Tropical cyclones

• Tropical cyclones across the globe, except Atlantic hurricanes, are moving closer to land in recent decades, a new study found.
• Tropical cyclones generally have been moving westward by about 30 kilometres per decade since 1982, putting them closer to land and making them more dangerous, a study published in Science said.
• Each decade since the 1980s, an additional two cyclones have come within 200 kilometres of land, the study said.

Ominous trends

• Researchers do not quite know why this is happening, but it adds to other ominous trends in cyclone activity.
• Past studies have found that the most intense storms are getting stronger and storms in general are getting wetter, shifting poleward, moving slower and are keeping their power longer after hitting land.
• But while the new study found storms are getting closer to land, researchers still haven’t seen a significant increase in landfalls, which “is still a puzzle,” said study lead author Shuai Wang, a cyclone scientist at Imperial College in London.

Atlantic zone

• It's mysterious that, unlike other areas, the Atlantic hurricane basin didn’t show any significant westward shift, but that could be because the Atlantic hurricane zone is more closely surrounded by continents, Wang said.
• The busiest tropical cyclone basin is in the western Pacific, where there are the most landfalls and the shift westward is twice as big as the global average.
• Wang and his colleagues are still trying to figure out why this westward shift is happening. Storms generally move east to west because of trade winds in the tropics, so a greater westward shift usually puts them closer to where the land is, Wang said.
• Storms that form just west of land, such as in the Pacific off the California and Mexican coasts, are usually moving away from land already, so this shift doesn’t spare more land.
• Changes in atmospheric currents that steer storms tend to be pushing cyclones farther west, but why is still an open question, Wang said.
• He said it could be only partly explained by some natural long-term climate cycles.

Other factors

• Other shifts in atmospheric patterns have been connected to human-caused climate change and that’s a possible factor in the shift but not something researchers can prove yet, he said.
• Massachusetts Institute of Technology hurricane expert Kerry Emanuel said the study is plausible, especially since scientists have already seen a shift of storms more toward the north and south poles, but it raises questions that require follow up, especially why no corresponding increase in landfalls has been found.

Law to ban Cryptocurrencies

• India plans to introduce a law to ban private cryptocurrencies such as bitcoin and put in place a framework for an official digital currency to be issued by the central bank, according to a legislative agenda listed by the government.

• The law will “create a facilitative framework for the creation of the official digital currency to be issued by the Reserve Bank of India (RBI),” the agenda, published on the lower house website on Friday, showed.
• The legislation, listed for debate in the current Parliamentary session, seeks “to prohibit all private cryptocurrencies in India, however, it allows for certain exceptions to promote the underlying technology of cryptocurrency and its uses,” the government said.
• In mid-2019, a government panel recommended banning all private cryptocurrencies, with a jail term of up to 10 years and heavy fines for anyone dealing in digital currencies.
• The panel had, however, asked the government to consider the introduction of an official government-backed digital currency, to function like bank notes, through the RBI.
• In the central bank had in April 2018 ordered financial institutions to break off all ties with individuals or businesses dealing in virtual currencies such as bitcoin within three months.
• However, in March 2020, the Supreme Court allowed banks to handle cryptocurrency transactions from exchanges and traders, overturning a ban that had dealt the thriving industry a blow.
• Governments around the world have been looking into ways to regulate cryptocurrencies but no major economy has taken the drastic step of placing a blanket ban on owning them, even though concerns have been raised about the misuse of consumer data and its possible impact on the financial system.

How Neutrinos help in the death of massive stars?

• Many stars, towards the end of their lifetimes, form supernovas - massive explosions that send their outer layers shooting into the surrounding space.
• Most of the energy of the supernova is carried away by neutrinos – tiny particles with no charge and which interact weakly with matter. Researching the mechanisms of the so called Type II supernovas, a team from IIT Guwahati has come up with new insights into the part played by neutrinos in this dramatic death of massive stars.
• The collaboration includes astrophysicists from Max Planck Institute, Munich, Germany; Northwestern University, Illinois and University of California, Berkeley, in the U.S.
• All stars burn nuclear fuel in their cores to produce energy.
• The heat generates internal pressure which pushes outwards and prevents the star from collapsing inward due to the action of gravity on its own mass.
• But when the star ages and runs out of fuel to burn, it starts to cool inside.
• This causes a lowering of its internal pressure and therefore the force of gravity wins; the star starts to collapse inwards.
• This builds up shock waves because it happens very suddenly, and the shock wave sends the outer material of the star flying. This is what is perceived as a supernova. This happens in very massive stars.
• In stars that are more than eight times as massive as the Sun, the supernova is accompanied by a collapsing of the inner material of the dying star – this is also known as core collapse supernova or Type II supernova.
• The collapsing core may form a black hole or a neutron star, according as its mass. “Our work is on these core-collapse events of type II supernova,” says Sovan Chakraborty of the physics department of IIT Guwahati, in an email to The Hindu.

