Culture

A lithium-ion battery that is safe, has high power and can last for 1 million miles has been developed by a team in Penn State's Battery and Energy Storage Technology (BEST) Center.

Electric vehicle batteries typically require a tradeoff between safety and energy density. If the battery has high energy and power density, which is required for uphill driving or merging on the freeway, then there is a chance the battery can catch fire or explode in the wrong conditions. But materials that have low energy/power density, and therefore high safety, tend to have poor performance. There is no material that satisfies both. For that reason, battery engineers opt for performance over safety.

"In this work we decided we were going to take a totally different approach," said Chao-Yang Wang, professor of mechanical, chemical and materials science and engineering, and William E. Diefenderfer Chair in Mechanical Engineering, Penn State. "We divided our strategy into two steps. First we wanted to build a highly stable battery with highly stable materials."

Their second step was to introduce instant heating. About four years ago, Wang developed a self-heating battery to overcome the problem of poor performance in cold climates. The battery uses an electric current to heat up in seconds compared to the hours an external heater required. By heating the battery from room temperature to around 140 degrees Fahrenheit -- 60 degrees Celsius -- the battery gets an instant boost in reactivity because the law of kinetics is that reactivity increases exponentially with temperature.

"With these two steps I can get high safety when the battery is not being used and high power when it is," he said.

The self-heating battery, called the All Climate battery, has been adopted by several car companies, including BMW, and was chosen to power a fleet of 10,000 vehicles that will be used to ferry people between venues at the next Winter Olympics in Beijing.

The BEST Center tests the safety of the battery using nail penetration equipment. They drive the nail into the cell causing short circuiting. They then monitor the cell for temperature and voltage. The difference in temperature for the passivated cell was 212 degrees F -- 100 degrees C --compared to a standard battery cell which was 1,832 degrees F -- 1000 degrees C, an enormous improvement.

Because their batteries are built using stable materials, they have a long cycle life. Even at 140 degrees F, their cycle number is over 4000, which translates to over a million miles.

The team's next project will be to develop a solid-state battery, which will likely require heating as well.

The current work appears in the journal Science Advances and is titled "A new approach to both safety and high performance of lithium-ion batteries." Wang's coauthors are research assistant professors Shanhai Ge, Yongjun Leng and Xiao-Guang Yang, and doctoral students Teng Liu, Ryan Longchamps, Yue Gao and Daiwei Wang. Donghai Wang, professor of mechanical and of chemical engineering, Penn State, also participated in this work.

The Department of Energy funded this work.

In a recent study, scientists at Baycrest's Rotman Research Institute (RRI) found that research participants moved their eyes to determine whether they had seen an image before, and that their eye movement patterns could predict mistakes in memory. They obtained these results using an innovative new eye tracking technique they developed.

"Our findings indicate that eye movements play a functional role in memory retrieval," says Dr. Jennifer Ryan, senior scientist at the RRI and Canada Research Chair in Cognitive Neuroscience of Memory. "They can tell us a lot about someone's memory."

This study builds on previous Baycrest research examining the link between eye movements and memory, including the role of our eye movements in memorization and the weakening connection between our eye movements and our brain activity as we age.

"When we see a picture, a face or something else that we have already seen, our eyes tend to look at the same locations as they did the first time. The brain compares important characteristics of what we are seeing to a mental picture in our memory, and it identifies the two as the same," says Dr. Bradley Buchsbaum, senior scientist at the RRI. "The brain is pretty good at this, even in conditions of lower visibility."

"If we see someone in the distance, or if their face is partially hidden by branches, our brain will compare the features that are visible to a mental picture to determine whether we know that person," says Jordana Wynn, lead researcher on this study, former PhD student at the RRI and current fellow at Harvard University.

This phenomenon is called "pattern completion." When it goes wrong, we may end up mistakenly waving to a stranger if he or she has similar hair or a similar nose to someone we know.

In this study, published in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS), participants were first asked to memorize a series of 30 new images on a screen. Next, they viewed another series, this time containing both some of the previously seen images and some new-but-similar images. They were then asked to indicate whether they had seen each one before. Their eye movements were tracked during both stages. Each image was shown briefly, ranging from 250 milliseconds to 750 milliseconds, before the participants were instructed to visualize it while looking at a blank screen.

Participants were highly accurate in identifying previously seen images as old, scoring almost 90%. They were more likely to be correct if their eye movements were the same as when they initially saw the image. On the other hand, they performed less well, at 70%, when faced with a new-but-similar image. In the latter case, the more participants repeated their initial viewing pattern instead of focusing on the different aspects of the image, the more likely they were to incorrectly identify the image as old.

To emulate real-world situations where we don't have full information, the researchers also used incomplete, or "degraded," versions of images. This ranged from 0 to 80% degradation, in the form of grey squares covering parts of the image. Remarkably, even when the image was 80% degraded, performance was much better than pure guessing, reflecting the strength of pattern completion.

