Tech

The extensive use of epidemiological surveillance, isolation of infected patients, and quarantines of exposed individuals in the Chinese city of Shenzhen in the early months of the COVID-19 outbreak allowed scientists to estimate important characteristics of this now-pandemic infectious disease, according to a study co-led by researchers at Johns Hopkins Bloomberg School of Public Health.

The researchers, who published their findings April 27 in The Lancet Infectious Diseases, analyzed data gathered by the Shenzhen Center for Disease Control and Prevention on 391 people with COVID-19--what are referred to as "index cases," or the first identified cases in an outbreak--and 1,286 of their close contacts, during the 30-day period January 14 to February 12. Shenzhen is a densely populated city of about 13 million people, situated just north of Hong Kong.

The analysis, thought to be the first of its kind in such a well-documented and well-tested set of cases, revealed that the COVID-19 index cases had symptoms for about five days on average before being identified, but that contact tracing and extensive testing reduced this to about three days for infected contacts. Among the contacts, household contacts were at particularly high risk of infection. Children, while less likely to develop severe symptoms, were infected at about the same rate as adults.

"Having data on an early set of infected individuals as well as their contacts allowed us to tackle questions about COVID-19 transmission dynamics that had been hard to answer before," says study co-senior author Justin Lessler, associate professor in the Bloomberg School's Department of Epidemiology.

The study was a collaboration between Lessler's group at the Bloomberg School; Ting Ma, PhD, and colleagues at the Harbin Institute of Technology and Peng Cheng Laboratory in Shenzhen; and Tiejian Feng, MD, of the Shenzhen Center for Disease Control and Prevention.

How an emergent pathogen is transmitted from one individual to the next can be difficult for epidemiologists to assess once community spread has begun since the potential paths of transmission become too complex to trace reliably. By contrast, early in an outbreak, before community spread has started, epidemiologists can much more easily assess transmission dynamics by finding symptomatic people, and then tracing their recent contacts to see who got infected and who didn't.

Prompted by reports from Hubei Province, where the COVID-19 outbreak appears to have started in the city of Wuhan in late 2019, the Shenzhen CDC in early January began gathering and testing suspected cases in the city: people who had recently traveled from Hubei, people with fevers in local hospitals, and others identified through community fever screening. The public health agency also traced all recent close contacts of suspected cases. Suspected or confirmed cases with symptoms were isolated in local hospitals, and asymptomatic people with test-confirmed exposures were quarantined. For their study, Lessler and colleagues analyzed the data gathered by the Shenzhen CDC from January 14 to February 12.

The researchers found that among the 391 confirmed cases of COVID-19 during this period, men (187 cases) and women (204 cases) were about equally represented, though men were about 2.5 times more likely to show severe symptoms. Children also were about as likely as adults to be infected, though they were less likely to have severe symptoms.

Only about 9 percent of the 391 infected people showed severe symptoms at the time they were first evaluated by doctors. Among the secondary cases discovered by contact tracing, 20 percent reported no symptoms at the time they were first evaluated--suggesting that a significant proportion of coronavirus carriers are "silent carriers," at least during the early stage of infection. The average age of the 391 infected people was about 45.

The sample of 391 people included subsets for whom the timing of key events was known with high confidence, enabling the researchers to estimate key time intervals for COVID-19. For example, the "incubation period," from exposure to symptom onset, had an estimated median value of 4.8 days. The median recovery time--the interval from symptom onset to having no symptoms and also testing negative for viral RNA--was 23 days for 60­-69 year olds, 22 days for 50-59 year olds, and 19 days for 20-29 year olds.

The "attack rate," or the proportion of close contacts of a confirmed case that are infected, was 6.6 percent when the researchers assumed that all close contacts were tested and all positive results were recorded. The attack rate was higher--11.2 percent--for household contacts.

The "serial interval," which approximates the interval between one person's becoming infected and infecting another, had an average value of 6.3 days.

The researchers also calculated that the "observed reproduction number," the average number of detected infections caused by each infected person, was just 0.4. That low figure, suggesting a disease that will quickly die out instead of spreading, was likely in part due to the Shenzhen CDC's efforts to detect and isolate the index cases and their contacts. If the reproductive number remains less than one, infection is not able to spread effectively.

Lessler notes, however, that the 0.4 figure is based only on the known infected contacts. "We don't have the full picture--there weren't data on all the unknown contacts of each case, such as the people who rode on buses with them, or passed them on the street," he says.

Moreover, the researchers found that some infected individuals accounted for many further infections, implying that such superspreaders could relatively easily reignite outbreaks.

"Our analysis suggested that about 80 percent of infections among contacts were caused by just 8.9 percent of our index cases," says study co-first author Qifang Bi, MHS, a PhD student in the Bloomberg School's Department of Epidemiology.

These estimates for key COVID-19 intervals and rates will help epidemiologists, pharmaceutical scientists, and public health officials around the world shape their goals and policies to meet the challenge of the pandemic, the researchers say.

It is known that approximately 80% of human immune system functions in the gastrointestinal tract. Gut bacteria and their metabolites play a fundamental role in the interaction between gut and other organs. Since the organic acids produced by colon bacteria (acetate, lactate, propionate, succinate and butyrate) activate a number of immune and hormonal processes, the microbiota composed of hundreds of different bacterial species is of vital importance for the normal functioning and health of the human body.

Head of the Microbiomics Research Group of TalTech Department of Chemistry and Biotechnology, Senior Researcher Kaarel Adamberg says, "Food is a crucial factor in modulating the gut microbiota and its metabolism. Very important nutrients for the colon bacteria are the dietary compounds that are not broken down by enzymes in the stomach and small intestine and, thus, reach the large intestine. A person requires at least 25 - 35 g of fibre a day for normal bowel function. Water-binding fibers also promote the movement of food in the digestive tract."

