Friday, September 29, 2017

Gamers Have an Advantage in Learning

Video games are apparently better than their reputation.

Neuropsychologists of the Ruhr-Universität Bochum let video gamers compete against non-gamers in a learning competition. During the test, the video gamers performed significantly better and showed an increased brain activity in the brain areas that are relevant for learning. Prof Dr Boris Suchan, Sabrina Schenk and Robert Lech report their findings in the journal Behavioural Brain Research.
The weather prediction task

The research team studied 17 volunteers who – according to their own statement – played action-based games on the computer or a console for more than 15 hours a week. The control group consisted of 17 volunteers who didn’t play video games on a regular basis. Both teams did the so-called weather prediction task, a well-established test to investigate the learning of probabilities. The researchers simultaneously recorded the brain activity of the participants via magnetic resonance imaging.

Sabrina Schenk and Boris Suchan tested how well video gamers learn.
Porträt
Credit: © RUB, Marquard

The participants were shown a combination of three cue cards with different symbols. They should estimate whether the card combination predicted sun or rain and got a feedback if their choice was right or wrong right away. The volunteers gradually learned, on the basis of the feedback, which card combination stands for which weather prediction. The combinations were thereby linked to higher or lower probabilities for sun and rain. After completing the task, the study participants filled out a questionnaire to sample their acquired knowledge about the cue card combinations.
Video gamers better with high uncertainties

The gamers were notably better in combining the cue cards with the weather predictions than the control group. They fared even better with cue card combinations that had a high uncertainty such as a combination that predicted 60 percent rain and 40 percent sunshine.

The analysis of the questionnaire revealed that the gamers had acquired more knowledge about the meaning of the card combinations than the control group. “Our study shows that gamers are better in analysing a situation quickly, to generate new knowledge and to categorise facts – especially in situations with high uncertainties,” says first author Sabrina Schenk.

This kind of learning is linked to an increased activity in the hippocampus, a brain region that plays a key role in learning and memory. “We think that playing video games trains certain brain regions like the hippocampus”, says Schenk. “That is not only important for young people, but also for older people; this is because changes in the hippocampus can lead to a decrease in memory performance. Maybe we can treat that with video games in the future.”
Funding

The study was conceived as part of Collaborative Research Centre 874, which has been funded since 2010 by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) to investigate memory formation and sensory processing.
Original publication



Contacts and sources:
Prof Dr Boris Suchan
Department of Clinical Neuropsychology
Institute for Cognitive Neuroscience
Faculty of Psychology
Ruhr-Universität Bochum


Citation: Sabrina Schenk, Robert K. Lech, Boris Suchan: Games people play: How video games improve probabilistic learning, in: Behavioral Brain Research, 2017, DOI: 10.1016/j.bbr.2017.08.027
 

5000-Year-Old Words: Scandinavia's Earliest Farmers Exchanged Terminology With Indo-Europeans

5,000 years ago, the Yamnaya culture migrated into Europe from the Caspian steppe. In addition to innovations such as the wagon and dairy production, they brought a new language - Indo-European - that replaced most local languages the following millennia. But local cultures also influenced the new language, particularly in southern Scandinavia, where Neolithic farmers made lasting contributions to Indo-European vocabulary before their own language went extinct, new research shows.

Most historical linguists agree that words such as 'wheel', 'wagon', 'horse', 'sheep', 'cow', 'milk' and 'wool' can be attributed to the Yamnaya people who migrated into Europe from the Caspian steppe 5,000 years ago. The nomadic and pastoral Yamnayans introduced their material culture to the local peoples through a new language known as Proto-Indo-European, from which most European languages descend.

However, not all words in the European languages are of Proto-Indo-European origin, linguists say; there are words for flora and fauna, which must have been incorporated into Indo-European from local cultures. But where could such cultural exchange have taken place? According to a new study published in American Journal of Archaeology by archaeologist Rune Iversen and linguist Guus Kroonen from the University of Copenhagen, southern Scandinavia 2,800 BC provides an ideal setting for such an exchange:

This is a schematic impression of how the different Indo-European branches may have absorbed lexical items (circles) from previously spoken languages in the linguistically complex setting of Europe from the third millennium BC.
Credit: University of Copenhagen

"The archaeological evidence tells us that between 2,800 and 2,600 BC two very different cultures co-existed in southern Scandinavia: there was the local, Neolithic culture known as the Funnel Beaker Culture with its characteristic funnel-shaped ceramics and collective burial practices and the new Single Grave Culture influenced by the Yamnaya culture. The Funnel Beaker Culture was eventually superseded by the Single Grave Culture, but the transition took hundreds of years in the eastern part of southern Scandinavia, and the two cultures must have influenced each other during this time, "says archaeologist Rune Iversen, who has specialised in this particular transitional period.

Yamna culture tomb in Volgograd oblast'
File:Yamna culture tomb.jpg
Credit: XVodolazx / Wikimedia Commons


Peas, beans, turnips and shrimps

Historical linguist Guus Kroonen points to a number of words for local flora and fauna and important plant domesticates that the incoming speakers of Indo-European could not have brought with them to southern Scandinavia.

"There is a cluster of words in European languages such as Danish, English, and German - the Germanic languages - which stand out because they do not conform to the established sound changes of Indo-European vocabulary. It is words like sturgeon, shrimp, pea, bean and turnip that cannot be reconstructed to the Proto-Indo-European ancestor," Guus Kroonen explains and adds:

This is the distribution of the earliest Single Grave culture burials in southern Scandinavia, ca. 2850-2800. The Single Grave Culture co-existed with the local Funnel Beaker Culture, which inhabited the island of Zealand, for 200 years.
Credit; University of Copenhagen

"This tells us that these words must have entered Indo-European after it had spread from the Caspian steppe to the various parts of Europe. In other words: the new Single Grave Culture is likely to have adopted much farming and hunting terminology from the local Funnel Beaker Culture that inhabited southern Scandinavia and Denmark till around 2,600 BC. When Indo-European in Northern Europe developed into Proto-Germanic, the terminology for local flora and fauna was preserved, which is why we know and can study the terms today."

Guus Kroonen adds that this farming terminology may be vestiges of a now extinct language spoken by the people who initially brought farming to Europe from Anatolia 9,000-6,000 years ago.





Contacts and sources:
Archaeologist Rune Iversen
University of Copenhagen

Linguist Guus Kroonen
Roots of Europe, University of Copenhagen

Citation:  Talking Neolithic: Linguistic and Archaeological Perspectives on How Indo-European Was Implemented in Southern Scandinavia by  Rune Iversen's and Guus Kroonen  American Journal of Archaeology.  http://www.jstor.org/stable/10.3764/aja.121.4.0511

Thursday, September 28, 2017

Mapping the Thylacine's Mysterious Loss from Mainland

Ancient DNA extracted from fossil bones and museum specimens has shed new light on the mysterious loss of the Tasmanian tiger (thylacine) from Australia's mainland.

The University of Adelaide study, published in the Journal of Biogeography, traces the history of thylacine populations over the last 30,000 years.

The researchers from the University's Australian Centre for Ancient DNA (ACAD) found that a large and genetically diverse population of thylacines lived in western regions of Australia right up to their extinction from the mainland around 3000 years ago, separated from the eastern population.

These are Thylacine jaw bones kept in the Tasmanian Museum and Art Gallery.
Credit: University of Adelaide

They have concluded that climate change from about 4000 years ago, in particular more drought-prone seasons caused by the onset of the El Niño-Southern Oscillation, was the likely main cause of mainland extinction.

"The thylacine was a marsupial carnivore, now infamous for its recent human-driven extinction from Tasmania following the arrival of Europeans and their bounty hunting schemes," says project leader Associate Professor Jeremy Austin, Deputy Director of ACAD.

"Thylacines once lived across most of the Australian mainland, but by the time Europeans arrived in the late 1700s they were found only in Tasmania. They became extinct about 150 years later, with the last of the species dying in Hobart Zoo in 1936. But the reasons for their disappearance from mainland Australia and continuing survival in Tasmania has remained a mystery." Climate change, increased human activity and the introduction of the dingo are the three main causes debated.

The researchers generated 51 new thylacine mitrochondrial DNA genome sequences from fossil bones and museum specimens - the largest dataset of thylacine DNA to date.

This provided the first genetic evidence that mainland thylacines split into eastern and western populations in southern Australia before the last Ice Age peak of about 25,000 years ago.

"We wanted to understand why thylacines went extinct on the mainland, but survived in Tasmania," says lead author and PhD student Lauren White. "The ancient DNA tells us that the mainland extinction was rapid, and not the result of intrinsic factors such as inbreeding or loss of genetic diversity.

"We also found evidence of a population crash, reducing numbers and genetic diversity of thylacines in Tasmania around the same time," says Associate Professor Austin. "This mirrors what happened with another carnivorous marsupial, the Tasmanian devil, which still lives in Tasmania. Unlike the devil, however, it appears that the population of thylacines was expanding at the time of European arrival."

"Tasmania would have been somewhat shielded from the warmer, drier climate because of its higher rainfall but it appears that this population was also affected by the El Niño event before starting to recover."


 Contacts and sources:
Associate Professor Jeremy Austin
University of Adelaide 

Citation: Ancient mitochondrial genomes reveal the demographic history and phylogeography of the extinct, enigmatic thylacine (Thylacinus cynocephalus)
Authors: Lauren C. White, Kieren J. Mitchell, Jeremy J. Austin
http://dx.doi.org/10.1111/jbi.13101

Robots to Emulate Nature’s Perfect Pursuit

Although its name may not inspire fear and dread in the way of a great white shark, or Bengal tiger, the humble dragonfly is widely considered nature’s most effective predator.