"Using our eye tracking technique, we were able to map the participants' eye movements and observe that they were mentally picturing an image that they could not see," says Wynn. "They were using pattern completion."

Many studies have examined pattern completion over the past decades, but with one critical weakness. "These studies have all been based on the untested assumption that we can infer pattern completion is happening when participants mistakenly 'recognize' images that they have not seen before," says Wynn. "Our study is the first to use eye movement analysis, rather than behaviour, to show that people are in fact retrieving a memory of an old image when they make this mistake."

This study's findings have important implications in terms of assessing memory. "Some of the traditional tests used to diagnose memory impairments are quite verbal," says Dr. Ryan. "They often require good command of the English language, which can be a problem in a multicultural city like Toronto."

"With eye tracking, you don't have to ask people what they remember. You can just look at their eyes. This gives us a lot more information about their memory than we thought," says Dr. Buchsbaum.

This work was made possible with support from the Canadian Institutes of Health Research (CIHR) and the Natural Sciences and Engineering Research Council of Canada (NSERC).

With additional funding, the researchers could further examine the role of eye movements in memory retrieval. "This could lead to the development of better screening tools for dementia, which is the ultimate hope," says Dr. Ryan.

A new study links being overweight in middle age and later adulthood to a greater risk of advanced prostate cancer. Jeanine Genkinger, PhD, an epidemiologist at Columbia University Mailman School of Public Health, and colleagues published the study in Annals of Oncology, the journal of the European Society for Medical Oncology and Japanese Society of Medical Oncology.

Prostate cancer is the second most common cause of cancer in men in the United States. Fewer than one in three men with advanced prostate cancer live five years beyond diagnosis.

Before this study, only a few studies examined contributing factors to advanced prostate cancer. There was an especially noticeable lack of research on the linkage between factors like weight in early adulthood, changes in weight during adulthood, and waist circumference, specifically with advanced prostate cancer risk.

Using data from 15 large studies combined together, Genkinger examined associations between body fat, height, and prostate cancer risk in 830,772 men, 51,734 of whom had been diagnosed with prostate cancer. Her study took a life-course-based approach, examining survey data collected across respondents' lifespans to determine whether and at what age during adulthood excess body fat increased risk for advanced prostate cancer. The researchers found that a BMI elevated above a healthy weight during middle to late adulthood--median age range from 50 to 64--was linked to the greatest risk for developing advanced prostate cancer. A "healthy" weight is defined as a BMI between 21 and 25 kg/m2.

They also found that greater waist circumference was linked with increased risk of advanced prostate cancer and death. Although other studies have linked higher BMI with increased prostate cancer, this is the first study to find a positive association with waist circumference.

"These study results show that risk for advanced prostate cancer can be decreased by maintaining a 'healthy' weight, which is in line with guidelines by the American Cancer Society and World Cancer Research Fund. Adopting healthy eating and exercising are factors that can help maintain a healthy weight," says Genkinger, associate professor of epidemiology at Columbia Mailman School. "This study shows that adopting and maintaining healthy weight in middle to late adulthood can especially reduce risk of advanced prostate cancer."

EAST LANSING, Mich. - Nearly 30% of the $3.6 trillion spent on health care costs in the United States is wasted. New research from Michigan State University and Rutgers University reveals the amount of money washed away in hospital operating rooms, offering solutions to save hospitals - and the country - millions of dollars each year.

The paper, published in the Journal of Operations Management, found that five to 10 minutes were added to each surgery due to unplanned supplies. Additionally, an average $1,800 per surgery - nearly $28 million annually - could be saved by more frequently planning the supplies needed for a surgery.

"This problem is due to the fact that quality of care has always taken precedence over cost -- and rightly so," said Anand Nair, professor of operations and supply chain management. "However, with increasing pressure on health care organizations, they are trying to find ways to jointly increase quality and reduce costs."

Nair - along with co-authors David Dreyfus, assistant professor at Rutgers Business School and alumnus of MSU's doctoral program, and Claudia Rosales, assistant professor of supply chain management at MSU - found that not only do unplanned costs affect a hospital's bottom line, but they can also endanger patients under anesthesia with potentially harmful complications.

The team spent more than 250 hours observing hospital operating rooms, taking note of processes, preparation and performance of 92 surgeries. Ultimately, they found that the greatest issue stems from a lack of standardization for the planning processes.

"In most hospitals, every surgeon is allowed to make their own decisions in terms of equipment and supplies," Nair said. "Surgeons are comfortable using certain supplies due to their past experiences; this increases the variance among items and the number of items that hospitals need to carry in inventory."

Surgeons request equipment and supplies they need on what's called a physician preference card, or PPC.