Moreover, the nature of the processes taking place in the large intestine is to a large extent determined by the transit rate of the chyme that can be simulated in vitro by the dilution rate of the continuous culture. Transit rate is a key parameter that determines the nutrient availability for the bacteria, which in turn determines which products can be produced from the food residues. First, bacteria break down carbohydrates, i.e. fibers. At lower transit rates, when carbohydrates have run out, bacteria will break down more proteins, which can result in the formation of toxic substances.

TalTech's Microbiomics Research Group studied recently how the proportions and metabolism of fecal microbiota change at the range of specific growth rates similar to physiological colonic transit rate. The study focused on the effect of pectin and xylan on the fecal microbiota. Pectin can be found in many fruits and berries (currants, apples, plums) and xylan is an important fiber found mainly in cereals (rye, wheat).

"The experiments showed that the growth rate had a much greater effect on the composition and metabolism of fecal microbiota compared to fiber specificity. From the point of view of nutrition, this means that the amount and diversity of dietary fibers determine the rate of passage of food in the digestive tract and, thus, the growth rate and activity of the gut microbiota. The effect of the transit rate has not been studied in detail so far and the study of combined effects of various factors must be continued in the future. This is an even more complicated task," Senior Researcher Adamberg says.

As the results of in vitro tests may depend on the initial conditions of the experiment, it was checked whether the same results would be obtained if the culture was stabilized at either high or low dilution rate and the experiments were carried out in both directions: gradually moving dilution rates from slow to fast and from fast to slow. The results suggest that the culture adapted to the changing conditions under both directions of the dilution rate and the results were reproducible. This confirms that the specific growth rate is a key factor in the development of microbial communities.

"We have previously studied the degradation of dietary fibers and the dynamics of gut microbial communities using the fecal samples from children. In this study similar changes in the fecal microbiota were seen in adults' gut microbiota. In addition, the fecal microbiota was able to adapt to the slow changes in acceleration rate. This could mean than if we are able reduce the time it takes for food to travel through the gut, i.e. increase the transit rate by making changes in dietary patterns, the bacterial community will adapt to the new transit rate and its metabolism will become more favorable to health," Kaarel Adamberg says.

Controlled in vitro cultivation and up-to-date analytical methods enable systematic evaluation of complex interactions between the members of microbial consortia. This is a challenging, but promising approach for research, industrial and medical applications. It is known that in many cases the diversity of human gut microbiota has decreased so much that diet change will not help, because the beneficial bacteria have been washed out. In such cases, the best solution provided currently is to transplant faeces from a healthy individual into the patient's colon. If we learn to grow the consortia suitable for transplantation under laboratory or even industrial conditions, the next generation probiotics could be used instead of the fecal transplant, i.e. this would be the artificial microbiota that could be transplanted in individuals dysbiotic gut microbiota.

"This new knowledge about the associations between gut microbial communities and dietary fibers allows the diet modifications supporting personal gut bacteria. Although the results obtained in laboratory experiments need to be verified by human nutrition studies, our previous in vitro results have shown good associations with the outcomes of the human trials," Kaarel Adamberg says.

Scientists at the University of Southampton and Forest Research say understanding the risk of damage by deer to new and existing forests in Britain is crucial when considering their expansion.

The researchers analysed data from over 15,000 National Forest Inventory survey plots across Britain and, among other findings, showed the level of destruction deer cause isn't solely down to the concentration of their numbers in a given area. They concluded damage is also driven by a range of other important factors, such as climate, tree type and density, roads and, crucially, the amount of forest in the surrounding landscape.

The study is part of SCALEFORES, a €1.5m project funded by the European Research Council (ERC), and detailed findings are published in the Journal of Applied Ecology.

Ambitious targets for planting new woodland have been set in the UK. The Government has committed to planting up to 30,000 hectares of trees per year, across the UK, by 2025.1

Wild deer pose a significant threat to forests. They strip the leaves, shoots and bark of trees, decimate plant communities in the undergrowth, and prevent natural regeneration of trees.

Lead author, Dr Rebecca Spake, Research Fellow in Applied Biogeography at the University of Southampton, comments: "As we make plans to expand our forests in Britain, it becomes increasingly important to understand what drives damage by deer populations. New woodland needs protection from deer, but creating woodlands could also have knock-on effects on deer damage in another.

"Our study shows how this understanding can be used to target costly mitigation efforts, such as fencing, to the right places."

Professor Felix Eigenbrod, study co-author, adds: "This study shows the importance of considering the wider landscape context when deciding where to plant the forests required to help meet the UK's ambitious climate change goals."

Ben Ditchburn, Programme Lead for the National Forest Inventory at Forest Research said: "This collaborative research provides a deep dive into our National Forest Inventory data, revealing hidden patterns and valuable new insights into deer behaviour that we would otherwise not be aware of."

Dr Chloe Bellamy, Forest Research, adds "Recent official national statistics from the National Forest Inventory highlighted the fact that 40 percent of British forests have 'unfavourable' levels herbivore damage, which limits the survival of young trees and threatens biodiversity. Our analysis shows where and why deer are likely to damage trees, information which is critical to targeting efforts to enhance forest cover and condition."

The researchers found that the amount of forest in the surrounding landscape was important in explaining the likelihood of damage to a site. However, this effect was not straightforward, and depended on regional deer density and climate, in addition to the surrounding cover of low vegetation. To communicate this complexity, the authors have launched an interactive Deer Damage Tool to help land managers investigate how afforestation may influence deer damage in different areas of the country, in addition to summarising their findings in a paper.

