Neutrinos yield first experimental evidence of catalyzed fusion dominant in many stars

 An international team of about 100 scientists of the Borexino Collaboration, including particle physicist Andrea Pocar at the University of Massachusetts Amherst, report in Nature this week detection of neutrinos from the sun, directly revealing for the first time that the carbon-nitrogen-oxygen (CNO) fusion-cycle is at work in our sun.

The CNO cycle is the dominant energy source powering stars heavier than the sun, but it had so far never been directly detected in any star, Pocar explains.

For much of their life, stars get energy by fusing hydrogen into helium, he adds. In stars like our sun or lighter, this mostly happens through the 'proton-proton' chains. However, many stars are heavier and hotter than our sun, and include elements heavier than helium in their composition, a quality known as metallicity. The prediction since the 1930's is that the CNO-cycle will be dominant in heavy stars.

Neutrinos emitted as part of these processes provide a spectral signature allowing scientists to distinguish those from the 'proton-proton chain' from those from the 'CNO-cycle.' Pocar points out, "Confirmation of CNO burning in our sun, where it operates at only one percent, reinforces our confidence that we understand how stars work."

Beyond this, CNO neutrinos can help resolve an important open question in stellar physics, he adds. That is, how the sun's central metallicity, as can only be determined by the CNO neutrino rate from the core, is related to metallicity elsewhere in a star. Traditional models have run into a difficulty -- surface metallicity measures by spectroscopy do not agree with the sub-surface metallicity measurements inferred from a different method, helioseismology observations.

Pocar says neutrinos are really the only direct probe science has for the core of stars, including the sun, but they are exceedingly difficult to measure. As many as 420 billion of them hit every square inch of the earth's surface per second, yet virtually all pass through without interacting. Scientists can only detect them using very large detectors with exceptionally low background radiation levels.

The Borexino detector lies deep under the Apennine Mountains in central Italy at the INFN's Laboratori Nazionali del Gran Sasso. It detects neutrinos as flashes of light produced when neutrinos collide with electrons in 300-tons of ultra-pure organic scintillator. Its great depth, size and purity make Borexino a unique detector for this type of science, alone in its class for low-background radiation, Pocar says. The project was initiated in the early 1990s by a group of physicists led by Gianpaolo Bellini at the University of Milan, Frank Calaprice at Princeton and the late Raju Raghavan at Bell Labs.

Until its latest detections, the Borexino collaboration had successfully measured components of the 'proton-proton' solar neutrino fluxes, helped refine neutrino flavor-oscillation parameters, and most impressively, even measured the first step in the cycle: the very low-energy 'pp' neutrinos, Pocar recalls.

Its researchers dreamed of expanding the science scope to also look for the CNO neutrinos -- in a narrow spectral region with particularly low background -- but that prize seemed out of reach. However, research groups at Princeton, Virginia Tech and UMass Amherst believed CNO neutrinos might yet be revealed using the additional purification steps and methods they had developed to realize the exquisite detector stability required.

Over the years and thanks to a sequence of moves to identify and stabilize the backgrounds, the U.S. scientists and the entire collaboration were successful. "Beyond revealing the CNO neutrinos which is the subject of this week's Nature article, there is now even a potential to help resolve the metallicity problem as well," Pocar says.

Before the CNO neutrino discovery, the lab had scheduled Borexino to end operations at the close of 2020. But because the data used in the analysis for the Nature paper was frozen, scientists have continued collecting data, as the central purity has continued to improve, making a new result focused on the metallicity a real possibility, Pocar says. Data collection could extend into 2021 since the logistics and permitting required, while underway, are non-trivial and time-consuming. "Every extra day helps," he remarks.

Pocar has been with the project since his graduate school days at Princeton in the group led by Frank Calaprice, where he worked on the design, construction of the nylon vessel and the commissioning of the fluid handling system. He later worked with his students at UMass Amherst on data analysis and, most recently, on techniques to characterize the backgrounds for the CNO neutrino measurement.

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Breaking the skill limit, pianists attain more delicate touch

 In JST Strategic Basic Research Programs, Drs. Masato Hirano and Shinichi Furuya, Sony Computer Science Laboratories, Inc., discovered a training method to further improve the delicate touch of pianists.

Experts such as pianists, athletes and surgeons acquire advanced skills through tremendous amounts of practice. It is difficult to further improve upon these skills, and the methods for exceeding these limits have not been clarified.

The research group developed a system that freely controls the weight of piano keys using a haptic device, which enables to control the strength and direction of the force. This same group has also invented active haptic training (AHT) that enhances tactile force sense during exercise by presenting the tasks of discriminating the difference in piano key weights and the correctness of answers. Three experiments were conducted using AHT in 64 pianists and 25 ordinary persons who had received no professional music training. The results showed that enhancing the somatosensory function of fingertips with AHT could improve the accuracy of keystrokes, breaking through the ceiling effect of over-trained skills. Such skill improvement was not observed through usual repetitive practice, or in ordinary persons with no piano experience.

This study demonstrated that, in order to exceed the limits in the exercise skills of experts, it was important to optimize the method rather than increase the amount of training. This finding is expected to be useful for elucidating principles of the nervous system that define the limits in exercise skills, new training theories to exceed the limits of experts' expertise, and functional flexibility (plasticity) of the expert's brain, as well as in the development of rehabilitation methods for neurological disorders in which finger functions were impaired due to excessive training.

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Motor neural population activity patterns are different for reach and grasp behaviors

 A new study from researchers at the University of Chicago has found that neuronal population dynamics in the motor cortex are very different during reaching and grasping behavior, challenging a popular theory that indicated intrinsic, dynamic patterns control motor behaviors.

Prior research examining neural population dynamics in the motor cortex of macaque monkeys had shown that during the planning and execution of a reaching movement with the arm, populations of neurons exhibited rotational dynamics -- cascades of smooth and orderly waves of neuronal activity that pass through the motor cortex.

This population-level behavior has been interpreted as showing that the motor cortex acts as a pattern generator that drives muscles to give rise to movements.

"In the previous work on reaching, my colleagues and I showed that brain areas that control movement act like a little machine for generating muscle commands," said co-author Matthew Kaufmann, PhD, an assistant professor of organismal biology and anatomy at UChicago. "That is, the activity followed mathematical "rules" that let it act like a music box, to get each muscle's commands timed correctly relative to the others."

Researchers suggested that these activity patterns represent a general principle of neuronal activity within the motor cortex, and that these elegant dynamics are a property of the neural circuits.

