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Friday, May 31, 2013

NASA Radar Reveals Asteroid Has Its Own Moon

A sequence of radar images of asteroid 1998 QE2 was obtained on the evening of May 29, 2013, by NASA scientists using the 230-foot (70-meter) Deep Space Network antenna at Goldstone, Calif., when the asteroid was about 3.75 million miles (6 million kilometers) from Earth, which is 15.6 lunar distances.

Radar data of asteroid 1998 QE2 obtained on May 29, 2013. The small moving white dot is the moon, or satellite, orbiting asteroid 1998 QE2.
Credit: NASA/JPL

The radar imagery revealed that 1998 QE2 is a binary asteroid. In the near-Earth population, about 16 percent of asteroids that are about 655 feet (200 meters) or larger are binary or triple systems. Radar images suggest that the main body, or primary, is approximately 1.7 miles (2.7 kilometers) in diameter and has a rotation period of less than four hours. Also revealed in the radar imagery of 1998 QE2 are several dark surface features that suggest large concavities. The preliminary estimate for the size of the asteroid's satellite, or moon, is approximately 2,000 feet (600 meters) wide. The radar collage covers a little bit more than two hours.

First radar images of asteroid 1998 QE2 were obtained when the asteroid was about 3.75 million miles (6 million kilometers) from Earth. The small white dot at lower right is the moon, or satellite, orbiting asteroid 1998 QE2. 

Image credit: NASA/JPL-Caltech/GSSR

The radar observations were led by scientist Marina Brozovic of NASA's Jet Propulsion Laboratory, Pasadena, Calif.

The closest approach of the asteroid occurs on May 31 at 1:59 p.m. Pacific (4:59 p.m. Eastern / 20:59 UTC), when the asteroid will get no closer than about 3.6 million miles (5.8 million kilometers), or about 15 times the distance between Earth and the moon. This is the closest approach the asteroid will make to Earth for at least the next two centuries. Asteroid 1998 QE2 was discovered on Aug. 19, 1998, by the Massachusetts Institute of Technology Lincoln Near Earth Asteroid Research (LINEAR) program near Socorro, N.M.

The resolution of these initial images of 1998 QE2 is approximately 250 feet (75 meters) per pixel. Resolution is expected to increase in the coming days as more data become available. Between May 30 and June 9, radar astronomers using NASA's 230-foot-wide (70 meter) Deep Space Network antenna at Goldstone, Calif., and the Arecibo Observatory in Puerto Rico, will perform an extensive campaign of observations on asteroid 1998 QE2. The two telescopes have complementary imaging capabilities that will enable astronomers to learn as much as possible about the asteroid during its brief visit near Earth.

Radar is a powerful technique for studying an asteroid's size, shape, rotation state, surface features and surface roughness, and for improving the calculation of asteroid orbits. Radar measurements of asteroid distances and velocities often enable computation of asteroid orbits much further into the future than if radar observations weren't available.

NASA places a high priority on tracking asteroids and protecting our home planet from them. In fact, the United States has the most robust and productive survey and detection program for discovering near-Earth objects. To date, U.S. assets have discovered more than 98 percent of the known Near-Earth Objects.

When Asteroid 1998 QE2 makes its closest approach to Earth on May 31, 2013, it promises to be a bonanza for radar science.
Credit; NASA

In 2012, the Near-Earth Object budget was increased from $6 million to $20 million. Literally dozens of people are involved with some aspect of near-Earth object research across NASA and its centers. Moreover, there are many more people involved in researching and understanding the nature of asteroids and comets, including those objects that come close to Earth, plus those who are trying to find and track them in the first place.

In addition to the resources NASA puts into understanding asteroids, it also partners with other U.S. government agencies, university-based astronomers, and space science institutes across the country that are working to track and better understand these objects, often with grants, interagency transfers and other contracts from NASA.

NASA's Near-Earth Object Program at NASA Headquarters, Washington, manages and funds the search, study, and monitoring of asteroids and comets whose orbits periodically bring them close to Earth. JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena.

In 2016, NASA will launch a robotic probe to one of the most potentially hazardous of the known Near-Earth Objects. The OSIRIS-REx mission to asteroid (101955) Bennu will be a pathfinder for future spacecraft designed to perform reconnaissance on any newly-discovered threatening objects. Aside from monitoring potential threats, the study of asteroids and comets enables a valuable opportunity to learn more about the origins of our solar system, the source of water on Earth, and even the origin of organic molecules that lead to the development of life.

NASA recently announced development of a first-ever mission to identify, capture and relocate an asteroid for human exploration. Using game-changing technologies this mission would mark an unprecedented technological achievement that raises the bar of what humans can do in space. Capturing and redirecting an asteroid will integrate the best of NASA's science, technology and human exploration capabilities and draw on the innovation of America's brightest scientists and engineers.

More information about asteroids and near-Earth objects is available at: http://neo.jpl.nasa.gov/ ,http://www.jpl.nasa.gov/asteroidwatch and via Twitter at http://www.twitter.com/asteroidwatch .

More information about asteroid radar research is at: http://echo.jpl.nasa.gov/

More information about the Deep Space Network is at: http://deepspace.jpl.nasa.gov/dsn .


Contacts and sources:
DC Agle
Jet Propulsion Laboratory



Hubble Sees the Messy Result of a Galactic Collision

This new image from the NASA/ESA Hubble Space Telescope captures an ongoing cosmic collision between two galaxies — a spiral galaxy is in the process of colliding with a lenticular galaxy. The collision looks almost as if it is popping out of the screen in 3-D, with parts of the spiral arms clearly embracing the lenticular galaxy’s bulge.
an off-center spiral galaxy appears to radiate a blur of stars through its axis and another, dimmer ray at 20 degrees off the axis.
Credit: Credit: ESA/Hubble & NASA, Acknowledgement: Luca Limatola

The image also reveals further evidence of the collision. There is a bright stream of stars coming out from the merging galaxies, extending out towards the top of the image. The bright spot in the middle of the plume, known as ESO 576-69, is what makes this image unique. This spot is believed to be the nucleus of the former spiral galaxy, which was ejected from the system during the collision and is now being shredded by tidal forces to produce the visible stellar stream.


Contacts and sources:
European Space Agency/NASA Hubble

The Scoop On Bird Poop

Gut bacteria are known to have a central role both in human and in animal health. Animals acquire different bacteria as they age but how the microbial communities in the bodies of wild animals change over time is not well understood. Wouter van Dongen and colleagues at the Vetmeduni Vienna have examined the gastrointestinal bacteria of chick and adult black-legged kittiwakes. Surprisingly, the microbial assemblages of chicks and adults generally differ greatly, with only a few types of bacteria in common. The findings have recently been published in the journal BMC Ecology.

The black-legged Kittiwake and chicks (Rissa tridactyla)  
Photo: Joel White

Gastrointestinal bacteria are important for digestion, immune functions and general health. Wouter van Dongen and colleagues from the Konrad Lorenz Institute of Ethology of the Vetmeduni Vienna have collaborated with scientists from the Laboratoire Évolution & Diversité Biologique (EDB), Toulouse and from the US Geological Survey, Anchorage to study the cloacal bacterial assemblies of black-legged kittiwakes (Rissa tridactyla). The bacteria in the cloaca are known to be similar to assemblages deeper within the gastrointestinal tract, so the researchers examined samples from the cloaca of birds at different ages to look indirectly at gut bacteria.

Flushing bacteria

To obtain bacterial samples, the researchers ”flushed” the birds’ cloacae by gently infusing a salt solution into the cloacae and collecting the liquid. The bacterial diversity in the cloaca of each bird could be estimated with the aid of molecular genetic techniques. The scientists were able to identify different bacterial assemblages and thus to draw a clear picture of how bacterial communities in bird guts change as the birds age.
From a youthful hodgepodge to a stable community

There turned out to be a great variety of bacterial species in the guts of kittiwake chicks but the assortment in the adults was much less diverse. Astonishingly, the sampled chicks and adults had only seven out of a total of 64 bacteria species in common and some of the bacteria that were very common in adults were not present in chicks at all. Wouter van Dongen says, “We were very surprised to find that the bacteria in chick gastrointestinal tracts are so different from those in adults. Given that chicks share the nest with their parents and eat food that is regurgitated by the parents, we expected the level of bacterial sharing to be a lot higher.” The scientists´ findings suggest that young birds are susceptible to many species of bacteria that pass through their gut. As the animals mature, the number of bacterial species decreases. Particular groups of bacteria that stay ultimately form a stable community.

A number of causes

It is known from other studies that the composition of gastrointestinal microbes changes according to the age of the host. The differences may correlate with changes in the birds´ gut chemistry over time or with changes in diet or may result from competition between bacterial species. A more developed immune system in adults and the lack of mobility of the young could also play a part. Further studies are needed to determine the causes and consequences of the variation in the bacterial assemblages in guts of wild birds.

The article “Age-related differences in the cloacal microbiota of a wild bird species“ by Wouter van Dongen, Joël White, Hanja Brandl, Yoshan Moodley, Thomas Merkling, Sarah Leclaire, Pierrick Blanchard, Étienne Danchin, Scott Hatch and Richard Wagner appeared on March 25 2013 in the journal BMC Ecology 2013, 13:11 doi:10.1186/1472-6785-13-11.



