For most of the last century, T. rex was pictured as a sluggish, tail-dragging reptile that had to warm up in the sun before it could go anywhere. Then, further research changed that view, replacing it with the active, bird-like animal shown in the movie Jurassic Park. But whether T. rex used warm blood to power that activity remained a question. Now we might have gotten closer to an answer.

A team of researchers led by Randon J. Flores and Robert A. Eagle, geochemists at the University of California, Los Angeles, has measured the T. rex body temperature by analyzing its teeth. This dental thermometer read about 36° Celsius—roughly the body temperature of a modern elephant.

Dental thermometry

Paleontologists have long argued about dinosaur physiology based on indirect evidence like bone microstructure, growth rates, and where fossils turn up on the map. Some studies suggested many dinosaurs were endotherms, generating their own body heat like birds and mammals. Others argued that each lineage may have had its own thermal strategy.

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Learning another language is a highly complex mental activity. It requires people to remember words, distinguish unfamiliar sounds, recognize patterns, work out grammatical rules, and retrieve the right expression at the right moment. All of this happens while listening, interpreting, and preparing a response.

Could all this mental activity also help keep an aging brain healthier? Research suggests it can.

Concerns about memory and dementia can send aging adults looking for ways to exercise their brain and maintain cognitive function, whether it is solving crossword puzzles or playing a musical instrument. Language learning might not seem like the same kind of brain exercise, but it is a complex activity that engages several mental processes at once.

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For decades, astronomers thought rings were something only giant planets had. That changed in 2013, when a small, dark body orbiting between Saturn and Uranus passed in front of a star and blinked twice on either side of the main event, revealing two narrow rings around an object barely 250 kilometers across. “It was a surprise,” says Pablo Santos-Sanz, an astronomer at the Instituto de Astrofísica de Andalucía in Granada, Spain. Ever since, the question has been what such rings are made of and how long they can last.

In a recent study, Santos-Sanz and his colleagues used the James Webb Space Telescope to watch the same body, now known as Chariklo, pass in front of a background star again. They found one of its rings had grown denser and the other had almost vanished. We don’t know exactly why.

Shadowing a star

The technique behind the observation is simple. “We predict when a Solar System object passes in front of a star,” Santos-Sanz said. The starlight dims for a moment, and the shape of that dip reveals the size, shape, and surroundings of the object that caused it. “This is particularly challenging for minor bodies, and more challenging for distant minor bodies,” he said.

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For a long time, sleep research has treated the cerebral cortex as a passive follower reacting to signals from the deep brain. “Usually, sleep is associated with being controlled by subcortical regions,” said Geoffrey Terral, a neuroscientist at the Albert Einstein College of Medicine in New York.

The cortex is where the slow rhythms of deep sleep can be seen, but researchers assumed the signals that triggered them originated elsewhere. In a recent Nature study, Terral and Renata Batista-Brito, who runs the lab, report a population of cortical cells that challenges that assumption.

These cortical cells make up only around one percent of the cortex's inhibitory neurons, and switching them on in a mouse puts the animal to sleep. “What our work shows is that the cortex can not only see this rhythm but also initiate it by itself, and this is sufficient to promote sleep,” Terral said.

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A Chinese optical engineer is the winner of this year's Small World in Motion competition, sponsored by Nikon. Ning Xu of Tsinghua University in Beijing beat out 346 other video entries from 40 different countries with his super-resolution video (above) of the abnormal beating of cilia in the airways of a child with a rare genetic respiratory disorder.

Founded in 2011, the Nikon Small World in Motion competition is a spinoff of the company's Small World Photomicrography Competition, which has been around since 1974. Both are meant "to showcase the beauty and complexity of things seen through the light microscope"—one through still photographs, the other through photovideography, taking advantage of all the technological advances that now allow users to make movies or time-lapse images through the microscope.

Primary ciliary dyskinesia (PCD) is a genetic disorder that adversely affects the tiny hairlike structures that line the lungs, among other areas. Their wavelike motion helps move around germs, mucus, dust, and other irritants so the body can dispel them via coughing or sneezing. In people born with PCD, there is something wrong with those cilia, so those irritants build up, causing respiratory infections, among other complications. The cilia might be the wrong size, the wrong shape, or missing altogether. They might move abnormally or not move at all.

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