"The activity pattern is a bit like a domino effect," explained senior author Sliman Bensmaia, PhD, the James and Karen Frank Family Professor of Organismal Biology and Anatomy at UChicago. "The idea is that as the behavior starts, it's like knocking over that first domino, and then all the rest will fall in order. If you set it back up, it'll do the same sequence again."

However, this new research, looking instead at hand-grasping behavior rather than arm-reaching behavior, did not see such a neat pattern. The study, published Nov. 17 in E-Life, examined neural activity in the motor cortex.

"We wanted to know whether the same type of neural dynamics was present during hand movements, which involve a very different effector, producing very different movements," said co-first author Aneesha Suresh, PhD, a former graduate student in the Bensmaia lab. "We recorded neural activity in the motor cortex of monkeys as they performed a reach task and a grasp task to compare the dynamics of the two motions."

In contrast to past results, the investigators found that grasping behaviors instead produced less orderly neuronal activity patterns at the population level and little evidence of the rotational dynamics seen with reaching motions.

"We expected neurons in this network to be activated in orderly, predictable sequences, like the ones thought to drive the arm as it reaches toward a target," said co-first author James Goodman, PhD, now a postdoctoral scientist at the German Primate Center. "Instead, the patterns of activity we saw during grasping were far more complex and chaotic, in some respects suggesting an especially important role for the senses of touch and proprioception during hand movements."

These results make sense in the context of the differences between reaching movements and grasping movements. "Conceptually, the jobs that the arm and the hand do are different," said co-author Nicholas Hatsopoulous, PhD, a professor of organismal biology and anatomy and neurology at UChicago. "The arm moves the hand and brings the hand to different locations for actions like waving or reaching for a cup. The hand, on the other hand, is usually involved in manipulating objects such as grasping things, typing on a keyboard, and so on."

This study raises new questions, such as why this elegant activity pattern exists for reaching movements but not for grasping, and whether similar patterns exist for other types of movement patterns. "The brain uses this kind of pattern for reach, and the implication was that the brain would use it for other movements, too, and that maybe the pattern applies even in other systems," said Bensmaia. "But we've shown that this pattern doesn't generalize everywhere, and then the question is, how general is it, really?"

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Cooking with wood may cause lung damage

 Advanced imaging with CT shows that people who cook with biomass fuels like wood are at risk of suffering considerable damage to their lungs from breathing in dangerous concentrations of pollutants and bacterial toxins, according to a study being presented at the annual meeting of the Radiological Society of North America (RSNA).

Approximately 3 billion people around the world cook with biomass, such as wood or dried brush. Pollutants from cooking with biomass are a major contributor to the estimated 4 million deaths a year from household air pollution-related illness.

While public health initiatives have tried to provide support to transition from biomass fuels to cleaner-burning liquefied petroleum gas as a fuel source, a significant number of homes continue to use biomass fuels. Financial constraints and a reluctance to change established habits are factors, combined with a lack of information on the impact of biomass smoke on lung health.

"It is important to detect, understand and reverse the early alterations that develop in response to chronic exposures to biomass fuel emissions," said study co-author Abhilash Kizhakke Puliyakote, Ph.D., a postdoctoral researcher from the University of California San Diego School of Medicine.

A multidisciplinary team led by Eric A. Hoffman, Ph.D., at the University of Iowa, in collaboration with researchers from Periyar Maniammai Institute of Science and Technology, investigated the impact of cookstove pollutants in 23 people cooking with liquefied petroleum gas or wood biomass in Thanjavur, India.

The researchers measured the concentrations of pollutants in the homes and then studied the lung function of the individuals, using traditional tests such as spirometry. They also used advanced CT scanning to make quantitative measurements -- for instance, they acquired one scan when the person inhaled and another after they exhaled and measured the difference between the images to see how the lungs were functioning.

Analysis showed that the ones who cooked with wood biomass were exposed to greater concentrations of pollutants and bacterial endotoxins compared to liquefied petroleum gas users. They also had a significantly higher level of air trapping in their lungs, a condition associated with lung diseases.

"Air trapping happens when a part of the lung is unable to efficiently exchange air with the environment, so the next time you breathe in, you're not getting enough oxygen into that region and eliminating carbon dioxide," Dr. Kizhakke Puliyakote said. "That part of the lung has impaired gas exchange."

The researchers found a smaller subset of the biomass users who had very high levels of air trapping and abnormal tissue mechanics, even when compared to other biomass users. In about one-third of the group, more than 50% of the air they inhaled ended up trapped in their lungs.

"This increased sensitivity in a subgroup is also seen in other studies on tobacco smokers, and there may be a genetic basis that predisposes some individuals to be more susceptible to their environment," Dr. Kizhakke Puliyakote said.

CT added important information on smoke's effect on the lungs that was underestimated by conventional tests.

"The extent of damage from biomass fuels is not really well captured by traditional tests," Dr. Kizhakke Puliyakote said. "You need more advanced, sensitive techniques like CT imaging. The key advantage to using imaging is that it's so sensitive that you can detect subtle, regional changes before they progress to full blown disease, and you can follow disease progression over short periods of time."

The lack of emphysema in the study group suggests that exposure to biomass smoke is affecting the small airways in the lungs, Dr. Kizhakke Puliyakote said, although more research is needed to understand the disease process. Regardless, the study results underscore the importance of minimizing exposure to smoke. Even in the absence of overt symptoms or breathing difficulties, the lung may have injury and inflammation that can go undetected and potentially unresolved in some people.

"For people exposed to biomass smoke for any extended duration, it is critical to have a complete assessment of lung function by health care professionals to ensure that any potential injury can be resolved with appropriate interventions," Dr. Kizhakke Puliyakote said.

While the study focused on cooking with biomass, the findings have important implications for exposure to biomass smoke from other sources, including wildfires.

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Understanding the power of our Sun

 Stars produce their energy through nuclear fusion by converting hydrogen into helium -- a process known to researchers as "hydrogen burning." There are two ways of carrying out this fusion reaction: one, the so-called pp cycle (proton-proton reaction) or the other, the Bethe Weizsäcker cycle (also known as the CNO cycle, derived from the elements carbon (C), nitrogen (N) and oxygen (O)).

The pp cycle is the predominant energy source in our Sun, only about 1.6 per mil of its energy comes from the CNO cycle. However, the Standard Solar Model (SSM) predicts that the CNO cycle is probably the predominant reaction in much larger stars. As early as the 1930s, the cycle was theoretically predicted by the physicists Hans Bethe and Carl Friedrich von Weizsäcker and subsequently named after these two gentlemen. While the pp cycle could already be experimentally proven in 1992 at the GALLEX experiment, also in the Gran Sasso massif, the experimental proof of the CNO cycle has so far not been successful.

