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Moths vs bats: moths use sound to thwart bat attacks

Photograph of the atlas moth on a person's hand.
Photograph of the Atlas moth (Attacus atlas). This large silkmoth has the strongest known wingtip decoy with ripples and folds. Credit: T. Neil

Who would win in a bat-moth fight? A new study has found that moths have more of a leg-up than previously thought, because their wings are structured to mess up the echolocation of bats.

Researchers from the University of Bristol have found that the wingtips of certain species of silkmoth are rippled and folded with unique structures that strongly reflect sound.

“Structurally, the wingtips act as acoustic retroreflectors, reflecting sound back to its source from numerous angles, meaning a bat would be more likely to strike the wingtip over the more vulnerable body of the moth,” explains Marc Holderied, co-author of the study published in Current Biology.

“Wider implications might include improved man-made anti-radar and sonar decoy architectures,” Holderied adds.

Astronomers snap best pics of “dog-bone” asteroid

Like a dog with a bone, astronomers have persevered to take the best images yet of a peculiar asteroid called Kleopatra.

Using the Very Large Telescope (VLT) in Chile, they have obtained the sharpest and most detailed images of the dog-bone-shaped asteroid, plus obtained its 3D shape and mass.

“Kleopatra is truly a unique body in our Solar System,” says Franck Marchis, an astronomer at the SETI Institute in the US and at the Marseille Astrophysics Laboratory, France.

“Science makes a lot of progress thanks to the study of weird outliers. I think Kleopatra is one of those and understanding this complex, multiple asteroid system can help us learn more about our Solar System.”

Marchis co-authored the new study, published in Astronomy & Astrophysics, which gives astronomers hints as to how this asteroid and its two moons formed.

Eleven images of a white asteroid on black background, at different orientations
These eleven images are of the asteroid Kleopatra, viewed at different angles as it rotates. The images were taken at different times between 2017 and 2019 with the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument on ESO’s VLT.  Credit: ESO/Vernazza, Marchis et al./MISTRAL algorithm (ONERA/CNRS)

Too little, too much – how does free time affect your well-being?

A study published in the Journal of Personality and Social Psychology has found that your sense of well-being soars as your free time increases – but only up to a point.

“People often complain about being too busy and express wanting more time. But is more time actually linked to greater happiness?” says lead author Marissa Sharif, from The Wharton School of the University of Pennsylvania, US.

“We found that having a dearth of discretionary hours in one’s day results in greater stress and lower subjective well-being. However, while too little time is bad, having more time is not always better.”

The study was based off data from more than 21,000 Americans, reporting what they had done in the previous 24-hour period along with their sense of well-being. Well-being increased with free time up to about two hours of free time, then levelled off, and declined again after five hours of free time.

Read more: R U OK? Understanding mental health in a global pandemic

“Our findings suggest that ending up with entire days free to fill at one’s discretion may leave one similarly unhappy,” Sharif says. “People should instead strive for having a moderate amount of free time to spend how they want.

“In cases when people do find themselves with excessive amounts of discretionary time, such as retirement or having left a job, our results suggest these individuals would benefit from spending their newfound time with purpose.”

Prehistoric primates had a sweet tooth

3d reconstruction of upper jaw showing cavities in teeth
Part of the upper jaw from Microsyops latidens with two caries (cavities). Credit: Keegan Selig.

You might be able to blame your love of chocolate and sweets on your ancient ancestors, if their dental fossils are anything to go by.

A new study, published in Scientific Reports, has found cavities in the teeth of a prehistoric primate (Microsyops latidens) dating back to 54 million years ago.

This is the earliest known evidence of dental cavities in mammals.

The researchers looked at 1,030 individual teeth and jaw sections from the Southern Bighorn Basin in Wyoming, US, and found that 77 (7.5%) displayed cavities.

They were likely caused by a diet high in fruit or other sugar-rich foods.

The oldest and youngest fossils of those 77 had fewer cavities, which may indicate that the diet of these ancient primates varied over time, possibly due to changing climate and food availability.

Atomically thin semiconductors could power next-gen computers

Researchers from the Australian National University (ANU) have developed a super energy-efficient way to transport data – using semiconductors that are one atom thick, or around 100,000 time thinner than a sheet of paper.

This energy efficiency is thanks to an excited state of matter called an exciton, created when an electron gains energy and jumps to a higher energy level, leaving behind a “hole”.

A schematic showing how polaritons are created in the semiconductor
The process of excitons mixing with light in one-atom thin semiconductors. Credit: ANU

For their semiconductor, the research team used a particular type of material (called a monolayer transition metal dichalcogenide crystal) that has stable excitons at room temperature. In this new study, they demonstrated that by making the excitons interact strongly with light, they formed exciton polaritons, able to efficiently transport data cross the material. It doesn’t give off any heat, meaning energy isn’t wasted.

This is the first time it’s been done in this type of semiconductor at room temperature, which may be hugely useful for reducing energy consumption in computers.

“There are many other options for future research, including the development of energy-efficient sensors and lasers based on this semiconductor technology,” adds ANU’s Elena Ostrovskaya, co-author of the paper published in Nature Communications.

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