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Sunday, April 23, 2017

Tarantulas Use Their Lateral Eyes to Calculate Distance

A necessary part of any animal's sense of direction is a positioning system, allowing it to have an idea of the relation between where it is and where it wants to go; this is known as odometry. A study from the Autonomous University of Madrid shows that tarantulas use their posterior lateral eyes and anterior lateral eyes (they have a total of four pairs of eyes) to establish the distance they have travelled.

The tarantula species Lycosa tarantula ambushes its prey and lives in burrows around 20 cm deep topped by a structure, a kind of turret which the tarantula build from twigs, leaves and small stones, fastened with the spider's silk. From the turret, the tarantula surprises its prey and runs to pursue it, subsequently returning to the burrow from distances between 30 and 40 cm.
Photos: Joaquín Ortega Escobar

L. tarantula uses path integration to return to its burrow. With this mechanism, it does not follow the same path back to its burrow; instead, it moves as though it had followed the sides of a right-angle triangle, returning along the hypotenuse.

In 1999, a research team from the Autonomous University of Madrid discovered that these animals used polarised light from the sky to know their position with respect to their nest. In the new research, the scientists wanted to go beyond this, and have analysed the role of each pair of the tarantula's eyes (they have four pairs in total) in the process of distance measurement, or odometry.

"To calculate the distance it has travelled, the animal needs an odometer that registers the route, its location with respect to the finish point, which would be the burrow, and a 'compass' to track the direction of travel," SINC was told by Joaquin Ortega Escobar, lead author of a paper published in the 'Journal of Experimental Biology' on the function of each eye in these processes.

The 'compass' would correspond to polarised light, which the median eyes use to measure the angle; direction is detected by the anterior lateral eyes. Through this research, the scientists have learned that it is principally the anterior lateral eyes (which until now had not been analysed), and to a lesser extent the posterior lateral eyes, that help tarantulas measures the distance to their nest.

Orientation with covered eyes

"These eyes look at the substrate. Seeing as they point downwards, it seems logical to think they would have a role in measuring the distance travelled. In the experiment, we covered these eyes with a water-soluble paint and observed that instead of travelling 30 cm from the nest, which is the distance we initially set, they stopped 8.5 centimetres before they reached their objective," explains the researcher.


Photos: Joaquín Ortega Escobar

This explains that with those eyes covered and the other six active, they have problems determining distance. "When we uncovered them, they could return to their nests perfectly. They need the lateral anterior eyes to measure the distance," he adds.

In previous work with the lateral eyes of other animals, such as desert ants (Cataglyphis fortis), the researchers observed that animals moving across a grid of black and white bands, like those used in the tarantula study, with the ventral region of their compound eyes (the part that perceives the grid) covered did not present a significant difference in the return trip to the nest compared to when the eyes were uncovered.

"The situations of these two animals are analogous. In the case of the spider, it is the anterior lateral eye that perceives the ventral field of view, while in the ant it is the ventral region of the compound eye. Spiders have simple eyes like our own, rather than compound eyes," Ortega Escobar explains.

Through this research, the scientists also observed that the tarantulas do not move their front two legs when their eyes are covered. "This movement had been observed in another species, C. salei, under complete darkness. The movement was due to the absence of light, not because its eyes were covered, which would not necessarily be the same. We do not know why it does this when the posterior median eyes or anterior lateral eyes are covered and not the posterior lateral eyes," concludes Ortega Escobar.


Contacts and sources:
Plataforma SINC

Citation: Joaquin Ortega-Escobar y Miguel A. Ruiz. "Role of the different eyes in the visual odometry in the wolf spider Lycosa tarantula (Araneae, Lycosidae)". Journal of Experimental Biology (2017) 220, 259-265 doi:10.1242/jeb.145763

Will Earth Like Planets Have Oceans Like Earth

For a planetary surface to boast extensive areas of both land and water, a delicate balance must be struck between the volume of water it retains and the capacity of its oceanic basins. Each of these two quantities may vary substantially across the full spectrum of water-bearing worlds.

Why the Earth's values are so well balanced is an unresolved and long-standing conundrum. In a paper published in the Monthly Notices of the Royal Astronomical Society (Ed. Oxford University Press) the author, Fergus Simpson of the Institute of Cosmos Science at the University of Barcelona, has constructed a statistical model - based on Bayesian probability - to predict the division between land and water on habitable exoplanets.

In the paper the author, Fergus Simpson of the ICCUB, has constructed a statistical model to predict the division between land and water on habitable exoplanets.
Credit: © Antartis / Depositphotos.com

This model predicts that most habitable planets are dominated by oceans spanning over 90% of their surface area (95% credible interval). This conclusion is reached because the Earth is in close proximity to the waterworld limit, a regime where the existence of our species would no longer be viable. "A scenario in which the Earth has less water than most other habitable planets would be consistent with results from simulations, and could help explain why some planets have been found to be a bit less dense than we expected" explains Simpson.


In this paper, the ICCUB researcher finds that the Earth's finely balanced oceans may be a consequence of the anthropic principle - more often used in a cosmological context - which accounts for how our observations of the Universe are influenced by the requirement for the formation of conscious life. "Based on the Earth's ocean coverage of 71%, we find substantial evidence supporting the hypothesis that anthropic selection effects are at work" explains Simpson.

To test the statistical model the ICCUB researcher has also taken some feedback mechanisms into account such as the deep water cycle or the erosion and deposition processes. Also, he proposed a statistical approximation to determine the diminishing habitable land area for planets with smaller oceans, as they become increasingly dominated by deserts.

In this study Simpson focuses on the selection effect involving a planet's ocean coverage. "Our understanding of the development of life may be far from complete, but it is not so dire that we must adhere to the conventional approximation that all habitable planets have an equal chance of hosting intelligent life", Simpson concludes.

Animation: showing how the Earth would appear as the amount of water in its oceans increases. Only a narrow window exists in which large areas of both land and water are present. Credit: F. Simpson


Contacts and sources:
 University of Barcelona

 Citation: Fergus Simpson. ‘Bayesian evidence for the prevalence of waterworlds’. Monthly Notices of the Royal Astronomical Society, April 2017. Doi: http://doi.org/10.1093/mnras/stx516

3D-Printing of Glass Now Possible

Three-dimensional printing allows extremely small and complex structures to be made even in small series. A method developed at the Karlsruhe Institute of Technology (KIT) for the first time allows also glass to be used for this technique.

As a consequence of the properties of glass, such as transparency, thermal stability and resistance to acids, the use of this material in 3D-printing opens up manifold new applications in production and research, such as optics, data transmission, and biotechnology. The process is published in “Nature” and also presented at the Hanover Fair.

Complicated high-precision structures made of glass can be manufactured in a 3D-printing process developed at the KIT.
Photos: KIT

Glass is one of mankind’s oldest materials. It was used as far back as in ancient Egypt and ancient Rome and has found a place now also in manufacturing technology of the 21st century. An interdisciplinary team at the KIT led by mechanical engineer Dr. Bastian E. Rapp developed a process using glass for additive manufacturing techniques. 

The scientists mix nanoparticles of high-purity quartz glass and a small quantity of liquid polymer and allow this mixture to be cured by light at specific points – by means of stereolithography. The material, which has remained liquid, is washed out in a solvent bath, leaving only the desired cured structure. The polymer still mixed in this glass structure is subsequently removed by heating. “The shape initially resembles that of a pound cake; it is still unstable, and therefore the glass is sintered in a final step, i.e. heated so that the glass particles are fused,” explains Rapp. 

He conducts research at the KIT Institute of Microstructure Technology and heads a working group of chemists, electrical engineers, and biologists. The scientists present the method in the “Nature” journal under the title of “Three-dimensional Printing of Transparent Fused Silica Glass.”

The variety of 3D-printing techniques available so far have been used on polymers or metals, but never on glass. Where glass was processed into structures, for instance by melting and application by means of a nozzle, the surface turned out to be very rough, the material was porous and contained voids.

Complicated high-precision structures made of glass can be manufactured in a 3D-printing process developed at the KIT. 
Photos: KIT

“We present a new method, an innovation in materials processing, in which the material of the piece manufactured is high-purity quartz glass with the respective chemical and physical properties,” explains Rapp. The glass structures made by the KIT scientists show resolutions in the range of a few micrometers – one micrometer corresponding to one thousandth of a millimeter. However, the structures may have dimensions in the range of a few centimeters, emphasizes Rapp.

3D-formed glass can be used, for instance, in data technology. “The next plus one generation of computers will use light, which requires complicated processor structures; 3D-technology could be used, for instance, to make small, complex structures out of a large number of very small optical components of different orientations,” explains the mechanical engineer. For biological and medical technologies, very small analytical systems could be made out of miniaturized glass tubes. In addition, 3D-shaped microstructures of glass could be employed in a variety of optical areas, from eyeglasses meeting special requirements to lenses in laptop cameras.


Photos: KIT

The development by scientists under Junior Scientist Group Leader Bastian E. Rapp is a result of the “NanoMatFutur” junior scientist funding scheme run by the German Federal Ministry for Education and Research (BMBF) to support the development of innovative materials for industry and society. The work performed by the research group headed by Rapp has been funded by the BMBF since 2014 for a total of four years to the tune of approx. € 2.8 million. 

