Slow Earthquakes: It's All In The Rock Mechanics

A slow earthquake is a discontinuous, earthquake-like event that releases energy over a period of hours to months, rather than the seconds to minutes characteristic of a typical earthquake.

Earthquakes that last minutes rather than seconds are a relatively recent discovery, according to an international team of seismologists. Researchers have been aware of these slow earthquakes, only for the past five to 10 years because of new tools and new observations, but these tools may explain the triggering of some normal earthquakes and could help in earthquake prediction.

"New technology has shown us that faults do not just fail in a sudden earthquake or by stable creep," said Demian M. Saffer, professor of geoscience, Penn State. "We now know that earthquakes with anomalous low frequencies -- slow earthquakes -- and slow slip events that take weeks to occur exist."

Slow slip events

Credit: Wikipedia

These new observations have put a big wrinkle into our thinking about how faults work, according to the researchers who also include Chris Marone, professor of geosciences, Penn State; Matt J. Ikari, recent Ph.D. recipient, and Achim J. Kopf, former Penn State postdoctural fellow, both now at the University of Bremen, Germany. So far, no one has explained the processes that cause slow earthquakes.

The researchers thought that the behavior had to be related to the type of rock in the fault, believing that clay minerals are important in this slip behavior to see how the rocks reacted. Ikari performed laboratory experiments using natural samples from drilling done offshore of Japan in a place where slow earthquakes occur. The samples came from the Integrated Ocean Drilling Program, an international collaborative. The researchers reported their results recently in Nature Geoscience.

These samples are made up of ocean sediment that is mostly clay with a little quartz.

"Usually, when you shear clay-rich fault rocks in the laboratory in the way rocks are sheared in a fault, as the speed increases, the rocks become stronger and self arrests the movement," said Saffer. "Matt noticed another behavior. Initially the rocks reacted as expected, but these clays got weaker as they slid further. They initially became slightly stronger as the slip rate increased, but then, over the long run, they became weaker."

The laboratory experiments that produced the largest effect closely matched the velocity at which slow earthquakes occur in nature. The researchers also found that water content in the clays influenced how the shear occurred.

"From the physics of earthquake nucleation based on the laboratory experiments we would predict the size of the patch of fault that breaks at tens of meters," said Saffer. "The consistent result for the rates of slip and the velocity of slip in the lab are interesting. Lots of things point in the direction for this to be the solution."

Common Cross Section of a Subduction Zone

Credit: Wikipedia

The researchers worry about slow earthquakes because there is evidence that swarms of low frequency events can trigger large earthquake events. In Japan, a combination of broadband seismometers and global positioning system devices can monitor slow earthquakes.

For the Japanese and others in earthquake prone areas, a few days of foreknowledge of a potential earthquake hazard could be valuable and save lives.

For slow slip events, collecting natural samples for laboratory experiments is more difficult because the faults where these take place are very deep. Only off the north shore of New Zealand is there a fault that can be sampled. Saffer is currently working to arrange a drilling expedition to that fault.

The National Science Foundation and the Deutsche Forschungsgemeinschaft supported this work.


Contacts and sources:
A'ndrea Elyse Messer
Penn State

Kinks And Curves At The Nanoscale

New research shows 'perfect twin boundaries' are not so perfect


One of the basic principles of nanotechnology is that when you make things extremely small—one nanometer is about five atoms wide, 100,000 times smaller than the diameter of a human hair—they are going to become more perfect.

Since 2004, materials scientists and nanotechnologists have been excited about a special of arrangement of atoms called a "coherent twin boundary" that can add strength and other advantages to metals like gold and copper. The CTB's are often described as "perfect," appearing like a one-atom-thick perfectly-flat plane in models and images. New research at the University of Vermont and Lawrence Livermore National Laboratory shows that these boundaries are not so perfect after all. Even more surprising, the newly discovered kinks and defects appear to be the cause of the CTB's strength.This image shows a simulation of atoms in a coherent twin boundary (shown in red) in copper. The newly discovered "kink" defects appear as green step-like structures and folds in the red areas. The red twin boundaries extend between columns of green atoms which represent grain boundaries within the copper.

Credit: Frederic Sansoz, University of Vermont

"Perfect in the sense that their arrangement of atoms in the real world will become more like an idealized model," says University of Vermont engineer Frederic Sansoz, "with smaller crystals—in for example, gold or copper—it's easier to have fewer defects in them."

And eliminating the defects at the interface separating two crystals, or grains, has been shown by nanotechnology experts to be a powerful strategy for making materials stronger, more easily molded, and less electrically resistant—or a host of other qualities sought by designers and manufacturers.

Since 2004, when a seminal paper came out in Science, materials scientists have been excited about one special of arrangement of atoms in metals and other materials called a "coherent twin boundary" or CTB.

Based on theory and experiment, these coherent twin boundaries are often described as "perfect," appearing like a perfectly flat, one-atom-thick plane in computer models and electron microscope images.

Over the last decade, a body of literature has shown these coherent twin boundaries—found at the nanoscale within the crystalline structure of common metals like gold, silver and copper—are highly effective at making materials much stronger while maintaining their ability to undergo permanent change in shape without breaking and still allowing easy transmission of electrons—an important fact for computer manufacturing and other electronics applications.

But new research now shows that coherent twin boundaries are not so perfect after all.

A team of scientists, including Sansoz, a professor in UVM's College of Engineering and Mathematical Sciences, and colleagues from the Lawrence Livermore National Laboratory and elsewhere, write in the May 19 edition of Nature Materials that coherent twin boundaries found in copper "are inherently defective."

Frederic Sansoz, a professor of engineering at the University of Vermont, works at the intersection of nanotechnology and materials science. His work makes extensive use of state-of-the-art atomistic simulation techniques, as well as of atomic force microscopy-based experiments for the discovery of new properties -- like a newly discovered set of defects in coherent twin boundaries.

Credit: Joshua Brown, University of Vermont, 2013

With a high-resolution electron microscope, using a more powerful technique than has ever been used to examine these boundaries, they found tiny kink-like steps and curvatures in what had previously been observed as perfect.

Even more surprising, these kinks and other defects appear to be the cause of the coherent twin boundary's strength and other desirable qualities.

"Everything we have learned on these materials in the past 10 years will have to be revisited with this new information," Sansoz says

The experiment, led by Morris Wang at the Lawrence Livermore Lab, applied a newly developed mapping technique to study the crystal orientation of CTBs in so-called nanotwinned copper and "boom—it revealed these defects," says Sansoz.

This real-world discovery conformed to earlier intriguing theoretical findings that Sansoz had been making with "atomistic simulations" on a computer. The lab results sent Sansoz back to his computer models where he introduced the newly discovered "kink" defects into his calculations. Using UVM's Vermont Advanced Computing Center, he theoretically confirmed that the kink defects observed by the Livermore team lead to "rather rich deformation processes at the atomic scale," he says, that do not exist with perfect twin boundaries.

With the computer model, "we found a series of completely new mechanisms," he says, for explaining why coherent twin boundaries simultaneously add strength and yet also allow stretching (what scientists call "tensile ductility")— properties that are usually mutually exclusive in conventional materials.

"We had no idea such defects existed," says Sansoz. "So much for the perfect twin boundary. We now call them defective twin boundaries."

For several decades, scientists have looked for ways to shrink the size of individual crystalline grains within metals and other materials. Like a series of dykes or walls within the larger structure, the boundaries between grains can slow internal slip and help resist failure. Generally, the more of these boundaries—the stronger the material.

Originally, scientists believed that coherent twin boundaries in materials were much more reliable and stable than conventional grain boundaries, which are incoherently full of defects. But the new research shows they could both contain similar types of defects despite very different boundary energies.

"Understanding these defective structures is the first step to take full use of these CTBs for strengthening and maintaining the ductility and electrical conductivity of many materials," Morris Wang said. "To understand the behavior and mechanisms of these defects will help our engineering design of these materials for high-strength applications."

For Sansoz, this discovery underlines a deep principle, "There are all manner of defects in nature," he says, "with nanotech, you are trying to control the way they are formed and dispersed in matter, and to understand their impact on properties. The point of this paper is that some defects make a material stronger."


Contacts and sources:
Joshua Brown
University of Vermont

Friday CME Arrives, No Geomagnetic Storm

A combined view of the coronal mass ejection, or CME, that occurred on May 17, 2013, at 5:36 EDT. The center yellow image was captured by NASA's Solar Dynamics Observatory and shows the sun as seen in UV light, in the 171 Angstrom wavelength. The SDO image is superimposed on top of an image from the Solar and Heliospheric Observatory showing the CME propagating into space.

