US president pays surprise visit to Afghanistan

London, Jun 4: Meghan, Britain's Duchess of Sussex, has spoken about events following the death of George Floyd saying she was sorry that children had to grow up in a world where racism still existed and that current events in the United States were "devastating".

"I know you know that black lives matter," Meghan said in a video she recorded for students graduating from her old high school in Los Angeles which was aired on Wednesday.

The death of Floyd has become the latest flashpoint for long-simmering rage over police brutality against African Americans and led to nationwide protests, some violent, with curfews imposed in some cities to quell the disorder.

"For the past couple of weeks I've been planning on saying a few words to you for your graduation and as we've all seen over the last week what is happening in our country, and in our state and in our home town of LA is absolutely devastating," said Meghan, whose mother is African American and father is white.

"First thing I want to say to you is that I'm sorry, I'm so sorry that you have to grow up in a world where this is still present," she said in her message to the girls at the Immaculate Heart High School.

The duchess, a former US actress and wife of Queen Elizabeth's grandson Prince Harry, said she wanted to say "the right thing" and was nervous her words would be "picked apart".

"The only wrong thing to say is to say nothing. Because George Floyd's life mattered, and Breonna Taylor's life mattered, and Philando Castile's life mattered and Tamir Rice's life mattered and so did so many other people whose names we know, and whose names we do not know," she said.

Britain's royal family by tradition does not comment on political issues. However, Meghan and Harry stepped down from their official royal roles at the end of March and are now living in Los Angeles with their baby son Archie.

In her message, the 38-year-old reflected on her own memories of the 1992 LA riots.

"Those memories don't go away and I can't imagine that at 17 or 18 years old, which is how old you are now, that you would have to have a different version of that same type of experience," she said.

"That's something you should have an understanding of, but an understanding of as a history lesson not as your reality. So I'm sorry that in a way we have not gotten the world to the place you deserve it to be."

Geneva, Jun 24: The global cumulative count of confirmed coronavirus cases is approaching nine million, with 133,326 cases recorded over the past day, the World Health Organisation (WHO) said in its daily situation report on Tuesday.

Over the past 24 hours, 3,847 people died from COVID-19 worldwide, taking the cumulative death toll to 469,587 fatalities, according to the report.

The global case total has now reached 8,993,659.

The Americas still account for the majority of cases and deaths -- 4.4 million and 224,207, respectively.

The United States remains the country with the highest count of cases and fatalities -- 2.3 million and 119,761, respectively.

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.