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By Alice Klein How can you stop old anxieties from resurfacing? An injection of new neurons may help, a study in mice suggests. Post-traumatic stress disorder (PTSD), anxiety and other fear-related disorders are difficult to treat, and many people who seem to get better later relapse. A similar phenomenon occurs in rodents. Adult mice can be conditioned to fear a sound by giving them an electric shock every time they hear it. Playing the sound repeatedly without the shock gradually wipes out the fear – a process known as extinction training. However, the fear often returns spontaneously if the mouse hears the sound later on. Baby mice, on the other hand, do not seem to relapse as much. Yong-Chun Yu at Fudan University in China and his colleagues wanted to know if they could treat fearful adult mice with brain cells from mouse embryos. The transplants did not prevent the mice developing new fears, nor help them overcome existing ones – at least not by themselves. But coupled with extinction training, the embryonic cells did help wipe out existing fears and prevent the mice relapsing. First, the researchers injected live brain cells from mouse embryos into the amygdalae of adult mice – the parts of the brain involved in fear. Other mice were implanted with dead embryonic brain cells as a comparison. © Copyright Reed Business Information Ltd.
Men and women who suffered traumatic brain injuries had more than twice the risk of winding up in a federal prison in Canada as their uninjured peers, a new study shows. That doesn't surprise Dr. Geoffrey Manley, a neurosurgeon who runs a trauma centre. He knows all too well the long-term struggles of survivors of traumatic brain injuries. "Because there's no system of care for these individuals, they fall into the cracks and get themselves in trouble. And we really as a society are not doing a good job of taking care of people with traumatic brain injuries," Manley, who was not involved in the study, said in a phone interview. For 13 years, researchers followed more than 1.4 million people who were eligible for health care in Ontario and were between the ages of 18 and 28 in 1997. As reported in CMAJ Open, the open-access journal of the Canadian Medical Association, the research team linked subjects' health records to correctional records, adjusted for a variety of factors like age and substance abuse, and found that men with traumatic brain injuries were 2.5 times more likely to serve time in a Canadian federal prison than men without head injuries. Female prisoners were even more likely to have survived traumatic brain injuries. For women with these injuries, the risk of winding up in a Canadian federal prison was 2.76 times higher than it was for uninjured women, although the authors caution that the pool of incarcerated females was small, accounting for only 210 of the more than 700,000 women studied. ©2016 CBC/Radio-Canada.
By Jason G. Goldman In her widely celebrated 1978 book Illness as Metaphor Susan Sontag wrote that when medical experts attribute psychological causality to biological disease, they “assign to the luckless ill the ultimate responsibility both for falling ill and for getting well.” The latest salvo in the ongoing debate over the extent to which psychological factors can explain physiological outcomes comes from a study published today, which finds optimistic women are less likely to die of a variety of illnesses—from cancer to heart failure to infectious disease. Researchers from Harvard University's T. H. Chan School of Public Health turned to a 40-year survey-based study begun in 1976 of American female nurses, most of whom were white, called the “Nurses’ Health Study.” They extracted data on the women's personalities from the 2004 and 2008 surveys and compared it with mortality rates for the same women between 2006 and 2012. Altogether, they collected information from more than 70,000 individuals. To assess optimism, the study asked participants to rate on a five-point scale the extent to which they agreed with six statements such as, “in uncertain times, I usually expect the best.” “When comparing the top 25 percent most optimistic [women] to the bottom 25 percent, they had about a 30 percent reduced risk of mortality,” says study leader Eric Kim of Harvard. Those relationships remained, albeit less robustly, even after the researchers adjusted the predictions to account for sociodemographic factors and health-related behaviors. Kim is quick to point out that this does not necessarily mean optimism leads to healthier lifestyles, only that there is a statistical association. Still, he and his colleagues argue that because personality traits are somewhat malleable, optimism-based interventions could be a fairly simple, low-cost way to improve public health. © 2016 Scientific American
