Russia, North Korea to challenge US President Donald Trump overseas

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.

Dubai/Washington, Jan 7: Iran's Supreme Leader Ayatollah Ali Khamenei wept in grief with hundreds of thousands of mourners thronging Tehran's streets on Monday for the funeral of military commander Qassem Soleimani, killed by a U.S. drone on U.S. President Donald Trump's orders.

The coffins of General Qassem Soleimani and Iraqi militia leader Abu Mahdi al-Muhandis, who also died in Friday's attack in Baghdad, were draped in their national flags and passed from hand to hand over the heads of mourners in central Tehran.

Responding to Trump's threats to hit 52 Iranian sites if Tehran retaliates for the drone strike, Iran's President Hassan Rouhani pointedly wrote on Twitter: "Never threaten the Iranian nation." And Soleimani's successor vowed to expel U.S. forces from the Middle East in revenge.

Khamenei, 80, led prayers at the funeral, pausing as his voice cracked with emotion. Soleimani, 62, was a national hero in Iran, even to many who do not consider themselves supporters of Iran's clerical rulers.

Aerial footage showed people, many clad in black, packing thoroughfares and side streets in the Iranian capital, chanting "Death to America!" - a show of national unity after anti-government protests in November in which many demonstrators were killed.

The crowd, which state media said numbered in the millions, recalled the masses of people that gathered in 1989 for the funeral of the Islamic Republic's founder, Ayatollah Ruhollah Khomeini. Soleimani, architect of Iran's drive to extend its influence across the Middle East, was widely seen as Iran's second most powerful figure behind Khamenei.

His killing of Soleimani has prompted concern around the world that a broader regional conflict could flare.

Trump on Saturday vowed to strike 52 Iranian targets, including cultural sites, if Iran retaliates with attacks on Americans or U.S. assets, and stood by his threat on Sunday, though American officials sought to downplay his reference to cultural targets. The 52 figure, Trump noted, matched the number of U.S. Embassy hostages held for 444 days after the 1979 Iranian Revolution.

Rouhani, regarded as a moderate, responded to Trump on Twitter.

"Those who refer to the number 52 should also remember the number 290. #IR655," Rouhani wrote, referring to the 1988 shooting down of an Iranian airline by a U.S. warship in which 290 were killed.

Trump also took to Twitter to reiterate the White House stance that "Iran will never have a nuclear weapon" but gave no other details.

'ACTIONS WILL BE TAKEN'

General Esmail Ghaani, Soleimani's successor as commander of the Quds Force, the elite unit of Iran's Revolutionary Guards charged with overseas operations, promised to "continue martyr Soleimani's cause as firmly as before with the help of God, and in return for his martyrdom we aim to rid the region of America."

"God the Almighty has promised to take martyr Soleimani's revenge," he told state television. "Certainly, actions will be taken."

Other political and military leaders have made similar, unspecific threats. Iran, which lies at the mouth of the key Gulf oil shipping route, has a range of proxy forces in the region through which it could act.

Iran's demand for U.S. forces to withdraw from the region gained traction on Sunday when Iraq's parliament passed a resolution calling for all foreign troops to leave the country.

Iraqi caretaker Prime Minister Abdel Abdul Mahdi told the U.S. ambassador to Baghdad on Monday that both nations needed to implement the resolution, the premier's office said in a statement. It did not give a timeline.

The United States has about 5,000 troops in Iraq.

Soleimani built a network of proxy militia that formed a crescent of influence - and a direct challenge to the United States and its regional allies led by Saudi Arabia - stretching from Lebanon through Syria and Iraq to Iran. Outside the crescent, Iran nurtured allied Palestinian and Yemeni groups.

He notably mobilised Shi'ite Muslim militia forces in Iraq that helped to crush ISIS, the Sunni militant group that had seized control of swathes of Syria and Iraq in 2014.

Washington, however, blames Soleimani for attacks on U.S. forces and their allies.

The funeral moves to Soleimani's southern home city of Kerman on Tuesday. Zeinab Soleimani, his daughter, told mourners in Tehran that the United States would face a "dark day" for her father's death, adding, "Crazy Trump, don't think that everything is over with my father's martyrdom."

NUCLEAR DEAL

Iran stoked tensions on Sunday by dropping all limitations on its uranium enrichment, another step back from commitments under a landmark deal with major powers in 2015 to curtail its nuclear programme that Trump abandoned in 2018.

In response, European signatories may launch a dispute resolution process against Iran this week that could lead to a renewal of the United Nations sanctions that were lifted as part of the deal, European diplomats said on Monday.

Diplomats said France, Britain and Germany could make a decision ahead of an EU foreign ministers' meeting on Friday that would assess whether there were any ways to salvage the deal.

After quitting the deal, the United States imposed new sanctions on Iran, saying it wanted to halt Iranian oil exports, the main source of government revenues. Iran's economy has been in freefall as the currency has plunged.

Trump adviser Kellyanne Conway said on Monday that he was still confident he could renegotiate a new nuclear agreement "if Iran wants to start behaving like a normal country."

Tehran has said Washington must return to the existing nuclear pact and lift sanctions before any talks can take place.

The United States advised American citizens in Israel and the Palestinian territories to be vigilant, citing the risk of rocket fire amid heightened tensions. As a U.S. ally against Iran, Israel is concerned about possible rocket attacks from Gaza, ruled by Iranian-backed Palestinian Islamists, or major Iran proxy Hezbollah in Lebanon.

Democratic critics of Trump have said the Republican president was reckless in authorising the strike, with some saying his threat to hit cultural sites amounted to a vow to commit war crimes. Trump also threatened sanctions against Iraq and said Baghdad would have to pay Washington for an air base in Iraq if U.S. troops were required to leave.

Geneva, May 27: The number of confirmed cases of COVID-19 worldwide has increased by nearly 100,000 over the past 24 hours to surpass 5.4 million, the World Health Organisation (WHO) said.

According to the WHO, the global case tally currently stands at 5,404,512 -- a rise by 99,780 over the past day.

The death count worldwide amounts to 343,514 -- an increase by 1,486.

Most cases of infection are recorded in the Americas -- 2,454,452, with 143,739 deaths.