Americans drove more miles in 2015 than any year since the U.S. government started keeping records 45 years ago. The U.S. Department of Transportation (USDT) recently reported that Americans drove a record of 3.148 trillion miles last year. In case you are wondering, that is enough to take 337 round trips from Earth to Pluto.

    There are a number of reasons why Americans are driving more miles. The social experts agree that the first is the price of gas, which has dropped to the level of the year 2004 in the past year. The American Automobile Association (AAA) said that the average price of gas was just $1.71 a gallon. That could be the lowest price since 2004.

    P.J. Sriraj, a director of the Urban Transportation Center at the University of Chicago, notes that the lower cost to fill up a car is just one reason. Another reason is that more Americans are back to work after the 2008 economic recession, and they drive to their jobs.

    Besides, more Americans have to travel a long distance every day between home and the office. There are a lot of Americans who must travel more than 45 miles per day for their jobs. And as for many, there is not enough public transportation.

    Because of the heavy traffic, roads are becoming more and more crowded. While modern cars are more fuel-efficient, the improvement is not enough to offset more cars on the road. “There is no doubt that driving more will make the air dirtier,” said P.J. Sriraj. And many Americans showed a great concern in a recent survey.

    Barditch High School decided to an All-School Reunion. Over 450 people came to the event. There were tours of the old school building and a picnic at Confederate Park. Several former teachers were on hand to tell stories about the old days. Ms. Mabel Yates, the English teacher for fifty years, was wheeled to the Park.

    Some eyes rolled and there were a few low groans(嘟囔声)when Ms.Yates was about to speak. Many started looking at their watches and coming up with excuses to be anywhere instead of preparing to listen to a lecture from an old woman who had few kind words for her students and made them work harder than all the other teachers combined.

    Then Ms. Yates started to speak:

     “I can't tell you how pleased I am to be here. I haven't seen many of you since your graduation, but I have followed your careers and enjoyed your victories as well as crying for your tragedies. I have a large collection of newspaper photographs of my students. Although I haven't appeared in person, I have attended your college graduations, weddings and even the birth your children, in my imagination.”

    Ms. Yates paused and started crying a bit. Then she continued:

     “It was my belief that if I pushed you as hard as I could, some of you would succeed to please me and others would succeed to annoy me. Regardless of our motives, I can see that you have all been successful in you chosen path.”

     “There is no greater comfort for an educator than to see the end result of his or her years of work. You have all been a great source of pleasure and pride for me and I want you to know I love you all from the bottom of my heart.”

    There was a silence over the crowd for a few seconds and then someone started clapping. Tee clapping turned into cheering, then into a deafening roar(呼喊). Lawyers, truck drivers, bankers and models were rubbing their eyes or crying openly with no shame all because of the words from a long forgotten English teacher from their hometown.

    Fashions have a lot of rules. Most of them, however, are just wrong. But there's one rule that goes beyond tradition and into the field of scientific study of the brain: Black clothes are slimming. It all comes down to how your visual system processes the light. The below holes in each square are the same in size, yet the white hole looks bigger than the black hole.

    In the 1500s, Galileo Galilei noticed that some of the planets looked larger when viewed with the naked eye than they did when viewed through a telescope, making the white light of Venus appear eight to ten times larger than Jupiter in the night sky. He knew something strange must be going on with his vision to cause this illusion, but he wasn't sure what it was. Luckily, scientists never stopped wondering, and in 2014, they figured it out.

    Our visual system operates via two main channels: "on" neurons (神经元) that are sensitive to light things and "off" neurons that are sensitive to dark things. When it came to the dark "off" neurons, the researchers found that they responded predictably to dark shapes on a light background the greater the contrast between the two, the more active these neurons were. But the light on" neurons behaved unpredictably. Even with the same amount of contrast, light objects on a dark background caused a greater response in these neurons.

    This phenomenon makes some sense, evolutionarily speaking. In the dark of night, you'd want to be able to take in every bit of light you can get, so a visual system that enlarges light objects on a dark background could be very useful. However, it's not that hard to see dark objects in the light of day. It has some effects in the colors of your clothes and in the appearance of the planets—the brighter appearance of Venus in the night sky makes it look bigger than the darker Jupiter.

    There were smiling children all the way. Clearly they knew at what time the train passed their homes and they made it their business to stand along the railway, wave to complete strangers and cheer them up as they rushed towards Penang. Often whole families stood outside their homes and waved and smiled as if those on the trains were their favorite relatives. This is the simple village people of Malaysia. I was moved.

