Wednesday, June 2, 2010

FERMILAB SCIENTISTS FIND EVIDENCE FOR SIGNIFICANT MATTER-ANTIMATTER ASYMMETRY

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Scientists of the DZero collaboration at the Department of Energy’s Fermi National Accelerator Laboratory announced Friday, May 14, that they have found evidence for significant violation of matter-antimatter symmetry in the behavior of particles containing bottom quarks beyond what is expected in the current theory, the Standard Model of particle physics. The new result, submitted for publication in Physical Review D by the DZero collaboration, an international team of 500 physicists, indicates a one percent difference between the production of pairs of muons and pairs of antimuons in the decay of B mesons produced in high-energy collisions at Fermilab’s Tevatron particle collider.

The dominance of matter that we observe in the universe is possible only if there are differences in the behavior of particles and antiparticles. Although physicists have observed such differences (called “CP violation") in particle behavior for decades, these known differences are much too small to explain the observed dominance of matter over antimatter in the universe and are fully consistent with the Standard Model. If confirmed by further observations and analysis, the effect seen by DZero physicists could represent another step towards understanding the observed matter dominance by pointing to new physics phenomena beyond what we know today.

Using unique features of their precision detector and newly developed analysis methods, the DZero scientists have shown that the probability that this measurement is consistent with any known effect is below 0.1 percent (3.2 standard deviations).

"This exciting new result provides evidence of deviations from the present theory in the decays of B mesons, in agreement with earlier hints," said Dmitri Denisov, co-spokesperson of the DZero experiment, one of two collider experiments at the Tevatron collider. Last year, physicists at both Tevatron experiments, DZero and CDF, observed such hints in studying particles made of a bottom quark and a strange quark.

When matter and anti-matter particles collide in high-energy collisions, they turn into energy and produce new particles and antiparticles. At the Fermilab proton-antiproton collider, scientists observe hundreds of millions every day. Similar processes occurring at the beginning of the universe should have left us with a universe with equal amounts of matter and anti-matter. But the world around is made of matter only and antiparticles can only be produced at colliders, in nuclear reactions or cosmic rays. “What happened to the antimatter?” is one of the central questions of 21st–century particle physics.

To obtain the new result, the DZero physicists performed the data analysis "blind," to avoid any bias based on what they observe. Only after a long period of verification of the analysis tools, did the DZero physicists look at the full data set. Experimenters reversed the polarity of their detector’s magnetic field during data collection to cancel instrumental effects.

“Many of us felt goose bumps when we saw the result,” said Stefan Soldner-Rembold, co-spokesperson of DZero. “We knew we were seeing something beyond what we have seen before and beyond what current theories can explain.”

The precision of the DZero measurements is still limited by the number of collisions recorded so far by the experiment. Both CDF and DZero therefore continue to collect data and refine analyses to address this and many other fundamental questions.

“The Tevatron collider is operating extremely well, providing Fermilab scientists with unprecedented levels of data from high energy collisions to probe nature’s deepest secrets. This interesting result underlines the importance and scientific potential of the Tevatron program,” said Dennis Kovar, Associate Director for High Energy Physics in DOE’s Office of Science.

The DZero result is based on data collected over the last eight years by the DZero experiment: over 6 inverse femtobarns in total integrated luminosity, corresponding to hundreds of trillions of collisions between protons and antiprotons in the Tevatron collider.

“Tevatron collider experiments study high energy collisions in every detail, from searches for the Higgs boson, to precision measurement of particle properties, to searches for new and yet unknown laws of nature. I am delighted to see yet another exciting result from the Tevatron,” said Fermilab Director Pier Oddone.

(Photo: DZero collaboration)

Fermi National Accelerator Laboratory

NEW FOSSIL MATERIAL REDEFINES AZENDOHSAURUS AS BIZARRE EARLY REPTILE

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Following careful study of a prehistoric skull of a new species unearthed in Madagascar, Azendohsaurus madagaskarensis, it turns out Azendohsaurus is not an early dinosaur as long assumed, but rather something even more remarkable.

After scientists pieced together an entire skull of this 230-million-year-old azendohsaur –– a group known previously from just teeth and jaws –– these animals have now been aligned with a very early branch of the reptile evolutionary tree.

In a study published in the journal Palaeontology, UC Santa Barbara Earth Science professor Andre Wyss and other scientists concluded that many aspects of Azendohsaurus are far more primitive than previously assumed, which means that its plant-eating adaptations –– similar to those found in some early dinosaurs –– were developed independently.

"Even though this extraordinary ancient reptile, a member of the ‘Archosauromorpha' (a group of reptiles that includes birds and crocodilians, but not lizards, snakes, or turtles), looks similar to some plant-eating dinosaurs in some features of the skull and dentition, it is in fact only distantly related to dinosaurs," said John J. Flynn, curator in the Division of Paleontology at the American Museum of Natural History, and lead author of the study. "With more complete materials, we reassessed features like the down-turned jaw and leaf-shaped teeth found in A. madagaskarensis as convergent with some herbivorous dinosaurs."