With different surgeons requesting preferred equipment for procedures, hospitals end up fulfilling multiple personalized requests, Nair explained. Additionally, without a standardized planning process, teams must address supply shortages during surgery, which can reduce quality, increase costs and present possibilities of potential security lapses.

"If a doctor doesn't have what they immediately need, a surgical team member must find it, which becomes an unplanned cost - and potentially a health risk if they leave the area," Nair said. "On the other hand, if a surgeon requests something that isn't necessary for the surgery, it's simply a waste of money."

Nair explained that some surgeons err on the side of caution and carry supplies in case they might be needed. While this is important given the critical nature of surgeries, a more standardized use of PPCs - along with audits of what supplies are on them - will allow hospitals to reduce redundancies.

Nair explained that minor changes in processes can add up to big savings.

"Managing medical supplies is a critical aspect of the health care supply chain," Nair said.

"Mechanisms need to be put in place to provide more learning opportunities from such operational failures for long-term benefits to happen."

Another complication in hospital rooms is that surgical teams change often, which makes it difficult to communicate which supplies on the PPC aren't consistently used. Open communication among surgical teams helps anticipate needs and reduces unplanned costs in a surgery.

The researchers acknowledge that savings aren't always immediate, but that progress happens along the way during any procedure.

"Our research should encourage hospitals to embrace systems that can better track unplanned costs and plan ahead," Nair said. "Hospitals should explore methods to incentivize surgeons to plan more often. This may be achieved by providing visibility about unplanned costs and workarounds, offering greater control on administering supplies and rewarding for unplanned cost reduction."

ITHACA, N.Y. - "Scooter clutter" has been a concern amplified by media reports in urban areas where micromobility has entered the landscape, with large numbers of dockless scooters and shared e-bikes on city streets and sidewalks. But a recent study finds that motor vehicles are still the main offender by far when it comes to blocking access by other travelers.

Research co-authored by Nicholas Klein, assistant professor of city and regional planning at Cornell University, offers data on the impacts of scooters and bikeshare vehicles in five American cities.

The research is translatable and replicable, to help inform cities' efforts in reimagining public streets and sidewalks. Some cities are considering new parking regulations and seeking other planning and policy solutions for these shared scooters and bikes, which have been introduced to more than 100 cities since 2018.

A paper, published in Transportation Research Interdisciplinary Perspectives, investigated scooter, bike and car parking behavior in Austin, Texas; Portland, Oregon; San Francisco and Santa Monica, California; and Washington, D.C. The research was led by Anne Brown of the University of Oregon School of Planning, Public Policy and Management.

Researchers collected 3,666 observations of e-scooters, bikes, motor vehicles and "sidewalk objects" such as sandwich boards. Research assistants recorded parking behavior on both sides of a busy commercial corridor for three days, eight hours each day. They observed parked cars, scooters and bicycles, as well as sidewalk furniture including advertising, construction materials and sidewalk-mounted elevator or stair-access doors.

The study found that parking noncompliance rates across the five cities were far higher for motor vehicles (24.7% of 2,631 motor vehicles observed) than for micromobility vehicles (0.8% of 865 scooter and bike observations).

Food delivery and ride-hailing vehicles accounted for a disproportionate number of improper parking incidents impeding access or mobility for other travelers, Klein said. Most of these violations occurred while dropping off or picking up people or food, including double parking, occupying "No Parking" or restricted areas and blocking driveways.

The findings suggest that the presence of micromobility companies and other technology-enabled transportation services should motivate cities to rethink their parking policies, the researchers said.

LAWRENCE -- Some children in the U.S. grow up under severe disadvantage in terms of the amount and quality of language they are exposed to in their earliest years. Researchers have documented that some children are exposed to roughly 30 million fewer words than other children during years that are critical for learning language. Researchers call this the "word gap" and say it portends lifelong consequences.

"The word gap represents inequities in early experience with language that can place children at a disadvantage in terms of not only their early language and vocabulary development, but also literacy and school readiness," said Dale Walker, associate research professor and scientist at Juniper Gardens Children's Project and the Life Span Institute at the University of Kansas.

"When young children do not have sufficient opportunities to hear and practice language, they are less likely to develop vocabulary by age 3," Walker said. "That can lead not only to decreased language and social outcomes, but children are less likely to be ready to succeed in school. They begin school already at a disadvantage in terms of the vocabulary that they've been exposed to and can continue to fall behind in reading and in school achievement. And as noted by economists, that inequity can follow a child into adulthood in terms of educational opportunities and their earning potential."

Walker and Judith Carta, professor of special education at KU, recently guest-edited a special issue of the peer-reviewed Early Childhood Research Quarterly that brings together 18 language-intervention research and empirical studies that address the word gap.

"Understanding research evidence is necessary to inform education and intervention efforts to improve the language-learning experiences for young children and prevent the word gap," Walker said.

