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Sunday, February 26, 2017

The Ancient Art of Kirigami Is Inspiring a New Class of Materials

Origami-inspired materials use folds in materials to embed powerful functionality. However, all that folding can be pretty labor intensive. Now, researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) are drawing material inspiration from another ancient Japanese paper craft — kirigami.

Kirigami relies on cuts, rather than folds, to change the structure and function of materials.

The buckling-induced cubic patterned kirigami sheet can be folded flat 
Image courtesy of Ahmad Rafsanjani/Harvard SEAS

In a new paper published in Physical Review Letters, SEAS researchers demonstrate how a thin, perforated sheet can be transformed into a foldable 3D structure by simply stretching the cut material.

“We find that applying sufficiently large amounts of stretching, buckling is triggered and results in the formation of a 3D structure comprising a well-organized pattern of mountains and valleys, very similar to popular origami folds such as the Miura-ori,” said Ahmad Rafsanjani, a postdoctoral fellow at SEAS and first author of the paper.



The team found that if the material is stretched more, the temporary deformations become permanent folds. The team also found that the pop-up pattern and resulting mechanical properties of the material can be controlled by varying the orientation of the cuts.

“This study shows a robust pop-up strategy to manufacture complex morphable structures out of completely flat perforated sheets,” said Katia Bertoldi, the John L. Loeb Associate Professor of the Natural Sciences at SEAS and senior author of the paper.



Contacts and sources:
Leah Burrows
Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) 

Even Shredded to Pieces They Live: How Nearly Immortal Hydras Know Where to Regrow Lost Body Parts

Hydras the almost immortal animals. immortal.

Few animals can match the humble hydra’s resilience. The small, tentacled freshwater animals can be literally shredded into pieces and regrow into healthy animals.

Hydras are a genus of the Cnidaria phylum. All cnidarians can regenerate, allowing them to recover from injury and to reproduce asexually. Hydras are simple, freshwater animals possessing radial symmetry and no post-mitotic cells. All hydra cells continually divide. It has been suggested that hydras do not undergo senescence, and, as such, are biologically

A study published February 7 in Cell Reports suggests that pieces of hydras have structural memory that helps them shape their new body plan according to the pattern inherited by the animal’s “skeleton.” Previously, scientists thought that only chemical signals told a hydra where its heads and/or feet should form.
Credit: Technion

Regenerating hydras use a network of tough, stringy protein fibers, called the cytoskeleton, to align their cells. When pieces are cut or torn from hydras, the cytoskeletal pattern survives and becomes part of the new animal. The pattern generates a small but potent amount of mechanical force that shows cells where to line up. This mechanical force can serve as a form of “memory” that stores information about the layout of animal bodies. “You have to think of it as part of the process of defining the pattern and not just an outcome”, says senior author, biophysicist Kinneret Keren of the Technion – Israel Institute of Technology

When pieces of hydra begin the regeneration process, the scraps of hydra fold into little balls, and the cytoskeleton has to find a balance between maintaining its old shape and adapting to the new conditions. “If you take a strip or a square fragment and turn it into a sphere, the fibers have to change or stretch a lot to do that,” explains Keren. However, some portions retain their pattern. As the little hydra tissue ball stretches into a tube and grows a tentacle-ringed mouth, the new body parts follow the template set by the cytoskeleton in fragments from the original hydra. 


Hydras
Credit: Stephen Friedt/Wikipedia

The main cytoskeletal structure in adult hydra is an array of aligned fibers that span the entire organism. Tampering with the cytoskeleton is enough to disrupt the formation of new hydras, the researchers found. In many ways, the cytoskeleton is like a system of taut wires that helps the hydra keep its shape and function. In one experiment, the researchers cut the original hydra into rings which folded into balls that contained multiple domains of aligned fibers. Those ring-shaped pieces grew into two-headed hydras. However, anchoring the hydra rings to stiff wires resulted in healthy one-headed hydras, suggesting that mechanical feedbacks promote order in the developing animal.

Hydras are much simpler than most of their cousins in the animal kingdom, but the basic pattern of aligned cytoskeletal fibers is common in many organs, including human muscles, heart, and guts. Studying hydra regeneration may lead to a better understanding of how mechanics integrate with biochemical signals to shape tissues and organs in other species. “The actomyosin cytoskeleton are the main force generator across the animal kingdom,” says Keren. “This is very universal.”



Contacts and sources:
Technion – Israel Institute of Technology.

Citation: "Structural Inheritance of the Actin Cytoskeletal Organization Determines the Body Axis in Regenerating Hydra"   Cell Reports

‘Eye-Opening’ Study Shows Rural U.S. Loses Forests Faster Than Cities

Americans are spending their lives farther from forests than they did at the end of the 20th century and, contrary to popular wisdom, the change is more pronounced in rural areas than in urban settings.

A study published today (Feb. 22) in the journal PLOS ONE says that between 1990 and 2000, the average distance from any point in the United States to the nearest forest increased by 14 percent - or about a third of a mile. And while the distance isn't insurmountable for humans in search of a nature fix, it can present challenges for wildlife and have broad effects on ecosystems.

Dr. Giorgos Mountrakis, an associate professor in the ESF Department of Environmental Resources, and co-author of the study, called the results "eye opening."

"Our study analyzed geographic distribution of forest losses across the continental U.S. While we focused on forests, the implications of our results go beyond forestry," Mountrakis said.

Figure;  Forest cover change (FCC) and forest attrition distance change (FADC) in level III ecoregions.While the southeastern U.S. is experiencing high forest loss, the highest forest attrition is concentrated in other parts of the country















Credit: Forest dynamics in the U.S. indicate disproportionate attrition in western forests, rural areas and public lands Sheng Yang Giorgos Mountrakis PLoS One

The study overturned conventional wisdom about forest loss, the researcher noted. The amount of forest attrition - the complete removal of forest patches - is considerably higher in rural areas and in public lands. "The public perceives the urbanized and private lands as more vulnerable," said Mountrakis, "but that's not what our study showed. Rural areas are at a higher risk of losing these forested patches.

"Patches of forests are important to study because they serve a lot of unique ecoservices," Mountrakis said, citing bird migration as one example. "You can think of the forests as little islands that the birds are hopping from one to the next."


Illustration shows a female spirit labeled "Public Spirit" warning two men cutting logs, of the consequences of deforestation.
Credit: Wikimedia Commons/Joseph Keppler - Library of Congress  Illus. from Puck, v. 14, no. 357, (1884 January 9), centerfold


"Typically we concentrate more on urban forest," said Sheng Yang, an ESF graduate student and co-author of the study, "but we may need to start paying more attention - let's say for biodiversity reasons - in rural rather than urban areas. Because the urban forests tend to receive much more attention, they are better protected."

Forest dynamics are an integral part of larger ecosystems and have the potential to significantly affect water chemistry, soil erosion, carbon sequestration patterns, local climate, biodiversity distribution and human quality of life, Mountrakis said.

Using forest maps over the entire continental United States, researchers compared satellite data from the 1990s with data from 2000. "We did a statistical analysis starting with forest maps from 1990 and compared it to forests in 2000," said Mountrakis.

The study looked at the loss of forest by calculating the distance to the nearest forest from every area in the landscape, Mountrakis said. The loss of a smaller isolated forest could have a greater environmental impact than losing acreage within a larger forest.

Credit; William B. Greeley, US Forest Service

The study also found distance to the nearest forest is considerably greater in western forests than eastern forests.

"So if you are in the western U.S. or you are in a rural area or you are in land owned by a public entity, it could be federal, state or local, your distance to the forest is increasing much faster than the other areas," he said. "The forests are getting further away from you."

"Distances to nearest forest are also increasing much faster in less forested landscapes. This indicates that the most spatially isolated - and therefore important - forests are the ones under the most pressure," said Yang.

Credit; William B. Greeley, US Forest Service

The loss of these unique forests proposes a different set of side effects, Mountrakis said, "for local climate, for biodiversity, for soil erosion. This is the major driver - we can link the loss of the isolated patches to all these environmental degradations."