Contacts and sources:
Dr. Wouter van Dongen
University of Veterinary Medicine -- Vienna

Efficient And Long-Lived Storage Of Information In Magnetic Vortices: Magnetic Monopoles Erase Data

A physical particle postulated 80 years ago, could provide a decisive step toward the realization of novel, highly efficient data storage devices. Scientists at the Technische Universitaet Muenchen (TUM), the Technische Universitaet Dresden and the University of Cologne found that with magnetic monopoles in magnetic vortices, called skyrmions, information can be written and erased.

A grid of magnetic vortex structures 
Picture: TUM

Iron filings strewn on a sheet of paper trace the field lines of a bar magnet below the paper, thereby showing the magnet's north and south poles. No matter how often it is split, the bar magnet always forms a north and a south pole. However, in the early 1930s physicist Paul A. M. Dirac postulated a particle that should, as the magnetic counterpart of the electron, possess only one of the two poles, and should carry just one magnetic elementary charge.

Looking for a simple way to study the magnetic vortices, researchers associated with TUM physicist Prof. Christian Pfleiderer collaborated with Prof. Lukas Eng's group at the Technische Universitaet Dresden, which has a magnetic force microscope. When they scanned the surface of the materials with this microscope, they not only observed the vortices for the first time, but also found that neighboring skyrmions merge with one another.

Computer simulations of Prof. Achim Rosch's group at Cologne, together with experiments at the research neutron source FRM II at TUM, showed that magnetic monopoles were at work here, drawing the vortices together like a zipper.

Compact and long-lived data storage

An important future application of the magnetic eddies could be extremely compact and long-lived storage media. Whereas one needs around a million atoms to store one bit in a modern hard disk, the smallest known skyrmions in magnetic materials consist of only 15 atoms.

Depiction of the merging of two magnetic vortices, so-called skyrmions, in the magnetic structure of a material. The point at the which the vortices merge displays the properties of an emergent magnetic monopole. When the monopole moves along the direction of the vortices a skyrmion is created or destroyed 
Picture: Ch. Schütte/University of Cologne

At the same time moving such skyrmions requires 100,000 times less power than moving memory bits in devices based on conventional magnetic materials, in order to process information such a precisely controlled manner. Perhaps the most interesting characteristic of skyrmions, however, is that they are especially stable, like a knot in a string.

The magnetic vortex structures were discovered in 2009 through neutron scattering experiments on manganese-silicon in the research neutron source FRM II, conducted by a team around Christian Pfleiderer and Achim Rosch. Since then this area of research has attracted intense interest and made rapid progress worldwide. "Whereas initially the experiments required extremely low temperatures, today we also know materials in which skyrmions exist at room temperature," says Christian Pfleiderer, Professor for Magnetic Materials at the Technische Universitaet Muenchen.

"With the magnetic force microscopy, we finally have a method at hand that allows us for the first time to observe skyrmions in systems that are relevant for applications. This is a decisive step in the direction of a real technical use."

The work was funded by the European Research Council, the German Research Foundation, (DFG), and the Australian Research Council, as well as the TUM Graduate School and the Bonn-Cologne Graduate School.


Contacts and sources:
Patrick Regan
Technische Universitaet Muenchen

Citation: Unwinding of a Skyrmion Lattice by Magnetic Monopoles, 
P. Milde, D. Köhler, J. Seidel, L. M. Eng, A. Bauer, A. Chacon, J. Kindervater, S. Mühlbauer, C. Pfleiderer, S. Buhrandt, C. Schütte, A. Rosch, 
Science, Advanced online publication, 31 May 2013, DOI: after end of embargo


For First Time Atomic Changes In A Molecule During A Chemical Reaction Photographed

Taking an image of an individual molecule while it undergoes a chemical reaction has been deemed one of the holy grails of chemistry. Scientists at the University of Berkeley and the University of the Basque Country (UPV-EHU) have managed, for the very first time, to take direct, single-bond-resolved images of individual molecules just before and immediately after a complex organic reaction. 

Credit: Elhuyar Fundazioa

The images enable appreciating the processes of the rupture and creation of links between the atoms making up a molecule. The article, entitled Direct Imaging of Covalent Bond Structure in Single-Molecule Chemical Reactions, appears today, the 30 of May, in the online Science Express as an outstanding research work and will be published in the print edition of Science in the middle of June. The authors are the teams of Felix Fischer (Department of Chemistry at Berkeley), Michael Crommie (Department of Physics at the same university) and Ángel Rubio (Professor at the UPV/EHU and researcher at the CSIC-UPV/EHU Centre for the Physics of Materials and at the Donostia International Physics Center). The lead author of the article is Mr. Dimas Oteyza, who has just been reincorporated into the CSIC-UPV/EHU Centre for the Physics of Materials after his postdoctoral term in Berkeley.

Organic chemical reactions are, in general, fundamental processes that underlie all biology, as well as highly important industrial processes, such as the production of liquid fuel. The structural models of molecules that we have traditionally relied on to understand these processes come from indirect measurements averaged over an enormous number of molecules (in the order of 1020) as well as from theoretical calculations. Nobody has ever before taken direct, single-bond-resolved images of individual molecules right before and immediately after a complex organic reaction.

“The importance of our discovery is that we were able to image the detailed microscopic structures that a molecule can transform into on a surface, thus allowing us to directly determine the microscopic atomic motions that underlie these chemical transformations”, explained Ángel Rubio. More specifically, researchers were able to record highly resolved images of an oligo-enediyne (a simple molecule composed of three benzene rings linked by carbon atoms) deposited on a flat gold surface. The technique used is called non-contact Atomic Force Microscopy (nc-AFM), based on an instrument with an extraordinarily sensitive tactile probe. 

This AFM uses a very fine needle that can sense even the smallest atomic-scale bumps on a surface in much the same way that you would use the tip of your fingers to read/feel a word written in Braille. Given that the oligo-enediyne molecules studied are so small (~10–9 m) the probe tip of this instrument was configured to consist of only a single oxygen atom. This arises from a single carbon monoxide (CO) molecule adsorbed onto the AFM microscope tip and acting as an “atomic finger” in tactile reading.”

By moving this “atomic finger” back and forth along the surface they obtained height profiles corresponding to the precise positions of atoms and chemical bonds of the oligo-enediyne molecules studied. Recent advances in this microscopy technique have made it so precise that we can even distinguish the bond order between carbon atoms (single or double or triple bonds). On heating the surface supporting our molecules, they induced a chemical reaction that is closely related to “cyclisations”. 

Cyclisations, discovered by Berkeley Professor Bergman in the early 1970s, cause carbon atoms linked in chains (aromatic rings) to “fold up” into closed-ring formations. “The height profiles we recorded after the molecules react clearly show how new chemical bonds are formed and how atoms within the molecules rearrange to form new structures”, explained Dimas Oteyza. The results have been interpreted and analysed microscopically thanks to simulations carried out by Mr Rubio’s team.

Apart from achieving surprising visual confirmation of the microscopic mechanisms underlying theoretically predicted organic chemical reactions, this work has relevance in the manufacture of new, high-precision customised materials and electronic apparatus at a nanometric scale.


Contacts and sources:
Irati Kortabitarte
Elhuyar Fundazioa

Even With Defects, Graphene Is Strongest Material In The World

In a new study, published in Science May 31, 2013, Columbia Engineering researchers demonstrate that graphene, even if stitched together from many small crystalline grains, is almost as strong as graphene in its perfect crystalline form. This work resolves a contradiction between theoretical simulations, which predicted that grain boundaries can be strong, and earlier experiments, which indicated that they were much weaker than the perfect lattice.

Graphene remains the strongest material ever measured and, as Columbia Engineering Professor James Hone once said, so strong that "it would take an elephant, balanced on a pencil, to break through a sheet of graphene the thickness of Saran Wrap."

Credit: Illustration by Andrew Shea for Columbia Engineering

Graphene consists of a single atomic layer of carbon, arranged in a honeycomb lattice. "Our first Sciencepaper, in 2008, studied the strength graphene can achieve if it has no defects—its intrinsic strength," says James Hone, professor of mechanical engineering, who led the study with Jeffrey Kysar, professor of mechanical engineering. "But defect-free, pristine graphene exists only in very small areas. Large-area sheets required for applications must contain many small grains connected at grain boundaries, and it was unclear how strong those grain boundaries were. This, our second Science paper, reports on the strength of large-area graphene films grown using chemical vapor deposition (CVD), and we're excited to say that graphene is back and stronger than ever."

The study verifies that commonly used methods for post-processing CVD-grown graphene weaken grain boundaries, resulting in the extremely low strength seen in previous studies. The Columbia Engineering team developed a new process that prevents any damage of graphene during transfer. "We substituted a different etchant and were able to create test samples without harming the graphene," notes the paper's lead author, Gwan-Hyoung Lee, a postdoctoral fellow in the Hone lab. "Our findings clearly correct the mistaken consensus that grain boundaries of graphene are weak. This is great news because graphene offers such a plethora of opportunities both for fundamental scientific research and industrial applications."

In its perfect crystalline form, graphene (a one-atom-thick carbon layer) is the strongest material ever measured, as the Columbia Engineering team reported in Science in 2008—so strong that, as Hone observed, "it would take an elephant, balanced on a pencil, to break through a sheet of graphene the thickness of Saran Wrap." For the first study, the team obtained small, structurally perfect flakes of graphene by mechanical exfoliation, or mechanical peeling, from a crystal of graphite. But exfoliation is a time-consuming process that will never be practical for any of the many potential applications of graphene that require industrial mass production.

