The wave beneath their wings

It's a common sight: pelicans gliding along the waves, right by the shore. These birds make this kind of surfing look effortless, but actually the physics involved that give them a big boost are not simple.

Researchers at the University of California San Diego have recently developed a theoretical model that describes how the ocean, the wind and the birds in flight interact in a recent paper in Movement Ecology.

UC San Diego mechanical engineering Ph.D. student Ian Stokes and adviser Professor Drew Lucas, of UC San Diego's Department of Mechanical and Aerospace Engineering and Scripps Institution of Oceanography, found that pelicans can completely offset the energy they expend in flight by exploiting wind updrafts generated by waves through what is known as wave-slope soaring. In short, by practicing this behavior, sea-birds take advantage of winds generated by breaking waves to stay aloft.

The model could be used to develop better algorithms to control drones that need to fly over water for long periods of time, the researchers said. Potential uses do not stop there.

"There's a community of biologists and ornithologists that studies the metabolic cost of flight in birds that can use this and see how their research connects to our estimates from theory. Likewise, our model generates a basic prediction for the winds generated by passing swell, which is important to physicists that study how the ocean and atmosphere interact in order to improve weather forecasting," Stokes said.

"This is an interesting project because it shows how the waves are actually moving the air around, making wind. If you're a savvy bird, you can optimize how you move to track waves and to take advantage of these updrafts. Since seabirds travel long distances to find food, the benefits may be significant," Lucas said.

Stokes and Lucas are, of course, not the first scientists to study the physics of the atmosphere that pelicans and other birds are hardwired to intuit so they can conserve energy for other activities. For centuries, humans have been inspired by the sight of birds harnessing the power and patterns of the winds for soaring flight.

That's how it started with Stokes, who is now in the second year of his PhD at UC San Diego. As a UC Santa Barbara undergraduate, Stokes, a surfer and windsurfer in his off hours, needed a project for his senior physics class and thought of the birds that would accompany him on the waves. When he looked closer, he appreciated the connection between their flight dynamics and the study of environmental fluid dynamics, a speciality of scientists at UC San Diego. The project ultimately turned into a master's thesis with Lucas, drawing inspiration from oceanographers at Scripps who seek to understand the interactions between the ocean and atmosphere.

Wave-slope soaring is just one of the many behaviors in sea-birds that take advantage of the energy in their environment. By tapping into these predictable patterns, the birds are able to forage, travel, and find mates more effectively.

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Genetic effects of Chernobyl radiation

In two landmark studies, researchers have used cutting-edge genomic tools to investigate the potential health effects of exposure to ionizing radiation, a known carcinogen, from the 1986 accident at the Chernobyl nuclear power plant in northern Ukraine. One study found no evidence that radiation exposure to parents resulted in new genetic changes being passed from parent to child. The second study documented the genetic changes in the tumors of people who developed thyroid cancer after being exposed as children or fetuses to the radiation released by the accident.

The findings, published around the 35th anniversary of the disaster, are from international teams of investigators led by researchers at the National Cancer Institute (NCI), part of the National Institutes of Health. The studies were published online in Science on April 22.

"Scientific questions about the effects of radiation on human health have been investigated since the atomic bombings of Hiroshima and Nagasaki and have been raised again by Chernobyl and by the nuclear accident that followed the tsunami in Fukushima, Japan," said Stephen J. Chanock, M.D., director of NCI's Division of Cancer Epidemiology and Genetics (DCEG). "In recent years, advances in DNA sequencing technology have enabled us to begin to address some of the important questions, in part through comprehensive genomic analyses carried out in well-designed epidemiological studies."

The Chernobyl accident exposed millions of people in the surrounding region to radioactive contaminants. Studies have provided much of today's knowledge about cancers caused by radiation exposures from nuclear power plant accidents. The new research builds on this foundation using next-generation DNA sequencing and other genomic characterization tools to analyze biospecimens from people in Ukraine who were affected by the disaster.

The first study investigated the long-standing question of whether radiation exposure results in genetic changes that can be passed from parent to offspring, as has been suggested by some studies in animals. To answer this question, Dr. Chanock and his colleagues analyzed the complete genomes of 130 people born between 1987 and 2002 and their 105 mother-father pairs.

One or both of the parents had been workers who helped clean up from the accident or had been evacuated because they lived in close proximity to the accident site. Each parent was evaluated for protracted exposure to ionizing radiation, which may have occurred through the consumption of contaminated milk (that is, milk from cows that grazed on pastures that had been contaminated by radioactive fallout). The mothers and fathers experienced a range of radiation doses.

The researchers analyzed the genomes of adult children for an increase in a particular type of inherited genetic change known as de novo mutations. De novo mutations are genetic changes that arise randomly in a person's gametes (sperm and eggs) and can be transmitted to their offspring but are not observed in the parents.

For the range of radiation exposures experienced by the parents in the study, there was no evidence from the whole-genome sequencing data of an increase in the number or types of de novo mutations in their children born between 46 weeks and 15 years after the accident. The number of de novo mutations observed in these children were highly similar to those of the general population with comparable characteristics. As a result, the findings suggest that the ionizing radiation exposure from the accident had a minimal, if any, impact on the health of the subsequent generation.

"We view these results as very reassuring for people who were living in Fukushima at the time of the accident in 2011," said Dr. Chanock. "The radiation doses in Japan are known to have been lower than those recorded at Chernobyl."