The original specimens of the genus Azendohsaurus were a fragmentary set of teeth and jaws found in 1972 near a village in Morocco's Atlas Mountains. A related species was found in the late 1990's in Madagascar, the world's fourth-largest island, off the east coast of Africa. The current study is based on more recently discovered Malagasay fossils. The fossils, including multiple individuals that likely perished together, were uncovered by a team of U.S. and Malagasay paleontologists from red sediment in an inconspicuous gully.

"It turns out that there are simply remarkable fossils there (in Madagascar)," Wyss said. "We found this site in the southwest part of the country. It was quite rich with fossils. We recovered a lot of really amazing animals."

This species was initially identified as an early dinosaur in a study published in the journal Science more than a decade ago, but the more recently unearthed fossils have provided the first substantial glimpse of what this animal looked like –– and proof that A. madagaskarensis was not a dinosaur.

A. madagaskarensis lived during the period of time that dinosaurs, crocodile relatives, mammals, pterosaurs, turtles, frogs, and lizards were getting their start, and when all of the continents were connected to the supercontinent Pangaea. A. madagaskarensis was 2-4 meters (6-13 feet) long and weighed between 44 and 110 pounds. It was an efficient, vegetation-slicing herbivore –– a veritable, legged "weed whacker" –– with teeth covering not only its jaws but also the roof of its mouth.

Even though early archosaurs were commonly thought to be primarily carnivorous, A. madagaskarensis shows that traits associated with herbivores were much more widespread across archosaur reptiles.

"Now there are many more cases of herbivorous archosaurs," Wyss said. "We are rethinking the evolution of diet and feeding strategies, as well as the broader evolution of the group."

"This is the way science works," Flynn said. "As we found and analyzed more material, it made us realize that this was a much more primitive animal and the dinosaur-like features were really the product of convergent evolution."

Wyss added: "In many ways, Azendohsaurus ends up being a much more fantastic animal than if it simply represented a generic early dinosaur. It's been a wonderful experience finding these animals."

(Photo: George Foulsham, UCSB Public Affairs)

UC Santa Barbara

EARTH'S MANTLE FLOWS FAST

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The Earth's mantle flows far more rapidly around a sinking tectonic plate than previously thought, according to new computer modeling by UC Davis geologists. The findings could change the way that we think about plate tectonics and the amount of energy available for earthquakes. The results were published May 20 in the journal Nature.

"Our model suggests that some parts of the mantle are moving at screaming speeds compared to what we can observe directly at the Earth's surface," said Magali Billen, associate professor of geology at UC Davis and co-author of the paper. "There is much more mixing and more rapid transport of heat in these regions of the Earth than we suspected."

Billen and graduate student Margarete Jadamec, now a postdoctoral researcher at Monash University in Australia, studied the Alaskan subduction zone, where the Pacific plate is diving beneath Alaska and pushing up Mt. McKinley.

To do so, they built the most detailed computer model to date of the plate and the surrounding mantle. The model revealed that rather than moving at roughly the same speed as the plate, the mantle was flowing much faster.

"We expected it to flow faster, but the surprise was that it is flowing 20 to 30 times faster," Billen said.

For geophysicists, that's as jarring as looking out your car window and estimating your speed at 10 miles an hour based on the passing scenery, then looking at the speedometer to find that you are doing 200 miles an hour, Billen said.

The Earth's surface is made of rocky plates floating on the mantle. Although solid, the mantle can flow under enormous pressure and temperature as individual grains are stretched. Where the surface plates meet, they may rub alongside each other or one may dive under the other and sink into the mantle, creating a subduction zone. As the plate sinks, it drags the mantle material along with it, Billen said.

Billen and Jadamec's model assumes that the viscosity of the mantle is not directly proportional to the stress on it. As stress increases, the mantle gets much less viscous and flows more easily.

The model raises questions about how movements in the mantle are connected to the movements of plates at the surface. One prediction is that there is more energy available in subduction zones to cause earthquakes than previously thought.

The model includes 100 million data points and takes 48 hours to run on a supercomputer with 400 processors. Billen and Jadamec ran their model on the Teragrid supercomputer at the Texas Advanced Computing Center, which is partly supported by the National Science Foundation.

(Photo: Magali Billen)

UC Davis

WATER WAS PRESENT DURING BIRTH OF EARTH

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New research by The University of Manchester and the Carnegie Institution of Washington is to make scientists rethink their understanding of how Earth formed.

The team have found that volatile elements - most likely to include water - were present during the violent process of the Earth's birth between 30 and 100 million years after the solar system was created - a minute period in geological terms

The findings mean that comets and asteroids were unlikely to have brought the bulk of volatile elements to Earth - as commonly thought.

Lead scientist Dr Maria Schonbachler from The University of Manchester, publishes her research in Science, the prestigious weekly American journal today.

The scientist based at the University's School of Earth, Atmospheric and Environmental Sciences hit upon the findings by using high precision equipment to measure abundances of Silver isotopes contained in rocks.