The research in the special issue covers interventions conducted with parents, educators and health care providers. Further, it includes cultural and linguistic diversity of study participants, as well as training and implementation practices, and the methodological factors informing intervention research.

Walker, who recently earned KU's Steven F. Warren Research Achievement Award, said she hoped research gathered in the special edition could be used by academics, early childhood educators, health care professionals and policymakers.

"We are encouraged about the potential of efforts to address the word gap and hope that our special issue on this topic can be used as a resource that can help inform future research, practice and prevention to close the word gap," she said.

COLUMBIA, Mo. - Self-inflicted injury, aggression toward others and yelling are common problem behaviors associated with young children diagnosed with autism spectrum disorder. These actions can result from the child being denied attention or access to items they enjoy, as well as from internal discomfort or environmental stressors such as noise or large crowds.

Now, a researcher at the University of Missouri has adjusted an existing treatment procedure aimed at reducing problem behaviors for children with autism spectrum disorder. Instead of traditional techniques, which require constant monitoring of the child, the new approach, which emphasizes momentary check-ins, provides more flexibility for parents and caregivers.

Kyle Hamilton, a behavior analyst at the Thompson Center for Autism and Neurodevelopmental Disorders, said that while existing intervention methods can be effective in controlled environments, they can be harder for busy parents, teachers and caregivers to implement in everyday situations.

Currently, experts advise parents to watch their children for long periods of time (up to several minutes) and give a reward only if the child's behavior is appropriate the entire time. However, a parent that is cooking dinner in the kitchen may not be able to simultaneously supervise children playing in a nearby room for long periods of time. With Hamilton's new approach, parents would only check their children periodically for a few seconds. If the child was behaving appropriately at the moment of the check, a small reward could be given.

"Rather than constantly monitoring the child, this new technique allows for periodic check-ins to see if the child is engaging in problem behaviors and reward them if we are seeing improvements," Hamilton said. "Through positive reinforcement, we can help reduce problem behaviors for kids with autism, which will allow them to be around their typically developing peers more often in society."

Given the broadness of the autism spectrum, these findings can lead to additional studies into which treatment options are most effective for reducing various problem behaviors. In addition to minimizing self-inflicted harm that can damage children's long-term health, reducing problem behaviors can help remove the social stigma that many kids with autism face.

"By reducing problem behaviors, we can help these kids spend more time in natural environments, whether that is at the grocery store, pool, restaurants or school," Hamilton said. "We want them to have every opportunity to live the most normal life possible and provide them more exposure to the natural world."

A "decoy" mechanism has been found in human and animal cells to protect them from potentially dangerous toxins released by foreign invaders, such as bacteria.

Scientists at NYU Grossman School of Medicine have found that cells exposed to bacteria release tiny, protein-coated packages called exosomes, which act like decoys to bind to bacterial toxins, including those produced by MRSA (methicillin-resistant Staphylococcus aureus), a bacterium that has become resistant to many antibiotics, or Corynebacterium diphtheriae (the bacterium responsible for highly contagious diphtheria).

Researchers say this "soaking up" of toxins neutralizes their action and helps keep cells safe. If left to move around freely, the toxins would normally bind to the cells' outer membranes, creating holes in those membranes and killing the cells.

Publishing in the journal Nature online March 4, the new study showed that bacteria-exposed cells died on their own but lived only when toxin-absorbing exosomes were present.

Researchers say their latest findings show that this cell defense system is common among mammals, including humans, and may help explain why as many as one-fifth of Americans have community-based MRSA bacteria on their body yet very few, no more than 1 in 10,000, die from infection by it.

"Exosomes act much like a sponge, preventing the toxins for a time from attacking the cell, while toxins that are not corralled are left to burrow through cell membranes," says study co-senior investigator Ken Cadwell, PhD. "This defense mechanism also buys some time for other widely recognized immune defenses, such as bacteria-attacking T cells, or antibodies, to kick in and fight the infection directly," adds Cadwell, an associate professor at NYU Langone Health and its Skirball Institute for Biomolecular Medicine.

Cadwell says many disease-carrying pathogens, such as bacteria and viruses, initially target cells' outer membranes, so the NYU team plans to investigate whether similar, generic "sponge-like" exosomes exist and take defensive action in other infections.

According to study co-senior investigator Victor J. Torres, PhD, the C.V. Starr Associate Professor of Microbiology at NYU Langone, the team's results not only add knowledge of mammalian defenses against infection, but also suggest new strategies for strengthening the immune system, either by injecting artificial, exosome-like vesicles into the body to soak up toxins or by boosting exosome production to ramp up the body's defenses.

