Jul 30, 2016

Quantum theory and Einstein's special relativity applied to plasma physics issues

This is a sketch of a pulsar, center, in binary star system.
Among the intriguing issues in plasma physics are those surrounding X-ray pulsars -- collapsed stars that orbit around a cosmic companion and beam light at regular intervals, like lighthouses in the sky. Physicists want to know the strength of the magnetic field and density of the plasma that surrounds these pulsars, which can be millions of times greater than the density of plasma in stars like the sun.

Researchers at the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL) have developed a theory of plasma waves that can infer these properties in greater detail than in standard approaches. The new research analyzes the plasma surrounding the pulsar by coupling Einstein's theory of relativity with quantum mechanics, which describes the motion of subatomic particles such as the atomic nuclei -- or ions -- and electrons in plasma. Supporting this work is the DOE Office of Science.

Quantum field theory

The key insight comes from quantum field theory, which describes charged particles that are relativistic, meaning that they travel at near the speed of light. "Quantum theory can describe certain details of the propagation of waves in plasma," said Yuan Shi, a graduate student in the Princeton Program in Plasma Physics and lead author of a paper published July 29 in the journal Physical Review A. Understanding the interactions behind the propagation can then reveal the composition of the plasma.

Shi developed the paper with assistance from co-authors Nat Fisch, director of the Program in Plasma Physics and professor and associate chair of astrophysical sciences at Princeton University, and Hong Qin, a physicist at PPPL and executive dean of the School of Nuclear Science and Technology at the University of Science and Technology of China. "When I worked out the mathematics they showed me how to apply it," said Shi.

In pulsars, relativistic particles in the magnetosphere, the magnetized atmosphere that surrounds the body, absorb light waves, and this absorption displays peaks against a blackbody background. "The question is, what do these peaks mean?" asks Shi. Analysis of the peaks with equations from special relativity and quantum field theory, he found, can determine the density and field strength of the magnetosphere.

Combining physics techniques
The process combines the techniques of high-energy physics, condensed matter physics, and plasma physics. In high-energy physics, researchers use quantum field theory to describe the interaction of a handful of particles. In condensed matter physics, people use quantum mechanics to describe the states of a large collection of particles. Plasma physics uses model equations to explain the collective movement of millions of particles. The new method utilizes aspects of all three techniques to analyze the plasma waves in pulsars.

The same technique can be used to infer the density of the plasma and strength of the magnetic field created by inertial confinement fusion experiments. Such experiments use lasers to ablate -- or vaporize -- a target that contains plasma fuel. The ablation then causes an implosion that compresses the fuel into plasma and produces fusion reactions.

Read more at Science Daily

Gullies on Mars Probably Not Carved by Water

The gullies, three- to 33 feet in width, on a scarp in Mars' Hellas impact basin.
The hunt for what carved channels into polar-facing slopes on Mars -- a process that is ongoing today -- took a new twist on Friday with the release a study showing no chemical fingerprints of flowing water at more than 100 gully sites.

Similar features on Earth are carved by flowing liquid water. Mars' cold temperatures and a low atmospheric pressure means that liquid water would be transient, if it exists at all.

Nevertheless, telltale signs of water, in the form of hydrated salts, has been tied to another seasonal feature on Mars known as recurring slope lineae, or RSL.

Scientists are beginning to take test images of potential RSL sites in Gale Crater with NASA's Mars rover Curiosity, project scientist Ashwin Vasavada told DNews.

"These things really aren't understood yet," Vasavada said.

Scientists consider gullies to be features that have an alcove on top, a channel and an apron of material at the bottom. RSLs are characterized by seasonal darkening and fading, not how the ground is shaped.

Most RSLs are found on equator-facing slopes, as opposed to the pole-facing locations of gullies, leading scientists to theorize that the features stem from different processes.

Gullies are found all over Mars, with most located between 30 degrees and 50 degrees latitude in the northern and southern hemispheres.

In the new study, planetary scientist Jorge Nunez with Johns Hopkins University Applied Physics Laboratory, and colleagues correlated high-resolution images of more than 100 gullies taken by Mars Reconnaissance Orbiter with chemical data obtained by the spacecraft's Compact Reconnaissance Imaging Spectrometer for Mars, or CRISM, instrument.

Several mechanisms have been proposed over the years to explain gully formation, including the melting of ground ice or the melting of a relict, regolith-covered snow pack. Another option is carbon dioxide frost activity that doesn't involve liquid water at all, the study said.

To help narrow the options, scientists looked for minerals, such as clays, silica, zeolites, sulfates, carbonates, or chlorides in the gullies which could indicate past water activity.

"We might have expected to see spectral evidence for liquid water such as hydrated salts as observed at RSL sites if present or recent liquid water activity had played a role in gully formation and evolution," the study said.

"We find no such evidence for brines in any of the gullies we have investigated," Nunez wrote.

The scientists conclude that their observations indicate "a limited role for long-lived liquid water in the formation and modification of Martian gullies, and support a stronger role for carbon dioxide frost-related processes."

The research is published in this week's Geophysical Research Letters.

Read more at Discovery News

Jul 29, 2016

Swirling data: Boosting computing power and info transfer rates tenfold

This is a close up look the vortex laser beam.
Like a whirlpool, a new light-based communication tool carries data in a swift, circular motion.

Described in a study published today (July 28, 2016) by the journal Science, the optics advancement could become a central component of next generation computers designed to handle society's growing demand for information sharing.

It may also be a salve to those fretting over the predicted end of Moore's Law, the idea that researchers will find new ways to continue making computers smaller, faster and cheaper.

"To transfer more data while using less energy, we need to rethink what's inside these machines," says Liang Feng, PhD, assistant professor in the Department of Electrical Engineering at the University at Buffalo's School of Engineering and Applied Sciences, and the study's co-lead author.

The other co-lead author is Natalia M. Litchinitser, PhD, professor of electrical engineering at UB.

Additional authors are: Pei Miao and Zhifeng Zhang, PhD candidates at UB; Jingbo Sun, PhD, assistant research professor of electrical engineering at UB; Wiktor Walasik, PhD, postdoctoral researcher at UB; and Stefano Longhi, PhD, professor at the Polytechnic University of Milan in Italy, and UB graduate students.

For decades, researchers have been able to cram evermore components onto silicon-based computer chips. Their success explains why today's smartphones have more computing power than the world's most powerful computers of the 1980s, which cost millions in today's dollars and were the size of a large file cabinet.

But researchers are running into a bottleneck in which existing technology may no longer meet society's demand for data. Predictions vary, but many suggest this could happen within the next five years.

Researchers are addressing the matter in numerous ways including optical communications, which uses light to carry information. Examples of optical communications vary from old lighthouses to modern fiber optic cables used to watch television and browse the internet.

Lasers are a central part of today's optical communication systems. Researchers have been manipulating lasers in various ways, most commonly by funneling different signals into one path, to carry more information. But these techniques -- specifically, wavelength-division multiplexing and time-division multiplexing -- are also reaching their limits.

The UB-led research team is pushing laser technology forward using another light manipulation technique called orbital angular momentum, which distributes the laser in a corkscrew pattern with a vortex at the center.

Usually too large to work on today's computers, the UB-led team was able to shrink the vortex laser to the point where it is compatible with computer chips. Because the laser beam travels in a corkscrew pattern, encoding information into different vortex twists, it's able to carry 10 times or more the amount of information than that of conventional lasers, which move linearly.

Read more at Science Daily

Tooth wear sheds light on the feeding habits of ancient elephant relatives

Elephant tusks
How can we ever know what ancient animals ate? For the first time, the changing diets of elephants in the last two million years in China have been reconstructed, using a technique based on analysis of the surface textures of their teeth.

The work was carried out by a University of Bristol student, working with an international team of researchers. The research was published online in Quaternary International.

Today, elephants live only in remote, tropical parts of Africa and southern Asia, but before the Ice Ages they were widespread.

As his undergraduate research project, Zhang Hanwen, MSci Palaeontology and Evolution graduate and now PhD student at the University of Bristol, undertook cutting-edge analysis of fossilised elephant teeth from China.

