Friday, November 19, 2010

ASTRONOMERS FIND GIANT, PREVIOUSLY UNSEEN STRUCTURE IN OUR GALAXY

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NASA's Fermi Gamma-ray Space Telescope has unveiled a previously unseen structure centered in the Milky Way -- a finding likened in terms of scale to the discovery of a new continent on Earth. The feature, which spans 50,000 light-years, may be the remnant of an eruption from a supersized black hole at the center of our galaxy.

"What we see are two gamma-ray-emitting bubbles that extend 25,000 light-years north and south of the galactic center," said Doug Finkbeiner, an astronomer at the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., who first recognized the feature. "We don't fully understand their nature or origin."

At more than 100 degrees across, the structure spans more than half of the sky, from the constellation Virgo to the constellation Grus. It may be millions of years old.

A paper on the findings will appear in an upcoming issue of The Astrophysical Journal.

Finkbeiner and Harvard graduate students Meng Su and Tracy Slatyer revealed the bubbles by processing publicly available data from the satellite's Large Area Telescope (LAT). Their work expanded on previous studies led by Greg Dobler at the Kavli Institute for Theoretical Physics in Santa Barbara, Calif.

Fermi's Large Area Telescope is the most sensitive and highest-resolution gamma-ray detector ever orbited. Gamma rays are the highest-energy form of light.

The structures eluded previous astronomers studying gamma rays due in part to the so-called diffuse emission -- a fog of gamma rays that appears all over the sky. The emissions are caused by particles moving near the speed of light interacting with light and interstellar gas in the Milky Way.

The Fermi LAT team is constantly refining models to uncover new gamma-ray sources obscured by the diffuse emission. By using various estimates of the gamma-ray fog, including the Fermi team's, Finkbeiner and his colleagues were able to subtract it from the LAT data and unveil the giant bubbles.

"The LAT team confirmed the existence of an extended structure in the direction of the inner part of the Milky Way and we're in the process of performing a deeper analysis to better understand it," said Simona Murgia, a Fermi research associate at the SLAC National Accelerator Laboratory in Menlo Park, Calif.

The researchers believe that an important process for producing the Milky Way's gamma-ray fog, called inverse Compton scattering, also lights up the bubbles. In that process, electrons moving near the speed of light collide with low-energy light, such as radio or infrared photons. The collision increases the energy of the photons into the gamma-ray part of the electromagnetic spectrum.

The bubble emissions are much more energetic than the gamma-ray fog seen elsewhere in the Milky Way.

The bubbles also appear to have well-defined edges. Taken together, the structure's shape and emissions suggest that it was formed as a result of a large and relatively rapid energy release -- the source of which remains a mystery, Finkbeiner noted.

One possibility includes a particle jet from the supermassive black hole at the galactic center. In many other galaxies, astronomers see fast particle jets powered by matter falling toward a central black hole. While there is no evidence that the Milky Way's black hole sports such a jet today, it may have in the past.

The bubbles also may have formed as a result of gas outflows from a burst of star formation, perhaps the one that produced many massive star clusters in the Milky Way's central light-years several million years ago.

"In other galaxies, we see that starbursts can drive enormous gas outflows," said David Spergel at Princeton University in New Jersey. "Whatever the energy source behind these huge bubbles may be, it is connected to many deep questions in astrophysics."

Finkbeiner noted that, in retrospect, hints of the bubbles appear in earlier spacecraft data, including the Germany-led Roentgen X-ray Satellite (ROSAT) and NASA's Wilkinson Microwave Anisotropy Probe (WMAP).

(Photo: NASA/GSFC)

Harvard-Smithsonian Center for Astrophysics

RESEARCHERS AIM TO HARVEST SOLAR ENERGY FROM PAVEMENT TO MELT ICE, POWER STREETLIGHTS

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The heat radiating off roadways has long been a factor in explaining why city temperatures are often considerably warmer than nearby suburban or rural areas. Now a team of engineering researchers from the University of Rhode Island is examining methods of harvesting that solar energy to melt ice, power streetlights, illuminate signs, heat buildings and potentially use it for many other purposes.

"We have mile after mile of asphalt pavement around the country, and in the summer it absorbs a great deal of heat, warming the roads up to 140 degrees F or more," said K. Wayne Lee, URI professor of civil and environmental engineering and the leader of the joint project. "If we can harvest that heat, we can use it for our daily use, save on fossil fuels, and reduce global warming."

