Tech

High-energy ion beams -- laser-like beams of atomic particles fired through accelerators -- have applications that range from inertial confinement fusion to the production of superhot extreme states of matter that are thought to exist in the core of giant planets like Jupiter and that researchers are eager to study. These positively charged ion beams must be neutralized by negatively charged electrons to keep them sharply focused. However, researchers have found many obstacles to the neutralization process.

Featured Article

At the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL), scientists have discovered a surprising new obstacle that reduces the neutralization of ion beam pulses. The findings, reported in Physics of Plasmas and promoted as a Featured Article, provide new insight into a source of the problem and indicate how to prevent it.

The discovery proposes an explanation for the poor rate of neutralization first observed in experiments at the Lawrence Berkeley National Laboratory back in 2002. The problem has remained unexplained prior to the development of codes capable of simulating the processes involved.

Physicist Chaohui Lan, a visiting scientist from the China Academy of Engineering Physics, uncovered the cause while performing computer simulations of electron dynamics with PPPL physicist Igor Kaganovich, deputy head of the PPPL Theory and Computation Department. Their research on Princeton University computers explored the injection of electrons from a thin filament into the beam pulse to neutralize it for effective focusing and transport. Results showed that the process reduced neutralization when compared with passing the beam through plasma ¬-- the charged state of matter composed of free ions and electrons.

Charged islands

"In these simulations I found something unusual," said Lan, lead author of the Physics of Plasmas paper that Kaganovich coauthored. "I called them 'charged islands' that could not be further neutralized by injected electrons."

What Lan had stumbled on was formation of "electrostatic solitary waves" (ESW), a type of stable electron-excited wave that previous studies of neutralization had not reported. Such waves can reach several centimeters in length and move back and forth from the edges of the ion beam pulse, affecting electron motion and reducing neutralization. The waves interact weakly with one another and in some cases disrupt and impart energy to the electrons, causing them to escape the beam and further reduce the neutralization.

To minimize the problem, the new findings suggest widening the filament that injects the electrons into the beam to improve the rate of neutralization. "That broadens the distribution of electrons," says Kaganovich, "and lessens the excitation of the waves." Moreover, he adds, the model developed at PPPL should help researchers study and understand the mechanisms behind the excitation of these waves to aid in controlling them.

Though abundance is a fundamental measure in ecology and environmental management, detecting all individuals in a population is usually impossible when monitoring, so estimates of abundance must account for imperfect detection.

Researchers developed the first method designed specifically to estimate population abundance from simultaneous counts of unmarked individuals over multiple sites, testing the methodology on three species of critically endangered vulture species in Cambodia.

They found that the new approach works best when existing methods are expected to perform poorly (few sites, large variation in abundance among sites), and when individuals may move among sites between sampling; and they believe the approach will be useful in particular for simultaneous surveys at aggregation sites, such as roosts.

Researchers conducted a 12-year study from 2010 to 2017 on ocelots (Leopardus pardalis) in the Brazilian Amazon, deploying 899 camera traps at 12 stations to determine habitat preferences, which were largely unknown.

Their findings show that ocelots are ubiquitous and adaptable, and seemingly abundant in protected areas or wherever there are forests populated with suitable prey.

The authors warn, however, that this does do not justify complacency regarding their conservation, as deforestation is destroying their habitat.

Analyzing the data on 10,077 citizen complaints lodged against the Chicago Police Department between 2011 and 2014, a pair of New York University researchers has found that just 2 percent of allegations made by black Chicagoans resulted in a recommendation for sanction against an officer, compared to 20 percent for white complainants and 7 percent for Latino complainants.

The study by Jacob W. Faber, assistant professor at NYU's Robert F. Wagner Graduate School of Public Service, and Jessica Kalbfeld, doctoral candidate in NYU's Sociology Department, underscores the impact and implications of racial distrust in a highly segregated city.

"We have shown that not only are officers rarely disciplined for alleged misconduct, but that there are significant racial disparities in the outcomes of a process ostensibly designed to provide accountability in a highly segregated city," writes Faber and Kalbfeld in the article for the June issue of City and Community, a journal of the American Sociological Association.

"Although we are unable to prove explicit racial discrimination, the inequalities created and/or perpetuated by this process are still of great import to the policed communities, the CPD [Chicago Police Department] and criminologists. Perceptions about (or the reality of) the unfairness of the disciplinary process may reduce trust in law enforcement and exacerbate tensions between communities of color and the police," the authors wrote.

The paper also shows that racial disparities in the adjudication of citizen allegations of police misconduct are further shaped by the race of the officer involved and neighborhood context: incidents alleged by white citizens in high-crime and predominantly black neighborhoods are more likely to result in a recommendation that the officer be punished, as are incidents involving a black officer.

Researchers at Dana-Farber Cancer Institute and the VA Boston Healthcare System have uncovered a new vital sign for gauging survival and likelihood of having an unplanned hospitalization in older patients with blood cancers: the speed at which they can walk.