In a collaboration with the University of Leicester, and the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, where the fossilised teeth are curated, Hanwen sampled 27 teeth for tiny wear patterns called microwear.

"We are talking huge, brick-sized molars here -- the largest of any animal," said Hanwen, "but the signs of tooth wear are tiny, down to thousandths of a millimetre. However, these microscopic surface textures can tell us whether they were eating grass or leaves."

Hanwen took peels of the fossilised teeth in China, using high-grade dental moulding materials, and captured the 3D surface textures under a digital microscope at the University of Leicester. The textures were quantified and analysed to identify what the elephants were eating in the days and weeks before they died.

By comparing the results with information from modern ruminants (deer, antelopes and oxen) of known diet, the study concluded two extinct elephants from Southern China -- Sinomastodon and Stegodon -- were primarily browsing on leaves. The third, Elephas, which includes the modern Asian elephants, shows much more catholic feeding habit, incorporating both grazing and browsing.

"It's wonderful that we can identify diets of any fossil mammal with confidence now," said Professor Christine Janis, from the University of Bristol, one of Hanwen's PhD supervisors and a leading expert on the evolution of herbivorous mammals.

"This is based on the fact that the microwear textures produced by different kinds of plant material are comparable across unrelated animals."

"This method for identifying diet relies on high-quality 3D surface data and analysis," said Professor Mark Purnell, of the University of Leicester, another co-supervisor of Hanwen's.

"It removes the subjectivity of trying to quantify microwear textures by identifying and counting scratches and pits in 2D microscopic images."

Sinomastodon and Stegodon coexisted in Southern China between 2.6 and one million years ago, but Sinomastodon then became extinct and left Stegodon to become the dominant elephant of Southern China for the remainder of the Pleistocene, the time of the great Ice Ages.

"The fossil pollen record, and recently-excavated mammal fossil assemblages from various karst cave sites near the Chinese-Vietnamese border, suggest a prolonged, fluctuating period of environmental deterioration around this time," Hanwen explained.

He added: "Forests were on the decline, alongside many of the more archaic mammal species that inhabited them. The highly evolved molars of Stegodon, with multiple enamel ridges, might have allowed it to browse on its preferred foliage in a more efficient way, thus outcompeting Sinomastodon, which preferred the same diet, but had less sophisticated molars consisting of large, blunt, conical cusps."

Read more at Science Daily

Teasing out the microbiome of the Kansas prairie

Scientists at the Pacific Northwest National Laboratory have untangled that Kansas-based mess of microbes more fully than scientists have ever done for a sample of soil.
The Kansas prairie seems like the very picture of beauty and simplicity, with undulating fields of corn and wheat stretching as far as the eye can see.

But below ground, the soil bears witness to the incredible diversity and chaos of life within even the smallest patch of ground. Just a teaspoonful of Kansas soil contains tens of thousands of microbial species.

Now scientists at the Pacific Northwest National Laboratory have untangled that Kansas-based mess of microbes more fully than scientists have ever done for a sample of soil.

In one of the most in-depth looks to date at a soil metagenome -- all the genetic material recovered from a sample of soil -- the team reconstructed portions of the genomes of 129 species of microbes. While it's only a tiny proportion of the estimated 100,000 species in the sample, it's a leap forward for scientists who have had only a fraction of that success to date.

The results include the first reconstruction of the complete genome of a single microbe ever from a complex soil sample. Other groups have reconstructed full genomes of microbes out of less complex environments, including mines, microbial mats, and the human microbiome.

The results were published recently in mSystems, a publication of the American Society for Microbiology.

Soil microbes: Crucial for climate, environment

Microbes in soil determine in large part how the planet stores carbon, when and how carbon is released into the environment, how plants take up nutrients and how crops fare. While many people have become familiar with the community of microbes that live on us, with us, and within us -- the human microbiome -- the soil microbiome is lesser known but crucial for the fate of our planet. More knowledge about microbes helps scientists understand climate change and the forces that shape the health of our planet.

While scientists have made strides sorting out which species are present in complex soil samples, how those species interact remains a hugely daunting problem.

"We're trying to sort out the broad questions. What are the various microbes in the microbial community doing? Which species are very active and which seem dormant? How do they all fit together?" said microbiologist Janet Jansson, the corresponding author.

"Today we're able to compile immense data about microbial communities very quickly, but it's very difficult to put the information together to create a coherent picture," she added.

Jansson turned to post-doctoral associate Richard Allen White III, the first author of the paper, to take on the challenge of disentangling the genomes.

Digging up the dirt on the Kansas prairie

The team started with data culled from a sample of uncultivated, native Kansas prairie collected at the Konza Prairie Biological Station in northeastern Kansas. Scientists compiled the genetic data previously through the Great Prairie Soil Metagenome Grand Challenge Initiative at the Joint Genome Institute, a DOE Office of Science User Facility.

The Kansas soil is from the Great Plains, where soil has high carbon content compared to other soils. Scientists like Jansson are exploring what will happen in the soil as the climate changes. For example, there could be greater release of greenhouse gases to the atmosphere if microorganisms convert carbon to carbon dioxide more rapidly.

The sample under scrutiny included more than 250 billion base pairs of genetic data, mostly of microbes, which awaited a scientific team with the chutzpah to try to make sense of it. Jansson's team took on the challenge, unraveling an amount of information approximately equal to all the data streaming through 200 cell phones in a month.

The genetic material didn't come neatly packaged. It had been torn, split, twisted, crushed and exposed to all manner of disrespect.

"Imagine taking a thick book written in hundreds of different languages, chopping the book up into pieces the size of grains of rice, and then having to put it back together again," said White. "That's not unlike the challenge we face when we try to understand what's going on in even a handful of soil."

Jansson considers untangling the microbes in soil especially challenging because there is a huge diversity. Scientists estimate 50 to 100 times as many microbial species inhabit a typical soil sample than the human gut. Also, most microbes from soil have never been grown in a laboratory where they could be studied thoroughly.

Knitting soil DNA together

Scientists use multiple techniques to knit together strings of DNA accurately. The techniques are generally a combination of sophisticated chemistry methods and software algorithms designed to make sense of genetic material. A key to the team's success was the use of powerful supercomputers at PNNL and EMSL, the Environmental Molecular Sciences Laboratory. EMSL is a DOE Office of Science User Facility on the PNNL campus.

To do the study, White used a sequencing technology originally developed in the laboratory of his former adviser, Stephen Quake of Stanford. Scientists use the genome analysis tool to break DNA down into smaller pieces, then sequence those and assemble those into longer pieces.

When the team combined the technology with other methods, they ended up with 10,000 pieces of DNA, each longer than 10 kilobase pairs -- longer than 10,000 pairs of the biological compounds that make up DNA. Other attempts at cracking a soil metagenome have yielded much lower numbers, for instance, just 9 pieces of DNA of that length -- less than one-thousandth of what the team achieved.

Read more at Science Daily

New fossil evidence supports theory that first mass extinction engineered by early animals

Conichnus burrows are trace fossils: the surface bumps represent vertical tubes that were originally occupied by anemone-like animals that may have fed on Ediacaran larvae.
Newly discovered fossil evidence from Namibia strengthens the proposition that the world's first mass extinction was caused by "ecosystem engineers" -- newly evolved biological organisms that altered the environment so radically it drove older species to extinction.

The event, known as the end-Ediacaran extinction, took place 540 million years ago. The earliest life on Earth consisted of microbes -- various types of single-celled organisms. These held sway for more than 3 billion years, when the first multicellular organisms evolved. The most successful of these were the Ediacarans, which spread around the globe about 600 million years ago. They were a largely immobile form of marine life shaped like discs and tubes, fronds and quilted mattresses.

After 60 million years, evolution gave birth to another major innovation: metazoans, the first animals. Metazoans could move spontaneously and independently at least during some point in their life cycle and sustain themselves by eating other organisms or what other organisms produce. Animals burst onto the scene in a frenzy of diversification that paleontologists have labeled the Cambrian explosion, a 25 million-year period when most of the modern animal families -- vertebrates, mollusks, arthropods, annelids, sponges and jellyfish -- came into being.

