1 . Polar bears are icons of the Arctic. Detailed monitoring of their populations is crucial for their conservation—but because polar bears are so difficult to find, we are missing critical data about population size. Scientists have now developed a new tool to help: DNA analysis using skin cells left in the bears’ footprints in the snow.

The scientists were inspired by the techniques that can be applied to tiny, degraded DNA samples. With these techniques, it isn’t necessary to physically capture bears, which can be stressful and dangerous for both bears and humans. Instead, the researchers can turn to the snow tracks of polar bears and look at sources of DNA left in passing—environmental DNA. "The tracks usually contain fresh cells, and the DNA is intact because of the cold’ storage’ temperature, "said Dr. Melanie Lancaster of the World Wide Fund, lead author.

The scientists collected snow from individual tracks made by Alaskan polar bears in the wild. Additional materials like hair and saliva(唾液)were sampled, confirming that the tracks provided accurate genotype(基因型) 24 wild polar bear tracks were sampled. The researchers melted and filtered the snow to collect environmental DNA, then carried out micro-satellite analysis. Although the concentrations (浓度)of DNA taken from trucks sampled in the wild were very low, 13 of the wild polar bear samples could be genotype, identifying 12 different individuals.

This technique has huge potential to inform conservation of these animals, to better understand their populations and behavior. Although the sampling has a lower success rate, ease of collection means that it can significantly expand sample sizes.

"We hope this method will be taken up by the polar bear research community, with the involvement of hunters, volunteers, and local communities, as a new way to collect information on polar bears, "said Lancaster. "We also hope the method will be expanded to other animals living in snowy environments. "

2 . Even though they may appear to be completely unrelated, black holes and Las Vegas have one thing in common: Whatever happens there stays there, much to the displeasure of astrophysicists who are trying to understand how black holes grow.

The event horizon can be conceptualized as an outer ring that surrounds black holes and is the boundary beyond which nothing, including matter, light, or information, may pass. It takes in every bit of evidence about the black hole’s past and has the appearance of being “stuck” to the eyes of an observer.

“Because of these physical facts, it had been thought impossible to measure how black holes formed,” said Peter Behroozi, an associate professor at the University of Arizona Steward Observatory.

Behroozi co-led an international team to rebuild the growth histories of black holes using machine learning and supercomputers, successfully avoiding the event horizon information barrier for individual black holes to show what is beyond. Millions of artificial universes were simulated (模拟), and the results showed that supermassive black holes grew at the same pace as their host galaxies (星系). Scientists had a theory about this for 20 years, but had not been able to confirm this relationship until now. The team’s research was reported in a publication in Monthly Notices of the Royal Astronomical Society.

“As the galaxy grows from small to large, its black hole, too, is growing from small to large, in exactly the same way as we see in galaxies today all across the universe,” Behroozi said.

Trinity is a platform developed by the researchers that uses a novel type of machine learning to generate millions of different universes on a supercomputer. The goal of Trinity is to find answers. The project’s three main research areas are galaxies, their supermassive black holes, and their dark matter halo (晕). The same Trinity is in inference to these three areas. Millions of galaxies and their dark matter halo were simulated using the researchers’ older University Machine in past investigations.

The researchers found that galaxies expanding in their dark matter halo have a very particular relationship between the galaxy’s mass and that of the halo.

4 . Stacy Dean, an official at the US Department of Agriculture, was inspired by a visit to Watkins Elementary, in Washington, D. C. Students grow vegetables in their school garden. They also roll up their sleeves in the school’s kitchen to participate in a FRESHFARM FoodPrints class, which integrates cooking and nutrition education.

“Who’s next?” asks instructional coach Regina Green, as kids throw vegetables into the pan and the smell of fresh ginger and onions fills the air. “We grew these in our garden,” Jessie Gibson, one of the students, says proudly. Then he measures and pours dry ingredients into a bowl.

“Our family has tried new things because of the program,” says Catie Kelley, whose two children have participated in the FRESHFARM program. “They come home with the recipes,” Kelley says. “It’s fun because it’s things that we don’t usually make at home,” so it has encouraged them to try novel combinations. She says the kids take more of an interest at the grocery store to identify foods they’ve tried in the program.

Dean wants to have the science around healthy eating integrated. A block to scaling up these types of programs is money. The program relies on grants and receives some federal funding, but it’s not enough to expand the program to all the schools that could benefit.

In fact, there are other problems. At a time when diet-related disease is a leading cause of death, and unhealthy eating habits are rooted in US culture, it’s unrealistic to think that a cooking curriculum could overcome such a sweeping, societal problem. “We know from years of evidence that we need multiple things to come together to support healthy eating,” says Angela Odoms-Young, a professor of maternal and child nutrition at Cornell University.

Despite these challenges, programs like FRESHFARM can help kids expand their choices by introducing them to new tastes. At first, many kids are turned off by the bitter taste of greens. But through the magic of cooking, processing the onions, and blending in fresh ginger, kids can be inspired.

5 . Princeton University Art Event

Program Information for Gaucho: A New Musical

March 8-10, 2024, in Wallace Theater

Presented by the Lewis Center for the Arts’ Program in Theater &Music Theater.

Gaucho:A New Musical

Book, music and lyries (歌词) by Princeton University seniors Aaron Ventresca and Emmu Ventresca; directed by lecturer Nicuo Krell with music direction by guest artist Gia Gan.

Run Time

Approximately 2 hours(including a 10-minute intermission).

Setting

In this new musical set in nineteenth-century Argentina, the gaucho (高乔人) community of San Antonio de Areco (a town in Buenos Aires Province, Argentina) faces growing threats to its traditional way of life from large landowners’ newest technology-barbed (带刺的) wire fence. A young gaucho named Mateo struggles to break free from his family’s dying way of life to become a writer. Then with some help, Mateo escapes to Buenos Aires. There, he meets Sofia, who shakes his narrow-minded view of the world. As modernity takes shape, Mateo is torn between choices:his family or the one he could create, his culture or the movements of the world.

Special Notes

No flash photography permitted. Please silence all electronic devices including mobile phone and watches, and avoid text messaging for the duration of the performance.

Tickets &Details

Performances are free and open to the public;advance tickets required. If a performance is listed as sold out, a wait list will be formed at the door with a limited number of tickets available.

Accessibility

The Wallace Theater is an accessible venue with an assistive listening system. Guests in need of other access accommodations are invited to contact the Lewis Center at least one week in advance at lewiscenter@princeton. edu.

10 . Eric knew he was in trouble. His _________ had ballooned to 320 pounds, and he was _________ more than $1,000 a month on medications (药物) for high blood pressure, Type 2 diabetes and high cholesterol.

In 2010, a _________ told him to buy a funeral plot, because he would need it in five years. He was 51 years old. So he went to talk with a naturopathic (自然疗法的) doctor about _________ weight. She said, “Get a shelter dog.”

Eric was _________, but he took that advice, _________ to the Humane Society Silicon Valley near his home in San Jose, Calif. He told the shelter, “I want a(n) _________ fat middle-aged dog, like me.” That’s how he _________ Peety.

Peety needed to be _________, so Eric and Peety walked, for at least a half hour a day. Eric, who was __________ as an area sales manager for GE appliances, shifted to a plant-based __________. Over the course of a year, he lost 140 pounds. Peety lost 25. Eric __________ the medications.

It wasn’t just the walks with Peety that __________ Eric’s life. The dog helped keep him from backsliding (倒退) into his old, __________ lifestyle. “He looked at me like I was the best person on the __________, and I wanted to become the person he thought I was.”