Both the pp cycle and the CNO cycle produce countless neutrinos -- very light and electrically neutral elementary particles. The fact that neutrinos hardly interact with other matter allows them to leave the interior of the sun at almost the speed of light and to transport the information about their origin to earth unhindered. Here the ghost particles have no more than to be captured. This is a rather complex undertaking, which is only possible in a few large-scale experiments worldwide, since neutrinos show up as small flashes of light in a huge tank full of a mixture of water, mineral oil and other substances, also called scintillator. The evaluation of the measured data is complex and resembles looking for a needle in a haystack.

Compared to all previous and ongoing solar neutrino experiments, Borexino is the first and only experiment worldwide that is able to measure these different components individually, in real time and with a high statistical power. This week, the Borexino research collaboration was able to announce a great success: In the scientific journal Nature, they present their results on the first experimental detection of CNO neutrinos -- a milestone in neutrino research.

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Dogmatic people seek less information even when uncertain

 People who are dogmatic about their views seek less information and make less accurate judgements as a result, even on simple matters unrelated to politics, according to a study led by UCL and Max Planck Institute for Biological Cybernetics researchers.

The researchers say their findings, published in PNAS, point to differences in thinking patterns that lead people to hold rigid opinions.

First author Lion Schulz, a PhD candidate at the Max Planck Institute in Germany who began the research while at UCL, said: "Anecdotally, it seems that dogmatic people are less interested in information that might change their mind. However, it was unclear if this is because a specific opinion is of high importance to them or if more fundamental processes are at play that transcend specific opinions."

Dogmatic people are characterised by a belief that their worldview reflects an absolute truth and are often resistant to change their mind, for example when it comes to partisan issues. This tendency can have societal impacts by polarising political, scientific and religious debates. However, the cognitive drivers of dogmatism are still poorly understood.

To investigate this, the researchers asked over 700 people to perform a simple decision-making task. Participants saw two boxes with flickering dots and had to decide which box contained more of the dots. Critically, after the participants had made an initial choice, the researchers gave them the chance to view another, clearer version of the boxes. They then made a final decision.

Schulz explained: "This mirrors many real-life situations -- for example, when we hear a rumour but aren't sure if it's true. Do we share it, or do we check a credible source beforehand?"

Joint first author, Dr Max Rollwage (Wellcome Centre for Human Neuroimaging at UCL and Max Planck UCL Centre for Computational Psychiatry & Ageing Research) said: "By using simple tasks, we were able to minimise motivational or social influences and pin down drivers of altered evidence processing that contribute to dogmatic beliefs."

The task was followed by a comprehensive set of questionnaires that allowed the researchers to measure participants' political orientation and levels of dogmatism.

Dogmatic individuals and moderates did not differ in their accuracy or confidence of their decisions. However, the researchers found that more dogmatic participants were more likely to decline the helpful additional information.

The differences between more and less dogmatic participants were especially large when participants had little confidence in a decision. Senior author Dr Steve Fleming (Wellcome Centre for Human Neuroimaging at UCL, Max Planck UCL Centre for Computational Psychiatry & Ageing Research and UCL Experimental Psychology) said: "Previous work has found that there is a close link between how confident we feel and whether or not we seek out new information. In the current study we found that this link was weaker in more dogmatic individuals."

In general, the reduced search was detrimental, with more dogmatic people being less accurate in their final judgements.

Dr Fleming added: "It is striking that we could detect links between dogmatism about issues such as politics, and information-seeking in a simple online game. This tells us that real-world dogmatism isn't just a feature of specific groups or opinions but may be associated with more fundamental cognitive processes."

The study highlights that simply having corrective information available does not necessarily mean people will consume it.

Schulz said: "This is particularly relevant today. We have never been so free to decide if we have enough evidence about something or whether we should seek out further information from a reliable source before believing it.

"It is also important to stress that the differences between more and less dogmatic people were subtle, and we don't know yet how they would manifest when considering real-world information such as news about political parties. In the end, it's a cautionary tale, whether we think of ourselves as dogmatic or not: when uncertain, it might be wise to check the information again."

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Memories of past events retain remarkable fidelity even as we age

 Scientists studying the complex relationship between aging and memory have found that in a controlled experiment, people can remember the details about past events with a surprising 94% accuracy, even accounting for age. These results, published in the journal Psychological Science, suggest that the stories we tell about past events are accurate, although details tend to fade with time.

"These results are surprising to many, given the general pessimism about memory accuracy among scientists and the prevalent idea that memory for one-time events is not to be trusted," said Nicholas Diamond, the study's lead researcher, a former graduate student at Baycrest's Rotman Research Institute (RRI), and currently a postdoctoral researcher at the University of Pennsylvania.

About 400 academics, including memory scientists, surveyed as part of this study estimated memory accuracy to be around 40% at best, expecting this score to be even lower for older participants or when greater amounts of time had elapsed since the events.

"This study shows us that memory accuracy is actually quite good under normal circumstances, and it remains stable as we age," said Brian Levine, a senior scientist at RRI and a professor of psychology and neurology at the University of Toronto and co-author on the study. "These results will be helpful for understanding memory in healthy aging."

For their study, the researchers created an immersive, scientifically controlled event for their participants: a 30-minute audio-guided tour of art and other items displayed at Baycrest. Two days later, participants were asked to tell the researcher everything they could remember about the tour. The responses were recorded and then verified against the facts.

The researchers also tested Baycrest employees on their recall of a standardized, scripted procedure that they had experienced one month to three years prior. This allowed the researchers to examine the effect of delay between the event and memory recall, while the standardized nature of the procedure made it possible to verify accuracy.

Using standardized, verifiable events to test memory is an innovative approach, the researchers said, as scientists typically use artificial laboratory stimuli, such as random word lists, rather than real-life experiences, or they test participants' memory for personal past experiences, which cannot be verified.

"This pessimism originates from earlier studies showing that memory can be manipulated using certain testing methods," said Levine. "While those studies were important in showing the ways in which memory can fail, we wanted to know what happens when people freely recall events without such manipulation. We found that they are overwhelmingly accurate."

The results showed that participants' accuracy was high in both cases, though, as expected, the number of details they remembered decreased with age and time. At best, they recalled about 25% of their experience. "This suggests that we forget the majority of details from everyday events, but the details we do recall correspond to the reality of the past," Diamond said.

In a related study also published in Psychological Science, Diamond and Levine examined the degree to which people's memories matched the true order of events. In this case, younger adults tended to perform better than older adults, suggesting that while accuracy of details remains high with age, older adults are less likely to correctly remember the true sequence of past events. That is, the order of our memories becomes disorganized as we age.

