Killer Whales Engage in Cross-Species Vocal Learning

A newly published study reveals that killer whales (Orcinus orca) can engage in cross-species vocal learning, revealing that they shifted the types of sounds they made to more closely match the bottlenose dolphins they cross-socialized with.

Washington, D.C. — From barks to gobbles, the sounds that most animals use to communicate are innate, not learned. However, a few species, including humans, can imitate new sounds and use them in appropriate social contexts. This ability, known as vocal learning, is one of the underpinnings of language.

Vocal learning has also been observed in bats, some birds, and cetaceans, a group that includes whales and dolphins. But while avian researchers have characterized vocal learning in songbirds down to specific neural pathways, studying the trait in large marine animals has presented more of a challenge.

Now, University of San Diego graduate student Whitney Musser and Hubbs-Sea World Research Institute senior research scientist Dr. Ann Bowles have found that killer whales (Orcinus orca) can engage in cross-species vocal learning: when socialized with bottlenose dolphins, they shifted the types of sounds they made to more closely match their social partners. The results, published in The Journal of the Acoustical Society of America, suggest that vocal imitation may facilitate social interactions in cetaceans.

Killer whales have complex vocal repertoires made up of clicks, whistles and pulsed calls—repeated brief bursts of sound punctuated with silence. The acoustic features of these vocalizations, such as their duration, pitch and pulse pattern, vary across social groups. Whales that are closely related or live together produce similar pulsed calls that carry vocal characteristics distinct to the group, known as a dialect.

“There’s been an idea for a long time that killer whales learn their dialect, but it isn’t enough to say they all have different dialects so therefore they learn. There needs to be some experimental proof so you can say how well they learn and what context promotes learning,” said Bowles.

Testing vocal learning ability in social mammals usually requires observing the animal in a novel social situation, one that might stimulate them to communicate in new ways. Bottlenose dolphins provide a useful comparison species in this respect: they make generally similar sounds but produce them in different proportions, relying more on clicks and whistles than the pulsed calls that dominate killer whale communication.

“We had a perfect opportunity because historically, some killer whales have been held with bottlenose dolphins,” said Bowles. By comparing old recordings of vocalization patterns from the cross-socialized subjects with recordings of killer whales and bottlenose dolphins housed in same-species groups, Bowles and her team were able to evaluate the degree to which killer whales learned vocalization patterns from their cross-species social partners.

All three killer whales that had been housed with dolphins for several years shifted the proportions of different call types in their repertoire to more closely match the distribution found in dolphins—they produced more clicks and whistles and fewer pulsed calls. The researchers also found evidence that killer whales can learn completely new sounds: one killer whale that was living with dolphins at the time of the experiment learned to produce a chirp sequence that human caretakers had taught to her dolphin pool-mates before she was introduced to them.

Vocal learning skills alone don’t necessarily mean that killer whales have language in the same way that humans do. However, they do indicate a high level of neural plasticity, the ability to change circuits in the brain to incorporate new information. “Killer whales seem to be really motivated to match the features of their social partners,” said Bowles, though the adaptive significance of the behavior is not yet known.

There are immediate reasons to study the vocal patterns of cetaceans: these marine mammals are threatened by human activities through competition for fishery resources, entanglement in fishing gear, collisions with vessels, exposure to pollutants and oil spills and, ultimately, shrinking habitats due to anthropogenic climate change. If their social bonds are closely linked to their vocalizations, killer whales’ ability to survive amidst shifting territories and social groups may be tied to their ability to adapt their communication strategies.

“It’s important to understand how they acquire [their vocalization patterns], and lifelong, to what degree they can change it, because there are a number of different [cetacean] populations on the decline right now,” said Bowles. “And where killer whales go, we can expect other small whale species to go—it’s a broader question.”

Publication: Whitney B. Musser, et al., “Differences in acoustic features of vocalizations produced by killer whales cross-socialized with bottlenose dolphins,” Journal of the Acoustical Society of America, 136, 1990 (2014); DOI: 10.1121/1.4893906

Source: Acoustical Society of America (ASA)

Noninvasive Arterial Spin Labeling MRI Detects Evidence of Cognitive Decline Before Symptoms Appear

Brain perfusion. Red indicates low perfusion, yellow indicates high perfusion. Overall, the brain perfusion is similar between all three groups. The most prominent difference is present in the posterior cingulate cortex (indicated by the arrow), a region close to the midline in the superior and posterior part of the brain. Control participants who remain stable have higher perfusion as compared to deteriorating controls and MCI.

A new study shows that a noninvasive arterial spin labeling MRI can detect signs of cognitive decline in the brain even before symptoms appear, finding that patients who showed reduced brain perfusion at their initial exams exhibited cognitive decline at follow-up 18 months later.