The readings show that the moderately volatile element Silver was present in relatively large amounts towards the final stages of the Earth's formation.

The radioactive isotope Palladium 107 decays to Silver 107, which was present during the formation of the solar system.

The decay of Palladium 107 creates anomalies in the abundances of Silver isotopes, which can be measured and used for dating, even though Palladium 107 is no longer present on Earth.

The findings give a new boost to a 30 year old model, which suggests that volatile elements were already present in the final stages of the Earth's birth.

How much of these elements were lost during impacts like the one that formed the moon, however, is still not well known.

Dr Schonbachler said: "The sensitive equipment we use works in much the same way as when you might carbon date a rock or artifact - but on a scale which enables us to go back billions of years.

"And those measurements allow us to detect a transition from volatile-depleted to volatile-enriched building blocks as the accumulation of Earth proceeded.

"Because we know what happened to the moderately volatile Silver, it's very likely that the same thing happened to the highly volatile water.

"Though I accept that about 85 per cent of the Earth's mass was built without volatile elements the rest of it was- and that's quite an important difference in our understanding of the Earth's geological history."

"We don't now need any theories about how water came to Earth - such as comets and asteroids - it was most likely here almost from the beginning. And water is, what made Earth habitable for life."

(Photo: U. Manchester)

University of Manchester

EARLY BIRD WAS NO HIGH FLIER

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The evolution of flight took longer than previously thought with the ancestors of modern birds “rubbish” at flying, if they flew at all, according to a Manchester scientist.

Archaeopteryx, the theropod dinosaur believed to be the earliest bird, was discovered 150 years ago but debates about how flight evolved still persist. The two theories are that flight evolved in running bipeds through a series of short jumps or that Archaeopteryx leapt from tree to tree using its wings as a balancing mechanism.

Dr Robert Nudds at The University of Manchester is carrying out a series of biomechanical investigations to shed light on the subject with his colleague Dr Gareth Dyke at University College Dublin.

For their latest paper Dr Nudds and Dr Dyke applied a novel biomechanical analysis to the flight feathers of the early birds Archaeopteryx and Confuciusornis to find out if they were strong enough to allow flight.

They found that the dinosaur feathers’ much thinner central stem (rachis) must have been solid or they would have broken under the lift forces generated during flight or by gusts of wind. This solid structure is very different to modern birds, whose rachises are broader, hollow straws. If the dinosaurs’ feathers had had hollow rachises, they would not have been able to fly at all.

“These are surprising results,” says Dr Nudds, whose findings are published in Science (13th May 2010).

“I thought the feathers would be strong enough with a hollow rachis to fly but they weren’t. Even with a solid rachis, they were not very good. These dinosaurs were rubbish at flying.

“This pushes the origin of flapping flight to after Archaeopteryx and Confuciusornis. It must have come much later.”

It is impossible to tell from fossils whether the rachises were solid or hollow. However Dr Nudds, at Manchester’s Faculty of Life Sciences, believes the dinosaurs’ feathers were solid and therefore they could fly, but very poorly.

“The fossilsof Confuciusornis and Archaeopteryx suggest flight and at this stage it would be a brave person to say they couldn’t fly” he says.

“However their feathers must have been very different to modern birds and they were poor fliers. I believe the feathers were originally for insulation or display purposes then they found that by elongating them they had a parachuting surface, then a gliding surface.

“Archeopteryx and Confuciusornis are still at a very early stage in the evolution of flight.”

Dr Nudds’ and Dr Dykes’ work builds on their previous paper, in the journal Evolution, which investigated how the movement of feathered dinosaur forelimbs evolved into flapping flight. Again they found the flight was a consequence of gradual changes in wing shape and movement – a long, slow evolution.

Dr Nudds adds: “Our analysis also shows that Confuciusornis, which is younger by 25 million years, was worse at flying than Archaeopteryx. This raises the further question of lineage – did the dinosaur-bird line branch off, giving rise to flying and flightless birds?”

He and Dr Dyke plan to analyse other fossilized feathers to find out when flapping flight evolved. However such specimens are rare.

“I don’t mind,” says Dr Nudds. “It makes it more exciting and all the more intriguing.”

(Photo: U. Manchester)

University of Manchester

SEMICONDUCTOR MANUFACTURING TECHNIQUE HOLDS PROMISE FOR SOLAR ENERGY

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Thanks to a new semiconductor manufacturing method pioneered at the University of Illinois, the future of solar energy just got brighter.

Although silicon is the industry standard semiconductor in most electronic devices, including the photovoltaic cells that solar panels use to convert sunlight into energy, it is hardly the most efficient material available. For example, the semiconductor gallium arsenide and related compound semiconductors offer nearly twice the efficiency as silicon in solar devices, yet they are rarely used in utility-scale applications because of their high manufacturing cost.

U. of I. professors John Rogers and Xiuling Li explored lower-cost ways to manufacture thin films of gallium arsenide that also allowed versatility in the types of devices they could be incorporated into. “If you can reduce substantially the cost of gallium arsenide and other compound semiconductors, then you could expand their range of applications,” said Rogers, the Lee J. Flory Founder Chair in Engineering Innovation, and a professor of materials science and engineering and of chemistry.