Along with research into the drivers behind the loss of forests, Mountrakis expects the differing geographic distributions and differences in land ownership and urbanization levels will initiate new research and policy across forestry, ecology, social science and geography.

This work was supported by the National Urban and Community Forestry Advisory Council and the McIntire-Stennis program, U.S. Forest Service.






Contacts and sources:
 SUNY College of Environmental Science and Forestry

Citation: Forest dynamics in the U.S. indicate disproportionate attrition in western forests, rural areas and public lands Authors: Sheng Yang ,Giorgos Mountrakis
Published: February 22, 2017 http://dx.doi.org/10.1371/journal.pone.0171383

Nanoconfinement: A Boon for Hydrogen Vehicles?

Lawrence Livermore scientists have collaborated with an interdisciplinary team of researchers including colleagues from Sandia National Laboratories to develop an efficient hydrogen storage system that could be a boon for hydrogen powered vehicles.

Hydrogen is an excellent energy carrier, but the development of lightweight solid-state materials for compact, low-pressure storage is a huge challenge.

Complex metal hydrides are a promising class of hydrogen storage materials, but their viability is usually limited by slow hydrogen uptake and release. Nanoconfinement — infiltrating the metal hydride within a matrix of another material such as carbon — can, in certain instances, help make this process faster by shortening diffusion pathways for hydrogen or by changing the thermodynamic stability of the material.


Hydrogenation forms a mixture of lithium amide and hydride (light blue) as an outer shell around a lithium nitride particle (dark blue) nanoconfined in carbon. Nanoconfinement suppresses all other intermediate phases to prevent interface formation, which has the effect of dramatically improving the hydrogen storage performance.
Credit; LLNL


However, the Livermore-Sandia team, in conjunction with collaborators from Mahidol University in Thailand and the National Institute of Standards and Technology, showed that nanoconfinement can have another, potentially more important consequence. They found that the presence of internal “nano-interfaces” within nanoconfined hydrides can alter which phases appear when the material is cycled.

The researchers examined the high-capacity lithium nitride (Li3N) hydrogen storage system under nanoconfinement. Using a combination of theoretical and experimental techniques, they showed that the pathways for the uptake and release of hydrogen were fundamentally changed by the presence of nano-interfaces, leading to dramatically faster performance and reversibility. The research appears on the cover of the Feb. 23 edition of the journal Advanced Materials Interfaces.

“The key is to get rid of the undesirable intermediate phases, which slow down the material’s performance as they are formed or consumed. If you can do that, then the storage capacity kinetics dramatically improve and the thermodynamic requirements to achieve full recharge become far more reasonable,” said Brandon Wood, an LLNL materials scientist and lead author of the paper. “In this material, the nano-interfaces do just that, as long as the nanoconfined particles are small enough. It’s really a new paradigm for hydrogen storage, since it means that the reactions can be changed by engineering internal microstructures.”

The Livermore researchers used a thermodynamic modeling method that goes beyond conventional descriptions to consider the contributions from the evolving solid phase boundaries as the material is hydrogenated and dehydrogenated. They showed that accounting for these contributions eliminates intermediates in nanoconfined lithium nitride, which was confirmed spectroscopically.

Beyond demonstrating nanoconfined lithium nitride as a rechargeable, high-performing hydrogen-storage material, the work establishes that proper consideration of solid–solid nanointerfaces and particle microstructure are necessary for understanding hydrogen-induced phase transitions in complex metal hydrides.

“There is a direct analogy between hydrogen storage reactions and solid-state reactions in battery electrode materials,” said Tae Wook Heo, another LLNL co-author on the study. “People have been thinking about the role of interfaces in batteries for some time, and our work suggests that some of the same strategies being pursued in the battery community could also be applied to hydrogen storage. Tailoring morphology and internal microstructure could be the best way forward for engineering materials that could meet performance targets.”

Other Livermore researchers on the study include Keith Ray and Jonathan Lee.

The research is supported through the Hydrogen Storage Materials Advanced Research Consortium of the Department of Energy Office of Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office.


Contacts and sources: 
Anne M Stark
Lawrence Livermore National Laboratory 

Saturday, February 25, 2017

Is the Kid More Like Mom or Dad: Brain Cells Prefer One Parent’s Gene Over the Other’s


Many kids say they love their mom and dad equally, but there are times when even the best prefers one parent over the other. The same can be said for how the body’s cells treat our DNA instructions. It has long been thought that each copy - one inherited from mom and one from dad - is treated the same. A new study from scientists at the University of Utah School of Medicine shows that it is not uncommon for cells in the brain to preferentially activate one copy over the other. The finding breaks basic tenants of classic genetics and suggests new ways in which genetic mutations might cause brain disorders.

In at least one region of the newborn mouse brain, the new research shows, inequality seems to be the norm. About 85 percent of genes in the dorsal raphe nucleus, known for secreting the mood-controlling chemical serotonin, differentially activate their maternal and paternal gene copies. Ten days later in the juvenile brain, the landscape shifts, with both copies being activated equally for all but 10 percent of genes.

More than an oddity of the brain, the disparity also takes place at other sites in the body, including liver and muscle. It also occurs in humans.


Many cells in the brain express two copies of each gene, one inherited from mom and one from dad. Others express just one copy. If the single copy happens to carry a genetic mutation, it may cause the cell to become sick. The discovery from the University of Utah offers a previously undescribed nuanced view of genetics that has consequences at the cellular level.
Credit: Christopher Gregg


“We usually think of traits in terms of a whole person, or animal. We’re finding that when we look at the level of cells, genetics is much more complicated than we thought,” says Christopher Gregg, Ph.D., assistant professor of neurobiology and anatomy and senior author of the study which publishes online in Neuron on Feb. 23. “This new picture may help us understand brain disorders,” he continues.

Among genes regulated in this unorthodox way are risk factors for mental illness. In humans, a gene called DEAF1, implicated in autism and intellectual disability, shows preferential expression of one gene copy in multiple regions of the brain. A more comprehensive survey in primates, which acts as a proxy for humans, indicates the same is true for many other genes including some linked to Huntington’s Disease, schizophrenia, attention deficit disorder, and bipoloar disorder.

What the genetic imbalance could mean for our health remains to be determined, but preliminary results suggest that it could shape vulnerabilities to disease, explains Gregg. Normally, having two copies of a gene acts as a protective buffer in case one is defective. Activating a gene copy that is mutated and silencing the healthy copy - even temporarily - could be disruptive enough to cause trouble in specific cells.

Supporting the idea, Gregg’s lab found that some brain cells in transgenic mice preferentially activate mutated gene copies over healthy ones. “It has generally been assumed that there is correlation between both copies of a gene,” says Elliott Ferris, a computer scientist who co-led the study with graduate student Wei-Chao Huang. Instead, they found something unexpected. “We developed novel methods for mining big data, and discovered something new,” Huang explains.

The investigators screened thousands of genes in their study, quantifying the relative levels of activation for each maternal and paternal gene copy and discovered that expression of the two is different for many genes. Surprised by what they saw, they developed statistical methods to rigorously test their validity and determined that they were not due to technical artifacts, nor genetic noise. Following up on their findings, they examined a subset of genes more closely, directly visualized imbalances between gene copies at the cellular level in the mouse and human brain.

Results from Gregg and colleagues build on previous research, expanding on scenarios in which genes play favorites. Imprinted genes and X-linked genes are specific gene categories that differentially activate their maternal and paternal gene copies. Studies in cultured cells had also determined that some genes vary which copy they express. The results from this study, however, suggests that silencing one gene copy may be a way in which cells fine tune their genetic program at specific times during the lifecycle of the animal, or in discrete places.

“Our new findings reveal a new landscape of diverse effects that shape the expression of maternal and paternal gene copies in the brain according to age, brain region, and tissue type,” explains Gregg. “The implication is a new view of genetics, one that starts up close.”



