Culture

Far, far beyond the orbits of the planets lie the hazy contours of the magnetic bubble in space that we call home.

This is the heliosphere, the vast bubble that is generated by the Sun's magnetic field and envelops all the planets. The borders of this cosmic bubble are not fixed. In response to the Sun's gasps and sighs, they shrink and stretch over the years.

Now, for the first time, scientists have used an entire solar cycle of data from NASA's IBEX spacecraft to study how the heliosphere changes over time. Solar cycles last roughly 11 years, as the Sun swings from seasons of high to low activity, and back to high again. With IBEX's long record, scientists were eager to examine how the Sun's mood swings play out at the edge of the heliosphere. The results show the shifting outer heliosphere in great detail, deftly sketch the heliosphere's shape (a matter of debate in recent years), and hint at processes behind one of its most puzzling features. These findings, along with a newly fine-tuned data set, are published in The Astrophysical Journal Supplements on June 10, 2020.

IBEX, short for the Interstellar Boundary Explorer, has been observing the boundary to interstellar space for more than 11 years, showing us where our cosmic neighborhood fits in with the rest of the galaxy.

"It's this very small mission," said David McComas, the principal investigator for the mission at Princeton University in New Jersey. IBEX is just as big as a bus tire. "It's been hugely successful, lasting much longer than anybody anticipated. We're lucky now to have a whole solar cycle of observations."

Mapping the solar system's edge, one particle at a time

The heliosphere is filled with the solar wind, the constant flow of charged particles from the Sun. The solar wind rushes out in all directions, a million miles per hour, until it butts against the interstellar medium, winds from other stars that fill the space between them.

As the Sun wades through the interstellar medium, it generates a hot, dense wave much like the wave at the front of a boat coursing through the sea. Our cosmic neighborhood is called the Local Fluff, for the cloud of superhot gases that blooms around us. Where the solar wind and Local Fluff meet forms the edge of the heliosphere, called the heliopause. Just inside that lies a turbulent region called the heliosheath.

Particles called energetic neutral atoms, or ENAs, that are formed in this distant region of space are the focus of IBEX's surveys. They're created when hot, charged particles like the ones in the solar wind collide with cold neutrals like those flowing in from interstellar space. Zippy solar wind particles can snatch electrons from lumbering interstellar atoms, becoming neutral themselves.

The journey of these particles begins long before IBEX detects them. Past the planets, past the asteroid belt and the Kuiper Belt, to the edge of the heliosphere, it takes about a year for a gust of solar wind to race 100 times the distance between the Sun and Earth. Along the way, the solar wind picks up ionized atoms of interstellar gases that have wriggled in to the heliosphere. The solar wind that arrives at the edge is not the same wind that left the Sun a year before.

Solar wind particles might spend another six months roving the chaos of the heliosheath, the gulf between the heliosphere's two outer boundaries. Inevitably, some collide with interstellar gases and become energetic neutrals. It takes the neutral particles close to another year for the return trip, traversing the space from the edge of the heliosphere to reach IBEX -- if the particles happened to be heading in precisely the right direction. Of all the neutral particles formed, only a few actually make it to IBEX. The whole trip takes two to three years for the highest-energy particles in IBEX's observing range, and even longer at lower energies or more distant regions.

IBEX takes advantage of the fact that neutral atoms like these aren't diverted by the Sun's magnetic field: Fresh neutral particles bound away from collisions in nearly a straight line.

IBEX surveys the skies for the particles, noting their direction and energy. The spacecraft only detects about one every other second. The result is a map of the interstellar boundary, crafted from the same principle a bat uses to echolocate its way through the night: monitor an incoming signal to learn more about one's surroundings. By studying where the neutrals come from, and when, IBEX can trace the remote boundaries of our heliosphere.

"We're so lucky to observe this from inside the heliosphere," said Justyna Sokol, a visiting scientist on the Princeton team. "These are processes that happen at very small distances. When you observe other stars that are very far away, you observe distances of light years, from outside their astrospheres." Even the distance between the Sun and the nose of the heliosphere is tiny compared to many, many light years.

Using IBEX's 11-plus years of data, McComas and his team were able to study changes that evolve over time and are key to understanding our place in space.

The solar wind is constant, but the wind is not steady. When the wind gusts, the heliosphere inflates like a balloon, and neutral particles surge at the outer fringes. When the wind calms, the balloon contracts; neutral particles dwindle. The ensuing seesaw of neutral particles, the scientists reported, consistently echoed two to three years after the changes in the wind -- reflecting their journey to the edge of this balloon and back.

"It takes so many years for these effects to reach the edge of the heliosphere," said Jamey Szalay, another Princeton researcher on the team. "For us to have this much data from IBEX, finally allows us to make these long-term correlations."

Shaping up the heliosphere

From 2009 to 2014, the wind blew fairly low and steady, a gentle breeze. The heliosphere contracted. Then came a surprise swell in the solar wind, as if the Sun heaved a great sigh. In late 2014, NASA spacecraft orbiting Earth detected the solar wind pressure increase by about 50% (it has since remained high for several years).

Two years later, the billowing solar wind led to a flurry of neutral particles in the heliosheath. Another two years later, they filled most of the nose of the heliosphere. Eventually, they crested over the heliosphere's north and south poles.

These changes were not symmetric. Each observed bump traced the quirks of the heliosphere's shape. The scientists were surprised at how clearly they saw the tidal wave of solar wind pushing out the heliopause.

"Time and the neutral particles have really painted the distances in the shape of the heliosphere for us," McComas said.