In a study published today in the journal Blood, the researchers report that for every 0.1 meter per second decrease in how fast patients walk four meters (about 13 feet), the risk of dying, unexpectedly going to the hospital, or using the emergency room increased by 22 percent, 33 percent, and 34 percent, respectively. The association was strongest in patients with non-Hodgkin lymphoma.

"The slower someone walks, the higher their risk of problems," said the study's senior author, Jane A. Driver, MD, MPH, co-director of the Older Adult Hematologic Malignancy (OHM) Program at Dana-Farber and associate director of the Geriatric Research Education and Clinical Center at VA Boston Healthcare System.

Measuring gait speed not only helps identify individuals who are frail and may have worse long-term outcomes, but it also can indicate those who are in better-than-expected shape based on their age. Researchers say the study results support efforts to integrate gait speed as a routine part of medical assessments for older patients with blood cancer, and that it should be measured over time to guide treatment plans.

"There is an unmet need for brief screening tests for frailty that can easily fit into clinic workflow and predict important clinical outcomes. This test can be done in less than a minute and takes no longer than measuring blood pressure or other vital signs," said Driver. "Based on our findings, it is as good as other commonly used methods which take considerably more time and resources and may not be practical for many oncology clinics."

The new study enrolled 448 adults ages 75 years and older who had hematologic cancers. Participants were 79.7 years old on average and completed several screenings for cognition, frailty, gait, and grip strength. Gait speed was measured using the National Institutes of Health 4-meter gait speed test. Patients were asked to walk at a normal pace for 4 meters and their speed was recorded in meters per second using a stopwatch.

The association between slower walking speed and poorer outcomes persisted even after adjusting for cancer type and aggressiveness, patient age and other demographic factors, as well as traditional measures of frailty and functional status. Gait speed remained an independent predictor of death even after accounting for standard measures of physical health.

Patients whose performance status - their general well-being and quality of life - was rated as very good or excellent by their physician were stratified into three groups by gait speed - those at risk or frail, pre-frail, or robust. Of the 314 patients in this group, nearly 20 percent had an unplanned hospital stay unrelated to elective or scheduled treatments, and 16.8 percent visited the emergency department.

"Our study reveals that the current standard of care for functional assessment in oncology--performance status--is not sufficient for elders with blood cancers. Gait speed appears to be much better at differentiating those patients at highest risk for poor outcomes," explained Gregory A. Abel, MD, MPH, director of the OHM clinic.

So much a part of everyday life that it's easily taken for granted, walking is a complex activity that involves multiple bodily systems, including the musculoskeletal, cardiovascular, and nervous systems, all of which must function properly together. Gait speed has been widely used as an assessment in rehabilitative and geriatric medicine. Measuring it doesn't require special equipment, is reasonably efficient, and has value even for patients who use a cane or a walker, Driver noted.

Adversity early in life tends to affect a child's executive function skills -- their ability to focus, for example, or organize tasks.

Experiences such as poverty, residential instability, or parental divorce or substance abuse, also can lead to changes in a child's brain chemistry, muting the effects of stress hormones. These hormones rise to help us face challenges, stress or to simply "get up and go."

Together, these impacts to executive function and stress hormones create a snowball effect, adding to social and emotional challenges that can continue through childhood. A new University of Washington study examines how adversity can change the ways children develop.

"This study shows how adversity is affecting multiple systems inside a child," said the study's lead author, Liliana Lengua, a UW professor of psychology and director of the Center for Child and Family Well-Being. "The disruption of multiple systems of self-control, both intentional planning efforts and automatic stress-hormone responses, sets off a cascade of neurobiological effects that starts early and continues through childhood."

The study, published May 10 in Development and Psychopathology, evaluated 306 children at intervals over more than two years, starting when participants were around 3 years old, up to age 5 ½. Children were from a range of racial, ethnic and socioeconomic backgrounds, with 57% considered lower income or near poverty.

Income was a key marker for adversity. In addition, the children's mothers were surveyed about other risk factors that have been linked to poor health and behavior outcomes in children, including family transitions, residential instability, and negative life events such as abuse or the incarceration of a parent.

Against these data, Lengua's team tested children's executive function skills with a series of activities, and, through saliva samples, a stress-response hormone called diurnal cortisol.

The hormone that "helps us rise to a challenge," Lengua said, cortisol tends to follow a daily, or diurnal, pattern: It increases early in the morning, helping us to wake up. It is highest in the morning -- think of it as the energy to face the day -- and then starts to fall throughout the day. But the pattern is different among children and adults who face constant stress, Lengua said.

"What we see in individuals experiencing chronic adversity is that their morning levels are quite low and flat through the day, every day. When someone is faced with high levels of stress all the time, the cortisol response becomes immune, and the system stops responding. That means they're not having the cortisol levels they need to be alert and awake and emotionally ready to meet the challenges of the day," she said.

