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Long chats, indoors: where masks matter
An analysis of hundreds of COVID-19 cases suggests where face masks matter most: during long encounters and indoors. Researchers studied more than a thousand people in California who tested positive for SARS-CoV-2 between February and September 2021. Each of them was matched with at least one control participant: a person with the same factors, such as age and sex, but who tested negative during that time period. Participants who’d been exposed to someone known to have COVID-19 provided details about the encounter, such as the setting and duration. The study, which is not yet peer reviewed, found that participants who were not fully vaccinated had the greatest risk of infection when they reported an exposure to someone with COVID-19 that occurred indoors or that lasted for more than three hours. Participants exposed to someone with COVID-19 had lower odds of infection if masks were worn at the encounter than if they weren’t.
Reference: medRxiv preprint (not peer reviewed)
US astronomy’s ambitious ten-year plan
A long-anticipated road map for the next ten years of US astronomy just dropped, and it’s super-ambitious. It recommends that NASA coordinate, build and launch three flagship space observatories that are capable of detecting light over a broad range of wavelengths. It suggests that the US National Science Foundation fund two enormous ground-based telescopes in Chile and possibly Hawaii, to try to catch up with an advanced European telescope that’s under construction. And for the first time, it issues recommendations for how federal agencies should fight systemic racism, sexism and other structural issues that drive people out of astronomy, weakening the quality of the science.
Boost hungry whales to restore ocean life
Whales eat up to three times more prey than was previously thought. Their faeces once fuelled a rich undersea ecosystem that was devastated by whaling. Researchers tagged whales and monitored krill to directly observe the eating habits of baleen whales, such as humpbacks (Megaptera novaeangliae) and blue whales (Balaenoptera musculus). With an estimated 2 million animals killed by whalers in the twentieth century — a mass twice as large as all the wild mammals on Earth today — that means an estimated 430 million tonnes of krill went uneaten. That iron-rich poo never sank to fertilize the ocean’s food web, breaking an iron cycle that nourished everything from diatoms to seabirds. People might be able to help restore these formerly rich ecosystems, say researchers, by seeding the ocean with iron that ultimately encourages the whale population to bounce back and do the job itself.
Read the expert view by bio-oceanographer Victor Smetacek in the Nature News & Views article (7 min read, Nature paywall)
Reference: Nature paper
When whales eat krill, they aid iron cycling by defecating the iron-rich remains. They can also aid iron availability by mixing ocean waters through their vigorous tail movements. Since iron availability limits productivity in ocean waters, this fuelled a rich food web — which widespread whaling has disrupted. (Nature News & Views article | 7 min read, Nature paywall)
Image of the week
This tiny tardigrade has been preserved in amber for 16 million years. Researchers were studying the fragment for months before spotting the half-millimetre-long creature in a corner. The discovery is “truly a once-in-a-generation event”, says entomologist Phil Barden. It is only the third fossilized tardigrade to be found, and the first from the Cenozoic, the current geological era. The fossil specimen — a genus and species new to science — has been named Paradoryphoribius chronocaribbeus.
See more of the month’s sharpest science shots, selected by Nature’s photo team.