Tuesday, July 31, 2018

High Fiber Foods Reduce Stress and Improve Mood

Eating high fiber foods may reduce the effects of stress on our gut and behavior, according to new research published in The Journal of Physiology.

Stress is a significant health concern and can cause major changes in the gut and in the brain, which can cause changes in behaviour. In recent years there has been growing interest in the link between gut bacteria and stress-related disorders including anxiety, depression and irritable bowel syndrome.

Bacteria in the gut produce short-chain fatty acids (SCFAs), which are the main source of nutrition for cells in this region of the body1. Foods such as grains, legumes and vegetables, contain high levels of fibres and will stimulate the production of these SCFAs.
 Credit: CSIRO

The study conducted by scientists at APC Microbiome Ireland at University College Cork and Teagasc Food Research Centre found that there was decreased levels of stress and anxiety-like behaviour when SCFAs were introduced.

Moreover, stress experienced over a prolonged period of time can affect the bowel by making the barrier between the inside of the gut and the rest of the body less effective and "leaky". This means undigested food particles, bacteria and germs will pass through the leaky gut wall into the blood and cause persistent inflammation. Treating with the SCFAs can also reverse this "leakiness".

These results provide new insights into mechanisms related to the impact of the gut bacteria on the brain and behaviour as well as gut health. Developing dietary treatments which target these bacteria will be important for treating stress-related disorders.

The study involved feeding mice the main SCFAs normally produced by the gut bacteria and then subjecting them to stress. Using behavioural tests the mice were assessed for anxiety and depressive-like behaviour, stress-responsiveness, cognition and sociability as well as how easily material passes through the gut.

The exact mechanisms by which SCFAs facilitate their effect remain undetermined. SCFAs had no effect on an increase in body weight caused by stress therefore understanding why SCFAs only affect certain stress-induced effects will be important.

Professor John F. Cryan, the corresponding author on the research, commented on the findings 'There is a growing recognition of the role of gut bacteria and the chemicals they make in the regulation of physiology and behaviour. The role of short-chain fatty acids in this process is poorly understood up until now. It will be crucial that we look at whether short-chain fatty acids can ameliorate symptoms of stress-related disorders in humans.'

Contacts and sources:
Andrew Mackenzie
The Physiological Society

EJU Study Examines Exposure to EMF at Work and Brain Tumors

By assessing individual exposure to electromagnetic fields, INTEROCC represents the most comprehensive study in the field

No clear associations were found between occupational exposure to high frequency electromagnetic fields (EMF) and risk of glioma or meningioma, in one of the largest epidemiological studies performed to date and led by ISGlobal, an institution supported by "la Caixa" Foundation. However, the findings highlight the need for further research on radiofrequency magnetic fields and tumour promotion, as well as possible interactions with other frequencies and with chemicals.

High frequency electromagnetic fields are a form of non-ionising radiation and comprise intermediate frequency (3kHz-10MHz) and radiofrequency (10MHz-300 GHz). Based on limited animal and epidemiological evidence, they were declared by WHO's International Agency for Research on Cancer (IARC) in 2011 as possibly carcinogenic to humans, but few recent studies have provided further evidence regarding exposure at work. "This is the largest study of brain tumours and occupational high-frequency EMF exposure to date", explains senior author Elisabeth Cardis, Head of the Radiation Programme at ISGlobal.

This is a westerbork radio telescope.

Photo by Tim van der Kuip

The researchers developed a 'source-exposure matrix' based on measurements collected from the literature for EMF sources reported by the study participants. With this tool plus detailed individual data, they estimated individual RF and IF exposure at work and analysed the possible association with risk of glioma or meningioma, two of the most frequent brain tumours in adults. The INTEROCC study, performed under the umbrella of INTERPHONE, and supported by the European project GERoNiMO, comprised 2,054 glioma cases, 1,924 meningioma cases and 5,601 controls from seven countries. Occupational sectors that involved exposure to electromagnetic fields included working with or near radars, telecommunication antennas, medical diagnosis and treatment and microwave drying ovens, among others.

Despite the major improvements in estimating exposure, this large case-control study provided no clear evidence for a positive association between cumulative high-frequency EMF exposure and glioma or meningioma risk. However, the number of exposed participants was small: only 10% of the participants were exposed to radiofrequencies and less than 1% were exposed to intermediate frequencies, which limited the statistical power to find clear associations, if they exist.

"Our individualised exposure assessment approach is an important improvement over previous efforts to assess high-frequency EMF exposure risks. Although we did not find a positive association, the fact that we observed indication of an increased risk in the group with most recent radiofrequency exposure deserves further investigation," explains first author Javier Vila. "We also need to investigate possible interactions with other frequencies, and with chemicals," adds Cardis.

Contacts and sources:
Pau Rubio
Barcelona Institute for Global Health (ISGLOBAL)

Citation: Occupational exposure to high-frequency electromagnetic fields and brain tumor risk in the INTEROCC study: An individualized assessment approach
Environment International
Volume 119, October 2018, Pages 353-365 http://dx.doi.org/10.1016/j.envint.2018.06.038

Why Has Largest King Penguin Colony Shrunk Nearly 90%

The world's biggest colony of king penguins is found in the National Nature Reserve of the French Southern and Antarctic Lands (TAAF). Using high-resolution satellite images, researchers from the Chizé Centre for Biological Studies (CNRS / University of La Rochelle)1 have detected a massive 88% reduction in the size of the penguin colony, located on Île aux Cochons, in the Îles Crozet archipelago. The causes of the colony's collapse remain a mystery but may be environmental. These findings are published in Antarctic Science (July 25).

Known since the 1960s, the colony of king penguins (Aptenodytes patagonicus) on Île aux Cochons, in the southern Indian Ocean, had the distinction of being the world's biggest colony of king penguins and second biggest colony of all penguins. However, due to its isolation and inaccessibility, no new estimates of its size were made over the past decades.

Île aux Cochons king penguin colony in 1982. 

Credit:  © Henry Weimerskirch

The Chizé team used high-resolution satellite images to measure changes in the size of the colony since the island was last visited by a crew of scientists (1982). At the time, the colony included 500,000 breeding pairs and consisted of over two million penguins. To calculate the area occupied by the colony at different times between 1960 and the present, the researchers studied changes in its contours over the years. They found that the colony has shrunk, yielding its territory to encroaching vegetation. Photographs taken from a helicopter during the Antarctic Circumpolar Expedition confirm that the colony's penguin population has plummeted.

Data show that the decline began in the late 1990s, coinciding with a major climatic event in the Southern Ocean related to El Niño. This event temporarily affected the foraging capacities of another colony 100 km from Île aux Cochons, causing it to dwindle. The same process may be responsible for the fate of the Île aux Cochons colony

Northern view of colony from helicopter on December 30, 2016. 

Credit: © Peter Ryan

 Its size may also subject it to density-dependent effects. That is, the larger the population, the fiercer the competition between individuals, slowing the growth of all members of the group. The repercussions of lack of food are thus amplified and can trigger an unprecedented rapid and drastic drop in numbers, especially following a climatic event like the one at the end of the 1990s.

Disease is another hypothesis entertained. Avian cholera is currently ravaging populations of seabirds on other islands in the Indian Ocean, like the albatross of Île Amsterdam and the penguins of Marion Island.

Gradual shrinkage of bare ground surface area, corresponding to extent of colony.

Credit: © Henry Weimerskirch

Still, none of these possibilities seems to offer a satisfactory explanation for a decline of the magnitude observed on Île aux Cochons. Field studies led by CNRS researchers, with support from the French Polar Institute (IPEV), and in close partnership with TAAF nature reserve staff, should be getting under way shortly to verify initial conclusions drawn from the satellite images.

Contacts and sources:
Henri Weimerskirch / Juliette Dunglas

Citation: Massive decline of the world’s largest king penguin colony at Ile aux Cochons, Crozet.
Henri Weimerskirch, Fabrice Le Bouard, Peter G. Ryan, C.A. Bost. Antarctic Science, 2018; 30 (04): 236 DOI: 10.1017/S0954102018000226

Finally Einstein’s General Relativity Near Black Hole Confirmed

Observations made with ESO’s Very Large Telescope have for the first time clearly revealed the effects of Einstein’s general relativity on the motion of a star passing through the extreme gravitational field very close to the supermassive black hole in the centre of the Milky Way. This long-sought result represents the climax of a 26-year-long observation campaign using ESO’s telescopes in Chile.

Obscured by thick clouds of absorbing dust, the closest supermassive black hole to the Earth lies 26 000 light years away at the centre of the Milky Way. This gravity monster, which has a mass four million times that of the Sun, is surrounded by a small group of stars orbiting at high speed. This extreme environment – the strongest gravitational field in our galaxy – makes it the perfect place to test gravitational physics, particularly Einstein’s general theory of relativity.

