Thursday, December 31, 2009


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A discovery by scientists at the University of East Anglia could contribute to the development of systems that use domestic or agricultural waste to generate clean electricity.

Published by the leading scientific journal, Proceedings of the National Academy of Sciences (PNAS), the researchers have demonstrated for the first time the mechanism by which some bacteria survive by ‘breathing rocks’.

The findings could be applied to help in the development of new microbe-based technologies such as fuel cells, or ‘bio-batteries’, powered by animal or human waste, and agents to clean up areas polluted by oil or uranium.

“This is an exciting advance in our understanding of bacterial processes in the Earth’s sub-surfaces,” said Prof David Richardson, of UEA’s School of Biological Sciences, who is leading the project.

“It will also have important biotechnological impacts. There is potential for these rock-breathing bacteria to be used to clean-up environments contaminated with toxic organic pollutants such as oil or radioactive metals such as uranium. Use of these bacteria in microbial fuel-cells powered by sewerage or cow manure is also being explored.”

The vast proportion of the world’s habitable environments is populated by micro-organisms which, unlike humans, can survive without oxygen. Some of these micro-organisms are bacteria living deep in the Earth’s subsurface and surviving by ‘breathing rocks’ – especially minerals of iron.

Iron respiration is one of the most common respiratory processes in oxygen-free habitats and therefore has wide environmental significance.

Prof Richardson said: “We discovered that the bacteria can construct tiny biological wires that extend through the cell walls and allow the organism to directly contact, and conduct electrons to, a mineral. This means that the bacteria can release electrical charge from inside the cell into the mineral, much like the earth wire on a household plug.”

(Photo: UEA)

University of East Anglia


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People who have smaller fingers have a finer sense of touch, according to new research in the Dec. 16 issue of The Journal of Neuroscience. This finding explains why women tend to have better tactile acuity than men, because women on average have smaller fingers.

“Neuroscientists have long known that some people have a better sense of touch than others, but the reasons for this difference have been mysterious,” said Daniel Goldreich, PhD, of McMaster University in Ontario, one of the study’s authors. “Our discovery reveals that one important factor in the sense of touch is finger size.”

To learn why the sexes have different finger sensitivity, the authors first measured index fingertip size in 100 university students. Each student’s tactile acuity was then tested by pressing progressively narrower parallel grooves against a stationary fingertip — the tactile equivalent of the optometrist’s eye chart. The authors found that people with smaller fingers could discern tighter grooves.

“The difference between the sexes appears to be entirely due to the relative size of the person’s fingertips,” said Ethan Lerner, MD, PhD, of Massachusetts General Hospital, who is unaffiliated with the study. “So, a man with fingertips that are smaller than a woman’s will be more sensitive to touch than the woman.”

The authors also explored why more petite fingers are more acute. Tinier digits likely have more closely spaced sensory receptors, the authors concluded. Several types of sensory receptors line the skin’s interior and each detect a specific kind of outside stimulation. Some receptors, named Merkel cells, respond to static indentations (like pressing parallel grooves), while others capture vibrations or movement.

When the skin is stimulated, activated receptors signal the central nervous system, where the brain processes the information and generates a picture of what a surface “feels” like. Much like pixels in a photograph, each skin receptor sends an aspect of the tactile image to the brain — more receptors per inch supply a clearer image.

To find out whether receptors are more densely packed in smaller fingers, the authors measured the distance between sweat pores in some of the students, because Merkel cells cluster around the bases of sweat pores. People with smaller fingers had greater sweat pore density, which means their receptors are probably more closely spaced.

“Previous studies from other laboratories suggested that individuals of the same age have about the same number of vibration receptors in their fingertips. Smaller fingers would then have more closely spaced vibration receptors,” Goldreich said. “Our results suggest that this same relationship between finger size and receptor spacing occurs for the Merkel cells.”