To assess executive function, researchers chose preschool-friendly activities that measured each child's ability to follow directions, pay attention and take actions contrary to impulse. For instance, in a game called "Head-Toes-Knees-Shoulders," children are told to do the opposite of what a researcher tells them to do -- if the researcher says, "touch your head," the child is supposed to touch their toes. In another activity, children interact with two puppets -- a monkey and a dragon -- but are supposed to follow only the instructions given by the monkey.

When children are better at following instructions in these and similar activities, they tend to have better social skills and manage their emotions when stressed. Children who did well on these tasks also tended to have more typical patterns of diurnal cortisol.

But children who were in families that had lower income and higher adversity tended to have both lower executive function and an atypical diurnal cortisol pattern. Each of those contributed to more behavior problems and lower social-emotional competence in children when they were about to start kindergarten.

The study shows that not only do low income and adversity affect children's adjustment, but they also impact these self-regulation systems that then add to children's adjustment problems. "Taken all together, it's like a snowball effect, with adverse effects adding together," Lengua said.

While past research has pointed to the effects of adversity on executive function, and to the specific relationship between cortisol and executive function, this new study shows the additive effects over time, Lengua said.

"Executive function is an indicator that shows the functioning of cognitive regulation. Cortisol is the neuroendocrine response, an automatic response, and the two consistently emerge as being related to each other and impacting behavior in children," she said.

The research could be used to inform parenting programs, early childhood and school-based interventions, Lengua said. Safe, stable environments and communities, and positive, nurturing parenting practices support child development, while a focus on relationships and healthy behaviors in preschool settings can support children of all backgrounds -- those with high as well as low adversity.

Clinicians often feel that they have a role in preventing firearm injury. But few talk with patients about the risk of firearms and safe firearm practices during office visits.

Physicians and researchers at the UC Davis Violence Prevention Research Program (VPRP), Brown University, the University of Colorado and Stanford University are looking to change that. They've developed a clinical guide to help providers get more comfortable recognizing a patient's risk of firearm injury or death. It also helps them talk with patients about firearm safety and teaches them how to intervene in emergency situations.

Their guide, published June 4 in the Annals of Internal Medicine's "In the Clinic" series, is based on existing research and on expert opinion.

"Clinicians are uniquely positioned to identify at-risk patients and discuss safe firearm practices, and patients are overwhelmingly open to having these conversations, especially when they happen directly in the context of the patient's health or the health of someone else in the home," said Rocco Pallin, first author and director of VPRP's What You Can Do initiative.

"This article presents background and practical tools to help clinicians recognize risk and start having these conversations when they feel firearms are clinically relevant," she said.

The guide shares findings from existing studies on firearm-related harm and violence prevention. It recommends strategies for screening, counseling and potential interventions when needed. It also provides a toolkit with information for patients and clinicians on firearm injury and firearm safety.

Researchers believe that a better understanding of gun ownership and more evidence on the factors that increase the risk of violence and injury can help physicians increase patient safety. The authors suggest a conversational and collaborative approach to discussions about firearm safety.

Facts on gun violence, gun ownership and risk factors for clinicians:

Homicides: Highest among teens and young adults, especially African Americans. Highest in the south. Highest in urban areas.

Suicides: Highest among middle-aged and older white men. Highest in Montana, Idaho and western states. Highest in rural areas.

U.S. gun owners: Most are male, white, middle-aged or older and residents of non-urban areas.

Reasons Americans own guns: protection from other people (63%), for hunting (40%) and other sporting uses (28%).

Gun safety: Approximately 20% of homes with children have guns stored in the least safe manner.

Mental illness and guns: Contrary to common belief, only 4% to 5% of person-on-person violence is primarily attributable to diagnosed mental illness.

Risk factors: Patients with abusive partners, alcohol and other substance misuse, history of violent behavior, dementia, impaired cognition, poorly controlled mental illness, prior convictions for violent crimes.

Laws: It is legal for physicians to have discussions about gun ownership with their patients. A survey of gun owners found 70% were somewhat comfortable talking about owning guns if their physicians asked.

Garen Wintemute, VPRP's director, emphasizes that "preventing firearm violence is absolutely 'in our lane' for physicians and other health professionals. We hope this new guide and other materials at the What You Can Do website will give them the knowledge and tools they need to help protect the health and safety of their patients and communities."

Increasing sleep duration may help reduce cardiometabolic risk--or the risk of heart disease and metabolic disorders-- in individuals who do not get enough sleep, according to an analysis of all published studies on the topic.

The Journal of Sleep Research analysis, which was led by researchers at the University of Cape Town, South Africa, included seven studies that aimed to increase sleep duration in adults by any sleep extension intervention. These studies had a combined number of 138 participants who were either healthy, healthy short-sleeping, overweight short-sleeping, or pre- or hypertensive short-sleeping individuals. The durations of the sleep extension interventions ranged from three days to six weeks and all successfully increased total sleep time by between 21 and 177 minutes.