This artist’s impression shows the path of the star S2 as it passes very close to the supermassive black hole at the centre of the Milky Way. As it gets close to the black hole the very strong gravitational field causes the colour of the star to shift slightly to the red, an effect of Einstein’s general thery of relativity. In this graphic the colour effect and size of the objects have been exaggerated for clarity.
Artist’s impression of S2 passing supermassive black hole at centre of Milky Way
Credit: ESO/M. Kornmesser

New infrared observations from the exquisitely sensitive GRAVITY, NACO and SINFONI instruments on ESO’s Very Large Telescope (VLT) have now allowed astronomers to follow one of these stars, called S2, as it passed very close to the black hole during May 2018 at a speed in excess of 25 million kilometres per hour – three percent of the speed of light – and at a distance of less than 20 billion kilometres.

These extremely delicate measurements were made by an international team led by Reinhard Genzel of the Max Planck Institute for extraterrestrial physics (MPE) in Garching, Germany, in conjunction with collaborators around the world. The observations form the culmination of a 26-year series of ever more precise observations of the centre of the Milky Way using ESO instruments. ‘This is the second time that we have observed the close passage of S2 around the black hole in our galactic centre. But this time, because of much improved instrumentation, we were able to observe the star with unprecedented resolution’, explains Genzel. ‘We have been preparing intensely for this event over several years, as we wanted to make the most of this unique opportunity to observe general relativistic effects.’

This artist’s impression video shows the path of the star S2 as it passes very close to the supermassive black hole at the centre of the Milky Way. As it gets close to the black hole the very strong gravitational field causes the colour of the star to shift slightly to the red, an effect of Einstein’s general thery of relativity. In this graphic the colour effect, speed and size of the objects have been exaggerated for clarity.

Credit: ESO/M. Kornmesser

The new measurements clearly reveal an effect called gravitational redshift. Light from the star is stretched to longer wavelengths by the very strong gravitational field of the black hole. And the stretch in wavelength of light from S2 agrees precisely with that predicted by Einstein’s theory of general relativity. This is the first time that this deviation from the predictions of simpler Newtonian gravity has been observed in the motion of a star around a supermassive black hole. The team used SINFONI to measure the motion of S2 towards and away from Earth and the GRAVITY interferometric instrument to make extraordinarily precise measurements of the position of S2 in order to define the shape of its orbit. GRAVITY creates such sharp images that it can reveal the motion of the star from night to night as it passes close to the black hole – 26 000 light years from Earth.

This simulation shows the orbits of stars very close to the supermassive black hole at the heart of the Milky Way. One of these stars, named S2, orbits every 16 years and is passing very close to the black hole in May 2018. This is a perfect laboratory to test gravitational physics and specifically Einstein's general theory of relativity.
Orbits of stars around black hole at the heart of the Milky Way
Credit:  ESO/L. Calçada/spaceengine.org

‘Our first observations of S2, about two years ago, already showed that we would have the ideal black hole laboratory’, adds Frank Eisenhauer (MPE), Co-Principal Investigator of the GRAVITY instrument. ‘During the close passage, we managed not only to precisely follow the star on its orbit, we could even detect the faint glow around the black hole on most of the images.’ By combining the position and velocity measurements from SINFONI and GRAVITY, as well as previous observations using other instruments, the team could compare them to the predictions of Newtonian gravity, general relativity and other theories of gravity. As expected, the new results are inconsistent with Newtonian predictions and in excellent agreement with the predictions of general relativity. More than one hundred years after he published his paper setting out the equations of general relativity, Einstein has been proved right once more.

This simulation shows the orbits of a tight group of stars close to the supermassive blackhole at the heart of the Milky Way. During 2018 one of these stars, S2, passed very close to the black hole and was the subject of intense scrutiny with ESO telescope. Its behaviour matched the predictions of Einsteins's general relativity and was inconsistent with simpler Newtonian gravity.

Credit:  ESO/L. Calçada/spaceengine.org

The hardware contribution of the Institute of Physics I of the University of Cologne was the development and construction of the two spectrometers of GRAVITY. The spectrometers analyse the wavelength of the observed stellar light and convert the received photons into electronic signals. ‘GRAVITY is a technological challenge. However, after more than two decades of astrophysical research on the high velocity stars in the Galactic Centre and on the development of astronomical instrumentation, the effort has been rewarded with an excellent result in experimental physics’, says Andreas Eckhart from the University of Cologne.

Continuing observations are expected to reveal another relativistic effect later in the year – a small rotation of the star’s orbit, known as Schwarzschild precession – as S2 moves away from the black hole.

Xavier Barcons, ESO’s Director General, concludes: ‘ESO has worked with Reinhard Genzel and his team and collaborators in the ESO Member States for over a quarter of a century. It was a huge challenge to develop the uniquely powerful instruments needed and make these very delicate measurements. The discovery announced today is the very satisfying result of a remarkable partnership.’

This artist’s impression shows the path of the star S2 as it passes very close to the supermassive black hole at the centre of the Milky Way. As it gets close to the black hole the very strong gravitational field causes the colour of the star to shift slightly to the red, an effect of Einstein’s general thery of relativity. In this graphic the colour effect and size of the objects have been exaggerated for clarity.
Artist’s impression of S2 passing supermassive black hole at centre of Milky Way - annotated
Credit: ESO/M. Kornmesser

Contacts and sources:
Dr. Andreas Eckart
University of Cologne

    Citation: Detection of the gravitational redshift in the orbit of the star S2 near the Galactic centre massive black hole. Astronomy & Astrophysics, 2018; 615: L15 DOI: 10.1051/0004-6361/201833718
    Authors: R. Abuter, A. Amorim, N. Anugu, M. Bauböck, M. Benisty, J. P. Berger, N. Blind, H. Bonnet, W. Brandner, A. Buron, C. Collin, F. Chapron, Y. Clénet, V. Coudé du Foresto, P. T. de Zeeuw, C. Deen, F. Delplancke-Ströbele, R. Dembet, J. Dexter, G. Duvert, A. Eckart, F. Eisenhauer, G. Finger, N. M. Förster Schreiber, P. Fédou, P. Garcia, R. Garcia Lopez, F. Gao, E. Gendron, R. Genzel, S. Gillessen, P. Gordo, M. Habibi, X. Haubois, M. Haug, F. Haußmann, Th. Henning, S. Hippler, M. Horrobin, Z. Hubert, N. Hubin, A. Jimenez Rosales, L. Jochum, L. Jocou, A. Kaufer, S. Kellner, S. Kendrew, P. Kervella, Y. Kok, M. Kulas, S. Lacour, V. Lapeyrère, B. Lazareff, J.-B. Le Bouquin, P. Léna, M. Lippa, R. Lenzen, A. Mérand, E. Müler, U. Neumann, T. Ott, L. Palanca, T. Paumard, L. Pasquini, K. Perraut, G. Perrin, O. Pfuhl, P. M. Plewa, S. Rabien, A. Ramírez, J. Ramos, C. Rau, G. Rodríguez-Coira, R.-R. Rohloff, G. Rousset, J. Sanchez-Bermudez, S. Scheithauer, M. Schöller, N. Schuler, J. Spyromilio, O. Straub, C. Straubmeier, E. Sturm, L. J. Tacconi, K. R. W. Tristram, F. Vincent, S. von Fellenberg, I. Wank, I. Waisberg, F. Widmann, E. Wieprecht, M. Wiest, E. Wiezorrek, J. Woillez, S. Yazici, D. Ziegler, G. Zins

How Religious Ideologies Spread?

Over the last 2000 years Christianity has grown from a tiny religious sect to the largest family of religions in the world. How did Christianity become so successful? Did Christianity spread through grass-roots movements or political elites? And what can the spread of Christianity tell us about how widespread social change happens? 

The chiefs Waikato and Hongi Hika with missionary Thomas Kendall, Oil on canvas by James Barry, 1820.

Credit: National Library of New Zealand Te Puna Mātauranga o Aotearoa, Alexander Turnbull Library, Wellington (Ref:G-618)

A paper published July 23  in Nature Human Behaviour uses new computational cross-cultural methods to help answer these questions. The research tested how political hierarchies, social inequality, and population size affected the spread of Christianity in 70 Austronesian societies.

Austronesian societies shared a common ancestral language and are located across Southeast Asia, East Africa and the South Pacific. Historically, they ranged from very small egalitarian family-based communities to large politically complex societies such as Hawaii. Conversion typically happened in the 18th and 19thcenturies, and while some societies took less than a year to convert, others took up to 205 years. The range of social structures and conversion histories makes Austronesian societies ideal for theories about how cultural change happens.

The results of the study show that cultures with political leadership structures were often the fastest to convert to Christianity. This supports a “top-down” process of conversion whereby chiefs and elite leaders, themselves converted by missionaries, were highly influential in spreading Christian doctrine among their people.

