Imran Khan's ex-wife Reham Khan leaves Pakistan over threats

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, Jul 20: Two coronavirus vaccine candidates have proven safe for humans and produced strong immune reactions among patients involved in separate clinical trials, doctors said on Monday.

The first trial among more than 1,000 adults in Britain found that the vaccine induced "strong antibody and T cell immune responses" against the novel coronavirus.

A separate trial in China involving more than 500 people showed most had developed widespread antibody immune response.

The studies, published in The Lancet medical journal, constitute a major step on the road towards a COVID-19 vaccine that is effective and safe for widespread use.

The authors of the studies said that they encountered few adverse side-effects from the vaccine candidates.

However, they cautioned that more research was needed, particularly among older adults, who are disproportionately at risk of dying of COVID-19.

Co-author Sarah Gilbert from the University of Oxford said the results "hold promise".

"If our vaccine is effective, it is a promising option as these types of vaccine can be manufactured at large scale."

Seoul/South Korea, Apr 27: North Korean leader Kim Jong Un is "alive and well", a top security adviser to the South's President Moon Jae-in said, downplaying rumours over Kim's health following his absence from a key anniversary.
"Our government position is firm," said Moon's special adviser on national security Moon Chung-in, in an interview with CNN on Sunday. "Kim Jong Un is alive and well."

The adviser said that Kim had been staying in Wonsan -- a resort town in the country's east -- since April 13, adding: "No suspicious movements have so far been detected."

Conjecture about Kim's health has grown since his conspicuous absence from the April 15 celebrations for the birthday of his grandfather Kim Il Sung, the North's founder -- the most important day in the country's political calendar.

Kim has not made a public appearance since presiding over a Workers' Party politburo meeting on April 11, and the following day state media reported him inspecting fighter jets at an air defence unit.

North Korean leader Kim Jong Un was not gravely ill, two South Korean government sources said on Tuesday, following reports he had undergone a cardiovascular procedure and was now in "grave danger."

His absence unleashed a series of unconfirmed media reports over his condition, which officials in Seoul previously poured cold water on.

"We have nothing to confirm and no special movement has been detected inside North Korea as of now," the South's presidential office said in a statement last week.

South Korea's unification minister Kim Yeon-chul reiterated Monday that remained the case, adding the "confident" conclusion was drawn from "a complex process of intelligence gathering and assessment".

'Grave danger'

Daily NK, an online media outlet run mostly by North Korean defectors, has reported Kim was undergoing treatment after a cardiovascular procedure earlier this month.

Citing an unidentified source inside the country, it said Kim, who is in his mid-30s, had needed urgent treatment due to heavy smoking, obesity and fatigue.

Soon afterwards, CNN reported that Washington was "monitoring intelligence" that Kim was in "grave danger" after undergoing surgery, quoting what it said was an anonymous US official.

US President Donald Trump on Thursday rejected reports that Kim was ailing but declined to state when he was last in touch with him.

On Monday, the official Rodong Sinmun newspaper reported that Kim had sent a message of thanks to workers on the giant Wonsan Kalma coastal tourism project.

It was the latest in a series of reports in recent days of statements issued or actions taken in Kim's name, although none has carried any pictures of him.

Satellite images reviewed by 38North, a US-based think tank, showed a train probably belonging to Kim at a station in Wonsan last week.

It cautioned that the train's presence did not "indicate anything about his health" but did "lend weight" to reports he was staying on the country's eastern coast.

Reporting from inside the isolated North is notoriously difficult, especially regarding anything to do with its leadership, which is among its most closely guarded secrets.

Previous absences from the public eye on Kim's part have prompted speculation about his health.

In 2014 he dropped out of sight for nearly six weeks before reappearing with a cane. Days later, the South's spy agency said he had undergone surgery to remove a cyst from his ankle.