The URI team has identified four potential approaches, from simple to complex, and they are pursuing research projects designed to make each of them a reality.

One of the simplest ideas is to wrap flexible photovoltaic cells around the top of Jersey barriers dividing highways to provide electricity to power streetlights and illuminate road signs. The photovoltaic cells could also be embedded in the roadway between the Jersey barrier and the adjacent rumble strip.

"This is a project that could be implemented today because the technology already exists," said Lee. "Since the new generation of solar cells are so flexible, they can be installed so that regardless of the angle of the sun, it will be shining on the cells and generating electricity. A pilot program is progressing for the lamps outside Bliss Hall on campus."

Another practical approach to harvesting solar energy from pavement is to embed water filled pipes beneath the asphalt and allow the sun to warm the water. The heated water could then be piped beneath bridge decks to melt accumulated ice on the surface and reduce the need for road salt. The water could also be piped to nearby buildings to satisfy heating or hot water needs, similar to geothermal heat pumps. It could even be converted to steam to turn a turbine in a small, traditional power plant.

Graduate student Andrew Correia has built a prototype of such a system in a URI laboratory to evaluate its effectiveness, thanks to funding from the Korea Institute for Construction Technology. By testing different asphalt mixes and various pipe systems, he hopes to demonstrate that the technology can work in a real world setting.

"One property of asphalt is that it retains heat really well," he said, "so even after the sun goes down the asphalt and the water in the pipes stays warm. My tests showed that during some circumstances, the water even gets hotter than the asphalt."

A third alternative uses a thermo-electric effect to generate a small but usable amount of electricity. When two types of semiconductors are connected to form a circuit linking a hot and a cold spot, there is a small amount of electricity generated in the circuit.

URI Chemistry Professor Sze Yang believes that thermo-electric materials could be embedded in the roadway at different depths – or some could be in sunny areas and others in shade – and the difference in temperature between the materials would generate an electric current. With many of these systems installed in parallel, enough electricity could be generated to defrost roadways or be used for other purposes. Instead of the traditional semiconductors, he proposes to use a family of organic polymeric semiconductors developed at his laboratory that can be fabricated inexpensively as plastic sheets or painted on a flexible plastic sheet.

"This is a somewhat futuristic idea, since there isn't any practical device on the market for doing this, but it has been demonstrated to work in a laboratory," said Yang. "With enough additional research, I think it can be implemented in the field."

Perhaps the most futuristic idea the URI team has considered is to completely replace asphalt roadways with roadways made of large, durable electronic blocks that contain photovoltaic cells, LED lights and sensors. The blocks can generate electricity, illuminate the roadway lanes in interchangeable configurations, and provide early warning of the need for maintenance.

According to Lee, the technology for this concept exists, but it is extremely expensive. He said that one group in Idaho made a driveway from prototypes of these blocks, and it cost about $100,000. Lee envisions that corporate parking lots may become the first users of this technology before they become practical and economical for roadway use.

"This kind of advanced technology will take time to be accepted by the transportation industries," Lee said. "But we've been using asphalt for our highways for more than 100 years, and pretty soon it will be time for a change."

(Photo: URI Department of Communications & Marketing/Michael Salerno Photograph)

University of Rhode Island

DISCOVERY COULD REVEAL SECRETS OF ANCIENT MARTIAN AND TERRESTRIAL ATMOSPHERES

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Chemists at UC San Diego have uncovered a new chemical reaction on tiny particulates in the atmosphere that could allow scientists to gain a glimpse from ancient rocks of what the atmospheres of the Earth and Mars were like hundreds of millions years ago.

Their discovery also provides a simple chemical explanation for the unusual carbonate inclusions found in a meteorite from Mars that was once thought by some scientists to be evidence of ancient Martian life.

“We never knew before how the atmosphere could be trapped in carbonate,” said Mark Thiemens, dean of UC San Diego’s Division of Physical Sciences who headed the team of scientists that detailed its discovery in this week’s early online edition of the Journal of the Proceedings of the National Academy of Sciences. “This chemical reaction, which takes place on the surface of aerosols in the atmosphere, not only provides us with an understanding of how these carbonates can form on the Earth and Mars. It gives us a new tool to better understand climate change, as our planet warms and becomes more dusty.”

