'Wasn't kidding,' says Trump as US begins designing Mexican border wall

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 8: Four top Republican senators have urged US President Donald Trump to suspend all-new guest worker visas for 60 days and some of its categories, including the H-1B visa, for at least the next year or until unemployment figures return to normal levels in the country.

The unemployment figures in the US have reached an all-time high due to the coronavirus pandemic. The letter has been signed by Senators Ted Cruz, Tom Cotton, Chuck Grassley and Josh Hawley.

"As you know, more than 33 million Americans have filed for unemployment coverage just since mid-March, and approximately one-fifth of the American workforce is currently out of work. This is a stunning difference compared with the historically-low nationwide unemployment rate of just 3.5 per cent in February this year," they said in their letter to the president on Thursday.

The letter, dated May 7, specifically calls for suspension of all non-immigrant guest worker visas for the next 60 days, followed by a continued suspension of certain categories of new non-immigrant guest worker visas for a year or until the national unemployment figures return to normal levels.

"To protect unemployed Americans in the early stages of economic recovery, we urge you to suspend all non-immigrant guest worker visas for the next 60 days," the senators said.

Exceptions to this suspension should be rare, limited to time-sensitive industries such as agriculture and issued only on a case-by-case basis, when the employers can demonstrate that they have been unable to find Americans to take the jobs, the senators wrote.

After 60 days, the senators urged Trump to continue to suspend new non-immigrant guest workers for a year or until the national unemployment figures return to normal levels, whichever comes first.

"That suspension should, at a minimum, include H-2B visas (non-agricultural seasonal workers), H-1B visas (specialty occupation workers) and the Optional Practical Training (OPT) program (extension of foreign student visas after graduation). We also urge you to suspend the EB-5 immigrant visa program, effective immediately," the lawmakers wrote.

The H-1B work visa for foreign technology professionals is highly popular among Indians and a large number of Indians also opt for the EB-5 investors visa.

The senators argued that there is no reason why unemployed Americans and recent college graduates should have to compete in such a limited job market against an influx of additional H-1B workers, most of whom work in business, technology or STEM fields.

"Temporarily suspending the issuance of new H-1B visas would also protect the hundreds of thousands of H-1B workers and their families already working in the United States -- workers who could otherwise be subject to deportation if they are laid off for more than 60 days," they said.

"Of course, appropriate exceptions could also be crafted to the H-1B program suspension to allow for doctors, nurses and other healthcare professionals who wish to come to the United States to assist in combating the coronavirus pandemic," the senators wrote.

Additionally, the United States ought to suspend its Optional Practical Training (OPT) programme, which allows foreign students in the country to extend their stay after graduation for one to three years to get "experience in the field" by taking jobs here, they wrote.

In 2019, more than 223,000 former foreign students had their OPT applications approved or extended. While the merits of such a programme are subject to debate, there is certainly no reason to allow foreign students to stay for three additional years just to take jobs that would otherwise go to unemployed Americans as the country's economy recovers, the lawmakers said.

The senators also urged Trump to remove the EB-5 visa from the exemptions in his Presidential Proclamation issued on April 22, at least until real reforms are adopted.

The EB-5 programme has long been plagued by scandal and fraud, and criticised as effectively functioning as a pay-for-citizenship scheme in many cases. There is no reason that the programme should receive preferential treatment as opposed to other green card programmes for employment-based immigrants, the lawmakers said.

Beijing, Jan 21: The Chinese official investigating a pneumonia outbreak stemming from a new coronavirus said the disease can spread from person to person but can be halted with increased vigilance, as authorities on Tuesday confirmed a fourth death.

Zhong Nanshan said there was no danger of a repeat of the Severe Acute Respiratory Syndrome (SARS) epidemic that killed nearly 800 people globally during a 2002-2003 outbreak, which started in China, as long as precautions were taken.

"It took only two weeks to identify the novel coronavirus," state news agency Xinhua quoted Zhong as saying late on Monday.

The outbreak was still in its early stages and China had good surveillance and quarantine systems to help control it, he added.

The outbreak has spread from the central city of Wuhan to cities including Beijing and Shanghai, with more than 200 cases reported so far. Four cases have been reported outside China - in South Korea, Thailand and Japan.

Australia on Tuesday said it would screen passengers on flights from Wuhan amid rising concerns that the virus will spread globally as Chinese travellers take flights abroad for the Lunar New Year holiday starting this week.

Authorities around the globe, including in the United States and many Asian countries, have stepped up screening of travellers from Wuhan.

Chinese authorities confirmed a total of 217 cases of the virus in China as of 6 p.m. (1000 GMT) on Monday, state television reported, 198 of which were in Wuhan.

A fourth person died on Jan. 19, the Wuhan Municipal Health Commission said. The 89-year-old man, who had underlying health diseases including coronary heart disease, developed symptoms on Jan. 13 and was admitted to hospital five days later, it added.

Zhong, who is renowned in China for his work fighting SARS in 2003, confirmed that the virus can pass from person-to-person.

Fifteen medical workers in Wuhan had been diagnosed with pneumonia, with one other suspected case, the Wuhan Municipal Health Commission said. Of the infected staff, one was in critical condition.

In Shanghai, officials on Tuesday confirmed a second case involving a 35-year-man who had visited Wuhan in early January, and said they were monitoring four other suspected cases.

The virus causes a type of pneumonia and belongs to the same family of coronaviruses as SARS. Symptoms include fever and difficulty in breathing, which are similar to many other respiratory diseases and pose complications for screening efforts.

The World Health Organisation (WHO) said on Monday an animal source appeared most likely to be the primary origin of the outbreak and that some "limited human-to-human transmission" occurred between close contacts.

The Geneva-based U.N. agency convened an emergency committee for Wednesday to assess whether the outbreak constitutes an international health emergency and what measures should be taken to manage it.

So far, the WHO has not recommended trade or travel restrictions, but a panel of independent experts could do so or make other recommendations to limit spread.