In contrast, social inequality was not related to conversion times. This challenges one of the most widely-cited reasons for Christianity’s popularity, that it spread from the “bottom-up” by empowering lower classes and promising to improve the lives of the less privileged in the afterlife.

The research also found that Christianity spread most quickly among small populations. This helps clarify the importance of population size in processes of cultural change.

“While people often think of big societies as sources of innovation, our findings show that bigger societies can also be slow to pick up on new ideas,” says lead author Dr Joseph Watts who undertook the research at the University of Auckland’s School of Psychology and at the Max Planck Institute for the Science of Human History in Jena, Germany. “In a small population, it becomes more likely that beliefs will be transmitted relatively quickly, particularly if they are being driven by leaders and other powerful figures.”

Dr Watts says the findings provide significant insight into large-scale human behaviour and the process of cultural change, a fascinating aspect of human life. “If you look at our contemporary world, some things spread incredibly quickly while others take a very long time so here we provide evidence of why that might be.”

University of Auckland Professor Quentin Atkinson, a researcher in this study, says that finding new answers about how beliefs have spread in the past gives us insight into how they might spread in the future. “This research can help us understand how both the size and the structure of populations influence the diffusion and adoption of new institutions, ideologies or technologies.”

The study was undertaken in collaboration with researchers at the University of Auckland in New Zealand and the Max Planck Institute for the Science of Human History in Germany. The research team also includes doctoral candidate Oliver Sheehan, Professor Joseph Bulbulia, and Professor Russell Gray.

Contacts and sources:
Russell Gray, Prof., Ph.D.
University of Auckland.

Citation: Christianity spread faster in small politically structured societies Watts, Joseph; Sheehan, Oliver; Bulbulia, Joseph; Gray, Russell D.; & Atkinson, Quentin D.
Nature Human Behaviour

Homo Sapiens Developed a Niche That Separated It from Other Hominins

Our species is ecologically unique in its ability to occupy, and specialize in, a variety of different environments as it began to colonize the entire planet between approximately 300 and 60 thousand years ago.
<p>Our species is ecologically unique in its ability to occupy, and specialize in, a variety of different environments as it began to colonize the entire planet between approximately 300 and 60 thousand years ago.</p>
Image by John Klausmeyer, concept by Brian Stewart, University of Michigan. Aerial view of reindeer herd from zanskar / iStock.

The paper, by scientists from the Max Planck Institute for the Science of Human History and the University of Michigan, suggests investigations into what it means to be human should shift from attempts to uncover the earliest material traces of ‘art’, ‘language’, or technological ‘complexity’ towards understanding what makes our species ecologically unique. In contrast to our ancestors and contemporary relatives, our species not only colonized a diversity of challenging environments, including deserts, tropical rainforests, high altitude settings, and the palaeoarctic, but also specialized in its adaptation to some of these extremes.

Ancestral ecologies – the ecology of Early and Middle Pleistocene

Although all hominins that make up the genus Homo are often termed ‘human’ in academic and public circles, this evolutionary group, which emerged in Africa around 3 million years ago, is highly diverse. Some members of the genus Homo(namely Homo erectus) had made it to Spain, Georgia, China, and Indonesia by 1 million years ago. Yet, existing information from fossil animals, ancient plants, and chemical methods all suggest that these groups followed and exploited environmental mosaics of forest and grassland. It has been argued that Homo erectus and the ‘Hobbit’, or Homo floresiensis, used humid, resource-scarce tropical rainforest habitats in Southeast Asia from 1 million years ago to 100,000 and 50,000 years ago, respectively. However, the authors found no reliable evidence for this.

Map of the potential distribution of archaic hominins, including H. erectus, H. floresiensis, H. neanderthalenesis, Denisovans and archaic African hominins, in the Old World at the time of the evolution and dispersal of H. sapiens between approximately 300 and 60 thousand years ago

© Roberts and Stewart. 2018. Defining the ‘generalist specialist’ niche for Pleistocene Homo sapiens. Nature Human Behaviour. 10.1038/s41562-018-0394-4.

It has also been argued that our closest hominin relatives, Homo Neanderthalensis– or the Neanderthals – were specialized to the occupation of high latitude Eurasia between 250,000 and 40,000 years ago. The base for this includes a face shape potentially adapted to cold temperatures and a hunting focus on large animals such as woolly mammoths. Nevertheless, a review of the evidence led the authors to again conclude that Neanderthals primarily exploited a diversity of forest and grassland habitats, and hunted a diversity of animas, from temperature northern Eurasia to the Mediterranean.

Deserts, rainforests, mountains, and the arctic

In contrast to these other members of the genus Homo, our species – Homo sapiens– had expanded to higher-elevation niches than its hominin predecessors and contemporaries by 80-50,000 years ago, and by at least 45,000 years ago was rapidly colonizing a range of palaeoarctic settings and tropical rainforest conditions across Asia, Melanesia, and the Americas. Furthermore, the authors argue that the continued accumulation of better-dated, higher resolution environmental datasets associated with our species’ crossing the deserts of northern Africa, the Arabian Peninsula, and northwest India, as well as the high elevations of Tibet and the Andes, will further help to determine the degree to which our species demonstrated novel colonizing capacities in entering these regions.

Finding the origins of this ecological ‘plasticity’, or the ability to occupy a number of very different environments, currently remains difficult in Africa, particularly back towards the evolutionary origins of Homo sapiens 300-200,000 years ago. However, the authors argue that there are tantalizing hints for novel environmental contexts of human habitation and associated technological shifts across Africa just after this timeframe. They hypothesize that the drivers of these changes will become more apparent with future work, especially that which tightly integrates archaeological evidence with highly resolved local palaeoecological data. For example, lead author of the paper, Dr. Patrick Roberts, suggests, “although a focus on finding new fossils or genetic characterization of our species and its ancestors has helped rough out the broad timing and location of hominin specifications, such efforts are largely silent on the various environmental contexts of biocultural selection".

The ‘generalist specialist’ – a very sapiens niche

Schematic of the utilization of different numbers of food webs by generalist and specialist populations, and the proposed unique human ecological niche of ‘generalist specialist’
Roberts and Stewart. 2018. Defining the ‘generalist specialist’ niche for Pleistocene Homo sapiens. Nature Human Behaviour. 10.1038/s41562-018-0394-4.

One of the main new claims of the authors is that the evidence for human occupation of a huge diversity of environmental settings across the majority of the Earth’s continents by the Late Pleistocene hints at a new ecological niche, that of the ‘generalist specialist’. As Roberts states “A traditional ecological dichotomy exists between ‘generalists’, who can make use of a variety of different resources and inhabit a variety of environmental conditions, and ‘specialists’, who have a limited diet and narrow environmental tolerance. However, Homo sapiens furnish evidence for ‘specialist’ populations, such as mountain rainforest foragers or palaeoarctic mammoth hunters, existing within what is traditionally defined as a ‘generalist’ species”.

This ecological ability may have been aided by extensive cooperation between non-kin individuals among Pleistocene Homo sapiens, argues Dr. Brian Stewart, co-author of the study. “Non-kin food sharing, long-distance exchange, and ritual relationships would have allowed populations to ‘reflexively’ adapt to local climatic and environmental fluctuations, and outcompete and replace other hominin species.” In essence, accumulating, drawing from, and passing down a large pool of cumulative cultural knowledge, in material or idea form, may have been crucial in the creation and maintenance of the generalist-specialist niche by our species in the Pleistocene.

Implications for our pursuit of ancient humanity

Map showing the youngest suggested dates of persistent occupation of the different environmental extremes discussed by our species based on current evidence.
© NASA Worldview. In Roberts and Stewart. 2018. Defining the ‘generalist specialist’ niche for Pleistocene Homo sapiens. Nature Human Behaviour. 10.1038/s41562-018-0394-4.

The authors are clear that this proposition remains hypothetical and could be disproven by evidence for the use of ‘extreme’ environments by other members of the genus Homo. However, testing the ‘generalist specialist’ niche in our species encourages research in more extreme environments that have previously been neglected as unpromising for palaeoanthropological and archaeological work, including the Gobi Desert and Amazon rainforest. The expansion of such research is particularly important in Africa, the evolutionary cradle of Homo sapiens, where more detailed archaeological and environmental records dating back to 300-200,000 years ago are becoming increasingly crucial if we are to track the ecological abilities of the earliest humans.

It is also clear that growing evidence for hominin interbreeding and a complex anatomical and behavioural origin of our species in Africa highlights that archaeologists and palaeoanthropologists should focus on looking at the environmental associations of fossils. “While we often get excited by the discovery of new fossils or genomes, perhaps we need to think about the behavioural implications of these discoveries in more detail, and pay more attention to what these new finds tell us about new the passing of ecological thresholds” says Stewart. Work focusing on how the genetics of different hominins may have led to ecological and physical benefits such as high-altitude capacities or UV tolerance remain highly fruitful ways forward in this regard.

