Rohingya seemingly face ethnic cleansing: UN rights chief

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, Jul 14: The United States has the biggest Covid-19 testing programme in the world, better than big countries like Russia, China, India and Brazil, President Donald Trump said on Monday, asserting that America has "just about the lowest mortality rate" due to the disease in the world.

"We have one of the lowest mortality rates anywhere," Trump said at a White House roundtable. More than 34 lakh Americans have tested positive for Covid-19 so far and over 1,37,000 have died due to the disease, both of which are the largest numbers among all the countries.

The huge number of positive cases, the president said, is due to the massive testing efforts undertaken by his administration, more extensive than any other country.

"We test more than anybody by far. And when you test, you create cases. So we have created cases. I can tell you that some countries, they test when somebody walks into a hospital sick or walks into maybe a doctor's office, but usually a hospital. That is the testing they do, so they do not have cases, whereas we have all these cases. So, it is a double-edged sword," he said.

At the same time, the United States has the lowest mortality rate or just about the lowest mortality rate due to the disease in the world, Trump added. "We are doing a great job. We are doing very well with vaccines and we are doing very, very well with therapeutics. I think we are going to have some very good information coming out soon," he said in response to a question.

"But we have the best and certainly, by far, the biggest testing programme anywhere in the world. If you tested China or Russia or any of the larger countries, if you just tested India, as an example, the way we test, you would see numbers that would be very surprising. Brazil too. You know, Brazil is going through a big problem, but they do not do testing like we do," Trump said.

"So we do the testing and by doing the testing, we have tremendous numbers of cases. As an example, we have done 45 million tests. If we did half that number, you would have half the cases probably -- around that number. If we did another half of that, you would have half the numbers. Everyone would be saying, 'Oh, we are doing so well on cases'," he added.

Responding to a question, Trump said what China did to the world should not be forgotten.

"I think what China has done to the world with what took place -- the China plague -- you can call it the China virus, you can call it whatever you want to call it. It has about 20 different names. What they did to the world should not be forgotten," he said.

The trade deal with China that was signed early this year remains intact, the president said. "It is intact, they (China) are buying. Whether they buy or not, that is up to them. They are buying," he said.

Jan 6: Senior Bharatiya Janata Party leader Subramanian Swamy on Sunday said the country's economy is not showing good signs though Prime Minister Narendra Modi has manifested tremendous leadership skills in fighting terror and in social welfare projects.

The fiscal decisions of the government have not yielded the desired results, the Rajya Sabha MP said here.

"Modi had shown tremendous leadership skill in fighting terror, in several social areas, micro areas like bringing toilets to every village home. But the economy is a complex system...," he said while taking part in a discussion.

While every minister is talking about a 5 trillion dollar economy by 2024, but the current GDP growth has to be multiplied in four years to achieve that, the former Union minister said.

He said, if wages are slashed as a measure to cope with the situation, labor will become cheap but that will also cut down the people's purchasing power triggering dip in demand, closing down factories and rise in unemployment.

"This is one problem for which you really need an economist," he said.

Swamy said in jest, "I think Modi has one problem with me. Not only I am an economist but also a politician."