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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.

United Nations, Mar 21: The UN has called on all nations to stop the use of capital punishment or put a moratorium on it, a day after four men convicted of gang-raping and murdering a 23-year-old woman were hanged in India.

Seven years after the rape and murder of the young medical student, who came to be known as 'Nirbhaya', sent shock waves across the country, the four convicts - Mukesh Singh (32), Pawan Gupta (25), Vinay Sharma (26) and Akshay Kumar Singh (31) - were hanged to death on Friday at 5.30 am in New Delhi's Tihar Jail.

Responding to the hanging, UN Secretary-General Antonio Guterres' spokesperson Stephane Dujarric said the world organisation calls on all nations to stop the use of capital punishment or put a moratorium on it.

"Our position has been clear, is that we call on all States to halt the use of capital punishment or at least put a moratorium on this," Dujarric said at the daily press briefing on Friday.

The horrific gang-rape and murder of the physiotherapy intern on December 16, 2012, who came to be known as Nirbhaya, the fearless, had seared the nation's soul and triggered countrywide outrage.

This was the first time that four men have been hanged together in Tihar Jail, South Asia's largest prison complex that houses more than 16,000 inmates.

The executions were carried out after the men exhausted every possible legal avenue to escape the gallows. Their desperate attempts only postponed the inevitable by less than two months after the first date of execution was set for January 22.

The execution of the four convicts brings the curtains down on the case that shook not just India but also the world with the details of its brutality The widespread protests subsequently paved the way for a change in India's rape laws.

Washington, Mar 18: Hundreds of distressed Indian students, stuck in the Philippines, are seeking help through video messages as they are unable to fly back home due to the travel restrictions imposed by India to contain the spread of the deadly novel coronavirus, according to friends and relatives of some of these students in the US.

The Indian government on Tuesday banned the entry of passengers from Afghanistan, Philippines and Malaysia to India with immediate effect amid stepped up efforts against the spread of COVID-19.

In a video message by one of these students Akhil Bala Nair, around 200 Indian students had booked their flight tickets for India in the next few days. But all of them have been cancelled due to the new policy.

Most of the students, she said, had booked their flights for March 17 and rest were schedule to travel to India on March 19 and 20. But the flights were cancelled and scores of Indian students are now stuck at the airport in Manila, Nair said in the video message sent to Prem Bhandari, head of the Jaipur Foot USA.

“It is need of the hour that the Indian government send a plane to bring these Indian students back home,” Bhandari, who in the past has worked for the cause of the Indian diaspora, and who was approached by these students told PTI.

According to these students, some 100 of them have been at the airport since Tuesday.

They all have confirmed tickets but the airport authorities are not allowing them to check in because of the new travel regulations.

While the airport authorities have asked them to go back to their respective place of residence, the students said they were unable to travel because of the absence of local taxi or shared ride services.

The students said that they are running out of time as the Philippines government has given them 72 hours time to exit the country, which started from March 16, after which the country will go into lockdown.

“This means we would not be able to travel anywhere outside Philippines after March 20,” Nair said in her message.

The students said that there are many of them who have applied for renewal of their visas and are unable to travel to India.

There are nearly 1,000 Indian students presently in Manila who are willing to travel back home, they said.

Meanwhile, the Indian Embassy in Manila, in a tweet, said that they, along with the Ministry of External Affairs, are trying to work out a solution.

“It is requested to all to kindly have patience,” the embassy said.