Contacts and sources:

Fracking Wastewater Spills Alter Microbes in West Virginia Waters

Wastewater from oil and gas operations – including fracking for shale gas – at a West Virginia site altered microbes downstream, according to a Rutgers-led study.

The study, published recently in Science of the Total Environment, showed that wastewater releases, including briny water that contained petroleum and other pollutants, altered the diversity, numbers and functions of microbes. The shifts in the microbial community indicated changes in their respiration and nutrient cycling, along with signs of stress.

The study also documented changes in antibiotic resistance in downstream sediments, but did not uncover hot spots, or areas with high levels of resistance. The findings point to the need to understand the impacts on microbial ecosystems from accidental releases or improper treatment of fracking-related wastewater. Moreover, microbial changes in sediments may have implications for the treatment and beneficial reuse of wastewater, the researchers say.


The hydraulic fracturing (fracking) water cycle includes withdrawing water, adding chemicals, injecting fracking fluids through a well to a rock formation, and pumping wastewater to the surface for disposal or reuse.

Credit: U.S. Environmental Protection Agency


“My hope is that the study could be used to start making hypotheses about the impacts of wastewater,” said Nicole Fahrenfeld, lead author of the study and assistant professor in Rutgers’ Department of Civil and Environmental Engineering. Much remains unknown about the impacts of wastewater from fracking, she added.

“I do think we’re at the beginning of seeing what the impacts could be,” said Fahrenfeld, who works in the School of Engineering. “I want to learn about the real risks and focus our efforts on what matters in the environment.”

Underground reservoirs of oil and natural gas contain water that is naturally occurring or injected to boost production, according to the U.S. Geological Survey (USGS), whose scientists contributed to the study. During fracking, a fracturing fluid and a solid material are injected into an underground reservoir under very high pressure, creating fractures to increase the porosity and permeability of rocks.


Nicole Fahrenfeld, assistant professor in the Department of Civil and Environmental Engineering. 
Photo: Nick Romanenko


Liquid pumped to the surface is usually a mixture of the injected fluids with briny water from the reservoir. It can contain dissolved salt, petroleum and other organic compounds, suspended solids, trace elements, bacteria, naturally occurring radioactive materials and anything injected into wells, the USGS says. Such water is recycled, treated and discharged; spread on roads, evaporated or infiltrated; or injected into deep wells.

Fracking for natural gas and oil and its wastewater has increased dramatically in recent years. And that could overwhelm local infrastructure and strain many parts of the post-fracking water cycle, including the storage, treatment, reuse, transportation or disposal of the wastewater, according to the USGS.

For the Rutgers-USGS study, water and sediment samples were collected from tributaries of Wolf Creek in West Virginia in June 2014, including an unnamed tributary that runs through an underground injection control facility.

The facility includes a disposal well, which injects wastewater to 2,600 feet below the surface, brine storage tanks, an access road and two lined ponds (now-closed) that were used to temporarily store wastewater to allow particles to settle before injection.

Water samples were shipped to Rutgers, where they were analyzed. Sediment samples were analyzed at the Waksman Genomics Core Facility at Rutgers. The study generated a rich dataset from metagenomic sequencing, which pinpoints the genes in entire microbial communities, Fahrenfeld noted.

“The results showed shifts in the microbial community and antibiotic resistance, but this site doesn’t appear to be a new hot spot for antibiotic resistance,” she said. The use of biocides in some fracturing fluids raised the question of whether this type of wastewater could serve as an environment that is favorable for increasing antimicrobial resistance. Antimicrobial resistance detected in these sediments did not rise to the levels found in municipal wastewater – an important environmental source of antimicrobial resistance along with agricultural sites.

Antibiotics and similar drugs have been used so widely and for so long that the microbes the antibiotics are designed to kill have adapted to them, making the drugs less effective, according to the U.S. Centers for Disease Control and Prevention. At least 2 million people become infected with antibiotic-resistant bacteria each year in the U.S., with at least 23,000 of them dying from the infections.

“We have this really nice dataset with all the genes and all the microbes that were at the site,” Fahrenfeld said. “We hope to apply some of these techniques to other environmental systems.”

Study authors include Rutgers undergraduate Hannah Delos Reyes and Rutgers doctoral candidate Alessia Eramo. Other authors include Denise M. Akob, Adam C. Mumford and Isabelle M. Cozzarelli of the U.S. Geological Survey’s National Research Program. Mumford earned a doctorate in microbiology at Rutgers.


Contacts and sources:
Todd B. Bates
Rutgers University

700% Surge in Infections Caused by Antibiotic Resistant Bacteria: A Fast Growing Problem for Kids Too

The adage that kids are growing up too fast these days has yet another locus of applicability.

In a new, first-of-its-kind study, researchers from Case Western Reserve University School of Medicine have found a 700-percent surge in infections caused by bacteria from the Enterobacteriaceae family resistant to multiple kinds of antibiotics among children in the US. These antibiotic resistant infections are in turn linked to longer hospital stays and potentially greater risk of death.

The research, published in the March issue of the Journal of the Pediatric Infectious Diseases Society, is the first known effort to comprehensively examine the problem of multi-drug resistant infections among patients under 18 admitted to US children’s hospitals with Enterobacteriaceae infections. Earlier studies focused mainly on adults, while some looked at young people in more limited geographical areas, such as individual hospitals or cities, or used more limited surveillance data.

Credit: Penn State

“There is a clear and alarming upswing throughout this country of antibiotic resistant Enterobacteriaceae infections in kids and teens,” said lead author Sharon B. Meropol, MD, PhD, a pediatrician and epidemiologist at Case Western Reserve University School of Medicine and Rainbow Babies and Children’s Hospital in Cleveland. “This makes it harder to effectively treat our patients’ infections. The problem is compounded because there are fewer antibiotics approved for young people than adults to begin with. Health care providers have to make sure we only prescribe antibiotics when they’re really needed. It’s also essential to stop using antibiotics in healthy agricultural animals.”

In the retrospective study, Meropol and co-authors Allison A. Haupt, MSPH, and Sara M. Debanne, PhD, both from Case Western Reserve University School of Medicine, analyzed medical data from nearly 94,000 patients under the age of 18 years diagnosed with Enterobacteriaceae-associated infections at 48 children’s hospitals throughout the US. The average age was 4.1 years. Enterobacteriaceae are a family of bacteria; some types are harmless, but they also include such pathogens as Salmonella and Escherichia coli; Enterobacteriaceae are responsible for a rising proportion of serious bacterial infections in children.



The researchers found that the share of these infections resistant to multiple antibiotics rose from 0.2 percent in 2007 to 1.5 percent in 2015, a seven-fold-plus increase in a short, eight-year span. Children with other health problems were more likely to have the infections while there were no overall differences based on sex or insurance coverage. The yearly number of discharges with Enterobacteriaceae-associated infections remained relatively stable over the course of the study years.

In a key finding, more than 75 percent of the antibiotic-resistant infections were already present when the young people were admitted to the hospital, upending previous findings that the infections were mostly picked up in the hospital. “This suggests that the resistant bacteria are now more common in many communities,” said Meropol. For reasons that are unclear, older children and those living in the Western US were more likely to have the infections.

The investigators also found that young people with antibiotic-resistant infections stayed in the hospital 20 percent longer than those whose infections could be addressed by antibiotics. Additionally, there was a greater—but not statistically significant—risk of death among pediatric patients infected with the resistant bacterial strains.

Previous studies have shown that the problem is even worse elsewhere in the world, with an 11.4 percent global rate of antibiotic-resistant Enterobacteriaceae infections among young people, including 27 percent in Asia and the Pacific, 8.8 percent in Latin America, and 2.5 percent in Europe.

“Escalating antibiotic resistance limits our treatment options, worsens clinical results, and is a growing global public health crisis,” said Meropol. “What’s more, the development of new antibacterial drugs, especially ones appropriate for children, remains essentially stagnant. We need to stop over-using antibiotics in animals and humans and develop new ones if we want to stop a bad problem from getting worse.”