Between email and cell phones, many of us feel like we're at work 24/7. The concept of workplace burnout is not that old. NPR's Planet Money team has the story of the man who coined the term. ARI SHAPIRO, HOST: If you're the type of person who checks your work email right before bed and just as you wake up the next day, you might know the word burnout, but you may not know the story behind it. Noel King from NPR's Planet Money podcast tells us about the man who coined the term burnout and then found a sort of solution. NOEL KING, BYLINE: In the early '70s, Herbert Freudenberger had a successful psychology practice on New York's Upper East Side. He was a serious, driven man. He'd survived the Holocaust and moved to the U.S. as a kid. Here's his daughter Lisa Freudenberger. Her dad died in 1999. LISA FREUDENBERGER: His childhood kind of stopped at 7 or 8 because he had then had to grow up pretty quickly and survive in a new country. KING: In the States, he was taken in by an aunt who was cruel to him. She made him sleep in an attic. In his teens, he ran away and lived on the street for a while. Herbert grew up to become someone who was always pushing himself to help more people. That's why in addition to his practice on the Upper East Side, he opened a clinic on the Bowery - New York's Skid Row. He worked with drug addicts. © 2016 npr
Link ID: 22968 - Posted: 12.09.2016
By Meredith Wadman There have been few happy endings when it comes to spinal muscular atrophy (SMA), the most common genetic cause of death in childhood. The disease inexorably destroys the motor neurons of the spinal cord and brainstem that control movement, including swallowing and breathing. In its most severe form, SMA kills those afflicted at about age 2, most commonly by suffocating them. There are no Food and Drug Administration (FDA)–approved drugs for the disease. That is almost certainly about to change. An innovative drug that helps cells bypass the genetic flaw responsible for SMA may be approved as soon as this month, on the heels of strongly positive results from late-stage clinical trials. On 7 November, a trial of the drug, nusinersen, in wheelchair-bound children aged 2 to 12, was stopped on the grounds that it was unethical to deny the drug to children in the control arm, given the positive results in the treated children. In August, a similar trial in infants was stopped for the same reason, allowing the untreated infants in a control arm to begin receiving the drug. And today, a paper appearing in The Lancet provides compelling biological evidence that nusinersen is having its desired effect in the cells of the brain and spinal cord. “These [infant-onset] SMA kids are going to die. And not only are they now not dying, you are essentially on the path to a true cure of a degenerative [neurological] disease, which is unheard of,” says Jeffrey Rothstein, a neurologist at the Johns Hopkins School of Medicine in Baltimore, Maryland, who was not affiliated with the trials of the drug and is not connected with either of the two companies involved in its development: Ionis of Carlsbad, California, and Biogen of Cambridge, Massachusetts. © 2016 American Association for the Advancement of Science
Laura Sanders Flickering light kicks off brain waves that clean a protein related to Alzheimer’s disease out of mice’s brains, a new study shows. The results, described online December 7 in Nature, suggest a fundamentally new approach to counteracting Alzheimer’s. Many potential therapies involve drugs that target amyloid-beta, the sticky protein that accumulates in the brains of Alzheimer’s patients. In contrast, the new method used on mice causes certain nerve cells to fire at a specific rhythm, generating brain waves that researchers believe may clear A-beta. “This is a very creative and innovative new approach to targeting brain amyloid load in Alzheimer’s,” says geriatric psychiatrist Paul Rosenberg of Johns Hopkins Medicine. But he cautions that the mouse results are preliminary. Neuroscientist Li-Huei Tsai of MIT and colleagues saw that mice engineered to produce lots of A-beta don’t produce as many gamma waves in the hippocampus, a brain structure important for memory. Using a method called optogenetics, the researchers genetically designed certain nerve cells in the hippocampus to fire off signals in response to light. In this way, the researchers induced gamma waves — rhythmic firings 40 times per second. After just an hour of forced gamma waves, the mice had less A-beta in the hippocampus, the researchers found. Further experiments revealed that gamma waves packed a double whammy — they lowered A-beta by both reducing production and enhancing the brain’s ability to clear it. © Society for Science & the Public 2000 - 2016
Link ID: 22966 - Posted: 12.08.2016