"These new species were 'ecological engineers' who changed the environment in ways that made it more and more difficult for the Ediacarans to survive," said Simon Darroch, assistant professor of earth and environmental sciences at Vanderbilt University, who directed the new study described in the paper titled "A mixed Ediacaran-metazoan assemblage from the Zaris Sub-basin, Namibia," published in the journal Palaeogeography, Palaeoclimatology, Palaeoecology.

Darroch and his colleagues report that they have found one of the best-preserved examples of a mixed community of Ediacarans and animals, which provides the best evidence of a close ecological association between the two groups.

"Until this, the evidence for an overlapping ecological association between metazoans and soft-bodied Ediacaran organisms was limited," Darroch said. "Here, we describe new fossil localities from southern Namibia that preserve soft-bodied Ediacara biota, enigmatic tubular organisms thought to represent metazoans and vertically oriented metazoan trace fossils. Although the precise identity of the tracemakers remains elusive, the structures bear several striking similarities with a cone-shaped organism called Conichnus that has been found in the Cambrian period."

In a previous paper that Darroch and his collaborators published last September, they reported on a fossil record that showed stressed-looking communities of Ediacara associated with a suite of animal burrows.

"With this paper we're narrowing in on causation; we've discovered some new fossil sites that preserve both Ediacara biota and animal fossils (both animal burrows -- 'trace fossils' -- and the remains of animals themselves) sharing the same communities, which lets us speculate about how these two very different groups of organisms interacted," he said.

"Some of the burrow fossils we've found are usually interpreted as being formed by sea anemones, which are passive predators that may have preyed upon Ediacaran larvae. We've also found stands of Ediacaran frondose organisms, with animal fossils preserved in place coiled around their bases. In general, these new fossil sites reveal a snapshot of a very unusual 'transitional' ecosystem existing right before the Cambrian explosion, with the last of the Ediacara biota clinging on for grim death, just as modern-looking animals are diversifying and starting to realize their potential."

Read more at Science Daily

Jul 28, 2016

Cancer on a Paleo-diet? Ask someone who lived 1.7 million years ago

Metatarsal (a) and (b) surface rendered models show medullary spongy bone infill and clear focalized cortical destruction near the periosteal margin; also evident on external cortical margin directly abutting malignant neoplasm is the characteristic hair on end bone reaction in (b).
An international team of researchers led by scientists from the University of the Witwatersrand's Evolutionary Studies Institute and the South African Centre for Excellence in PalaeoSciences today announced in two papers, published in the South African Journal of Science, the discovery of the most ancient evidence for cancer and bony tumors yet described in the human fossil record.

The discovery of a foot bone dated to approximately 1.7 million years ago from the site of Swartkrans with definitive evidence of malignant cancer, pushes the oldest date for this disease back from recent times into deep prehistory. Although the exact species to which the foot bone belongs is unknown, it is clearly that of a hominin, or bipedal human relative.

In an accompanying paper appearing in the same journal, a collaborating team of scientists identify the oldest tumor ever found in the human fossil record, a benign neoplasm found in the vertebrae of the well-known Australopithecus sediba child, Karabo from the site of Malapa, and dated to almost two million years in age. The oldest previously demonstrated possible hominin tumor was found in the rib of a Neanderthal and dated to around 120,000 years old.

Edward Odes, a Wits doctoral candidate and lead author of the cancer paper, and co-author on the tumor paper, notes "Modern medicine tends to assume that cancers and tumors in humans are diseases caused by modern lifestyles and environments. Our studies show the origins of these diseases occurred in our ancient relatives millions of years before modern industrial societies existed."

The cancer in a foot bone, a metatarsal, was identified as an osteosarcoma, an aggressive form of cancer which usually affects younger individuals in modern humans, and, if untreated typically results in early death. "Due to its preservation, we don't know whether the single cancerous foot bone belongs to an adult or child, nor whether the cancer caused the death of this individual, but we can tell this would have affected the individuals' ability to walk or run," says Dr Bernhard Zipfel, a Wits scientist and an expert on the foot and locomotion of early human relatives. "In short, it would have been painful."

Lead author of the tumor paper and co-author of the cancer paper, Dr Patrick Randolph-Quinney of Wits University and the University of Central Lancashire in the UK, suggests "The presence of a benign tumor in Australopithecus sediba is fascinating not only because it is found in the back, an extremely rare place for such a disease to manifest in modern humans, but also because it is found in a child. This, in fact, is the first evidence of such a disease in a young individual in the whole of the fossil human record."

Prof. Lee Berger, an author on both papers and leader of the Malapa project where the fossil vertebra was found adds "not only has there been an assumption that these sorts of cancers and tumors are diseases of modernity, which these fossils clearly demonstrate they are not, but that we as modern humans exhibit them as a consequence of living longer, yet this rare tumor is found in a young child. The history of these types of tumors and cancers is clearly more complex than previously thought."

Both incidents of disease were diagnosed using state of the art imaging technologies including those at the European Synchrotron Research Facility in Grenoble, France, medical CT at the Charlotte Maxeke Hospital in Johannesburg, and the micro-CT facility at the Nuclear Energy Corporation of South Africa at Pelindaba.

Read more at Science Daily

World's Deepest Blue Hole Is in South China Sea

A new exploration of a legendary blue hole in the South China Sea has found that the underwater feature is the deepest known on Earth.

According to Xinhua News, Dragon Hole, or Longdong, is 987 feet (300.89 meters) deep, far deeper than the previous record holder, Dean's Blue Hole in the Bahamas. (That blue hole measures about 663 feet, or 202 m, deep.) According to Xinhua, local legend holds that Dragon Hole is mentioned in the Ming dynasty novel "Journey to the West," in which a supernatural monkey character gets a magical cudgel from an undersea kingdom ruled by a dragon.

The findings have yet to be confirmed or reviewed by scientists in the field, but if they hold up, the measurements peg Dragon Hole as far deeper than Dean's Blue Hole, said Pete van Hengstum, a marine geologist at Texas A&M University at Galveston, who conducts research on blue holes and sinkholes throughout the Caribbean region.

Blue holes are water-filled sinkholes that form in carbonate rock such as limestone. Over long periods of time, the carbonate rock dissolves in the subsurface to form caves or cavities, van Hengstum told Live Science.

"Eventually, the process of dissolution causes the cave to reach very close to the Earth's surface, and if the cave ceiling collapses, a blue hole or sinkhole is formed," he said.

Some blue holes, like Dragon Hole, open up to the marine environment, while others are inland.

It's something of a mystery why blue holes form precisely where they do and what factors influence their development. Chemical reactions at the interface of saltwater and freshwater can create weak acids that eat away at limestone and other carbonates, said Lisa Park Boush, a geoscientist at the University of Connecticut who studies blue-hole sediments in the Bahamas. As a result, rising and falling sea levels can influence when and where blue holes form.

"There is also a group of researchers looking into microbial processes," Boush told Live Science. In some cases, she said, microbe activity might help to dissolve bedrock and contribute to the formation of blue holes.

In addition to microbes, other organisms also call these jaw-droppingly gorgeous holes home.

"It's interesting to see what actually lives in these blue holes," said Boush, who called the environment of blue holes "cryptic."

Scientists with the Sansha Ship Course Research Institute for Coral Protection in China used an underwater robot and a depth sensor to investigate the mysterious environment of Dragon Hole, which is a well-known feature in Yongle, a coral reef near the Xisha Islands in the South China Sea, according to Xinhua. They found more than 20 marine organisms living in the upper portions of the hole. Below about 328 feet (100 m), the seawater in the blue hole had almost no oxygen, and thus little life, the researchers told Xinhua on July 22.

Even so, diving in blue holes is extremely dangerous, she said.

"One of the reasons why it's very dangerous is because of the limited oxygen," she said. "And sometimes there are even sulfuric waters."

Well-trained divers can make the journey, van Hengstum said. In other cases, researchers park a boat right above a blue hole and send equipment down to measure depth, temperature, oxygenation and other factors. Both Boush and van Hengstum conduct research on the sediments at the bottom of blue holes. These sediments contain information about the past environment and climate change — and sometimes fossils.