“As with other definitions of human origins, problems of preservation also make it difficult to pinpoint the origins of humans as an ecological pioneer. However, an ecological perspective on the origins and nature of our species potentially illuminates the unique path of Homo sapiens as it rapidly came to dominate the Earth’s diverse continents and environments”, concludes Roberts. The testing of this hypothesis should open up new avenues for research and, if correct, new perspectives as to whether the ‘generalist specialist’ will continue to be an adaptive success in the face of growing issues of sustainability and environmental conflict.

Some of the ecological challenges faced by Pleistocene H. sapiens. a. The Thar Desert of northwest India at the site of Katoati. Credit: James Blinkhorn. b. The highlands of Lesotho at the site of Sehonghong. Credit: Brian A. Stewart. c. The Siberian steppe of Russia. Credit: Yuri Demyanov. d. The tropical evergreen rainforest of Sri Lanka in the vicinity of one of the earliest occupied sites in the region. Credit: Patrick Roberts.

© Roberts and Stewart. 2018. Defining the ‘generalist specialist’ niche for Pleistocene Homo sapiens. Nature Human Behaviour. 10.1038/s41562-018-0394-4.

Contacts and sources:
Patrick Roberts
Max Planck Institute for the Science of Human History

Citation: Defining the ‘generalist specialist’ niche for Pleistocene Homo sapiens.
Patrick Roberts, Brian A. Stewart. Nature Human Behaviour, 2018; 

Sunday, July 29, 2018

Gut Bacteria Byproduct Protects Against Salmonella

A molecule called propionate inhibits the growth of Salmonella in mice and may be a promising new treatment for people sickened by the pathogen, according to a new Stanford study.

Researchers at the Stanford University School of Medicine have identified a molecule that serves as natural protection against one of the most common intestinal pathogens.

Propionate, a byproduct of metabolism by a group of bacteria called the Bacteroides, inhibits the growth of Salmonella in the intestinal tract of mice, according to the researchers. The finding may help to explain why some people are better able to fight infection by Salmonella and other intestinal pathogens and lead to the development of better treatment strategies.

Salmonella bacteria cause about 1.2 million illnesses a year, but a new Stanford study identified a molecule that offers natural protection against the pathogen. 

Credit: Kateryna Kon/Shutterstock

A paper describing the work was published July 26 in Cell Host and Microbe.

The researchers determined that propionate doesn’t trigger the immune response to thwart the pathogen. Instead, the molecule prolongs the time it takes the pathogen to start dividing by increasing its internal acidity.

Salmonella infections often cause diarrhea, fever and abdominal cramps. Most people recover within four to seven days. However, the illness may be severe enough to require hospitalization for some patients. Salmonella causes about 1.2 million illnesses, 23,000 hospitalizations and 450 deaths nationwide each year, according to the Centers for Disease Control and Prevention. Most cases are caused by contaminated food.
Different responses to exposure

“Humans differ in their response to exposure to bacterial infections. Some people get infected and some don’t, some get sick and others stay healthy, and some spread the infection while others clear it,” said Denise Monack, PhD, professor of microbiology and immunology and the senior author of the paper. “It has been a real mystery to understand why we see these differences among people. Our finding may shed some light on this phenomenon.”

For years, scientists have been using different strains of mice to determine how various genes might influence susceptibility to infection by intestinal pathogens. But this is the first time that researchers have looked at how the variability of gut bacteria in these mice might contribute to their different responses to pathogens.

“The gut microbiota is an incredibly complex ecosystem. Trillions of bacteria, viruses and fungi form complex interactions with the host and each other in a densely packed, heterogeneous environment,” said Amanda Jacobson, the paper’s lead author and a graduate student in microbiology and immunology. “Because of this, it is very difficult to identify the unique molecules from specific bacteria in the gut that are responsible for specific characteristics like resistance to pathogens.”
From mice to men

The scientists started with an observation that has been recognized in the field for years: Two inbred strains of mice harbor different levels of Salmonella in their guts after being infected with the pathogen. “The biggest challenge was to determine why this was happening,” Jacobson said.

First, they determined that the differences in Salmonella growth could be attributed to the natural composition of bacteria in the intestines of each mouse strain. They did this by performing fecal transplants, which involved giving mice antibiotics to kill off their usual composition of gut bacteria and then replacing the microbial community with the feces of other mice, some of whom were resistant to Salmonella infection. Then, the researchers determined which microbes were responsible for increased resistance to Salmonella infection by using machine-learning tools to identify which groups of bacteria were different between the strains.

They identified a specific group of bacteria, the Bacteroides, which was more abundant in mice transplanted with the microbiota that was protective against Salmonella. Bacteroides produce short-chain fatty acids such as formate, acetate, butyrate and propionate during metabolism, and levels of propionate were threefold higher in mice that were protected against Salmonella growth. Then, the researchers sought to figure out whether propionate protected against Salmonella by boosting the immune system like other short-chain fatty acids do.

The scientists examined their Salmonella model for the potential impact of propionate on the immune system but found that the molecule had a more direct effect on the growth of Salmonella. Propionate acts on Salmonella by dramatically decreasing its intracellular pH and thus increasing the time it takes for the bacterium to start dividing and growing, the study found.

“Collectively, our results show that when concentrations of propionate, which is produced by Bacteroides, in the gut are high, Salmonella are unable to raise their internal pH to facilitate cellular functions required for growth,” Jacobson said. “Of course, we would want to know how translatable this is to humans.”
Reducing the impact of salmonella

“The next steps will include determining the basic biology of the small molecule propionate and how it works on a molecular level,” Jacobson said. In addition, the researchers will work to identify additional molecules made by intestinal microbes that affect the ability of bacterial pathogens like Salmonella to infect and “bloom” in the gut. They are also trying to determine how various diets affect the ability of these bacterial pathogens to infect and grow in the gut and then shed into the environment. “These findings will have a big impact on controlling disease transmission,” Monack said.

The findings could also influence treatment strategies. Treating Salmonella infections sometimes require the use of antibiotics, which may make Salmonella-induced illness or food poisoning worse since they also kill off the “good” bacteria that keep the intestine healthy, according to Monack. Using propionate to treat these infections could overcome this limitation. “Reducing the use of antibiotics is an added benefit because overuse of antibiotics leads to increased incidence of antibiotic-resistant microbes,” Monack said.

Other Stanford co-authors of the paper are postdoctoral scholar Manohary Rajendram, PhD; graduate students Lilian Lam, Fiona Tamburini, Will Van Treuren, Kali Pruss, Jared Honeycutt and Kyler Lugo; Trung Pham, MD, instructor of pediatrics and infectious diseases; life science researcher Russel Stabler; Donna Bouley, DVM, PhD, professor emeritus of comparative medicine; José Vilches-Moure, PhD, assistant professor of comparative medicine; senior research scientist Mark Smith, PhD; Justin Sonnenburg, PhD, associate professor of microbiology and immunology; Ami Bhatt, MD, PhD, assistant professor of medicine and of genetics; and KC Huang, PhD, associate professor of bioengineering and of microbiology and immunology.

Bhatt, Huang, Monack, Sonnenburg and Vilches-Moure are members of Stanford Bio-X. Bhatt, Huang, Monack and Sonnenburg are faculty fellows at Stanford ChEM-H. Bhatt, Bouley and Vilches-Moure are members of the Stanford Cancer Institute. Bhatt and Monack are members of the Stanford Child Health Research Institute. Vilches-Moure is a member of the Stanford Cardiovascular Institute. Bouley is an affiliate of the Stanford Woods Institute for the Environment. Sonnenburg and Huang are Chan Zuckerberg Biohub Investigators.

The study was funded by the National Institutes of Health (grants R01DK085025, T32GM007276, R01AI116059 and F32AI133917), the Paul Allen Stanford Discovery Center on Systems Modeling of Infection and the National Science Foundation.

Stanford’s Department of Microbiology and Immunology also supported the work.
Contacts and sources:
Kimber Price
Stanford Medicine

Citation: A Gut Commensal-Produced Metabolite Mediates Colonization Resistance to Salmonella Infection.
Amanda Jacobson, Lilian Lam, Manohary Rajendram, Fiona Tamburini, Jared Honeycutt, Trung Pham, Will Van Treuren, Kali Pruss, Stephen Russell Stabler, Kyler Lugo, Donna M. Bouley, Jose G. Vilches-Moure, Mark Smith, Justin L. Sonnenburg, Ami S. Bhatt, Kerwyn Casey Huang, Denise Monack. Cell Host & Microbe, 2018; DOI: 10.1016/j.chom.2018.07.002

Study Reveals Rewards and Perils of Kissing Up to the Boss

Kissing up to the boss at work may help boost employees’ careers but it also depletes the employees’ self-control resources, leaving them more susceptible to behaving badly in the workplace, a new study has found.

“There’s a personal cost to ingratiating yourself with your boss,” said Anthony Klotz, an associate professor of management in the College of Business at Oregon State University and the lead author of the paper. “When your energy is depleted, it may nudge you into slack-off territory.”

