Exhibition Ages of Splendor: A History of Spain in the Museo del Prado, running in Shanghai’s Museum of Art Pudong from Apr 23 to Sept 1, marks the largest presentation of the Prado Museum’s collection in China. One of the most famous paintings of all time, Leonardo da Vinci’s Mona Lisa has a fine copy in the collection of Prado Museum in Madrid, Spain.

HOST: It’s ALL THINGS CONSIDERED from Shanghai News with big news from the art world that’s changing our understanding of the “Mona Lisa.” There are many replicas (复制品) of Leonardo da Vinci’s painting. But researchers in Madrid have examined one of them and discovered something new. This was created at the same time Leonardo was painting his Florentine lady with her famous smile. Martin, how did the researchers do this?

MARTIN: They used modern technology, something called infrared reflectography (红外反射成像). One’s able to look under the surface of the paint. It’s not exactly like an X-ray, but it’s similar process. So they used this process, and found there were lines that were hidden under the surface of the two paintings but visible in the reflectography. So they reached the conclusion that the copyist of the painting had been working alongside Leonardo, seeing how he was creating his painting.

HOST: You know, I’m looking at the two works, Leonardo’s from the Louvre and the other, the copy. The copy is much brighter, and she looks much the same but also quite a bit different. How do you think it changes what we understand about the original (原作)?

MARTIN: Well, it is surprising because, first of all, you see a much brighter and much more colorful image. The original “Mona Lisa” in the Louvre is difficult to see. And what is wonderful about the copy, the Prado “Mona Lisa”, is how vivid it is, and you see Lisa in a quite different light. I mean, her eyes are charming, and you see her smile in a way that you don’t quite get in the original.

March 16 is International Sleep Day. And we should all celebrate the act of sleeping. Researchers say sleep is probably the best tool we have for memory and learning. But what about getting rest during the middle of the day?

A recent study on napping(小睡) says short periods of sleep may help our brains work better. Past studies have shown that napping can help babies and young children learn better. And napping can help brain performance in older adults. Taking a nap may also help this group of people fight off memory loss because of the increase in their age.

Many Americans do nap. But one-third of all adults in the United States are also chronically(长期的) tired, says the U.S. Centers for Disease Control and Prevention (CDC). It found that 50 million to 70 million Americans have chronic sleep disorders. However, they seem to be unwilling to tell people that they take a nap. They may think that napping shows they are weak or they don’t have enough energy. It is not an uncommon opinion that only children, the very old, sick or lazy people nap. In fact, Americans sometimes do a very strange thing. Some people brag about how few hours of sleep they need each night to show that they are somehow stronger than the average human-superhuman, if you will. However, that may be changing. Many offices now offer napping rooms and napping cafes(咖啡馆) are appearing in many U.S. cities, including Washington, D.C. Remember that an hour long nap may be too long for young, healthy adults. It is Recommended that 30 minutes is enough to remove the pressure(压力) to sleep and will help people feel more awake. If people nap longer, they will get trapped into deep sleep, which can be hard to get out of. If you have trouble falling asleep at night, limit your daytime nap to under 45 minutes. Also nap before 3 p.m.

How many digits of pi (圆周率位数) can you remember? Just 3.1415926? Well, this may not be good enough for scientists.

Swiss researchers said they broke a new record. Using a supercomputer, they counted pi to 62.8 trillion (万亿) digits. The team, at University of Applied Sciences in Graubunden, Switzerland, took 108 days and nine hours to do this!

It was “3.5 times as fast as the former world record in 2020”, which reached 50 trillion digits, according to the university. Researchers are waiting for the Guinness Book of Records to certify (认证) their efforts.

Since it was first discovered and understood 4,000 years ago, humans have been trying to count pi as exactly as possible. Zu Chongzhi (429-500), a Chinese mathematician (数学家) , counted pi between 3.1415926 and 3.1415927. Nobody surpassed (超过) his results for about 1,000 years — until Al-Kashi, an Iranian (伊朗的) mathematician, counted it to 16 decimal places (小数位).

Why do we need to know an exact value (数值) of pi? “It’s used everywhere, from the general relativity (广义相对论) of Einstein to your GPS to all kinds of engineering problems,” Jan de Gier, a math professor at the University of Melbourne, Australia, told The Guardian.

It’s true that pi pops up everywhere. But is it too much to count it to 62.8 trillion digits? “I can’t imagine any real-life use where you would need any more than 15 decimal places,” said David Harvey from the University of New South Wales, Australia. However, De Gier compares this to the Olympic Games: “World records are not useful by themselves, but they set a benchmark (基准) and they teach us about what we can achieve.”

“It’s a big challenge for computers,” Harvey agreed. “It’s really a difficult thing to do and it needs lots of math and computer science.”