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Saturday, February 6, 2016

Man-Made Underwater Sound May Have Wider Ecosystem Effects Than Previously Thought

Underwater sound linked to human activity could alter the behavior of seabed creatures that play a vital role in marine ecosystems, according to new research from the University of Southampton.

The study, reported in the journal Scientific Reports published by Nature, found that exposure to sounds that resemble shipping traffic and offshore construction activities results in behavioral responses in certain invertebrate species that live in the marine sediment.

These species make a crucial contribution to the seabed ecosystem as their burrowing and bioirrigation activities (how much the organism moves water in and out of the sediment by its actions) are crucial in nutrient recycling and carbon storage.

Image shows a langoustine (Nephrops norvegicus)
Credit: University of Southampton

The study showed that some man-made sounds can cause certain species to reduce irrigation and sediment turnover. Such reductions can lead to the formation of compacted sediments that suffer reduced oxygen, potentially becoming anoxic (depleted of dissolved oxygen and a more severe condition of hypoxia), which may have an impact on seabed productivity, sediment biodiversity and also fisheries production.

Lead author Martin Solan, Professor in Marine Ecology, said: "Coastal and shelf environments support high levels of biodiversity that are vital in mediating ecosystem processes, but they are also subject to noise associated with increasing levels of offshore human activity. Previous work has almost exclusively focussed on direct physiological or behavioural responses in marine mammals and fish, and has not previously addressed the indirect impacts of sound on ecosystem properties.

"Our study provides evidence that exposing coastal environments to anthropogenic sound fields is likely to have much wider ecosystem consequences than are presently understood."

The Southampton researchers exposed three species - the langoustine (Nephrops norvegicus), a slim, orange-pink lobster which grows up to 25 cm long, the Manila clam (Ruditapes philippinarum) and the brittlestar Amphiura filfiformis - to two different types of underwater sound fields: continuous broadband noise (CBN) that mimics shipping traffic and intermittent broadband noise (IBN) reflecting marine construction activity.

The sounds were reproduced in controlled test tanks and experiments were run on one species at a time. For CBN, a recording (one minute duration, continuously looped) of a ship made in the English Channel at a distance of around 100 metres was used'. For IBN, a recording (two minutes duration, continuously looped) of a wind farm in the North Sea at a distance of about 60 metres was used.

The results showed that the sounds could alter the way these species behaved when interacting with their environments.

With the langoustine, which disturbs the sediment to create burrows in which it lives, the researchers saw a reduction in the depth of sediment redistribution (how much of the surface sediment was overturned into the deeper layers) with exposure to IBN or CBN. Under CBN and IBN there was evidence that bioirrigation increased.

The Manila clam, a commercial fishery species in Europe that lives in the sediment and connects to the overlying water through a retractable siphon, reduced its surface activity under CBN, which affected the surface roughness of the sediment. Bioirrigation, which is strongly influenced by clam behaviour and the activity of the siphon, was markedly reduced by CBN and slightly reduced under IBN.

However, the sound fields had little impact on the brittlestar.

Co-author Dr Chris Hauton, Associate Professor in Invertebrate Ecophysiology and Immune Function, said: "I think these findings raise the prospect that anthropogenic sounds in the marine environment are impacting marine invertebrate species in ways that have not been previously anticipated. The potential effects of anthropogenic noise on ecosystem function, mediated through changes in organism behaviour merits further study as, in the long term, it may identify impacts to the productivity of seabed systems that have, to date, not really been constrained."

Tim Leighton, Professor of Ultrasonics and Underwater Acoustics and study co-author, added: "There has been much discussion over the last decade of the extent to which whales, dolphins and fish stocks, might be disturbed by the sounds from shipping, windfarms and their construction, seismic exploration etc. However, one set of ocean denizens has until now been ignored, and unlike these other classes, they cannot easily move away from loud man-made sound sources. These are the bottom feeders, such as crabs, shellfish and invertebrates similar to the ones in our study, which are crucial to healthy and commercially successful oceans because they form the bottom of the food chain."

Contacts and sources:

Land Degradation Affects 3.2 Billion People

Land degradation is on the rise to a dramatic extent, affecting around 3.2 billion people worldwide. Every dollar invested in saving land and soils today will save us five dollars in the future. Professor Klaus Töpfer, former Executive Director of UNEP; Professor Joachim von Braun, Director of the Center for Development Research, University of Bonn (ZEF); and Dr. Stefan Schmitz, German Federal Ministry for Economic Cooperation and Development (BMZ) will present the latest research insights on this issue.

Credit:  United Nations

The press conference will be held on Thursday, February 11, 2016, 10:00 AM – 11:00 AM in the Berlin-Brandenburgische Akademie der Wissenschaften, Jägerstraße 22/23, in 10117 Berlin.

Land and soil are the basis of life on Earth. Nevertheless, insufficient effort has been made so far to ensure sustainable land use and the protection of soils. This is the conclusion that a team of international scientists has drawn from studies conducted in 12 world regions and countries, including India, Argentina, Central Asia, Russia and a large number of African countries. 

The findings, partly based on remote-sensing satellite data, are alarming: Globally, 33 percent of grasslands, 25 percent of croplands and 23 percent of forests have experienced degradation over the past three decades. Around 30 percent of the global land area, home to around 3.2 billion people, is affected by significant soil degradation. The global costs amount to around 300 billion Euros per annum. The global assessment concludes: Every US Dollar invested today will save us five US Dollars in the future.

“Sustainable land management contributes to achieving several of the Sustainable Development Goals (SDGs), such as land degradation neutrality and an ambitious climate and biodiversity agenda. This fact was highlighted in the series of Global Soil Week events held in Berlin in recent years”, explains Professor Klaus Töpfer, former Executive Director the United Nations Environment Programme (UNEP).