Credit: NASA/SDO/Goddard, ESA&NASA SOHO

On 5:24 a.m. EDT on May 17, 2013, the sun erupted with an Earth-directed coronal mass ejection or CME, a solar phenomenon that can send billions of tons of solar particles into space that can reach Earth one to three days later and affect electronic systems in satellites and on the ground. Experimental NASA research models, based on observations from NASA’s Solar Terrestrial Relations Observatory, show that the CME left the sun at speeds of around 745 miles per second. The solar material in CMEs cannot pass through the atmosphere to affect humans on Earth.

Not to be confused with a solar flare, a CME can cause a space weather phenomenon called a geomagnetic storm, which occurs when they connect with the outside of the Earth's magnetic envelope, the magnetosphere, for an extended period of time.

The CME may also pass by Spitzer and its mission operators have been notified. If warranted, operators can put spacecraft into safe mode to protect the instruments from the solar material.

NOAA's Space Weather Prediction Center (http://swpc.noaa.gov) is the U.S. government's official source for space weather forecasts, alerts, watches and warnings.

The almost exclusively northward embedded magnetic field in the CME has resulted in no Geomagnetic Storm conditions at this writing. Things could change quickly if the field goes southward.

This video is a combination of two satellite views, showing both the sun and its atmosphere, the corona. The center image shows the sun in UV light, as captured by the Solar Dynamics Observatory, or SDO. The red and larger blue areas show the sun's corona as recorded by two instruments aboard the Solar and Heliospheric Observatory, or SOHO. The CME cloud appears and expands into space from the center left. The white dot on the far left is the planet Mars.  

Credit: NASA/SDO/Goddard, ESA& NASA SOHO


Contacts and sources:
Susan Hendrix
NASA/Goddard Space Flight Center

Cassini Shapes First Global Topographic Map of Titan

Scientists have created the first global topographic map of Saturn's moon Titan, giving researchers a valuable tool for learning more about one of the most Earth-like and interesting worlds in the solar system. The map was just published as part of a paper in the journal Icarus.

These polar maps show the first global, topographic mapping of Saturn’s moon Titan, using data from NASA's Cassini mission. To create these maps, scientists employed a mathematical process called splining, which uses smooth curved surfaces to “join” the areas between grids of existing topography profiles obtained by Cassini's radar instrument. The topography maps at bottom focus on the polar regions (north at left, south at right) in stereographic projection. The top maps show the 2-D radar data in gold and black, with topography data color-coded by elevation. The bottom images are from the new topography map, with contour lines added at 656 feet (200 meters) apart in elevation.   Visible are deep basins at 72 degrees south latitude and 20 degrees east longitude, and a wider basin at 68 degrees south latitude and 105 degrees east longitude.

Image credit: NASA/JPL-Caltech/ASI/JHUAPL/Cornell/Weizmann

Titan is Saturn's largest moon - with a radius of about 1,600 miles (2,574 kilometers), it's bigger than planet Mercury - and is the second–largest moon in the solar system. Scientists care about Titan because it's the only moon in the solar system known to have clouds, surface liquids and a mysterious, thick atmosphere. The cold atmosphere is mostly nitrogen, like Earth's, but the organic compound methane on Titan acts the way water vapor does on Earth, forming clouds and falling as rain and carving the surface with rivers. Organic chemicals, derived from methane, are present in Titan's atmosphere, lakes and rivers and may offer clues about the origins of life.

"Titan has so much interesting activity - like flowing liquids and moving sand dunes - but to understand these processes it's useful to know how the terrain slopes," said Ralph Lorenz, a member of the Cassini radar team based at the Johns Hopkins University Applied Physics Laboratory, Laurel, Md., who led the map-design team. "It's especially helpful to those studying hydrology and modeling Titan's climate and weather, who need to know whether there is high ground or low ground driving their models."

Using data from NASA's Cassini spacecraft, scientists have created the first global topographic map of Saturn’s moon Titan, giving researchers a 3-D tool for learning more about one of the most Earthlike and interesting worlds in the solar system. 

Image credit: NASA/JPL-Caltech/ASI/JHUAPL/Cornell/Weizmann 

Titan's thick haze scatters light in ways that make it very hard for remote cameras to "see" landscape shapes and shadows, the usual approach to measuring topography on planetary bodies. Virtually all the data we have on Titan comes from NASA's Saturn-orbiting Cassini spacecraft, which has flown past the moon nearly 100 times over the past decade. On many of those flybys, Cassini has used a radar imager, which can peer through the haze, and the radar data can be used to estimate the surface height.

"With this new topographic map, one of the most fascinating and dynamic worlds in our solar system now pops out in 3-D," said Steve Wall, the deputy team lead of Cassini's radar team, based at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "On Earth, rivers, volcanoes and even weather are closely related to heights of surfaces - we're now eager to see what we can learn from them on Titan."

There are challenges, however. "Cassini isn't orbiting Titan," Lorenz said. "We have only imaged about half of Titan's surface, and multiple 'looks' or special observations are needed to estimate the surface heights. If you divided Titan into 1-degree by 1-degree [latitude and longitude] squares, only 11 percent of those squares have topography data in them."

To create the first global, topographic map of Saturn’s moon Titan, scientists analyzed data from NASA's Cassini spacecraft and a mathematical process called splining. This method effectively uses smooth curved surfaces to “join” the areas between grids of existing topography profiles obtained by Cassini's radar instrument. In the upper panel of this graphic, gold colors show where radar images have been obtained over almost half of Titan’s surface. Within the gold areas, narrow strips of rainbow colors show where height data have been obtained. Those data are laid over a blue-toned, near-global map of infrared color from the Cassini visual and infrared mapping spectrometer instrument. The lower panel shows the new topography map, with contour lines added at 656 feet (200 meters) apart in elevation. South polar depressions and four mountains are notably prominent; a dark region at 50 to 65 degrees south latitude and 0 to 60 degrees east longitude coincides with a major depression.  The radar and VIMS data were obtained from 2004 to 2011.

Lorenz's team used a mathematical process called splining - effectively using smooth, curved surfaces to "join" the areas between grids of existing data. "You can take a spot where there is no data, look how close it is to the nearest data, and use various approaches of averaging and estimating to calculate your best guess," he said. "If you pick a point, and all the nearby points are high altitude, you'd need a special reason for thinking that point would be lower. We're mathematically papering over the gaps in our coverage."

The estimations fit with current knowledge of the moon - that its polar regions are "lower" than areas around the equator, for example - but connecting those points allows scientists to add new layers to their studies of Titan's surface, especially those modeling how and where Titan's rivers flow, and the seasonal distribution of its methane rainfall. "The movement of sands and the flow of liquids are influenced by slopes, and mountains can trigger cloud formation and therefore rainfall. This global product now gives modelers a convenient description of this key factor in Titan's dynamic climate system," Lorenz said.

The most recent data used to compile the map is from 2012; Lorenz says it could be worth revising when the Cassini mission ends in 2017, when more data will have accumulated, filling some of the gaps in present coverage. "We felt we couldn't wait and should release an interim product," he says. "The community has been hoping to get this for a while. I think it will stimulate a lot of interesting work."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and ASI, the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.

Contacts and sources:
Jia-Rui Cook
Jet Propulsion Laboratory

Blond Monkey Has Incredible Human Looking Face: Lesula, A New Species of Cercopithecus Monkey Endemic to the Democratic Republic of Congo

The scientific discovery of Cercopithecus lomamiensis was made in June 2007 when field teams saw a captive juvenile female of an unknown species at the residence of the primary school director in the town of Opala (S 0.50721°, E 24.22713°). The school director identified the animal as a “lesula” a vernacular name we had not recorded before, and said that it is well known by local hunters. He reported that he acquired the infant about two months earlier from a family member who had killed its mother in the forest near Yawende, south of Opala and west of the Lomami River (S 0.99772°, E 24.29810°). We took photographs of the animal and made arrangements for its care. We observed and photographed this animal regularly over the next 18 months.
New species of Cercopithecus Monkey discovered in  the Democratic Republic of Congo


Subsequent searches in Opala and in the Yawende area turned up other male and female captive juvenile lesula; all were photographed and some monitored for several months afterwards. The researchers first observation of the species in the wild was in the Obenge area (S 1.38461°, E 25.03749°) in December 2007 where the species is well known by local hunters.
Juvenile Lesula monkeys

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Captive Cercopithecus lomamiensis.