“Our research benefits very much from the interdisciplinary cooperation of various KIT institutes. Besides the Institute of Microstructure Technology, colleagues of the Institute of Nuclear Waste Management and the Institute of Applied Materials, among others, are involved in the project,” says Rapp.


Contacts and sources:
Margarete Lehné
Karlsruhe Institute of Technology (KIT)

Friday, April 21, 2017

BP Oil Spill Did $17.2 Billion In Damage to Natural Resources, Scientists Find

The 2010 BP Deepwater Horizon oil spill did $17.2 billion in damage to the natural resources in the Gulf of Mexico, a team of scientists recently found after a six-year study of the impact of the largest oil spill in U.S. history.

This is the first comprehensive appraisal of the financial value of the natural resources damaged by the 134-million-gallon spill.

"This is proof that our natural resources have an immense monetary value to citizens of the United States who visit the Gulf and to those who simply care that this valuable resource is not damaged,"
said Kevin Boyle, a professor of agricultural and applied economics in the Virginia Tech College of Agriculture and Life Science and one of the authors on the paper.

The first-ever comprehensive appraisal of the financial impact on natural resources impacted by the BP Deepwater Horizon oil spill found that it did $17.2 billion in damage.
BP oil spill
Photo courtesy US Coast Guard

Findings from the study are published in the issue of Science released Friday, April 21.

The scientists developed a survey to put a dollar value on the natural resources damaged by the BP Deepwater spill by determining household willingness to pay for measures that would prevent similar damages should a spill of the same magnitude happen in the future. Survey information included descriptions of damaged beaches, marshes, animals, fish, and coral.

On top of estimating the impact of the spill, the $17.2 billion represents the benefits to the public to protect against damages that could result from a future oil spill in the Gulf of a similar magnitude.

In May 2010, one month after the spill, the U.S. National Oceanic and Atmospheric Administration commissioned a group of 18 researchers to put a dollar value on the natural resources damaged by the BP Deepwater spill.

To estimate Gulf Coast resource values, researchers created a scenario in which people were told that they could have a role in mitigating future damages by effectively paying for a prevention program.

Final analysis showed that the average household was willing to pay $153 for a prevention program. This rate was then multiplied by the number of households sampled to get the final valuation of $17.2 billion.

"The results were eye-opening in that we could tell how much people really value marine resources and ecosystems," said Boyle. "And even more meaningful because we did additional analysis that proved the legitimacy of oft-criticized values for environmental resources."

The project team administered surveys to a large random sample of American adults nation-wide after three years of survey development. The first round of surveys was administered face-to-face with trained interviewers while the remaining surveys were completed via mail.

Survey participants were informed of pre- and post-spill conditions in the Gulf of Mexico and what caused the oil spill. They were then told about a prevention program, which can be viewed as 100 percent effective insurance against future spill damages, and that another spill would occur in the next 15 years. With this information, participants were asked to vote for or against the program, which would impose a one-time tax on their household.

"Our estimate can guide policy makers and the oil industry in determining not only how much should be spent on restoration efforts for the Deepwater spill, but also how much should be invested to protect against damages that could result from future oil spills," said Boyle. "People value our natural resources, so it's worth taking major actions to prevent future catastrophes and correct past mistakes."



Contacts and sources:
Zeke Barlow
Virginia Tech

NASA Image Shows Earth Between the Rings of Saturn

A new image from NASA's Cassini spacecraft shows planet Earth as a point of light between the icy rings of Saturn.

The spacecraft captured the view on April 12, 2017, at 10:41 p.m. PDT (1:41 a.m. EDT on April 13). Cassini was 870 million miles (1.4 billion kilometers) away from Earth when the image was taken. Although far too small to be visible in the image, the part of Earth facing Cassini at the time was the southern Atlantic Ocean.

NASA's Cassini spacecraft captured this view of planet Earth as a point of light between the icy rings of Saturn on April 12, 2017.
View of planet Earth
Credits: NASA/JPL-Caltech/Space Science Institute

Earth's moon is also visible nearby in a cropped, zoomed-in version of the image.

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the mission for NASA's Science Mission Directorate, Washington. JPL designed, developed and assembled the Cassini orbiter.

This cropped, zoomed-in version of the image makes it easier to see Earth's moon -- a smaller, fainter dot to the left of our planet's bright dot.
Credits: NASA/JPL-Caltech/Space Science Institute

Can We See a Singularity, The Most Extreme Object in The Universe?

A team of scientists at the Tata Institute of Fundamental Research (TIFR), Mumbai, India, have found new ways to detect a bare or naked singularity, the most extreme object in the universe.

When the fuel of a very massive star is spent, it collapses due to its own gravitational pull and eventually becomes a very small region of arbitrarily high matter density, that is a`Singularity', where the usual laws of physics may breakdown. If this singularity is hidden within an event horizon, which is an invisible closed surface from which nothing, not even light, can escape, then we call this object a black hole.

 In such a case, we cannot see the singularity and we do not need to bother about its effects. But what if the event horizon does not form? In fact, Einstein's theory of general relativity does predict such a possibility when massive stars collapse at the end of their life-cycles. In this case, we are left with the tantalizing option of observing a naked singularity.

A black hole (on the left) and a naked singularity (on the right). The dashed line represents the event horizon of the black hole, which is absent in the case of a naked singularity, and the arrows represent the direction in which light rays travel. In the case of the black hole, because of the presence of an event horizon, all light rays inside it necessarily end up at the singularity. However, light rays may escape from the vicinity of a naked singularity to a far away observer rendering it visible.
Credit: Sudip Bhattacharyya, Pankaj Joshi

An important question then is, how to observationally distinguish a naked singularity from a black hole. Einstein's theory predicts an interesting effect: the fabric of spacetime in the vicinity of any rotating object gets `twisted' due to this rotation. This effect causes a gyroscope spin and makes orbits of particles around these astrophysical objects precess.

The TIFR team has recently argued that the rate at which a gyroscope precesses (the precession frequency), when placed around a rotating black hole or a naked singularity, could be used to identify this rotating object. Here is a simple way to describe their results. If an astronaut records a gyroscope's precession frequency at two fixed points close to the rotating object, then two possibilities can be seen: (1) the precession frequency of the gyroscope changes by an arbitrarily large amount, that is, there is a wild change in the behaviour of the gyroscope; and (2) the precession frequency changes by a small amount, in a regular well-behaved manner. For the case (1), the rotating object is a black hole, while for the case (2), it is a naked singularity.

The TIFR team, namely, Dr. Chandrachur Chakraborty, Mr. Prashant Kocherlakota, Prof. Sudip Bhattacharyya and Prof. Pankaj Joshi, in collaboration with a Polish team comprising Dr. Mandar Patil and Prof. Andrzej Krolak, has infact shown that the precession frequency of a gyroscope orbiting a black hole or a naked singularity is sensitive to the presence of an event horizon. A gyroscope circling and approaching the event horizon of a black hole from any direction behaves increasingly 'wildly,' that is, it precesses increasingly faster, without a bound. But, in the case of a naked singularity, the precession frequency becomes arbitrarily large only in the equatorial plane, but being regular in all other planes.

The TIFR team has also found that the precession of orbits of matter falling into a rotating black hole or a naked singularity can be used to distinguish these exotic objects. This is because the orbital plane precession frequency increases as the matter approaches a rotating black hole, but this frequency can decrease and even become zero for a rotating naked singularity. This finding could be used to distinguish a naked singularity from a black hole in reality, because the precession frequencies could be measured in X-ray wavelengths, as the infalling matter radiates X-rays.




Contacts and sources:
Pankaj Joshi
Tata Institute of Fundamental Research (TIFR)

Citation:

1. "Spin precession in a black hole and naked singularity spacetimes,''C. Chakraborty, P. Kocherlakota, and P. S. Joshi, Phys. Rev. D 95, 044006 (2017)

2. "Distinguishing Kerr naked singularities and black holes using the spin precession of a test gyro in strong gravitational fields,''C. Chakraborty, P. Kocherlakota, M. Patil, S. Bhattacharyya, P. S. Joshi, and A. Kr\'olak, Phys. Rev. D 95, 084024 (2017)




Is Soda Bad for Your Brain? (And Is Diet Soda Worse?)

Americans love sugar. Together we consumed nearly 11 million metric tons of it in 2016, according to the US Department of Agriculture, much of it in the form of sugar-sweetened beverages like sports drinks and soda.

Now, new research suggests that excess sugar -- especially the fructose in sugary drinks--might damage your brain. Researchers using data from the Framingham Heart Study (FHS) found that people who drink sugary beverages frequently are more likely to have poorer memory, smaller overall brain volume, and a significantly smaller hippocampus -- an area of the brain important for learning and memory.

But before you chuck your sweet tea and reach for a diet soda, there's more: a follow-up study found that people who drank diet soda daily were almost three times as likely to develop stroke and dementia when compared to those who did not.

Matthew Pase is lead author on two studies that link higher consumption of both sugary and artificially sweetened drinks to adverse brain effects.
Photo by Cydney Scott

Researchers are quick to point out that these findings, which appear separately in the journals Alzheimer's & Dementia and Stroke, demonstrate correlation but not cause-and-effect. While researchers caution against over-consuming either diet soda or sugary drinks, more research is needed to determine how -- or if -- these drinks actually damage the brain, and how much damage may be caused by underlying vascular disease or diabetes.

