is working in both directions," said Andrzej Slominski, a researcher at the University of Tennessee who was not involved with the endocannabinoids study but does research on the skin's neuroendocrine system.

Brain-skin connection

Neuropeptides — such as serotonin, melatonin, cortisol and, possibly endocannabinoids — are made by the skin in response to environmental stressors or rewards such as thorns, humidity, sunshine or a refreshing breeze. These compounds can then spur the brain to alter behavior, Slominski explained.

Conversely, psychological stress sends signals from the brain to the skin.

The discoveries are giving credence to old wives' tales that connect skin condition with mental state. Yes, perhaps exam period did give you that pimple.

Because the skin is less complex than the brain, it knows only a few names for stress, said Slominski.

Therefore, the skin may respond to emotional distress as if the body is under physical attack. Protective lubricants are increased (resulting in oily skin) and less critical functions (like growing hair) may be halted.

Even though the skin is the simpler organ, as primates evolved our skin likely learned to deal with stress before the brain did, said Slominski. The skin, the body's largest organ, is continuously exposed to a stressful environment, he pointed out. Of all organs, it had the most pressing evolutionary need to develop protective responses.

Later, the skin's stress responses were adopted and perfected by the brain, he said, which explains why the same compounds have similar effects in each organ.

Natural high?

While these discoveries may lead to breakthrough topical treatments, such as the use of endocannabinoids to treat chronically dry and itchy skin, the research may also inspire the pursuit of relaxation in the name of a glowing complexion and a full head of hair.

What about the endo-pot already on our skin? Can it get us high?

"Theoretically, yes," said Bíró. But, while our skin is constantly pumping out its own type of hash, even if you chewed your arm to bits, he continued, there isn't enough to have a psychological effect.

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The Brain Hides Information From Us To Prevent Mistakes

When we notice a mosquito alight on our forearm, we direct our gaze in order to find its exact position and quickly try to swat it or brush it away to prevent it bite us. This apparently simple, instantaneous reaction is the result of a mental process that is much more complex than it may seem. It requires the brain to align the tactile sensation on the skin with spatial information about our surroundings and our posture.

For the first time, a study done by the Cognitive Neuroscience Research Group (GRNC), attached to the Barcelona Science Park, has shown how this process unfolds over time, examining the conflicts posed by the coexistence of differing spatial maps in the brain. GRNC researchers Salvador Soto-Faraco (ICREA research professor) and Elena Azañón conducted the new study.

“The main finding of the study is that it has enabled us to confirm that tactile sensations are initially located unconsciously in anatomical coordinates, but they reach our awareness only when the brain has formed an image of their origin in the spatial coordinates, external to the body,” explained Salvador Soto-Faraco. The coexistence of different spatial reference frames in the brain has been known for some time. So has the fact that confusions between them may result in some cases, such as when we invert the usual anatomical position of some body parts (e.g. when crossing our arms over the body midline). “The brain sorts out problems of this kind rapidly, in a matter of tenths of a second. To do so, however, it has to integrate information arriving in formats that are quite disparate”, Sotoa-Faraco added. “Our research has helped us understand how this process works and how the brain manages spatial realignment when faced with conflict”, he concluded.

A simple example serves to illustrate the confusion that can occur when different spatial reference frames are set in conflict: cross one of your arms over the other, then interleave the fingers of both hands together, palms touching, and turn your hands towards your body so that the left hand is on the right side and vice versa. While holding this position, if you receive an instruction but no direct physical contact that you are to move one of your fingers, you will most likely move the equivalent finger of the opposite hand.

In order to determine how long it takes for the brain to realign these conflicting spatial reference frames, the GRNC researchers devised a specific methodology that enabled indirect measurement of the location of a tactile sensation on the skin. To do this, they measured response times to a brief flash (produced with an LED light emitting diode) appearing near one of the observer’s hands. The researchers then compared the reaction times to the flash when it had appeared near a hand that had previously received a tactile stimulus, versus when the flash had appeared near the opposite hand. In the main study, the participants (a group of 32 university students) were asked to cross their arms so that their right hand lay in their left-hand visual field and vice versa. The purpose of this procedure was to ensure that the actual external position of the hands was in conflict with their anatomical location.