Currently, scientists can grow sheets of graphene as large as a television screen by using chemical vapor deposition (CVD), in which single layers of graphene are grown on copper substrates in a high-temperature furnace. One of the first applications of graphene may be as a conducting layer in flexible displays.

"But CVD graphene is 'stitched' together from many small crystalline grains—like a quilt—at grain boundaries that contain defects in the atomic structure," Kysar explains. "These grain boundaries can severely limit the strength of large-area graphene if they break much more easily than the perfect crystal lattice, and so there has been intense interest in understanding how strong they can be."

The Columbia Engineering team wanted to discover what was making CVD graphene so weak. In studying the processing techniques used to create their samples for testing, they found that the chemical most commonly used to remove the copper substrate also causes damage to the graphene, severely degrading its strength.

Their experiments demonstrated that CVD graphene with large grains is exactly as strong as exfoliated graphene, showing that its crystal lattice is just as perfect. And, more surprisingly, their experiments also showed that CVD graphene with small grains, even when tested right at a grain boundary, is about 90% as strong as the ideal crystal.

"This is an exciting result for the future of graphene, because it provides experimental evidence that the exceptional strength it possesses at the atomic scale can persist all the way up to samples inches or more in size," says Hone. "This strength will be invaluable as scientists continue to develop new flexible electronics and ultrastrong composite materials."

Strong, large-area graphene can be used for a wide variety of applications such as flexible electronics and strengthening components—potentially, a television screen that rolls up like a poster or ultrastrong composites that could replace carbon fiber. Or, the researchers speculate, a science fiction idea of a space elevator that could connect an orbiting satellite to Earth by a long cord that might consist of sheets of CVD graphene, since graphene (and its cousin material, carbon nanotubes) is the only material with the high strength-to-weight ratio required for this kind of hypothetical application.

The team is also excited about studying 2D materials like graphene. "Very little is known about the effects of grain boundaries in 2D materials," Kysar adds. "Our work shows that grain boundaries in 2D materials can be much more sensitive to processing than in 3D materials. This is due to all the atoms in graphene being surface atoms, so surface damage that would normally not degrade the strength of 3D materials can completely destroy the strength of 2D materials. However with appropriate processing that avoids surface damage, grain boundaries in 2D materials, especially graphene, can be nearly as strong as the perfect, defect-free structure."

The study was supported by grants from the Air Force Office of Scientific Research and the National Science Foundation.


Contacts and sources:
Holly Evarts
Columbia University

New Speaker System For Cars Creates Separate 'Audio Zones' For Front And Rear

Ever wish that your car's interior cabin could have separate audio zones for the front and rear seats? It soon may.

A new approach achieves independent listening zones within a car by using small, modified speakers to produce directional sound fields and a signal processing strategy that optimizes the audio signals used to drive each of the speakers. The new design will be presented at the 21st International Congress on Acoustics (ICA 2013), held June 2-7 in Montreal.

Car Cabin 
Credit: nicecarautos.blogspot.com

Today, car cabins often reverberate with the sounds of music, video soundtracks, navigation system instructions, telecommunications, and warning sounds. Problems arise, however, when occupants of the same car want to listen to different programs. The driver may require navigation system instructions and warning sounds, while the kids in the back seat want to watch a movie. Intergenerational audio conflict might be avoided, however, with a new type of car speaker system.

"We've begun developing an audio reproduction system capable of producing independent listening zones in the front and rear seats of a car cabin – without the use of headphones," says Jordan Cheer, Research Fellow in Active Control at the Institute of Sound and Vibration Research at the University of Southampton, UK. "Our system uses standard car audio loudspeakers, which are usually mounted in the doors of the car, at low frequencies, and these are complemented by a set of small loudspeakers mounted to the headrests."

"Our complete system is able to achieve a significant level of isolation between the front and rear seating positions to provide independent listening zones for the front and rear cabin occupants," Cheer says.

The necessary degree of isolation between the two listening zones depends on the audio program, he explains. For example, if speech is being reproduced at the front seats and pop music is playing in the rear seats, a higher level of isolation is required than if pop music were playing in both zones.

Future work on the system will factor in the effect of the audio program selection on the required system performance. Based on this information, the researchers will continue to explore improvements to both loudspeaker configuration and digital signal processing.

Presentation 1aSP9, "Design and implementation of a personal audio system in a car cabin," is in the morning session on Monday, June 3. Abstract: http://asa.aip.org/web2/asa/abstracts/search.jun13/asa117.html


Contacts and sources:
Catherine Meyers
American Institute of Physics

Ultrasound 'Making Waves' For Enhancing Biofuel Production

All chefs know that "you have to break some eggs to make an omelet," and that includes engineers at Iowa State University who are using high-frequency sound waves to break down plant materials in order to cook up a better batch of biofuel.

Research by David Grewell, associate professor of agricultural and biosystems engineering, and his colleagues Melissa Montalbo-Lomboy and Priyanka Chand, has shown that "pretreating" a wide variety of feedstocks (including switch grass, corn stover, and soft wood) with ultrasound consistently enhances the chemical reactions necessary to convert the biomass into high-value fuels and chemicals.

(A) Biodiesel conversion (TGA weight percent yields) obtained with ultrasonic treatment at a pulse mode (5 s on/25 s off) of 60μm. (B) Biodiesel conversion (TGA weight percent yields) obtained with ultrasonic treatment at a pulse mode of 120 μm. (C) Biodiesel conversion
(TGA weight percent yields) obtained with ultrasonic treatment at a pulse mode of 180 μm. (D) Comparison of biodiesel conversion (TGA weight percent) obtained at three amplitude levels in pulse mode.

Credit: Iowa State University

The team will present its findings at the 21st International Congress on Acoustics (ICA 2013), held June 2-7 in Montreal.

In one example of ultrasound's positive impact on biofuel production, the Iowa State researchers found that they could significantly increase the efficiency of removing lignin from biomass in solution. Lignin is the chemical compound that binds cellulose and hemicellulose together in plant cell walls. Commonly, enzymes or chemicals are used to remove it from biomass and allow the freed sugars to be dissolved for further processing into biofuel. Grewell and his colleagues found that pretreating instead with ultrasound makes lignin removal so efficient that sugar dissolution occurs in minutes rather than the hours needed with traditional mixing systems.

Grewell's team also found that hydrolysis of corn starch could be greatly accelerated using ultrasonics. In a conventional ethanol plant, ground corn is steamed with jet cookers at boiling point temperatures. This breaks down the corn, leaving a starch mash that is then cooled and treated with enzymes in a process known as hydrolysis to release glucose for fermentation. The Iowa State team replaced the initial steaming with ultrasound, sonically smashing the corn into tiny particles in the same way physicians use ultrasound to shatter kidney stones. The smaller corn fragments provided more surface area for enzymatic action, and therefore, resulted in fermentation yields comparable to jet cooking.

The potential cost savings for this method, says Grewell, are very encouraging. "Economic models," he explains, "have shown that once implemented, this technology could have a payback period of less than one year."

Grewell and his colleagues report a third application for ultrasound in biofuel production, showing that they can accelerate transesterification, the main chemical reaction for converting oil to biodiesel. In one case, the researchers found that subjecting soybean oil to ultrasound transformed it into biodiesel in less than a minute, rather than the 45 minutes it normally takes. Similarly, Grewell's team found that yeast populated with sugar and starved with glycerin, a co-product of biodiesel production, could prodfuce high yields of oil that could be extracted and simultaneously converted to biodiesel with ultrasonics in less than a minute. This is a dramatically faster and less complicated method than traditional techniques requiring multiple steps and relatively long cycle times.

Presentation 5aPA3, "Enhancing biofuel production by ultrasonics," is in the morning session on Friday, June 7. Abstract: http://asa.aip.org/web2/asa/abstracts/search.jun13/asa1501.html

Contacts and sources:
Catherine Meyers
American Institute of Physics

Secrets Of The Cicada's Sound

Of all the bugs that achieve the mantle of summer pest, cicadas are perhaps the most curious. They don't sting, they don't bite, they don't buzz around your head, they taste good in chocolate, but as the drowning din of the 17-year brood this summer will remind: we would love them less if they emerged more often.

Cicada
File:Tibicen linnei.jpg
Credit: Wikipedia

Cicadas are unique among insects in their ability to emit loud and annoying sounds. So why would anyone actually want to replicate theses sounds?

A team of U.S. Naval researchers have been working on that very problem for several years now, because it turns out that the humble cicada has naturally solved a compelling unmet challenge in underwater communication: how to make an extremely loud noise with a very small body using very little power.

At the 21st International Congress on Acoustics (ICA 2013), held June 2-7 in Montreal, the team, based at the Naval Undersea Warfare Center (NUWC) in Newport, RI, will present their latest results analyzing the cicada's sound – first steps toward making devices that would mimic it for remote sensing underwater, ship-to-ship communications, rescue operations and other applications.

How Cicadas Make Their Sound

Humans have marveled at the periodic emergence of cicadas for thousands of years, and as far back as the 1940s, scientists have tried to uncover the secrets of this strange insect. But only recently has it been possible to carefully measure the physical properties of the cicada using lasers to simultaneously measure the vibration of its "tymbals," the corrugated exoskeleton on the insect responsible for its sound, explained Derke Hughes, a researcher at the Naval Undersea Warfare Center.

Hughes works on an unfunded project to uncover the insect's secrets in his spare time, collaborating with other volunteers. In Montreal, Hughes and his colleagues will present work on the nonlinear nature of cicada mating calls.

