Apr 9, 2016

The missing brown dwarfs

Possible manifestations of brown dwarfs (artist's impression). As brown dwarfs are nearly invisible in the optical light and only emit radiation in the IR regime, they exhibit different colors in that range.
When re-analysing catalogued and updated observational data of brown dwarfs in the solar neighbourhood, astronomers from Potsdam have found that a significant number of nearby brown dwarfs should still be out there, awaiting their discovery. The corresponding study by Gabriel Bihain and Ralf-Dieter Scholz from the Leibniz Institute for Astrophysics Potsdam (AIP) challenges the previously established picture of brown dwarfs in the solar neighbourhood.

Brown dwarfs are objects that are too large to be called planets, yet too small to be stars. Having a mass of only less than seven per cent of the mass of the Sun, they are unable to create sufficient pressure and heat in their interiors to ignite hydrogen-to-helium fusion, a fundamental physical mechanism by which stars generate radiation. In this sense brown dwarf are "failed stars." It is therefore important to know how many brown dwarfs really exist in different regions of the sky in order to achieve a better understanding of star formation and of the motion of stars in the Milky Way.

Gabriel Bihain and Ralf-Dieter Scholz have taken a careful look at the distribution of nearby known brown dwarfs from a point of view that was not looked at before. To their surprise they discovered a significant asymmetry in the spatial configuration, strongly deviating from the known distribution of stars.

"I projected the nearby brown dwarfs onto the galactic plane and suddenly realized: half of the sky is practically empty! We absolutely didn't expect this, as we have been looking at an environment that should be homogeneous.," Gabriel Bihain explained. Seen from Earth, the empty region overlaps with a large part of the northern sky.

The scientists concluded that there should be many more brown dwarfs in the solar neighbourhood that are yet to be discovered and that will fill the observed gap. If they are right, this would mean that star formation fails significantly more often than previously thought, producing one brown dwarf for every four stars. In any case, it appears, the established picture of the solar neighbourhood and of its brown dwarf population will have to be rethought.

"It is quite possible that not only brown dwarfs are still hiding in the observational data, but also other objects with even smaller, planetary-like masses. So it is definitely worth it to take another deep look at both existing and future data.," Ralf-Dieter Scholz concluded.

From Science Daily

Clathrate ices identified in comet 67P

Southwest Research Institute scientists led an international team studying the composition of comet 67P's coma to better understand the ice structures and the possible origin of its nucleus. The team found evidence of water ice clathrates that could indicate the comet formed closer to the Sun than originally thought.
For decades, scientists have agreed that comets are mostly water ice, but what kind of ice -- amorphous or crystalline -- is still up for debate. Looking at data obtained by ESA's Rosetta spacecraft in the atmosphere, or coma, around comet 67P/Churyumov-Gerasimenko, scientists at Southwest Research Institute (SwRI) are seeing evidence of a crystalline form of ice called clathrates.

"The structure and phase of the ice is important because it tells us a lot about how and where the comet may have formed," says Dr. Adrienn Luspay-Kuti, a research scientist in SwRI's Space Science and Engineering Division. She is the lead author of a paper titled "The presence of clathrates in comet 67P/Churyumov-Gerasimenko" published in the April 8 issue of the journal Science Advances. "If the building blocks of 67P were predominantly crystalline ices and clathrates, then 67P likely agglomerated from chunks of ice closer to the Sun. The protosolar nebula closer to the Sun experienced higher temperatures and more turbulence where crystalline ices could form as the nebula cooled. More pristine amorphous ices likely dominated the colder outskirts of the rotating disk of dust and gas that surrounds the core of a developing solar system."

Amorphous water ice efficiently traps large amounts of volatile compounds, which are released simultaneously upon warming. Water clathrates are crystalline structures containing gas molecules. The volatiles locked inside the water actually create the stable clathrate structure. These structures release gases at characteristic temperatures, dependent on the gas-phase volatile locked inside the clathrate. Luspay-Kuti led an international team of cometary experts that interpreted Rosetta spacecraft data, and found that the observed outgassing pattern indicates the nucleus of 67P contains clathrates.

"Without direct sampling of the nucleus interior, evaluating the composition of the coma provides the best clues about the ice structure and, as a result, the possible origin of cometary nuclei," said Luspay-Kuti. "Thought to closely reflect the composition of the building blocks of our solar system, comets carry important information about the prevalent conditions in the solar nebula before and after planet formation. These small icy bodies help us understand the big picture."

The multi-institute team of cometary scientists analyzed mass spectrometer data from the southern region of 67P from September to October 2014, before equinox. 67P is a Jupiter family comet thought to originate from the Kuiper Belt. Scientists are comparing these new data with data from the flyby of Hartley 2 -- considered cometary kin in family and origin to 67P -- and finding correlations. If these comets formed closer to the Sun than originally thought, these data could help refine solar system formation models.

From Science Daily

Transcranial direct current stimulation can boost language comprehension

Transcranial direct current stimulation (tDCS) can alter our language processing, allowing for faster comprehension of meaningful word combinations, according to new research.
How the human brain processes the words we hear and constructs complex concepts is still somewhat of a mystery to the neuroscience community. Transcranial direct current stimulation (tDCS) can alter our language processing, allowing for faster comprehension of meaningful word combinations, according to new research from the department of Neurology the Perelman School of Medicine at the University of Pennsylvania. The work is published in the Journal of Neuroscience.

"Integrating conceptual knowledge is one of the neural functions fundamental to human intelligence," said the study's first author Amy Price, a neuroscience graduate student at Penn. "For example, when we read or listen to a sentence, we need to combine, or integrate, the meaning of the words to understand the full idea of the sentence. We perform this process effortlessly on a daily basis but it is quite a complex process and little is known about the brain regions that support this ability."

Semantic memory is our stored knowledge about the world, such as the meaning of words and objects. "We sought to understand how and in what part of the brain semantic representations are integrated into more complex ideas" said senior author Roy Hamilton, MD, MS, an assistant professor in the departments of Neurology and Physical Medicine & Rehabilitation, and director of the Laboratory for Cognition and Neural Stimulation at Penn. Recent findings from functional MRI scans (fMRI) and magnetoencephalography (MEG) have suggested the angular gyrus, a region of the brain known to be involved in language, number processing and spatial cognition, memory retrieval and attention, as a potential hub for semantic memory integration, specifically the left angular gyrus.

Hamilton and team, which also included Jonathan Peelle PhD, an assistant professor in the Department of Otolaryngology at the Washington University School of Medicine, Michael Bonner, PhD, a postdoctoral fellow in the Department of Psychology at Penn, and Murray Grossman, MD, EdD, professor of Neurology and director of the Penn Frontotemporal Dementia Center, looked at the role of the left angular gyrus in semantic memory by applying high definition tDCS in healthy adults to modulate neural activity and determine its effect on semantic integration. This was done using three separate brain stimulation sessions in 18 healthy adults. Subjects donned the tDCS stimulation cap equipped with electrodes that stimulated the left angular gyrus or the right angular gyrus, as well as applied a fake form of stimulation known as sham stimulation as a control. After each stimulation session, subjects were presented with word pairs that could to be semantically integrated into coherent, or meaningful, combinations -- such as "plaid jacket" and another set of word pairs that formed non-coherent, or non-meaningful combinations- such as "fast blueberry."

This was followed by a letter task that served as a control for brain stimulation affects on vision and attention, in which subjects looked at non-pronounceable strings of letters -- such as vsbsl vsbql -- and were asked to indicate whether or not the letter strings matched.

Results showed that stimulation to the left angular gyrus resulted in a faster comprehension of meaningful relative to non-meaningful word pairs when compared with both sham and right angular gyrus stimulation. This same effect was not produced in the letter-string task, showing that these findings cannot be easily attributed to non-specific effects on attention, motor control or low-level visual processing.

Read more at Science Daily

Apr 8, 2016

Frog in Sweden Grows Faster in Warmer Weather

A frog in Swedish waters has a neat trick: It speeds up its growth rate when the weather is warmest during breeding season, in a country where “warm” doesn’t last too long for that kind of thing.

The animal is the pool frog (Pelophylax lessonae), an amphibian that needs enough relative warmth to allow its tadpoles to develop as they should. And it’s found a way to make hay — or growth, that is — while the Swedish sun is shining, according to a pair of scientists from Sweden’s Uppsala University.