This phenomenally talented aerialist is able to target, pursue and capture tiny flying prey in mid-air at speeds of up to 60 km/h—even if that target attempts to disappear within a seething swarm—with an incredible hit-rate of over 95%.

With such abilities having obvious application to human needs in the areas of defence and surveillance, along with health systems, environmental monitoring and manufacturing, researchers at the University of Adelaide recently set themselves the task of unlocking and harnessing the dragonfly’s secrets.

According to lead researcher and neuroscientist Dr Steven Wiederman, from the Adelaide Medical School, they’re succeeding.

“We’re delighted to say that we’ve been able to build an autonomous robot that, using computational models bio-inspired by the dragonfly’s neuronal processing, can effectively and efficiently pursue targets in unstructured environments,” says Steven.



The team, which also includes researchers in the fields of mechanical engineering and computer science, first investigated how the dragonfly was able to focus on a single moving target and shut out all else.

“We recorded the activity of dragonfly neurons, and discovered the first identified neuron in any animal that exhibits an ‘attentional spotlight’; selecting a single target amidst distracters.

“We also recorded from target-detecting neurons that predictively encode trajectory, enabling the dragonfly to estimate its target’s future location and ambush it.”

The processes displayed were then adapted into a unique algorithm to emulate the dragonfly’s visual tracking capability. When tested in various nature-mimicking virtual reality environments, the algorithm performed every bit as accurately as other state-of-the-art algorithms, but while running up to 20 times faster, so requiring less relative processing power.

“We’re very excited to continue our research now,” says Steven, “and further define the fundamental principles that underlie neuronal processing. Translating these principles into the development of advanced artificial vision systems could result in some incredibly effective autonomous robotics, drones, neuronal prosthetics, and many more applications.”





Contacts and sources:
The University of Adelaide

Perovskite Solar Cells Reach Record Long-Term Stability, Efficiency Over 20 Percent

Perovskite solar cells (PSCs) can offer high light-conversion efficiency with low manufacturing costs. But to be commercially viable, perovskite films must also be durable and not degrade under solar light over time. 

Ecole Polytechnique Fédérale de Lausanne (EPFL) scientists have now greatly improved the operational stability of PSCs, retaining more than 95% of their initial efficiencies of over 20 % under full sunlight illumination at 60oC for more than 1000 hours. The breakthrough, which marks the highest stability for perovskite solar cells, is published in Science.

Challenges of stability

Conventional silicon solar cells have reached a point of maturation, with efficiencies plateauing around 25% and problems of high-cost manufacturing, heavyweight, and rigidity has remained largely unresolved. On the contrary, a relatively new photovoltaic technology based on perovskite solar cells has already achieved more than 22% efficiency.


Structure of β-CuSCN and cross-sectional SEM micrograph of a complete solar cell.

Credit: M. Ibrahim Dar/EPFL

Given the vast chemical versatility, and the low-cost processability of perovskite materials, the PSCs hold the promise to lead the future of photovoltaic technology by offering cheap, light weight and highly efficient solar cells. But until now, only highly expensive, prototype organic hole-transporting materials (HTMs,selectively transporting positive charges in a solar cell) have been able to achieve power-conversion efficiencies over 20%. And by virtue of their ingredients, these hole-transporting materials adversely affect the long-term operational stability of the PSC.

Therefore, investigating cheap and stable hole transporters that produce equally high efficiencies is in great demand to enable large-scale deployment of perovskite solar cells. Among various inorganic HTMs, cuprous thiocyanate (CuSCN) stands out as a stable, efficient and cheap candidate ($0.5/gr versus $500 /gr for the commonly used spiro-OMeTAD). But previous attempts to use CuSCN as a hole transporter in perovskite solar cells have yielded only moderately stabilized efficiencies and poor device stability, due to problems associated with depositing a high-quality CuSCN layer atop of the perovskite film, as wells as the chemical instability of the CuSCN layer when integrated into a 
perovskite solar cell.


A stable solution

Now, researchers at Michael Grätzel's lab at EPFL, in a project led by postdocs Neha Arora and M. Ibrahim Dar, have introduced two new concepts that overcome the major shortcomings of CuSCN-based perovskite solar cells. First, they developed a simple dynamic solution-based method for depositing highly conformal, 60-nm thick CuSCN layers that allows the fabrication of perovskite solar cells with stabilized power-conversion efficiencies exceeding 20%. This is comparable to the efficiencies of the best performing, state-of-the-art spiro-OMeTAD-based perovskite solar cells.

Second, the scientists introduced a thin spacer layer of reduced graphene oxide between the CuSCN and a gold layer. This innovation allowed the perovskite solar cells to achieve excellent operational stability, retaining over 95% of their initial efficiency while operating at a maximum power point for 1000 hours under full-sun illumination at 60 °C. This surpasses even the stability of organic HTM-based perovskite solar cells that are heavily researched and have recently dominated the field.

The researchers also discovered that the instability of the perovskite devices originates from the degradation of CuSCN/gold contact during the solar cell's operation.

"This is a major breakthrough in perovskite solar-cell research and will pave the way for large-scale commercial deployment of this very promising new photovoltaic technology," says Michael Grätzel. "It will benefit the numerous scientists in the field that have been intensively searching for a material that could replace the currently used, prohibitively expensive organic hole-transporters," adds M. Ibrahim Dar.


Contacts and sources:
Nik Papageorgiou /Professor Michael Grätzel /Dr M. Ibrahim Dar 
Ecole Polytechnique Fédérale de Lausanne (EPFL)

Citation: Neha Arora, M. Ibrahim Dar, Alexander Hinderhofer, Norman Pellet, Frank Schreiber, Shaik Mohammed Zakeeruddin, Michael Grätzel. Perovskite solar cells with CuSCN hole extraction layers yield stabilized efficiencies >20%. Science 28 September 2017.

Chimpanzees Figure Out How to Make and Use Tools Without Observing Others

New observations have lead researchers to believe that chimpanzees can use tools spontaneously to solve a task, without needing to watch others first.

The evidence of chimpanzees (Pan troglodytes) spontaneously using sticks to scoop food from water surfaces is published in the open-access journal PeerJ.

Researchers from the University of Birmingham, UK, and University of Tübingen, Germany, looked for the spontaneous re-occurrence of a tool-use behaviour practiced in wild chimpanzees where sticks are used to 'scoop' algae from the top of water surfaces.

animal-20413_1920
Credit:  University of Birmingham

Chimpanzees at Twycross Zoo, UK, were provided with a container of water with pieces of floating food. The tested chimpanzees successfully used the sticks, and moreover, spontaneously showed the same underlying action pattern (a scooping action of the stick) as their wild cousins do.

The results challenge the accepted belief that chimpanzees need to learn from each other how to use tools, and instead suggest that some (if not all) forms of tool-use are instead within their pre-existing behavioural repertoire (what the authors call "latent solutions").

Elisa Bandini explained, "The commonly held belief is that chimpanzee behaviour is cultural, much like how human culture has been passed between groups. But if that was the case, the same behaviours should never re-occur in naïve subjects. Nobody, for example, could accurately reinvent extinct languages on the spot."

Due to the close genetic ties between humans and chimpanzees, it is likely that naïve individuals also spontaneously invented some forms of early human material culture.

Dr Claudio Tennie added, "Given these results, the long-held assumption that apes must observe one another in order to show these behaviours may have been due to an illusion of cultural transmission - created by the apes arriving at the same behaviour independently."

The University of Birmingham and Twycross Zoo has a Memorandum of Understanding (MoU), which promotes teaching, research and other activities for the mutual benefit of both parties. This research was conducted under the MoU agreement, using Twycross' extensive history with, and in caring for, primates.

The researchers, working with Twycross Zoo and the British and Irish Association of Zoos and Aquariums (BIAZA), have devised a new Enclosure Design Tool to keep the chimpanzees physically and mentally active and socially interactive, in a bid to ensure their behaviour emulates chimpanzee behaviour in the wild. This will help show how wild chimps really behave, enhance their welfare and improve their chance of survival in the wild, should reintroduction of future generations ever be required.




Contacts and sources:
Luke Harrison
University of Birmingham

Unprecedented: Hundreds of Species Surfed 2011 Tsunami To Hawaii and American West Coast from Japan

The 2011 Japanese tsunami set the stage for something unprecedented. For the first time in recorded history, scientists have detected entire communities of coastal species crossing the ocean by floating on makeshift rafts. Nearly 300 species have appeared on the shores of Hawaii and the U.S. West Coast attached to tsunami debris, marine biologists from the Smithsonian Environmental Research Center, Williams College and other institutions reported in the journal Science on Thursday.

The tsunami formed March 11, 2011, triggered by an earthquake of 9.0 moment magnitude that struck Japan the same day. At its tallest point, the tsunami towered 125 feet over Japan's Tohoku coast and swept millions of objects out to sea, from small pieces of plastic to fishing boats and docks. These kinds of objects, scientists said, helped the species attached to them complete the transoceanic journey.