"The results of these studies can contribute to identifying differences in memory among those who develop dementia," said Dr. Levine.

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New study explains important cause of fatal influenza

 It is largely unknown why influenza infections lead to an increased risk of bacterial pneumonia. Researchers at Karolinska Institutet in Sweden have now described important findings leading to so-called superinfections, which claim many lives around the world every year. The study is published in the journal PNAS, Proceedings of the National Academy of Sciences, and can also contribute to research on COVID-19.

The Spanish Flu was an influenza pandemic that swept across the world in 1918-20 and unlike many other pandemics disproportionately hit young otherwise healthy adults. One important reason for this was so-called superinfections caused by bacteria, in particular pneumococci.

Influenza is caused by a virus, but the most common cause of death is secondary bacterial pneumonia rather than the influenza virus per se. Pneumococcal infections are the most common cause of community-acquired pneumonia and a leading global cause of death. A prior influenza virus infection sensitizes for pneumococcal infections, but mechanisms behind this increase susceptibility are not fully understood. Researchers at Karolinska Institutet have now identified influenza-induced changes in the lower airways that affect the growth of pneumococci in the lungs.

Using an animal model, the researchers found that different nutrients and antioxidants, such as vitamin C and other normally cell protective substances leak from the blood, thereby creating an environment in the lungs that favours growth of the bacteria. The bacteria adapt to the inflammatory environment by increasing the production of the bacterial enzyme HtrA.

The presence of HtrA weakens the immune system and promotes bacterial growth in the influenza-infected airways. The lack of HtrA stops bacterial growth.

"The ability of pneumococcus to grow in the lower airways during an influenza infection seems to depend on the nutrient-rich environment with its higher levels of antioxidants that occurs during a viral infection, as well as on the bacteria's ability to adapt to the environment and protect itself from being eradicated by the immune system," says principal investigator Birgitta Henriques Normark, professor at the Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet.

The results provide valuable information on how bacteria integrate with their environment in the lungs and could be used to find new therapies for double infections between the influenza virus and pneumococcal bacteria.

"HtrA is an enzyme, a protease, which helps to weaken the immune system and allows pneumococcal bacteria to penetrate the protective cell layer on the inside of the airways," explains the paper's first author Vicky Sender, researcher at the same department. "A possible strategy can therefore be use of protease inhibitors to prevent pneumococcal growth in the lungs."

It is still not known if COVID-19 patients are also sensitive to such secondary bacterial infections, but the researchers think that similar mechanisms could potentially be found in severely ill COVID-19 patients.

"It's likely that acute lung inflammation, regardless of cause, gives rise to leakage of nutrients and antioxidants, and to an environment that fosters bacterial growth," says Professor Henriques Normark.

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Galaxy encounter violently disturbed Milky Way

 The spiral-shaped disc of stars and planets is being pulled, twisted and deformed with extreme violence by the gravitational force of a smaller galaxy -- the Large Magellanic Cloud (LMC).

Scientists believe the LMC crossed the Milky Way's boundary around 700 million years ago -- recent by cosmological standards -- and due to its large dark matter content it strongly upset our galaxy's fabric and motion as it fell in.

The effects are still being witnessed today and should force a revision of how our galaxy evolved, astronomers say.

The LMC, now a satellite galaxy of the Milky Way, is visible as a faint cloud in the southern hemisphere's night skies -- as observed by its namesake, the 16th century Portuguese explorer Ferdinand Magellan.

Previous research has revealed that the LMC, like the Milky Way, is surrounded by a halo of dark matter -- elusive particles which surround galaxies and do not absorb or emit light but have dramatic gravitational effects on the movement of stars and gas in the universe.

Using a sophisticated statistical model that calculated the speed of the Milky Way's most distant stars, the University of Edinburgh team discovered how the LMC warped our galaxy's motion. The study, published in Nature Astronomy, was funded by UK Science and Technology Facilities Council (STFC).

The researchers found that the enormous attraction of the LMC's dark matter halo is pulling and twisting the Milky Way disc at 32 km/s or 115,200 kilometers per hour towards the constellation Pegasus.

To their surprise they also found that the Milky Way was not moving towards the LMC's current location, as previously thought, but towards a point in its past trajectory.

They believe this is because the LMC, powered by its massive gravitational force, is moving away from the Milky Way at the even faster speed of 370 km/s, around 1.3 million kilometres per hour.

Astronomers say it is as if the Milky Way is trying hard to hit a fast moving target, but not aiming very well.

This discovery will help scientists develop new modelling techniques that capture the strong dynamic interplay between the two galaxies.

Astronomers now intend to find out the direction from which the LMC first fell in to the Milky Way and the exact time it happened. This will reveal the amount and distribution of dark matter in the Milky Way and the LMC with unprecedented detail.

Dr Michael Petersen, lead author and Postdoctoral Research Associate, School of Physics and Astronomy, said:

"Our findings beg for a new generation of Milky Way models, to describe the evolution of our galaxy.

"We were able to show that stars at incredibly large distances, up to 300,000 light-years away, retain a memory of the Milky Way structure before the LMC fell in, and form a backdrop against which we measured the stellar disc flying through space, pulled by the gravitational force of the LMC."

Professor Jorge Peñarrubia, Personal Chair of Gravitational Dynamics, School of Physics and Astronomy, said:

"This discovery definitely breaks the spell that our galaxy is in some sort of equilibrium state. Actually, the recent infall of the LMC is causing violent perturbations onto the Milky Way.

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Blast from the past

 An international team of astronomers using Gemini North's GNIRS instrument have discovered that CK Vulpeculae, first seen as a bright new star in 1670, is approximately five times farther away than previously thought. This makes the 1670 explosion of CK Vulpeculae much more energetic than previously estimated and puts it into a mysterious class of objects that are too bright to be members of the well-understood type of explosions known as novae, but too faint to be supernovae.

350 years ago, the French monk Anthelme Voituret saw a bright new star flare into life in the constellation of Vulpecula. Over the following months, the star became almost as bright as Polaris (the North Star) and was monitored by some of the leading astronomers of the day before it faded from view after a year. The new star eventually gained the name CK Vulpeculae and was long considered to be the first documented example of a nova -- a fleeting astronomical event arising from an explosion in a close binary star system in which one member is a white dwarf, the remnant of a Sun-like star. However, a string of recent results have thrown the longstanding classification of CK Vulpeculae as a nova into doubt.

