Like humans, the paper wasp has a special talent for learning faces

"Wasps and humans have independently evolved similar and very specialized face-learning mechanisms, despite the fact that everything about the way we see and the way our brains are structured is different," said graduate student Michael Sheehan, who worked with evolutionary biologist Elizabeth Tibbetts on the face-recognition study. "That's surprising and sort of bizarre."

The study marks the first time that any insect has demonstrated such a high level of specialized visual learning, said Sheehan, lead author of a paper on the topic scheduled for online publication in the journal Science on Thursday, Dec. 1.

In earlier research, Tibbetts showed that paper wasps (Polistes fuscatus) recognize individuals of their species by variations in their facial markings and that they behave more aggressively toward wasps with unfamiliar faces.

In 2008, Sheehan and Tibbetts published a paper in Current Biology demonstrating that these wasps have surprisingly long memories and base their behavior on what they remember of previous social interactions with other wasps.

In their latest study, Sheehan and Tibbetts tested learning by training wasps to discriminate between two different images mounted inside a T-maze, with one image displayed at each end of the top arm of the T.

Twelve wasps were trained for 40 consecutive trials on each image type. The paired images included photos of normal paper wasp faces, photos of caterpillars, simple geometric patterns, and computer-altered wasp faces. A reward was consistently associated with one image in a pair.

The researchers found that the paper wasps, which are generalist visual predators of caterpillars, were able to differentiate between two unaltered P. fuscatus faces faster and more accurately than a pair of caterpillar photos, two different geometric patterns, or a pair of computer-altered wasp faces. They learned to pick the correct unaltered wasp face about three-quarters of the time.

Two simple black-and-white geometric patterns should have been easy for the wasps to distinguish, because the insects' compound eyes are good at detecting contrast and outlines, Sheehan said. Yet the wasps learned complicated face images more rapidly than the geometric patterns.

At the same time, introducing seemingly minor changes to a P. fuscatus facial image -- by using a photo-editing program to remove a wasp's antennae, for example -- caused test subjects to perform much worse on the facial recognition test.

"This shows that the way they learn faces is different than the way they seem to be learning other patterns. They treat faces as a different kind of thing," Sheehan said.

"Humans have a specialized face-learning ability, and it turns out that this wasp that lives on the side of your house evolved an analogous system on its own," he said. "But it's important to note that we're not claiming the exact process by which wasps learn faces is the same as humans."

The ability to recognize individuals is important to a species like P. fuscatus, in which multiple queens establish communal nests and raise offspring cooperatively, but also compete to form a linear dominance hierarchy. Remembering who they've already bested-and been bested by-keeps individuals from wasting energy on repeated aggressive encounters and presumably promotes colony stability by reducing friction.

Sheehan also tested a closely related species of wasp, P. metricus, which lacks the varied facial markings of the paper wasp and lives in colonies controlled by a single queen. In the T-maze test, P. metricus scored no better than chance when asked to distinguish between individuals of its own species.

"Differences in face learning between the two species cannot be attributed to general differences in visual learning, as both species learned to discriminate between pairs of artificial patterns and caterpillars at the same rate and with the same accuracy," Sheehan and Tibbetts wrote. "P. fuscatus and P. metricus differed only in their ability to learn normal face stimuli."

"The evolutionary flexibility of specialized face learning is striking and suggests that specialized cognition may be a widespread adaptation to facilitate complex behavioral tasks such as individual recognition," they wrote.

Funding for the project was provided by the University of Michigan and an E.S. George Reserve Scholarship to Sheehan.

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Like humans, the paper wasp has a special talent for learning faces

Some people can hallucinate colors at will

The study, published this week in the journal Consciousness and Cognition, was carried out in the Department of Psychology at the University of Hull. It focused on a group of people that had shown themselves to be 'highly suggestible' in hypnosis.

The subjects were asked to look at a series of monochrome patterns and to see colour in them. They were tested under hypnosis and without hypnosis and both times reported that they were able to see colours.

Individuals' reactions to the patterns were also captured using an MRI scanner, which enabled the researchers to monitor differences in brain activity between the suggestible and non-suggestible subjects. The results of the research, showed significant changes in brain activity in areas of the brain responsible for visual perception among the suggestible subjects only.

Professor Giuliana Mazzoni, lead researcher on the project says: "These are very talented people. They can change their perception and experience of the world in ways that the rest of us cannot."

The ability to change experience at will can be very useful. Research has shown that hypnotic suggestions can be used to block pain and increase the effectiveness of psychotherapy.

It has always been assumed that hypnosis was needed for these effects to occur, but the new study suggests that this is not true. Although hypnosis does seem to heighten the subjects' ability to see colour, the suggestible subjects were also able to see colours and change their brain activity even without the help of hypnosis.

The MRI scans also showed clearly that although it was not necessary for the subjects to be under hypnosis to be able to perceive colours in the tests, it was evident that hypnosis increased the ability of the subjects to experience these effects.

Dr William McGeown, who also contributed to the study, says: "Many people are afraid of hypnosis, although it appears to be very effective in helping with certain medical interventions, particularly pain control. The work we have been doing shows that certain people may benefit from suggestion without the need for hypnosis."

The study, which was partially funded by the BBC, used a control group formed of less suggestible people, or people less likely to respond to hypnosis. It was found that this group of people were not able to hallucinate colour and, again, these reported results were supported by MRI scans.

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Some people can hallucinate colors at will

When the heat's on, some fish can cope: Certain tropical species have greater capacity to deal with rising sea temperatures than thought

The discovery, by researchers at the ARC Centre of Excellence for Coral Reef Studies, James Cook University and CSIRO sheds a ray of hope amid the rising concern over the future of coral reefs and their fish under the levels of global warming expected to occur by the end of the 21st century.

Understanding the ability of species to acclimatise to rising temperatures over longer time periods is critical for predicting the biological consequences of global warming -- yet it remains one of the least understood aspects of climate science. The scientists were seeking to discover how fish would cope with the elevated sea temperatures expected by 2050 and 2100.

"When we exposed damsel fish to water temperatures 1.5 degrees and 3 degrees above today's, there was a marked decline in their aerobic capacity as we'd expected," explains lead researcher Jennifer Donelson. "This affects their ability to swim fast and avoid predators."

"However when we bred the fish for several generations at higher temperatures, we found that the second generation offspring had almost completely adjusted to the higher temperatures. We were amazed… stunned, even," she says. "It shows that some species can adjust faster than the rate of climate change."

"When one generation of damselfish experiences high temperatures their whole life, the next generation is better able to cope with warmer water. We don't yet fully understand the mechanisms involved, but it doesn't seem to be simple Darwinian selection over a couple of generations," explains team leader Professor Philip Munday.

"Instead, there has been a transmission of information between the generations that enables damselfish to adjust to higher water temperatures."

The two temperatures used in the trial represent likely tropical ocean temperatures at the mid-century and by 2100, based on current trends in carbon dioxide emissions by humanity. A 3 degree increase in tropical ocean temperatures is the temperature predicted to occur if humanity's carbon dioxide emissions continue on their current trajectory.

The unusual finding suggests that some fish may have an innate ability to cope with increased sea temperatures greater than previously thought, the researchers say.

However they caution it applies so far only to a single coral reef fish species, and does not address the more complex issue of the survival of the coral habitat itself, and the effects of warming on plankton in the food chains on which fish depend.

Also, there are likely to be penalties for fish that successfully adapt to higher temperatures, Jennifer Donelson says. Initial observations suggest that the acclimatized offspring are on average smaller than their parents, and we still do not know if they are able to reproduce at the same rate as their predecessors.

Although the experiment has yet to run its full course, the researchers also say they do not expect the fishes' ability to adjust to higher temperatures to continue past 3 degrees.

"At such a level of planetary warming there will be profound changes in Earth's ecosystems, affecting all forms of life, including humans," says Prof. Munday.

However, assuming humans manage to gradually bring global warming under control, it is important to understand how well animals and plants can cope with higher temperatures, in order to manage ecosystems for optimum survival of their species and the services they provide. This research provides an early insight into the adaptive capacity of fish, the team says.

This study reveals that transgenerational acclimation is a potentially important mechanism for coping with rapid climate change. Such acclimation could reduce the impact of warming temperatures and allow some fish populations to persist across their current range, instead of having to move away in search of cooler waters.

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When the heat's on, some fish can cope: Certain tropical species have greater capacity to deal with rising sea temperatures than thought

Climate changes faster than species can adapt, rattlesnake study finds

The study, which focuses on North American rattlesnakes, finds that the rate of future change in suitable habitat will be two to three orders of magnitude greater than the average change over the past 300 millennia, a time that included three major glacial cycles and significant variation in climate and temperature.

"We find that, over the next 90 years, at best these species' ranges will change more than 100 times faster than they have during the past 320,000 years," said Michelle Lawing, lead author of the paper and a doctoral candidate in geological sciences and biology at IU Bloomington. "This rate of change is unlike anything these species have experienced, probably since their formation."

The study, "Pleistocene Climate, Phylogeny, and Climate Envelope Models: An Integrative Approach to Better Understand Species' Response to Climate Change," was published by the online science journal PLoS ONE. Co-author is P. David Polly, associate professor in the Department of Geological Sciences in the IU Bloomington College of Arts and Sciences.