Oak Brook, Illinois — A magnetic resonance imaging (MRI) technique can detect signs of cognitive decline in the brain even before symptoms appear, according to a new study published online in the journal Radiology. The technique has the potential to serve as a biomarker in very early diagnosis of preclinical dementia.

The World Health Organization estimates that dementia affects more than 35 million people worldwide, a number expected to more than double by 2030. Problems in the brain related to dementia, such as reduced blood flow, might be present for years but are not evident because of cognitive reserve, a phenomenon where other parts of the brain compensate for deficits in one area. Early detection of cognitive decline is critical, because treatments for Alzheimer’s disease, the most common type of dementia, are most effective in this early phase.

Researchers recently studied arterial spin labeling (ASL), a promising MRI technique that doesn’t require injection of a contrast agent. ASL measures brain perfusion, or penetration of blood into the tissue.

“ASL MRI is simple to perform, doesn’t require special equipment and only adds a few minutes to the exam,” said study author Sven Haller, M.D., from the University of Geneva in Geneva, Switzerland.

The study group included 148 healthy elderly participants and 65 people with mild cognitive impairment (MCI). The participants underwent brain MRI and a neuropsychological assessment, a common battery of tests used to determine cognitive ability.

ROC curve analysis of the pairwise comparison between groups. ASL relative CBF in PCC enabled discrimination of (a) dCON (P ˂ .001) and (b) MCI (P˂ .001) from sCON; however, there was no difference between (c) dCON and MCI.

Of the 148 healthy individuals, 75 remained stable, while 73 deteriorated cognitively at 18 months clinical follow-up. Those who deteriorated had shown reduced perfusion at their baseline ASL MRI exams, particularly in the posterior cingulate cortex, an area in the middle of the brain that is associated with the default mode network, the neural network that is active when the brain is not concentrating on a specific task. Declines in this network are seen in MCI patients and are more pronounced in those with Alzheimer’s disease.

The pattern of reduced perfusion in the brains of healthy individuals who went on to develop cognitive deficits was similar to that of patients with MCI.

“There is a known close link between neural activity and brain perfusion in the posterior cingulate cortex,” Dr. Haller said. “Less perfusion indicates decreased neural activity.”

The results suggest that individuals with decreased perfusion detected with ASL MRI may temporarily maintain their cognitive status through the mobilization of their cognitive reserve, but will eventually develop subtle cognitive deficits.

Previous research done with positron emission tomography (PET), the current gold standard for brain metabolism imaging, found that patients with Alzheimer’s disease had reduced metabolism in the same area of the brain where the perfusion abnormalities were found using ASL MRI. This points to a close link between brain metabolism and perfusion, according to Dr. Haller.

ASL MRI has potential as a standalone test or as an adjunct to PET for dementia screening, Dr. Haller said. While PET can identify markers of Alzheimer’s disease in the brain and cerebrospinal fluid, it exposes the patient to radiation. ASL does not expose the patient to radiation and is easy to perform in routine clinical settings.

“ASL might replace the classic yet unspecific fluordesoxyglucose PET that measures brain metabolism. Instead, PET could be done with the new and specific amyloid PET tracers,” Dr. Haller said.

The results also support a role for ASL MRI as an alternative to neuropsychological testing.

The researchers plan to perform follow-up studies on the patient group to learn more about ASL and long-term cognitive changes.

Publication: Aikaterini Xekardaki, et al., “Arterial Spin Labeling May Contribute to the Prediction of Cognitive Deterioration in Healthy Elderly Individuals,” Radiology, 2014; DOI: 10.1148/radiol.14140680

Source: Radiological Society of North America

Temperature Variability Across the World Alters the Ecological Impacts of Seasons

Global variation in temperature cycling. Each point represents a weather station (7,906 total) for which we determined (for the entire temperature record, longest record: 1926–2010): mean temperature (a,e), the range of diurnal temperature cycling (DTC; b,f), the range of annual temperature cycling (ATC; c,g), and the natural log of the ratio of DTC to ATC (ln(D/A); d,h). Right-hand figures show latitudinal variation in these variables, with latitude on the y axis, value on the x axis, and cubic spline fits (λ = 0.6) indicated by black lines. For each figure pair, the colour of the point indicates its value, with the scale shown on the right-hand plot. Grey dashed lines indicate tropical boundaries.

New research from the Max Planck Institute for Developmental Biology and the University of Wyoming details how changes in temperature variability across the globe are altering the environment.

If more of the world’s climate becomes like that in tropical zones, it could potentially affect crops, insects, malaria transmission, and even confuse migration patterns of birds and mammals worldwide. George Wang, a postdoctoral fellow at the Max Planck Institute for Developmental Biology in Tübingen, Germany, is part of a research tandem that has found that the daily and nightly differences in temperatures worldwide are fast approaching yearly differences between summer and winter temperatures.

