Earplugs unavoidable for musicians in the orchestra and at home

Remy Wenmaekers performed measurements with mannequins on stage to determine the effect of the presence of an orchestra on the acoustics. His conclusion is that measurements on empty stages do not give a good picture of the stage acoustics.

Many musicians suffer ear damage. Professional orchestras have therefore taken measures in recent years to reduce the sound levels. Studies now reveal that physical measures, like placing screens between sections or creating more space between them, have little effect. This is due to one's own instrument contributing just as much to the sound level that reaches the ear as all the orchestra's instruments together. So experienced musicians that play alone at home -- whether professionals or amateurs -- also produce excessive sound levels. The only solution that really helps is earplugs.

The eardrums of trumpet players and flute players are the most burdened. During loud passages they are subjected to average decibel levels of 95 to 100 dB(A), just from their own instruments. The violin and viola produce decibel levels in excess of 90 dB(A) for their players. These levels are similar to those of a rock concert. They also well exceed the 85 dB(A) limit that European regulations stipulate for the compulsory wearing of ear protection on the work floor.

Close to the ears

Acoustics expert and researcher Remy Wenmaekers got these results using a calculation model he developed to work out the level of sound close to the ears of musicians. Wenmaekers chose to use a calculation model rather than measurements on the spot where musicians play their instruments. The reason is musicians never reproduce exactly the same level of sound, which makes comparison of experiments with 'real' musicians virtually impossible.

As a foundation for his model he used recordings of orchestra music per instrument made in an anechoic chamber (a room without an echo). The model takes account of the direction of the sound of the instruments, the listening orientation of the receivers, reflection of sound, and blocking by people (the musicians themselves). He compared the results of his model with measurements in a real orchestra and there appeared to be a good correspondence.

This video shows the sound levels at the ears of musicians as calculated by Wenmaekers' model, for the first two minutes of Mahler first symphony (4th movement). It clearly shows sound levels exceeding 100 dB(A) repeatedly.

Earplugs

Using his model Wenmaekers calculated the effect of the most commonly used sound-reducing measures, like screens and higher plateaus for the different sections in the orchestra. Those effects appeared to be very small since the main source of the sound was the player's own instrument. The same cause lies behind the relatively small impact (around 3 dB) of the sound-intensifying effect of small orchestra playing areas like covered orchestra pits. According to Wenmaekers it is still advisable to avoid such small orchestra playing areas but then again, the sound levels are still too high in other areas.

The only thing that really helps is to play more quietly or to use earplugs. Musicians have long been advised to play using earplugs but now it has been proven that there is no other feasible measure that can be taken.

Too late

Wenmaekers, himself a musician, realizes that this is not really what the doctor ordered. "A musician with poor hearing risks losing his job. So to avoid this, earplugs are inevitable. At the same time, you want to perform as well as possible, so earplugs may hinder this. Musicians will have to get used to playing with earplugs from a young age because once you have a hearing problem you are too late."

Getting away with it

There is, however, one part of the orchestra that can get away with it in part, the cello and the bass sections. These instruments produce a relatively soft sound and thus present no risk by themselves. The sound that affects the ears of the cellists and bassists tends to be generally lower and comes mainly from the other orchestra sections. So for this group there may be other interventions that are effective apart from earplugs.

These results were published this month in the Journal of the Acoustical Society of America.

Mannequins

Another purpose of the study was to improve methods of measurement based on loudspeaker sound and microphones to get a picture of the stage acoustics. This form of objective measurement is highly desirable, especially because an evaluation of the acoustics is essential to the design and improvement of music auditoriums.

Read more at Science Daily

Dark matter and dark energy: Do they really exist?

View of Milky Way

For close on a century, researchers have hypothesised that the universe contains more matter than can be directly observed, known as "dark matter." They have also posited the existence of a "dark energy" that is more powerful than gravitational attraction. These two hypotheses, it has been argued, account for the movement of stars in galaxies and for the accelerating expansion of the universe respectively. But -- according to a researcher at the University of Geneva (UNIGE), Switzerland -- these concepts may be no longer valid: the phenomena they are supposed to describe can be demonstrated without them. This research, which is published in The Astrophysical Journal, exploits a new theoretical model based on the scale invariance of the empty space, potentially solving two of astronomy's greatest mysteries.
onger valid: the phenomena they are supposed to describe can be demonstrated without them. This research, which is published in The Astrophysical Journal, exploits a new theoretical model based on the scale invariance of the empty space, potentially solving two of astronomy's greatest mysteries.

In 1933, the Swiss astronomer Fritz Zwicky made a discovery that left the world speechless: there was, claimed Zwicky, substantially more matter in the universe than we can actually see. Astronomers called this unknown matter "dark matter," a concept that was to take on yet more importance in the 1970s, when the US astronomer Vera Rubin called on this enigmatic matter to explain the movements and speed of the stars. Scientists have subsequently devoted considerable resources to identifying dark matter -- in space, on the ground and even at CERN -- but without success. In 1998 there was a second thunderclap: a team of Australian and US astrophysicists discovered the acceleration of the expansion of the universe, earning them the Nobel Prize for physics in 2011. However, in spite of the enormous resources that have been implemented, no theory or observation has been able to define this black energy that is allegedly stronger than Newton's gravitational attraction. In short, black matter and dark energy are two mysteries that have had astronomers stumped for over 80 years and 20 years respectively.

A new model based on the scale invariance of the empty space

The way we represent the universe and its history are described by Einstein's equations of general relativity, Newton's universal gravitation and quantum mechanics. The model-consensus at present is that of a big bang followed by an expansion. "In this model, there is a starting hypothesis that hasn't been taken into account, in my opinion," says André Maeder, honorary professor in the Department of Astronomy in UNIGE's Faculty of Science. "By that I mean the scale invariance of the empty space; in other words, the empty space and its properties do not change following a dilatation or contraction." The empty space plays a primordial role in Einstein's equations as it operates in a quantity known as a "cosmological constant," and the resulting universe model depends on it. Based on this hypothesis, Maeder is now re-examining the model of the universe, pointing out that the scale invariance of the empty space is also present in the fundamental theory of electromagnetism.

Do we finally have an explanation for the expansion of the universe and the speed of the galaxies?

When Maeder carried out cosmological tests on his new model, he found that it matched the observations. He also found that the model predicts the accelerated expansion of the universe without having to factor in any particle or dark energy. In short, it appears that dark energy may not actually exist since the acceleration of the expansion is contained in the equations of the physics.

In a second stage, Maeder focused on Newton's law, a specific instance of the equations of general relativity. The law is also slightly modified when the model incorporates Maeder's new hypothesis. Indeed, it contains a very small outward acceleration term, which is particularly significant at low densities. This amended law, when applied to clusters of galaxies, leads to masses of clusters in line with that of visible matter (contrary to what Zwicky argued in 1933): this means that no dark matter is needed to explain the high speeds of the galaxies in the clusters. A second test demonstrated that this law also predicts the high speeds reached by the stars in the outer regions of the galaxies (as Rubin had observed), without having to turn to dark matter to describe them. Finally, a third test looked at the dispersion of the speeds of the stars oscillating around the plane of the Milky Way. This dispersion, which increases with the age of the relevant stars, can be explained very well using the invariant empty space hypothesis, while there was before no agreement on the origin of this effect.

Read more at Science Daily

How badly do you want something? Babies can tell

To evaluate infants’ intuition regarding what other people value, researchers showed them videos in which an agent (red bouncing ball) decides whether it’s worth the effort to leap over an obstacle to reach a goal (blue cartoon character).

Babies as young as 10 months can assess how much someone values a particular goal by observing how hard they are willing to work to achieve it, according to a new study from MIT and Harvard University.

This ability requires integrating information about both the costs of obtaining a goal and the benefit gained by the person seeking it, suggesting that babies acquire very early an intuition about how people make decisions.