“Soil is the most neglected natural resource”, states Professor Joachim von Braun, Director of the Center for Development Research (ZEF) and co-editor of the book “Economics of Land Degradation and Improvement – A Global Assessment for Sustainable Development”, which was published by Springer recently. “Yet, investments in land and soil are crucial for food supply, climate and human security”, von Braun adds.

According to von Braun: “The international scientists involved in these country case studies basically all reach the same conclusion; namely, that if we invest in rescuing global land and soil now, the cost will be much lower than if we wait longer. This applies both to industrialized and developing countries alike”.

The high levels of land degradation in croplands and grazing lands in developing countries, especially in sub-Saharan Africa, pose a serious problem too and may lead to migration. Often, there is a lack of advisory services and knowledge transfer for farmers, for example about integrated soil fertility management. Poor access to markets is another obstacle as well as weak security of land tenure.

The latter means that farmers are not motivated to practice sustainable land use methods. “In order to change this, the German government has been substantially involved in sustainable land use initiatives”, emphasizes Stefan Schmitz of the German Federal Ministry for Economic Cooperation and Development (BMZ), who is the coordinator of the BMZ special initiative ‘One World no Hunger’. “Combating land degradation is one of the most important elements in our fight against hunger”, he adds.

Contacts and sources:
Universität Bonn

Global Sea Levels Could Rise 3 Meters Due to Melting Antarctic Ice

Loss of ice in Antarctica caused by a warming ocean could raise global sea levels by three meters, research by Northumbria and Edinburgh universities suggests.

Scientists carrying out fieldwork in the region have assessed the landscape to determine how the West Antarctic ice sheet might respond to increasing global temperatures.

In the first study of its kind, researchers were able to gauge how levels of ice covering the land have changed over hundreds of thousands of years. They did so by studying peaks protruding through ice in the Ellsworth Mountains, on the Atlantic flank of Antarctica.

Credit: Northumbria University

The team assessed changes on slopes at various heights on the mountainside, which indicate levels previously reached by the ice sheet. They also mapped the distribution of boulders on the mountainside, which were deposited by melting glaciers. Chemical technology – known as exposure dating – showed how long rocks had been exposed to the atmosphere, and their age.

Their results indicate that during previous warm periods, a substantial amount of ice would have been lost from the West Antarctic ice sheet by ocean melting, but it would not have melted entirely. This suggests that ice would have been lost from areas below sea level, but not on upland areas. The research shows that parts of the West Antarctic ice sheet have existed continuously for at least 1.4 million years.

The study, published in Nature Communications, was carried out by researchers at Northumbria University and the University of Edinburgh, alongside the Scottish Universities Environmental Research Centre. It was supported by the Natural Environment Research Council and the British Antarctic Survey.

Credit: Northumbria University

Professor John Woodward, Northumbria’s Associate Dean (Research and Innovation) in Engineering and Environment, co-led the study.

He said: “It is possible that the ice sheet has passed the point of no return and, if so, the big question is how much will go and how much will sea levels rise.”

Dr Andrew Hein, of the University of Edinburgh’s School of GeoSciences, joint leader of the study, added: “Our findings narrow the margin of uncertainty around the likely impact of the West Antarctic Ice Sheet on sea level rise. This remains a troubling forecast since all signs suggest the ice from West Antarctica could disappear relatively quickly.”

Cold and paleo environments are one of Northumbria’s research specialisms in the Department of Geography. Research involves field based projects in cold regions across the globe, including Antarctica, a range of high Arctic European and Canadian sites, New Zealand, the Alps, Alaska and Chile.

The group applies novel techniques to field data collection, including ground-penetrating radar, new borehole radar technologies, seismics, NIR camera techniques, meteorological monitoring technologies, the use of unmanned aerial vehicles (UAV) and terrestrial laser scanning (TLS), to address fundamental questions in Earth Systems Science. Cutting-edge physical and numerical modelling, remote sensing and laboratory techniques for palaeo-environmental work are also applied.

Contacts and sources:
Northumbria University

Turbulent Times: When Stars Approach

HITS astrophysicists are using new methods to simulate the common-envelope phase of binary stars and discovering dynamic irregularities that may help to explain how supernovae evolve.

When we look at the night sky, we see stars as tiny points of light eking out a solitary existence at immense distances from Earth. But appearances are deceptive. More than half the stars we know of have a companion, a second nearby star that can have a major impact on their primary companions. 

The interplay within these so-called binary star systems is particularly intensive when the two stars involved are going through a phase in which they are surrounded by a common envelope consisting of hydrogen and helium. Compared to the overall time taken by stars to evolve, this phase is extremely short, so astronomers have great difficulty observing and hence understanding it. This is where theoretical models with highly compute-intensive simulations come in. Research into this phenomenon is relevant understanding a number of stellar events such as supernovae.

The simulation video visualizes the evolution of the density during a time span of 105 days. As the core of the red giant and the companion draw closer together, the gravity between them releases energy that passes into the common envelope. The turbulent instabilities that occur during this phase become clearly evident. (\
Video: Sebastian Ohlmann / HITS

Using new methods, astrophysicists Sebastian Ohlmann, Friedrich Roepke, Ruediger Pakmor, and Volker Springel of the Heidelberg Institute for Theoretical Studies (HITS) have now made a step forward in modeling this phenomenon. As they report in The Astrophysical Journal Letters, the scientists have successfully used simulations to discover dynamic irregularities that occur during the common-envelope phase and are crucial for the subsequent existence of binary star systems. These so-called instabilities change the flow of matter inside the envelope, thus influencing the stars' distance from one another and determining, for example, whether a supernova will ensue and, if so, what kind it will be.