Their analysis shows is that the insects manage to produce their incredibly large sound because they have a unique anatomy that combines a ribbed membrane on the torso that vibrates when they deform their bodies.

While that basic insight is clear, the problem of reproducing the sound is still daunting, Hughes said. He has not yet worked out an accurate physics-based model that describes how the cicada makes its sound when it deforms its body. "We're still working on it," he said.

A second talk in Montreal will describe an attempt to give a fuller physical explanation of how the cicada generates sound. The explanation, in brief, is that a buckling rib is arrested in its rapid motion by impact with the part of the cicada's anatomy called a tymbal, which functions somewhat as a gong being hit by a hammer. It is set into vibration at nearly a single frequency, and the vibration rapidly dies out.

Like Buckling All Your Ribs at Once

To understand how the cicada makes its sound, you would have to imagine pulling your ribs to the point of buckling collapse, releasing them and then repeating that cycle, said Hughes.

Time sequence photos of a Tibicen cicada moulting in Ohio
Credit: Wikipedia

If your body were like that of a cicada, he explained, you would have a thick set of muscles on either side of your torso that would allow you to cave in your chest so far that all your ribs would buckle inward one at a time into a deformed position. Releasing the muscle would allow your ribs to snap back to their regular shape and then pulling the muscle again would repeat this. The cicada repeats this cycle for its left and right sides about 300 to 400 times a second.

"That's basically what's happening in the cicada," Hughes said.

Replicating this sound is a challenge because the cicada's chirp is nonlinear – it is not a simple matter of one part moving and the sound emerging from that. The buckling is not a uniform process, and the tymbal surfaces vibrate out of phase with each other and then somehow combine to make a sound that can drown out even the noisiest summer barbecues.

Why Cicadas Make Noise

The cause for all that chirping is nature's oldest, Hughes said. Cicada males make sounds to attract nearby females, who respond by snapping their wings. The male hears this and responds to by moving closer.

A few years ago Hughes and his colleagues showed that as the male cicada approaches the female, its sound gets softer. Hughes described this as the cicada putting on its best bedroom voice and uttering the insect equivalent of "hey, baby."

In field experiments, he and his colleagues showed that they could trick the male cicada by making a snapping sound that mimics the female.

The presentations 1pAB11 and 1pAB10, "Nature of nonlinear mechanisms in the generation and propagation of sound in the cicada mating call" and "Buckling as a source of sound, with application to the modeling of cicada sound generation," are in the afternoon session of Monday, June 3. Abstracts: http://asa.aip.org/web2/asa/abstracts/search.jun13/asa151.html andhttp://asa.aip.org/web2/asa/abstracts/search.jun13/asa150.html

Contacts and sources:
Catherine Meyers
American Institute of Physics

A New Kind Of Cosmic Glitch

Astronomers led by McGill research group discover new phenomenon in neutron star

The physics behind some of the most extraordinary stellar objects in the Universe just became even more puzzling.

A group of astronomers led by McGill researchers using NASA's Swift satellite have discovered a new kind of glitch in the cosmos, specifically in the rotation of a neutron star.

Neutron stars are among the densest objects in the observable universe; higher densities are found only in their close cousins, black holes. A typical neutron star packs as much mass as half-a-million Earths within a diameter of only about 20 kilometers. A teaspoonful of neutron star matter would weigh approximately 1 billion tons, roughly the same as 100 skyscrapers made of solid lead.

Credit: NASA

Neutron stars are known to rotate very rapidly, from a few revolutions per minute to as fast as several hundred times per second. A neutron star glitch is an event in which the star suddenly begins rotating faster. These sudden spin-up glitches have long been thought to demonstrate that these exotic ultra-dense stellar objects contain some form of liquid, likely a superfluid.

This new cosmic glitch was detected in a special kind of neutron star – a magnetar -- an ultra-magnetized neutron star that can exhibit dramatic outbursts of X-rays, sometimes so strong they can affect the Earth's atmosphere from clear across the galaxy. A magnetar's magnetic field is so strong that, if one were located at the distance of the Moon, it could wipe clean a credit card magnetic strip here on Earth.

Now astronomers led by a research group at McGill University have discovered a new phenomenon: they observed a magnetar suddenly rotate slower -- a cosmic braking act they've dubbed an "anti-glitch." The result is reported in the May 30 issue of Nature.

The magnetar in question, 1E 2259+586 located roughly 10,000 light years away in the constellation of Cassiopeia, was being monitored by the McGill group using the Swift X-ray telescope in order to study the star's rotation and try to detect the occasional giant X-ray explosions that are often seen from magnetars.

"I looked at the data and was shocked -- the neutron star had suddenly slowed down," says Rob Archibald, lead author and MSc student at McGill University. "These stars are not supposed to behave this way."

Accompanying the sudden slowdown, which rang in at one third of a part per million of the 7-second rotation rate, was a large increase in the X-ray output of the magnetar, telltale evidence of a major event inside or near the surface of the neutron star.

"We've seen huge X-ray explosions from magnetars before," says Victoria Kaspi, Professor of Physics at McGill and leader of the Swift magnetar monitoring program, "but an anti-glitch was quite a surprise. This is telling us something brand new about the insides of these amazing objects." In 2002, NASA's Rossi X-ray Timing Explorer satellite also saw a large X-ray outburst from the source, but in that case, it was accompanied by a more usual spin-up glitch.

The internal structure of neutron stars is a long-standing puzzle, as the matter inside these stars is subject to forces so intense that they are presently not re-creatable in terrestrial laboratories. The densities at the hearts of neutron stars are thought to be upwards of 10 times higher than in the atomic nucleus, far beyond what current theories of matter can describe.

The reported anti-glitch strongly suggests previously unrecognized behaviour inside neutron stars, possibly with pockets of superfluid rotating at different speeds. The researchers further point out in the Nature paper that some properties of conventional glitches have been noted to be puzzling and suggestive of flaws in the existing theory to explain them. They are hoping that the discovery of a new phenomenon will open the door to renewed progress in understanding neutron star interiors.

The research was funded in part by the Natural Sciences and Engineering Research Council of Canada, the Canadian Institute for Advance Research, the Fonds de recherche du Québec - Nature et technologies, the Canada Research Chairs program, the Lorne Trottier Chair in Astrophysics and Cosmology, and the Centre de recherche en Astrophysique du Québec.


Contacts and sources:
Chris Chipello
McGill University

Radiation Could Be Killer For Trip To Mars

On November 26, 2011, the Mars Science Laboratory began a 253-day, 560-million-kilometer journey to deliver the Curiosity rover to the Red Planet. En route, the Southwest Research Institute-led Radiation Assessment Detector (RAD) made detailed measurements of the energetic particle radiation environment inside the spacecraft, providing important insights for future human missions to Mars.

The RAD instrument measures radiation dose using silicon detector and plastic scintillator technology. The latter has a composition somewhat similar to tissue and is more sensitive to neutrons than are the silicon detectors. This illustration of RAD shows the silicon detectors (A, B & C) that measure charged particles and the plastic detectors (D, E & F) that measure both charged and neutral particles. (Hassler et al., 2012. Space Science Reviews, 170, 503. )
 Diagram: RAD instrument
Image courtesy of Southwest Research Institute

"In terms of accumulated dose, it's like getting a whole-body CT scan once every five or six days," said Dr. Cary Zeitlin, a principal scientist in SwRI's Space Science and Engineering Division and lead author of Measurements of Energetic Particle Radiation in Transit to Mars on the Mars Science Laboratory, scheduled for publication in the journal Science on May 31.

"Understanding the radiation environment inside a spacecraft carrying humans to Mars or other deep space destinations is critical for planning future crewed missions," Zeitlin said. "Based on RAD measurements, unless propulsion systems advance rapidly, a large share of mission radiation exposure will be during outbound and return travel, when the spacecraft and its inhabitants will be exposed to the radiation environment in interplanetary space, shielded only by the spacecraft itself."

Two forms of radiation pose potential health risks to astronauts in deep space: a chronic low dose of galactic cosmic rays (GCRs) and the possibility of short-term exposures to the solar energetic particles (SEPs) associated with solar flares and coronal mass ejections. Radiation dose is measured in units of Sievert (Sv) or milliSievert (1/1000 Sv). Long-term population studies have shown that exposure to radiation increases a person's lifetime cancer risk; exposure to a dose of 1 Sv is associated with a 5 percent increase in fatal cancer risk.

GCRs tend to be highly energetic, highly penetrating particles that are not stopped by the modest shielding provided by a typical spacecraft. These high-energy particles include a small percentage of so-called heavy ions, which are atomic nuclei without their usual complement of electrons. Heavy ions are known to cause more biological damage than other types of particles.

The solar particles of concern for astronaut safety are typically protons with kinetic energies up to a few hundred MeV (one MeV is a million electron volts). Solar events typically produce very large fluxes of these particles, as well as helium and heavier ions, but rarely produce higher-energy fluxes similar to GCRs. The comparatively low energy of typical SEPs means that spacecraft shielding is much more effective against SEPs than GCRs.

"A vehicle carrying humans into deep space would likely have a 'storm shelter' to protect against solar particles. But the GCRs are harder to stop and, even an aluminum hull a foot thick wouldn't change the dose very much," said Zeitlin.