"These studies are not the be-all and end-all, but it's strong data and a very strong suggestion," says Sudha Seshadri, a professor of neurology at Boston University School of Medicine (MED) and a faculty member at BU's Alzheimer's Disease Center, who is senior author on both papers. "It looks like there is not very much of an upside to having sugary drinks, and substituting the sugar with artificial sweeteners doesn't seem to help."

"Maybe good old-fashioned water is something we need to get used to," she adds.

Matthew Pase, a fellow in the MED neurology department and an investigator at the FHS who is corresponding author on both papers, says that excess sugar has long been associated with cardiovascular and metabolic diseases like obesity, heart disease, and type 2 diabetes, but little is known about its long-term effects on the human brain. He chose to study sugary drinks as a way of examining overall sugar consumption. "It's difficult to measure overall sugar intake in the diet," he says, "so we used sugary beverages as a proxy."

For the first study, published in Alzheimer's & Dementia on March 5, 2017, researchers examined data, including magnetic resonance imaging (MRI) scans and cognitive testing results, from about 4,000 people enrolled in the Framingham Heart Study's Offspring and Third-Generation cohorts. (These are the children and grandchildren of the original FHS volunteers enrolled in 1948.) The researchers looked at people who consumed more than two sugary drinks a day of any type -- soda, fruit juice, and other soft drinks -- or more than three per week of soda alone. Among that "high intake" group, they found multiple signs of accelerated brain aging, including smaller overall brain volume, poorer episodic memory, and a shrunken hippocampus, all risk factors for early-stage Alzheimer's disease. Researchers also found that higher intake of diet soda--at least one per day--was associated with smaller brain volume.

In the second study, published in Stroke on April 20, 2017, the researchers, using data only from the older Offspring cohort, looked specifically at whether participants had suffered a stroke or been diagnosed with dementia due to Alzheimer's disease. After measuring volunteers' beverage intake at three points over seven years, the researchers then monitored the volunteers for 10 years, looking for evidence of stroke in 2,888 people over age 45, and dementia in 1,484 participants over age 60. Here they found, surprisingly, no correlation between sugary beverage intake and stroke or dementia. However, they found that people who drank at least one diet soda per day were almost three times as likely to develop stroke and dementia.

Although the researchers took age, smoking, diet quality, and other factors into account, they could not completely control for preexisting conditions like diabetes, which may have developed over the course of the study and is a known risk factor for dementia. Diabetics, as a group, drink more diet soda on average, as a way to limit their sugar consumption, and some of the correlation between diet soda intake and dementia may be due to diabetes, as well as other vascular risk factors. However, such preexisting conditions cannot wholly explain the new findings.

"It was somewhat surprising that diet soda consumption led to these outcomes," says Pase, noting that while prior studies have linked diet soda intake to stroke risk, the link with dementia was not previously known. He adds that the studies did not differentiate between types of artificial sweeteners and did not account for other possible sources of artificial sweeteners. He says that scientists have put forth various hypotheses about how artificial sweeteners may cause harm, from transforming gut bacteria to altering the brain's perception of "sweet," but "we need more work to figure out the underlying mechanisms."



Contacts and sources: 
Matthew Pase
Boston University

Origins of Indonesian Hobbits Finally Revealed

CThe most comprehensive study on the bones of Homo floresiensis, a species of tiny human discovered on the Indonesian island of Flores in 2003, has found that they most likely evolved from an ancestor in Africa and not from Homo erectus as has been widely believed.

The study by The Australian National University (ANU) found Homo floresiensis, dubbed "the hobbits" due to their small stature, were most likely a sister species of Homo habilis -- one of the earliest known species of human found in Africa 1.75 million years ago.

This is an artists impression of Homo floresiensis.

Credit:  Katrina Kenny, SA Museum


Data from the study concluded there was no evidence for the popular theory that Homo floresiensis evolved from the much larger Homo erectus, the only other early hominid known to have lived in the region with fossils discovered on the Indonesian mainland of Java.

Study leader Dr Debbie Argue of the ANU School of Archaeology & Anthropology, said the results should help put to rest a debate that has been hotly contested ever since Homo floresiensis was discovered.

"The analyses show that on the family tree, Homo floresiensis was likely a sister species of Homo habilis. It means these two shared a common ancestor," Dr Argue said.

"It's possible that Homo floresiensis evolved in Africa and migrated, or the common ancestor moved from Africa then evolved into Homo floresiensis somewhere."

Homo floresiensis is known to have lived on Flores until as recently as 54,000 years ago.

This is a reconstructed skull of Homo floresiensis. 
Credit: Stuart Hay, ANU

The study was the result of an Australian Research Council grant in 2010 that enabled the researchers to explore where the newly-found species fits in the human evolutionary tree.

Where previous research had focused mostly on the skull and lower jaw, this study used 133 data points ranging across the skull, jaws, teeth, arms, legs and shoulders.

Dr Argue said none of the data supported the theory that Homo floresiensis evolved from Homo erectus.

"We looked at whether Homo floresiensis could be descended from Homo erectus," she said.

"We found that if you try and link them on the family tree, you get a very unsupported result. All the tests say it doesn't fit -- it's just not a viable theory."

Dr Argue said this was supported by the fact that in many features, such as the structure of the jaw, Homo floresiensis was more primitive than Homo erectus.

"Logically, it would be hard to understand how you could have that regression -- why would the jaw of Homo erectus evolve back to the primitive condition we see in Homo floresiensis?"

Dr Argue said the analyses could also support the theory that Homo floresiensis could have branched off earlier in the timeline, more than 1.75 million years ago.

"If this was the case Homo floresiensis would have evolved before the earliest Homo habilis, which would make it very archaic indeed," she said.

Professor Mike Lee of Flinders University and the South Australian Museum, used statistical modeling to analyse the data.

"When we did the analysis there was really clear support for the relationship with Homo habilis. Homo floresiensis occupied a very primitive position on the human evolutionary tree," Professor Lee said.

"We can be 99 per cent sure it's not related to Homo erectus and nearly 100 per cent chance it isn't a malformed Homo sapiens," Professor Lee said.

Dr Argue undertook the study along with ANU Professor Colin Groves, and Professor William Jungers from Stony Brook University, USA. The findings have been released in the Journal of Human Evolution.


Contacts and sources:
Dr Debbie Argue, ANU School of Archaeology and Anthropology
Professor Colin Groves, ANU School of Archaeology and Anthropology

Alien Oceans Galore: New Study Suggests Most Habitable Planets May Lack Dry Land

When it comes to exploring exoplanets, it may be wise to take a snorkel along. A new study, published in a paper in the journal Monthly Notices of the Royal Astronomical Society, has used a statistical model to predict that most habitable planets may be dominated by oceans spanning over 90% of their surface area.

The author of the study, Dr Fergus Simpson of the Institute of Cosmos Sciences at the University of Barcelona, has constructed a statistical model – based on Bayesian probability – to predict the division between land and water on habitable exoplanets.

For a planetary surface to boast extensive areas of both land and water, a delicate balance must be struck between the volume of water it retains over time, and how much space it has to store it in its oceanic basins. Both of these quantities may vary substantially across the full spectrum of water-bearing worlds, and why the Earth’s values are so well balanced is an unresolved and long-standing conundrum.





Continents on other habitable worlds may struggle to break above sea level, like much of Europe in this illustration, representing Earth with an estimated 80% ocean coverage. © Antartis / Depositphotos.com. Click for a larger imageSimpson’s model predicts that most habitable planets are dominated by oceans spanning over 90% of their surface area. This conclusion is reached because the Earth itself is very close to being a so-called ‘waterworld’ - a world where all land is immersed under a single ocean.

“A scenario in which the Earth holds less water than most other habitable planets would be consistent with results from simulations, and could help explain why some planets have been found to be a bit less dense than we expected,” explains Simpson.

In the new work, Simpson finds that the Earth’s finely balanced oceans may be a consequence of the anthropic principle – more often used in a cosmological context - which accounts for how our observations of the Universe are influenced by the requirement for the formation of sentient life.

“Based on the Earth’s ocean coverage of 71%, we find substantial evidence supporting the hypothesis that anthropic selection effects are at work,” comments Simpson.

To test the statistical model Simpson has taken feedback mechanisms into account, such as the deep water cycle, and erosion and deposition processes. He also proposes a statistical approximation to determine the diminishing habitable land area for planets with smaller oceans, as they become increasingly dominated by deserts.

Why did we evolve on this planet and not on one of the billions of other habitable worlds? In this study Simpson suggests the answer could be linked to a selection effect involving the balance between land and water.

“Our understanding of the development of life may be far from complete, but it is not so dire that we must adhere to the conventional approximation that all habitable planets have an equal chance of hosting intelligent life,” Simpson concludes.




Contacts and sources:
Dr Robert Massey, Royal Astronomical Society
Dr Morgan Hollis, Royal Astronomical Society
Dr Fergus Simpson, Institute of Cosmos Sciences, University of Barcelona

Naked Mole-Rats Turn into Plants When Oxygen Is Low

Deprived of oxygen, naked mole-rats can survive by metabolizing fructose just as plants do, researchers report this week in the journal Science.