Typically, gallium arsenide is deposited in a single thin layer on a small wafer. Either the desired device is made directly on the wafer, or the semiconductor-coated wafer is cut up into chips of the desired size. The Illinois group decided to deposit multiple layers of the material on a single wafer, creating a layered, “pancake” stack of gallium arsenide thin films.

“If you grow 10 layers in one growth, you only have to load the wafer one time,” said Li, a professor of electrical and computer engineering. “If you do this in 10 growths, loading and unloading with temperature ramp-up and ramp-down take a lot of time. If you consider what is required for each growth – the machine, the preparation, the time, the people – the overhead saving our approach offers is a significant cost reduction.”

Next the researchers individually peel off the layers and transfer them. To accomplish this, the stacks alternate layers of aluminum arsenide with the gallium arsenide. Bathing the stacks in a solution of acid and an oxidizing agent dissolves the layers of aluminum arsenide, freeing the individual thin sheets of gallium arsenide. A soft stamp-like device picks up the layers, one at a time from the top down, for transfer to another substrate – glass, plastic or silicon, depending on the application. Then the wafer can be reused for another growth.

“By doing this we can generate much more material more rapidly and more cost effectively,” Rogers said. “We’re creating bulk quantities of material, as opposed to just the thin single-layer manner in which it is typically grown.”

Freeing the material from the wafer also opens the possibility of flexible, thin-film electronics made with gallium arsenide or other high-speed semiconductors. “To make devices that can conform but still retain high performance, that’s significant,” Li said.

In a paper to be published online May 20 in the journal Nature, the group describes its methods and demonstrates three types of devices using gallium arsenide chips manufactured in multilayer stacks: light sensors, high-speed transistors and solar cells. The authors also provide a detailed cost comparison.

Another advantage of the multilayer technique is the release from area constraints, especially important for solar cells. As the layers are removed from the stack, they can be laid out side-by-side on another substrate to produce a much larger surface area, whereas the typical single-layer process limits area to the size of the wafer.

“For photovoltaics, you want large area coverage to catch as much sunlight as possible. In an extreme case we might grow enough layers to have 10 times the area of the conventional route,” Rogers said.

“You really multiply the area coverage, and by a similar multiplier you reduce the cost, while at the same time eliminating the consumption of the wafer,” he said.

Among the paper’s co-authors are two scientists from Semprius Inc., a North Carolina-based startup company that is beginning to use this technique to manufacture solar cells. A shift from silicon-based panels to more efficient gallium arsenide models could make solar power a more cost-effective form of alternative energy.

Next, the group plans to explore more potential device applications and other semiconductor materials that could adapt to multilayer growth.

(Photo: John Rogers)

University of Illinois

AN ISLAND AS A REFLECTION OF THE WORLD

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Réunion is to Ralf Sommer and Matthias Herrmann from the Max Plank Institute for Developmental Biology in Tübingen what the Galápagos Islands were to Charles Darwin. The island in the Indian Ocean is where the biologists are studying biological diversity with the help of a very unremarkable creature: the nematode.

Nematodes, which are tiny worms, can be found in virtually every ecosystem throughout the world, and count as one of the most biologically diverse groups in the animal kingdom. The biologists recently succeeded in drawing up an evolutionary tree of these animals which explains their global proliferation. They were helped in their efforts by studies conducted on the island of Réunion. The worm Pristionchus pacificus was frequently introduced onto the island as a "stowaway", whereupon it achieved a substantial degree of genetic diversity, and enabling it to adapt quickly to new habitats. Just why this particular species is so successful throughout the world is a subject which the scientists are keen to explore more closely at their new field station. "To achieve this, we need to consider population genetics and evolutionary ecology as well," says Ralf Sommer, Director at the Tübingen-based Institute.

In the wild, P. pacificus enters into a fascinating alliance with beetles from the scarab beetle family, which includes the May bug, dung beetle and rose chafer. The young worms attach to a beetle and enter into dormancy, waiting for the beetle to die. When the host dies, the worms resume their development and feed on the microbes, colonising the decomposing carcass. This behaviour was discovered several years ago by Matthias Herrmann, entomologist and nematode expert in Sommer’s department. The Tübingen-based biologists have already travelled all over the world studying this close relative of the very well-studied Caenorhabditis elegans in all its diversity. For the past two years they have also been studying the nematodes on Réunion, an island in the Indian Ocean of less than 1000 square kilometres. The interactions of the species under investigation can be recorded in precise detail in this manageable terrain - ideal conditions for studying population genetics and their dynamics. Herrman is on the look-out for species of beetle that cannot be found anywhere else in the world, as well as those that have been introduced onto the island. "Many of them could be home to unique nematodes," says the scientist.