Each participant underwent roughly 600 essays of this sort. The time between the tactile sensation and the appearance of the target visual stimulus, as well as their realtive locations, were varied at random. It was observed that the participants’ responses to the flash changed dramatically as a function of the time elapsed between receiving the tactile sensation and the presentation of the visual stimulus. In the initial phase (60 ms or earlier), the brain tended to locate the tactile sensation in anatomical terms, i.e. if it received the sensation on the left hand, even though it was crossed over to the right- visual field, the sensation was processed as though it had happened on the left-hand side of the body. However, only a few tenths of a second later (roughly 200 ms), compensation occurred and the tactile sensation was determined to arise from the right-hand side.

Curiously, when participants in the study were asked to locate the tactile stimulus explicitly, they always referred their response to its external source. This reveals that, although a transition occurs from an initial anatomically-based reference frame towards a visually or externally-based reference frame, we apparently become aware of the tactile sensation in the latter phase.

“The study’s results have allowed us to deepen our understanding of how tactile information is located, suggesting that our brain avoids confusions among the various spatial reference frames by keeping the initial part of the process below the threshold of awareness”, explained Soto-Faraco. “Put simply, it could be said that this system of spatial transformation works much as when we hastily jot down some rough notes and later copy them out into final form, discard the original draft,” he concluded.

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Cow farts collected in plastic tank for global warming study

Scientists are examining cow farts and burps in a novel bid to combat global warming.

A cow stands in her pen at the National Institute of Agricultural Technology in Castelar, near Buenos Aires. Argentine scientists are taking a novel approach to studying global warming, strapping plastic tanks to the backs of cows to collect methane
REUTERS
Argentine scientists are strapping plastic tanks to the backs of cows

Experts said the slow digestive system of cows makes them a key producer of methane, a potent greenhouse gas that gets far less public attention than carbon dioxide.

In a bid to understand the impact of the wind produced by cows on global warming, scientists collected gas from their stomachs in plastic tanks attached to their backs.

The Argentine researchers discovered methane from cows accounts for more than 30 per cent of the country's total greenhouse emissions.

As one of the world's biggest beef producers, Argentina has more than 55 million cows grazing in its famed Pampas grasslands.

Guillermo Berra, a researcher at the National Institute of Agricultural Technology, said every cow produces between 8000 to 1,000 litres of emissions every day.

Methane, which is also released from landfills, coal mines and leaking gas pipes, is 23 times more effective at trapping heat in the atmosphere than carbon dioxide.

Scientists are now carrying out trials of new diets designed to improve cows's digestion and hopefully reduce global warming. Silvia Valtorta, of the National Council of Scientific and Technical Investigations, said that by feeding cows clover and alfalfa instead of grain "you can reduce methane emissions by 25 percent".

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MIT opens new 'window' on solar energy

Cost effective devices expected on market soon

Elizabeth A. Thomson, News Office

Imagine windows that not only provide a clear view and illuminate rooms, but also use sunlight to efficiently help power the building they are part of. MIT engineers report a new approach to harnessing the sun's energy that could allow just that.

The work, to be reported in the July 11 issue of Science, involves the creation of a novel "solar concentrator." "Light is collected over a large area [like a window] and gathered, or concentrated, at the edges," explains Marc A. Baldo, leader of the work and the Esther and Harold E. Edgerton Career Development Associate Professor of Electrical Engineering.

As a result, rather than covering a roof with expensive solar cells (the semiconductor devices that transform sunlight into electricity), the cells only need to be around the edges of a flat glass panel. In addition, the focused light increases the electrical power obtained from each solar cell "by a factor of over 40," Baldo says.

Because the system is simple to manufacture, the team believes that it could be implemented within three years--even added onto existing solar-panel systems to increase their efficiency by 50 percent for minimal additional cost. That, in turn, would substantially reduce the cost of solar electricity.

In addition to Baldo, the researchers involved are Michael Currie, Jon Mapel, and Timothy Heidel, all graduate students in the Department of Electrical Engineering and Computer Science, and Shalom Goffri, a postdoctoral associate in MIT's Research Laboratory of Electronics.