Read more at Discovery News

Mysterious 'Purple Blob' Spotted Off California Coast

A mysterious "purple blob" in the Pacific Ocean off of California's southern coast was spotted this week by Ocean Exploration Trust's vessel, Nautilus.

The as-of-yet unidentified purple orb could represent a previously unknown type of egg sac or a new species, according to researchers aboard the vessel, which has been streaming live footage. The moment of discovery, complete with the scientists' comments and a curious crab, was captured in full on video:

As the video shows, the colorful orb was sucked into the vessel. Shortly thereafter, Nautilus Live shared via social media that the find was collected from the Arguello Canyon near the NOAA Channel Islands National Marine Sanctuary.

"After sampling," the statement reads, "it began to unfold to reveal two distinct lobes. This may be a new species of nudibranch, or sea slug."

Several hours later, this update was posted: "We're still working on a species ID with our science partners, but currently we're thinking the purple orb is a pleurobranch, a nudibranch relative."

Pleurobranchs are a type of sea slug that have a prominent outer covering called a mantle and an internal shell that reduces, or is entirely lost, in adults. Pleurobranchs often visually stand out from the substrate.

Pleurobranchus forskali.
As researchers further analyze the still mysterious orb, Nautilus has continued its exploration of waters off the southern California coast. A short while ago, the scientists posted the following image saying: "From mysterious purple orbs to this crinoid on a column of whelk snail eggs, we never know what we'll find on the deep sea floor!"

Read more at Discovery News

'Game of Thrones' Spiked Ants Discovered

3-D scan of the newly discovered ant Pheidole drogon.
The dragons Viserion and Drogon from the "Game of Thrones" fantasy novels and TV series have come to life in miniature as two newly discovered muscular, spiny ants, which are described in a new study.

The new ants, Pheidole viserion and Pheidole drogon, not only feature dragon-like characteristics, but the soldier ants of these species also have massive heads relative to the size of the rest of their bodies. The formidable insects are documented in the journal PLOS ONE.

3-D scans of a Pheidole drogon minor (left) and a major worker (right).
Researchers Georg Fischer, Eli Sarnat and Evan Economo from the Okinawa Institute of Science and Technology Graduate University found the ants in the tropical rainforests of Papua New Guinea. To study the ants, they used a cutting edge 3-D imaging technology called x-ray microtomography, which is like a hospital CT scan, but with a much higher resolution suitable for small organisms.

"This is one of the first studies in ant taxonomy to use micro-CT," Economo, head of OIST's Biodiversity and Biocomplexity Unit, said in a press release. "While this method is gaining popularity in different scientific fields, it is rare to use it in this way."

Pheidole viserion.
Fischer said, "If you are working in the bush in Africa and find an ant that you want to identify, it is really difficult to fly all the way to a museum in Europe or the U.S. to see collections of already known species. This way you can download the virtual ant, make measurements, and compare it to the specimen you are trying to identify."

That process, along with more traditional analysis, allowed the researchers to determine that the found ants represent new species. The ants now "live" in 3-D, allowing them to be dissected, archived and shared with other scientists around the world.

The spines on the ants help to protect the insects, but the scientists think the sharp appendages serve another surprising function, given the ants' enormous heads.

"Once you open up the rotational 3-D PDF and see these ants' extraordinary spines, or 'inordinate spinescence' as we phrase it in the study, you can't help but ask why on earth these structures evolved," Sarnat said. "The most obvious answer is defense, but the internal morphology revealed by this new micro-CT scanning technology suggests that the answer might also have something to do with muscle mechanics and powering the huge heads of the soldier ants."

Read more at Discovery News

Jul 27, 2016

Scientists simulated a nuclear explosion of an asteroid

Employees of the Department of Celestial Mechanics and Astrometry NII PMM of Tomsk state university (Russia) and colleagues from St. Petersburg State University, Keldysh Research Center, and Research Institute Sirius are developing measures to protect the Earth from potentially dangerous celestial bodies. With the help of supercomputer SKIF Cyberia, the scientists simulated the nuclear explosion of an asteroid 200 meters in diameter in such a way that its irradiated fragments do not fall to the Earth.

"The way we propose to eliminate the threat from space is reasonable to use in case of the impossibility of the soft disposal of an object from a collision in orbit and for the elimination of an object that is constantly returning to Earth," says Tatiana Galushina, an employee of the Department of Celestial Mechanics and Astrometry. "Previously, as a preventive measure, it was proposed to abolish the asteroid on its approach to our planet, but this could lead to catastrophic consequences -- a fall to Earth of the majority of the highly radioactive fragments."

TSU scientists with colleagues from other research centres have offered another solution to the problem. It is known that the majority of dangerous objects pass close to Earth several times before the collision. Therefore, there is a possibility to blow up the asteroid at the time when it is farther from the planet. This measure will be much more effective and safer.

For computer modeling as a potential target was taken a celestial body with a diameter of 200 meters, similar to the asteroid Apophis, which in 2029 will approach Earth at a distance of 38,000 kilometers. Calculations have shown that for the destruction of the object there must be the impact of a nuclear device with energy of one megaton of TNT equivalent. In this case, part of the asteroid turns into gas and liquid droplets, and some will break into pieces no larger than 10 meters. This is the maximum in terms of safety for the Earth.

"Because the rocket catches behind the asteroid, almost all the pieces after the destruction will fly forward," says Tatiana Galushina. "In this case the orbit of the fragments will be significantly different from the asteroid's orbit. For 10 years after the explosion an insignificant number of fragments will fall to Earth. Their radioactivity during this time will be reduced considerably, and after a few years they will not pose a danger. It is worth adding that nuclear explosions in space are prohibited by international treaty, but in the case of a real threat to humanity maybe there will be an exception to this rule."

Specialists from different areas who are experts in celestial mechanics and ballistics worked on the project. The scientists note that the theoretical calculations are only the beginning of the work, without which the practical implementation on the preventive measures protecting the Earth is impossible.

From Science Daily

Finding the loneliest young star

The stars circled in blue are ones identified by the US Naval Observatory B-1.0 catalog.
Alone on the cosmic road, far from any known celestial object, a young, independent star is going through a tremendous growth spurt.

The unusual object, called CX330, was detected as a source of X-ray light in 2009 by NASA's Chandra X-Ray Observatory while surveying the bulge in the central region of the Milky Way. Further observations indicated this object was emitting optical light as well. With only these clues, scientists had no idea what this object was.

But when a team led by Texas Tech University Department of Physics associate professor Tom Maccarone and postdoctoral researcher Chris Britt examined infrared images of the same area taken with NASA's Wide-field Infrared Survey Explorer (WISE), they realized this object has a lot of warm dust around it, which must have been heated by an outburst.

Comparing WISE data from 2010 with Spitzer Space Telescope data from 2007, researchers determined CX330 likely is a young star that has been outbursting for several years. In fact, in that three-year period, its brightness had increased a few hundred times.

Astronomers gathered data about the object from a variety of other observatories, including the ground-based SOAR, Magellan, and Gemini telescopes. They also used the VISTA Variables in the Via Lactea and Optical Gravitational Lensing Experiment IV to measure the intensity of light emitted from CX330. By combining the different perspectives on the object, a clearer picture emerged.

"We tried various interpretations for it, and the only one that makes sense is that this rapidly growing young star is forming in the middle of nowhere," said Britt, lead author of a study on CX330 recently published in the Monthly Notices of the Royal Astronomical Society.

The lone star's behavior is remarkably similar to FU Orionis, a young outbursting star that had an initial three-month outburst in 1936-37 and whose bright emissions have been fading ever since. CX330 is fading as well, but its brightness hasn't fallen more than a factor of 10 since its peak in 2010 or 2011. CX330 is more compact, hotter and likely more massive than the FU Orionis-like objects, launching faster outflows slamming into the gas and dust around it.

"The disk has probably heated to the point where the gas in the disk has become ionized, leading to a rapid increase in how fast the material falls onto the star," said Maccarone, co-author on the study.

Most puzzling to astronomers, FU Orionis and the rare objects like it -- there are only about 10 of them -- are located in star-forming regions. That's because young stars form and feed from their surroundings, which are the gas- and dust-rich -- and most tightly packed -- regions in star-forming clouds. By contrast, the region of star formation closest to CX330 is several hundred parsecs away. If the sun were this isolated, the nearest star-forming region would be near Orion.