Citation: Cercopithecus lomamiensis J.Hart, Detwiler, Gilbert, Burrell, Fuller, Emetshu, T.Hart, Vosper, Sargis, and Tosi, sp. nov. urn:lsid:zoobank.org:act:8BA96F42-16A5-4​6B6-A194-B3DB0B2711B7.

World's Smallest Droplets

Physicists may have created the smallest drops of liquid ever made in the lab.

That possibility has been raised by the results of a recent experiment conducted by Vanderbilt physicist Julia Velkovska and her colleagues at the Large Hadron Collider, the world’s largest and most powerful particle collider located at the European Laboratory for Nuclear and Particle Physics (CERN) in Switzerland. Evidence of the minuscule droplets was extracted from the results of colliding protons with lead ions at velocities approaching the speed of light.

Credit: Istock

According to the scientists’ calculations, these short-lived droplets are the size of three to five protons. To provide a sense of scale, that is about one-100,000th the size of a hydrogen atom or one-100,000,000th the size of a virus.

“With this discovery, we seem to be seeing the very origin of collective behavior,” said Velkovska, professor of physics at Vanderbilt who serves as a co-convener of the heavy ion program of the CMS detector, the LHC instrument that made the unexpected discovery. “Regardless of the material that we are using, collisions have to be violent enough to produce about 50 sub-atomic particles before we begin to see collective, flow-like behavior.”

These tiny droplets “flow” in a manner similar to the behavior of the quark-gluon plasma, a state of matter that is a mixture of the sub-atomic particles that makes up protons and neutrons and only exists at extreme temperatures and densities. Cosmologists propose that the entire universe once consisted of this strongly interacting elixir for fractions of a second after the Big Bang when conditions were dramatically hotter and denser than they are today. Now that the universe has spent billions of years expanding and cooling, the only way scientists can reproduce this primordial plasma is to bang atomic nuclei together with tremendous energy.

A three-dimensional view of a p-Pb collision that produced collective flow behavior. The green lines are the trajectories of the sub-atomic particles produced by the collision reconstructed by the CMS tracking system. The red and blue bars represent the energy measured by the instrument's two sets of calorimeters.

 CMS Collaboration

The new observations are contained in a paper submitted by the CMS collaboration to the journal Physics Letters B and posted on the arXiv preprint server. In addition, Vanderbilt doctoral student Shengquan Tuo recently presented the new results at a workshop held in the European Centre for Theoretical Studies in Nuclear Physics and Related Areas in Trento, Italy.

Scientists have been trying to recreate the quark-gluon plasma since the early 2000s by colliding gold nuclei using the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. This exotic state of matter is created when nuclei collide and dump a fraction of their energy into the space between them. When enough energy is released, it causes some of the quarks and gluons in the colliding particles to melt together to form the plasma. The RHIC scientists had expected the plasma to behave like a gas, but were surprised to discover that it acts like a liquid instead.

When the LHC started up, the scientists moved to the more powerful machine where they basically duplicated the results they got at RHIC by colliding lead nuclei.

In what was supposed to be a control run to check the validity of their lead-lead results, the scientists scheduled the collider to smash protons and lead nuclei together. They didn’t expect to see any evidence of the plasma. Because the protons are so much lighter than lead nuclei (they have only one-208th the mass), it was generally agreed that proton-lead collisions couldn’t release enough energy to produce the rare state of matter.

“The proton-lead collisions are something like shooting a bullet through an apple while lead-lead collisions are more like smashing two apples together: A lot more energy is released in the latter,” said Velkovska.

Shengquan Tuo, right, Julia Velkovska and graduate student Dillon Roach in Vanderbilt's CMS Center, a room set up with telecommunications equipment that allows them to monitor of the detector's performance and directly download data.

  Courtesy of Physics Department / Vanderbilt

Last September, the LHC did a brief test run to make sure it was adjusted properly to handle proton-lead collisions. When the results of the run were analyzed, team members were surprised to see evidence of collective behavior in five percent of the collisions—those that were the most violent. In these cases, it appeared that when the “bullet” passed through “apple” it released enough energy to melt some of the particles surrounding the bullet hole. They appeared to be forming liquid droplets about one tenth the size of those produced by the lead-lead or gold-gold collisions.

However, the initial analysis was limited to tracking the motion of pairs of particles. The researchers knew that this analysis could be influenced by another well-known phenomenon, the production of particle jets. So, when the scheduled proton-lead run took place in January and February, they searched the data for evidence of groups of four particles that exhibit collective motion. After analyzing several billion events, they found hundreds of cases where the collisions produced more than 300 particles flowing together.

According to Tuo, only two models were advanced to explain their observations at the workshop. Of the two, the plasma droplet model seems to fit the observations best. In fact, he reported that the new data is forcing the authors of the competing model – color glass condensate, which attributes the particle correlations to the internal gluon structure of the protons themselves – to incorporate hydrodynamic effects, meaning that it is also describing the phenomenon as liquid droplets.

U.S. members of the CMS collaboration are supported primarily by the U.S. Department of Energy and National Science Foundation.


Contacts and sources:
David Salisbury
Vanderbilt University

New Discovery Of Ancient Diet Shatters Conventional Ideas Of How Agriculture Emerged

Use of new analysis techniques provides food for thought about how people lived 5,000 years ago


Archaeologists have made a discovery in southern subtropical China which could revolutionise thinking about how ancient humans lived in the region.

They have uncovered evidence for the first time that people living in Xincun 5,000 years ago may have practised agriculture –before the arrival of domesticated rice in the region.

This is Dr Mingqi Li sampling one of the pebble tools for ancient starch using an ultrasonic bath, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences in Beijing.

Credit: Dr. Huw Barton

Current archaeological thinking is that it was the advent of rice cultivation along the Lower Yangtze River that marked the beginning of agriculture in southern China. Poor organic preservation in the study region, as in many others, means that traditional archaeobotany techniques are not possible.

Now, thanks to a new method of analysis on ancient grinding stones, the archaeologists have uncovered evidence that agriculture could predate the advent of rice in the region.

The research was the result of a two-year collaboration between Dr Huw Barton, from the School of Archaeology and Ancient History at the University of Leicester, and Dr Xiaoyan Yang, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, in Beijing.

Funded by a Royal Society UK-China NSFC International Joint Project, and other grants held by Yang in China, the research is published in PLOS ONE.

This shows the Xincun site under excavation, a) Neolithic living surface under cleaning.

Credit: Dr Jun Wei

Dr Barton, Senior Lecturer in Bioarchaeology at the University of Leicester, described the find as 'hitting the jackpot': "Our discovery is totally unexpected and very exciting.

"We have used a relatively new method known as ancient starch analysis to analyse ancient human diet. This technique can tell us things about human diet in the past that no other method can.

"From a sample of grinding stones we extracted very small quantities of adhering sediment trapped in pits and cracks on the tool surface. From this material, preserved starch granules were extracted with our Chinese colleagues in the starch laboratory in Beijing. These samples were analysed in China and also here at Leicester in the Starch and Residue Laboratory, School of Archaeology and Ancient History.

"Our research shows us that there was something much more interesting going on in the subtropical south of China 5,000 years ago than we had first thought. The survival of organic material is really dependent on the particular chemical properties of the soil, so you never know what you will get until you sample. At Xincun we really hit the jackpot. Starch was well-preserved and there was plenty of it. While some of the starch granules we found were species we might expect to find on grinding and pounding stones, ie. some seeds and tuberous plants such as freshwater chestnuts, lotus root and the fern root, the addition of starch from palms was totally unexpected and very exciting."

This is a map of the study region in southern China (A), Xincun site indicated by red triangle (B), and details of the Xincun site including excavation areas marked by red grids, stippling shows location of coastal sand dunes (C).

Credit: Xiaoyan Yang

Several types of tropical palms store prodigious quantities of starch. This starch can be literally bashed and washed out of the trunk pith, dried as flour, and of course eaten. It is non-toxic, not particularly tasty, but it is reliable and can be processed all year round. Many communities in the tropics today, particularly in Borneo and Indonesia, but also in eastern India, still rely on flour derived from palms.

Dr Barton said: "The presence of at least two, possibly three species of starch producing palms, bananas, and various roots, raises the intriguing possibility that these plants may have been planted nearby the settlement.