"Professor Baldo's project utilizes innovative design to achieve superior solar conversion without optical tracking," says Dr. Aravinda Kini, program manager in the Office of Basic Energy Sciences in the U.S. Department of Energy's Office of Science, a sponsor of the work. "This accomplishment demonstrates the critical importance of innovative basic research in bringing about revolutionary advances in solar energy utilization in a cost-effective manner."

Solar concentrators in use today "track the sun to generate high optical intensities, often by using large mobile mirrors that are expensive to deploy and maintain," Baldo and colleagues write in Science. Further, "solar cells at the focal point of the mirrors must be cooled, and the entire assembly wastes space around the perimeter to avoid shadowing neighboring concentrators."

The MIT solar concentrator involves a mixture of two or more dyes that is essentially painted onto a pane of glass or plastic. The dyes work together to absorb light across a range of wavelengths, which is then re-emitted at a different wavelength and transported across the pane to waiting solar cells at the edges.

In the 1970s, similar solar concentrators were developed by impregnating dyes in plastic. But the idea was abandoned because, among other things, not enough of the collected light could reach the edges of the concentrator. Much of it was lost en route.

The MIT engineers, experts in optical techniques developed for lasers and organic light-emitting diodes, realized that perhaps those same advances could be applied to solar concentrators. The result? A mixture of dyes in specific ratios, applied only to the surface of the glass, that allows some level of control over light absorption and emission. "We made it so the light can travel a much longer distance," Mapel says. "We were able to substantially reduce light transport losses, resulting in a tenfold increase in the amount of power converted by the solar cells."

This work was also supported by the National Science Foundation. Baldo is also affiliated with MIT's Research Laboratory of Electronics, Microsystems Technology Laboratories, and Institute for Soldier Nanotechnologies.

Mapel, Currie and Goffri are starting a company, Covalent Solar, to develop and commercialize the new technology. Earlier this year Covalent Solar won two prizes in the MIT $100K Entrepreneurship Competition. The company placed first in the Energy category ($20,000) and won the Audience Judging Award ($10,000), voted on by all who attended the awards.

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Biodiversity: Some species could be wiped out 100 times faster than feared, say researchers

Ian Sample, science correspondent


Mountain gorilla in the Virunga Mountains of Rwanda. Photograph: Andy Rouse/Corbis

Endangered species could become extinct 100 times faster than previously thought, scientists warned yesterday in a bleak reassessment of the threats to global biodiversity. They say methods used to predict when species will die out are seriously flawed and dramatically underestimate the speed at which some will disappear.

The findings, presented in the journal Nature, suggest that animals such as the western gorilla, the Sumatran tiger and Malayan sun bear, the smallest of the bear family, may become extinct much sooner than conservationists had feared.

Ecologists Brett Melbourne, at the University of Colorado at Boulder, and Alan Hastings at the University of California, Davis said conservation organisations should use updated extinction models to urgently re-evaluate the risks to wildlife. "Some species could have months instead of years left, while other species that haven't even been identified as under threat yet should be listed as endangered," said Melbourne.

The warning has particular implications for the International Union for Conservation of Nature (IUCN), which compiles an annual "red list" of endangered species. Last year the list upgraded western gorillas to critically endangered, after populations of a subspecies were found to have been badly affected by Ebola virus and the commercial trade in bushmeat.

The Yangtze river dolphin was listed as critically endangered, but could possibly be already extinct.

The researchers analysed mathematical models used to predict extinction risks and found that while they included some factors crucial to predicting a species' survival they overlooked others. For example, models took into account the fact that some animals died from rare accidents such as falling out of a tree. They also included chance environmental threats, such as sudden heatwaves or rainstorms that could kill off animals.

But what the extinction models failed to include was the proportion of males compared with females in a population, and the differences in reproductive success between individuals in the group. When they factored these aspects into risk assessments for particular species they found the danger of extinction rose substantially.

"The older models could be severely overestimating the time to extinction. Some species could go extinct 100 times sooner than we expect," Melbourne said.