This work was supported by the National Institute for Allergy and Infectious Diseases at the National Institutes of Health [K23AI097284-01A1].



Contacts and sources: 

Human Brains Could Evolve to Require Very Little Sleep, Just Like The Cavefish


We all do it; we all need it – humans and animals alike. Sleep is an essential behavior shared by nearly all animals and disruption of this process is associated with an array of physiological and behavioral deficits. Although there are so many factors contributing to sleep loss, very little is known about the neural basis for interactions between sleep and sensory processing.

Neuroscientists at Florida Atlantic University have been studying Mexican cavefish to provide insight into the evolutionary mechanisms regulating sleep loss and the relationship between sensory processing and sleep. They are investigating how sleep evolves and using this species as a model to understand how human brains could evolve to require very little sleep, just like the cavefish

The Pachón cavefish live in deep, dark caves in central Mexico, with little food, oxygen or light, and have lost their eyes completely. Because of their harsh environment, they have evolved to get very creative in order to survive and suppress sleep. They are able to find their way around by means of their lateral lines, which are highly sensitive to fluctuating water pressure.

Credit: Pavel Masek


In their latest study, just published in the Journal of Experimental Biology, findings suggest that an inability to block out your environment is one of the ways to lose sleep. The study also provides a model for understanding how the brain’s sensory systems modulate sleep and sheds light into the evolution of the significant differences in sleep duration observed throughout the animal kingdom.

“Animals have dramatic differences in sleep with some sleeping as much as 20 hours and others as little as two hours and no one knows why these dramatic differences in sleep exist,” said Alex C. Keene, Ph.D., corresponding author of the study and an associate professor in the Department of Biological Sciences in FAU’s Charles E. Schmidt College of Science. “Our study suggests that differences in sensory systems may contribute to this sleep variability. It is possible that evolution drives sensory changes and changes in sleep are a secondary consequence, or that evolution selects for changes in sensory processing in order to change sleep.”


Credit: FAU Science Jupiter

Because the cave environment differs dramatically from the rivers inhabited by surface fish, cavefish have evolved robust differences in foraging and feeding behavior, raising the possibility that differences in nutrient availability contribute to the evolution of sleep loss in cave populations. Furthermore, multiple cave populations have evolved substantial reductions in sleep duration and enhanced sensory systems, suggesting that sleep loss is evolutionary and functionally associated with sensory and metabolic changes.

Key findings of the study have shown that the evolution of enhanced sensory capabilities contribute to sleep loss in cavefish and that sleep in cavefish is plastic and may be regulated by seasonal changes in food availability.

There are more than 29 different populations of cavefish and many of them evolved independently. This enabled the researchers to determine whether evolution occurs through the same or different mechanisms. The Pachon cavefish, the population they studied, appear to have lost sleep due to increased sensory input, but not the other populations.

“We were surprised to find that there are multiple independent mechanisms regulating sleep loss in different cave populations and this can be a significant strength moving forward,” said James Jaggard, first author and a graduate student at FAU working with Keene. “This means that there are many different ways to lose sleep or evolve a brain that sleeps less and we are going to search to identify these mechanisms.”

Keene, Jaggard and their colleagues use Mexican cavefish because they are a powerful system for examining trait evolution. In earlier research studies, they observed the evolutionary convergence on sleep loss in these fish. However, the neural mechanisms underlying this dramatic behavioral shift remained elusive. Since they already knew that cavefish also had evolved a highly sensitive lateral line (the groups of sensory neurons that line the body of the fish), they wondered if an increase in sensory input from these neurons contribute to sleep loss.

For the study, the researchers recorded the cavefish under infrared light set up in individual tanks. They automated video-tracking software that told them when the fish were inactive and they defined sleep as one minute of immobility because it correlated with changes in arousal threshold.

“Humans block out sensory cues when we enter a sleep-like state,” said Keene. “For example, we close our eyes and there are mechanisms in the brain to reduce auditory input. This is one of the reasons why a sensory stimuli like someone entering a room is less likely to get your attention if you are asleep. Our thinking was that cavefish have to some degree lost this ability and this drives sleep loss.”

The researchers recently generated transgenic fish lines and they will be able to image brain activity and genetically map anatomical differences between the Mexican cavefish populations.

This study is supported by a grant from the National Science Foundation (1601004).


Contacts and sources:
Gisele Galoustian
Florida Atlantic University:

Cat Ownership Not Linked to Mental Health Problems

New UCL research has found no link between cat ownership and psychotic symptoms, casting doubt on previous suggestions that people who grew up with cats are at higher risk of mental illness.

Recent research has suggested that cat ownership might contribute to some mental disorders, because cats are the primary host of the common parasite Toxoplasma Gondii (T. Gondii), itself linked to mental health problems such as schizophrenia.

"The message for cat owners is clear: there is no evidence that cats pose a risk to children's mental health," says lead author Dr Francesca Solmi (UCL Psychiatry). "In our study, initial unadjusted analyses suggested a small link between cat ownership and psychotic symptoms at age 13, but this turned out to be due to other factors. Once we controlled for factors such as household over-crowding and socioeconomic status, the data showed that cats were not to blame. Previous studies reporting links between cat ownership and psychosis simply failed to adequately control for other possible explanations."

Credit: UCL


The new study, published in Psychological Medicine, suggests that cat ownership in pregnancy and childhood does not play a role in developing psychotic symptoms during adolescence. The study looked at nearly 5000 people born in 1991 or 1992 who were followed-up until the age of 18. The researchers had data on whether the household had cats while the mother was pregnant and when the children were growing up.

The new study was significantly more reliable than previous research in this area since the team looked at families who were followed up regularly for almost 20 years. This is much more reliable than methods used in previous studies, which asked people with and without mental health problems to remember details about their childhood. Such accounts are more vulnerable to errors in recall which can lead to spurious findings.

Previous studies were also relatively small and had significant gaps in the data, whereas the new study looked at a large population and was able to account for missing data. The new study was not able to measure T. Gondii exposure directly, but the results suggest that if the parasite does cause psychiatric problems then cat ownership does not significantly increase exposure.


6 paintings of cats by Louis Wain with an increasing degree of abstractedness, attributed by some to his suffering from schizophrenia
Credit; Louis Wain


"Our study suggests that cat ownership during pregnancy or in early childhood does not pose a direct risk for later psychotic symptoms," explains senior author Dr James Kirkbride (UCL Psychiatry). "However, there is good evidence that T. Gondii exposure during pregnancy can lead to serious birth defects and other health problems in children. As such, we recommend that pregnant women should continue to follow advice not to handle soiled cat litter in case it contains T. Gondii."



Contacts and sources:
Harry Dayantis
University College London

Simple Rule Predicts an Ice Age’s End

A simple rule can accurately predict when Earth’s climate warms out of an ice age, according to new research led by UCL.

In a new study published  in Nature, researchers from UCL, University of Cambridge and University of Louvain have combined existing ideas to solve the problem of which solar energy peaks in the last 2.6 million years led to the melting of the ice sheets and the start of a warm period.

During this interval, Earth’s climate has alternated between cold (glacial) and warm (interglacial) periods. In the cold times, ice sheets advanced over large parts of North America and northern Europe. In the warm periods like today, the ice sheets retreated completely.


The Antarctic ice sheet 

Credit: Stephen Hudson via Wikimedia Commons


It has long been realised that these cycles were paced by astronomical changes in the Earth’s orbit around the Sun and in the tilt of its axis, which change the amount of solar energy available to melt ice at high northern latitudes in summer.

However, of the 110 incoming solar energy peaks (about every 21,000 years) only 50 led to complete melting of the ice sheets. Finding a way to translate the astronomical changes into the sequence of interglacials has previously proved elusive.

Professor Chronis Tzedakis (UCL Geography) said: “The basic idea is that there is a threshold for the amount of energy reaching high northern latitudes in summer. Above that threshold, the ice retreats completely and we enter an interglacial.”