Robina Shaheen, a postdoctoral researcher in Thiemens’ laboratory, discovered the chemical reaction and detailed its importance in the Earth’s atmosphere after four years of painstaking experiments in which she found a higher than expected proportion of oxygen 17 isotopes in the carbonates found on dust grains, aerosols and dirt from various parts of the world.

Martian meteorites, such as ALH84001, which was once thought to exhibit evidence of extraterrestrial life, have carbonates with similarly high oxygen 17 anomalies. Scientists have long attributed those anomalies to photochemical processes involving ozone and carbon dioxide in the thin atmosphere on Mars, which is bathed by intense ultraviolet radiation. But after finding similar anomalies on terrestrial carbonates formed in atmospheric aerosols, Shaheen surmised they might be the result of another chemical process more common to both planets.

She analyzed in painstaking detail in the laboratory and in the Earth’s atmosphere how ozone molecules interacted with oxygen-bearing mineral aerosols from dust, sea spray and other sources to form hydrogen peroxide and carbonates containing this same oxygen-isotope anomaly.

“What she found is that the tiny little layer on the outside of the grain is where this chemistry all happens,” said Thiemens. “It’s the ozone in the atmosphere mixing with water and carbon dioxide that drives a completely different kind of chemistry, one that’s not in any of the models.”

While current models of atmospheric processes assume that the mixing of large volumes of gases drives the chemistry of the Earth’s atmosphere, the UCSD chemists think their discovery may force a rethinking of this idea, particularly as the Earth’s atmosphere becomes warmer and more dusty, providing more opportunities for this sort of chemistry to take place on aerosols.

“You can do chemistry on a grain that’s a lot quicker and easier in many respects than is possible in other atmospheric processes,” said Thiemens.

Shaheen, who analyzed the carbonates in the Martian meteorite ALH84001 and found that they could have been formed on aerosols in ancient Martian atmosphere, said that NASA’s Phoenix lander recently detected carbonates associated with particulates in the dusty atmosphere of Mars. “We think it might be this same mechanism that is operating,” she added.

Besides understanding current and future atmospheric processes on the Earth and Mars, the new discovery offers the possibility of mining information about the Earth’s atmosphere, particularly its oxygen levels, from carbonates found in ancient rocks millions of years ago, far beyond the time period from which scientists can now obtain information about the ancient atmosphere from ice cores. The development of this new tool to probe ancient atmospheres could be the most significant aspect of the UCSD chemists’ discovery.

“We’ve found a new way to measure the earth’s atmosphere for time periods when we previously could not do it,” said Thiemens. “What happened to ozone and oxygen levels 65 million years ago during the Cretaceous-Tertiary period when the dinosaurs and many other forms of life were killed in a mass extinction? Who died first? Did the food chain disappear before the dinosaurs? What happened 251 million years ago during the Permian-Triassic period, the most severe extinction of life on Earth, when 85 percent of life disappeared and no one knows why? There’s no record of what happened in the atmosphere. But if you can find a record of what happened to oxygen levels, you can answer questions like that.”

(Photo: Kim McDonald, UCSD)

University of California, San Diego

BRAIN TRUMPS HAND IN STONE AGE TOOL STUDY

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Was it the evolution of the hand, or of the brain, that enabled prehistoric toolmakers to make the leap from simple flakes of rock to a sophisticated hand axe?

A new study finds that the ability to plan complex tasks was key. The research, published in the Public Library of Science journal PLoS ONE, is the first to use a cyber data glove to precisely measure the hand movements of stone tool making, and compare the results to brain activation.

“Making a hand axe appears to require higher-order cognition in a part of the brain commonly known as Broca’s area,” said Emory anthropologist Dietrich Stout, co-author of the study. It’s an area associated with hierarchical planning and language processing, he noted, further suggesting links between tool-making and language evolution.

“The leap from stone flakes to intentionally shaped hand axes has been seen as a watershed in human prehistory, providing our first evidence for the imposition of preconceived, human designs on the natural world,” he said.

Stout is an experimental archeologist who recreates prehistoric tool making to study the evolution of the human brain and mind. Subjects actually knap tools from stone as activity in their brains is recorded.

“Changes in the hand and grip were probably what made it possible to make the first stone tools,” Stout said. “Increasingly we’re finding that the earliest tools required visual and motor skills, but were conceptually simple.”

