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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.

New Delhi, Mar 18: As many as 276 Indians have been infected with coronavirus abroad, including 255 in Iran, 12 in UAE and five in Italy, the government informed the Lok Sabha on Wednesday.

In a written reply to a question in the Lok Sabha, Minister of State for External Affairs V Muraleedharan said the total number of Indians infected by coronavirus is 276 — 255 in Iran, 12 in UAE, five in Italy, and one each in Hong Kong, Kuwait, Rwanda and Sri Lanka.

A fourth batch of 53 Indians returned to India from Iran on Monday, taking the total number of people evacuated from the coronavirus-hit country to 389.

Iran is one of the worst-affected countries by the coronavirus outbreak and the government has been working to bring back Indians stranded there. Over 700 people have died from the disease in Iran and nearly 14,000 cases detected.

New Delhi, Jan 13: Walmart, the world’s largest retailer, has fired around 50 of its India executives as part of its restructuring in the country, three sources with direct knowledge said.

The move underscores the struggles Walmart has faced in expanding its wholesale business in India. The Bentonville, Arkansas based company currently operates 28 wholesale stores where it sells goods to small shopkeepers, and not to retail consumers.

The firings mostly affected executives in the company’s real estate division because the growth in the wholesale model has not been that robust, two of the sources said.

“It’s happening because focus is shifting to e-commerce rather than physical (stores),” said one source, who declined to be identified as the decision is not public.

Walmart did not respond to a request for comment.

Walmart has placed bold bets on India’s e-commerce sector. In 2018, it paid $16 billion to acquire a majority stake in India’s online marketplace Flipkart, in its biggest global acquisition.

The second source added that while Walmart could slow down the pace of opening new wholesale stores, the focus will increasingly be on boosting sales through business-to-business and retail e-commerce.

Some of the executives were sacked last week and more could be let go on Monday, two sources said.

In a statement to India’s Economic Times newspaper, which first reported the news, Walmart said it was always looking for ways to operate more effectively and that “this requires us to review our corporate structure to ensure that we are organized in the right way to best meet the needs of our members.”

Walmart has around 600 staff in its India head office out of a total of around 5,300 nationally, one of the sources said.