In a study published in the journal Evolutionary Applications, the researchers describe the frog’s ability to grow faster when the temperature rises.

The duo collected frog spawn, during their breeding seasons, from Baltic Sea regions in Poland, Latvia, and Sweden.

Using two rooms – one set to a low temperature for the species (19 degrees C.) and one to a higher temperature (26 degrees C.) – the scientists tested the growth rates of the spawn by breeding the tadpoles from the three countries.

The Uppsala scientists found that tadpoles from all three Swedish, Polish, and Latvian regions grew at the same rate under the lower temperature, but in the higher temperature the Swedish tadpoles grew faster than did the central European (Latvian and Polish) variety.

In Sweden, the pool frog doesn’t even think about breeding until the middle or latter part of May, when temperatures hit at least 16 degrees C., say the researchers.

“The period of time that these frog larvae have for development at northern latitudes is very limited,” said study co-author Germán Orizaola in a statement.

“Since Sweden has briefer periods of high temperatures than Poland and Latvia do,” he explained, “this increased growth capacity under warm conditions allows this frog to take full advantage of the short periods of high temperatures.”

“As a result,” Orizaola said, “it is able to complete its life cycle — which relies heavily on warm temperatures — at high latitudes such as in Scandinavia.”

Read more at Discovery News

Isaac Newton Alchemy Manuscript Going Online

A 17th-century manuscript written by Sir Isaac Newton that was held in a private collection for decades is being placed online, offering a fascinating glimpse into the work of the celebrated physicist.

The rediscovered document is Newton’s handwritten copy of a manuscript by alchemist George Starkey detailing the preparation of “sophick mercury,” viewed as an essential element in producing the so-called “philosopher’s stone” for turning base metals into gold.

Philadelphia-based nonprofit the Chemical Heritage Foundation bought the manuscript in February and is placing digital images and transcriptions of the text into an online database for study.

“The significance of the manuscript is that it helps us understand Newton’s alchemical reading–especially of his favorite author — and gives us evidence of one more of his laboratory procedure,” explained James Voelkel, curator of rare books at the Othmer Library of Chemical History, in a statement emailed to FoxNews.com. Voelkel notes that there are scores and scores of Newton’s alchemical manuscripts by Newton, who wrote an estimated 1,000,000 words of notes on alchemy during his lifetime. “Our manuscript is just one among these,” he added.

Starkey, writing in Latin as Eirenaeus Philalethes, published a text on the preparation of sophick mercury in 1678. Newton’s manuscript, however, is a copy of another Starkey manuscript, not the printed text – it may even predate the published version. “We can tell this from Newton’s comments in square brackets that either expand abbreviations in the other manuscript or correct it,” Voelkel explained.

Newton also wrote unrelated notes on the distillation of iron ore on the back of the manuscript bought by the Chemical Heritage Foundation. The notes “may well be laboratory notes of a process Newton had tried or was thinking of trying,” said Voelkel. “Like many of us, when Newton needed a place to jot something down, he would sometimes just turn over a manuscript and write on the blank page on the back.”

Read more at Discovery News

Neanderthal Y Chromosome Not Seen in Men

Modern men have no traces of Neanderthal DNA on their Y chromosome, the first-ever analysis of the male Neanderthal sex chromosome has revealed.

The disappearance of the Neanderthal Y chromosome may be due to genetic incompatibilities between the two species that led to miscarriages, suggests a study published today in the American Journal of Human Genetics.

The Y chromosome is passed exclusively from father to son.

Until now, all sequencing of the Neanderthal genome had been done on females because those happened to be the specimens that provided enough good-quality DNA, the study's lead author, Dr. Fernando Mendez of Stanford University, said.

"Characterising the Neanderthal Y chromosome helps us to better understand the population divergence that led to Neanderthals and modern humans," he said.

"It also enables us to explore possible genetic interactions between archaic and modern variants within hybrid offspring."

It is widely known that modern non-Africans have around 2.5 to 4 per cent Neanderthal DNA in their genes, but the Y chromosome is special, Dr Mendez said.

"Either you get the whole Y chromosome, or you get nothing," he said.

Analysis compared ancient and modern Y chromosomes

Dr Mendez and his colleagues compared the Y chromosome of a 49,000 year-old Neanderthal male found in El Sidron in Spain, with the Y chromosome from two modern humans.

Their analysis supports earlier data that estimated Neanderthals and modern humans diverged from their common ancestor around 588,000 years ago.

They also found the Neanderthal Y chromosome was distinct from any Y chromosome observed in modern humans, suggesting the lineage is extinct.

The researchers then searched for evidence that would explain why the Neanderthal Y chromosome disappeared.

"The Y chromosome has a number of genes that are specific for male functions, like making sperm, so we said maybe we'd find something in one of those, but we didn't," Dr Mendez said.

These genes did contain mutations that distinguished Neanderthals from modern humans, but none would have adversely affected their function.

Genetic incompatibility may have caused miscarriages

But the team identified mutations on three genes on the Neanderthal Y chromosome connected to immune factors called the minor histocompatibility antigens.

When these antigens, which are only found in males, are mismatched they can cause women to reject organ transplants from men as well as have miscarriages after the birth of their first child, Mendez said.

This may have had serious consequences for the offspring of Neanderthal and modern human interbreeding; a male foetus could have sensitised his mother's immune system so any subsequent male offspring would be at greatly increased risk of being miscarried.

"If they have fewer boys than other couples, then systematically boys are likely to have fewer boys," said Mendez.

Over time the Neanderthal Y chromosome would be lost in favour of the modern human Y chromosome.

However, Mendez stressed this was still only a hypothesis.

"The amount of Neanderthal DNA in modern humans nowadays is relatively low so it could have been lost by drift," he said.

But reduced fertility or viability of hybrid offspring with Neanderthal Y chromosomes is consistent with an observation known as Haldane's rule.

Read more at Discovery News

Pope's Guidelines on Love, Sex and Marriage

Pope Francis has issued hotly-anticipated new guidelines on the Church’s approach to family life after two years of consultations with the world’s bishops. Here are some of the main points:

- Homosexuality -

Francis slaps down proposals to place gay unions on the same level as marriage, saying bishops found “there are absolutely no grounds for considering homosexual unions to be in any way similar or even remotely analogous to God’s plan for marriage and family.”

He also slams external pressure on churches to change their position and says it is “unacceptable” that “international bodies should make financial aid to poor countries dependent on the introduction of laws to establish ‘marriage’ between persons of the same sex.”

The pope offered sympathy to those families with gay relatives, “a situation not easy for parents or for children,” and said the Church must avoid “every sign of unjust discrimination” towards homosexuals.

- Cohabitation -

Francis says couples who live together outside of marriage “need to be welcomed and guided, patiently and discreetly,” and the choice to cohabit may be based on external factors such as financial difficulties or cultural situations.

- Remarried divorced people -

“They are not excommunicated and should not be treated as such,” and should be made to feel part of the Church “while avoiding any occasion of scandal.” The pope says the Christian community caring for such people “is not to be considered a weakening of its faith” but a sign of “its charity.”

- Broken marriages -

Pastors should judge situations on a case-by-case basis: “we know that no ‘easy recipes’ exist.”

- Children -

Offspring should be taught to say “Please,” “Thank you” and “Sorry,” they should be punished for misbehavior, cured of the vice of “wanting it all now” and prevented from watching television programs which undercut family values.

Read more at Discovery News

Kepler's New Mission: To Hunt Strange Orphan Worlds

After an unprecedented survey to look for Earth-like planets beyond the solar system, NASA’s Kepler space telescope this week begins a search for free-flying planets to learn just how common orphan worlds may be.

Planets without host stars are difficult to find, but they do exist. Scientists believe these bodies were ejected from their solar system families due to gravitational dynamics, lured away by tidal forces from interloping passersby, or perhaps even formed without the benefit of a parent star. What they don’t know is if orphan planets are common or not.

To find the free-flying worlds, astronomers are turning to a technique known as microlensing, which occurs when the background light of a star is distorted due to the gravitational effects of another, unseen body located between the star and the observing telescope.

