Oil prices fall as US-China tensions offset coronavirus hope

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.

Washington, Feb 27: President Donald Trump has said that the US' relationship with India is "extraordinary" right now and a lot of progress was made in bilateral ties during his maiden official visit to the country where America will be doing a lot of business.

Talking to reporters, after his return from India on Wednesday, Trump said, "He (Prime Minister Narendra Modi) is a great gentleman, a great leader. It's an incredible country."

President Trump visited India from February 24 to 25. He was accompanied by first lady Melania Trump, daughter Ivanka Trump, son-in-law Jared Kushner and the top brass of his administration, including national security advisor Robert O'Brien.

They visited Ahmedabad, Agra and New Delhi before leaving for Washington on Tuesday.

During his stay, he addressed a massive rally in Ahmedabad, visited Agra and held official meetings in New Delhi.

The US President was feted at the world's largest cricket stadium in the "Namaste Trump" event in Ahmedabad and was cheered by tens of thousands of people.

"We were treated very, very well and we really enjoyed it. A lot of tremendous progress was made in terms of relationship - our relationship with India is extraordinary right now," he said.

"We are going to be doing a lot of business with India, they are sending billions and billions of dollars now to the United States," Trump said in response to a question.

In a tweet, his daughter Ivanka said that, Trump announced that US international development finance corporation "will establish a permanent presence in India to strengthen our economic ties, improve development plus further women's economic empowerment through WGDP (Women's Global Development and Prosperity Initiative)!"

On her arrival from India, she thanked PM Modi for "your warm hospitality as we visited your beautiful country and celebrated the strength, spirit and unity of the US and India!"

"Throughout our visit we saw monumental achievements of human creativity and proof of the infinite capacity of the human heart!" she said.

The first lady tweeted two pictures of her with Trump facing the Taj Mahal in Agra.

"One of the Seven Wonders of the World, the breathtaking Taj Mahal!" she said.

President Trump "reaffirmed the strong strategic partnership, vibrant economic ties and expanding security relationship between our two countries. Wonderful trip, but glad to be home! Thank you India!" said White House press secretary Stephanie Grisham.

During the visit, India and the US on Tuesday finalised defence deals worth $3 billion under which 30 military helicopters will be procured from two American defence majors for Indian armed forces.

The deals will include procurement of 24 MH-60 Romeo helicopters by India from the US at a cost of $2.6 billion. Another contract to acquire six AH-64E Apache helicopters for $800 million from the US is also on the table.

Beijing, Jun 4: Around 40 students and staff members of a primary school in China were stabbed by a security guard, official media reported today.

The incident happened at a school in China's Guangxi province, state-run China Daily said in a brief report.

Further details about the attack are awaited.

Knife attacks by disgruntled people have been taking place in different parts of China in the past few years, reported news agency Press Trust of India.

The attackers targeted mainly kindergarten and primary schools besides public transport, the news agency reported.