For this study, Stout used a data glove to record the exact hand postures of the research subject across a range of prehistoric technologies. He teamed with Aldo Faisal, a neuroscientist at Imperial College London, and archeologists Jan Apel of Gotland University College in Sweden and Bruce Bradley of Exeter University in Devon, England.

The researchers compared the manual dexterity for the tasks involved in making two types of tools: Oldowan flakes and Late Acheulean hand axes. Simple Oldowan stone flakes are the earliest known tools, dating back 2.6 million years. The Late Acheulean hand axe, going back 500,000 years, embodies a higher level of refinement and standardization.

“I assumed that the manual dexterity was going to be greater for making the hand axe,” Stout said. “But we found that the hand gestures were so similar that we couldn’t distinguish them.”

A previous study by Stout found differences in the brain activation associated with Oldowan versus Acheulean technologies. It was unclear, however, whether the difference was due to higher-level behavior organization or lower-level differences in manipulative complexity.

The results of the data glove study point to higher cognition. “The advances of Late Acheulean technology were not about increased dexterity. They were about the ability to plan complex action sequences,” Stout said.

A hand axe requires the maker to begin with a precise, symmetrical end in mind. A variety of tools are involved, from a large rock to rough out the basic shape of the axe, to a softer implement, such as an antler billet, to thin and sharpen the edges.

The ongoing research could lead to new understanding of the modern human brain. “For the past two million years, stone tool-making has been the most common and consistent human technology, done by virtually every society,” Stout said. "It’s an important human behavior that probably helped shape our brains.”

(Photo: Carol Clark)

EMORY University

NEW STATISTICAL MODEL MOVES HUMAN EVOLUTION BACK 3 MILLION YEARS

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Evolutionary divergence of humans from chimpanzees likely occurred some 8 million years ago rather than the 5 million year estimate widely accepted by scientists, a new statistical model suggests.

The revised estimate of when the human species parted ways from its closest primate relatives should enable scientists to better interpret the history of human evolution, said Robert D. Martin, curator of biological anthropology at the Field Museum, and a co-author of the new study appearing in the journal Systematic Biology.

Working with mathematicians, anthropologists and molecular biologists, Martin has long sought to integrate evolutionary information derived from genetic material in various species with the fossil record to get a more complete picture.

Comparing DNA among related animals can provide a clear picture of how their shared genes evolved over time, giving rise to new and separate species, Martin said. But such molecular information doesn't yield a timetable showing when the genetic divergence occurred.

Fossil evidence is the only direct source of information about long-extinct species and their evolution, Martin and his colleagues said, but large gaps in the fossil record can make such information difficult to interpret. For a generation, paleontologists have estimated human origins at 5 million to 6 million years ago.

But that estimate rests on a thin fossil record. By looking at all of today's primate species, all of the known fossil primates and using DNA evidence, computer models suggest a longer evolutionary timetable. The new analysis described in the Systematic Biology paper takes into account gaps in the fossil record and fills in those gaps statistically.

Such modeling techniques, which are widely used in science and commerce, take into account more overall information than earlier processes used to estimate evolutionary history using just a few individual fossil dates, Martin said. It can give scientists a broader perspective for interpreting data.

One example is a skull fossil discovered in Chad (central Africa) earlier in this decade. The fossil, named Sahelanthropus tchadensis and nicknamed Toumaï (which means "hope of life" in the local Goran language), raised great interest because it has many human characteristics. But consensus on how to classify the discovery has been elusive particularly because the fossil is about 7 million years old, well beyond the accepted time frame for human evolution.

Under the new estimate, Toumaï would fall within the period after the human lineage split from chimpanzees, Martin said.

The new approach to dating evolutionary history builds on earlier work by Martin and colleagues. In 2002, they published a paper in Nature that argues the last common ancestor of today's primates lived some 85 million years ago.

This implies that for 20 million years before dinosaurs became extinct, early versions of primates also lived and evolved. It challenged the accepted theory that primates and other mammals didn't really thrive on the planet until dinosaurs were gone.

After that paper was published, Martin said he expected someone would apply the new statistical techniques to the question of human evolution, but when no one did, "We decided to do it ourselves."

