Wednesday, January 6, 2010


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Skull fragments of prehistoric koalas from the Riversleigh rainforests of millions of years ago suggest they shared the modern koala's "lazy" lifestyle and ability to produce loud "bellowing" calls to attract mates and provide warnings about predators.

However, the new findings published as the featured cover article in the current issue of The Journal of Vertebrate Paleontology suggest that the two species of koalas from the Miocene (24 to five million years ago) did not share the uniquely specialized eucalyptus leaf diet of the modern koala (Phascolarctos cinereus).

The shift to a wholly eucalyptus diet by modern koalas was an adaptation that probably came later as Australia drifted north, causing its rainforests to retreat and Eucalypts to become the dominant tree of most Australian forests and woodlands.

Modern koalas – the sole living member of the diprotodontian marsupial family Phascolarctidae –are among the largest of all arboreal leaf-eaters. To attain this remarkable condition on a diet of eucalyptus leaves, a notoriously poor and somewhat toxic food source, the tree-dwelling marsupials developed unique anatomical and physiological adaptations including specialized chewing and digestive anatomies and a highly sedentary lifestyle. The dramatic differences between the skulls of extinct and modern koalas, especially in the facial region, are probably related to the change to a tougher diet of eucalyptus leaves.

Researchers from the University of New South Wales and the CSIRO have drawn these conclusions after making dozens of detailed anatomical comparisons between the brush-tailed possum, the modern koala and the two fossil species (Litokoala kutjamarpensis and Nimiokoala greystanesi).

The fossil species were unearthed from the Riversleigh World Heritage site in Queensland, Australia. The comparisons reveal similarities in the back of the skull between the modern and fossil koalas, but substantial differences in their teeth, palate and jaws.

Koalas are most closely related among living marsupials to wombats but the two species diverged some 30-40 million years ago. Among fossil koalas there are 18 named species representing five genera spanning the period from the late Oligocene (37 million years ago) to the present.

However, they are generally scarce in the fossil record and most species are only known from a few isolated teeth or jaw fragments. Therefore, it has been difficult to develop an accurate picture of their behaviour, diet and evolution.

The researchers believe that the prehistoric koalas also shared with their modern cousins the ability to produce loud "bellows" based on similar large bony prominences – the auditory bullae – that enclose structures in the middle and inner ear. However the auditory bullae of the extinct Nimiokoala and Litokoala species are not as exaggerated as in the modern koala, according to team member UNSW Professor Mike Archer.

"Modern koalas are extremely sedentary and vocal animals," says Archer, who is perhaps best known for leading research into the extraordinary Riversleigh fossil deposits in Queensland, which led to the site being listed on the World Heritage Register.

"They produce low frequency vocalisations that pass through vegetation and can be heard up to 800 metres away – far exceeding the home range limits of male koalas. The fossil koalas share similar large bony ear structures to the modern koala and would have been well adapted to detecting vocalisations in the rainforest environment of Riversleigh in the Miocene era."

"In order to accommodate both the mechanical demands of their new diet, as well as maintaining their auditory sophistication, the koala underwent substantial changes to its cranial anatomy, in particular that of the facial skeleton," says Dr Julien Louys of UNSW's School of Biological, Earth and Environmental Sciences. "The unique cranial configuration of the modern koala is therefore the result of accommodating their masticatory adaptations without compromising their auditory system."

University of New South Wales


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A network of ground-based cameras deployed around the Arctic in support of NASA's THEMIS mission has made a startling discovery about the aurora borealis, commonly known as the Northern Lights. Sometimes vast curtains of aurora borealis collide, producing spectacular outbursts of light.

"Our jaws dropped when we saw the movies for the first time," said Larry Lyons, UCLA professor of atmospheric and oceanic sciences and a member of the research team that made the discovery. "These outbursts are telling us something very fundamental about the nature of auroras."

NASA and the Canadian Space Agency created the camera network in the Arctic. THEMIS (Time History of Events and Macroscale Interactions during Substorms) consists of five identical satellite probes launched in 2006 to solve a long-standing mystery: Why do auroras occasionally erupt in an explosion of light known as a substorm? Substorms are dramatic disturbances of the global magnetosphere-ionosphere system that release large amounts of solar wind energy and are associated with auroral activations.

Over the last 40 years, substorms have been studied extensively from the ground and in space. However, the sequence of events during a substorm has remained elusive and been a key subject of debate among scientists who study the physics of the near–Earth space environment.

"Using the array of ground-based imagers of the THEMIS program, we have found what appears to be the answer to this long debate, the answer having similarities to, but also important differences from, previous ideas," Lyons said.

"The initial brightening seems to have started hundreds of miles away from the eventual epicenter of the substorm, and nobody before had managed to put the two together," said Vassilis Angelopoulos, UCLA professor of Earth and space sciences and the principal investigator for THEMIS. "These results unify old and recent observations from the ground and in space in a totally new paradigm of substorm evolution."

Twenty all-sky imagers (ASIs) were deployed across the Alaskan and Canadian Arctic to photograph auroras from below while the spacecraft sampled charged particles and electromagnetic fields from above.

The breakthrough came earlier this year when UCLA researcher Toshi Nishimura assembled continent-wide movies from the individual ASI cameras.

The first movie he showed Lyons was of a pair of auroras crashing together in December 2007.

"It was like nothing I had seen before," Lyons recalled. "Over the next several days, we surveyed more events. Our excitement mounted as we became convinced that the collisions were happening over and over."

The explosions of light, they believe, are a sign of something dramatic happening in the space around Earth — specifically, in the Earth's "plasma tail." Millions of miles long and pointed away from the sun, the plasma tail is made of charged particles captured mainly from the solar wind. Sometimes called the "plasma sheet," the tail is held together by the Earth's magnetic field.

"Collisions of auroras associated with plasma coming from the deep plasma tail, with the aurora coming from the plasma in the nearest portion of the plasma tail, set up an unstable configuration," Lyons said.

The same magnetic field that holds the tail together also connects it to the Earth's polar regions. Because of this connection, watching the dance of the Northern Lights can reveal much about the plasma tail.