Whether the total number of Merkel cell clusters remains fixed in adults and how the sense of touch fluctuates in children as they age is still unknown. Goldreich and his colleagues plan to determine how tactile acuity changes as a finger grows and receptors grow farther apart.

Society for Neuroscience


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A University of Florida researcher has co-authored a study tracing the evolution of the modern opossum back to the extinction of the dinosaurs and finding evidence to support North America as the center of origin for all living marsupials.

The study, published in PLoS ONE on Dec. 16, shows that peradectids, a family of marsupials known from fossils mostly found in North America and Eurasia, are a sister group of all living opossums. The findings are based in part on high-resolution CT scans of a 55-million-year-old skull found in freshwater limestone from the Bighorn Basin of Wyoming.

“The extinction of the dinosaurs was a pivotal moment in the evolution of mammals,” said Jonathan Bloch, study co-author and associate curator of vertebrate paleontology at UF’s Florida Museum of Natural History. “We’re tracing the beginnings of a major group of mammals that began in North America.”

Opossum-like peradectids first appeared on the continent about 65 million years ago, at the time of the Cretaceous–Paleogene extinction event, which killed the dinosaurs.

“North America is a critical area for understanding marsupial and opossum origins because of its extensive and varied fossil record,” said lead author Inés Horovitz, an assistant adjunct professor at the University of California, Los Angeles. “Unfortunately, most of its species are known only from teeth.”

The study also analyzes two 30-million-year-old skeletons of Herpetotheriidae, the sister group of all living marsupials.

Based on fossil evidence from the skull and two skeletons, the study’s authors concluded the evolutionary split between the ancestor of opossums and the ancestor of all other living marsupials occurred at least 65 million years ago, Horovitz said.

Marsupials migrated between North and South America until the two continents separated after the end of the Cretaceous period. Marsupials in South America diversified and also migrated into Antarctica and Australia, which were still connected at that time, Bloch said.

North American marsupials went extinct during the early Miocene, about 20 million years ago. But after the Isthmus of Panama emerged to reconnect North and South America 3 million years ago, two marsupials made it back to North America: the Virginia opossum (Didelphis virginiana), a common resident in the Southeast today, and the southern opossum (Didelphis marsupialis), which lives as far north as Mexico.

The study describes a new peradectid species, Mimoperadectes houdei, based on a relatively complete fossil skull. The high-resolution CT scan of the skull gave researchers a large amount of information about the animal’s internal anatomy. The ear, in particular, provides researchers with information on skull anatomy and clues about the animal’s locomotion, Bloch said.

The scan showed the new species shared enough common traits with living opossums to indicate an evolutionary relationship. Some predictions about that relationship could have been made from fossil teeth, Bloch said, “but this provides a much stronger foundation for that conclusion.”

Most North American marsupials living in the Paleocene and early Eocene (56 million to 48 million years ago) were small-bodied animals. But M. houdei approached the body size of some opossums living today.

“You would probably recognize it as an opossum, but it wouldn’t look quite right,” Bloch said.

The skull came from the same limestone deposits in Wyoming as the primitive primate skull Bloch and other researchers used to map an early primate brain with CT scans in a study published earlier this year.

“In parts of North America today, opossums are one of the most commonly observed mammals around,” Bloch said. “This fossil skull shows its roots going back to the extinction of the dinosaurs. This is literally the fossil that shows us the ancestry of that animal.”

The study’s examination of the two skeletons gives a first glimpse into the form and structure of primitive marsupials and shows that they were more terrestrial than modern opossums. The skeletons came from the late Oligocene and were found in the White River Badlands of Wyoming.

(Photo: Jeff Gage)

University of Florida


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A three dimensional solar cell design that uses micron-scale “towers” to capture nearly three times as much light as flat solar cells made from the same materials has been awarded broad patent protection in both China and Australia. Modeling suggests that the 3-D cell could boost power production by as much as 300 percent compared to conventional solar cells.