"Infants are far from experiencing the world as a 'blooming, buzzing confusion,'" says lead author Shari Liu, referring to a description by philosopher and psychologist William James about a baby's first experience of the world. "They interpret people's actions in terms of hidden variables, including the effort [people] expend in producing those actions, and also the value of the goals those actions achieve."

"This study is an important step in trying to understand the roots of common-sense understanding of other people's actions. It shows quite strikingly that in some sense, the basic math that is at the heart of how economists think about rational choice is very intuitive to babies who don't know math, don't speak, and can barely understand a few words," says Josh Tenenbaum, a professor in MIT's Department of Brain and Cognitive Sciences, a core member of the joint MIT-Harvard Center for Brains, Minds and Machines (CBMM), and one of the paper's authors.

Tenenbaum helped to direct the research team along with Elizabeth Spelke, a professor of psychology at Harvard University and CBMM core member, in whose lab the research was conducted. Liu, the paper's lead author, is a graduate student at Harvard. CBMM postdoc Tomer Ullman is also an author of the paper, which appears in the Nov. 23 online edition of Science.

Calculating value

Previous research has shown that adults and older children can infer someone's motivations by observing how much effort that person exerts toward obtaining a goal.

The Harvard/MIT team wanted to learn more about how and when this ability develops. Babies expect people to be consistent in their preferences and to be efficient in how they achieve their goals, previous studies have found. The question posed in this study was whether babies can combine what they know about a person's goal and the effort required to obtain it, to calculate the value of that goal.

To answer that question, the researchers showed 10-month-old infants animated videos in which an "agent," a cartoon character shaped like a bouncing ball, tries to reach a certain goal (another cartoon character). In one of the videos, the agent has to leap over walls of varying height to reach the goal. First, the babies saw the agent jump over a low wall and then refuse to jump over a medium-height wall. Next, the agent jumped over the medium-height wall to reach a different goal, but refused to jump over a high wall to reach that goal.

The babies were then shown a scene in which the agent could choose between the two goals, with no obstacles in the way. An adult or older child would assume the agent would choose the second goal, because the agent had worked harder to reach that goal in the video seen earlier. The researchers found that 10-month-olds also reached this conclusion: When the agent was shown choosing the first goal, infants looked at the scene longer, indicating that they were surprised by that outcome. (Length of looking time is commonly used to measure surprise in studies of infants.)

The researchers found the same results when babies watched the agents perform the same set of actions with two different types of effort: climbing ramps of varying incline and jumping across gaps of varying width.

"Across our experiments, we found that babies looked longer when the agent chose the thing it had exerted less effort for, showing that they infer the amount of value that agents place on goals from the amount of effort that they take toward these goals," Liu says.

The findings suggest that infants are able to calculate how much another person values something based on how much effort they put into getting it.

"This paper is not the first to suggest that idea, but its novelty is that it shows this is true in much younger babies than anyone has seen. These are preverbal babies, who themselves are not actively doing very much, yet they appear to understand other people's actions in this sophisticated, quantitative way," says Tenenbaum, who is also affiliated with MIT's Computer Science and Artificial Intelligence Laboratory.

Studies of infants can reveal deep commonalities in the ways that we think throughout our lives, suggests Spelke. "Abstract, interrelated concepts like cost and value -- concepts at the center both of our intuitive psychology and of utility theory in philosophy and economics -- may originate in an early-emerging system by which infants understand other people's actions," she says.

Modeling intelligence

Over the past 10 years, scientists have developed computer models that come close to replicating how adults and older children incorporate different types of input to infer other people's goals, intentions, and beliefs. For this study, the researchers built on that work, especially work by Julian Jara-Ettinger PhD '16, who studied similar questions in preschool-age children. The researchers developed a computer model that can predict what 10-month-old babies would infer about an agent's goals after observing the agent's actions. This new model also posits an ability to calculate "work" (or total force applied over a distance) as a measure of the cost of actions, which the researchers believe babies are able to do on some intuitive level.

"Babies of this age seem to understand basic ideas of Newtonian mechanics, before they can talk and before they can count," Tenenbaum says. "They're putting together an understanding of forces, including things like gravity, and they also have some understanding of the usefulness of a goal to another person."

Building this type of model is an important step toward developing artificial intelligence that replicates human behavior more accurately, the researchers say.

"We have to recognize that we're very far from building AI systems that have anything like the common sense even of a 10-month-old," Tenenbaum says. "But if we can understand in engineering terms the intuitive theories that even these young infants seem to have, that hopefully would be the basis for building machines that have more human-like intelligence."

Still unanswered are the questions of exactly how and when these intuitive abilities arise in babies.

"Do infants start with a completely blank slate, and somehow they're able to build up this sophisticated machinery? Or do they start with some rudimentary understanding of goals and beliefs, and then build up the sophisticated machinery? Or is it all just built in?" Ullman says.

Read more at Science Daily

Climate change could increase volcano eruptions

Tephras -- rock fragments and particles ejected by a volcanic eruption.

Shrinking glacier cover could lead to increased volcanic activity in Iceland, warn scientists.

A new study, led by the University of Leeds, has found that there was less volcanic activity in Iceland when glacier cover was more extensive and as the glaciers melted volcanic eruptions increased due to subsequent changes in surface pressure.

Dr Graeme Swindles, from the School of Geography at Leeds, said: "Climate change caused by humans is creating rapid ice melt in volcanically active regions. In Iceland, this has put us on a path to more frequent volcanic eruptions."

The study examined Icelandic volcanic ash preserved in peat deposits and lake sediments and identified a period of significantly reduced volcanic activity between 5,500 and 4,500 years ago. This period came after a major decrease in global temperature, which caused glacier growth in Iceland.

The findings, published in the journal Geology, found there was a time lag of roughly 600 years between the climate event and a noticeable decrease in the number of volcanic eruptions. The study suggests that perhaps a similar time lag can be expected following the more recent shift to warmer temperatures.

Iceland's volcanic system is in process of recovering from the 'Little Ice Age' -- a recorded period of colder climate roughly between the years 1500 to 1850. Since the end of the Little Ice Age, a combination of natural and human caused climate warming is causing Icelandic glaciers to melt again.

Dr Swindles said: "The human effect on global warming makes it difficult to predict how long the time lag will be but the trends of the past show us more eruptions in Iceland can be expected in the future.

"These long term consequences of human effect on the climate is why summits like COP are so important. It is vital to understand how actions today can impact future generations in ways that have not been fully realised, such as more ash clouds over Europe, more particles in the atmosphere and problems for aviation. "

Icelandic volcanism is controlled by complex interactions between rifts in continental plate boundaries, underground gas and magma build-up and pressure on the volcano's surface from glaciers and ice. Changes in surface pressure can alter the stress on shallow chambers where magma builds up.

Study co-author, Dr Ivan Savov, from the School of Earth & Environment at Leeds, explains: "When glaciers retreat there is less pressure on Earth's surface. This can increase the amount of mantle melt as well as affect magma flow and how much magma the crust can hold.

Read more at Science Daily

New species can develop in as little as two generations, Galapagos study finds

Medium ground finch (Geospiza fortis) on sandy beach, Tortuga Bay, Santa Cruz, Galapagos Islands.

The arrival 36 years ago of a strange bird to a remote island in the Galapagos archipelago has provided direct genetic evidence of a novel way in which new species arise.

In this week's issue of the journal Science, researchers from Princeton University and Uppsala University in Sweden report that the newcomer belonging to one species mated with a member of another species resident on the island, giving rise to a new species that today consists of roughly 30 individuals.

The study comes from work conducted on Darwin's finches, which live on the Galapagos Islands in the Pacific Ocean. The remote location has enabled researchers to study the evolution of biodiversity due to natural selection.

The direct observation of the origin of this new species occurred during field work carried out over the last four decades by B. Rosemary and Peter Grant, two scientists from Princeton, on the small island of Daphne Major.

