Imran Khan taken off US-bound plane in Toronto

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 21: US President Donald Trump has made yet another tall claim about the size of the crowd that will welcome him in Ahmedabad, saying Prime Minister Narendra Modi has told him that there will 10 million(1 crore) people to greet him on his arrival for his maiden visit to India.

President Trump and First Lady Melania are scheduled to travel to Ahmedabad, Agra and New Delhi on February 24 and 25.

Speaking to reporters at the Joint Base Andrews in Maryland on Tuesday, Trump said that Modi told him that "we'll have 7 million people between the airport and the event."

"So it's going to be very exciting. But he says between the stadium and the airport, we'll have about 7 million people. So it's going to be very exciting. I hope you all enjoy it," he said.

On Thursday, Trump upped the crowd size by three million at a 'Keep America Great' rally in Colorado.

"I hear, they are going to have 10 million people. They say anywhere from six to 10 million people are going to be showing up along the route to one of the largest stadiums in the world, the largest cricket stadium in the world, which is brand new and beautiful," said Trump, who is seeking reelection in the November presidential polls.

But according to a top civic official in Ahmedabad, the total population of the city is only around 70 lakh.

The authorities believe that between one to two lakh people are expected to line up along the 22-km route of the road show by Modi and Trump from the airport to the Motera cricket stadium, said to be the world's largest.

"We believe that around one to two lakh people will gather to welcome the dignitaries during the road show," Ahmedabad Municipal Commissioner Vijay Nehra said on Thursday, contradicting the claims made by the US President.

As per the road show route plan, Trump and Modi will first reach the Sabarmati Ashram, a place closely associated with Mahatma Gandhi, from Ahmedabad airport.

Addressing his supporters, Trump spoke about his India visit and said the "Namaste Trump" rally in Ahmedabad would spoil him.

"Prime Minister Modi said, we will have 10 million people greet you. Here's my problem. We have a packed house. We have a lot of people, thousands of people that couldn't get in. It's going to look like peanuts from now on," he said.

"I'll never be satisfied with the crowd. If we have 10 million people in India, how can I be satisfied when we fill up like a 60,000-seat stadium? I am getting spoiled," Trump said.

One of Trump's supporters from the audience then suggested that he build a bigger stadium.

Washington, May 1:The novel coronavirus, that has killed over 230,000 people globally so far and has shattered economies, emerged from a virology lab in the Wuhan city of China, US President Donald Trump claimed Thursday with a high degree of confidence.

"Yes, I have. Yes, I have," Trump told reporters at the East Room of the White House when asked if he has seen anything at this point that gives him a high degree of confidence that the Wuhan Institute of Virology is where the virus originated.

The president, however, refuse to provide any details, except for saying that investigations are on and it would be out soon.

Asked what gave him a high degree of confidence that the virus originated from the Wuhan Institute of Virology, he said, "I can't tell you that. I'm not allowed to tell you that."

The president, however, did not hold his Chinese counterpart Xi Jinping responsible for this. "I don't want to say that, I don't want to say that, but certainly it could have been stopped. It came out of China and it could have been stopped and I wish they had stopped it and so does the whole world wish they had stopped it."

Reiterating that this is something that could have been contained at Wuhan ground zero, he said that China could have contained it. "They were either unable to, or they chose not to. And the world has suffered greatly."

One of two things happened, he reasoned. "They either didn't do it and you know they couldn't do it from a competent standpoint or they let it spread and I would say probably it got out of control."

"But there's another case that how come they stopped all of the planes and all of the traffic from going into China, but they didn't stop the planes and the traffic from coming into the United States and from coming into all over Europe," he said, citing the example of Italy, the hardest-hit European country.

"This country (the US) is very lucky and I'm very lucky that I put the ban on China, as you know, very early on. In January, we put the ban on China and that was a very early day. That wasn't a late day, that was an early day. Then, we later put the ban on in Europe," he said.

Before holding them accountable, Trump said he wants to find out what happened. "I think we'll be able to get a very good -- a very powerful definition of exactly what happened. We're working on it strongly now and I think it's going to be very powerful," he said.

"But they could have stopped it. They are a very brilliant nation, scientifically and otherwise. It got loose, let's say, and they could have capped it. They could have stopped it, but they didn't. And they stopped the planes from going to China, but they didn't stop them from going to the rest of the world. What was that all about?” he asked.

"We should have the answer to that in the not-too-distant future and that will determine a lot how I feel about China," Trump said.

When asked if President Xi misled him, Trump said, "Something happened. I don't say misleading or not. I'll let you know that. I mean, I'll be able to give you that answer at some point in the hopefully not-too-distant future."

The entire world has suffered as a result of this, he said.

"We have had tremendous death and tremendous sorrow, sadness, and nobody's ever seen anything like it. So, have most of the countries of the world. They've suffered tremendously. It's something that is going to have to be dealt with. We'll have to see," said the president.