Urban density not linked to higher COVID-19 infection, death: Johns Hopkins

Melbourne, Jul 24: Home-made cloth face masks may need a minimum of two layers, and preferably three, to prevent the dispersal of viral droplets associated with Covid-19, according to a study.

Researchers, including those from the University of New South Wales in Australia, noted that viral droplets are generated by those infected with the novel coronavirus when they cough, sneeze, or speak.

As face masks have been proven to protect healthy people from inhaling infectious droplets as well as reducing the spread from those who are already infected, several types of material have been suggested for these, but based on little or no evidence of how well they work, the scientists said.

In the current study, published in the journal Thorax, the researchers compared the effectiveness of single and double-layer cloth face coverings with a surgical face mask (Bao Thach) at reducing droplet spread.

They said the single layer covering was made from a folded piece of cotton T shirt and hair ties, and the double layer covering was made using the sew method described by the US Centers for Disease Control and Prevention (CDC).

The scientists used a tailored LED lighting system and a high-speed camera to film the dispersal of airborne droplets produced by a healthy person with no respiratory infection, during speaking, coughing, and sneezing while wearing each type of mask.

Their analysis showed that the surgical face mask was the most effective at reducing airborne droplet dispersal, although even a single layer cloth face covering reduced the droplet spread from speaking.

But the study noted that a double layer covering was better than a single layer in reducing the droplet spread from coughing and sneezing.

According to the researchers, the effectiveness of cloth face masks is dependent on the number of layers of the covering, the type of material used, design, fit as well as the frequency of washing.

Based on their observations, they said a home made cloth mask with at least two layers is preferable to a single layer mask.

"Guidelines on home-made cloth masks should stipulate multiple layers," the scientists said, adding that there is a need for more research to inform safer cloth mask design.

London, Feb 21: Scientists have discovered a new species of land snail, and have named it Craspedotropis Greta Thunberg in honour of the Swedish activist Greta Thunberg for her efforts to raise awareness about climate change.

According to the study, published in the Biodiversity Data Journal, the newly discovered species belongs to the so-called caenogastropods -- a group of land snails known to be sensitive to drought, temperature extremes, and forest degradation.

The scientists, including evolutionary ecologist Menno Schilthuizen from Naturalis Biodiversity Center in the Netherlands, said the snails were found very close to the research field station at Kuala Belalong Field Studies Centre in Brunei.

They added that the snails were discovered at the foot of a steep hill-slope, next to a river bank, foraging at night on the green leaves of understorey plants.

The effort aided by amateur scientist J.P. Lim, who found the first individual of the snail said, "Naming this snail after Greta Thunberg is our way of acknowledging that her generation will be responsible for fixing problems that they did not create."

"And it's a promise that people from all generations will join her to help," Lim said.

The researchers said they approached Thunberg who said that she would be "delighted" to have this species named after her.

The study work including, fieldwork, morphological study, and classification of identified specimen was carried out in a field centre with basic equipment and no internet access, the scientists said.

According to the study, the work was done by untrained ‘citizen scientists’ guided by experts, on a 10-day taxon expedition.

"While we are aware that this way of working has its limitations in terms of the quality of the output (for example, we were unable to perform dissections or to do extensive literature searches), the benefits include rapid species discovery and on-site processing of materials," the researchers wrote in the study.

Bengaluru, Mar 13: In the wake of fresh cases of Covid-19 reported in Karnataka, Infosys Foundation chairperson Sudha Murty has urged the Karnataka government to take steps to shut malls and theatres, saying the coronavirus multiplies in air-conditioned areas.

In a letter to the government, she said preventive measures should be taken to control the spread of coronovirus before it gets worse.

Murty, who also leads the State government-constituted Karnataka Tourism Task Force, said she has discussed the current situation with Chairman and Executive Director of Narayana Health, Devi Prasad Shetty.

She suggested closure of all schools and colleges with immediate effect, malls, theatres and “all air-conditioned areas where the virus multiplies”, and allow only essential services like pharmacy, grocery and petrol bunks.

“It is not scientifically proven that the virus dies in high temperature,” she said pointing to spread of the virus -- despite heat -- in peak summer in Australia and Singapore, which have “summer all 12 months”.

“I request you to vacate one government hospital with at least 500 - 700 beds for this purpose (to deal with coronavirus cases), which requires oxygen lines and pipes,” she said.

“Infosys Foundation, the philanthropic and CSR arm of software major Infosys, would do the civil work and Devi Shetty has agreed to share resources like medical equipment,” she added.

“We would like to work with the government proactively so that we can prevent this as early as possible,” Sudha Murty said.

The total number of confirmed coronavirus positive cases in Karnataka is five, including the 76-year old man from Kalaburagi who died on Tuesday night.