Sleep extension was associated with improved measures of insulin sensitivity and reductions in overall appetite, desire for sweet and salty foods, intake of daily free sugar, and percentage of daily caloric intake from protein.

"Given the overwhelming evidence that sleeping less than seven hours is associated with an increased cardiometabolic risk, it is surprising that so few studies have explored whether extending sleep duration can lower cardiometabolic risk," said lead author Rob Henst, a PhD candidate. He noted that this review highlights the need for such studies and provides direction for future study designs.

"Although we have focused on studies with sleep extension interventions in this review, it is now apparent that poor sleep quality may be an equally important risk factor for cardiometabolic disease," added senior author Dr. Dale Rae. "Thus future studies testing interventions aimed at improving sleep quality are also required."

Irvine, Calif., June 5, 2019 -- A nanotechnology treatment derived from bone marrow stem cells has reversed multiple sclerosis symptoms in mice and could eventually be used to help humans, according to a new study led by University of California, Irvine researchers.

"Until now, stem cell therapies for autoimmune and neurodegenerative diseases have produced mixed results in clinical trials, partly because we don't know how the treatments work," said corresponding author Weian Zhao, an associate professor of pharmaceutical sciences and biomedical engineering who is affiliated with the Sue & Bill Gross Stem Cell Research Center. "This study helps unravel that mystery and paves the way for testing with human patients."

In past experiments, intravenously injected stem cells - taken from bone marrow and activated with interferon gamma, an immune system protein - often got trapped in filter organs before reaching their target. For this study, published in the journal ACS Nano, researchers avoided that problem by extracting nano-sized particles called exosomes from the stem cells and injecting them into rodents with MS.

Loaded with anti-inflammatory and neuroprotective RNA and protein molecules, the exosomes were able to slip through the blood-spinal cord barrier. In addition to rejuvenating lost motor skills and decreasing nerve damage caused by MS, they normalized the subjects' immune systems, something conventional drugs can't do, said study co-lead author Reza Mohammadi, a UCI doctoral candidate in materials science & engineering.

More experiments are in the pipeline.

"This novel treatment will be tested on humans in early 2020, initially on people with Type 1 diabetes," said co-lead author Milad Riazifar, who worked on the study as a pharmacological sciences doctoral student in Zhao's lab and is currently helping prepare for a City of Hope clinical trial of the method. "If successful, it could pave the way for treating other autoimmune diseases, including multiple sclerosis."

Other UCI researchers involved were Egest J. Pone, Aude I. Segaliny, Laura L. McIntyre, Ashley Hamamoto, Erika N. Calle, Wenbin Liao, Victor Pham, Jayapriya Jayaraman, Jonathan R.T. Lakey and Craig M. Walsh. Support was provided by the National Institutes of Health, a National Institute of Neurological Disorders and Stroke training grant, an Otto W. Shaler Scholarship and France's ARC Foundation for Cancer Research.

Earlier in the week, NOAA's National Hurricane Center was monitoring a low-pressure system in the Gulf of Campeche that has now moved along the Texas and Louisiana coastlines, bringing heavy rainfall. On June 5, NASA used a constellation of satellites to estimate that rainfall.

On June 5, the National Weather Service National Prediction Center in College Park, Maryland noted that there is a "High risk for flash flooding across parts of southeast Texas and southern Louisiana Today into Tonight."

Estimating Heavy Rainfall

Forming in the Bay of Campeche on June 3, tropical disturbance 91L looked ripe to develop into a minor tropical cyclone before making landfall along the Gulf Coast of Texas, but high wind shear inhibited its development. On June 4, the National Hurricane Center dropped the chances that it would consolidate into a depression to 20 percent. On June 5, although the low-pressure area is expected to remain disorganized, it is expected to generate a lot of rainfall for the Gulf coast states.

"NASA's IMERG data showed the tropical rainfall it brought has led to flash flooding throughout the Houston area on the morning of June 5, dumping more than 10 inches on a large region southwest of the city," said Matt Lammers of NASA's Goddard Space Flight Center in Greenbelt, Maryland.

The Integrated Multi-satellitE Retrievals for GPM (IMERG) creates a merged precipitation product from the Global Precipitation Measurement mission or GPM constellation of satellites. At NASA Goddard an IMERG rainfall accumulation image was created from June 3 at 0000 UTC (June 2 at 8 p.m. EDT) to June 5 at 5:30 a.m. EDT (0930 UTC). Most of the precipitation in the Houston area has fallen since the latest IMERG Early processing, so rainfall totals will be higher.

The National Weather Service noted that the moisture interacting with an upper level low moving into the Southern Plains. Heavy to excessive rainfall is likely across southeast Texas and into the Lower Mississippi Valley today, with a high risk for flash flooding where as much as 4 to 7 plus inches more of rain is in the forecast from extreme southeast Texas into southwest Louisiana.

What Is NASA's IMERG?

