China is a land of bicycles. At least it was back in 1992 when I traveled the country. Back then everyone seemed to be riding a bicycle. Millions of them, all black. Cars were rare. Yet since my arrival in Beijing last year, I've found the opposite is true. There are millions of cars. However, people still use their bicycles to get around. For many, it's the easiest and cheapest way to travel today. Bicycles also come in different colors — silver, green, red, blue, yellow, whatever you want.

    It's fun watching people biking. They rush quickly through crossroads, move skillfully through traffic, and ride even on sidewalks. Bicycles allow people the freedom to move about that cars just can't provide.

    Eager to be part of this aspect of Chinese culture, I decided to buy a bicycle. Great weather accompanied my great buy. I immediately jumped up on my bicycle seat and started home.

    My first ride home was orderly (守秩序的). To be safe, I stayed with a “pack” of bikers while cars on the streets came running swiftly out of nowhere at times. I didn't want to get hit. So I took the ride carefully.

    Crossing the streets was the biggest problem. It was a lot like crossing a major highway back in the United States. The streets here were wide, so crossing took time, skill and a little bit of luck.

    I finally made it home. The feeling on the bicycle was amazing. The air hitting my face and going through my hair was wonderful. I was sitting on top of the world as I passed by places and people. Biking made me feel alive.

    Failure is probably the most exhausting experience a person ever has. There is nothing more tiring than not succeeding.

    We experience this tiredness in two ways: as start-up fatigue (疲惫) and performance fatigue. In the former case, we keep putting off a task because it has either too boring or too difficult. And the longer we delay it, the more tired we feel. Such start-up fatigue is very real, even if not actually physical, not something in our muscles and bones. The solution is obvious though perhaps not easy to apply: always handle the most difficult job first.

    Years ago, I was asked to write 102 essays on the great ideas of some famous authors. Applying my own rule, I determined to write them in alphabetical (按字母顺序), never letting myself leave out a tough idea. And I always started the day's work with the difficult task of essay-writing. Experience proved that the rule works.

    Performance fatigue is more difficult to handle. Though willing to get started, we cannot seem to do the job right. Its difficulties appear so great that, however hard we work, we fail again and again. In such a situation, I work as hard as I can — then let the unconscious take over.

    When planning Encyclopaedia Britannica (《大英百科全书》), I had to create a table of contents based on the topics of its articles. Nothing like this had ever been done before, and day after day I kept coming up with solutions, but none of them worked. My fatigue became almost unbearable.

    One day, mentally exhausted, I wrote down all the reasons why this problem could not be solved. I tried to convince myself that the trouble was with the problem itself, not with me. Then, I sat back in an easy chair and fell asleep.

    An hour later, I woke up suddenly with the solution clearly in mind. In the weeks that followed, the solution which had come up in my unconscious mind provided correct at every step. Though I worked as hard as before, I felt no fatigue. Success was now as exciting as failure had been depressing.

    Human beings, I believe, must try to succeed. Success, then, means never feeling tired.

    There's a new achievement 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(大规模地). And the industry isn't stopping there.

    Food production

    With a 3D printer, a cook can print complicated 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(消费者) to print food with customized(定制的) nutritional content, 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 (烹饪原料) 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 limited to dry ingredients, because meat and milk products may easily go bad. Some experts are doubtful about 3D food printers, believing they are better suited for fast food restaurants than homes and high-end restaurants.

    As any plane passenger will confirm, a crying baby is almost impossible to ignore, no matter how hard you try. Now scientists believe they may have worked out why. A baby's cry pulls at the heartstrings(扣人心弦) in a way while other cries don't, researchers found.

    Researchers found that a baby's cry can trigger unique emotional responses in the brain, making it impossible for us to ignore them—whether we are parents or not. Other types of cries, including calls of animals in great pain, fail to get the same response—suggesting the brain is programmed to respond specifically to a baby' cry.