"CX330 is both more intense and more isolated than any of these young outbursting objects that we've ever seen," said Joel Green, study co-author and researcher at the Space Telescope Science Institute in Baltimore. "This could be the tip of the iceberg -- these objects may be everywhere."

In fact, it is possible all stars go through this dramatic stage of development in their youth, but many of the outbursts are too short in cosmological time for humans to observe.

How did CX330 become so isolated? Scientists aren't sure. One idea is that CX330 was born in a star-forming region but was ejected into its present lonely pocket of the universe. This is unlikely, astronomers say. Because CX330 is in a youthful phase of its development -- likely less than 1 million years old -- and still is eating its surrounding disk, it must have formed near its present location in the sky.

"If it had migrated from a star-forming region, it couldn't get there in its lifetime without stripping its disk away entirely," Britt said.

CX330 also may help scientists study how stars form under different circumstances. One scenario suggests stars form through turbulence. In this "hierarchical" model, a critical density of gas in a cloud causes the cloud to gravitationally collapse into a star. A different model, called "competitive accretion," claims stars begin as low-mass cores that fight over the mass of material left in the cloud. CX330 more naturally fits into the first scenario, as the turbulent circumstances would theoretically allow for a lone star to form.

It is still possible other intermediate- to low-mass stars are in the immediate vicinity of CX330 but have not been detected yet.

CX330 was last viewed in August 2015, and it was still outbursting then. Astronomers plan to continue studying the object, including with future telescopes that could view CX330 in other wavelengths of light.

Read more at Science Daily

Exotic White Dwarf Brutalizes its Red Dwarf Partner

Comprised of a tiny white dwarf and red dwarf that orbit one another every 3.6 hours, the AR Scorpii system was misidentified in the 1970s as a single variable star that fluctuated in brightness. But in 2015, amateur astronomers stumbled upon the star and made a note of its strange behavior. In followup observations, culminating in observing time with the Hubble Space Telescope, AR Scorpii's binary nature was revealed.

Binary stars are common in our galaxy, but this particular system has an exotic side that that is causing some confusion.

Every 1 minute and 58 seconds, the white dwarf blasts its red dwarf binary partner with an incredibly powerful beam of radiation. This pulse of radiation causes the whole system to brighten and dim like clockwork and includes radiation over a broad range of frequencies, including radio waves. And herein lies the puzzle.

White dwarfs are small husks of stars that died long ago. After sun-like stars run out of hydrogen fuel, they puff up into erupting red giants, eventually shedding their hot plasma, creating beautiful planetary nebulae. When our sun eventually dies in about 5 billion years, all that will be left behind is a nebula and tiny white dwarf in the core. These dense objects are around the size of Earth but contain the mass of 200,000 Earths. They are also highly magnetized, compressing the entire magnetic field of a large main sequence star into the volume of a small planet.

So the powerful beam of radiation sweeps through space like a lighthouse as the white dwarf spins -- in a similar way that spinning neutron stars create pulsars. This beam is generated by the white dwarf's intense magnetic field accelerating electrons to relativistic speeds. But astronomers aren't sure where these electrons are coming from as it's not clear whether they are supplied by the white dwarf or red dwarf.

"We've known about pulsing neutron stars for nearly fifty years, and some theories predicted white dwarfs could show similar behavior," said Boris Gänsicke of the University of Warwick. "It's very exciting that we have discovered such a system, and it has been a fantastic example of amateur astronomers and academics working together."

Read more at Discovery News

Rocky the Orangutan Copies Human Sounds

Rocky the orangutan.
Rocky, an orangutan at the Indianapolis Zoo, can copy the pitch and tone of vowel-like sounds made by people, according to a new study.

The ability, demonstrated by Rocky in a video and documented in the journal Scientific Reports, suggests that critical skills underlying human speech were present in the common ancestor of our species and other great apes.

As the video shows, Rocky -- when rewarded with plenty of peanuts -- can play a successful game of "do-as-I-do." He really nails one of the sounds towards the end of the clip:

"It's not clear how spoken language evolved from the communication systems of the ancestral great apes," project leader Adriano Lameira of Durham University said in a press release. "Instead of learning new sounds, it has been presumed that sounds made by great apes are driven by arousal over which they have no control, but our research proves that orangutans have the potential capacity to control the action of their voices.

"This indicates that the voice control shown by humans could derive from an evolutionary ancestor with similar voice control capacities as those found in orangutans and in all great apes more generally."

Lameira and his team compared the vowel-like sounds produced by Rocky with the largest available database of orangutan calls. The database recordings were collected from over 12,000 hours of observations of more than 120 orangutans from 15 wild and captive populations.

After this extensive comparison, the scientists were able to conclude that the sounds made by Rocky were different than the sounds included in the database. This shows that Rocky was able to learn new sounds and to control the action of his voice in a "conversational" context.

Read more at Discovery News

Jul 26, 2016

Puzzling paucity of large craters on dwarf planet Ceres

The top of this false-color image includes a grazing view of Kerwan, Ceres' largest impact crater. This well-preserved crater is 280 km (175 miles) wide and is well defined with red-yellow high-elevation rims and a deep central depression shown in blue. Kerwan gradually degrades as one moves toward the center of the image into an 800-km (500-mile) wide, 4-km (2.5-mile) deep depression (in green) called Vendimia Planitia. This depression is possibly what's left of one of the largest craters from Ceres' earliest collisional history.
A team of scientists led by Southwest Research Institute (SwRI) made a puzzling observation while studying the size and distribution of craters on the dwarf planet Ceres.

Ceres is the largest object in the tumultuous Main Asteroid Belt between Mars and Jupiter. Collision models predicted Ceres should have accumulated up to 10 to 15 craters larger than 400 kilometers (250 miles) wide, and at least 40 craters larger than 100 km (62 miles) wide. Instead, NASA's Dawn spacecraft found only 16 craters larger than 100 km, and none larger than the 280 km (175 miles) across.

Crater size and distribution offer planetary scientists important clues to the age, makeup, and geologic history of planets and asteroids. Ceres is believed to have originated about 4.5 billion years ago at the dawn of our solar system. It grew in size through a history of accretionary collisions of smaller bodies. Some of its largest siblings were subsequently incorporated into larger objects, such as planets. Today, Ceres and Main Belt asteroids remain as the leftovers of the planet-building process.

Although Ceres endured the most violent phase of the solar system's collision-prone past, images of its surface taken by the Dawn spacecraft showed plenty of small impact craters, but the largest well-defined crater is only about 280-km in diameter. This defied most models of crater size and distribution and is at odds with what is known from previously imaged asteroids. For example, Dawn images of the asteroid Vesta, only about half the size of Ceres, revealed huge craters, including one 500 kilometers (300 miles) in diameter, covering almost an entire side of that asteroid.

"We concluded that a significant population of large craters on Ceres has been obliterated beyond recognition over geological time scales, likely the result of Ceres' peculiar composition and internal evolution," said lead investigator Dr. Simone Marchi, a senior research scientist in SwRI's Space Science and Engineering Division.

A closer look at Ceres' topography revealed subtle clues to a possible solution. Up to three roughly circular, shallow basins as much as 800 km (500 miles) wide may lie hidden beneath a surface subsequently marked with small craters.

"These depressions -- or planitiae -- may be 'relict' impact basins, left over from large collisions that took place early in Ceres' history," Marchi said. This implies that the predicted enormous craters may have indeed once marked the surface of Ceres. "It is as though Ceres cures its own large impact scars and regenerates new surfaces, over and over."

The scientists think Ceres' missing large craters may have been erased over time as a deep subsurface ice-rich layer or low viscous material caused the crater rims and bowls to relax, or that cryolava may have flowed across the surface. This process, however, may have not operated as efficiently for the largest, deepest impact features.

