Every man wants his son to be somewhat of a clone, not in features but in footsteps. As he grows, you also age, and your ambitions become more unachievable. You begin to realize that your boy, in your footsteps, could probably achieve what you hoped for. But footsteps can be muddied and they can go off in different directions.

    My son Jody has hated school since day one in kindergarten. Science projects waited until the last moment. Book reports weren't written until the final threat.

    I've been a newspaperman all my adult life. My daughter is a university graduate working toward her master's degree in English. But Jody? When he entered the tenth grade, he became a “vo-tech(技校)” student. They're called “motorheads” by the rest of the student body.

    When a secretary in my office first called him “motorhead”, I was shocked. “Hey, he's a good kid,” I wanted to say. “And smart, really.”

    I learned later that motorheads are, indeed, different. They usually have dirty hands and wear dirty work clothes. And they don't often make school honor rolls(光荣榜).

    But being the parent of a motorhead is itself an experience in education. We, who work in clean shirts in offices, don't have the abilities that motorheads have. I began to learn this when I had my car crashed. The cost to repair it was estimated at $800. “Hey, I can fix it,” said Jody. I doubted it, but let him go ahead, for I had nothing to lose.

    My son, with other motorheads, fixed the car. They got parts(零件) from a junkyard, and ability from vo-tech classes. The cost was $25 instead of $800.

Since that first repair job, a broken air-conditioner, a non-functioning washer and a non-toasting toaster have been fixed. Neighbors and co-workers trust their car repairs to him.

    These kids are happiest when doing repairs. They joke and laugh and are living in their own relaxed world. And their minds are bright in spite of their dirty hands and clothes.

    I have learned a lot from my motorhead: publishers need printers, engineers need mechanics, and architects need builders. Most importantly, I have learned that fathers don't need clones in footsteps or anywhere else.

My son may never make the school honor roll, but he made mine.

    It's said that you don't know a man until you walk a mile in his shoes. And you also don't know what it's like for older people to travel until you accompany one on a trip.

    After flying with my elderly father from Washington, D.C. to L.A. in July, I began to realize that a companion has important tasks that can make a journey easier for older people. I booked nonstop tickets on JetBlue to avoid tiring, confusing connections, and we flew directly into small, manageable Long Beach Airport. Even though my father could walk, I arranged with the airline for wheelchair assistance, which meant we got on board first.

    When I took him back to the airport for his return flight to Washington, I got permission from JetBlue to wait with him at the gate instead of saying goodbye at the security checkpoint. I wished he'd had a first-class seat and access to a comfortable airline club. Better yet, I wish I had flown with him both ways. As I watched the attendant wheel him to the lift that took him from the tarmac（飞机跑道）to the plane, I felt like an anxious mom sending her child to school for the first time.

    Things can go awry on a plane trip. And then there is the horrifying story about Joe and Margie. When they landed at Dallas-Fort Worth International Airport, a wheelchair attendant met them to help with a connection. But somehow Margie, who had Alzheimer's disease, disappeared.

    I didn't need to worry about my father wandering away; at 82, his mind was sharper than mine. But his hearing was poor, so I worried about what would happen if he missed an important announcement. Fortunately, everything went just fine. Careful planning made the trip successful.

    Next time I travel with a senior, I'll know better. I hope there will be a next time.

    Humans' invention of zero was vital for modern mathematics and science, but we're not the only species to consider “nothing” a number. Parrots and monkeys understand the concept of zero, and now bees have joined the club, too.

    Honey bees are known to have some numerical skills such as the ability to count to four, which may come in handy when keeping track of landmarks in their environment. To see whether these abilities extended to understanding zero, researchers trained 10 bees to identify the smaller of two numbers. Across a series of trials, they showed the insects two different pictures displaying a few black shapes on a white background. If the bees flew to the picture with the smaller number of shapes, they were given delicious sugar water, but if they flew toward the larger number, they were punished with bitter-tasting food.

    Once the bees had learned to consistently make the correct choice, the researchers gave them a new choice: a white background containing no shapes at all. Even though the bees had never seen an empty picture before, 64% of the time they chose it rather than a picture containing two or three shapes, the authors report today in Science. This suggests that the insects understood that “zero” is less than two or three. And they weren't just going for the empty picture because it was new and interesting. Another group of bees trained to always choose the larger number tended to pick the nonzero image in this test.

    In further experiments, the researchers showed that bees' understanding of zero was even more complex: for example, they were able to distinguish between one and zero-a challenge even for some other members of the zero club. Advanced numerical abilities like this could give animals an evolutionary advantage, helping them keep track of predators（捕食者）and food sources. And if an insect can display such a thorough grasp of the number zero, write the researchers, then this ability may be more common in the animal kingdom than we think.

    Being an astronaut sounds cool, doesn't it? In space, they get to do some pretty amazing things, like floating (漂浮) in zero gravity(重力).