In 2015, a team of astronomers suggested that CK Vulpeculae's appearance in 1670 was the result of two normal stars undergoing a cataclysmic collision. Just over three years later, the same astronomers further proposed that one of the stars was in fact a bloated red giant star, following their discovery of a radioactive isotope of aluminum in the immediate surroundings of the site of the 1670 explosion. Complicating the picture even further, a separate group of astronomers proposed a different interpretation. In their paper, also published in 2018, they suggested that the sudden brightening in 1670 was the result of the merger between a brown dwarf -- a failed star too small to shine via thermonuclear fusion that powers the Sun -- and a white dwarf.

Now, adding to the ongoing mystery surrounding CK Vulpeculae, new observations from the international Gemini Observatory, a Program of NSF's NOIRLab, reveal that this enigmatic astronomical object is much farther away and has ejected gas at much higher speeds than previously reported.

This team, led by Dipankar Banerjee of Physical Research Laboratory Ahmedabad, India, Tom Geballe of Gemini Observatory, and Nye Evans of Keele University in the United Kingdom, initially planned to use the Gemini Near-Infrared Spectrograph (GNIRS) instrument on Gemini North on Hawai'i's Maunakea to confirm the 2018 detection of radioactive aluminum at the heart of CK Vulpeculae. After realizing that detecting this in the infrared would be far more difficult than they originally thought, the astronomers improvised and obtained infrared observations across the full extent of CK Vulpeculae, including the two wisps of nebulosity at its outermost edges.

"The key to our discovery was the GNIRS measurements obtained at the outer edges of the nebula," elaborated Geballe. "The signature of redshifted and blueshifted iron atoms detected there shows that the nebula is expanding much more rapidly than previous observations had suggested."

As lead author and astronomer Banerjee explains further, "We did not suspect that this is what we would find. It was exciting when we found some gas traveling at the unexpectedly high speed of about 7 million km/hour. This hinted at a different story about CK Vulpeculae than what had been theorized."

By measuring both the speed of the nebula's expansion and how much the outermost wisps had moved during the last ten years, and accounting for the tilt of the nebula on the night sky, which had been estimated earlier by others, the team determined that CK Vulpeculae lies approximately 10,000 light-years distant from the Sun -- about five times as far away as previously thought. That implies that the 1670 explosion was far brighter, releasing roughly 25 times more energy than previously estimated. This much larger estimate of the amount of energy released means that whatever event caused the sudden appearance of CK Vulpeculae in 1670 was far more violent than a simple nova.

"In terms of energy released, our finding places CK Vulpeculae roughly midway between a nova and a supernova," commented Evans. "It is one of a very few such objects in the Milky Way and the cause -- or causes -- of the outbursts of this intermediate class of objects remain unknown. I think we all know what CK Vulpeculae isn't, but no one knows what it is."

The visual appearance of the CK Vulpeculae nebula and the high velocities observed by the team could help astronomers to recognize relics of similar events -- in our Milky Way or in external galaxies -- that have occurred in the past.

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Why experiences are better gifts for older children

 What should we get for our kids this holiday? As children get older, giving them something they can experience (live through) instead of material things makes them happier, according to new research led by Lan Nguyen Chaplin, associate professor of marketing at the University of Illinois Chicago.

The research, published in the International Journal of Research in Marketing, compared the level of happiness children derive from material goods with the level of happiness they derive from experiences.

Across four studies with children and adolescents, Chaplin and her collaborators demonstrated that children ages 3-12 derive more happiness from material things than from experiences. However, older children derive more happiness from their experiences than from their possessions.

"What this means is, experiences are highly coveted by adolescents, not just expensive material things, like some might think," Chaplin says.

She goes on to explain, "Don't get me wrong. Young children do love experiences. Entire industries (e.g., theme parks such as Disneyland) are built around this premise. In fact, young children are ecstatic throughout the experience. However, for experiences to provide enduring happiness, children must be able to recall details of the event long after it is over."

Long after they have unwrapped their Legos and stuffed animals, there will still be a physical reminder to give them a "jolt" of happiness. However, young children can't see or touch experiences after they are over, making it harder for them to appreciate experiences long after the event is over. There's an easy and inexpensive fix though, according to Chaplin.

"Take pictures or videos of family walks, playing in the snow, and birthday parties," she said. "Children are likely going to appreciate those experiences more if there is something to remind them of the event. Additionally, they'll be able to learn the social value of shared experiences."

Children will remember and appreciate not only the birthday gifts they received, but also the time spent with family and friends as they relive the experience through concrete reminders such as photos and videos.

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Hormone found to switch off hunger could help tackle obesity

 A hormone that can suppress food intake and increase the feeling of fullness in mice has shown similar results in humans and non-human primates, says a new study published today in eLife.

The hormone, called Lipocalin-2 (LCN2), could be used as a potential treatment in people with obesity whose natural signals for feeling full no longer work.

LCN2 is mainly produced by bone cells and is found naturally in mice and humans. Studies in mice have shown that giving LCN2 to the animals long term reduces their food intake and prevents weight gain, without leading to a slow-down in their metabolism.

"LCN2 acts as a signal for satiety after a meal, leading mice to limit their food intake, and it does this by acting on the hypothalamus within the brain," explains lead author Peristera-Ioanna Petropoulou, who was a Postdoctoral Research Scientist at Columbia University Irving Medical Center, New York, US, at the time the study was carried out, and is now at the Helmholtz Diabetes Center, Helmholtz Zentrum München, Munich, Germany. "We wanted to see whether LCN2 has similar effects in humans, and whether a dose of it would be able to cross the blood-brain barrier."

The team first analysed data from four different studies of people in the US and Europe who were either normal weight, overweight or living with obesity. The people in each study were given a meal after an overnight fast, and the amount of LCN2 in their blood before and after the meal was studied. The researchers found that in those who were of normal weight, there was an increase in LCN2 levels after the meal, which coincided with how satisfied they felt after eating.

By contrast, in people who were overweight or had obesity, LCN2 levels decreased after a meal. Based on this post-meal response, the researchers grouped people as non-responders or responders. Non-responders, who showed no increase in LCN2 after a meal, tended to have a larger waist circumference and higher markers of metabolic disease -- including BMI, body fat, increased blood pressure and increased blood glucose. Remarkably, however, people who had lost weight after gastric bypass surgery were found to have a restored sensitivity to LCN2 -- changing their status from non-responders before their surgery, to responders afterwards.

Taken together, these results mirror those seen in mice, and suggest that this loss of post-meal LCN2 regulation is a new mechanism contributing to obesity and could be a potential target for weight-loss treatments.

After verifying that LCN2 can cross into the brain, the team explored whether treatment with the hormone might reduce food intake and prevent weight gain. To do this, they treated monkeys with LCN2 for a week. They saw a 28% decrease in food intake compared with that before treatment within a week, and the monkeys also ate 21% less than their counterparts who were treated only with saline. Moreover, after only one week of treatment, measurements of body weight, body fat and blood fat levels showed a declining trend in treated animals.

