Toggle light / dark theme

Warm weather brings thoughts of spring peepers and leaping bull frogs. But what happens to frogs in the winter? If they can’t dig down far enough into the soil to avoid the ice or aren’t lucky enough to live in warmer climates, some actually freeze.

Fortunately for them, they don’t freeze to death: Most survive to mate another spring.

There are five known species of freeze-tolerant frogs in North America, including the well-studied wood frog, as well as Cope’s gray tree frog, the eastern gray tree frog, spring peepers and the western chorus frog. In the fall, these frogs bury themselves under the leaves on the forest floor — but not deeply enough to escape the icy fingers of Jack Frost.

🏺 That time where it rained for two million years.

Fyodor R.

At the beginning of the Triassic Period, the world was hot, and very dry. But then 234 million years ago, it started to rain and didn €™t stop for two million years. This period of intense rain called the Carnian Pluvial Episode killed of many of the early reptiles and set the stage for the dinosaurs to take over the world.

Researchers at the University of California, Los Angeles (UCLA) and the California NanoSystems Institute in Los Angeles have recently developed a soft swimming robot based on a self-sustained hydrogel oscillator. This robot, presented in a paper published in Science Robotics, operates under constant light input without the need for a battery.

“When I shone on a soft, fast responsive hydrogel pillar, I observed the pillar started to oscillate around the optical beam,” Yusen Zhao, a Ph.D. student involved in the research, said. “It looked very intriguing to me, and I wondered: How can a constant input produce intermittent output? Under what conditions does the oscillation happen? Would it be powerful enough to propel and swim in water, and eventually lead to solar sails? With these questions, I continued systematic studies aiming to achieve these objectives.”

Zhao and his colleagues developed a soft oscillator made of a light-responsive soft gel, which is molded into the shape of a pillar or strip. When light hits a spot of this gel pillar, it is automatically absorbed and converted into heat. The locally heated spot on the causes it to eject some of its water and shrink in volume, resulting in its tail bending towards the light source.