By Helen Briggs BBC News Humans may in part owe their big brains to a DNA "typo" in their genetic code, research suggests. The mutation was also present in our evolutionary "cousins" - the Neanderthals and Denisovans. However, it is not found in humans' closest living relatives, the chimpanzees. As early humans evolved, they developed larger and more complex brains, which can process and store a lot of information. Last year, scientists pinpointed a human gene that they think was behind the expansion of a key brain region known as the neocortex. They believe the gene arose about five or six million years ago, after the human line had split off from chimpanzees. Now, researchers have found a tiny DNA change - a point mutation - that appears to have changed the function of the gene, sparking the process of expansion of the neocortex. It may have paved the way for the brain's expansion by dramatically boosting the number of brain cells found in this region. Dr Wieland Huttner of the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany, led the research. "A point mutation in a human-specific gene gave it a function that allows expansion of the relevant stem cells that make a brain big," he told BBC News. "This one, as it is fixed in the human genome - so all living humans have the gene - apparently gave a tremendous selection advantage, and that's why we believe it spread in the human population." Between two and six million years ago, the ancestors of modern humans began to walk upright and use simple tools.
Children don’t usually have the words to communicate even the darkest of thoughts. As a result, some children aged 5 to 11 take their own lives. It’s a rare and often overlooked phenomenon—and one that scientists are only just beginning to understand. A study published today in the journal Pediatrics reveals that attention deficit disorder (A.D.D.), not depression, may be the most common mental health diagnosis among children who die by suicide. By contrast, the researchers found that two-thirds of the 606 early adolescents studied (aged 12 to 14) had suffered from depression. While the finding isn’t necessarily causal, it does suggest that impulsive behavior might contribute to incidences of child suicide. Alternatively, some of these cases could be attributed to early-onset bipolar disorder, misdiagnosed as A.D.D. or A.D.H.D. Here’s Catherine Saint Louis, reporting for The New York Times: Suicide prevention has focused on identifying children struggling with depression; the new study provides an early hint that this strategy may not help the youngest suicide victims. “Maybe in young children, we need to look at behavioral markers,” said Jeffrey Bridge, the paper’s senior author and an epidemiologist at the Research Institute at Nationwide Children’s Hospital in Columbus, Ohio. Jill Harkavy-Friedman, the vice president of research at the American Foundation for Suicide Prevention, agreed. “Not everybody who is at risk for suicide has depression,” even among adults, said Dr. Harkavy-Friedman, who was not involved in the new research. © 1996-2016 WGBH Educational Foundation
By MATT RICHTEL Soaring use of e-cigarettes among young people “is now a major public health concern,” according to a report being published Thursday from the United States Surgeon General. It is the first comprehensive look on the subject from the nation’s highest public-health authority, and it finds that e-cigarettes are now the most commonly used tobacco product among youths, surpassing tobacco cigarettes. E-cigarettes, which turn nicotine into inhalable vapor, can harm developing brains of teenagers who use them, and also can create harmful aerosol for people around the user, the equivalent of secondhand smoke, the report said, citing studies in animals. “Adolescent brains are particularly sensitive to nicotine’s effects,” and can experience “a constellation of nicotine-induced neural and behavioral alterations,” the report said. It urged stronger action to prevent young people from getting access to e-cigarettes. Some researchers have said that e-cigarette use among youth could act as a gateway to traditional smoking, but the report says the relationship is not yet fully established. Cigarette smoking among youth has fallen sharply in recent years but use of nicotine products over all remains essentially flat among young people. With its focus on youth, the report did not address adult use of e-cigarettes, and the most divisive issue of whether the technology is an effective tool to help smokers of traditional cigarettes quit their deadly habit. The report also did not break new scientific ground, but public health advocates said the voice of the surgeon general in the debate marked a milestone. “It’s the most comprehensive and objective answer to the question of whether e-cigarette use is a matter of serious concern that requires government action,” said Matthew Myers, President of the Campaign for Tobacco Free Kids. “The answer, based on the findings, is: yes.” © 2016 The New York Times Company
