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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.

Singapore, Mar 23: Oil prices fell at the open in Asia on Monday after a trillion-dollar Senate proposal to help the coronavirus-hit American economy was defeated and death tolls soared across Europe and the US.

US benchmark West Texas Intermediate initially tumbled more than three percent but then pulled back some ground to trade 1.5 percent lower, at $22 a barrel.

Brent crude, the international benchmark, fell 4.9 percent to $25 a barrel.

Prices have fallen to multi-year lows in recent weeks as lockdowns and travel restrictions to fight the virus hit demand, and top producers Saudi Arabia and Russia engage in a price war.

The latest drop came after a trillion-dollar Senate proposal to rescue the US economy was defeated after receiving zero support from Democrats, and with five Republicans absent from the chamber because of virus-related quarantines.

The bill had proposed funding for American families, thousands of shuttered or suffering businesses and the nation's critically under-equipped hospitals.

Coronavirus deaths soared across Europe and the United States at the weekend despite heightened restrictions.

The death toll from the virus -- which has upended lives and closed businesses and schools across the planet -- surged to more than 14,300 Sunday, according to an AFP tally.

AxiCorp chief markets strategist Stephen Innes said that "total demand devastation" had set it.

"Oil markets collapsed out of the gate this morning as prices react... to stringent containment lockdown measures," he said.

New Delhi, Jan 11: The Supreme Court is scheduled to hear the curative petition of two death row convicts in 2012 Nirbhaya gang-rape case on January 14.

A five-judge Bench of Justices N V Ramana, Arun Mishra, R F Nariman, R Banumathi and Ashok Bhushan will hear the petition filed by Vinay Sharma and Mukesh.

The duo had moved a curative petition in the top court after a Delhi court issued a death warrant in their name and announced January 22 as the date of their execution.

Besides them, two other convicts named Pawan and Akshay are also slated to be executed on the same day at 7 am in Delhi's Tihar Jail premises.

They were convicted and sentenced to death for raping a 23-year-old woman on a moving bus in the national capital on the night of December 16, 2012.

The victim, who was later given the name Nirbhaya, died at a hospital in Singapore where she had been airlifted for medical treatment.

A curative petition is the last judicial resort available for redressal of grievances. It is decided by the judges in-chamber.

If it is rejected, they are legally bound to move a mercy petition. It is filed before the President who has the power to commute it to life imprisonment.

The court after issuing a black warrant in their name gave them two weeks' time to file both the curative and mercy petition.