Nishimura, Lyons and Angelopoulos, together with Stephen Mende from the University of California, Berkeley, have identified a common sequence of events. It begins with a broad curtain of slow-moving auroras and a smaller knot of fast-moving auroras, initially far apart. The slow curtain quietly hangs in place, almost immobile, while the speedy knot rushes in from the north. The auroras collide, and an eruption of light ensues.

How does this sequence connect to events in the plasma tail? Lyons believes the fast-moving knot is associated with a stream of relatively lightweight plasma jetting through the tail. The stream gets started in the outer regions of the plasma tail and moves rapidly inward toward Earth. The fast knot of auroras moves in sync with this stream.

Meanwhile, the broad curtain of auroras is connected to the stationary inner boundary of the plasma tail and is fueled by plasma instabilities there. When the lightweight stream reaches the inner boundary of the plasma tail, there is an eruption of plasma waves and instabilities. This collision of plasma is mirrored by a collision of auroras over the poles.

National Science Foundation–funded radars located in Poker Flat, Alaska, and Sondrestrom, Greenland, confirm this basic picture. They have detected material rushing through the Earth's upper atmosphere just before the auroras collide and erupt. The five THEMIS spacecraft also agree. They were able to fly through the plasma tail and confirm the existence of lightweight flows rushing toward the Earth last year. In results reported in July 2008 in the journal Science, the THEMIS team identified the mechanism that triggers such plasma streams toward Earth, just prior to onset.

At high northern latitudes in the northern U.S. and Canada, the shimmering bands of light of the aurora borealis stretch across the sky from the east to the west. During geomagnetically disturbed periods known as substorms, the bands brighten. These multicolored light shows are generated when showers of high-speed electrons descend along magnetic field lines to strike the Earth's upper atmosphere.

The THEMIS mission is establishing for the first time when and where substorms begin, determining how the individual components of substorms interact, and discovering how substorms power the aurora borealis.

Catching the substorms as they happen are THEMIS's five satellites — with electric, magnetic, ion and electron detectors — in carefully chosen orbits around the Earth and the array of 20 ground observatories with automated, all-sky cameras located in the northern U.S. and Canada.

As the satellites are measuring the magnetic and electric fields of the plasma above the Earth's atmosphere once every four days, the ground-based observatories are imaging the auroral lights and the electrical currents from space that generate them. THEMIS was launched on Feb. 17, 2007, from Cape Canaveral, Fla.

Themis was the blindfolded Greek goddess of order and justice. In 1619 A.D., Galileo Galilei coined the term "aurora borealis" after Aurora, the Roman goddess of morning. He had the misconception that the auroras he saw were due to sunlight reflecting from the atmosphere.

(Photo: UCLA)



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In the new blockbuster Avatar, humans visit the habitable - and inhabited - alien moon called Pandora. Life-bearing moons like Pandora or the Star Wars forest moon of Endor are a staple of science fiction. With NASA's Kepler mission showing the potential to detect Earth-sized objects, habitable moons may soon become science fact. If we find them nearby, a new paper by Smithsonian astronomer Lisa Kaltenegger shows that the James Webb Space Telescope (JWST) will be able to study their atmospheres and detect key gases like carbon dioxide, oxygen, and water vapor.

"If Pandora existed, we potentially could detect it and study its atmosphere in the next decade," said Lisa Kaltenegger of the Harvard-Smithsonian Center for Astrophysics (CfA).

So far, planet searches have spotted hundreds of Jupiter-sized objects in a range of orbits. Gas giants, while easier to detect, could not serve as homes for life as we know it. However, scientists have speculated whether a rocky moon orbiting a gas giant could be life-friendly, if that planet orbited within the star's habitable zone (the region warm enough for liquid water to exist).

"All of the gas giant planets in our solar system have rocky and icy moons," said Kaltenegger. "That raises the possibility that alien Jupiters will also have moons. Some of those may be Earth-sized and able to hold onto an atmosphere."

Kepler looks for planets that cross in front of their host stars, which creates a mini-eclipse and dims the star by a small but detectable amount. Such a transit lasts only hours and requires exact alignment of star and planet along our line of sight. Kepler will examine thousands of stars to find a few with transiting worlds.

Once they have found an alien Jupiter, astronomers can look for orbiting moons, or exomoons. A moon's gravity would tug on the planet and either speed or slow its transit, depending on whether the moon leads or trails the planet. The resulting transit duration variations would indicate the moon's existence.

Once a moon is found, the next obvious question would be: Does it have an atmosphere? If it does, those gases will absorb a fraction of the star's light during the transit, leaving a tiny, telltale fingerprint to the atmosphere's composition.

The signal is strongest for large worlds with hot, puffy atmospheres, but an Earth-sized moon could be studied if conditions are just right. For example, the separation of moon and planet needs to be large enough that we could catch just the moon in transit, while its planet is off to one side of the star.

Kaltenegger calculated what conditions are best for examining the atmospheres of alien moons. She found that alpha Centauri A, the system featured in Avatar, would be an excellent target.

"Alpha Centauri A is a bright, nearby star very similar to our Sun, so it gives us a strong signal" Kaltenegger explained. "You would only need a handful of transits to find water, oxygen, carbon dioxide, and methane on an Earth-like moon such as Pandora."

"If the Avatar movie is right in its vision, we could characterize that moon with JWST in the near future," she added.

While alpha Centauri A offers tantalizing possibilities, small, dim, red dwarf stars are better targets in the hunt for habitable planets or moons. The habitable zone for a red dwarf is closer to the star, which increases the probability of a transit.

Astronomers have debated whether tidal locking could be a problem for red dwarfs. A planet close enough to be in the habitable zone would also be close enough for the star's gravity to slow it until one side always faces the star. (The same process keeps one side of the Moon always facing Earth.) One side of the planet then would be baked in constant sunlight, while the other side would freeze in constant darkness.

An exomoon in the habitable zone wouldn't face this dilemma. The moon would be tidally locked to its planet, not to the star, and therefore would have regular day-night cycles just like Earth. Its atmosphere would moderate temperatures, and plant life would have a source of energy moon-wide.