Understanding how the animals do this could lead to treatments for patients suffering crises of oxygen deprivation, as in heart attacks and strokes.



“This is just the latest remarkable discovery about the naked mole-rat — a cold-blooded mammal that lives decades longer than other rodents, rarely gets cancer, and doesn’t feel many types of pain,” says Thomas Park, professor of biological sciences at the University of Illinois at Chicago, who led an international team of researchers from UIC, the Max Delbrück Institute in Berlin and the University of Pretoria in South Africa on the study.

Ignore the whiskers and teeth — these are plants.




In humans, laboratory mice, and all other known mammals, when brain cells are starved of oxygen they run out of energy and begin to die.

But naked mole-rats have a backup: their brain cells start burning fructose, which produces energy anaerobically through a metabolic pathway that is only used by plants – or so scientists thought.

In the new study, the researchers exposed naked mole-rats to low oxygen conditions in the laboratory and found that they released large amounts of fructose into the bloodstream. The fructose, the scientists found, was transported into brain cells by molecular fructose pumps that in all other mammals are found only on cells of the intestine.

“The naked mole-rat has simply rearranged some basic building-blocks of metabolism to make it super-tolerant to low oxygen conditions,” said Park, who has studied the strange species for 18 years.

At oxygen levels low enough to kill a human within minutes, naked mole-rats can survive for at least five hours, Park said. They go into a state of suspended animation, reducing their movement and dramatically slowing their pulse and breathing rate to conserve energy. And they begin using fructose until oxygen is available again.

The naked mole-rat is the only known mammal to use suspended animation to survive oxygen deprivation.

The scientists also showed that naked mole-rats are protected from another deadly aspect of low oxygen – a buildup of fluid in the lungs called pulmonary edema that afflicts mountain climbers at high altitude.

The scientists think that the naked mole-rats’ unusual metabolism is an adaptation for living in their oxygen-poor burrows. Unlike other subterranean mammals, naked mole-rats live in hyper-crowded conditions, packed in with hundreds of colony mates. With so many animals living together in unventilated tunnels, oxygen supplies are quickly depleted.

The research was supported by National Science Foundation (grant #0744979), the European Research Council (grant 294678), the Deutsche Forschungsgemeinschaft SFB 665, and the National Institutes of Health (grants HL71626 and HL60678).




Contacts and sources:
Bill Burton
University of Illinois at Chicago


Citation: “Fructose-driven glycolysis supports anoxia resistance in the naked mole-rat” (DOI: 10.1126/science.aab3896) co-authors are Bethany L. Peterson, Gregory Blass, Brigitte M. Browe, Daniel T. Applegate, Victoria Gavaghan, Vince G. Amoroso and Vidya Govind of UIC’s Laboratory of Integrative Neuroscience; Richard D. Minshall and John Larson of the UIC College of Medicine; Gary R. Lewin, Jane Reznick, Damir Omerbašić, Tetiana Kosten, Ole Eigenbrod, Valérie Bégay, P. Henning J.L. Kuich, Christin Zasada, Stefan Kempa, Wiebke Hamann, Michael H. Radke and Michael Gotthardt of the Max Delbrück Center for Molecular Medicine and Ewan St. J. Smith, now at the University of Cambridge; and Nigel C. Bennett and Heike Lutermann of the University of Pretoria. http://dx.doi.org/10.1126/science.aab3896

Environmental ‘Memories’ Passed on for 14 Generations Even When Conditions Return to Normal

Scientists at the Centre for Genomic Regulation (CRG) in Barcelona and the Josep Carreras Leukaemia Research Institute and The Institute for Health Science Research Germans Trias i Pujol (IGTP) in Badalona, Spain, have discovered that the impact of environmental change can be passed on in the genes of tiny nematode worms for at least 14 generations – the most that has ever been seen in animals. The findings will be published on Friday 21st April in the journal Science.

Led by Dr Ben Lehner, group leader at the EMBL-CRG Systems Biology Unit and ICREA and AXA Professor, together with Dr Tanya Vavouri CRG Alumna and currenty group leader at the Josep Carreras Leukaemia Research Institute and the Institute for Health Science Research Germans Trias i Pujol (IGTP), the researchers noticed that the impact of environmental change can be passed on in the genes for many generations while studying C. elegans worms carrying a transgene array – a long string of repeated copies of a gene for a fluorescent protein that had been added into the worm genome using genetic engineering techniques.


C elegans worm
Credit:  Adam Klosin CRG

If the worms were kept at 20 degrees Celsius, the array of transgenes was less active, creating only a small amount of fluorescent protein. But shifting the animals to a warmer climate of 25 degrees significantly increased the activity of the transgenes, making the animals glow brightly under ultraviolet light when viewed down a microscope.

When these worms were moved back to the cooler temperature, their transgenes were still highly active, suggesting they were somehow retaining the ‘memory’ of their exposure to warmth. Intriguingly, this high activity level was passed on to their offspring and onwards for 7 subsequent generations kept solely at 20 degrees, even though the original animals only experienced the higher temperature for a brief time. Keeping worms at 25 degrees for five generations led to the increased transgene activity being maintained for at least 14 generations once the animals were returned to cooler conditions.

Although this phenomenon has been seen in a range of animal species – including fruit flies, worms and mammals including humans – it tends to fade after a few generations. These findings, which will be published on Friday 21st April in the journal Science, represent the longest maintenance of transgenerational environmental ‘memory’ ever observed in animals to date.

“We discovered this phenomenon by chance, but it shows that it’s certainly possible to transmit information about the environment down the generations,” says Lehner. “We don’t know exactly why this happens, but it might be a form of biological forward-planning," adds the first author of the study, Adam Klosin. "Worms are very short-lived, so perhaps they are transmitting memories of past conditions to help their descendants predict what their environment might be like in the future,” adds Vavouri.

Comparing the transgenes that were less active with those that had become activated by the higher temperature, Lehner and his team discovered crucial differences in a type of molecular ‘tag’ attached to the proteins packaging up the genes, known as histone methylation.*

Transgenes in animals that had only ever been kept at 20 degrees had high levels of histone methylation, which is associated with silenced genes, while those that had been moved to 25 degrees had largely lost the methylation tags. Importantly, they still maintained this reduced histone methylation when moved back to the cooler temperature, suggesting that it is playing an important role in locking the memory into the transgenes.**

The researchers also found that repetitive parts of the normal worm genome that look similar to transgene arrays also behave in the same way, suggesting that this is a widespread memory mechanism and not just restricted to artificially engineered genes.

Explainers:
*DNA inside cells is wrapped around ball-shaped proteins called histones. These can be modified with molecular ‘tags’ (epigenetic marks) in a number of different ways. Some epigenetic marks are associated with active genes, while others are linked to gene silencing. In this paper, the researchers were studying a histone modification known as H3K9 trimethylation, which represses gene activity. 

** It’s not known whether the histone methylation patterns themselves are responsible for transmitting the temperature memory down the generations, although they can be seen in eggs and sperm, and are present at the earliest stages of worm development. It’s also unclear exactly how the increase in temperature leads to the loss of histone methylation marks. However, Lehner, Vavouri and their team have found that a protein called SET-25 is responsible for maintaining the histone methylation patterns on the transgene arrays.


Contacts and sources:
Centre for Genomic Regulation (CRG) 

Citation: Klosin et al. Transgenerational transmission of environmental information in C. elegans. Science. April 21 2017. DOI: 10.1126/science.aah6412

Why Cockroaches Are So Prolific

Asexual reproduction increases when female cockroaches are housed as a group, not alone, enabling them to maintain a colony for at least three years without a male’s contribution.

Asexual reproduction is promoted when female cockroaches are housed as a group, not alone, enabling them to maintain a colony for at least three years without a male’s contribution.

(A) Female cockroaches kept in a container. (B) The egg case on the left is an asexual egg case, while the right one was produced by sexual reproduction. (C) A dissected egg case stuffed with 16 eggs.




Parthenogenesis is a strategy employed by females to reproduce asexually when they find no mating partners available, and is seen in a wide variety of animals, including arthropods, fish, amphibians and reptiles. As opposed to sexual mating which enhances genetic diversity, the asexual strategy is aimed at rapidly generating large numbers of female progeny to expand their habitat.

Cockroaches belonging to the Periplaneta genus are indoor pests that are ubiquitously found across temperate and tropical regions. Parthenogenesis of this genus was reported in literature a long time ago, but little has been known about the factors that cause them to switch from a sexual mode of reproduction to an asexual one.

In a study conducted by Hokkaido University researchers, one or more female American cockroaches (Periplaneta americana) were placed in individual plastic containers immediately after becoming adults. They then measured the exact timing of the delivery of asexually produced egg cases (i.e. oothecae, each containing about sixteen eggs) for more than two-months.

When only one female was kept in a container, it took more time to produce an egg case than group-housed females. When three or five females were kept in a container together, they produced egg cases faster than any of the other groups. While the timing of egg case production of isolated females varied from individual to individual, the group-housed females produced egg cases in a synchronized manner. This apparent synchronization was observed even across different containers, suggesting that the egg case production rate had reached its maximum through some kind of interaction between individuals within the container.