The NYU researchers based their latest experiments on their previous work showing how bacterial toxins bind to cells during an infection. One earlier finding was that a specific protein called ATG16L1 was always present in cells that lived longer or survived infection. However, cells that lacked ATG16L1 all died from infection. ATG16L1, they say, is a known autophagy protein, acting as a key component in molecules involved in enveloping cellular waste so it can be broken down and disposed of. The researchers say the action of exosomes outside of cells "mirrors" this autophagy/ATG16L1 waste removal pathway observed inside cells.

For the new study, researchers injected MRSA into healthy mice and doubled how long and how many mice lived by fortifying the animals with injections of exosomes extracted from mice infected with the same bacterium. Normal mice injected with MRSA all died.

In other experiments in mice and human cells, when exosome production was chemically and/or genetically blocked, the cells all died, demonstrating to researchers the critical role played by these exosomes in cell survival.

DURHAM, N.C. -- An international team of researchers that pooled genetic samples from developmentally disabled patients from around the world has identified dozens of new mutations in a single gene that appears to be critical for brain development.

"This is important because there are a handful of genes that are recognized as 'hot spots' for mutations causing neurodevelopmental disorders," said lead author Debra Silver, an associate professor of molecular genetics and microbiology in the Duke School of Medicine. "This gene, DDX3X, is going to be added to that list now."

An analysis led by the Elliott Sherr lab at the University of California-San Francisco found that half of the DDX3X mutations in the 107 children studied caused a loss of function that made the gene stop working altogether, but the other half caused changes predicted to disrupt the function of the gene.

The DDX3X gene is carried by the X chromosome, which occurs twice in females and only once in males. Only three of the children in the study were male, indicating that an aberrant copy of the gene is probably most often a lethal problem for males who only have a single copy of X.

In humans, this syndrome often results in smaller brains and intellectual disability. Understanding how and why DDX3X mutations lead to developmental issues provides insight into how the gene functions normally.

With the finding that DDX3X was a common element in the developmental disabilities of these children, Silver's team "used a set of experimental tricks to see how it would lead to disease." In mice, her team manipulated levels of the gene to see how development of the cerebral cortex would be altered.

Changes in the gene led to fewer neurons being produced in a dosage-dependent manner, Silver said.

In the most severe cases, Sherr's team showed that functional changes in DDX3X resulted in a smaller or even completely missing corpus collosum, the broad communications structure between the two halves of the brain. In some cases, identical genetic spelling errors that occurred in several children also led to polymicrogyria, an abnormal folding pattern on the surface of the brain.

"Not every mutation acts the same," Silver said.

The collaborative team also tested how 'missense' mutations, in which the protein is made but somehow defective, would impair brain development. In the most severe missense mutations, the way protein was made was affected, leading to the formation of 'clumps' of RNA-protein aggregates in neural stem cells, similar to the protein clumps found in Alzheimer's disease, Silver said.

Together, these issues point to a role for DDX3X in the genesis of developing neurons as the brain grows. "The way neurons are made and organized is disrupted," Silver said. "We know that this gene is required for early brain development which can cause a whole host of developmental problems."

Almost all of the mutations seen in the study children were 'de novo,' meaning they happened during the child's early development, rather than being inherited from a parent.

Parents of the children with these mutations have established the DDX3X Foundation to pursue better understanding of what causes the disease, identify therapies, and provide a supportive community for families.

What The Study Did: Researchers examined associations between two of the most common weight-loss surgeries on type 2 diabetes outcomes by comparing diabetes remission and relapse rates, glycemic control and weight loss after five years among 9,700 adults with type 2 diabetes who had Roux-en-Y gastric bypass or sleeve gastrectomy.

Authors: Kathleen McTigue, M.D., of the University of Pittsburgh, is the corresponding author.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/ 

(doi:10.1001/jamasurg.2020.0087)

Editor's Note: The article includes conflict of interest and funding/support disclosures. Please see the articles for additional information, including other authors, author contributions and affiliations, conflicts of interest and financial disclosures, and funding and support.

The conclusions of a study carried out by Víctor Costumero, as the first author, Marco Calabria and Albert Costa (died in 2018), members of the Speech Production and Bilingualism (SPB) group at the Cognition and Brain Center (CBC) of the Department of Information Technology and the Communications (DTIC) of the UPF, together with researchers from the Universities of Jaume I, Valencia, Barcelona and Jaén; IDIBELL, Hospital La Fe (Valencia) and Grupo Médico ERESA (Valencia) show that bilingualism acts as a cognitive reserve factor against dementia. Lidón Marín, one of the authors of the article, states that "although sick bilinguals show a greater brain atrophy, the cognitive level among bilinguals and monolinguals is the same. The work has been published in the scientific journal Alzheimer's Research and Therapy with the title "A cross-sectional and longitudinal study on the protective effect of bilingualism against dementia using brain atrophy and cognitive measures". It has been financed by La Marató de TV3 Foundation.