“For a lensing event that’s due to a just a single object, the most salient feature of the light curve is the time scale. In general, a shorter time scale is potentially indicative of a lower-mass lensing object,” said astronomer Calen Henderson, with NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

The time scale for a lensing event caused by a free-floating planet may last just days or even hours, he added.

“If you’re just monitoring one star, it’s very, very rare to capture a microlensing event. That would only happen once per individual star every maybe 300,000 years,” Henderson told Discovery News.

“It’s a fishing expedition. Microlensing events are rare. They’re unpredictable and so what microlensing surveys have done for decades is just try to play the numbers game,” he said.

Ongoing ground-based surveys boost the odds of capturing a microlensing event by focusing on tens of millions or even hundreds of millions of stars, looking for targets that brighten within short time periods.

While some variations in a star’s brightness are due to stellar flares or because the star is what is known as a cataclysmic variable and periodically erupts, other changes are caused by unseen bodies in the foreground warping the light of the background star.

“What we’re going to try to do with K2 is look for those events that are due to a lensing system that is just a free-floating planet,” Henderson said.

To accomplish that, the K2 team will work in conjunction with ground-based surveys to try to get two perspectives of a lensing event, which will allow astronomers to calculate the mass what is causing the lensing.

Read more at Discovery News

Apr 7, 2016

When will a neutron star collapse to a black hole?

Neutron stars are the most extreme and fascinating objects known to exist in our universe: Such a star has a mass that is up to twice that of the sun but a radius of only a dozen kilometres: hence it has an enormous density, thousands of billions of times that of the densest element on Earth. An important property of neutron stars, distinguishing them from normal stars, is that their mass cannot grow without bound. Indeed, if a nonrotating star increases its mass, also its density will increase. Normally this will lead to a new equilibrium and the star can live stably in this state for thousands of years. This process, however, cannot repeat indefinitely and the accreting star will reach a mass above which no physical pressure will prevent it from collapsing to a black hole. The critical mass when this happens is called the "maximum mass" and represents an upper limit to the mass that a nonrotating neutron star can be.

However, once the maximum mass is reached, the star also has an alternative to the collapse: it can rotate. A rotating star, in fact, can support a mass larger than if it was nonrotating, simply because the additional centrifugal force can help balance the gravitational force. Also in this case, however, the star cannot be arbitrarily massive because an increase in mass must be accompanied by an increase in rotation and there is a limit to how fast a star can rotate before breaking apart. Hence, for any neutron star there is an absolute maximum mass and is given by the largest mass of the fastest-spinning model.

Determining this value from first principles is difficult because it depends on the equation of state of the matter composing the star and this is still essentially unknown. Because of this, the determination of the maximum rotating mass of a neutron star has been an unsolved problem for decades. This has changed with a recent work published on Monthly Notices of the Royal Astronomical Society, where it has been found that it is indeed possible to predict the maximum mass a rapidly rotating neutron star can attain by simply considering what is maximum mass of corresponding the nonrotating configuration.

"It is quite remarkable that a system as complex as a rotating neutron star can be described by such a simple relation," declares Prof. Luciano Rezzolla, one of the authors of the publication and Chair of Theoretical Astrophysics at the Goethe University in Frankfurt. "Surprisingly, we now know that even the fastest rotation can at most increase the maximum mass of 20% at most," remarks Rezzolla.

Although a very large number of stellar models have been computed to obtain this result, what was essential in this discovery was to look at this data in proper way. More specifically, it was necessary to realise that if represented with a proper normalisation, the data behaves in a universal manner, that is, in a way that is essentially independent of the equation of state.

"This result has always been in front of our eyes, but we needed to look at it from the right perspective to actually see it," says Cosima Breu, a Master student at the University of Frankfurt, who has performed the analysis of the data during her Bachelor thesis.

Read more at Science Daily

Insect Panama Papers? Corruption Exists Among Animals, Too

Humans are a cooperative species by nature, but no doubt there are many individuals who prioritize their own interests to the detriment of the greater good. Look no further than the recent news around the “Panama Papers,” a 2.6-terabyte data leak from the law firm Mossack Fonseca documenting how companies, political leaders, wealthy individuals and even criminals hide their assets.

Corruption isn’t exclusively a human vice, though; animals do it, too. Even eusocial species — highly organized, cooperative animals that share in the responsibility of raising offspring and have a clear division of labor — will cheat each other when given the opportunity.

Take ants, for example. A model of cooperation in the animal kingdom, ants cluster into highly organized colonies, with labor divided among workers, soldiers, drones and a queen. A 2008 study on leaf-cutter ants published in the Proceedings of the National Academy of Sciences, however, found the ant world rampant with cheating and corruption.

How exactly does an ant cheat the system to get ahead? While researchers had believed that all larvae had the opportunity to develop into queens so long as they were fed certain foods, DNA fingerprinting found that the offspring of some ant fathers were more likely to become queens than others, according to biologist Bill Hughes, then of the University of Leeds. These ants possess a “royal” gene that gives them an advantage over other ants, cheating the others out of a chance to become queens.

These royal genes are exceedingly rare within an ant colony, “an evolutionary strategy by the cheaters to escape suppression by the altruistic masses they exploit,” Hughes said.

Bees aren’t much better. Like ants, bees exist in stratified societies, separated across workers, drones and a queen. Offspring within a colony are produced entirely by the queen, a kinship meant to hold together bees’ social structure — or at least that’s how it’s supposed to work.

According to a 2009 study published in Molecular Ecology, worker bees within the species Melipona scutellaris, a stingless Brazilian bee, will reproduce behind the queen’s back. The study, which examined the lineage of 600 males across 45 colonies, found that nearly a quarter of the bees were sons of workers rather than the queen. Rather than cooperating, the workers were instead in conflict with their queen.

Reproduction isn’t really about passing genes on to the next generation in this case. Instead, worker bees that are reproducing live almost three times longer than those that don’t, nearly matching the life expectancy of the queen. The reason why is that reproducing worker bees usually do a lot less work and avoid potentially dangerous tasks like foraging. The individual benefits for reproductive worker bees come at a cost for the entire colony, of course. The more worker bees there are reproducing, the lower the collective production of the colony and the worse off everyone is.

This reproductive tug-of-war between workers and queens isn’t unique to Melipona scutellaris. A 2013 study on honeybees (Apis mellifera) found evidence of a similar conflict.

Read more at Discovery News

Rare Bronze Incense Shovel Found in Israel

On the western shore of the Sea of Galilee in Israel, archaeologists report that they have uncovered a rare decorated bronze incense shovel and bronze jug.

The artifacts were unearthed at a site called Magdala, a large Jewish settlement that dates to about 2000 years ago— the Early Roman period— where archaeologists have already discovered ancient streets, ritual baths, a marketplace, a mosaic-floored synagogue, and the famous Magdala stone.

“The incense shovel that was found is one of ten others that are known in the country from the Second Temple period,” Dina Avshalom-Gorni, chief archaeologist for the Israel Antiquities Authority, said in a statement.

The incense shovel could have been used for rituals, like handling embers used in ceremonies, but it also might have had a practical, daily use as well, Avshalom-Gorni said. Both the shovel and the bronze jug were found on the floor of a storehouse, near the site’s docks, and could have been a family’s heirlooms.

Arfan Najar, an archaeologist with Israel Antiquities Authority, referred to the incense shovel as “a very rare find.” Similar shovels have been found in other locations in Israel, she said.

According to the Israel Antiquities Authority, Magdala— the ancient site where artifacts were uncovered— once served as a military base in the Jewish-Roman conflict, and in the Christian tradition, it’s known as the birthplace of Mary Magdalene.

From Discovery News

Life's Building Blocks Created on Lab-Grown Comet

Mix water, methanol and ammonia at low temperatures and low pressure, irradiate with ultraviolet light and what do you get?

A residue of organics, which when warmed to room temperature, contains ribose and other sugars that are believed to be building blocks for RNA and DNA, molecules essential for all known forms of life.

The experiment suggests that ribose and similarly structured sugars such as arabinose, xylose and lyxose could assemble under the chemical and temperature conditions of cosmic ices during the solar system's formation.

“The identification of ribose and related sugar molecules in the simulated cometary ice is new and entirely unexpected,” astrochemist Cornelia Meinert, with the University of Nice Sophia Antipolis in Nice, France, wrote in an email to Discovery News.