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Which speaker are you listening to? Hearing aid of the future uses brainwaves to find out

 In a noisy room with many speakers, hearing aids can suppress background noise, but they have difficulties isolating one voice -- that of the person you're talking to at a party, for instance. KU Leuven researchers have now addressed that issue with a technique that uses brainwaves to determine within one second whom you're listening to.

Having a casual conversation at a cocktail party is a challenge for someone with a hearing aid, says Professor Tom Francart from the Department of Neurosciences at KU Leuven: "A hearing aid may select the loudest speaker in the room, for instance, but that is not necessarily the person you're listening to. Alternatively, the system may take into account your viewing direction, but when you're driving a car, you can't look at the passenger sitting next to you."

Researchers have been working on solutions that take into account what the listener wants. "An electroencephalogram (EEG) can measure brainwaves that develop in response to sounds. This technique allows us to determine which speaker someone wants to listen to. The system separates the sound signals produced by different speakers and links them to the brainwaves. The downside is that you have to take into account a delay of ten to twenty seconds to get it right with reasonable certainty."

Artificial intelligence to speed up the process

A new technique makes it possible to step up the pace, Professor Alexander Bertrand from the Department of Electrical Engineering at KU Leuven continues: "Using artificial intelligence, we found that it is possible to directly decode the listening direction from the brainwaves alone, without having to link them to the actual sounds."

"We trained our system to determine whether someone is listening to a speaker on their left or their right. Once the system has identified the direction, the acoustic camera redirects its aim, and the background noise is suppressed. On average, this can now be done within less than one second. That's a big leap forward, as one second constitutes a realistic timespan to switch from one speaker to the other."

From lab to real life

However, it will take at least another five years before we have smart hearing aids that work with brainwaves, Professor Francart continues. "To measure someone's brainwaves in the lab, we make them wear a cap with electrodes. This method is obviously not feasible in real life. But research is already being done into hearing aids with built-in electrodes."

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Plant evolves to stay hidden from harvesting humans

 A plant used in traditional Chinese medicine has evolved to become less visible to humans, new research shows.

Scientists found that Fritillaria delavayi plants, which live on rocky slopes of China's Hengduan mountains, match their backgrounds most closely in areas where they are heavily harvested.

This suggests humans are "driving" evolution of this species into new colour forms because better-camouflaged plants have a higher chance of survival.

The study was carried out by the Kunming Institute of Botany (Chinese Academy of Sciences) and the University of Exeter.

"It's remarkable to see how humans can have such a direct and dramatic impact on the colouration of wild organisms, not just on their survival but on their evolution itself," said Professor Martin Stevens, of the Centre for Ecology and Conservation on Exeter's Penryn Campus in Cornwall.

"Many plants seem to use camouflage to hide from herbivores that may eat them -- but here we see camouflage evolving in response to human collectors.

"It's possible that humans have driven evolution of defensive strategies in other plant species, but surprisingly little research has examined this."

In the new study, the researchers measured how closely plants from different populations matched their mountain environment and how easy they were to collect, and spoke to local people to estimate how much harvesting took place in each location.

They found that the level of camouflage in the plants was correlated with harvesting levels.

In a computer experiment, more-camouflaged plants also took longer to be detected by people.

Fritillaria delavayi is a perennial herb that has leaves -- varying in colour from grey to brown to green -- at a young age, and produces a single flower per year after the fifth year.

The bulb of the fritillary species has been used in Chinese medicine for more than 2,000 years, and high prices in recent years have led to increased harvesting.

"Like other camouflaged plants we have studied, we thought the evolution of camouflage of this fritillary had been driven by herbivores, but we didn't find such animals," said Dr Yang Niu, of the Kunming Institute of Botany. "Then we realised humans could be the reason."

Professor Hang Sun, of the Kunming Institute of Botany, added: "Commercial harvesting is a much stronger selection pressure than many pressures in nature. "The current biodiversity status on the earth is shaped by both nature and by ourselves."

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Milky Way family tree

 Galaxies like the Milky Way formed by the merging of smaller progenitor galaxies. An international team of astrophysicists led by Dr Diederik Kruijssen from the Centre for Astronomy at Heidelberg University has succeeded in reconstructing the merger history of our home galaxy, creating a complete family tree. To achieve this, the researchers analysed the properties of globular clusters orbiting the Milky Way with artificial intelligence. Their investigations revealed a previously unknown galaxy collision that must have permanently altered the appearance of the Milky Way.

Globular clusters are dense groups of up to a million stars that are almost as old as the universe itself. The Milky Way hosts over 150 of such clusters. "Many of them came from smaller galaxies that later merged to form the Milky Way that we live in today," explains Dr Kruijssen. To study the merger history, the Heidelberg researcher and his colleague Dr Joel Pfeffer of Liverpool John Moores University (United Kingdom) and their research groups developed a suite of advanced computer simulations, called E-MOSAICS. These simulations include a complete model for the formation, evolution, and destruction of globular clusters.

The German-British team used these simulations to relate the ages, chemical compositions, and orbital motions of the globular clusters to the properties of the progenitor galaxies in which they formed, more than ten billion years ago. By applying these insights to groups of globular clusters in the Milky Way, they not only determined how massive these progenitor galaxies were, but also when they merged with our home galaxy.

"The main challenge was that the merger process is extremely messy, because the orbits of the globular clusters are completely reshuffled," explains Dr Kruijssen. "To overcome this complexity, we developed an artificial neural network and trained it on the E-MOSAICS simulations. We were astonished at how precisely the artificial intelligence allowed us to reconstruct the merger histories of the simulated galaxies, using only their globular clusters." The researchers then applied the neural network to groups of globular clusters in the Milky Way and precisely determined the stellar masses and merger times of the progenitor galaxies. They also discovered a previously unknown collision between the Milky Way and an unknown galaxy, which the researchers named "Kraken."

"The collision with Kraken must have been the most significant merger the Milky Way ever experienced," Dr Kruijssen adds. Before, it was thought that a collision with the Gaia-Enceladus galaxy some nine billion years ago was the biggest collision event. However, the merger with Kraken took place eleven billion years ago, when the Milky Way was four times less massive than today. "As a result, the collision with Kraken must have truly transformed what the Milky Way looked like at the time," explains the Heidelberg scientist.

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Newfound ability to change baby brain activity could lead to rehabilitation for injured brains

 Researchers from King's College London have identified the brain activity for the first time in a newborn baby when they are learning an association between different types of sensory experiences. Using advanced MRI scanning techniques and robotics, the researchers found that a baby's brain activity can be changed through these associations, shedding new light on the possibility of rehabilitating babies with injured brains and promoting the development of life-long skills such as speech, language and movement.