Only recently, the UN Climate Summit came together in New York to further address the necessary measures to protect the Earth from a dramatic climate change. It has long been recognized that an increase of the average temperature will cause rising oceans and thus flooded landscapes. Particularly, regions close to the coasts are endangered. While it is well known that climate change has increased average temperatures, it is less clear how temperature variability has altered with climate change.

Postdoctoral fellow George Wang, from Detlef Weigel’s Department for Molecular Biology at the Max Planck Institute for Developmental Biology, has now examined this issue in more depth.

He realized that existing climate measures did not provide enough information to predict the life history responses, such as hatching, hibernation, or flowering of organisms. Together with his partner Michael Dillon, an Assistant Professor in the Department of Zoology and Physiology, University of Wyoming, USA, he started to analyze climate conditions since records began to be kept.

“We describe, for the first time, changes in temperature variability across the globe. We’ve had a long discussion about changes in the mean temperature. It has been ongoing for over 30 years,” says George Wang. “It’s very clear mean temperatures have shifted across the globe. It’s less clear if the variation in temperature has changed.”

For example, the variability in temperature could potentially mean bugs survive for a longer period in non-tropical regions. The result could be increased crop damage from pest insects or spread of diseases, such as malaria transmitted by mosquitoes.

In addition, plants in temperate regions are adapted to use temperature to tell the season. This is how they know when to produce flowers and fruits. As daily temperature cycles become more extreme, it becomes harder for plants to behave appropriately to the season. Therefore, plants might produce flowers too early or too late, and so there might be some years where certain fruits never appear.

Wang is first author of a paper, titled “Recent Geographic Convergence in Diurnal and Annual Temperature Cycling Flattens Global Thermal Profiles,” that was published in the online edition of Nature Climate Change. Dillon is the paper’s co-writer. The monthly journal is dedicated to publishing the most significant and cutting-edge research on the science of climate change, its impacts and wider implications for the economy, society and policy.

Wang and Dillon first estimated global spacial variation in the mean temperature and in temperature cycling by analyzing more than 1 billion temperature measurements from 7,906 weather stations that sampled from the period of Jan. 1, 1926, through Dec. 31, 2009. Analysis of monthly and yearly averages of daily temperature extremes reveals that daily and annual minimum and maximum temperatures have increased across the world since 1950. The scientists then estimated global changes in the magnitudes of diurnal and annual temperature cycles from 1975-2013.

The research was “very computationally intensive”, as Michael Dillon points out. The researchers had to use computer clusters on two continents, with the majority of the work performed on the cluster at the MPI for Developmental Biology. They also used a new mathematical technique to describe how temperature changes from day to night, and winter to summer, thus characterizing the variability of temperature over the globe.

According to this, the changes have been most dramatic for places closest to the poles and far from oceans. “In these places, warmer winters — decreasing the difference between summer and winter — and hotter days — increasing the difference between day and night — mean that the range of temperatures, which organisms experience over a few days, is closer to the range of temperatures they experience over an entire year. These patterns are strongest in Canada and Russia, but occur even in Germany,” explains Wang. “For example, in Wiesbaden, in 1992, the average difference between day and night was 1.2 degrees, while the average difference between summer and winter was 24.8 degrees. In 2012, the day/night cycle was 5.2 degrees, while the summer/winter cycle was 18.9, so the daily temperature variability is now much more similar to the yearly variability. Compare this to Las Palmas in the Canary Islands, where the day/night difference is about 4.3 degrees and the summer/winter difference is about 6.7 — it has not changed very much.”

The range of diurnal temperature cycling (DTC), meaning the change in temperature from the daytime high to nighttime low, was lowest at the poles, intermediate at the tropics and was relatively small close to large bodies of water and at lower elevations, according to the study. The range of annual temperature cycling (ATC), meaning temperatures for any given location will go through a regular cycle on an annual basis, was lowest at the tropics and increased toward the poles.

“For these temperature zones that we historically think of as having lower daily variations relative to the annual variations in temperatures, what we found in these zones is that the ATC has not changed much in the last 30 to 40 years,” Michael Dillon explains. “But, the DTC has gone up considerably. If the annual is constant and daily temperatures increase, areas outside the tropics will become more tropical. This idea of convergence could be a really important thing.”

The findings show that no place is safe from climate change. “Most people are rightly concerned about sea level rise, but feel that this will not affect them if they don’t live next to the ocean. We find that places far from the oceans will have be biggest changes in daily and seasonal temperature variability, because they are far away from the buffering effects of oceans”, says Wang. Therefore, there would be no places immune from effects of climate change, and this would have consequences on crops, parasites, and disease.