IBEX still hasn't observed the effects of this cosmic punch from the back end of the heliosphere, the heliotail. That means the tail end is much farther away from the Sun than the front; those particles are on a much longer journey. Maybe the solar wind surge is still hurtling toward the tail, or maybe neutral particles are already on their way back. In the coming years, the IBEX team will be watching for signs of their return from the tail.

"Nature set up this perfect experiment for us to better understand this boundary," Szalay said. "We got to see what happens when this one big thing -- the solar wind push -- changes."

Overall, this paints a picture of the heliosphere that is shaped something like a comet. The shape of the heliosphere has been a matter of debate in recent years. Some have argued our bubble in space is spherical as a globe; others suggested it is closer to a croissant. But in this study, McComas said, IBEX data clearly shows the heliosphere's response to the solar wind push was asymmetric -- so the heliosphere itself must be asymmetric too. The Sun is situated close to the front, and as the Sun hurtles through space, the heliotail trails much farther behind, something like the streaking tail of a comet.

Tackling IBEX's biggest puzzle

IBEX's many years of data have also brought scientists closer to an explanation for one of the heliosphere's more puzzling features, known as the IBEX ribbon. The ribbon remains one of IBEX's biggest discoveries. Announced in 2009, it refers to a vast, diagonal swath of energetic neutrals, painted across the front of the heliosphere. It's long puzzled scientists: Why should any part of the boundary should be so different from the rest?

Over time, IBEX has indicated that what forms the ribbon is very different than what forms the rest of the interstellar sky. It is shaped by the direction of the interstellar magnetic field. But how are ribbon particles produced? Now, the scientists report that it's very likely a secondary process is responsible, causing the journey of a certain group of energetic neutral particles to roughly double.

After becoming energetic neutrals, rather than ricochet back toward IBEX, this group of particles would streak in the opposite direction, across the heliopause and into interstellar space. There, they'd get a taste of the Local Fluff, cruising until some would inevitably collide with passing charged particles, losing an electron once again and becoming tied to the surrounding magnetic field.

Another two years or so pass, and the charged particles might collide yet again with slower peers, stealing electrons like they've done before. After this brief migration beyond the heliosphere, the twice-born energetic neutrals might eventually re-enter, hurtling back toward home.

Extended IBEX data helped the scientists connect the ribbon to the particles' long interstellar tour. Particles forming the ribbon have journeyed some two years more than the rest of the neutral particles observed. When it came to the solar wind spike, the ribbon took another two years after the rest of the heliosphere to even start responding.

Far exceeding its initial mission of two years, IBEX will soon be joined by another NASA mission, IMAP -- short for the Interstellar Mapping and Acceleration Probe, for which McComas also serves as principal investigator. The mission is scheduled to launch in late 2024.

"IMAP presents a perfect opportunity to study, with great resolution and sensitivity, what IBEX has begun to show us, so that we will really get a detailed understanding of the physics out there," McComas said.

Researchers from Kumamoto University, Japan have pinpointed the mechanism that regulates the balance between plant growth and defense. Plants synthesize and accumulate protective hormones to protect them from pathogen infections, but excessive accumulation significantly hinders plant growth. Researchers found that the DEL1 gene plays a role in balancing growth and defense of plants infected with nematodes. This finding is expected to contribute to the improvement of agricultural crop varieties and the identification of infection mechanisms of various pathogens.

Plants grow continuously throughout their life but growth becomes suppressed and energy is put into defense responses, like the synthesis of the defense hormones salicylic acid and lignin, when attacked by pathogens. When the accumulation of salicylic acid and lignin becomes excessive, plants show significant growth inhibition. It is therefore believed that plants keep an appropriate balance between growth and defense. However, this type of balance regulating mechanism has only been reported in leaves; the existence of a similar mechanism in roots was unknown.

To test for a mechanism in roots, researchers infected wild-type and DEL1-deficient Arabidopsis, a plant related to cabbage or mustard frequently used in plant-based genetic research experiments, with Meloidogyne Incognita, a parasitic roundworm that infects roots. After nematode infection, DEL1 deficient plants exhibited excessive salicylic acid accumulation and infected sites turned brown, a strong reaction color, when stained with lignin. Additionally, the DEL1 deficient plant had a higher nematode resistance than the wild type, indicating that the DEL1 gene acts to suppress the defense response against nematodes. Furthermore, when the DEL1 deficient plant was infected with nematodes, significant root growth inhibition was observed.

This is the first study to demonstrate that the DEL1 gene plays an important role in the growth vs defense balancing mechanism in plant roots.

"This study should allow us to develop more diverse strategies for controlling pathogens," said study leader Professor Shinichiro Sawa. "For example, plant varieties that have excellent appearance, taste, and resistance traits often have slow growth and low yield. By focusing on genes involved in growth vs defense balance regulation like the DEL1 gene, increased yields and better plant varieties may be produced. We believe that direct control over DEL1 activity will improve our ability to breed pest resistant, high yield plants."

Science and engineering researchers at the University of Melbourne have been awarded a $3.95 million Australian Government grant to help develop cutting edge space capabilities in Australia.

The funding from the International Space Investment Expand Capability Program will allow researchers to build a small satellite - called SpIRIT - to be launched in space by 2022, in collaboration with multiple Australian space industry companies and the Italian Space Agency.

Associate Professor Michele Trenti from the University's School of Physics is the lead investigator of the Space Industry Responsive Intelligent Thermal (SpIRIT) satellite.

"SpIRIT will be very small - about the size of a shoe box - but powerful," Associate Professor Trenti said. "It will carry innovative X-ray sensors, sophisticated on-board computers and radios, and even a miniaturised electric propulsion engine, so we could well say that we will be building a tiny robotic spaceship.