The researchers also found that housing females with genitalia-ablated males or removing the antennae of group-housed females did not significantly promote egg case production. The daily addition of female sex pheromones to the containers did not raise egg case production either. The results imply that group-housed females promote asexual egg production by perceiving female-specific chemosensory signals - other than sex pheromones - that they detect via their antennae.

“Our study shows that female cockroaches promote asexual egg production when they are together, not alone. This is consistent with the fact that progenies produced by fifteen females in a larger container have maintained a colony for more than three years, whereas those produced by one female die out fairly quickly. In addition to the increased fecundity of group-housed females, the synchronized egg production could also assure higher survival rates via the aggregation of similar-aged larvae,” says the corresponding author, Hiroshi Nishino, at Hokkaido University. “The traps utilizing sex pheromones to attract only male cockroaches are not sufficient. Understanding the physiological mechanism behind the reproductive strategies should help us find more effective ways to exterminate pest cockroaches in the future.”



Contacts and sources:
Assistant Professor Hiroshi Nishino
Research Center of Mathematics for Social Creativity
Research Institute for Electronic Science
Hokkaido University

Thursday, April 20, 2017

Light Rays from a Supernova Bent by the Curvature of Space-Time Around a Galaxy

An international research team led by Ariel Goobar at Stockholm University has detected for the first time multiple images from a gravitationally lensed Type Ia supernova. The new observations suggest promising new avenues for the study of the accelerated expansion of the Universe, gravity and distribution of dark matter in the universe.

Type Ia supernovae, nature's own "standard candles", have been used for many years by astronomers to measure cosmological distances. These studies led to the discovery of the accelerated expansion of the Universe, a sensational discovery that won the 2011 Nobel prize in Physics. Professor Ariel Goobar at the Department of Physics at Stockholm University was a member of the team led by one of the Nobel laureates, Saul Perlmutter.

The light from the supernova iPTF16geu and of its host galaxy is warped and amplified by the curvature of space mass of a foreground galaxy. In the case of the point-like supernova, the light is split into four images. These have been resolved with the Hubble Space Telescope.

Credit: Original image by ALMA (ESO/NRAO/NAOJ), L. Calçada (ESO), Y. Hezaveh et al, edited and modified by Joel Johansson

An international team of physicists and astronomers led from Stockholm University has now seen, for the first time, the rare appearance of multiple images of the same exploding star dubbed iPTF16geu, which belongs to a class of supernovae known as Type Ia. The phenomenon, called strong gravitational lensing is a result of the intense warping of the supernova light by an intervening galaxy positioned between us and the star in near perfect alignment. In this special case, the supernova appeared magnified, but also multiplied. The new observations provide a promising new tool to test key cosmological theories about the accelerating expansion of the universe and the distribution of a mysterious substance known as dark matter.

Type Ia supernovae are abundant and frequently used by astronomers to accurately measure distances in the universe. Gravitational lensing - the curving of space due to gravity - has also been observed many times since the early 20th century when it was predicted by Einstein. Yet, imaging a gravitationally lensed Type Ia supernova had proven formidably difficult, until now.

"Resolving, for the first time, multiple images of a strongly lensed "standard candle" supernova is a major breakthrough. We can measure the light focusing power of gravity more accurately than ever before, and probe physical scales that may have seemed out of reach until now," says Ariel Goobar, Professor at Oskar Klein Centre, Stockholm University and a lead author of the study, published today in the journal Science.

Goobar and his group are partners in two Caltech-led international scientific collaborations-- iPTF (intermediate Palomar Transient Factory) and GROWTH (Global Relay of Observatories Watching Transients Happen). The iPTF takes advantage of the Palomar Observatory and its unique capabilities to scan the skies and discover, in near real time, fast-changing cosmic events such as supernovae. GROWTH manages a global network of researchers and telescopes that can swiftly perform follow-up observations to study these transient events in detail.

Within two months of detection, the team observed iPTF16geu supernova with NASA/ESA Hubble Space Telescope, and the adaptive-optics instruments on the Keck Observatory atop Mauna Kea, Hawaii, and the VLT telescopes in Chile. Apart from producing a striking visual effect, capturing the image of the strongly lensed Type Ia supernova such as iPTF16geu is extremely useful scientifically. Astronomers can now measure very accurately how much time it takes for the light from each of the multiple images of the supernova to reach us. The difference in the time of arrival can then be used to estimate with a high precision the expansion rate of the universe known as the Hubble constant. Currently, the different methods to measure the Hubble constant produce slightly different results but even these small changes can result in significantly different scenarios for the predicted evolution and expansion of the universe.

The study of iPTF16geu is already delivering interesting results. Based on current knowledge of supernovae and gravitational lensing, observing an event such as iPTF16geu is rather improbable. Moreover, using data from Keck and Hubble the team finds that the lensing galaxy needs a great deal of substructure to account for the observed differences in the four supernova images, and the total lens magnification.

This may introduce new questions about the way matter clumps in the universe and challenge astronomers' understanding of gravitational lensing at small scales.

"The discovery of iPTF16geu is truly like finding a somewhat weird needle in a haystack. It reveals to us a bit more about the universe, but mostly triggers a wealth of new scientific questions. That's why I love science and astronomy" - says Rahman Amanullah, a postdoctoral fellow at Stockholm University and a co-author on the study.



Contacts and sources:
Ariel Goobar
Department of Physics, Stockholm University.

Pizzlies, Grolars and Capuccinos Reveal Frisky Bears Breed Across Species Borders

Senckenberg scientists have sequenced the entire genomes of four bear species, making it now possible to analyze the evolutionary history of all bears at the genome level. It shows that gene flow, or gene exchange, between species by extensive hybridization, is possible between most bear species - not only polar and brown bear.

 The DNA samples of different bear species came from different European zoos, underlining their importance not only for conservation, but also for research. The study published today in "Nature Scientific Reports" also questions the existing species concept in general, because other genome studies too have, frequently found gene flow among species.

Hybrids between bear species such as the pizzly or grolar bear, which is a mixture of polar and grizzly bear, are not as rare as hitherto assumed. 
Copyright: Andrew E. Derocher

Pizzly, grolars or "capuccino bears" are common names of the offspring resulting from the mating of grizzly bears (Ursus arctos) and polar bears (Ursus maritimus). "Such hybrids among bears are not as rare as we have hitherto assumed," says Prof. Dr. Axel Janke of the Senckenberg Biodiversity and Climate Research Center in Frankfurt. In a large-scale analysis, a team of scientists led by the German evolutionary geneticist has sequenced six complete bear genomes. Each genome is about 2.5 billion base pairs large. "With these new data of the sun bear, sloth bear, Asiatic black bear and spectacled bear, we now have the genomes of all known bear species," adds Janke.

Pizzly, grolars or "capuccino bears"

Credit: Wikimedia Commons

It has previously been assumed that the number of hybrids between polar and brown bears is increasing due to climate change, because brown bears invade northern regions and polar bears move onto the sea ice later than usual. The new results show however that an abundant flow of genes among different bear species occurred to a good deal in the past. Hybrids are thus not necessarily linked to climate change. 

"Bears can form hybrids in different combinations," explains Janke, and adds: "We knew this from zoos. In the wild, so far this was only observed for polar bears and brown bear as well as Asiatic black and sun bear."

Brown bears may be intermediate hosts of genes between the geographically separated polar and sun bears because the brown bear distribution area overlaps with both of the species. 

Copyright: Alexander Kopatz

The new genomic data also show that there must have even been gene flow between the polar and sun bears. However, the two species live in geographically completely distinct areas and thus have never met. The researchers are able to explain this alleged contradiction by suggesting that an "intermediate host" or "vector species" has passed the genes on in various directions. 

The brown bear is an ideal candidate for this role as conveyor of genes: his geographic distribution overlaps with that of all other bear species and its genome contains polar bear genes. "By hybridization the brown bear could pass these polar bear genes on to other bear species in Asia", adds the Frankfurt scientist.

Sloth Bear, a nocturnal insectivorous bear species native to the Indian subcontinent
Sloth Bear Washington DC.JPG
Credit: Wikipedia

The detected gene flow among bears also questions the basic biological concept of a species. The biological species definition assumes that different species cannot produce offspring in the wild or that hybrid offspring are sterile. The best-known example of this is the mule – a hybrid between a horse and a donkey. 

However, it has been observed that grolars, the hybrids between polar and grizzly bears, are often fertile. Janke: "We have to ask ourselves: Does the species concept still hold true, given there is evidence of gene flow not only in bears, but also in other animals? Therefore, what do we need to protect for the future – species or genomic diversity? ".

It is certain that the amazing progress of genomics and its technology will also question other fundamental principles of biology and fuel research. "Evolution creates genetic differences and adaptations, whether we call these differences species or not, is less important. What we must preserve, however, is genetic variation to protect diversity and to allow adaptation to future environmental changes", Janke states.



Contacts and sources:
Senckenberg Research Institute and Natural History Museum


Citation: Kumar, V. et al. (2017): The evolutionary history of bears is characterized by gene flow across species. Scientific Reports 7, 46487, doi: 10.1038/srep46487

240 Million Year Old Ancestor of Crocodiles and Dinosaurs Discovered in the Pyrenees

The bones of a creature never known before that lived more than 240 millions years ago has been found in the Pyrenees.  