In the second study, researchers used next-generation sequencing to profile the genetic changes in thyroid cancers that developed in 359 people exposed as children or in utero to ionizing radiation from radioactive iodine (I-131) released by the Chernobyl nuclear accident and in 81 unexposed individuals born more than nine months after the accident. Increased risk of thyroid cancer has been one of the most important adverse health effects observed after the accident.

The energy from ionizing radiation breaks the chemical bonds in DNA, resulting in a number of different types of damage. The new study highlights the importance of a particular kind of DNA damage that involves breaks in both DNA strands in the thyroid tumors. The association between DNA double-strand breaks and radiation exposure was stronger for children exposed at younger ages.

Next, the researchers identified the candidate "drivers" of the cancer in each tumor -- the key genes in which alterations enabled the cancers to grow and survive. They identified the drivers in more than 95% of the tumors. Nearly all the alterations involved genes in the same signaling pathway, called the mitogen-activated protein kinase (MAPK) pathway, including the genes BRAF, RAS, and RET.

The set of affected genes is similar to what has been reported in previous studies of thyroid cancer. However, the researchers observed a shift in the distribution of the types of mutations in the genes. Specifically, in the Chernobyl study, thyroid cancers that occurred in people exposed to higher radiation doses as children were more likely to result from gene fusions (when both strands of DNA are broken and then the wrong pieces are joined back together), whereas those in unexposed people or those exposed to low levels of radiation were more likely to result from point mutations (single base-pair changes in a key part of a gene).

The results suggest that DNA double-strand breaks may be an early genetic change following exposure to radiation in the environment that subsequently enables the growth of thyroid cancers. Their findings provide a foundation for further studies of radiation-induced cancers, particularly those that involve differences in risk as a function of both dose and age, the researchers added.

"An exciting aspect of this research was the opportunity to link the genomic characteristics of the tumor with information about the radiation dose -- the risk factor that potentially caused the cancer," said Lindsay M. Morton, Ph.D., deputy chief of the Radiation Epidemiology Branch in DCEG, who led the study.

"The Cancer Genome Atlas set the standard for how to comprehensively profile tumor characteristics," Dr. Morton continued. "We extended that approach to complete the first large genomic landscape study in which the potential carcinogenic exposure was well-characterized, enabling us to investigate the relationship between specific tumor characteristics and radiation dose."

She noted that the study was made possible by the creation of the Chernobyl Tissue Bank about two decades ago -- long before the technology had been developed to conduct the kind of genomic and molecular studies that are common today.

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Mars has right ingredients for present-day microbial life beneath its surface, study finds

As NASA's Perseverance rover begins its search for ancient life on the surface of Mars, a new study suggests that the Martian subsurface might be a good place to look for possible present-day life on the Red Planet.

The study, published in the journal Astrobiology, looked at the chemical composition of Martian meteorites -- rocks blasted off of the surface of Mars that eventually landed on Earth. The analysis determined that those rocks, if in consistent contact with water, would produce the chemical energy needed to support microbial communities similar to those that survive in the unlit depths of the Earth. Because these meteorites may be representative of vast swaths of the Martian crust, the findings suggest that much of the Mars subsurface could be habitable.

"The big implication here for subsurface exploration science is that wherever you have groundwater on Mars, there's a good chance that you have enough chemical energy to support subsurface microbial life," said Jesse Tarnas, a postdoctoral researcher at NASA's Jet Propulsion Laboratory who led the study while completing his Ph.D. at Brown University. "We don't know whether life ever got started beneath the surface of Mars, but if it did, we think there would be ample energy there to sustain it right up to today."

In recent decades, scientists have discovered that Earth's depths are home to a vast biome that exists largely separated from the world above. Lacking sunlight, these creatures survive using the byproducts of chemical reactions produced when rocks come into contact with water.

One of those reactions is radiolysis, which occurs when radioactive elements within rocks react with water trapped in pore and fracture space. The reaction breaks water molecules into their constituent elements, hydrogen and oxygen. The liberated hydrogen is dissolved in the remaining groundwater, while minerals like pyrite (fool's gold) soak up free oxygen to form sulfate minerals. Microbes can ingest the dissolved hydrogen as fuel and use the oxygen preserved in the sulfates to "burn" that fuel.

In places like Canada's Kidd Creek Mine, these "sulfate-reducing" microbes have been found living more than a mile underground, in water that hasn't seen the light of day in more than a billion years. Tarnas has been working with a team co-led by Brown University professor Jack Mustard and Professor Barbara Sherwood Lollar of the University of Toronto to better understand these underground systems, with an eye toward looking for similar habitats on Mars and elsewhere in the solar system. The project, called Earth 4-D: Subsurface Science and Exploration, is supported by the Canadian Institute for Advances Research.

For this new study, the researchers wanted to see if the ingredients for radiolysis-driven habitats could exist on Mars. They drew on data from NASA's Curiosity rover and other orbiting spacecraft, as well as compositional data from a suite of Martian meteorites, which are representative of different parts of the planet's crust.

The researchers were looking for the ingredients for radiolysis: radioactive elements like thorium, uranium and potassium; sulfide minerals that could be converted to sulfate; and rock units with adequate pore space to trap water. The study found that in several different types of Martian meteorites, all the ingredients are present in adequate abundances to support Earth-like habitats. This was particularly true for regolith breccias -- meteorites sourced from crustal rocks more than 3.6 billion years old -- which were found to have the highest potential for life support. Unlike Earth, Mars lacks a plate tectonics system that constantly recycle crustal rocks. So these ancient terrains remain largely undisturbed.