"The novelty of this study is that we can follow the emergence of new species in the wild," said B. Rosemary Grant, a senior research biologist, emeritus, and a senior biologist in the Department of Ecology and Evolutionary Biology. "Through our work on Daphne Major, we were able to observe the pairing up of two birds from different species and then follow what happened to see how speciation occurred."

In 1981, a graduate student working with the Grants on Daphne Major noticed the newcomer, a male that sang an unusual song and was much larger in body and beak size than the three resident species of birds on the island.

"We didn't see him fly in from over the sea, but we noticed him shortly after he arrived. He was so different from the other birds that we knew he did not hatch from an egg on Daphne Major," said Peter Grant, the Class of 1877 Professor of Zoology, Emeritus, and a professor of ecology and evolutionary biology, emeritus.

The researchers took a blood sample and released the bird, which later bred with a resident medium ground finch of the species Geospiz fortis, initiating a new lineage. The Grants and their research team followed the new "Big Bird lineage" for six generations, taking blood samples for use in genetic analysis.

In the current study, researchers from Uppsala University analyzed DNA collected from the parent birds and their offspring over the years. The investigators discovered that the original male parent was a large cactus finch of the species Geospiza conirostris from Española island, which is more than 100 kilometers (about 62 miles) to the southeast in the archipelago.

The remarkable distance meant that the male finch was not able to return home to mate with a member of his own species and so chose a mate from among the three species already on Daphne Major. This reproductive isolation is considered a critical step in the development of a new species when two separate species interbreed.

The offspring were also reproductively isolated because their song, which is used to attract mates, was unusual and failed to attract females from the resident species. The offspring also differed from the resident species in beak size and shape, which is a major cue for mate choice. As a result, the offspring mated with members of their own lineage, strengthening the development of the new species.

Researchers previously assumed that the formation of a new species takes a very long time, but in the Big Bird lineage it happened in just two generations, according to observations made by the Grants in the field in combination with the genetic studies.

All 18 species of Darwin's finches derived from a single ancestral species that colonized the Galápagos about one to two million years ago. The finches have since diversified into different species, and changes in beak shape and size have allowed different species to utilize different food sources on the Galápagos. A critical requirement for speciation to occur through hybridization of two distinct species is that the new lineage must be ecologically competitive -- that is, good at competing for food and other resources with the other species -- and this has been the case for the Big Bird lineage.

"It is very striking that when we compare the size and shape of the Big Bird beaks with the beak morphologies of the other three species inhabiting Daphne Major, the Big Birds occupy their own niche in the beak morphology space," said Sangeet Lamichhaney, a postdoctoral fellow at Harvard University and the first author on the study. "Thus, the combination of gene variants contributed from the two interbreeding species in combination with natural selection led to the evolution of a beak morphology that was competitive and unique."

The definition of a species has traditionally included the inability to produce fully fertile progeny from interbreeding species, as is the case for the horse and the donkey, for example. However, in recent years it has become clear that some closely related species, which normally avoid breeding with each other, do indeed produce offspring that can pass genes to subsequent generations. The authors of the study have previously reported that there has been a considerable amount of gene flow among species of Darwin's finches over the last several thousands of years.

One of the most striking aspects of this study is that hybridization between two distinct species led to the development of a new lineage that after only two generations behaved as any other species of Darwin's finches, explained Leif Andersson, a professor at Uppsala University who is also affiliated with the Swedish University of Agricultural Sciences and Texas A&M University. "A naturalist who came to Daphne Major without knowing that this lineage arose very recently would have recognized this lineage as one of the four species on the island. This clearly demonstrates the value of long-running field studies," he said.

Read more at Science Daily

Comparison of Primate Brains Reveals Why Humans Are Unique

The Thinker by Auguste Rodin

Since humans and chimpanzees split from their common ancestor around 6 million years ago, the Homo sapiens brain and that of our closest primate relative evolved on their own separate paths.

Besides the obvious size difference — the human brain is about three times larger than the chimp brain — little has been known about how the human brain and the rest of the nervous system changed in our lineage over evolutionary time.

A new evaluation of brain tissue samples from various primates identified key elements that make the human brain unique, including cortical circuits underlying production of the neurotransmitter dopamine. The findings are published in the journal Science.

"Based on our data, which is comprised of gene expression across 16 brain regions, we found that the most distinct region, i.e. the region where we observe more human-specific differences in gene expression, is the striatum, a region involved in motor coordination, reward, and decision-making," lead author André M. Sousa of the Yale School of Medicine and the Kavli Institute for Neuroscience told Seeker.

The study looked at transcriptional profiles of 247 tissue samples from six humans, five chimps, and five macaques. While they were not surprised by the differences between human and chimp brains, the researchers were astounded by a feature that links humans to monkeys.

Sousa, senior author Nenad Sestan, and their team found a rare population of interneurons that produce dopamine and is enriched in the human striatum, but did not make a similar finding in chimp, bonobo, or gorilla brains.

"Surprisingly, this population of cells is also present in macaques and several other primate species that are not among the non-human African great apes," Sestan told Seeker. "The implication is that these cells were somehow lost in the lineage leading to the African great apes and recovered specifically in the human lineage."

Barbary macaque

The finding shows that the human brain is more similar to that of a macaque than a chimp brain.

How the other great apes lost the cells remains unknown, but the researchers theorize genetic disruptions affecting the cells' migration to different parts of the brain, differentiation, or survival could have led to the loss.

Sestan explained that, like a city, the brain is a highly organized arrangement of discrete units linked by transportation and communication systems. In the brain, cells are among the units, migratory pathways are the highways or roads, and various electrical or chemical signals, including dopamine, are the communication systems.

Similar to a city’s real estate industry, the three most important things are location, location, location.

"Very few neurons born in the developing brain reside in the same location in the adult," Sestan said. "Instead, they are born, migrate to a new location, establish functionality, and then, eventually die.  As you might expect, a lot can go wrong. A cell might not be born or might die prematurely, it might migrate to the wrong location, or it might assume or acquire a different functionality."

These events could then help to explain why the brain differences exist between humans and chimps, with which we share up to 98 percent of the same DNA. "In principle,” Sestan said, “small changes in the wiring of the brain can lead to profound and specific functional changes."

Human brain interneurons express the enzymes tyrosine hydroxylase (TH) and DOPA (3,4-dihydroxyphenylalanine) decarboxylase (DDC). The two proteins are involved in dopamine biosynthesis.

While the ancestors of chimps and gorillas lost the ability to express these enzymes in the neocortex, a human ancestor likely recovered it. The scientists do not know which human ancestor recovered this ability, or when.

Since dopamine in the midbrain plays many roles in the central nervous system tied to cognition and behavior, humans would seem to have won the evolutionary brain jackpot. The definition of intelligence is subjective, but our working memory, reflective exploratory behavior, and other cognitive skills appear to be uniquely enhanced versus these abilities in other animals.

"After all, to the best of our knowledge, we are the only living species that is trying to understand how our brain works and what makes our brain different from other species' brains," Sousa said.

On the other hand, there appear to be drawbacks associated with the structure and organization of the human brain.

"In general, the additional brain size and connectivity of the human brain compared to the chimpanzee or macaque, along with the protracted period of time during which human neurodevelopment occurs, means that there are many more problems than can arise and a greater period of time during which those problems can occur," Sestan explained.

Prior research, for example, determined that dopamine-producing neurons throughout the brain are damaged in Parkinson's disease. In fact, Parkinson's patients often receive L-DOPA, an amino acid produced by TH. DDC may then produce dopamine using L-DOPA as a substrate.

Read more at Seeker

Do birdsong and human speech share biological roots?

Male Zebra Finch.

Do songbirds and humans have common biological hardwiring that shapes how they produce and perceive sounds?

Scientists who study birdsong have been intrigued for some time by the possibility that human speech and music may be rooted in biological processes shared across a variety of animals. Now, research by McGill University biologists provides new evidence to support this idea.