The researchers showed that the missing factors - the number of males to females, and variations in the number of offspring - were capable of causing unexpected large swings in the size of a population, sometimes causing it to grow but also increasing the risk that a population crashed and became extinct.

To test the new models, Melbourne's team studied populations of beetles in the laboratory. "The results showed that the old models misdiagnosed the importance of different types of randomness, much like miscalculating the odds in an unfamiliar game of cards because you didn't know the rules," he said.

For some endangered species, such as mountain gorillas, conservationists could collect data on individuals and plug the information into models to predict these animals' chances of survival.

"For many other species, like marine fish, the best biologists can do is measure abundances and population fluctuations," Melbourne said.

Craig Hilton-Taylor, who manages the IUCN red list in Cambridge, said extinction estimates were often inadequate. "We are certainly underestimating the number of species that are in danger of becoming extinct because there are around 1.8m described species and we've only been able to assess 41,000 of those."

The latest study could help refine models used to decide which species are put on the red list, he said. "We are constantly looking at how we evaluate extinction risk, and it may be they have hit on something that can help us."

More than 16,000 species worldwide are threatened with extinction, according to a 2007 report from the IUCN. One in four mammal species, one in eight bird species and one in three amphibian species are on the organisation's red list. An updated list is due to be published in October.

Next week, the IUCN is expected to highlight the dire state of the world's corals after surveying the condition of more than 1,000 species around the world.

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Solar Powered Bubble Plane is Awesome

A design for an ultra-environmental aricraft just won the top prize at the prestigious Lucky Strike Junior Designer Award. Roland Cernat, who just graduated from the University of Applied Sciences Schwäbisch Gmünd / Germany created the airplane with the environment in mind.

First, once in the air, it can travel entirely fuelessly, much like other ultra-light gliders. It can tuck away it's tiny propellers for 100% aerodynamic flight. But when it needs an extra boost, generally for take-off, the glider's propellers unfurl, driven by a small electric motor that is powered either by an on-board generator or by thin film solar panels on the planes wings and tail.

We've seen other ultra-lights that get good gas mileage, but every component of this plane was constructed for minimal environmental impact.

The cockpit is constructed entirely from a new kind of plastic that can be melted and re-molded infinitely for cradle to cradle use. It also allows the entire body of the airplane to be clear. And though some (including myself) might this find extremely disconcerting, others would love the experience.

I talked briefly with Roland about the design, and wondered what kind of fuel efficiency one could expect. He said, flying at night and with the worst winds possible, a flight would be about 30 miles per gallon. But with the trickle charge of the solar panels, plus an option to charge from the grid, it's possible that the plane would use absolutely no energy over the course of a flight.

Now that's an airplane I can get excited about!

Check out more images of the glider below.

Ausra Goes Viva Las Vegas with Solar Thermal Power Factory

Ausra, a developer of utility-scale solar thermal power, has opened their solar thermal power parts factory in brightly lit Sin City. It is the first of its kind in the US and the highest capacity plant in the world. As if you needed another great reason to visit Las Vegas, right? The factory will produce reflectors, absorber tubes and other components of the company’s solar thermal power plants, and will produce upwards of 700 MW of solar electricity generation equipment each year.

The excitement bubbling around this fairly boring announcement is that the opening of the factory brings us that much closer to large-scale solar thermal electricity generation. The factory triples worldwide manufacturing capacity and will help speed up the industry on the whole. Last year Ausra paired up with California’s PG&E on a power purchase agreement for a 177 MW solar thermal power plant in central California, and this new Nevada-based factory will make the equipment needed for this project and many others.

While the factory employs only 50 workers, according to Ausra’s output rate, they figure they’re creating about 1,400 green collar construction jobs for building solar plants – a much needed job boost in a much needed industry.

Knowing that we’re moving past prototypes into large-scale development of solar thermal electricity generation systems gives me confidence that we’re finally gathering speed in the right direction. Now if the BLM will just get their act together

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New, Cost Effective Solar Energy Devices from MIT

How do astronomers get dates?

Q: How do astronomers get dates?

A: Ask a lot of heavenly bodies.