From 2.6 to 1 million years ago, the threshold was reached roughly every 41,000 years, and this predicts almost perfectly when interglacials started and the ice sheets disappeared. Professor Eric Wolff (University of Cambridge) said: “Simply put, every second solar energy peak occurs when the Earth’s axis is more inclined, boosting the total energy at high latitudes above the threshold.”

Somewhere around a million years ago, the threshold rose, so that the ice sheets kept growing for longer than 41,000 years. However, as a glacial period lengthens, ice sheets become larger, but also more unstable.

The researchers combined these observations into a simple model, using only solar energy and waiting time since the previous interglacial, that was able to predict all the interglacial onsets of the last million years, occurring roughly every 100,000 years.

Dr Takahito Mitsui (University of Louvain) said: “The next step is to understand why the energy threshold rose around a million years ago – one idea is that this was due to a decline in the concentration of CO2, and this needs to be tested.”

The results explain why we have been in a warm period for the last 11,000 years: despite the weak increase in solar energy, ice sheets retreated completely during our current interglacial because of the very long waiting time since the previous interglacial and the accumulated instability of ice sheets.

Intriguingly, the researchers found that sometimes the amount of energy was very close to the threshold, so that some interglacials were just aborted, while others just made it. “The threshold was only just missed 50,000 years ago. If it hadn’t been missed, then we wouldn’t have had an interglacial in the last 11,000 years” added Professor Michel Crucifix (University of Louvain).

However, statistical analysis shows that the succession of interglacials is not chaotic: the sequence that has occurred is one among a very small set of possibilities. “Finding order among what can look like unpredictable swings in climate is aesthetically rather pleasing” said Professor Tzedakis.




Contacts and sources:
Ruth Howells
University College London 

FuturaCorp: A.I. Will Make Us More Human By Eliminating Workplace Drudgery Says New Research

The arrival of Artificial Intelligence (AI) in the workplace could triple productivity by automating more than 80 per cent of repetitive, process-oriented tasks - freeing human minds from tedium and enabling them to focus on creating and innovating, according to research from Goldsmiths, University of London and IPsoft.

The result will be a revolutionary shift in workplace productivity and a fundamental restructuring of work as we know it as humans are redeployed in higher-skill roles. 


The study, FuturaCorp: Artificial Intelligence & The Freedom To Be Human paints a vision of ‘FuturaCorp’ – an idealised man + machine workplace of tomorrow.
  
Credit: IPSoft 


The research describes job roles as comprised of a series of tasks. Some are repetitive and process-oriented (deterministic). Some require a human working in concert with machines (probabilistic). Some rely on the types of connections that can only be made by the human brain, from ideas generation to complex problem solving (cross-functional reasoning).

The Goldsmiths team predicts that, in the near future:

• More than 80% of deterministic tasks will be done by machines
• Probabilistic tasks will be shared 50:50 by machines and humans
• But humans will still carry out 80% of all cross-functional reasoning tasks

Dr. Chris Brauer, Director of Innovation and a Senior Lecturer at Goldsmiths, University of London, says: "AI will do far more than automate existing processes. It will free our minds from process-oriented repetition, enabling a refocusing of time and capital for our most human of pursuits: innovation and creativity. So the arrival of AI in workplaces will engender entirely new, unknown possibilities for humans and what they can achieve."



The study paints an optimistic picture of the future for individuals, pointing out that previous waves of automation have led to low-skill work being replaced by new, higher-skill jobs. It predicts that the arrival of the robots in the workplace will make us more human, pointing to crucial human skills that we will need to nurture to complement our digital colleagues.

Chetan Dube, CEO and President of IPsoft said: “AI engenders emergent individual qualities which push us to access the more complex parts of our minds. When routine work is automated, we will be able – and required – to flex our most human of skills. To do what the machines can’t, and likely never will be able to do. The future of society relies on individuals accessing higher reasoning, critical thinking and complex problem solving skills.” 
Credit: IPSoft


However, the need for rapid skill transformation could lead to a near-term skills shortage, according to the research.

The Goldsmiths team found little widespread evidence of businesses, universities and training institutions preparing individuals to manage these looming future shifts.

Finally, the research team developed in liaison with IPsoft a first-of-its-kind ‘organisational readiness equation’ for business leaders to assess how equipped their company is to take its first brave steps into an AI future. The equation scores an organisation in relation to the utopian vision of FuturaCorp, and helps leaders to determine what changes need to be made to push the business model towards this ideal.

Chetan Dube concludes: “CEOs must be prepared to redefine their business in order to capitalise on the productivity potential of AI. That journey begins with fundamental change to organization structure, who they hire for which roles, and how they use the new relationship between humans and machines to maximize efficiency and innovation.”



Contacts and sources:
Oliver Fry, Goldsmiths University of London
IPSoft

Citation: FuturaCorp: Artificial Intelligence & the Freedom to Be Human

New “Tougher-Than-Metal” Fiber-Reinforced Hydrogels

A team of Hokkaido University scientists has succeeded in creating “fiber-reinforced soft composites,” or tough hydrogels combined with woven fiber fabric. These fabrics are highly flexible, tougher than metals, and have a wide range of potential applications.

Efforts are currently underway around the world to create materials that are friendly to both society and the environment. Among them are those that comprise different materials, which exhibit the merits of each component.


The newly developed fiber-reinforced hydrogel consists of polyampholyte (PA) gels and glass fiber fabric. The team theorizes that toughness is increased by dynamic ionic bonds between the fiber and hydrogels, and within the hydrogels. 
Credit: Hokkaido University


Hokkaido University researchers, led by Professor Jian Ping Gong, have focused on creating a reinforced material using hydrogels. Though such a substance has potential as a structural biomaterial, up until now no material reliable and strong enough for long-term use has been produced. This study was conducted as a part of the Cabinet Office’s Impulsing Paradigm Change through Disruptive Technologies Program (ImPACT).

To address the problem, the team combined hydrogels containing high levels of water with glass fiber fabric to create bendable, yet tough materials, employing the same method used to produce reinforced plastics. The team found that a combination of polyampholyte (PA) gels, a type of hydrogel they developed earlier, and glass fiber fabric with a single fiber measuring around 10μm in diameter produced a strong, tensile material. The procedure to make the material is simply to immerse the fabric in PA precursor solutions for polymerization.

When used alone, the fiber-reinforced hydrogels developed by the team are 25 times tougher than glass fiber fabric, and 100 times tougher than hydrogels - in terms of the energy required to destroy them. Combining these materials enables a synergistic toughening. The team theorizes that toughness is increased by dynamic ionic bonds between the fiber and hydrogels, and within the hydrogels, as the fiber’s toughness increases in relation to that of the hydrogels. Consequently, the newly developed hydrogels are 5 times tougher compared to carbon steel.

“The fiber-reinforced hydrogels, with a 40 percent water level, are environmentally friendly,” says Dr. Jian Ping Gong, “The material has multiple potential applications because of its reliability, durability and flexibility. For example, in addition to fashion and manufacturing uses, it could be used as artificial ligaments and tendons, which are subject to strong load-bearing tensions.” The principles to create the toughness of the present study can also be applied to other soft components, such as rubber.



Contacts and sources:
Professor Jiang Ping Gong
Graduate School of Life Science
Hokkaido University
 

Measuring the True Size of Gods and Giants

Archeological artefacts, such as the Jupiter Column of Ladenburg, a town with an impressive Roman history, hold many as yet undiscovered secrets. Discovered in 1973, the history of the monument that is more than 1800 years old is still unclear. 

The HEiKA MUSIEKE project is aimed at uncovering some of these secrets and making the cultural heritage of Ladenburg visible and perceptible. For this purpose, modern digitization techniques of Karlsruhe Institute of Technology (KIT) are used.

“Contact-free digitization of objects opens up new approaches to research,” Dr. Thomas Vögtle of KIT’s Institute of Photogrammetry and Remote Sensing says. The Jupiter Column is about four meters high and combines Roman and Germanic symbols and conceptions. The figures on the column represent the battle between the Roman god Jupiter and a giant. The texture of the column and the equestrian figure, however, appear to follow Celtic tradition. “The digital model makes archeologists and laymen experience the artefact in an entirely new way.”