In a series of experiments, the researchers found that young zebra finches -- a species often used to study birdsong -- are intrinsically biased to learn to produce particular kinds of sound patterns over others. "In addition, these sound patterns resembled patterns that are frequently observed across human languages and in music," says Jon Sakata, Associate Professor of Biology at McGill and senior author of a paper published online in Current Biology on Nov. 22.

On the shoulders of Chomsky

The idea for the experiments was inspired by current hypotheses on human language and music. Linguists have long found that the world's languages share many common features, termed "universals." These features encompass the syntactic structure of languages (e.g., word order) as well as finer acoustic patterns of speech, such as the timing, pitch, and stress of utterances. Some theorists, including Noam Chomsky, have postulated that these patterns reflect a "universal grammar" built on innate brain mechanisms that promote and bias language learning. Researchers continue to debate the extent of these innate brain mechanisms, in part because of the potential for cultural propagation to account for universals.

At the same time, vast surveys of zebra finch songs have documented a variety of acoustic patterns found universally across populations. "Because the nature of these universals bears similarity to those in humans and because songbirds learn their vocalizations much in the same way that humans acquire speech and language, we were motivated to test biological predisposition in vocal learning in songbirds," says Logan James, a PhD student in Sakata's lab and co-author of the new study.

A buffet of birdsong

In order to isolate biological predispositions, James and Sakata individually tutored young zebra finches with songs consisting of five acoustic elements arranged in every possible sequence. The birds were exposed to each sequence permutation in equal proportion and in a random order. Each finch therefore had to individually "choose" which sequences to produce from this buffet of birdsong.

In the end, the patterns that the laboratory-raised birds preferred to produce were highly similar to those observed in natural populations of birds. For example, like wild zebra finches, birds tutored with randomized sequences often placed a "distance call" -- a long, low-pitched vocalization -- at the end of their song.

Other sounds were much more likely to appear in the beginning or middle of the song; for example, short and high-pitched vocalizations were more likely to be produced in the middle of song than at the beginning or end of song. This matches patterns observed across diverse languages and in music, in which sounds at the end of phrases tend to be longer and lower in pitch than sounds in the middle.

Future research avenues

"These findings have important contributions for our understanding of human speech and music," says Caroline Palmer, a Professor of Psychology at McGill who was not involved in the study. "The research, which controls the birds' learning environment in ways that are not possible with young children, suggests that statistical learning alone -- the degree to which one is exposed to specific acoustic patterns -- cannot account for song (or speech) preferences. Other principles, such as universal grammars and perceptual organization, are more likely to account for why human infants as well as juvenile birds are predisposed to prefer some auditory patterns."

Sakata, who is also a member of the Centre for Research on Brain, Language and Music (CRBLM), says the study opens up many avenues of future work for his team with speech, language, and music researchers. "In the immediate future," he says, "we want to reveal how auditory processing mechanisms in the brain, as well as aspects of motor learning and control, underlie these learning biases."

Read more at Science Daily

Lightning, with a chance of antimatter

A Kyoto University-based team has unraveled the mystery of gamma-ray emission cascades caused by lightning strikes.

A storm system approaches: the sky darkens, and the low rumble of thunder echoes from the horizon. Then without warning... Flash! Crash! -- lightning has struck.

This scene, while familiar to anyone and repeated constantly across the planet, is not without a feeling of mystery. But now that mystery has deepened, with the discovery that lightning can result in matter-antimatter annihilation.

In a collaborative study appearing in Nature, researchers from Japan describe how gamma rays from lightning react with the air to produce radioisotopes and even positrons -- the antimatter equivalent of electrons.

"We already knew that thunderclouds and lightning emit gamma rays, and hypothesized that they would react in some way with the nuclei of environmental elements in the atmosphere," explains Teruaki Enoto from Kyoto University, who leads the project.

"In winter, Japan's western coastal area is ideal for observing powerful lightning and thunderstorms. So, in 2015 we started building a series of small gamma-ray detectors, and placed them in various locations along the coast."

But then the team ran into funding problems. To continue their work, and in part to reach out to a wide audience of potentially interested members of the public as quickly as possible, they turned to the internet.

"We set up a crowdfunding campaign through the 'academist' site," continues Enoto, "in which we explained our scientific method and aims for the project. Thanks to everybody's support, we were able to make far more than our original funding goal."

Spurred by their success, the team built more detectors and installed them across the northwest coast of Honshu. And then in February 2017, four detectors installed in Kashiwazaki city, Niigata recorded a large gamma-ray spike immediately after a lightning strike a few hundred meters away.

It was the moment the team realized they were seeing a new, hidden face of lightning.

When they analyzed the data, the scientists found three distinct gamma-ray bursts. The first was less than one millisecond in duration; the second was a gamma-ray afterglow that decayed over several dozens of milliseconds; and finally there was a prolonged emission lasting about one minute.

Enoto explains, "We could tell that the first burst was from the lightning strike. Through our analysis and calculations, we eventually determined the origins of the second and third emissions as well."

The second afterglow, for example, was caused by lightning reacting with nitrogen in the atmosphere. The gamma rays emitted in lightning have enough energy to knock a neutron out of atmospheric nitrogen, and it was the reabsorption of this neutron by particles in the atmosphere that produced the gamma-ray afterglow.

The final, prolonged emission was from the breakdown of now neutron-poor and unstable nitrogen atoms. These released positrons, which subsequently collided with electrons in annihilation events releasing gamma rays.

"We have this idea that antimatter is something that only exists in science fiction. Who knew that it could be passing right above our heads on a stormy day?" says Enoto.

"And we know all this thanks to our supporters who joined us through 'academist'. We are truly grateful to all."

Read more at Science Daily

This Soft Robot Hugs the Heart and Helps It Beat

A team of engineers and physicians has developed a soft robot implant that hugs the heart and helps it to pump.

Made from specially prepared rubber and plastics, the implant device wraps around the heart like a rope and squeezes the organ to help move blood through body. Electronic components within the robot synchronize the mechanical squeezing and twisting to the heart's natural rhythm.

The heart-hugging robot has only been tested on animals so far, but if the technique proves viable for humans, it could be a life-saving option for patients who otherwise can only be helped with heart transplants.

Heart failure — a condition in which the heart is unable to generate sufficient blood flow — affects around 5.7 million people in the US each year, according to a paper describing the device, published Nov. 22 in the journal Science Robotics.

Currently available devices can assist heart function in a similar manner, but the new soft robot device adds several critical improvements, said Nikolay Vasilyev of Harvard Medical School and co-author of the new research.

“While there have been devices that 'hug' the entire surface of both heart ventricles, this is a brand new approach that 'hugs' and engages only one — the diseased ventricle,” Vasilyev told Seeker. “The healthy ventricle stays intact. Importantly, this is the first device that engages the inner structure of the heart — interventricular septum — that plays a very important role in heart contraction.”

In its current iteration, the apparatus consists of an exterior soft-robotic heart-hugging sleeve — that's the “rope” — and an interior anchor that braces the interventricular septum, the muscular wall separating the heart’s two ventricles. The robot can be configured to squeeze either ventricle, targeting the diseased half while leaving the healthy and functioning ventricle undisturbed.

Another benefit of the new device is that it contracts the heart without actually coming in contact with the blood. This reduces the risk of clotting and infection, Vasilyev said. In essence, the soft robot serves as an additional set of muscles around the exterior of the heart, which improves the function of damaged muscle layers.

The soft robotic ventricular assist device consists of an exterior soft-robotic heart-hugging “sleeve” (comprised of soft actuators) and an interior anchor that braces the interventricular septum — a sturdy wall separating the heart’s two ventricles.

The device was tested on beating pig hearts.

To effectively circulate blood, the soft robot uses compressed air from an external pump, which inflates the pneumatically actuated sleeves that wrap around the heart. The external pump can be powered by any electrical source. For now, the pump is simply plugged into a wall outlet, Vasilyev said. A portable battery system could eventually be used to power the device.