At a local level, there's an increased likelihood of deer foraging in unmanaged, broadleaved woodland which has relatively low numbers of trees and varies widely in age. This is likely due to greater ease of movement for the animals, an attractive layer of vegetation between trees for feeding and a preference for eating broadleaved species. Findings also showed, in agreement with previous studies, that roads deter deer from selecting surrounding habitats.

Dr Robin Gill, deer specialist at Forest Research comments: "These results will help us assess the risk of deer damage in the future, which is particularly important in the context of new policy initiatives to expand our forests to combat climate change."

The study authors used data from The National Forest Inventory field survey and deer density figures from the Game and Wildlife Conservation Trust's National Game Bag Census. From these, they modelled and mapped site susceptibility to deer damage.

With antimicrobial resistance (AMR) increasing around the world, new research led by the University of Bristol has shown a new drug formulation could possibly be used in antifungal treatments against Candida infections.

Candida albicans, a well-known yeast usually seen in the mouth, skin, gut and vagina, is reported to form biofilms and cause mild to life threatening infections. Fluconazole, an antifungal drug widely used to treat Candida infections is completely ineffective in treating Candida biofilms and new drugs are needed to treat them. However, unlike antibiotics, developing antifungal drugs is very challenging because yeast cells are structurally similar to human cells, as a result, there is a greater chance of unwanted side effects with new antifungal drugs. A better alternative would be to improve the efficiency of currently approved antifungal drugs such as fluconazole but with minimal side effects.

Recent studies have shown that microorganisms can communicate with each other using various chemical signals. Some microorganisms use these signals to control other competing microorganisms and these signals could potentially be used as antimicrobial drugs.

In the study, published in International Journal of Pharmaceutics, the researchers investigated whether using some of these microbial signals from bacteria could improve the activity of fluconazole against Candida biofilms.

The research team found that a specific chemical signal released from a major bacterial pathogen can be successfully used to significantly improve the activity of fluconazole against Candida biofilms by packaging them to small lipid molecules and delivering them together.

The pioneering research is one of only a few studies to demonstrate the possibility of using naturally existing microbial compounds against other pathogenic microorganisms.

Dr Nihal Bandara, Lecturer in Oral Microbiology from the Bristol Dental School and corresponding author, said: "It is well known that microorganisms live as "slime" communities, called "microbial biofilms", and are responsible for up to 80 per cent of all infections in humans. These microorganisms are extremely difficult to remove even with the most effective antimicrobial drugs. They can lead to a significant number of deaths and disabilities to patients and can be a healthcare and financial burden to economies around the world.

"It was really exciting to discover that we can use various signals released by microorganisms against others to control infections."

The research team would like to develop the technique used in the study and investigate the efficacy of new drug formulation using an animal model.

In the future, it is hoped researchers and pharmaceutical industries will explore the antimicrobial properties of microbial chemical signals so they can be developed into cost effective treatments.

Philadelphia, April 28, 2020 - Researchers report the development of a sensitive and specific assay to detect different serotypes of Salmonella, paving the way for rapid serotyping directly from specimens. This improvement upon current testing methods can play a critical role in quickly tracing the origin of the infection. The report appears in The Journal of Molecular Diagnostics, published by Elsevier.

Recent data from the Centers for Disease Control and Prevention (CDC) indicate that food poisoning caused by Salmonella bacteria leads to 1.35 million infections, 26,500 hospitalizations, and 420 deaths in the United States per year. During an outbreak, the speed and simplicity of a test to detect specific types of bacteria are important for public health investigators to track down the source.

"Salmonella in a clinical or food sample may be present in very small amounts and thus requires very sensitive methods to detect them. Multiple cross-displacement amplification (MCDA) is a method that can detect very small amounts of DNA rapidly and is also performed at a single constant temperature, in contrast to the cycling of temperatures required in other methods such as PCR. This makes it a good fit for a simple, rapid, and sensitive bacterial detection test. Although an MCDA test for any Salmonella already exists, it does not distinguish between different serotypes," explained Professor Ruiting Lan, PhD, of the School of Biotechnology and Biomolecular Sciences at the University of New South Wales, Sydney, NSW, Australia.

The investigators developed an MCDA assay for each of the seven serovar (subtype)-specific targets of Salmonella. All of these assays accurately detect as few as 10 copies of DNA and can produce results in approximately eight minutes. Importantly, these assays do not require specialized detection equipment, simplifying any future application in clinical or industrial settings. By combining these seven serovar-specific assays with the existing species assay, Salmonella detection can be simplified and accelerated.

"The assays developed in this study are unique because the gene markers used were selected based on analyzing thousands of genomes. Thus, these markers future proof Salmonella serotyping in the era of culture-independent diagnostic testing," commented Professor Lan.

Traditional methods to distinguish Salmonella serotypes involve growing the bacteria from samples and then testing them to assign them to a serovar. The MCDA test is faster because it does not require first growing the bacteria in culture. Rather, it can detect very small amounts of Salmonella DNA.

Although there are hundreds of Salmonella serovars, the authors chose the five most commonly occurring in Australia, which cause more than 85 percent of Salmonella infections in that country. However, at least two of these serovars are also the top Salmonella serovars throughout the world, therefore the researchers believe the results are applicable to other geographic regions.

Salmonella bacteria typically live in animal and human intestines and are shed through feces. Humans may become infected by ingesting contaminated water or food such as raw or undercooked meat, poultry, eggs, or egg products. Possible signs and symptoms of Salmonella poisoning include nausea, vomiting, abdominal cramps, diarrhea, fever, and headache.

Researchers at Aalto University and Turku PET Centre have developed a new method for simultaneous imaging brain activity from two people, allowing them to study social interaction.