The researchers make use of the fact that species have been responding to climate change throughout their history and their past responses can inform what to expect in the future. They synthesize information from climate cycle models, indicators of climate from the geological record, evolution of rattlesnake species and other data to develop what they call "paleophylogeographic models" for rattlesnake ranges. This enables them to map the expansion and contraction at 4,000-year intervals of the ranges of 11 North American species of the rattlesnake genus Crotalus.

Projecting the models into the future, the researchers calculate the expected changes in range at the lower and upper extremes of warming predicted by the Intergovernmental Panel on Climate Change -- between 1.1 degree and 6.4 degrees Celsius. They calculate that rattlesnake ranges have moved an average of only 2.3 meters a year over the past 320,000 years and that their tolerances to climate have evolved about 100 to 1000 times slower, indicating that range shifts are the only way that rattlesnakes have coped with climate change in the recent past. With projected climate change in the next 90 years, the ranges would be displaced by a remarkable 430 meters to 2,400 meters a year.

Increasing temperature does not necessarily mean expanded suitable habitats for rattlesnakes. For example, Crotalus horridus, the timber rattlesnake, is now found throughout the Eastern United States. The study finds that, with a temperature increase of 1.1 degree Celsius over the next 90 years, its range would expand slightly into New York, New England and Texas. But with an increase of 6.4 degrees, its range would shrink to a small area on the Tennessee-North Carolina border. C. adamanteus, the eastern diamondback rattlesnake, would be displaced entirely from its current range in the southeastern U.S. with a temperature increase of 6.4 degrees.

The findings suggest snakes wouldn't be able to move fast enough to keep up with the change in suitable habitat. The authors suggest the creation of habitat corridors and managed relocation may be needed to preserve some species.

Rattlesnakes are good indicators of climate change because they are ectotherms, which depend on the environment to regulate their body temperatures. But Lawing and Polly note that many organisms will be affected by climate change, and their study provides a model for examining what may happen with other species. Their future research could address the past and future effects of climate change on other types of snakes and on the biological communities of snakes.

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Climate changes faster than species can adapt, rattlesnake study finds

Giant super-Earths made of diamond are possible, study suggests

A new study suggests that some stars in the Milky Way could harbor "carbon super-Earths" -- giant terrestrial planets that contain up to 50 percent diamond.

But if they exist, those planets are likely devoid of life as we know it.

The finding comes from a laboratory experiment at Ohio State University, where researchers recreated the temperatures and pressures of Earth's lower mantle to study how diamonds form there.

The larger goal was to understand what happens to carbon inside planets in other solar systems, and whether solar systems that are rich in carbon could produce planets that are mostly made of diamond.

Wendy Panero, associate professor in the School of Earth Sciences at Ohio State, and doctoral student Cayman Unterborn used what they learned from the experiments to construct computer models of the minerals that form in planets composed with more carbon than Earth.

The result: "It's possible for planets that are as big as fifteen times the mass of the Earth to be half made of diamond," Unterborn said. He presented the study Tuesday at the American Geophysical Union meeting in San Francisco.

"Our results are striking, in that they suggest carbon-rich planets can form with a core and a mantle, just as Earth did," Panero added. "However, the cores would likely be very carbon-rich -- much like steel -- and the mantle would also be dominated by carbon, much in the form of diamond."

Earth's core is mostly iron, she explained, and the mantle mostly silica-based minerals, a result of the elements that were present in the dust cloud that formed into our solar system. Planets that form in carbon-rich solar systems would have to follow a different chemical recipe -- with direct consequences for the potential for life.

Earth's hot interior results in geothermal energy, making our planet hospitable.

Diamonds transfer heat so readily, however, that a carbon super-Earth's interior would quickly freeze. That means no geothermal energy, no plate tectonics, and -- ultimately -- no magnetic field or atmosphere.

"We think a diamond planet must be a very cold, dark place," Panero said.

She and former graduate student Jason Kabbes subjected a tiny sample of iron, carbon, and oxygen to pressures of 65 gigapascals and temperatures of 2,400 Kelvin (close to 9.5 million pounds per square inch and 3,800 degrees Fahrenheit -- conditions similar to the Earth's deep interior).

As they watched under the microscope, the oxygen bonded with the iron, creating iron oxide -- a type of rust -- and left behind pockets of pure carbon, which became diamond.

Based on the data from that test, the researchers made computer models of Earth's interior, and verified what geologists have long suspected -- that a diamond-rich layer likely exists in Earth's lower mantle, just above the core.

That result wasn't surprising. But when they modeled what would happen when these results were applied to the composition of a carbon super-Earth, they found that the planet could become very large, with iron and carbon merged to form a kind of carbon steel in the core, and vast quantities of pure carbon in the mantle in the form of diamond.

The researchers discussed the implications for planetary science.

"To date, more than five hundred planets have been discovered outside of our solar system, yet we know very little about their internal compositions," said Unterborn, who is an astronomer by training.

"We're looking at how volatile elements like hydrogen and carbon interact inside the Earth, because when they bond with oxygen, you get atmospheres, you get oceans -- you get life," Panero said. "The ultimate goal is to compile a suite of conditions that are necessary for an ocean to form on a planet."

This work contrasts with the recent discovery by an unrelated team of researchers who found a so-called "diamond planet" which is actually the remnant of a dead star in a binary system.

The Ohio State research suggests that true terrestrial diamond planets can form in our galaxy. Exactly how many such planets might be out there and their possible internal composition is an open question -- one that Unterborn is pursuing with Ohio State astronomer Jennifer Johnson.

This research was funded by Panero's CAREER award from the National Science Foundation.

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Giant super-Earths made of diamond are possible, study suggests

NASA's Kepler confirms its first planet in habitable zone outside our solar system

The newly confirmed planet, Kepler-22b, is the smallest yet found to orbit in the middle of the habitable zone of a star similar to our sun. The planet is about 2.4 times the radius of Earth. Scientists don't yet know if Kepler-22b has a predominantly rocky, gaseous or liquid composition, but its discovery is a step closer to finding Earth-like planets.

Previous research hinted at the existence of near-Earth-size planets in habitable zones, but clear confirmation proved elusive. Two other small planets orbiting stars smaller and cooler than our sun recently were confirmed on the very edges of the habitable zone, with orbits more closely resembling those of Venus and Mars.

"This is a major milestone on the road to finding Earth's twin," said Douglas Hudgins, Kepler program scientist at NASA Headquarters in Washington. "Kepler's results continue to demonstrate the importance of NASA's science missions, which aim to answer some of the biggest questions about our place in the universe."

Kepler discovers planets and planet candidates by measuring dips in the brightness of more than 150,000 stars to search for planets that cross in front, or "transit," the stars. Kepler requires at least three transits to verify a signal as a planet.

"Fortune smiled upon us with the detection of this planet," said William Borucki, Kepler principal investigator at NASA Ames Research Center at Moffett Field, Calif., who led the team that discovered Kepler-22b. "The first transit was captured just three days after we declared the spacecraft operationally ready. We witnessed the defining third transit over the 2010 holiday season."

The Kepler science team uses ground-based telescopes and NASA's Spitzer Space Telescope to review observations on planet candidates the spacecraft finds. The star field that Kepler observes in the constellations Cygnus and Lyra can only be seen from ground-based observatories in spring through early fall. The data from these other observations help determine which candidates can be validated as planets.

Kepler-22b is located 600 light-years away. While the planet is larger than Earth, its orbit of 290 days around a sun-like star resembles that of our world. The planet's host star belongs to the same class as our sun, called G-type, although it is slightly smaller and cooler.

Of the 54 habitable zone planet candidates reported in February 2011, Kepler-22b is the first to be confirmed. This milestone will be published in The Astrophysical Journal.

The Kepler team is hosting its inaugural science conference at Ames Dec. 5-9, announcing 1,094 new planet candidate discoveries. Since the last catalog was released in February, the number of planet candidates identified by Kepler has increased by 89 percent and now totals 2,326. Of these, 207 are approximately Earth-size, 680 are super Earth-size, 1,181 are Neptune-size, 203 are Jupiter-size and 55 are larger than Jupiter.

The findings, based on observations conducted May 2009 to September 2010, show a dramatic increase in the numbers of smaller-size planet candidates.

Kepler observed many large planets in small orbits early in its mission, which were reflected in the February data release. Having had more time to observe three transits of planets with longer orbital periods, the new data suggest that planets one to four times the size of Earth may be abundant in the galaxy.

The number of Earth-size, and super Earth-size candidates, has increased by more than 200 and 140 percent since February, respectively.

There are 48 planet candidates in their star's habitable zone. While this is a decrease from the 54 reported in February, the Kepler team has applied a stricter definition of what constitutes a habitable zone in the new catalog, to account for the warming effect of atmospheres, which would move the zone away from the star, out to longer orbital periods.

"The tremendous growth in the number of Earth-size candidates tells us that we're honing in on the planets Kepler was designed to detect: those that are not only Earth-size, but also are potentially habitable," said Natalie Batalha, Kepler deputy science team lead at San Jose State University in San Jose, Calif. "The more data we collect, the keener our eye for finding the smallest planets out at longer orbital periods."

NASA's Ames Research Center manages Kepler's ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed Kepler mission development.

Ball Aerospace and Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

The Space Telescope Science Institute in Baltimore archives, hosts and distributes the Kepler science data. Kepler is NASA's 10th Discovery Mission and is funded by NASA's Science Mission Directorate at the agency's headquarters.

For more information about the Kepler mission and to view the digital press kit, visit http://www.nasa.gov/kepler .