NASA's GPM or Global Precipitation Measurement mission satellite provides information on precipitation from its orbit in space. GPM is a joint mission between NASA and the Japan Aerospace Exploration Agency or JAXA. GPM also utilizes a constellation of other satellites to provide a global analysis of precipitation that are used in the IMERG calculation.

At NASA's Goddard Space Flight Center in Greenbelt, Maryland, those data are incorporated into NASA's IMERG or Integrated Multi-satellitE Retrievals for GPM. IMERG is used to estimate precipitation from a combination of passive microwave sensors, including the Global Precipitation Measurement (GPM) mission's core satellite's GMI microwave sensor and geostationary IR (infrared) data. IMERG real-time data are generated by NASA's Precipitation Processing System every half hour and are normally available within six hours.

IMERG creates a merged precipitation product from the GPM constellation of satellites. These satellites include DMSPs from the U.S. Department of Defense, GCOM-W from the Japan Aerospace Exploration Agency (JAXA), Megha-Tropiques from the Centre National D'etudies Spatiales (CNES) and Indian Space Research Organization (ISRO), NOAA series from the National Oceanic and Atmospheric Administration (NOAA), Suomi-NPP from NOAA-NASA, and MetOps from the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT).  All of the instruments (radiometers) onboard the constellation partners are inter-calibrated with information from the GPM Core Observatory's GPM Microwave Imager (GMI) and Dual-frequency Precipitation Radar (DPR).

Flood Watches

There is a moderate to high risk for flash flooding across parts of southeast Texas and southern Louisiana on Wednesday, June 5.

The National Weather Service in Houston/Galveston, Texas noted, "Numerous showers and thunderstorms are expected today. Rainfall will be locally heavy at times. A Flash Flood Watch is in effect through this evening. Rainfall totals will average 3 to 5 inches with isolated totals approaching 8 inches. Strong onshore winds will will produce elevated tides today and water levels at high tide could exceed 3.5 feet. Minor coastal flooding will be possible and a Coastal Flood Advisory is in effect.

Movement of the Weather System

The National Weather Service noted that "heavy to excessive rainfall threat shifts from the lower Mississippi Valley on Wednesday into the Central Gulf Coast states and eventually the U.S. Southeast by the end of the week." For updated forecasts, visit: http://www.weather.gov

Creating a municipally funded team to provide intensive services to chronically homeless people who use a large amount of public services can help the individuals get off the streets, while also reducing spending on services such as police services and emergency medical care, according to a new RAND Corporation study.

Examining a program aimed at a small group of chronically homeless people in Santa Monica, the study found that the locally focused effort succeeded in getting most of the residents into housing and reduced their use of public services, offsetting city spending on the program by 17% to 43%.

However, only one of the 26 people targeted by the program became stable enough to transition into less-intensive care, which is a key challenge facing the effort.

"Large cities such as Los Angeles and New York have created efforts to target individuals who are chronically homeless, but it's unique for a relatively small city such as Santa Monica to undertake such an effort," said Scott Ashwood, the study's lead author and a policy researcher at RAND, a nonprofit research organization. "We found the effort had positive impact on the clients and that the community views it as a valuable resource."

In 2016 the City of Santa Monica created its Homeless Multidisciplinary Street Team, a group of specialists who locate and engage homeless individuals in the city who most-frequently use city services. The goal was to help the people obtain housing and address their other needs, including mental health and substance use disorders.

Santa Monica has long had a large homeless population, potentially attracted by the city's policies and its seaside location. While Los Angeles County has the nation's highest rate of unsheltered homelessness, Santa Monica is one of the focal points where large numbers of the homeless gather. The number of homeless living in the city was estimated to be 905 in 2018.

City officials realized that a small number of homeless residents generated a large number of complaints about disruptiveness and frequently used municipal services. Most of the individuals have lived in the community for years and are well known to both residents and first responders.

The city's Homeless Street Team includes a program manager, a wellness case manager, a housing case manager and a substance abuse case manager. There also is a physician, psychiatrist, physician's assistant and peer support specialist who spend time with the program.

The team tries to see each of the targeted homeless residents at least twice a week, with many being seen almost daily. Team members worked for weeks or months to gain the trust of the homeless residents, using a light touch to build relationships in order to convince them to accept housing and services.

The RAND evaluation found that the program's greatest challenge is graduating clients to other support programs. The city originally had hoped to serve a new set of 25 clients each year.

Client graduation is complicated by the difficulty of finding appropriate follow-up programs for the population. Even after they are housed, the participants still require regular home visits, as well as intensive mental health and substance abuse prevention support.

"This is a very difficult population both to convince to receive services and then to manage their many needs on an ongoing basis," Ashwood said. "There has been a shortage of services in Los Angeles County for homeless people who have this high level of needs."

Santa Monica invested $600,000 in the program during its first year. The RAND study estimates that the decreased encounters between the chronically homeless and public service providers offset between 17% and 43% of the money invested in the team.

