Sidewalks in Chicago were packed during the rush hour. I marched along as quickly as I could. If I didn't get to the station fast I would miss the early train out of the city. That meant even less time to spend at home with my baby.

    On my left was Saint Peter's Church. I'd passed it on the way to the station many times, but today I stopped. Other commuters (使用月票乘车者) rushed around me. I knew I should follow them since my train wouldn't wait. But I had the strangest compulsion to go into the church instead. I hesitated for a moment, but the feeling was strong. I went inside.

    I sat down in a comer. It seemed like ages since I'd sat down to think. Mary Ellen had been born in October, on the very date of her due date, in fact, October 16. A month before my husband, Rick, had lost his job. I often worked as a designer, but I'd planned on taking time off after the baby was born. With Rick out of work, I didn't have the choice. One of us had to find a job fast. I was lucky to find the job I had now. Unfortunately, it wasn't one I could work on at home. Every day I had to take the train into Chicago, a two-hour commute in both directions. I left the house so early and came home so late, so I felt like I barely got to see my baby.

    I was grateful that Rick was at home caring for her, but it was not her mother. Every minute away from her I felt like I was abandoning her.

    Looking around at the windows, I remembered when Rick and I bad first decided to try for a baby. My friend Renee was almost as excited as I was when I told her about it.

    “I've got something for you,” she said one afternoon when I her for lunch. She pulled a medal out of her purse.

    “Fix this to your clothes every day,” she said. “You'll have a baby in no time.”

    Not long after I learned I was pregnant, I was thrilled at first. But little by little I started to worry: Was my baby okay? What if something happened? The doctor assured me things were going smoothly. My family gave me support. Rick tried to encourage me. I even continued to wear my medal. But no matter what anyone said, I couldn't shake off my worries.

    Now that Mary Ellen was born I had new worries about motherhood. Is this how life was going to be from now on, with every stage of my child's life bringing new fears and anxieties?

    I thought of Renee and her gift of the medal, feeling hopeful. On my way to the door I stopped at the gift counter. I'd missed the early train, so there was time to look around. I went over to a box full of angel cards, thinking of Renee. So many things could happen in the future as Mary Ellen grew up, went to school and went out on her own. So many things to worry about. It would take an army of angels to cover them all.

    I saw a familiar face in the box. It almost felt like I was looking at a friend, someone who cared about my baby as much as her father and I did: On the back of the card was a date. “October sixteenth?” I said, not believing my eyes.

    “That's the angel's birthday,” the woman at the counter told me. I nearly burst out laughing right there. Mary Ellen's birthday! Maybe I couldn't be with Mary Ellen every minute. But never again would I worry that she was out of the angers protection, or doubt that she had a special friend.

    There is a lot to learn about the creations of Beatrix Potter—not only is she the author of one of the world's most famous children 's books, The Tale of Peter Rabbit ,but also a pioneering conservationist(自然资源保护论者) with the spirit of a scientist.

    “Potter grew up as the daughter of a wealthy Victorian family, but along with her brother who filled an entire floor of their large house in London with all sorts of animals, which contributed a lot to her works,” said Anne Lundin, a retired professor for the UW-Madison School of Library and Information Studies.

    “As an adult, she was a frustrated botanical scientist. That field was not open to her because she was female,” Lundin said. Potter was urged to turn the charming stories she wrote in letters to children into books. She wrote 23 books in all--a body of work that has inspired plays, ballets, films and an astonishing amount of merchandise.

    “The Tule of Peter Rabbit is probably the most famous children's book in the world, which was published in 1902 and has really stood the test of time. It's been translated into 36 languages. The parents and grandparents will share it with the next generation,” said Lundin.

    Potter also made a mark on the world through her land conservation.“In many ways, she was like Peter Rabbit, risking into a world of adventure. She withdrew from London as soon as she started making some money on her books to the Lake District and became an extremely important farmer and conservationist. She preserved and passed on 15 farms and over 4,000 acres, which were given back to the country as gifts in the 20th century,” said Lundin.

    Even though she was born 150 years ago, she was amazingly modern--her embracing of the natural world, commented Jennifer Blatchley Smith, an artistic director of the show Peter Rabbit Tales to celebrate the 150th anniversary of Potter's birth.

    Scientists are using robots to study the health of waters in and around Venice, Italy. The robots are designed to act like fish, other underwater creatures and plants. The scientists are working with several universities and research centers as part of a group called subCULTron. The European Union gives money to the project as part of its Horizon 2020 program whose aim is to take great ideas from the lab to the market and support science and innovation (创新) in Europe. The scientists want to use the artificial intelligence of the robots to help humans understand what is happening under the water of the Venice lagoon (潟湖).

    SubCULTron, a collective artificial intelligence project, plans to create the biggest shoal (鱼群) of robot fish in the world. The project's aim is to improve knowledge of the seabed and try to turn human abilities into hi-tech items.

    Alexandre Campo, a computer scientist, says the scientists have looked at the way animals learn to work in groups to understand how robots can learn to work together. The subCULTron project wants its robots to learn to work together so they can watch out for changes and new problems in the water.

    One problem the researchers had in the beginning was how the robots would communicate with each other. Wi-Fi and GPS equipment don't work underwater. Instead，the robots can use sonar (声呐) and an electric field.