"Today groups that rely on palms growing in the wild are highly mobile, moving from one palm stand to another as they exhaust the clump. Sedentary groups that utilise palms for their starch today, plant suckers nearby the village, thus maintaining continuous supply. If they were planted at Xincun, this implies that 'agriculture' did not arrive here with the arrival of domesticated rice, as archaeologists currently think, but that an indigenous system of plant cultivation may have been in place by the mid Holocene.

"The adoption of domesticated rice was slow and gradual in this region; it was not a rapid transformation as in other places. Our findings may indicate why this was the case. People may have been busy with other types of cultivation, ignoring rice, which may have been in the landscape, but as a minor plant for a long time before it too became a food staple.

"Future work will focus on grinding stones from nearby sites to see if this pattern is repeated along the coast."
Contacts and sources:
Dr. Huw Barton
University of Leicester

Stacking 2-D Materials Produces Surprising Results

New experiments reveal previously unseen effects, could lead to new kinds of electronics and optical devices.

Graphene has dazzled scientists, ever since its discovery more than a decade ago, with its unequalled electronic properties, its strength and its light weight. But one long-sought goal has proved elusive: how to engineer into graphene a property called a band gap, which would be necessary to use the material to make transistors and other electronic devices.

Now, new findings by researchers at MIT are a major step toward making graphene with this coveted property. The work could also lead to revisions in some theoretical predictions in graphene physics.

From left: Prof. Ray Ashoori, postdocs Andrea Young and Ben Hunt, graduate student Javier Sanchez-Yamagishi, and Prof. Pablo Jarillo-Herrero.

Photo: Jarillo-Herrero and Ashoori groups

The new technique involves placing a sheet of graphene — a carbon-based material whose structure is just one atom thick — on top of hexagonal boron nitride, another one-atom-thick material with similar properties. The resulting material shares graphene’s amazing ability to conduct electrons, while adding the band gap necessary to form transistors and other semiconductor devices.

The work is described in a paper in the journal Science co-authored by Pablo Jarillo-Herrero, the Mitsui Career Development Assistant Professor of Physics at MIT, Professor of Physics Ray Ashoori, and 10 others.

“By combining two materials,” Jarillo-Herrero says, “we created a hybrid material that has different properties than either of the two.”

Graphene is an extremely good conductor of electrons, while boron nitride is a good insulator, blocking the passage of electrons. “We made a high-quality semiconductor by putting them together,” Jarillo-Herrero explains. Semiconductors, which can switch between conducting and insulating states, are the basis for all modern electronics.

To make the hybrid material work, the researchers had to align, with near perfection, the atomic lattices of the two materials, which both consist of a series of hexagons. The size of the hexagons (known as the lattice constant) in the two materials is almost the same, but not quite: Those in boron nitride are 1.8 percent larger. So while it is possible to line the hexagons up almost perfectly in one place, over a larger area the pattern goes in and out of register.

At this point, the researchers say they must rely on chance to get the angular alignment for the desired electronic properties in the resulting stack. However, the alignment turns out to be correct about one time out of 15, they say.

“The qualities of the boron nitride bleed over into the graphene,” Ashoori says. But what’s most “spectacular,” he adds, is that the properties of the resulting semiconductor can be “tuned” by just slightly rotating one sheet relative to the other, allowing for a spectrum of materials with varied electronic characteristics.

Others have made graphene into a semiconductor by etching the sheets into narrow ribbons, Ashoori says, but such an approach substantially degrades graphene’s electrical properties. By contrast, the new method appears to produce no such degradation.

The band gap created so far in the material is smaller than that needed for practical electronic devices; finding ways of increasing it will require further work, the researchers say.

“If … a large band gap could be engineered, it could have applications in all of digital electronics,” Jarillo-Herrero says. But even at its present level, he adds, this approach could be applied to some optoelectronic applications, such as photodetectors.

The results “surprised us pleasantly,” Ashoori says, and will require some explanation by theorists. Because of the difference in lattice constants of the two materials, the researchers had predicted that the hybrid’s properties would vary from place to place. Instead, they found a constant, and unexpectedly large, band gap across the whole surface.

In addition, Jarillo-Herrero says, the magnitude of the change in electrical properties produced by putting the two materials together “is much larger than theory predicts.”

The MIT team also observed an interesting new physical phenomenon. When exposed to a magnetic field, the material exhibits fractal properties — known as a Hofstadter butterfly energy spectrum — that were described decades ago by theorists, but thought impossible in the real world. There is intense research in this area; two other research groups also report on these Hofstadter butterfly effects this week in the journal Nature.

The research included postdocs Ben Hunt and Andrea Young and graduate student Javier Sanchez-Yamagishi, as well as six other researchers from the University of Arizona, the National Institute for Materials Science in Tsukuba, Japan, and Tohoku University in Japan. The work was funded by the U.S. Department of Energy, the Gordon and Betty Moore Foundation and the National Science Foundation.
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Contacts and sources:
Sarah McDonnell
Massachusetts Institute of Technology
Written by: David L. Chandler, MIT News Office

How Should Geophysics Contribute To Disaster Planning?

Identifying natural hazards is only a part of what the field should do, analysis suggests, and effective disaster risk reduction strategies integrate many different experts on community level

Earthquakes, tsunamis, and other natural disasters often showcase the worst in human suffering – especially when those disasters strike populations who live in rapidly growing communities in the developing world with poorly enforced or non-existent building codes.'

Taken at Ao Nang, Krabi Province, Thailand, during the 2004 Indian Ocean earthquake and tsunami in Thailand

Credit: Wikipedia

This week in Cancun, a researcher from Yale-National University of Singapore (NUS) College in Singapore is presenting a comparison between large-scale earthquakes and tsunamis in different parts of the world, illustrating how nearly identical natural disasters can play out very differently depending on where they strike.

The aim of the talk at the 2013 Meeting of the Americas, which is sponsored by the American Geophysical Union (AGU), is to focus on the specific role geoscientists can play in disaster risk reduction and how their work should fit in with the roles played by other experts for any given community.

"To reduce the losses from these disasters, a diverse group of researchers, engineers, and policy makers need to come together to benefit from each other's expertise," said Brian McAdoo, professor of science at Yale-NUS College. "Geophysicists play a crucial role in natural hazard identification and determining the key questions of, how often does a geophysical hazard affect a given area and how big will it be when it hits?" McAdoo said. "We need to be aware of how this information is incorporated into the disaster planning architecture."

San Francisco, Haiti, and New Zealand

In his talk, McAdoo will present case studies that he and his colleague Vivienne Bryner compiled comparing death counts and economic fallout following geophysical events of similar magnitude in areas with different levels of economic development.

What their analysis shows is that deaths tend to be higher in poor countries exposed to severe natural disasters because of existing socioeconomic, environmental, and structural vulnerabilities. At the same time, economic losses tend to be higher in developed nations, but developing countries may be less able to absorb those economic losses that do occur.

As an example, he points to the earthquakes that hit Haiti, San Francisco, and Christchurch and Canterbury, New Zealand, in 2010, 1989 and 2010-2011. While the quakes were nearly identical in magnitude, the consequences of these natural disasters were remarkably different.

Some 185 people died in the 2011 Canterbury earthquake, which was preceded by the larger Christchurch quake in 2010 in which nobody died. Both quakes and their aftershocks cost New Zealand about $6.5 billion, which was approximately 10-20 percent of its gross domestic product (GDP). The 1989 San Francisco earthquake killed 63 people, and it cost $5.6 billion (the equivalent of about $10 billion in 2010 dollars). The U.S. economy is so large, however, that it only caused a one-tenth of one percent drop in U.S. GDP. The 2011 earthquake in Haiti, on the other hand, killed some 200,000 people and resulted in economic losses approaching an estimated $8 billion, which is more than 80 percent of Haiti's GDP.

To address such disparities, McAdoo advocates what is known as Disaster Risk Reduction (DRR) decision making – a framework for finding solutions to best prepare for natural disasters, lessen their impact, and sensibly engage in post-disaster reconstruction. For such planning to work, he said, it must be broad-based.

"We won't ever be able to prevent disasters," he said. "The only way we will effectively minimize the effects of hazards is to collaborate across academic disciplines, businesses, governments, NGOs, and perhaps most critically the exposed community."

"Planning for any sort of natural disaster takes insight into what may be expected, which necessarily includes the important perspective of scientists," added Philip ("Bo") Hammer, Associate Vice President for Physics Resources at the American Institute of Physics (AIP) and co-organizer of the session in which McAdoo is speaking. "One reason why we organized this session in the first place was to encourage the sharing of such perspectives within the context of how geophysicists can build local capacity, not only for dealing with acute issues such as disasters, but also longer term challenges like building capacity for economic growth."

