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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.

Paris, Apr 24: The worldwide death toll from the coronavirus pandemic crossed 190,000 on Friday, with nearly two-thirds of the fatalities in Europe, according to an AFP tally compiled from official sources at 0740 GMT.

A total of 190,089 people have died and 2,698,733 been infected since the virus emerged in China in December. The hardest hit continent is Europe, with 116,221 deaths and 1,296,248 cases.

The country with the most deaths is the United States with 49,963, followed by Italy with 25,549, Spain with 22,157, France with 21,856 and Britain 18,738.

London, Feb 9: A US court has rejected a Turkish attempt to dismiss civil cases brought by protesters who were violently attacked in Washington by Recep Tayyip Erdogan’s security officers.

The incident took place in May 2017 during a visit to the US by the Turkish president. About a dozen bodyguards beat-up a group demonstrating outside the Turkish ambassador’s residence in Washington.

The attack, which was caught on video, left nine people injured and further strained US relations with Turkey.

While criminal charges against the security guards were dropped within a year, around the same time Turkey released a US pastor, the victims pressed ahead with a civil case.

On Thursday, a federal court denied Turkey’s request to have the two cases thrown out on the grounds that it should have sovereign immunity from legal proceedings.

US District Judge Colleen Kollar-Kotelly said the protesters had not posed a threat and were merely gathered on a sidewalk outside the residence at Sheridan Circle when Erdogan’s security burst through a police line and attacked them.

“The Turkish security forces did not have the discretion to violently physically attack the protesters, with the degree and nature of force which was used, when the protesters were standing, protesting on a public sidewalk,” she said. “And, Turkish security forces did not have the discretion to continue violently physically attacking the protesters after the protesters had fallen to the ground or otherwise attempted to flee.”

The judge said Turkey “has not met its burden of persuasion to show that it is immune from suit in these cases.”

The ruling was welcomed by the victims of the attack, which Erdogan stopped to watch as he made his way from his car to inside the residence.