"Alien moons orbiting gas giant planets may be more likely to be habitable than tidally locked Earth-sized planets or super-Earths," said Kaltenegger. "We should certainly keep them in mind as we work toward the ultimate goal of finding alien life."

(Photo: David A. Aguilar, CfA)

Harvard-Smithsonian Center for Astrophysics


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Physicists have long theorized the existence of dark matter, arguing that it is a kind of hidden cosmic glue that helps to hold galaxies together. But detecting it has proven extremely difficult because the particles do not absorb or reflect light, and interact very weakly with other particles.

In a presentation at the Fermi National Accelerator Laboratory in Batavia, Ill., scientists from the Cryogenic Dark Matter Search (CDMS) experiment announced the two new potential detections in data taken in 2007 and 2008. However, they cautioned that both events could be the signatures of background particles — other particles with interactions that mimic the signals of dark matter candidates.

“The results of this analysis cannot be interpreted as significant evidence for (dark matter) interactions, but we cannot reject either event,” said Lauren Hsu, a Fermilab CDMS researcher who presented the results.

MIT Assistant Professor of Physics Enectalí Figueroa-Feliciano, a member of CDMS, and his group members have been involved in operating the experiment and analyzing the data.

Caltech researcher Fritz Zwicky first proposed dark matter in the 1930s as a way to explain discrepancies between the inferred mass and the light output of a cluster of galaxies. Other observations also suggest the existence of dark matter. The speed of stars in the outer reaches of spinning galaxies allows astronomers to calculate the amount of mass that must be in those galaxies, according to accepted gravitational theory. However, there isn't enough visible matter in those galaxies to produce the necessary gravitational pull, so physicists theorize that dark matter makes up the difference.

The only alternative would be that there is something wrong with the theory of gravity, as formulated by Isaac Newton and refined by Albert Einstein’s theory of relativity. Some physicists have come up with alternative theories of gravity to explain the discrepancies, but these have not been widely accepted. The detection of dark matter, if confirmed, could solidify the case for the present theory, says Paul Schechter, MIT’s William A. M. Burden Professor of Astrophysics and an observational astronomer who studies galaxies and clusters of galaxies and the distribution of dark matter therein.

“Perhaps the most important thing, if it's correct, is that it exonerates gravity, in particular General Relativity,” says Schechter, who was not a member of the CDMS team. “Until [dark matter] is detected, there is always the possibility that gravity is wrong.”

Many particle physicists believe that dark matter is composed of Weakly Interacting Massive Particles, or WIMPs. These particles are difficult to detect because the likelihood of their interacting with protons and neutrons is very small. However, they may occasionally bounce off an atomic nucleus, leaving a small amount of energy that is detectable under the right conditions.

Those rare interactions can be easily masked by neutron collisions, which occur far more frequently and produce a similar electronic signature. Gamma rays can also produce background interactions. To minimize background, the CDMS experiments are located half a mile underground at the Soudan mine in northern Minnesota.

The CDMS experiment, which has been searching for dark matter since 2003, consists of 30 detectors made of germanium and silicon, cooled to temperatures very near absolute zero. Particle interactions in the crystalline detectors deposit energy as heat and as charges that move in an applied electric field. Special sensors detect these signals, which are then amplified and recorded for later study. By comparing the size and relative timing of these two signals, experimenters can distinguish whether the particle that interacted in the crystal was a WIMP or a background particle.

Due to the size of the data set from 2007 and 2008, five events would be necessary to claim that dark matter had been detected. With only two events found, there is about a one in four chance that these could be background signals. Therefore the CDMS experimenters do not claim to have discovered WIMPs. However, the fact that more possible signals weren’t seen does set upper limits on the mass of dark matter particles, which can already rule out some proposed theories of their nature.

CDMS experimenters, including Figueroa’s group at MIT, are now working on larger detectors, expected to be in place by next summer, that will be able to gather three times as much data in a given time period and thus could produce compelling evidence for dark matter.

MIT Assistant Professor of Physics Jocelyn Monroe, who is involved in two other dark matter detection projects but not CDMS, calls the new data from that experiment “intriguing,” and says this is “probably not a significant or conclusive detection, it’s more like a tantalizing hint.” One of the new detectors, called miniCLEAN and being built in Ontario, Canada, should be able to see somewhere between 20 and 100 events per year if the CDMS detection really was dark matter, she says.

Monroe says that with the upgrade to CDMS, plus three other new experiments under construction, “within the next two or three years we’ll know one way or the other” whether this really was a detection of dark matter. “We won’t have to wait very long.”

(Photo: Fermilab)



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The use and control of fire are behavioral characteristics that distinguish humans from other animals. Now, a new study by Iowa State University anthropologist Jill Pruetz reports that savanna chimpanzees in Senegal have a near human understanding of wildfires and change their behavior in anticipation of the fire's movement.

An ISU associate professor of anthropology, Pruetz and Thomas LaDuke, an associate professor of biological sciences at East Stroudsburg (Pa.) University, co-authored the paper, which will be posted online by the American Journal of Physical Anthropology. It will be published in a 2010 edition of the journal.

Data on the chimps' behavior with seasonal fires was collected by Pruetz during two specific encounters in March and April 2006. She reports that wildfires are set yearly by humans for land clearing and hunting, and most areas within the chimpanzees' home range experience burning to some degree.

The researchers interpret the chimpanzees' behavior to the wildfires as being predictive, rather than responsive, in that they showed no signals of stress or fear -- other than avoiding the fire as it approached them.

"It was the end of the dry season, so the fires burn so hot and burn up trees really fast, and they [the chimps] were so calm about it. They were a lot better than I was, that's for sure," said Pruetz, who was selected a 2008 National Geographic Emerging Explorer for her previous research on the savanna chimpanzees at the Fongoli research site in Senegal.

"They [the chimps] were experts at predicting where it was going to go," she continued. "I could predict it, sort of, but if it were just me, I would have left. At one time, I actually had to push through them because I could feel the heat from the fire that was on the side of me and I just wasn't that comfortable with it."

Pruetz says it was hard to find previous research on how other animals interacted with fire. But the few examples that she and LaDuke found -- such as elephants' encounters with similar wildfires -- reported that those animals were highly stressed and experienced high mortality rates.