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NASA's Kepler confirms its first planet in habitable zone outside our solar system

'Double tsunami' doubled Japan destruction

Satellites captured not just one wave front that day, but at least two, which merged to form a single double-high wave far out at sea -- one capable of traveling long distances without losing its power. Ocean ridges and undersea mountain chains pushed the waves together, but only along certain directions from the tsunami's origin.

The discovery helps explain how tsunamis can cross ocean basins to cause massive destruction at some locations while leaving others unscathed, and raises hope that scientists may be able to improve tsunami forecasts.

At a news conference Dec. 5 at the American Geophysical Union meeting in San Francisco, Y. Tony Song, a research scientist at NASA's Jet Propulsion Laboratory (JPL); and C.K. Shum, professor and Distinguished University Scholar in the Division of Geodetic Science, School of Earth Sciences at Ohio State University, discussed the satellite data and simulations that enabled them to piece the story together.

"It was a one-in-ten-million chance that we were able to observe this double wave with satellites," said Song, the study's principal investigator. "Researchers have suspected for decades that such 'merging tsunamis' might have been responsible for the 1960 Chilean tsunami that killed many in Japan and Hawaii, but nobody had definitively observed a merging tsunami until now."

"It was like looking for a ghost," he continued. "A NASA/French Space Agency satellite altimeter happened to be in the right place at the right time to capture the double wave and verify its existence."

Shum agreed. "We were very lucky, not only in the timing of the satellite, but also to have access to such detailed GPS-observed ground motion data from Japan to initiate Tony's tsunami model, and to validate the model results using the satellite data. Now we can use what we learned to make better forecasts of tsunami danger in specific coastal regions anywhere in the world, depending on the location and the mechanism of an undersea quake."

The NASA/Centre National d'Etudes Spaciales Jason-1 satellite passed over the tsunami on March 11, as did two other satellites: the NASA/European Jason-2 and the European Space Agency's EnviSAT. All three carry a radar altimeter, which measures sea level changes to an accuracy of a few centimeters.

Each satellite crossed the tsunami at a different location. Jason-2 and EnviSAT measured wave heights of 20 cm (8 inches) and 30 cm (12 inches), respectively. But as Jason-1 passed over the undersea Mid-Pacific Mountains to the east, it captured a wave front measuring 70 cm (28 inches).

The researchers conjectured ridges and undersea mountain chains on the ocean floor deflected parts of the initial tsunami wave away from each other to form independent jets shooting off in different directions, each with its own wave front.

The sea floor topography nudges tsunami waves in varying directions and can make a tsunami's destruction appear random. For that reason, hazard maps that try to predict where tsunamis will strike rely on sub-sea topography. Previously, these maps only considered topography near a particular shoreline. This study suggests scientists may be able to create maps that take into account all undersea topography, even sub-sea ridges and mountains far from shore.

Song and his team were able to verify the satellite data through model simulations based on independent data, including the GPS data from Japan and buoy data from the National Oceanic and Atmospheric Administration's Deep-ocean Assessment and Reporting of Tsunamis program.

"Tools based on this research could help officials forecast the potential for tsunami jets to merge," said Song. "This, in turn, could lead to more accurate coastal tsunami hazard maps to protect communities and critical infrastructure."

Song and Shum's collaborators include Ichiro Fukumori, an oceanographer and supervisor in JPL's Ocean Circulation Group; and Yuchan Yi, a research scientist in the Division of Geodetic Science, School of Earth Sciences at Ohio State.

This research was supported by NASA.

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'Double tsunami' doubled Japan destruction

Global carbon emissions reach record 10 billion tons, threatening 2 degree target

Published Dec. 4 in the journal Nature Climate Change, the new analysis by the Global Carbon Project shows fossil fuel emissions increased by 5.9 per cent in 2010 and by 49 per cent since 1990 -- the reference year for the Kyoto protocol.

On average, fossil fuel emissions have risen by 3.1 per cent each year between 2000 and 2010 -- three times the rate of increase during the 1990s. They are projected to continue to increase by 3.1 per cent in 2011.

Total emissions -- which combine fossil fuel combustion, cement production, deforestation and other land use emissions -- reached 10 billion tonnes of carbon* in 2010 for the first time. Half of the emissions remained in the atmosphere, where CO₂ concentration reached 389.6 parts per million. The remaining emissions were taken up by the ocean and land reservoirs, in approximately equal proportions.

Rebounding from the global financial crisis of 2008-09 when emissions temporarily decreased, last year's high growth was caused by both emerging and developed economies. Rich countries continued to outsource part of their emissions to emerging economies through international trade.

Contributions to global emissions growth in 2010 were largest from China, the United States, India, the Russian Federation and the European Union. Emissions from the trade of goods and services produced in emerging economies but consumed in the West increased from 2.5 per cent of the share of rich countries in 1990 to 16 per cent in 2010.

In the UK, fossil fuel CO₂ emissions grew 3.8 per cent in 2010 but were 14 per cent below their 1990 levels. However, emissions from the trade of goods and services grew from 5 per cent of the emissions produced locally in 1990 to 46 per cent in 2010 -- overcompensating the reductions in local emissions. Emissions in the UK were 20 per cent above their 1990 levels when emissions from trade are taken into account.

"Global CO₂ emissions since 2000 are tracking the high end of the projections used by the Intergovernmental Panel on Climate Change, which far exceed two degrees warming by 2100," said co-author Prof Corinne Le Quéré, director of the Tyndall Centre for Climate Change Research and professor at the University of East Anglia. "Yet governments have pledged to keep warming below two degrees to avoid the most dangerous aspects of climate change such as widespread water stress and sea level rise, and increases in extreme climatic events.

"Taking action to reverse current trends is urgent."

Lead author Dr Glen Peters, of the Centre for International Climate and Environmental Research in Norway, said: "Many saw the global financial crisis as an opportunity to move the global economy away from persistent and high emissions growth, but the return to emissions growth in 2010 suggests the opportunity was not exploited."

Co-author Dr Pep Canadell, executive director of the Global Carbon Project, added: "The global financial crisis has helped developed countries meet their production emission commitments as promised in the Kyoto Protocol and Copenhagen Accord, but its impact has been short-lived and pre-existing challenges remain."

* Values reported here are in billion tonnes of carbon. To convert emissions to billion tonnes of CO₂, multiply the value by 3.67.

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Global carbon emissions reach record 10 billion tons, threatening 2 degree target

Record massive black holes discovered lurking in monster galaxies

These black holes are at the centers of two galaxies more than 300 million light years from Earth, and may be the dark remnants of some of the very bright galaxies, called quasars, that populated the early universe.

"In the early universe, there were lots of quasars or active galactic nuclei, and some were expected to be powered by black holes as big as 10 billion solar masses or more," said Chung-Pei Ma, UC Berkeley professor of astronomy. "These two new supermassive black holes are similar in mass to young quasars, and may be the missing link between quasars and the supermassive black holes we see today."

Black holes are dense concentrations of matter that produce such strong gravitational fields that even light cannot escape. While exploding stars, called supernovas, can leave behind black holes the mass of a single star like the sun, supermassive black holes have presumably grown from the merger of other black holes or by capturing huge numbers of stars and massive amounts of gas.

"These black holes may shed light on how black holes and their surrounding galaxies have nurtured each other since the early universe," said UC Berkeley graduate student Nicholas McConnell, first author of a paper on the discovery being published in the Dec. 8 issue of the British journal Nature by McConnell, Ma and their colleagues at the university of Toronto, Texas and Michigan, as well as by the National Optical Astronomy Observatory in Arizona.

To date, approximately 63 supermassive black holes have been found sitting in the cores of nearby galaxies. The largest for more than three decades was a 6.3 billion solar mass black hole in the center of the nearby galaxy M87.

One of the newly discovered black holes is 9.7 billion solar masses and located in the elliptical galaxy NGC 3842, the brightest galaxy in the Leo cluster of galaxies, 320 million light years away in the direction of the constellation Leo. The second is as large or larger and sits in the elliptical galaxy NGC 4889, the brightest galaxy in the Coma cluster about 336 million light years from Earth in the direction of the constellation Coma Berenices.

According to McConnell, these black holes have an event horizon -- the "abandon all hope" edge from which not even light can escape -- that is 200 times the orbit of Earth, or five times the orbit of Pluto. Beyond the event horizon, each black hole has a gravitational influence that would extend over a sphere 4,000 light years across.

"For comparison, these black holes are 2,500 times as massive as the black hole at the center of the Milky Way Galaxy, whose event horizon is one fifth the orbit of Mercury," McConnell said.

The brightest galaxy in a cluster

These 10 billion solar mass black holes have remained hidden until now, presumably because they are living in quiet retirement, Ma said. During their active quasar days some 10 billion years ago, they cleared out the neighborhood by swallowing vast quantities of gas and dust. The surviving gas became stars that have since orbited peacefully. According to Ma, these monster black holes, and their equally monster galaxies that likely contain a trillion stars, settled into obscurity at the center of galaxy clusters.

Ma, a theoretical astrophysicist, decided to look for these huge black holes in relatively nearby clusters of elliptical galaxies as a result of her computer simulations of galaxy mergers.

