【推荐1】Every human being, no matter what he is doing, gives off body heat. The usual problem is how to get rid of it.   But the designers of the Johnstown campus (校园) of the University of Pittsburgh set themselves the opposite problem — how to collect body heat.   They have designed a collection system which uses not only body heat, but the heat given off by such objects as light bulbs and refrigerators as well. The system works so well that no fuel is needed to make the campus’s six buildings comfortable.

Some parts of most modern buildings — theaters and offices as well as classrooms, are more sufficiently heated by people and lights and sometimes must be air-conditioned (使用空调的) even in winter. The technique of saving heat and redistributing (再分配) it is called “heat recovery”. A few modern buildings recover heat, but the University’s system is the first to recover heat from buildings and reuse it in others.

Along the way, Pittsburgh has learned a great deal about some of its producers.   The harder a student studies, the more heat his body gives off.   Male students send out more heat than female students, and the larger a student is, the more heat he produces. We may conclude that the hottest prospect for the Johnstown campus would be a hard working overweight male genius.

【推荐1】Nostalgia (怀旧) has become increasingly common in the current accelerated, unexpected changes. More and more Americans are turning back with longing to what feels like simpler, sweeter times. They collect cassette tapes, manual typewriters, even decades-old video games.

Is it a mistake to miss the past? Some psychologists warn that too much devotion to the so-called good old days is an escape from reality; it suggests loneliness or that a person is having a difficult time coping in the present. Psychologist Stephanie Coontz argues that nostalgia distracts us from addressing the problems of modern life and contributes to anxiety, depression, sleeplessness, etc.

But new studies suggest that a modest amount of nostalgia is not only harmless, but actually beneficial. They suggest it helps strengthen our sense of identity and makes us feel more optimistic and inspired. It is also a tool for self-discovery and memories are a psychological response when you want to take a break from negativity. Recalling our childhood reminds us of “the times when we were accepted and loved unconditionally,” says Krystine Batcho, a psychologist. “That is such a powerful comfort, knowing that there was a time in life when we didn’t have to earn our love.” Nostalgia can turn even the most ordinary past into legends which warms the heart and the body. Let’s not forget that nostalgia has been a source of inspiration to countless American writers. Mark Twain recalled his boyhood, writing, “After all these years, I can picture that old time to myself now, just as it was then.”

So go ahead, daydream a little about your best childhood friend, a long-gone family pet, etc. As Dr. Sedikides says, “Nostalgia is absolutely central to human experience.” But at the same time, keep these words of wisdom from the great inventor Charles Kettering in mind as well: “You can’t have a better tomorrow if you are thinking about yesterday all the time.”

【推荐2】I heard many parents complaining that their teenage children are rebelling(叛逆). I suggested they recall their own teenage years. At that age they would like to be growing away from parents. They preferred to stand on their own two feet. But take a good look at the present rebellion. It seems that teenagers are taking the same way of showing that they disagree with their parents. Instead of going out fighting bravely on their own, most of them are clutching (紧握) at one another’s hands for reassurance.

They declare they want to dress as they like. But they all wear the same clothes. They set off in new directions in music. But somehow they all end up gathering around listening to the same record. Their reason for thinking or acting in a similar way is that the crowd is doing it. They have come out of their cocoon (蚕茧) into a larger cocoon.

It has become harder and harder for a teenager to stand up against the popularity wave and to go his or her own way. Industry has firmly carved out a teenage market. These days every teenager can learn from the advertisements what a teenager should have and be. And many of today’s parents have come to award high marks for the popularity of their children. All this create a great barrier for the teenager who wants to find his or her own path.

But the barrier is worth climbing over. The path is worth following. You may want to listen to classical music instead of going to a party. You may want to collect rocks when everyone else is collecting records. You may have some thoughts that you don’t care to share at once with your classmates. Well, go for it. Find yourself. Be yourself. Popularity will come — with the people who respect you for who you are. That is the only kind of popularity that really matters.

【推荐3】Recently, I had lunch with a young Chinese student who studies at a college in New York. He is very bright and ambitious and I enjoyed our conversation. Still, I felt upset and useless afterwards because I was not able to provide him with any good news. Graduating at the end of this year, he asked me how he could find a job in this country and fulfill his career dreams.