Go ahead and ogle NGC 6791:

Whoa. That’s an open cluster, a collection of thousands of stars that are (in general) gravitationally bound to one another. In reality, over millions of years, the stars interact with each gravitationally, and a lot of the stars get flung out of the cluster, becoming loners. But a large fraction of the stars stick around, aging and eventually dying while still in the cluster. They’re like city dwellers who never feel the need to leave town.

In this newly released Hubble image, you can see thousands of stars in just this one small patch of the cluster. You can see far more distant background galaxies, too (I love that kind of stuff).

But how old are these clusters, and the stars in them? Those are good questions, and important ones. The age tells us a lot about the environment of the cluster. For example, more massive stars tend to "sink" down to the center, and less massive ones move out away from the middle. How long does that take? The age of the cluster can tell us about how it moves around the Milky Way, and how stars behave in a cluster. All kinds of cool stuff can be figured out if we just know how long this guy has been around.

One advantage we have is that we’re pretty sure all the stars in the cluster formed at about the same time. Not exactly, but probably not off by that much. So if we can find the age of any of the stars, then we should know the age of all of them. Still, it turns out that’s not easy to determine. One way to is to look at the stars that have died already. We know that stars with more mass live their lives more quickly than low mass stars, eventually either exploding (if they are really massive) or blowing off their outer layers and leaving behind a white dwarf, a dense hot cinder.

So, if you want to date the cluster, look at the white dwarfs. Once formed, they don’t generate any more heat, so they simply sit there and cool off like a chunk of charcoal. We know how that works, so we can work backwards to get the age of the cluster.

Astronomers used Hubble to observe NGC 6791, a cluster that sits a little over 13,000 light years away toward the summer constellation of Lyra. They made that gorgeous image above, and looked for white dwarfs. They found a bunch, got their ages… and immediately had a problem: they got two different ages. Some of the dead stars appeared to be 4 billions years old (a little younger than the Sun), and others appeared to be 6 billion years old. Ouch. Worse, another technique used to get the ages of normal stars showed them to be 8 billion years old.

Uh oh.

In the image above, a zoom of the previous image, the younger appearing white dwarfs are circled in blue, and the older ones in red. Why would there be two separate populations of white dwarfs?

Well, there probably aren’t! It turns out that 13,000 light years is a long way off. The younger-seeming white dwarfs actually are binary stars, white dwarfs orbiting normal low mass stars, but they’re so far away from us they look like one single star (and it’s easier to date single stars than ones in a committed relationship). The light from the normal star changes the color we see, making us think the star is younger, when in fact it’s not.

So that fixes the 4 and 6 billion year issue; the white dwarfs are probably all 6 billion years old (why do stars want to look younger all the time?). But there’s still the problem that the normal stars in the cluster look like they’re 8 billion years old. Why would the dwarfs look younger?

Maybe they evolved differently than we expected while they were still alive. Maybe there’s something about the cool-down rates of white dwarfs we don’t understand. Maybe there’s something about the normal stars in the cluster that make them look older. It’s hard to say.

My suspicion is that the white dwarfs cool more slowly than we think. It takes them longer to get to a lower temperature, so when we look at them now they’re warmer than we expect, so we think they’re younger. What could do that? It might be that they have an odd chemical composition which affects their cooling rate (the presence or absence of some elements can affect how well a star radiates away its heat). I wonder if stellar encounters might play a role as well: stars are densely distributed in clusters, and there are more encounters between stars than out here in the suburbs of space. I don’t know how that might play a part… but it usually pays to look at the environment. How is a cluster different than other parts of the galaxy? More stars, more encounters, more binaries… somewhere in there is the key to the mystery of the discrepant cluster star ages.

Only by studying more stars and more clusters are astronomers going to get answers to these questions. Happily there are lots of clusters to observe, and lots of stars in them. So truly, I was right before: how do astronomers get dates? Volume.

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'Great Green Wall' will slow down southwards spread of Sahara desert

Washington, July 9 (ANI): Preparations for an African 'wall of trees' to slow down the southwards spread of the Sahara desert are getting underway.

North African nations have been promoting the idea of a Green Belt since 2005. The project has been scaled down to reinforce and then expand on existing efforts, and will not be a continent-wide wall of trees, despite the name of the project.