This image shows a slice through the three-dimensional simulation volume after 105 days in the common envelope. In the orbital plane (figure 1), the companion star and the red giant core are circling around each other. 
Image: Sebastian Ohlmann / HITS

The article is the fruit of collaboration between two HITS research groups, the Physics of Stellar Objects (PSO) group and the Theoretical Astrophysics group (TAP). Prof. Volker Springel's Arepo code for hydrodynamic simulations was used and adapted for the modeling. It solves the equations on a moving mesh that follows the mass flow, and thus enhances the accuracy of the model.

Two stars, one envelope

More than half the stars we know of have evolved in binary star systems. The energy for their luminosity comes from the nuclear fusion of hydrogen at the core of the stars. As soon as the hydrogen fueling the nuclear fusion is exhausted in the heavier of the two stars, the star core shrinks. At the same time, a highly extended stellar envelope evolves, consisting of hydrogen and helium. The star becomes a red giant.

As the envelope of the red giant goes on expanding, the companion star draws the envelope to itself via gravity, and part of the envelope flows towards it. In the course of this process the two stars come closer to one another. Finally, the companion star may fall into the envelope of the red giant and both stars are then surrounded by a common envelope. 

As the core of the red giant and the companion draw closer together, the gravity between them releases energy that passes into the common envelope. As a result, the envelope is ejected and mixes with interstellar matter in the galaxy, leaving behind it a close binary star system consisting of the core of the giant and the companion star.

The path to stellar explosion

Sebastian Ohlmann of the PSO group explains why this common-envelope phase is important for our understanding of the way various star systems evolve: "Depending on what the system of the common envelope looks like initially, very different phenomena may ensue in the aftermath, such as thermonuclear supernovae." 

Figure 2 shows a plane perpendicular to the orbital plane.

Image: Sebastian Ohlmann / HITS

Ohlmann and colleagues are investigating the run-up to these stellar explosions, which are among the most luminous events in the universe and can light up a whole galaxy. But modeling the systems that can lead to such explosions is bedeviled by major uncertainty in the description of the common-envelope phase. 

One of the reasons for this is that the core of the giant is anything between a thousand and ten thousand times smaller than the envelope, so that spatial and temporal scale differences complicate the modeling process and make approximations necessary. The methodically innovative simulations performed by the Heidelberg scientists are a first step towards a better understanding of this phase.

Contacts and sources:
Dr. Peter Saueressig
HITS Heidelberg Institute for Theoretical Studies

Citation: Ohlmann, S. T., Roepke, F. K., Pakmor, R., & Springel, V. (2016): Hydrodynamic moving-mesh simulations of the common envelope phase in binary stellar systems, The Astrophysical Journal Letters, 816, L9, DOI: 10.3847/2041-8205/816/1/L9
Astrophysics Data System: http://adsabs.harvard.edu/abs/2016ApJ...816L...9O

'Cannibalism' Between Stars: New Research Shows the Turbulent Past of Our Sun

Stars are born inside a rotating cloud of interstellar gas and dust, which contracts to stellar densities thanks to its own gravity. Before finding itself on the star, however, most of the cloud lands onto a circumstellar disk forming around the star owing to conservation of angular momentum. The manner in which the material is transported through the disk onto the star, causing the star to grow in mass, has recently become a major research topic in astrophysics.

This is a Simulation of a gravitationally unstable circumstellar disk by means of hydrodynamic calculations. Protoplanetary 'embryo' form in the disc thanks to gravitational fragmentation. The three small pictures show the successive 'disappearance' of the lump by the star.

Credit: Copyright: Eduard Vorobyov, Universität Wien

It turned out that stars may not accumulate their final mass steadily, as was previously thought, but in a series of violent events manifesting themselves as sharp stellar brightening. The young FU Orionis star in the constellation of Orion is the prototype example, which showed an increase in brightness by a factor of 250 over a time period of just one year, staying in this high-luminosity state now for almost a century.

One possible mechanism that can explain these brightening events was put forward 10 years ago by Eduard Vorobyov, now working at the Astrophysical Department of the Vienna University, in collaboration with Shantanu Basu from the University of Western Ontario, Canada.

According to their theory, stellar brightening can be caused by fragmentation due to gravitational instabilities in massive gaseous disks surrounding young stars, followed by migration of dense gaseous clumps onto the star. Like the process of throwing logs into a fireplace, these episodes of clump consumption release excess energy which causes the young star to brighten by a factor of hundreds to thousands. During each episode, the star is consuming the equivalent of one Earth mass every ten days. After this, it may take another several thousand years before another event occurs.

Eduard Vorobyov describes the process of clump formation in circumstellar disks followed by their migration onto the star as "cannibalism on astronomical scales". These clumps could have matured into giant planets such as Jupiter, but instead they were swallowed by the parental star. This invokes an interesting analogy with the Greek mythology, wherein Cronus, the leader of the first generation of Titans, ate up his newborn children (though failing to gobble up Zeus, who finally brought death upon his father).

These are the polarized intensities of four selected FU Orionis objects observed with the 8.2-meter Subaru Telescope. Significant asymmetries, such as elbows, arms and broad trends -- typical of gravitationally unstable disks -- are indicated by arrows.

Credit:  Copyright: Eduard Vorobyov, Universität Wien

With the advent of advanced observational instruments, such as SUBARU 8.2 meter optical-infrared telescope installed in Mauna Kea (Hawaii), it has become possible for the first time to test the model predictions. Using high-resolution, adaptive optics observations in the polarized light, an international group of astronomers led by Hauyu Liu from European Space Observatory (Garching, Germany) has verified the presence of the key features associated with the disk fragmentation model -- large-scale arms and arcs surrounding four young stars undergoing luminous outbursts, including the prototype FU Orionis star itself. The results of this study were accepted for publication in Science Advances - a peer-review, open-access journal belonging to the Science publishing group.