These are marine sea slugs from a Japanese vessel from Iwate Prefecture, washed ashore in Oregon in April 2015

Credit: John Chapman


"I didn't think that most of these coastal organisms could survive at sea for long periods of time," said Greg Ruiz, a co-author and marine biologist at the Smithsonian Environmental Research Center. "But in many ways they just haven't had much opportunity in the past. Now, plastic can combine with tsunami and storm events to create that opportunity on a large scale."

Scientists began finding tsunami debris washing up in Hawaii and western North America in 2012, with living organisms still attached. From 2012 to 2017, they continued to find debris, including buoys, crates, vessels and docks. In total, they detected 289 living species on tsunami debris originating from Japan, and they suspect there are far more that escaped their notice. While the arrivals have slowed down, they have not stopped. The team was still finding new species when the study period ended in 2017.

Mollusks such as mussels occurred most frequently of all invertebrate groups. Worms, hydroids (sea anemone and jellyfish relatives), crustaceans and bryozoans that form branch-like underwater colonies were not far behind. Nearly two-thirds of the species had never been seen on the U.S. West Coast. None of the species were known--or expected--to survive a transoceanic rafting voyage between continents, largely because the open ocean is considered to be a harsher environment for creatures used to more hospitable waters of the coasts. However, the slower speed of ocean rafts (1 or 2 knots, compared to 20 or more knots for commercial ships) may have allowed species to gradually adjust to their new environments. The sluggish pace of these "floating islands" may also have made it easier for some species to reproduce and for their larvae to attach to the debris.

A vessel carried by the Japanese tsunami washed ashore in Oregon, coated in gooseneck barnacles that colonized the boat as it floated across the North Pacific. Several Japanese species also survived the voyage, in the crevices inside and underneath the boat.

Credit: John Chapman

The increase in marine plastics and other more durable debris also made survival easier, according to the researchers. Much of the debris the scientists found rafted ashore was made of fiberglass or other plastic materials that do not decompose and could easily survive six or more years at sea. These materials started becoming common in the mid-20th century, and their dominance is only expected to rise.

"There is huge potential for the amount of marine debris in the oceans to increase significantly," said lead author James Carlton, an invasive species expert with the Maritime Studies Program of Williams College and Mystic Seaport in Connecticut. According to a 2015 report in Science, over 10 million tons of plastic waste enter the ocean each year, and that figure may increase 10 times by 2025. Hurricanes and typhoons, which scientists also expect to become more frequent due to climate change, also can sweep debris out into the ocean.

So far, no new species are known to have colonized the West Coast directly due to the 2011 tsunami. However, it can take years after a nonnative species first arrives to detect a newly established population. This provides a window of time for action, although the full consequences of the tsunami-driven rafting are still uncertain.

"This has turned out to be one of the biggest, unplanned, natural experiments in marine biology, perhaps in history," said co-author John Chapman of Oregon State University.

However, scientists largely agree that prevention is the most effective way to combat invasive species. Since preventing tsunamis is not an option, Ruiz suggested the main focus should be managing plastic.

"There's an increasing load of plastic and microplastics at sea that are thought to have significant consequences for biology and ecology," he said. "This is one other dimension and consequence of plastics and manmade material that deserves attention."

Moss Landing Marine Laboratories, the Oregon Institute of Marine Biology and Portland State University also contributed to this report.

Supersonic Gas Streams Left Over from The Big Bang Drive Massive Black Hole Formation

An international team of researchers has successfully used a super-computer simulation to recreate the formation of a massive black hole from supersonic gas streams left over from the Big Bang. Their study, published in this week's Science, shows this black hole could be the source of the birth and development of the largest and oldest super-massive black holes recorded in our Universe.

"This is significant progress. The origin of the monstrous black holes has been a long-standing mystery and now we have a solution to it," said author and Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) Principal Investigator Naoki Yoshida.

Recent discoveries of these super-massive black holes located 13 billion light years away, corresponding to when the universe was just five per cent of its present age, pose a serious challenge to the theory of black hole formation and evolution. The physical mechanisms that form black holes and drive their growth are poorly understood.

These are projected density distributions of dark matter (background and top panel) and gas (bottom three panels) components when the massive star forms. The stellar cradle is extremely assymmetry as a wide wedge-shaped structure (middle panel) due to the initial supersonic gas motions left over from the Big Bang. The circle in the right panel indicates the gravitationally unstable region with mass of 26,000 solar-masses.

Credit: Shingo Hirano


Theoretical studies have suggested these black holes formed from remnants of the first generation of stars, or from a direct gravitational collapse of a massive primordial gas cloud. However, these theories either have difficulty in forming super-massive black holes fast enough, or require very particular conditions.

Yoshida and JSPS Overseas Research Fellow Shingo Hirano, currently at the University of Texas at Austin, identified a promising physical process through which a massive black hole could form fast enough. The key was incorporating the effect of supersonic gas motions with respect to dark matter.

This is the gas density distribution around the new-born protostar. The left-to-right supersonic gas motion results in the non-spherical, compressed density structure. The collapsed inner cloud also shows the turbulated object, which can rapidly accrete onto the central protostar and cause a fast mass growth of it.

Credit:  Shingo Hirano

The team's super-computer simulations showed a massive clump of dark matter had formed when the universe was 100 million years old. Supersonic gas streams generated by the Big Bang were caught by dark matter to form a dense, turbulent gas cloud. Inside, a protostar started to form, and because the surrounding gas provided more than enough material for it to feed on, the star was able to grow extremely big in a short amount of time without releasing a lot of radiation.

"Once reaching the mass of 34,000 times that of our Sun, the star collapsed by its own gravity, leaving a massive black hole. These massive black holes born in the early universe continued to grow and merge together to become a supermassive black hole," said Yoshida.

This the evolution of the temperature and density structure in the protostellar accretion phase after the protostar formation. The rapid accretion of dense gas cloud (white contour) constricts an expansion of the photoionized region (red) which is possible to shut off the gas accretion.

Credit: Takashi Hosokawa

"The number density of massive black holes is derived to be approximately one per a volume of three billion light-years on a side - remarkably close to the observed number density of supermassive black holes," said Hirano.

The result from this study will be important for future research into the growth of massive black holes. Especially with the increased number of black hole observations in the far universe that are expected to be made when NASA's James Webb Space Telescope is launched next year.

This research was published in Science on September 28.

Aterui, one of the supercomputers this work used, is operated by the Center for Computational Astrophysics (CfCA) of the National Astronomical Observatory of Japan (NAOJ).


Contacts and sources:
Motoko Kakubayashi 
 Kavli Institute for the Physics and Mathematics of the Universe

Earliest Evidence for Domesticated Sorghum in Africa

Archaeologists examining plant impressions within broken pottery have discovered the earliest evidence for domesticated sorghum in Africa. The evidence comes from an archaeological site (known as KG23) in eastern Sudan, dating from 3500 to 3000 BC, and is associated with an ancient archaeological culture known as the Butana Group.


Credit: Drawing by Dorian Q. Fuller


Sorghum is a native African grass that was utilized for thousands of years by prehistoric peoples, and emerged as one of the world's five most important cereal crops, along with rice, wheat, barley, and maize.

 For a half century scholars have hypothesized that native African groups were domesticating sorghum outside the winter rainfall zone of the ancient Egyptian Nile Valley (where wheat and barley cereals were predominant) in the semi-arid tropics of Africa, but no archaeological evidence existed. This new discovery in eastern Sudan reveals that during the 4th millennium BC, peoples of the Butana Group were intensively cultivating wild stands of sorghum until they began to change the plant genetically into domesticated morphotypes.

Along with the recent discovery of domesticated pearl millet in eastern Mali around 2500 BC, this latest discovery in eastern Sudan pushes back the process for domesticating summer rainfall cereals another thousand years in the Sahel, with sorghum, providing new evidence for the earliest known native African cultigen.



Contacts and sources:
Frank Winchell
The University of Chicago Press

Citation: Evidence for Sorghum Domestication in Fourth Millennium BC Eastern Sudan: Spikelet Morphology from Ceramic Impressions of the Butana Group
Frank Winchell, Chris J. Stevens, Charlene Murphy, Louis Champion, and Dorian Q. Fuller 
Current Anthropology  published by The University of Chicago Press and sponsored by the Wenner-Gren Foundation for Anthropological Research.    http://www.journals.uchicago.edu/doi/10.1086/693898

Rewriting Prehistory: Stone Age Child Reveals Modern Humans Emerged More Than 300,000 Years Ago



South Africa is well-known for its hominin fossil record. But this time, results from a study of ancient DNA presented in the September 28th First Release early online issue of Science show that the 2000-year-old remains of a boy found at Ballito Bay in KwaZulu-Natal during the 1960s, helped to rewrite human history.

Marlize Lombard, Professor of Stone Age archaeology at the University of Johannesburg, initiated collaboration with geneticists from Uppsala University in Sweden and the University of the Witwatersrand, who put together a team of experts at the Uppsala laboratory.

They reconstructed the full genome of the Ballito Bay child, together with the genomes of six other individuals from KwaZulu-Natal who lived between 2300 and 300 years ago.

This is Marlize Lombard (University of Johannesburg) excavating at Sibudu Cave (under the direction of Prof Lyn Wadley, University of the Witwatersrand), about 40 km southeast of Ballito Bay where the boy was found. The cave was intermittently occupied by humans from at least 77 000 years ago who might have been ancestral to the Ballito boy.
Photograph: Lyn Wadley, University of the Witwatersrand.

