Sunita Williams unfurls tricolour in space

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.

Beijing, May 9: Mounting a strong defence of the ruling Communist Party of China, President Xi Jinping has said the COVID-19 fight has once again shown that the CPC leadership and the country's socialist political system can overcome any challenge.

Xi's comments came as China faced global criticism for its initial inaction to act against the novel coronavirus, which according to Chinese officials emerged in the central Chinese city of Wuhan in December last year.

Pressure is also mounting on Beijing to agree for an international probe on the origins of the vicious virus, including from the Wuhan Institute of Virology (WIV), as claimed by the US leadership.

China curbed the spread of the coronavirus in over a month and brought COVID-19 under control at its first epicentre in Wuhan in about three months, Xi, also the General Secretary of the CPC, said at a symposium held on Friday to get suggestions from non-ruling Communist Party of China (CPC) parties on COVID-19 prevention and control.

He termed the curbing of the COVID-19 pandemic as "hard-won achievements" for the world's most populous country and the second-biggest economy.

The COVID-19 fight has once again shown that the CPC leadership, China's socialist system and its governance system can overcome any challenge and make big contributions to the progress of human civilisation, he said.

Xi said China had basically curbed the spread of the virus in over one month, managed to bring the daily number of new domestically-transmitted cases down to single digits in about two months, and secured decisive achievements in protecting epicentres Wuhan and Hubei province in about three months.

"For a huge country with 1.4 billion people, these are hard-won achievements," he said

Besides the top CPC officials, the symposium was attended by members of the central committees of non-CPC parties in China, the All-China Federation of Industry and Commerce, and persons without party affiliation.

The speakers at the symposium praised the Chinese leadership in handling the crisis, saying it fully demonstrated the political advantage of China's socialist system and showed that China was a major responsible country.

Xi, who is also the head of the People's Liberation Army, praised China's one-party political system governed by the CPC.

His comments on the country's political system came as Beijing is also defending the role of the CPC as US President Donald Trump and Secretary of State Mike Pompeo have blamed the ruling party for not being transparent in the fight against the pandemic.

Both Trump and Pompeo have been pressing Beijing to allow American experts for a probe on whether the virus emerged from the WIV, China's premier research lab where viruses of different types are reportedly researched.

At the symposium attended by the top CPC officials, Xi's leadership came for praise for successfully handling the situation, the state-run Xinhua news agency reported.

"Attendees noted the major strategic achievements in the COVID-19 fight under the strong leadership of the CPC Central Committee with Comrade Xi Jinping at the core," the report said.

The meeting was held amid reports of murmurs of internal criticism within the CPC about Xi's handling of the coronavirus crisis.

While China's move of handling the coronavirus from January 23 by locking down Hubei province and its capital Wuhan to prevent the spread of the virus and curbing it by deploying 42000 medical personnel has been praised, Beijing is criticised for its slow reaction after it emerged in December last year.

China used less than a week to identify the full genome sequence of the novel coronavirus and isolate the virus strain, produced various testing kits and swiftly selected a number of effective drugs and treatments. Different types of vaccines have also entered clinical trials.

President Xi said during the COVID-19 fight, China upheld the centralised and unified leadership of the CPC and concentrated the nation's best doctors, the most advanced equipment and the most needed resources to treat patients, with all treatment expenses covered by the state.

It managed to maximise the testing and cure rates while minimising the infection and fatality rates.

As of Friday, the COVID-19 death toll in China remained at 4,633 with no new fatalities reported for several days while the total number of cases stood at 82,887. In contrast, Chinese officials point out the death toll in the US which has crossed 75,000 with over 1.2 million cases, besides the mounting global toll.

Almost all countries in the world have been under lockdown for weeks to control the spread of the virus.

Xi called for mobilising the whole society, leveraging the institutional strength of concentrating resources to get things done and tapping the composite national strength as well as closely relying on science and technology.

On international cooperation, Xi said China had helped countries and international organisations to the best of its ability, demonstrating the nation's sense of responsibility as a major and responsible country.

Xi also stressed fixing the shortcomings in the country's major epidemic prevention and control mechanism and for the national public health system to raise the ability to deal with major public health emergencies.

He emphasised on targeted and effective measures to guard against the importation of cases and prevent a resurgence of the epidemic.

Washington, Jun 2: US President Donald Trump said that peaceful protests following the death of African-American man George Floyd in police custody were derailed by acts of domestic terrorism.

"These are not acts of peaceful protests, these are acts of domestic terror - the destruction of innocent life, and the spilling of innocent blood is an offence to humanity and a crime against God," Trump said during a press briefing on Monday.

Trump also added that the chaos is the work of professional agitators and provocateurs - anarchists and the far-left movement Antifa, among others - and put them on notice, vowing to enforce law and order.

He further said, "Those who threaten innocent life and property will be arrested, detained and prosecuted to the fullest extent of the law. I want the organizers of this terror to be on notice that you will face severe criminal penalties and lengthy sentences in jail. This includes Antifa and others who are leading instigators."

The US president also that he is invoking an 1807 law to mobilize the military around the country to "quickly solve the problem."

"I am also taking swift and decisive action to protect our capital Washington DC. As we speak, I am dispatching thousands and thousands of heavily armed soldier, military personnel and enforcement officers to stop the rioting," Trump said during a press briefing.

"I am mobilizing all available federal resources, civilian and military, to stop the rioting and looting, to end the destruction and arson. And to protect the rights of law-abiding Americans, including your Second Amendment rights," he added.

Trump said mayors and governors must establish an "overwhelming law enforcement presence until the violence has been quelled." If the city or state refuses to take the actions, Trump said he would deploy the US military.

Trump on Monday also said that all Americans are rightly 'sickened by the brutal death' of George Floyd and his administration is fully committed to providing justice to George and his family.

"All Americans were rightly sickened and revolted by the brutal death of George Floyd. My administration is fully committed, the justice will be fully served for George and his family and He will not have died in vain," Trump said.

"My first and highest duty as president is to defend and protect the great country and the American people. I have sworn an oath to uphold the laws of our nation and that is exactly what I will do," he added.

After the media address, Trump made a surprise visit to the damaged St Johns church near White House, walking through park violently cleared of protesters. He walked to the church across the street from the White House after tear gas was fired at protesters in the area.