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The UCNtau magnet array

The magnet array for the UCNτ experiment at Los Alamos National Laboratory, where physicists have measured the lifetime of the neutron with the highest ever precision.Credit: Los Alamos National Laboratory

Super-precise measure of neutron lifetime

Physicists have measured the lifetime of the neutron more precisely than ever before. The average time it takes for the subatomic particle to decay is 877.75 seconds, according to an experiment that used magnetic fields to trap ultra-cold neutrons. The results have twice the precision of similar measurements, and are consistent with theoretical calculations. But they do not explain why neutrons live nearly 10 seconds longer in a different experiment that involves watching the particles decay as they move in a beam.

Nature | 5 min read

Reference: Physical Review Letters paper

Unresolved differences: Chart showing the results of two experimental methods used to measure the lifetime of a neutron.

Source: Wietfeldt, F. E. Atoms 6, 70, https://doi.org/10.3390/atoms6040070 (2018) and Ref. 1

Late-stage trial for Koala chlamydia vaccine

Researchers in Australia have rolled out trials of a one-shot chlamydia vaccine in some 400 koalas at a wildlife hospital in Queensland, Australia. They hope the protein-based vaccine will help to improve the marsupials’ long-term survival by protecting them against the sexually transmitted bacterium, which can cause infertility and blindness.

The Guardian | 3 min read

Costa Rica, coral among Earthshot winners

Projects to restore coral, make hydrogen and reduce food waste are among the winners of the first Earthshot Prizes for innovative solutions to environmental challenges.

• The city of Milan, Italy won for creating hubs that redirect surplus food from supermarkets and company canteens to people in need.

• The Republic of Costa Rica won for its programme to reverse deforestation.

• Takachar, a social enterprise in India, developed a machine that attaches to tractors to convert agricultural waste into fuel and fertilizer, instead of seeing it burnt.

• Coral Vita, a charity in the Bahamas, grows coral in tanks on land that can be used to restore reefs.

• The AEM Electrolyser, developed by a company called Enapter headquartered in Germany, is a modular device that can generate hydrogen from renewable electricity, on site.

The £50-million (US$65-million) prize consists of five £1-million prizes awarded each year for ten years and aims to inject positivity into the search for green solutions. “They all give us hope, which we are told springs eternally,” said naturalist David Attenborough at the ceremony. “But we don’t have eternity. We need to do this now.”

The New York Times | 4 min read

Features & opinion

How to write a pop-science book

Persistence, networking and serendipity all smoothed the way for immunologist John Tregoning to publish his book, Infectious. He shares advice about pitching, getting an agent, and actually putting all those words onto the page.

Nature | 8 min read

The death of darkness

As companies fill low-Earth orbit with thousands of communication satellites, space is becoming a new region of environmental dissent. Astronomers, amateur stargazers, photographers and Indigenous leaders are among those pitted against the proponents of ‘megaconstellations’ that aim to offer global broadband. After a confab with astronomers at the Vera C. Rubin Observatory, SpaceX engineers managed to reduce the light bouncing off some of the company’s Starlink satellites by giving them a sun shade. But debate continues over who will decide the fate of the high skies.

Science | 16 min read

Infographic of the week

figure 1

Figure 1 | Neuronal targets of electroacupuncture. In a treatment called electroacupuncture, certain sites on the body known as acupoints are stimulated electrically. For example, low-intensity stimulation of a leg acupoint called ST36 can reduce inflammation by activating the vagus nerve, which sends signals from the brain to the adrenal glands (located, as shown, on the kidneys), and promotes the release of anti-inflammatory catecholamine molecules such as dopamine and noradrenaline. Liu et al. used a mouse model of sepsis — a potentially fatal condition in which the inflammatory reaction to an infection gets out of control — to identify a population of sensory neurons that express the protein Prokr2 and that are needed for the anti-inflammatory effects of low-intensity ST36 stimulation, but not high-intensity stimulation (not shown). These neurons have cell bodies in the lower spinal cord, and have processes (red lines) that extend down the hindlimb and up to a brain structure called the nucleus tractus solitarius (NTS), which influences the activity of the vagus nerve.

Electroacupuncture — which delivers a small electric current into tissue in the body — has been shown to reduce inflammation in mice, but only when applied to specific points. For example, low-intensity stimulation of a leg acupoint called ST36 activates the vagus nerve, which sends signals that release anti-inflammatory molecules. Now researchers have identified the sensory neurons, which express the protein Prokr2, that are involved. These neurons have cell bodies in the lower spinal cord, and have processes (red lines) that extend down the hindlimb and up to a brain structure called the nucleus tractus solitarius (NTS), which influences the activity of the vagus nerve. These results provide, for the first time, a way to identify neurons that might be stimulated to control particular organ functions. (Nature News & Views article | 8 min read, Nature paywall)

Hear neurobiologist Qiufu Ma give insight into the work on the Nature Podcast (26 min listen, free)

Reference: Nature paper

See more of the week’s key infographics, selected by Nature’s news and art teams.

Quote of the day

“It’s really irritating when they talk, but they don’t do.”

Local monarch Queen Elizabeth II was overheard decrying world leaders’ lack of action on climate change ahead of the COP26 climate-change conference in Glasgow, UK. (Bloomberg | 1 min read)