Betsy Mason With virtual reality finally hitting the consumer market this year, VR headsets are bound to make their way onto a lot of holiday shopping lists. But new research suggests these gifts could also give some of their recipients motion sickness — especially if they’re women. In a test of people playing one virtual reality game using an Oculus Rift headset, more than half felt sick within 15 minutes, a team of scientists at the University of Minnesota in Minneapolis reports online December 3 in Experimental Brain Research. Among women, nearly four out of five felt sick. So-called VR sickness, also known as simulator sickness or cybersickness, has been recognized since the 1980s, when the U.S. military noticed that flight simulators were nauseating its pilots. In recent years, anecdotal reports began trickling in about the new generation of head-mounted virtual reality displays making people sick. Now, with VR making its way into people’s homes, there’s a steady stream of claims of VR sickness. “It's a high rate of people that you put in [VR headsets] that are going to experience some level of symptoms,” says Eric Muth, an experimental psychologist at Clemson University in South Carolina with expertise in motion sickness. “It’s going to mute the ‘Wheee!’ factor.” Oculus, which Facebook bought for $2 billion in 2014, released its Rift headset in March. The company declined to comment on the new research but says it has made progress in making the virtual reality experience comfortable for most people, and that developers are getting better at creating VR content. All approved games and apps get a comfort rating based on things like the type of movements involved, and Oculus recommends starting slow and taking breaks. But still some users report getting sick. © Society for Science & the Public 2000 - 2016.
Link ID: 22962 - Posted: 12.07.2016
By Karinna Hurley Autonomy, peer relationships, and parental conflict — these are the universal themes that made the popular 1990s comic Zits identifiable for anyone who has, or has been, a teenager. In one strip, hands in pockets and making a sullen sideways glance, Jeremy slouches next to his father. His t-shirt reads, “question authority.” Next to him, his equally chagrined father sports the t-shirt: “do not question my authority.” While his parents work to steer the 16-year-old in the right direction on his path to adulthood, Jeremy is equally determined to forge his own way. For the most part, their suggestions, pleas, and cajoles, don’t make it past his headphones. Figuring out how to effectively appeal to adolescents was the first challenge facing researchers in a fascinating new study published in the Proceedings of the National Academy of Sciences. Their goal was to induce teens to change one critically important behavior — food choice — in a completely novel way. The researchers set-up a scenario where healthy eating itself became an avenue for fighting authority. While such a unique value-based intervention also has the potential to be applicable to other groups and values, it’s hard to find a better place to start in today’s society than healthy eating. One of the major initiatives developed and championed by outgoing First Lady Michelle Obama was aimed at reducing childhood obesity. Because, despite the consequences — heart disease, stroke, diabetes — about one in three American adults and nearly one in five children are obese. Carrying extra weight is harmful to individuals and also costly to society. But changing eating habits, one factor in being overweight, is just plain hard. It is not enough to know the consequences of eating junk food: In movie theaters, on best-seller lists and billboards, the warnings are all around us. Yet, even widespread public health messages and access to kitchen gardens, like on the South Lawn of the White House, have not yet curbed rising obesity levels. © 2016 Scientific American
Link ID: 22961 - Posted: 12.07.2016
Sometimes the biggest gifts arrive in the most surprising ways. A couple in Singapore, Tianqiao Chen and Chrissy Luo, were watching the news and saw a Caltech scientist help a quadriplegic use his thoughts to control a robotic arm so that — for the first time in more than 10 years — he could sip a drink unaided. Inspired, Chen and Luo flew to Pasadena to meet the scientist, Richard Andersen, in person. Now they’ve given Caltech $115 million to shake up the way scientists study the brain in a new research complex. Construction of the Tianqiao and Chrissy Chen Institute for Neuroscience at Caltech will begin as early as 2018 and bring together biology, engineering, chemistry, physics, computer science and the social sciences to tackle brain function in an integrated, comprehensive way, university officials announced Tuesday. The goal of connecting these traditionally separate departments is to make “transformational advances” that will lead to new scientific tools and medical treatments, the university said. Research in shared labs will include looking more deeply into fundamentals of the brain and exploring the complexities of sensation, perception, cognition and human behavior. Neuroscience research has advanced greatly in recent years, Caltech President Thomas Rosenbaum said. The field now has the tools to look at individual neurons, for example, as well as the computer power to analyze massive data sets and an entire system of neurons. Collaborating across traditional academic boundaries takes it to the next level, he said. “The tools are at a time and place where we think that the field is ready for that sort of combination.”