Publication: George Wang & Michael E. Dillon, “Recent geographic convergence in diurnal and annual temperature cycling flattens global thermal profiles,” Nature Climate Change, 2014; doi:10.1038/nclimate2378

Source: Max Planck Institute

NuSTAR Discovers Brightest Pulsar to Date

A rare and mighty pulsar (pink) can be seen at the center of the galaxy Messier 82 in this new multi-wavelength portrait. NASA’s NuSTAR mission discovered the “pulse” of the pulsar — a type of dead star — using is high-energy X-ray vision. Image Credit: NASA/JPL-Caltech

Using NASA’s Nuclear Spectroscopic Telescope Array, astronomers have detected the brightest pulsar to date, located about 12 million light-years away in the galaxy Messier 82.

Astronomers have found a pulsating, dead star beaming with the energy of about 10 million suns. This is the brightest pulsar – a dense stellar remnant left over from a supernova explosion – ever recorded. The discovery was made with NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR.

“You might think of this pulsar as the ‘Mighty Mouse’ of stellar remnants,” said Fiona Harrison, the NuSTAR principal investigator at the California Institute of Technology in Pasadena, California. “It has all the power of a black hole, but with much less mass.”

The discovery appears in a new report in the Thursday Oct. 9 issue of the journal Nature.

The surprising find is helping astronomers better understand mysterious sources of blinding X-rays, called ultraluminous X-ray sources (ULXs). Until now, all ULXs were thought to be black holes. The new data from NuSTAR show at least one ULX, about 12 million light-years away in the galaxy Messier 82 (M82), is actually a pulsar.

This animation shows a neutron star — the core of a star that exploded in a massive supernova. This particular neutron star is known as a pulsar because it sends out rotating beams of X-rays that sweep past Earth like lighthouse beacons. Image Credit: NASA/JPL-Caltech

“The pulsar appears to be eating the equivalent of a black hole diet,” said Harrison. “This result will help us understand how black holes gorge and grow so quickly, which is an important event in the formation of galaxies and structures in the universe.”

ULXs are generally thought to be black holes feeding off companion stars — a process called accretion. They also are suspected to be the long-sought after “medium-size” black holes – missing links between smaller, stellar-size black holes and the gargantuan ones that dominate the hearts of most galaxies. But research into the true nature of ULXs continues toward more definitive answers.

NuSTAR did not initially set out to study the two ULXs in M82. Astronomers had been observing a recent supernova in the galaxy when they serendipitously noticed pulses of bright X-rays coming from the ULX known as M82 X-2. Black holes do not pulse, but pulsars do.

Pulsars belong to a class of stars called neutron stars. Like black holes, neutron stars are the burnt-out cores of exploded stars, but puny in mass by comparison. Pulsars send out beams of radiation ranging from radio waves to ultra-high-energy gamma rays. As the star spins, these beams intercept Earth like lighthouse beacons, producing a pulsed signal.

“We took it for granted that the powerful ULXs must be massive black holes,” said lead study author Matteo Bachetti, of the University of Toulouse in France. “When we first saw the pulsations in the data, we thought they must be from another source.”

NASA’s Chandra X-ray Observatory and Swift satellite also have monitored M82 to study the same supernova, and confirmed the intense X-rays of M82 X-2 were coming from a pulsar.

“Having a diverse array of telescopes in space means that they can help each other out,” said Paul Hertz, director of NASA’s astrophysics division in Washington. “When one telescope makes a discovery, others with complementary capabilities can be called in to investigate it at different wavelengths.”

The key to NuSTAR’s discovery was its sensitivity to high-energy X-rays, as well as its ability to precisely measure the timing of the signals, which allowed astronomers to measure a pulse rate of 1.37 seconds. They also measured its energy output at the equivalent of 10 million suns, or 10 times more than that observed from other X-ray pulsars. This is a big punch for something about the mass of our sun and the size of Pasadena.

How is this puny, dead star radiating so fiercely? Astronomers are not sure, but they say it is likely due to a lavish feast of the cosmic kind. As is the case with black holes, the gravity of a neutron star can pull matter off companion stars. As the matter is dragged onto the neutron star, it heats up and glows with X-rays. If the pulsar is indeed feeding off surrounding matter, it is doing so at such an extreme rate to have theorists scratching their heads.

Astronomers are planning follow-up observations with NASA’s NuSTAR, Swift and Chandra spacecraft to find an explanation for the pulsar’s bizarre behavior. The NuSTAR team also will look at more ULXs, meaning they could turn up more pulsars. At this point, it is not clear whether M82 X-2 is an oddball or if more ULXs beat with the pulse of dead stars. NuSTAR, a relatively small telescope, has thrown a big loop into the mystery of black holes.

“In the news recently, we have seen that another source of unusually bright X-rays in the M82 galaxy seems to be a medium-sized black hole,” said astronomer Jeanette Gladstone of the University of Alberta, Canada, who is not affiliated with the study. “Now, we find that the second source of bright X-rays in M82 isn’t a black hole at all. This is going to challenge theorists and pave the way for a new understanding of the diversity of these fascinating objects.”