In their paper, the researchers wrote that the control of fire by humans involves the acquisition of these three cognitive stages:
1. Conceptualization of fire. An understanding of the behavior under varying conditions that would allow one to predict its movement, thus permitting activity in close proximity to the fire.
2. The ability to control fire. Involving containment, providing or depriving the fire of fuel and perhaps the ability to put it out.
3. The ability to start a fire.

According to Pruetz, the Fongoli chimpanzees have mastered the first stage, which is the prerequisite to the other two. But she doesn't see them figuring out how to start a fire anytime soon -- at least, not without help.

"I think they could learn. It might be difficult only because of their dexterity, since they're less dexterous than us," she said. "But naturally, I can't ever see them making fire. I think cognitively they are able to control it (stage 2)."

Yet they are very aware of fire and its power. In fact, Pruetz reports that the chimps have developed a unique "fire dance."

"Chimps everywhere have what is called a 'rain dance' -- Jane Goodall (a famed primatologist) coined that term -- and it's just a big male display (to show dominance)," she said. "Males display all the time for a number of different reasons, but when there's a big thunderstorm approaching, they do this real exaggerated display -- it's almost like slow motion. And when I was with this one party of chimps, the dominant male did the same sort of thing, but it was towards the fire, so I call it the fire dance.

"The other interesting thing was that I heard a vocalization that I never heard before [the fire dance] and I've never heard since," Pruetz continued.

She says the study provides insight into how the earliest human ancestors first developed the ability to control fire.

"If chimps can understand and predict the movement of fire, then maybe that's the thing that allowed some of the very earliest bipedal apes [human ancestors] to eventually be able to control fire," she said.

Pruetz will be continuing her research in Senegal during the spring semester. It is sponsored, in part, by the National Geographic Society, in addition to Iowa State.

(Photo: Bob Elbert, ISU News Service)

Iowa State University


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A team of researchers at the FOM institute AMOLF has succeeded for the first time in powering an energy transfer between nano-electromagnets with the magnetic field of light. This breakthrough is of major importance in the quest for magnetic 'meta-materials' with which light rays can be deflected in every possible direction.

This could make it possible to produce perfect lenses and, in the fullness of time, even 'invisibility cloaks'. The AMOLF researchers – Ivana Sersic, Martin Frimmer, Ewold Verhagen and Vidi laureate and group leader Femius Koenderink – published their results in the authoritative journal Physical Review Letters.

The artificial 'meta-materials' studied by the researchers consist of very small U-shaped metal 'nano-rings'. The electromagnetic field of light drives charges back and forth, thereby inducing an alternating current in each U shape. The tiny opening at the top of the ring makes sure that the current zooms around at the frequencies of light. In this way, each ring becomes a small but strong electromagnet, with its north and south poles alternating 500 billion times per second.

The researchers made an important discovery by measuring how much light passes through a thick grid of these electromagnets. It appears that when the tiny currents of the rings are actuated by light the nano-magnets also influence each other and can power each other.

The researchers have also shown for the first time that the interaction with the magnetic field of light is very strong in these materials; just as strong as the interaction with the electrical field in the best 'classical' optical materials. This improved understanding of the nano-magnets and their interaction with light gives the researchers all the ingredients they need to disperse light along arbitrary paths.

We are all familiar with rod-shaped magnets: they are described as 'dipolar', with a north pole and a south pole, and the tendency to attract each other’s opposite poles and repel similar poles. We also know that, just like a compass, magnets align themselves along a magnetic field. This is how you can manipulate magnets with magnetic fields, and – vice versa – you can exercise control over magnetic fields using magnets. This commonplace intuition works particularly well for slowly changing magnetic fields, but not for those in a state of rapid flux.

Light is an electromagnetic wave consisting of a very rapidly fluctuating electrical field and an associated magnetic field. In principle, you can direct electromagnetic waves at will by manipulating both the electrical field and the magnetic field. But at the very high frequencies of light (500 THz – 500 billion vibrations per second), atoms scarcely respond to magnetic fields. This is why normal materials only control the electrical field of light and not the magnetic field, and is also why normal optical devices (lenses, mirrors and glass fibres) are handicapped in the way they work. But this type of control is actually possible with these artificial 'meta-materials'.

Netherlands Organisation for Scientific Research


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Scientists funded by the National Science Foundation (NSF) and NOAA have recorded the deepest erupting volcano yet discovered--West Mata Volcano--describing high-definition video of the undersea eruption as "spectacular."

"For the first time we have been able to examine, up close, the way ocean islands and submarine volcanoes are born," said Barbara Ransom, program director in NSF's Division of Ocean Sciences. "The unusual primitive compositions of the West Mata eruption lavas have much to tell us."

The volcanic eruption, discovered in May, is nearly 4,000 feet below the surface of the Pacific Ocean, in an area bounded by Fiji, Tonga and Samoa.

"We found a type of lava never before seen erupting from an active volcano, and for the first time observed molten lava flowing across the deep-ocean seafloor," said the expedition's chief scientist Joseph Resing, a chemical oceanographer at the University of Washington.

"It was an underwater Fourth of July, a spectacular display of fireworks nearly 4,000 feet deep," said co-chief scientist Bob Embley, a marine geologist at NOAA's Pacific Marine Environmental Laboratory in Newport, Ore.

"Since the water pressure at that depth suppresses the violence of the volcano's explosions, we could get an underwater robot within feet of the active eruption. On land, or even in shallow water, you could never hope to get that close and see such great detail."

Imagery includes large molten lava bubbles three feet across bursting into cold seawater, glowing red vents exploding lava into the sea, and the first-observed advance of lava flows across the deep-ocean floor.

Sounds of the eruption were recorded by a hydrophone and later matched with the video footage.

Expedition scientists released the video and discussed their observations at a Dec. 17 news conference at the American Geophysical Union (AGU)'s annual fall meeting in San Francisco.

The West Mata Volcano is producing boninite lavas, believed to be among the hottest on Earth in modern times, and a type seen before only on extinct volcanoes more than one million years old.