"This is a major step towards our understanding of how stars and planets form and evolve", says Vorobyov, "If we can prove that most stars undergo such episodes of brightening caused by disk gravitational instability, this would mean that our own Sun might have experienced several such episodes, implying that the giant planets of the Solar system may in fact be lucky survivors of the Sun's tempestuous past".

Contacts and sources: 
Eduard Vorobyov
Vienna University

Citation:  Hauyu Baobab Liu, Michihiro Takami, Tomoyuki Kudo, Jun Hashimoto, Ruobing Dong, Eduard I. Vorobyov, Tae-Soo Pyo, Misato Fukagawa, Motohide Tamura, Thomas Henning, Michael M. Dunham, Jennifer Karr, Nobuhiko Kusakabe, Toru Tsuribe: "Circumstellar Disks of the Most Vigorously Accreting Young Stars", published online February 5, 2016. Publication in Science Advances  

Thursday, February 4, 2016

Changing Weather Patterns Making Southwest Drier; Less Rain The New Normal

The weather patterns that typically bring moisture to the southwestern United States are becoming more rare, an indication that the region is sliding into the drier climate state predicted by global models, according to a new study.

“A normal year in the Southwest is now drier than it once was,” said Andreas Prein, a postdoctoral researcher at the National Center for Atmospheric Research (NCAR) who led the study. “If you have a drought nowadays, it will be more severe because our base state is drier.”

Weather systems that typically bring moisture to the southwestern United States are forming less often, resulting in a drier climate across the region. This map depicts the portion of overall changes in precipitation across the United States that can be attributed to these changes in weather system frequency. The gray dots represent areas where the results are statistically significant.

Credit: Andreas Prein, NCAR.

Climate models generally agree that human-caused climate change will push the southwestern United States to become drier. And in recent years, the region has been stricken by drought. But linking model predictions to changes on the ground is challenging.

In the new study—published online today in the journal Geophysical Research Letters, a publication of the American Geophysical Union—NCAR researchers grapple with the root cause of current drying in the Southwest to better understand how it might be connected to a warming climate.

Subtle shift yields dramatic impact

For the study, the researchers analyzed 35 years of data to identify common weather patterns—arrangements of high and low pressure systems that determine where it’s likely to be sunny and clear or cloudy and wet, among other things. They identified a dozen patterns that are typical for the weather activity in the contiguous United States and then looked to see whether those patterns were becoming more or less frequent.

“The weather types that are becoming more rare are the ones that bring a lot of rain to the southwestern United States,” Prein said. “Because only a few weather patterns bring precipitation to the Southwest, those changes have a dramatic impact.”

The Southwest is especially vulnerable to any additional drying. The region, already the most arid in the country, is home to a quickly growing population that is putting tremendous stress on its limited water resources.

“Prolonged drought has many adverse effects,” said Anjuli Bamzai, program director in the National Science Foundation’s Division of Atmospheric and Geospace Sciences, which funded the research, “so understanding regional precipitation trends is vital for the well-being of society. These researchers demonstrate that subtle shifts in large-scale weather patterns over the past three decades or so have been the dominant factor in precipitation trends in the southwestern United States.”

The study also found an opposite, though smaller, effect in the Northeast, where some of the weather patterns that typically bring moisture to the region are increasing.

“Understanding how changing weather pattern frequencies may impact total precipitation across the U.S. is particularly relevant to water resource managers as they contend with issues such as droughts and floods, and plan future infrastructure to store and disperse water,” said NCAR scientist Mari Tye, a co-author of the study.

The climate connection

The three patterns that tend to bring the most wet weather to the Southwest all involve low pressure centered in the North Pacific just off the coast of Washington, typically during the winter. Between 1979 and 2014, such low-pressure systems formed less and less often. The associated persistent high pressure in that area over recent years is a main driver of the devastating California drought.

This shift toward higher pressure in the North Pacific is consistent with climate model runs, which predict that a belt of higher average pressure that now sits closer to the equator will move north. This high-pressure belt is created as air that rises over the equator moves poleward and then descends back toward the surface. The sinking air causes generally drier conditions over the region and inhibits the development of rain-producing systems.

Many of the world’s deserts, including the Sahara, are found in such regions of sinking air, which typically lie around 30 degrees latitude on either side of the equator. Climate models project that these zones will move further poleward. The result is a generally drier Southwest.

While climate change is a plausible explanation for the change in frequency, the authors caution that the study does not prove a connection. To examine this potential connection further, they are studying climate model data for evidence of similar changes in future weather pattern frequencies.

“As temperatures increase, the ground becomes drier and the transition into drought happens more rapidly,” said NCAR scientist Greg Holland, a co-author of the study. “In the Southwest the decreased frequency of rainfall events has further extended the period and intensity of these droughts.”

Contacts and sources: 
Nanci Bompey
The American Geophysical Union

Bright Sparks Shed New Light On the Dark Matter Riddle

The origin of matter in the universe has puzzled physicists for generations. Today, we know that matter only accounts for 5% of our universe; another 25% is constituted of dark matter. And the remaining 70% is made up of dark energy. Dark matter itself represents an unsolved riddle.

Physicists believe that such dark matter is composed of (as yet undefined) elementary particles that stick together thanks to gravitational force. In a study recently published in EPJ C, scientists from the CRESST-II research project use the so-called phonon-light technique to detect dark matter. They are the first to use a detection probe that operates with such a low trigger threshold, which yields suitable sensitivity levels to uncover the as-yet elusive particles responsible for dark matter.