Link ID: 22960 - Posted: 12.07.2016
Scientists have developed a mind-controlled robotic hand that allows people with certain types of spinal injuries to perform everyday tasks such as using a fork or drinking from a cup. The low-cost device was tested in Spain on six people with quadriplegia affecting their ability to grasp or manipulate objects. By wearing a cap that measures electric brain activity and eye movement the users were able to send signals to a tablet computer that controlled the glove-like device attached to their hand. Participants in the small-scale study were able to perform daily activities better with the robotic hand than without, according to results published Tuesday in the journal Science Robotics. The principle of using brain-controlled robotic aids to assist people with quadriplegia isn't new. But many existing systems require implants, which can cause health problems, or use wet gel to transmit signals from the scalp to the electrodes. The gel needs to be washed out of the user's hair afterward, making it impractical in daily life. "The participants, who had previously expressed difficulty in performing everyday tasks without assistance, rated the system as reliable and practical, and did not indicate any discomfort during or after use," the researchers said. It took participants just 10 minutes to learn how to use the system before they were able to carry out tasks such as picking up potato chips or signing a document. ©2016 CBC/Radio-Canada.
Link ID: 22959 - Posted: 12.07.2016
By MARC SANTORA At least four babies have been born in New York City with Zika-related brain developmental symptoms since July, the city’s health department said on Wednesday, bringing the total number of such births to five. The numbers were announced in an alert the Department of Health and Mental Hygiene sent to doctors, urging them to remain vigilant and to continue to warn pregnant women and sexually active women of reproductive age not using a reliable form of birth control against traveling to places where the virus is spreading. It was a reminder that while the threat of the virus may have eased in many places around the world, it still poses a danger and its consequences are likely to be felt for some time. Zika is primarily transmitted by mosquitoes but can also be passed on through sex. In most cases, the virus causes only mild illness, but the danger to women pregnant or trying to become pregnant is much greater, because of the impact the disease can have on fetal development. A small percentage of women with the virus have given birth to infants with a abnormally small heads and stunted brain growth — a condition known as microcephaly. As of Friday, about 8,000 New Yorkers have been tested for Zika and 962 have tested positive, including 325 pregnant women, according to the health department. All the cases were associated with travel; six involved sexual transmission by a partner who had been to the areas hit hardest by the Zika epidemic. © 2016 The New York Times Company
Keyword: Development of the Brain
Link ID: 22958 - Posted: 12.07.2016
A graduate student has been charged with murder in the fatal stabbing of beloved USC neuroscience professor, Bosco Tjan on campus Friday. David Jonathan Brown, 28, of Los Angeles is expected to be arraigned Tuesday in downtown Los Angeles, according to the L.A. County district attorney’s office. If he is convicted, Brown faces up to 26 years to life in prison. Prosecutors allege that Brown used a knife when he attacked and stabbed Tjan in the chest at 4:30 p.m. Friday in his office in the Seeley G. Mudd Building on campus. Brown was immediately taken into custody. It was the last day of classes. Tjan, who joined the faculty in 2001, was a professor of psychology at the USC Dornsife College of Letters, Arts and Sciences and a vision loss expert. As co-director of the Dornsife Cognitive Neuroimaging Center, Tjan ran a laboratory devoted to studying human sight. Brown was a doctoral student in Tjan’s lab, according to a USC website. The district attorney’s announcement comes a day after hundreds of students, staff and faculty gathered to honor the slain professor. “Bosco died doing what he loved, doing what he believed in — serving his students and building up a new generation of scholars,” USC President C.L. Max Nikias said. “His achievements are real, his influence enduring.” Tjan led a number of research projects and conducted a lab course on functional imaging. He was also a member of the Society for Neuroscience and Vision Sciences Society.
