Over 100 killed as building collapses in Dhaka; rescuers pull 150 survivors from rubble

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, May 29: Reiterating his offer to mediate on the border dispute between India and China, US President Donald Trump has said that he spoke with Narendra Modi about the "big conflict" and asserted that the Indian Prime Minister is not in a "good mood" over the latest flare-ups between the two countries.

Speaking with the reporters in the Oval Office of the White House on Thursday, Trump said a "big conflict" was going on between India and China.

"I like your prime minister a lot. He is a great gentleman," the president said.

"Have a big conflict …India and China. Two countries with 1.4 billion people (each). Two countries with very powerful militaries. India is not happy and probably China is not happy," he said when asked if he was worried about the border situation between India and China.

"I can tell you; I did speak to Prime Minister Modi. He is not in a good mood about what is going on with China," Trump said.

A day earlier, the president offered to mediate between India and China.

Trump on Wednesday said in a tweet that he was "ready, willing and able to mediate" between the two countries.

Responding to a question on his tweet, Trump reiterated his offer, saying if called for help, "I would do that (mediate). If they thought it would help" about "mediate or arbitrate, I would do that," he said.

India on Wednesday said it was engaged with China to peacefully resolve the border row, in a carefully crafted reaction to Trump's offer to arbitrate between the two Asian giants to settle their decades-old dispute.

"We are engaged with the Chinese side to peacefully resolve it," External Affairs Ministry Spokesperson Anurag Srivastava said, replying to a volley of questions at an online media briefing.

While the Chinese Foreign Ministry is yet to react to Trump's tweet which appears to have caught Beijing by surprise, an op-ed in the state-run Global Times said both countries did not need such a help from the US President.

"The latest dispute can be solved bilaterally by China and India. The two countries should keep alert on the US, which exploits every chance to create waves that jeopardise regional peace and order," it said.

In Beijing, Chinese Foreign Ministry spokesman Zhao Lijian said on Wednesday that both China and India have proper mechanisms and communication channels to resolve the issues through dialogue and consultations.

Trump previously offered to mediate between India and Pakistan on the Kashmir issue, a proposal which was rejected by New Delhi.

The situation in eastern Ladakh deteriorated after around 250 Chinese and Indian soldiers were engaged in a violent face-off on the evening of May 5 which spilled over to the next day before the two sides agreed to "disengage" following a meeting at the level of local commanders.

Over 100 Indian and Chinese soldiers were injured in the violence.

The incident in Pangong Tso was followed by a similar incident in north Sikkim on May 9.

Doha, Feb 29: The United States signed a landmark deal with the Taliban on Saturday, laying out a timetable for a full troop withdrawal from Afghanistan within 14 months as it seeks an exit from its longest-ever war.

President Donald Trump urged the Afghan people to embrace the chance for a new future, saying the deal held out the possibility of ending the 18-year conflict.

"If the Taliban and the government of Afghanistan live up to these commitments, we will have a powerful path forward to end the war in Afghanistan and bring our troops home," he said on the eve of the event in Doha.

Secretary of State Mike Pompeo arrived in the Qatari capital to witness the signing of the accord, while Defence Secretary Mark Esper was in Kabul for a separate joint declaration with the Afghan government.

The agreement is expected to lead to a dialogue between the Kabul government and the Taliban that, if successful, could ultimately see the Afghan war wind down.

But the position of the Afghan government, which has been excluded from direct US-Taliban talks, remains unclear and the country is gripped by a fresh political crisis amid contested election results.

The United States and its allies will withdraw all their forces from Afghanistan within 14 months if the Taliban abide by the Doha agreement, Washington and Kabul said in a joint statement.

After an initial reduction of troops to 8,600 within 135 days of Saturday's signing, the US and its partners "will complete the withdrawal of their remaining forces from Afghanistan within 14 months... and will withdraw all their forces from remaining bases", the declaration stated.

The Doha accord was drafted over a tempestuous year of dialogue marked by the abrupt cancellation of the effort by Trump in September.

The signing comes after a week-long, partial truce that has mostly held across Afghanistan, aimed at building confidence between the warring parties and showing the Taliban can control their forces.

NATO Secretary General Jens Stoltenberg heralded the agreement as a "first step to lasting peace".

"The way to peace is long and hard. We have to be prepared for setbacks, spoilers, there is no easy way to peace but this is an important first step," the Norwegian former prime minister told reporters in Kabul.

Since the US-led invasion that ousted the Taliban after the September 11, 2001 attacks, America has spent more than $1 trillion in fighting and rebuilding in Afghanistan.

About 2,400 US soldiers have been killed, along with unknown tens of thousands of Afghan troops, Taliban fighters and Afghan civilians.

The insurgents said they had halted all hostilities Saturday in honour of the agreement.

"Since the deal is being signed today, and our people are happy and celebrating it, we have halted all our military operations across the country," Taliban spokesman Zabihullah Mujahid told AFP.

Close to 30 nations were represented at Saturday's signing in the Qatari capital.

While Kabul will not be represented at the Doha ceremony, set for 1245 GMT, it will send a six-person taskforce to the Qatari capital to make initial contact with the Taliban political office, established in 2013.

Any insurgent pledge to guarantee Afghanistan is never again used by jihadist movements such as Al-Qaeda and the Islamic State group to plot attacks abroad will be key to the deal's viability.

The Taliban's sheltering of Al-Qaeda was the main reason for the US invasion following the 9/11 attacks.

The group, which had risen to power in the 1990s in the chaos of civil war, suffered a swift defeat at the hands of the US and its allies. They retreated before re-emerging to lead a deadly insurgency against the new government in Kabul.

After the NATO combat mission ended in December 2014, the bulk of Western forces withdrew from the country, leaving it in an increasingly precarious position.

While Afghans are eager to see an end to the violence, experts say any prospective peace will depend on the outcome of talks between the Taliban and the Kabul government.

But with President Ashraf Ghani and rival Abdullah Abdullah at loggerheads over contested election results, few expect the pair to present a united front, unlike the Taliban, who would then be in a position to take the upper hand in negotiations.