Three Stone Age individuals who lived between 2300 and 1800 years ago were found to be genetically related to the descendants of Khoe-San groups living in southern Africa today. The remains of the other four individuals who lived 500-300 years ago during the Iron Age, were genetically related to present-day South Africans of West African descent.

Because the boy from Ballito Bay was of hunter-gatherer descent, living at a time before migrants from further north in Africa reached South African shores, his DNA could be used to estimate the split between modern humans and earlier human groups as occurring between 350 000 and 260 000 years ago. "This means that modern humans emerged earlier than previously thought", says Mattias Jakobsson, population geneticist at Uppsala University, who headed the project together with Marlize Lombard from the University of Johannesburg.

This image shows the new demographic model of African population history and estimated divergences resulting from the ancient DNA study on hunter-gatherer remains from South Africa presented in the Sept. 28th (early online) issue of Science.


Credit: Uppsala University

The 350 000 to 260 000 years estimate also coincides with the Florisbad skull, who was a contemporary of the small-brained Homo naledi in South Africa. "It now seems that at least two or three Homo species occupied the southern African landscape during this time, which also represents the early phases of the Middle Stone Age", says Lombard.

Cumulatively, the fossil, ancient DNA and archaeological records indicate that the transition from archaic to modern humans might not have occurred in only one place in Africa. Instead, regions including southern and northern Africa (as recently reported) probably played a role. "Thus, both palaeo-anthropological and genetic evidence increasingly points to multiregional origins of anatomically modern humans in Africa, i.e. Homo sapiens did not originate in one place in Africa, but might have evolved from older forms in several places on the continent with gene flow between groups from different places", says Carina Schlebusch.




This is Dr. Helena Malmström (Uppsala University) sampling in South Africa for ancient human DNA.

Photograph: Mattias Jakobsson (Uppsala University)

The team sequenced the genomes of seven individuals who lived in southern Africa 2300-300 years ago. The three oldest individuals dating to 2300-1800 years ago were genetically related to the descendants of the southern Khoe-San groups, and the four younger individuals who lived 500-300 years ago were genetically related to current-day South African Bantu-speaking groups. "This illustrates the population replacement that occurred in southern Africa", says co-first author Carina Schlebusch, population geneticist at Uppsala University.

The authors estimate the divergence among modern humans to have occurred between 350,000 and 260,000 years ago, based on the ancient Stone Age hunter-gatherer genomes. The deepest split time of 350,000 years ago represents a comparison between an ancient Stone Age hunter-gatherer boy from Ballito Bay on the east coast of South Africa and the West African Mandinka. "This means that modern humans emerged earlier than previously thought", says Mattias Jakobsson, population geneticist at Uppsala University who headed the project together with Stone Age archaeologist Marlize Lombard at the University of Johannesburg.

The fossil record of east Africa, and in particular the Omo and Herto fossils have often been used to set the emergence of anatomically modern humans to about 180,000 years ago. The deeper estimate for modern human divergence at 350,000-260,000 years ago coincides with the Florisbad and Hoedjiespunt fossils, contemporaries of the small-brained Homo naledi in southern Africa. "It now seems that at least two or three Homo species occupied the southern African landscape during this time period, which also represents the early phases of the Middle Stone Age", says Marlize Lombard. It will be interesting to see in future if we find any evidence of interaction between these groups.

"We did not find any evidence of deep structure or archaic admixture among southern African Stone Age hunter-gatherers, instead, we see some evidence for deep structure in the West African population, but that affects only a small fraction of their genome and is about the same age as the deepest divergence among all humans", says Mattias Jakobsson.

The authors also found that all current-day Khoe-San populations admixed with migrant East African pastoralists a little over a thousand years ago. "We could not detect this widespread East African admixture previously since we did not have an un-admixed San group to use as reference. Now that we have access to ancient DNA of people who lived on the landscape before the East African migration, we are able to detect the admixture percentages in all San groups. The admixture percentages in the Khoekhoe, historically identified as pastoralists, are higher than previously estimated", says Carina Schlebusch.

Of the Iron Age individuals, three carry at least one Duffy null allele, protecting against malaria, and two have at least one sleeping-sickness-resistance variant in the APOL1 gene. The Stone Age individuals do not carry these protective alleles. "This tells us that Iron Age farmers carried these disease-resistance variants when they migrated to southern Africa", says co-first author Helena Malmström, archaeo-geneticist at Uppsala University.

Marlize Lombard said that "archaeological deposits dating to the time of the split by 350,000-260,000 years ago, attest to South Africa being populated by tool-making hunter-gatherers at the time. Although human fossils are sparse, those of Florisbad and Hoedjiespunt are seen as transitional to modern humans." These fossils may therefore be ancestral to the Ballito Bay boy and other San hunter-gatherers who lived in southern Africa 2000 years ago.

The transition from archaic to modern humans might not have occurred in one place in Africa but in several, including southern Africa and northern Africa as recently reported. "Thus, both palaeo-anthropological and genetic evidence increasingly points to multiregional origins of anatomically modern humans in Africa, i.e. Homo sapiens did not originate in one place in Africa, but might have evolved from older forms in several places on the continent with gene flow between groups from different places", says Carina Schlebusch.

"It is remarkable that we can now sequence entire genomes of ancient human remains from tropical areas, such as the southeast coast of South Africa", says Helena Malmström. This is promising for our several ongoing investigations in Africa.


Contacts and sources:
Prof Marlize Lombard, University of Johannesburg
Mattias Jakobsson Uppsala University

 

K2 Incoming: The Most Primitive Comet Ever Seen, Still 1.5 Billion Miles Away

A solitary frozen traveler has been journeying for millions of years toward the heart of our planetary system. The wayward vagabond, a city-sized snowball of ice and dust called a comet, was gravitationally kicked out of the Oort Cloud, its frigid home at the outskirts of the solar system. This region is a vast comet storehouse, composed of icy leftover building blocks from the construction of the planets 4.6 billion years ago.


Credit: NASA, ESA, and D. Jewitt (UCLA)

NASA's Hubble Space Telescope has photographed the farthest active inbound comet ever seen, at a whopping distance of 1.5 billion miles from the Sun (beyond Saturn's orbit). Slightly warmed by the remote Sun, it has already begun to develop an 80,000-mile-wide fuzzy cloud of dust, called a coma, enveloping a tiny, solid nucleus of frozen gas and dust. These observations represent the earliest signs of activity ever seen from a comet entering the solar system's planetary zone for the first time.

The comet, called C/2017 K2 (PANSTARRS) or "K2", has been travelling for millions of years from its home in the frigid outer reaches of the solar system, where the temperature is about minus 440 degrees Fahrenheit. The comet's orbit indicates that it came from the Oort Cloud, a spherical region almost a light-year in diameter and thought to contain hundreds of billions of comets. Comets are the icy leftovers from the formation of the solar system 4.6 billion years ago and therefore pristine in icy composition.

Since we’re seeing it so far away, past the orbit of Saturn, K2 is still in its early phase of activity, likely making it the most primitive comet anyone has ever seen.

Video: NASA, STScI, and Goddard Space Flight Center/K. Jackson;
Music: “Space Cake” by Donn Wilerson [BMI] and Lance Sumner [BMI]; Killer Tracks BMI; Killer Tracks Production Music.

"K2 is so far from the Sun and so cold, we know for sure that the activity — all the fuzzy stuff making it look like a comet — is not produced, as in other comets, by the evaporation of water ice," said lead researcher David Jewitt of the University of California, Los Angeles. "Instead, we think the activity is due to the sublimation [a solid changing directly into a gas] of super-volatiles as K2 makes its maiden entry into the solar system's planetary zone. That's why it's special. This comet is so far away and so incredibly cold that water ice there is frozen like a rock."

This illustration shows the orbit of comet C/2017 K2 PANSTARRS (K2) on its maiden voyage into the solar system. The Hubble Space Telescope observed K2 when it was 1.5 billion miles from the Sun, halfway between the orbits of Saturn and Uranus. The observations revealed a fuzzy cloud of dust, called a coma, surrounding the icy visitor, evidence that the frozen comet is being warmed by the Sun and releasing material. K2 is the farthest active inbound comet ever observed.

K2 has been traveling toward the Sun for millions of years from its home in the Oort Cloud, a spherical region at the edge of our solar system. The graphic shows the comet in its inbound journey, high above the plane of the major planets' orbits. The orbits of the giant planets, from Jupiter to Neptune, are also shown in the diagram. The farthest object from the Sun depicted here is the dwarf planet Pluto, which resides in the Kuiper Belt, a vast rim of primordial debris encircling our solar system.
Schematic of Comet C/2017 K2's Approach to the Solar System
Credits:  NASAESA, and D. Jewitt (UCLA)

Based on the Hubble observations of K2's coma, Jewitt suggests that sunlight is heating frozen volatile gases - such as oxygen, nitrogen, carbon dioxide, and carbon monoxide - that coat the comet's frigid surface. These icy volatiles lift off from the comet and release dust, forming the coma. Past studies of the composition of comets near the Sun have revealed the same mixture of volatile ices.

"I think these volatiles are spread all through K2, and in the beginning billions of years ago, they were probably all through every comet presently in the Oort Cloud," Jewitt said. "But the volatiles on the surface are the ones that absorb the heat from the Sun, so, in a sense, the comet is shedding its outer skin. Most comets are discovered much closer to the Sun, near Jupiter's orbit, so by the time we see them, these surface volatiles have already been baked off. That's why I think K2 is the most primitive comet we've seen."