The research has analysed a hundred patients with mild cognitive impairment who are bilingual and monolingual, with an average age of 73 years. Those people who use Catalan and Spanish alternately, regardless of the register, have been considered bilingual. Those people who do not use it indiscriminately although they know, understand and can use Catalan occasionally have been considered monolingual (or passive bilingual). César Ávila, director of the research group, explains that "the alternative use of these two languages (Catalan and Spanish) in any situation is complex at the cognitive level because there are many similarities between them".

At the beginning of the study, the two groups of patients showed the same level of cognitive impairment (language, memory, etc.). However, in the case of bilinguals, brain atrophy was greater than in the case of monolinguals. This fact implies the need for more brain injury load to show the same symptoms. The researchers have followed the evolution of the patients for seven months, in which they have been able to observe that the group of bilinguals has had a lower loss of brain volume and has better maintained their cognitive abilities. Researchers consider that "this explains that there is a cognitive reserve of bilingualism". These results are especially relevant because "this would be the first longitudinal evidence of this possible protective effect of bilingualism against dementia", indicates Ávila.

The study was carried out with patients from the General University Hospital of València and La Fe University and Polytechnic Hospital, with similar socio-demographic characteristics and educational levels. Previous data already indicated that bilingual people (of any language) take five years longer to reach dementia than monolingual people. However, one of the contributions of this study, in addition to comparing two different moments in time, has been to reveal that the mechanism that makes it so is the cognitive stimulation favoured by the alternation in use between one language and another. Although it is too early to apply the results obtained in treatments for dementia, "we do know that there are cognitive stimulation therapies that include practical exercises in the use of different languages", explains the researcher Victor Costumero.

In addition to the research group from Castelló, the study has also involved the Cognition and Brain Centre of the Pompeu Fabra University of Barcelona; the ERI se Lectura of the University of València; the ERESA Medical Group of València; the Department of Neurology of the General Hospital of València; the Neurology Unit of the University and Polytechnic Hospital La Fe; the Cognitive Processes Section of the Department of Cognition, Development and Educational Psychology of the University of Barcelona; the Cognition and Brain Plasticity Group of the Bellvitge Biomedical Research Institute (IDIBELL) of L'Hospitalet de Llobregat and the Department of Computer Science of the University of Jaén.

Exciton-based solid-state devices have the potential to be essential building blocks for modern information technology to slow down the end of Moore's law. Exploiting excitonic devices requires the ability to control the excitonic properties (e.g., exciton flow, exciton recombination rates or exciton energy) in an active medium. However, until now, the demonstrated techniques for excitonic control have either been inherently complex or sacrificed the operation speed, which is self-defeating and impractical for actual implementation. Hence, a scheme with an emphasis on all-optical control, bottom-up fabrication and self-assembly is highly desired for real-world applications.

In a new paper published in Light Science & Applications, scientists from the School of Electrical & Electronic Engineering, Nanyang Technological University, Singapore, developed a convenient way to control exciton flow between different colloidal quantum wells (CQWs) at room temperature, all through optical signals. Through the combination of stimulated emission and Förster resonance energy transfer (FRET), the flow of excitons between donor Cadium selenide (CdSe) core-only CQWs and acceptor CdS/CdSe/CdS core-shell CQWs can be strongly manipulated. Using this method, continuous transition among three distinct exciton flow regimes with efficiencies of ~50%, ~90% and ~2% has been demonstrated. The reported method and technique, which demonstrate a lab-prototype of an all-optical controllable exciton flow device with multiple modulation stages, may inspire the design of all-optical excitonic circuits operating at room temperature.

The core idea of the method is based on the competition of stimulated emission rate, spontaneous emission rate and FRET rate together with the threshold behavior of stimulated emission. These scientists summarize the excitonic flow control process in their works:

"At low pump fluence when the emission of both donors and acceptors is spontaneous, nearly 50% of the exciton population in the donors outflows into the acceptors via FRET. By increasing the pumping level to achieve stimulated emission in the acceptors, we can greatly enhance the exciton flow efficiency up to 90% since quick depletion of excitons in the acceptors significantly promotes the FRET process. Upon further increasing the fluence to initiate stimulated emission in the donors, the exciton flow towards the acceptors almost switches off because the stimulated emission rate in donors is much faster than the FRET rate."

"To get deeper insight into this process, we have developed a FRET-coupled kinetic model to identify the competing processes responsible for the manipulation of exciton flow at different level of optical excitation. The simulation results can qualitatively reproduce the exciton flow trend from the donors to the acceptors demonstrated in our experiments." Junhong Yu, the first author of the research, added.

"This active excitonic control in an all-optical device (i.e., a whispering gallery mode laser configuration) not only offers a platform to gain deeper insight of the FRET physics but also is highly preferable for excitonic-based information processing with potentials of all-optical-control excitonic circuits." Dr. Cuong Dang, the senior author of the research said.