In a recent study, the researchers scanned brain activity from 10 couples. Each couple spent 45 minutes inside the MRI scanner in physical contact with each other. The objective of the study was to examine how social contact activates the brain. The results were published in the theme issue Social Interaction in Neuropsychiatry of the journal Frontiers in Psychiatry.

"This is an excellent start for the study of natural interaction. People don't just react to external stimuli, but adjust their actions moment-by-moment based on what they expect to happen next," says Riitta Hari, emerita Professor at Aalto University.

Ordinary magnetic resonance imaging is used to scan one person at a time. In the device developed at Aalto University, the head coil used for regular brain scans was divided into two separate coils. This new design allows for simultaneous scanning of two brains, when the individuals are positioned close enough to each other inside the scanner. During scanning, the participants were face-to-face, almost hugging each other.

When instructed by the researchers, the subjects took turns in tapping each other's lips. Looking at the brain scans, the researchers could see that the motor and sensory areas of the couples' brains were activated.

Studying the fundamentals of human interaction

"During social interaction, people's brains are literally synchronised. The associated mental imitation of other people's movements is probably one of the basic mechanisms of social interaction. The new technology now developed will provide totally new opportunities for studying the brain mechanisms of social interaction," says Professor Lauri Nummenmaa from Turku PET Centre.

"For example, during a conversation or problem solving, people's brain functions become flexibly linked with each other. However, we cannot understand the brain basis of real-time social interaction if we cannot simultaneously scan the brain functions of both persons involved in social interaction," Riitta Hari says.

Health care providers and parents have been valuable partners in managing adolescent sexual and reproductive health. But research has been limited concerning the efficacy of "triadic" interventions, or those implemented with parents and providers with the goal of reducing adolescent sexual risk behavior.

Now, a randomized clinical trial carried out under a grant by the National Institutes of Health shows the efficacy of a triadic intervention to postpone adolescent sexual debut and to promote condom use among adolescents aged 11 to 14 years.

Published today (Apr. 28) in Pediatrics, the study - "A Triadic Intervention for Sexual Health: A Randomized Clinical Trial" - was conducted by Vincent Guilamo-Ramos, director of the Center for Latino Adolescent and Family Health (CLAFH) at the Silver School of Social Work at New York University and a nurse practitioner specializing in adolescent sexual and reproductive health care at the Adolescent AIDS Program at Children's Hospital at Montefiore.

The study's coauthors include Adam Benzekri (CLAFH); Marco Thimm-Kaiser (CLAFH and the CUNY School of Public Health and Health Policy); Patricia Dittus (Centers for Disease Control and Prevention, Division of STD Prevention); Yumary Ruiz (Purdue University and CLAFH); Charles M. Cleland (NYU Langone), and Dr. Wanda McCoy (Morris Heights Health Center, Bronx, NY).

The researchers evaluated Families Talking Together (FTT), a triadic intervention developed by Dr. Guilamo-Ramos and colleagues designed to reduce adolescent sexual risk behavior and address persistent disparities in unplanned teen pregnancies as well as sexually transmitted infections such as HIV/AIDS.

Adolescents aged 11-14 and their female caregivers were recruited from a Bronx, N.Y., pediatric clinic, and 900 families enrolled in the study. The Families Talking Together intervention consists of a 45-minute face-to-face session for mothers, health care provider endorsement of the intervention content, FTT family communication workbook for families, and a booster phone call for mothers.

To evaluate the FTT intervention, assessments were conducted initially (baseline), three months later, and a year later, asking whether adolescents engaged in vaginal intercourse, made their sexual debut within the past 12 months, and used a condom in their last sexual encounter.

At 12-month follow-up, 5.2% of adolescents in the experimental group (those participating in the Families Talking Together intervention program) reported having had sexual intercourse, compared to 18.0% of adolescents in the control groups, who did not receive the FTT intervention.

In the experimental group, 4.7% of adolescents reported sexual debut within the past 12 months, compared to 14.7% of adolescents in the control group.

In the experimental group, 74.2% of sexually active adolescents indicated using a condom at last sex, compared to 49.1% of sexually active adolescents in the control group.

"The research suggests that the FTT triadic intervention is efficacious in delaying sexual debut and reducing sexual risk behavior among adolescents," according to the study.

The findings are particularly important since FTT addresses the important role of parents in shaping adolescent sexual and reproductive health while respecting adolescent autonomy and confidentiality in healthcare, making FTT an innovative solution to respond to calls from parents and national health organizations for more parental involvement in adolescent SRH care.

An invasive species first identified in the Mediterranean Sea just eight years ago is likely to become a permanent feature of the region, a new study suggests.

First seen off the coast of Cyprus in 2012, lionfish (Pterois miles) are now thriving and well-established in the area and across southern Europe.

However, the increasing densities observed over time - combined with the species' generalist diet and consumption of ecologically and socio-economically important fish - may result in further disruption of an already stressed marine environment.

The scale of spread would suggest the lionfish cannot be eradicated, with scientists writing in the Journal of Fish Biology suggesting the development of a dedicated lionfish industry could help manage the situation and lessen some of the species' negative impacts.

The research was carried out by a team of international scientists from the Marine and Environmental Research (MER) Lab in Cyprus, the University of Cyprus, the University of Plymouth (UK) and the Enalia Physis Environmental Research Centre (Cyprus).

They are among the collaborators on the four-year, €1.6million RELIONMED project - funded by the European Union - which aims to assess the history of the lionfish invasion in Cyprus, and identify ways to minimise its future impact.