A three dimensional solar cell design that uses micron-scale "towers" to capture nearly three times as much light as flat solar cells made from the same materials has been awarded broad patent protection in both China and Australia. Modeling suggests that the 3-D cell could boost power production by as much as 300 percent compared to conventional solar cells.

Because it can capture more power from a given area, the 3-D design could be useful for powering satellites, cell phones, military equipment and other applications that have a limited surface area. Developed at the Georgia Tech Research Institute (GTRI), the "three dimensional multi-junction photovoltaic device" uses its 3-D surface structure to increase the likelihood that every photon striking it will produce energy.

"One problem with conventional flat solar cells is that the sunlight hits a flat surface and can bounce off, so the light only has one chance to be absorbed and turned into electricity," explained John Bacon, president of IP2Biz®, an Atlanta company that has licensed the technology from GTRI. "In the GTRI 3-D solar cell, we build a nanometer-scale version of Manhattan, with streets and avenues of tiny light-capturing structures similar to tall buildings. The sunlight bounces from building to building and produces more electricity."

The arrays of towers on the 3-D solar cell can increase the surface area by several thousand percent, depending on the size and density of the structures.

"Conventional cells have to be very large to make adequate amounts of electricity, and that limits their applications," Bacon explained. "The large surface area of our 3-D cell means that applications from satellites to cell phones will be more practical since we can pack so much light gathering power into a small footprint."

The three dimensional structure also means that the cells don't have to be aimed directly at the sun to capture sunlight efficiently, Bacon added. Conventional solar cells work best when the sunlight hits them at a narrow range of angles, but the new 3-D system remains efficient regardless of the angle at which the light hits.

The tower structures on the GTRI solar cells are about 100 microns tall, 40 microns by 40 microns square, 50 microns apart — and grown from arrays containing millions of vertically aligned carbon nanotubes. The nanotubes primarily serve as the structure on which current-generating photovoltaic p/n coatings are applied.

"The carbon nanotubes are like the framing inside of buildings, and the photovoltaic materials are like the outer skin of the buildings," said Tom Smith, president of 3-D Solar LLC, a company formed to commercialize the cells. "Within the three-dimensional structures, multiple materials could be used to create the physical framing. Carbon nanotubes were used in the original solar cells, but they are not required for the technology to work."

The 3-D solar cells were developed in the laboratory of Jud Ready, a GTRI senior research engineer. Tests comparing the 3-D solar cells produced in Ready's lab with traditional planar cells produced from the same materials showed an increase in power generation, Smith said.

The researchers chose to make their prototype cells from cadmium materials because they were familiar with them from other research. However, a broad range of photovoltaic materials could also be used, and selecting the best material for specific applications will be the goal of future research.

Fabrication of the cells begins with a silicon wafer, which also serves as the solar cell's bottom junction. The researchers first coat the wafer with a thin layer of iron using a photolithography process that can create a wide variety of patterns. The patterned wafer is then placed into a furnace heated to approximately 700 degrees Celsius.

Hydrocarbon gases are then flowed into the furnace, where the carbon and hydrogen separate. In a process known as chemical vapor deposition, the carbon grows arrays of multi-walled carbon nanotubes atop the patterns created by the iron particles.

Once the carbon nanotube towers have been grown, the researchers use a process known as molecular beam epitaxy to coat the nanotube arrays with cadmium telluride (CdTe) and cadmium sulfide (CdS), which serve as the p-type and n-type photovoltaic layers. Atop that, a thin coating of indium tin oxide, a clear conducting material, is added to serve as the cell's top electrode.


The 3-D solar cells were described in the March 2007 issue of the journal JOM, published by the Minerals, Metals and Materials Society, and in the Journal of Applied Physics in 2008. The research leading to their development was supported by the Air Force Office of Scientific Research and the Air Force Research Laboratory.

Beyond the patents in China and Australia, IP2Biz has applied for protection in the United States, Canada, Europe, Korea and India, Smith noted. The patents granted so far apply to any photovoltaic application in which three dimensional structures are used to capture light bouncing off them, he added.

