London stocks hammered as Britain records first virus death

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.

Paris, Apr 24: The worldwide death toll from the coronavirus pandemic crossed 190,000 on Friday, with nearly two-thirds of the fatalities in Europe, according to an AFP tally compiled from official sources at 0740 GMT.

A total of 190,089 people have died and 2,698,733 been infected since the virus emerged in China in December. The hardest hit continent is Europe, with 116,221 deaths and 1,296,248 cases.

The country with the most deaths is the United States with 49,963, followed by Italy with 25,549, Spain with 22,157, France with 21,856 and Britain 18,738.

Days after Twitter accounts of several billionaires were hacked to engineer a crypto scam, Twitter on Saturday said it is embarrassed, disappointed and, more than anything, sorry for what happened with some of its high-profile users as attackers successfully manipulated its employees and used their credentials to access internal systems, including getting through the two-factor protections.

In the first detailed summary of the "social engineering attack" via a crypto scam that hit at least 130 users this week, Twitter said for 45 of those accounts, the attackers were able to initiate a password reset, login to the account and send Tweets.

"We are continuing our forensic review of all of the accounts to confirm all actions that may have been taken. In addition, we believe they may have attempted to sell some of the usernames," the micro-blogging platform said in a statement.

For up to eight of the Twitter accounts involved, the attackers took the additional step of downloading the account's information via "Your Twitter Data" tool.

This is a tool that is meant to provide an account owner with a summary of their Twitter account details and activity.

"We are reaching out directly to any account owner where we know this to be true. None of the eight were verified accounts," said Twitter.

The company said the attackers were not able to view previous account passwords, as those are not stored in plain text or available through the tools used in the attack.

"Attackers were able to view personal information including email addresses and phone numbers, which are displayed to some users of our internal support tools," informed Twitter.

In cases where an account was taken over by the attacker, they may have been able to view additional information, Twitter added, saying its forensic investigation of these activities was still ongoing.

"We are actively working on communicating directly with the account-holders that were impacted".

The company said it will soon restore access for all account owners who may still be locked out as a result of the remediation efforts.

The New York Times reported on Friday that the Twitter crypto scam can be traced back to a group of hackers who congregate online at OGusers.com, a username-swapping community where people buy and sell coveted online handles.

The report said that the Twitter hack is not from Russian, Chinese or North Korean hackers but was done by a group of young people, "one of whom says he lives at home with his mother".