University of Hawaii geochemist Ken Rubin believes that the active boninite eruption provides a unique opportunity to study magma formation at volcanoes, and to learn more about how Earth recycles material where one tectonic plate is subducted under another.

Water from the volcano is very acidic, with some samples collected directly above the eruption, the scientists said, as acidic as battery acid or stomach acid.

Julie Huber, a microbiologist at the Marine Biological Laboratory, found diverse microbes even in such extreme conditions.

Tim Shank, a biologist at the Woods Hole Oceanographic Institution (WHOI), found that shrimp were the only animals thriving in the acidic vent water near the eruption. Shank is analyzing shrimp DNA to determine whether they are the same species as those found at seamounts more than 3,000 miles away.

The scientists believe that 80 percent of eruptive activity on Earth takes place in the ocean, and that most volcanoes are in the deep sea.

Further study of active deep-ocean eruptions will provide a better understanding of oceanic cycles of carbon dioxide and sulfur gases, how heat and matter are transferred from the interior of the Earth to its surface, and how life adapts to some of the harshest conditions on Earth.

The science team worked aboard the University of Washington's research vessel Thomas Thompson, and deployed Jason, a remotely-operated vehicle owned by WHOI.

Jason collected samples using its manipulator arms, and obtained imagery using a prototype still and HD imaging system developed and operated by the Advanced Imaging and Visualization Lab at WHOI.

(Photo: NSF/NOAA)

National Science Foundation


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Landing is tricky: hit the ground too fast and you will crash and burn; too slow and you may stall and fall. Bees manage their approach by monitoring the speed of images moving across their eyes. By slowing so that the speed of the looming landing pad's image on the retina remains constant, bees manage to control their approach.

But what happens in the final few moments before touch down? And how do bees adapt to landing on surfaces ranging from the horizontal to upside-down ceilings? Flies land on a ceiling by simply grabbing hold with their front legs and somersaulting up as they zip along, but a bee's approach is more sedate. Mandyam Srinivasan, an electrical engineer from the Queensland Brain Institute, The University of Queensland and the Australian Research Council's Vision Centre, knew that bees must be doing something different from daredevil flies. Curious to know more about bee landing strategies Srinivasan teamed up with Carla Evangelista, Peter Kraft, and Judith Reinhard from the University of Queensland, and Marie Dacke, visiting from Lund University. The team used a high-speed camera to film the instant of touch down on surfaces at various inclinations and publish their discoveries about bee landing tactics in The Journal of Experimental Biology on December 28 2009 at

First the scientists built a bee-landing platform that could be inclined at any angle from horizontal to inverted (like a ceiling), then they trained bees to land on it and began filming. Having collected movies of the bees landing on surfaces ranging from 0deg. to 180deg., and every 10deg. inclination between, Evangelista began the painstaking task of manually analysing the bees landing strategies, and saw that the bees' approach could be broken down into 3 phases.

Initially the bees approached from almost any direction and at any speed, however, as they got closer to the platforms, they slowed dramatically, almost hovering, until they were 16mm from the platform when they ground to a complete halt, hovering for anything ranging from 50ms to over 140ms. When the surface was horizontal or inclined slightly, the bees' hind legs were almost within touching distance of the surface, so it was simply a matter of the bee gently lowering itself and grabbing hold with its rear feet before lowering the rest of the body.

However, when the insects were landing on surfaces ranging from vertical to 'ceilings', their antennae were closest to the surface during the hover phase. The team saw that the antennae grazed the surface and this contact triggered the bees to reach up with the front legs, grasp hold of the surface and then slowly heave their middle and hind legs up too. 'We had not expected the antennae to play a role and the fact that there is a mechanical aspect of this is something that we hadn't thought about,' admits Srinivasan.

Looking at the antennae's positions, the team realised that in the final stages as the insects approached inverted surfaces, they held their antennae roughly perpendicular to the surface. 'The bee is able to estimate the slope of the surface to orient correctly the antennae, so it is using its visual system,' explains Srinivasan. But this is surprising, because the insects are almost completely stationary while hovering and unable to use image movement across the eye to estimate distances. Srinivasan suspects that the bees could be using stereovision over such a short distance, and is keen to test the idea.

Finally the team realised that bees are almost tailor made to land on surfaces inclined at angles of 60deg. to the horizontal. 'When bees are flying fast their bodies are horizontal, but when they are flying slowly or hovering their abdomen tilts down so that the tips of the legs and antennae lie in a plane that makes an angle of 60deg.' explains Srinivasan: so the legs and antennae all touch down simultaneously on surfaces inclined at 60deg. 'It seems like they are adapted to land on surfaces tilted to 60deg. and we are keen to find out whether many flowers have this natural tilt,' says Srinivasan.

Srinivasan is optimistic that he will eventually be able to use his discoveries in the design of novel flight control systems.

The Company of Biologists Limited


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The brain acts as a profound regulatory centre, controlling myriad processes throughout the body in ways we are only just beginning to understand. In new findings, Australian scientists have shown surprising connections between the brain and regulation of bone mass.

One of the key functions of our skeletons is to provide mechanical support. In order to fulfil this role, bone tissue is modified throughout our lives, in response to changing activity levels and body weight. Bone mass increases as we gain weight and decreases as we lose it.

The new findings show that bone formation, far from being a straightforward mechanical process dependent on body weight, is delicately orchestrated by the brain, which sends and receives signals through the body’s neural and hormone systems.

It is now clear that the neural network which controls appetite and energy also alters bone density. When we are starving, our brains don’t allow us to waste energy by reproducing, making fat or creating new bone. When we are eating too much, on the other hand, our brains make it easier to reproduce, store fat and create bone.

Dr Paul Baldock, a neuroscientist from Sydney’s Garvan Institute of Medical Research, has demonstrated in mice that the neurotransmitter Neuropeptide Y (NPY) directly controls osteoblasts, the cells that make bone. His findings are published today in the international online journal Public Library of Science ONE (PLoS ONE).

“It has always been thought that changes in bone mass are purely mechanical - you get heavier and your bones get denser to support the increased load,” said Baldock.

“While that’s true to some extent, our findings show a sophisticated central surveillance system at work. It’s as if the brain, as boss, sends out a global memo saying ‘make more bone’.”