The talk, "Building Capacity for Disaster Risk Reduction," will be presented by Brian G. McAdoo and Vivienne Bryner on Friday, May 17, 2013, at the 2013 Meeting of the Americas in Cancún, Mexico. McAdoo is affiliated with Yale-NUS College in Singapore, and Bryner is at University of Otago in Dunedin, New Zealand.



Contacts and sources:
Jason Socrates Bardi
American Institute of Physics

Nanotechnology Could Help Fight Diabetes

Injectable nanogel can monitor blood-sugar levels and secrete insulin when needed.CAMBRIDGE, Mass. — Injectable nanoparticles developed at MIT may someday eliminate the need for patients with Type 1 diabetes to constantly monitor their blood-sugar levels and inject themselves with insulin.

The nanoparticles were designed to sense glucose levels in the body and respond by secreting the appropriate amount of insulin, thereby replacing the function of pancreatic islet cells, which are destroyed in patients with Type 1 diabetes. Ultimately, this type of system could ensure that blood-sugar levels remain balanced and improve patients’ quality of life, according to the researchers.

“Insulin really works, but the problem is people don’t always get the right amount of it. With this system of extended release, the amount of drug secreted is proportional to the needs of the body,” says Daniel Anderson, an associate professor of chemical engineering and member of MIT’s Koch Institute for Integrative Cancer Research and Institute for Medical Engineering and Science.

Anderson is the senior author of a paper describing the new system in a recent issue of the journal ACS Nano. Lead author of the paper is Zhen Gu, a former postdoc in Anderson’s lab. The research team also includes Robert Langer, the David H. Koch Institute Professor at MIT, and researchers from the Department of Anesthesiology at Boston Children’s Hospital.

Mimicking the pancreas

Currently, people with Type 1 diabetes typically prick their fingers several times a day to draw blood for testing their blood-sugar levels. When levels are high, these patients inject themselves with insulin, which breaks down the excess sugar.

In recent years, many researchers have sought to develop insulin-delivery systems that could act as an “artificial pancreas,” automatically detecting glucose levels and secreting insulin. One approach uses hydrogels to measure and react to glucose levels, but those gels are slow to respond or lack mechanical strength, allowing insulin to leak out.

The MIT team set out to create a sturdy, biocompatible system that would respond more quickly to changes in glucose levels and would be easy to administer.

Their system consists of an injectable gel-like structure with a texture similar to toothpaste, says Gu, who is now an assistant professor of biomedical engineering and molecular pharmaceutics at the University of North Carolina at Chapel Hill and North Carolina State University. The gel contains a mixture of oppositely charged nanoparticles that attract each other, keeping the gel intact and preventing the particles from drifting away once inside the body.

Using a modified polysaccharide known as dextran, the researchers designed the gel to be sensitive to acidity. Each nanoparticle contains spheres of dextran loaded with an enzyme that converts glucose into gluconic acid. Glucose can diffuse freely through the gel, so when sugar levels are high, the enzyme produces large quantities of gluconic acid, making the local environment slightly more acidic.

That acidic environment causes the dextran spheres to disintegrate, releasing insulin. Insulin then performs its normal function, converting the glucose in the bloodstream into glycogen, which is absorbed into the liver for storage.

Long-term control

In tests with mice that have Type 1 diabetes, the researchers found that a single injection of the gel maintained normal blood-sugar levels for an average of 10 days. Because the particles are mostly composed of polysaccharides, they are biocompatible and eventually degrade in the body.

The researchers are now trying to modify the particles so they can respond to changes in glucose levels faster, at the speed of pancreas islet cells. “Islet cells are very smart. They can release insulin very quickly once they sense high sugar levels,” Gu says.

Before testing the particles in humans, the researchers plan to further develop the system’s delivery properties and to work on optimizing the dosage that would be needed for use in humans.

The research was funded by the Leona M. and Harry B. Helmsley Charitable Trust and the Tayebati Family Foundation.


Contacts and sources:
Sarah McDonnell
Massachusetts Institute of Technology

Written by: Anne Trafton, MIT News Office

70's-Era Physics Prediction Finally Confirmed

New CCNY professor part of team confirming Hofstadter Butterfly in graphene

City College of New York Assistant Professor of Physics Cory Dean, who recently arrived from Columbia University where he was a post-doctoral researcher, and research teams from Columbia and three other institutions have definitively proven the existence of an effect known as Hofstadter’s Butterfly.

The phenomenon, a complex pattern of the energy states of electrons that resembles a butterfly, has appeared in physics textbooks as a theoretical concept of quantum mechanics for nearly 40 years. However, it had never been directly observed until now. Confirming its existence may open the door for researchers to uncover completely unknown electrical properties of materials.

Artist's illustration of a butterfly as if departing from a moire pattern in graphene formed on top of a sheet of boron nitride. 

Credit: James Hedberg

“We are now standing at the edge of an entirely new frontier in terms of exploring properties of a system that have never before been realized,” said Professor Dean, who developed the material that allowed the observation. "The ability to generate this effect could possibly be exploited to design new electronic and optoelectronic devices."

The international group, which also included the University of Central Florida, the National High Magnetic Field Laboratory, and Japan’s Tohoku University and National Institute for Materials Science, published its findings in the journal Nature; they appeared in an advance online publicationMay 15. Separate groups at the University of Manchester (UK) and Massachusetts Institute of Technology simultaneously reported similar results.

Douglas Hofstadter, a physicist and Pulitzer Prize-winning author, first predicted the existence of the butterfly in 1976, when he imagined what would happen to electrons subjected to two forces simultaneously: a magnetic field and the periodic electric field.

The energy spectrum, or pattern of energy levels, that these dueling forces create is said to be “fractal,” that is, infinitely smaller versions of the pattern appear within the main one. This effect is common in classical physics, but rare in the quantum world.

“When you plot the spectrum, it takes on the form of a butterfly. Zoom in on the spectrum and you see the butterfly again, zoom in and see butterfly again,” said Professor Dean. The light and dark sections of the pattern, respectively, correspond to light “gaps” in energy level that electrons cannot cross and dark areas where they can move freely.

“The existence of gaps changes the way electrons move through a material. Copper for example, has no gaps, whereas an insulator, like glass, has very large gaps,” explained Professor Dean. “The relationship between energy and how dense the electrons are in a material – energy density – determines all electrical properties. That’s why copper conducts, glass or ceramic doesn’t, and other materials weakly conduct, like semiconductors.”

“What you see in a Hofstadter spectrum is a very complicated structure of gaps arranged in a fractal pattern,” he continued, which suggests as yet unknown electrical properties.

The team produced the effect by sandwiching together flat sheets of graphene – a single-atom-thickness of carbon – and another material, called boron nitride, and twisting them against each other to create what is called a superlattice. “Graphene has hexagonal chicken wire structure and boron nitride does too,” he said. “It is as if you take screen door material and put one sheet on top of other. As you rotate it you see a periodic pattern appear. You get an interference effect – a ‘moiré’ pattern.” In the case of the chicken-wire structure of graphene and boron nitride, the pattern forms a fractal butterfly of energy states.

“This is a very good example of fundamental discovery that opens doors that we don’t even know about yet. Why go to a distant planet?” Professor Dean wondered, about the implications of the work. “We go there to discover what’s out there. We don’t yet know what this new world will result in and what will emerge out of this.”


Contacts and sources:
Jessa Netting
City College of New York

Citation: C. R. Dean, Hofstadter’s butterfly and the fractal quantum Hall effect in moiré superlattices, Nature, May 15, 2013 doi:10.1038/nature12186

New Study Recommends Using Active Videogaming ('Exergaming') To Improve Children's Health

Levels of physical inactivity and obesity are very high in children, with fewer than 50% of primary school-aged boys and fewer than 28% of girls meeting the minimum levels of physical activity required to maintain health. 

Exergaming, using active console video games that track player movement to control the game (e.g., Xbox-Kinect, Wii), has become popular, and may provide an alternative form of exercise to counteract sedentary behaviors. In a study scheduled for publication in The Journal of Pediatrics, researchers studied the effects of exergaming on children.