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The Plague Likely Arrived in Europe During the Stone Age

A primitive gas mask in the shape of a bird's beak. A common belief at the time was that the plague was spread by birds. It was thought that by dressing in a bird-like mask, the wearer could draw the plague away from the patient and onto the garment the plague doctor wore. The mask also included red glass eyepieces, which were thought to make the wearer impervious to evil. The beak of the mask was often filled with strongly aromatic herbs and spices to overpower the miasmas or 'bad air' which was also thought to carry the plague. At the very least, it may have served a dual purpose, also dulling the smell of unburied corpses, sputum, and ruptured bouboules in plague victims.

A current plague outbreak in Madagascar, where well over 2,200 people are now infected with the bacterial pathogen, is a reminder that the so-called "medieval disease" still poses a serious health threat. In addition to Madagascar, nine other countries are currently at risk for the latest strain, according to the World Health Organization, including Kenya, Ethiopia, South Africa, Mozambique, Tanzania, Reunion, Mauritius, Seychelles, and Comoros.

Plague, caused by the bacterium Yersinia pestis, was responsible for three major pandemics: the Plague of Justinian (6th–8th century), the Black Death of the 14th century with recurrent outbreaks until the 18th century, and a 19th century outbreak that spread worldwide and became endemic in several regions, including Madagascar.

The early spread and persistence of plague has largely been a mystery that new research appears to have just solved. A paper published in the journal Current Biology reports that migrants entering Europe starting around 4,800 years ago likely brought plague with them from the Great Steppe, which is a vast strip of land stretching from the Ukraine to Mongolia.

The disease's origins may even be as old as dirt.

"Yersinia pestis is actually a specific mutant lineage of the bacterium Y. pseudotuberculosis, which is found in soil," co-author Alexander Herbig of the Max Planck Institute for the Science of Human History told Seeker. "Y. pseudotuberculosis can cause gastrointestinal infections that are only very rarely lethal."

Map of proposed Yersinia pestis circulation throughout Eurasia. A) Entrance of Y. pestis into Europe from Central Eurasia with the expansion of Yamnaya pastoralists around 4,800 years ago. B) Circulation of Y. pestis to Southern Siberia from Europe. Only complete genomes are shown.

Rodents are often blamed for the spread of Y. pestis, but it is a little-known fact that over 200 species can catch and harbor the disease. Fleas may become infected by feeding on such animals and can then transmit the bacteria to others when they feed again.

In its pneumonic form, such as what is now observed in Madagascar, the plague is only transmitted from human to human, however. "This form is aggressive," Herbig said, "and if untreated, it kills infected individuals very quickly."

According to the WHO, the plague death toll for the present epidemic in Madagascar is now close to 200 and rising.

During the Black Death, plague killed an estimated 25 million people in Europe alone. Since the pandemic coincided with the migration out of the Great Steppe, Herbig and his colleagues investigated the remains of people from that region dating from the Late Neolithic to the Bronze Age (4,800–3,700 years ago).

A total of 563 tooth and bone samples dating from the period were genetically screened for Y. pestis. The samples came from individuals from Russia (122), Hungary and Croatia (139), Lithuania (220), Estonia (45), Latvia (10) and Germany (220).

The remains of a male from which samples were taken for the study. His grave included a dagger, flint arrow heads, a bracelet and a bone pin.

Lead author Aida Andrades Valtueña, Herbig, and their team recovered full Y. pestis genomes from six of the studied individuals. They determined that all of the genomes were fairly closely related.

"This suggests that the plague either entered Europe multiple times during this period from the same reservoir or entered once in the Stone Age and remained there," Andrades Valtueña said.

Herbig added that when plague was introduced to Europe, it likely "established a local reservoir before moving back towards Central Eurasia." The recovered genomes show that changes were occurring during this period in genes related to plague virulence. It is possible that the pathogen was capable of causing large-scale epidemics before it developed these traits, however.

If so, the migrations might have occurred as people tried to escape areas where people were sick and dying from the disease. This could help to explain why early farmers seemed often to be on the move. Other recent genetic research shows these individuals frequently wound up settling in various regions within Europe, where they sometimes mated with locals.

"Living close to domestic animals might have facilitated the spread of new diseases during that time," Herbig said. "Furthermore, agriculture and food storage could have attracted wild living rodents, increasing the likelihood of zoonotic infections. The advent of agriculture and domestication very likely had a great influence on the human disease landscape."

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Smart people have better connected brains

The brain of more intelligent people is 'wired' differently from the brain of people with less intelligence.

Differences in intelligence have so far mostly been attributed to differences in specific brain regions. However, are smart people's brains also wired differently to those of less intelligent persons? A new study supports this assumption. In intelligent persons, certain brain regions are more strongly involved in the flow of information between brain regions, while other brain regions are less engaged.

Understanding the foundations of human thought is fascinating for scientists and laypersons alike. Differences in cognitive abilities -- and the resulting differences for example in academic success and professional careers -- are attributed to a considerable degree to individual differences in intelligence. A study just published in Scientific Reports shows that these differences go hand in hand with differences in the patterns of integration among functional modules of the brain. Kirsten Hilger, Christian Fiebach and Ulrike Basten from the Department of Psychology at Goethe University Frankfurt combined functional MRI brain scans from over 300 persons with modern graph theoretical network analysis methods to investigate the neurobiological basis of human intelligence.

Already in 2015, the same research group published a meta-study in the journal Intelligence, in which they identified brain regions -- among them the prefrontal cortex -- activation changes of which are reliably associated with individual differences in intelligence. Until recently, however, it was not possible to examine how such 'intelligence regions' in the human brain are functionally interconnected.

Earlier this year, the research team reported that in more intelligent persons two brain regions involved in the cognitive processing of task-relevant information (i.e., the anterior insula and the anterior cingulate cortex) are connected more efficiently to the rest of the brain (2017, "Intelligence"). Another brain region, the junction area between temporal and parietal cortex that has been related to the shielding of thoughts against irrelevant information, is less strongly connected to the rest of the brain network. "The different topological embedding of these regions into the brain network could make it easier for smarter persons to differentiate between important and irrelevant information -- which would be advantageous for many cognitive challenges," proposes Ulrike Basten, the study's principle investigator.

In their current study, the researchers take into account that the brain is functionally organized into modules. "This is similar to a social network which consists of multiple sub-networks (e.g., families or circles of friends). Within these sub-networks or modules, the members of one family are more strongly interconnected than they are with people from other families or circles of friends. Our brain is functionally organized in a very similar way: There are sub-networks of brain regions -- modules -- that are more strongly interconnected among themselves while they have weaker connections to brain regions from other modules. In our study, we examined whether the role of specific brain regions for communication within and among brain modules varies with individual differences in intelligence, i.e., whether a specific brain region supports the information exchange within their own 'family' more than information exchange with other 'families', and how this relates to individual differences in intelligence."

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Smiling human faces are attractive to dogs, thanks to oxytocin

The hormone oxytocin is probably a key factor in the interaction between dogs and humans.

Researchers in the University of Helsinki's Canine Mind research project found that oxytocin made dogs interested in smiling human faces. It also made them see angry faces as less threatening. Associated with affection and trust, the hormone oxytocin is probably a key factor in the interaction between dogs and humans.

"It seems that the hormone oxytocin influences what the dog sees and how it experiences the thing it sees," says doctoral student Sanni Somppi.

Researchers in the Canine Mind group showed 43 dogs images of smiling and angry faces on a computer screen. Each dog was tested twice: once under the influence of oxytocin, which was administered as part of the test, and once without oxytocin. The dog's gaze on the images and pupil size were measured with an eye-tracking device. Emotions and attentiveness guide the gaze and regulate pupil size, making eye tracking a window into the dogs' minds.

Dogs typically focus on the most remarkable aspect of each situation, such as threatening stimuli in a frightening situation. Recognising and interpreting threats quickly is important for survival. Dogs under the influence of oxytocin were more interested in smiling faces than they were in angry ones.

In addition, oxytocin also influenced the dogs' emotional states, which was evident in their pupil size.