Publication: M. Bachetti, et al., “An ultraluminous X-ray source powered by an accreting neutron star,” Nature 514, 202–204 (09 October 2014); doi:10.1038/nature13791

Source: Felicia Chou, NASA

NASA Scientists Share Microgravity Bone Research

Micro-computed tomography bone density imaging shows ground mice (G) with highly connected, dense spongy bone structure, flight mice (F) with less connectivity and flight mice treated with a myostatin inhibitor (F+D) on STS-118 that appear to have bone structure unaffected by microgravity. Image Credit: Bioserve

At this year’s American Society for Bone and Mineral Research conference, NASA scientists shared what they’ve learned from a half century of related space flight research about how microgravity negatively affects bone density.

Once you reach your fifties, you may anticipate some health changes, such as the beginning of bone loss. You may not expect such challenges in your prime—that is, unless you suffered from osteoporosis, limited mobility or were an astronaut. Scientists have known since the early days of space flight that microgravity negatively affects bone density at an advanced rate. Examining this consequence of living in space provides researchers the opportunity for accelerated study of bone health.

Bone research began at the start of human space travel, with experiments both in space and on the ground. This area of study continues today aboard the International Space Station with investigations that build on their predecessors. Crew members stand to lose about as much bone density in one month as a post-menopausal woman loses in the course of a year. Scientists can turn this negative into a positive, using the microgravity conditions to accomplish more research in less time. Their investigations in space examine the causes of bone loss and identify countermeasures, while contributing to the development of treatments for use on Earth and in space.

“In a six month mission, we can do research on counteracting bone loss that would take an equivalent of roughly a five-year longitudinal study on Earth,” said Scott M. Smith, Ph.D., manager for the Nutritional Biochemistry Laboratory at NASA’s Johnson Space Center in Houston. “This helps us to see changes in physiology faster than on Earth, and in a study population very different than the typical [ground] studies. This perspective contributes to overall understanding and provides a valuable addition to the general knowledge base—allowing us all to get to treatments faster.”

In a recent publication, “Fifty Years of Human Space Travel: Implications for Bone and Calcium Research,” Scott and his colleagues look back on lessons learned. He points out that in the pursuit to combat bone loss in microgravity, we gain ground on advancing bone health on Earth. For instance, model animal research using rodents in space has already contributed to clinical trials for pharmaceuticals that can mitigate bone loss. Some of these treatments already are available for people to use.

Research continues on orbit, such as with the Pro-K investigation, which will finish sample collection with the current crew. The goal of Pro-K is to develop a way to optimize nutrition by examining how diet impacts bones. Specifically, researchers are looking at how a decreased ratio of animal protein to potassium that an astronaut consumes may mitigate bone breakdown. The question is if the crew eats more fruits and vegetables with less meat, will this help improve skeletal health?

The findings may have implications for those suffering bone loss on Earth, providing possible mitigation through the right balance in an individual’s diet. “The work done for space travelers contributes uniquely to the overall knowledge base in the fields of nutrition and bone biology,” said Smith.

Building better bones is not as simple as drinking your milk, though, regardless of if you drink from a glass or a space coffee cup. While vitamin D and calcium are among the important components, it’s actually a complex quest for scientists to identify the right balance of countermeasures, which fall into three categories: physical, pharmacological and nutritional. What researchers found is that nutrition is a large part of this equation, but it works in combination with the right type and amount of exercise. These findings were published in the Journal of Bone and Mineral Research.

“We’ve seen in the past few years that nutrition and exercise can help protect bone mineral density in astronauts,” said Smith. “That’s the first time in more than a half century of space flight that we’ve seen this. We’re not done, but we are making progress, and that is incredibly exciting.”

Scientists had suspected that, just as on Earth, diet and exercise were a winning team to keep human bones healthy. Application of this knowledge, however, didn’t immediately translate into the space environment. Initial attempts to exercise on the Mir space station and early days on the International Space Station showed little impact to mitigating bone loss. The crew needed resistance-based exercise that provided enough “weight” to productively stress bones and muscles. Enter the Advanced Resistance Exercise Device (ARED), which launched in 2008. The addition of ARED helped researchers prove that the right kind of exercise, combined with nutrition, could maintain bone mineral density.

“What was shown,” said Smith in his publication, “is that crew members who had access to the ARED returned from flight with no loss of body mass, an increased percentage of lean mass, a decreased percentage of fat mass, and maintenance of bone mineral density in most regions and in whole body scans.”