"The 3-D photovoltaic cell could be of great value in satellite, cell phone and defense applications given its order of magnitude reduction in footprint, coupled with the potential for increased power production compared to planar cells," Smith added. "We are very pleased with the level of interest in licensing or acquiring this innovation as means of addressing the world's growing need for energy."

(Photo: GIT)

Georgia Institute of Technology


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The gases which formed the Earth's atmosphere - and probably its oceans - did not come from inside the Earth but from outer space, according to a study by University of Manchester and University of Houston scientists.

The report published in the prestigious international journal 'Science' means that textbook images of ancient Earth with huge volcanoes spewing gas into the atmosphere will have to be rethought.

According to the team, the age-old view that volcanoes were the source of the Earth's earliest atmosphere must be put to rest.

Using world-leading analytical techniques, the team of Dr Greg Holland, Dr Martin Cassidy and Professor Chris Ballentine tested volcanic gases to uncover the new evidence.

The research was funded by Natural Environment Research Council (NERC).

"We found a clear meteorite signature in volcanic gases," said Dr Greg Holland the project's lead scientist.




The techniques enabled the team to measure tiny quantities of the unreactive volcanic trace gases Krypton and Xenon, which revealed an isotopic 'fingerprint' matching that of meteorites which is different from that of 'solar' gases.



"We will now have to redraw this picture."

University of Manchester


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(Photo: McGill U.)

McGill University


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(Photo: LBNL)


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"When a lot of gas is flowing, the dense disk reaches nearly to the black hole," said John Tomsick at the University of California, Berkeley. "But when the flow is reduced, theory predicts that gas close to the black hole heats up, resulting in evaporation of the innermost part of the disk." Never before have astronomers shown an unambiguous signature of this transformation.

To look for this effect, Tomsick and an international group of astronomers targeted GX 339-4, a low-mass X-ray binary located about 26,000 light-years away in the constellation Ara. There, every 1.7 days, an evolved star no more massive than the sun orbits a black hole estimated at 10 solar masses. With four major outbursts in the past seven years, GX 339-4 is among the most dynamic binaries in the sky.

In September 2008, nineteen months after the system's most recent outburst, the team observed GX 339-4 using the orbiting Suzaku X-ray observatory, which is operated jointly by the Japan Aerospace Exploration Agency and NASA. At the same time, the team also observed the system with NASA's Rossi X-ray Timing Explorer satellite.

Instruments on both satellites indicated that the system was faint but in an active state, when black holes are known to produce steady jets. Radio data from the Australia Telescope Compact Array confirmed that GX 339-4's jets were indeed powered up when the satellites observed.

Despite the system's faintness, Suzaku was able to measure a critical X-ray spectral line produced by the fluorescence of iron atoms. "Suzaku's sensitivity to iron emission lines and its ability to measure the shapes of those lines let us see a change in the accretion disk that only happens at low luminosities," said team member Kazutaka Yamaoka at Japan's Aoyama Gakuin University.

X-ray photons emitted from disk regions closest to the black hole naturally experience stronger gravitational effects. The X-rays lose energy and produce a characteristic signal. At its brightest, GX 339-4's X-rays can be traced to within about 20 miles of the black hole. But the Suzaku observations indicate that, at low brightness, the inner edge of the accretion disk retreats as much as 600 miles.

"We see emission only from the densest gas, where lots of iron atoms are producing X-rays, but that emission stops close to the black hole -- the dense disk is gone," explained Philip Kaaret at the University of Iowa. "What's really happening is that, at low accretion rates, the dense inner disk thins into a tenuous but even hotter gas, rather like water turning to steam."

The dense inner disk has a temperature of about 20 million degrees Fahrenheit, but the thin evaporated disk may be more than a thousand times hotter.

The study, which appears in the Dec. 10 issue of The Astrophysical Journal Letters, confirms the presence of low-density accretion flow in these systems. It also shows that GX 339-4 can produce jets even when the densest part of the disk is far from the black hole.