Kinect Sports – 200m Hurdles

Dr. Louise Naylor and researchers from The University of Western Australia, Liverpool John Moores University, and Swansea University evaluated 15 children, 9-11 years of age, who participated in 15 minutes each of high intensity exergaming (Kinect Sports – 200m Hurdles), low intensity exergaming (Kinect Sports – Ten Pin Bowling), and a graded exercise test (treadmill). The researchers measured energy expenditure. They also measured the vascular response to each activity using flow-mediated dilation (FMD), which is a validated measure of vascular function and health in children.

They found that high intensity exergaming elicited an energy expenditure equivalent to moderate intensity exercise; low intensity exergaming resulted in an energy expenditure equivalent to low intensity exercise. Additionally, although the low intensity exergaming did not have an impact on FMD, high intensity exergaming significantly decreased FMD, suggesting that the latter may improve vascular health in children. High intensity exergaming also increased heart rate and the amount of energy burned. Participants reported similar enjoyment levels with both intensities of exergaming, which indicates that children may be equally likely to continue playing the high intensity games.

According to Dr. Naylor, "Higher intensity exergaming may be a good form of activity for children to use to gain long-term and sustained health benefits." These findings also support the growing notion that high intensity activity is beneficial for children's health, and high intensity exergaming should be considered a means of encouraging children to become more active.


Contacts and sources:
Becky Lindeman
Elsevier Health Sciences

New World Record in Wireless Data Transmission

Researchers of the Fraunhofer Institute for Applied Solid State Physics and the Karlsruhe Institute for Technology have achieved the wireless transmission of 40 Gbit/s at 240 GHz over a distance of one kilometer. Their most recent demonstration sets a new world record and ties in seamlessly with the capacity of optical fiber transmission. In the future, such radio links will be able to close gaps in providing broadband internet by supplementing the network in rural areas and places which are difficult to access.

A distance of over one kilometer has already been covered by using a long range demonstrator between two skyscrapers in Karlsruhe. 

Photo: Ulrich Lewark / KIT

Digital, mobile and networked – changing media usage habits of modern society require the faster transmission of increasing volumes of data. Compared to the European standard, Germany lags behind in the expansion of the fiber-optic network, according to statistics from the FTTH Council Europe. Deploying new fiber-optic cables is expensive and difficult when there are natural or urban obstacles such as rivers or traffic junctions. Broadband radio links can help to overcome such critical areas, thereby facilitating the expansion of the network infrastructures. In rural areas they can be a cost-effective and flexible alternative to “Fiber to the Home”.

Researchers have now set a new world record in wireless data transmission: For the first time, fully integrated electronic transmitters and receivers have been developed for a frequency of 240 GHz, which allows the transmission of data rates of up to 40 Gbit/s. This equals the transmission of a complete DVD in under a second or 2400 DSL16000 internet connections. Distances of over one kilometer have already been covered by using a long range demonstrator, which the Karlsruhe Institute of Technology set up between two skyscrapers as part of the project “Millilink”. “We have managed to develop a radio link based on active electronic circuits, which enables similarly high data rates as in fiber-optic systems, therefore allowing seamless integration of the radio link”, says Prof. Ingmar Kallfass, who coordinated the project at Fraunhofer IAF within the scope of a Shared Professorship between IAF and KIT. Since 2013, Kallfass is with the University of Stuttgart, where he continues to lead the project.

High Frequencies enable Fast Data Transmission

Using the high frequency range between 200 and 280 GHz not only enables the fast transmission of large volumes of data, but also results in very compact technical assembly. Since the size of electronic circuits and antennae scales with frequency / wavelength, the transmitter and receiver chip only measures 4 x 1.5 mm². The semiconductor technology developed at Fraunhofer IAF, based on transistors with high carrier mobility (HEMT), makes it possible to use the frequency between 200 and 280 GHz with active transmitters and receivers in the form of compact, integrated circuits. The atmosphere shows low attenuation in this frequency range, which enables broadband directional radio links. “This makes our radio link easier to install compared to free-space optical systems for data transmission. It also shows better robustness in poor weather conditions such as fog or rain”, explains Jochen Antes of KIT.

The high frequency chip only measures 4 x 1.5 mm², as the size of electronic devices scales with frequency / wavelength. 

Photo: Sandra Iselin / Fraunhofer IAF

Up to now, radio links were not able to directly transmit the data rates of glass fiber. This might change in the future, as the test setup of the project shows. Such a high performance system would also have the advantage of the so-called bit transparency, i.e. the signal of a glass fiber could be fed directly and without energy-consuming transcoding into a radio link. It could then be transmitted and redirected into a glass fiber. The record data from the test setup is only the beginning. “Improving the spectral efficiency by using more complex modulation formats or a combination of several channels, i.e. multiplexing, will help to achieve even higher data rates”, says Antes. This could give new impetus to the expansion of the broadband network. Maybe Germany will then no longer occupy the lower ranks compared to the rest of Europe.


Contacts and sources:

 Karlsruhe Institute of Technology

Beautiful 'Flowers' Self-Assemble In A Beaker

"Spring is like a perhaps hand," wrote the poet E. E. Cummings: "carefully / moving a perhaps / fraction of flower here placing / an inch of air there... / without breaking anything."

With the hand of nature trained on a beaker of chemical fluid, the most delicate flower structures have been formed in a Harvard laboratory—and not at the scale of inches, but microns.

These false-color SEM images reveal microscopic flower structures created by manipulating a chemical gradient to control crystalline self-assembly. (Image courtesy of Wim L. Noorduin.)

Credit: Harvard School of Engineering and Applied Sciences

These minuscule sculptures, curved and delicate, don't resemble the cubic or jagged forms normally associated with crystals, though that's what they are. Rather, fields of carnations and marigolds seem to bloom from the surface of a submerged glass slide, assembling themselves a molecule at a time.

By simply manipulating chemical gradients in a beaker of fluid, Wim L. Noorduin, a postdoctoral fellow at the Harvard School of Engineering and Applied Sciences (SEAS) and lead author of a paper appearing on the cover of the May 17 issue of Science, has found that he can control the growth behavior of these crystals to create precisely tailored structures.

"For at least 200 years, people have been intrigued by how complex shapes could have evolved in nature. This work helps to demonstrate what’s possible just through environmental, chemical changes," says Noorduin.

The precipitation of the crystals depends on a reaction of compounds that are diffusing through a liquid solution. The crystals grow toward or away from certain chemical gradients as the pH of the reaction shifts back and forth. The conditions of the reaction dictate whether the structure resembles broad, radiating leaves, a thin stem, or a rosette of petals.

It is not unusual for chemical gradients to influence growth in nature; for example, delicately curved marine shells form from calcium carbonate under water, and gradients of signaling molecules in a human embryo help set up the plan for the body. Similarly, Harvard biologist Howard Berg has shown that bacteria living in colonies can sense and react to plumes of chemicals from one another, which causes them to grow, as a colony, into intricate geometric patterns.

Replicating this type of effect in the laboratory was a matter of identifying a suitable chemical reaction and testing, again and again, how variables like the pH, temperature, and exposure to air might affect the nanoscale structures.

The project fits right in with the work of Joanna Aizenberg, an expert in biologically inspired materials science, biomineralization, and self-assembly, and principal investigator for this research.

Aizenberg is the Amy Smith Berylson Professor of Materials Science at Harvard SEAS, Professor of Chemistry and Chemical Biology in the Harvard Department of Chemistry and Chemical Biology, and a Core Faculty Member of the Wyss Institute for Biologically Inspired Engineering at Harvard.

Her recent work has included the invention of an extremely slippery material, inspired by the pitcher plant, and the discovery of how bacteria use their flagella to cling to the surfaces of medical implants.

"Our approach is to study biological systems, to think what they can do that we can’t, and then to use these approaches to optimize existing technologies or create new ones," says Aizenberg. "Our vision really is to build as organisms do."

To create the flower structures, Noorduin and his colleagues dissolve barium chloride (a salt) and sodium silicate (also known as waterglass) into a beaker of water. Carbon dioxide from air naturally dissolves in the water, setting off a reaction which precipitates barium carbonate crystals. As a byproduct, it also lowers the pH of the solution immediately surrounding the crystals, which then triggers a reaction with the dissolved waterglass. This second reaction adds a layer of silica to the growing structures, uses up the acid from the solution, and allows the formation of barium carbonate crystals to continue.

"You can really collaborate with the self-assembly process," says Noorduin. "The precipitation happens spontaneously, but if you want to change something then you can just manipulate the conditions of the reaction and sculpt the forms while they're growing."