The researchers say the findings help make the case for an exploration program that looks for signs of present-day life in the Martian subsurface. Prior research has found evidence of an active groundwater system on Mars in the past, the researchers say, and there's reason to believe that groundwater exists today. One recent study, for example, raised the possibility of an underground lake lurking under the planet's southern ice cap. This new research suggests that wherever there's groundwater, there's energy for life.

Tarnas and Mustard say that while there are certainly technical challenges involved in subsurface exploration, they aren't as insurmountable as people may think. A drilling operation wouldn't require "a Texas-sized oil rig," Mustard said, and recent advances in small drill probes could soon put the Martian depths within reach.

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More belly weight increases danger of heart disease even if BMI does not indicate obesity

People with abdominal obesity and excess fat around the body's mid-section and organs have an increased risk of heart disease even if their body mass index (BMI) measurement is within a healthy weight range, according to a new Scientific Statement from the American Heart Association published today in the Association's flagship journal, Circulation.

"This scientific statement provides the most recent research and information on the relationship between obesity and obesity treatment in coronary heart disease, heart failure and arrhythmias," said Tiffany M. Powell-Wiley, M.D., M.P.H., FAHA, chair of the writing committee and a Stadtman Tenure-Track Investigator and chief of the Social Determinants of Obesity and Cardiovascular Risk Laboratory in the Division of Intramural Research at the National Heart, Lung, and Blood Institute at the National Institutes of Health in Bethesda, Maryland. "The timing of this information is important because the obesity epidemic contributes significantly to the global burden of cardiovascular disease and numerous chronic health conditions that also impact heart disease."

A greater understanding of obesity and its impact on cardiovascular health highlights abdominal obesity, sometimes referred to as visceral adipose tissue, or VAT, as a cardiovascular disease risk marker. VAT is commonly determined by waist circumference, the ratio of waist circumference to height (taking body size into account) or waist-to-hip ratio, which has been shown to predict cardiovascular death independent of BMI.

Experts recommend both abdominal measurement and BMI be assessed during regular health care visits because a high waist circumference or low waist-to-hip ratio, even in healthy weight individuals, could mean an increased risk of heart disease. Abdominal obesity is also linked to fat accumulation around the liver that often leads to non-alcoholic fatty liver disease, which adds to cardiovascular disease risk.

"Studies that have examined the relationship between abdominal fat and cardiovascular outcomes confirm that visceral fat is a clear health hazard," said Powell-Wiley.

The risk-inducing power of abdominal obesity is so strong that in people who are overweight or have obesity based on BMI, low levels of fat tissue around their midsection and organs could still indicate lower cardiovascular disease risks. This concept, referred to as "metabolically healthy obesity," seems to differ depending on race/ethnicity and sex.

Worldwide, around 3 billion people are overweight (BMI = 25 to 29.9 kg/m2) or have obesity obese(BMI ?30 kg/m2). Obesity is a complex disease related to many factors, including biologic, psychological, environmental and societal aspects, all of which may contribute to a person's risk for obesity. Obesity is associated with greater risk of coronary artery disease and death due to cardiovascular disease and contributes to many cardiovascular risk factors and other health conditions, including dyslipidemia (high cholesterol), type 2 diabetes, high blood pressure and sleep disorders.

For this statement, experts evaluated research on managing and treating obesity, particularly abdominal obesity. The writing group reports that reducing calories can reduce abdominal fat, and the most beneficial physical activity to reduce abdominal obesity is aerobic exercise. Their analysis found that meeting the current recommendations of 150 min/week of physical activity may be sufficient to reduce abdominal fat, with no additional loss from longer activity times. Exercise or a combination of dietary change and physical activity has been shown in some instances to reduce abdominal obesity even without weight loss.

Lifestyle changes and subsequent weight loss improve blood sugar, blood pressure, triglyceride and cholesterol levels -- a cluster of factors referred to as metabolic syndrome -- and reduce inflammation, improve blood vessel function and treat non-alcoholic fatty liver disease. However, studies of lifestyle change programs have not shown a reduction in coronary artery disease events (such as heart attack or chest pain).

In contrast, bariatric surgery for weight loss treatment is associated with a reduction in coronary artery disease risk compared to non-surgical weight loss. This difference may be attributed to the larger amount of weight loss and the resultant changes in metabolism that are typical after bariatric surgery.

"Additional work is needed to identify effective interventions for patients with obesity that improve cardiovascular disease outcomes and reduce cardiovascular disease mortality, as is seen with bariatric surgery," said Powell-Wiley.

The statement also addresses the "obesity paradox," which is sometimes observed in research, particularly in populations that have overweight or have Class I obesity (BMI = 30 to 34.9 kg/m2). The paradox suggests that even though overweight and obesity are strong risk factors for the development of cardiovascular disease, they are not always a risk factor for negative cardiovascular outcomes. The writing group notes that people with overweight or obesity are often screened earlier for cardiovascular disease than people with healthy weight, thus resulting in earlier diagnoses and treatment.

"The underlying mechanisms for the obesity paradox remain unclear," said Powell-Wiley. "Despite the existence of the paradox for short-term cardiovascular disease outcomes, the data show that patients with overweight or obesity suffer from cardiovascular disease events at an earlier age, live with cardiovascular disease for more of their lives and have a shorter average lifespan than patients with normal weight."