    Another problem was charging batteries. The robots come up to the water's surface and stay near a boat or a power station to charge without any electrical cables. Besides, how to be water- proof, especially for some key pads of the robots, was really tough. Fortunately, a special mixture has been created to be pinned on the robot, which successfully stands the test of water.

    The health state of the lagoon is pretty good. There are no industrial polluters, and the city now has a modem sewer (污水管) system. It's not like before when all the waste flushed directly into the water. The robots in Venice will continue their work until 2019. The subCULTron project hopes they develop into “an artificial society underneath the water surface” that serves “a human society above the water”.

Yawning（哈欠）sends out certain messages—either “Oh, this movie is boring" or "I probably need to get some sleep". But did you know that a yawn can also help your brain to cool down when it is so overheated?

    A new study, led by a research team of Princeton University, has indicated（表明）that yawning could be the brain's natural way of regulating temperature. People yawn more often when the temperature outdoors is lower than their body temperature but are less likely to yawn when it is hotter outdoors, according to Sciencedaily.com.

    The research team did an experiment on 160 people, 80 in summer and 80 in winter, to examine how often they yawned at different air temperatures. The study found that people yawned more often in winter than in summer. Scientists say that when the air temperature is lower outside the body, there is heat exchange between the overheated brain and the cool air. But when the air temperature is higher than or equal to the body, people are less likely to yawn because the hot air they breathe in will make the brain even hotter.

    When people yawn, their jaw is also stretched, which increases blood flow and may also help cool the brain.

    The study showed that the amount someone yawned could be related to the amount of time they spent outside. The longer they spent outside in summer, the less they yawn. Nearly 40 percent of participants yawned within their first five minutes outside, but after that the percentage was reduced to less than 10 percent.

    However, the result was the opposite in winter. The number of people who yawned increased when they spent more than five minutes outdoors. But the change was only slight compared to summertime.

    According to Gallup, this is the first report to show that yawning frequencies(频率) change depending on season. This could help us to understand better the way our brains work. It may also help us understand the reason why frequent yawning can sometimes be a sign of brain disease.

    Whatever happened to the familiar scene from the past of children playing "tag(捉人游戏)" in the streets while their parents chatted with the neighbors over the garden fence? This picture is fading fast today, as children are now leaving the streets in favor of a screen.

    Several organizations are attempting to change this situation. One of these organizations is Play England, which aims to improve opportunities for children to play outside. A leading figure in the campaign is 50-year-old Adrian Voce, who has childhood memories of days spent in the "Big Woods" near his house with his older brothers. "We were given a packed lunch and told not to talk to strangers. I can still remember wandering in and out of each others' houses." he says.

    However, it is not only the children that Mr. Voce and his organization have to convince. In many cases the parents themselves block his efforts. A survey in 2014 found that 85 percent of adults agreed that it was important for children to be able to play safely in the road or street where they live. However, many of them were not prepared to park their cars an extra 50 meters away from their homes.

    Mr. Voce's attempts to encourage children to play outside include the organization of campaigns like National Playday. Hundreds of communities all over the country take part in this effort, yet it can take a lot of people to give children a taste of what it is like to play in the streets. On one street in Aldershot last year there were five policemen, three community support officers, a traffic management crew, a closed-circuit television van, and a team of "play workers."

    Society today has changed to such an extent that children do not feel safe on the streets and their parents no longer feel comfortable about letting them play there. It is not only the appeal of computers and video games that has driven children inside, but also the presence of traffic, crime, and violent young people. However, thanks to the efforts of people like Adrian Voce, it may not be too late to turn back the clock.

    The Hong Kong-Zhuhai-Macau Bridge, the world's longest sea-based project, comprises four parts: a 22.9-kilometer steel bridge, two artificial islands, a submerged sea tunnel extending for 6.7 kilometers, as well as leading bridges that connect the bridge to the cities.

    For a bridge project, designers prefer to build all the structure on the ground, and only choose the tunnel when there is no alternative. However, for the HZMB, the most practical design is to integrate bridge, island and tunnel to form a complete cross-sea channel.

    "The Pearl River Estuary （河口）holds a world-level shipping channel. Smooth traffic should be guaranteed. And the location is near the Hong Kong International Airport. With about 2,000 flights taking off and landing at the airport, the bridge cannot be built too high for safety reasons, said Meng Fanchao, chief designer of the project. ^"But you cannot have a submerged sea tunnel without any support. That forced us to build the artificial islands."

    Chinese engineers declared a trail in installing deep-immersed tunnel tubes. There is no model for us to refer to as all the cases are shallow-buried tubes, said Meng.

    "For lack of experience, the installation of the first tube lasted for 96 hours," said Yin Haiqing, deputy manager of the Project Management Department. "Everyone was exhausted when we made it."

    The 6.7-kilometer tunnel is the world's longest submerged sea tunnel.

    Two artificial islands, covering an area of 200,000 square meters, help create a smooth transition between bridge sections and tunnels. Different from traditional island, the engineers put 120 steel cylinders （圆柱）with a 22-meter diameter （直径）into the seabed, make out the shape of an island, and fill the island with soil. It is an innovative way they adopted to build the artificial island, making it firmer, more efficient and friendly to the marine ecology.

    The HZMB provides a fixed link between the two Chinese economic centres Hong Kong and Macau and the mainland of China at Zhuhai.