Energetic protons constitute about 85 percent of the primary galactic cosmic ray flux and easily traverse even the most shielded paths (reds) inside the MSL spacecraft. Heavy ions tend to break up into lighter ions in thick shielding, but can survive traversal of thin shielding (blues) intact. 
Diagram: RAD Shielding in Cruise
Image courtesy of Southwest Research Institute

"The RAD data show an average GCR dose equivalent rate of 1.8 milliSieverts per day in cruise. The total during just the transit phases of a Mars mission would be approximately .66 Sv for a round trip with current propulsion systems," said Zeitlin. Time spent on the surface of Mars might add considerably to the total dose equivalent, depending on shielding conditions and the duration of the stay. Exposure values that ensure crews will not exceed the various space agencies standards are less than 1 Sv.

"Scientists need to validate theories and models with actual measurements, which RAD is now providing. These measurements will be used to better understand how radiation travels through deep space and how it is affected and changed by the spacecraft structure itself," says Donald M. Hassler, a program director at Southwest Research Institute and principal investigator of the RAD investigation. "The spacecraft protects somewhat against lower energy particles, but others can propagate through the structure unchanged or break down into secondary particles."

Only about 5 percent of the radiation dose was associated with solar particles, both because it was a relatively quiet period in the solar cycle and due to shielding provided by the spacecraft. Crew exposures during a human mission back and forth to Mars would depend on the habitat shielding and the unpredictable nature of large SEP events. Even so, the results are representative of a trip to Mars under conditions of low to moderate solar activity.

The Curiosity rover, with RAD mounted to its top deck, was folded inside the MSL spacecraft on its trip to Mars, sitting immediately beneath the descent module and above the heat shield. The spacecraft and various internal structures provided complicated levels of shielding against the deep space radiation environment. A spacecraft carrying humans would likely be designed to have a more homogeneous mass distribution with few if any lightly shielded paths into inhabited areas. (credit NASA)

Image courtesy of Southwest Research Institute

"This issue will have to be addressed, one way or another, before humans can go into deep space for months or years at a time," said Zeitlin.

SwRI, together with Christian Albrechts University in Kiel, Germany, built RAD with funding from the NASA Human Exploration and Operations Mission Directorate and Germany's national aerospace research center, Deutsches Zentrum für Luft- und Raumfahrt.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, Calif., manages the Mars Science Laboratory Project. The NASA Science Mission Directorate, at NASA Headquarters in Washington, manages the Mars Exploration Program.


Contacts and sources:
Southwest Research Institute

Comet ISON Hurtling Toward Uncertain Destiny With The Sun

Astronomer Karen Meech, at the University of Hawaii’s Institute for Astronomy (IfA) in Honolulu, is currently working on preliminary analysis of the new Gemini data (as well as other observations from around the world) and notes that the comet’s activity has been decreasing somewhat over the past month.

Images of Comet ISON obtained using the Gemini Multi-Object Spectrograph at Gemini North on February 4, March 4, April 3, and May 4, 2013 (left to right, respectively; Comet ISON at center in all images).
Credit: Gemini Observatory/AURA Color composite produced by Travis Rector, University of Alaska Anchorage.

“Early analysis of our models shows that ISON’s brightness through April can be reproduced by outgassing from either carbon monoxide or carbon dioxide. The current decrease may be because this comet is coming close to the Sun for the first time, and a “volatile frosting” of ice may be coming off revealing a less active layer beneath. It is just now getting close enough to the Sun where water will erupt from the nucleus revealing ISON’s inner secrets,” says Meech.

“Comets may not be completely uniform in their makeup and there may be outbursts of activity as fresh material is uncovered,” adds IfA astronomer Jacqueline Keane. “Our team, as well as astronomers from around the world, will be anxiously observing the development of this comet into next year, especially if it gets torn asunder, and reveals its icy interior during its exceptionally close passage to the Sun in late November.”

NASA’s Swift satellite and the Hubble Space Telescope (HST) have also imaged Comet ISON recently in this region of space. Swift’s ultraviolet observations determined that the comet’s main body was spewing some 850 tons of dust per second at the beginning of the year, leading astronomers to estimate the comet’s nucleus diameter is some 3-4 miles (5-6 kilometers). HST scientists concurred with that size estimate, adding that the comet’s coma measures about 3100 miles (5000 km) across.

The comet gets brighter as the outgassing increases and pushes more dust from the surface of the comet. Scientists are using the comet’s brightness, along with information about the size of the nucleus and measurements of the production of gas and dust, to understand the composition of the ices that control the activity. Most comets brighten significantly and develop a noticeable tail at about the distance of the asteroid belt (about 3 times the Earth-Sun distance –– between the orbits of Mars and Jupiter) because this is when the warming rays of the Sun can convert the water ice inside the comet into a gas. This comet was bright and active outside the orbit of Jupiter — when it was twice as far from the Sun. This meant that some gas other than water was controlling the activity.

Meech concludes that Comet ISON “…could still become spectacularly bright as it gets very close to the Sun” but she cautions, “I’d be remiss, if I didn’t add that it’s still too early to predict what’s going to happen with ISON since comets are notoriously unpredictable.”
A Close Encounter

On November 28, 2013, Comet ISON will make one of the closest passes ever recorded as a comet grazes the Sun, penetrating our star’s million-degree outer atmosphere, called the corona, and moving to within 800,000 miles (1.3 million km) of the Sun’s surface. Shortly before that critical passage, the comet may appear bright enough for expert observers using proper care to see it close to the Sun in daylight.

What happens after that no one knows for sure. But if Comet ISON survives that close encounter, the comet may appear in our morning sky before dawn in early December and become one of the greatest comets in the last 50 years or more. Even if the comet completely disintegrates, skywatchers shouldn’t lose hope. When Comet C/2011 W3 (Lovejoy) plunged into the Sun’s corona in December 2011, its nucleus totally disintegrated into tiny bits of ice and dust, yet it still put on a glorious show after that event.

The question remains, are we in for such a show? Stay tuned…

Comet ISON: The View from the North and South

Regardless of whether Comet ISON becomes the “Comet of the Century,” as some speculate, it will likely be a nice naked-eye and/or binocular wonder from both the Northern and Southern Hemispheres in the weeks leading up to its close approach with the Sun.

By late October, the comet should be visible through binoculars as a fuzzy glow in the eastern sky before sunrise, in the far southeastern part of the constellation of Leo. By early November, the comet should be a much finer binocular object. It will steadily brighten as it drifts ever faster, night by night, through southern Virgo, passing close to the bright star Spica. It is during the last half of the month that observations will be most important, as the comet edges into Libra and the dawn, where it will brighten to naked-eye visibility and perhaps sport an obvious tail.

The comet reaches perihelion (the closest point in its orbit to the Sun) on November 28th, when it will also attain its maximum brightness, and perhaps be visible in the daytime. If Comet ISON survives perihelion, it will swing around the Sun and appear as both an early morning and early evening object from the Northern Hemisphere. The situation is less favorable from the Southern Hemisphere, as the comet will set before the Sun in the evening and rise with the Sun in the morning.

By December 10th, and given that everything goes well, Comet ISON may be a fine spectacle in the early morning sky as viewed from the Northern Hemisphere. Under dark skies, it may sport a long tail stretching straight up from the eastern horizon, from the constellations of Ophiuchus to Ursa Major. The comet will also be visible in the evening sky during this time but with its tail appearing angled and closer to the horizon.


Contacts and sources:Peter Michaud
Gemini Observatory

Ancient Egyptians Accessorized With Meteorites

Researchers at The Open University (OU) and The University of Manchester have found conclusive proof that Ancient Egyptians used meteorites to make symbolic accessories.

The evidence comes from strings of iron beads which were excavated in 1911 at the Gerzeh cemetery, a burial site approximately 70km south of Cairo. Dating from 3350 to 3600BC, thousands of years before Egypt's Iron Age, the bead analysed was originally assumed to be from a meteorite owing to its composition of nickel-rich iron. But this hypothesis was challenged in the 1980s when academics proposed that much of the early worldwide examples of iron use originally thought to be of meteorite-origin were actually early smelting attempts.

The Gerzeh bead is the earliest discovered use of iron by the ancient Egyptians.

Credit: Manchester Museum

Subsequently, the Gerzeh bead, still the earliest discovered use of iron by the Egyptians, was loaned by the Manchester Museum to the OU and the University of Manchester's School of Materials for further testing. Researchers used a combination of the OU's electron microscope and Manchester's X-Ray CT scanner to demonstrate that the nickel-rich chemical composition of the bead confirms its meteorite origins.

OU Project Officer Diane Johnson, who led the study, said: "This research highlights the application of modern technology to ancient materials not only to understand meteorites better but also to help us understand what ancient cultures considered these materials to be and the importance they placed upon them."

Meteorite iron had profound implications for the Ancient Egyptians, both in their perception of the iron in the context of its celestial origin and in early metallurgy attempts.

Co-author Dr Joyce Tyldesley, a Senior Lecturer in Egyptology at The University of Manchester, said: "Today, we see iron first and foremost as a practical, rather dull metal. To the ancient Egyptians, however, it was a rare and beautiful material which, as it fell from the sky, surely had some magical/religious properties. They therefore used this remarkable metal to create small objects of beauty and religious significance which were so important to them that they chose to include them in their graves."

Philip Withers, Professor of Materials Science at The University of Manchester, added: "Meteorites have a unique microstructural and chemical fingerprint because they cooled incredibly slowly as they travelled through space. It was really interesting to find that fingerprint turn up in Egyptian artefacts."