The discovery, she added, “is relevant for many theories on the origin of life.”

The experiment, reported in this week’s Science, stems from work to develop an organics detector for the Philae comet lander, which was dispatched by Europe’s Rosetta spacecraft to the surface of Comet 67P/Churyumov-Gerasimenko in November 2014.

Philae didn’t find ribose on the comet, but it did detect three organic compounds that also turned up in the lab samples.

“The detection of ribose is really exciting and provides insight into the prebiotic origin of a critical compound needed for life,” said University of Washington astronomer Donald Brownlee, who was not involved in the research.

“In the first few million years the outer regions of the solar system contained massive quantities of ice-coated dust grains and the proposed UV irradiation of these grains is surely an important source of organic materials. It seems like a wonderful gift from nature, that this process can produce ribose. We might not be here without it,” Brownlee wrote in an email to Discovery News.

Scientists do not know how life began on Earth, but many theorize that key ingredients came from comets and asteroids crashing into the developing planet.

“I am sure that (ribose) can survive atmospheric entry,” Brownlee added.

“Meteorites get hot on their surfaces but not in their interiors. If they are rocky materials, they are like Baked Alaskas. It is likely some cosmic dust particles from comets could also carry ribose through the atmosphere. A very interesting question is if Earth could make ribose or other critical molecules or whether it has to come from somewhere else. Irradiation of frozen volatiles is a natural process in space, but it does not easily occur on Earth,” Brownlee said.

Read more at Discovery News

Mystery Fast Radio Burst Caused By Flashing Black Hole

The true nature of mysterious fast radio bursts (FRBs) may not have been revealed after all.

These energetic eruptions seem to pop up in random locations in the cosmos and they appear and disappear in a matter of milliseconds, making them exceedingly hard to pinpoint. Until February, only a handful of definitive FRB signals had been uncovered in archival radio data. As these signals were recorded months or years in the past, follow-up observations were all but impossible, leaving the source of these flashes steeped in mystery.

But that was until the Australian 64-meter Parkes Radio Telescope got lucky and spotted an FRB erupt. Immediately, a collaboration of international astronomers were notified and other observatories slewed into the direction of the burst, zooming-in on its radio afterglow. The Japanese Subaru telescope on Mauna Kea in Hawaii was then able to zero-in on the burst’s location and identify a galaxy as the source.

Very quickly the collaboration made some conclusions based on the information they could gather from the source. The galaxy was an old elliptical located around 6 billion light-years from Earth. This galaxy shows little sign of star formation, so it was pretty clear that FRBs (at least in this isolated case) probably aren’t related to star formation processes.

The FRB signal, dubbed “FRB 150418″, was even used to test some of our models of the cosmos — through the analysis of the signal and knowing where it had some from, astrophysicists were able to measure the cosmic expansion and the quantity of dark matter the radio emission traveled through.

Although much hope was pinned on the February event being evidence of a new cosmic phenomenon, concerns from the astronomical community quickly surfaced: Was FRB 150418 really an FRB? Or was it a known phenomenon masquerading as the mysterious pulse?

In a new study accepted for publication in the Astrophysical Journal Letters, Harvard astronomers Peter Williams and Edo Berger think that this particular signal was actually a case of mistaken identity and the real source of FRBs remains a mystery.

Using the NSF’s Jansky Very Large Array in New Mexico, Williams and Berger was able to gather radio data from the suspect galaxy that produced FRB 150418 and they detected even more radio pulses. FRBs are thought to be one-shot deals; they flash, generating a huge energy output for a few milliseconds and then they disappear. This galaxy, however, was still generating flashes of radio emissions, some as powerful as the measurements of FRB 150418′s radio afterglow.

“What the other team saw was nothing unusual,” said Berger in a statement. “The radio emission from this source goes up and down, but it never goes away. That means it can’t be associated with the fast radio burst.”

Read more at Discovery News

Apr 6, 2016

Stone Age Humans Brought Deer to Scotland by Sea

Stone Age humans populated the Scottish islands with red deer transported “considerable distances” by boat, said researchers Wednesday who admitted surprise at our prehistoric ancestors’ seafaring prowess.

DNA analysis revealed that deer on Scotland’s northermost islands were unlikely to have come from the closest and seemingly most obvious places — mainland Scotland, Ireland or Norway, said a study in the Royal Society journal Proceedings of the Royal Society B.

“Our results imply that Neolithic humans were transporting deer considerable distances, by sea, from an unknown source” some 4,500-5,500 years ago, co-author David Stanton of Cardiff University told AFP by email.

“These results are surprising… The evidence suggests that we have misunderstood our relationship with this species,” he added.

“Perhaps humans managed deer, having long-term relationships with herds that allowed them to plan, capture and transport deer on longer voyages.”

It was known that late Stone Age humans had transported cattle, sheep and pigs by boat, but not large wild animals, and not over such vast distances.

Red deer, said Stanton, were central to life in Britain from the end of the last Ice Age about 11,000 years ago to the arrival of the first late Stone Age farmers.

The animals provided crucial nourishment, skins, sinew, bones and antlers — used to till the soil, among other things.

Scientists say all animals, including deer, found on the islands today must have been introduced by seafaring people.

The islands were covered in ice during the last “glacial maximum”, a period of deep Earth freeze, and have since been separated from each other and the mainland by spans of ocean too wide for deer to swim.

It was therefore thought the deer must have been brought from nearby, possibly from mainland Scotland, boat-hopping from island to island with short spurts of swimming in between.

Read more at Discovery News

Preserved Poop Points Way to Hannibal's Path

The question of precisely where the historically acclaimed general Hannibal and his army crossed the Alps into Italy to defeat the Romans — during the Second Punic War, around 218 to 201 B.C. — has perplexed historians for nearly 2,000 years.

Thanks to a new study, the first evidence pointing to an answer has finally been unearthed. Clues to Hannibal’s secret military route were recently discovered — not in maps or letters, but in the geologic record.

But it wasn’t exactly rocks that revealed the full story. Scientists dug up signs of Hannibal’s passage in preserved poop deposits, from a churned-up stretch of boggy terrain that likely served as a watering hole and toilet for the army’s resting animals.

Even the ancient Romans couldn’t agree on where Hannibal’s crossing took place, and scholars around the world have debated the topic over the thousands of years since. Some proposed that the general traced a route through a narrow mountain pass called Col de la Traversette, to the southwest of Turin, Italy, but they couldn’t produce any archaeological proof.

Solid evidence

Chris Allen, of Queen’s University Belfast, and William Mahaney, of York University in Toronto, were conducting research near Col de la Traversette that was unrelated to Hannibal. That’s when the 2,000-year-old question about the general’s Alps route confronted them in the shape of a mire, a waterlogged area along the mountain passage, Allen told Live Science.

It occurred to them that Hannibal’s army — which included 30,000 troops, 37 elephants and an estimated 15,000 to 20,000 horses — would have needed to stop for water during their travels.

And then, another colleague mentioned to Allen that when animals drink, they typically defecate.

“We realized if we were lucky enough in this mire to find a layer of sediment that was old enough and hadn’t been disturbed, we might actually be able to find evidence of horse manure that would have been left by his army when they passed through,” said Allen, an associate professor of environmental microbiology.

“A mass animal deposition”

The researchers excavated a cylindrical sample of soil called a core. They used carbon dating to establish that its layers dated back 8,000 years and examined changes — physical, chemical and microbial — that appeared in the dirt layers over time.

As they came close to the point in time when Hannibal was known to have crossed the Alps, unusual indicators appeared in the soil. The dirt was physically churned up, as though a number of animals had plodded through. Chemical analysis identified organic materials that typically inhabit a human’s or a horse’s gut, while DNA analysis revealed the presence of microbes associated with horse manure.

“By combining all these methods, we were able to point strongly to the fact that there was an accumulation of fecal materials at the correct date, about 2,200 years ago,” Allen said. The quantity of dung appearing at that point in time hints at an animal presence that was unusual for the region, but was also likely to be associated with Hannibal, who was already known to be on the move across the Alps during that time, the authors suggested.