In recent years, students who found a job here after graduation have had to go through a cruel lottery system to obtain their H-1B working visa. And the success rates have been declining year after year because of the ever growing number of applicants. Last year, there were 233,000 applicants and only 30 percent of them were lucky, about half of the rate in 2013.

And it can only become worse. US former President Donald Trump’s immigration policies in this country have been tightening up and this trend will continue for at least the next few years. In this case, foreign students studying social sciences, a field in which starting salaries are rarely above the required amount, can kiss their visa hopes goodbye.

Compared to the older generation of Chinese students, today’s young people no longer consider the US as the only option. Many start to think China offers better opportunities in the longer term.

This is not to say that Chinese students in the US are not interested in job opportunities here any more. A few years of work experience in the US can give them advantages when they finally land back in their home country. But if the job opportunities are largely reduced by the tightening of immigration policy, I expect there will be a decline. And if that happens, it is the American economy that will suffer from the loss of those educated, hard-working and talented immigrants.

【推荐1】The famous scientist Stephen Hawking spoke at a science festival in Norway in 2017, “We are running out of space and the only places to go to are other worlds... Spreading out may be the only thing that saves us from ourselves. I’m convinced that humans need to leave Earth.”

Hawking was not alone in this view. Many experts feel that the only way for humanity to last far into the future is to colonize (移民于) other planets. That way, if a terrible disease, nuclear war or some other disaster strikes Earth, civilization as we know it would still have a chance. Mars is one of the most attractive destinations. NASA, the United Arab Emirates, the private company SpaceX, and the organization Mars One all have plans to send humans there. “Either we spread Earth to other planets, or we risk going extinct,” SpaceX founder Elon Musk said at a conference in 2013.

But not everyone agrees that colonizing Mars or any other planet is such a great plan. The most common argument against going is that it’s just too expensive or dangerous. It will take huge amounts of money and other resources just to get people there, let alone set up a place for them to live. It’s not even clear if humans could survive on Mars. One of the biggest dangers there is deadly radiation that ruins the planet.

Maybe all the time and money people would pour into a Mars mission would be better spent on more urgent projects here on Earth, like dealing with poverty or climate change. Some experts argue that handling a problem like an asteroid (小行星) strike or disease outbreak while staying here on Earth would be much easier and less expensive than surviving on a new planet.

In addition, moving to a new planet could harm or destroy anything that already lives there. Mars seems uninhabited, but it could possibly host micro-organism like. Human visitors may destroy this life or permanently change or damage the Martian environment. Some feel that’s too much of a risk to take.

【推荐2】Which is better for Earth: an electric or gas-powered vehicle? The answer to this question might seem blindingly obvious: Of course electric cars must be better for the environment, because they don’t give off greenhouse gases as people drive. However, electric vehicles (EVs) aren’t perfect, and they come with their own set of polluting problems. Their batteries require a large amount of energy to produce.

Battery production is just one part of an electric car’s life span. A study looked at the entire life cycle of an EV’s emissions (排放), from mining the metals for the batteries to producing the electricity needed to power them, and then compared this with the average emissions of a gas-powered vehicle. The team found that when EVs are charged with coal-powered electricity, they’re actually worse for the environment than gas-powered cars.

“Only when connected to the dirtiest, coal-heavy electric grids (电网) do gas-powered cars become comparable to EVs on a greenhouse gas basis,” said Colin Sheppard, an expert in energy and transportation systems. That’s why more and more countries are decreasing the power supply from coal. In China, the national grid is improving with more investments in renewable energy. For example, it has twice as much wind energy capacity as the U.S. and it builds more solar panels per year than any other countries.

Sheppard modelled a future in which all cars were electric. “We wanted to understand what it might be like if all passenger vehicles are electrified.” For example, Sheppard calculated that if all vehicles in the U.S. were electric, it would reduce greenhouse-gas emissions by 46% every year. This reduction could be increased even further if those vehicles were using a technique known as “smart charging” in which cars are recharged at chosen times (often at night) to reduce the cost of electricity.

In short, it’s far easier to argue in favor of buying an EV than a gas-powered vehicle. But what about the cost? Aren’t electric vehicles too expensive for most people?