Taliban attack prison in Pakistan, free militants

Washington, May 20: The United States recorded another 1,536 coronavirus deaths over the past 24 hours, the Johns Hopkins University tracker said.

That figure, tallied as of 8:30 pm (0030 GMT), raises to 91,845 the total number of COVID-19 deaths in the US.

The US tops the global rankings both for the highest death toll and the highest number of infections, with more than 1.5 million cases.

Beijing, Mar 29: In a rare display of public anger in China, dozens of people in central Hubei province, the epicentre of the coronavirus outbreak till recently, attacked official vehicles after they were stopped from crossing a bridge and travel to neighbouring Jiangxi after the lifting of the lockdown.
Hubei province with over 56 million people was kept under lockdown from January 23 as part of aggressive measures to bring down COVID-19 cases which rapidly spread in the area.

Videos on Chinese social media on Friday showed unprecedented scenes of police from Hubei and Jiangxi clashing on the bridge connecting the two provinces over barricades erected from stopping Hubei people from moving out over fears of coronavirus spreading.

Policemen from both sides argued over how to verify if people were allowed to enter Jiangxi, according to local media reports.

It was a major relief for millions of people in Hubei province, when the Chinese government which kept it under lockdown lifted the restrictions on travel.

The government will permit people from the province to travel if they hold a green health code, meaning no contact with any infected or suspected COVID-19 cases.

But people of Hubei to their shock on Friday found roadblocks on the 1st Yangtze River Bridge that separates Huangmei county in Hubei erected by Huangmei county of Jiangxi province.

In local media reports, witnesses were quoted as saying that Huangmei police in Jiujiang erected roadblocks on the bridge to stop people from Hubei from crossing it, a move they alleged stigmatised them.

Video footage shared online showed rows of police armed with riot shields holding back the crowds, while members of the public could be seen damaging and even overturning police vehicles.

In a clip published by the Huanggang city government, which administers Huangmei, the county's Communist Party chief Ma Yanzhou could be heard speaking to the people through a loud hailer, warning them that by gathering in a large group they were increasing their chances of contracting the virus, Hong Kong-based South China Morning Post reported.

While it is unclear exactly how the clash started, police from the two sides published separate official statements online, which were quickly deleted, it said.

The incident underlines the problems China faces as it seeks a return to normalcy after months of lockdown, the Post said.

After the incident, the governments of Huangmei and Jiujiang on Friday issued a joint statement saying they had agreed to remove the barriers set up to restrict travel during the lockdown, and also to recognise each other's health screening codes to make it easier for people in good health to get to where they needed to be, the Post report said.

An article by the ruling Communist Party of China (CPC) mouthpiece, People''s Daily acknowledged the problems in getting the country back on its feet.

"In the past few days, all walks of life have called for governments to accept workers from Hubei," it said.

"However, it is undeniable that some places, intentionally or not, have set up obstacles for Hubei migrant workers to return to their posts and hold prejudices against them."

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.