Published recently in Cerebral Cortex, the researcher builds on the fact that learning associations is a very important part of babies' development but the activity inside the brain that was responsible for learning these associations was unknown and unstudied.

Lead researcher, Dr Tomoki Arichi said it is the first time it has been shown that babies' brain activity can be altered through associative learning -- and in particular, brain responses become associated with particular stimuli, in this case, sound.

"We also found that when a baby is learning, it actually is activating lots of different parts of the brain, so it is starting to incorporate the 'wider network' inside the brain which is important for processing activity," he said.

A total of 24 infants were studied by playing them a sound of a jingling bell for six seconds, coupled with a gentle movement induced by a custom-made 3D printed robot strapped to their right hand.

During this time, the resulting brain activity was measured using functional MRI (fMRI). After 20 minutes of learning an association between the two types of stimuli, the babies then just heard the sound on its own and the resulting brain activity was compared to that seen before the period of learning.

Dr Arichi said not only do the results provide new information about what is happening inside the normal baby brain when it is learning, but also have implications for the injured brain.

If a baby was not capable of processing movement, or movement is not associated with normal activity inside the brain (such might be the case in a baby with cerebral palsy), clinicians could then be able to induce that activity by learning an association with sound, and using the sound simulation to try and amplify and rehabilitate their movement.

"With our findings it raises the possibility of trying to do something to help with that through targeted stimulation and learning associations," Dr Arichi said.

"It is possible to induce activity inside the part of the brain that normally processes movement, for instance, just by using a single sound. This could be used in conjunction with rehabilitation or to try and help guide brain development early in life."

When babies are born, they have a new sensory experience around them that is completely different to what they would have been experiencing inside the womb.

They must then start to quickly understand their environment and the relationships between different things happening, which is even more important in babies that have injuries to their brain.

The researchers sought to understand how babies start to learn these key relationships between different kinds of sensory experiences and how this then contributes to the early stages of overall brain development.

"A baby's brain is constantly learning associations and changing its activity all the time so that it can respond to the new experiences that are around it," Dr Arichi said.

Read more at Science Daily

Helicates meet Rotaxanes to create promise for future disease treatment

 A new approach to treating cancers and other diseases that uses a mechanically interlocked molecule as a 'magic bullet' has been designed by researchers at the University of Birmingham.

Called rotaxanes, the molecules are tiny nanoscale structures that resemble a dumbbell with a ring trapped around the central post. Scientists have been experimenting with rotaxanes based on thin, thread-like central posts for a number of years, but this new design uses instead a much larger cylindrical-shaped supramolecular 'helicate' molecule -- around 2nm long and 1nm wide -- which have remarkable ability to bind Y-shaped junctions or forks in DNA and RNA.

These forks are created when DNA replicates and, in laboratory tests, the Birmingham researchers have shown that, when they bind to the junctions, the cylinder molecules are able to stop cancer cells, bacteria and viruses from reproducing.

To gain control over that binding, the team from the University's Schools of Chemistry and Biosciences, collaborated with researchers in Wuhan, in China, and Marseille, in France, to solve the challenge of identifying a ring structure large enough to fit around this central cylinder molecule. They have now shown that a giant pumpkin-shaped molecule, called a cucurbit, is able to host the cylinder. When the ring is present, the rotaxane molecule is unable to bind.

To prevent the cylinder from slipping out of the pumpkin-shaped ring, the researchers added branches to each end of the cylinder. They demonstrated that the cylinder then becomes mechanically locked inside the ring and that they can use this to control the way the supramolecular cylinder interacts with RNA and DNA.

The results, published in the Journal of the American Chemical Society, show not only how these complex molecules can be produced simply and efficiently, but also how the number of branches can be used to regulate the speed at which the cylinder can escape from the pumpkin-shaped ring -- from quickly to not at all.This allows temporal control of the fork-recognition and thus the biological activity.

Lead researcher, Professor Mike Hannon, explains: "This is a really promising new approach that harnesses robust and proven chemistry in an entirely new way that has potential for targeted treatment of cancers and other diseases.

"Our approach is very different to leading cancer drugs which commonly affect all cells in the body, not just the cancer cells. The rotaxane molecule holds the promise that, by turning it on and off as required, it can specifically target and inhibit cancer cells with a high degree of accuracy."

Read more at Science Daily

Science reveals secrets of a mummy's portrait

 How much information can you get from a speck of purple pigment, no bigger than the diameter of a hair, plucked from an Egyptian portrait that's nearly 2,000 years old? Plenty, according to a new study. Analysis of that speck can teach us about how the pigment was made, what it's made of -- and maybe even a little about the people who made it. The study is published in the International Journal of Ceramic Engineering and Science.

"We're very interested in understanding the meaning and origin of the portraits, and finding ways to connect them and come up with a cultural understanding of why they were even painted in the first place," says materials scientist Darryl Butt, co-author of the study and dean of the College of Mines and Earth Sciences.

Faiyum mummies

The portrait that contained the purple pigment came from an Egyptian mummy, but it doesn't look the same as what you might initially think of as a mummy -- not like the golden sarcophagus of Tutankhamen, nor like the sideways-facing paintings on murals and papyri. Not like Boris Karloff, either.

The portrait, called "Portrait of a Bearded Man," comes from the second century when Egypt was a Roman province, hence the portraits are more lifelike and less hieroglyphic-like than Egyptian art of previous eras. Most of these portraits come from a region called Faiyum, and around 1,100 are known to exist. They're painted on wood and were wrapped into the linens that held the mummified body. The portraits were meant to express the likeness of the person, but also their status -- either actual or aspirational.

That idea of status is actually very important in this case because the man in the portrait we're focusing on is wearing purple marks called clavi on his toga. "Since the purple pigment occurred in the clavi -- the purple mark on the toga that in Ancient Rome indicated senatorial or equestrian rank- it was thought that perhaps we were seeing an augmentation of the sitter's importance in the afterlife," says Glenn Gates of the Walters Art Museum in Baltimore, where the portrait resides.

The color purple, Butt says, is viewed as a symbol of death in some cultures and a symbol of life in others. It was associated with royalty in ancient times, and still is today. Paraphrasing the author Victoria Finlay, Butt says that purple, located at the end of the visible color spectrum, can suggest the end of the known and the beginning of the unknown.

"So the presence of purple on this particular portrait made us wonder what it was made of and what it meant," Butt says. "The color purple stimulates many questions."