The paper, 'Analysis of a prehistoric Egyptian iron bead with implications for the use and perception of meteorite iron in ancient Egypt,' is published in the Meteoritics and Planetary Science journal.


Contacts and sources:
Aeron Haworth
University of Manchester

Elevated Carbon Dioxide Making Arid Regions Greener

Scientists have long suspected that a flourishing of green foliage around the globe, observed since the early 1980s in satellite data, springs at least in part from the increasing concentration of carbon dioxide in Earth’s atmosphere. Now, a study of arid regions around the globe finds that a carbon dioxide “fertilization effect” has, indeed, caused a gradual greening from 1982 to 2010.

New research links gradual greening of arid areas like Australia’s outback to increasing concentrations of atmospheric carbon dioxide. 
Photo by Bruce Doran

Focusing on the southwestern corner of North America, Australia’s outback, the Middle East, and some parts of Africa, Randall Donohue of the Commonwealth Scientific and Industrial Research Organization (CSIRO) in Canberra, Australia and his colleagues developed and applied a mathematical model to predict the extent of the carbon-dioxide (CO2) fertilization effect. They then tested this prediction by studying satellite imagery and teasing out the influence of carbon dioxide on greening from other factors such as precipitation, air temperature, the amount of light, and land-use changes.

The team’s model predicted that foliage would increase by some 5 to 10 percent given the 14 percent increase in atmospheric CO2 concentration during the study period. The satellite data agreed, showing an 11 percent increase in foliage after adjusting the data for precipitation, yielding “strong support for our hypothesis,” the team reports.

“Lots of papers have shown an average increase in vegetation across the globe, and there is a lot of speculation about what’s causing that,” said Donohue of CSIRO’s Land and Water research division, who is lead author of the new study. “Up until this point, they’ve linked the greening to fairly obvious climatic variables, such as a rise in temperature where it is normally cold or a rise in rainfall where it is normally dry. Lots of those papers speculated about the CO2 effect, but it has been very difficult to prove.”

He and his colleagues present their findings in an article that has been accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union.

The team looked for signs of CO2 fertilization in arid areas, Donohue said, because “satellites are very good at detecting changes in total leaf cover, and it is in warm, dry environments that the CO2 effect is expected to most influence leaf cover.” Leaf cover is the clue, he added, because “a leaf can extract more carbon from the air during photosynthesis, or lose less water to the air during photosynthesis, or both, due to elevated CO2­­.” That is the CO2 fertilization effect.

But leaf cover in warm, wet places like tropical rainforests is already about as extensive as it can get and is unlikely to increase with higher CO­2 concentrations. In warm, dry places, on the other hand, leaf cover is less complete, so plants there will make more leaves if they have enough water to do so. “If elevated CO­2 causes the water use of individual leaves to drop, plants will respond by increasing their total numbers of leaves, and this should be measurable from satellite,” Donohue explained.

To tease out the actual CO2 fertilization effect from other environmental factors in these regions, the researchers first averaged the greenness of each location across 3-year periods to account for changes in soil wetness and then grouped that greenness data from the different locations according to their amounts of precipitation. The team then identified the maximum amount of foliage each group could attain for a given precipitation, and tracked variations in maximum foliage over the course of 20 years. This allowed the scientists to remove the influence of precipitation and other climatic variations and recognize the long-term greening trend.

In addition to greening dry regions, the CO2 fertilization effect could switch the types of vegetation that dominate in those regions. “Trees are re-invading grass lands, and this could quite possibly be related to the CO2 effect,” Donohue said. “Long lived woody plants are deep rooted and are likely to benefit more than grasses from an increase in CO2.”

“The effect of higher carbon dioxide levels on plant function is an important process that needs greater consideration,” said Donohue. “Even if nothing else in the climate changes as global CO2 levels rise, we will still see significant environmental changes because of the CO2 fertilization effect.


Contacts and sources:\
Peter Weiss
AGU

Citation:  CO2 fertilisation has increased maximum foliage cover across the globe's warm, arid environments

Authors: Randall J. Donohue and Tim R. McVicar: CSIRO Land and Water, Canberra, Australia;

Michael L. Roderick: Research School of Biology, The Australian National University, Canberra, Australia; Research School of Earth Sciences, The Australian National University, Canberra, Australia; and Australian Research Council Centre of Excellence for Climate System Science;

Graham D. Farquhar: Research School of Biology, The Australian National University, Canberra, Australia.

NASA's GRAIL Mission Solves Mystery of Moon's Surface Gravity

NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission has uncovered the origin of massive invisible regions that make the moon's gravity uneven, a phenomenon that affects the operations of lunar-orbiting spacecraft.

Because of GRAIL's findings, spacecraft on missions to other celestial bodies can navigate with greater precision in the future.

Using a precision formation-flying technique, the twin GRAIL spacecraft mapped the moon's gravity field, as depicted in this artist's rendering. detail. 
GRAIL artist's rendition
Image credit: NASA/JPL-Caltech

GRAIL's twin spacecraft studied the internal structure and composition of the moon in unprecedented detail for nine months. They pinpointed the locations of large, dense regions called mass concentrations, or mascons, which are characterized by strong gravitational pull. Mascons lurk beneath the lunar surface and cannot be seen by normal optical cameras.

GRAIL scientists found the mascons by combining the gravity data from GRAIL with sophisticated computer models of large asteroid impacts and known detail about the geologic evolution of the impact craters. The findings are published in the May 30 edition of the journal Science.

"GRAIL data confirm that lunar mascons were generated when large asteroids or comets impacted the ancient moon, when its interior was much hotter than it is now," said Jay Melosh, a GRAIL co-investigator at Purdue University in West Lafayette, Ind., and lead author of the paper. "We believe the data from GRAIL show how the moon's light crust and dense mantle combined with the shock of a large impact to create the distinctive pattern of density anomalies that we recognize as mascons."

The origin of lunar mascons has been a mystery in planetary science since their discovery in 1968 by a team at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. Researchers generally agree mascons resulted from ancient impacts billions of years ago. It was not clear until now how much of the unseen excess mass resulted from lava filling the crater or iron-rich mantle upwelling to the crust.

On a map of the moon's gravity field, a mascon appears in a target pattern. The bulls-eye has a gravity surplus. It is surrounded by a ring with a gravity deficit. A ring with a gravity surplus surrounds the bulls-eye and the inner ring. This pattern arises as a natural consequence of crater excavation, collapse and cooling following an impact. The increase in density and gravitational pull at a mascon's bulls-eye is caused by lunar material melted from the heat of a long-ago asteroid impact.

"Knowing about mascons means we finally are beginning to understand the geologic consequences of large impacts," Melosh said. "Our planet suffered similar impacts in its distant past, and understanding mascons may teach us more about the ancient Earth, perhaps about how plate tectonics got started and what created the first ore deposits."

This new understanding of lunar mascons also is expected to influence planetary geology well beyond that of Earth and our nearest celestial neighbor.

"Mascons also have been identified in association with impact basins on Mars and Mercury," said GRAIL principal investigator Maria Zuber of the Massachusetts Institute of Technology in Cambridge. "Understanding them on the moon tells us how the largest impacts modified early planetary crusts."

Launched as GRAIL A and GRAIL B in September 2011, the probes, renamed Ebb and Flow, operated in a nearly circular orbit near the poles of the moon at an altitude of about 34 miles (55 kilometers) until their mission ended in December 2012. The distance between the twin probes changed slightly as they flew over areas of greater and lesser gravity caused by visible features, such as mountains and craters, and by masses hidden beneath the lunar surface.

JPL managed GRAIL for NASA's Science Mission Directorate in Washington. The mission was part of the Discovery Program managed at NASA's Marshall Space Flight Center in Huntsville, Ala. NASA's Goddard Space Flight Center, in Greenbelt, Md., manages the Lunar Reconnaissance Orbiter. Operations of the spacecraft's laser altimeter, which provided supporting data used in this investigation, is led by the Massachusetts Institute of Technology in Cambridge.

Lockheed Martin Space Systems in Denver built GRAIL.


Contacts and sources: 
DC Agle
Jet Propulsion Laboratory

Picture Taking Contact Lenses

Ulsan National Institute of Science & Technology (UNIST) has demonstrated that a live rabbit could wear contact lenses fitted with inorganic light-emitting diode with no side effects. This new class of hybrid transparent and stretchable electrode paves the way for flexible displays, solar cells, and electronics.

LED fitted soft eye contact lense

Credit:  UNIST

UNIST scientists have combined graphene with silver nanowires to form a thin, transparent and stretchable electrode which overcome the weaknesses of each individual material, resulting in a new class of electrodes with widespread possible applications including picture taking and scanning using soft contact lenses.

Transparent electrodes have been widely used in things like touch screens, flat-screen TVs, solar cells and light-emitting devices. Commonly made from indium tin oxide(ITO), it is brittle and cracks thus losing functionality if flexed. It also degrades over time, and is expensive due to the limited quantities of indium metal.

As an alternative, the networks of randomly distributed mNWs have been considered as promising candidates for next-generation transparent electrodes, due to their low-cost, high-speed fabrication of transparent electrodes. However, the number of disadvantages of the mNW networks limited their integration into commercial devices. They have low breakdown voltage, typically high NW-NW junction resistance, high contact resistance between network and active materials, material instability and poor adhesion to plastic substrates.