"It will be the first Australian-made spacecraft to host a foreign space agency payload, with an X-ray detector provided by the Italian Space Agency."

Associate Professor Trenti said SpIRIT will demonstrate that Australian-made spacecraft are internationally competitive, opening new market opportunities.

"SpIRIT will not only benefit Australian industry, it will also contribute to some awesome scientific discoveries," Associate Professor Trenti said. "In particular, SpIRIT will combine its X-ray observations with data from a constellation of six other European satellites to spot cosmic fireworks that can be produced when stars die or collide with each other."

The SpIRIT mission will demonstrate innovative technological elements in the areas of thermal management, real-time communications and on-board autonomous decision capabilities that University of Melbourne researchers will use in future space telescope projects for both Earth and astronomical observations.

SpIRIT is a partnership between the University of Melbourne's Physics and Engineering Schools, Sitael Australia, Inovor Technologies, Neumann Space, and Nova Systems, with support from the Italian and United Kingdom Space Agencies (UK in an advisory role).

Dr Airlie Chapman, senior lecturer in mechatronics from Melbourne School of Engineering and co-investigator on the project, said SpIRIT will increase Australia's reputation in the global space sector, and contribute to training a highly capable future workforce.

"Building an innovative space-ready nanosatellite comes with unique challenges," Dr Chapman said. "This project will help us apply engineering research to break new ground in nanosatellite design, manufacturing and operations, hopefully acting as a guide for Australian aerospace research in the future."

Postgraduate students will have the opportunity to join engineering teams at the University of Melbourne and at industry partners through a paid internship program designed to mentor and inspire future space leaders, concluded Dr Chapman.

Deputy Vice Chancellor (Research) Professor Jim McCluskey has welcomed the grant saying it acknowledges the work of the University to support Australia's space capabilities endeavours.

"SpIRIT is an important partnership that reflects the creativity, relevance and excellence of our researchers. The program will generate wider benefit for Australian businesses, and the next generation of space workforce, researchers and entrepreneurs. This is an outstanding achievement," Professor McCluskey said.

A world-first framework that identifies a health practitioner's readiness to address family violence has been developed in a University of Melbourne-led study funded by the Safer Families Centre.

The model identifies Commitment, Advocacy, Trust, Collaboration, and Health system support (CATCH) as vital in building readiness to deal with family violence. CATCH themes reflect factors that health practitioners felt they needed to be confident about providing sensitive care for survivors.

Experts say the development is timely given the surge in reported family violence incidents during the coronavirus (COVID-19) pandemic, which has also seen a move to telehealth sessions for those seeking professional help.

The lead researcher, Professor Kelsey Hegarty from the University of Melbourne and Royal Women's Hospital, said the CATCH model allowed training and systems to tailor strategies to enable greater readiness to deal with family violence.

"We hope that this will change the way we prepare practitioners for this important role, in Australia and globally," Professor Hegarty said.

"The CATCH model could also prove timely during and following the COVID-19 crisis, as survivors may only be able to see health practitioners during movement restrictions."

Published in PLOS ONE journal, the qualitative meta-synthesis of 47 studies identifies five themes involved in readiness of health practitioners to address family violence.

Co-lead Dr Gemma McKibbin said these factors involved health practitioners having a personal commitment, adopting an advocacy approach, trusting the relationship in the health setting, collaborating with a team, and being supported by the health system.

"It is fundamental that health practitioners are ready to identify and respond to family violence," Dr McKibbin said. "Health practitioners may be the first people to 'name' family violence for victims, which can influence the entire trajectory of women and their children's journey to recovery."

The analysis involved the University of Melbourne, Auckland University of Technology, the University of Bristol, La Trobe University, which are all involved with the Safer Families Centre. It found major gaps remained in knowledge about how best to support and train health practitioners to enable an evidence-based pathway to safety for those experiencing family violence through the health system.

Interview and focus group data was drawn from health practitioners across emergency medicine, primary care, intensive care, obstetrics/gynaecology, maternal and child health, family planning, prenatal and antenatal medicine, mental health, orthopaedics, paediatrics, dentistry, and allied health.

The researchers found a 'ready' health practitioner was motivated to make a difference, knew how to advocate, and felt they were likely to succeed. They also had received encouraging feedback, worked with others and were strongly supported with ongoing training, clinical protocols, tools, and health system leadership.

Professor Hegarty said the model was comprehensive and could improve training in this space.

"Now, more than ever, we need to ensure that health professionals are well equipped to deal with family violence," Professor Hegarty said.

"This could improve survivors' experience within the health system and their overall outcomes."

Most of the studies were from high income countries such as Australia, Canada, the USA, and parts of Europe. Researchers say more work needs to be done in low and middle income countries.

Researchers at Tokyo Institute of Technology (Tokyo Tech) and NEC Corporation have jointly developed a 28 GHz phased-array[1] transceiver supporting dual-polarized MIMO[2] for fifth-generation mobile communications system (5G) radio units. Advances in 5G will benefit an array of industries ranging from healthcare, manufacturing and transportation to education and entertainment that require high bandwidth and high-quality connectivity.

As countries launch or prepare for 5G services, researchers are continuing to step up efforts to facilitate deployment of 5G infrastructure. Dual-polarized phased-array transceivers are an attractive class of antenna systems that can transmit data simultaneously through horizontal and vertical-polarized waves. Numerous studies have shown that dual-polarized MIMO can improve the data rate and spectrum efficiency in 5G radio units. However, one problem encountered with these systems is cross-polarization leakage[3], which results in degradation of signal quality especially in the millimeter wave band.

