【推荐2】Every year, millions of monarch butterflies migrate 3,000 miles to Mexico from North America. “Everybody knows about the monarchs’ migration,” says Andy Davis, an animal ecologist at the University of Georgia. “But one of the things that we still don’t understand is how they’re capable of making such tremendous flight while being such small animals with limited energy.” Amazingly, some of the monarch’s continent-spanning magic may be owed to the size of its wing spot, according to a study published in PLOS One.

The question of how color influences the monarch’s flight began when Mostafa Hassanalian, a professor of mechanical engineering, published a paper about how the colors on the wings of the albatross (信天翁) might help it fly for longer distances. The black on the top of the bird’s wings absorbs more solar energy, creating a pocket of warm air; the white on the bottom absorbs less. Together, the opposite colors create more lift and less drag, helping the albatross to fly up more efficiently.

Motivated by Hassanalian’s paper, Andy Davis contacted him and they teamed up with three other experts to investigate whether the orange, black. and white patterns on North American monarch butterflies’ wings influenced their flight distance. Specifically, they explored whether these color patterns determined how far the butterflies could fly. They discovered that surviving migratory monarchs had 3% less black pigment (色素) and 3% more white pigment a surprising contrast from the albatross. They also observed larger white spots on Eastern monarchs, which migrate farther than Western and Floridian populations, along with deeper shades of orange. The team assumed that these color patterns might offer an aerodynamic (空气动力) advantage, although the reason for the larger white spots remains unknown.

Should the connection between white markings and flight performance prove true, they plan to apply it to drone technology. “If small coloration (自然色彩) effects can improve like 10% of your efficiency, that’s a lot,” Hassanalian says, “Another aspect is that your drone would be able to carry more, because this coloration helps it gain extra lift.” The enhancement could also benefit other aircraft, but he points out one warning: planes fly at a much faster speed than butterflies, so coloration may not be as relevant to them.

Other butterfly scientists have reacted to their work with both enthusiasm and skeptlesm. “It is a totally new idea and it’s quite exciting,” says Marcus Kronforst, an evolutionary biologist. “I’ve worked on butterfly color patterns my whole life, basically, and never, never considered this. It’s never crossed my mind that it might influence how the butterflies fly.”

【推荐3】A blind fish living within a Mexican cave system’s deep, enduring darkness still maintains some ability to sense light. As the cave fish no longer seem to rely on an internal daily cycle and some sleep very little, biologist Inca Stein-dal and her colleagues were keen to see if their bodies can still regulate cyclically through time. Most animals on Earth have an internal clock for this the circadian rhythm (昼夜节律) that uses light levels to make our bodies fit in with our planet’s day and night cycles. This rhythm is then used to cycle through different biological processes that can influence our behaviour, such as our hunger cycles.

The Mexican blind cave fish live in a complex of over 30 isolated caves, within which they have each independently adjusted to the dark.   Their bodies are extra sensitive to vibrations (震动), allowing them to sense changes in water currents for navigation (导航) in compensation for their limited or complete lack of sight. This adaptation occurred despite the fish from each cave evolving from the same species with fully functioning eyes. This ancestral group still lives in the surface waters in the El Albra region of Mexico and some parts of the Southwestern US.

Steindal and her team took tissue samples from the blind cave fish, from three isolated caves, and their surface relatives and tested the cells in different conditions. They detected the activation of several molecular (分子的) clock mechanisms when the cells were exposed to light, even in the cave fish cells. “Non-visual light detection is maintained at a fundamental cell-based level,” the researchers explain,although the cave fish cells did not respond as strongly as those cells from surface fish. While there were some similarities between the fish from the different caves compared to their surface relatives, there were also differences that confirm their biological clock changes each evolved independently of one another via different molecular mechanisms.

“We have provided proof that despite being blind, cells from the Mexican blind cave fish can detect light and make their clocks fit in with a light/dark cycle,” Steindal and her colleagues conclude. The team hopes these can help us learn more about the circadian rhythm and provide an easier way to study animal adaptations to dark environments.

【推荐1】During COVID’s first wave, the streets of New York and other major cities became empty. The sound of cars decreased, but urban citizens heard something new: an abundance of birdsong. During walks outside, they breathed cleaner air. Lockdowns had meant fewer cars on the roads, and the effects were unmissable. Levels of nitrogen dioxide-a by-product of fossil fuels burned in cars and in electricity generation—were 30 percent lower along the road from Washington D. C. to Boston in March 2020 compared with previous years. Summer coming, people sat at outdoor extensions of restaurants built in parking zones and moved around on newly added bike lanes. These incidental adaptations to the pandemic allowed citizens to experience the benefits of moving away from the “car is king“ situation in a way that policies for climate-friendly equipment never could, explains Christian Brand, an environmental scientist with the Transport Studies Unit at the University of Oxford. Now, he says, “they know what’s possible.”

Some fought to keep it that way. Paris has been a leader of this conversion. The French capital already had plans to press down car use and encourage cycling before COVID appeared, but in late spring 2020 some 50 kilometers of pop-up bike lanes, called coronapistes, were added almost overnight. They are now a permanent part of Paris’s cycling network, with more in the works.

These measures, Brand says, came in no small part because of political will. Paris Mayor Anne Hidalgo made climate change a focus of her reelection campaign. Besides providing subsidies(补贴)for purchasing and repairing bicycles, she emphasized the health benefits of reducing car emissions. In other cities, like New York, changes were more modest or temporary. Shutdowns may have presented the possibility of safer, healthier streets-but it was often a fleeting(飞逝的)vision.

【推荐3】The human voice is delicate. The vocal cords (声带) can easily get damaged by stress, infections, or overuse. According to a 2005 study, 30%of the population will experience a voice disorder at some point in their life.

In a study published in the journal Nature Communications this week, a group of bioengineering researchers from the University of California have put forward an attractive solution. They have designed and tested a soft patch (贴片) that can be stuck onto a person’s neck, where it will pick up muscle movements when speaking, process the signals and translate them into speech.

Even though the team’s device is an early prototype, it has the potential to offer a great improvement on current alternatives. When a person loses their voice today, the easiest fix is to type, text, or write notes to communicate. Typing can be slow and inconvenient, says Jun Chen, the paper’s lead author, and writing is only possible in good lighting. A patch would theoretically clear all these hurdles.

When the throat muscles move under the silicone (硅酮) patch, the resulting magnetic-field variations can be converted into electrical signals. In a test with eight participants, the researchers captured the signals arising as the subjects spoke and lip-sounded five different sentences. They then trained a machine-learning model to recognize the distinct shapes of the electrical signals associated with each sentence. This device then predicted which of the five sentences the participants spoke with more than 90%accuracy, whether aloud or in silence.

In addition to stretchiness, the patch remains sticky on sweaty skin, and can be used continuously for 40 minutes without heating up.

For now the device can only recognize the five phrases it was trained on. Plus, individual difference in vocal cords means the algorithm has to be personalized to each user. To make it practical at scale, the researchers will need to collect a lot more data.