    However, there are also plenty of things that astronauts can't do because of their weightless environment(环境), and that's very sad. What's worse, they can't even let their sadness show -because it's impossible to cry in zero gravity.

    Of course, astronauts can still produce tears. But crying is much more difficult in space, reported The Atlantic in January. Without gravity；tears don't flow downward out of the eyes like they do here on Earth. This means that when you cry in space, your tears have nowhere to go — they just stick to your eyes.

    In May 2011, astronaut Andrew Feustel experienced this during one of his spacewalks. "Tears," he said, "don't fall off your eye...They just kind of stay there."

    Besides making your vision(视觉) unclear, this can also cause physical pain. Back on Earth, tears are supposed to bring comfort to the eyes. But that's not the case in space. The space environment dries out astronauts' eyes, and when tears suddenly wet the eyes, it can cause pain rather than comfort. "My right eye is painful like crazy." Feustel told his teammate during the walk.

    Since gravity doesn't work in space, astronauts need some extra help to get rid of the tears. Feustel chose to rub his eyes against his helmet to wipe the tears away. Another choice is to just wait — "When the tears get big enough they simply break free of the eye and float around," astronaut Ron Parise told The Atlantic.

    There are lots of small things — things like crying — that we are so used to on Earth, we usually take them for granted, until they become a problem in a totally different environment, like space. There, astronauts can't talk to each other directly. They also can't eat or drink in normal ways. They can't even burp (打嗝), because there is no gravity to hold the food down in their stomach. If they do burp, they just end up throwing up (呕吐) everything in their stomach, according to the UK National Space Center.

    Thus, perhaps it's only space explorers who can honestly say, "Gravity, you're the best."

    Many Americans think of driverless cars as a futuristic technology that will revolutionize travel in cities and along state highways. But recent experiments are proving that autonomous vehicles also have the potential to improve the quality of life for millions of Americans underserved by traditional ways of transportation, such as the elderly and disabled, so long as lawmakers make smart policies that pave the way for innovation.

    A retirement community in San Jose, Calif, which has been transformed by a small fleet (车队) of driverless taxis, shows the potential of self-driving cars to transform people's lives. Built by a tech start-up called Voyage, the modified (被改进的) Ford Fusions are currently limited to a two-mile road, but residents are already having the benefits of these autonomous vehicles, which allow them to participate in social activities they would otherwise be unable to enjoy simply because they could not get to them.

    When the trial run finally expands to 15 miles of road, these residents—whose average age is 76—will also have a convenient and reliable new way to appointments. As these cars continue to serve residents there, it is easy to understand why California is moving to simplify regulations for the industry.

    In Michigan, forward-thinking policies have the potential to unlock other hidden benefits of autonomous vehicles, especially for those with physical disability. The Michigan Disability Rights Coalition has strongly advocated for the development of this technology, saying that it could give people with disabilities greater opportunities in the workforce and enable them to lead more fulfilling (满意的), independent lives.

    Many recognize that autonomous vehicles will be the future of transportation, but it is too often overlooked that this future cannot arrive fast enough for millions of Americans who are forced to depend on others for day-to-day travel. The policymakers should follow the lead of places like California and Michigan, and pass rules and regulations to unlock these hidden benefits of driverless cars.

    Here are some great people and their achievements.

    Mary Anderson ­ windscreen wiper.

    Back on a freezing winter's day in 1902, Mary Anderson was travelling by train through New York City. Snow was falling, forcing the driver to stop repeatedly and get out to clear it. Each time the door opened, Mary suffered a gust of sub-zero air. She had an idea: why not make some kind of a rubber blade that could be operated from inside the vehicle? And that's exactly what she did.

    Josephine Cochrane ­ dishwasher

    The dishwasher dates back even earlier to the 19th century, and to the dinner parties thrown by a lady called Josephine Cochrane. As a frequent host, she wanted a machine that could wash dishes faster than people. Her response was to develop what was to become the first commercially successful dishwasher. Interestingly, innovation was in her blood: her grandfather had invented the steamboat.

    Stephanie Kwolek ­ Kevlar

    Kevlar is the lightweight fibre used in bulletproof vests. The material is used by millions every day and has saved countless lives. The super tough fabric is also used in objects ranging from gloves to airplanes. Incredibly, its strength-to-weight ratio(比强度) is five times higher than steel. Again, it was invented by a woman, the American chemist Stephanie Kwolek, in 1964.

    Grace Hopper ­ first compiler(编译程序)

    One of the most important inventions of the 20th century must surely be the computer programme. The world of programming is unbalanced in terms of gender. Men vastly outnumber women, and take home around 30% more pay than their female counterparts on average. But back in the 1940s and 1950s, women were at the forefront of this new field. Grace Hopper is credited with inventing the first compiler in 1952, which serves as the bridge between code and the binary(二进制的) ones and zeros understood by computers.