Now, Kenichi Okada's Lab at Tokyo Tech's Department of Electrical and Electronic Engineering and NEC corporation in Japan have developed a transceiver capable of canceling cross-polarization interference using a built-in so-called horizontal and vertical (H/V) canceller. Tests have shown that the error vector magnitude[4] in 256QAM[5] can be improved from 7.6% to a more desirable, lower figure of 3.3% using this new leakage cancellation technique. "The cancellation signals are generated for horizontal and vertical polarization at the transmission side so that it can cancel the cross-polarization leakage caused by all through the transmitter/receiver chip, package, printed circuit board and antenna," the researchers say.

The transceiver was fabricated using low-cost, mass-producible silicon CMOS[6] technology, occupying an area of just 16 mm2. The researchers anticipate that the new circuitry could be installed in a wide range of applications that will be enabled by 5G in the future. Importantly, they point out that their transceiver will improve spectrum efficiency while keeping equipment size and set-up costs to a minimum.

The findings are being presented at the 2020 Symposia on VLSI Technology and Circuits (VLSI 2020), held online from 14 June. The paper has also been selected as one of the technical highlights at the conference.

New Rochelle, NY, June 16, 2020--COVID-19 is like a heat-seeking missile that targets the most vulnerable. The bull's-eye is environmental justice communities, which are the poorest, the most polluted, and the sickest when it comes to comorbidities. A Roundtable Discussion on this subject is in the current issue of the peer-reviewed journal Environmental Justice. Click here to read the article now.

COVID-19 is a civil rights issue, observes Moderator and Editor-in-Chief Sacoby Wilson, PhD, University of Maryland-College Park. The participants discuss the impact of COVID-19 in the context of issues such as inequality in access to jobs, food, housing, and healthcare, and equity implications in the context of climate change.

"COVID-19 has made many of these issues, like social determinants of health and structural racism, front-page news for America, in human terms, for the first time. I think we have to seize this moment," says Roundtable participant, Stephen Thomas, PhD, Maryland Center for Health Equity.

North America had the T. rex, South America had the Giganotosaurus and Africa the Spinosaurus - now evidence shows Australia had gigantic predatory dinosaurs.

The discovery came in University of Queensland research, led by palaeontologist Dr Anthony Romilio, which analysed southern Queensland dinosaur footprint fossils dated to the latter part of the Jurassic Period, between 165 and 151 million-year-ago.

"I've always wondered, where were Australia's big carnivorous dinosaurs?" Dr Romilio said.

"But I think we've found them, right here in Queensland.

"The specimens of these gigantic dinosaurs were not fossilised bones, which are the sorts of things that are typically housed at museums.

"Rather, we looked at footprints, which - in Australia - are much more abundant.

"These tracks were made by dinosaurs walking through the swamp-forests that once occupied much of the landscape of what is now southern Queensland."

Most of the tracks used in the study belong to theropods, the same group of dinosaurs that includes Australovenator, Velociraptor, and their modern-day descendants, birds.

Dr Romilio said these were clearly not bird tracks.

"Most of these footprints are around 50 to 60 centimetres in length, with some of the really huge tracks measuring nearly 80 centimetres," he said.

"We estimate these tracks were made by large-bodied carnivorous dinosaurs, some of which were up to three metres high at the hips and probably around 10 metres long.

"To put that into perspective, T. rex got to about 3.25 metres at the hips and attained lengths of 12 to 13 metres long, but it didn't appear until 90 million years after our Queensland giants.

"The Queensland tracks were probably made by giant carnosaurs - the group that includes the Allosaurus.

"At the time, these were probably some of the largest predatory dinosaurs on the planet."

Despite the study providing important new insights into Australia's natural heritage, the fossils are not a recent discovery.

"The tracks have been known for more than half a century," Dr Romilio said.

"They were discovered in the ceilings of underground coal mines from Rosewood near Ipswich, and Oakey just north of Toowoomba, back in the 1950s and 1960s.

"Most hadn't been scientifically described, and were left for decades in museum drawers waiting to be re-discovered.

"Finding these fossils has been our way of tracking down the creatures from Australia's Jurassic Park."

Like any cells in the body, cancer cells need sugar ­- namely glucose - to fuel cell proliferation and growth. Cancer cells in particular metabolize glucose at a much higher rate than normal cells. However researchers from USC Viterbi's Mork Family Department of Chemical Engineering and Materials Science have unlocked a weakness in a common type of cancer cell: sugar inflexibility. That is, when cancer cells are exposed to a different type of sugar - galactose - the cells can't adapt, and will die.

The discovery, which could have important implications for new metabolic treatments for cancer, was led by Dongqing Zheng, a PhD student in the lab of Nicholas Graham, assistant professor of chemical engineering and materials science. The research was recently published in the Journal of Cell Science.

The paper describes how oncogenes, the genes that cause cancer, can also lead cancer cells to become inflexible to changes in their sugar supply. Normally, cells grow by metabolizing glucose, but most normal cells can also grow using galactose. However, the team discovered that cells possessing a common cancer-causing gene named AKT cannot process galactose, and therefore they die when exposed to this type of sugar.

Zheng said that galactose is quite structurally similar to the glucose which helps cancer cells thrive, but that it has some differences. Graham said that exposing cells to galactose forces them to do more oxidative metabolism, where oxygen is used to convert sugars into energy, as opposed to glycolytic metabolism, where energy is derived from glucose. Normal cells can metabolize both glucose and galactose, but cancer cells that with an activated AKT signaling pathway, commonly found in breast cancer cells, cannot.

