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

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

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