"There are likely to be many other financial and nonfinancial benefits associated with the program that were outside what we could quantify so we believe our estimates are conservative," Ashwood said.

Among the recommendations made by RAND researchers is that the program coordinate earlier with potential step-down providers to improve the ability to hand off clients to other programs when appropriate.

In addition, the program should collect more information about the potential benefits of the effort, including from providers outside the city of Santa Monica and should track a broader array of outcomes.

A team of researchers encoded their specialized knowledge into the computer game Foldit to enable citizen scientists to successfully design synthetic proteins for the first time.

The initial results of this collaboration appear in the June 5 issue of Nature. The Institute for Protein Design at the University of Washington School of Medicine led the multi-institutional effort.

"There are more possible proteins than there are atoms in the universe. It's exciting to think that now anyone can help explore this vast space of possibilities," said senior co-author David Baker, professor of biochemistry at the UW School of Medicine and director of the Institute for Protein Design.

"The diversity of molecules that these gamers came up with is astonishing," said lead author Brian Koepnick, postdoctoral researcher at the Institute for Protein Design. "These new proteins are by no means inferior to the stuff a PhD-level scientist might make."

Foldit was created in 2008 as a way to 'gamify' protein research. Proteins are essential biomolecules found inside every cell of every organism. Their intricate three-dimensional structures give rise to their diverse functions, which include digestion, wound healing, autoimmunity and much more.

Through gameplay, Foldit players have helped determine the structure of an HIV-related protein and improved the activity of useful enzymes. Until now, however, Foldit players could interact only with proteins that already existed. There was no way to design new ones.

"Designing completely new proteins that didn't exist in nature has been our goal with Foldit for a long time," said senior co-author Seth Cooper, assistant professor in the Khoury College of Computer Sciences at Northeastern University. "This new set of results shows that it's possible."

To turn Foldit into a platform for protein design, the researchers encoded biochemical knowledge into the game. That way, designer molecules that scored well in Foldit would be more likely to fold up as intended in the real world.

"We didn't give [Foldit players] any lectures or tell them to read anything. Instead, we tweaked the code that has run the game over many years," said senior co-author Firas Khatib, assistant professor of computer science at the University of Massachusetts Dartmouth.

The scientists tested 146 proteins designed by Foldit players in the laboratory. 56 were found to be stable. This finding suggested the gamers had produced some realistic proteins. The researchers collected enough data on four of these new molecules to show that the designs adopted their intended structures.

"I never would have believed they would get that good, but Foldit players never cease to amaze us." said Khatib.

Crafting new proteins is a bit like trying to tie never-before-seen knots using rope that is a million times thinner than a human hair. To date, only a small group of experts with intimate knowledge of the way biomolecules twist and turn bothered with this exceedingly complex task. Most use automated molecular design algorithms, and most design algorithms fail far more often than they succeed.

"We are always trying to make the algorithms better, but the human element is key," said Khatib. "In fact, through Foldit design, players have even discovered flaws in the Rosetta energy function -- our state-of-the-art method for protein design."

Protein design is an emerging scientific discipline. In the past five years, experts at the Institute for Protein Design and their colleagues have created proteins that stimulate the immune system to fight cancer and others that act as potent vaccine candidates. In April, the Institute for Protein Design received a commitment of $45 million in funding through The Audacious Project, a philanthropic collaborative organized by TED, to design protein-based vaccines, medicines and materials.

Could gamers create the next blockbuster drug?

"Foldit players are a new addition to the research arsenal," said Khatib. "They're not a silver bullet, but they are an amazing resource."

The first humans in North America arrived from Asia some time before 14,500 years ago. The next major stream of gene flow came about 5000 years ago, and is known to archaeologists as Paleo-Eskimos. About 800 years ago, the ancestors of the present-day Inuit and Yup'ik people replaced this population across the Arctic. By about 700 years ago, the archaeological evidence for the Paleo-Eskimo culture disappeared. Their genetic legacy in living populations has been contentious, with several genetic studies arguing that they made little contribution to later North Americans.

In the current study, researchers generated genome-wide data from 48 ancient individuals and 93 modern individuals from Siberia, Alaska, the Aleutian Islands and Canada, and compared this with previously published data. The researchers used novel analysis methods to create a comprehensive model of population history that included many ancient and modern groups to determine how they might be related to each other. "Our study is unique, not only in that it greatly expands the number of ancient genomes from this region, but because it is the first study to comprehensively describe all of these populations in one single coherent model," states Stephan Schiffels of the Max Planck Institute for the Science of Human History.

Paleo-Eskimos left a lasting legacy that extends across North America

The researchers were able to show that a substantial proportion of the genetic heritage of all ancient and modern American Arctic and Chukotkan populations comes from Paleo-Eskimos. This includes people speaking Eskimo-Aleut languages, such as the Yup'ik, Inuit and Aleuts, and groups speaking Na-Dene languages, such as Athabaskan and Tlingit speakers, in Canada, Alaska, and the lower 48 states of the United States.