"We hadn't seen research looking at galactose in a cancer context, to see whether specific mutations can cause cancer cause cells to be better or worse at managing that switch between glycolytic and oxidative metabolism," Graham said.

Zheng said that the discovery did not mean that galactose itself would be an effective treatment for AKT-type cancer cells, but that it did uncover a fundamental flaw in these cells, whereby the oxidative state leads to cell death.

"What we're trying to do is to use a systems approach to understand this, so we can use some type of targeted drug or gene therapy that can induce a similar effect and force the cell into this oxidative state," Zheng said.

"Galactose is a model system that we're using to uncover these vulnerabilities in cells that would then lead to future drug development," Graham said. "Our lab will focus on trying to use drugs specifically to do that."

The team's findings also showed that while the oxidative process brought on by galactose did result in cell death in AKT-type cancer cells, when the cells were given a different genetic mutation, MYC, the galactose did not kill the cells.

"So if you had a drug that could inhibit glycolysis, you would give it to a patient that had an AKT mutation," Graham said. "But you wouldn't give it to a patient that had an MYC mutation, because it wouldn't work theoretically for those MYC cells."

The researchers also discovered after around 15 days in galactose, some cancer cells started to reoccur.

"Maybe there is a small sub population that are resistant to the galactose," Zheng said. "The other possibility is that some cancer cells are very resilient and they adapt and reprogram themselves after two weeks exposed to the galactose treatment."

The systems biology approach to cancer treatment is different to traditional treatments like chemotherapy and radiation therapy in that it targets metabolic processes in cancer cells. It aims to identify drugs without a lot of the side effects of traditional chemotherapies that also kill healthy cells, leading to adverse effects such as hair loss. However some resurgence is common in a lot of targeted metabolic treatments for cancer, which demonstrate strong initial results before a partial recurrence of the cells. Graham said that AKT tumors can potentially be targeted using a metabolic treatment like this, in order to initially shrink the tumor, but that the treatment would need to be accompanied by another treatment in a drug cocktail to prevent recurrence and protect against cancer cells mutating and adapting.

Zheng and Graham said the latest research would not have been possible without the work of undergraduate students Jonathan Sussman (biomedical engineering) and Matthew Jeon (chemical engineering and materials science), who assisted with cell counting tasks and proteomics ­- the study of the proteins involved in the cancer cells' metabolism.

Graham said that moving forward, the team's biggest challenge is to figure out which types of combination treatments to apply to test in cancer cells with the AKT gene, to lead to more effective therapeutics.

In the absence of a vaccine or highly effective treatments for COVID-19, combining isolation and intensive contact tracing with physical distancing measures--such as limits on daily social or workplace contacts--might be the most effective and efficient way to achieve and maintain epidemic control, according to new modelling research published in The Lancet Infectious Diseases journal.

Using social-contact data on more than 40,000 individuals from the BBC Pandemic database [1] to simulate SARS-CoV-2 transmission in different settings and under different combinations of control measures, the researchers estimate that a high incidence of COVID-19 would require a considerable number of individuals to be quarantined to control infection. For example, a scenario in which 5,000 new symptomatic cases were diagnosed each day would likely require 150,000-200,000 contacts to be quarantined every day if no physical distancing was in place.

The study is the first time researchers have used social contact data to quantify the potential impact of control measures on reducing individual-level transmission of SARS-CoV-2 in specific settings. They aimed to identify not only what would theoretically control transmission, but what the practical implications of these measures would be in terms of numbers quarantined.

However, the authors note that the model is based on a series of assumptions about the effectiveness of testing, tracing, isolation, and quarantine--for example about the amount of time it takes to isolate cases with symptoms (average 2.6 days) and the likelihood that their contacts adhere to quarantine (90%)--which, although plausible, are optimistic.

"Our findings reinforce the growing body of evidence which suggests that we can't rely on one single public health measure to achieve epidemic control", says Dr Adam Kucharski from the London School of Hygiene & Tropical Medicine, UK. "Successful strategies will likely include intensive testing and contact tracing supplemented with moderate forms of physical distancing, such as limiting the size of social gatherings and remote working, which can both reduce transmission and the number of contacts that need to be traced." [2]

He adds: "The huge scale of testing and contact tracing that is needed to reduce COVID-19 from spreading is resource intensive, and new app-based tracing, if adopted widely alongside traditional contact tracing, could enhance the effectiveness of identifying contacts, particularly those that would otherwise be missed." [2]

In the study, researchers analysed data on how 40,162 people moved about the UK and interacted with others prior to COVID-19 to simulate how combinations of different testing, isolation, tracing, and physical distancing scenarios--such as app-based tracing, remote working, limits on different sized gatherings, and mass population-based testing--might contribute to reducing secondary cases [3]. They also modelled the rate at which the virus is transmitted--known as the reproductive number (R), or the average number of people each individual with the virus is likely to infect at a given moment--under different strategies. To keep the COVID-19 epidemic declining, R needs to be less than 1.

In the model, the secondary attack rate (the probability that a close contact of a confirmed case will be infected) was assumed to be 20% among household contacts and 6% among other contacts. The researchers calculated that, had no control measures been implemented, R would be 2.6--meaning that one infected person would infect, on average, 2-3 more people.

The model suggested that mass testing alone, with 5% of the population undergoing random testing each week (i.e. 460,000 tests per day in UK), would lower R to just 2.5, because so many infections would either be missed or detected too late (table 3 and infographic).

