Following news of the potential for life on the recently-discovered TRAPPIST-1 system, there may be another competitor ready to take its place.

    With the help of the Cassini spacecraft, NASA (National Aeronautics and Space Administration) scientists have picked up the first evidence that chemical reactions are taking place deep below the surface of Enceladus, Saturn's (土星的) sixth-largest moon. This means that there could be life in Enceladus' warm underground seas.

    An early study found that liquid oceans exist miles below Enceladus' surface. But to reveal what is happening down there, scientists must rely on the plumes (股) of water that spray (喷射) through cracks in Enceladus' icy surface. In October 2015, NASA sent Cassini into a deep dive into one of the plumes.

    Cassini's findings, published on April 13 in the journal Science, showed that hydrogen (氢) not only exists on Enceladus, but is also responsible for a chemical reaction between hot rocks and water in the ocean beneath its surface.

    This same process on Earth provides energy for entire ecosystems around volcanic vents (火山口). There, tiny creatures are able to survive without sunlight, using hydrogen and carbon dioxide as fuel in a process known as “methanogenesis (甲烷生成)”.

    The discovery of this chemical energy source on Enceladus means it could be a very good candidate to host life.

    “Confirmation (确认) that the chemical energy for life exists within the ocean of a small moon of Saturn is an important milestone (里程碑) in our search for habitable (可居住的) worlds beyond Earth,” Linda Spilker, Cassini project scientist at NASA, told the Daily Mail.

    Alien life was once only thought possible on habitable planets within the “Goldilocks zone” – far enough from our sun not to be a fireball, but not so far as to be freezing.

    Research on Enceladus is still in its early stages, but the recent findings have important meanings for future exploration.

    “At present, we know of only one genesis (诞生) of life, the one that led to us,” David Rothery, professor of planetary geosciences (行星与地球科学) from the Open University in the UK, told The Telegraph.

    “If we knew that life had started independently in two places in our solar system, then we could be pretty confident that life also got started on some of the tens of billions of planets and moons around other stars in our galaxy,” he said.

    By trying to tickle(挠痒痒) rats and recording how their nerve cells respond, Shimpei Ishiyama and his adviser are discovering a mystery that has puzzled thinkers since Aristotle expected that humans, given their thin skin and unique ability to laugh, were the only ticklish animals.

    It turns out that Aristotle was wrong. In their study published on Thursday, Ishiyama and his adviser Michael Brecht found that rats squeaked and jumped with pleasure when tickled on their backs and bellies. These signs of joy changed according to their moods. And for the first time, they discovered a special group of nerve cells. These nerve cells made this feeling so powerful that it causes an individual being tickled to lose control.

    To make sure that he had indeed found a place in the brain where tickling was processed, Ishiyama then stimulated that area with electrical currents. The rats began to jump like rabbits and sing like birds.

    “It's truly ground-breaking,” said Jeffrey Burgdorf, a neuroscientist at Northwestern University who reviewed the paper. “It takes the study of emotion to a new level.”

    Burgdorf has played a central role in our understanding of animal tickling. He was part of a team that first noticed, in the late 1990s, that rats made special noises when they were experiencing social pleasure. Others had already noted that rats repeatedly made short and high sounds during meals. But the lab where Burgdorf worked noticed that they emitted similar sounds while playing. And so one day, the senior scientist in the lab said, “Let's go and tickle some rats.” They quickly found that those cries of pleasure doubled.

    “The authors have been very adventurous,” said Daniel O'Connor, a neuroscientist at Johns Hopkins University who studies touch. To him, that finding was very surprising.

    “Why does the world literally feel different when you are stressed out?” he said. “This is the first step towards answering that question. It gives us a way to approach it with experimental rigor(严谨).”

    Societies all over the world name places in similar ways. Quite often there is no official naming ceremony but places tend to be called names as points of reference by people. Then an organized body steps in and gives the place a name. Frequently it happens that a place has two names: One is named by the people and the other by the government. As in many areas, old habits died hard, and the place continues to be called by its unofficial name long after the meaning is lost.

Many roads and places in Singapore(新加坡) are named in order that the pioneers will be remembered by future generations. Thus we have names such as Stamford Road and Raffles Place. This is in keeping with traditions in many countries — in both the West and the East.

Another way of naming places is naming them after other places. Perhaps they were named to promote friendships between the two places or it could be that the people who used to live there were originally from the places that the roads were named after. The mystery is clearer when we see some of the roads named in former British bases. If you step into Selector Airbase you will see Piccadilly Circus — obviously named by some homesick Royal Air Force personnel.

    Some places were named after the activities that used to go on at those places. Bras Basah Road is an interesting example, "Base Basah" means "wet rice" in Malay(马来语). Now why would anyone want to name a road "Wet Rice Road"? The reason is simple. During the pioneering days, wet rice was laid out to dry along this road.