In reviewing the effects of obesity on a common heart rhythm disorder, the writing group reports there is now "convincing data" that obesity may cause atrial fibrillation, a quivering or irregular heartbeat. Estimates suggest obesity may account for one-fifth of all atrial fibrillation cases and 60% of recently documented increases in people with atrial fibrillation. Research has demonstrated people with atrial fibrillation who had intense weight loss experienced a significant reduction in cumulative time spent in atrial fibrillation.

"The research provides strong evidence that weight management be included as an essential aspect of managing atrial fibrillation, in addition to the standard treatments to control heart rate, rhythm and clotting risk," said Powell-Wiley.

The statement identifies areas of future research, including a call for further study of lifestyle interventions that may be most effective in decreasing visceral adiposity and improving cardiovascular outcomes. Powell-Wiley said, "It's important to understand how nutrition can be personalized based on genetics or other markers for cardiovascular disease risk.

Read more at Science Daily

Ankle exoskeleton enables faster walking

Being unable to walk quickly can be frustrating and problematic, but it is a common issue, especially as people age. Noting the pervasiveness of slower-than-desired walking, engineers at Stanford University have tested how well a prototype exoskeleton system they have developed -- which attaches around the shin and into a running shoe -- increased the self-selected walking speed of people in an experimental setting.

The exoskeleton is externally powered by motors and controlled by an algorithm. When the researchers optimized it for speed, participants walked, on average, 42 percent faster than when they were wearing normal shoes and no exoskeleton. The results of this study were published April 20 in IEEE Transactions on Neural Systems and Rehabilitation Engineering.

"We were hoping that we could increase walking speed with exoskeleton assistance, but we were really surprised to find such a large improvement," said Steve Collins, associate professor of mechanical engineering at Stanford and senior author of the paper. "Forty percent is huge."

For this initial set of experiments, the participants were young, healthy adults. Given their impressive results, the researchers plan to run future tests with older adults and to look at other ways the exoskeleton design can be improved. They also hope to eventually create an exoskeleton that can work outside the lab, though that goal is still a ways off.

"My research mission is to understand the science of biomechanics and motor control behind human locomotion and apply that to enhance the physical performance of humans in daily life," said Seungmoon Song, a postdoctoral fellow in mechanical engineering and lead author of the paper. "I think exoskeletons are very promising tools that could achieve that enhancement in physical quality of life."

Walking in the loop

The ankle exoskeleton system tested in this research is an experimental emulator that serves as a testbed for trying out different designs. It has a frame that fastens around the upper shin and into an integrated running shoe that the participant wears. It is attached to large motors that sit beside the walking surface and pull a tether that runs up the length of the back of the exoskeleton. Controlled by an algorithm, the tether tugs the wearer's heel upward, helping them point their toe down as they push off the ground.

For this study, the researchers had 10 participants walk with five different modes of operation. They walked in normal shoes without the exoskeleton, with the exoskeleton turned off and with the exoskeleton turned on with three different modes: optimized for speed, optimized for energy use, and a placebo mode adjusted to make them walk more slowly. In all of the tests, participants walked on a treadmill that adapts to their speed.

The mode that was optimized for speed -- which resulted in the 42 percent increase in walking pace -- was created through a human-in-the-loop process. An algorithm repeatedly adjusted the exoskeleton settings while the user walked, with the goal of improving the user's speed with each adjustment. Finding the speed-optimized mode of operation took about 150 rounds of adjustment and two hours per person.

In addition to greatly increasing walking speed, the speed-optimized mode also reduced energy use, by about 2 percent per meter traveled. However, that result varied widely from person to person, which is somewhat expected, given that it was not an intentional feature of that exoskeleton mode.

"The study was designed to specifically answer the scientific question about increasing walking speed," Song said. "We didn't care too much about the other performance measures, like comfort or energy. However, seven out of 10 participants not only walked faster but consumed less energy, which really shows how much potential exoskeletons have for helping people in an efficient way."

The settings that were optimized specifically for energy use were borrowed from a previous experiment. In the current study, this mode decreased energy use more than the speed-optimized settings but did not increase speed as much. As intended, the placebo mode both slowed down participants and boosted their energy use.

Better, faster, stronger

Now that the researchers have attained such significant speed assistance, they plan to focus future versions of the ankle exoskeleton emulator on reducing energy use consistently across users, while also being more comfortable.

In considering older adults specifically, Collins and his lab wonder whether future designs could reduce pain caused by weight on joints or improve balance. They plan to conduct similar walking tests with older adults and hope those provide encouraging results as well.

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Creativity and community: How modern humans overcame the Neanderthals

A new study is the first-ever to identify the genes for creativity in Homo sapiens that distinguish modern humans from chimpanzees and Neanderthals. The research identified 267 genes that are found only in modern humans and likely play an important role in the evolution of the behavioral characteristics that set apart Homo sapiens, including creativity, self-awareness, cooperativeness, and healthy longevity. The study, led by an international and interdisciplinary team of researchers from the American Museum of Natural History and Washington University among other institutions, is published today in the journal Molecular Psychiatry.

"One of the most fundamental questions about human nature is what sparked the explosive emergence of creativity in modern humans in the period just before and after their widespread dispersal from Africa and the related extinction of Neanderthals and other human relatives," said study co-author Ian Tattersall, curator emeritus in the American Museum of Natural History's Division of Anthropology. "Major controversies persist about the basis for human creativity in art and science, as well as about potential differences in cognition, language, and personality that distinguish modern humans from extinct hominids. This new study is the result of a truly pathbreaking use of genomic methodologies to enlighten us about the mechanisms underpinning our uniqueness."