"We were among the first researchers in the world to use pupil measurements in the evaluation of dogs' emotional states. This method had previously only been used on humans and apes," says Professor Outi Vainio, who heads the research group.

Without oxytocin, the dogs' pupils were at their largest when they looked at angry faces. This indicated that the angry faces caused the most powerful emotional reaction in the dogs. Under the influence of oxytocin, however, images of smiling faces enhanced the dogs' emotional state more than angry ones. This is to say that oxytocin probably made the angry faces seem less threatening and the smiling faces more appealing.

"Both effects promote dog-human communication and the development of affectionate relations," says Professor Vainio.

Professor Vainio's research group has previously successfully applied eye tracking and EEGs to studying the canine mind. In this study, the group partnered with József Topál, a Hungarian pioneer of canine research who specialises in dog-human interaction and the social intelligence of dogs.

From Science Daily

Chimp females who leave home postpone parenthood

Imani the chimpanzee, a newcomer to her group, lounges with her son at Gombe National Park in Tanzania.

New moms need social support, and mother chimpanzees are no exception. So much so that female chimps that lack supportive friends and family wait longer to start having babies, according to researchers who have combed through the records of Jane Goodall's famous Gombe chimpanzees.

Wild chimpanzee females in western Tanzania who leave home or are orphaned take roughly three years longer to start a family.

The researchers analyzed more than 50 years' worth of daily records for 36 female chimps born in Gombe National Park. Stored in the Jane Goodall Institute Research Center at Duke University, the records are part of a larger database containing close observations of hundreds of wild chimpanzees, going all the way back to Goodall's first field notes from the early 1960s.

Some female chimpanzees stay with the group they were born into their entire lives. Others pull up their roots and move to a new group when they reach adolescence, presumably to avoid inbreeding.

The average age of first-time moms varies a lot, the researchers found. Females that stay home deliver their first infant around age 13. For migrants, it's 16.

Several factors may contribute to the delay, the researchers said. Like all newcomers, they get pushed around, mostly by resident females. Having left their family and friends behind, they must jostle for position in the pecking order of a new and unfamiliar group.

"It's a tough integration period," said Kara Walker, postdoctoral associate in the department of evolutionary anthropology at Duke.

In contrast, stay-at-home females benefit from better support. Females also started reproducing earlier if their own mothers were around while they were growing up, particularly if their moms were high-ranking -- in part because females with high-ranking moms get better access to food.

Their head start on motherhood means these early bloomers have the potential to produce more offspring over their lifetimes, said Anne Pusey, James B. Duke professor of evolutionary anthropology and director of the Jane Goodall Research Institute Center at Duke.

"This really raises the question of why some females stay and others go," Pusey said.

The results also suggest that a lengthy journey from childhood to adulthood -- long thought to be unique to the human branch of the primate family tree -- may have deeper roots than previously thought.

Read more at Science Daily

How bacteria survive in oxygen-poor environments

Biofilms are multicellular communities formed by densely-packed microbes that are often associated with persistent infections. Steep gradients of nutrients and oxygen form in these crowded structures. The human pathogen Pseudomonas aeruginosa produces molecules called phenazines that help it to cope with the oxygen-limited conditions within biofilms. Columbia researchers have uncovered new roles for proteins of the electron transport chain that implicate them in utilization of phenazines.

Columbia University biologists have revealed a mechanism by which bacterial cells in crowded, oxygen-deprived environments access oxygen for energy production, ensuring survival of the cell. The finding could explain how some bacteria, such as Pseudomonas aeruginosa (P. aeruginosa), are able to thrive in oxygen-poor environments like biofilms and resist antibiotics.

"P. aeruginosa biofilm infections are a leading cause of death for people suffering from cystic fibrosis, a genetic condition that affects the lungs and the digestive system," said Principal Investigator Lars Dietrich, an associate professor of biological sciences. "An understanding of the pathways that contribute to the survival and virulence of P. aeruginosa and other bacteria able to exist in oxygen-starved environments could inform treatment approaches for many of these and other immunocompromised patients."

The study appears this week in the journal eLife.

Bacteria rarely live by themselves as single-celled organisms. Most instead grow in communities, leveraging the strength of numbers to form a biofilm with tissue-like properties similar to a scaffold that serves to fortify the community, making it up to 1,000 times more resistant to most antibiotics.

Each individual cell must on its own extract electrons from food that are then transported along the cell's membrane until they reach an oxygen molecule. The energy released during this metabolic process is used to sustain life. As communities of bacteria continue to grow and form into a biofilm, however, they can become overcrowded, creating an environment where each cell has to compete for limited nutrients and oxygen to survive.

Research has shown that some bacteria, including P. aeruginosa, have evolved different strategies to respond to and cope with the low-oxygen conditions in biofilms. Communities of bacteria can, for example, change the overall structure of the biofilm so that its surface area-to-volume ratio is higher and a larger proportion of the cells inside are able to access the oxygen on the outside. P. aeruginosa can also make molecules called phenazines, which help to shuttle electrons from the inside to the outside of the cell and ultimately to oxygen available at a distance. Another strategy is to make alternative versions of terminal oxidases, enzymes in the membrane that transfer electrons to oxygen, which use oxygen more efficiently or are better at scavenging oxygen when its concentration is low. While there have been numerous studies done to examine the importance of these enzymes and strategies for P. aeruginosa growth, they've largely been conducted in well-oxygenated liquid cultures in the lab. When P. aeruginosa infects an actual host, such as a human, it often grows as a biofilm and encounters vastly different conditions.

With federal funding from the National Institutes of Health and the National Science Foundation, Dietrich, first author Jeanyoung Jo, and their colleagues set out to better understand whether specific terminal oxidases are important for P. aeruginosa metabolism in biofilm communities, how phenazines can compensate for low oxygen levels, and how these adapted strategies may contribute to P. aeruginosa's ability to cause infections.

They found that the electron transport chain so critical to the conversion of electrons to energy can and is operating deep down in the oxygen-deprived biofilm and that in these environments, the bacterium depends on a specific part of the chain's terminal oxidase -- a protein called CcoN4 -- to access oxygen and grow normally. Cells lacking this protein do not survive as well as cells with it and the researchers believe therefore that CcoN4 contributes to the bacterium's virulence. They also found that CcoN4 plays a role in using phenazines optimally within biofilms. Though these phenazines have previously been shown to metabolically compensate for the low-oxygen conditions in P. aeruginosa biofilms, the mechanism allowing for this had remained a scientific mystery.

"This bacterium is a master at finding different strategies to access oxygen," Dietrich said. "We knew that phenazines were involved and that they were somehow helping the cell get oxygen, but we didn't know how. It appears they are coming from the electron transport chain. That's an important revelation. We know that bacterial cells have different ways of metabolizing energy in oxygen-rich environments, but for the longest time we couldn't figure out how they were doing it when oxygen is difficult to access."

The findings could have big implications for the treatment of P. aeruginosa biofilm infections, as an understanding of the pathways that contribute to P. aeruginosa survival and virulence could inform treatment approaches for patients. Developing therapies that block CcoN4-containing terminal oxidases, for example, would weaken the bacterium and its ability to cause infection.

Read more at Science Daily

Mysterious Polar Vortex Observed on Titan, Saturn's Largest Moon

This true color image captured by NASA'S Cassini spacecraft before a distant flyby of Saturn's moon Titan on June 27, 2012, shows a south polar vortex, or a mass of swirling gas around the pole in the atmosphere of the moon.

Winter fell faster than expected in 2012 on Titan, the largest moon in Saturn's system. Astronomers now think that the moon's south pole cooled down quickly because of an increase in trace amounts of certain gases in the atmosphere.

Scientists saw a hotspot suddenly cool in the planet’s southern hemisphere, creating a strong polar vortex. They also spotted hydrocarbon ice in a cloud at roughly 300 kilometers (186 miles) above the surface. Researchers studying the observations called the finding surprising because ice formation on Titan requires temperatures of about minus 234 degrees Fahrenheit (minus 148 degrees Celsius).