Until quite recently, the so-called WIMP - Weakly Interacting Massive Particle - was the preferred candidate for a new elementary particle to explain dark matter. However, the asymmetric dark matter particle models have attracted more and more interest in the past few years. The experimental detection is no different from the scattering of two billiard balls, as the particle scatters on an atomic nucleus. The detection method is based on the fact that the scattering would heat up a calcium tungstate (CaWO4) crystal.

The challenge: the lighter the dark matter particle is, the smaller the energy deposited in the crystal is. Currently, no other direct dark matter search method has a threshold for nuclear recoils as low as 0.3 kiloelectronVolt (keV). As such, the CRESST-II team are the first to ever probe dark matter particle masses at such low mass scale (below one GeV/c^2-as far as 0.5GeV/c^2). The next-generation CRESST-III detector is currently being upgraded and promises to reach thresholds of 100 electronVolts (eV), following successful tests of prototypes.

Contacts and sources:
Sabine Lehr

Good or Bad? Deodorants and Antiperspirants Alter the Microbial Ecosystem on Your Skin

Wearing antiperspirant or deodorant doesn’t just affect your social life, it substantially changes the microbial life that lives on you. New research finds that antiperspirant and deodorant can significantly influence both the type and quantity of bacterial life found in the human armpit’s “microbiome.” The work was done by researchers at North Carolina State University, the North Carolina Museum of Natural Sciences, North Carolina Central University, Rutgers University and Duke University.

“We wanted to understand what effect antiperspirant and deodorant have on the microbial life that lives on our bodies, and how our daily habits influence the life that lives on us,” says Julie Horvath, head of the genomics and microbiology research laboratory at the NC Museum of Natural Sciences, an associate research professor at NC Central, and corresponding author of a paper describing the work published in the journal PeerJ. “Ultimately, we want to know if any changes in our microbial ecosystem are good or bad, but first we have to know what the landscape looks like and how our daily habits change it.”

Cultured bacteria from one of the samples in the study. 
Photo credit: Dawn Stancil, North Carolina Central University.

“Thousands of bacteria species have the potential to live on human skin, and in particular in the armpit,” says Rob Dunn, a professor of applied ecology at NC State and co-author of the paper. “Just which of these species live in any particular armpit has been hard to predict until now, but we’ve discovered that one of the biggest determinants of the bacteria in your armpits is your use of deodorant and/or antiperspirant.”

“Within the last century, use of underarm products has become routine for the vast majority of Americans,” says Julie Urban, co-author of the paper, assistant head of the genomics and microbiology laboratory at the NC Museum of Natural Sciences, and adjunct professor of entomology at NC State. “Yet, whether use of these products favors certain bacterial species – be they pathogenic or perhaps even beneficial – seems not to have been considered, and remains an intriguing area needing further study.”

Chart detailing differences in microbial diversity among study participants.  
Credit:  North Carolina State University

To learn about the microbial impact of antiperspirant and deodorant, the researchers recruited 17 study participants: three men and four women who used antiperspirant products, which reduce the amount we sweat; three men and two women who used deodorant, which often includes ethanol or other antimicrobials to kill off odor-causing microbes; and three men and two women who used neither product. They then launched an eight-day experiment, in which all of the participants had swabs taken of their armpits between 11 a.m. and 1 p.m.

On day one, participants followed their normal hygiene routine in regard to deodorant or antiperspirant use. On days two through six, participants did not use any deodorant or antiperspirant. On days seven and eight, all participants used antiperspirant.

The researchers then cultured all the samples to determine the abundance of microbial organisms growing on each participant and how that differed day to day.

“We found that, on the first day, people using antiperspirant had fewer microbes in their samples than people who didn’t use product at all – but there was a lot of variability, making it hard to draw firm conclusions,” Horvath says. “In addition, people who used deodorant actually often had more microbes – on average – than those who didn’t use product.”

By the third day, participants who had used antiperspirant were beginning to see more microbial growth. And by day six, the amount of bacteria for all study participants was fairly comparable.

“However, once all participants began using antiperspirant on days seven and eight, we found very few microbes on any of the participants, verifying that these products dramatically reduce microbial growth,” Horvath notes.

The researchers also did genetic sequencing on all of the samples from days three and six, to determine how antiperspirant and deodorant might affect the microbial biodiversity – the composition and variety of types of bacteria – over time.

They found that, among study participants who hadn’t worn deodorant or antiperspirant, 62 percent of the microbes they found were Corynebacteria, followed by various Staphylococcaceae bacteria (21 percent), with a random assortment of other bacteria accounting for less than 10 percent. Corynebacteria are partially responsible for producing the bad smells we associate with body odor, but they are also thought to help us defend against pathogens. Staphylococcaceae are a diverse group of bacteria that are among the most common microbes found on human skin and, while some can pose a risk to human health, most are considered beneficial.

The participants who had been regular antiperspirant users coming into the study had wildly different results. Sixty percent of their microbes were Staphylococcaceae, only 14 percent were Corynebacteria, and more than 20 percent were filed under “other” – meaning they were a grab-bag of opportunistic bacteria.

“Using antiperspirant and deodorant completely rearranges the microbial ecosystem of your skin – what’s living on us and in what amounts,” Horvath says. “And we have no idea what effect, if any, that has on our skin and on our health. Is it beneficial? Is it detrimental? We really don’t know at this point. Those are questions that we’re potentially interested in exploring.”

The new findings also highlight how human behavior can have a profound, if unintended, impact on the evolution of microbial organisms.