Astronomers believe that many, if not all, galaxies have a massive black hole at the center, with the larger galaxies harboring larger black holes. The largest black holes are found in elliptical galaxies, which are thought to result from the merger of two spiral galaxies. Ma found, however, that mergers of elliptical galaxies themselves could produce the largest elliptical galaxies as well as supermassive black holes approaching 10 billion solar masses. These black holes can grow even larger by consuming gas left over from a merger.

"Multiple mergers are one way to build up these behemoths," Ma said.

To look for these monster black holes, Ma teamed up with observational astronomers, including James Graham, a professor of astronomy at UC Berkeley and the University of Toronto, and Karl Gebhardt, a professor of astronomy at the University of Texas at Austin. Gebhardt had obtained the mass of the previous record holder in galaxy M87.

Using telescopes at the Gemini and Keck observatories in Hawaii and at McDonald Observatory in Texas, McConnell and Ma obtained detailed spectra of the diffuse starlight at the centers of several massive elliptical galaxies, each the brightest galaxy in its cluster. So far, they've analyzed the orbital velocities of stars in two galaxies and calculated the central masses to be in the quasar range. Having such huge masses contained within a volume only a few hundred light years across led the astronomers to conclude that the masses were massive black holes.

"If all that mass were in stars, then we would see their light," Ma said.

Modeling these massive galaxies required use of state-of-the-art supercomputers at the Texas Advanced Computing Center.

"For an astronomer, finding these insatiable black holes is like finally encountering people nine feet tall, whose great height had only been inferred from fossilized bones. How did they grow so large?" Ma said. "This rare find will help us understand whether these black holes had very tall parents or ate a lot of spinach."

Other coauthors of the Nature paper are Hubble postdoctoral fellow Shelley A. Wright at UC Berkeley and graduate student Jeremy D. Murphy of the University of Texas; Tod R. Lauer of the National Optical Astronomy Observatory; and Douglas O. Richstone of the University of Michigan.

The research was supported by the National Science Foundation, the National Aeronautics and Space Administration and UC Berkeley's Miller Institute for Basic Research in Science.

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Record massive black holes discovered lurking in monster galaxies

Global winds could explain record rains, tornadoes

Both events seem to be linked to a relatively rare coupling between the polar and the subtropical jet streams, says Jonathan Martin, a University of Wisconsin-Madison professor of atmospheric and oceanic sciences.

But the fascinating part is that the change originates in the western Pacific, about 9,000 miles away from the intense storms in the U.S. midsection, Martin says.

The mechanism that causes the storms originates during spring or fall when organized complexes of tropical thunderstorms over Indonesia push the subtropical jet stream north, causing it to merge with the polar jet stream.

The subtropical jet stream is a high-altitude band of wind that is normally located around 30 degrees north latitude. The polar jet stream is normally hundreds of miles to the north.

Martin calls the resulting band of wind a "superjet."

Jet streams in the northern hemisphere blow from the west at roughly 140 miles per hour, and are surrounded by a circular whirlwind that looks something like a tornado pushed on its side. The circulating wind at the bottom of the jet stream blows from the south. On the north side, the circulating winds turn vertical, lifting and cooling the air until the water vapor condenses and feeds precipitation.

A superjet and its circulating winds carry roughly twice as much energy as a typical jet stream, Martin says. "When these usually separate jet streams sit atop one another, there tends to be a very strong vertical circulation, which produces clouds, precipitation and tornadoes under the right conditions."

And because the circulating wind in a superjet moving across the U.S. south picks up moisture from the Gulf of Mexico, "the superjet gives a double-whammy -- more moisture, and more lifting, producing that intense rain."

That was the case in May 2010, when 10 to 20 inches of rain fell around Nashville.

Andrew Winters, who is now a graduate student studying with Martin, latched onto the Tennessee flood as the topic of his senior undergraduate thesis in 2010. "It had a lot of interesting aspects, brought an anomalous amount of moisture into the southeast, and that hefty amount of rain," Winters says.

And that super-strong jet stream "could be traced back to conditions in the western Pacific, almost a week earlier," Winters says.

Martin and Winters describe their work in talks Dec. 6 and 7 at the annual meeting of the American Geophysical Union in San Francisco.

Studies of the Tennessee floods, the Alabama tornados, and an odd October storm in Wisconsin showed "that when the subtropical jet is pushed poleward under the influence of strong thunderstorms in the western Pacific, it seems to result in these intense storms in the U.S. midsection," Martin says. "It's a really fascinating global connection that occurs seven to 10 days later."

Martin also suggests the altered position of the subtropical jet stream may be linked to global warming.

"There is reason to believe that in a warmer climate, this kind of overlapping of the jet streams that can lead to high-impact weather may be more frequent," Martin says.

That idea can be tested, Martin adds.

"Historic weather data should tell us whether there has been a change in the frequency of these overlapping events, and whether that might be linked to a change in high impact-weather events. It's an interesting lead that could help us understand one possible mechanism by which a warmer climate could lead to an increase in severe weather," he says.

Although hurricanes can be tracked for a week or more as they cross the Atlantic Ocean, weather phenomena seldom last so long, Martin says. "If the subtropical jet stream is rearranged and superposed on top of the polar jet stream, it might be the mechanism that allows for this very long delay, a disturbance that can have discernible effect on severe weather thousands of miles downstream, and a week or more later."

Martin says that if the new analysis survives further study, it could contribute to severe weather forecasting.

Though severe weather was forecast a day or two in advance of the deadly tornado outbreak in the Southeast this April, "most tornado forecasts are made 12 or at most 24 hours in advance. That saves lives. But if we get the idea five or six days in advance that we should watch the position of the jet streams, we could say, 'Hey, we have a pretty exciting week coming up, we have to be on high alert.'"

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Global winds could explain record rains, tornadoes

World's most efficient flexible organic light-emitting diodes created on plastic

The results are reported online in the latest issue of Nature Photonics.

OLEDs provide high-contrast and low-energy displays that are rapidly becoming the dominant technology for advanced electronic screens. They are already used in some cell phone and other smaller-scale applications.

Current state-of-the-art OLEDs are produced using heavy-metal doped glass in order to achieve high efficiency and brightness, which makes them expensive to manufacture, heavy, rigid and fragile.

"For years, the biggest excitement behind OLED technologies has been the potential to effectively produce them on flexible plastic," says Materials Science & Engineering Professor Zheng-Hong Lu, the Canada Research Chair (Tier I) in Organic Optoelectronics.

Using plastic can substantially reduce the cost of production, while providing designers with a more durable and flexible material to use in their products.

The research, which was supervised by Professor Lu and led by PhD Candidates Zhibin Wang and Michael G. Helander, demonstrated the first high-efficiency OLED on plastic. The performance of their device is comparable with the best glass-based OLEDs, while providing the benefits offered by using plastic.

"This discovery, unlocks the full potential of OLEDs, leading the way to energy-efficient, flexible and impact-resistant displays," says Professor Lu.

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World's most efficient flexible organic light-emitting diodes created on plastic

Physicists identify room temperature quantum bits in widely used semiconductor

The research team discovered that silicon carbide contains crystal imperfections that can be controlled at a quantum mechanical level. The finding is published this week in the journal Nature.

The research group of David Awschalom, senior author, made the finding. Awschalom is director of UCSB's Center for Spintronics & Quantum Computation, professor of physics, electrical and computer engineering, and the Peter J. Clarke Director of the California NanoSystems Institute.

In conventional semiconductor-based electronic devices, crystal defects are often deemed undesirable because of their tendency to immobilize electrons by "trapping" them at a particular crystal location. However, the UCSB team discovered that electrons that become trapped by certain imperfections in silicon carbide do so in a way that allows their quantum states to be initialized, precisely manipulated, and measured using a combination of light and microwave radiation. This means that each of these defects meets the requirements for use as a quantum bit, or "qubit," which is often described as the quantum mechanical analog of a transistor, since it is the basic unit of a quantum computer.

"We are looking for the beauty and utility in imperfection, rather than struggling to bring about perfect order," said Awschalom, "and to use these defects as the basis for a future quantum technology."

Most crystal imperfections do not possess these properties, which are intimately tied to the atomic structure of a defect and the electronic characteristics of its semiconductor host, explained Awschalom. In fact, before this research, the only system known to possess these same characteristics was a flaw in diamond known as the nitrogen-vacancy center.

The diamond nitrogen-vacancy center is renowned for its ability to function as a qubit at room temperature, while many other quantum states of matter require an extremely cold temperature, near absolute zero. However, this center exists in a material that is difficult to grow and challenging to manufacture into integrated circuits.

In contrast, high-quality crystals of silicon carbide, multiple inches in diameter, are commonly produced for commercial purposes. They can be readily fashioned into a multitude of intricate electronic, optoelectronic, and electromechanical devices. In addition, the defects studied by Awschalom and his group are addressed using infrared light that is close in energy to the light used widely throughout modern telecommunications networks. And while several distinct defect types were studied at a range of temperatures, two of them were capable of room temperature operation, just like the diamond nitrogen-vacancy center.

The combination of these features makes silicon carbide, with its defects, an attractive candidate for future work seeking to integrate quantum mechanical objects with sophisticated electronic and optical circuitry, according to the researchers. This research fits within a wider effort at UCSB to engineer quantum devices by fostering collaboration between the fields of materials science and quantum physics.

While defects in silicon carbide may offer many technologically attractive qualities, an immense number of defects in other semiconductors are still left to be explored.