Compared with no control measures, self-isolation of symptomatic cases (at home) alone reduced transmission by an estimated 29% (lowering R to 1.8); whilst combining self-isolation, household quarantine, and tracing strategies could potentially lower transmission by as much as 47% (R 1.4) when using app-based contact tracing (assuming the app is adopted by 53% of the population), and by 64% with manual tracing of all contacts (R 0.94).

Achieving such a thorough level of contact tracing may be impractical, but the new study suggests that a large reduction in transmission could also be achieved by supplementing with moderate physical distancing measures. For example, they estimate that, limiting daily contacts outside home, school, and work to four people (e.g. by restricting mass gatherings) along with manual tracing of acquaintances only (i.e. people they have met before) and app-based tracing, would have the greatest impact, reducing disease spread by 66%, and lowering R to 0.87. However, they note that the effectiveness of manual contact tracing strategies is highly dependent on how many contacts are successfully traced, with a high level of tracing required to ensure R is lower than 1, especially if it takes time to isolate symptomatic cases.

The researchers also modelled the number of contacts that might need to be quarantined under different contact tracing strategies. They estimate that a scenario in which 1,000 new symptomatic cases were reported daily would likely require a minimum of 15,000 contacts quarantined every day (isolation plus app-based testing) and a maximum of 41,000 (isolation plus manual tracing all contacts). This could increase to an average of 150,000-200,000 contacts quarantined daily in a scenario where 5,000 new symptomatic cases were diagnosed each day (table 4).

"Our results highlight several characteristics of SARS-CoV-2 which make effective isolation and contact tracing challenging. The high rate of transmission, the short time between one person becoming infected and infecting another, and transmission that occurs without symptoms all make things difficult", says co-author Dr Hannah Fry from University College London, UK. "If there are a lot of symptomatic COVID-19 cases, then tracing, testing, and trying to quarantine a huge number of contacts will be a big challenge. How well we manage it will affect how and when it is possible to reduce transmission predominantly through targeted isolation and tracing measures or whether ongoing physical distancing measures will be required to control the epidemic." [2]

According to co-author Professor Julia Gog from the University of Cambridge, UK, "Planning for control based on isolation and contact tracing should consider the likely need for large numbers of cases to be tested and also a large number contacts rapidly quarantined. Crucially, this work is able to quantify the scales of what is needed for a successful control strategy involving tracing and isolation by making use of the dataset from the BBC pandemic project. The BBC data gives a uniquely detailed picture of how people in the UK mix and thus the extent of contact tracing necessary if we return to social mixing patterns as they were before the pandemic." [2]

The authors highlight several limitations to their study, including that it did not consider more detailed settings beyond home, school, work, or 'other' categories, or explicitly include imported infections, which may be detected at a different rate to local infections.

Writing in a linked Comment, Professor Raina MacIntyre (who was not involved in the study) from The University of New South Wales, Australia, says, "Whilst the study is specific to the UK, the findings are relevant to all countries. For countries which are opening up for business and resuming social activities, as social contacts increase, non-pharmaceutical interventions become even more critical. It may even be worthwhile for countries to invest in strategies to vastly improve the uptake of contact tracing apps to enable rapid response to resurgence of COVID-19. If you don't trace, you leave a chain of transmission free to grow undetected and exponentially. With 80% of cases being mild, it may take several generations of silent epidemic growth before it is even recognised."

If you want to see one of the wonders of the natural world, just startle a bombardier beetle. But be careful: when the beetles are scared, they flood an internal chamber with a complex cocktail of aromatic chemicals, triggering a cascade of chemical reactions that detonates the fluid and sends it shooting out of the insect's spray nozzle in a machine-gun-like pulse of toxic, scalding-hot vapor. The explosive, high-pressure burst of noxious chemicals doesn't harm the beetle, but it stains and irritates human skin--and can kill smaller enemies outright.

The beetle's extraordinary arsenal has been held up by some as a proof of God's existence: how on earth, creationists argue, could such a complex, multistep defense mechanism evolve by chance? Now researchers at Stevens Institute of Technology in Hoboken, N.J. show how the bombardier beetle concocts its deadly explosives and in the process, learn how evolution gave rise to the beetle's remarkable firepower.

"We explain for the first time how these incredible beetles biosynthesize chemicals to create fuel for their explosions," said Athula Attygalle, a research professor of chemistry and lead author of the work, which appears today in the July 2020 issue of the Science of Nature. "It's a fascinating story that nobody has been able to tell before."

To trace the workings of the beetle's internal chemistry set, Attygalle and colleagues at University of California, Berkeley used deuterium, a rare hydrogen isotope, to tag specially synthesized chemical blends. The team led by Kipling Will then either injected the deuterium-labeled chemicals into the beetles' internal fluids, or mixed them with dog food and fed them to the beetles over a period of several days.

Attygalle's team sedated the bugs by popping them in the freezer, then gently tugged at their legs, annoying the sleepy insects until they launched their defensive sprays onto carefully placed filter papers. The team also dissected some beetles, using human hairs to tie closed the tiny ducts linking their chemical reservoirs and reaction chambers, and sampling the raw chemicals used to generate explosions.

Using mass spectrometers, Attygalle checked the samples sent to Stevens for deuterium-labeled products, enabling him to figure out exactly which chemicals the beetles had incorporated into their bomb-making kits. "People have been speculating about this for at least 50 years, but at last we have a clear answer," Attygalle said. "It turns out that the beetles' biochemistry is even more intricate than we'd thought."