In another paper, published last month in Proceedings of the Royal Society B, the researchers, in addition to collaborators at Duke and the University of Pennsylvania, examined the diversity and abundance of microbes found in the armpits of humans, compared to other primates: chimpanzees, gorillas, baboons and rhesus macaques. In that paper, the researchers found that armpit microbes have evolved over time in conjunction with the primates they live on. But the microbial ecosystems found in the armpits of humans are vastly different – and far less diverse – than those found in our primate relatives.

“One exciting finding was that the non-human primates were more covered in fecal and soil associated microbes, which we often view as dirty,” Horvath says. “Perhaps the diversity of fecal and soil microbes on non-human primate skin serves some benefit that we don’t yet understand or appreciate.

“Over evolutionary time, we would expect our microbes to co-evolve with us,” Horvath says. “But we appear to have altered that process considerably through our habits, from bathing to taking steps to change the way we look or smell.”

The PeerJ paper, “The effect of habitual and experimental antiperspirant and deodorant product use on the armpit microbiome,” is under embargo and will be published at 7 a.m. EST on Feb. 2. The paper was co-authored by Daniel Fergus, Amy Savage, Megan Ehlers and Holly Menninger.

The paper was supported by the National Science Foundation, under grants 0953390 and 1319293; the U.S. Army Research Office, under grant W911NF-14-1-0556; and the Howard Hughes Medical Institute, under grant 52006933.

Contacts and sources: 
Matt Shipman
North Carolina State University

Superwinds Driven by Star Births and Star Deaths

An international team led by a researcher from Hiroshima University has succeeded in revealing the detailed structure of a massive ionized gas outflow streaming from the starburst galaxy NGC 6240. The team used the Suprime-Cam mounted on the 8.2-meter Subaru Telescope on Maunakea in Hawaii.

The ionized gas the astronomers observed extends across 300,000 light-years and is carried out of the galaxy by a powerful superwind. That wind is driven by intense star-forming activity at the galactic center. The light-collecting power and high spatial resolution of Subaru Telescope made it possible to study, for the first time, the complex structure of one of the largest known superwinds being driven by star birth - and star death.

Blue, green, and red colors are attributed to the B-band, R-band, and H-alpha (emission line from ionized hydrogen gas) images, respectively. The giant ionized gas blown out from the galaxy is seen in red.
Credit: Hiroshima University / NAOJ

The term "starburst" indicates large-scale intensive star-forming activity, making a "starburst galaxy" one where star birth is occurring on a grand scale. The star formation rate (SFR) of our Milky Way Galaxy is approximately one solar mass per year. By contrast, the SFRs of starburst galaxies reach ten, or even a hundred to a thousand solar masses per year.

Starburst activity is a very important part of galaxy evolution. When a starburst occurs, the intense episode star formation rapidly consumes the galaxy's interstellar gas. In addition, ultraviolet light from newborn massive stars as well as gas heating and ram pressure from supernova explosions blows much of a galaxy's gas away into intergalactic space. This galactic-scale energetic wind is called a "galactic wind" or "superwind". Its action forces interstellar gas out of the galaxy very efficiently, which accelerates the galaxy's gas-loss rate. It also chokes off star formation.

The metal-rich gas expelled from the galaxy's disk pollutes its halo as well as intergalactic space. Consequently, starburst and starburst-driven superwind significantly affect the evolution of the galaxy and the gas outside of that galaxy.

This image was produced by subtracting the stellar continuum light from the H-alpha image and extracting the pure (net) H-alpha emission. The complicated filamentary structure extends over hundreds of thousands light years.
Credit: Hiroshima University / NAOJ

One of the mechanisms that seems to induce large-scale starburst activity is galaxy collision and merger. When two gas-rich giant spiral galaxies merge, the gravitational perturbation induced by the merging process disturbs the orbits of stars. At the same time, the gas in the galaxy disks loses its angular momentum via viscous process associated with gas mixture, and falls into the gravitational center of the merger. This creates a vast concentration of gas, which begins to coalesce, creating a starburst knot. The starburst also creates a huge amount of dust which emits strong infrared radiation as it absorbs ultraviolet light from the newly born massive stars.

NGC 6240 is a starburst galaxy fairly close to the Milky Way, at a distance of about 350 million light-years. Its SFR is estimated to be 25-80 times that of our galaxy. It has a peculiar, disturbed morphology which indicates that two spiral galaxies are merging. Due to the giant starburst at its heart as a result of the merger, NGC 6240 is very bright in infrared light being emitted from heated dust. The total infrared luminosity reaches almost a trillion times of that the Sun's.

NGC 6240 is an important object to investigate in order to understand the physical and evolutional relationship among the processes of galaxy merger, the action of a starburst, and the phenomenon of an active galactic nucleus. Hence, it is one of the most-studied starburst galaxies in the nearby universe within 500 million light-years of the Sun.

The research team wanted a wide-field of NGC 6240. The Suprime-Cam optical camera was used on Subaru Telescope to zero in on the detailed structure of the starburst-driven superwind. In addition, the team searched for important clues to understanding the starburst history of NGC 6240. They observed the galaxy using a special band-pass filter that selectively transmits the light around an emission line produced by ionized hydrogen (called the H-alpha emission line). It allowed them to study the structure of the ionized gas associated with the superwind.

Their unprecedented deep observation (long-exposure images) revealed a complex giant ionized gas nebula (called an "H-alpha nebula") surrounding NGC 6240. This nebula extends out about 300,000 light-years and contains complicated structures of filaments, loops, and blobs. 

a) Right panel: Same as Figure 2. The giant ionized gas nebula (H-alpha nebula) of NGC 6240. This image was produced by subtracting the stellar continuum light from the H-alpha image and extracting the pure (net) H-alpha emission. The complicated filamentary structure extends over hundreds of thousands light years. b) Left panel: A sketch of the H-alpha nebula of NGC 6240.