The role of minerals and diet in bone health came into a different focus during space station habitation. In 2009, as the crew conducted water reclamation using urine—a necessity for long-duration space exploration—the system had to be shut down because of pressure concerns. It turns out that an excess of minerals, in particular calcium sulfate, was clogging the hardware. Sulfur, used in the space station toilet, had combined with calcium crew members lost as a result of the accelerated bone breakdown in space. The resulting high concentration of calcium in the astronaut’s urine pointed not only to the relationship between bone loss and calcium, but also to the need to increase crew members’ water consumption. Similarly, increased water consumption helps keep kidney stone risk low—another concern for astronauts.

Researchers continue to look at the right amount of calcium intake and other dietary factors for bone health, including vitamin D, omega-3 fatty acids, protein and potassium, sodium, iron and phosphorus. The next study planned for space station seeking the optimal balance of diet and nutrition for bone health is called Integrated Nutrition. The experiments will be a joint effort of NASA’s Space Food Systems Laboratory and the Nutritional Biochemistry Laboratory teams at Johnson.

“We’re working to optimize intake of a number of dietary factors known to have protective effects on bone in ground-based or flight research to help to protect bone during long-duration spaceflight,” said Smith. “We’re very optimistic about the prospects for this for bone and believe this is likely to have beneficial effects on many other body systems as well.”

Part of this multifaceted concern is to examine bone strength, not just as a whole, but according to which parts of the bone are building during countermeasures. Researchers hope to find out if the apparent prevention is actually just the buildup of additional bone from resistance-based exercise, rather than a halting of loss overall. The goal is to go beyond just density to understand how spaceflight impacts the strength of the bone.

“Although this mode of bone remodeling, with increases in bone resorption and formation, maintained bone mineral density, it may yield a bone with different strength characteristics than existed before flight,” Scott continued. “Studies to assess bone strength after flight are underway at NASA to better understand this phenomenon.”

And in case you wondered, based on the earlier comparison to a post-menopausal woman’s bone loss, researchers are looking at gender, too. During the course of studies on orbit, researchers have found similarities between the sexes with regard to processing bone mineral breakdown.

“In July of this year, we published data showing that the response of men and women to space flight—and to diet and exercise—was not different with regard to bone and renal stone risk,” said Smith. “The number of astronauts flown is still relatively small…but growing all the time. The space station has provided a great platform, and it has already given us many years of long-duration flights. We’re starting to be able to see differences in response as countermeasures evolve and differences among sub-groups of astronauts.”

Publications:

• Smith SM., et al., “Men and women in space: bone loss and kidney stone risk after long-duration spaceflight,” Journal of Bone and Mineral Research, 2014 Jul;29(7):1639-45. doi: 10.1002/jbmr.2185.
• Scott M Smith, et al., “Benefits for bone from resistance exercise and nutrition in long-duration spaceflight: Evidence from biochemistry and densitometry,” Journal of Bone and Mineral Research, Volume 27, Issue 9, pages 1896–1906, 2012; DOI: 10.1002/jbmr.1647

Yale Engineers Develop Hybrid System for Quantum Communication

Using microwaves and magnets, researchers at the Yale School of Engineering & Applied Science developed a hybrid system for quantum communication.

Yale engineers have developed a hybrid system that strongly couples magnons—the smallest unit of measurement for a magnetic spin excitation—with microwave photons. According to the researchers, the hybrid system achieved an ultrahigh coherence between the two platforms that makes the system suitable for storing and transferring information.

“Magnons, because they can interact with many different information carriers, can be an ideal bridge to platforms as diverse as microwaves, light waves, and acoustic waves,” says Hong Tang, associate professor of electrical engineering, physics & applied physics and principal investigator of the research published October 7 in Physical Review Letters. “This ability makes magnons a promising new platform for quantum communication and possibly for the development of a quantum computer.”

The Yale team’s hybrid system utilized a small sphere made of yttrium iron garnet (YIG)—a magnetic insulator that has very low magnon attenuation—placed inside a microwave cavity. The geometry of both the YIG sphere and the cavity resulted in uniform coupling between the microwave photons and magnons, and at a higher quality than previous experiments that used YIG thin films. The coupling was in fact so strong that information carried by the microwave signal can be written to or read from the magnon five billion times per second; such a processing speed allowed the information stored in a single magnon to be accessed 10,000 times before its energy was dissipated and the information lost.

In addition to the ultrahigh coherence and ultrastrong coupling between the magnons and microwave photons, the researchers also argue for further magnon use because of the platform’s high tunability and nonlinearity; these two attributes enable the platform to flexibly couple with other platforms.

“Nonlinearity is also crucial because it enables not only integration with other platforms, but also more complex manipulations to the information signal itself, such as one magnon being split into two magnons, each with half the energy of the original magnon, or perhaps two identical magnons being converted into two magnons with different frequencies,” says Xufeng Zhang, a Yale engineering doctoral student and lead author of the paper. “Our next step is to explore such nonlinear processes. With these linear and nonlinear properties, magnons become a very promising candidate as carriers for information processing and communication.”