Previously, researchers had assumed that two toxic, benzene-like chemicals called benzoquinones found in the beetles' spray were metabolized from hydroquinone, a toxic chemical that in humans can cause cancer or genetic damage. The team at Stevens showed that in fact just one of the beetle's benzoquinones derived from hydroquinone, with the other springing from a completely separate precursor: m-cresol, a toxin found in coal tar.

It's fascinating that the beetles can safely metabolize such toxic chemicals, Attygalle said. In future studies, he hopes to follow the beetles' chemical supply chain further upstream, to learn how the precursors are biosynthesized from naturally available substances.

The team's findings also show that the beetles' explosives rely on chemical pathways found in many other creepy-crawlies. Other animals such as millipedes also use benzoquinones to discourage predators, although they lack the bombardier's ability to detonate their chemical defenses. Evolutionarily distant creatures such as spiders and millipedes use similar strategies, too, suggesting that multiple organisms have independently evolved ways to biosynthesize the chemicals.

That's a reminder that the bombardier beetle, though remarkable, is part of a rich and completely natural evolutionary tapestry, Attygalle said. "By studying the similarities and differences between beetles' chemistry, we can see more clearly how they and other species fit together into the evolutionary tree," he explained. "Beetles are incredibly diverse, and they all have amazing chemical stories to tell."

BOSTON, MASS. (June 16, 2020) - A new study co-authored by six scientists with the New England Aquarium has found that rehabilitated Kemp's ridley and loggerhead sea turtles experience a substantial stress response when transported to release locations in the southern United States but that the turtles remained physically stable and ready for release.

Every year, dozens and even hundreds of "cold-stunned" turtles are treated at the Aquarium's Quincy Animal Care Center for a variety of life-threatening medical conditions that result from weeks of hypothermia and the inability to feed during stranding season. Typically, the stranding season begins in early November and runs through early January when New England water temperatures quickly turn cold and the turtles get stuck on the north side of Cape Cod. The turtles are then rescued and rehabilitated for two to eight months. When the time comes to be released back into the wild, the turtles must enter the ocean at beaches with appropriate water temperatures, often requiring transportation to southeastern states by climate controlled SUV or van. These transports may take up to 24 hours, and can induce a stress response.

"As for humans, traveling many hours over long distances can be stressful for turtles. We wanted to characterize the degree of the stress response and document whether the turtles were still in good condition after such a long trip," said Dr. Charles Innis, Director of Animal Health at the New England Aquarium.

Until now, the full impact of the transport process was unclear. In this new study, led by Dr. Kathleen Hunt of George Mason University and published in the journal Integrated Organismal Biology, all turtles had stranded in a cold-stunned state along the shore of Cape Cod Bay between October and December of 2011-2017 and were rehabilitated at the Aquarium's Animal Care Center for six to eight months. During trips to release the turtles back into the wild, scientists studied the responses of Kemp's ridley and loggerhead turtles before and after vehicle transport for under six hours, 12 hours, 18 hours, and 24 hours, gathering blood samples.

The researchers found that transport induced a physiological stress response for both sea turtle species. The duration of those transports significantly affected the stress responses, with both species showing more pronounced changes on longer journeys. Importantly, despite the findings, both turtle species in the study remained in good clinical condition based on evaluation of vital signs and blood data, even after 24-hour transport. Nonetheless, the researchers suggest that minimizing transport time, when possible, may help to ensure that rehabilitated turtles are released into the ocean under the best possible conditions.

"Results of this study will be used to ensure that sea turtle transports are conducted under controlled environments and at safe durations," said Connie Merigo, Marine Animal Rescue Department Manager. "This study will be helpful to the global community of sea turtle rehabilitators, veterinarians, researchers and biologists."

WASHINGTON, June 16, 2020 -- Researchers used a computer simulation to show how a flushing toilet can create a cloud of virus-containing aerosol droplets that is large and widespread and lasts long enough that the droplets could be breathed in by others.

With recent studies showing the novel coronavirus that causes COVID-19 can survive in the human digestive tract and show up in feces of the infected, this raises the possibility the disease could be transmitted with the use of toilets.

Toilet flushing creates a great deal of turbulence, and qualitative evidence suggests this can spread both bacteria and viruses. The public, however, remains largely unaware of this infection pathway, since few quantitative studies have been carried out to investigate this possible mechanism.

In the journal Physics of Fluids, by AIP Publishing, precise computer models were used to simulate water and air flows in a flushing toilet and the resulting droplet cloud. The investigators used a standard set of fluid dynamic formulas, known as the Navier-Stokes equations, to simulate flushing in two types of toilet -- one with a single inlet for flushing water, and another with two inlets to create a rotating flow.

The investigators also used a discrete phase model to simulate movement of the numerous tiny droplets likely to be ejected from the toilet bowl into the air. A similar model was used recently to simulate the movement of aerosol droplets ejected during a human cough. (See https://publishing.aip.org/publications/latest-content/six-feet-not-far-enough-to-stop-virus-transmission-in-light-winds/.)

The results of the simulations were striking.

As water pours into the toilet bowl from one side, it strikes the opposite side, creating vortices. These vortices continue upward into the air above the bowl, carrying droplets to a height of nearly 3 feet, where they might be inhaled or settle onto surfaces. These droplets are so small they float in the air for over a minute. A toilet with two inlet ports for water generates an even greater velocity of upward flowing aerosol particles.

"One can foresee that the velocity will be even higher when a toilet is used frequently, such as in the case of a family toilet during a busy time or a public toilet serving a densely populated area," said co-author Ji-Xiang Wang, of Yangzhou University.

The simulations show that nearly 60% of the ejected particles rise high above the seat for a toilet with two inlet ports. A solution to this deadly problem is to simply close the lid before flushing, since this should decrease aerosol spread.