"This doesn't tell us how jets form, but it does tell us that jets can be launched even when the high-density accretion flow is far from the black hole," Tomsick said. "This means that the low-density accretion flow is the most essential ingredient for the formation of a steady jet in a black hole system."

(Photo: ESO/L. Calçada)



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Now, new studies have revealed that the effect of meltwater on acceleration and ice loss -- through fast-moving outlet glaciers that connect the inland ice sheet to the ocean -- is much more complex. This is because a kind of plumbing system evolves over time at the base of the ice, expanding and shrinking with the volume of meltwater.




“That doesn’t mean that meltwater is not important,” he continued. “It plays a role along these glacial fronts -- it’s just a very complex role, one that makes it hard for us to predict the future.”

In a press conference at the American Geophysical Union (AGU) meeting in San Francisco on Wednesday, December 16, 2009, Howat joined colleagues from the University of Colorado-Boulder/NOAA Cooperative Institute for Research in Environmental Sciences (CIRES) and NASA’s Jet Propulsion Laboratory (JPL) to discuss three related projects -- all of which aim to uncover how this meltwater interacts with ice and the ocean.

Their work has implications for ice loss elsewhere in the world -- including Antarctica -- and could ultimately lead to better estimates of future sea level rise due to climate change.




“My tenet is pushing the miniaturization of technology, so that small autonomous platforms -- in the sea, on the surface, or in the air -- can reliably gather scientific information in remote regions,” Adler said.



Howat has found that glacial meltwater at the base of the ice sheet has little influence on ice loss along the coast -- most of the time.




But outlet glaciers along the coast are already flowing out to sea at rates as high as 10 kilometers per year -- a rate too high to be caused by the meltwater.


His team looked for correlations between times of peak meltwater in the summer and times of sudden acceleration in outlet glaciers, and found none. “Some of these outlet glaciers accelerated in the wintertime, and some of accelerated over long periods of time. The changes didn’t correlate with any time that you would expect there to be more melt,” he added.




At one point, he and his colleagues witnessed the latter effect first hand. They detected a sudden decrease of sub-glacial meltwater inland, only to see a giant plume of dirty water burst out from under the ice at the nearby water’s edge.




(Photo: Alberto Behar, Jet Propulsion Laboratory)

Ohio State University

Wednesday, December 30, 2009


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(Photo: UCAR/Carlyle Calvin)

Pacific Northwest National Laboratory


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(Photo: LIGO Scientific Collaboration (LSC) / NASA)

Royal Astronomical Society


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(Photo: Cyrus Read, AVO/USGS)

University of California, Santa Cruz

Tuesday, December 29, 2009


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Scientists once thought that life could originate only within a solar system's "habitable zone," where a planet would be neither too hot nor too cold for liquid water to exist on its surface. But according to planetary scientist Francis Nimmo, evidence from recent NASA missions suggests that conditions necessary for life may exist on the icy satellites of Saturn and Jupiter.

"If these moons are habitable, it changes the whole idea of the habitable zone," said Nimmo, a professor of Earth and planetary sciences at UC Santa Cruz. "It changes our thinking about how and where we might find life outside of the solar system."



"Liquid water is the one requirement for life that everyone can agree on," Nimmo said.

The icy surfaces may insulate deep oceans, shift and fracture like tectonic plates, and mediate the flow of material and energy between the moons and space.

Several lines of evidence support the presence of subsurface oceans on Europa and Enceladus, Nimmo said. In 2000, for example, NASA's Galileo spacecraft measured an unusual magnetic field around Europa that was attributed to the presence of an ocean beneath the moon's surface. On Enceladus, the Cassini spacecraft discovered geysers shooting ice crystals a hundred miles above the surface, which also suggests at least pockets of subsurface water, Nimmo said (see earlier story).