The developmental biologists from Tübingen initially examined the genes of 96 nematodes that were found to exist on the island. The scientists were able to classify the samples into four distinct species; 76 isolates belonged to the species P. pacificus. In order to compare how they were inter-related and to uncover possible differences between them and other global P. pacificus isolates, the biologists analysed the genetic material in the animals’ mitochondria. What they discovered was astounding: it turned out that the specimens discovered on Réunion represent a large proportion of the entire genetic diversity of this nematode - anywhere in the world. "This indicates that the worms settled on the island on numerous separate occasions since it was formed two to three million years ago," says Ralf Sommer. The analyses conducted to date also imply that the worms arrived on the island after they had already taken up residence on their respective host beetles.

The close association between P. pacificus and the beetles previously presented the researchers with several problems. By the time they had transported the material gathered on Réunion back to Germany, the beetles had long since died. And it was no longer the original worms that were living in them - but their offspring. However, since the beginning of the year, the scientists have been able to carry out their initial analyses on the island itself: in January they inaugurated a "container lab" in the harbour town of Le Port. The six-metre-long field station enables the Institute’s researchers to conduct long-term studies on the island - a significant step, as in future the scientists from Tübingen want to add population-genetic studies on Réunion to the other studies that they are carrying out world-wide. "It’s important to us to find out whether phenotypical differences, which we previously observed in P. pacificus strains living a considerable distance apart also occur in a local context," says Sommer. This could shed light on how natural variation between individuals affects the evolution of a species. The scientists also want to find out how certain characteristics change in the course of time, and as a function of environmental conditions on the island.

(Photo: Max-Planck-Institut für Entwicklungsbiologie)

Max Plank Institute

GESTURE-BASED COMPUTING ON THE CHEAP

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Ever since Steven Spielberg’s 2002 sci-fi movie Minority Report, in which a black-clad Tom Cruise stands in front of a transparent screen manipulating a host of video images simply by waving his hands, the idea of gesture-based computer interfaces has captured the imagination of technophiles.

Academic and industry labs have developed a host of prototype gesture interfaces, ranging from room-sized systems with multiple cameras to detectors built into laptops’ screens. But MIT researchers have developed a system that could make gestural interfaces much more practical. Aside from a standard webcam, like those found in many new computers, the system uses only a single piece of hardware: a multicolored Lycra glove that could be manufactured for about a dollar.

Other prototypes of low-cost gestural interfaces have used reflective or colored tape attached to the fingertips, but “that’s 2-D information,” says Robert Wang, a graduate student in the Computer Science and Artificial Intelligence Laboratory who developed the new system together with Jovan Popović, an associate professor of electrical engineering and computer science. “You’re only getting the fingertips; you don’t even know which fingertip [the tape] is corresponding to.” Wang and Popović’s system, by contrast, can translate gestures made with a gloved hand into the corresponding gestures of a 3-D model of the hand on screen, with almost no lag time. “This actually gets the 3-D configuration of your hand and your fingers,” Wang says. “We get how your fingers are flexing.”

The most obvious application of the technology, Wang says, would be in video games: Gamers navigating a virtual world could pick up and wield objects simply by using hand gestures. But Wang also imagines that engineers and designers could use the system to more easily and intuitively manipulate 3-D models of commercial products or large civic structures.

The glove went through a series of designs, with dots and patches of different shapes and colors, but the current version is covered with 20 irregularly shaped patches that use 10 different colors. The number of colors had to be restricted so that the system could reliably distinguish the colors from each other, and from those of background objects, under a range of different lighting conditions. The arrangement and shapes of the patches was chosen so that the front and back of the hand would be distinct but also so that collisions of similar-colored patches would be rare. For instance, Wang explains, the colors on the tips of the fingers could be repeated on the back of the hand, but not on the front, since the fingers would frequently be flexing and closing in front of the palm.

Technically, the other key to the system is a new algorithm for rapidly looking up visual data in a database, which Wang says was inspired by the recent work of Antonio Torralba, the Esther and Harold E. Edgerton Associate Professor of Electrical Engineering and Computer Science in MIT’s Department of Electrical Engineering and Computer Science and a member of CSAIL. Once a webcam has captured an image of the glove, Wang’s software crops out the background, so that the glove alone is superimposed upon a white background. Then the software drastically reduces the resolution of the cropped image, to only 40 pixels by 40 pixels. Finally, it searches through a database containing myriad 40-by-40 digital models of a hand, clad in the distinctive glove, in a range of different positions. Once it’s found a match, it simply looks up the corresponding hand position. Since the system doesn’t have to calculate the relative positions of the fingers, palm, and back of the hand on the fly, it’s able to provide an answer in a fraction of a second.

Of course, a database of 40-by-40 color images takes up a large amount of memory — several hundred megabytes, Wang says. But today, a run-of-the-mill desktop computer has four gigabytes — or 4,000 megabytes — of high-speed RAM memory. And that number is only going to increase, Wang says.