Digitization of the Jupiter Column makes this cultural heritage perceptible by both archaeologists and laymen. 
Photo: KIT/IPEF


To model the three-dimensional structure of the column on the computer, the KIT team uses a professional, commercially available digital single-lens reflex camera of 36 megapixels resolution with conventional illumination technology. “Our hardware is robust and mobile so that we can collect our data easily, rapidly, and at low costs at any place,” Vögtle explains. 

On a single working day, the team took about 800 photos of the column from all perspectives. On the computer, characteristic features of the column were identified and interlinked in the different images. Information of the two-dimensional photos was processed to yield a photorealistic, three-dimensional model. Using this model, hardly visible structures can be seen with the bare eye. “The computer model then is the basis for further work of archeologists.” 

“Digital objects may also provide laymen with a new experience of cultural heritage,” Dr. Ralf Schneider of ZAK I Center for Cultural and General Studies of KIT says. He coordinates the HEiKA-MUSIEKE – Multidimensional Perceptibility of Cultural Heritage project. Large parts of our cultural heritage have long been lost from our world of interest. With the help of digital methods, cultural heritage can be acquired, analyzed, and presented to a broader public in a new way, in a context that is also understandable by laymen. 


The Jupiter Column from Ladenburg. 
Photo: KIT/IPF


The MUSIEKE project combines archeology, remote sensing, forensic computer science, geoinformatics, and applied cultural science to make cultural heritage perceptible. Apart from the digitization of artefacts, it also covers the generation of databases with geoinformation or production of digital maps of various historic stages of settlements and cities.

Vögtle normally uses photogrammetry and digitization methods for technical purposes. Based on aerial photos, he determines the orientation of roofs in cities for finding out whether they are suited for the installation of solar facilities. In industrial production, camera photos are used to find out whether the product was produced with the required accuracy and can be used in the next production stage or needs to be adjusted. Or the progress of construction of an underground station can be compared with the planned target. “In production or in the construction sector in particular, objects have to be measured in a contact-free, automatic, and rapid way. Cameras and digitization are very valuable tools for this purpose,” Vögtle says.



Contacts and sources:
Kosta Schinarakis

Darwin’s “Abominable Mystery: ”Where Do Flowers Come From? Researchers Find Clues

The mystery that is the origin of flowering plants has been partially solved thanks to a team of French researchers.  

Their discovery, published in the journal New Phytologist on February 24, 2017, sheds light on a question that much intrigued Darwin: the appearance of a structure as complex as the flower over the course of evolution.  The team was made up of researchers from the Laboratoire de Physiologie Cellulaire et Végétale (CNRS/Inra/CEA/Université Grenoble Alpes), in collaboration with the Reproduction et Développement des Plantes laboratory (CNRS/ENS Lyon/Inra/Université Claude Bernard Lyon 1) and Kew Gardens (UK).

Terrestrial flora is today dominated by flowering plants. They provide our food and contribute color to the plant world. But they have not always existed. While plants colonized the land over 400 million years ago, flowering plants appeared only 150 million years ago. They were directly preceded by a group known as the gymnosperms, whose mode of reproduction is more rudimentary and whose modern-day representatives include conifers.


Detail of a Welwitschia mirabilis plant showing its two leaves and male cones. 
Credit: Michael W. Frohlich 


Darwin long pondered the origin and rapid diversification of flowering plants, describing them as an “abominable mystery”. In comparison with gymnosperms, which possess rather rudimentary male and female cones (like the pine cone), flowering plants present several innovations: the flower contains the male organs (stamens) and the female organs (pistil), surrounded by petals and sepals, while the ovules, instead of being naked, are protected within the pistil.


A female Welwitschia mirabilis plant in its natural environment in the desert of Namibia. 
Credit: Stephen G. Weller & Ann K. Sakai


How was nature able to invent the flower, a structure so different from that of cones? The team led by François Parcy, a CNRS senior researcher at the Cell and Plant Physiology Laboratory (CNRS/Inra/CEA/Université Grenoble Alpes), has just provided part of the answer. To do so, the researchers studied a rather original gymnosperm called Welwitschia mirabilis. This plant, which can live for more than a millennium, grows in the extreme conditions of the deserts of Namibia and Angola, and, like other gymnosperms, possesses separate male and female cones.


Close-up on male cones, on which pollen can be seen. 

Credit: Michael W. Frohlich


 What is exceptional is that the male cones possess a few sterile ovules and nectar, which indicates a failed attempt to invent the bisexual flower. Yet, in this plant (as well as in certain conifers), the researchers found genes similar to those responsible for the formation of flowers, and which are organized according to the same hierarchy (with the activation of one gene activating the next gene, and so on)!

The fact that a similar gene cascade has been found in flowering plants and their gymnosperm cousins indicates that this is inherited from their common ancestor. This mechanism did not have to be invented at the time of the origins of the flower: it was simply inherited and reused by the plant, a process that is often at work in evolution.

The study of the current biodiversity of plants thus enables us to go back in time and gradually sketch the genetic portrait of the common ancestor of a large proportion of modern-day flowers. The team is continuing to study other traits to better understand how the first flower emerged.



Contacts and sources:
CNRS (Délégation Paris Michel-Ange)


Citation: A link between LEAFY and B-gene homologs in Welwitschia mirabilis sheds light on ancestral mechanisms prefiguring floral development, Edwige Moyroud, Marie Monniaux, Emmanuel Thévenon, Renaud Dumas, Charles P. Scutt, Michael W.Frohlich, François Parcy. New Phytologist, 24 February 2017. DOI:10.1111/nph.14483

Violently Exploding Ice

A droplet of water freezing from the outside in, shows an exciting series of rapid changes until it violently explodes. Researchers of the University of Twente in The Netherlands unravel this in their paper in Physical Review Letters of February 24.

Water droplets that freeze from the outside in, show an exciting series of rapid physical changes before they violently explode. This is shown by University of Twente researchers in their paper in Physical Review Letters of February 24.

A perfectly spherical droplet of water that freezes from the outside, forms a shell first. This has the diameter of the droplet. As the shell thickens inward, the remaining water ‘gets a problem’: it wants to expand, but is confined by the shell. After some time, this causes the droplet to explode. But what happens in between?

Credit: University of Twente


Shell formation

For creating spherical droplets, the UT scientists have placed them on a hydrophobic surface, placed in a vacuum chamber. The temperature is lowered by evaporative cooling so that the droplet is ‘supercooled’: the temperature is well below zero but the droplet doesn’t freeze yet. The first ice crystal is formed by touching the droplet with a silver iodide tip. A skin of ice forms rapidly, thickening from the outside in. The video images show that cracks are formed in the shell, that a peak is formed and vapour cavities are formed underneath the surface. After releasing some ice flakes, the whole droplet explodes in the end. The ice parts have velocities of about 1,5 m/sec. 
Credit: Sander Wildeman

Clouds

The mathematical model Sander Wildeman and his colleagues developed for explaining this series of events, show that there is a minimum droplet size: below a diameter of 50 micron, no explosion will take place. Meteorologists already know the phenomenon of droplet explosions in the cold tops of clouds. They play a role in the onset of precipitation and can lead to the rapid transformation of a cloud with fluid droplets to a cloud of ice droplets.

‘Dutch tears’

The experiments have some resemblance to a well-known way to produce hard glass, already known to Dutch glass-blowers in 17th century. Droplets of molten glass, put into cold water, also solidify from the outside in, forming a shell of glass around the melt. They are also known as ‘Dutch tears’. The difference with water is that glass shrinks when it becomes solid. This makes the glass sphere very strong.

Max Planck Center

The research has been done in the Physics of Fluids group of Prof. Detlef Lohse. This group will be part of the new Max Planck - University of Twente Center for Complex Fluid Dynamics that will be opened March 3, 2017.