Liquid water isn't easy to find in the cold expanses beyond Earth's orbit. But according to Nimmo, tidal forces could keep subsurface oceans from freezing up. Europa and Enceladus both have eccentric orbits that bring them alternately close to and then far away from their respective planets. These elongated orbits create ebbs and flows of gravitational energy between the planets and their satellites.

"A moon like Enceladus is getting squeezed and stretched and squeezed and stretched," Nimmo said.

The extent to which this squeezing and stretching transforms into heat remains unclear, he said. Tidal forces likely shift plates in the lunar cores, creating friction and geothermal energy. This energy may also rub surface ice against itself at the sites of deep ice fissures, creating heat and melting, according to Nimmo. Enceladus's geysers appear to originate from these shifting faults, and the thin lines running along Europa's surface suggest geologically active plates, he said.

A frozen outer layer may be crucial to maintaining oceans that could harbor life on these moons. The icy surfaces may shield the oceans from the frigidity of space and from radiation harmful to living organisms.

"If you want to have life, you want the ocean to last a long time," Nimmo said. "The ice above acts like an insulating blanket."



Nimmo cautioned that being habitable is no guarantee that a planetary body is actually inhabited. It is unlikely that we will find life elsewhere in our solar system, despite all the time and resources devoted to the search, he said. But such a discovery would certainly be worth the effort.

"I think pretty much everyone can agree that finding life anywhere else in the solar system would be the scientific discovery of the millennium," Nimmo said.

(Photo: NASA/JPL/Space Science Institute)

University of California


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A new study of images from NASA's Chandra X-ray Observatory on supernova remnants - the debris from exploded stars - shows that the symmetry of the remnants, or lack thereof, reveals how the star exploded. This is an important discovery because it shows that the remnants retain information about how the star exploded even though hundreds or thousands of years have passed.


Astronomers sort supernovas into several categories, or "types", based on properties observed days after the explosion and which reflect very different physical mechanisms that cause stars to explode. But, since observed remnants of supernovas are leftover from explosions that occurred long ago, other methods are needed to accurately classify the original supernovas.


For each of these remnants there is independent information about the type of supernova involved, based not on the shape of the remnant but, for example, on the elements observed in it. The researchers found that one type of supernova explosion - the so-called Type Ia - left behind relatively symmetric, circular remnants. This type of supernova is thought to be caused by a thermonuclear explosion of a white dwarf, and is often used by astronomers as "standard candles" for measuring cosmic distances.


"If we can link supernova remnants with the type of explosion", said co-author Enrico Ramirez-Ruiz, also of University of California, Santa Cruz, "then we can use that information in theoretical models to really help us nail down the details of how the supernovas went off."





(Photo: NASA/CXC/UCSC/L. Lopez et al.)

Harvard-Smithsonian Center for Astrophysics


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Stem cells that could one day provide therapeutic options for muscle and bone disorders can be easily harvested from the tissue of the umbilical cord, just as the blood that goes through it provides precursor cells to treat some blood disorders, said University of Pittsburgh School of Medicine researchers in the online version of the Journal of Biomedicine and Biotechnology.

Umbilical cord tissue cells can be expanded to greater number, are remarkably stable and might not trigger strong immune responses, said senior investigator Bridget M. Deasy, Ph.D., assistant professor in the Department of Orthopaedic Surgery, Pitt School of Medicine. The cells are obtained from the gelatinous material in the cord known as Wharton's jelly and from blood vessel walls.

"Our experiments indicate also that at least 21 million stem cells, and possibly as many as 500 million, could be banked from a single umbilical cord after the birth of a baby," she noted. "So, the cord could become an accessible source of a multitude of stem cells that overcomes many of the restrictions, such as limited quantity as well as donor age and donor sex issues, that come with other adult stem cell populations."

Dr. Deasy and her team analyzed sections of two-foot-long human umbilical cords that were donated for research, looking for cells in Wharton's jelly and blood vessel walls that displayed the characteristic protein markers found in stem cells derived from other sources. The researchers then sought to find the best way to isolate the stem cells from the cords, and tested them in the lab to confirm their ability to produce specialized cells, such as bone and cartilage, while retaining their invaluable ability to renew themselves.