“Bone-making cells at local level appear to have the ability to fine-tune this directive, like office workers saying ‘we’re not going to waste time putting on bone here when it’s needed more over there’.”

“So what happens in practice is that places exposed to more load put on more bone, while those exposed to less load put on less bone.”

All the intricate central processing takes place in the hypothalamus, a small yet complex region of the brain that links the nervous and hormone systems.

According to Baldock, the NPY system in the brain evolved to allow survival of humans during very lean times as well as plenty. “In evolutionary terms, people are kept alive so that they can reproduce, and body systems are all integrated to preserve that function.”

“I have no doubt that osteoporosis treatments of the future will find a safe way to block NPY receptors on osteoblasts,” said Baldock.

“Obviously, the development of such treatments would have to take account of all the processes affected by the NPY system – including appetite and mood. You’d need something that increased bone mass without also making people fat, skinny, sad or angry at the same time.”

As a first step, Baldock is showing the orthopaedic relevance of his findings at the Children’s hospital at Westmead, where he is collaborating with an orthopaedic surgeon, Associate Professor David Little.

(Photo: Garvan I.)

Garvan Institute of Medical Research


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Sandia National Laboratories scientists have developed tiny glitter-sized photovoltaic cells that could revolutionize the way solar energy is collected and used.

The tiny cells could turn a person into a walking solar battery charger if they were fastened to flexible substrates molded around unusual shapes, such as clothing.

The solar particles, fabricated of crystalline silicon, hold the potential for a variety of new applications. They are expected eventually to be less expensive and have greater efficiencies than current photovoltaic collectors that are pieced together with 6-inch- square solar wafers.

The cells are fabricated using microelectronic and microelectromechanical systems (MEMS) techniques common to today’s electronic foundries.

Sandia lead investigator Greg Nielson said the research team has identified more than 20 benefits of scale for its microphotovoltaic cells. These include new applications, improved performance, potential for reduced costs and higher efficiencies.

“Eventually units could be mass-produced and wrapped around unusual shapes for building-integrated solar, tents and maybe even clothing,” he said. This would make it possible for hunters, hikers or military personnel in the field to recharge batteries for phones, cameras and other electronic devices as they walk or rest.

Even better, such microengineered panels could have circuits imprinted that would help perform other functions customarily left to large-scale construction with its attendant need for field construction design and permits.

Said Sandia field engineer Vipin Gupta, “Photovoltaic modules made from these microsized cells for the rooftops of homes and warehouses could have intelligent controls, inverters and even storage built in at the chip level. Such an integrated module could greatly simplify the cumbersome design, bid, permit and grid integration process that our solar technical assistance teams see in the field all the time.”

For large-scale power generation, said Sandia researcher Murat Okandan, “One of the biggest scale benefits is a significant reduction in manufacturing and installation costs compared with current PV techniques.”

Part of the potential cost reduction comes about because microcells require relatively little material to form well-controlled and highly efficient devices.

From 14 to 20 micrometers thick (a human hair is approximately 70 micrometers thick), they are 10 times thinner than conventional 6-inch-by-6-inch brick-sized cells, yet perform at about the same efficiency.

“So they use 100 times less silicon to generate the same amount of electricity,” said Okandan. “Since they are much smaller and have fewer mechanical deformations for a given environment than the conventional cells, they may also be more reliable over the long term.”

Another manufacturing convenience is that the cells, because they are only hundreds of micrometers in diameter, can be fabricated from commercial wafers of any size, including today’s 300-millimeter (12-inch) diameter wafers and future 450-millimeter (18-inch) wafers. Further, if one cell proves defective in manufacture, the rest still can be harvested, while if a brick-sized unit goes bad, the entire wafer may be unusable. Also, brick-sized units fabricated larger than the conventional 6-inch-by-6-inch cross section to take advantage of larger wafer size would require thicker power lines to harvest the increased power, creating more cost and possibly shading the wafer. That problem does not exist with the small-cell approach and its individualized wiring.

Other unique features are available because the cells are so small. “The shade tolerance of our units to overhead obstructions is better than conventional PV panels,” said Nielson, “because portions of our units not in shade will keep sending out electricity where a partially shaded conventional panel may turn off entirely.”

Because flexible substrates can be easily fabricated, high-efficiency PV for ubiquitous solar power becomes more feasible, said Okandan.

A commercial move to microscale PV cells would be a dramatic change from conventional silicon PV modules composed of arrays of 6-inch-by-6-inch wafers. However, by bringing in techniques normally used in MEMS, electronics and the light-emitting diode (LED) industries (for additional work involving gallium arsenide instead of silicon), the change to small cells should be relatively straightforward, Gupta said.

Each cell is formed on silicon wafers, etched and then released inexpensively in hexagonal shapes, with electrical contacts prefabricated on each piece, by borrowing techniques from integrated circuits and MEMS.

Offering a run for their money to conventional large wafers of crystalline silicon, electricity presently can be harvested from the Sandia-created cells with 14.9 percent efficiency. Off-the-shelf commercial modules range from 13 to 20 percent efficient.

A widely used commercial tool called a pick-and-place machine — the current standard for the mass assembly of electronics — can place up to 130,000 pieces of glitter per hour at electrical contact points preestablished on the substrate; the placement takes place at cooler temperatures. The cost is approximately one-tenth of a cent per piece with the number of cells per module determined by the level of optical concentration and the size of the die, likely to be in the 10,000 to 50,000 cell per square meter range. An alternate technology, still at the lab-bench stage, involves self-assembly of the parts at even lower costs.

Solar concentrators — low-cost, prefabricated, optically efficient microlens arrays — can be placed directly over each glitter-sized cell to increase the number of photons arriving to be converted via the photovoltaic effect into electrons. The small cell size means that cheaper and more efficient short focal length microlens arrays can be fabricated for this purpose.

High-voltage output is possible directly from the modules because of the large number of cells in the array. This should reduce costs associated with wiring, due to reduced resistive losses at higher voltages.

Other possible applications for the technology include satellites and remote sensing.

(Photo: Murat Okandan)


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Researchers at the University of Chicago are studying communication in animals to improve their understanding of how language develops in humans and how they use it.