Link ID: 22957 - Posted: 12.07.2016
By Michael Price The titular detective of the BBC television series Sherlock possesses a “mind palace”—a highly organized mental catalog of nearly every memory he’s ever had. We mere mortals can’t match Holmes’s remarkable recollection, but when we store and recall memories, our brain activity probably looks a lot like his, according to a new study. The findings might help us find early warning signs of memory loss in diseases like Alzheimer’s. Previous research has found that when people perceive an event for the first time and when they are asked to remember it later, the same brain regions are activated. But whether different people encode the same memory in the same way has been a topic of debate. So scientists turned to Sherlock Holmes for answers. A group led by Janice Chen, a postdoc in the psychology department at Princeton University, and Yuan Chang Leong, a graduate student studying psychology at Stanford University in Palo Alto, California, strapped 22 study participants into a functional magnetic resonance imaging (fMRI) machine, which traces blood flow in the brain to measure brain activity. The scientists then showed them a 48-minute segment of BBC’s Sherlock. (Roughly the first half of the series’s first episode, “A Study in Pink,” for the curious superfans.) Immediately afterward, Chen asked the volunteers to tell her as much about the episode as they could. © 2016 American Association for the Advancement of Science.
Keyword: Learning & Memory
Link ID: 22956 - Posted: 12.06.2016
By CHRISTOPHER MELE Have you called your daughter by your wife’s name or your son by his brother’s name? Have you misplaced your car keys or forgotten where you parked at the mall? If you worry these might be signs of significant memory loss or the early stages of Alzheimer’s disease, which causes a slow deterioration in memory and reasoning skills, fear not, experts said. By the age of 45, the average person experiences a decline in memory, Dr. Gary W. Small, a professor of psychiatry and biobehavioral sciences at the David Geffen School of Medicine at the University of California, Los Angeles, said in an email. Forgetting facts or events over time, absent-mindedness and incorrectly recalling a detail are among six “normal” memory problems that should not cause concern, according to the Center for Brain-Mind Medicine at Brigham and Women’s Hospital in Boston. When people do experience normal memory decline related to aging, 85 percent of their complaints involve recalling people’s names, Dr. Small said. You can blame multitasking for overloading your mind. Think about the ways we are driven to distraction with smartphones and social media, for instance. “Whenever our brains are taxed by multiple demands, cognitive ‘slips’ or errors are more likely to occur due to a concept called memory ‘interference,’ ” Carrington Wendell, a neuropsychology specialist at the Anne Arundel Medical Group in Annapolis, Md., said in an email. Name mix-ups are also more likely to occur when the two names share the same beginning, middle or ending, such as Bob and Ben or Dave and Jake, and are the same sex and similar age, she added. © 2016 The New York Times Company
People who consistently smoked an average of less than one cigarette per day over their lifetime had a 64 percent higher risk of earlier death than never smokers, and those who smoked between one and 10 cigarettes a day had an 87 percent higher risk of earlier death than never smokers, according to a new study from researchers at the National Cancer Institute (NCI). Risks were lower among former low-intensity smokers compared to those who were still smokers, and risk fell with earlier age at quitting. The results of the study were reported Dec. 5, 2016, in JAMA Internal Medicine. NCI is part of the National Institutes of Health. When researchers looked at specific causes of death among study participants, a particularly strong association was observed for lung cancer mortality. Those who consistently averaged less than one cigarette per day over their lifetime had nine times the risk of dying from lung cancer than never smokers. Among people who smoked between one and 10 cigarettes per day, the risk of dying from lung cancer was nearly 12 times higher than that of never smokers. The researchers looked at risk of death from respiratory disease, such as emphysema, as well as the risk of death from cardiovascular disease. People who smoked between one and 10 cigarettes a day had over six times the risk of dying from respiratory diseases than never smokers and about one and half times the risk of dying of cardiovascular disease than never smokers. Smoking has many harmful effects on health, which have been detailed in numerous studies since the U.S. Surgeon General’s 1964 report linking smoking to lung cancer. The health effects of consistent low-intensity smoking, however, have not been well studied and many smokers believe that low-intensity smoking does not affect their health.