Modern humans demonstrate remarkable creativity compared to their closest living relatives, the great apes (chimpanzees, gorillas, and orangutans and their immediate ancestors), including innovativeness, flexibility, depth of planning, and related cognitive abilities for symbolism and self-awareness that also enable spontaneous generation of narrative art and language. But the genetic basis for the emergence of creativity in modern humans remains a mystery, even after the recovery of full-genome data for both chimpanzees and our extinct close relatives the Neanderthals.

"It has been difficult to identify the genes that led to the emergence of human creativity before now because of the large number of changes in the human genome after it diverged from the common ancestor of humans and chimpanzees around 10 million years ago, as well as uncertainty about the functions of those changes," said Robert Cloninger, a psychiatrist and geneticist at Washington University in St. Louis, and the lead author of the study. "Therefore, we began our research by first identifying the way the genes that influence modern human personality are organized into coordinated systems of learning that have allowed us to adapt flexibly and creatively to changing life conditions."

The team led by Cloninger had previously identified 972 genes that regulate gene expression for human personality, which is comprised of three nearly separate networks for learning and memory. One, for regulating emotional reactivity -- emotional drives, habit learning, social attachment, conflict resolution -- emerged in monkeys and apes about 40 million years ago. The second, which regulates intentional self-control -- self-directedness and cooperation for mutual benefit -- emerged a little less than 2 million years ago. A third one, for creative self-awareness, emerged about 100,000 years ago.

In the latest study, the researchers discovered that 267 genes from this larger group are found only in modern humans and not in chimpanzees or Neanderthals. These uniquely human genes code for the self-awareness brain network and also regulate processes that allow Homo sapiens to be creative in narrative art and science, to be more prosocial, and to live longer lives through greater resistance to aging, injury, and illness than the now-extinct hominids they replaced.

Genes regulating emotional reactivity were nearly the same in humans, Neanderthals, and chimps. And Neanderthals were about midway between chimps and Homo sapiens in their genes for self-control and self-awareness.

"We found that the adaptability and well-being of Neanderthals was about 60 to 70 percent of that of Homo sapiens, which means that the difference in fitness between them was large," Cloninger said. "After the more creative, sociable, and physically resilient Homo sapiens migrated out of Africa between 65,000 and 55,000 years ago, they displaced Neanderthals and other hominids, who all became extinct soon after 40,000 years ago."

The genes that distinguish modern humans from Neanderthals and chimpanzees are nearly all regulatory genes made of RNA, not protein-coding genes made of DNA.

"The protein-coding genes of Homo sapiens, Neanderthals, and chimps are nearly all the same, and what distinguishes these species is the regulation of the expression of their protein-coding genes by the genes found only in humans," said co-author Igor Zwir, a computer scientist at Washington University School of Medicine and the University of Granada. "We found that the regulatory genes unique to modern humans were constituents of clusters together with particular protein-coding genes that are overexpressed in the human brain network for self-awareness. The self-awareness network is essential to the physical, mental, and social well-being of humans because it provides the insight to regulate our habits in accord with our goals and values."

The researchers determined that the genes unique to modern humans were selected because of advantages tied to greater creativity, prosocial behavior, and healthy longevity. Living longer, healthier lives and being more prosocial and altruistic allowed Homo sapiens to support their children, grandchildren, and others in their communities throughout their lives in diverse and sometimes harsh conditions. And being more innovative than other hominids allowed humans to adapt more flexibly to unpredictable climatic fluctuations.

"In the bigger picture, this study helps us understand how we can effectively respond to the challenges that modern humans currently face," Tattersall said. "Our behavior is not fixed or determined by our genes. Indeed, human creativity, prosociality, and healthy longevity emerged in the context of the need to adjust rapidly to harsh and diverse conditions and to communicate in large social groups."

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ALMA discovers rotating infant galaxy with help of natural cosmic telescope

Using the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers found a rotating baby galaxy 1/100th the size of the Milky Way at a time when the Universe was only seven percent of its present age. Thanks to assistance by the gravitational lens effect, the team was able to explore for the first time the nature of small and dark "normal galaxies" in the early Universe, representative of the main population of the first galaxies, which greatly advances our understanding of the initial phase of galaxy evolution.

"Many of the galaxies that existed in the early Universe were so small that their brightness is well below the limit of the current largest telescopes on Earth and in Space, making difficult to study their properties and internal structure," says Nicolas Laporte, a Kavli Senior Fellow at the University of Cambridge. "However, the light coming from the galaxy named RXCJ0600-z6, was highly magnified by gravitational lensing, making it an ideal target for studying the properties and structure of a typical baby galaxies."

Gravitational lensing is a natural phenomenon in which light emitted from a distant object is bent by the gravity of a massive body such as a galaxy or a galaxy cluster located in the foreground. The name "gravitational lensing" is derived from the fact that the gravity of the massive object acts like a lens. When we look through a gravitational lens, the light of distant objects is intensified and their shapes are stretched. In other words, it is a "natural telescope" floating in space.

The ALMA Lensing Cluster Survey (ALCS) team used ALMA to search for a large number of galaxies in the early Universe that are enlarged by gravitational lensing. Combining the power of ALMA, with the help of the natural telescopes, the researchers are able to uncover and study fainter galaxies.