The several excavation campaigns conducted in 2012 by geologists, biologists and palaeontologists of the Universitat Autònoma de Barcelona (UAB) and the Institut Català de Paleontologia Miquel Crusafont (ICP), together with local geologists in outcrops of the Pyrenees corresponding to the Permian and Triassic periods (ranging from 300 to 200 million years ago), have given way to the discovery of a large amount of new sites.

This week, researchers published in PLOS ONE a new project on the ecosystems of the Lleida Pyrenees during the beginning of the Mesozoic Era. The new studies are based on the vertebrates living there during the early and middle Triassic period (some 247 and 248 million years ago). This gap in time was crucial for the recovery of the ecosystems after the End-Permian extinction (about 252 million years ago), the most devastating known extinction event in the history of Earth, where it is estimated that 90% of species disappeared; far worse than what caused the extinction of dinosaurs.

Artistic reconstruction of an archosauromorph. 
Author: Oscar Sanisidro / Institut Català de Paleontologia Miquel Crusafont

During the Triassic Period, the configuration of the Earth was very different from today: all continents were united into one called Pangaea. In this geological period the Pyrenees, located at the equatorial level of the planet, were formed by a set of small basins in which river sediments gathered and which gave way to rock formations with a typically reddish colour, highly abundant throughout the Pyrenees, as well as across Europe.

The study is based on the analysis of trace fossils (ichnites) left by several groups of reptiles on these sediments, as well as of the ecosystems in which they lived. “Ichnites are very ephemeral fossils and difficult to conserve, but thanks to photogrammetric techniques which obtain 3D models and to the creation of silicone moulds, we were able to identify and preserve them in their registry”, UAB researcher Eudald Mujal explains. The analysis of rocks in three different areas of the Pyrenees has allowed researchers to see the Triassic environments formed by winding rivers and floodplains. In all of these environments lived a large diversity of vertebrates, mostly corresponding to arcosauromorphs, the group of reptiles which later evolved into crocodiles and dinosaurs.

The study of the tracks has demonstrated that the reduced-size arcosauromorphs (approximately half a metre long) were the largest group and, although in less amounts, there were also reptiles measuring over three metres long.

New Trace Fossil Species

Found among the group of ichnites was the presence of a never before described shape, which has made researchers establish a new ichnotaxon: Prorotodactylus mesaxonichnus. An ichnotaxon is how researchers classify a trace fossil (given that the specific animal which produced the fossil is not known) and is the equivalent of a biological species. Until now, the ichnogenera (genus of a trace fossil) Prorotodactylus was only known to exist in the Central European Germanic basin (Poland and Germany). The ichnites were first attributed to dinosauromorphs, first members of the dinosaur lineage, but the new Pyrenean ichnites reveal that they are related to another group of basal archosauromorphs, thereby discarding the possibility of the new ichnotaxon being related to the dinosaur lineage.

According to ICP researcher Josep Fortuny “the new Pyrenean footprints indicate that these animals, measuring around half a metre, used all four limbs to walk and often also left marks with their tails. In any case, some footprints point to the possibility of bipedal locomotion in specific moments with the aim of moving faster.” All these characteristics indicate that the authors of the footprints could be the euparkeriidae, a group of basal archosauromorphs known for their fossil remains found from the same time period in Poland, Russia, China and South Africa.

The association of Pyrenean ichnites is similar to that of other areas such as southern France, Morocco, Germany, Poland and the United States. That makes the authors of the study think that the fauna from the early and middle Triassic period were quite homogeneous, at least in the equatorial area of Pangaea, and that river environments, very extensive during these periods, were dominated by the archosauromorphs. Therefore, the authors of the study conclude that this group was key in the recovery of ecosystems after the End-Permian extinction by making use of the large empty ecological niches caused by the mass extinction and allowing the predecessors of the first dinosaurs to spread and diversify.


Contacts and sources:
Universitat Autònoma de Barcelona

Citation:  Mujal, E., Fortuny, J., Bolet, A., Oms, O., López, J. Á. “An archosauromorph dominated ichnoassemblage in fluvial settings from the late Early Triassic of the Catalan Pyrenees (NE Iberian Peninsula).” PLOS ONE http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0174693

Mesmerizing Animation Of 2016 Sea Surface Temperature

The animation below combines satellite data with ocean surface measurements. The satellite data used come from both the geostationary ring of satellites and polar orbiting data including from Europe, America and Japan.



“The animation is important to see the changes on a global scale of the surface temperatures of our ocean, and to consider how these influence weather patterns and thus our daily lives. Moreover, the compilation of the voiceover was an interesting opportunity to put these changes into context,” Anne said.

The global sea surface temperature animation is compiled from the Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) as produced by the Met Office. The products are available from the Copernicus Marine Environment Monitoring Service (CMEMS).
The animation shows the beauty of the movement of our ocean and the changes in temperature and how energy is distributed and spreads around our globe

“The animation shows a level-4 analysis product, which means that it uses a combination of satellite sea surface temperature data combined together with the surface measurements. These are all provided in a common way and specification through coordination by the Group for High Resolution Sea Surface Temperature (more information here). It is a daily analysis for night-time produced at 1/20 degree spatial resolution which is at approximately 5km” Anne explains.

Anne goes through each month of the year highlighting specific weather events, currents and changes in temperatures in different zones of the Earth focussing especially on El Niño–Southern Oscillation (ENSO) and La Niña.

Watch El Niño

El Niño is a natural cycle in Pacific Ocean temperatures, winds and cloud that influences climate all around the planet. It consists in a band of warm water developing in the central and east-central equatorial Pacific. On the other hand La Niña is the “cool” phase that follows El Niño, bringing colder temperatures.

Image 1: El Niño conditions in February 2016

Credit: EUMETSAT


In February (image 1 and minute 00.46) we can see El Niño conditions in the El Niño 3.4 region with sea surface temperatures at more than ½ degree above average conditions. In April the strength of El Niño is fading and we can see cooler temperatures moving westward in the Central Pacific (Image 2 and minute 02.50).

Image 2: Cooler temperatures moving off the coast of Peru lowering the strength of El Niño in April

Credit: EUMETSAT


Moving into summer, El Niño conditions reach the neutral state with sea surface temperatures getting gradually cooler (04.15).

Finally, from October onwards we can see La Niña conditions where sea surface temperatures in the El Nino 3.4 region are 0.5 degrees colder than usual (05.50).

As seasons change, colder temperatures are coloured in blue while warmer surface temperatures evolve from yellow to magenta, and while currents move we can see the changes in temperatures twirling around.

Image 3: Malvinas or Falkland western boundary current

Credit: EUMETSAT

“The animation shows the beauty of the movement of our ocean and the changes in temperature and how energy is distributed and spreads around our globe, affecting the weather, climate, ecosystem and all our daily lives” Anne said.

Image 4: Record low sea ice extent of late 2016

Credit: EUMETSAT


Contacts and sources:
European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT)

Wednesday, April 19, 2017

The Arrhythmic Beating of a Black Hole Heart

At the center of the Centaurus galaxy cluster, there is a large elliptical galaxy called NGC 4696. Deeper still, there is a supermassive black hole buried within the core of this galaxy.

New data from NASA's Chandra X-ray Observatory and other telescopes has revealed details about this giant black hole, located some 145 million light years from Earth. Although the black hole itself is undetected, astronomers are learning about the impact it has on the galaxy it inhabits and the larger cluster around it.


Credit: Chandra X-ray Observatory

In some ways, this black hole resembles a beating heart that pumps blood outward into the body via the arteries. Likewise, a black hole can inject material and energy into its host galaxy and beyond.

A black hole has been "beating" about every 5 to 10 million years, pumping material and energy into its environment.
Credit: Chandra X-ray Observatory

By examining the details of the X-ray data from Chandra, scientists have found evidence for repeated bursts of energetic particles in jets generated by the supermassive black hole at the center of NGC 4696. These bursts create vast cavities in the hot gas that fills the space between the galaxies in the cluster. The bursts also create shock waves, akin to sonic booms produced by high-speed airplanes, which travel tens of thousands of light years across the cluster.

This composite image contains X-ray data from Chandra (red) that reveals the hot gas in the cluster, and radio data from the NSF's Karl G. Jansky Very Large Array (blue) that shows high-energy particles produced by the black hole-powered jets. Visible light data from the Hubble Space Telescope (green) show galaxies in the cluster as well as galaxies and stars outside the cluster.

Cavity processing scale: This image shows a larger field of view than the main composite image above and is about 122,000 light years across. This image has also been rotated slightly clockwise to the main composite image above.

Credit: Chandra X-ray Observatory

Astronomers employed special processing to the X-ray data (shown above) to emphasize nine cavities visible in the hot gas. These cavities are labeled A through I in an additional image, and the location of the black hole is labeled with a cross. The cavities that formed most recently are located nearest to the black hole, in particular the ones labeled A and B.

The researchers estimate that these black hole bursts, or "beats", have occurred every five to ten million years. Besides the vastly differing time scales, these beats also differ from typical human heartbeats in not occurring at particularly regular intervals.