Read more at Science Daily

Digging deeper into Mars

This is a global map of Mars sulfur concentration (as percentage by mass) derived from the 2001: Mars Odyssey Gamma Ray Spectrometer spectra. Overlay shows qualitatively what types of hydrated sulfates are consistent with the variations seen in sulfur and water across the latitudes. Upright triangles indicate peaks in possible sulfate type abundance while the inverted triangles show less prominent values.
Water is the key to life on Earth. Scientists continue to unravel the mystery of life on Mars by investigating evidence of water in the planet's soil. Previous observations of soil observed along crater slopes on Mars showed a significant amount of perchlorate salts, which tend to be associated with brines with a moderate pH level. However, researchers have stepped back to look at the bigger picture through data collected from the 2001: Mars Odyssey, named in reference to the science fiction novel by Arthur C. Clarke, "2001: A Space Odyssey," and found a different chemical on Mars may be key. The researchers found that the bulk soil on Mars, across regional scales the size of the U.S. or larger, likely contains iron sulfates bearing chemically bound water, which typically result in acidic brines. This new observation suggests that iron sulfates may play a major role in hydrating martian soil.

This finding was made from data collected by the 2001: Mars Odyssey Gamma Ray Spectrometer, or GRS, which is sensitive enough to detect the composition of Mars soil up to one-half meter deep. This is generally deeper than other missions either on the ground or in orbit, and it informs the nature of bulk soil on Mars. This research was published recently in the Journal of Geophysical Research: Planets.

"This is exciting because it's contributing to the story of water on Mars, which we've used as a path for our search for life on Mars," said Nicole Button, LSU Department of Geology and Geophysics doctoral candidate and co-author in this study.

The authors expanded on previous work, which explored the chemical association of water with sulfur on Mars globally. They also characterized how, based on the association between hydrogen and sulfur, the soil hydration changes at finer regional scales. The study revealed that the older ancient southern hemisphere is more likely to contain chemically bound water while the sulfates and any chemically bound water are unlikely to be associated in the northerly regions of Mars.

The signature of strong association is strengthened in the southern hemisphere relative to previous work, even though sulfates become less hydrated heading southwards. In addition, the water concentration may affect the degree of sulfate hydration more than the sulfur concentration. Limited water availability in soil-atmosphere exchange and in any fluid movement from deeper soil layers could explain how salt hydration is water-limited on Mars. Differences in soil thickness, depth to any ground ice table, atmospheric circulation and sunshine may contribute to hemispheric differences in the progression of hydration along latitudes.

The researchers considered several existing hypotheses in the context of their overall observations, which suggest a meaningful presence of iron-sulfate rich soils, which are wet compared to Mars' typically desiccated soil. This type of wet soil was uncovered serendipitously by the Spirit Rover while dragging a broken wheel across the soil in the Paso Robles area of Columbia Hills at Gusev Crater. Key hypotheses of the origin of this soil include hydrothermal activity generating sulfate-rich, hydrated deposits on early Mars similar to what is found along the flanks of active Hawaiian volcanoes on Earth. Alternatively, efflorescence, which creates the odd salt deposits on basement walls on Earth, may have contributed trace amounts of iron-sulfates over geologic time. A third key hypothesis involves acidic aerosols released at volcanic sites, such as acid fog, dispersed throughout the atmosphere, and interacting subsequently with the finer components of soil as a source of widespread hydrated iron-sulfate salts.

Among these hypotheses, the researchers identify acid fog and hydrothermal processes as more consistent with their observations than efflorescence, even though the sensitivity of GRS to elements, but not minerals, prevents a decisive inference. Hydrothermal sites, in particular, are increasingly recognized as important places where the exchange between the surface and deep parts of Earth's biosphere are possible. This hypothesis is significant to the question of martian habitability.

Read more at Science Daily

From vision to hand action: Neuroscientists decipher how our brain controls grasping movements

All finger and hand movements of the monkeys were recorded with an electromagnetic data glove.
Our hands are highly developed grasping organs that are in continuous use. Long before we stir our first cup of coffee in the morning, our hands have executed a multitude of grasps. Directing a pen between our thumb and index finger over a piece of paper with absolute precision appears as easy as catching a ball or operating a doorknob. The neuroscientists Stefan Schaffelhofer and Hansjörg Scherberger of the German Primate Center (DPZ) have studied how the brain controls the different grasping movements.

In their research with rhesus macaques, it was found that the three brain areas AIP, F5 and M1 that are responsible for planning and executing hand movements, perform different tasks within their neural network. The AIP area is mainly responsible for processing visual features of objects, such as their size and shape. This optical information is translated into motor commands in the F5 area. The M1 area is ultimately responsible for turning this motor commands into actions. The results of the study contribute to the development of neuroprosthetics that should help paralyzed patients to regain their hand functions.

The three brain areas AIP, F5 and M1 lay in the cerebral cortex and form a neural network responsible for translating visual properties of an object into a corresponding hand movement. Until now, the details of how this "visuomotor transformation" are performed have been unclear. During the course of his PhD thesis at the German Primate Center, neuroscientist Stefan Schaffelhofer intensively studied the neural mechanisms that control grasping movements. "We wanted to find out how and where visual information about grasped objects, for example their shape or size, and motor characteristics of the hand, like the strength and type of a grip, are processed in the different grasp-related areas of the brain," says Schaffelhofer.

For this, two rhesus macaques were trained to repeatedly grasp 50 different objects. At the same time, the activity of hundreds of nerve cells was measured with so-called microelectrode arrays. In order to compare the applied grip types with the neural signals, the monkeys wore an electromagnetic data glove that recorded all the finger and hand movements. The experimental setup was designed to individually observe the phases of the visuomotor transformation in the brain, namely the processing of visual object properties, the motion planning and execution. For this, the scientists developed a delayed grasping task. In order for the monkey to see the object, it was briefly lit before the start of the grasping movement. The subsequent movement took place in the dark with a short delay. In this way, visual and motor signals of neurons could be examined separately.

The results show that the AIP area is primarily responsible for the processing of visual object features. "The neurons mainly respond to the three-dimensional shape of different objects," says Stefan Schaffelhofer. "Due to the different activity of the neurons, we could precisely distinguish as to whether the monkeys had seen a sphere, cube or cylinder. Even abstract object shapes could be differentiated based on the observed cell activity."

In contrast to AIP, area F5 and M1 did not represent object geometries, but the corresponding hand configurations used to grasp the objects. The information of F5 and M1 neurons indicated a strong resemblance to the hand movements recorded with the data glove. "In our study we were able to show where and how visual properties of objects are converted into corresponding movement commands," says Stefan Schaffelhofer. "In this process, the F5 area plays a central role in visuomotor transformation. Its neurons receive direct visual object information from AIP and can translate the signals into motor plans that are then executed in M1. Thus, area F5 has contact to both, the visual and motor part of the brain."

Read more at Science Daily

Ancient Tasmanian Devil Cousin Was Flesh-Eating Terror

A newly described ancient marsupial is a distant relative of modern-day Tasmanian devils.
A new species of extinct flesh-eating marsupial that terrorized Australia's forests some five million years ago has been identified from a recently discovered fossil site, scientists said Tuesday.

The animal, weighing 20 to 25 kilograms (44 to 55 pounds) and named Whollydooleya tomnpatrichorum, is a distant and bigger cousin of Australia's largest living flesh-eating marsupial -- the Tasmanian Devil.

An illustration shows the size comparison of Australian marsupials including new extinct species of carnivorous marsupial, Whollydooleya tomnpatrichorum, from New Riversleigh fossil site in Queensland.
It is the first creature to be formally identified from a range of strange new animals whose remains have been found at a fossil site in remote northwestern Queensland.

"W. tomnpatrichorum had very powerful teeth capable of killing and slicing up the largest animals of its day," said University of New South Wales professor Mike Archer, the lead author of a study into the find published in the Memoirs of Museum Victoria.

The late Miocene period between 12 and five million years ago, when Australia began to dry out and megafauna began to evolve, is one of the least understood in the vast continent's past, he added.

Fossils of land animals from this time are extremely rare.

"Fortunately, in 2012, we discovered a whole new fossil field that lies beyond the internationally famous Riversleigh World Heritage Area fossil deposits in northwestern Queensland," said Archer.

With a grant from the National Geographic Society, Archer and his colleagues began to explore the "New Riversleigh" site in 2013 and the species' highly distinctive molar was one of the first finds.