Why is it crucial to explore the faintest galaxies in the early Universe? Theory and simulations predict that the majority of galaxies formed few hundred millions years after the Big-Bang are small, and thus faint. Although several galaxies in the early Universe have been previously observed, those studied were limited to the most massive objects, and therefore the less representative galaxies, in the early Universe, because of telescopes capabilities. The only way to understand the standard formation of the first galaxies, and obtain a complete picture of galaxy formation, is to focus on the fainter and more numerous galaxies.

The ALCS team performed a large-scale observation program that took 95 hours, which is a very long time for ALMA observations, to observe the central regions of 33 galaxy clusters that could cause gravitational lensing. One of these clusters, called RXCJ0600-2007, is located in the direction of the constellation of Lepus, and has a mass 1000 trillion times that of the Sun. The team discovered a single distant galaxy that is being affected by the gravitational lens created by this natural telescope. ALMA detected the light from carbon ions and stardust in the galaxy and, together with data taken with the Gemini telescope, determined that the galaxy is seen as it was about 900 million years after the Big Bang (12.9 billion years ago). Further analysis of these data suggested that a part of this source is seen 160 times brighter than it is intrinsically.

By precisely measuring the mass distribution of the cluster of galaxies, it is possible to "undo" the gravitational lensing effect and restore the original appearance of the magnified object. By combining data from Hubble Space Telescope and the European Southern Observatory's Very Large Telescope with a theoretical model, the team succeeded in reconstructing the actual shape of the distant galaxy RXCJ0600-z6. The total mass of this galaxy is about 2 to 3 billion times that of the Sun, which is about 1/100th of the size of our own Milky Way Galaxy.

What astonished the team is that RXCJ0600-z6 is rotating. Traditionally, gas in the young galaxies was thought to have random, chaotic motion. Only recently has ALMA discovered several rotating young galaxies that have challenged the traditional theoretical framework, but these were several orders of magnitude brighter (larger) than RXCJ0600-z6.

"Our study demonstrates, for the first time, that we can directly measure the internal motion of such faint (less massive) galaxies in the early Universe and compare it with the theoretical predictions," says Kotaro Kohno, a professor at the University of Tokyo and the leader of the ALCS team.

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To design truly compostable plastic, scientists take cues from nature

Despite our efforts to sort and recycle, less than 9% of plastic gets recycled in the U.S., and most ends up in landfill or the environment.

Biodegradable plastic bags and containers could help, but if they're not properly sorted, they can contaminate otherwise recyclable #1 and #2 plastics. What's worse, most biodegradable plastics take months to break down, and when they finally do, they form microplastics -- tiny bits of plastic that can end up in oceans and animals' bodies -- including our own.

Now, as reported in the journal Nature, scientists at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley have designed an enzyme-activated compostable plastic that could diminish microplastics pollution, and holds great promise for plastics upcycling. The material can be broken down to its building blocks -- small individual molecules called monomers -- and then reformed into a new compostable plastic product.

"In the wild, enzymes are what nature uses to break things down -- and even when we die, enzymes cause our bodies to decompose naturally. So for this study, we asked ourselves, 'How can enzymes biodegrade plastic so it's part of nature?" said senior author Ting Xu , who holds titles of faculty senior scientist in Berkeley Lab's Materials Sciences Division, and professor of chemistry and materials science and engineering at UC Berkeley.

At Berkeley Lab, Xu -- who for nearly 15 years has dedicated her career to the development of functional polymer materials inspired by nature -- is leading an interdisciplinary team of scientists and engineers from universities and national labs around the country to tackle the mounting problem of plastic landfill posed by both single-use and so-called biodegradable plastics.

Most biodegradable plastics in use today are usually made of polylactic acid (PLA), a vegetable-based plastic material blended with cornstarch. There is also polycaprolactone (PCL), a biodegradable polyester that is widely used for biomedical applications such as tissue engineering.

But the problem with conventional biodegradable plastic is that they're indistinguishable from single-use plastics such as plastic film -- so a good chunk of these materials ends up in landfills. And even if a biodegradable plastic container gets deposited at an organic waste facility, it can't break down as fast as the lunch salad it once contained, so it ends up contaminating organic waste, said co-author Corinne Scown, a staff scientist and deputy director for the Research, Energy Analysis & Environmental Impacts Division in Berkeley Lab's Energy Technologies Area.

Another problem with biodegradable plastics is that they aren't as strong as regular plastic -- that's why you can't carry heavy items in a standard green compost bag. The tradeoff is that biodegradable plastics can break down over time -- but still, Xu said, they only break down into microplastics, which are still plastic, just a lot smaller.

So Xu and her team decided to take a different approach -- by "nanoconfining" enzymes into plastics.

Putting enzymes to work

Because enzymes are part of living systems, the trick would be carving out a safe place in the plastic for enzymes to lie dormant until they're called to action.

In a series of experiments, Xu and co-authors embedded trace amounts of the commercial enzymes Burkholderia cepacian lipase (BC-lipase) and proteinase K within the PLA and PCL plastic materials. The scientists also added an enzyme protectant called four-monomer random heteropolymer, or RHP, to help disperse the enzymes a few nanometers (billionths of a meter) apart.

In a stunning result, the scientists discovered that ordinary household tap water or standard soil composts converted the enzyme-embedded plastic material into its small-molecule building blocks called monomers, and eliminated microplastics in just a few days or weeks.

They also learned that BC-lipase is something of a finicky "eater." Before a lipase can convert a polymer chain into monomers, it must first catch the end of a polymer chain. By controlling when the lipase finds the chain end, it is possible to ensure the materials don't degrade until being triggered by hot water or compost soil, Xu explained.