"Our dream is to make quantum mechanics fully engineerable," said William Koehl, lead author and a graduate student in the Awschalom lab. "Much like a civil engineer is able to design a bridge based on factors such as load capacity and length span, we'd like to see a day when there are quantum engineers who can design a quantum electronic device based on specifications such as degree of quantum entanglement and quality of interaction with the surrounding environment."

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Physicists identify room temperature quantum bits in widely used semiconductor

'Noise' tunes logic circuit made from virus genes

Engineers from Arizona State University in Tempe and the Space and Naval Warfare Systems Center (SPAWAR) in San Diego, Calif., are exploiting noise to control the basic element of a computer – a logic gate that can be switched back and forth between two different logic functions, such as AND\OR – using a genetically engineered system derived from virus DNA. In a paper accepted to the AIP’s journal Chaos, the team has demonstrated, theoretically, that by exploiting sources of external noise, they can make the network switch between different logic functions in a stable and reliable way.

The scientists focused on a single-gene network in a bacteriophage λ (lamda). The gene they use regulates the production of a particular protein in the virus. Normally, there are biological reactions that regulate the creation and destruction of this protein; upsetting that balance results in a protein concentration that is either too high or too low. The scientists assigned a “1” to one concentration and a “0” to the other. By manipulating the protein concentration, the team could encode the logic gate input values and obtain the desired output values.

Researchers modeled the system as two potential energy “wells” separated by a hump, corresponding to an energy barrier. In the presence of too much noise, the system never relaxes into one of the two wells, making the output unpredictable. Too little noise, on the other hand, does not provide the boost necessary for the system to reach a high enough protein concentration to overcome the energy barrier; in this case, there is also a high probability that the biological logic gate will fail to achieve its predicted computation. But an optimal amount of noise stabilizes the circuit, causing the system to jump into the “correct well” – and stay there.

This proof-of-concept work offers the possibility of exploiting noise in biologic circuits instead of regarding it as a laboratory curiosity or a nuisance, the researchers say.

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'Noise' tunes logic circuit made from virus genes

Researching graphene nanoelectronics for a post-silicon world

As new generations of computer chips continue to shrink in size, so do the copper pathways that transport electricity and information around the labyrinth of transistors and components. When these pathways -- called interconnects -- grow smaller, they become less efficient, consume more power, and are more prone to permanent failure.

To overcome this hurdle, industry and academia are vigorously researching new candidates to succeed traditional copper as the material of choice for interconnects on computer chips. One promising candidate is graphene, an atom-thick sheet of carbon atoms arranged like a nanoscale chicken-wire fence. Prized by researchers for its unique properties, graphene is essentially a single layer of the graphite found commonly in our pencils or the charcoal we burn on our barbeques.

Led by Rensselaer Professor Saroj Nayak, a team of researchers discovered they could enhance the ability of graphene to transmit electricity by stacking several thin graphene ribbons on top of one another. The study, published in the journal ACS Nano, brings industry closer to realizing graphene nanoelectronics and naming graphene as the heir apparent to copper.

"Graphene shows enormous potential for use in interconnects, and stacking up graphene shows a viable way to mass produce these structures," said Nayak, a professor in the Department of Physics, Applied Physics, and Astronomy at Rensselaer. "Copper's limitations are apparent, as increasingly smaller copper interconnects suffer from sluggish electron flows that results in hotter, less reliable devices. Our new study makes a case for the possibility that stacks of graphene ribbons could have what it takes to be used as interconnects in integrated circuits."

The study, based on large-scale quantum simulations, was conducted using the Rensselaer Computational Center for Nanotechnology Innovations (CCNI), one of the world's most powerful university-based supercomputers.

Copper interconnects suffer from a variety of unwanted problems, which grow more prominent as the size of the interconnects shrink. Electrons travel through the copper nanowires sluggishly and generate intense heat. As a result, the electrons "drag" atoms of copper around with them. These misplaced atoms increase the copper wire's electrical resistance, and degrade the wire's ability to transport electrons. This means fewer electrons are able to pass through the copper successfully, and any lingering electrons are expressed as heat. This heat can have negative effects on both a computer chip's speed and performance.

It is generally accepted that a quality replacement for traditional copper must be discovered and perfected in the next five to 10 years in order to further perpetuate Moore's Law -- ;an industry mantra that states the number of transistors on a computer chip, and thus the chip's speed, should double every 18 to 24 months.

Nayak's recent work, published in the journal ACS Nano, is titled "Effect of Layer Stacking on the Electronic Structure of Graphene Nanoribbons." When cut into nanoribbons, graphene is known to exhibit a band gap -- an energy gap between the valence and conduction bands -- which is an unattractive property for interconnects. The new study shows that stacking the graphene nanoribbons on top of each other, however, could significantly shrink this band gap.

"The optimal thickness is a stack of four to six layers of graphene," said Neerav Kharche, first author of the study and a computational scientist at CCNI. "Stacking more layers beyond this thickness doesn't reduce the band gap any further."

The end destination, Nayak said, is to one day manufacture microprocessors -- both the interconnects and the transistors -- entirely out of graphene. This game-changing goal, called monolithic integration, would mean the end of the long era of copper interconnects and silicon transistors.

"Such an advance is likely still many years into the future, but it will certainly revolutionize the way nearly all computers and electronics are designed and manufactured," Nayak said.

Along with Nayak and Kharche, contributors to this study were: former Rensselaer physics graduate student Yu Zhou; Swastik Kar, former Rensselaer physics research assistant professor; and Kevin P. O'Brien of Intel Corporation.

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Researching graphene nanoelectronics for a post-silicon world

Robot speeds up glass development

For laymen glas looks like glass -- it might be a window, a drinking vessel, a lense for an automotive headlight. But there is much more in and to the transparent material: glass can consist of 50 to 60 different elements. Experts are constantly being asked to create glass with certain characteristics out of these elements, since new applications require new materials quite often. Let's take the car as an example: the electronic components in a car's engine compartment are being brought ever closer to the engine and so must increasingly be resistant to heat and corrosive gasses. This also applies to the glue, a glass solder. In the development of fuel cells, the demand for new types of glass is also great: the use of new metals requires that the glass solder also be adapted. In addition, over a period of approximately 100,000 hours, the glass must withstand thermal heat of 900 degrees Celsius without being damaged.

In order to develop glass with new characteristics, experts select about ten compounds from potential elements, mix them and then heat the powder. They heat it in a furnace until it is soft, then they pour it into a mould and let it cool slowly and in a controlled fashion, down to room temperature. During that process small samples from the viscous glass are taken to test it: how viscous is it? How well does it wet metals? How does it crystallize out? To produce the glass samples by hand and to test them requires a lot of time: one employee needs approximately two weeks to process 16 samples.

Researchers of the Fraunhofer Institute for Silicate Research ISC in Würzburg have developed a unit that carries out all these steps automatically. "It needs only 24 hours to process 16 samples," says Dr. Martin Kilo, manager of the expert group for glass and high-temperature materials at the ISC. "For this reason we are able to develop glass elements more cost-effectively than previously, by up to 50 percent." The core piece of the unit is a robot: it puts a mixing cup on a scale and moves it under 14 storage vessels, from which a certain amount of powder is filled into the cup. Then the robot mixes the individual ingredients by closing the cup and shaking it, just like a bartender does with a cocktail shaker. The robot arm then grabs a crucible, puts it onto the scale, fills it with a certain amount of the mixed powder and puts the crucible into one of the five furnaces available in total. The robot repeats this steps several times, since gases build up when the powder is heated and foam could form otherwise. In addition, the powder shrinks during the melting process. Finally the furnace heats the fully filled crucible to a higher temperature, causing the gas bubbles in the glass to rise to the surface. Once the glass is viscous, the robot arm removes the crucible, pours the glass into a new mould and places it in a stress-relieving furnace. Here, the glass cools slowly and in a controlled manner, from 600 to 800 degrees Celsius down to room temperature.

An additional central element of the unit is the analysis unit. It works according to the thermo-optical measurement principle. Looking through two measurement windows, the shade the sample projects in a backlight test system is recorded by a CCD camera. The changes in the contour make it possible to determine characteristics such as sample volume, hemisphere point and wetting angle. This test unit measures how viscous the melt is, and if and how it crystallizes and wets metals. The test unit can also be used independently of the glass screening unit. The unit also determines and records the ability of the glass to conduct heat.

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Robot speeds up glass development

New revolutionary material can be worked like glass

And, quite surprisingly, it also retains certain properties specific to organic resins and rubbers: it is light, insoluble and difficult to break. Inexpensive and easy to produce, this material could be used in numerous industrial applications, particularly in the automobile, aeronautics, building, electronics and leisure sectors. This work is published on 18 November 2011 in Science.

Replacing metals by lighter but just as efficient materials is a necessity for numerous industries, such as aeronautics, car manufacturing, building, electronics and sports industry. Due to their exceptional mechanical strength and thermal and chemical resistance, composite materials based on thermosetting resins are currently the most suitable. However, such resins must be cured in situ, using from the outset the definitive shape of the part to be produced. In fact, once these resins have hardened, welding and repair become impossible. In addition, even when hot, it is impossible to reshape parts in the manner of a blacksmith or glassmaker.

This is because glass (inorganic silica) is a unique material: once heated, it changes from a solid to a liquid state in a very progressive manner (glass transition), which means it can be shaped as required without using molds. Conceiving highly resistant materials that can be repaired and are infinitely malleable, like glass, is a real challenge both in economic and ecological terms. It requires a material that is capable of flowing when hot, while being insoluble and neither as brittle nor as "heavy" as glass.