Savva Ioannis, the publication's lead author and a researcher at MER, said: "Among the numerous threats to our marine ecosystems, biological pollution is less apparent to the human perception. But in reality, it's potent enough to disrupt the ecological balance. Although not all alien species successfully establish in or harm their new environment, some acclimatise relatively easy, exhibit rapid spread and exert catastrophic impacts on local marine communities. That has been the case with lionfish populations in the western Atlantic Ocean and now the story is repeating itself in the Mediterranean Sea."

The current study examined some of the species' biological and ecological characteristics, and found individuals measuring between 8 and 37cm in length, and aged 0.5 to four years old. Both factors signify their successful establishment around the island.

Female lionfish were generally greater in proportion than males, which scientists say is alarming since a single male can court several females, hence causing a population boom at a faster rate.

They also say the invasion characteristics resemble those of the western Atlantic Ocean. There, lionfish were first recorded off the coast of Florida in 1994, but by 2014 it was estimated that there were up to 1,000 lionfish per acre.

In the Mediterranean, lionfish are spreading fast along the island of Cyprus, forming large aggregations and achieving greater body size and faster growth rates than those in the Indian Ocean from where they immigrated.

The Mediterranean population also differs because although the lionfish show signs of spawning throughout the year, they exhibit a single major reproductive peak that coincides with seawater warming over the summer period.

Jason Hall-Spencer, Professor of Marine Biology at the University of Plymouth, said: "The recent rapid spread of lionfish in the Mediterranean is a serious concern for the balance of marine life in the region as this is the most damaging invasive fish species known to science. This study really does emphasise the need for biosecurity measures in the Suez canal which is like a cut artery, with marine invasive species pouring through."

PITTSBURGH--Today's virtual reality systems can create immersive visual experiences, but seldom do they enable users to feel anything -- particularly walls, appliances and furniture. A new device developed at Carnegie Mellon University, however, uses multiple strings attached to the hand and fingers to simulate the feel of obstacles and heavy objects.

By locking the strings when the user's hand is near a virtual wall, for instance, the device simulates the sense of touching the wall. Similarly, the string mechanism enables people to feel the contours of a virtual sculpture, sense resistance when they push on a piece of furniture or even give a high five to a virtual character.

Cathy Fang, who will graduate from CMU next month with a joint degree in mechanical engineering and human-computer interaction, said the shoulder-mounted device takes advantage of spring-loaded strings to reduce weight, consume less battery power and keep costs low.

"Elements such as walls, furniture and virtual characters are key to building immersive virtual worlds, and yet contemporary VR systems do little more than vibrate hand controllers," said Chris Harrison, assistant professor in CMU's Human-Computer Interaction Institute (HCII). User evaluation of the multistring device, as reported by co-authors Harrison, Fang, Robotics Institute engineer Matthew Dworman and HCII doctoral student Yang Zhang, found it was more realistic than other haptic techniques.

"I think the experience creates surprises, such as when you interact with a railing and can wrap your fingers around it," Fang said. "It's also fun to explore the feel of irregular objects, such as a statue."

The team's research paper was named a best paper by the Conference on Human Factors in Computing Systems (CHI 2020), which was scheduled for this month but canceled due to the COVID-19 pandemic. The paper has now been published in the conference proceedings in the Association for Computing Machinery's Digital Library.

Other researchers have used strings to create haptic feedback in virtual worlds, but typically they use motors to control the strings. Motors wouldn't work for the CMU researchers, who envisioned a system both light enough to be worn by the user and affordable for consumers.

"The downside to motors is they consume a lot of power," Fang said. "They also are heavy."

Instead of motors, the team used spring-loaded retractors, similar to those seen in key chains or ID badges. They added a ratchet mechanism that can be rapidly locked with an electrically controlled latch. The springs, not motors, keep the strings taut. Only a small amount of electrical power is needed to engage the latch, so the system is energy efficient and can be operated on battery power.

The researchers experimented with a number of different strings and string placements, eventually concluding that attaching one string to each fingertip, one to the palm and one to the wrist provided the best experience. A Leap Motion sensor, which tracks hand and finger motions, is attached to the VR headset. When it senses that a user's hand is in proximity to a virtual wall or other obstacle, the ratchets are engaged in a sequence suited to those virtual objects. The latches disengage when the person withdraws their hand.

The entire device weighs less than 10 ounces. The researchers estimate that a mass-produced version would cost less than $50.

Fang said the system would be suitable for VR games and experiences that involve interacting with physical obstacles and objects, such a maze. It might also be used for visits to virtual museums. And, in a time when physically visiting retail stores is not always possible, "you might also use it to shop in a furniture store," she added.

Chronic iron imbalances - having either too little or too much iron in the blood - can result in medical conditions ranging from anaemia and haemochromatosis through to more severe diseases, such as cancer, Parkinson's Disease and Alzheimer's Disease.

Haemochromatosis is one of Australia's most common hereditary diseases and the Australian Bureau of Statistics estimates approximately 780,000 people live with anaemia.

School of Biomedical Engineering PhD candidate and Sydney Nano Institute student ambassador, Pooria Lesani, who is undertaking his studies under the supervision of Professor Hala Zreiqat and Dr Zufu Lu, has developed a multipurpose nanoscale bio-probe that allows researchers to precisely monitor iron disorders in cells, tissue, and body fluids as small as 1/1000th of a millimolar[1].

The test is more sensitive and specific than blood testing currently used to detect iron disorders, which begin at very low, cellular level concentrations.

Using novel carbon-based fluorescent bio-nanoprobe technology, the test, which involves non-invasive subcutaneous or intravenous injections, allows for a more accurate disease diagnosis before the onset of symptoms, potentially allowing for the early treatment and prevention of more serious diseases.

"More than 30% of the world's population lives with an iron imbalance, which over time can lead to certain forms of cancer, as well Parkinson's Disease and Alzheimer's Disease," said Mr Lesani from the Tissue Engineering and Biomaterials Research Unit and the ARC Centre for Innovative BioEngineering.

