Michelle Kwan is a champion ice skater who has won five World Championships, nine U. S. Championships and two Olympic medals, in addition to countless other skating competitions. While audiences have seen her glide effortlessly across the ice, long hours of practice and devotion contribute each jump and spin.

Kwan began ice skating when she was five years old, and her skill quickly became evident. At the age of eight, she skated several hours a day, every day of the week. Before school, after school and on weekends, she was at the ice rink. The cost of ice time and coaches quickly grew, but her parents were committed to her success. Her family sold their home and purchased a much smaller one to free up money to pay for her ice skating.

When Kwan was 13, she performed at her first U. S. National Championships. After a disappointing performance, she swore to work even harder and improve. She did. The next year, she finished second. From there she went on to win a silver medal at the 1998 Olympics and the first of her World Championships. She followed up with a bronze medal at the 2002 Olympic Games.

Kwan is the most decorated figure skater in American history. She was the sole member to the U. S. Figure Skating Hall of Fame and the World Figure Skating Hall of Fame classes of 2012, and in 2014, she was appointed to the Hall of Fame at the U. S. National Competition.

Even after retiring from skating. Kwan has not given up her devotion to learning, service and hard work. She received her college degree in 2009 from the University of Denver and is pursuing graduate studies in international relations at Tufts University. Meanwhile, she has held several diplomatic and ambassador positions representing the United States globally. Ultimately，whether on the ice, in the classroom or representing her nation, Kwan presents one consistent quality—devotion.

About 150 million years ago, in Montana, a young dinosaur roamed through a land. Not yet five years old, the long-necked creature somehow ended up buried in a violent and muddy flood, forever freezing it in adolescence.

Now, researchers have found this potentially record-setting dinosaur. After uncovering the remains, the scientists argue that the skull (颅骨) is the smallest yet found from a group of long-necked dinosaurs called Diplodocus (梁龙). The little fellow even has a nickname ： Andrew, after Andrew Carnegie, who funded the research, and there is a Diplodocus species named after him.

With its skull just 10 inches across , researchers’ best guess is that Andrew was a juvenile Diplodocus—an especially rare find. While more than a hundred Diplodocus samples have been discovered, their skulls are much rarer. Fewer than a dozen have been dug up to date. If the researchers’ reconstruction is correct, Andrew’s skull could be the smallest and least mature Diplodocus skull ever found, potentially providing insights into the dinosaur’s development.

Kristi Curry Rogers, a paleontologist at Macalester College in Minnesota doesn’t fully agree with the findings because of the poor preservation of the fossil (化石). Andrew’s skull is missing parts of the cheek, palate and lower jaw, plus the fossils are slightly pressed. These problems make it hard to reconstruct the skull, let alone infer the dinosaur’s behavior from it.

“The researchers don’t address the damage of the skull or the missing components of the face in any great detail, which could easily change the explanations,” she said in an email.

For now, Diplodocus is the best guess for Andrew’s identity, but it could also be an unknown species. To help settle the debate, Andrew’s skull is currently being 3-D scanned for future research.

The results from the world’s largest sleep study have shown that people who sleep on average between 7 to 8 hours per night perform better cognitively (认知地) than those who sleep less or more than this amount.

The world’s largest sleep study was launched in June 2018 and within days more than 40,000 people from the world participated in the online scientific investigation, which included an in-depth questionnaire and a series of cognitive performance activities.

“We really wanted to capture the sleeping habits of people around the entire globe. Obviously, there have been many smaller sleep studies of people in laboratories but we wanted to find out what sleep is like in the real world,” says Adrian Owen, western’s researcher in Cognitive Neuroscience and Imaging. “People who logged in gave us a lot of information about themselves. We had a fairly extensive questionnaire and they told us things like which medications they were on, where they were in the world and what kind of education they’d received because these are all factors that might have contributed to some of the results.”

More than half of all participants reported typically sleeping less than 6.3 hours per night, about an hour less than the study’s recommended amount. One shocking truth was that most participants who slept four hours or less performed as if they were almost nine years older.

Another surprising discovery was that sleep affected all adults equally. The amount of sleep associated with highly functional cognitive behavior was the same for everyone, regardless of age. Also, the harm associated with too little, or too much sleep did not depend on the age of the participants.

“We found that the best amount of sleep to keep your brain performing its best is 7 to 8 hours every night. We also found that people that slept more than that amount were equally harmed as those who slept too little,” says Conor Wild, Owen Lab Research Associate and the study’s lead author.

Self-esteem (自尊) is all about how much we feel valued, loved, accepted and thought well of by others and how much we value, love and accept ourselves.     11     They tend to have better relationships with others, feel happier, find it easier to deal with mistakes and failures, and more likely to stick to something until they succeed. People with low self-esteem often feel as if no one will like them or accept them or that they don’t do well in anything. The following ways may help you improve your self-esteem.

    12     If you’re used to focusing on your shortcomings, start thinking about positive aspects of yourself that overweigh them.

It is good to aim high, but your goals for yourself should be within reach.     13     Mistakes are part of learning, so view mistakes as learning opportunities. Accept that you make mistakes because everyone does.

    14     If you realize that you’re unhappy with something about yourself that you can change, start today. If it’s something you can’t change (like your height), start to work toward loving yourself the way you are.

Feeling like you’re making a difference and that your help is valued can do wonders to improve your self-esteem.    15     You can lend a hand to a classmate who’s having trouble, help clean up your neighborhood or volunteer to do some other things.