Curved processing scale: This image also shows a larger field of view than the main composite image and is about 550,000 light years across. This image has also been rotated slightly clockwise to the main composite image.

Credit: Chandra X-ray Observatory

A different type of processing of the X-ray data (shown above) reveals a sequence of curved and approximately equally spaced features in the hot gas. These may be caused by sound waves generated by the black hole's repeated bursts. In a galaxy cluster, the hot gas that fills the cluster enables sound waves — albeit at frequencies far too low for the human hear to detect — to propagate. (Note that both images showing the labeled cavities and this image are rotated slightly clockwise to the main composite.)

The features in the Centaurus Cluster are similar to the ripples seen in the Perseus cluster of galaxies. The pitch of the sound in Centaurus is extremely deep, corresponding to a discordant sound about 56 octaves below the notes near middle C. This corresponds to a slightly higher (by about one octave) pitch than the sound in Perseus. Alternative explanations for these curved features include the effects of turbulence or magnetic fields.

The black hole bursts also appear to have lifted up gas that has been enriched in elements generated in supernova explosions. The authors of the study of the Centaurus cluster created a map showing the density of elements heavier than hydrogen and helium. The brighter colors in the map show regions with the highest density of heavy elements and the darker colors show regions with a lower density of heavy elements. Therefore, regions with the highest density of heavy elements are located to the right of the black hole. A lower density of heavy elements near the black hole is consistent with the idea that enriched gas has been lifted out of the cluster's center by bursting activity associated with the black hole. The energy produced by the black hole is also able to prevent the huge reservoir of hot gas from cooling. This has prevented large numbers of stars from forming in the gas.

A paper describing these results was published in the March 21st 2016 issue of the Monthly Notices of the Royal Astronomical Society and is available online. The first author is Jeremy Sanders from the Max Planck Institute for Extraterrestrial Physics in Garching, Germany.

NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.


Contacts and sources:
Megan Watzke
Chandra X-ray Observatory

Newly Discovered Exoplanet May Be Best Candidate in Search for Signs of Life

An exoplanet orbiting a red dwarf star 40 light-years from Earth may be the new holder of the title “best place to look for signs of life beyond the Solar System”. Using ESO’s HARPS instrument at La Silla, and other telescopes around the world, an international team of astronomers discovered a “super-Earth” orbiting in the habitable zone around the faint star LHS 1140. 

This world is a little larger and much more massive than the Earth and has likely retained most of its atmosphere. This, along with the fact that it passes in front of its parent star as it orbits, makes it one of the most exciting future targets for atmospheric studies. The results will appear in the 20 April 2017 issue of the journal Nature.

This artist’s impression shows the exoplanet LHS 1140b, which orbits a red dwarf star 40 light-years from Earth and may be the new holder of the title “best place to look for signs of life beyond the Solar System”. Using ESO’s HARPS instrument at La Silla, and other telescopes around the world, an international team of astronomers discovered this super-Earth orbiting in the habitable zone around the faint star LHS 1140. This world is a little larger and much more massive than the Earth and has likely retained most of its atmosphere.
Artist’s impression of the super-Earth exoplanet LHS 1140b
Credit: ESO/spaceengine.org


The newly discovered super-Earth LHS 1140b orbits in the habitable zone around a faint red dwarf star, named LHS 1140, in the constellation of Cetus (The Sea Monster). The habitable zone is defined by the range of orbits around a star, for which a planet possesses the appropriate temperature needed for liquid water to exist on the planet’s surface.

Red dwarfs are much smaller and cooler than the Sun and, although LHS 1140b is ten times closer to its star than the Earth is to the Sun, it only receives about half as much sunlight from its star as the Earth and lies in the middle of the habitable zone. The orbit is seen almost edge-on from Earth and as the exoplanet passes in front of the star once per orbit it blocks a little of its light every 25 days.

“This is the most exciting exoplanet I’ve seen in the past decade,” said lead author Jason Dittmann of the Harvard-Smithsonian Center for Astrophysics (Cambridge, USA). “We could hardly hope for a better target to perform one of the biggest quests in science — searching for evidence of life beyond Earth.”
"The present conditions of the red dwarf are particularly favourable — LHS 1140 spins more slowly and emits less high-energy radiation than other similar low-mass stars," explains team member Nicola Astudillo-Defru from Geneva Observatory, Switzerland.  Although the planet is located in the zone in which life as we know it could potentially exist, it probably did not enter this region until approximately forty million years after the formation of the red dwarf star. During this phase, the exoplanet would have been subjected to the active and volatile past of its host star. A young red dwarf can easily strip away the water from the atmosphere of a planet forming within its vicinity, leading to a runaway greenhouse effect similar to that on Venus.

This planet is located in the liquid water habitable zone surrounding its host star, a small, faint red star named LHS 1140. The planet weighs about 6.6 times the mass of Earth and is shown passing in front of LHS 1140. Depicted in blue is the atmosphere the planet may have retained.
Artist’s impression of the newly-discovered rocky exoplanet, LHS 1140b
Credit: M. Weiss/CfA

For life as we know it to exist, a planet must have liquid surface water and retain an atmosphere. When red dwarf stars are young, they are known to emit radiation that can be damaging for the atmospheres of the planets that orbit them. In this case, the planet's large size means that a magma ocean could have existed on its surface for millions of years. This seething ocean of lava could feed steam into the atmosphere long after the star has calmed to its current, steady glow, replenishing the planet with water.

The discovery was initially made with the MEarth facility, which detected the first telltale, characteristic dips in light as the exoplanet passed in front of the star. ESO’s HARPS instrument, the High Accuracy Radial velocity Planet Searcher, then made crucial follow-up observations which confirmed the presence of the super-Earth. HARPS also helped pin down the orbital period and allowed the exoplanet’s mass and density to be deduced.   This effort enabled other transit events to be detected by MEarth so that the astronomers could nail down the detection of the exoplanet once and for all.

The astronomers estimate the age of the planet to be at least five billion years. They also deduced that it has a diameter 1.4 times larger than the Earth — almost 18 000 kilometres. But with a mass around seven times greater than the Earth, and hence a much higher density, it implies that the exoplanet is probably made of rock with a dense iron core.

This artist’s impression video shows an imaginary trip to the exoplanet LHS 1140b, which orbits a red dwarf star 40 light-years from Earth and may be the new holder of the title “best place to look for signs of life beyond the Solar System”. Using ESO’s HARPS instrument at La Silla, and other telescopes around the world, an international team of astronomers discovered this super-Earth orbiting in the habitable zone around the faint star LHS 1140. This world is a little larger and much more massive than the Earth and has likely retained most of its atmosphere.


Credit: ESO/spaceengine.org

This super-Earth may be the best candidate yet for future observations to study and characterise its atmosphere, if one exists. Two of the European members of the team, Xavier Delfosse and Xavier Bonfils both at the CNRS and IPAG in Grenoble, France, conclude: “The LHS 1140 system might prove to be an even more important target for the future characterisation of planets in the habitable zone than Proxima b or TRAPPIST-1. This has been a remarkable year for exoplanet discoveries!” 

 The planet around Proxima Centauri (eso1629) is much closer to Earth, but it probably does not transit its star, making it very difficult to determine whether it holds an atmosphere. Unlike the TRAPPIST-1 system (eso1706), no other exoplanets around LHS 1140 have been found. Multi-planet systems are thought to be common around red dwarfs, so it is possible that additional exoplanets have gone undetected so far because they are too small.

In particular, observations coming up soon with the NASA/ESA Hubble Space Telescope will be able to assess exactly how much high-energy radiation is showered upon LHS 1140b, so that its capacity to support life can be further constrained.

Further into the future — when new telescopes like ESO’s Extremely Large Telescope are operating — it is likely that we will be able to make detailed observations of the atmospheres of exoplanets, and LHS 1140b is an exceptional candidate for such studies.



Contacts and sources: 
Richard Hook
ESO

This research was presented in a paper entitled “A temperate rocky super-Earth transiting a nearby cool star”, by J. A. Dittmann et al. to appear in the journal Nature on 20 April 2017.

Think Brain Games Make You Smarter? Think Again

Be skeptical of ads declaring you can rev up your brain’s performance by challenging it with products from the growing brain-training industry.

Science does not support many of the claims.

That’s according to a new study published in the science journal Frontiers in Aging Neuroscience from a team of Florida State University researchers.

Neil Charness, professor of psychology and a leading authority on aging and cognition, teamed up with Wally Boot, associate professor of psychology, and graduate student Dustin Souders to test the theory that brain games help preserve cognitive function.

Credit: Wikimedia Commons

“Our findings and previous studies confirm there’s very little evidence these types of games can improve your life in a meaningful way,” said Boot, an expert on age-related cognitive decline.

Charness, who’s also the director of FSU’s Institute for Successful Longevity, said an increasing number of people believe brain training helps protect them against memory loss or cognitive disorders.

“Brain challenges like crossword games are a popular approach, especially among baby boomers, as a way to try to protect cognition,” Charness said.

That popularity has turned the brain-training industry into a billion-dollar business. Brain games are available online and through mobile apps that typically sell for about $15 a month or $300 for lifetime memberships. But advertising for this rapidly growing business sector has sometimes used inflated claims. The Federal Trade Commission fined one brain-training company $50 million for false advertising, which was later lowered to $2 million.