K2 was discovered in May 2017 by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) in Hawaii, a survey project of NASA's Near-Earth Object Observations Program. Jewitt used Hubble's Wide Field Camera 3 at the end of June to take a closer look at the icy visitor.

Hubble's sharp "eye" revealed the extent of the coma and also helped Jewitt estimate the size of the nucleus — less than 12 miles across — though the tenuous coma is 10 Earth diameters across.

This vast coma must have formed when the comet was even farther away from the Sun. Digging through archival images, Jewitt's team uncovered views of K2 and its fuzzy coma taken in 2013 by the Canada-France-Hawaii Telescope (CFHT) in Hawaii. But the object was then so faint that no one noticed it.

"We think the comet has been continuously active for at least four years," Jewitt said. "In the CFHT data, K2 had a coma already at 2 billion miles from the Sun, when it was between the orbits of Uranus and Neptune. It was already active, and I think it has been continuously active coming in. As it approaches the Sun, it's getting warmer and warmer, and the activity is ramping up."

But, curiously, the Hubble images do not show a tail flowing from K2, which is a signature of comets. The absence of such a feature indicates that particles lifting off the comet are too large for radiation pressure from the Sun to sweep them back into a tail.

Astronomers will have plenty of time to conduct detailed studies of K2. For the next five years, the comet will continue its journey into the inner solar system before it reaches its closest approach to the Sun in 2022 just beyond Mars' orbit. "We will be able to monitor for the first time the developing activity of a comet falling in from the Oort Cloud over an extraordinary range of distances," Jewitt said. "It should become more and more active as it nears the Sun and presumably will form a tail."

Jewitt said that NASA's James Webb Space Telescope, an infrared observatory scheduled to launch in 2018, could measure the heat from the nucleus, which would give astronomers a more accurate estimate of its size.

The team's results will appear in the September 28 issue of The Astrophysical Journal Letters.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.


Contacts and sources:
Donna Weaver / Ray Villard
Space Telescope Science Institute, Baltimore, Maryland

David Jewitt
University of California, Los Angeles, California

Wednesday, September 27, 2017

New Light on How Earth and Mars Were Created

Analyzing a mixture of earth samples and meteorites, scientists from the University of Bristol have shed new light on the sequence of events that led to the creation of the planets Earth and Mars.

Planets grow by a process of accretion - a gradual accumulation of additional material - in which they collisionally combine with their neighbours.

This is often a chaotic process and material gets lost as well as gained.

Massive planetary bodies impacting at several kilometers per second generate substantial heat which, in turn, produces magma oceans and temporary atmospheres of vaporized rock.

This is a snapshot of a computer simulation of two (relatively small) planets colliding with each other. The colours show how the rock of the impacting body (dark grey, in centre of impact area) accretes to the target body (rock; light grey), while some of the rock in the impact area is molten (yellow to white) or vaporized (red).

Credit: Philip J. Carter

Before planets get to approximately the size of Mars, gravitational attraction is too weak to hold onto this inclement silicate atmosphere.

Repeated loss of this vapour envelope during continued collisional growth causes the planet's composition to change substantially.

Dr Remco Hin from the University of Bristol's School of Earth Sciences, led the research which is published today in Nature.

He said: "We have provided evidence that such a sequence of events occurred in the formation of the Earth and Mars, using high precision measurements of their magnesium isotope compositions.

"Magnesium isotope ratios change as a result of silicate vapour loss, which preferentially contains the lighter isotopes. In this way, we estimated that more than 40 per cent of the Earth's mass was lost during its construction.

"This cowboy building job, as one of my co-authors described it, was also responsible for creating the Earth's unique composition."

The research was carried out in an effort to resolve a decades long debate in Earth and planetary sciences about the origin of distinctive, volatile poor compositions of planets.

Did this result from processes that acted in the mixture of gas and dust in the nebula of the earliest solar system or is it consequence of their violent growth?

Researchers analysed samples of the Earth together with meteorites from Mars and the asteroid Vesta, using a new technique to get higher quality (more accurate and more precise) measurements of magnesium isotope ratios than previously obtained.

The main findings are three-fold:
  • Earth, Mars and asteroid Vesta have distinct magnesium isotope ratios from any plausible nebula starting materials
  • The isotopically heavy magnesium isotope compositions of planets identify substantial (~40 per cent) mass loss following repeated episodes of vaporisation during their accretion
  • This slipshod construction process results in other chemical changes during growth that generate the unique chemical characteristics of Earth.

Dr Hin added: "Our work changes our views on how planets attain their physical and chemical characteristics.

"While it was previously known that building planets is a violent process and that the compositions of planets such as Earth are distinct, it was not clear that these features were linked.

"We now show that vapour loss during the high energy collisions of planetary accretion has a profound effect on a planet's composition.

"This process seems common to planet building in general, not just for Earth and Mars, but for all planets in our Solar System and probably beyond, but differences in the collision histories of planets will create a diversity in their compositions."



Contacts and sources:
Shona East
\University of Bristol'

'Magnesium isotope evidence that accretional vapour loss shapes planetary compositions' by R. Hin, C. Coath, P. Carter, F. Nimmo et al in Nature.

Researchers Develop Wearable Solar Thermoelectric Generator

A recent study, led by Professor Kyoung Jin Choi in the School of Materials Science and Engineering at UNIST has introduced a new advanced energy harvesting system, capable of generating electricity by simply being attached to clothes, windows, and outer walls of a building.

This new device is based on a temperature difference between the hot and cold sides. The temperature difference can be increased as high as 20.9 °C, which is much higher than the typical temperature differences of 1.5 to 4.1 °C of wearable thermoelectric generators driven by body heat. The research team expects that their wearable solar thermoelectric generator proposes a promising way to further improve the efficiency by raising the temperature difference.


Credit:  UNIST

Energy harvesting is a diverse field encompassing many technologies, which involve a process that captures small amounts of energy that would otherwise be lost as heat, light, sound, vibration, or movement. A thermoelectric generator (TEGs) refers to a device that converts waste heat energy, such as solar energy, geothermal energy, and body heat into additional electrical power.

There has been a great increase in the study of wearable thermoelectric (TE) generators using the temperature difference between the body heat and surrounding environment. However, one of the main drawbacks of wearable TEG techniques driven by body heat was that such temperature difference is only 1 ~ 4 ℃ and this has hindered further commercialization.

Photograph of the TE ink printed in various shapes with curves and straight lines.

Credit: UNIST

The research team solved this low temperature difference faced by conventional wearable TEGs by introducing a local solar absorber on a PI substrate. The solar absorber is a five-period Ti/MgF2 superlattice, in which the structure and thickness of each layer was designed for optimal absorption of sunlight. This has increased the temperature difference as high as 20.9 °C, which is the highest value of all wearable TEGs reported to date.

“Through this study, we have secured a temperature difference with the ten-fold increase from the conventional wearable solar thermoelectric generators,” says Yeon Soo Jung in the Graduate School of Materials Science and Engineering at UNIST. “Since the output of a TE generator is proportional to the square root of the temperature difference, one can significantly increase the output with the help of this technology.”

In this study, Professor Choi and his team designed a noble wearable solar thermoelectric generator (W-STEG) by integrating flexible BiTe-based TE legs and sub-micron thick solar absorbers on a polymide (PI) substrate. The TE legs were prepared by dispenser printing with an ink consisting of mechanically alloyed BiTe-based powders and an Sb2Te3-based sintering additive dispersed in glycerol. They report that a W-STEG comprising 10 pairs of p-n legs has an open-circuit voltage of 55.15 mV and an output power of 4.44 μW when exposed to sunlight.

“Our new werable STEG is expected to be useful in various applications, such as in self-powered wearable electronic devices,” says Professor Choi. “It will also serve as a catalyst to further improve the future wearable electronic technology market.”

The findings of the research have been published in the August issue of the prestigious journal Nano Energy (IF: 12.34). This work has been supported by the R&D Convergence Program of National Research Council of Science & Technology (NST) of Republic of Korea and the KIST-UNIST partnership program.


Credit: UNIST



Contacts and sources:
  JooHyeon Heo 
Ulsan National Institute of Science and Technology (UNIST)


Citation: Yeon Soo Jung et al., “Wearable solar thermoelectric generator driven by unprecedentedly high temperature difference.” Nano Energy, (2017).

This Material Obscures Supermassive Black Holes

Black holes appear to play a fundamental role in how galaxies evolve throughout their life during a phase in which they are active and consume material from the galaxy itself. During this phase, the galaxy hosts an active galactic nucleus (AGN), and the effect that this nuclear activity produces in the galaxy is known as AGN feedback. This feedback can take place in different forms: the AGN can heat, disrupt, consume and remove the gas available to form new stars, preventing further galaxy growth.

In fact, AGN feedback is now required by simulations of galaxy formation to explain the observations of massive galaxies at cosmological distances. "If AGN feedback is not accounted for in the simulations", explains Cristina Ramos, "the predicted number of massive galaxies when the universe was younger is much higher than those that are observed".

Galaxy NGC 1068 can be seen in close-up in this view from NASA's Hubble Space Telescope. This active black hole -shown as an illustration in the zoomed-in inset- is one of the most obscured known, as it is surrounded by extremely thick clouds of gas and dust that can be characterized using infrared and X-ray observations.
Click to enlarge image
Credit: NASA/JPL-Caltech.