From ingredients that are currently available and used in industry (epoxy resins, hardeners, catalysts, etc.), researchers from the Laboratoire "Matière Molle et Chimie" (CNRS/ESPCI ParisTech) developed a novel organic material made of a molecular network with original properties: under the action of heat, this network is capable of reorganizing itself without altering the number of cross-links between its atoms. This novel material goes from the liquid to the solid state or vice versa, just like glass. Until now, only silica and some inorganic compounds were known to show this type of behavior. The material thus acts like purely organic silica. It is insoluble even when heated above its glass transition temperature.

Remarkably, at room temperature, it resembles either hard or soft elastic solids, depending on the chosen composition. In both cases, it has the same characteristics as thermosetting resins and rubbers currently used in industry, namely lightness, resistance and insolubility. Most importantly, it has a significant advantage over the latter as it is reshapeable at will and can be repaired and recycled under the action of heat. This property means it can undergo transformations using methods that cannot be envisaged either for thermosetting resins or for conventional plastic materials. In particular, it makes it possible to produce shapes that are difficult or even impossible to obtain by molding or for which making a mold is too expensive for the envisaged purpose.

Used as the basis of composites, this new material could therefore favorably compete with metals and find extensive applications in sectors as diverse as electronics, car manufacturing, construction, aeronautics or printing. In addition to these applications, these results shed unexpected light on a fundamental problem: the physics of glass transition.

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New revolutionary material can be worked like glass

Highly efficient method for creating flexible, transparent electrodes developed

Besides its high price, ITO has several drawbacks. It's brittle, making it impractical for use in flexible displays and solar cells, and there is a lack of availability of indium, which is found primarily in Asia. Further, the production of ITO films is relatively inefficient.

Now, researchers at UCLA report in the journal ACS Nano that they have developed a unique method for producing transparent electrodes that uses silver nanowires in combination with other nanomaterials. The new electrodes are flexible and highly conductive and overcome the limitations associated with ITO.

For some time, silver nanowire (AgNW) networks have been seen as promising candidates to replace ITO because they are flexible and each wire is highly conductive. But complicated treatments have often been required to fuse crossed AgNWs to achieve low resistance and good substrate adhesion. To address this, the UCLA researchers demonstrated that by fusing AgNWs with metal-oxide nanoparticles and organic polymers, they could efficiently produce highly transparent conductors.

The team of researchers represents a collaboration between the department of materials science and engineering at the UCLA Henry Samueli School of Engineering and Applied Science; the department of chemistry and biochemistry in the UCLA College of Letters and Science; and the California NanoSystems Institute (CNSI) at UCLA.

The team was led by Yang Yang, a professor of materials science and engineering, and Paul Weiss, director of the CNSI and a professor of materials science and engineering and of chemistry and biochemistry.

"In this work, we demonstrate a simple and effective solution method to achieve highly conductive AgNW composite films with excellent optical transparency and mechanical properties," said Yang who also directs the Nano Renewable Energy Center at the CNSI. "This is by far the best solution: a processed, transparent electrode that is compatible with a wide variety of substrate choices."

Scientists can easily spray a surface with the nanowires to make a transparent mat, but the challenge is to make the silver nanowires adhere to the surface more securely without the use of extreme temperatures (200° C) or high pressures, steps that make the nanomaterials less compatible with the sensitive organic materials typically used to make flexible electronics.

To meet this challenge, Rui Zhu, the paper's first author, developed a low-temperature method to make high-performance transparent electrodes from silver nanowires using spray coating of a unique combination of nanomaterials.

First, researchers sprayed a solution of commercially available silver nanowires onto a surface. They then treated the nanowires with a solution of titanium dioxide nanoparticles to create a hybrid film. As the film dries, capillary forces pull the nanowires together, improving the film's conductivity. The scientists then coated the film with a layer of conductive polymer to increase the wires' adhesion to the surface.

The AgNW composite meshes are highly conductive, with excellent optical transparency and mechanical properties. The research team also built solar cells using the new electrodes and found that their performance was comparable to that of solar cells made with indium tin oxide.

The research received support from the Office of Naval Research and the Kavli Foundation.

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Highly efficient method for creating flexible, transparent electrodes developed

Emerging new properties at oxide interfaces

In many ionic materials, including the oxides, surfaces created along specific directions can become electrically charged. By the same token, such electronic charging, or 'polarisation', can also occur at the interface of two connecting materials.

Theoretically, this could lead to the build-up of an ever increasing voltage in the materials in certain systems, a situation known as a 'polarity catastrophe'. Certainly this cannot occur in practical systems, for energy sake, and Nature deals with this situation by reconstructing the electronic configuration of the interface via a shifting of charges across the interface, or by structural reconstructions, namely, the displacement of atoms.

With oxide materials, a unique consequence of these reconstructions is that it provides a means to create novel electronic phases, stabilised by the interface, and which cannot exist in the bulk.

Dr. Ariando from the National University of Singapore's (NUS) Department of Physics and NUS Nanoscience and Nanotechnology-NanoCore, along with his co-workers, showed that at this interface, a remarkable combination of strong diamagnetism (superconductor like), paramagnetism and ferromagnetism can co-exist with the quasi two-dimensional electron gas when prepared under a more oxidising condition.

Past studies had shown that two-dimensional conducting planes, in the form of quasi two-dimensional electron gas, could emerge between otherwise non-magnetic insulating oxide, Lanthanum Alumniate (LaAlO3) and Strontium Titanate (SrTiO3).

Interestingly, Dr. Ariando's team had also shown that the ferromagnetic phase was stable even above room temperature and the diamagnetism below a relatively high temperature of 60 K.

Industrial applications

The results also indicate that the free surface of SrTiO3 could well be responsible for all these fascinating phenomena. The SrTiO3 resembles Silicon. This will have a significant impact on industry since Silicon has been used in semiconductor technology -- silicon has been the workhorse for oxide-based devices and electronics.

These multiple electronic and magnetic phases at oxide interfaces could yield interesting technological applications. That a variety of magnetic states can be produced close to the surface (< 10 nm) by changing the external stimulus to the SrTiO3 or the interface of LaAlO3/SrTiO3, be it change in oxygen pressure or magnetic field, thus proves that this is a very active interface, and that it can yield strong responses to external stimuli.

One could well consider building novel sensors out of these interfaces that could be used as, say, oxygen sensors, or even magnetic sensors. Still, where these applications are concerned, there is a need to further understand these phenomena and optimise the device configuration.

The research of Dr. Ariando and his co-workers in the oxide interface field is reminiscent of the times when two-dimensional electron gas in the semiconductor heterostructures first became available, and the quantum Hall effect and fractional quantum Hall effect were discovered, both resulting in Nobel prizes.

The physics of the oxide material systems is however richer, involving much stronger interaction between the electrons, mutually and within the crystal lattice. There is great interest in exploring these interfaces in the quest for new nano-electronic devices.

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Emerging new properties at oxide interfaces

When it comes to churning out electrons, metal glass beats plastics

The embedded nanotubes, which serve as the source for the electrons, also enable the normally inert plastic to conduct electricity. This has the desired effect of producing a versatile and easily manufactured field emission device. But since plastics are, by nature, poor conductors of electricity, they require a high concentration of nanomaterials to function. Plastics also have low thermal stability and do not hold up well under the excess heat produced by prolonged operation.

A team of researchers from Monash University in Australia, in collaboration with colleagues from CSIRO Process Science and Engineering, has developed a promising and easily manufactured replacement for plastics: amorphous bulk metallic glass (ABM). These ABM alloys form amorphous materials as they cool, giving them more of a glass-like behavior. In a paper accepted for publication in the AIP's journal Applied Physics Letters, the researchers used an alloy made from magnesium, copper, and gadolinium.

This metallic glass has many of plastics' desirable features. It can conform to a variety of shapes, be produced in bulk, and serve as an effective matrix for the nanotubes. Besides its high conductivity, the metallic glass' highly robust thermal properties mean that it can withstand high temperatures and still retain its shape and durability. According to the researchers, these advantages, alongside excellent electron emission properties, make these composites one of the best reported options for electron emission applications to date.

Though other composites of bulk metallic glass and carbon nanotubes have been reported before, this is the first time that such a system is being used for a functional device, such as for field emission. Electron microscopes, microwave or X-ray generation, nano-electronics, and modern display devices are all examples of the potential applications of this technology, the researchers note.

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When it comes to churning out electrons, metal glass beats plastics

First molybdenite microchip

After having revealed the electronic advantages of molybdenite, EPFL researchers have now taken the next definitive step. The Laboratory of Nanoscale Electronics and Structures (LANES) has made a chip, or integrated circuit, confirming that molybdenite can surpass the physical limits of silicon in terms of miniaturization, electricity consumption, and mechanical flexibility.

"We have built an initial prototype, putting from two to six serial transistors in place, and shown that basic binary logic operations were possible, which proves that we can make a larger chip," explains LANES director Andras Kis, who recently published two articles on the subject in the scientific journal ACS Nano.

In early 2011, the lab unveiled the potential of molybdenum disulfide (MoS₂), a relatively abundant, naturally occurring mineral. Its structure and semi-conducting properties make it an ideal material for use in transistors. It can thus compete directly with silicon, the most highly used component in electronics, and on several points it also rivals graphene.