"Current testing methods can be complex and time consuming. To counter this, and to enable the early detection of serious diseases, we have developed a hyper-sensitive and cost-efficient skin testing technique for detecting iron in the body's cells and tissue.

"Our most recent testing demonstrated a rapid detection of free iron ions with remarkably high sensitivity. Iron could be detected at concentrations in the parts per billion range, a rate ten times smaller than previous nano-probes.

"Our sensor is multifunctional and could be applied to deep-tissue imaging, involving a small probe that can visualise structure of complex biological tissues and synthetic scaffolds."

Tested on pig skin, the nanoprobe outperformed current techniques for deep tissue imaging, and rapidly penetrated biological tissue to depths of 280 micrometres and remained detectable at depths of up to 3,000 micrometres - about three millimetres - in synthetic tissue.

The team aims to test the nanoprobe in larger animal models, as well as investigate other ways in which it can be used to determine the structure of complex biological tissues.

We hope to integrate the nanoprobe into a "lab-on-a-chip" sensing system - a portable, diagnostic blood testing tool which could allow clinicians to remotely monitor their patients' health.

"Lab-on-a-chip systems are relatively simple to operate and require only small blood volume samples from the patient to gain an accurate insight of potential ferric ion disorders in the body, assisting early intervention and prevention of disease," he said.

The nano-sensors can also be made from agricultural and petrochemical waste products, allowing for low-cost, sustainable manufacturing.

Vietnam features extensive ethnolinguistic diversity and occupies a key position in Mainland Southeast Asia (MSEA). Vietnam, with its borders to China, Laos and Cambodia, has a rich geographical diversity, and ample access to human migration with the Red River and Mekong deltas, and a long coastline.

The early settlement of anatomically modern humans in MSEA dates back to at least 65 thousand years ago (kya) and is associated with the formation of a hunter-gatherer tradition called Hoabinhian. Since the Neolithic period, which dates to about ~4,000-5,000 years ago, cultural transitions and diversification have happened multiple times eventually leading to the extraordinary cultural diversity in present day MSEA.

According to the General Statistics Office of Vietnam, Vietnam has a population size of more than 96 million people comprising 54 official ethnic groups; 110 languages are spoken in the country. To date, there are hundreds of ethnolinguistic groups in MSEA, speaking languages belonging to five major language families: Austro-Asiatic (AA), Austronesian (AN), Hmong-Mien (HM), Tai-Kadai (TK), and Sino-Tibetan (ST).

Yet, the genetic diversity of Vietnam has remained relatively unexplored, especially with genome-wide data, because previous studies have focused mainly on the majority Kinh group.

Now, in a new paper published in the advanced online access edition of Molecular Biology and Evolution, Dang Liu, Mark Stoneking and colleagues have analyzed newly-generated genome-wide SNP data for the Kinh and 21 additional ethnic groups in Vietnam, encompassing all five major language families in MSEA, along with previously-published data from nearby populations and ancient samples.

"We find that the Vietnamese ethnolinguistic groups harbor multiple sources of genetic diversity that are associated with heterogeneous ancestry sharing profiles in each
language family," said corresponding author Nong Van Hai. First author Dang Liu added, "However, the linguistic diversity does not completely match genetic diversity; there have been extensive interactions between the Hmong-Mien and Tai-Kadai groups, and a likely case of cultural diffusion in which some Austro-Asiatic groups shifted to speaking Austronesian languages.

On a global scale, the strongest signal separates most Indian groups from the East Asian groups. They also found evidence that the majority group Kinh, which have been the focus of previous studies, may not reflect the total Vietnamese diversity. Within modern Vietnamese groups, individuals from the same language family are mostly placed together. Within these language families, the ST, HM, and TK groups are mostly separated from AA and AN groups. Vietnam ethnolinguistic groups overall tend to show the closest relationships with Taiwanese and southern Chinese groups.

"Overall, our results highlight the importance of genome-wide data from dense sampling of ethnolinguistic groups in providing new insights into the genetic diversity and history of an ethnolinguistically-diverse region, such as Vietnam," said corresponding author Mark Stoneking. "In contrast to previous studies suggesting a largely indigenous origin of the Vietnamese, we find evidence for extensive contact, over different time periods, between Vietnamese and other groups.

The study is the most wide-spread analysis to date, carrying out the most updated and informative approaches available from using modern genomic data, to better understand the rich genetic population diversity of Vietnam.

A simple pretreatment step enables membranes to be enhanced using atomic layer deposition, a technique that can improve performance and introduce new surface properties.

Many industrial processes rely on thin membranes that can clean water, for example, by filtering out impurities. In recent years, a technique called atomic layer deposition (ALD) has been used to tune these membranes for better performance, but there’s a hitch: Many of them are made from materials that aren’t compatible with ALD, a process using alternating chemical vapors to create very thin layers on a surface.

A new method developed by a team including researchers from the U.S. Department of Energy’s (DOE) Argonne National Laboratory makes ALD possible on nearly any membrane. The researchers discovered a surprisingly simple solution: dipping membranes in tannic acid first. The acid’s molecules stick to the membrane’s surface, providing nucleation sites — or points where an ALD coating can take hold and grow.

“There’s a whole library of things you can do with ALD. This technique now opens up that library for polymer membranes.” — Seth Darling, director of Argonne’s Advanced Materials for Energy-Water Systems (AMEWS) Energy Frontier Research Center

The ability to use this technique on typically resistant membrane materials enables a variety of potential enhancements that could improve functionality and durability — or create altogether new properties. The work is detailed in the paper “Polyphenol-Sensitized Atomic Layer Deposition for Membrane Interface Hydrophilization,” which was recently published in the journal Advanced Functional Materials.