“People have tried to do hand tracking in the past,” says Paul Kry, an assistant professor at the McGill University School of Computer Science. “It’s a horribly complex problem. I can’t say that there’s any work in purely vision-based hand tracking that stands out as being successful, although many people have tried. It’s sort of changing the game a bit to say, ‘Hey, okay, I’ll just add a little bit of information’” — the color of the patches — “‘and I can go a lot farther than these purely vision-based techniques.’” Kry particularly likes the ease with which Wang and Popović’s system can be calibrated to new users. Since the glove is made from stretchy Lycra, it can change size significantly from one user to the next; but in order to gauge the glove’s distance from the camera, the system has to have a good sense of its size. To calibrate the system, the user simply places an 8.5-by-11-inch piece of paper on a flat surface in front of the webcam, presses his or her hand against it, and in about three seconds, the system is calibrated.

Wang initially presented the glove-tracking system at last year’s Siggraph, the premier conference on computer graphics. But at the time, he says, the system took nearly a half-hour to calibrate, and it didn’t work nearly as well in environments with a lot of light. Now that the glove tracking is working well, however, he’s expanding on the idea, with the design of similarly patterned shirts that can be used to capture information about whole-body motion. Such systems are already commonly used to evaluate athletes’ form or to convert actors’ live performances into digital animations, but a system based on Wang and Popović’s technique could prove dramatically cheaper and easier to use.

(Photo: Jason Dorfman/CSAIL)

Massachusetts Institute of Technology

NOW HEAR THIS

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About 36 million Americans suffer from some type of hearing loss. However, only one in five who could benefit from a hearing aid actually wears one, according to the National Institute on Deafness and other Communication Disorders. MIT engineers believe that number could be boosted if there were a better way to fit hearing aids to the wearers’ ears.

Getting useful sound amplification from a hearing aid depends on a tight fit between hearing aid and ear canal, but the current method of modeling patients’ ears is messy and not always accurate, potentially leading to a device that fits poorly and offers little benefit.

“A lot of people with hearing aids are likely walking around with hearing aids that don’t fit, because they don’t know what they’re supposed to feel like,” says Douglas Hart, MIT professor of mechanical engineering.

Hart has patented a new way of scanning the ear canal with 3-D imaging technology — a process that is much faster, easier and more accurate than the plaster-mold technique. He plans to market the technology to hearing-aid manufacturers first, but believes it could also be useful to build fitted earphones for MP3 music players, or custom-fit earplugs for military personnel and other people who work in noisy environments.

The new technology is similar to a recently commercialized 3-D scanning system that Hart developed for dentistry, designed to replace the silicone molds traditionally used to make impressions for dental crowns and bridges. While Hart was working on that imaging system, hearing-aid manufacturers approached him to see what he could do to improve their fitting process.

Getting a precise 3-D scan of the ear canal is the “Holy Grail of the hearing aid industry,” says Scott Witt, head of research and development for hearing-aid manufacturer Phonak. “Taking these impressions is still the messiest, least exact part of the process,” he says.

Patients who need a hearing aid usually have to spend about an hour with an audiologist, who fills the patient’s ear canal with a gooey silicone substance. After about 15 minutes, the gel hardens into a mold that is removed from the ear and shipped to a hearing-aid manufacturer, who scans the mold and builds a custom-fit hearing aid using a 3-D printer.

With this method, it can be difficult to achieve a tight seal between the hearing aid and the patient’s ear canal. A tight seal is necessary to prevent feedback between the microphone and receiver, which can produce squealing sounds annoying to the wearer and anyone standing nearby.

With the new MIT system, a very stretchy, balloon-like membrane is inserted into the ear canal and inflated to take the shape of the canal. The membrane is filled with a fluorescent dye that can be imaged with a tiny fiber-optic camera inside the balloon. Scanning the canal takes only a few seconds, and the entire fitting process takes only a minute or two.

Witt believes the MIT scanner has more potential than any other proposed imaging system he has seen in the past several years. “What really interested me is, they say they can determine the physical properties of the ear canal, such as how soft the tissue is,” he says.

Because the camera captures 3-D images so quickly, it can measure how much the surface of the ear canal deforms when the pressure changes, or how the canal shape changes when the wearer chews or talks. That could help hearing-aid manufacturers design devices that keep their tight seal in those situations.

The higher accuracy of digital scans could also eliminate the need for repeated impressions. “So many times we get impressions and have to go back (to the audiologist) and say, ‘We can’t really use this,’” says Witt.

The Deshpande Center for Technological Innovation funded the development of the new technology, which Hart described in a 2004 article in the journal Applied Optics. He patented the system in January and has founded a company in the hope of bringing the innovation to market.

The researchers have built a prototype scanner to demonstrate the proof of concept, and are now working on a handheld version of the device. Once it’s ready, they plan to do a study comparing the fit of hearing aids built with the new scanner to that of traditional hearing aids.

The new technology could be seamlessly integrated into existing manufacturing practices, says Witt. “We could do it right now. The rest of our manufacturing process is set up to receive digital scans,” he says.