Lake pigments

Through a microscope, Gates saw that the pigment looked like crushed gems, containing particles ten to a hundred times larger than typical paint particles. To answer the question of how it was made, Gates sent a particle of the pigment to Butt and his team for analysis. The particle was only 50 microns in diameter, about the same as a human hair, which made keeping track of it challenging.

"The particle was shipped to me from Baltimore, sandwiched between two glass slides," Butt says, "and because it had moved approximately a millimeter during transit, it took us two days to find it." In order to move the particle to a specimen holder, the team used an eyelash with a tiny quantity of adhesive at its tip to make the transfer. "The process of analyzing something like this is a bit like doing surgery on a flea."

With that particle, as small as it was, the researchers could machine even smaller samples using a focused ion beam and analyze those samples for their elemental composition.

What did they find? To put the results in context, you'll need to know how dyes and pigments are made.

Pigments and dyes are not the same things. Dyes are the pure coloring agents, and pigments are the combination of dyes, minerals, binders and other components that make up what we might recognize as paint.

Initially, purple dyes came from a gland of a genus of sea snails called Murex. Butt and his colleagues hypothesize that the purple used in this mummy painting is something else -- a synthetic purple.

The researchers also hypothesize that the synthetic purple could have originally been discovered by accident when red dye and blue indigo dye mixed together. The final color may also be due to the introduction of chromium into the mix.

From there, the mineralogy of the pigment sample suggests that the dye was mixed with clay or a silica material to form a pigment. According to Butt, an accomplished painter himself, pigments made in this way are called lake pigments (derived from the same root word as lacquer). Further, the pigment was mixed with a beeswax binder before finally being painted on linden wood.

The pigment showed evidence suggesting a crystal structure in the pigment. "Lake pigments were thought to be without crystallinity prior to this work," Gates says. "We now know crystalline domains exist in lake pigments, and these can function to 'trap' evidence of the environment during pigment creation."

Bottom of the barrel, er, vat

One other detail added a bit more depth to the story of how this portrait was made. The researchers found significant amounts of lead in the pigment as well and connected that finding with observations from a late 1800s British explorer who reported that the vats of dye in Egyptian dyers' workshops were made of lead.

"Over time, a story or hypothesis emerged," Butt says, "suggesting that the Egyptian dyers produced red dye in these lead vats." And when they were done dyeing at the end of the day, he says, there may have been a sludge that developed inside the vat that was a purplish color. "Or, they were very smart and they may have found a way to take their red dye, shift the color toward purple by adding a salt with transition metals and a mordant [a substance that fixes a dye] to intentionally synthesize a purple pigment. We don't know."

Broader impacts

This isn't Butt's first time using scientific methods to learn about ancient artwork. He's been involved with previous similar investigations and has drawn on both his research and artistic backgrounds to develop a class called "The Science of Art" that included studies and discussions on topics that involved dating, understanding and reverse engineering a variety of historical artifacts ranging from pioneer newspapers to ancient art.

"Mixing science and art together is just fun," he says. "It's a great way to make learning science more accessible."

And the work has broader impacts as well. Relatively little is known about the mummy portraits, including whether the same artist painted multiple portraits. Analyzing pigments on an atomic level might provide the chemical fingerprint needed to link portraits to each other.

Read more at Science Daily

Zebra finches amazing at unmasking the bird behind the song

 

Zebra finches

If songbirds could appear on "The Masked Singer" reality TV competition, zebra finches would likely steal the show. That's because they can rapidly memorize the signature sounds of at least 50 different members of their flock, according to new research from the University of California, Berkeley.

In findings recently published in the journal Science Advances, these boisterous, red-beaked songbirds, known as zebra finches, have been shown to pick one another out of a crowd (or flock) based on a particular peer's distinct song or contact call.

Like humans who can instantly tell which friend or relative is calling by the timbre of the person's voice, zebra finches have a near-human capacity for language mapping. Moreover, they can remember each other's unique vocalizations for months and perhaps longer, the findings suggest.

"The amazing auditory memory of zebra finches shows that birds' brains are highly adapted for sophisticated social communication," said study lead author Frederic Theunissen, a UC Berkeley professor of psychology, integrative biology and neuroscience.

Theunissen and fellow researchers sought to gauge the scope and magnitude of zebra finches' ability to identify their feathered peers based purely on their unique sounds. As a result, they found that the birds, which mate for life, performed even better than anticipated.

"For animals, the ability to recognize the source and meaning of a cohort member's call requires complex mapping skills, and this is something zebra finches have clearly mastered," Theunissen said.

A pioneer in the study of bird and human auditory communication for at least two decades, Theunissen acquired a fascination and admiration for the communication skills of zebra finches through his collaboration with UC Berkeley postdoctoral fellow Julie Elie, a neuroethologist who has studied zebra finches in the forests of their native Australia. Their teamwork yielded groundbreaking findings about the communication skills of zebra finches.

Zebra finches usually travel around in colonies of 50 to 100 birds, flying apart and then coming back together. Their songs are typically mating calls, while their distance or contact calls are used to identify where they are, or to locate one another.

"They have what we call a 'fusion fission' society, where they split up and then come back together," Theunissen said. "They don't want to separate from the flock, and so, if one of them gets lost, they might call out 'Hey, Ted, we're right here.' Or, if one of them is sitting in a nest while the other is foraging, one might call out to ask if it's safe to return to the nest."

These days, Theunissen keeps a few dozen zebra finches in aviaries on and around campus, 20 of which were used in this latest experiment.

In a two-part experiment, 20 captive zebra finches were trained to distinguish between different birds and their vocalizations. At first, half the birds were tested on memorizing songs, while the other half were assessed on distance or contact calls. They then switched those tasks.

Next, the zebra finches were placed, one at a time, inside a chamber and listened to sounds as part of a reward system. The goal was to train them to respond to particular zebra finches by hearing several different renditions of those birds' distinct vocalizations and memorizing them.

By pecking a key inside the chamber, the bird subjects triggered an audio recording of a zebra finch vocalization. If they waited until the six-second recording ended, and it was part of the reward group, they received birdseed. If they pecked before the recording was finished, they moved to the next recording. Over several trials, they learned which vocalizations would yield birdseed, and which ones to skip.

Next, the zebra finches were introduced to more audio recordings from new zebra finches, to teach them to distinguish which vocalizations belonged to which bird. They soon learned to differentiate between 16 different zebra finches.

In fact, the zebra finches, both male and female, performed so well in the tests that four of them were given the more challenging task of distinguishing between 56 different zebra finches. On average, they succeeded in recognizing 42 different zebra finches, based on their signature sounds. Plus, they were still able to identify the birds based on their unique sounds a month later.

Read more at Science Daily