Donald Trump lashes out at social media companies after Twitter labels tweets with fact checks

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.

Jun 2: A new female billionaire has emerged from one of Asia's most-expensive breakups.

Du Weimin, the chairman of Shenzhen Kangtai Biological Products Co., transferred 161.3 million shares of the vaccine maker to his ex-wife, Yuan Liping, according to a May 29 filing, immediately catapulting her into the ranks of the world's richest.

The stock was worth $3.2 billion as of Monday's close.

Yuan, 49 this year, owns the shares directly, but signed an agreement delegating the voting rights to her ex-husband, the filing shows. The Canadian citizen, who resides in Shenzhen, served as a director of Kangtai between May 2011 and August 2018. She's now the vice general manager of subsidiary Beijing Minhai Biotechnology Co. Yuan holds a bachelor's degree in economics from Beijing's University of International Business and Economics.

Kangtai shares have more than doubled in the past year and have continued their ascent since February, when the company announced a plan to develop a vaccine to fight the coronavirus. They slipped for a second day Tuesday following news of the divorce terms, losing 3.1% as of 9:43 a.m. in Hong Kong and bringing the company's market value to $12.9 billion.

Du's net worth has now dropped to about $3.1 billion from $6.5 billion before the split, excluding his pledged shares.

The 56-year-old was born into a farming family in China's Jiangxi province. After studying chemistry in college, he began working in a clinic in 1987 and became a sales manager for a biotech company in 1995, according to the prospectus of Kangtai's 2017 initial public offering. In 2009, Kangtai acquired Minhai, the company Du founded in 2004, and he became the chairman of the combined entity.

China's rapidly growing economy has been an engine for the country's richest, and Du is not the only tycoon who's had to pay a steep price for a divorce. In 2012, Wu Yajun, at one point the nation's richest woman, transferred a stake worth about $2.3 billion to her ex-husband, Cai Kui, who co-founded developer Longfor Group Holdings Ltd. In 2016, tech billionaire Zhou Yahui gave $1.1 billion of shares in his online gaming company, Beijing Kunlun Tech Co., to ex-wife Li Qiong after a civil court settlement.

Sometimes, a goodbye can be time-consuming too. South Korean tycoon Chey Tae-won's wife filed a lawsuit in December asking for a 42.3% stake in SK Holdings Co. valued at $1.2 billion. That would make her the second-largest shareholder of the company should she win the case, which is still ongoing.

The most expensive divorce in history is that of Jeff and MacKenzie Bezos. The Amazon.com Inc. founder gave 4% of the online retailer to Mackenzie, who now has a $48 billion fortune and is the world's fourth-richest woman.

Panic gripped big tech firms like Facebook and Twitter which decided to close their offices from Seattle to London as more employees tested positive for the new coronavirus.

Facebook shut its three London offices till Monday after an employee was diagnosed with COVID-19.

The social networking giant told nearly 3,000 employees in London to work from home after an employee, who is based in Singapore but visited the London offices between February 24-26, was diagnosed with the new coronavirus, Sky News reported on Friday.

"An employee based in our Singapore office who has been diagnosed with COVID-19 visited our London offices on February 24-26.

"We are therefore closing our London offices until Monday for deep cleaning and employees are working from home until then," the company said in a statement.

There have been 163 cases of coronavirus so far in the UK.

Earlier, Facebook recommended all its Bay Area employees in the US to work from home. The latest precautions come after San Francisco announced its first two coronavirus cases on Thursday.

Facebook has also shut its Seattle office until Monday after one of its contractors was confirmed to be infected with the virus. The infected contractor last visited the Facebook office on February 21. King County health officials said all Facebook sites should work from home until March 31.

Twitter shut its Seattle office for a 'deep clean' after an employee developed COVID-19 like symptoms though final result was still awaited.

"A Seattle-based employee has been advised by doctor about likely COVID-19, though still awaiting the final testing," Twitter said in a tweet on Friday.

"While the employee has not been at a Twitter office for several weeks and hasn't been in contact w/others, we're closing our Seattle office to deep clean," the company added.

According to The Seattle Times, at least 14 people have died due to COVID-19 in Washington State till date.

Amazon, Microsoft, Google and Facebook have advised their employees in Washington State to work from home.

Apple has reportedly suggested its employees at California campuses to work from home as an "extra precaution" while new coronavirus cases spread on the west coast in the US, especially Seattle area.

Apple's flagship developers' conference WWDC 2020 in June is also at the risk of getting cancelled as the Santa Clara public health department has warned against large public gatherings. The event draws nearly 5,000 developers from across the world.

The US death toll from the new coronavirus has climbed to 14, according to Johns Hopkins' tracker, with 329 cases reported across the country.