To build on these findings, the team will test the umbilical cord stem cells in animal models of cartilage and bone repair, as well as muscle regeneration.

University of Pittsburgh


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The DNA of a 1st century shrouded man found in a tomb on the edge of the Old City of Jerusalem has revealed the earliest proven case of leprosy. Details of the research were published December 16 in the PloS ONE Journal.









Furthermore, the new research has shown that molecular pathology clearly adds a new dimension to the archaeological exploration of disease in ancient times and provides us with a better understanding of the evolution, geographic distribution and epidemiology of disease and social health in antiquity.


(Photo: Prof. Shimon Gibson)

The Hebrew University of Jerusalem


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NIST scientists developed models of how teeth fracture while chewing different foods. By fracturing teeth in the laboratory, they verified fundamental fracture mechanics models incorporating tooth shape and structure. These efforts revealed the effects of food stiffness and how various foods likely would damage ape teeth. "The research at NIST supports our theories and several related ones," Constantino says. "It's likely that fallback foods have influenced jaw and skull shape as well."

Constantino adds that the findings suggest mankind must protect not only forest areas where commonly eaten fruits grow, but also the places where apes' fallback resources appear. While identifying precisely what these resources are is a job for ecologists, he says, the new research shows just how important and influential these foods are in primate ecology.

"Among orangutans, for example, timber companies are harvesting the sources of their fallbacks," Constantino says. "These apes have evolved the right tools to survive on fallback foods, but they need to be able to find these foods in the first place."

National Institute of Standards and Technology


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Pamela Pallett and Stephen Link of UC San Diego and Kang Lee of the University of Toronto tested the existence of an ideal facial feature arrangement. They successfully identified the optimal relation between the eyes, the mouth and the edge of the face for individual beauty.



Interestingly, these proportions correspond with those of an average face.

"People have tried and failed to find these ratios since antiquity. The ancient Greeks found what they believed was a 'golden ratio' – also known as 'phi' or the 'divine proportion' – and used it in their architecture and art. Some even suggest that Leonardo Da Vinci used the golden ratio when painting his 'Mona Lisa.' But there was never any proof that the golden ratio was special. As it turns out, it isn't. Instead of phi, we showed that average distances between the eyes, mouth and face contour form the true golden ratios," said Pallett, a post-doctoral fellow in psychology at UC San Diego and also an alumna of the department.

"We already know that different facial features make a female face attractive – large eyes, for example, or full lips," said Lee, a professor at University of Toronto and the director of the Institute of Child Study at the Ontario Institute for Studies in Education. "Our study conclusively proves that the structure of faces – the relation between our face contour and the eyes, mouth and nose – also contributes to our perception of facial attractiveness. Our finding also explains why sometimes an attractive person looks unattractive or vice versa after a haircut, because hairdos change the ratios."

The researchers suggest that the perception of facial attractiveness is a result of a cognitive averaging process by which people take in all the faces they see and average them to get an ideal width ratio and an ideal length ratio. They also posit that "averageness" (like symmetry) is a proxy for health, and that we may be predisposed by biology and evolution to find average faces attractive.

University of Toronto


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(Photo: Beth McConnell)

Stanford University


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Melott and fellow researchers examined data from ice cores extracted in Greenland to compare atmospheric chemistry during the Tunguska and Younger Dryas events. In both instances, Melott's group found evidence that the Haber process — whereby a nitrogen fixation reaction produces ammonia — may have occurred on a large scale.





"There's a whole program to watch for near-Earth asteroids as they go around the sun repeatedly, and some of them have close brushes with the Earth," said Melott. "But comets are a whole different ball game. They don't do that circular thing. They come straight in from far, far out — and you don't see them coming until they push out a tail only a few years before they would enter the inner solar system. So we could be hit by a comet and only have a few years' warning — possibly not enough time to do anything about it."