Directly studying the influence of nuclear activity on galaxy evolution is challenging because of the different spatial scales and timescales involved in the two processes. Massive galaxies host extremely compact supermassive black holes of millions or even billions of solar masses in their nuclei. It is estimated that the phases of nuclear activity last for a short period of time, between one and a hundred million years, whereas galaxy evolution processes, such as bulge growth or bar formation last much longer. Thus, in order to study the connection between the AGN and the host galaxy, "we need," explains Claudio Ricci, "to look at the nucleus of galaxies, where the material that links them is found. This material consists mainly of gas and dust, which are normally studied in the infrared and X-ray band."

In this review, Cristina Ramos Almeida, researcher at the Instituto de Astrofísica de Canarias (IAC), and Claudio Ricci, astrophysicist at the Institute of Astronomy of the Universidad Católica de Chile, tried to give a comprehensive view of the current understanding, thanks to infrared and X-ray studies, of nuclear obscuration in AGN. This has greatly improved in the last decade thanks to observing facilities such as CanariCam on the Gran Telescopio CANARIAS (GTC), located at the Roque de los Muchachos Observatory (Garafía, La Palma) and the Very Large Array Interferometer (VLTI) in the infrared range, as well as X-ray satellites like NuSTAR, Swift/BAT and Suzaku.

"We now know", adds Cristina Ramos, "that this nuclear material is more complex and dynamic than we thought a few years ago: it is very compact, formed by gas and dusty clouds orbiting the black hole and its properties depend on the AGN luminosity and accretion rate. Moreover, it is not an isolated structure but appears connected with the galaxy via outflows and inflows of gas, like streams of material flowing as part of a cycle. This gas flow cycle keeps feeding the black hole and regulates the formation of new stars in the galaxy".

Very recently, the Atacama Large Millimeter/submillimeter Array (ALMA) has recently imaged for the first time the nuclear obscuring material in an active galaxy. ALMA operates in the millimiter and sub-millimeter range, and the latter traces the coolest dust and gas surrounding AGN. In the case of the galaxy NGC 1068, ALMA has shown that this material is distributed in a very compact disc-like shape of 7-10 parsecs (pc) diameter and, in addition to the regular rotation of the disk, there are non-circular motions that correspond to high-velocity gas outflowing from the galaxy nucleus. "Over the next decade, the new generation of infrared and X-ray facilities will contribute greatly to our understanding of the structure and physical properties of the nuclear material", concludes Claudio Ricci.


Contacts and sources:  
Elena Mora
Instituto de Astrofísica de Canarias (IAC)

Strange Blades of Ice the Size of Skyscrapers Found on Pluto

NASA’s New Horizons mission revolutionized our knowledge of Pluto when it flew past that distant world in July 2015. Among its many discoveries were images of strange formations resembling giant knife blades of ice, whose origin had remained a mystery.

Now, scientists have turned up a fascinating explanation for this “bladed terrain”: the structures are made almost entirely of methane ice, and likely formed as a specific kind of erosion wore away their surfaces, leaving dramatic crests and sharp divides.

Pluto’s bladed terrain as seen from New Horizons during its July 2015 flyby.

Credits: NASA/JHUAPL/SwRI

These jagged geological ridges are found at the highest altitudes on Pluto’s surface, near its equator, and can soar many hundreds of feet into the sky – as high as a New York City skyscraper. They are one of the most puzzling feature types on Pluto, and it now appears the blades are related to Pluto’s complex climate and geological history.

A team led by New Horizons team member Jeffrey Moore, a research scientist at NASA’s Ames Research Center in California’s Silicon Valley, has determined that formation of the bladed terrain begins with methane freezing out of the atmosphere at extreme altitudes on Pluto, in the same way frost freezes on the ground on Earth, or even in your freezer.

An example of the penitentes from the southern end of the Chajnantor plain in Chile. Though these ice formations only reach a few feet in height, while Pluto’s bladed terrain reaches hundreds of feet, they both have similar sharp ridges.'

Credits: Wikimedia Commons/ESO

“When we realized that bladed terrain consists of tall deposits of methane ice, we asked ourselves why it forms all of these ridges, as opposed to just being big blobs of ice on the ground,” said Moore. “It turns out that Pluto undergoes climate variation and sometimes, when Pluto is a little warmer, the methane ice begins to basically ‘evaporate’ away.”

Scientists use the term “sublimation” for this process where ice transforms directly into gas, skipping over the intermediate liquid form.

Similar structures can be found in high-altitude snowfields along Earth’s equator, though on a very different scale than the blades on Pluto. The terrestrial structures, called penitentes, are snow formations just a few meters high, with striking similarities to the vastly larger bladed terrain on Pluto. Their spiky texture also forms through sublimation.

This erosion of Pluto’s bladed terrain indicates that its climate has undergone changes over long periods of time – on a scale of millions of years – that cause this ongoing geological activity. Early climatic conditions allowed methane to freeze out onto high elevation surfaces, but, as time progressed, these conditions changed, causing the ice to “burn off” into a gas.

The maps above are from New Horizons’ data on the topography (top) and composition (bottom) of Pluto’s surface. In the high-resolution topographical map, the highlighted red region is high in elevation. The map below, showing the composition, indicates the same section also contains methane, color-coded in orange. One can see the orange features spread into the fuzzier, lower-resolution data that covers the rest of the globe, meaning those areas, too, are high in methane, and therefore likely to be high in elevation.

Credits: NASA/JHUAPL/SwRI/LPI

As a result of this discovery, we now know that the surface and air of Pluto are apparently far more dynamic than previously thought. The results have just been published in Icarus, an international journal of planetary science.

Mapping Pluto’s Surface

Identifying the nature of the exotic bladed terrain also brings us a step closer to understanding the global topography of Pluto. The New Horizons spacecraft provided spectacular, high-resolution data about one side of Pluto, called the encounter hemisphere, and observed the other side of Pluto at lower resolution.



Since methane has now been linked to high elevations, researchers can use data that indicates where methane is present around Pluto’s globe to infer which locations are at higher altitudes. This provides an opportunity to map out altitudes of some parts of Pluto’s surface not captured in high resolution, where bladed terrains also appear to exist.

Though the detailed coverage of Pluto’s bladed terrain covers only a small area, NASA researchers and their collaborators have been able to conclude from several types of data that these sharp ridges may be a widespread feature on Pluto’s so-called “far side”, helping to develop a working understanding of Pluto’s global geography, its present and its past.




Contacts and sources:
Author: Frank Tavares, NASA's Ames Research Center
 Darryl Waller, NASA's Ames Research Center

Graphene Pyramid Takes 2-D Material into 3-D

Researchers from Finland and Taiwan have discovered how graphene, a single-atom-thin layer of carbon, can be forged into three-dimensional objects by using laser light. A striking illustration was provided when the researchers fabricated a pyramid with a height of 60 nm, which is about 200 times larger than the thickness of a graphene sheet. The pyramid was so small that it would easily fit on a single strand of hair. The research was supported by the Academy of Finland and the Ministry of Science and Technology of the Republic of China.

Graphene is a close relative to graphite, which consists of millions of layers of graphene and can be found in common pencil tips. After graphene was first isolated in 2004, researchers have learned to routinely produce and handle it. Graphene can be used to make electronic and optoelectronic devices, such as transistors, photodetectors and sensors. In future, we will probably see an increasing number of products containing graphene.

Graphene pyramid: A similar structure was made experimentally by using laser irradiation in a process called "optical forging."
Credit: Academy of Finland

“We call this technique optical forging, since the process resembles forging metals into 3D shapes with a hammer. In our case, a laser beam is the hammer that forges graphene into 3D shapes,” explains Professor Mika Pettersson, who led the experimental team at the Nanoscience Center of the University of Jyväskylä, Finland. “The beauty of the technique is that it’s fast and easy to use; it doesn’t require any additional chemicals or processing. Despite the simplicity of the technique, we were very surprised initially when we observed that the laser beam induced such substantial changes on graphene. It took a while to understand what was happening.”

“At first, we were flabbergasted. The experimental data simply made no sense,” says Dr Pekka Koskinen, who was responsible for the theory. “But gradually, by close interplay between experiments and computer simulations, the actuality of 3D shapes and their formation mechanism started to become clear.”

“When we first examined the irradiated graphene, we were expecting to find traces of chemical species incorporated into the graphene, but we couldn’t find any. After some more careful inspections, we concluded that it must be purely structural defects, rather than chemical doping, that are responsible for such dramatic changes on graphene,” explains Associate Professor Wei Yen Woon from Taiwan, who led the experimental group that carried out X-ray photoelectron spectroscopy at the synchrotron facility.

The novel 3D graphene is stable and it has electronic and optical properties that differ from normal 2D graphene. Optically forged graphene can help in fabricating 3D architectures for graphene-based devices.

The research was carried out at the Nanoscience Center (NSC) of the University of Jyväskylä, the National Central University of Taiwan and the National Synchrotron Radiation Research Center in Taiwan.





Contacts and sources:
Suomen Akatemia (Academy of Finland)

Citation: Andreas Johansson, Pasi Myllyperkiö, Pekka Koskinen, Jukka Aumanen, Juha Tapio Koivistoinen, Hung-Chieh Tsai, Chia-Hao Chen, Lo-Yueh Chang, Vesa-Matti Hiltunen, Jyrki Manninen, Wei-Yen Woon, and Mika Pettersson, Optical Forging of Graphene into Three-Dimensional Shapes. Nano Lett., DOI: 10.1021/acs.nanolett.7b03530 http://pubs.acs.org/doi/10.1021/acs.nanolett.7b03530

Discovery May Revolutionize Dieting

Dieting could be revolutionized, thanks to the ground-breaking discovery by the University of Warwick of the key brain cells which control our appetite.