That's substantially cooler than temperatures observed at similar altitudes and latitudes in 2011. The vortex took more than two years to enter a settled state and set off chain reactions through the rest of the planet’s atmosphere.

“This effect is so far unique in the solar system and is only possible because of Titan’s exotic atmospheric chemistry,” Nick Teanby of the University of Bristol said in a press statement. “A similar effect could also be occurring in many exoplanet atmospheres, having implications for cloud formation and atmospheric dynamics.”

Teanby is the lead author on a paper describing the conditions on Titan. The paper appears in the journal Nature Communications.

Titan is the only known moon that has a thick atmosphere. The atmosphere on Titan is so thick that its orange-colored gases completely shroud the surface below. The atmosphere is 98 percent nitrogen, but several types of trace gases are present, such as hydrogen cyanide, acetylene, cyanoacetylene, and propylene.

The new data comes from the Cassini spacecraft, which orbited Saturn's system for 13 years between 2004 and 2017. The probe made 127 Titan flybys and observed Saturn's system for almost half of the 29.5 years it takes the planet to orbit the sun. This long timespan allowed Cassini to compare winter in the moon’s northern hemisphere to winter in its southern hemisphere.

Titan is unique in the solar system because cooling gases are produced through photochemical interactions high in the atmosphere, meaning the chemical reactions are triggered by exposure to the sun. "This does not happen on the other terrestrial planets — Earth, Venus, and Mars — as the major atmospheric cooler on those planets is [carbon dioxide]," the authors wrote. The gases on those planets are more uniformly mixed between latitudes. So changes in trace gases at the poles don't spur the same kinds of effects.

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Righty blue whales sometimes act like lefties, study finds

A blue whale dives into the water off the California coast.

Blue whales are the largest animals in the world, with bodies that can weigh as much as 25 elephants and extend over the length of a basketball court. To support their hulking bodies, the whale use various acrobatic maneuvers to scoop up many individually tiny prey, filtering the water back out through massive baleen plates. In most cases, the whales roll to the right as they capture their prey, just as most people are right-handed. But, researchers reporting in Current Biology on November 20 now show that the whales shift directions and roll left when performing 360° barrel rolls in shallow water.

The findings offer the first evidence of "handedness" in blue whales, the researchers say. They also highlight the importance of studying animals in their natural three-dimensional environments for revealing phenomena that may be impossible to capture in a captive environment.

"We believe that this left-side bias is the result of the whales maintaining a visual connection with their prey with their right eye," says Ari Friedlaender at the University of California, Santa Cruz. "If the whales turned to the right on approach, they would lose sight of their prey and decrease the ability to forage successfully. By rolling to the left, the whales may be maintaining this visual connection to their prey."

"To the best of our knowledge, this is the first example where animals show different lateralized behaviors depending on the context of the task that is being performed," says study co-author James Herbert-Read from Stockholm University in Sweden.

Friedlaender and his colleagues have long studied blue whales' feeding behaviors in an attempt to understand how they can support their large bodies. In the new study, the researchers attached motion-sensing tags to 63 blue whales living off the coast of California to capture how the animals move as they engulf their prey.

In total, the researchers collected data on more than 2,800 rolling lunges for prey to find that the animals approach their prey using two different rolling behaviors. In some cases, they roll to the side and then back, turning 180° or less. In other cases, they go in for a complete barrel roll that takes them around full circle.

The evidence shows that individual whales have a preference as to whether they roll to the right or the left. The vast majority of the whales showed a preference for rolling to the right, much as more people show a preference for using their right hands. But, the whales also showed some flexibility in their approach. When the animals did a barrel roll in shallow water to attack a small patch of prey from below at a steep angle, they more often spun left, going against their general preference.

The findings are the first to demonstrate a left-side bias for a lateralized routine behavior, the researchers say. They also highlight blue whales' adaptability when it comes to feeding behaviors. The whales shift their foraging strategies depending on where they are feeding in the water column, how their prey are behaving, and how they need to maneuver to forage successfully.

"We were completely surprised by these findings, but when considering the means by which the whales attack smaller prey patches, the behavior really seems to be effective, efficient, and in line with the mechanisms that drive their routine foraging behaviors," Friedlaender says.

"While most other large baleen whales that lunge-feed can feed on both krill patches and small forage fish like anchovies and herring, blue whales feed almost exclusively on krill patches and seem to exhibit feeding strategies to maximize their intake of as many krill as possible with each energetically costly feeding event," adds co-author Dave Cade at Stanford University.

Read more at Science Daily

Rise in oxygen levels links to ancient explosion of life, researchers find

The photograph shows the Shingle Pass section in east central Nevada, where late Cambrian to Middle Ordovician (460 to 495 million years ago) limestone rocks are exposed. These strata were sampled for carbon and sulfur isotopic analysis in order to estimate atmospheric oxygen levels based on certain isotopic trends. At Shingle Pass, oxygen levels do not appear to increase until near the end of the evolving section (460 million years ago), and perhaps this is just about the spot where an abundance of macro fauna fossils begin to be seen, such as trilobites, corals and cephalopods.

Oxygen has provided a breath of fresh air to the study of the Earth's evolution some 400-plus million years ago.

A team of researchers, including a faculty member and postdoctoral fellow from Washington University in St. Louis, found that oxygen levels appear to increase at about the same time as a three-fold increase in biodiversity during the Ordovician Period, between 445 and 485 million years ago, according to a study published Nov. 20 in Nature Geoscience.

"This oxygenation is supported by two approaches that are mostly independent from each other, using different sets of geochemical records and predicting the same amount of oxygenation occurred at roughly the same time as diversification," said Cole Edwards, the principal investigator of a study conducted when he was a postdoctoral fellow in the lab under the paper's senior author, David Fike, associate professor in Earth and Planetary Sciences in Arts & Sciences. The other authors are Matthew Saltzman of Ohio State University and Dana Royer of Wesleyan University in Connecticut.

"We made another link between biodiversification and oxygen levels, but this time during the Ordovician where near-modern levels of oxygen were reached about 455 million years ago," said Edwards, assistant professor in geological and environmental sciences at Appalachian State in Boone, N.C. "It should be stressed that this was probably not the only reason why diversification occurred at that time. It is likely that other changes -- such as ocean cooling, increased nutrient supply to the oceans and predation pressures -- worked together to allow animal life to diversify for millions of years."

This explosion of diversity, recognized as the Great Ordovician Biodiversification Event, brought about the rise of various marine life, tremendous change across species families and types, as well as changes to the Earth, starting at the bottom of the ocean floors. Asteroid impacts were among the many disruptions studied as the reasons for such an explosion of change. Edwards, Fike and others wanted to continue to probe the link between oxygen levels in the ocean-atmosphere and diversity levels of animals through deep time.

Estimating such oxygen levels is particularly difficult: There is no way to directly measure the composition of ancient atmospheres or oceans. Time machines exist only in fiction.

Using geochemical proxies, high-resolution data and chemical signatures preserved in carbonate rocks formed from seawater, the researchers were able to identify an oxygen increase during the Middle and Late Ordovician periods -- and a rapid rise, at that. They cite a nearly 80-percent increase in oxygen levels where oxygen constituted about 14 percent of the atmosphere during the Darriwilian Stage (Middle Ordovician 460-465 million years ago) and increased to as high as 24 percent of the atmosphere by the mid-Katian (Late Ordovician 450-455 million years ago).

"This study suggests that atmospheric oxygen levels did not reach and maintain modern levels for millions of years after the Cambrian explosion, which is traditionally viewed as the time when the ocean-atmosphere was oxygenated," Edwards said. "In this research, we show that the oxygenation of the atmosphere and shallow ocean took millions of years, and only when shallow seas became progressively oxygenated were the major pulses of diversification able to take place."

