China Announces 48 High-End Drones For Pak, Days After India's S-400 Deal

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.

Islamabad, Apr 16: The number of coronavirus cases in Pakistan topped 6000 while the death toll due to the virus has reached 117, Dawn reported citing official data on Wednesday.

Over 1,446 people have recovered in the country from the deadly virus that has killed over 1.3 lakh people worldwide.

The total number of cases in the country has reached 6297 with Punjab being the worst affected province with 3,016 cases. Meanwhile, Sindh has 1,688 cases of the deadly virus.

Khyber Pakhtunkhwa has reported 47 new cases of the coronavirus, taking the provincial total to 912. Most of the new cases are of Tableeghi Jamaat members who have travel history.

Balochistan has reported four new cases of COVID-19, taking the provincial total to 281 according to provincial government spokesperson Liaquat Shahwani.

On Tuesday, Prime Minister Imran Khan had announced the extension of the nationwide lockdown with relaxation to some sectors.

Addressing the media in Islamabad on Tuesday, Khan said, "We made the hard decision of imposing lockdown in the country which was very well implemented due to cooperation of the people."

The countrywide lockdown was imposed last month in a bid to stem the spread of coronavirus. Later, a two-week extension was announced in the restrictions until April 14.

British lawmaker Debbie Abrahams' e-Business visa was revoked as she was involved in anti-India activities and the cancellation was conveyed to her on February 14, government sources said on Tuesday.

Asserting that the grant, rejection or revocation of a visa or electronic travel authorisation is the sovereign right of a country, the sources said Abrahams was issued an e-Business visa on October 7 last year which was valid till October 5, 2020 for attending business meetings.

"Her e-Business visa was revoked on February 14, 2020 on account of her indulging in activities which went against India's national interest. The rejection of the e-Business visa was intimated to her on February 14," a source said.

Abrahams, who chairs a British parliamentary group on Kashmir, was denied entry into India upon her arrival at the New Delhi airport on Monday.

Government officials had said on Monday also that she was informed in advance that her e-visa had been cancelled.