Based on the researchers' analysis, Paleo-Eskimos interbred with people with ancestry similar to more southern Native peoples shortly after their arrival to Alaska, between 5,000 and 4,000 years ago. The ancestors of Aleutian Islanders and Athabaskans derive their genetic heritage directly from the ancient mixture between these two groups. The researchers also found that the ancestors of the Inuit and Yup'ik people crossed the Bering Strait at least three times: first as Paleo-Eskimos to Alaska, second as predecessors of the Old Bering Sea archaeological culture back to Chukotka, and third to Alaska again as bearers of the Thule culture. During their stay in Chukotka that likely lasted for more than 1000 years, Yupik and Inuit ancestors also admixed with local groups related to present-day Chukchi and local peoples from Kamchatka.

Paleo-Eskimo ancestry is particularly widespread today in Na-Dene language speakers, which includes Athabaskan and Tlingit communities from Alaska and northern Canada, the West Coast of the United States, and the southwest United States.

"For the last seven years, there has been a debate about whether Paleo-Eskimos contributed genetically to people living in North America today; our study resolves this debate and furthermore supports the theory that Paleo-Eskimos spread Na-Dene languages," explains David Reich of Harvard Medical School and the Howard Hughes Medical Institute. "One of the most striking case examples from our study is the ancient DNA we generated from the ancient Athabaskan site of Tochak McGrath in interior Alaska, where we worked in consultation with the local community to obtain data from three approximately seven hundred year old individuals. We found that these individuals, who lived after the time when the Paleo-Eskimo archaeological culture disappeared across North America, are well modeled as a mixture of the same two ancestry components as those found in Athabaskans today, and derived more than 40% of their ancestry from Paleo-Eskimos.

A case example for how genetics can be combined with archaeology to shed new light on the past

The researchers hope that the paper will provide an example of the value of genetic data, in the context of archaeological knowledge, to resolve long-standing questions.

"Determining what happened to this population was not possible from the archaeological record alone," explains Pavel Flegontov of the University of Ostrava. "By analyzing genetic data in concert with the archaeological data, we can meaningfully improve our understanding of the prehistory of peoples of this region. We faced challenging analytical problems due to the complex sequence of gene flows that have shaped ancestries of peoples on both sides of the Bering Strait. Reconstructing this sequence of events required new modelling approaches that we hope may be useful for solving similar problems in other regions of the world."

Earth's outer layer is composed of giant plates that grind together, sliding past or dipping beneath one another, giving rise to earthquakes and volcanoes. These plates also separate at undersea mountain ridges, where molten rock spreads from the centers of ocean basins.

But this was not always the case. Early in Earth's history, the planet was covered by a single shell dotted with volcanoes--much like the surface of Venus today. As Earth cooled, this shell began to fold and crack, eventually creating Earth's system of plate tectonics.

According to new research, the transition to plate tectonics started with the help of lubricating sediments, scraped by glaciers from the slopes of Earth's first continents. As these sediments collected along the world's young coastlines, they helped to accelerate the motion of newly formed subduction faults, where a thinner oceanic plate dips beneath a thicker continental plate.

The new study, published June 6, 2019 in the journal Nature, is the first to suggest a role for sediments in the emergence and evolution of global plate tectonics. Michael Brown, a professor of geology at the University of Maryland, co-authored the research paper with Stephan Sobolev, a professor of geodynamics at the GFZ German Research Centre for Geosciences in Potsdam.

The findings suggest that sediment lubrication controls the rate at which Earth's crust grinds and churns. Sobolev and Brown found that two major periods of worldwide glaciation, which resulted in massive deposits of glacier-scrubbed sediment, each likely caused a subsequent boost in the global rate of plate tectonics.

The most recent such episode followed the "snowball Earth" that ended sometime around 635 million years ago, resulting in Earth's modern plate tectonic system.

"Earth hasn't always had plate tectonics and it hasn't always progressed at the same pace," Brown said. "It's gone through at least two periods of acceleration. There's evidence to suggest that tectonics also slowed to a relative crawl for nearly a billion years. In each case, we found a connection with the relative abundance--or scarcity--of glacial sediments."

Just as a machine needs grease to keep its parts moving freely, plate tectonics operates more efficiently with lubrication. While it may be hard to confuse the gritty consistency of clay, silt, sand and gravel with a slippery grease, the effect is largely the same at the continental scale, in the ocean trenches where tectonic plates meet.

"The same dynamic exists when drilling Earth's crust. You have to use mud--a very fine clay mixed with water or oil--because water or oil alone won't work as well," Brown said. "The mud particles help reduce friction on the drill bit. Our results suggest that tectonic plates also need this type of lubrication to keep moving."

Previous research on the western coast of South America was the first to identify a relationship between sediment lubrication and friction along a subduction fault. Off the coast of northern Chile, a relative lack of sediment in the fault trench creates high friction as the oceanic Nazca plate dips beneath the continental South America plate. This friction helped to push the highest peaks of the central Andes Mountains skyward as the continental plate squashed and deformed.