In addition, they found that this strategy only works when BC-lipase is nanodispersed -- in this case, just 0.02 percent by weight in the PCL block -- rather than randomly tossed in and blended.

"Nanodispersion puts each enzyme molecule to work -- nothing goes to waste," Xu said.

And that matters when factoring in costs. Industrial enzymes can cost around $10 per kilogram, but this new approach would only add a few cents to the production cost of a kilogram of resin because the amount of enzymes required is so low -- and the material has a shelf life of more than 7 months, Scown added.

The proof is in the compost

X-ray scattering studies performed at Berkeley Lab's Advanced Light Source characterized the nanodispersion of enzymes in the PCL and PLA plastic materials.

Interfacial-tension experiments conducted by co-author Tom Russell revealed in real time how the size and shape of droplets changed as the plastic material decomposed into distinct molecules. The lab results also differentiated between enzyme and RHP molecules.

"The interfacial test gives you information about how the degradation is proceeding," he said. "But the proof is in the composting -- Ting and her team successfully recovered plastic monomers from biodegradable plastic simply by using RHPs, water, and compost soil."

Russell is a visiting faculty scientist and professor of polymer science and engineering from the University of Massachusetts who leads the Adaptive Interfacial Assemblies Towards Structuring Liquids program in Berkeley Lab's Materials Sciences Division.

Developing a very affordable and easily compostable plastic film could incentivize produce manufacturers to package fresh fruits and vegetables with compostable plastic instead of single-use plastic wrap -- and as a result, save organic waste facilities the extra expense of investing in expensive plastic-depackaging machines when they want to accept food waste for anaerobic digestion or composting, Scown said.

Since their approach could potentially work well with both hard, rigid plastics and soft, flexible plastics, Xu would like to broaden their study to polyolefins, a ubiquitous family of plastics commonly used to manufacture toys and electronic parts.

The team's truly compostable plastic could be on the shelves soon. They recently filed a patent application through UC Berkeley's patent office. And co-author Aaron Hall, who was a Ph.D. student in materials science and engineering at UC Berkeley at the time of the study, founded UC Berkeley startup Intropic Materials to further develop the new technology. He was recently selected to participate in Cyclotron Road, an entrepreneurial fellowship program in partnership with Activate.

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Mechanical engineers develop new high-performance artificial muscle technology

In the field of robotics, researchers are continually looking for the fastest, strongest, most efficient and lowest-cost ways to actuate, or enable, robots to make the movements needed to carry out their intended functions.

The quest for new and better actuation technologies and 'soft' robotics is often based on principles of biomimetics, in which machine components are designed to mimic the movement of human muscles -- and ideally, to outperform them. Despite the performance of actuators like electric motors and hydraulic pistons, their rigid form limits how they can be deployed. As robots transition to more biological forms and as people ask for more biomimetic prostheses, actuators need to evolve.

Associate professor (and alum) Michael Shafer and professor Heidi Feigenbaum of Northern Arizona University's Department of Mechanical Engineering, along with graduate student researcher Diego Higueras-Ruiz, published a paper in Science Robotics presenting a new, high-performance artificial muscle technology they developed in NAU's Dynamic Active Systems Laboratory. The paper, titled "Cavatappi artificial muscles from drawing, twisting, and coiling polymer tubes," details how the new technology enables more human-like motion due to its flexibility and adaptability, but outperforms human skeletal muscle in several metrics.

"We call these new linear actuators cavatappi artificial muscles based on their resemblance to the Italian pasta," Shafer said.

Because of their coiled, or helical, structure, the actuators can generate more power, making them an ideal technology for bioengineering and robotics applications. In the team's initial work, they demonstrated that cavatappi artificial muscles exhibit specific work and power metrics ten and five times higher than human skeletal muscles, respectively, and as they continue development, they expect to produce even higher levels of performance.

"The cavatappi artificial muscles are based on twisted polymer actuators (TPAs), which were pretty revolutionary when they first came out because they were powerful, lightweight and cheap. But they were very inefficient and slow to actuate because you had to heat and cool them. Additionally, their efficiency is only about two percent," Shafer said. "For the cavatappi, we get around this by using pressurized fluid to actuate, so we think these devices are far more likely to be adopted. These devices respond about as fast as we can pump the fluid. The big advantage is their efficiency. We have demonstrated contractile efficiency of up to about 45 percent, which is a very high number in the field of soft actuation."

The engineers think this technology could be used in soft robotics applications, conventional robotic actuators (for example, for walking robots), or even potentially in assistive technologies like exoskeletons or prostheses.

"We expect that future work will include the use of cavatappi artificial muscles in many applications due to their simplicity, low-cost, lightweight, flexibility, efficiency and strain energy recovery properties, among other benefits," Shafer said.

Technology is available for licensing, partnering opportunities.

Working with the NAU Innovations team, the inventors have taken steps to protect their intellectual property. The technology has entered the protection and early commercialization stage and is available for licensing and partnering opportunities. For more information, please contact NAU Innovations.

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Astronomers release new all-sky map of Milky Way's outer reaches

Astronomers using data from NASA and ESA (European Space Agency) telescopes have released a new all-sky map of the outermost region of our galaxy. [Editor's note: See Related Multimedia link below.] Known as the galactic halo, this area lies outside the swirling spiral arms that form the Milky Way's recognizable central disk and is sparsely populated with stars. Though the halo may appear mostly empty, it is also predicted to contain a massive reservoir of dark matter, a mysterious and invisible substance thought to make up the bulk of all the mass in the universe.