Read more at Discovery News

Half of Natural Heritage Sites Threatened by Industry

Almost half of all natural World Heritage Sites, including the Great Barrier Reef and Machu Picchu, are threatened by industrial activities such as mining, oil exploration and illegal logging, conservation group WWF warned Wednesday.

The 114 threatened sites, virtually half the total listed by UNESCO, provide food, water, shelter and medicine to over 11 million people — more than the population of Portugal, according to a WWF-commissioned report.

The sites are meant to be protected for future generations.

“Despite the obvious benefits of these natural areas, we still haven’t managed to decouple economic development from environmental degradation,” WWF director general Marco Lambertini said in a foreword.

“Instead, too often, we grant concessions for exploration of oil, gas or minerals, and plan large-scale industrial projects without considering social and environmental risks.”

The UN Educational, Scientific and Cultural Organisation (UNESCO) lists 197 “natural” and 32 “mixed” Heritage Sites in 96 countries around the world, alongside 802 cultural sites.

The 229 natural and mixed sites, nominated by governments of the countries in which they are found, include national parks and nature reserves, forests, coral reefs, islands and coastal areas.

But among the 114 sites highlighted by the WWF, Australia’s Great Barrier Reef, the world’s biggest coral reef ecosystem, is threatened by both mining and shipping.

In the United States, the Grand Canyon Natural Park is threatened by dams or unsustainable water use.

And the 15th-century Inca citadel of Machu Picchu in Peru, named a UNESCO World Heritage site in 1983, is threatened by logging, the WWF said.

The report said oil or gas concessions had been granted in 40 of the sites and mining concessions in 42.

Twenty-eight sites were at risk from dams or unsustainable water use, a further 28 from illegal logging, two from overfishing, and 20 from construction of roads or railways. Many sites were threatened in more than one category.

Countries are meant to assume responsibility under the World Heritage Convention to protect listed sites within their borders.

‘Not anti-development'

“The World Heritage Committee is clear and definitive that extractive activities should not occur in World Heritage sites,” WWF global conservation director Deon Nel told AFP by email.

“It has consistently maintained a position that oil, gas and mineral exploration and exploitation is ‘incompatible with World Heritage status.’ Despite this, about a third of natural sites have concessions allocated across them.”

The WWF urged governments to cancel all such concessions, and also called on companies to refrain from harmful activities in protected areas, and on financial institutions not to fund them.

The report relies in large part on data from the International Union for the Conservation of Nature, which monitors UNESCO’s natural Heritage Sites.

Read more at Discovery News

Supermassive Black Holes Could Be Everywhere

Astronomers have found a monster black hole, some 17 billion times more massive than the sun, in a modestly sized galaxy, raising suspicions that supermassive black holes may be much more common than originally thought.

Previously, all known supermassive black holes were found in very large galaxies that are clustered in large groups of galaxies.

Black holes are regions so packed with matter that not even photons of light can escape the gravitational warping of space.

The largest black hole found so far is about 21 billion times more massive than the sun. In comparison, the black hole at the center of the Milky Way galaxy, named Sagittarius A, is about 4 million time the mass of the sun.

The newly discovered black hole is in a somewhat isolated and average-sized galaxy known as NGC 1600. It was studied as part of an ongoing survey of the 100 most massive galaxies within about 300 million light-years from Earth.

“Probably all of these galaxies harbor black holes in their centers. The question we would like to answer is how massive the black holes are, and whether there are more hefty ones like the one we found in NGC 1600,” University of California Berkeley astronomer Chung-Pei Ma wrote in an email to Discovery News.

"We don’t know right now if NGC 1600 is the tip of an iceberg, or a rare find, perhaps as a result of an unusually voracious phase during its youth,” she added.

However it came to exist, NGC 1600’s black hole is an oddity, roughly 10 times bigger than what astronomers would expect a galaxy of its size to host.

“The relationship between black holes and their host galaxies is more intricate and depends on a black hole’s feeding history in addition to location. Nurture and nature therefore both matter for the ultimate size of these black holes,” Ma said.

Typically, supermassive black holes account for about 0.2 percent of its host galaxy’s mass. NGC 1600’s black hole is 2.1 percent of the galaxy’s mass.

One idea is that NGV 1600 is a “fossil” system, astronomer Jens Thomas with Germany’s Max Planck Institute for Extraterrestrial Physics wrote in an email to Discovery News.

In contrast to other averaged-sized galaxy groups, which typically contain a family of a few, similarly massive galaxies, the NGC 1600 group may have formed in a slightly different way, merging together into a single massive galaxy very quickly, Thomas said.

Read more at Discovery News

Ashes of Supernovas Litter Ocean Floor

Scientists have discovered radioactive debris from relatively nearby stars that exploded a few million years ago, raising questions about whether cosmic rays released by the supernovae impacted Earth’s past climate.

The evidence comes from samples taken from the floors of the Pacific, Atlantic and Indian oceans. All contained a radioactive isotope of iron, known as iron-60, which is produced in the cores large stars and in supernovae, which are exploding stars.

The particles were transported via interstellar dust grains to Earth between 1.7 million and 3.2 million years ago, according to a paper published in this week’s Nature.

A second analysis, also published in Nature, traces the iron-60 to two explosions, the first occurring about 2.3 million years ago and the second 1.5 million years ago.

The exploded stars, which were roughly 9.2 and 8.8 times bigger than the sun, respectively, were about 300 light-years away at the time -- close enough to be visible during the day.

“We have shown that the iron-60 must come from outer space, it cannot originate from the solar system,” lead researcher Anton Wallner, with the Australian National University’s Department of Nuclear Physics, wrote in an email to Discovery News.

Wallner and colleagues also were able to ferret out when the iron-60 was deposited, indicating that there was more than one nearby supernova explosion.

“It’s not a single event in the last 10 million years or so, it’s rather a series of supernovae,” Wallner said.

The timing of the supernova explosions coincides with a period of time when Earth cooled, shifting from what is known as the Pliocene into the Pleistocene periods.

"We have now a consistent and coherent picture of what happened around the solar system in the last 20 million years and we know how close these supernovae were. We can now proceed to find out if there might have been any biological effects," astronomer Deiter Breitschwerdt, with the Berlin Institute of Technology, wrote in an email to Discovery News.

Read more at Discovery News

Apr 5, 2016

'Topsy turvy' ocean circulation seen on distant planets

The salt levels of oceans on distant Earth-like planets could have a major effect on their climates -- according to new research from the Centre for Ocean and Atmospheric Sciences at the University of East Anglia.

A study published today reveals that the circulation in extremely salty or fresh water extra-terrestrial seas would influence their temperatures -- and could in fact make for more habitable conditions for alien life.

Until recently, computer simulations of habitable climates on Earth-like planets have mainly focused on their atmospheres. But studying their oceans is vital for understanding climate stability and habitability -- as on our own Earth.

Not only this, but until now, researchers had not considered that the seas on distant Earth-like planets might not be quite like ours -- they might be significantly more or less salty than the oceans on Earth.

Prof David Stevens, from UEA's School of Mathematics, said: "The number of planets being discovered outside our solar system is rapidly increasing. Our research helps to answer whether or not these planets could sustain alien life.

"We think that many planets may be uninhabitable because they are either too close or too far from their sun. A planet's habitable zone is based on its distance from the sun and temperatures at which it is possible for the planet to have liquid water.

"Oceans play a vital role in sustaining life and also have an immense capacity to control climate. But previous studies on ocean circulation on other planets have made the assumption that fundamental ocean properties -- such as the salinity and depth of water -- would be similar to that on Earth.

"We wanted to find out what might be happening on other planets which might appear superficially similar to Earth, but where conditions such as salinity are radically different to our own planet."

The research team used computer models of ocean circulation on exoplanets to see what would happen when their oceans had different salinity levels to Earth. They considered oceans with very low salinity (similar to freshwater), salinity similar to the average value of Earth's oceans, and high salinity (similar levels to the Dead Sea).

Dr Manoj Joshi, from UEA's School of Environmental Sciences, said: "On Earth, we have a circulation where warm water moves towards the poles at the surface, before being cooled, then sinking at high latitudes and travelling towards the equator at depth.

"Our research shows that oceans on other planets with a much higher salinity could circulate in the opposite direction -- with polar water flowing towards the equator at the surface, sinking in the tropics and travelling back towards the poles at depth. We also found a similar pattern emerging for freshwater oceans.