Professor Nicholas Dale in the School of Life Sciences has identified for the first time that tanycytes – cells found in part of the brain that controls energy levels – detect nutrients in food and tell the brain directly about the food we have eaten.

According to the new research, tanycytes in the brain respond to amino acids found in foods, via the same receptors that sense the flavour of amino acids (“umami” taste), which are found in the taste buds of the tongue.

Two amino acids that react most with tanycytes - and therefore are likely to make you feel fuller – are arginine and lysine.

Tanycyte cells reacting to a puff of the amino acid arginine
Credit: Professor Nicholas Dale/Greta Lazutkaite

These amino acids are found in high concentration in foods such as pork shoulder, beef sirloin steak, chicken, mackerel, plums, apricots, avocadoes, lentils and almonds – so eating those foods will activate the tanycytesand make you feel less hungry quicker.

The researchers made their discovery by adding concentrated amounts of arginine and lysine into brain cells, which were made fluorescent so that any microscopic reactions would be visible. They observed that within thirty seconds, the tanycytes detected and responded to the amino acids, releasing information to the part of the brain that controls appetite and body weight.

They found that signals from amino acids are directly detected by the umami taste receptors by removing or blocking these receptors and observing that the amino acids no longer reacted with tanycytes.

Nicholas Dale, who is Ted Pridgeon Professor of Neuroscience at the University of Warwick, commented:

“Amino acid levels in blood and brain following a meal are a very important signal that imparts the sensation of feeling full. Finding that tanycytes, located at the centre of the brain region that controls body weight, directly sense amino acids has very significant implications for coming up with new ways to help people to control their body weight within healthy bounds.”

This major discovery opens up new possibilities for creating more effective diets – and even future treatments to suppress one’s appetite by directly activating the brain’s tanycytes, bypassing food and the digestive system.

Nearly two thirds of the UK population is overweight or obese. This excess weight elevates the risk of premature death and a range of illnesses, such as cancer, diabetes, cardiovascular disease and stroke, which greatly reduce quality of life. A new understanding of how appetite functions could curb the growing obesity crisis.

The research, ‘Amino Acid Sensing in Hypothalamic Tanycytes via Umami Taste Receptors’, will be published in Molecular Metabolism.

It is funded by the Biotechnology and Biological Sciences Research Council.




Contacts and sources:
Luke Walton
University of Warwick

Citation: ‘Amino Acid Sensing in Hypothalamic Tanycytes via Umami Taste Receptors’, will be published inMolecular Metabolism. Authors: Greta Lazutkaite, Alice Soldà, Kristina Lossow, Wolfgang Meyerhof, Nicholas Dale

Middle Age Fattens You Up If You Do Not Increase Your Physical Activity

The Faculty of Sport and Health Sciences at the University of Jyväskylä has examined how changes in the daily step count are related to changes in the body mass index (BMI).

During the four-year follow-up period, especially women increased their daily step count significantly. Approximately 25% of the research participants increased their step count with more than 2,000 steps, whereas approximately 19% decreased their step count during the follow-up.

The participants were grouped into increasers, decreasers and maintainers according to the total of their steps. The changes in the groups’ BMI were compared to the changes in their step count, and the comparison of the step counts was proportioned to the time the step counter had been kept on.

Image result for middle aged weight gain
Credit: Wikipedia

During the research period, there was growth in both the women’s and the men’s BMI. Almost half of the participants maintained the amount of their daily aerobic steps at the same level and approximately one-fourth increased their daily step count with over 1,000 steps during the research period.

The test participants whose total step count grew by more than 2,000 steps during the follow-up period, maintained their BMI at the same level throughout the years. In contrast, BMI increased for those whose step count stayed at the same level or decreased.

- The trend in physical activity looks good. International studies have shown that physical activity generally decreases along with age, but here it increased, Professor Mirja Hirvensalo states. Even though step counts in general look good, it should be noted that the amount of passive people who take less than 5,000 steps per day did not change significantly during the research period.

The researchers remind everyone about the significance of incidental activity.

- The steps accumulate on many instances during the day, if you give it a chance. One does not necessarily need to go for a walk every day to increase the daily step count. Instead, attention should be paid to choices in everyday life. Does every trip need to be made by car or could some of them be done by foot, or could the stairs be taken instead of the elevator, Postdoctoral Researcher Kasper Salin reminds us.

The Cardiovascular Risk in Young Finns Study has been monitoring over 3,000 Finns regularly from 1980 onwards. One part of the study considers physical activity, and during the last two measurings it was monitored with step counters. During the four-year follow-up period, the step count data and the required background variables were gathered from a total of 1,033 participants. During the follow-up period, the examinees were from 34 to 49 years of age. The recommended daily step count for adults is 10,000 steps.

The research was executed as a part of The Cardiovascular Risk in Young Finns Study led by professor Olli Raitakari. The study is funded by the Ministry of Education and Culture and the Finnish Cultural Foundation.






Contacts and sources:
University of Jyväskylä

Citation:  Salin, K., Hirvensalo, M., Magnussen, CG., Telama, R., Hutri-Kähönen, N., Viikari, J., Raitakari, O., & Tammelin, T. (2017). Changes in daily steps and body mass index and waist to height ratio during four year follow-up in adults: Cardiovascular Risk in Young Finns Study.  http://www.mdpi.com/1660-4601/14/9/1015

Oxygen-Deficient Dwarf Galaxy Hints at Makings of Early Universe

A recently discovered dwarf galaxy in the constellation Lynx may serve well as a proxy for better understanding the developing chemistry of the early universe, according to a research team that includes University of Virginia astronomers.

Their new finding, published in the journal Monthly Notices of the Royal Astronomical Society, shows that the oxygen level in the little galaxy is the lowest yet discovered in any star-forming galaxy, likely resembling early nascent galaxies.

Astronomers know that the first galaxies during their forming stages were chemically simple - primarily made up of hydrogen and helium, elements made in the Big Bang during the first three minutes of the universe's existence. Oxygen came later, as massive stars formed and made heavier and more complex elements by nuclear fusion in their interiors and also in their explosive deaths, ultimately creating a universe of countless oxygen-rich galaxies like our Milky Way.

The faint Lynx constellation requires the eye of a lynx to see.
The faint Lynx constellation requires the eye of a lynx to see.
Credit: University of Virginia

The earliest oxygen-deficient galaxies are so far away and so faint as to be nearly undetectable, but relatively close-by star-forming dwarf galaxies, with very little oxygen like early galaxies, may be easier to detect and offer the same clues. Unfortunately, these nearby tiny galaxies with little oxygen, which currently produce many massive blue stars, are very rare. But if detected, they can offer valuable insights to how the first galaxies formed some 13 billion years ago, and therefore to the evolution of the early universe.

The star-forming dwarf galaxy in the new study was found during an ongoing, large-scale inventory of the heavens, the Sloan Digital Sky Survey, which revealed it as a possible point of interest. Astronomers then targeted it for further scrutiny using the powerful Large Binocular Telescope in Arizona. Data from the that telescope revealed that the tiny star-forming galaxy, dubbed J0811+4730, is a record-breaker: It has 9 percent less oxygen - a sign of simplicity - than any other so far discovered.

"We found that a considerable fraction of the stellar mass of the galaxy was formed only a few million years ago, making this one of the best counterparts we've found of primordial galaxies," said UVA astronomer Trinh Thuan, one of the study's authors. "Because of its extremely low oxygen level, this galaxy serves as an accessible proxy for star-forming galaxies that came together within one to two billion years after the Big Bang, the early period of our nearly 14 billion-year-old universe."

The dwarf galaxy also is of interest because it provides clues to how the early simple universe became re-ionized by early star formation, moving it from the so-called cosmic Dark Ages of neutral gases to the development of the complexly structured universe now in existence, where the gas between galaxies is ionized.

Thuan said the data indicates that the tiny galaxy is rapidly producing new stars at a quarter of the rate of the Milky Way - yet its mass in stars is 30,000 times smaller. Eighty percent of its stellar mass has formed in just the past few million years, marking this as an exceptionally young galaxy, producing copious amounts of ionizing radiation.

Trinh's colleagues on the study are astronomers Yuri Izotov and Natalia Guseva of the Ukrainian National Academy of Sciences, and graduate student Sandy Liss of UVA.



Contacts and sources: 
Fariss Samarrai
University of Virginia 

Coconut-Cracking Giant Rat Discovered in Solomon Islands

Remember the movie The Princess Bride, when the characters debate the existence of R.O.U.S.es (Rodents of Unusual Size), only to be beset by enormous rats? That's kind of what happened here.

Mammalogist Tyrone Lavery heard rumors of a giant, possum-like rat that lived in trees and cracked open coconuts with its teeth on his first trip to the Solomon Islands in 2010. After years of searching and a race against deforestation destroying the rat's would-be home, Lavery, along with John Vendi and Hikuna Judge, finally found it.

"The new species, Uromys vika, is pretty spectacular -- it's a big, giant rat," said Lavery, a post-doctoral researcher at The Field Museum in Chicago and the lead author of the Journal of Mammalogy paper announcing the rat's discovery. "It's the first rat discovered in 80 years from Solomons, and it's not like people haven't been trying -- it was just so hard to find."