The chemical signatures that served as proxies for dissolved inorganic carbon included data from geologic settings ranging from the Great Basin in the western United States, to the northern and eastern U.S., to Canada and its Maritimes, as well as Argentina in the Southern Hemisphere and Estonia in the Eastern Hemisphere. Nevada, Utah, Oklahoma, Missouri (New London north and Highway MM south of St. Louis), Iowa, Ohio, West Virginia and Pennsylvania were among the data points across the U.S.

The researchers concluded that it remained unclear whether the increased oxygenation had a direct effect on animal life, or even if it had a passive effect by, say, expanding the oxygen-rich ecospace. So it is difficult to resolve if temperature, increased oxygenation or something else served as the driver for biodiversification. But the findings showed that oxygen certainly was spiking during the times of some of the greatest change.

Read more at Science Daily

Astronomers reveal nearby stars that are among the oldest in our galaxy

Artist's concept of the Milky Way Galaxy.

Astronomers have discovered some of the oldest stars in our Milky Way galaxy by determining their locations and velocities, according to a study led by scientists at Georgia State University.

Just like humans, stars have a life span: birth, youth, adulthood, senior and death. This study focused on old or "senior citizen" stars, also known as cool subdwarfs, that are much older and cooler in temperature than the sun.

The Milky Way is nearly 14 billion years old, and its oldest stars developed in the early stage of the galaxy's formation, making them about six to nine billion years old. They're found in the halo, a roughly spherical component of the galaxy that formed first, in which old stars move in orbits that are highly elongated and tilted. Younger stars in the Milky Way rotate together along the galaxy's disc in roughly circular orbits, much like horses on a merry-go-round.

In this study, published in the November 2017 edition of The Astronomical Journal, astronomers conducted a census of our solar neighborhood to identify how many young, adult and old stars are present. They targeted stars out to a distance of 200 light years, which is relatively nearby considering the galaxy is more than 100,000 light years across. A light year is how far light can travel in one year. This is farther than the traditional horizon for the region of space that is referred to as "the solar neighborhood," which is about 80 light years in radius.

"The reason my horizon is more distant is that there are not a lot of senior citizens (old stars) in our solar neighborhood," said Dr. Wei-Chun Jao, lead author of the study and research scientist in the Department of Physics and Astronomy at Georgia State. "There are plenty of adult stars in our solar neighborhood, but there's not a lot of senior citizens, so we have to reach farther away in the galaxy to find them."

The astronomers first observed the stars over many years with the 0.9 meter telescope at the United State's Cerro Tololo Inter-American Observatory in the foothills of the Chilean Andes. They used a technique called astrometry to measure the stars' positions and were able to determine the stars' motions across the sky, their distances and whether or not each star had a hidden companion orbiting it.

The team's work increased the known population of old stars in our solar neighborhood by 25 percent. Among the new subdwarfs, the researchers discovered two old binary stars, even though older stars are typically found to be alone, rather than in pairs.

"I identified two new possible double stars, called binaries," Jao said. "It's rare for senior citizens to have companions. Old folks tend to live by themselves. I then used NASA's Hubble Space Telescope to detect both stars in one of the binaries and measured the separation between them, which will allow us to measure their masses."

Jao also outlined two methods to identify these rare old stars. One method uses stars' locations on a fundamental map of stellar astronomy known as the Hertzsprung-Russell (H-R) diagram. This is a classic technique that places the old stars below the sequence of dwarf stars such as the sun on the H-R diagram, hence the name "subdwarfs."

The authors then took a careful look at one particular characteristic of known subdwarf stars -- how fast they move across the sky.

"Every star moves across the sky," Jao said. "They don't stay still. They move in three dimensions, with a few stars moving directly toward or away from us, but most moving tangentially across the sky. In my research, I've found that if a star has a tangential velocity faster than 200 kilometers per second, it has to be old. So, based on their movements in our galaxy, I can evaluate whether a star is an old subdwarf or not. In general, the older a star is, the faster it moves."

They applied the tangential velocity cutoff and compared stars in the subdwarf region of the H-R diagram to other existing star databases to identify an additional 29 previously unidentified old star candidates.

In 2018, results from the European Space Agency's Gaia mission, which is measuring accurate positions and distances for millions of stars in the Milky Way, will make finding older stars much easier for astronomers. Determining the distance of stars is now very labor intensive and requires a lot of telescope time and patience. Because the Gaia mission will provide a much larger sample size, Jao says the limited sample of subdwarfs will grow, and the rarest of these rare stars -- binary subdwarfs -- will be revealed.

Read more at Science Daily

Liquid Water Might Not Be the Cause of Dark Streaks on Mars

Recurring slope linea on the surface of Mars

Bad news for microbes that want to make a home on Mars: A new study argues that dark streaks on the Martian surface are not caused by underground supplies of liquid water.

In 2015, observations by NASA's Mars Reconnaissance Orbiter revealed trace amounts of water (mixed with heavy doses of salts) on the Red Planet's surface. These "hydrated salts" corresponded with dark streaks on Martian hillsides called recurring slope lineae (RSL), which researchers had already identified as possible sites of liquid water rising to the surface.

Studies of RSL, and in particular the findings by the MRO, introduced the tantalizing possibility that there could be enough liquid water on the surface of Mars today to support microbial life.

But the new study shows that those dark RSL could simply be flows of sand and other granular material, according to a statement from NASA. In addition, the authors provide more reasons why the liquid water explanation does not fit with certain features of RSL.

"We've thought of RSL as possible liquid water flows, but the slopes are more like what we expect for dry sand," Colin Dundas, a research geologist with the US Geological Survey's Astrogeology Science Center and a lead author on the new study, said in the statement. "This new understanding of RSL supports other evidence that shows that Mars today is very dry."

However, neither study can fully explain all the features of the Martian RSL, and the authors of the new paper admit the mystery may not be solved until a rover or a human expedition can explore those regions directly.

This processed, false-color image of Mars' Hale Crater was taken by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. The image highlights dark streaks on the Martian surface known as recurring slope lineae or RSL's.

Granular flows

Thousands of RSL sites have been identified on Martian slopes surface, in about 50 hilly regions spread out between the north and south midlatitudes, according to the statement from NASA. The streaks appear during warm seasons and shrink or disappear during winter. Similar features on Earth are only caused by "seeping water," officials said in the statement, but "how they form in the dry Martian environment remains unclear."

The new study offers an alternative explanation to flowing water.

When sand and other granular materials are lumped into piles, the material locks into place until the pile reaches a certain height. At that point, some of the grains begin to slip and flow smoothly down the sides, forming rivulets. Those rivers of material could appear darker than the material around them, according to the statement, and thus could explain the RSL.

And there's another key piece of evidence that the authors point to in support of this hypothesis: For a given type of granular material (such as sand), there is a specific angle at which those rivulets can form, and it's known as the "angle of repose." The authors show that the RSL that have been observed so far only appear on hillsides that reach the angle of repose for sand dunes. If the RSL sites were created by water, the authors postulate that these features should also appear on gentler slopes.

"The RSL don't flow onto shallower slopes, and the lengths of these are so closely correlated with the dynamic angle of repose, it can't be a coincidence," Alfred McEwen, a professor of planetary geology at the University of Arizona, Tucson, said in the statement. McEwen is the HiRISE Principal Investigator and a co-author of the new report.

The research also relies on models of slope steepness using data from the High Resolution Imaging Science Experiment (HiRISE) camera on MRO. The paper includes examinations of 151 RSL features at 10 sites. Another study, published in March, suggested that the RSL were caused by "dry avalanches."

A home for life

The findings do not negate the detection of hydrated salts by MRO, and liquid water may still play a role in the formation and seasonal evolution of RSL streaks, according to the paper. But, similar to a 2016 study, they contend the hypothesis that the water comes from beneath the surface.

The authors propose that the water detected in the RSL is sucked from the thin Martian atmosphere, rather than supplied by underground reserves. The increase in hydration could cause changes in the granular material on these slopes that triggers some of the flow that creates the dark streaks. The dark regions could also be the result of "changes in hydration," according to the statement.

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