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Mice move their ears, cheeks and eyes to convey emotion.Credit: Getty

Researchers have used a machine-learning algorithm to decipher the seemingly inscrutable facial expressions of laboratory mice. For example, a mouse experiencing pleasure pulls its nose down towards its mouth, and pulls its ears and jaw forwards. By contrast, when in pain, it pulls back its ears and bulks out its cheeks, and sometimes squints. The work “is an important first step” in understanding some of the mysterious aspects of emotions and how they manifest in the brain, says neuroscientist David Anderson.

Nature | 4 min read

Reference: Science paper

After a long and contentious struggle, mathematician Shinichi Mochizuki has had his 600-page proof of the abc conjecture — one of the biggest open problems in number theory — accepted by a journal. If confirmed to be true, the proof confirms a profound link between the addition and multiplication of integer numbers. Critics have complained that the proof is impenetrable, and it was largely deemed flawed after two authoritative mathematicians circulated a rebuttal in 2018. Some also lament the poor optics of publishing the paper in a journal of which Mochizuki is chief editor — although that is not unheard of in maths.

Nature | 6 min read

For the first time, superconductors have been found in meteorites. The tiny particles of alloys containing indium, lead and tin would have formed in extreme environments, such as during planetary collisions. Researchers analysed meteorites using magnetic-field-modulated microwave spectroscopy to find where tiny amounts of superconducting materials were hiding. They then used a ‘divide-and-conquer’ technique, progressively breaking the meteorites into smaller grains to pinpoint the superconducting particles. In the coldness of space, these particles might affect planetary formation.

Chemistry World | 4 min read

Reference: PNAS paper

Governments across the world are relying on mathematical projections to help to guide decisions in this pandemic. But much information about how SARS-CoV-2 spreads is still unknown and must be estimated or assumed — limiting the precision of forecasts. Epidemiologist Neil Ferguson, a member of the Imperial College London team that has most influenced the British response to the outbreak, explains exactly how the process works.

Nature | 12 min read

Source: Ref. 1

More than 1 million

Total confirmed cases of COVID-19 worldwide as of 2 April. Because many patients are not tested, the true number of cases is probably much higher. (Nature | Continuously updated)

Features & opinion

“As young scientists, we want to be involved in shaping the landscape that determines our day-to-day work, since we are the ones who will benefit most (namely, for the rest of our careers)”, write three early-career researchers. As members of a student-run think tank, Young SiT, they call on universities to implement fairer evaluation methods that promote professional diversity and growth, not just publication metrics.

Nature Index | 5 min read

This week, in the coronavirus-free Nature Podcast, we look at evidence from deep below the sea-floor that there was a verdant forest on Antarctica around 90 million years ago.

In Nature’s new coronavirus podcast, Coronapod, we explore how low- and middle-income countries are preparing for the pandemic.

Nature Podcast | 17 min listen

Coronapod | 26 min listen

Subscribe to the Nature Podcast on iTunes, Google Podcasts or Spotify.

Books & culture

A 3D magnetic resonance imaging scan of the brain.Credit: Tom Barrick, Chris Clark, SGHMS/SPL

Scientists facing the daunting task of describing the brain conventionally conjure up different kinds of metaphor. The problem comes when we forget that they are descriptors, and see them instead as natural properties, writes historian Stephen Casper. Casper reviews a new book by biologist and historian Matthew Cobb, which provokes contemplation about how some metaphors burden us with invisible assumptions made in the past.

Nature | 5 min read

Andrew Robinson’s pick of the top five science books to read this week includes the neuroscience of navigation, a world of ice, and a black inventor reconstructed.

Nature | 3 min read

Where I work

Maria Josefa Verdugo is a PhD student in marine biogeochemistry at the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, Germany.Credit: Esther Horvath for Nature

Marine biogeochemist Maria Josefa Verdugo spent last winter living and working on a ship locked in the ice as part of the first year-round expedition to explore climate in the far north. “I’m from Chile, and I didn’t grow up around a lot of cold, snow and ice. But I’ve learnt to embrace it,” says Verdugo. “Everything’s cold when you’re handling an Arctic Ocean ice core.” (Nature | 3 min read)