'Bolo' app won't send children's data to us: Google

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.

Paris, Jul 2: Several interacting exoplanets have already been spotted by satellites. But a new breakthrough has been achieved with, for the first time, the detection directly from the ground of an extrasolar system of this type.

An international collaboration including CNRS researchers has discovered an unusual planetary system, dubbed WASP-148, using the French instrument SOPHIE at the Observatoire de Haute-Provence (CNRS/Aix-Marseille Universite).

The scientists analysed the star's motion and concluded that it hosted two planets, WASP-148b and WASP-148c. The observations showed that the two planets were strongly interacting, which was confirmed from other data.

Whereas the first planet, WASP-148b, orbits its star in nearly nine days, the second one, WASP-148c, takes four times longer. This ratio between the orbital periods implies that the WASP-148 system is close to resonance, meaning that there is enhanced gravitational interaction between the two planets. And it turns out that the astronomers did indeed detect variations in the orbital periods of the planets.

While a single planet, uninfluenced by a second one, would move with a constant period, WASP-148b and WASP-148c undergo acceleration and deceleration that provides evidence of their interaction.

The study will shortly be published in the journal Astronomy & Astrophysics.

New Delhi, Mar 14: Excise duty on petrol and diesel was on Saturday hiked by ₹3 per litre as the government looked to mop up gains arising from fall in international oil prices.

Special excise duty on petrol was hiked by ₹2 to ₹8 per litre incase of petrol and to Rs 4 incase of diesel, an official notification said.

Additionally, road cess on petrol was raised by ₹1 per litre each on petrol and diesel to ₹10.

The increase in excise duty would in normal course result in a hike in petrol and diesel prices but most of it would be adjusted against the fall in rates that would have necessitated because of slump in international oil prices.