Graphene is also well known as good a candidate for transparent electrode because of their unique electrical properties and high mechanical flexibility. However, scalable graphene synthesis methods for commercialization produces lower quality graphene with individual segments called grains which increases the electrical resistance at boundaries between these grains.

Silver nanowires, on the other hand, have high resistance because they are randomly oriented like a jumble of toothpicks facing in different directions. In this random orientation, there are many contact between nanowires, resulting in high resistance due to large junction resistance of nanowires. Due to these drawbacks, neither is good for conducting electricity, but a hybrid structure, combined from two materials, is.

The hybrid material presents a high electrical and optical performance with mechanical flexibility and stretchability for flexible electronics. The hybrid transparent electrode has a low “sheet resistance” and high transmittance. There’s almost no change in its resistance when bent and folded. Where the ITO is bent, its resistance increases significantly. Additionally the hybrid material preserve its electrical and optical properties against thermal oxidation condition

The graphene-mNW hybrid structure developed by the UNIST research team is a new class of electrodes and may soon find use in a variety of other applications. The research team demonstrated Inorganic light-emitting diode (ILED) devices fitted on a soft eye contact lens using the transparent, stretchable interconnects of the hybrid electrodes as an application example.

As an in vivo study, this contact lens was worn by a live rabbit eye for five hours and no abnormal behavior, such as bloodshot eye or the rubbing of eye areas were observed in the live rabbit. Wearing eye contact lenses, picture-taking and scanning, is not science fiction anymore.

The research was led by Jang-Ung Park, professor of the School of Nano-Bioscience and Chemical Engineering at UNIST. “We believe the hybridization between two-dimensional and one-dimensional nanomaterials presents a promising strategy toward flexible, wearable electronics and implantable biosensor devices, and indicate the substantial promise of future electronics,” said Prof. Par

Contacts and sources:
UNIST

Ulsan National Institute of Science and Technolog
Homepage of Prof. Jang-Ung Park
Link to research paper

Citation: Published online on May 23, 2013 in Nano Letters. (Title: High-Performance, Transparent and Stretchable Electrodes using Graphene-Metal Nanowire Hybrid Structures.)

This work was supported by the National Research Foundation of Korea and the Ministry of Knowledge Economy through the Materials Original Technology Program. 

Thursday, May 30, 2013

Getting To The Bottom Of The Zombie Ant Phenomenon

While unraveling a dramatic case of mind control, biologist David Hughes is taking calls from Hollywood -- and gaining new insights into the role behavior plays in spreading disease.



It may sound like science fiction, but the body snatchers are for real. David Hughes has seen them, and trailed them from the jungles of Thailand to the woodlands of South Carolina. He has brought them back to his lab, and cultured them, and begun to unravel their secrets.

The cadaver of a zombie ant clings to a leaf in the tropical understory. Emerging from its head are spores of the parasitic fungus that killed it.

Image: David Hughes
Hughes, an assistant professor of entomology and biology at Penn State, is a rainforest ecologist with a special interest in parasites. In particular, he is fascinated by that subset of parasites that accomplishes its ends by mind control: invading the brain of a hapless host and causing that creature to do its bidding. Zombie behavior, biologists call the phenomenon. And the woods, as they say, are full of it.

Hughes has studied crickets compelled by parasitic worms to jump into swimming pools and drown themselves, whereupon the worm emerges wriggling and swims off to find a mate. He has looked at wasps that take orders from small parasitic insects sticking out of their backs, taxiing from flower to flower to spread the parasite's larvae. But the one subject of his research that has made the biggest splash—round-the-world headlines, CBC and BBC documentaries, consultant gigs for Hollywood movies and blockbuster video games—is the case of the zombie ants.


David Hughes helps bring zombies to life in movies and video games. Read about his Hollywood connections in the cause of science.

You may have heard the basic outlines. Infected by the fungusOphiocordyceps unilateralis, a common denizen of the world's tropical forests, individuals of a certain species of tree-dwelling carpenter ant behave in a most peculiar manner. Wandering as if drunk, they leave their nest high in the canopy and stagger or fall to the understory below. There they mill about aimlessly until, at the appointed hour, they bite down hard with their mandibles onto the main vein on the underside of a leaf about 10 inches above the ground. Those jaws remain locked even as the ant dies, its body still clinging to the leaf. A few days later, the victorious fungus pushes a stalk through a hole in the dead ant's head, and the stalk drops spores to infect more unsuspecting ants.

This creepy ritual is not new to science: It was first discovered in 1859 by the great British naturalist Alfred Russel Wallace. But it's only in the last few years that researchers have uncovered its details. During that span, Hughes and colleagues around the world have begun to show just how the fungus brainwashes its victim to accomplish a precise set of behaviors aimed at insuring its own survival.

Evolutionary biologists call it an extended phenotype. In effect, the hijacked host's behavior becomes an expression of the parasite's genes. Or, as Hughes has written: "While the manipulated individual may look like an ant, it represents a fungal genome expressing fungal behavior through the body of an ant."
Parasites Rule

Hughes has been stuck fast on parasites since he was an honors zoology student at the University of Glasgow in the late 1990s. "I was always taken with social insects, the idea of the collective," he remembers. "And then immediately I became interested in how parasites break into that collective, and break it down. It's the intersection between this beautifully orchestrated biology and something that's trying to smash it that interests me."

As a graduate student at Oxford, he worked on "a very beautiful, incredible organism known as Strepsiptera," the wasp-controlling insect, somewhere between a beetle and a fly, described above. This was not, he stresses, a fringe pursuit. "Half of life on earth is parasitic," Hughes says, "and parasites dominate biomass as well. We've only recently realized it, but most of the energy flowing through the environment is flowing through parasites."


Those that manipulate behavior, he notes, are a "tiny, tiny minority, and that only makes sense. It's extremely expensive biologically. The whole point of a parasite is to transmit its genes from one host to another, and so to continue on to the next generation. Most parasites can do a really good job of this without having to control behavior."

In fact, he says, the idea that some parasites control their hosts was long resisted in scientific circles. Its early champions—among them Richard Dawkins, the well-known evolutionary biologist—faced considerable opposition. "People dismissed it as storytelling," Hughes says. "It's only now in the last five years that it's become really accepted."

The difficulty, Hughes explains, has been that "in order to show that a parasite is controlling behavior, you have to show that that behavior is adaptive. That it's actually benefiting the parasite's fitness for survival." This was the task he set himself with the zombie-ant fungus.

He chose Ophiocordyceps mostly for practical reasons. "First, they have a small genome, so you can do a lot of genetics with them," he says. "Second, the beer and yeast industries are based on enzymes from fungi—so we know a lot already about the chemicals they produce. But the most important thing is this." He pulls out a small film canister and lifts off the lid to show two dead ants pinned to a circle of cork, one biting onto a tiny leaf, the other onto a twig. Each ant has a streamer of dried fungus trailing from its head.

"Most parasite-host interactions are ephemeral," he says. "But in this case, as you can see, the behavior is frozen. These ants may have died months before I found them, but I can still see what they were doing in the last minutes of their lives. This allows us to do huge studies all around the world."

This photo shows a zombie ant with the brain-manipulating fungus (Ophiocordyceps unilateralis) having been castrated by a hyperparasite fungus (white with yellow material).

Image: David Hughes

Following in Sequence

At first, those studies involved combing the jungle for extended periods, locating ant "graveyards" where hundreds of ant carcasses pile up over time, and then finding and observing live ants. "It isn't rocket science," Hughes says cheerily.

Working in a protected rainforest in Thailand in 2006 and 2007, he and his colleagues showed that fungal infection causes the drunken walking and convulsions suggestive of central nervous system impairment, and ultimately leads the ants to a precise location to die. They showed that that place, outside the nest but above the ground—and even the programmed time of death, solar noon—are optimal for the fungi's growth and reproduction. Examining thin sections of ants with powerful microscopes, they found heads packed with fungal cells, and also atrophy of the jaw muscles, a likely factor in the "death grip" that keeps the dead ant fixed to the leaf.

Theirs was one of the first studies to demonstrate fitness, Hughes says. In the five years since, the study of mind-controlling parasites has boomed. Last year, he co-edited a book for Oxford University Press that offers a broad overview of the field, with a foreword by Richard Dawkins himself. The term "extended phenotype" has come into scientific vogue.

"This has been mainly driven by our ability to understand the chemical evidence," Hughes says. With the powerful gene-sequencing tools now available, he explains, investigators have moved from describing remarkable behaviors observed in the field to explaining their precise chemical mechanisms.

Thus, using the resources of Penn State's Genomics Institute, a part of the Huck Institutes of the Life Sciences, Hughes and his students are currently sequencing the genome and transcriptomes of two species ofOphiocordyceps that manipulate ant behavior, with the aim of comparing them to the genomes of species that don't.

A complementary tool is metabolomics: analyzing the bioactive chemicals a given genome produces. Already, Hughes says, this approach has identified in the fungus a compound that likely causes the atrophy of ant jaw muscles. More recently, a post-doc on his team, Charissa de Bekker working with Andrew Patterson and Phil Smith at the Genomics Institute's metabolomics facility, found molecules that play a key role in controlling the ant's brain.