Increasing the concentration of carbon dioxide, for instance, helps to create 'broad-leafed' structures. Reversing the pH gradient at the right moment can create curved, ruffled structures.

Noorduin and his colleagues have grown the crystals on glass slides and metal blades; they've even grown a field of flowers in front of President Lincoln's seat on a one-cent coin.

"When you look through the electron microscope, it really feels a bit like you’re diving in the ocean, seeing huge fields of coral and sponges," describes Noorduin. "Sometimes I forget to take images because it's so nice to explore."

In addition to her roles at Harvard SEAS, the Department of Chemistry and Chemical Biology, and the Wyss Institute, Joanna Aizenberg is Director of the Kavli Institute for Bionano Science and Technology at Harvard and Director of the Science Program at the Radcliffe Institute for Advanced Study.

Coauthors included Alison Grinthal, a research scientist at Harvard SEAS, and L. Mahadevan, who is the Lola England de Valpine Professor of Applied Mathematics at SEAS, Professor of Organismic and Evolutionary Biology and of Physics, and a Core Faculty Member at the Wyss Institute.

The project was supported by National Science Foundation grants to the Harvard Materials Research Science and Engineering Center (DMR-0820484) and the Harvard Center for Nanoscale Systems (ECS-0335765); and by the Netherlands Organization for Scientific Research.

Contacts and sources:Harvard School of Engineering and Applied Sciences


Citation: Wim L. Noorduin, et al., "Rationally designed complex, hierarchical micro-architectures," SCIENCE, May 17, 2013.

Asian Invasion: Biological Warfare By Multicolored Asian Lady Beetles

Multicolored Asian lady beetles are advancing round the globe, often driving out native species in many of the countries they invade, and their methods amount to no less than biological warfare: they infect their opponents with deadly parasites against which they themselves are immune. This was revealed in a study conducted by Fraunhofer IME, published in the current edition of Science Magazine, the academic journal of the American Association for the Advancement of Science.

From the human point of view, ladybugs are harmless creatures that are not only pretty to look at, but that also serve a useful purpose, as their diet includes aphids and other botanical pests. The multicolored Asian lady beetle or Harlequin ladybird (also known as the Japanese ladybug, the Halloween ladybug or the Harlequin ladybird) is an especially voracious eater; this little glutton can munch its way through up to 200 aphids a day.

Its sizeable appetite led resourceful organic farmers to import Harlequin ladybird decades ago as a natural method of biological pest control. They initially introduced the insect onto fields and into greenhouses in North America before bringing it over to Europe – but from the 1990s onward, these little helpers started to become a problem in their own right. The beetle has reproduced uncontrollably, and is now considered a primary example of an invasive species.

The alien invaders also gained a foothold in Germany, where they are making life difficult for the 80 or so native ladybug species. This could have worrying consequences, as Professor Andreas Vilcinskas, biologist and joint head of the Institute for Phytopathology and Applied Zoology at Justus Liebig University Giessen, explains: “If things continue at this rate, many of these species will disappear.” 

Professor Vilcinskas also set up the Bioresources project group at the Fraunhofer Institute for Molecular Biology and Applied Ecology IME in 2010, an initiative that is funded to the tune of 4.5 million euros by the Land Hesse through the LOEWE research promotion program (“State offensive for the development of scientific and economic excellence”). “Our aim is to utilize the enormous potential that the insect world holds for us. Insects are an incredibly diverse species in possession of many bio- molecules that could have all manner of medicinal and biotechnological applications,” Vilcinskas adds.

Credit: www.ipm.iastate.edu -

Fraunhofer research scientists consider invasive species such as the multicolored Asian lady beetles to be very promising. “If a species is able to successfully spread across the planet, then it must have a very strong immune system, else it would not be able to withstand the various pathogens it encounters every time it enters a new habitat.” 

Comparing the invading beetle with two native species, the seven-spotted ladybug (Coccinella septempunctata) and the two-spotted ladybug (Adalia bipunctata), gives credence to the biolodist’s argument: laboratory tests indicate that the blood of the foreign insects has much greater activity against bacteria than the blood of both European species. Vilcinska’s team identified the active agent as harmonin, a substance that is exclusively produced by Harmonia. This substance proved to be an effective antibiotic that is capable of combatting tuberculosis and malaria pathogens, among others.

But harmonin is just one of many chemical weapons the multicolored Asian lady beetle uses to defend itself against microorganisms. Its armory also contains over 50 types of peptides with which it can fight off massive bacterial attacks, as revealed by Dr. Heiko Vogel’s in-depth molecular biological analyses conducted at the Max Planck Institute for Chemical Ecology in Jena. 

“This makes Harmonia a record breaker. We know of no other animal that produces so many antimicrobial peptides,” says Vilcinskas. This gives the interlopers a distinct competitive advantage over their seven-spotted rivals and other ladybugs. But having a strong immune system still doesn’t explain their incredible assertiveness – for these little fighters invariably come out on top when they go head-to-head with their local relatives, too.

Credit: University of Arkansas

A startling observation made by the Fraunhofer team led them to discover the real secret to Harmonia’s success. When competing for food and space in their natural habitat, it’s not unusual for ladybugs to eat their rivals’ larvae and eggs. If a seven-spotted ladybug tucks into the young of its exotic opponent, then it’s a deadly meal: the hungry native dies. When a multicolored Asian lady beetle gobbles up the offspring of its local relation, however, it suffers no ill side-effects whatsoever. The answer to the mystery is contained within the invaders’ blood, which is filled with spore-like parasites. Some 18 months of molecular biological detective work finally identified the organism as belonging to a group of fungi-like unicellular parasites called Nosema, a microsporidian.

“Since making the discovery, we have examined multicolored Asian lady beetles from all over the world. We found microsporidia in every single animal in every population, even in the eggs,” explains Vilcinskas. This means that whenever a seven-spotted ladybug eats a Harmonia egg, the insect is invariably infected with the pathogens the egg contains. The microsporadia multiply in their new host, and eventually kill it. Researchers at the IME do not yet know why the Asian ladybugs aren’t affected by the microsporidia they carry – but they’re hot on the heels of a promising lead, as Vilcinskas reveals: “Presumably the beetles protect themselves using harmonin. We think that they use it to limit the rate of microsporidia reproduction, thus keeping levels harmlessly low.”



Contacts and sources:

Prof. Dr. AndreasVilcinskas
Fraunhofer-Institut für Molekularbiologie und Angewandte Oekologie IME-MBFraunhofer-Gesellschaft

Changing Wave Heights Projected As The Atmosphere Warms

Climate scientists studying the impact of changing wave behavior on the world's coastlines are reporting a likely decrease in average wave heights across 25 per cent of the global ocean.

New study seeks to understand potential impacts on coasts from climate change driven wind-wave conditions.

In some of the first climate simulations of modelled wave conditions they also found a likely increase in wave height across seven per cent of the global ocean, predominantly in the Southern Ocean.

These findings are derived from a study which seeks to understand potential impacts on coasts from climate change driven wind-wave conditions. The study will be published in the print edition of the journal Nature Climate Change on 25 April.

"Waves are dominant drivers of coastal change in these sandy environments, and variability and change in the characteristics of surface ocean waves (sea and swell) can far exceed the influences of sea-level rise in such environments.Lead author, CSIRO researcher Dr Mark Hemer, said that 20 per cent of the world's coastlines are sandy beaches which are prone to natural or man-made changes. It is estimated that 10 per cent of these sandy coasts are becoming wider as they build seawards, 70 per cent are eroding and the remaining 20 per cent are stable. Around 50 per cent of Australia's coast is sand.

"If we wish to understand how our coasts might respond to future changes in climate then we need to try and understand how waves might respond to the projected changes in global atmospheric circulation seen as shifts in storm frequency, storm intensity and storm tracks," Dr Hemer stated.

Dr Hemer explained that coastal impacts of climate change studies have predominantly focused on the influence of sea-level rise and, until now, not focussed on how changing wave conditions will impact the coastal zone in a changing climate.

He said sea-level rise is likely to have considerable influence along much of the world's coastlines. However, with such poor understanding of how changes in waves and other coastal processes will also influence shoreline position, it is difficult to attribute a level of future risk to the coast under a warmer climate.

The study compared results from five research groups from Australia, the United States, Japan, Europe and Canada. Each group used different modelling approaches to develop future wave-climate scenarios.

"While we find agreement in projected change in some parts of the world's oceans, considerable uncertainty remains. We're continuing to quantify the dominant sources of variation with the latest generation of climate models which will be used in the up-coming Intergovernmental Panel on Climate Change reports," Dr Hemer said.