(Photo: MIT)

Massachusetts Institute of Technology

WRINKLES RATE WORSE THAN CANCER FOR TANNERS

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What's the most effective way to convince young women to cut back on their indoor tanning, a habit that hikes their risk of melanoma, the deadliest form of skin cancer, by 75 percent? Warn them that it will cause leathery, wrinkled skin.

"They're not worried about skin cancer, but they are worried about getting wrinkled and being unattractive," said June Robinson, a professor of dermatology at Northwestern University Feinberg School of Medicine and senior author of a May 17 paper in Archives of Dermatology reporting the findings. The study examined the best strategy to wean college-age women who are considered addicted or pathological tanners from tanning salons.

"The fear of looking horrible trumped everything else," said Robinson, who also is a member of the Robert H. Lurie Comprehensive Cancer Center of Northwestern University. "It was the most persuasive intervention, regardless of why they were going to tan." The research showed warning them about the effects on their appearance caused a 35 percent drop in their indoor tanning visits, which were measured at intervals up to six months after the intervention.

Joel Hillhouse, lead author of the paper and a professor of community health at East Tennessee State University, noted that some women in the study eventually stopped tanning. "It was a progressive kind of thing," he said. "At first the women said they tried sunless tanning as an alternative, but over time they gave up tanning altogether."

Between 25 to 40 percent of older adolescent girls visit tanning salons, according to the study's authors. They and other scientists link the rapidly rising rates of melanoma and other skin cancers in young women to tanning beds. A new 10 percent federal excise tax on indoor tanning will go into effect July 1 in an effort to discourage indoor tanning.

The National Cancer Institute found that melanoma rates among Caucasian women aged 15 to 39 rose 50 percent between 1980 and 2004. The World Health Organization recently reclassified indoor tanning beds to its highest cancer risk category.

The study included 435 college women, ages 18 to 22, who visited tanning salons. Within this population, researchers focused on women who visited salons up to four times a week - more than what is needed to maintain a tan -- and who tanned for psychological reasons, not just for a special event.

These tanners included one group who strongly disliked the natural color of their skin, which was related to a psychological condition called body dysmorphia. "They thought their skin was disgusting when it was pale," Hillhouse said.

The other group, who said tanning made them feel happier and more relaxed, showed symptoms of seasonal affective disorder (SAD) on a diagnostic psychological test. "They were self medicating their own depression," Robinson said, noting that lying in a tanning bed produces internal opioids.

The women received a 25-page booklet, authored by Hillhouse, that discussed the effect of tanning on appearance and explained how ultraviolet rays destroy collagen in the skin. The booklet also offered many alternatives to meet the women's needs for tanning, such as taking an exercise class for socializing and relaxation or getting a spray-on tan or self-tanning cream application at a spa. After reading the booklet, the women reported their attitudes and behaviors twice a week in diaries.

The study results surprised researchers. "The hypothesis was because this was an appearance intervention, it would have less of an effect on the people tanning for mood problems," Hillhouse said. "We found the opposite. The intervention worked just as well for people with seasonal affective disorder as for people who didn't like their skin color. That means it's a really good intervention for everyone."

His advice to parents and physicians: "Don't focus on skin cancer. The message that will get young women's attention is indoor tanning's long-term effect on their appearance. That will wake them up and get them to think about this."

Robinson stressed it was also important to offer women alternatives to tanning salons. "You have to balance the positive and the negative forces that motivate someone to change," she said. "First you have the fear that they will look horrible, then you offer a positive - an alternative to meet their needs."

Northwestern University

NEW TYPE OF EXPLODING STAR DISCOVERED: MAY REVEAL A SOURCE OF CALCIUM

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A new type of exploding star has been discovered by an international team of scientists that includes Penn State University astronomer Derek Fox, an assistant professor of astronomy and astrophysics. Until now, scientists had observed only two basic kinds of exploding stars, known as supernovae. But now the team's discovery has revealed a third type of supernova that, if common, could reveal a previously unknown source of the calcium in our bodies and of the positron particles observed near the center of our Milky Way Galaxy. Positrons previously have been suggested as indicating of the presence of "dark matter."

The discovery was published in the May 20 issue of the journal Nature.

The two previously known supernova mechanisms involve either an old, dense "white dwarf" star whose death occurs in a powerful thermonuclear disruption, or a hot, young giant that explodes in a violent display as it collapses under its own weight. The new, comparatively dim, supernova appeared in telescope images in early January of 2005, while Fox was a researcher at the California Institute of Technology (Caltech). Seeing that the supernova, named SN 2005E, recently had begun the process of exploding, Fox and other scientists around the world started collecting and combining data from different telescopes, measuring both the amount of material thrown off in the explosion and its chemical makeup.

"We soon found that the new supernova did not fit either of the known patterns, but it took quite a long while to sort out all of the aspects of this supernova that make it so interesting," Fox said. He and other scientists formed the team that produced the Nature paper, led by Hagai Perets and Avishay Gal-Yam at The Weizmann Institute of Science in Israel. While a researcher at Caltech, Fox help to conceive and lead a yearlong program devoted to joint imaging and spectroscopic studies of bright supernovae. SN 2005E was one of the objects selected for studies under this program, which helped to reveal its identity as a new type of supernova.