    A team of Oxford University scientists scanned the brains of 28 men and women as they listened to a variety of calls and cries. After 100 milliseconds—roughly the time to blink(眨眼)—two parts of the brain that respond to emotion lit up. Their response to a baby's cry was particularly strong. The response was seen in both men and women—even if they had no children.

    Researcher Dr Christine Parsons said, “You might read that men should just notice a baby and step over it and not see it, but it's not true. There is a special processing in men and women, which makes sense from an evolutionary view that both men and women would be responding to these cries.” The study was in people who were not parents, yet they are all responding at 100ms to these particular cries, so this might be a fundamental response present in all of us regardless of parental status.

    Fellow researcher Katie Young said it may take a bit longer for someone to recognize their own child's cries because they need to do more “fine-grained analysis”. The team had previously found that our reactions speed up when we hear a baby crying. Adults performed better on computer games when they heard the sound of a baby crying than after they heard recordings of adults crying.

    Throughout history scientists have risked their health and their lives in their search for the truth.

    Sir Isaac Newton, the seventeenth century scientist, was very smart, but that didn't stop him from doing some pretty stupid things. In his laboratory in Cambridge he often did the strangest experiments. Once, while testing how light passes through lenses (晶状体), he put a long needle into his eye, pushed it to the back, and then moved it around just to see what would happen. Luckily, nothing long-lasting did. On another occasion he stared at the sun for as long as he could bear, to discover what effect this would have on his sight. Again he escaped suffering permanent damage, though he had to spend some days in a darkened room before his eyes recovered.

    In the 1750s the Swedish chemist Karl Scheele was the first person to find a way to produce phosphorus (磷). He in fact discovered eight more chemical elements including chlorine (氯), though he didn't get any praise for them. He was a very clever scientist, but his one failing was a curious habit of tasting a little of every substance he worked with. This risky practice finally caught up with him, and in 1786 he was found dead in his laboratory surrounded by a large number of dangerous chemicals, any of which might have been responsible for his death.

    Eugene Shoemaker was a respected geologist. He spent a large part of his life studying craters (火山口) on the moon, and how they were formed, and later did research into the comets of the planet Jupiter. In 1997 he and his wife were in the Australian desert where they went every year to search for places where comets might have hit the earth. While driving in the Tanami desert, normally one of the emptiest places in the world, another vehicle crashed into them and Shoemaker was killed on the spot. Some of his ashes (骨灰) were sent to the moon aboard the Lunar Prospector spacecraft and left there — he is the only person who has had this honor.

A storm hit Houston, Texas, on Tuesday. It brought heavy rains and rising flood-waters. By Tuesday night, some parts of the city had received 10 inches of rain. Police and firefighters helped people move to safe places. They also saved people from cars and buses that were stuck on roads.

Certain areas around Houston were hit really hard. In just four hours, more than seven inches of rain fell in Sugar Land in the southwest of Houston. Cars could not pass through any of the areas main roadways. On Twitter, Sugar Land city officials asked people to get to high ground.

Tuesday's rain hit parts of Texas that Hurricane Harvey had already damaged almost two years ago. Hurricane Harvey in August, 2017 was the second most costly hurricane in US history. It caused $125 billion worth of damage in Texas. In the Houston area, 36 people died and about 150, 000 homes were flooded.

A spokesman for the Harris County Office of Homeland Security and Emergency Management spoke with the Houston Chronicle. The spokesman said that this week's rain is "not in any way a Harvey-level event."

But the worst may not be over yet. People will have a break from the heavy rain on Wednesday. According to the National Weather Service, the Texas Gulf Coast will continue to experience heavy rain later in the week. "Today should be our quietest over the next few days for rainfall," said Don Oettinger, a National Weather Service meteorologist (气象学家).

Houston Fire Chief Samuel Peia warned, "As there is too much water on the ground, these are perfect conditions for flash floods, so we hope people are careful of what they're doing and encourage them to stay home. There's no sense in putting yourself, firefighters or anybody in danger needlessly."