He said climate is one of several mostly human-driven factors influencing coastline change.


Contacts and sources:
CSIRO

CTRL+P: Printing Australia’s largest solar cells

Scientists have produced the largest flexible, plastic solar cells in Australia – 10 times the size of what they were previously able to – thanks to a new solar cell printer that has been installed at CSIRO.


Credit: CSIRO

The printer has allowed researchers from the Victorian Organic Solar Cell Consortium (VICOSC) – a collaboration between CSIRO, The University of Melbourne, Monash University and industry partners – to print organic photovoltaic cells the size of an A3 sheet of paper.

According to CSIRO materials scientist Dr Scott Watkins, printing cells on such a large scale opens up a huge range of possibilities for pilot applications.

Dr Scott Watkins holding a sheet of flexible solar cells.

"There are so many things we can do with cells this size," he says. "We can set them into advertising signage, powering lights and other interactive elements. We can even embed them into laptop cases to provide backup power for the machine inside."

The new printer, worth A$200,000, is a big step up for the VICOSC team. In just three years they have gone from making cells the size of a fingernail to cells 10cm square. Now with the new printer they have jumped to cells that are 30cm wide.

(L-R) Dr David Jones, Professor Andrew Holmes and Dr Scott Watkins.

"We're using the same techniques that you would use if you were screen printing an image on to a T-Shirt," he says.VICOSC project coordinator and University of Melbourne researcher Dr David Jones says that one of the great advantages of the group's approach is that they're using existing printing techniques, making it a very accessible technology.

Using semiconducting inks, the researchers print the cells straight onto paper-thin flexible plastic or steel. With the ability to print at speeds of up to ten metres per minute, this means they can produce one cell every two seconds.

As the researchers continue to scale up their equipment, the possibilities will become even greater.

"Eventually we see these being laminated to windows that line skyscrapers," Dr Jones says. "By printing directly to materials like steel, we'll also be able to embed cells onto roofing materials."

The organic photovoltaic cells, which produce 10–50 watts of power per square metre, could even be used to improve the efficiency of more traditional silicon solar panels.

"The different types of cells capture light from different parts of the solar spectrum. So rather than being competing technologies, they are actually very complementary," Dr Watkins says.

The scientists predict that the future energy mix for the world, including Australia, will rely on many non-traditional energy sources. "We need to be at the forefront of developing new technologies that match our solar endowment, stimulate our science and support local, high-tech manufacturing.

"While the consortium is focused on developing applications with current industrial partners there are opportunities to work with other companies through training programs or pilot-scale production trials," he says.

As part of the consortium, a complementary screen printing line is also being installed at nearby Monash University. Combined, they will make the Clayton Manufacturing and Materials Precinct one of the largest organic solar cell printing facilities in the world.

The Victorian Organic Solar Cell Consortium is a research collaboration between CSIRO, The University of Melbourne, Monash University, BlueScope Steel, Robert Bosch SEA, Innovia Films and Innovia Security. It is supported by the Victorian State Government and the Australian Government through the Australian Renewable Energy Agency.

The consortium has developed processes that use spray coating, reverse gravure and slot-dye coating as well as screen printing. The consortium has developed processes that can be used with a range of solvents, most of which are in common industrial use. In particular, the consortium has developed in-house inks that do not require chlorinated solvents.

Current module power output from printed devices is 10-50W per square metre. On smaller, lab-scale devices, power outputs equivalent to over 80W per square metre have been achieved. 

Lifetime testing of modules is ongoing, with current studies showing stable outdoor performance beyond six months. The consortium anticipates lifetimes of several years will be achievable in the near future.

The consortium is currently only purchasing materials on a research scale. When bought on a larger scale it is anticipated that component costs will be significantly lower and that pricing around A$1/W will be achievable.

Contacts and sources:
 VICOSC consortium
University of Melbourne
Dr David Jones |
Professor Andrew Holmes |

CSIRO
Dr Scott Watkins
Dr Gerry Wilson |

Video: Human Embryo Produced From Stem Cells, Human Skin Cells Reprogrammed To Produce Embryonic Stem Cells, Opens New Doors For Stem Cell Therapies

The breakthrough marks the first time human stem cells have been produced via nuclear transfer and follows several unsuccessful attempts by research groups worldwide

Scientists at Oregon Health & Science University and the Oregon National Primate Research Center (ONPRC) have successfully reprogrammed human skin cells to become embryonic stem cells capable of transforming into any other cell type in the body. It is believed that stem cell therapies hold the promise of replacing cells damaged through injury or illness. Diseases or conditions that might be treated through stem cell therapy include Parkinson’s disease, multiple sclerosis, cardiac disease and spinal cord injuries.

Donor egg cytoplasm containing skin cell nucleus

Credit; OHSU

The research breakthrough, led byShoukhrat Mitalipov, Ph.D., a senior scientist at ONPRC, follows previous success in transforming monkey skin cells into embryonic stem cells in 2007. This latest research will be published in the journal Cell online May 15 and in print June 6.

The technique used by Drs. Mitalipov,Paula Amato, M.D., and their colleagues in OHSU’s Division of Reproductive Endocrinology and Infertility, Department of Obstetrics & Gynecology, is a variation of a commonly used method called somatic cell nuclear transfer, or SCNT. It involves transplanting the nucleus of one cell, containing an individual’s DNA, into an egg cell that has had its genetic material removed. The unfertilized egg cell then develops and eventually produces stem cells.
Video of the cell manipulation process filmed using a microscope equipped with a video camera from OHSU Video on Vimeo.

“A thorough examination of the stem cells derived through this technique demonstrated their ability to convert just like normal embryonic stem cells, into several different cell types, including nerve cells, liver cells and heart cells. Furthermore, because these reprogrammed cells can be generated with nuclear genetic material from a patient, there is no concern of transplant rejection,” explained Dr. Mitalipov. “While there is much work to be done in developing safe and effective stem cell treatments, we believe this is a significant step forward in developing the cells that could be used in regenerative medicine.”

Another noteworthy aspect of this research is that it does not involve the use of fertilized embryos, a topic that has been the source of a significant ethical debate.

The Mitalipov team’s success in reprogramming human skin cells came through a series of studies in both human and monkey cells. Previous unsuccessful attempts by several labs showed that human egg cells appear to be more fragile than eggs from other species. Therefore, known reprogramming methods stalled before stem cells were produced.

To solve this problem, the OHSU group studied various alternative approaches first developed in monkey cells and then applied to human cells. Through moving findings between monkey cells and human cells, the researchers were able to develop a successful method.

Several early stage egg cells following procedure
Credit: OHSU

The key to this success was finding a way to prompt egg cells to stay in a state called “metaphase” during the nuclear transfer process. Metaphase is a stage in the cell’s natural division process (meiosis) when genetic material aligns in the middle of the cell before the cell divides. The research team found that chemically maintaining metaphase throughout the transfer process prevented the process from stalling and allowed the cells to develop and produce stem cells.

“This is a remarkable accomplishment by the Mitalipov lab that will fuel the development of stem cell therapies to combat several diseases and conditions for which there are currently no treatments or cures,” said Dr. Dan Dorsa, Ph.D., OHSU Vice President for Research. “The achievement also highlights OHSU’s deep reproductive expertise across our campuses. A key component to this success was the translation of basic science findings at the OHSU primate center paired with privately funded human cell studies.”

Single human SCNT blastocyst

Credit: OHSU

One important distinction is that while the method might be considered a technique for cloning stem cells, commonly called therapeutic cloning, the same method would not likely be successful in producing human clones otherwise known as reproductive cloning. Several years of monkey studies that utilize somatic cell nuclear transfer have never successfully produced monkey clones. It is expected that this is also the case with humans.

Furthermore, the comparative fragility of human cells as noted during this study, is a significant factor that would likely prevent the development of clones.“Our research is directed toward generating stem cells for use in future treatments to combat disease,” added Dr. Mitalipov. “While nuclear transfer breakthroughs often lead to a public discussion about the ethics of human cloning, this is not our focus, nor do we believe our findings might be used by others to advance the possibility of human reproductive cloning.”

The human studies were funded by OHSU and a grant from Leducq Foundation. The nonhuman primate studies were funded by the following grants from the National Institutes of Health: HD063276, HD057121, HD059946, EY021214 and OD011092.

Contacts and sources:
Oregon Health & Science University