Image result for brain training games
Credit: Flickr

“More companies are beginning to be fined for these types of inflated claims and that’s a good thing,” Boot said. “These exaggerated claims are not consistent with the conclusions of our latest study.”

The FSU team’s study focused on whether brain games could boost the “working memory” needed for a variety of tasks. In their study, they set up one group of people to play a specially designed brain-training video game called “Mind Frontiers,” while another group of players performed crossword games or number puzzles.

All players were given lots of information they needed to juggle to solve problems. Researchers tested whether the games enhanced players’ working memory and consequently improved other mental abilities, such as reasoning, memory and processing speed.

That’s the theory behind many brain games: If you improve overall working memory, which is fundamental to so much of what we do every day, then you can enhance performance in many areas of your life.

The team examined whether improving working memory would translate to better performance on other tasks or as the researchers called it: “far transfer.”

Screenshots of Mind Frontiers games
Mind Frontiers tasks.Screenshots of Mind Frontiers games: Top to bottom, left to right: Supply Run, Riding Shotgun, Sentry Duty, Safe Cracker, Irrigator, Pen ‘Em Up.
Credit: iOpen

In short, no.

“It’s possible to train people to become very good at tasks that you would normally consider general working memory tasks: memorizing 70, 80, even 100 digits,” Charness said. “But these skills tend to be very specific and not show a lot of transfer. The thing that seniors in particular should be concerned about is, if I can get very good at crossword puzzles, is that going to help me remember where my keys are? And the answer is probably no.”

Charness has spent much of his career the past 45 years trying to wrap his brain around the way the mind functions and how it ages. With the senior population continuing to grow — 45 million Americans are 65 or older — Charness understands their concerns about preserving brain function and remaining independent.

“People have real concerns about loss of cognition and loss of memory as they age, so they do all kinds of things to try to stave off cognitive decline,” Charness said.

Charness noted that other research finds aerobic exercise, rather than mental exercise, is great for your brain. Physical exercise can actually cause beneficial structural changes in the brain and boost its function. He predicts “exer-gaming,” which combines exercise with brain games, will increase in popularity in the 21st century.

“I wouldn’t come away from our article totally discouraged,” Charness said. “It’s another piece of the puzzle that we’re all trying to assemble. It’s discouraging in the sense that we can’t find far transfer and that seems to be a fairly consistent finding in research. But if your real goal is to improve cognitive function and brain games are not helping, then maybe you are better off getting aerobic exercise rather than sitting in front of the computer playing these games.”



Contacts and sources:
Florida State University

Citation: Evidence for Narrow Transfer after Short-Term Cognitive Training in Older Adults
Frontiers in Aging Neuroscience, 28 February 2017 | https://doi.org/10.3389/fnagi.2017.00041

New Study Ranks Hazardous Asteroid Effects from Least to Most Destructive

If an asteroid struck Earth, which of its effects--scorching heat, flying debris, towering tsunamis--would claim the most lives? A new study has the answer: violent winds and shock waves are the most dangerous effects produced by Earth-impacting asteroids.

The study explored seven effects associated with asteroid impacts--heat, pressure shock waves, flying debris, tsunamis, wind blasts, seismic shaking and cratering--and estimated their lethality for varying sizes. The researchers then ranked the effects from most to least deadly, or how many lives were lost to each effect.

This chart shows reported fireball events for which geographic location data are provided. Each event’s calculated total impact energy is indicated by its relative size and by a color.

Credit: NASA

Overall, wind blasts and shock waves were likely to claim the most casualties, according to the study. In experimental scenarios, these two effects accounted for more than 60 percent of lives lost. Shock waves arise from a spike in atmospheric pressure and can rupture internal organs, while wind blasts carry enough power to hurl human bodies and flatten forests.

"This is the first study that looks at all seven impact effects generated by hazardous asteroids and estimates which are, in terms of human loss, most severe," said Clemens Rumpf, a senior research assistant at the University of Southampton in the United Kingdom, and lead author of the new study published in Geophysical Research Letters, a journal of the American Geophysical Union.

Radar images of asteroid 2014 JO25 were obtained early Tuesday morning (April 18, 2017), with NASA's 70-meter antenna at the Goldstone Deep Space Communications Complex in California.
Radar Imagery of Asteroid 2014 JO25
Credit: NASA'

Rumpf said his findings, which he plans to present at the 2017 International Academy of Astronautics Planetary Defense Conference in Tokyo, Japan, could help hazard mitigation groups better prepare for asteroid threats because it details which impact effects are most dominant, which are less severe and where resources should be allocated.

Though studies like his are necessary to reduce harm, deadly asteroid impacts are still rare, Rumpf said. Earth is struck by an asteroid 60 meters (more than 190 feet) wide approximately once every 1500 years, whereas an asteroid 400 meters (more than 1,300 feet) across is likely to strike the planet every 100,000 years, according to Rumpf.

"The likelihood of an asteroid impact is really low," said Rumpf. "But the consequences can be unimaginable."

Modeling asteroid effects

Rumpf and his colleagues used models to pepper the globe with 50,000 artificial asteroids ranging from 15 to 400 meters (49 to 1312 feet) across--the diameter range of asteroids that most frequently strike the Earth. The researchers then estimated how many lives would be lost to each of the seven effects.

Land-based impacts were, on average, an order of magnitude more dangerous than asteroids that landed in oceans.

Large, ocean-impacting asteroids could generate enough power to trigger a tsunami, but the wave's energy would likely dissipate as it traveled and eventually break when it met a continental shelf. Even if a tsunami were to reach coastal communities, far fewer people would die than if the same asteroid struck land, Rumpf said. Overall, tsunamis accounted for 20 percent of lives lost, according to the study.

The heat generated by an asteroid accounted for nearly 30 percent of lives lost, according to the study. Affected populations could likely avoid harm by hiding in basements and other underground structures, Rumpf said.

Seismic shaking was of least concern, as it accounted for only 0.17 percent of casualties, according to the study. Cratering and airborne debris were similarly less concerning, both garnering fewer than 1 percent of deaths.

The trace left in the sky by the meteor that broke up over Chelyabinsk, Russia, in 2013. A new study explored seven effects associated with asteroid impacts — heat, pressure shock waves, flying debris, tsunamis, wind blasts, seismic shaking and cratering — and estimated their lethality for varying sizes.

Credit: Alex Alishevskikh

Only asteroids that spanned at least 18 meters (nearly 60 feet) in diameter were lethal. Many asteroids on the lower end of this spectrum disintegrate in Earth's atmosphere before reaching the planet's surface, but they strike more frequently than larger asteroids and generate enough heat and explosive energy to deal damage. For example, the meteor involved in the 2013 impact in Chelyabinsk, Russia, was 17 to 20 meters (roughly 55 to 65 feet) across and caused more than 1,000 injuries, inflicting burns and temporary blindness on people nearby.

Understanding risk

"This report is a reasonable step forward in trying to understand and come to grips with the hazards posed by asteroids and comet impactors," said geophysicist Jay Melosh, a distinguished professor in the Department of Earth, Atmospheric and Planetary Sciences at Purdue University in Lafayette, Indiana.

Melosh, who wasn't involved in the study, added that the findings "lead one to appreciate the role of air blasts in asteroid impacts as we saw in Chelyabinsk." The majority of the injuries in the Chelyabinsk impact were caused by broken glass sent flying into the faces of unknowing locals peering through their windows after the meteor's bright flash, he noted.

The 15,000th near-Earth asteroid discovered is designated 2016 TB57. It was discovered on Oct. 13, 2016, by observers at the Mount Lemmon Survey, an element of the NASA-funded Catalina Sky Survey in Tucson, Arizona.
Diagram of asteroid path
Credits: NASA/JPL-Caltech

The study's findings could help mitigate loss of human life, according to Rumpf. Small towns facing the impact of an asteroid 30 meters across (about 98 feet) may fare best by evacuating. However, an asteroid 200 meters wide (more than 650 feet) headed for a densely-populated city poses a greater risk and could warrant a more involved response, he said.

"If only 10 people are affected, then maybe it's better to evacuate the area," Rumpf said. "But if 1,000,000 people are affected, it may be worthwhile to mount a deflection mission and push the asteroid out of the way."

Trojan asteroids are common at the L4 and L5 Lagrange points of other planets, leading or following the planet in its orbit. But detecting our own Trojan asteroids from Earth is difficult since they appear close to the sun from our perspective. In mid-February 2017, NASA's OSIRS-REx mission will search for these elusive objects when the spacecraft passes by Earth's L4 Lagrange point, en route to asteroid Bennu in 2018.




Contacts and sources:
Nanci Bompey 
The American Geophysical Union


Citation: “Asteroid impact effects and their immediate hazards for human populations”
Authors: Clemens M. Rumpf, Hugh G. Lewis: University of Southampton, Engineering and the Environment, Southampton, United Kingdom; Peter M. Atkinson: Lancaster University, Faculty of Science and Technology, Lancaster, United Kingdom; University of Southampton, Geography and Environment, Southampton, United Kingdom; Queen’s University Belfast, School of Geography, Archaeology and Palaeoecology, Belfast, United Kingdom.