Read more at Discovery News

Record-Setting Dinosaur Footprint Found in Bolivia

A huge dinosaur footprint measuring 1.2 meters (nearly four feet) in diameter has been discovered in Bolivia, a researcher said Monday.

The dinosaur, from the Abelisaurid family, would have left the track some 80 million years ago, said the local paleontologist who found it, Omar Medina.

He made the find in southeast Bolivia, a hotbed of dinosaur fossils.

"It's one of the largest prints ever found" in the South American country, he told AFP.

The dinosaur that left it, the carnivorous biped Abelisaurus, from the Late Cretaceous, would have been about 49 feet (15 meters) tall.

The paleontologist who verified the footprint, Sebastian Apestiguia, said other carnivorous dinosaurs of the period in South America usually only stood about 29.5 feet (9 meters) tall and that this new find would be record-setting, according to the Spanish news agency EFE.

Huge dinosaur prints measuring up to two meters across have also been found in France and Argentina.

From Discovery News

Jul 25, 2016

New lithium-oxygen battery greatly improves energy efficiency, longevity

In a new concept for battery cathodes, nanometer-scale particles made of lithium and oxygen compounds (depicted in red and white) are embedded in a sponge-like lattice (yellow) of cobalt oxide, which keeps them stable. The researchers propose that the material could be packaged in batteries that are very similar to conventional sealed batteries yet provide much more energy for their weight.
Lithium-air batteries are considered highly promising technologies for electric cars and portable electronic devices because of their potential for delivering a high energy output in proportion to their weight. But such batteries have some pretty serious drawbacks: They waste much of the injected energy as heat and degrade relatively quickly. They also require expensive extra components to pump oxygen gas in and out, in an open-cell configuration that is very different from conventional sealed batteries.

But a new variation of the battery chemistry, which could be used in a conventional, fully sealed battery, promises similar theoretical performance as lithium-air batteries, while overcoming all of these drawbacks.

The new battery concept, called a nanolithia cathode battery, is described in the journal Nature Energy in a paper by Ju Li, the Battelle Energy Alliance Professor of Nuclear Science and Engineering at MIT; postdoc Zhi Zhu; and five others at MIT, Argonne National Laboratory, and Peking University in China.

One of the shortcomings of lithium-air batteries, Li explains, is the mismatch between the voltages involved in charging and discharging the batteries. The batteries' output voltage is more than 1.2 volts lower than the voltage used to charge them, which represents a significant power loss incurred in each charging cycle. "You waste 30 percent of the electrical energy as heat in charging. ... It can actually burn if you charge it too fast," he says.

Staying solid

Conventional lithium-air batteries draw in oxygen from the outside air to drive a chemical reaction with the battery's lithium during the discharging cycle, and this oxygen is then released again to the atmosphere during the reverse reaction in the charging cycle.

In the new variant, the same kind of electrochemical reactions take place between lithium and oxygen during charging and discharging, but they take place without ever letting the oxygen revert to a gaseous form. Instead, the oxygen stays inside the solid and transforms directly between its three redox states, while bound in the form of three different solid chemical compounds, Li2O, Li2O2, and LiO2, which are mixed together in the form of a glass. This reduces the voltage loss by a factor of five, from 1.2 volts to 0.24 volts, so only 8 percent of the electrical energy is turned to heat. "This means faster charging for cars, as heat removal from the battery pack is less of a safety concern, as well as energy efficiency benefits," Li says.

This approach helps overcome another issue with lithium-air batteries: As the chemical reaction involved in charging and discharging converts oxygen between gaseous and solid forms, the material goes through huge volume changes that can disrupt electrical conduction paths in the structure, severely limiting its lifetime.

The secret to the new formulation is creating minuscule particles, at the nanometer scale (billionths of a meter), which contain both the lithium and the oxygen in the form of a glass, confined tightly within a matrix of cobalt oxide. The researchers refer to these particles as nanolithia. In this form, the transitions between LiO2, Li2O2, and Li2O can take place entirely inside the solid material, he says.

The nanolithia particles would normally be very unstable, so the researchers embedded them within the cobalt oxide matrix, a sponge-like material with pores just a few nanometers across. The matrix stabilizes the particles and also acts as a catalyst for their transformations.

Conventional lithium-air batteries, Li explains, are "really lithium-dry oxygen batteries, because they really can't handle moisture or carbon dioxide," so these have to be carefully scrubbed from the incoming air that feeds the batteries. "You need large auxiliary systems to remove the carbon dioxide and water, and it's very hard to do this." But the new battery, which never needs to draw in any outside air, circumvents this issue.

No overcharging

The new battery is also inherently protected from overcharging, the team says, because the chemical reaction in this case is naturally self-limiting -- when overcharged, the reaction shifts to a different form that prevents further activity. "With a typical battery, if you overcharge it, it can cause irreversible structural damage or even explode," Li says. But with the nanolithia battery, "we have overcharged the battery for 15 days, to a hundred times its capacity, but there was no damage at all."

In cycling tests, a lab version of the new battery was put through 120 charging-discharging cycles, and showed less than a 2 percent loss of capacity, indicating that such batteries could have a long useful lifetime. And because such batteries could be installed and operated just like conventional solid lithium-ion batteries, without any of the auxiliary components needed for a lithium-air battery, they could be easily adapted to existing installations or conventional battery pack designs for cars, electronics, or even grid-scale power storage.

Because these "solid oxygen" cathodes are much lighter than conventional lithium-ion battery cathodes, the new design could store as much as double the amount of energy for a given cathode weight, the team says. And with further refinement of the design, Li says, the new batteries could ultimately double that capacity again.

Read more at Science Daily

New movie screen allows for glasses-free 3-D

A new prototype display could show 3-D movies to any seat in a theater, with no eyewear required.
3-D movies immerse us in new worlds and allow us to see places and things that we otherwise couldn't. But behind every 3-D experience is something that is uniformly despised: those goofy glasses.

In a new paper, a team from MIT's Computer Science and Artificial Intelligence Lab (CSAIL) and Israel's Weizmann Institute of Science have demonstrated a display that lets you watch 3-D films in a movie theater without extra eyewear.

Dubbed "Cinema 3D," the prototype uses a special array of lenses and mirrors to enable viewers to watch a 3-D movie from any seat in a theater.

"Existing approaches to glasses-free 3-D require screens whose resolution requirements are so enormous that they are completely impractical," says MIT professor Wojciech Matusik, one of the co-authors on a related paper. "This is the first technical approach that allows for glasses-free 3D on a large scale."

While the researchers caution that the system isn't currently market-ready, they are optimistic that future versions could push the technology to a place where theaters would be able to offer glasses-free alternatives for 3-D movies.

Among the paper's co-authors are MIT research technician Mike Foshey; former CSAIL postdoc Piotr Didyk; and two Weizmann researchers that include professor Anat Levin and PhD student Netalee Efrat, who was first author on the paper. Efrat will present the paper at this week's SIGGRAPH computer-graphics conference in Anaheim, California.

How it works

Glasses-free 3-D already exists, but not in a way that scales to movie theaters. Traditional methods for TV sets use a series of slits in front of the screen (a "parallax barrier") that allow each eye to see a different set of pixels, creating a simulated sense of depth.

But because parallax barriers have to be at a consistent distance from the viewer, this approach isn't practical for larger spaces like theaters that have viewers at different angles and distances.

Other methods, including one from the MIT Media Lab, involve developing completely new physical projectors that cover the entire angular range of the audience. However, this often comes at a cost of reduced image resolution.

The key insight with Cinema 3D is that people in movie theaters move their heads only over a very small range of angles limited by the width of their seat. Thus, it is enough to display a narrow range of angles and replicate it to all seats in the theater.

What Cinema 3D does, then, is encode multiple parallax barriers in one display, such that each viewer sees a parallax barrier tailored to their position. That range of views is then replicated across the theater by a series of mirrors and lenses within Cinema 3D's special optics system.