Three atoms thick

"The main advantage of MoS₂ is that it allows us to reduce the size of transistors, and thus to further miniaturize them," explains Kis. It has not been possible up to this point to make layers of silicon less than two nanometers thick, because of the risk of initiating a chemical reaction that would oxidize the surface and compromise its electronic properties. Molybdenite, on the other hand, can be worked in layers only three atoms thick, making it possible to build chips that are at least three times smaller. At this scale, the material is still very stable and conduction is easy to control.

Not as greedy

MoS₂ transistors are also more efficient. "They can be turned on and off much more quickly, and can be put into a more complete standby mode," Kis explains. Molybdenite is on a par with silicon in terms of its ability to amplify electronic signals, with an output signal that is four times stronger than the incoming signal. This proves that there is "considerable potential for creating more complex chips," Kis says. "With graphene, for example, this amplitude is about 1. Below this threshold, the output voltage would not be sufficient to feed a second, similar chip."

Built in flexibility

Molybdenite also has mechanical properties that make it interesting as a possible material for use in flexible electronics, such as eventually in the design of flexible sheets of chips. These could, for example, be used to manufacture computers that could be rolled up or devices that could be affixed to the skin.

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First molybdenite microchip

Fully printed carbon nanotube transistor circuits for displays

OLED-based displays are now used in cell phones, digital cameras and other portable devices. But developing a lower-cost method for mass-producing such displays has been complicated by the difficulties of incorporating thin-film transistors that use amorphous silicon and polysilicon into the production process.

Now, researchers from Aneeve Nanotechnologies, a startup company at UCLA's on-campus technology incubator at the California NanoSystems Institute (CNSI), have used low-cost ink-jet printing to fabricate the first circuits composed of fully printed back-gated and top-gated carbon nanotube-based electronics for use with OLED displays. 

The startup includes collaborators from the departments of materials science and electrical engineering at the UCLA Henry Samueli School of Engineering and Applied Science and the department of electrical engineering at the University of Southern California.

In this innovative study, the team made carbon nanotube thin-film transistors with high mobility and a high on-off ratio, completely based on ink-jet printing. They demonstrated the first fully printed single-pixel OLED control circuits, and their fully printed thin-film circuits showed significant performance advantages over traditional organic-based printed electronics.

"This is the first practical demonstration of carbon nanotube-based printed circuits for display backplane applications," said Kos Galatsis, an associate adjunct professor of materials science at UCLA Engineering and a co-founder of Aneeve. "We have demonstrated carbon nanotubes' viable candidacy as a competing technology alongside amorphous silicon and metal-oxide semiconductor solution as a low-cost and scalable backplane option."

This distinct process utilizes an ink-jet printing method that eliminates the need for expensive vacuum equipment and lends itself to scalable manufacturing and roll-to-roll printing. The team solved many material integration problems, developed new cleaning processes and created new methods for negotiating nano-based ink solutions.

For active-matrix OLED applications, the printed carbon nanotube transistors will be fully integrated with OLED arrays, the researchers said. The encapsulation technology developed for OLEDs will also keep the carbon nanotube transistors well protected, as the organics in OLEDs are very sensitive to oxygen and moisture.

The technology incubator at the CNSI was established two years ago to nurture early-stage research and to help speed the commercial translation of technologies developed at UCLA. Aneeve Nanotechnologies LLC has been conducting proof-of-concept work at the tech incubator with the mission of developing superior, low-cost, high-performance electronics using nanotechnology solutions that bridge the gap between emerging and traditional platforms.

The research was published this month in the journal Nano Letters.

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Fully printed carbon nanotube transistor circuits for displays

New magnetic-field-sensitive alloy could find use in novel micromechanical devices

The alloy exhibits a phenomenon called "giant magnetostriction," an amplified change in dimensions when placed in a sufficiently strong magnetic field. The effect is analogous to the more familiar piezoelectric effect that causes certain materials, like quartz, to compress under an electric field. They can be used in a variety of ways, including as sensitive magnetic field detectors and tiny actuators for micromechanical devices. The latter is particularly interesting to engineers because, unlike piezoelectrics, magnetostrictive elements require no wires and can be controlled by an external magnetic field source.

To find the best mixture of metals and processing, the team used a combinatorial screening technique, fabricating hundreds of tiny test cantilevers -- tiny, 10-millimeter-long, silicon beams looking like diving boards -- and coating them with a thin film of alloy, gradually varying the ratio of cobalt to iron across the array of cantilevers. They also used two different heat treatments, including, critically, one in which the alloy was heated to an annealing temperature and then suddenly quenched in water.

Quenching is a classic metallurgy technique to freeze a material's microstructure in a state that it normally only has when heated. In this case, measurements at NIST and the Stanford Synchrotron Radiation Lightsource (SSRL) showed that the best-performing alloy had a delicate hetereogenous, nanoscale structure in which cobalt-rich crystals were embedded throughout a different, iron-rich crystal structure. Magnetostriction was determined by measuring the amount by which the alloy bent the tiny silicon cantilever in a magnetic field, combined with delicate measurements at NIST to determine the stiffness of the cantilever.

The best annealed alloy showed a sizeable magnetostriction effect in magnetic fields as low as about 0.01 Tesla. (Earth's magnetic field generally ranges around roughly 0.000 045 T, and a typical ferrite refrigerator magnet might be about 0.7 T.)

The results, says team leader Ichiro Takeuchi of UMd, are lower than, but comparable to, the values for the best known magnetostrictive material, a rare-earth alloy called Tb-Dy-Fe* -- but with the advantage that the new alloy doesn't use the sometimes difficult to acquire rare earths. "Freezing in the heterogeneity by quenching is an old method in metallurgy, but our approach may be unique in thin films," he observes. "That's the beauty -- a nice, simple technique but you can get these large effects."

The quenched alloy might offer both size and processing advantages over more common piezoelectric microdevices, says NIST materials scientist Will Osborn. "Magnetorestriction devices are less developed than piezoelectrics, but they're becoming more interesting because the scale at which you can operate is smaller," he says. "Piezoelectrics are usually oxides, brittle and often lead-based, all of which is hard on manufacturing processes. These alloys are metal and much more compatible with the current generation of integrated device manufacturing. They're a good next-generation material for microelectromechanical machines."

The effort also involved researchers from the Russian Institute of Metal Physics, Urals Branch of the Academy of Science; Oregon State University and Rowan University. Funding sources included the Office of Naval Research and the National Science Foundation. SSRL is part of the SLAC National Accelerator Laboratory, operated under the auspices of the U.S. Department of Energy.

* Terbium-dysprosium-iron.

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New magnetic-field-sensitive alloy could find use in novel micromechanical devices

New switch could improve electronics

The research findings, supported by a $1 million grant from the W.M. Keck Foundation, were published online in the Nov. 14 issue of Nano Letters.

"This new switch is superior to existing single-molecule concepts," said Hrvoje Petek, principal investigator and professor of physics and chemistry in the Kenneth P. Dietrich School of Arts and Sciences and codirector of the Petersen Institute for NanoScience and Engineering (PINSE) at Pitt. "We are learning how to reduce electronic circuit elements to single molecules for a new generation of enhanced and more sustainable technologies."

The switch was discovered by experimenting with the rotation of a triangular cluster of three metal atoms held together by a nitrogen atom, which is enclosed entirely within a cage made up entirely of carbon atoms. Petek and his team found that the metal clusters encapsulated within a hollow carbon cage could rotate between several structures under the stimulation of electrons. This rotation changes the molecule's ability to conduct an electric current, thereby switching among multiple logic states without changing the spherical shape of the carbon cage. Petek says this concept also protects the molecule so it can function without influence from outside chemicals.

Because of their constant spherical shape, the prototype molecular switches can be integrated as atom-like building blocks the size of one nanometer (100,000 times smaller than the diameter of a human hair) into massively parallel computing architectures.

The prototype was demonstrated using an Sc3N@C80 molecule sandwiched between two electrodes consisting of an atomically flat copper oxide substrate and an atomically sharp tungsten tip. By applying a voltage pulse, the equilateral triangle-shaped Sc3N could be rotated predictably among six logic states.

The research was led by Petek in collaboration with chemists at the Leibnitz Institute for Solid State Research in Dresden, Germany, and theoreticians at the University of Science and Technology of China in Hefei, People's Republic of China. The experiments were performed by postdoctoral researcher Tian Huang and research assistant professor Min Feng, both in Pitt's Department of Physics and Astronomy.

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New switch could improve electronics

S-t-r-e-t-c-h-i-n-g electrical conductance to the limit

In research appearing in a recent issue of Nature Nanotechnology, Tao describes a method for mechanically controlling the geometry of a single molecule, situated in a junction between a pair of gold electrodes that form a simple circuit. The manipulations produced over tenfold increase in conductivity.

The unusual, often non-intuitive characteristics of single molecules may eventually be introduced into a broad range of microelectronics, suitable for applications including biological and chemical sensing electronic and mechanical devices.

Delicate molecular manipulations requiring patience and finesse are routine for Tao, whose research at Biodesign's Center for Bioelectronics and Biosensors has included work on molecular diodes, graphene behavior and molecular imaging techniques. Nevertheless, he was surprised at the outcome described in the current paper: "If you have a molecule attached to electrodes, it can stretch like a rubber band," he says. "If it gets longer, most people tend to think that the conductivity will decrease. A longer wire is less conductive than a shorter wire."