Other authors of the article include Chang-Ling Zou and Liang Jiang. The article is titled “Strongly Coupled Magnons and Cavity Microwave Photons.”

Publication: Xufeng Zhang, et al., “Strongly Coupled Magnons and Cavity Microwave Photons,” Phys. Rev. Lett. 113, 156401, 2014; doi:10.1103/PhysRevLett.113.156401

PDF Copy of the Study: Strongly coupled magnons and cavity microwave photons

Researchers Detail the Structure and Dynamics of the HIV Spike Protein

Structure of the HIV spike protein in its closed state, which makes it less detectable to immune system. (Illustration by Peter Kwong)

In two newly published studies, researchers detail the structure and dynamics of the HIV spike protein, which is used by the virus uses to fuse with and enter cells.

HIV is adept at eluding immune system responses because the protein it uses to infect cells is constantly changing.

Now a team of researchers including scientists from Yale have stripped the cloak from this master of disguise, providing a high resolution image of this surface spike protein and monitoring how it constantly changes its shape, information that suggests new ways to attack the virus through drugs and vaccines.

In two papers published simultaneously online October 8 in the journals Science and Nature, a team of researchers led by scientists from the labs of Walther Mothes at Yale University, Peter Kwong at Vaccine Research Center at the National Institute of Allergy and Infectious Diseases and Scott Blanchard at Weill Cornell Medical College describe the structure and dynamics of the HIV spike protein, which the virus uses to fuse with and enter cells.

“Now we can see how this fusion machine works, and in a general way it is similar to how fusion works in influenza and Ebola,” said Mothes, associate professor of microbial pathogenesis and co-senior author of the Science paper.

The spike protein needs to be in “an open state” to fuse with and infect cells. However, in its closed state it is less visible to antibodies. Thus, the spike protein tries to stay longer in the closed state and only briefly opens, making it more difficult to attack the virus.

Mothes noted that new research explains why a class of antibodies – discovered in few AIDS patients – offer protection against the disease. These broadly neutralizing antibodies keep this spike protein closed and thereby prevent the spread of the virus.

“The determination of the structure of this closed configuration of the HIV spike protein and the direct visualization of its fast openings represent a major step forward for drug and vaccine design,” Mothes said.

James B. Munro of Yale is the lead author of the Science paper. Blanchard of Cornell is co-senior author. Kwong of the NIAID is senior author of the Nature paper.

Funding for the studies were provided by the National Institutes of Health, The Cancer Research Institute, the China Scholarships Council, the International AIDS Vaccine Initiative, the Bill & Melinda Gates Foundation and the United States Agency for International Development (USAID).

Publications:

• James B. Munro, et al., “Conformational dynamics of single HIV-1 envelope trimers on the surface of native virions,” Science, 2014; DOI: 10.1126/science.1254426
• Marie Pancera, et al., “Structure and immune recognition of trimeric pre-fusion HIV-1 Env,” Nature (2014); doi:10.1038/nature13808

Black Hole Consumes Gas 10 Times Faster Than Previously Thought Possible

Primary Image: A combined optical/X-ray image of NGC 7793 Credit: X-ray (NASA/CXC/Univ of Strasbourg/M. Pakull et al); Optical (ESO/VLT/Univ of Strasbourg/M. Pakull et al); H-alpha (NOAO/AURA/NSF/CTIO 1.5m)
Inset image: A rendering of what P13 would look like close up. Credit: created by Tom Russell (ICRAR) using software created by Rob Hynes (Louisiana State University).

In a new study, a team of astronomers reveals that the black hole known as P13 is consuming gas from a nearby star 10 times faster than previously thought possible.

Astronomers have discovered a black hole that is consuming gas from a nearby star 10 times faster than previously thought possible. The black hole—known as P13—lies on the outskirts of the galaxy NGC7793 about 12 million light years from Earth and is ingesting a weight equivalent to 100 billion billion hot dogs every minute.

The discovery was published today in the journal Nature.

International Center for Radio Astronomy Research astronomer Dr Roberto Soria, who is based at ICRAR’s Curtin University node, said that as gas falls towards a black hole it gets very hot and bright. He said scientists first noticed P13 because it was a lot more luminous than other black holes, but it was initially assumed that it was simply bigger.

“It was generally believed the maximum speed at which a black hole could swallow gas and produce light was tightly determined by its size,” Dr Soria said.

“So it made sense to assume that P13 was bigger than the ordinary, less bright black holes we see in our own galaxy, the Milky Way.”

When Dr Soria and his colleagues from the University of Strasbourg measured the mass of P13 they found it was actually on the small side, despite being at least a million times brighter than the Sun. It was only then that they realized just how much material it was consuming.