    I had always traveled to Malaysia by plane or car, so this was the first time I was on a train. I did not particularly(特别) relish the long train journey and had brought along many magazines to read and reread. I looked about the train. There was not one familiar face. I sighed and sat down to read my Economics.

    It was not long before the train was across the Causeway and in Malaysia. Johor Bahru was just a city like Singapore, so I was tired of looking at the crowds of people as they hurried past. As we went beyond the city, I watched the straight rows of rubber trees and miles and miles of green. Then the first village came into sight. Immediately I came alive, I decided to wave back.

    From then on, my journey became interesting. I threw my magazines into the waste basket and decided to join in Malaysian life. Then everything came alive. The mountains seemed to speak to me. Even the trees were smiling. I stared at everything as if I was looking at it for the first time.

    The day passed fast and I even forgot to have my lunch until I felt hungry. I looked at my watch and was surprised that it was 3:00 pm. Soon the train pulled up at Butterworth. I looked at the people all round me. They all looked beautiful. When my uncle arrived with a smile, I threw my arms around him to give him a warm hug. I had never done this before. He seemed surprised and then his weather-beaten face warmed up with a huge smile. We walked arm in arm to his car.

    I looked forward to the return journey.

Ida Nelson and her sister were relaxing and enjoying themselves in the sauna (桑拿室) when she heard a series of long low sounds from a small airplane circling the nearby airport.

It was 11:30 at night in the Alaskan village of Igiugig, population 70, and, as she told the reporter, "Any time a plane flies over that late, you know something is wrong."

Nelson and her sister leaped out of the sauna, ran to the window, and saw the problem: The airport's runway lights were out.

Nelson threw on some clothes, jumped into her ATV, and floored it to the airport, where she found a local pilot trying to turn on the lights manually.

"Normally, if you push the button 10 or 15 times, the lights will just light up," Nelson told KTOO out of Juneau. Not this time. Meanwhile, she and the pilot learned of the plane's urgent mission: It was a medevac (医疗救护直升机), there to transport a seriously ill local girl to the nearest hospital, 280 miles away in Anchorage.

Nelson had a plan. Driving her ATV to the end of the runway, she shone her headlights for the plane to follow. Great idea, but it wasn't enough. More light was needed, so a neighbor called nearly every home in the village—32 of them.

Within 20 minutes, 20 vehicles arrived at the airport, many of the drivers still in pajamas (睡衣). Following directions from the medevac pilot, the cars lined up on one side of the runway.

The medevac made its final approach and, guided by the headlights, landed safely. The young patient was loaded onto the aircraft, and the plane immediately took off again. Her illness was never publicly revealed, but she has since been released from the hospital.

In a world filled with uncertainty, the little community's positive activism was a big deal. Not so much for Nelson. As she told the reporter, in Igiugig, coming together "is kind of a normal deal."

For future humans to survive long periods on Mars, growing food on the planet is a must. It would be too costly and risky to rely upon rocket deliveries to meet the food needs of settlers. With this in mind, scientists are exploring ways to improve space farming.

Researchers work in a controlled greenhouse. They have identified a way that could improve crop production in simulated （模拟的） Martian soil, with different crops grown together. The method is called "intercropping", invented by ancient Maya farmers in what is now Central America.

In their experiments, the researchers grew cherry tomatoes, peas and carrots together in small, round containers. Tomatoes grown in this way produced about double the amount of tomatoes grown alone—or "monocropped"—in the same simulated Martian soil. The tomatoes were also bigger. They flowered and matured earlier, gave more fruit per plant and had thicker stems. The amounts of peas and carrots did not increase with intercropping.

Rebeca Goncalves, an astrobiologist and lead writer of the study, said the research is the first time the intercropping technique was used in space soil, and that it was a big find—one that they could now build further research on. The crops were grown in simulated Martian regolith, a soil with no organic matter —a near-perfect physical and chemical match to real Martian soil.

The researchers added useful bacteria and nutrients. They also controlled the gases, temperature and humidity inside the greenhouse to match conditions expected in a Martian greenhouse. Intercropping involves growing plants with properties that could help each other grow. The method makes the best use of resources including water and nutrients.

The researchers said the tomato plants in intercropping may have benefited from being close to the pea plants. That is because the peas are good at turning nitrogen from the air, with the help of bacteria introduced into the soil, into an important nutrient. Overall, the tomatoes, peas and carrots grew well, though not as well as in Earth soil in the same greenhouse.