The findings were published recently in the Journal of Applied Psychology.

Ingratiation is just one of many behaviors employees use to create and maintain their desired image in the workplace. Past research has shown that successful use of these behaviors, known collectively as impression management tactics, can have benefits for employees, including stronger performance evaluations. 

File:Buzz Tweed.jpg
Credit:Buzz Tweed / Wikimedia Commons 
“Generally, impression management in the workplace is about wanting to be liked and appearing capable,” said co-author Lawrence Houston III, an assistant professor of management in OSU’s College of Business.

Klotz, Houston and their co-authors examined how 75 professionals in China used two supervisor-focused impression management tactics – ingratiation and self-promotion – over two work weeks.

Ingratiation, or kissing up, generally includes flattery, conforming with the supervisor’s opinion and doing favors. Self-promotion refers to taking credit for success, boasting about performance and highlighting connections to other important people.

The study participants – mid-level managers in a large, publicly traded software company – completed daily diary surveys of their workplace experiences and also took a survey measuring their political skill, which is the set of social abilities that helps them effectively understand others at work, influence others in ways that enhance their own objectives and navigate social situations with confidence.

The researchers found that the extent to which employees engaged in ingratiation varied widely from day to day. They also found that the more employees engaged in kissing up, the more their self-control resources were depleted by the end of the day.

It makes sense that ingratiation is depleting, because successfully kissing up requires the appearance of sincerity and that requires self-control, Klotz said.

The depleted employees were more likely to engage in workplace deviance such as incivility to a co-worker, skipping a meeting or surfing the internet rather than working. There was no evidence of a similar link between self-promotion and resource depletion, the researchers said.

“It’s also important to note that the depleting effects of ingratiation are immediate, but the workplace benefits of those acts tend to build over the long term,” Houston said.

The researchers also found that ingratiation was less depleting for employees with high levels of political skill. Those with relatively high political skill were less prone to engage in deviance after performing impression management than their peers lower in political skill, signaling that political skill can act as a buffer against the depleting effects of ingratiation.

The study’s findings suggest that employees should be mindful of the potential effects of ingratiation and the power of political skill in helping them manage appropriate and less-depleting ingratiation, Klotz said.

“Also, if you’re feeling depleted you may want to take steps to restore yourself – take a walk, talk to a friend, eat a snack,” he said. “That’s typically better than the allowing the depletion to manifest in other ways, like skipping a meeting or being rude to a co-worker.”

Workplace leaders should also be mindful that ingratiation comes at a cost to employees and their response to an employee’s action can play a role in determining what that cost is, Houston said.

“Leaders can respond to their employees’ ingratiation efforts in ways that are resource depleting or in ways that are more resource giving,” he said. “Positive reinforcement is resource giving, and it’s free.”

Contacts and sources:
Michelle Klampe
Oregon State University

Citation: Good actors but bad apples: Deviant consequences of daily impression management at work..
Anthony C. Klotz, Wei He, Kai Chi Yam, Mark C. Bolino, Wu Wei, Lawrence Houston. Journal of Applied Psychology, 2018; DOI: 10.1037/apl0000335

Overnight Brain Stimulation Improves Memory

New research in humans demonstrates the potential to improve memory with a non-invasive brain stimulation technique delivered during sleep. The results, published in JNeurosci, come from a project funded by the United States Department of Defense that aims to better understand the process of memory consolidation, which could translate into improved memory function in both healthy and patient populations.

Credit: Society for Neuroscience

The transfer of memories from the hippocampus to the neocortex for long-term storage is thought to be enabled by synchronization of these parts of the brain during sleep. Nicholas Ketz, Praveen Pilly, and colleagues at University of New Mexico sought to enhance this natural process of overnight reactivation or neural replay to improve memory with a closed-loop transcranial alternating current stimulation system matching the phase and frequency of ongoing slow-wave oscillations during sleep.

Participants were trained and tested on a realistic visual discrimination task in which they had to detect potentially threatening hidden objects and people such as explosive devices and enemy snipers. The researchers found that when participants received stimulation during overnight visits to their sleep laboratory, they showed improved performance in detecting targets in similar but novel situations the next day compared to when they did not receive the stimulation, suggesting an integration of recent experience into a more robust and general memory. 

Overnight memory changes correlated with stimulation-induced neural changes, which could be used to optimize stimulation in future applications. These findings provide a method for enhancing memory consolidation without disturbing sleep.

Contacts and sources:
Society for Neuroscience

Citation: Closed-loop slow-wave tACS improves sleep dependent long-term memory generalization by modulating endogenous oscillations.
Nicholas Ketz, Aaron Jones, Natalie Bryant, Vincent P. Clark, Praveen K. Pilly.The Journal of Neuroscience, 2018; 0273-18 DOI: 10.1523/JNEUROSCI.0273-18.2018

Cells Phone Robbing Adolescents of Memory Claims New Study

Radiofrequency electromagnetic fields may have adverse effects on the development of memory performance of specific brain regions exposed during mobile phone use. These are the findings of a study involving nearly 700 adolescents in Switzerland.

 The investigation, led by the Swiss Tropical and Public Health Institute (Swiss TPH), were published on Monday, 23 July 2018 in the peer-reviewed journal Environmental Health Perspectives.

This study looked at the relationship between exposure to mobile phone radiation and development of memory performance in adolescents

The rapid evolution of information and communication technologies (ICT) goes along with an increase in exposure to radiofrequency electromagnetic fields (RF-EMF) in our daily life. The most relevant exposure source to the brain is the use of a mobile phone close to the head. Several studies have been conducted to identify potential health effects related to RF-EMF, though results have remained inconclusive.

Credit: Swiss Tropical and Public Health Institute

The research conducted by scientists at the Swiss Tropical and Public Health Institute (Swiss TPH) looked at the relationship between exposure to RF-EMF from wireless communication devices and memory performance in adolescents. The study follows up a report published in the scientific journal Environment International in 2015 with twice the sample size and more recent information on the absorption of RF-EMF in adolescent brains during different types of wireless communication device use. These are the world’s first epidemiological studies to estimate cumulative RF-EMF brain dose in adolescents.

Media usage and brain exposure in young adults

The study to be published on 23 July 2018 found that cumulative RF-EMF brain exposure from mobile phone use over one year may have a negative effect on the development of figural memory performance in adolescents, confirming prior results published in 2015. Figural memory is mainly located in the right brain hemisphere and association with RF-EMF was more pronounced in adolescents using the mobile phone on the right side of the head. “This may suggest that indeed RF-EMF absorbed by the brain is responsible for the observed associations.” said Martin Röösli, Head of Environmental Exposures and Health at Swiss TPH.

Other aspects of wireless communication use, such as sending text messages, playing games or browsing the Internet cause only marginal RF-EMF exposure to the brain and were not associated with the development of memory performance. “A unique feature of this study is the use of objectively collected mobile phone user data from mobile phone operators.” said Röösli. He emphasised that further research is needed to rule out the influence of other factors. “For instance, the study results could have been affected by puberty, which affects both mobile phone use and the participant’s cognitive and behavioural state.”

The data gathered from the Health Effects Related to Mobile phone usE in adolescentS (HERMES) cohort looked at the relationship between exposure to RF-EMF and development of memory performance of almost 700 adolescents over the course of one year. Participants, aged 12 to 17 years, were recruited from 7th to 9th public school grades in urban and rural areas of Swiss-German speaking Switzerland.

Minimising the risk of RF-EMF exposure

The potential effect of RF-EMF exposure to the brain is a relatively new field of scientific inquiry. “It is not yet clear how RF-EMF could potentially affect brain processes or how relevant our findings are in the long-term.” said Röösli. “Potential risks to the brain can be minimised by using headphones or the loud speaker while calling, in particular when network quality is low and the mobile phone is functioning at maximum power.”

About the publication

The study was conducted by Swiss TPH in collaboration with the European Union project GERoNiMO, which aims to improve the knowledge of whether and to what extent RF-EMF affects health. The work on dose calculations was conducted in collaboration with Belgian scientists. The project was funded by the European Community’s Seventh Framework Programme and the Swiss National Science Foundation (SNSF).

Contacts and sources:
Martin Röösli
Swiss Tropical and Public Health Institute


    A prospective cohort study of adolescents' memory performance and individual brain dose of microwave radiation from wireless communication.
    Foerster M., Thielens A., Joseph W., Eeftens M., Röösli M. Environmental Health Perspectives, 2018 DOI: 10.1289/EHP2427

    Memory performance, wireless communication and exposure to radiofrequency electromagnetic fields: A prospective cohort study in adolescents. Anna Schoeni, Katharina Roser, Martin Röösli.Environment Internation
  1. al, 2015; 85: 343 DOI: 10.1016/j.envint.2015.09.025

Scientists Reverse Aging-Associated Skin Wrinkles and Hair Loss

Wrinkled skin and hair loss are hallmarks of aging. What if they could be reversed?