Many commercial membranes are made from common plastics such as polypropylene and polyethylene, which are inexpensive and relatively sturdy. But when used to treat water, these polymer-based membranes tend to cause problems. Their surfaces are prone to fouling, where contaminants accumulate in their pores and reduce efficacy.

With ALD, a process common in the semiconductor industry, membranes can be altered to resist fouling or take on other desirable properties. Molecules deposited on the surface can weave their way through a membrane’s tortuous network of pores to find all the surfaces inside, creating an exceptionally uniform coating.

“ALD, in principle, is great,” said Seth Darling, a co-author of the study and director of Argonne’s Advanced Materials for Energy-Water Systems (AMEWS) Energy Frontier Research Center. “The challenge is that most polymers that are used to make membranes are not amenable to coating with ALD.”

In the study, tannic acid pretreatment enabled a water-resistant polymer membrane to be coated with titanium dioxide, transforming its surface to become hydrophilic (water-loving) instead. The water-attracting layer creates a protective buffer against fouling.

The AMEWS center, which is funded by DOE’s Office of Science, supported the work as part of a broader effort to understand and control what happens at the interface between water and solid materials. Such understanding is key to improving how we process and use water.

In the past, Argonne researchers have exploited the fact that some polymers are inhospitable to ALD by creating a two-faced “Janus” membrane, with a full metal oxide coating on top of the membrane and none on the other side. This latest study is the first time scientists have been able to completely and uniformly sensitize a membrane to ALD using a nondestructive pretreatment.

Argonne is developing methods for scaling up ALD and other interface engineering capabilities so that these methods can be evaluated for large, industrial applications. “We currently use lab-scale reactors for these research studies, but we are building tools for efficient ALD processing of large area substrates. This will allow pilot-scale testing of our ALD materials,” said Jeffrey Elam, a senior chemist at Argonne and study co-author.

The new method potentially could work not just with tannic acid but any liquid polyphenol and also with any polymer membrane, which opens up a vast number of possibilities beyond the proof of concept described in the paper. In addition to water-attracting or water-resistant coatings, ALD can be used to create chemically reactive or electrically conductive materials.

“There’s a whole library of things you can do with ALD,” Darling said. “This technique now opens up that library for polymer membranes.”

Lithium-sulfur batteries have been hailed as the next big step in battery technology, promising significantly longer use for everything from cellphones to electric vehicles on a single charge, while being more environmentally sustainable to produce than current lithium-ion batteries. However, these batteries don't last as long as their lithium-ion counterparts, degrading over time.

A group of researchers in the Cockrell School of Engineering at The University of Texas at Austin has found a way to stabilize one of the most challenging parts of lithium-sulfur batteries, bringing the technology closer to becoming commercially viable. The team's findings, published today in Joule, show that creating an artificial layer containing tellurium, inside the battery in-situ, on top of lithium metal, can make it last four times longer.

"Sulfur is abundant and environmentally benign with no supply chain issues in the U.S.," said Arumugam Manthiram, a professor of mechanical engineering and director of the Texas Materials Institute. "But there are engineering challenges. We've reduced a problem to extend the cycle life of these batteries."

Lithium is a reactive element that tends to break down other elements around it. Every cycle of a lithium-sulfur battery -- the process of charging and discharging it -- can cause mossy, needle-like deposits to form on the lithium-metal anode, the negative electrode of the battery. This starts a reaction that can lead to the battery's overall degradation.

The deposits break down the electrolyte that shuttles lithium ions back and forth. This can trap some of the lithium, keeping the electrode from delivering the full power necessary for the ultra-long use the technology promises. The reaction can also cause the battery to short-circuit and potentially catch fire.

The artificial layer formed on the lithium electrode protects the electrolyte from being degraded and reduces the mossy structures that trap lithium from forming during charges.

"The layer formed on lithium surface allows it to operate without breaking down the electrolyte, and that makes the battery last much longer," said Amruth Bhargav, who, along with fellow graduate student Sanjay Nanda, co-authored the paper.

Manthiram added that this method can be applied to other lithium- and sodium-based batteries. The researchers have filed a provisional patent application for the technology.

"The stabilizing layer is formed by a simple in-situ process and requires no expensive or complicated pre-treatment or coating procedures on the lithium-metal anode," Nanda said.

Solving the instability of this part of the battery is key to extending its cycle life and bringing about wider adoption. Manthiram said that lithium-sulfur batteries are currently best suited for devices that need lightweight batteries and can run for a long time on a single charge and don't require a large number of charge cycles, such as drones. But they have the potential to play an important role in extending the range of electric vehicles and increased renewable energy adoption.

Both the positive and negative electrodes in lithium-sulfur batteries hold 10 times as much charge capacity as the materials used in today's lithium-ion batteries, Manthiram said, which means they can deliver much more use out of a single charge. Sulfur is widely available as a byproduct from the oil and gas industry, making the batteries inexpensive to produce. Sulfur is also more environmentally friendly than the metal oxide materials used in lithium-ion batteries.

ADELPHI, Md. -- In recent years, lithium-ion batteries have become better at supplying energy to Soldiers in the field, but the current generation of batteries never reaches its highest energy potential. Army researchers are extremely focused on solving this challenge and providing the power Soldiers demand.

At the U.S. Army Combat Capabilities Development Command's Army Research Laboratory, in collaboration with the University of Maryland, scientists may have found a solution.

"We are very excited to demonstrate a new electrolyte design for lithium ion batteries that improves anode capacity by more than five times compared to traditional methods," said Army scientist Dr. Oleg Borodin. "This is the next step needed to move this technology closer to commercialization."