However, in many countries, including the United States, toilets in public restrooms are often without lids. This poses a serious hazard. The investigators also suggest a better toilet design would include a lid that closes automatically before flushing.

What The Study Did: Clinical characteristics and outcomes of patients with COVID-19 at a health system in Detroit are described in this case series, which also provides a comparative analysis of hospitalized and ambulatory patient populations.

Authors: Geehan Suleyman, M.D., of the Henry Ford Hospital in Detroit, 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/jamanetworkopen.2020.12270)

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

WASHINGTON, June 16, 2020 -- Magnetic nanoparticles, a class of nanoparticles that can be manipulated by magnetic fields, have a wide range of technical and biomedical applications, including magnetic hyperthermia, targeted drug delivery, new magnetic storage media and nanorobots. Most commercial nanoparticles do not possess a single magnetic core but have a number of small magnetic crystals called crystallites.

The important question for researchers is how these crystallites behave inside a multicore nanoparticle and how they respond to an applied magnetic field. A paper in the Journal of Applied Physics, from AIP Publishing, compares the effective magnetic moments of different multicore nanoparticle systems and shows that they are magnetic-field dependent.

"The effective magnetic moment of such a multicore nanoparticle depends on various parameters, such as the size of magnetic crystallites, their packing density, core configuration and the magnetic interaction between them," said Frank Ludwig, one of the authors of the paper.

Many experimental findings indicate that the ensemble of crystallites behaves like a single magnetic core with some effective magnetic moment. Research has been directed toward determining how this effective magnetic moment is related to the number and size of crystallites inside one multicore nanoparticle because many applications require a large magnetic moment, which, e.g., determines the strength of the magnetic force needed for their manipulation.

The paper's findings are important for researchers optimizing magnetic nanoparticles for various applications, including magnetic hyperthermia and magnetic drug targeting, two new frontiers in cancer therapy.

In magnetic hyperthermia, the nanoparticles are located at the tumor cells. A magnetic field with a frequency and amplitude that will heat the nanoparticles to a temperature of approximately 42-44 degrees Celsius is applied, which kills the tumor cells.

In magnetic drug targeting, the capsule with drugs and magnetic particles is directed to the tumor by magnetic field gradients. When they arrive at the tumor, the drugs are released from the capsule by various techniques. Targeted drug therapy can result in dramatic reduction of doses and side effects versus traditional chemotherapy.

Technical applications of nanoparticles range from new magnetic storage media to nanorobots. Storage media made of nanoparticles are much smaller than existing media and can store greater amounts of data. Nanorobots are machines that can build and manipulate things precisely at an atomic level and can be used in a wide variety of contexts such as miniscule sensors that monitor blood chemistry.

Ludwig said continuing to gain a better understanding of the effective magnetic moment of multicore nanoparticles and, especially, its field dependence is essential for both basic science and applications.

One group of neurons controls various types of sighing, but they receive their instructions from different areas of the brain depending on the reason for the sigh, according to a study scheduled to publish June 16 in the journal Cell Reports.

Humans and other mammals sigh automatically once every few moments­ to maintain proper lung function. This so-called basal sighing is part of the normal breathing process and happens automatically, without us having to think about it. But beyond serving an essential physiological purpose, sighs also occur as behavioral responses to emotions ranging from stress and annoyance to relief.

"We want to understand how all of these diverse inputs, both emotional and physiological, lead to the same behavioral output," said Peng Li, a physiologist and assistant professor at the University of Michigan Life Sciences Institute.

Understanding the brain's control of emotions is a central goal of neurobiology and psychiatry, but it is difficult due to the challenges in teasing out emotional brain states and their complex outputs.

Because sighs offer a simple, measurable output from the brain, Li and his colleagues use them to learn more about how neural circuits communicate to regulate behavioral responses. They investigate how distinct neural circuits enable the brain to control sighing and breathing in different contexts, by studying the circuits in mice--which also exhibit both basal and emotional sighing and have brains that are architecturally similar to those of humans.

Previously, Li and colleagues identified the neurons and pathways that regulate basal sighing. In this newest study, the researchers traced up from these so-called NMB-neurons (short for neurons expressing Neuromedin B) to see what signals they were receiving when mice were under stress, and found a dozen forebrain regions that send direct inputs to the sigh-control center.

When the mice were confined to a small space, inducing a claustrophobic-like state, their sighing rate increased by two to three times. Using genetic tools, the researchers identified another type of neurons in one of the forebrain regions, called hypocretin-expressing (HCRT) neurons, that were firing under stress and sending signals to the NMB-neurons. The researchers then artificially activated the HCRT-neurons, without confining the mice, and saw the same change in sighing rate.

When the researchers silenced the NMB-neurons, both basal sighing and stress-induced sighing drastically decreased in the mice. When they silenced only the HCRT-neurons, however, only the stress-induced sighing decreased while basal sighing was unaffected.

The researchers found that HCRT-neurons also were responsible for an increased breathing rate when the mice were under confinement stress. Since NMB-neurons only control sighing, and not regular breathing, this finding indicates that the HCRT-neurons are sending signals to other parts of the brain simultaneously to activate different stress-induced behaviors.

"So we've found the circuit that regulates all types of sighing, but activates sighs for different reasons using input signals from different parts of the brain. And we found another group of neurons that induces sighing in response to this claustrophobic stress, but also regulates other claustrophobia-related outputs," said Li, who is also an assistant professor at the U-M School of Dentistry and Medical School.

"These findings give us clues about how the brain is wired to control various behavioral and physiological responses to emotions."