Keshav Singh, Ph.D., and colleagues have done just that, in a mouse model developed at the University of Alabama at Birmingham. When a mutation leading to mitochondrial dysfunction is induced, the mouse develops wrinkled skin and extensive, visible hair loss in a matter of weeks. When the mitochondrial function is restored by turning off the gene responsible for mitochondrial dysfunction, the mouse returns to smooth skin and thick fur, indistinguishable from a healthy mouse of the same age.

“To our knowledge, this observation is unprecedented,” said Singh, a professor of genetics in the UAB School of Medicine.

Importantly, the mutation that does this is in a nuclear gene affecting mitochondrial function, the tiny organelles known as the powerhouses of the cells. Numerous mitochondria in cells produce 90 percent of the chemical energy cells need to survive.

In humans, a decline in mitochondrial function is seen during aging, and mitochondrial dysfunction can drive age-related diseases. A depletion of the DNA in mitochondria is also implicated in human mitochondrial diseases, cardiovascular disease, diabetes, age-associated neurological disorders and cancer.

“This mouse model,” Singh said, “should provide an unprecedented opportunity for the development of preventive and therapeutic drug development strategies to augment the mitochondrial functions for the treatment of aging-associated skin and hair pathology and other human diseases in which mitochondrial dysfunction plays a significant role.”

The mutation in the mouse model is induced when the antibiotic doxycycline is added to the food or drinking water. This causes depletion of mitochondrial DNA because the enzyme to replicate the DNA becomes inactive.

In four weeks, the mice showed gray hair, reduced hair density, hair loss, slowed movements and lethargy, changes that are reminiscent of natural aging. Wrinkled skin was seen four to eight weeks after induction of the mutation, and females had more severe skin wrinkles than males.

Dramatically, this hair loss and wrinkled skin could be reversed by turning off the mutation. The photos below show the hair loss and wrinkled skin after two months of doxycycline induction, and the same mouse a month later after doxycycline was stopped, allowing restoration of the depleted mitochondrial DNA.

Little change was seen in other organs when the mutation was induced, suggesting an important role for mitochondria in skin compared to other tissues.

These photos show the hair loss and wrinkled skin after two months of doxycycline induction, and the same mouse a month later after doxycycline was stopped, allowing restoration of the depleted mitochondrial DNA.The wrinkled skin showed changes similar to those seen in both intrinsic and extrinsic aging — intrinsic aging is the natural process of aging, and extrinsic aging is the effect of external factors that influence aging, such as skin wrinkles that develop from excess sun or long-term smoking.

Credit: UAB

Among the details, the skin of induced-mutation mice showed increased numbers of skin cells, abnormal thickening of the outer layer, dysfunctional hair follicles and increased inflammation that appeared to contribute to skin pathology. These are similar to extrinsic aging of the skin in humans. The mice with depleted mitochondrial DNA also showed changed expression of four aging-associated markers in cells, similar to intrinsic aging.

The skin also showed disruption in the balance between matrix metalloproteinase enzymes and their tissue-specific inhibitor — a balance of these two is necessary to maintain the collagen fibers in the skin that prevent wrinkling.

The mitochondria of induced-mutation mice had reduced mitochondrial DNA content, altered mitochondrial gene expression, and instability of the large complexes in mitochondria that are involved in oxidative phosphorylation.

Reversal of the mutation restored mitochondrial function, as well as the skin and hair pathology. This showed that mitochondria are reversible regulators of skin aging and loss of hair, an observation that Singh calls “surprising.”

“It suggests that epigenetic mechanisms underlying mitochondria-to-nucleus cross-talk must play an important role in the restoration of normal skin and hair phenotype,” Singh said, who has a secondary UAB appointment as professor of pathology. “Further experiments are required to determine whether phenotypic changes in other organs can also be reversed to wildtype level by restoration of mitochondrial DNA.”

Co-authors with Singh for the paper, “Reversing wrinkled skin and hair loss in mice by restoring mitochondrial function,” published in the Cell Death and Disease, a Nature online journal, are Bhupendra Singh, Trenton R. Schoeb and Prachi Bajpai, UAB Department of Genetics; and Andrzej Slominski, UAB Department of Dermatology.

This work was supported by Veterans Administration grant 1I01BX001716 and National Institutes of Health grants CA204430, AR071189-01A1 and AR073004.

At UAB, Singh holds the Joy and Bill Harbert Endowed Chair in Cancer Genetics, and Slominski holds the Endowed Professorship in Basic Research in the Department of Dermatology.

Contacts and sources:
Jeff Hansen
University of Alabama at Birmingham


Artificial Intelligence Predicts Your by Tracking Your Eyes

It’s often been said that the eyes are the window to the soul, revealing what we think and how we feel. Now, new research reveals that your eyes may also be an indicator of your personality type, simply by the way they move.

Developed by the University of South Australia in partnership with the University of Stuttgart, Flinders University and the Max Planck Institute for Informatics in Germany, the research uses state-of-the-art machine-learning algorithms to demonstrate a link between personality and eye movements.

Findings show that people’s eye movements reveal whether they are sociable, conscientious or curious, with the algorithm software reliably recognising four of the Big Five personality traits: neuroticism, extroversion, agreeableness, and conscientiousness.

Credit:  University of South Australia

Researchers tracked the eye movements of 42 participants as they undertook everyday tasks around a university campus, and subsequently assessed their personality traits using well-established questionnaires.

UniSA’s Dr Tobias Loetscher says the study provides new links between previously under-investigated eye movements and personality traits and delivers important insights for emerging fields of social signal processing and social robotics.

“There’s certainly the potential for these findings to improve human-machine interactions,” Dr Loetscher says.

“People are always looking for improved, personalised services. However, today’s robots and computers are not socially aware, so they cannot adapt to non-verbal cues.

“This research provides opportunities to develop robots and computers so that they can become more natural, and better at interpreting human social signals.”

Dr Loetscher says the findings also provide an important bridge between tightly controlled laboratory studies and the study of natural eye movements in real-world environments.

“This research has tracked and measured the visual behaviour of people going about their everyday tasks, providing more natural responses than if they were in a lab.

“And thanks to our machine-learning approach, we not only validate the role of personality in explaining eye movement in everyday life, but also reveal new eye movement characteristics as predictors of personality traits.”

Contacts and sources:\
Dr Tobias Loetscher / Annabel Mansfield
University of South Australia

Citation: Eye Movements During Everyday Behavior Predict Personality Traits
Sabrina Hoppe, Tobias Loetscher, Stephanie A. Morey, Andreas Bulling.. Frontiers in Human Neuroscience, 2018; 12 DOI: 10.3389/fnhum.2018.00105

Never-Before-Seen Matter Around Black Hole Revealed

The black hole in Cygnus X-1 is one of the brightest sources of X-rays in the sky. The light near the black hole comes from matter siphoned off its companion star. 
Image: NASA, ESA, Martin Kornmesser

In an international collaboration between Japan and Sweden, scientists clarified how gravity affects the shape of matter near the black hole in binary system Cygnus X-1. Their findings, which were published in Nature Astronomy this month, may help scientists further understand the physics of strong gravity and the evolution of black holes and galaxies.

Near the center of the constellation of Cygnus is a star orbiting the first black hole discovered in the universe. Together, they form a binary system known as Cygnus X-1. This black hole is also one of the brightest sources of X-rays in the sky. However, the geometry of matter that gives rise to this light was uncertain. The research team revealed this information from a new technique called X-ray polarimetry.

Taking a picture of a black hole is not easy. For one thing, it is not yet possible to observe a black hole because light cannot escape it. Rather, instead of observing the black hole itself, scientists can observe light coming from matter close to the black hole. In the case of Cygnus X-1, this matter comes from the star that closely orbits the black hole.

Polarization filters light so that it vibrates in one direction.

Image: Masako Hayashi, CORE-U, Hiroshima University

Most light that we see, like from the sun, vibrates in many directions. Polarization filters light so that it vibrates in one direction. It is how snow goggles with polarized lenses let skiers see more easily where they are going down the mountain – they work because the filter cuts light reflecting off of the snow.

“It’s the same situation with hard X-rays around a black hole,” Hiroshima University Assistant Professor and study coauthor Hiromitsu Takahashi said. “However, hard X-rays and gamma rays coming from near the black hole penetrate this filter. There are no such ‘goggles’ for these rays, so we need another special kind of treatment to direct and measure this scattering of light.”

The team needed to figure out where the light was coming from and where it scattered. In order to make both of these measurements, they launched an X-ray polarimeter on a balloon called PoGO+. From there, the team could piece together what fraction of hard X-rays reflected off the accretion disk and identify the matter shape.

The PoGO+ satellite and research team. Takahashi is standing sixth from the right.