Contacts and sources:
Wiebe Van Der Veen
University of Twente


Citation: ‘Fast Dynamics of Water Droplets Freezing from the Outside In’, by Sander Wildeman, Sebastian Sterl, Chao Sun and Detlef Lohse, Physical Review Letters, February 24, 2017.
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118.084101

Vast Cosmic Mystery Posed by Giant Luminous Nebula


Astronomers have found an enormous, glowing blob of gas in the distant universe, with no obvious source of power for the light it is emitting. Called an "enormous Lyman-alpha nebula" (ELAN), it is the brightest and among the largest of these rare objects, only a handful of which have been observed.

ELANs are huge blobs of gas surrounding and extending between galaxies in the intergalactic medium. They are thought to be parts of the network of filaments connecting galaxies in a vast cosmic web. Previously discovered ELANs are likely illuminated by the intense radiation from quasars, but it's not clear what is causing the hydrogen gas in the newly discovered nebula to emit Lyman-alpha radiation (a characteristic wavelength of light absorbed and emitted by hydrogen atoms).

The newly discovered nebula was found at a distance of 10 billion light years in the middle of a region with an extraordinary concentration of galaxies. Researchers found this massive overdensity of early galaxies, called a "protocluster," through a novel survey project led by Zheng Cai, a Hubble Postdoctoral Fellow at UC Santa Cruz.


MAMMOTH-1 is an extended blob of gas in the intergalactic medium called an enormous Lyman-alpha nebula (ELAN). The color map and contours denote the surface brightness of the nebula, and the red arrows show its estimated spatial extent.

Credit: Cai et al., Astrophysical Journal (Figure 2)


"Our survey was not trying to find nebulae. We're looking for the most overdense environments in the early universe, the big cities where there are lots of galaxies," said Cai. "We found this enormous nebula in the middle of the protocluster, near the peak density."

Cai is first author of a paper on the discovery accepted for publication in the Astrophysical Journal and available online at arxiv.org/abs/1609.04021. His survey project is called Mapping the Most Massive Overdensities Through Hydrogen (MAMMOTH), and the newly discovered ELAN is known as MAMMOTH-1.

Coauthor J. Xavier Prochaska, professor of astronomy and astrophysics at UC Santa Cruz, said previously discovered ELANs have been detected in quasar surveys. In those cases, the intense radiation from a quasar illuminated hydrogen gas in the nebula, causing it to emit Lyman-alpha radiation. Prochaska's team discovered the first ELAN, dubbed the "Slug Nebula," in 2014. MAMMOTH-1 is the first one not associated with a visible quasar, he said.

"It's extremely bright, and it's probably larger than the Slug Nebula, but there's nothing else visible except the faint smudge of a galaxy. So it's a terrifically energetic phenomenon without an obvious power source," Prochaska said.

Equally impressive is the enormous protocluster in which it resides, he said. Protoclusters are the precursors to galaxy clusters, which consist of hundreds to thousands of galaxies bound together by gravity. Because protoclusters are spread out over a much larger area of the sky, they are much harder to find than galaxy clusters.

The protocluster hosting the MAMMOTH-1 nebula is massive, with an unusually high concentration of galaxies in an area about 50 million light years across. Because it is so far away (10 billion light years), astronomers are in effect looking back in time to see the protocluster as it was 10 billion years ago, or about 3 billion years after the big bang, during the peak epoch of galaxy formation. After evolving for 10 billion more years, this protocluster would today be a mature galaxy cluster perhaps only one million light years across, having collapsed down to a much smaller area, Prochaska said.

The standard cosmological model of structure formation in the universe predicts that galaxies are embedded in a cosmic web of matter, most of which is invisible dark matter. The gas that collapses to form galaxies and stars traces the distribution of dark matter and extends beyond the galaxies along the filaments of the cosmic web. The MAMMOTH-1 nebula appears to have a filamentary structure that aligns with the galaxy distribution in the large-scale structure of the protocluster, supporting the idea that ELANs are illuminated segments of the cosmic web, Cai said.

"From the distribution of galaxies we can infer where the filaments of the cosmic web are, and the nebula is perfectly aligned with that structure," he said.

Cai and his coauthors considered several possible mechanisms that could be powering the Lyman-alpha emission from the nebula. The most likely explanations involve radiation or outflows from an active galactic nucleus (AGN) that is strongly obscured by dust so that only a faint source can be seen associated with the nebula. An AGN is powered by a supermassive black hole actively feeding on gas in the center of a galaxy, and it is usually an extremely bright source of light (quasars being the most luminous AGNs in visible light).

The intense radiation from an AGN can ionize the gas around it (called photoionization), and this may be one mechanism at work in MAMMOTH-1. When ionized hydrogen in the nebula recombines it would emit Lyman-alpha radiation. Another possible mechanism powering the Lyman-alpha emissions is shock heating by a powerful outflow of gas from the AGN.

The researchers described several lines of evidence supporting the existence of a hidden AGN energizing the nebula, including the dynamics of the gas and emissions from other elements besides hydrogen, notably helium and carbon.

"It has all the hallmarks of an AGN, but we don't see anything in our optical images. I expect there's a quasar that is so obscured by dust that most of its light is hidden," Prochaska said.



Contacts and sources:
Tim Stephens
University of California Santa Cruz

38,000-Year-Old Engravings Confirm Ancient Origins of Pointillist Technique Used By Seurat, Van Gogh



A newly discovered trove of 16 engraved and otherwise modified limestone blocks, created 38,000 years ago, confirms the ancient origins of the pointillist techniques later adopted by 19th and 20th century artists such as Georges Seurat, Vincent Van Gogh, Camille Pissarro, and Roy Lichtenstein.

"We're quite familiar with the techniques of these modern artists," observes New York University anthropologist Randall White, who led the excavation in France's Vézère Valley. "But now we can confirm this form of image-making was already being practiced by Europe's earliest human culture, the Aurignacian."

Pointillism, a painting technique in which small dots are used to create the illusion of a larger image, was developed in the 1880s. However, archaeologists have now found evidence of this technique thousands of years earlier -- dating back more than 35,000 years.


Newly discovered limestone slab from Abri Cellier with pointillist mammoth in profile view formed my dozens of individual punctuations and re-shaping of the natural edge of the block to conform to the animals head and back line.

Photo and drawing by R. Bourrillon.


The findings appear in the journal Quaternary International.

Major discoveries by White and his colleagues--which include images of mammoths and horses--confirm that a form of pointillism was used by the Aurignacian, the earliest modern human culture in Europe. These add weight to previous isolated discoveries, such as a rhinoceros, from the Grotte Chauvet in France, formed by the application of dozens of dots, first painted on the palm of the hand, and then transferred to the cave wall.

Earlier this year, White's team reported the uncovering of a 38,000-year-old pointillist image of an aurochs or wild cow--a finding that marks some of the earliest known graphic imagery found in Western Eurasia and offers insights into the nature of modern humans during this period. Now, in short order they have found another pointillist image--this time of a woolly mammoth--in a rock shelter of the same period known as Abri Cellier located near the previous find-site of Abri Blanchard.

Abri Cellier has long been on archeologists' short-list of major art-bearing sites attributed to the European Aurignacian. Excavations in 1927 yielded 15 engraved and/or pierced limestone blocks that have served as a key point of reference for the study of Aurignacian art in the region.


This is a graphic rendering of the recently published Blanchard aurochs illustrating the arrangement of punctuations in relation to the animal.

Photo and drawing by R. Bourrillon


In 2014, White and his colleagues returned to Cellier, seeking intact deposits that would allow a better understanding of the archaeological sequence at the site and its relationship to other Aurignacian sites. They had their fingers crossed that the new excavation might yield new engraved images in context, but nothing prepared them for the discovery of the 16 stone blocks detailed in the Quaternary International article. One of these, broken in half prehistorically, was found in place with a radiocarbon date of 38,000 years ago.