Field Museum

MCMASTER SCIENTISTS TURN SKIN INTO BLOOD

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In an important breakthrough, scientists at McMaster University have discovered how to make human blood from adult human skin.

The discovery, published in the prestigious science journal Nature, could mean that in the foreseeable future people needing blood for surgery, cancer treatment or treatment of other blood conditions like anemia will be able to have blood created from a patch of their own skin to provide transfusions. Clinical trials could begin as soon as 2012.

Mick Bhatia, scientific director of McMaster’s Stem Cell and Cancer Research Institute in the Michael G. DeGroote School of Medicine, and his team of researchers have also shown that the conversion is direct. Making blood from skin does not require the middle step of changing a skin stem cell into a pluripotent stem cell that could make many other types of human cells, then turning it into a blood stem cell.

“We have shown this works using human skin. We know how it works and believe we can even improve on the process,” said Bhatia. “We’ll now go on to work on developing other types of human cell types from skin, as we already have encouraging evidence.”

The discovery was replicated several times over two years using human skin from both young and old people to prove it works for any age of person.

This research was funded by the Canadian Institutes of Health Research, the Canadian Cancer Society Research Institute, the Stem Cell Network and the Ontario Ministry of Research and Innovation.

Scientists and sponsors prepared to comment on the research findings.

“CIHR is proud to invest in the excellent research that is being undertaken by Mick Bhatia’s laboratory at the Stem Cell and Cancer Research Institute at McMaster University,” said Alain Beaudet, president of the Canadian Institutes for Health Research.

“The Bhatia research effort is building on significant findings in recent years, which have shown that human skin cells can be reprogrammed into pluripotent cells that have the potential to become all cell types. "The pioneering findings published today are the first to demonstrate that human skin cells can be directly converted into blood cells, via a programming process that bypasses the pluripotent stage. Producing blood from a patient’s own skin cells, has the potential of making bone marrow transplant HLA matching and paucity of donors a thing of the past.”

Glen Murray, Ontario minister of the Ministry of Research and Innovation said: “Future generations will benefit tremendously from the world-class research that Dr. Bhatia and Ontario stem cell scientists are making here today. Ontario is the place where stem cells were discovered. We will continue to lead the world with breakthrough discoveries that improve lives and create good jobs and a strong, innovative economy.”

Christine Williams, director of research for the Canadian Cancer Society Research Institute said: "We are happy to be able to fund this important stem cell research which holds enormous promise for improved treatment of many types of cancer, including solid tumours and leukemias.”

Dr. Cynthia Dunbar, head of the Molecular Hematopoiesis Section, Hematology Branch, National Heart, Lung and Blood Institute of the U.S. National Institutes of Health, said: "Bhatia's convincing demonstration that skin cells can be directly converted to hematopoietic progenitor cells is exciting and will immediately change the paradigms regarding the best way forward for production of hematopoietic cells to be used in regenerative medicine and in the study of human blood diseases.”

“Bhatia's approach detours around the pluripotent stem cell stage and thus avoids many safety issues, increases efficiency, and also has the major benefit of producing adult-type l blood cells instead of fetal blood cells, a major advantage compared to the thus far disappointing attempts to produce blood cells from human ESCs or IPSCs."

Michael Rudnicki, director of the Stem Cell Network, said from Ottawa: “This finding will no doubt be met with excitement in the research and medical communities. It's been nearly 50 years since blood stem cells were first identified here in Canada and it's fitting that this incredible new discovery should have happened here as well," said Michael Rudnicki, director of the Stem Cell Network.

Dr. John Kelton, dean and vice-president, Faculty of Health Sciences, McMaster University, said: “I find this discovery personally gratifying for professional reasons.

“During my 30 years as a practicing blood specialist, my colleagues and I have been pleased to help care for cancer patients whose lives were saved by bone marrow transplants. For all physicians, but especially for the patients and their families, the illness became more frustrating when we were prevented from giving a bone marrow transplant because we could not find a perfect donor match in the family or the community.

“Dr. Bhatia’s discovery could permit us to help this important group of patients.”

Samuel Weiss, professor and director, Hotchkiss Brain Institute, University of Calgary, said: “This groundbreaking work from Mick Bhatia’s lab is both fascinating and important. It heralds a new age by discovering a role for ‘directed differentiation’ in the treatment of cancers and other disorders of the blood and immune system.”

McMaster University

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