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, Mar 2: A global agency says the spreading new virus could make the world economy shrink this quarter, for the first time since the international financial crisis more than a decade ago.

The Organization for Economic Cooperation and Development says Monday in a special report on the impact of the virus that the world economy is still expected to grow overall this year and rebound next year.

But it lowered its forecasts for global growth in 2020 by half a percentage point, to 2.4 per cent, and said the figure could go as low as 1.5 per cent if the virus lasts long and spreads widely.

The last time world GDP shrank on a quarter-on-quarter basis was at the end of 2008, during the depths of the financial crisis. On a full-year basis, it last shrank in 2009.

The OECD said China's reduced production is hitting Asia particularly hard but also companies around the world that depend on its goods.

It urged governments to act fast to prevent contagion and restore consumer confidence.

The Paris-based OECD, which advises developed economies on policy, said the impact of this virus is much higher than past outbreaks because "the global economy has become substantially more interconnected, and China plays a far greater role in global output, trade, tourism and commodity markets."

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".