Remarkably, the remaining 15 blocks, including the pointillist mammoth, one of three mammoth figures recognized during the new work at Cellier, had been left on-site by the 1927 excavators. As many of the engraved traces are rudimentary and thus difficult to interpret, the original excavators set them aside just in case they might have something inscribed on them. The new article presents evidence that the 38,000 year date for the newly excavated engraving also applies to the new trove and to the other blocks found in 1927 and now housed in the French National Prehistory Museum.

Over the past decade, with these and other discoveries, White and his team have increased our known sample of the earliest graphic arts in southwestern France by 40 percent. The team includes researchers from the University of Arizona, the University of Toronto, the University of Toulouse, Paris' Museum of Natural History, and the University of Oxford.

The research appearing in Quaternary International was supported by the Partner University Fund and the Andrew Mellon Foundation, the Direction régional des affaires culturelles d'Aquitaine (DRAC-Aquitaine), the Institut des Sciences Humaines et Sociales (INSHS) of the CNRS, the Faculty of Arts and Science at NYU, and the Fyssen Foundation.




Contacts and sources:
James Devitt
New York University

Friday, February 24, 2017

Stunning Images from 30 Years of Observing Supernova 1987a

Three decades ago, astronomers spotted one of the brightest exploding stars in more than 400 years. The titanic supernova, called Supernova 1987A (SN 1987A), blazed with the power of 100 million suns for several months following its discovery on Feb. 23, 1987.

Since that first sighting, SN 1987A has continued to fascinate astronomers with its spectacular light show. Located in the nearby Large Magellanic Cloud, it is the nearest supernova explosion observed in hundreds of years and the best opportunity yet for astronomers to study the phases before, during, and after the death of a star.


The video begins with a nighttime view of the Small and Large Magellanic clouds, satellite galaxies of our Milky Way. It then zooms into a rich star-birth region in the Large Magellanic Cloud. Nestled between mountains of red-colored gas is the odd-looking structure of Supernova 1987A, the remnant of an exploded star that was first observed in February 1987. The site of the supernova is surrounded by a ring of material that is illuminated by a wave of energy from the outburst. Two faint outer rings are also visible. All three rings existed before the explosion as fossil relics of the doomed star’s activity in its final days.
Credits: NASA, ESA, and G. Bacon (STScI)


To commemorate the 30th anniversary of SN 1987A, new images, time-lapse movies, a data-based animation based on work led by Salvatore Orlando at INAF-Osservatorio Astronomico di Palermo, Italy, and a three-dimensional model are being released. By combining data from NASA's Hubble Space Telescope and Chandra X-ray Observatory, as well as the international Atacama Large Millimeter/submillimeter Array (ALMA), astronomers — and the public — can explore SN 1987A like never before.


This Hubble Space Telescope image shows Supernova 1987A within the Large Magellanic Cloud, a neighboring galaxy to our Milky Way.

Credits: NASA, ESA, R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation), and M. Mutchler and R. Avila (STScI)


This time-lapse video sequence of Hubble Space Telescope images reveals dramatic changes in a ring of material around the exploded star Supernova 1987A. The images, taken from 1994 to 2016, show the effects of a shock wave from the supernova blast smashing into the ring. The ring begins to brighten as the shock wave hits it. The ring is about one light-year across.

Credits: NASA, ESA, and R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation), and P. Challis (Harvard-Smithsonian Center for Astrophysics)

Hubble has repeatedly observed SN 1987A since 1990, accumulating hundreds of images, and Chandra began observing SN 1987A shortly after its deployment in 1999. ALMA, a powerful array of 66 antennas, has been gathering high-resolution millimeter and submillimeter data on SN 1987A since its inception.

"The 30 years' worth of observations of SN 1987A are important because they provide insight into the last stages of stellar evolution," said Robert Kirshner of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and the Gordon and Betty Moore Foundation in Palo Alto, California.

The latest data from these powerful telescopes indicate that SN 1987A has passed an important threshold. The supernova shock wave is moving beyond the dense ring of gas produced late in the life of the pre-supernova star when a fast outflow or wind from the star collided with a slower wind generated in an earlier red giant phase of the star's evolution. What lies beyond the ring is poorly known at present, and depends on the details of the evolution of the star when it was a red giant.


This scientific visualization, using data from a computer simulation, shows Supernova 1987A, as the luminous ring of material we see today.
Credits: NASA, ESA, and F. Summers and G. Bacon (STScI); Simulation Credit: S. Orlando (INAF-Osservatorio Astronomico di Palermo)


"The details of this transition will give astronomers a better understanding of the life of the doomed star, and how it ended," said Kari Frank of Penn State University who led the latest Chandra study of SN 1987A.

Supernovas such as SN 1987A can stir up the surrounding gas and trigger the formation of new stars and planets. The gas from which these stars and planets form will be enriched with elements such as carbon, nitrogen, oxygen and iron, which are the basic components of all known life. These elements are forged inside the pre-supernova star and during the supernova explosion itself, and then dispersed into their host galaxy by expanding supernova remnants. Continued studies of SN 1987A should give unique insight into the early stages of this dispersal.

Some highlights from studies involving these telescopes include:

Hubble studies have revealed that the dense ring of gas around the supernova is glowing in optical light, and has a diameter of about a light-year. The ring was there at least 20,000 years before the star exploded. A flash of ultraviolet light from the explosion energized the gas in the ring, making it glow for decades.


These images, taken between 1994 and 2016 by NASA's Hubble Space Telescope, chronicle the brightening of a ring of gas around an exploded star.

Credits: NASA, ESA, and R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation), and P. Challis (Harvard-Smithsonian Center for Astrophysics)


The central structure visible inside the ring in the Hubble image has now grown to roughly half a light-year across. Most noticeable are two blobs of debris in the center of the supernova remnant racing away from each other at roughly 20 million miles an hour.

From 1999 until 2013, Chandra data showed an expanding ring of X-ray emission that had been steadily getting brighter. The blast wave from the original explosion has been bursting through and heating the ring of gas surrounding the supernova, producing X-ray emission.


Astronomers combined observations from three different observatories to produce this colorful, multiwavelength image of the intricate remains of Supernova 1987A.
Credits: NASA, ESA, and A. Angelich (NRAO/AUI/NSF); Hubble credit: NASA, ESA, and R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation) Chandra credit: NASA/CXC/Penn State/K. Frank et al.; ALMA credit: ALMA (ESO/NAOJ/NRAO) and R. Indebetouw (NRAO/AUI/NSF)

In the past few years, the ring has stopped getting brighter in X-rays. From about February 2013 until the last Chandra observation analyzed in September 2015 the total amount of low-energy X-rays has remained constant. Also, the bottom left part of the ring has started to fade. These changes provide evidence that the explosion's blast wave has moved beyond the ring into a region with less dense gas. This represents the end of an era for SN 1987A.

Beginning in 2012, astronomers used ALMA to observe the glowing remains of the supernova, studying how the remnant is actually forging vast amounts of new dust from the new elements created in the progenitor star. A portion of this dust will make its way into interstellar space and may become the building blocks of future stars and planets in another system.

These observations also suggest that dust in the early universe likely formed from similar supernova explosions.

Astronomers also are still looking for evidence of a black hole or a neutron star left behind by the blast. They observed a flash of neutrinos from the star just as it erupted. This detection makes astronomers quite certain a compact object formed as the center of the star collapsed — either a neutron star or a black hole — but no telescope has uncovered any evidence for one yet.

These latest visuals were made possible by combining several sources of information including simulations by Salvatore Orlando and collaborators that appear in this paper: https://arxiv.org/abs/1508.02275. The Chandra study by Frank et al. can be found online at http://lanl.arxiv.org/abs/1608.02160. Recent ALMA results on SN 87A are available at https://arxiv.org/abs/1312.4086.

The Chandra program is managed by NASA's Marshall Space Flight Center in Huntsville, Alabama, for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.

ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of South Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ.




Contacts and sources:
Donna Weaver / Ray Villard
Space Telescope Science Institute, Baltimore, Md

Megan Watzke
Chandra X-ray Center, Cambridge, Mass.

Rob Gutro
NASA’s Goddard Space Flight Center,