 Photo: Hiromitsu Takahashi

Two competing models describe how matter near a black hole can look in a binary system such as Cygnus X-1: the lamp-post and extended model. In the lamp-post model, the corona is compact and bound closely to the black hole. Photons bend toward the accretion disk, resulting in more reflected light. In the extended model, the corona is larger and spread around the vicinity of the black hole. In this case, the reflected light by the disk is weaker.

Since light did not bend that much under the strong gravity of the black hole, the team concluded that the black hole fit the extended corona model.

With this information, the researchers can uncover more characteristics about black holes. One example is its spin. The effects of spin can modify the space-time surrounding the black hole. Spin could also provide clues into the evolution of the black hole. It could be slowing down in speed since the beginning of the universe, or it could be accumulating matter and spinning faster.

A representation of two competing black hole models: lamp-post and extended. The black dot is the black hole, blue is its accretion disk, and red is the corona.
 Image: Fumiya Imazato, Hiroshima University

“The black hole in Cygnus is one of many,” Takahashi said. “We would like to study more black holes using X-ray polarimetry, like those closer to the center of galaxies. Maybe we better understand black hole evolution, as well as galaxy evolution.”

Contacts and sources:
Hiroshima University

Citation: Accretion geometry of the black-hole binary Cygnus X-1 from X-ray polarimetry.
M. Chauvin, H.-G. Florén, M. Friis, M. Jackson, T. Kamae, J. Kataoka, T. Kawano, M. Kiss, V. Mikhalev, T. Mizuno, N. Ohashi, T. Stana, H. Tajima, H. Takahashi, N. Uchida, M. Pearce. Nature Astronomy, 2018; 2 (8): 652 DOI: 10.1038/s41550-018-0489-x

First-ever Movie of Cosmic Explosion: Enduring ‘Radio Rebound’ Powered by Jets from Gamma-Ray Burst

Astronomers using ALMA studied a cataclysmic stellar explosion known as a gamma-ray burst  or GRB, and found its enduring “afterglow.” The rebound, or reverse shock, triggered by the GRB’s powerful jets slamming into surrounding debris, lasted thousands of times longer than expected. These observations provide fresh insights into the physics of GRBs, one of the universe’s most energetic explosions.

Artist impression of the "reverse shock" echoing back through the jets of the gamma-ray burst (GRB 161219B).
Credit: NRAO/AUI/NSF, S. Dagnello

In the blink of an eye, a massive star more than 2 billion light-years away lost a million-year-long fight against gravity and collapsed, triggering a supernova  and forming a black hole  at its center.

This newborn black hole belched a fleeting yet astonishingly intense flash of gamma rays  known as a gamma-ray burst (GRB) toward Earth, where it was detected by NASA’s Neil Gehrels Swift Observatory on 19 December 2016.

While the gamma rays from the burst disappeared from view a scant seven seconds later, longer wavelengths of light from the explosion — including X-ray, visible light, and radio — continued to shine for weeks. This allowed astronomers to study the aftermath of this fantastically energetic event, known as GRB 161219B, with many ground-based observatories, including the National Science Foundation’s Very Large Array.

The unique capabilities of the Atacama Large Millimeter/submillimeter Array (ALMA), however, enabled a team of astronomers to make an extended study of this explosion at millimeter wavelengths, gaining new insights into this particular GRB and the size and composition of its powerful jets.

ALMA's time-lapse movie showing the "afterglow" of a powerful gamma-ray burst. These images of the millimeter-wavelength light reveal details about the energy in the GRB's jets.

Credit: ALMA (ESO/NAOJ/NRAO), T. Laskar; NRAO/AUI/NSF, S. Dagnello

“Since ALMA sees in millimeter-wavelength light, which carries information on how the jets interact with the surrounding dust and gas, it is a powerful probe of these violent cosmic explosions,” said Tanmoy Laskar, an astronomer at the University of California, Berkeley, and a Jansky Postdoctoral Fellow of the National Radio Astronomy Observatory. Laskar is lead author of the study, which appears in the Astrophysical Journal.

These observations enabled the astronomers to produce ALMA’s first-ever time-lapse movie of a cosmic explosion, which revealed a surprisingly long-lasting reverse shockwave from the explosion echoing back through the jets. “With our current understanding of GRBs, we would normally expect a reverse shock to last only a few seconds. This one lasted a good portion of an entire day,” Laskar said.

A reverse shock occurs when material blasted away from a GRB by its jets runs into the surrounding gas. This encounter slows down the escaping material, sending a shockwave back down the jet.

Since jets are expected to last no more than a few seconds, a reverse shock should be an equally short-lived event. But that now appears not to be the case.

“For decades, astronomers thought this reverse shock would produce a bright flash of visible light, which has so far been really hard to find despite careful searches. Our ALMA observations show that we may have been looking in the wrong place, and that millimeter observations are our best hope of catching these cosmic fireworks,” said Carole Mundell of the University of Bath, and co-author of the study.

Artist animation of a star exploding into a supernova and fueling a gamma-ray burst. Astronomers caught the enduring "afterglow" of one of these cataclysmic explosions with both ALMA and the VLA for the first time. The rebound, or reverse shock, triggered by the GRB’s powerful jets slamming into surrounding debris, lasted thousands of times longer than expected, giving astronomers an unprecedented glimpse into the structure and dynamics of the jets.

Credit: NRAO/AUI/NSF; S. Dagnello

Instead, the light from the reverse shock shines most brightly at the millimeter wavelengths on timescales of about a day, which is most likely why it has been so difficult to detect previously. While the early millimeter light was created by the reverse shock, the X-ray and visible light came from the blast-wave shock riding ahead of the jet.

“What was unique about this event,” Laskar adds, “is that as the reverse shock entered the jet, it slowly but continuously transferred the jet’s energy into the forward-moving blast wave, causing the X-ray and visible light to fade much slower than expected. Astronomers have always puzzled where this extra energy in the blast wave comes from. Thanks to ALMA, we know this energy – up to 85 percent of the total in the case of GRB 161219B – is hidden in slow-moving material within the jet itself.”

The bright reverse shock emission faded away within a week. The blast wave then shone through in the millimeter band, giving ALMA a chance to study the geometry of the jet.

The visible light from the blast wave at this critical time, when the outflow has slowed just enough for all of the jet to become visible at Earth, was overshadowed by the emerging supernova from the exploded star. But ALMA’s observations, unencumbered by supernova light, enabled the astronomers to constrain the opening angle of the outflow from the jet to about 13 degrees.

Understanding the shape and duration of the outflow from the star is essential for determining the true energy of the burst. In this case, the astronomers find the jets contained as much energy as our Sun puts out in a billion years.

“This is a fantastical amount of energy, but it is actually one of the least energetic events we have ever seen. Why this is so remains a mystery,” says Kate Alexander, a graduate student at Harvard University who led the VLA observations reported in this study. “Though more than two billion light-years away, this GRB is actually the nearest such event for which we have measured the detailed properties of the outflow, thanks to the combined power of ALMA and the VLA.”

The VLA, which observes at longer wavelengths, continued observing the radio emission from the reverse shock after it faded from ALMA’s view.

This is only the fourth gamma-ray burst with a convincing, multi-frequency detection of a reverse shock, the researchers note. The material around the collapsing star was about 3,000 times less dense than the average density of gas in our galaxy, and these new ALMA observations suggest that such low-density environments are essential for producing reverse shock emission, which may explain why such signatures are so rare.

“Our rapid-response observations highlight the key role ALMA can play in following up transients, revealing the energy source that powers them, and using them to map the physics of the Universe to the dawn of the first stars,” concludes Laskar. “In particular, our study demonstrates that ALMA’s superb sensitivity and new rapid-response capabilities makes it the only facility that can routinely detect reverse shocks, allowing us to probe the nature of the relativistic jets in these energetic transients, and the engines that launch and feed them.”

Contacts and sources:
Charles Blue
National Radio Astronomy Observatory

Citation:  First ALMA Light Curve Constrains Refreshed Reverse Shocks & Jets Magnetization in GRB
T. Laskar et al. 161219B. Astrophysical Journal, 2018

Researchers Discover Thin Gap On Stellar Family Portrait

A thin gap has been discovered on the Hertzsprung-Russell Diagram (HRD), the most fundamental of all maps in stellar astronomy, a finding that provides new information about the interior structures of low mass stars in the Milky Way Galaxy, according to a study led by astronomers at Georgia State University.

Just as a graph can be made of people with different heights and weights, astronomers compare stars using their luminosities and temperatures. The HRD is a “family portrait” of the stars in the Galaxy, where stars such as the Sun, Altair, Alpha Centauri, Betelgeuse, the north star Polaris and Sirius can be compared.The newly discovered gap cuts diagonally across the HRD and indicates where a crucial internal change occurs in the structures of stars. The gap outlines where stars transition from being larger and mostly convective with a thin radiative layer to being smaller and fully convective.