In contrast, further south there is a higher sediment load in the trench, resulting in less friction. This caused less deformation of the continental plate and, consequently, created smaller mountain peaks. But these findings were limited to one geographic area.

For their study, Sobolev and Brown used a geodynamic model of plate tectonics to simulate the effect of sediment lubrication on the rate of subduction. To verify their hypothesis, they checked for correlations between known periods of widespread glaciation and previously published data that indicate the presence of continental sediment in the oceans and trenches. For this step, Sobolev and Brown relied on two primary lines of evidence: the chemical signature of the influence of continental sediments on the chemistry of the oceans and indicators of sediment contamination in subduction-related volcanoes, much like those that make up today's "ring of fire" around the Pacific Ocean.

According to Sobolev and Brown's analysis, plate tectonics likely emerged on Earth between 3 and 2.5 billion years ago, around the time when Earth's first continents began to form. This time frame also coincides with the planet's first continental glaciation.

A major boost in plate tectonics then occurred between 2.2 to 1.8 billion years ago, following another global ice age that scrubbed massive amounts of sediments into the fault trenches at the edges of the continents.

The next billion years, from 1.75 billion to 750 million years ago, saw a global reduction in the rate of plate tectonics. This stage of Earth's history was so sedate, comparatively speaking, that it earned the nickname "the boring billion" among geologists.

Later, following the global "snowball Earth" glaciation that ended roughly 635 million years ago, the largest surface erosion event in Earth's history may have scrubbed more than a vertical mile of thickness from the surface of the continents. According to Sobolev and Brown, when these sediments reached the oceans, they kick-started the modern phase of active plate tectonics.

Researchers have demonstrated that vehicle armor using composite metal foam (CMF) can stop ball and armor-piercing .50 caliber rounds as well as conventional steel armor, even though it weighs less than half as much. The finding means that vehicle designers will be able to develop lighter military vehicles without sacrificing safety, or can improve protection without making vehicles heavier.

CMF is a foam that consists of hollow, metallic spheres - made of materials such as stainless steel or titanium - embedded in a metallic matrix made of steel, titanium, aluminum or other metallic alloys. In this study, the researchers used steel-steel CMF, meaning that both the spheres and the matrix were made of steel.

For the study, researchers manufactured a hard armor system consisting of a ceramic faceplate, a CMF core and a thin back plate made of aluminum. The armor was tested using .50 caliber ball and armor-piercing rounds. The armor was tested with the rounds being fired at impact velocities from 500 meters per second up to 885 meters per second.

The CMF layer of the armor was able to absorb 72-75% of the kinetic energy of the ball rounds, and 68-78% of the kinetic energy of the armor-piercing rounds.

"The CMF armor was less than half the weight of the rolled homogeneous steel armor needed to achieve the same level of protection," says Afsaneh Rabiei, corresponding author of a paper on the work and a professor of mechanical and aerospace engineering at North Carolina State University. Rabiei, the inventor of CMF, has spent years developing and testing CMF materials.

"In other words, we were able to achieve significant weight savings - which benefits vehicle performance and fuel efficiency - without sacrificing protection," Rabiei says.

"This work shows that CMF can offer a significant advantage for vehicle armor, but there is still room for improvement," Rabiei says. "These findings stem from testing armors we made by simply combining steel-steel CMF with off-the-shelf ceramic face plates, aluminum back plate and adhesive material. We only optimized our CMF material and replaced the steel plate in standard vehicle armor with steel-steel CMF armor. There is additional work we could do to make it even better. For example, we would like to optimize the adhesion and thickness of the ceramic, CMF and aluminum layers, which may lead to even lower total weight and improved efficiency of the final armor."

In previous work, Rabiei and her collaborators demonstrated that CMF could block blast pressure and fragmentation at 5,000 feet per second from high explosive incendiary rounds detonating only 18 inches away. Her team also showed that CMF could stop a 7.62 x 63 millimeter M2 armor piercing projectile at a total thickness of less than an inch, while the indentation on the back was less than 8 millimeters. For context, the National Institute of Justice standard allows up to 44 millimeters indentation in the back of armor.

In addition, Rabiei's group has shown that CMFs, in addition to being lightweight, are very effective at shielding X-rays, gamma rays and neutron radiation - and can handle fire and heat twice as well as the plain metals they are made of.

"In short, CMFs hold promise for a variety of applications: from space exploration to shipping nuclear waste, explosives and hazardous materials, to military and security applications and even cars, buses and trains," Rabiei says.

The new paper, "Ballistic Performance of Composite Metal Foam against Large Caliber Threats," is published in the journal Composite Structures. First author of the paper is Jacob Marx, a Ph.D. student at NC State. The paper was co-authored by Marc Portanova of the Aviation Development Directorate in the U.S. Army Combat Capabilities Development Command.