"These circulation patterns are the opposite of what happens on Earth, and would result in a dramatic warming in the polar regions.

Read more at Science Daily

Curse Tablets Found in 2,400-Year-Old Grave

Five lead tablets that cursed tavern keepers some 2,400 years ago have been discovered in a young woman’s grave in Athens, Greece.

Four of the tablets were engraved with curses that invoked the names of “chthonic” (underworld) gods, asking them to target four different husband-and-wife tavern keepers in Athens. The fifth tablet was blank and likely had a spell or incantation recited orally, the words spoken over it.

All five tablets were pierced with an iron nail, folded and deposited in the grave. The grave would have provided the tablets a path to such gods, who would then do the curses’ biddings, according to ancient beliefs.

One of the curses targeted husband-and-wife tavern keepers named Demetrios and Phanagora. The curse targeting them reads in part (translated from Greek):

“Cast your hate upon Phanagora and Demetrios and their tavern and their property and their possessions. I will bind my enemy Demetrios, and Phanagora, in blood and in ashes, with all the dead…”

“I will bind you in such a bind, Demetrios, as strong as is possible, and I will smite down a kynotos on tongue.”

The word kynotos literally means “dog’s ear,” an ancient gambling term that “was the name for the lowest possible throw of dice,” Jessica Lamont, an instructor at John Hopkins University in Baltimore who recently completed a doctorate in classics, wrote in an article published recently in the journal Zeitschrift für Papyrologie und Epigraphik. The “physical act of hammering a nail into the lead tablet would have ritually echoed this wished-for sentiment,” Lamont wrote.

“By striking Demetrios’ tongue with this condemningly unlucky roll, the curse reveals that local taverns were not just sociable watering holes, but venues ripe for gambling and other unsavory activities in Classical Athens,” Lamont wrote.

A woman’s grave

The grave where the five curse tablets were found was excavated in 2003 by archaeologists with Greece’s Ephorate for Prehistoric and Classical Antiquities. The grave was located northeast of the Piraeus, the port of Athens. Details of the burial have not yet been published, but Lamont said that excavation reports indicate that it contained the cremated remains of a young woman. Lamont has been studying the curse tablets at the Piraeus Museum, where they are now kept.

“The way that curse tablets work is that they’re meant to be deposited in an underground location,” such as a grave or well, Lamont told Live Science. “It’s thought that these subterranean places provided a conduit through which the curses could have reached the underworld,” and its chthonic gods would then do the curse’s biddings, Lamont said.

The woman buried in the grave might have had nothing to do with the curses or tavern keeping, Lamont said. Perhaps she died at the time when someone wanted to cast these curses on others in the same community, Lamont said.

Read more at Discovery News

Ancient Burials Revealed at Mysterious Plain of Jars

Archaeologists have uncovered ancient human remains and various burial practices at the mysterious Plain of Jars in Laos, Australian researchers said Monday, as scientists attempt to unravel the puzzle of the stone vessels.

The Plain of Jars in Laos’ central Xieng Khouang province is scattered with thousands of stone jars and scientists have long been perplexed by their original use.

“This will be the first major effort since the 1930s to attempt to understand the purpose of the jars and who created them,” Dougald O’Reilly from the Australian National University’s school of archaeology said in a statement.

He said excavations uncovered three types of burials at the site. In one practice, bones were buried in pits with a large limestone block placed over them, while other bones were found buried in ceramic vessels, separate from the jars.

The researchers also found for the first time an instance of a body being placed in a grave.

O’Reilly said while the jars were empty now, it is possible they were once used to hold bodies until the flesh had completely decomposed so the bones could then be buried.

“We don’t have any evidence for cremation which is something that has been suggested in the past,” said O’Reilly, adding that it was also unclear where those buried had lived.

Despite the finds, he said the original purpose of the jars remains unknown.

“The stone jars remain a mystery as to what they were used for,” O’Reilly said.

Only a few simple objects, such as a handful of glass beads, have been found with the human remains at the burial sites, which are thought to date from about 500 or 600 BC to 550 AD.

Read more at Discovery News

Pig Heart Kept Beating in Baboon for Years

One day, cardiac patients may enjoy a new lease on life with pig hearts beating in their chests, said researchers reporting a major advance Tuesday in cross-species organ transplantation.

Given the dire shortage of organ donors, the use of animal hearts, lungs or livers to save human lives has long been a holy grail of medical science.

But organ rejection has stood stubbornly in the way.

On Tuesday, scientists from the United States and Germany said they had succeeded in keeping transplanted pig hearts alive in baboons, primate cousins of humans, for a record 2.5 years.

Their method uses a combination of gene modification and targeted immune-suppressing drugs.

“It is very significant because it brings us one step closer to using these organs in humans,” said study co-author Muhammad Mohiuddin of the National Heart, Lung and Blood Institute in Maryland.

“Xenotransplants — organ transplants between different species — could potentially save thousands of lives each year that are lost due to a shortage of human organs for transplantation,” he told AFP by email.

In experiments with five baboons, the hearts survived for up to 945 days, breaking previous records held by the same group of researchers.

The hearts did not replace those of the monkeys, but were connected to the circulatory system via two large blood vessels in the baboon abdomen.

The transplanted heart beat like a normal heart, but the baboon’s own heart continued the function of pumping blood — a known method in studying organ rejection.

Donor organs are often rejected by a recipient’s immune system, which can recognise it as foreign, and thus a threat.

In this trial, the donor organs came from pigs which had been genetically modified to have high tolerance to immune response, basically making them invisible to the recipient’s natural defence system.

The scientists also added a human genetic signature to the pigs that help prevent blood clotting.

The recipient baboons were given a drug that suppresses immune response.

- Safe for humans? -

Scientists have been experiment with the transplantation of primate kidneys, hearts and livers into humans since the 1960s. None survived beyond a few months.

Given their genetic proximity to humans, primates were initially thought to be the best donor candidates. But there is no large source of captive-bred apes — which take long to grow and mature, and some like chimpanzees are endangered.

Their genetic closeness also poses a higher danger of inter-species disease transmission, as well as ethical questions.

Pigs have since emerged as better donors. Their hearts are anatomically similar to ours, they pose less of a disease transmission risk, they grow up fast and are already widely farmed.

In these xenotransplant trials, baboons serve as human models.

Read more at Discovery News

Apr 4, 2016

Ancient Animal Carried Its Young Like Tethered Kites

A tiny arthropod from 430 million years ago dubbed “The Kite Runner” had a novel way of hauling around its young: It stashed them in individual capsules tethered to its body, like so many kites at the ends of pieces of string.

That’s what a team of researchers from the United States and the United Kingdom found when they studied the fossil of an ancient arthropod named Aquilonifer spinosus, a creature not even half of an inch long that would have made its living on the sea floor alongside the sponges, snails, worms and other aquatic neighbors of its day.

The researchers described the many-tethered parent as having no eyes, its head covered by a shield-like apparatus.

Thanks to virtual reconstruction techniques, the scientists were able to determine that 10 juveniles were tethered to the fossil, in varying stages of development.

The pouches -- or “kites,” to continue the analogy -- holding the juveniles were attached to the adult by thin, flexible threads. The pouches themselves looked like “flattened lemons,” the scientists said.

“Modern crustaceans employ a variety of strategies to protect their eggs and embryos from predators: attaching them to the limbs, holding them under the carapace, or enclosing them within a special pouch until they are old enough to be released,” said the study’s lead author Derek Briggs, of Yale University, in a statement. “But this example is unique.”

Briggs and his colleagues from Oxford, the University of Leicester, and Imperial College London, ruled out any chance the juveniles were instead parasites attached to a convenient host, noting that their method of attachment would not have been very good for stealing nutrients.

Read more at Discovery News

Medieval Whip Used by Self-Flagellating Monks Found

British archaeologists have solved the mystery over some ancient pieces of woven copper-alloy wires that were unearthed at a Medieval monastery.

Found in 2014 at Rufford Abbey, Nottinghamshire, the braided-together length of copper wire, turned to be part of a whip or cat-o-nine-tail used by monks for self-flagellation.

According to Nottinghamshire County Council, the true meaning of the 14th century wire was realized after comparing it with a similar metal scourge found at another British monastery.