According to a report in ENN (Environmental News Network), the 'Great Green Wall' will involve several stretches of trees from Mauritania in the west to Djibouti in the east, to protect the semi-arid savannah region of the Sahel, and its agricultural land, from desertification.

A plan for the proposed 3 million dollar, two-year initial phase of the project, which involves a belt of trees 7,000 kilometres long and 15 kilometres wide, was formally adopted at the Community of Sahel-Saharan States (Cen-Sad) summit on rural development and food security in Cotonou, Benin, last month (17-18 June).

The Green Wall will involve two planting projects on the east and west sides of Africa.

The Inter-State Committee for Drought Control in the Sahel region (CILSS) is working with scientific consultants and representatives from the arid nations of Burkina Faso, Mali, Mauritania, Niger, Nigeria and Senegal to launch pilot planting projects planned for September.

Another planting programme, including Chad, Djibouti, Eritrea, Ethiopia and Sudan, should be finalized within two months under the auspices of six states in the Horn of Africa, linked through the Intergovernmental Authority on Development (IGAD).

According to Mariam Aladji Boni Diallo, the Benin-based president of the Cen-Sad summit organising committee, the Green Wall should consist of more than just trees.

"Reforestation, restoration of natural resources and the eventual development of fishing and livestock breeding were priorities for the project," said Diallo. (ANI)

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Feds: Grazing doesn't fit Ore. national monument

By JEFF BARNARD , Associated Press Writer, Space & Earth science / Environment
(AP) -- Federal rangeland managers said continuing to allow cattle to graze on the Cascade-Siskiyou National Monument is harming the rare plants, fish and wildlife the monument was created eight years ago to protect.

The U.S. Bureau of Land Management was to issue an assessment of the health of the monument rangeland on Thursday, concluding that the current level of grazing is incompatible with the biological values the monument was meant to protect, said monument Assistant Manager Howard Hunter.

Dave Willis, of the Soda Mountain Wilderness Council, said he hoped the long overdue finding will help pass special legislation pending in the Senate that would make it possible for conservation groups to pay ranchers to retire their grazing leases.

The monument was created in 2000 by President Clinton from 53,000 acres of BLM land near Ashland to protect the unique area, sometimes referred to as the Klamath Knot, where the Siskiyou Mountains connect to the Cascade Range.

The area is home to 111 species of butterflies, as well as the rare Keene Creek pebblesnail and the Jenny Creek redband trout.

The proclamation Clinton signed put an end to the small amount of logging and mining within the monument, but left it up to BLM to settle the thorny question of whether to continue allowing 11 ranchers to put up to 2,417 cows with calves on the monument to graze part of the year.

The rangeland health assessment found the cattle were harming sensitive streams and springs.

The finding marks the third straight study - one by BLM and another by scientists working for conservation groups - to find that cattle were harming the monument, said Dominic DellaSala, director of the National Center for Conservation Science and Policy in Ashland.

Hunter said the bureau would go through a formal assessment of whether grazing could be modified somehow to allow cattle to remain on the monument.
DellaSala said it was "game over" for grazing. Building the fences to keep cattle out of sensitive springs and streams would cost $4 million, he said, while the grazing leases bring in just $2,000 a year.

"BLM has just been dragging their feet because there is a culture of livestock grazing at any cost," he said.

A group of ranchers has agreed to be paid by conservation groups to retire their grazing leases if the legislation passes. The bill also would designate about half the monument as wilderness, a higher level of protection.

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SANTA BARBARA, Calif. (AP) - Avocado growers have lost at least $1 million worth of fruit and about 200 acres of orchards to a wildfire in Santa Barbara County, officials said.

County Agricultural Commissioner William D. Gillette said Wednesday at least 233 acres of orchards have burned.

Gillette estimated the cost to replace trees, farm equipment, and irrigation lines, plus lost production until new trees bear fruit, will be $9.5 million over the next five to seven years.

The commissioner delivered a preliminary report to the governor's Office of Emergency Services on Wednesday. He said it was the first step in helping local farmers get financial relief for crop losses. He said the total losses to ranching and farm lands will not be known until the fire is put out.

© 2008 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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