"The authors discuss a very timely scientific challenge, which is to move towards the excitonic devices. Controlling the exciton flow in the optically active media is the essential requirement for the development of solid-state device, and thus, has been the center of attention. The use of population overlap modulated by the lasing action in the donor-acceptor pairs will be an interesting addition to the extension excitonic studies on optically active materials. This study has merits and the advance is technological, offering an all-optical route to manipulate exciton flow in colloidal quantum well structures." Dr. Lei, one of the reviewer of LSA said.

At least two different groups of Neanderthals lived in Southern Siberia and an international team of researchers including scientists from Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have now proven that one of these groups migrated from Eastern Europe. The researchers have now published their findings in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS).

Neanderthals were widespread in Europe and also migrated to Southern Siberia, but the origins of these Siberian Neanderthals and when they migrated was not known.

An international team of researchers including archaeologist Thorsten Uthmeier, professor of Prehistory and Protohistory at FAU, have now examined tools found in the Chagyrskaya cave in the Altai mountains in Russia in order to find the answer.

Parallels to sites in Central and Eastern Europe

The site has been excavated since 2019 as part of a DFG research project in conjunction with the Siberian Branch of the Russian Academy of the Sciences in Novosibirsk. In addition to stone tools and bones from hunting remains, two main find layers yielded numerous Neanderthal fossils. After discovering that the stone tools did not resemble any of the tools from groups living in the Altai during the same period, the team searched for comparable finds in a larger radius.

Geometric morphological analyses of 3D models of scanned tools showed that the stone tools found in the Chagyrskaya cave were very similar to artefacts from the Micoquien, which is the name given to the corresponding stone tool industry in Central and Eastern Europe. The comparative scans originate among others from find sites in Bavaria including FAU's own Sesselfelsgrotte cave, in which most of the artefacts used in the comparison were found.

The researchers were able to reconstruct the route of migration of the Siberian Neanderthals using DNA analyses of Neanderthal bones and sediments from the Chagyrskaya cave. The route led the groups during the course of several generations via Croatia and the North Caucasus to the Altai.

Several groups of Neanderthals migrated to Siberia

The DNA analyses also showed that the Neanderthals from the Chagyrskaya cave differ significantly in terms of their DNA from a second Altai group found in the Denisova cave. This discovery fits with the observation that the Denisova Neanderthals were apparently not familiar with tools from the Micoquien. The research team therefore presumes that several groups of Neanderthals migrated to Siberia.

The interdisciplinary examinations of the Neanderthals found in the Chagyrskaya cave, in which Bavarian find sites investigated by FAU play an important role, clearly show that the wave of migration of groups of this species of human 60,000 years ago originated in Central and Eastern Europe.

At the same time, the researchers from Novosibirsk led by Professor Ksenia Kolobova and from FAU found rare evidence that artefacts are culturally informative indicators of population movements.

After more than 70 years, a great mystery of zoology has been solved: Honeybees actually use different dance dialects in their waggle dance. Which dialect has developed during evolution is related to the radius of action in which they collect food around the hive.

This is reported by research teams from the Biocenter of Julius-Maximilians-Universität Würzburg (JMU) in Bavaria, Germany, and the National Centre for Biological Sciences (NCBS) in Bangalore, India, in the journal Proceedings of the Royal Society B.

That honey bees might have dance dialects was first proposed in the 1940s by nobel laureate Karl von Frisch and his student Martin Lindauer. Later experiments, however, raised doubts about the existence of the dialects. The new results now prove that Frisch and Lindauer were right. The two pioneers of behavioural research were also right with their explanation why the dance dialects exist at all.

This is what the bees' dances are about

The dance language of the honeybees is a unique form of symbolic communication in the animal kingdom. For example, when a bee has discovered a blossoming cherry tree, it returns to the hive. There it informs the other bees with a dance about the direction in which the food source is located and how far away it is.

Part of the dance is the so-called waggle run, in which the bees energetically shake their abdomen. The direction of the waggle run on the honeycomb communicates the direction of the destination in relation to the position of the sun while the duration of the wagging indicates the distance.

"As the distance of the food source from the nest increases, the duration of the wagging increases in a linear fashion," explains JMU PhD student Patrick Kohl, first author of the publication. However, this increase is different for different bee species. This was shown in experiments carried out by the research team in southern India.

Experiments with three honeybee species in South India

There, three bee species with different radii of action were studied. The eastern honeybees (Apis cerana) fly up to about one kilometre away from the nest. The dwarf honeybees (Apis florea) fly up to 2.5 kilometres, the giant honeybees (Apis dorsata) about three kilometres.