“This is a fascinating discovery which helps us to build a picture of what life could have been like for the monks living in the Abbey during the dark days of the Black Death and its aftermath,” Councillor John Knight, committee chairman for culture, said in a statement.

The Black Death plague ravaged the country between 1348 and 1350, causing the decline of Rufford Abbey which lost much of its income from the wool industry. Because of the Abbey's dire financial situation, various kings excused the Abbey from paying taxes during this time.

The whip is one of only four uncovered in the country. It would have been used in this period by the Cistercian monks in an attempt to ward off the Black Death, or as an act of penance to take the population’s sins upon themselves.

The monks lived in austerity — they would rise at 4.30 a.m. to take part in church services and then labor in the fields for long hours.

Despite the use of the self-flagellating whip, historical records reveal that some Rufford monks strayed from the monastic vows. They include Brother William, arrested for the murder of Brother Robert in 1280, and two monks who were charged with the £200 ($285) robbery of Thomas De Holme.

Read more at Discovery News

Great Barrier Reef Bleaching 'Worst in Its History'

Australia’s Great Barrier Reef corals are in trouble.

The northern part of the world’s largest coral reef ecosystem is experiencing “the worst mass bleaching event in its history,” according to a statement released in late March by the Australian Research Council.

Documented by the National Coral Bleaching Taskforce (NCBT) in aerial surveys, observations of more than 500 coral reefs spanning 2,485 miles (4,000 kilometers) showed that the majority of reefs were undergoing extensive and severe bleaching.

“Almost without exception, every reef we flew across showed consistently high levels of bleaching, from the reef slope right up onto the top of the reef,” said Terry Hughes of the NCBT, calling the surveys “the saddest research trip of my life.”

Bleaching happens when corals are exposed to stresses such as warmer-than-average waters for prolonged periods of time. The corals respond to the stress by expelling the algae that provide them with their color, which makes the corals look like they’ve been bleached white. Bleaching can be fatal for corals if the stress is too intense, or if it continues for too long and the algae are unable to recolonize them.

Ecosystem at risk

Australia’s Great Barrier Reef (GBR) covers 134,364 square miles (348,000 square kilometers), making it larger than the U.K., Switzerland and the Netherlands combined, according to the Great Barrier Reef Marine Park Authority. Recognized as a World Heritage Area in 1981, the reef contains 400 types of coral and hosts 1,500 types of fish and 4,000 mollusk species, as well as other marine life such as large green turtles and dugongs (“sea cows”).

The GBR experienced bleaching events in 1998 and in 2002, but the current mass bleaching is much more severe, experts are saying. Rebecca Albright, a marine biologist with the Carnegie Institution for Science in Washington, D.C., has studied the GBR since 2011. Albright told Live Science that 95 percent of the GBR’s northern reefs are currently showing signs of extreme bleaching, compared with 18 percent that experienced bleaching in 2002.

Even the more robust corals are affected, Albright said, another sign that this event is particularly serious. She cautioned that it’s still too early to assess the long-term impacts of bleaching on the corals, though estimates of coral mortality anticipate losses of about 50 percent.

Two factors are responsible for stressing the corals, Albright said: climate change, which is driving ocean temperatures upward, and a strong El Niño  — a cyclical climate event associated with warmer-than-average sea surface temperatures in the tropical Pacific. And with El Niño conditions expected to extend through 2016, that doesn’t bode well for the corals’ recovery.

“Corals are sensitive to not only the anomaly in temperature — how high it goes — but also the duration of that exposure,” Albright told Live Science. “This kind of perfect storm of all these factors coming together makes this a catastrophic scenario right now.” [Images: Colorful Corals of the Deep Barrier Reef]

A global event

But what’s happening to the GBR is only part of the picture. A global bleaching event prolonged by El Niño is currently underway — “the longest coral die-off on record,” according to a statement released by the National Oceanic and Atmospheric Administration (NOAA) on Feb. 23.

Mark Eakin, coordinator of the NOAA Coral Reef Watch program, told Live Science that the event, which began in 2014 in the Pacific, could linger through 2017.

“We consider it a global bleaching event if it’s widespread in all three of the major ocean basins — Indian, Atlantic and Pacific,” he said. Eakin described current reports of bleaching that extend over half of the Southern Hemisphere, with severe bleaching in New Caledonia, Fiji and southern Indonesia, as well as in the GBR.

Even fast-growing corals take decades to develop, so damaged reefs will need time before they’re restored to their former level of health, Eakin said.

And recovery time may be in short supply. Global bleaching events have been expanding their reach and increasing in severity since the first event was documented in 1998, Eakin told Live Science.

“We’re seeing prolonged high temperatures that cause bleaching coming back repeatedly. We’re seeing areas that have seen high temperatures for two to three years in a row. There’s no time for corals to recover,” he said.

The 1998 global bleaching event was associated with a strong El Niño — the strongest on record — but as ocean temperatures rise, even a mild El Niño can trigger a devastating effect on the world’s corals. And the global bleaching event that’s underway right now began in 2014, before the current El Niño was active, Eakin said.

Read more at Discovery News

350-Year-Old Pendulum Clock Mystery Solved

The 350-year-old mystery of why pendulum clocks hanging from the same wall can influence each other and synchronize over time may hold even more secrets than previously thought, researchers say.

Solving this mystery could shed light on puzzling aspects of a variety of synchronized behaviors, such as how brain cells work together, the scientists added.

In 1665, the inventor of the pendulum clock, Dutch physicist Christiaan Huygens, was lying in bed sick, watching two of his clocks, when he noticed something odd: No matter how the pendulums on these clocks started, they ended up swinging in exactly the opposite direction from each other within about a half-hour.

For centuries, the cause of this effect was unknown. Solving the puzzle could help shed light on the mysterious phenomenon of synchronization, scientists say.

“The synchronization phenomenon is one of the most pervasive drives in nature,” said study lead author Jonatan Peña Ramirez, a dynamicist at the Center for Scientific Research and Higher Education in Ensenada, Mexico. “For example, consider a couple dancing to the rhythm of music, or violinists in an orchestra playing in unison, or a school of fish gracefully swimming.”

In a separate study published last year in the journal Scientific Reports, scientists suggested that the explanation for this phenomenon involved sound pulses traveling from clock to clock — for instance, through the wall on which the machines hang. However, Peña and his colleagues now suggest that Huygens’ original explanation for this mystery could be the correct one.

The researchers experimented with two complex pendulum clocks known as monumental clocks.”To the best of our knowledge, this is the first time that Huygens’ experiment is reproduced using real monumental pendulum clocks,” Peña told Live Science. “Previous studies have used scaled-down versions of pendulum clocks, or commercial and generic clocks.”

The scientists placed both clocks on the same wooden table. As they expected, the motion of the clock pendulums synchronized over time.

However, unlike the clocks in Huygens’ experiment, the clocks did not swing in opposite directions. Rather, they unexpectedly moved in exactly the same direction. Moreover, while the clocks stayed in sync, they became slower and more inaccurate over time, the scientists said.

To explain these findings, the researchers developed a mathematical model of the clocks, taking into account the flexible nature of the wooden support that both machines rested on. The model suggested that the clocks could make the wooden board vibrate.

The researchers found that the support connecting the clocks (in this case, the wooden table) could serve as a kind of communication channel between the clocks, which they could use to exchange energy. The rigidity, thickness and mass of this support can influence the way in which the clocks synchronize and how inaccurate they become, the researchers said.

Long ago, Huygens suggested that the synchronous behavior of the clocks he observed might be caused by “the imperceptible vibrations of the beam on which they are hanging,” Peña said. Huygens “was so brilliant that he gave the correct explanation for his discovery without using a single equation.”

These findings suggest that much remains unknown about how coupled pendulum clocks behave, Peña said. “There still are hidden secrets to be revealed, and consequently, further studies of this system are necessary in order to unveil more details about the complex yet intriguing synchronization phenomenon,” Peña said.

A better understanding of synchronization could have technological and biological implications. For instance, consider two rotors mounted on an elastic support. “A familiar example of this kind of devices is a washing machine,” Peña said. Under certain conditions, the rotors may synchronize to rotate in the same direction, or in opposite directions, he said.