Keyword: Drug Abuse
Link ID: 22954 - Posted: 12.06.2016
By CATHERINE SAINT LOUIS These days, even 3-year-olds wear headphones, and as the holidays approach, retailers are well stocked with brands that claim to be “safe for young ears” or to deliver “100 percent safe listening.” The devices limit the volume at which sound can be played; parents rely on them to prevent children from blasting, say, Rihanna at hazardous levels that could lead to hearing loss. But a new analysis by The Wirecutter, a product recommendations website owned by The New York Times, has found that half of 30 sets of children’s headphones tested did not restrict volume to the promised limit. The worst headphones produced sound so loud that it could be hazardous to ears in minutes. “These are terribly important findings,” said Cory Portnuff, a pediatric audiologist at the University of Colorado Hospital, who was not involved in the analysis. “Manufacturers are making claims that aren’t accurate.” The new analysis should be a wake-up call to parents who thought volume-limiting technology offered adequate protection, said Dr. Blake Papsin, the chief otolaryngologist at the Hospital for Sick Children in Toronto. “Headphone manufacturers aren’t interested in the health of your child’s ears,” he said. “They are interested in selling products, and some of them are not good for you.” Half of 8- to 12-year-olds listen to music daily, and nearly two-thirds of teenagers do, according to a 2015 report with more than 2,600 participants. Safe listening is a function of both volume and duration: The louder a sound, the less time you should listen to it. It’s not a linear relationship. Eighty decibels is twice as loud as 70 decibels, and 90 decibels is four times louder. Exposure to 100 decibels, about the volume of noise caused by a power lawn mower, is safe for just 15 minutes; noise at 108 decibels, however, is safe for less than three minutes. © 2016 The New York Times Company
Link ID: 22953 - Posted: 12.06.2016
Emily Conover A bird in laser goggles has helped scientists discover a new phenomenon in the physics of flight. Swirling vortices appear in the flow of air that follows a bird’s wingbeat. But for slowly flying birds, these vortices were unexpectedly short-lived, researchers from Stanford University report December 6 in Bioinspiration and Biomimetics. The results could help scientists better understand how animals fly, and could be important for designing flying robots (SN: 2/7/15, p. 18). To study the complex air currents produced by birds’ flapping wings, the researchers trained a Pacific parrotlet, a small species of parrot, to fly through laser light — with the appropriate eye protection, of course. Study coauthor Eric Gutierrez, who recently graduated from Stanford, built tiny, 3-D‒printed laser goggles for the bird, named Obi. Gutierrez and colleagues tracked the air currents left in Obi’s wake by spraying a fine liquid mist in the air, and illuminating it with a laser spread out into a two-dimensional sheet. High-speed cameras recorded the action at 1,000 frames per second. The vortex produced by the bird “explosively breaks up,” says mechanical engineer David Lentink, a coauthor of the study. “The flow becomes very complex, much more turbulent.” Comparing three standard methods for calculating the lift produced by flapping wings showed that predictions didn’t match reality, thanks to the unexpected vortex breakup. |© Society for Science & the Public 2000 - 20
Link ID: 22952 - Posted: 12.06.2016