The team designed a self-healing, protective layer in the battery that significantly slows down the electrolyte and silicon anode degradation process, which could extend the lifespan of next generation lithium-ion batteries.

Their latest battery design increased the number of possible cycles from tens to over a hundred with little degradation. The journal Nature Energy published their findings.

Here's how a battery works. A battery stores chemical energy and converts it into electrical energy. Batteries have three parts, an anode (-), a cathode (+), and the electrolyte. An anode is an electrode through which the conventional current enters into a polarized electrical device. This contrasts with a cathode, through which current leaves an electrical device.

The electrolyte keeps the electrons from going straight from the anode to the cathode within the battery. In order to create better batteries, Borodin said, you can increase the capacity of the anode and the cathode, but the electrolyte has to be compatible between them.

Lithium-ion batteries generally use graphite anodes, which have a capacity of about 370 milliamp hours (mAh) per gram. But anodes made out of silicon can offer about 1,500 to 2,800 mAh per gram, or at least four times as much capacity.

The researchers said silicon particle anodes, as opposed to traditional graphite anodes, provide excellent alternatives, but they also degrade much faster. Unlike graphite, silicon expands and contracts during a battery's operation. As the silicon nanoparticles within the anode get larger, they often crack the protective layer -- called the solid electrolyte interphase -- that surrounds the anode.

The solid electrolyte interphase forms naturally when anode particles make direct contact with the electrolyte. The resulting barrier prevents further reactions from occurring and separates the anode from the electrolyte. But when this protective layer becomes damaged, the newly exposed anode particles will react continuously with electrolyte until it runs out.

"Others have tried to tackle this problem by designing a protective layer that expands when the silicon anode does," Borodin said. "However, these methods still cause some electrolyte degradation, which significantly shortens the lifetime of the anode and the battery."

The joint team at the University of Maryland and the Army Research Laboratory decided to try a new approach. Instead of an elastic barrier, the researchers designed a rigid barrier that doesn't break apart -- even when the silicon nanoparticles expand. They developed a lithium-ion battery with an electrolyte that formed a rigid Lithium Fluoride solid electrolyte interphase, or SEI, when electrolyte interacts with the silicon anode particles and substantially reduced electrolyte degradation.

"We successfully avoided the SEI damage by forming a ceramic SEI that has a low affinity to the lithiated silicon particles, so that the lithiated silicon can relocate at the interface during volume change without damaging the SEI," said Prof. Chunsheng Wang, a professor of Chemical and Biomolecular Engineering at the University of Maryland. "The electrolyte design principle is universal for all alloy anodes and opens a new opportunity to develop high-energy batteries."

The battery design that Borodin and Wang's group conceived demonstrated a coulombic [the basic unit of electric charge] efficiency of 99.9 percent, which meant that only 0.1 percent of the energy was lost to electrolyte degradation each cycle.

This is a significant improvement over conventional designs for lithium-ion batteries with silicon anodes, which have a 99.5-percent efficiency. While seemingly small, Borodin said this difference translates to a cycle life more than five times longer.

"Experiments performed by Dr. Chunsheng Wang's group at the University of Maryland showed that this new method was successful," Borodin said. "However, it was successful not only for silicon but also for aluminum and bismuth anodes, which shows the universality of the principle."

The new design also came with several other benefits. The battery's higher capacity allowed the electrode to be markedly thinner, which made the charging time much faster and battery itself much lighter. In addition, the researchers found that the battery could handle colder temperatures better than normal batteries.

"For regular batteries, colder temperatures slow diffusion and may even freeze the liquids inside the batteries," Borodin said. "But because our design has a much higher capacity, thus ions have to diffuse shorter distances, resulting in a significantly improved low temperature operation, which is important for warfighters operating in cold climates."

The team thanked the ARL Enterprise for Multiscale Modeling of Materials program for its support during the research effort so far.

According to Borodin, the next step in the research is to develop a larger cell with a higher voltage using this design. In light of this goal, the team is currently looking into advancements into the cathode side of the lithium-ion battery.

Researchers from the University of York have recreated how toxins from smoking cause unique patterns of DNA damage. The discovery could help scientists better understand the cause of bladder cancer and the link to smoking.

The causes of bladder cancer remain largely unknown, however smoking is seen as the main risk factor for the disease.

Researchers - led by Dr Simon Baker from the Department of Biology - grew human bladder tissues in the laboratory and exposed them to a common toxin from cigarette smoke. After the tissues were damaged by the smoke toxin, the team analysed all three billion letters of the genetic code (DNA) to find a pattern of changes called a "mutational signature."

Dr Baker said: "Mutational signatures can be used like fingerprints at a crime scene. When we look at the DNA in a cancer we can see the fingerprints of all the criminals involved in causing the damage that led to cancer.

"The DNA damaging event might be exposure to cigarette smoke or UV from the sun but it might also be an unknown event that causes cancer."

"Our study found that the smoke toxin left its distinctive fingerprints on the DNA of bladder tissues grown in the laboratory. However, when we looked at the DNA of patients' bladder cancers the mutational signature, of the smoke toxin, was only responsible for a small amount of the damage.

"So despite smoking being the key risk factor for bladder cancer, direct damage of the DNA by smoke toxins is unlikely to be the main reason for these cancers forming."

It may be that the smoke toxins accelerate other DNA damaging events and attention is now focussing on a family of enzymes called "APOBEC".

APOBEC enzymes destroy viruses by mutating their DNA as part of the body's natural defences against infection, but recent studies suggest they might mistakenly target our own DNA in a number of cancer types. The next stage of the study will be to try and understand how and why APOBEC enzymes become activated in the cells of the bladder.