Kansas University


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To identify and record the genetic diversity of these wild apples, Gayle Volk and Christopher Richards at the National Center for Genetic Resources Preservation, U.S. Department of Agriculture (USDA), performed genetic diversity analyses on trees grown from Malus orientalis seeds collected in Georgia, Armenia, Russia, and Turkey. The trees are located at the USDA-ARS Plant Genetic Resources Unit (PGRU) in Geneva, New York. Seedling trees were evaluated for resistance to critical diseases such as fire blight, apple scab, and cedar apple rust. The full report was published in a recent issue of the Journal of the American Society for Horticultural Science.

Seeds from wild Malus orientalis trees were collected from 1998-2004 during explorations to Armenia, Georgia, Turkey, and Russia. Seedling orchards with between eight and 171 "individuals" from each collection location were established, and disease resistance data were collected for 776 trees. The genetic diversity of the 280 individuals from Armenia and Georgia was compared with results obtained for individuals from Russia and Turkey. A total of 106 alleles were identified in the trees from Georgia and Armenia. The average gene diversity ranged from 0.47 to 0.85 per locus. The researchers concluded that "the genetic differentiation among sampling locations was greater than that found between the two countries."

Six individuals from Armenia exhibited resistance to fire blight, apple scab, and cedar apple rust. According to Volk; "The data suggest wild populations of M. orientalis from regions around the Black Sea are genetically distinguishable and show high levels of diversity."

A core set of 27 trees that captures 93% of the alleles in the PGRU M. orientalis collection will be maintained in the field at the PGRU in Geneva, New York.

(Photo: Phil Forsline)

American Society for Horticultural Science

Monday, December 28, 2009


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Since melt water from Tibetan glaciers replenishes many of Asia's major rivers—including the Indus, Ganges, Yellow, and Brahmaputra—such losses could have a profound impact on the billion people who rely on the rivers for fresh water. While rain and snow would still help replenish Asian rivers in the absence of glaciers, the change could hamper efforts to manage seasonal water resources by altering when fresh water supplies are available in areas already prone to water shortages.







(Photo: NASA/Sally Bensusen)


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Ordinary stars are powered by the fusion of light nuclei into heavier ones – such as hydrogen into helium in the center of our sun. Electroweak stars, they theorize, would be powered by the total conversion of quarks – the particles that make up the proton and neutron building blocks of those nuclei – into much lighter particles called leptons. These leptons include electrons, but especially elusive – and nearly massless – neutrinos.

"This is a process predicted by the well-tested Standard Model of particle physics," Starkman said. At ordinary temperatures it is so incredibly rare that it probably hasn't happened within the visible universe anytime in the last 10 billion years, except perhaps in the core of these electroweak stars and in the laboratories of some advanced alien civilizations, he said.

In their dying days, stars smaller than 2.1 times our sun's mass die and collapse into neutron stars – objects dense enough that the neutrons and protons push against each other. More massive stars are thought to head toward collapse into a black hole. But at the extreme temperatures and densities that might be reached when a star begins to collapse into a black hole, electroweak conversion of quarks into leptons should proceed at a rapid rate, the scientists say.

The energy generated could halt the collapse, much as the energy generated by nuclear fusion prevents ordinary stars like the Sun from collapsing. In other words, an electroweak star is the possible next step before total collapse into a black hole. If the electroweak burning is efficient, it could consume enough mass to prevent what's left from ever becoming a black hole.

Most of the energy eventually emitted from electroweak stars is in the form of neutrinos, which are hard to detect. A small fraction comes out as light and this is where the electroweak star's signature will likely be found, Starkman, said. But, "To understand that small fraction, we have to understand the star better than we do."

And until they do, it's hard to know how we can tell electroweak stars from other stars.

There's time, however, to learn. The theorists have calculated that this phase of a star's life can last more than 10 million years – a long time for us, though just an instant in the life of a star.

Case Western Reserve University