The synchronization of these rotors in opposite directions is highly desirable, because this will reduce or even eliminate the vibrations of the washing machine while its rotors are operating, Peña said. However, synchronization of these rotors in the same direction is not desired at all, because strong vibrations can result, with harmful and undesirable effects, he explained.

Read more at Discovery News

Black Hole Jets Hotter Than Expected

New observations of a jet-emitting black hole show astonishing temperatures inside the jets of 10 trillion degrees Kelvin — a toasty 18 trillion degrees Fahrenheit. This new measurement shows that quasars can blow far past the theoretical temperature limit of 100 billion degrees Kelvin (179 billion degrees Fahrenheit), which has scientists puzzled.

“This result is very challenging to explain with our current understanding of how relativistic jets of quasars radiate,” said lead author Yuri Kovalev of the Moscow’s Lebedev Physical Institute in a statement.

Observations of quasar 3C 273 were done with the Russian Skeptr-R satellite working in concert with three ground observatories as part of the larger RadioAstron mission. Quasars are supermassive black holes that emit intense jets of radiation.

Previously, it was believed there was a limit to the temperature because the electrons inside the jet would produce X-rays and gamma rays, interact with each other and cool down.

Astronomers hailed the finding as a triumph for interferometry, which occurs when multiple telescopes are linked together to get fine resolution of a distant object. The four observatories working together can get better resolution than the Hubble Space Telescope (although Hubble does not observe in X-rays or gamma rays).

The team also had a secondary find, which was that 3C 273 had previously unknown visible distortions to its substructure as seen from Earth, caused by peering through the interstellar medium in our own Milky Way. The distortion was only spotted because of the resolution of RadioAstron, researchers said in a statement.

The results were published in The Astrophysical Journal.

From Discovery News

Apr 3, 2016

Heat and light get larger at the nanoscale

This is a schematic of two beams at different temperatures exchanging heat using light. In the situation when the beams are far from each other (left), heat transfer resulting from thermal radiation is small. When the beams are brought very close from each other (right) heat transfer becomes almost 100 times larger than predicted by conventional thermal radiation laws.
In a new study recently published in Nature Nanotechnology, researchers from Columbia Engineering, Cornell, and Stanford have demonstrated heat transfer can be made 100 times stronger than has been predicted, simply by bringing two objects extremely close--at nanoscale distances--without touching. Led by Columbia Engineering's Michal Lipson and Stanford Engineering's Shanhui Fan, the team used custom-made ultra-high precision micro-mechanical displacement controllers to achieve heat transfer using light at the largest magnitude reported to date between two parallel objects.

"At separations as small as 40 nanometers, we achieved almost a 100-fold enhancement of heat transfer compared to classical predictions," says Lipson, Eugene Higgins Professor of Electrical Engineering and professor of applied physics. "This is very exciting as it means that light could now become a dominant heat transfer channel between objects that usually exchange heat mostly through conduction or convection. And, while other teams have demonstrated heat transfer using light at the nanoscale before, we are the first to reach performances that could be used for energy applications, such as directly converting heat to electricity using photovoltaic cells."

All objects in our environment exchange heat with their surroundings using light. This includes the light coming at us from the sun, the glowing red color of the heating element inside our toaster ovens, or the "night vision" cameras that enable image recording even in complete darkness. But heat exchange using light is usually very weak compared to what can be achieved by conduction (i.e., by simply putting two objects in contact with each other) or by convection (i.e., using hot air). Radiative heat transfer at nanoscale distances, while theorized, has been especially challenging to achieve because of the difficulty of maintaining large thermal gradients over nanometer-scale distances while avoiding other heat transfer mechanisms like conduction.

Lipson's team was able to bring objects at different temperatures very close to each other--at distances smaller than 100 nanometers, or 1/1000th of the diameter of a strand of human hair. They were able to demonstrate near-field radiative heat transfer between parallel SiC (silicon carbide) nanobeams in the deep sub-wavelength regime. They used a high-precision micro-electromechanical system (MEMS) to control the distance between the beams and exploited the mechanical stability of nanobeams under high tensile stress to minimize thermal buckling effects, thus keeping control of the nanometer-scale separation even at large thermal gradients.

Using this approach, the team was able to bring two parallel objects at different temperatures to distances as small as 42 nm without touching. In this case they observed that the heat transfer between the objects was close to 100 times stronger that what is predicted by conventional thermal radiation laws (i.e. "blackbody radiation"). They were able to repeat this experiment for temperature differences as high as 260oC (500oF) between the two objects. Such high temperature difference is especially important for energy conversion applications since, in these cases, the conversion efficiency is always proportional to the thermal difference between the hot and the cold objects involved.

"An important implication of our work is that thermal radiation can now be used as a dominant heat transfer mechanism between objects at different temperatures," explains Raphael St-Gelais, the study's lead author and postdoctoral fellow working with Lipson at Columbia Engineering. "This means that we can control heat flow with a lot of the same techniques we have for manipulating light. This is a big deal since there are a lot of interesting things we can do with light, such as converting it to electricity using photovoltaic cells."

St-Gelais and Linxiao Zhu, who co-authored the study and is a PhD candidate in Fan's group at Stanford, note that the team's approach can be scaled up to a larger effective area by simply arraying several nanobeams--on top of a photovoltaic cell, for example--and by individually controlling their out-of-plane displacement using MEMS actuators. The researchers are now looking at applying their same approach for ultra-high-precision displacement control, this time with an actual photovoltaic cell to generate electricity directly from heat.

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Mile-high Mars mounds built by wind and climate change

This images shows sediment-filled craters on Mars (top) in different stages of erosion compared with results of a crater model in a wind tunnel experiment (bottom). Warm colors reflect high elevation, and cool colors low elevation.
New research has found that wind carved massive mounds of more than a mile high on Mars over billions of years. Their location helps pin down when water on the Red Planet dried up during a global climate change event.

The research was published in the journal Geophysical Research Letters, a journal of the American Geophysical Union, on March 31.

The findings show the importance of wind in shaping the Martian landscape, a force that, on Earth, is overpowered by other processes, said lead author Mackenzie Day, a graduate student at The University of Texas at Austin Jackson School of Geosciences.

"On Mars there are no plate-tectonics, and there's no liquid water, so you don't have anything to overprint that signature and over billions of years you get these mounds, which speaks to how much geomorphic change you can really instigate with just wind," Day said. "Wind could never do this on Earth because water acts so much faster, and tectonics act so much faster."

Day conducted the research with Jackson School researchers Gary Kocurek and David Mohrig of the Department of Geological Sciences and University of Texas at Dallas researcher William Anderson.

First spotted during NASA's Viking program in the 1970s, the mounds are at the bottom of craters. Recent analysis by the Mars rover Curiosity of Mount Sharp, a mound over three miles high inside Gale Crater, has revealed that the thickest ones are made of sedimentary rock, with bottoms made of sediments carried by water that used to flow into the crater and tops made of sediments deposited by wind. However, how the mounds formed inside craters that were once full of sediments was an open question.

"There's been a theory out there that these mounds formed from billions of years of wind erosion, but no one had ever tested that before," Day said. "So the cool thing about our paper is we figured out the dynamics of how wind could actually do that."

To test whether wind could create a mound, the researchers built a miniature crater 30 centimeters wide and 4 centimeters deep, filled it with damp sand, and placed it in a wind tunnel. They tracked the elevation and the distribution of sand in the crater until all of it had blown away. The model's sediment was eroded into forms similar to those observed in Martian craters, forming a crescent-shaped moat that deepened and widened around the edges of the crater. Eventually all that was left of the sediment was a mound -- which, in time, also eroded away.

"We went from a filled crater layer cake to this mounded shape that we see today," Day said.

To understand the wind dynamics, researchers also built a computer model that simulated how the wind flowed through the crater at different stages of erosion.

The mounds' structure helps link their formation to climate change on Mars, Kocurek said, with the bottom being built during a wet time, and the top built and mound shaped in a dry time.

"This sequence signals the change from a dominance of depositional processes by water during a wetter time, to wind reworking of these water-laid sediments with the onset of aridity, followed by wind erosion once these sediment supplies have been exhausted," he said. "Overall, we are seeing the complete remaking of the sedimentary cycle on Mars to the one that characterizes the planet today."

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