Three flavours

• Neutrinos come in three ‘flavours’, another name for ‘types’, and each flavour is associated with a light elementary particle.
• For instance, the electron-neutrino is associated with the electron; the muon-neutrino with the muon and the tau-neutrino with the tau particle.
• As they spew out of the raging supernova, the neutrinos can change from one flavour to another in a process known as neutrino oscillations. As Dr. Chakraborty explains, due to the high density and energy of the supernova, several interesting features emerge as this is a nonlinear phenomenon: “This [phenomenon] may generate neutrino oscillations happening simultaneously over different energies (unlike normal neutrino oscillation), termed collective neutrino oscillation.
• The oscillation result may dramatically change when one allows the evolution with the angular asymmetry, the oscillations can happen at a nanosecond time scale, termed fast oscillation.”
• Models of this process, dubbed the effective two-flavour models, have only taken into account the asymmetry between electron neutrino and the corresponding antineutrino.
• In a paper published in Physical Review Letters, the researchers from IIT Guwahati claim that a three-flavour model is needed to predict well the dynamics of the supernova.

Fast oscillations

• The fast oscillations are important because the researchers find that these can decide the flavour information of the supernova neutrinos.
• So far, this has not been done, and models have only kept terms involving a neutrino and its corresponding anti-neutrino. “We find that fast nonlinear oscillations of neutrinos are sensitive to three flavours, and neglecting the third flavour may yield the wrong answer,” says Dr. Chakraborty.
• “Thus, the presence of …[asymmetry between] the muon neutrinos and antineutrinos will be crucial for the neutrino oscillations, in turn influencing the supernova mechanism.”
• Understanding this is important when one wants to measure the influence of neutrinos and their oscillations on supernova mechanism and heavy element synthesis in stellar environments.

What caused the tilt of Saturn’s rotation axis?

• The tilt of the rotation axis of the gas giant Saturn may in fact be caused by its moons, scientists from CNRS, Sorbonne University and the University of Pisa have reported (Nature Astronomy).
• The current tilt of Saturn's rotation axis is caused by the migration of its satellites, and especially by that of its largest moon, Titan.
• Recent observations have shown that Titan and the other moons are gradually moving away from Saturn much faster than astronomers had previously estimated.
• By incorporating this into their calculations, the researchers concluded that this process affects the inclination of Saturn's rotation axis: as its satellites move further away, the planet tilts more and more.
• In fact, what we see today is merely a transitional stage in this shift. Over the next few billion years, the inclination of Saturn’s axis could more than double.
• The decisive event that tilted Saturn is thought to have occurred relatively recently. For over three billion years after its formation, Saturn’s rotation axis remained only slightly tilted.
• It was only roughly a billion years ago that the gradual motion of its satellites triggered a resonance phenomenon that continues today: Saturn's axis interacted with the path of the planet Neptune and gradually tilted until it reached the inclination of 27 degrees observed today, says a release from CNRS.

China’s nuclear power plant

China National Nuclear Corporation said its first nuclear power unit that uses Hualong One, a third-generation reactor, started commercial operation.

The reactor, located in Fuqing city in China’s southeastern Fujian province, was designed to have a 60-year lifespan, with its core equipment domestically produced. Each unit of the Hualong No. 1 has a capacity of 1.161 million kilowatts and can meet the annual domestic electricity demand of 1 million people in moderately developed countries, according to CNNC.

“With Hualong One online, China is now at the forefront of third-generation nuclear technology in the world, alongside countries like the U.S., France and Russia,” said CNNC President Yu Jianfeng.

A second Hualong One unit is due to be completed later this year.