This is an illustration of the new species, Uromys vika.

Credit: Velizar Simeonovski, The Field Museum

The Solomon Islands, a country made up of a series of islands a thousand miles northwest of Australia, are biologically isolated. Over half of the mammals on the Solomon Islands are found nowhere else on Earth, making it an attractive location for scientists like Lavery.

"When I first met with the people from Vangunu Island in the Solomons, they told me about a rat native to the island that they called vika, which lived in the trees," says Lavery. "I was excited because I had just started my Ph.D., and I'd read a lot of books about people who go on adventures and discover new species."

But years of searching didn't turn up any of the giant rats. "I started to question if it really was a separate species, or if people were just calling regular black rats 'vika,'"said Lavery. Part of what made the search so difficult was the rat's tree-dwelling lifestyle. "If you're looking for something that lives on the ground, you're only looking in two dimensions, left to right and forward and backward. If you're looking for something that can live in 30-foot-tall trees, then there's a whole new dimension that you need to search," explains Lavery.

This is a skull of new species Uromys vika.
Courtesy of Tyrone Lavery, The Field Museum

Finally, one of the rats was discovered scurrying out of a felled tree. "As soon as I examined the specimen, I knew it was something different," says Lavery. "There are only eight known species of native rat from the Solomon Islands, and looking at the features on its skull, I could rule out a bunch of species right away." After comparing the specimen to similar species in museum collections and checking the new rat's DNA against the DNA of its relatives, Lavery confirmed that the giant rat was a new species, which he named Uromys vika in honor of the local name for the rat. "This project really shows the importance of collaborations with local people," says Lavery, who learned about the rat through talking with Vangunu locals and confirmed with them that the new rat matched the "vika" they knew.

Vika are a lot bigger than the black rats that spread throughout the world with European colonists -- the rats you'll see in American alleys weigh around 200 grams (0.44 pounds), Solomon Islands rats can be more than four times that size, weighing up to a kilogram (2.2 pounds). And from the tip of its nose to the tip of its tail, U. vika is about a foot and a half long. And while they haven't yet been observed cracking open coconuts, they do have a penchant for chewing circular holes into nuts to get at the meat.

The rat's giant size and possum-like tree-dwelling lifestyle can be traced back to its island home. Islands are full of animals found nowhere else on earth that evolved in isolation from the rest of the world. "Vika's ancestors probably rafted to the island on vegetation, and once they got there, they evolved into this wonderfully new species, nothing like what they came from on the mainland," explains Lavery.

These are nuts bearing the characteristic tooth-marks of Uromys vika.

Courtesy of Tyrone Lavery, The Field Museum.

While the rat has only just been discovered, it will quickly be designated as Critically Endangered, due to its rarity and the threat posed by logging to its rainforest habitat. "It's getting to the stage for this rat that, if we hadn't discovered it now, it might never have gotten discovered. The area where it was found is one of the only places left with forest that hasn't been logged," says Lavery. 

"It's really urgent for us to be able to document this rat and find additional support for the Zaira Conservation Area on Vangunu where the rat lives."Lavery also emphasized the necessity of preserving the rats, not just for ecological reasons, but for the role they play in the lives of Vangunu's people. "These animals are important parts of culture across Solomon Islands -- people have songs about them, and even children's rhymes like our 'This little piggy went to market.'"The discovery marks an important moment in the biological study of the Solomon Islands, especially since vika is so uncommon and close to extinction. 

"Finding a new mammal is really rare -- there are probably just a few dozen new mammals discovered every year," says Lavery. "Vika was so hard to find, and the fact that I was able to persevere is something that I'm proud of."

This study was completed by scientists at The Field Museum and the Zaira Resource Management Area.



Contacts and sources:
Kate Golembiewski
The Field Museum

The Strange Structures of the Saturn Nebula

The spectacular planetary nebula NGC 7009, or the Saturn Nebula, emerges from the darkness like a series of oddly-shaped bubbles, lit up in glorious pinks and blues. This colourful image was captured by the powerful MUSE instrument on ESO’s Very Large Telescope (VLT), as part of a study which mapped the dust inside a planetary nebula for the first time. The map — which reveals a wealth of intricate structures in the dust, including shells, a halo and a curious wave-like feature — will help astronomers understand how planetary nebulae develop their strange shapes and symmetries.

The Saturn Nebula is located approximately 5000 light years away in the constellation of Aquarius (The Water Bearer). Its name derives from its odd shape, which resembles everyone’s favourite ringed planet seen edge-on.

The spectacular planetary nebula NGC 7009, or the Saturn Nebula, emerges from the darkness like a series of oddly-shaped bubbles, lit up in glorious pinks and blues. This colourful image was captured by the powerful MUSE instrument on ESO’s Very Large Telescope (VLT), as part of a study which mapped the dust inside a planetary nebula for the first time. This annotated version labels the features of this curious object.
Annotated image showing features in the Saturn Nebula
Credit: ESO/J. Walsh

But in fact, planetary nebulae have nothing to do with planets. The Saturn Nebula was originally a low-mass star, which expanded into a red giant at the end of its life and began to shed its outer layers. This material was blown out by strong stellar winds and energized by ultraviolet radiation from the hot stellar core left behind, creating a circumstellar nebula of dust and brightly-colored hot gas. At the heart of the Saturn Nebula lies the doomed star, visible in this image, which is in the process of becoming a white dwarf [1].

The spectacular planetary nebula NGC 7009, or the Saturn Nebula, emerges from the darkness like a series of oddly-shaped bubbles, lit up in glorious pinks and blues. This colourful image was captured by the powerful MUSE instrument on ESO’s Very Large Telescope (VLT), as part of a study which mapped the dust inside a planetary nebula for the first time.
Credit: ESO

In order to better understand how planetary nebulae are moulded into such odd shapes, an international team of astronomers led by Jeremy Walsh from ESO used the Multi Unit Spectroscopic Explorer (MUSE) to peer inside the dusty veils of the Saturn Nebula. MUSE is an instrument installed on one of the four Unit Telescopes of the Very Large Telescopeat ESO’s Paranal Observatory in Chile. It is so powerful because it doesn’t just create an image, but also gathers information about the spectrum — or range of colors — of the light from the object at each point in the image.

This view shows how the MUSE instrument on ESO’s Very Large Telescope gives a three-dimensional depiction of the Saturn Nebula. For each part of this spectacular nebula, the light has been split up into its component colours — revealing in detail the chemical and physical properties of each pixel.  During the subsequent analysis the astronomer can move through the data and study different views of the object at different wavelengths, just like tuning a television to different channels at different frequencies.
Three-dimensional MUSE view of the Saturn Nebula
Credit: ESO/J. Walsh


The team used MUSE to produce the first detailed optical maps of the gas and dust distributed throughout a planetary nebula [2]. The resulting image of the Saturn Nebula reveals many intricate structures, including an elliptical inner shell, an outer shell, and a halo. It also shows two previously imaged streams extending from either end of the nebula’s long axis, ending in bright ansae (Latin for “handles”).

This visualisation shows the three-dimensional MUSE data on the bright planetary nebula NGC 7009, also known as the Saturn Nebula. Each slice is presented in sequence shows a view of the object at a different wavelength. At certain wavelengths, corresponding to emission lines in the spectrum from hydrogen, oxygen and helium, the object glows brightly and strange structures are revealed. At the end these emission line views are combined to make a colour picture of the object.

Credit: ESO/J. Walsh/L.Calçada

Intriguingly, the team also found a wave-like feature in the dust, which is not yet fully understood. Dust is distributed throughout the nebula, but there is a significant drop in the amount of dust at the rim of the inner shell, where it seems that it is being destroyed. There are several potential mechanisms for this destruction. The inner shell is essentially an expanding shock wave, so it may be smashing into the dust grains and obliterating them, or producing an extra heating effect that evaporates the dust.

Mapping the gas and dust structures within planetary nebulae will aid in understanding their role in the lives and deaths of low mass stars, and it will also help astronomers understand how planetary nebulae acquire their strange and complex shapes.

This zoom sequence starts from a very broad view of the sky and heads towards the constellation of Aquarius (The Water Bearer). After a while we see a bright tiny blue disc, which eventually turns into the spectacular planetary nebula NGC 7009, known as the Saturn Nebula because of its distinctive shape. The final image is from new data taken with the MUSE instrument on ESO's Very Large Telescope in Chile.

Credit: ESO/Digitized Sky Survey 2/N. Risinger (skysurvey.org). Music: Astral Electronic

But MUSE’s capabilities extend far beyond planetary nebulae. This sensitive instrument can also study the formation of stars and galaxies in the early Universe, as well as map the dark matter distribution in galaxy clusters in the nearby Universe. MUSE has also created the first 3D map of the Pillars of Creation in the Eagle Nebula (eso1518) and imaged a spectacular cosmic crash in a nearby galaxy (eso1437).
Notes

[1] Planetary nebulae are generally short-lived; the Saturn Nebula will last only a few tens of thousands of years before expanding and cooling to such an extent that it becomes invisible to us. The central star will then fade as it becomes a hot white dwarf.

[2] The NASA/ESA Hubble Space Telescope has previously provided a spectacular image of the Saturn Nebula — but, unlike MUSE, it cannot reveal the spectrum at each point over the whole nebula.



Contacts and sources:
Richard Hook
ESO