ESA Gaia mission has made the richest star map of our galaxy yet

Credit: ESA/Gaia/DPAC

Radiation and convection are two ways to transfer energy from inside a star to its surface. Radiation transfers energy through space, and convection is the transfer of energy from one place to another by the movement of fluid.

The researchers estimate that stars above the gap contain more than about one-third the mass of the Sun, and those below have less mass. Because different types of stars have different masses, this feature reveals where different types of interior structures are on the HRD. The gap occurs in the middle of the region of “red dwarf” stars, which are much smaller and cooler than the Sun, but compose three of every four stars in the solar neighborhood. The findings are published in the journal The Astrophysical Journal Letters.

“We were pretty excited to see this result, and it provides us new insights to the structures and evolution of stars,” said Dr. Wei-Chun Jao, first author of the study and a staff astronomer in the Department of Physics and Astronomy at Georgia State.

In 2013, the European Space Agency (ESA) launched the Gaia spacecraft to make a census of the stars in the Milky Way Galaxy and to create a three-dimensional map. In April 2018, the ESA released results of this mission, revealing an unprecedented map of more than one billion stars in the Galaxy, a 10,000-fold increase in the number of stars with accurate distances. The research team led by Georgia State plotted nearly 250,000 of the closest stars in the Gaia data on the HRDto reveal the gap. Georgia State’s researchers have studied the distances to nearby stars for years, which enabled them to interpret the results and notice this thin gap.

The team is now working to pinpoint why the gap is present. Using results from a theoretical computer model that simulates the activity inside the stars, it appears the gap is caused by a slight shrinking in size if a star is convective all the way through.

Co-authors of the study include Drs. Todd Henry and Douglas Gies of Georgia State and Dr. Nigel Hambly of the University of Edinburgh, Royal Observatory.

The study is funded by the National Science Foundation.

Contacts and sources:
LaTina Emerson
Georgia State University

Citation: A Gap in the Lower Main Sequence Revealed by Gaia Data Release 2.
Wei-Chun Jao, Todd J. Henry, Douglas R. Gies, Nigel C. Hambly. The Astrophysical Journal, 2018; 861 (1): L11 DOI: 10.3847/2041-8213/aacdf6

Saturday, July 28, 2018

Where to Find Dying Massive Stars and Black Holes

Findings from a Rochester Institute of Technology study provide further evidence that the outskirts of spiral galaxies host massive black holes. These overlooked regions are new places to observe gravitational waves created when the massive bodies collide, the authors report.

The study winds back time on massive black holes by analyzing their visible precursors—supernovae with collapsing cores. The slow decay of these massive stars creates bright signatures in the electromagnetic spectrum before stellar evolution ends in black holes.

Using data from the Lick Observatory Supernova Search, a survey of nearby galaxies, the team compared the supernovae rate in outer spiral galaxies with that of known hosts—dwarf/satellite galaxies—and found comparable numbers for typical spiral outskirts and typical dwarf galaxies, roughly two core-collapse supernovae per millennium.

This Chandra X-ray photograph shows Cassiopeia A, the youngest supernova remnant in the Milky Way.

NASA/CXC/MIT/UMass Amherst/M.D.Stage et al.

The study, “Supernova Rate beyond the Optical Radius,” will appear in an upcoming issue of Astrophysical Journal Letters.

Low levels of elements heavier than hydrogen and helium found in dwarf/satellite galaxies create favorable conditions for massive black holes to form and create binary pairs. A similar galactic environment in the outer disks of spiral galaxies also creates likely hunting grounds for massive black holes, said Sukanya Chakrabarti, lead author and assistant professor in the RIT School of Physics and Astronomy.

“If these core-collapse supernovae are the predecessors to the binary black holes detected by LIGO (Laser Interferometer Gravitational-wave Observatory), then what we’ve found is a reliable method of identifying the host galaxies of LIGO sources,” said Chakrabarti. “Because these black holes have an electromagnetic counterpart at an earlier stage in their life, we can pinpoint their location in the sky and watch for massive black holes.”

The study’s findings complement Chakrabarti's 2017 study, which showed that the outer parts of spiral galaxies could contribute to LIGO detection rates. The regions form stars at a comparable rate to dwarf galaxies and are low in heavy element content, creating a conducive home for massive black holes. The current study isolates potential candidates within these favorable galactic environments.

“We see now that these are both important contributors,” Chakrabarti said. “The next step is to do deeper surveys to see if we can improve the rate.”

Co-author Brennan Dell, a recent graduate from RIT’s computer science program, analyzed the data with Chakrabarti during his undergraduate co-op.

“This work may help us determine which galaxies to be on the lookout for electromagnetic counterparts of massive black holes,” Dell said.

NASA and National Science Foundation awards funded Chakrabarti’s study and contributions from co-authors Dell and Benjamin Lewis at RIT’s Center for Computational Relativity and Gravitation; additional co-authors include Or Graur from Harvard-Smithsonian Center for Astrophysics; Alexei Filippenko at University of California, Berkeley, who leads the Lick Observatory Supernova Search; and Christopher McKee at the University of California, Berkeley

Contacts and sources:
Susan Gawlowicz
Rochester Institute of Technology

Citation: The supernova rate beyond the optical radius.
Sukanya Chakrabarti, Brennan Dell, Or Graur, Alexei Filippenko, Benjamin Lewis, Christopher McKee. Astrophysical Journal Letters, 2018 http://export.arxiv.org/abs/1807.07585

New Study Shows Ocean Acidification Is Having Major Impact on Marine Life

Carbon dioxide emissions are killing off coral reefs and kelp forests as heat waves and ocean acidification damage marine ecosystems, scientists have warned.

Writing in Scientific Reports, researchers say that three centuries of industrial development have already had a marked effect on our seas.

But if CO2 levels continue to rise as predicted, the coming decades and lowering seawater pH levels will have an even greater and potentially catastrophic impact.

Their predictions follow a comprehensive study of the effects of recently discovered volcanic CO2 seeps off Shikine Island, Japan, which is on the border of temperate and tropical climates.

Corals, such as this table Acroporid, provide habitats for a wide range of fauna 
<p>A scuba diver carries out investigations along underwater CO2 gradients created by volcanic seeps

Credit: Marco Milazzo

Ocean currents in the area mean there are naturally low levels of surface water CO2, similar to those that would have been present before the global Industrial Revolution.

However, the volcanic seeps indicate how rising CO2 levels will affect future ecology, both in the northwest Pacific Ocean and across the world.

Lead author Dr Sylvain Agostini, Associate Professor at the University of Tsukuba Shimoda Marine Research Centre, said:“These CO2 seeps provide a vital window into the future. There was mass mortality of corals in the south of Japan last year, but many people cling to the hope that corals will be able to spread north. Therefore it is extremely worrying to find that tropical corals are so vulnerable to ocean acidification, as this will stop them from being able to spread further north and escape the damage caused by water that is too hot for them.”

The research was led by scientists at the University of Tsukuba in Japan, the University of Plymouth in the UK and the University of Palermo in Italy.

It involved teams of scuba divers who carried out investigations along underwater CO2 gradients created by volcanic seeps, recording how the fauna and flora respond to seawater acidification.

They found that while a few plant species benefitted from the changing conditions, they tended to be smaller weeds and algae that blanket the seabed, choking corals and lowering overall marine diversity.

These species, and some smaller marine animals, are thriving because they are more tolerant to the stress posed by rising levels of CO2.

Jason Hall-Spencer, Professor of Marine Biology at the University of Plymouth, said:“O  impressive amount of calcified organisms such as corals and oysters. But in areas with present-day average levels of surface seawater CO2 we found far fewer corals and other calcified life, and so there was less biodiversity. It shows the extensive damage caused by humans due to CO2 emissions over the past 300 years and unless we can get a grip on reducing CO2 emissions we will undoubtedly see major degradation of coastal systems worldwide.”

Professor Kazuo Inaba, former director of the Shimoda Marine Research Centre, added: “Local fishermen are keen to know how ocean acidification will affect their livelihoods. Currents flowing past Japan bring waters that have naturally low levels of CO2 and fish benefit from the array of calcified habitats around our islands. If we are able to meet the Paris Agreement targets to limit emissions we should be able to limit further damage to kelp forests, coral reefs and all marine ecosystems.”

The full study – Ocean acidification drives community shifts towards simplified non-calcified habitats in a subtropical-temperate transition zone by Agostini, Harvey, Wada, Kon, Milazzo, Inaba and Hall-Spencer – is published in Scientific Reports, doi: 10.1038/s41598-018-29251-7.

Contacts and sources:
Alan Williams
University of Plymouth

Citation: Ocean acidification drives community shifts towards simplified non-calcified habitats in a subtropical−temperate transition zone
Sylvain Agostini, Ben P. Harvey, Shigeki Wada, Koetsu Kon, Marco Milazzo, Kazuo Inaba, Jason M. Hall-Spencer. . Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-018-29251-7