“We find compelling evidence that language is a phenomenon of evolutionary biology and within the reach of biological investigation,” write biologist Daniel Margoliash and psychologist Howard Nusbaum in “Language: The Perspective from Organismal Biology,” an opinion piece in the current issue of the journal Trends in Cognitive Sciences.

The two researchers challenge the position held by other scholars, including language theorist Noam Chomsky, that the way people develop language is uniquely human and unrelated to communication systems in other animals. In that theory, the ability to speak is contained in a “black box” in the brain and can be opened by informal contact as a baby begins recognizing sounds or a toddler begins speaking.

Recent research, including studies at the University on songbirds, questions that position and argues for inclusion of evolutionary biology as a means of learning more about how language develops. Songbirds also show a human-like capacity to learn complex vocal patterns, the researchers have found.

“This will help us understand the black box of language better,” said Margoliash, Professor in Organismal Biology and Anatomy, who has studied song development in birds.

“If we’re going to make progress understanding how language develops, we need to look at all the evidence, and that includes what we can learn from biology,” said Howard Nusbaum, Chair of Psychology and an expert on speech development.

Researchers have long studied vocal communication in animals, including birds, whales, porpoises, and non-human primates. Those patterns provide a way of understanding how human language develops if subjected to the right research program, the two Chicago scholars said.

“Animals have more intelligence than most people give them credit for. Crows are capable of developing tools, for instance. Jays have a sense of mental time travel. The problem is that we haven’t had a way to measure that intelligence,” Margoliash said.

The evidence that connects human and animal communication has provided conflicting conclusions. Scientists have not agreed on how communication abilities moved through evolution on their way to the human.

Some studies with non-human primates, the close relatives of humans, suggest that there may be no connections at all. Work by Margoliash and Nusbaum shows that starlings are capable of abstract learning of vocal structures.

A biological feature in starlings, a large well-defined forebrain substantially devoted to vocal learning, could account for their ability to learn complex vocal tasks, Margoliash said. In contrast, the monkeys that failed to learn the task are not vocal learners. But that experiment was in fact helpful, because it suggested such studies could be done, and it led Nusbaum and Margoliash to their work with starlings.

A new research horizon is opening up, as scholars go beyond considering human language and behavior to be uniquely human and embrace biological approaches, the authors conclude.

University of Chicago


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Scientists at UC Santa Barbara, in collaboration with scientists at University of Michigan, have developed synthetic particles that closely mimic the characteristics and key functions of natural red blood cells, including softness, flexibility, and the ability to carry oxygen.

The primary function of natural red blood cells is to carry oxygen, and the synthetic red blood cells (sRBCs) do that very well, retaining 90% of their oxygen-binding capacity after a week. The sRBCs also, however, have been shown to deliver therapeutic drugs effectively and with controlled release, and to carry well-distributed contrast agents for enhanced resolution in diagnostic imaging.

"This ability to create flexible biomimetic carriers for therapeutic and diagnostic agents really opens up a whole new realm of possibilities in drug delivery and similar applications," noted UCSB chemical engineering professor Samir Mitragotri. "We know that we can further engineer sRBCs to carry additional therapeutic agents, both encapsulated in the sRBC and on its surface."

Mitragotri, his research group, and their collaborators from the University of Michigan succeeded in synthesizing the particles by creating a polymer doughnut-shaped template, coating the template with up to nine layers of hemoglobin and other proteins, then removing the core template. The resulting particles have the same size and flexibility, and can carry as much oxygen, as natural red blood cells. The flexibility, absent in "conventional" polymer-based biomaterials developed as carriers for therapeutic and diagnostic agents, gives the sRBCs the ability to flow through channels smaller than their resting diameter, stretching in response to flow and regaining their discoidal shape upon exiting the capillary, just as their natural counterparts do.

In addition to synthesizing particles that mimic the shape and properties of healthy RBCs, the technique described in the paper can also be used to develop particles that mimic the shape and properties of diseased cells, such as those found in sickle-cell anemia and hereditary eliptocytosis. The availability of such synthetic diseased cells is expected to lead to greater understanding of how those diseases and others affect RBCs.

The discovery is described in the current online edition of Proceedings of the National Academy of Science, and will be published in the print version of the journal in the near future. UCSB graduate student Nishti Doshi was the lead author of the paper; former post-doctoral researcher Alisar Zahr (now at Harvard Medical School's Schepens Eye Research Institute), Mitragotri, and their University of Michigan collaborators Srijanani Bhaskar and professor Joerg Lahann were co-authors.

(Photo: UCSB)

University of California, Santa Barbara


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Evidence of sophisticated, human behavior has been discovered by Hebrew University of Jerusalem researchers as early as 750,000 years ago – some half a million years earlier than has previously been estimated by archaeologists.

The discovery was made in the course of excavations at the prehistoric Gesher Benot Ya'aqov site, located along the Dead Sea rift in the southern Hula Valley of northern Israel, by a team from the Hebrew University Institute of Archaeology. Analysis of the spatial distribution of the findings there reveals a pattern of specific areas in which various activities were carried out. This kind of designation indicates a formalized conceptualization of living space, requiring social organization and communication between group members. Such organizational skills are thought to be unique to modern humans.

Attempts until now to trace the origins of such behavior at various prehistoric sites in the world have concentrated on spatial analyses of Middle Paleolithic sites, where activity areas, particularly those associated with hearths, have been found dating back only to some 250,000 years ago.

The new Hebrew University study, a report on which is published this week in Science magazine, describes an Acheulian (an early stone tools culture) layer at Gesher Benot Ya'aqov that has been dated to about 750,000 years ago. The evidence found there consists of numerous stone tools, animal bones and a rich collection of botanical remains.

Analyses of the spatial distribution of all these finds revealed two activity areas in the layer: the first area is characterized by abundant evidence of flint tool manufacturing. A high density of fish remains in this area also suggests that the processing and consumption of many fish were carried out in this area -- one of the earliest evidences for fish consumption by prehistoric people anywhere.