“There’s not really a strict limit like we thought, black holes can actually consume more gas and produce more light,” Dr Soria said. Dr Soria said P13 rotates around a supergiant ‘donor’ star 20 times heavier than our own Sun.

He said the scientists saw that one side of the donor star was always brighter than the other because it was illuminated by X-rays coming from near the black hole, so the star appeared brighter or fainter as it went around P13.

“This allowed us to measure the time it takes for the black hole and the donor star to rotate around each other, which is 64 days, and to model the velocity of the two objects and the shape of the orbit,” Dr Soria said.

“From this, we worked out that the black hole must be less than 15 times the mass of our Sun.”

Dr Soria compared P13 to small Japanese eating champion Takeru Kobayashi.

“As hotdog-eating legend Takeru Kobayashi famously showed us, size does not always matter in the world of competitive eating and even small black holes can sometimes eat gas at an exceptional rate,” he said.

Dr Soria said P13 is a member of a select group of black holes known as ultraluminous X-ray sources.

“These are the champions of competitive gas eating in the Universe, capable of swallowing their donor star in less than a million years, which is a very short time on cosmic scales,” he said.

Publication: C. Motch, et al, “A mass of less than 15 solar masses for the black hole in an ultraluminous X-ray source,” Nature 514, 198–201 (09 October 2014); doi:10.1038/nature13730

Source: International Center for Radio Astronomy Research

Image: X-ray (NASA/CXC/Univ of Strasbourg/M. Pakull et al); Optical (ESO/VLT/Univ of Strasbourg/M. Pakull et al); H-alpha (NOAO/AURA/NSF/CTIO 1.5m); Tom Russell

Astrophysicists Reveal Amount of Dark Matter is Less Than Previously Thought

Artist’s impression of the Milky Way and its dark matter halo (shown in blue, but in reality invisible). Credit: ESO/L. Calçada

New research from the University of Western Australia reveals that the amount of dark matter in the Milky Way is half as much as previously thought.

Australian astronomers used a method developed almost 100 years ago to discover that the weight of dark matter in our own galaxy is 800,000,000,000 (or 8 x 1011) times the mass of the Sun.

They probed the edge of the Milky Way, looking closely, for the first time, at the fringes of the galaxy about 5 million billion kilometers from Earth.

Astrophysicist Dr Prajwal Kafle, from The University of Western Australia node of the International Center for Radio Astronomy Research, said we have known for a while that most of the Universe is hidden.

“Stars, dust, you and me, all the things that we see, only make up about 4 per cent of the entire Universe,” he said.

“About 25 per cent is dark matter and the rest is dark energy.”

Dr Kafle, who is originally from Nepal, was able to measure the mass of the dark matter in the Milky Way by studying the speed of stars throughout the galaxy, including the edges, which had never been studied to this detail before.

This animation shows a supercomputer simulation of a galaxy like the Milky Way and its invisible dark matter halo. We zoom in to the galaxy and can see knots of dark matter where we would expect to see many satellite galaxies, but they don’t exist in the real Universe. That’s the missing satellite problem. Credit: Prof Chris Power and Dr Rick Newton, ICRAR. Music by Reuben Christman

He used a robust technique developed by British astronomer James Jeans in 1915 — decades before the discovery of dark matter.

Dr Kafle’s measurement helps to solve a mystery that has been haunting theorists for almost two decades.

“The current idea of galaxy formation and evolution, called the Lambda Cold Dark Matter theory, predicts that there should be a handful of big satellite galaxies around the Milky Way that are visible with the naked eye, but we don’t see that,” Dr Kafle said.

“When you use our measurement of the mass of the dark matter the theory predicts that there should only be three satellite galaxies out there, which is exactly what we see; the Large Magellanic Cloud, the Small Magellanic Cloud and the Sagittarius Dwarf Galaxy.”

University of Sydney astrophysicist Professor Geraint Lewis, who was also involved in the research, said the missing satellite problem had been “a thorn in the cosmological side for almost 15 years.”

“Dr Kafle’s work has shown that it might not be as bad as everyone thought, although there are still problems to overcome,” he said.

The study also presented a holistic model of the Milky Way, which allowed the scientists to measure several interesting things such as the speed required to leave the galaxy.

“Be prepared to hit 550 kilometers per second if you want to escape the gravitational clutches of our galaxy,” Dr Kafle said.

“A rocket launched from Earth needs just 11 kilometers per second to leave its surface, which is already about 300 times faster than the maximum Australian speed limit in a car!”

Publication: Prajwal Raj Kafle, et al., “On the Shoulders of Giants: Properties of the Stellar Halo and the Milky Way Mass Distribution,” 2014, ApJ, 794, 59;doi:10.1088/0004-637X/794/1/59