The opposite relationships apply for the increase in the duration of the wagging. For example, if a food source is 800 meters away, an eastern honeybee will have a much longer wagging than a dwarf honeybee, and the latter will have a longer wagging than the giant honeybee. In order to communicate an identical distance to the food, each species uses its own dance dialect.

"We also saw this when we compared our results with published data from other research groups," says Patrick Kohl. The correlation between foraging range and dance dialect was corroborated when looking at honeybee species native to England, Botswana, and Japan.

Why did JMU researchers go to South India in the first place? "India has the advantage that three honeybee species live in the same area, so that their dance dialects can be easily compared," said Kohl. "We also have very good contacts with researchers at NCBS, a top research address in South Asia."

Dialects as evolutionary adaptations

The results also confirm what von Frisch and Lindauer had suspected about the meaning of the dance dialects. These are evolutionary adaptations to the honeybee species' typical foraging distances. Honeybees, for example, which regularly fly long distances, cannot afford to communicate these distances in the hive with very long waggle runs: On the crowded dance floor in the hive, other bees would have difficulties following such "marathon waggings".

The scientists' conclusion: The dance dialects of the bees are an excellent example of how complex behaviours can be tuned as an evolutionary adaptation to the environment.

Researchers from the Hong Kong University of Science and Technology (HKUST) have reported the world's first 1.5 μm III-V lasers directly grown on the industry-standard 220 nm SOI (silicon-on-insulators) wafers without buffer, potentially paving an opening to the "holy grail" for present silicon (Si-) photonics research.

Seamlessly bridging the active III-V light sources with the passive Si-based photonic devices, the demonstration could be deployed as light sources in integrated circuits to greatly improve circuit speed, power efficiency and cost-effectiveness.

In other conventional approaches of integrating III-V lasers on Si in the literature, thick III-V buffers up to a few micrometers are used to reduce the defect densities, which posts huge challenges for efficient light interfacing between the epitaxial III-V lasers and the Si-based waveguides.

For the first time in history, the research team led by Prof. LAU Kei-May of HKUST's Department of Electronic and Computer Engineering and Post-doctoral Fellow Dr. HAN Yu devised a novel growth scheme to eliminate the requirement of thick III-V buffers and thus promoted efficient light coupling into the Si-waveguides. The bufferless feature points to a fully integrated Si-based photonic integrated circuits.

That has enabled the first demonstration of 1.5 μm III-V lasers directly grown on the industry-standard 220 nm SOI wafers using metal organic chemical vapor deposition (MOCVD). Previous demonstrations required non-industry-standard bulk Si or thick SOI wafers.

The research findings were recently published online in Optica in February 2020.

The world's growing appetite for Internet services and the digitization of our lives leads to a vast amount of digital data being generated, processed, stored, and transmitted.

Silicon is the most widely used material in the manufacturing of semiconductors, which are embedded into nearly every piece of communications technology that we rely on every day, from computers and smartphones to datacenters and satellite communications.

But improvements in efficiency of conventional electronic data systems cannot catch up with the soaring data traffic, which calls for the integration of photonic functionalities onto the conventional Si-based electronic platform. The integration could produce optoelectronic integrated circuits with unparalleled speed and functionalities, and enable new applications.

Yet fundamental differences between Si and III-V materials means it is extremely challenging to directly grow III-V functionalities on the Si-platform.

Prof. Lau’s group at HKUST’s Phonics Technology Center has endeavored to integrate III-V materials and functionalities on mainstream silicon wafers for over a decade, innovating and optimizing various approaches to improve the performance of III-V lasers grown on Si, with the goal of progressively approaching the requirements of the industry. This work is part of their project on monolithic integration of III-V lasers on silicon.

Their method saw them first devising a unique growth scheme to directly grow high quality III-V materials on the industry-standard 220 SOI platforms. Then, they characterized and evidenced the excellent crystalline quality of these epitaxial III-V materials through extensive transmission electron microscopy and photoluminescence measurements. The team designed and fabricated the air-cladded laser cavities based on numerical simulations and they eventually tested the devices which showed that the lasers could sustain room-temperature and low-threshold lasing in the technologically important 1.5 μm band under optical excitation.

The demonstration leads to the possibility and potential to monolithically integrate III-V lasers on the industry-standard 220 nm SOI wafers in an economical, compact, and scalable way.

Prof. Lau said: "If practically applied, our technology could enable a significant improvement of the speed, power consumption, cost-effectiveness, and functionality of current Si-based integrated circuits. Our daily electronic devices, such as smartphones, laptops and TVs - basically everything connected to the internet - will be much faster, cheaper, using much less power and multi-functional."

Dr. Han added: "The next step of our research will be to design and demonstrate the first electrically-driven 1.5 μm III-V lasers directly grown on the 220 nm SOI platforms, and devise a scheme to efficiently couple light from the III-V lasers into Si-waveguides and thereby conceptually demonstrate fully-integrated Si-photonics circuits."