Indeed, diminishing conductivity through a molecule is commonly observed when the distance between the electrodes attached to its surface is increased and the molecule becomes elongated. But according to Tao, if you stretch the molecule enough, something unexpected happens: the conductance goes up -- by a huge amount. "We see at least 10 times greater conductivity, simply by pulling the molecule."

As Tao explains, the intriguing result is a byproduct of the laws of quantum mechanics, which dictate the behavior of matter at the tiniest scales: "The conductivity of a single molecule is not simply inversely proportional to length. It depends on the energy level alignment."

In the metal leads of the electrodes, electrons can move about freely but when they come to an interface -- in this case, a molecule that sits in the junction between electrodes -- they have to overcome an energy barrier. The height of this energy barrier is critical to how readily electrons can pass through the molecule. By applying a mechanical force to the molecule, the barrier is lowered, improving conductance.

"Theoretically, people have thought of this as a possibility, but this is a demonstration that it really happens," Tao says. "If you stretch the molecule and geometrically increase the length, it energetically lowers the barrier so electrons can easily go through. If you think in optical terms, it becomes more transparent to electrons."

The reason for this has to do with a property known as force-induced resonant tunneling. This occurs when the molecular energy moves closer to the Fermi level of the electrodes -- that is, toward the region of optimal conductance. Thus, as the molecule is stretched, it causes a decrease in the tunneling energy barrier.

For the experiments, Tao's group used 1,4'-Benzenedithiol, the most widely studied entity for molecular electronics. Further experiments demonstrated that the transport of electrons through the molecule underwent a corresponding decrease as the distance between the electrodes was reduced, causing the molecule's geometry to shift from a stretched condition to a relaxed or squeezed state. "We have to do this thousands of times to be sure the effect is robust and reproducible."

In addition to the discovery's practical importance, the new data show close agreement with theoretical models of molecular conductance, which had often been at variance with experimental values, by orders of magnitude.

Tao stresses that single molecules are compelling candidates for a new types of electronic devices, precisely because they can exhibit very different properties from those observed in conventional semiconductors.

Microelectromechanical systems or MEMS are just one domain where the versatile properties of single molecules are likely to make their mark. These diminutive creations represent a $40 billion a year industry and include such innovations as optical switches, gyroscopes for cars, lab-on-chip biomedical applications and microelectronics for mobile devices.

"In the future, when people design devices using molecules, they will have a new toolbox they can use."

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S-t-r-e-t-c-h-i-n-g electrical conductance to the limit

MEMS transistor integrated on CMOS

PORTLAND, Ore.—A micro-electro-mechanical system (MEMS) transistor was announced by Semiconductor Research Corp. (SRC) and Cornell University, giving SRC members access to on-chip timing solutions for their CMOS chips.

The MEMS-JFET builds a junction field-effect transistor (JFET) on top of a silicon resonator, providing both amplification and a rock-solid mechanical reference for on-chip channel-select filters and oscillators.

"We believe that this research result will allow the direct integration of radio frequency sources onto silicon chips alongside all the other CMOS circuitry," said Kwok Ng, senior director of device sciences at SRC.

The process works by integrating the MEMS and JFET structures on a silicon-on-insulator (SoI) substrate using conventional CMOS processes. Sacrificial oxides are then etched from beneath the single-crystal silicon resonator leaving it suspended. Using a p-n junctions as the transducer, the JFET can be made to oscillate at a frequency determined by the dimensions of the suspended MEMS resonator.


Junction field-effect transistor (JFET) built on a silicon resonator provides both amplification and a rock-solid mechanical reference for on-chip channel-select filters and oscillators.

MEMS transistor integrated on CMOS

Fab tool spending projected to decline in 2012

SAN FRANCISCO—Worldwide sales of new semiconductor manufacturing equipment are set to grow 4.7 percent in 2011, but forecast to decrease by roughly 10.8 percent next year before returning to growth in 2013, according to the fab tool vendor trade group SEMI.

SEMI (San Jose, Calif.) projects that sales of new semiconductor equipment will reach $41.8 billion in 2011, following a 151 percent market increase in 2011. Equipment revenues of $41.8 billion are roughly equivalent with 2007 investment levels, SEMI said during the annual Semicon Japan exposition near Tokyo.

"Given the exceptional growth in the market from 2009 to 2010, the lower growth rate in 2011 is   expected, not surprising," said Denny McGuirk, SEMI's president and CEO, in a statement. "The industry experiences highly cyclical markets, with the rebound likely to occur in 2013."

Wafer processing equipment, the largest product segment by dollar value, is expected to increase 9.3 percent in 2011 to almost $32.7 billion, SEMI said. The forecast predicts that the market for assembly and packaging equipment will decline by 12.5 percent to $3.4 billion in 2011. The market for semiconductor test equipment is forecasted to decline by 10.3 percent, reaching $3.7 billion this year, according to the forecast.



Fab tool spending projected to decline in 2012

ABB launches sulphur hexafluoride (SF6) insulating gas recycling technology Electronics News

ABB has launched its new SF6 (sulphur hexafluoride) gas recycling centre at Moorebank, NSW, the first of its kind in the world.

SF6 gas is extensively used in the electrical industry for dielectric insulation and current interruption in circuit breakers, switchgear, and other electrical equipment.

Pressurised SF6 gas is used for the safe and reliable operation of gas-insulated switchgear as it has a much higher dielectric strength than air or dry nitrogen, making it possible to significantly reduce product footprint and enable installation in constrained spaces.

However, managing the lifecycle of the SF6 gas is a challenge, as the cost of handling SF6 in a compliant manner can also be substantial, particularly when decommissioning aging substations.

The ABB technology comprehensively recycles contaminated SF6 gas. It is based on a new energy-efficient cryogenic process, and yields recycled SF6 gas with a purity of around 99.99 percent.

Using recycled SF6 gas will help reduce carbon emissions and could result in a cost saving potential of up to 30 percent.

The new service offering will see contaminated SF6 gas recycled into technical grade standard (according to IEC 60376 standards) for reuse using approved handling practices that do not allow the escape of SF6 gas into the atmosphere.

The service also covers monitoring to ensure compliance with changing local and international regulations and standards.

ABB launches sulphur hexafluoride (SF6) insulating gas recycling technology Electronics News

Solar cells and screens derived from crabs? Electronics News

SOLAR cells and flexible displays in the future could owe their underlying substrate technology to the humble crab, following work by Kyoto University researchers.

The scientists, Muhammad Iftekhar Shams and his team, took an entire (dead) crab, and treated with hydrochloric acid, sodium hydroxide and ethanol. This treatment stripped the body of minerals, proteins, lipids, fats and pigments.

The chitin crab shell was then immersed in an acrylic resin monomer. This caused a polymerisation reaction which rendered the shell completely see-through.

In a second experiment, the team crushed up chitin from crab shells and spread the powder into a nanocomposite sheet. The acrylic resin monomer treatment was applied, and the material became a transparent panel.

The material does not expand or lose its stability when heated. It also has a high light transmittance. It is ten times as resistant to heat as traditional materials, making it a very viable potential material for building bendable screens or solar cells that are moulded into shapes.

Solar cells and screens derived from crabs? Electronics News

IBM demos racetrack memory and nanotech chips Electronics News

IBM introduced a number of research breakthrough at the IEEE International Electron Devices Meeting.

According to IBM, these advancements could lead to dramatically smaller, faster and more powerful computer chips, allowing the industry to surpass Moore’s Law.

With virtually all electronic equipment today built on complementary-symmetry metal–oxide–semiconductor (CMOS) technology, there is an urgent need for new materials and circuit architecture designs compatible with this engineering process as the technology industry nears physical scalability limits of the silicon transistor.  

IBM says it has successfully integrated the development and application of new materials and logic architectures on 200mm (eight inch) diameter wafers.

Racetrack Memory

Racetrack memory combines the benefits of magnetic hard drives and solid-state memory to overcome challenges of growing memory demands and shrinking devices.

IBM researchers are proving the feasibility of Racetrack memory by detailing the first of these sorts of devices integrated with CMOS technology on 200mm wafers.

They have demonstrated read and write functionality on an array of 256 in-plane, magnetized horizontal racetracks. Eventually, the density will be boosted using perpendicular magnetized racetracks and three-dimensional architectures.

Graphene

This first-ever CMOS-compatible graphene device can advance wireless communications, and enable new, high frequency devices, which can operate under adverse temperature and radiation conditions in areas such as security and medical applications.

The graphene integrated circuit, a frequency multiplier, is operational up to 5 GHz and stable up to 200 degrees Celcius. While detailed thermal stability still needs to be evaluated, these results are promising for graphene circuits to be used in high temperature environments.

New architecture flips the current graphene transistor structure on its head. Instead of trying to deposit gate dielectric on an inert graphene surface, the researchers developed a novel embedded gate structure that enables high device yield on a 200mm wafer.

Carbon Nanotubes

IBM researchers also demonstrated the first transistor with sub-10 nm channel lengths, which outperform the best of the comparable silicon-based devices currently in existence.

At channel lengths below 10nm, conventional silicon technology will face extreme performance difficulties even with new advanced device architectures.

The scaled carbon nanotube devices below 10nm gate length are a significant breakthrough for future applications in computing technology.

The carbon nanotube devices have improved switching speed in the on-state, as well as excellent off-state behaviour.

IBM demos racetrack memory and nanotech chips Electronics News