Two journalists shot dead during Facebook Live broadcast

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.

New York, Jan 10: The US's National Transportation Safety Board (NTSB) announced that it has accepted an invitation from Tehran to participate in its investigation into the crash of a Ukrainian plane amid speculations that an Iranian missile might have brought down the plane.

The federal agency said in a statement on Thursday that the Iran Civil Aviation Organization has notified them that they could take part in the investigation of the plane crash that occurred shortly after taking off from Tehran on Wednesday, killing all 176 people on board, reports the Efe news.

"The NTSB has designated an accredited representative to the investigation of the crash," said the independent US government agency tasked with investigating transport accidents.

Since the aircraft was a US-made Boeing 737-800, international regulations allow Washington to be a part of the accident investigation.

However, it remains unclear to what extent the NTSB representative will be able to play an active role in the probe, as US sanctions complicate cooperation with Iran, and the two countries have no diplomatic relations.

The NTSB announcement came hours after US intelligence sources told several media outlets that the Kiev-bound Ukrainian International Airlines (UIA) flight 752 could have been accidentally shot down by an Iranian missile.

Canadian Prime Minister Justin Trudeau later confirmed that his government had "evidence" indicating that the aircraft "was shot down by an Iranian surface to air missile", although he added it may have been unintentional.

The accident occurred on the same day after Iran launched more than a dozen ballistic missiles at two US military bases in Iraq, in retaliation for the killing of Iranian Major General Qasem Soleimani in an American drone attack in Baghdad on January 3.

However, the Iranian authorities have denied that they had accidentally shot down the plane and claimed the accusations were a part of a psychological warfare campaign against Tehran.

Iranian foreign ministry spokesman Abbas Mousavi said they welcomed the presence of experts from countries whose citizens have died in the tragic accident, and requested Trudeau and any other government to provide any information they had regarding the crash.

Davos, Jan 22: President Donald Trump has said that the US is watching the developments between India and Pakistan over Kashmir "very closely" and repeated his offer to "help" resolve the longstanding dispute between the two neighbours as he met Prime Minister Imran Khan on the sidelines of the World Economic Forum here in the Swiss ski resort.

Addressing the media with the Pakistan Prime Minister prior to their private meeting on Tuesday, President Trump asserted that trade and borders were both critical points for discussion, while Khan said that for him, Afghanistan was the top priority.

Trump told Khan, whom he referred to as "my friend", that he would speak to Prime Minister Narendra Modi about the ongoing Kashmir issue. The US president is expected to visit India in the coming weeks, marking his first visit after taking up his post in the White House.

"What's going on between Pakistan and India … if we can help, we certainly will be willing to. We have been watching it very closely and it's an honour to be here with my friend," he said.

"The Pakistan-India conflict is a very big issue for us in Pakistan and we expect the US to always play its part in deescalating the tensions, because no other country can," Khan said.

President Trump has repeatedly offered to mediate following India's August 5 decision to revoke the special status to Jammu and Kashmir and bifurcate the state into two Union Territories, evoking strong reaction from Pakistan which has been trying to internationalise the Kashmir issue.

New Delhi has defended the move, saying Jammu and Kashmir is an integral part of India and the issue was strictly internal to the country, and the special status provisions only gave rise to terrorism in Jammu and Kashmir.

"The country took the decision of abrogation of Article 370, which had only given separatism and terrorism to that state," Prime Minister Narendra Modi said at a function in October last year.

This is the third meeting between Trump and Khan since Pakistan premier assumed office in 2018 and it came against the backdrop of Pakistan Foreign Minister Shah Mehmood Qureshi's recent trip to the US, amid reports that the US and Afghan Taliban were close to striking a peace deal.

"There are issues we want to talk about. The main issue is Afghanistan because it concerns the US and Pakistan. Fortunately, we are on the same page. Both of us are interested in peace there and an orderly transition in Afghanistan with talks with Taliban and the government," Khan said.

When a reporter asked Trump if he would visit Pakistan considering he was already set to visit India, the US president said he was meeting the Pakistan premier in Davos.

"Well, we're visiting right now. So we don't really have to. I wanted to say that from a relationship standpoint, we got a great relationship. From the standpoint our two countries, we're getting along very well. I would say we've never been closer with Pakistan the way we're right now. And this is a big statement," Trump said.

Khan left for Switzerland to attend the World Economic Forum and meet the world leaders, including President Trump, on the sidelines of the annual event which kicked off at the ski resort town of Davos on Tuesday.

The four-day summit marks the 50th anniversary of the forum.

A total of 53 heads of State are on the guest list. Nearly 3,000 participants from 118 countries are expected to attend the event during which political leaders, business executives, heads of international organisations and civil society representatives are set to deliberate on contemporary economic, geopolitical, social and environmental issues.