The scientists found that, on the one hand, the amount of material hurled out from supernova 2005E was too small to have come from an exploding hot, young, giant star. In addition, its location, distant from the regions filled with dense gas and dust where new stars form, implied it was an older star that had had time to wander far from its birthplace. On the other hand, the mysterious object's chemical makeup didn't match that commonly seen in the other well-known type of supernova, a white-dwarf explosion. "It was clear," says the paper's first author Perets, "that we were seeing a new type of supernova." The scientists turned to computer simulations to see what kind of process could have produced such a result.

The common type of exploding white dwarf (a type Ia supernova) is made up mainly of carbon and oxygen, and the chemical composition of the ejected material reflects this composition. The newly-discovered supernova 2005E had unusually high levels of the elements calcium and titanium, which are the products of a nuclear reaction involving helium, rather than carbon and oxygen. Scientists never before had seen a spectrum like this one. Where did the helium come from? The unique chemical composition of this explosion held an important key to understanding it. The simulations suggest that a pair of white dwarves are involved; one of them stealing helium from the other. When the thief star's helium load rises past a certain point, the explosion occurs. ""The donor star may have been completely destroyed in the process, but we're not quite sure about the fate of the thief star," said Gal-Yam.

The scientists believe that several other previously observed supernovae may fit this pattern. In fact, the scientists say these relatively dim explosions might turn out to be not all that rare, which could explain some puzzling phenomena in the universe. For example, because almost all the elements heavier than hydrogen and helium have been created in supernovae, the new type could help to explain the prevalence of calcium in both the universe and in our bodies. It might also account for observed concentrations of particles called positrons in the center of our Milky Way galaxy. Positrons are identical to electrons, but with an opposite charge, and some scientists have hypothesized that the decay of yet unseen "dark matter" particles may be responsible for their presence. One of the products of the new supernova is a radioactive form of titanium that, as it decays, emits positrons. "Dark matter may or may not exist," says Gal-Yam, "but these positrons are perhaps just as easily accounted for by this new type of supernova."

(Photo: Avishay Gal-Yam; Weizmann Institute of Science)

Penn State University

IT WAS BRAWN OVER BEAUTY IN HUMAN MATING COMPETITION

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Male physical competition, not attraction, was central in winning mates among human ancestors, according to a Penn State anthropologist.

"There is sexual competition in many species, including humans," said David A. Puts, assistant professor of biological anthropology.

Many researchers have considered mate choice the main operator in human sexual selection. They thought that people's mating success was mainly determined by attractiveness; but for men, it appears that physical competition among males was more important. Puts sees humans as similar to many of the apes in using male competition to determine access to mates, the winning male choosing the women of his dreams. He reports his findings in the current issue of Evolution and Human Behavior.

"On average men are not all that much bigger than women, only about 15 percent larger," said Puts. "But, the average guy is stronger than 99.9 percent of women."

The problem is that men and women do not appear sexually dimorphic -- different sexes having radically different sizes and weights. But Puts notes that women tend to store more body fat, while men have 60 percent more muscle mass than women.

Other traits indicate physical prowess was the major force in human mate competition through history. Men are far more aggressive than women, and approximately 30 percent of men in small-scale foraging communities die violently. Puts suggests that while a deep voice has been considered an appealing trait to women, it actually signals dominance.

"A deep voice makes men look dominant and older," said Puts. "A low voice's effect on dominance is many times greater than its effect on sexual attraction."

The main sticking point with human male competition compared to other species is that male humans do not possess inherent weapons.

"Other animals have antlers or long canines and claws," said Puts. "Why don't we have them?"

According to Puts, men do have weapons. They make them. Bows and arrows, spears, knives -- men have always manufactured weapons.

Other male traits also seem to imply competition. Males have thicker jawbones, which may have come from men hitting each other and the thickest-boned men surviving. Competition may explain why males have more robust skulls and brow ridges than women.

Another argument for male competition focuses on the environment. Puts suggests that species that live in three-dimensional space -- birds and insects in the air or swimming creatures in the sea -- tend not to compete for mates using physical competition because it would be very difficult for a male to defend females while fighting other males on all fronts. Species that live on the ground or the sea floor have it easier because there are only two dimensions to defend. Some insects that live in tunnels or burrows exhibit the most intense competition because it is impossible for the other male to get to the females except through the defender.

Male competition is rare among birds, occurring to a greater degree among large terrestrial species. Tree-living primates also show less physical competition. Humans living in a two-dimensional environment would experience substantial physical competition for mates.

According to Puts, humans and chimpanzees create male coalitions that are often strengthened by kinship. Coalitions can help males defend females from other males. However, when external forces are absent, these same males can compete with each other for mates.

These ideas may seem to paint a rather bleak picture of human nature with men duking it out among themselves for most of human evolution.

"Things are different for us now in many ways," said Puts. "It's heartening to think that human behavior is flexible enough that the right social institutions can increase equality and peace."

Penn State University

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