The data for the new map comes from ESA's Gaia mission and NASA's Near Earth Object Wide Field Infrared Survey Explorer, or NEOWISE, which operated from 2009 to 2013 under the moniker WISE. The study makes use of data collected by the spacecraft between 2009 and 2018.

The new map reveals how a small galaxy called the Large Magellanic Cloud (LMC) -- so named because it is the larger of two dwarf galaxies orbiting the Milky Way -- has sailed through the Milky Way's galactic halo like a ship through water, its gravity creating a wake in the stars behind it. The LMC is located about 160,000 light-years from Earth and is less than one-quarter the mass of the Milky Way.

Though the inner portions of the halo have been mapped with a high level of accuracy, this is the first map to provide a similar picture of the halo's outer regions, where the wake is found -- about 200,000 light-years to 325,000 light-years from the galactic center. Previous studies have hinted at the wake's existence, but the all-sky map confirms its presence and offers a detailed view of its shape, size, and location.

This disturbance in the halo also provides astronomers with an opportunity to study something they can't observe directly: dark matter. While it doesn't emit, reflect, or absorb light, the gravitational influence of dark matter has been observed across the universe. It is thought to create a scaffolding on which galaxies are built, such that without it, galaxies would fly apart as they spin. Dark matter is estimated to be five times more common in the universe than all the matter that emits and/or interacts with light, from stars to planets to gas clouds.

Although there are multiple theories about the nature of dark matter, all of them indicate that it should be present in the Milky Way's halo. If that's the case, then as the LMC sails through this region, it should leave a wake in the dark matter as well. The wake observed in the new star map is thought to be the outline of this dark matter wake; the stars are like leaves on the surface of this invisible ocean, their position shifting with the dark matter.

The interaction between the dark matter and the Large Magellanic Cloud has big implications for our galaxy. As the LMC orbits the Milky Way, the dark matter's gravity drags on the LMC and slows it down. This will cause the dwarf galaxy's orbit to get smaller and smaller, until the galaxy finally collides with the Milky Way in about 2 billion years. These types of mergers might be a key driver in the growth of massive galaxies across the universe. In fact, astronomers think the Milky Way merged with another small galaxy about 10 billion years ago.

"This robbing of a smaller galaxy's energy is not only why the LMC is merging with the Milky Way, but also why all galaxy mergers happen," said Rohan Naidu, a doctoral student in astronomy at Harvard University and a co-author of the new paper. "The wake in our map is a really neat confirmation that our basic picture for how galaxies merge is on point!"

A Rare Opportunity

The authors of the paper also think the new map -- along with additional data and theoretical analyses -- may provide a test for different theories about the nature of dark matter, such as whether it consists of particles, like regular matter, and what the properties of those particles are.

"You can imagine that the wake behind a boat will be different if the boat is sailing through water or through honey," said Charlie Conroy, a professor at Harvard University and an astronomer at the Center for Astrophysics | Harvard & Smithsonian, who coauthored the study. "In this case, the properties of the wake are determined by which dark matter theory we apply."

Conroy led the team that mapped the positions of over 1,300 stars in the halo. The challenge arose in trying to measure the exact distance from Earth to a large portion of those stars: It's often impossible to figure out whether a star is faint and close by or bright and far away. The team used data from ESA's Gaia mission, which provides the location of many stars in the sky but cannot measure distances to the stars in the Milky Way's outer regions.

After identifying stars most likely located in the halo (because they were not obviously inside our galaxy or the LMC), the team looked for stars belonging to a class of giant stars with a specific light "signature" detectable by NEOWISE. Knowing the basic properties of the selected stars enabled the team to figure out their distance from Earth and create the new map. It charts a region starting about 200,000 light-years from the Milky Way's center, or about where the LMC's wake was predicted to begin, and extends about 125,000 light-years beyond that.

Conroy and his colleagues were inspired to hunt for LMC's wake after learning about a team of astrophysicists at the University of Arizona in Tucson that makes computer models predicting what dark matter in the galactic halo should look like. The two groups worked together on the new study.

One model by the Arizona team, included in the new study, predicted the general structure and specific location of the star wake revealed in the new map. Once the data had confirmed that the model was correct, the team could confirm what other investigations have also hinted at: that the LMC is likely on its first orbit around the Milky Way. If the smaller galaxy had already made multiple orbits, the shape and location of the wake would be significantly different from what has been observed. Astronomers think the LMC formed in the same environment as the Milky Way and another nearby galaxy, M31, and that it is close to completing a long first orbit around our galaxy (about 13 billion years). Its next orbit will be much shorter due to its interaction with the Milky Way.

"Confirming our theoretical prediction with observational data tells us that our understanding of the interaction between these two galaxies, including the dark matter, is on the right track," said University of Arizona doctoral student in astronomy Nicolás Garavito-Camargo, who led work on the model used in the paper.

The new map also provides astronomers with a rare opportunity to test the properties of the dark matter (the notional water or honey) in our own galaxy. In the new study, Garavito-Camargo and colleagues used a popular dark matter theory called cold dark matter that fits the observed star map relatively well. Now the University of Arizona team is running simulations that use different dark matter theories to see which one best matches the wake observed in the stars.

"It's a really special set of circumstances that came together to create this scenario that lets us test our dark matter theories," said Gurtina Besla, a co-author of the study and an associate professor at the University of Arizona. "But we can only realize that test with the combination of this new map and the dark matter simulations that we built."

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