Closely monitoring India-China situation, says US

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.

Oakland, Jun 2: Facebook employees are using Twitter to register their frustration over CEO Mark Zuckerberg's decision to leave up posts by President Donald Trump that suggested protesters in Minneapolis could be shot.

While Twitter demoted and placed a warning on a tweet about the protests that read, in part, that “when the looting starts the shooting starts,” Facebook has let it stand, with Zuckerberg laying out his reasoning in a Facebook post Friday.

“I know many people are upset that we've left the President's posts up, but our position is that we should enable as much expression as possible unless it will cause imminent risk of specific harms or dangers spelled out in clear policies,” Zuckerberg wrote.

Trump's comment evoked the civil-rights era by borrowing a phrase used in 1967 by Miami's police chief to warn of an aggressive police response to unrest in black neighborhoods.

On Monday, Facebook employees staged a virtual “walkout” to protest the company's decision not to touch the Trump posts according to a report in the New York Times, which cited anonymous senior employees at Facebook.

The Times report says “dozens” of Facebook workers “took the day off by logging into Facebook's systems and requesting time off to support protesters across the country." “I work at Facebook and I am not proud of how we're showing up.

The majority of coworkers I've spoken to feel the same way. We are making our voice heard,” tweeted Jason Toff, a director of product management at Facebook who's been at the company for a year.

Toff, who has a verified Twitter account, had 131,400 “likes” and thousands of retweets of his comment. He did not immediately respond to a message seeking comment on Monday.

“I don't know what to do, but I know doing nothing is not acceptable. I'm a FB employee that completely disagrees with Mark's decision to do nothing about Trump's recent posts, which clearly incite violence. I'm not alone inside of FB.

There isn't a neutral position on racism,” tweeted another employee, design manager Jason Stirman.

Stirman did not immediately respond to a request for comment on Monday. Sara Zhang, a product designer at the company, tweeted that Facebook's “decision to not act on posts that incite violence ignores other options to keep our community safe.

The policy pigeon holes us into addressing harmful user-facing content in two ways: keep content up or take it down.” “I believe that this is a self-imposed constraint and implore leadership to revisit the solution,” she continued. Zhang declined to comment to The Associated Press.

Representatives for Facebook did not immediately respond to messages for comment.

Twitter has historically taken stronger stances than its larger rival, including a complete ban on political advertisements that the company announced last November.

That's partly because Facebook, a much larger company with a broader audience,targeted by regulators over its size and power, has more to lose. And partly because the companies' CEOs don't always see eye to eye on their role in society.

Over the weekend, Twitter changed the background and logo if its main Twitter account to black from its usual blue in support of the Black Lives Matter protesters and added a #blacklivesmatter hashtag. Facebook did the same with its own logo on its site, though without the hashtag.

Beijing, Feb 19: The death count from China's new coronavirus epidemic jumped to 2,000 on Wednesday after 132 more people died in Hubei province, the hard-hit epicentre of the outbreak.

In its daily update, the province's health commission also reported 1,693 new cases of people infected with the virus.

This brings the total number of cases in mainland China past 74,000.

Most of the cases are in Hubei, where the virus first emerged in December before spiralling into a nationwide epidemic.

Wednesday's jump in the death count was an increase on Tuesday's figures, although the number of new cases reported in Hubei were the lowest for a week.

A study released by Chinese officials claimed most patients have mild cases of the illness.

Outside of hardest-hit Hubei, which has been effectively locked down to try to contain the virus, the number of new cases has been slowing and China's national health authority has said this is a sign the outbreak is under control.

President Xi Jinping, in a phone call with the British prime minister, said China's measures were achieving "visible progress", according to state media Tuesday.

However, the World Health Organization has cautioned that it was too early to tell if the decline would continue.

On Tuesday the director of a hospital in the central Hubei city of Wuhan became the seventh medical worker to succumb to the COVID-19 illness.