China developing stealth drones to evade anti-aircraft missiles

London, May 20: The current physical distancing guidelines of 6 feet may be insufficient to prevent COVID-19 transmission, according to a study which says a mild cough in low wind speeds can propel saliva droplets by as much as 18 feet.

Researchers, including those from the University of Nicosia in Cyprus, said a good baseline for studying the airborne transmission of viruses, like the one behind the COVID-19 pandemic, is a deeper understanding of how particles travel through the air when people cough.

In the study, published in the journal Physics of Fluids, they said even with a slight breeze of about four kilometres per hour (kph), saliva travels 18 feet in 5 seconds.

"The droplet cloud will affect both adults and children of different heights," said study co-author Dimitris Drikakis from the University of Nicosia.

According to the scientists, shorter adults and children could be at higher risk if they are located within the trajectory of the saliva droplets.

They said saliva is a complex fluid, which travels suspended in a bulk of surrounding air released by a cough, adding that many factors affect how saliva droplets travel in the air.

These factors, the study noted, include the size and number of droplets, how they interact with one another and the surrounding air as they disperse and evaporate, how heat and mass are transferred, and the humidity and temperature of the surrounding air.

In the study, the scientists created a computer simulation to examine the state of every saliva droplet moving through the air in front of a coughing person.

The model considered the effects of humidity, dispersion force, interactions of molecules of saliva and air, and how the droplets change from liquid to vapour and evaporate, along with a grid representing the space in front of a coughing person.

Each grid, the scientists said, holds information about variables like pressure, fluid velocity, temperature, droplet mass, and droplet position.

The study analysed the fates of nearly 1,008 simulated saliva droplets, and solved as many as 3.7 million equations.

"The purpose of the mathematical modelling and simulation is to take into account all the real coupling or interaction mechanisms that may take place between the main bulk fluid flow and the saliva droplets, and between the saliva droplets themselves," explained Talib Dbouk, another co-author of the study.

However, the researchers added that further studies are needed to determine the effect of ground surface temperature on the behaviour of saliva in air.

They also believe that indoor environments, especially ones with air conditioning, may significantly affect the particle movement through air.

This work is important since it concerns safety distance guidelines, and advances the understanding of the transmission of airborne diseases, Drikakis said.

United Nations, Jun 19: Half of the world's children -- one billion every year -- are affected by physical, sexual or psychological violence, suffering injuries and death because countries have failed to follow established strategies to protect them, the first report of its kind from the UN has said, with experts noting that the coronavirus-related lockdowns have left far too many youngsters stuck with their abusers.

While nearly all countries (88 per cent) have laws in place to protect minors, less than half (47 per cent) say they strongly enforce them, said the Global Status Report on Preventing Violence Against Children 2020 launched on Thursday.

Because countries have failed to follow established strategies to protect children, about one billion are affected each year by physical, sexual or psychological violence, it said.

"There is never any excuse for violence against children," WHO Director-General Tedros Adhanom Ghebreyesus said.

"We have evidence-based tools to prevent it, which we urge all countries to implement. Protecting the health and well-being of children is central to protecting our collective health and well-being, now and for the future," he said.

The report -- launched by the World Health Organisation, the UNICEF, the UNESCO, the Special Representative of the UN Secretary-General on Violence against Children and the End Violence Partnership -- charted progress in 155 countries against the "INSPIRE" framework, a set of seven strategies for preventing and responding to violence against children.

The report signaled a clear need in all countries to scale up efforts to implement them. It included the first ever global homicide estimates specifically for children under 18 years of age -- previous estimates were based on data that included 18 to 19-year olds.

According to the findings, in 2017, around 40,000 children were victims of homicide.

"Violence against children has always been pervasive, and now things could be getting much worse," UNICEF Executive Director Henrietta Fore said.

"Lockdowns, school closures and movement restrictions have left far too many children stuck with their abusers, without the safe space that school would normally offer. It is urgent to scale up efforts to protect children during these times and beyond, including by designating social service workers as essential and strengthening child helplines," she said.

UNESCO Director-General Audrey Azoulay said during the COVID-19 pandemic, and the related school closures, "we have seen a rise in violence and hate online – and this includes bullying".

"Now, as schools begin to re-open, children are expressing their fears about going back to school. It is our collective responsibility to ensure that schools are safe environments for all children. We need to think and act collectively to stop violence at school and in our societies at large," Azoulay said.

Stay-at-home measures including school closures have limited the usual sources of support for families and individuals such as friends, extended family or professionals.

This further erodes victims’ ability to successfully cope with crises and the new routines of daily life. Spikes in calls to helplines for child abuse and intimate partner violence have been observed, the report said.

While online communities have become central to maintain many children's learning, support and play, an increase in harmful online behaviors including cyberbullying, risky online behavior and sexual exploitation have been identified.

“Whilst this report was being finalised, confinement measures and the disrupted provision of already limited child protection services exacerbated the vulnerability of children to various forms of violence," said Najat Maalla M’jid, Special Representative of the UN Secretary-General on Violence against Children.

Of the INSPIRE strategies, only access to schools through enrolment showed the most progress with 54 per cent of the countries reporting that a sufficient number of children in need were being reached in this way.

Between 32 per cent and 37 per cent of the countries considered that victims of violence could access support services, while 26 per cent of the countries provided programmes on parent and caregiver support; 21 per cent of the countries had programmes to change harmful norms; and 15 per cent of the countries had modifications to provide safe physical environments for children, the report said.

Although a majority of countries (83 per cent) have national data on violence against children, only 21 per cent used these to set baselines and national targets to prevent and respond to violence against children, it added.

The report said about 80 per cent of countries have national plans of action and policies but only one-fifth have plans that are fully funded or have measurable targets. A lack of funding combined with inadequate professional capacity are likely contributing factors and a reason why implementation has been slow.

"Ending violence against children is the right thing to do, a smart investment to make - and it's possible. We can and must create a world where every child can thrive," Howard Taylor of the End Violence Partnership said.