Credit: Hiroshima University / NAOJ

Astronomers knew that such a large ionized gas nebula surrounds NGC 6240, but the depth of the observation significantly surpassed any previous studies and first allowed the Hiroshima team to study the some of the faintest, most detailed structure of the nebula. Large "broken bubbles" were detected in the northwestern and southeastern parts of the galaxy. These features are the evidence of a past energetic bipolar-shaped superwind that blew along the minor axis of the main galaxy disk (orthogonal to the main galactic disk).

The research team performed detailed data analysis and found that NGC 6240 has experienced violent starbursts at least three times in the past and each starburst drove an energetic superwind. Those superwinds form complex structure in the H-alpha nebula. The oldest starburst started about 80 million years ago. 

Astronomers think that the galaxy merger process of NGC 6240 began about a billion years ago, so this work suggests that the later stages of the merger are what excited the gigantic starbursts and subsequent superwinds. These results contribute new information to the studies of galaxy evolution and its relation to galaxy-galaxy mergers.

Contacts and sources:
National Institutes Of Natural Sciences

Long-Term Global Warming Not Driven Naturally

By examining how Earth cools itself back down after a period of natural warming, a study by scientists at Duke University and NASA's Jet Propulsion Laboratory confirms that global temperature does not rise or fall chaotically in the long run. Unless pushed by outside forces, temperature should remain stable. The new study debunks argument that warming is driven by natural factors.

The new evidence may finally help put the chill on skeptics' belief that long-term global warming occurs in an unpredictable manner, independently of external drivers such as human impacts.

"This underscores that large, sustained changes in global temperature like those observed over the last century require drivers such as increased greenhouse gas concentrations," said lead author Patrick Brown, a PhD student at Duke's Nicholas School of the Environment. Natural climate cycles alone are insufficient to explain such changes, he said.

The Earth's thin atmosphere as viewed from space. A new study from NASA and Duke finds natural cycles alone aren't sufficient to explain warming trends observed over the last century.

Credit: NASA 

Brown and his colleagues published their peer-reviewed research Feb. 1 in the Journal of Climate.

Using global climate models and NASA satellite observations of Earth's energy budget from the last 15 years, the study finds that a warming Earth is able to restore its temperature equilibrium through complex and seemingly paradoxical changes in the atmosphere and the way radiative heat is transported.

Scientists have long attributed this stabilization to a phenomenon known as the Planck Response, a large increase in infrared energy that Earth emits as it warms. Acting as a safety valve of sorts, this response creates a negative radiative feedback that allows more of the accumulating heat to be released into space through the top of the atmosphere.

The new Duke-NASA research, however, shows it's not as simple as that.

"Our analysis confirmed that the Planck Response plays a dominant role in restoring global temperature stability, but to our surprise we found that it tends to be overwhelmed locally by heat-trapping positive energy feedbacks related to changes in clouds, water vapor, and snow and ice," Brown said. "This initially suggested that the climate system might be able to create large, sustained changes in temperature all by itself."

A more detailed investigation of the satellite observations and climate models helped the researchers finally reconcile what was happening globally versus locally.

"While global temperature tends to be stable due to the Planck Response, there are other important, previously less appreciated, mechanisms at work too," said Wenhong Li, assistant professor of climate at Duke. These other mechanisms include a net release of energy over regions that are cooler during a natural, unforced warming event. And there can be a transport of energy from the tropical Pacific to continental and polar regions where the Planck Response overwhelms positive, heat-trapping local effects.

"This emphasizes the importance of large-scale energy transport and atmospheric circulation changes in restoring Earth's global temperature equilibrium after a natural, unforced warming event," Li said.

Contacts and sources:
Tim Lucas
Duke University

Citation: "Unforced Surface Air Temperature Variability and Its Contrasting Relationship with the Atmospheric TOA Energy Flux at Local and Global Spatial Scales," Patrick T. Brown, Wenhong Li, Jonathan H. Jiang, Hui Su, Feb. 1, 2016, Journal of Climate; DOI: http://dx.doi.org/10.1175/JCLI-D-15-0384.1

Jonathan H. Jiang and Hui Su of NASA's Jet Propulsion Laboratory, managed by the California Institute of Technology, co-authored the new study.

Funding came from the National Science Foundation (#AGS-1147608) as well as the NASA ROSES13-NDOA and ROSES13-NEWS programs.

Climate Not to Blame for Megafauna Extinction in Australia

New research led by the University of Adelaide has found no relationship between sixteen megafauna extinctions in Australia and past climate change, suggesting humans were having negative impacts on the ecosystem as long as 55,000 years ago.

In a paper published in the journal Nature Communications, Dr Frédérik Saltré, from the University of Adelaide’s Environment Institute, and colleagues analysed dated ‘megafauna’ (animals weighing more than 40 kg) fossil records, archaeological evidence of the first humans in Australia and past climate data. 

Credit:  University of Adelaide

This research was conducted in collaboration with ecologists, palaeoclimatologist, archaeologists, geochronologists and mathematicians, and led by the University of Adelaide’s Professor Corey Bradshaw to address one of the longest-lasting and fiercest scientific debates in Australia.

“There has long been disputes about what caused the extinction of megafauna in Australia, and climate change was considered to be one of the potential culprits,” says Dr Saltré.

“To test this hypothesis, we collated a wide variety of reliable data to develop an accurate timeline of human arrival in Australia, when megafauna species went extinct, and the climate conditions over the same period.