In the second area, identified evidence indicates a greater variation of activities – all of which took place in the vicinity of a hearth. The many wood pieces found in this area were used as fuel for the fire. Processing of basalt and limestone was spatially restricted to the hearth area, where activities indicate the use of large stone tools such as hand axes, chopping tools, scrapers, and awls. The presence of stone hammers, and in particular of pitted anvils (used as nutting stones), suggest that nut processing was carried out near the hearth and may have involved the use of nut roasting. In addition, fish and crabs were probably consumed near the hearth.

(Photo: Gonen Sharon for the Hebrew University of Jerusalem)

Georgia Institute of Technology


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A group of University of Kansas researchers working with Chinese colleagues have discovered a venomous, birdlike raptor that thrived some 128 million years ago in China. This is the first report of venom in the lineage that leads to modern birds.

"This thing is a venomous bird for all intents and purposes," said Larry Martin, KU professor and curator of vertebrate paleontology at the Natural History Museum and Biodiversity Institute. "It was a real shock to us and we made a special trip to China to work on this."

The KU-China team's findings will be published in the early edition of the Proceedings of the National Academy of Sciences during the week of Dec. 21.

"We think it's going to make a big splash," said Martin.

The article's authors are Enpu Gong, geology department at Northeastern University in Shenyang, China, and researchers Martin, David Burnham and Amanda Falk at the KU Natural History Museum and Biodiversity Institute.

The dromaeosaur or raptor, Sinornithosaurus (Chinese-bird-lizard), is a close relative to Velociraptor. It lived in prehistoric forests of northeastern China that were filled with a diverse assemblage of animals including other primitive birds and dinosaurs.

"This is an animal about the size of a turkey," said Martin. "It's a specialized predator of small dinosaurs and birds. It was almost certainly feathered. It's a very close relative of the four-winged glider called Microraptor."

The venom most likely sent the victim into rapid shock, shrinking the odds of retaliation, escape or piracy from other predators while the raptor manipulated its prey.

"You wouldn't have seen it coming," said Burnham. "It would have swooped down behind you from a low-hanging tree branch and attacked from the back. It wanted to get its jaws around you. Once the teeth were embedded in your skin the venom could seep into the wound. The prey would rapidly go into shock, but it would still be living, and it might have seen itself being slowly devoured by this raptor."

The genus had special depressions on the side of its face thought by the investigators to have housed a poison gland, connected by a long lateral depression above the tooth row that delivered venom to a series of long, grooved teeth on the upper jaw. This arrangement is similar to the venom-delivery system in modern rear-fanged snakes and lizards. The researchers believe it to be specialized for predation on birds.

"When we were looking at Sinornithosaurus, we realized that its teeth were unusual, and then we began to look at the whole structure of the teeth and jaw, and at that point, we realized it was similar to modern-day snakes," Martin said.

Sinornithosaurus is represented by at least two species. These specimens have features consistent with a primitive venom-delivery system. The KU-China research team said it was a low-pressure system similar to the modern Beaded lizard, Heloderma, however the prehistoric Sinornithosaurus had longer teeth to break through layers of feathers on its bird victims.

The discovery of features thought to be associated with a venom-delivery system in Sinornithosaurus stemmed from a study of the anatomy and ecology of Microraptor by the joint Chinese-KU team. They now are seeking to discover if Microraptor may have possessed a similar poison-delivery system.

(Photo: Robert DePalma/KU)

The University of Kansas


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The Egyptians supposedly used it to guide the construction the Pyramids. The architecture of ancient Athens is thought to have been based on it. Fictional Harvard symbologist Robert Langdon tried to unravel its mysteries in the novel The Da Vinci Code.

"It" is the golden ratio, a geometric proportion that has been theorized to be the most aesthetically pleasing to the eye and has been the root of countless mysteries over the centuries. Now, a Duke University engineer has found it to be a compelling springboard to unify vision, thought and movement under a single law of nature's design.

Also know the divine proportion, the golden ratio describes a rectangle with a length roughly one and a half times its width. Many artists and architects have fashioned their works around this proportion. For example, the Parthenon in Athens and Leonardo da Vinci's painting Mona Lisa are commonly cited examples of the ratio.

Adrian Bejan, professor of mechanical engineering at Duke's Pratt School of Engineering, thinks he knows why the golden ratio pops up everywhere: the eyes scan an image the fastest when it is shaped as a golden-ratio rectangle.

The natural design that connects vision and cognition is a theory that flowing systems -- from airways in the lungs to the formation of river deltas -- evolve in time so that they flow more and more easily. Bejan termed this the constructal law in 1996, and its latest application appears early online in the International Journal of Design & Nature and Ecodynamics.

"When you look at what so many people have been drawing and building, you see these proportions everywhere," Bejan said. "It is well known that the eyes take in information more efficiently when they scan side-to-side, as opposed to up and down."

Bejan argues that the world – whether it is a human looking at a painting or a gazelle on the open plain scanning the horizon – is basically oriented on the horizontal. For the gazelle, danger primarily comes from the sides or from behind, not from above or below, so their scope of vision evolved to go side-to-side. As vision developed, he argues, the animals got "smarter" by seeing better and moving faster and more safely.

"As animals developed organs for vision, they minimized the danger from ahead and the sides," Bejan said. "This has made the overall flow of animals on earth safer and more efficient. The flow of animal mass develops for itself flow channels that are efficient and conducive to survival – straighter, with fewer obstacles and predators."

For Bejan, vision and cognition evolved together and are one and the same design as locomotion. The increased efficiency of information flowing from the world through the eyes to the brain corresponds with the transmission of this information through the branching architecture of nerves and the brain.

"Cognition is the name of the constructal evolution of the brain's architecture, every minute and every moment," Bejan said. "This is the phenomenon of thinking, knowing, and then thinking again more efficiently. Getting smarter is the constructal law in action."

While the golden ratio provided a conceptual entryway into this view of nature's design, Bejan sees something even broader.

"It is the oneness of vision, cognition and locomotion as the design of the movement of all animals on earth," he said. "The phenomenon of the golden ratio contributes to this understanding the idea that pattern and diversity coexist as integral and necessary features of the evolutionary design of nature."

(Photo: Duke University)

Duke University




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