Ultimately, says Hughes, he hopes to move on to reverse genetics, a tactic used successfully by Penn State colleague Kelli Hoover to solve another longstanding insect-behavior mystery. Only last year, Hoover and colleagues, including Hughes, were able to pinpoint the viral gene responsible for tree-top disease, a zombie-like phenomenon observed since the 1890s in gypsy moth caterpillars that are infected with a parasitic virus. She did it by infecting caterpillars in the lab with a version of the virus in which the gene she suspected had been inactivated, and comparing the resulting behavior against that caused by the full-strength version.
Defensive Behavior

In addition to the latest technology, Hughes uses old-fashioned carpentry skills, recreating ant nests in the lab in order to better observe ant behavior. "Because we work in the rainforest, and know the ant habitats well, we can build cages which are realistic," he stresses. "One of the things we want to do is reconstruct the social network inside the ant colony."

This is the flip side of the parasite-host equation: Understanding how the host species defends itself against infection. "In the case of ants," he says, "things are set up to protect the queen, whose life is indispensable to the colony's survival."

More broadly, "We're interested in how societies defend themselves, both prophylactically, by setting themselves up in this way, but also actively," Hughes says. "If we increase the level of infection, does the network change?"


For David Hughes, the zombie ant phenomenon has important links to global food security. Read about his idea for using his knowledge of insect behavior to protect vital subsistence crops like cassava.

Hughes himself marvels at the ways in which the zombie-ant system has evolved. Apparently, it's had ample time to do so: he has identified the characteristic death-grip bite marks in a fossil leaf over 48 million years old. Through the millennia, the ants have developed a behavioral defense that forces the fungus to leave the colony to transmit its genes to the next generation. In response, the fungus has had to ramp up its own arsenal—the mind-altering chemicals that cause the ant itself to leave the nest. "Bear in mind that this is just a yeast, no different from the one in your beer," Hughes notes. "It can't see the world. It's getting around the world by moving this ant."

Over time, he adds, both opponents have become highly specialized. Hughes and colleagues recently named four new species of Ophiocordycepsfungus, each one associated with a different species of carpenter ant. He speculates that there may be a thousand Ophiocordyceps species in all. Just as remarkably, he says, "of all the hundreds of ant species in the Amazon, only 13 percent are infected by these fungi. So what is it about some ants that makes them potential zombies while others are not?"

Oh, and there's one more twist to these ongoing hostilities. The ants, it turns out, have an ally. Recently Hughes reported on a second type of fungus that lurks in the shadows, moving in to attack Ophiocordyceps as it emerges from the ant cadaver. This so-called hyperparasite—a parasite on another parasite—effectively castrates the zombie-ant fungus, preventing it from spreading its spores and infecting more ants.

In the end, of course, it's all part of a complicated ecological balance. The fact that the hyperparasite keeps Ophiocordyceps in check prevents that fungus from annihilating its host altogether, and thereby short-circuiting its own survival. Instead, Ophiocordyceps kills just enough individual ants to further its cause, while the larger colony on which it relies remains mostly intact.

It's a story of interdependence that, far from science fiction, is something Hughes, who has worked in 11 countries on five continents, has witnessed in the wild time and time again. "There's a million other things you could find out that are as complex and as beautiful as the zombie ant phenomenon," he says. "The problem is so few of us, even biologists, are willing to get down on our hands and knees and spend months in the forest looking at them.

Contacts and sources:
Matthew Swayne
Penn State
By David Pacchioli

Super-Dense Star Is First Ever Found Suddenly Slowing Its Spin

One of the densest objects in the universe, a neutron star about 10,000 light years from Earth, has been discovered suddenly putting the brakes on its spinning speed. The event is a mystery that holds important clues for understanding how matter reacts when it is squeezed more tightly than the density of an atomic nucleus -- a state that no laboratory on Earth has achieved. The discovery, by an international team of scientists that includes a Penn State University astronomer, will be published in the journal Nature on May 30.

The magnetar 1E 2259+586 shines a brilliant blue-white in this false-color X-ray image of the CTB 109 supernova remnant, which lies about 10,000 light-years away toward the constellation Cassiopeia. CTB 109 is only one of three supernova remnants in our galaxy known to harbor a magnetar. X-rays at low, medium and high energies are respectively shown in red, green, and blue in this image created from observations acquired by the European Space Agency's XMM-Newton satellite in 2002.
The magnetar 1E 2259+586
Image: ESA/XMM-Newton/M. Sasaki et al.

The scientists detected the neutron star's abrupt slow-down with NASA's Swift observatory, a satellite with three telescopes whose science and flight operations are controlled by Penn State from the Mission Operations Center on the University Park campus.

"Because Swift has the ability to regularly measure the spin of this unusual star, we have been able to observe its surprising evolution," said Penn State astronomer Jamie Kennea, a co-author of the Nature paper. "This neutron star is doing something completely unexpected. Its speed of rotation has been dropping at an increasingly rapid rate ever since the initial sudden decrease in its spin."

Although astronomers have observed neutron stars suddenly speeding up their spins -- an event called a "glitch" -- they never before had observed a neutron star suddenly slowing down. "We've dubbed this event an 'anti-glitch' because it affected this star in exactly the opposite manner of every other clearly identified glitch seen in neutron stars," said co-author Neil Gehrels, the lead researcher on the Swift mission, at NASA's Goddard Space Flight Center. The star is in the Northern Hemisphere sky in the constellation Cassiopeia.

A neutron star is the closest thing to a black hole that astronomers can observe directly. It is the crushed core of a massive star that ran out of fuel, collapsed under its own weight, and then exploded as a supernova. The matter left behind after the explosion is compressed into a ball only about 12 miles across but with a mass roughly half a million times more than the mass of the Earth. One teaspoon of a neutron star weighs 1 billion tons, roughly twice the combined weight of all the cars in the United States.

A neutron star is the densest object astronomers can observe directly, crushing half a million times Earth's mass into a sphere about 12 miles across, or similar in size to the length of Manhattan Island, as shown in this illustration.
Neutron star compared to Manhattan
Image: NASA's Goddard Space Flight Center

Neutron stars can reach speeds of rotation as fast as the blades of a kitchen blender -- up to 43,000 revolutions per minute (rpm), and can have magnetic fields a trillion times stronger than the Earth's. But this abruptly slowing neutron star, named 1E2259+586, is an even more bizarre and rare kind of neutron star. It is one of fewer than two dozen neutron stars called "magnetars" because they have such ultra-strong magnetic fields -- up to approximately 5,000 trillion times that of the Earth. Magnetars also can have dramatic outbursts of X-rays so strong that they can affect Earth's atmosphere, even if the magnetar is sending its blasts from the opposite side of our Milky Way galaxy. "Magnetars are the universe's strongest magnets and are some of the best laboratories we have for understanding pure physics," Kennea said. "The extreme conditions on these stars could never be replicated in any laboratory here on Earth."

Using the Swift observatory's X-ray Telescope, the scientists observed regular X-ray pulses from magnetar 1E 2259+586 from July 2011 to mid-April 2012. During this time, the magnetar was spinning once every 7 seconds, or about 8 rpm, and it appeared to be slowing down at a gradual and stable rate. But at the next scheduled observation on 28 April 2012, the data captured by Swift showed the star's spin had abruptly slowed by 2.2 millionths of a second -- the surprisingly sudden change that now is called an anti-glitch.

On April 21, just a week before the Swift observation that discovered this anti-glitch, the magnetar produced a brief but intense X-ray burst detected by the Gamma-ray Burst Monitor aboard NASA's Fermi Gamma-ray Space Telescope. The scientists now think this 36-millisecond eruption of high-energy light likely marked the changes that drove the magnetar into the abrupt "anti-glitch" slowdown mode. In addition, continuing observations have revealed that the magnetar's spin is continuing to slow down at a much faster rate.

These discoveries confront astronomers with a new theoretical challenge. What exactly could cause the magnetar's X-ray outburst, then the abrupt slowdown of its rotation, and now the even faster deceleration of the star's rotation that the Swift observatory is continuing to detect?

An artist's rendering of an outburst on an ultra-magnetic neutron star, also called a magnetar
An artist's rendering of an ultra-magnetic neutron star.
Image: NASA's Goddard Space Flight Center.

Theories of the internal structure of a neutron star, which were current before the anti-glitch discovery, envision a crust of electrons and charged particles above an interior containing, among other oddities, a bizarre, friction-free state of matter called a neutron superfluid. According to these theories, because the surface of a neutron star accelerates streams of high-energy particles through its intense magnetic field, the star's crust should always be losing energy and slowing down -- but the fluid in the interior of the neutron star should resist being slowed. The crust could fracture under this strain, producing an X-ray outburst while also receiving a kick from the faster-spinning interior that would speed the star's rotation. So now, after the discovery of the anti-glitch, scientists need improved theories to explain the unexpected and continuing slowing-down of the rotation of magnetar 1E 2259+586.

In addition to the new anti-glitch mystery, this discovery is expected to catalyze renewed efforts to solve long-standing mysteries about the puzzling physics that rules super-dense states of matter in neutron stars and black holes -- the most mysterious objects in the universe.

In addition to Kennea at Penn State and Gehrels at NASA Goddard, other co-authors of the Nature paper include astronomers at McGill University in Montreal in Canada, the University of Hong Kong, and the University of Leicester in the United Kingdom. The Swift observatory, launched into Earth orbit in November 2004, is managed by Goddard Space Flight Center and operated in collaboration with Penn State University, the Los Alamos National Laboratory, and Orbital Sciences Corporation, with international collaborators in the United Kingdom and Italy and including contributions from Germany and Japan.

Contacts and sources:
Matthew Swayne
Penn State