Nobel Prize in physics awarded to 3 scientists for discoveries in cosmology

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.

Beijing, May 18: China has reported 25 new COVID-19 patients, the health authorities said on Monday, as 14 asymptomatic cases were detected in Wuhan, the first epicentre of the coronavirus where officials are doing mass testing of the city's entire 11 million population, taking the number of such cases in the city to 337, the highest in the country.

The death toll in China remained at 4,634 on Sunday with no new fatalities reported.

China's National Health Commission (NHC) reported seven new confirmed cases of COVID-19 and 18 asymptomatic cases on Sunday.

Jilin province where the government has implemented strict control measures in the last few days following reports of clusters of cases in Jilin city reported two cases on Sunday, while Shanghai city has reported one.

As of Sunday, the overall confirmed cases in China had reached 82,954, including 82 patients who are still being treated, and 78,238 people who have been discharged after recovery.

Also on Sunday, 18 new asymptomatic cases including two from abroad were reported in China, taking the total number under medical observation to 448, the NHC said.

Asymptomatic cases pose a problem as the patients are tested COVID-19 positive but develop no symptoms such as fever, cough or sore throat. However, they pose a risk of spreading the disease to others.

Wuhan which is undergoing mass testing of the city's entire over 11 million population to determine the prevalence of the virus has reported no new confirmed cases, but 14 new asymptomatic infections, taking the number of such cases in the city to 337, the highest in the country, according to the figures released by the local health commission on Sunday.

The death toll in Hubei province stood at 4,512, including 3,869 in Wuhan.

The province so far has reported 68,134 confirmed COVID-19 cases in total, including 50,339 in Wuhan, according to the officials figures.

As the cases dropped, China on Sunday exempted people in Beijing from wearing masks, signalling that the virus is under control in the national capital.

As the virus is abating in the country, China is opening up all its business including entertainment centres like Shanghai Disneyl and to show that it has managed to control the dreaded virus while the world is struggling with it with lockdowns and massive casualties.

The novel coronavirus which originated in Wuhan in December last year has claimed 315,185 lives and infected over 4.7 million people globally, according to Johns Hopkins University data.

Islamabad, Feb 29: A coalition comprising digital media giants Facebook, Google and Twitter (among others) have spoken out against the new regulations approved by the Pakistani government for social media, threatening to suspend services in the country if the rules were not revised, it was reported.

In a letter to Prime Minster Imran Khan earlier this month, the Asia Internet Coalition (AIC) called on his government to revise the new sets of rules and regulations for social media, The News International reported on Friday.

"The rules as currently written would make it extremely difficult for AIC Members to make their services available to Pakistani users and businesses," reads the letter, referring to the Citizens Protection Rules (Against Online Harm).

The new set of regulations makes it compulsory for social media companies to open offices in Islamabad, build data servers to store information and take down content upon identification by authorities.

Failure to comply with the authorities in Pakistan will result in heavy fines and possible termination of services.

It said that the regulations were causing "international companies to re-evaluate their view of the regulatory environment in Pakistan, and their willingness to operate in the country".

Referring to the rules as "vague and arbitrary in nature", the AIC said that it was forcing them to go against established norms of user privacy and freedom of expression.

"We are not against regulation of social media, and we acknowledge that Pakistan already has an extensive legislative framework governing online content. However, these Rules fail to address crucial issues such as internationally recognized rights to individual expression and privacy," The News International quoted the letter as saying.

According to the law, authorities will be able to take action against Pakistanis found guilty of targeting state institutions at home and abroad on social media.

The law will also help the law enforcement authorities obtain access to data of accounts found involved in suspicious activities.

It would be the said authority's prerogative to identify objectionable content to the social media platforms to be taken down.

In case of failure to comply within 15 days, it would have the power to suspend their services or impose a fine worth up to 500 million Pakistani rupees ($3 million).