"With a 3-D TV, you have to account for people moving around to watch from different angles, which means that you have to divide up a limited number of pixels to be projected so that the viewer sees the image from wherever they are," says Gordon Wetzstein, an assistant professor of electrical engineering at Stanford University who was not involved in the research. "The authors [of Cinema 3D] cleverly exploited the fact that theaters have a unique set-up in which every person sits in a more or less fixed position the whole time."

The team demonstrated that their approach allows viewers from different parts of an auditorium to see images of consistently high resolution.

Read more at Science Daily

'Exceptional points' give rise to counterintuitive physical effects

No matter whether it is acoustic waves, quantum matter waves or optical waves of a laser -- all kinds of waves can be in different states of oscillation, corresponding to different frequencies. Calculating these frequencies is part of the tools of the trade in theoretical physics. Recently, however, a special class of systems has caught the attention of the scientific community, forcing physicists to abandon well-established rules.

When waves are able to absorb or release energy, so-called "exceptional points" occur, around which the waves show quite peculiar behaviour: lasers switch on, even though energy is taken away from them, light is being emitted only in one particular direction, and waves which are strongly jumbled emerge from the muddle in an orderly, well-defined state. Rather than just approaching such an exceptional point, a team of researchers at TU Wien (Vienna, Austria) together with colleagues in Brazil, France, and Israel now managed to steer a system around this point, with remarkable results that have now been published in the journal Nature.

Waves with Complex Frequencies

"Usually, the characteristic frequencies of waves in a particular system depend on several different parameters," says Professor Stefan Rotter (Institute for Theoretical Physics, TU Wien). The frequencies of microwaves in a metal container are determined by the size and by the shape of the container. These parameters can be changed, so that the frequencies of waves are changing as well.

"The situation becomes much more complicated, if the system can absorb or release energy," says Rotter. "In this case, our equations yield complex frequencies, in much the same way as in mathematics, when complex values emerge from the square root of a negative number." At first glance, this may look like a mere technicality, but in recent years new experimental findings have shown that these "complex frequencies" have indeed important physical applications.

Microwaves in a Metal Box

The strange characteristics of these complex frequencies become most apparent when the system approaches an "exceptional point." "Exceptional points occur, when the shape and the absorption of a system can be tuned in such a way that two different waves can meet at one specific complex frequency," Rotter explains. "At this exceptional point the waves not only share the same frequency and absorption rate, but also their spatial structure is the same. One may thus really interpret this as two wave states merging into a single one at the exceptional point."

Whenever such exceptional points show up in a system, curious effects can be observed: "We send two different wave modes through a wave guide that is tailored not only to approach the exceptional point, but actually to steer the waves around it," says Jörg Doppler, the first author of the study. No matter which one of the two possible modes is coupled into the system -- at the output, always the same mode emerges. When waves are coupled into the waveguide from the opposite direction, the other mode is favoured. "It is like driving a car into an icy two-lane tunnel, in which one slides around wildly, but from which one always comes out on the correct side of the road," says Doppler.

In order to test the theoretical models, Stefan Rotter and his group teamed up with researchers in France working on microwave structures, i.e., hollow metal boxes through which electromagnetic waves are sent to study their behaviour. To produce the strange wave behaviour near an exceptional point the waveguides need to follow very special design rules, which were devised at TU Wien with support from Alexei Mailybaev from IMPA (Brazil). The experiments were carried out in the group of Ulrich Kuhl at the University of Nice, where the predicted behaviour could now indeed be observed.

Read more at Science Daily

New index reveals likelihood of terrestrial or aquatic lifestyles of extinct mammals

Paleoparadoxia (left: Desmostylia, Paenungulata) and Ambulocetus (right: Cetacea, Cetartiodactyla) in two different ways of reconstructions -- top: terrestrial/semi-aquatic; bottom: obligate aquatic.
Despite the extensive fossil record of mammals, it is often difficult to use fossil data to reconstruct the lifestyles and habitats of extinct species. The fact that some species spent all or part of their time underwater, respectively similar to modern-day whales and seals, further complicates this.

Konami Ando and Shin-chi Fujiwara, researchers at Nagoya University, addressed this by developing a new index for predicting if a species lived its entire life in the water. The index is based on how the ribs must be relatively strong for an animal to walk or crawl over land, but not for it to swim. After establishing the index via measurements of living terrestrial, semiaquatic, and exclusively aquatic species, Ando and Fujiwara used it to predict that some extinct species could not have supported themselves on land.

Although mammals originally evolved as terrestrial organisms, cladistics shows that some returned to aquatic lives, and that this sometimes occurred independently. Examples include whales, dolphins, and manatees, which never leave the water, and seals and hippopotamuses, which split time between land and water. Studies of fossils of extinct species also suggest some species spent all or some of their time in the water. However, inability to use fossil records alone to determine a species' lifestyle has made this hard to confirm.

In their study, reported in the Journal of Anatomy, Ando and Fujiwara analyzed rib cages and their resistance to vertical compression in a range of mammalian species. This important factor represents an animal's ability to support its body weight against gravity while walking or crawling; a trait aquatic organisms do not need. The researchers investigated 26 modern-day terrestrial, semiaquatic, and exclusively aquatic species, including the killer whale, polar bear, dugong, giraffe, and hippopotamus. They used their data to establish an index for differentiating between groups with different habitats. They then applied the index to four extinct mammalian species, all of which had retained their four limbs but showed signs of having been partially or completely aquatic, to shed light on their potential lifestyles.

"We selected mammals with different habitats from a range of taxa and analyzed fossils for which the bones in the thoracic region were well-preserved," Fujiwara says. "We focused on the fracture loads of ribs. We found the sum of the fracture loads of all true ribs directly connected to the sternum divided by the body weight effectively separated the extant species groups by habitat. Exclusively aquatic species were clearly differentiated."

After establishing that the index could correctly classify living species with known habitats and lifestyles, the researchers applied it to extinct groups: Ambulocetus, an early ancestor of whales, and three desmostylian species, which are the keens of elephants and sea cows. This was to confirm or reject earlier hypotheses about these groups' lifestyles, which were based on other morphological findings.

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Jul 24, 2016

New remote-controlled microrobots for medical operations

Scientists at EPFL and ETHZ have developed a new method for building microrobots that could be used in the body to deliver drugs and perform other medical operations.
For the past few years, scientists around the world have been studying ways to use miniature robots to better treat a variety of diseases. The robots are designed to enter the human body, where they can deliver drugs at specific locations or perform precise operations like clearing clogged-up arteries. By replacing invasive, often complicated surgery, they could optimize medicine.

EPFL scientist Selman Sakar teamed up with Hen-Wei Huang and Bradley Nelson at ETHZ to develop a simple and versatile method for building such bio-inspired robots and equipping them with advanced features. They also created a platform for testing several robot designs and studying different modes of locomotion. Their work, published in Nature Communications, produced complex reconfigurable microrobots that can be manufactured with high throughput. They built an integrated manipulation platform that can remotely control the robots' mobility with electromagnetic fields, and cause them to shape-shift using heat.

A robot that looks and moves like a bacterium

Unlike conventional robots, these microrobots are soft, flexible, and motor-less. They are made of a biocompatible hydrogel and magnetic nanoparticles. These nanoparticles have two functions. They give the microrobots their shape during the manufacturing process, and make them move and swim when an electromagnetic field is applied.

Building one of these microrobots involves several steps. First, the nanoparticles are placed inside layers of a biocompatible hydrogel. Then an electromagnetic field is applied to orientate the nanoparticles at different parts of the robot, followed by a polymerization step to "solidify" the hydrogel. After this, the robot is placed in water where it folds in specific ways depending on the orientation of the nanoparticles inside the gel, to form the final overall 3D architecture of the microrobot.

Once the final shape is achieved, an electromagnetic field is used to make the robot swim. Then, when heated, the robot changes shape and "unfolds." This fabrication approach allowed the researchers to build microrobots that mimic the bacterium that causes African trypanosomiasis, otherwise known as sleeping sickness. This particular bacterium uses a flagellum for propulsion, but hides it away once inside a person's bloodstream as a survival mechanism.

The researchers tested different microrobot designs to come up with one that imitates this behavior. The prototype robot presented in this work has a bacterium-like flagellum that enables it to swim. When heated with a laser, the flagellum wraps around the robot's body and is "hidden."

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