    A few roads in Singapore are named by their shapes. There is "Circular Road" for one. Other roads may have part of their names to describe their shapes, like "Paya Lebar Crescent". This road is called a crescent (月牙) because it begins on the main road, makes a crescent and comes back to join the main road again.

    There's a new frontier (新领域) in 3D printing that's beginning to come into focus: food. Recent development has made possible machines that print, cook, and serve foods on a mass scale. And the industry isn't stopping there.

    Food production

    With a 3D printer, a cook can print complicated (复杂的) chocolate sculptures and beautiful pieces for decoration on a wedding cake. Not everybody can do that—it takes years of experience, but a printer makes it easy. A restaurant in Spain uses a Foodini to “re-create forms and pieces” of food that are “exactly the same,” freeing cooks to complete other tasks. In another restaurant, all of the dishes and desserts it serves are 3D-printed, rather than farm to table.

    Nutrition

    Future 3D food printers could make processed food healthier. Hod Lipson, a professor at Columbia University, said, “Food printing could allow consumers to print food to meet their own nutritional needs, like vitamins. So instead of eating a piece of yesterday's bread from the supermarket, you'd eat something baked just for you on demand.”

    Challenges

    Despite recent advancements in 3D food printing, the industry has many challenges to overcome. Currently, most ingredients must be changed to a paste (糊状物) before a printer can use them, and the printing process is quite time-consuming, because ingredients interact with each other in very complex ways. On top of that, most of the 3D food printers now are restricted to dry ingredients, because meat and milk products may easily go bad. Some experts are skeptical about 3D food printers, believing they are better suited for fast food restaurants than homes and high-end restaurants.

    A recent experiment proves that bees can save time and energy when they fly around to different flowers.

    Dr Nigel Raine, from the Royal Holloway University of London, has always been interested in finding out why animal behave like they do. He is also interested in bees. It was not a surprise when he and some other scientists from Queen Mary University of London discovered that bees can quickly solve a problem that takes computers many days.

    Flowers make pollen (花粉), and when bees visit them, they carry the pollen to other flowers. The plants need the pollen to make seeds that will grow. Dr Raine notes that we get a lot of our food from plants, so it is important to know how the bees move around and take the pollen between flowers. The scientists wanted to examine the journey that the bees take and how they save energy when they do this. They completed the experiment on the roof of Queen Mary University, using artificial flowers and a large amount of nectar, a sweet liquid produced by flowers. They taught one bee to visit all the flowers in one place at the same time. When the bee got to know the location of the flowers well, they saw how it flew around and returned home with the nectar. After this, they changed the locations of the flowers. The scientists thought the bee would follow the route it knew already. This would mean that it followed a longer route than it needed to, and so it would use more energy. They watched the bee carefully as it travelled between the flowers in their new location, and they made notes. But in the experiment, the bee changed its route and flew a shorter distance.

    The problem that the bee solved is similar to a maths puzzle called the 'travelling salesman problem'. A salesman who goes to different places to sell things wants to travel the shortest distance. But he has to calculate the length of many possible routes to know which one is the shortest. A computer can calculate this but the experiment shows bees can do the same calculation quickly with a tiny brain. Scientists are very interested in how they do this. It would help us to understand how pollen is moved around. In addition, if they find this out, it could help us to improve communication networks. This might help humans to reduce traffic jams when there is an accident, for example.

    Some students prefer a part-time job after class to earn some money and improve themselves. Here are some good companies:

    IN-N-Out Burger

    It is the best hamburger shop in the west of America. Regarded as one of the best employers, it offers flexible hours and the highest part-time salaries. Above all, the company treats its employees the way they would like to be treated: like family. However, there is no discount offered to its employees.

    Position: selling assistant (experience required)

    Website: in-n-out.cm

    Starbucks Coffee

    Starbucks has been at the forefront (前沿) of the United States' coffee revolution. Working hours are flexible. Fit twenty hours of work into your week. There is also a 30% discount and a free pound of coffee or box of tea every week.

    Position: assistant coffee taster (experience required)

    Website: starbucks.com

    Whole Foods Market

    Whole Foods Market is the world's largest natural and organic food selling company. With its focus on organic ingredients, Whole Foods Market is all about health. Working hours are free. Benefits include paid-time off and a 20% discount so you can eat like a king or at least like a top chef in training. There are also training courses on health and food every week.

    Position: secretary

    Website: wwholefoodsmarket.com.

    Lands' End

    Lands' End is a Wisconsin-based clothes store that focuses on casual comfort and warmth for the great outdoors. Employees (even part-time employees) have the chance to go to a company-owned entertainment center and get a 25% discount on theme parks and movies, and an invitation to the yearly company picnic. Besides, for part-time employees, they can come to work anytime they like as long as they work for 4 hours a day.

    Position: salesperson

    Website:landsend.com