“We calculated that humans first arrived in Australia approximately 55,000 years ago and the extinction of megafauna began 42,000 years ago. Which means humans and megafauna coexisted for some 13,000 years.

“We also discovered that during the peak period of megafauna extinctions, Australia was arid and hot; however, the species had endured much more volatile weather patterns in the years prior to human arrival in Australia (between 120,000 and 60,000 years ago),” he says. “Therefore, it is highly unlikely that variation in climate drove continent-wide extinctions of these species.”

Dr Saltré says, while he was primarily focusing on the impact of climate on megafauna species, his research supports the hypothesis that the presence of humans was the principal driver of the extinctions of megafauna in Australia.

“Our findings support those by my colleague, Gifford Miller, from the University of Colorado,” says Dr Saltré.

“Species that looked like larger kangaroos, emus, koalas and echidnas were once abundant in Australia, but started to disappear some 13,000 years after humans arrived.

“13,000 years would have given the first Australian humans plenty of time to explore and colonise the continent, and have an impact on the continent’s ecosystem.

“It looks like the first humans who arrived in Australia around 55,000 years ago were also the first in history to have such a large, negative impact on the ecosystem of an entire continent,” he states.

Dr Saltré and his team will now focus on particular regions of Australia to see if local climate patterns could have influenced the role of humans in the demise of the megafauna.

This research was done in collaboration with the University of Tasmania, University of New South Wales, University of Wollongong, James Cook University, Australian National University, Curtin University, Flinders University, Macquarie University, Spanish National Museum of Natural Sciences, University of Colorado and Natural History Museum of Denmark, and was supported by the Australian Research Council.

Contacts and sources: 
Dr Frederik Saltre
University of Adelaide

Rhino, Tiger and Snow Leopard DNA Found in Chinese Medicines

More should be done to stop the use of endangered species in traditional Chinese medicines, with snow leopard, tiger and rhinoceros DNA still being found in remedies, according to a leading University of Adelaide pathologist.

In an article published in the journal Forensic Science Medicine and Pathology, Professor Roger Byard, from the University’s School of Medicine, has shown that traditional Chinese medicine has been identified as a significant driver in the illicit global wildlife trade. Furthermore, most of the policing surrounding the illegal trade is associated with species collection; the use of animal products in medicines is often overlooked.

Credit: University of Adelaide

“Rhinoceros horn is used to “cure” disorders ranging from cerebral haemorrhage to AIDS, selling for as much as US$50,000 per kilogram; the powdered bones of tigers and mole rats are used to treat arthritis; shell extracts of freshwater turtles are used to treat cancer; dried geckos are used as an aphrodisiac; monkey skeletons are used to treat general pain; and moon bears are milked for their bile through catheters in order to provide people with a treatment for digestive illnesses,” says Professor Byard.

“The World Health Organization has suggested that 80% of people in developing countries rely on traditional medicines, and it has been estimated that 13% of traditional Chinese medicines contain animal derivatives.

“Approximately 50% of the reptiles used in traditional medicines are on lists of threatened or endangered species. And the effectiveness of many of these animal products in treating disease has not been established,” he says.

Professor Byard would like more to be done to control the use of endangered and threatened animals in traditional medicines.

“Wildlife crime has been estimated to cost between US$10 and $20 billion per year globally,” says Professor Byard.

“While much of the crime involves the illegal collection of uncommon species, or the use of rare materials such as ivory and rhinoceros horn for decorative purposes, one area that is being largely overlooked is that of traditional medicines.

“Surprisingly, even a Chinese medicine product purchased over the counter in Adelaide, Australia, was found to contain traces of snow leopard.

“Clearly any controls on the importation and sale of such a preparation have failed. It is also uncertain what steps are taken by authorities once such a preparation is brought to their attention.

“This illegal and very damaging trade needs to stop, however, unfortunately, for a number of species, it may already be too late,” he says.\

Contacts and sources: 
Roger Byard
University of Adelaide

Wednesday, February 3, 2016

New Animation Takes a Colorful Flight Over Ceres

A colorful new animation shows a simulated flight over the surface of dwarf planet Ceres, based on images from NASA's Dawn spacecraft.

The movie shows Ceres in enhanced color, which helps to highlight subtle differences in the appearance of surface materials. Scientists believe areas with shades of blue contain younger, fresher material, including flows, pits and cracks.

The animated flight over Ceres emphasizes the most prominent craters, such as Occator, and the tall, conical mountain Ahuna Mons. Features on Ceres are named for earthly agricultural spirits, deities and festivals.

Simulated view of Dwarf planet Ceres using images from NASA's Dawn spacecraft. 
Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

The movie was produced by members of Dawn's framing camera team at the German Aerospace Center, DLR, using images from Dawn's high-altitude mapping orbit. During that phase of the mission, which lasted from August to October 2015, the spacecraft circled Ceres at an altitude of about 900 miles (1,450 kilometers).

"The simulated overflight shows the wide range of crater shapes that we have encountered on Ceres. The viewer can observe the sheer walls of the crater Occator, and also Dantu and Yalode, where the craters are a lot flatter," said Ralf Jaumann, a Dawn mission scientist at DLR.

Dawn is the first mission to visit Ceres, the largest object in the main asteroid belt between Mars and Jupiter. After orbiting asteroid Vesta for 14 months in 2011 and 2012, Dawn arrived at Ceres in March 2015. The spacecraft is currently in its final and lowest mapping orbit, at about 240 miles (385 kilometers) from the surface.

Dawn's mission is managed by the Jet Propulsion Laboratory for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team. For a complete list of mission participants, visit:

Contacts and sources:
Elizabeth Landau
Jet Propulsion Laboratory