American mathematicians solve Ramanujan's “deathbed” puzzle

New Delhi, May 28: Twitter CEO Jack Dorsey today reinforced his stance on pointing out "incorrect or disputed information about elections globally", a day after US President Donald Trump threatened to shutter social media over Twitter's actions on his posts.

Mr Dorsey appealed to "leave our employees out of this" as the face-off with Mr Trump is likely to escalate.

"Fact check: there is someone ultimately accountable for our actions as a company, and that's me. Please leave our employees out of this. We'll continue to point out incorrect or disputed information about elections globally. And we will admit to and own any mistakes we make," Mr Dorsey tweeted.

"This does not make us an 'arbiter of truth.' Our intention is to connect the dots of conflicting statements and show the information in dispute so people can judge for themselves. More transparency from us is critical so folks can clearly see the why behind our actions," said the Twitter CEO.

Fact check: there is someone ultimately accountable for our actions as a company, and that's me. Please leave our employees out of this. We'll continue to point out incorrect or disputed information about elections globally. And we will admit to and own any mistakes we make.

— jack (@jack) May 28, 2020

"Per our Civic Integrity policy (https://help.twitter.com/en/rules-and-policies/election-integrity-policy), the tweets yesterday may mislead people into thinking they don't need to register to get a ballot (only registered voters receive ballots). We're updating the link on

@realDonaldTrump tweet to make this more clear," Mr Dorsey tweeted.

Twitter had tagged two of Mr Trump's tweets in which he claimed that more mail-in voting would lead to what he called a "rigged election" this November. There is no evidence that attempts are being made to rig the election, and under the tweets Twitter posted a link which read: "Get the facts about mail-in ballots."

Five states in the US already conduct elections primarily by mail-in vote: Utah, Colorado, Hawaii, Washington and Oregon.

For years, Twitter has been accused of ignoring the US President's violation of platform rules with his daily, often hourly barrages of personal insults and inaccurate information sent to more than 80 million followers, news agency AFP reported.

But Twitter's slap on the wrist was enough to drive Mr Trump into a tirade - on Twitter - in which "Republicans feel that Social Media Platforms totally silence conservatives voices. We will strongly regulate, or close them down, before we can ever allow this to happen," Mr Trump said.

He said that an increase in mail-in ballots - seen in some states as vital for allowing people to avoid crowds during the COVID-19 pandemic - will undermine the election.

"It would be a free for all on cheating, forgery and the theft of Ballots," wrote Mr Trump, whose re-election campaign has been knocked off track by the coronavirus crisis. His torrent of angry tweets earned a top-10 trending hashtag: #TrumpMeltdown.

Facebook chief Mark Zuckerberg also waded in to the row, telling Fox News that his social network - still the biggest in the world - has a different policy. "I just believe strongly that Facebook should not be the arbiter of truth of everything that people say online," Mr Zuckerberg said in a snippet of the interview posted online Wednesday by Fox.

"I think, in general, private companies, especially these platform companies, shouldn't be in the position of doing that," he said.

 he claimed that the political right in the US is being censored.

"Republicans feel that Social Media Platforms totally silence conservatives voices. We will strongly regulate, or close them down, before we can ever allow this to happen," Mr Trump said.

He said that an increase in mail-in ballots - seen in some states as vital for allowing people to avoid crowds during the COVID-19 pandemic - will undermine the election.

"It would be a free for all on cheating, forgery and the theft of Ballots," wrote Mr Trump, whose re-election campaign has been knocked off track by the coronavirus crisis. His torrent of angry tweets earned a top-10 trending hashtag: #TrumpMeltdown.

Facebook chief Mark Zuckerberg also waded in to the row, telling Fox News that his social network - still the biggest in the world - has a different policy. "I just believe strongly that Facebook should not be the arbiter of truth of everything that people say online," Mr Zuckerberg said in a snippet of the interview posted online Wednesday by Fox.

"I think, in general, private companies, especially these platform companies, shouldn't be in the position of doing that," he said.

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, Jul 7: President Donald Trump on Tuesday formally started the withdrawal of the United States from the World Health Organization, making good on threats to deprive the UN body of its top funding source over its response to the coronavirus.

Public health advocates and Trump's political opponents voiced outrage at the departure from the Geneva-based body, which leads the global fight on maladies from polio to measles to mental health -- as well as Covid-19, at a time when cases have again been rising around the world.

After threatening to suspend the $400 million (Dh1.47 billion) in annual US contributions and then announcing a withdrawal, the Trump administration has formally sent a notice to UN Secretary-General Antonio Guterres, a State Department spokesperson said.

The withdrawal is effective in one year -- July 6, 2021 -- and Joe Biden, Trump's presumptive Democratic opponent, is virtually certain to stop it and stay in the WHO if he wins the November election.

A spokesman for Guterres and the global health body itself confirmed that the United States, a key founding WHO member, gave its notice.

In a speech earlier in the day, WHO chief Tedros Adhanom Ghebreyesus said of Covid-19, "National unity and global solidarity are more important than ever to defeat a common enemy."

In line with conditions set when the WHO was set up in 1948, the United States can leave within one year but must meet its remaining assessed financial obligations, the UN spokesman said.

'Total control'

In late May, Trump said that China exerted "total control" over the WHO and accused the UN body led by Tedros, an Ethiopian doctor and diplomat, of failing to implement reforms.

Blaming China for the coronavirus, Trump, a frequent critic of the UN, said the United States would redirect funding "to other worldwide and deserving, urgent, global public health needs."

Democratic lawmakers have accused Trump of seeking to deflect criticism from his handling of the pandemic in the United States, which has suffered by far the highest death toll of any nation despite the president's stated hope that the virus will disappear.

"To call Trump's response to Covid chaotic and incoherent doesn't do it justice," said Senator Robert Menendez, the top Democrat on the Foreign Relations Committee.

"This won't protect American lives or interests -- it leaves Americans sick and America alone," he wrote on Twitter.

Representative Ami Bera, himself a physician, said that the United States and World Health Organization had worked "hand in hand" to eradicate smallpox and nearly defeat polio.

"Our cases are increasing," Bera said of Covid-19. "If the WHO is to blame: why has the US been left behind while many countries from South Korea to New Zealand to Vietnam to Germany return to normal?"

Even some of Trump's Republican allies had voiced hope that he was exerting pressure rather than making a final decision to abandon the World Health Organization.

The investigative news outlet ProPublica reported last month that most of Trump's aides were blindsided by the WHO withdrawal announcement, which he made during an appearance about China. 

The Trump administration has said that the WHO ignored early signs of human-to-human transmission in China, including warnings from Taiwan -- which, due to Beijing's pressure, is not part of the UN body.

While many public health advocates share some criticism of the WHO, they question what other options the world body had other than to work with China, where Covid-19 was first detected late last year in the city of Wuhan.

The anti-poverty campaign ONE said the United States should work to reform, not abandon, the WHO.

"Withdrawing from the World Health Organization amidst an unprecedented global pandemic is an astounding action that puts the safety of all Americans the world at risk," it said.