We may not be aware of it, but ordinary family homes in the U.S. and the rest of the world are not energy-efficient.

    Most of their energy goes to heating and cooling, and a lot of it is wasted, as warm air and cool air escape through fireplace chimneys and thin or poorly fitting windows and doors. A passive house loses almost none."Imagine a thermos(保温瓶),"said housing developer Brendan O'Neill."You have insulation(隔绝) everywhere, and it's basically completely sealed. And so the idea is to build a house like a thermos. So the windows are sealed. There's insulation completely surrounding the building. We make it as sealed as possible."

    A 147-square-meter passive house, presented by O'Neill Development Corp. as a demonstration unit just outside Washington, was brought to the site in two boxes. "Once it's set and put together, it takes about four weeks to complete the outside construction, to put down carpets," O'Neill said. "If everything is set in place, you put a house like this together in about four months.”The total cost of building it was $325,000, or about 17 percent more than constructing an ordinary house. But its utility(公用事业) bill is only around $20 monthly, or one-tenth the amount for the average house of the same size.

    While passive houses have been around for a long time, the idea has never taken root in the U.S. There was no driving force to push it.

    However, David Peabody, an architect who designs passive houses said, "I think climate change is now becoming a larger issue. And I think building standards are catching on to that. So people are becoming more aware of energy."Peabody said the cost of building passive houses could come down."What really makes sense for truly affordable housing," he said, "is to build multi-storey buildings."

    In high school, all Canadian students take part in a very exciting event. It is "Take Your Children to Work Day". Students will have a chance to work with their parents. My day took place in my mom's work, the York Region Police Department.

    When I arrived, a coach was teaching the officers basic combat(格斗)skills. Everyone tried their best to practice. I could see them sweating and panting (喘气).

    The most exciting part of my visit was a stop at the 911 Communication Center. 911 is the same as 110,119 and 120 in China. Every 911 call in the city is answered here. When I entered the center, I stood beside a call dispatcher (分派人员)arid watched him dealing-with the calls.

    Suddenly, the phone rang, he picked it up and a woman cried for help. There was a robbery in her house. The call dispatcher told her, "Please calm down and move to the safe place quietly. Don't fight with them. Just let them take what they want. Please make sure you are not hurt. We are sending officers there."

    He followed the call and found the address. The call dispatcher chose the five closest police cars from the satellite map and clicked(敲键盘) to send the policemen.  I saw the police cars from the satellite map were quickly moving to the woman's house. Five minutes later, they arrived .I asked the call dispatcher why he sent five cars. He said, "There are different levels of emergencies. Robbery is a high priority (优先),so we have to send five cars." The day was interesting. I leaned how the different departments worked together. The officers were very friendly and admirable.

    Dolphins (海豚) live in a dark underwater world. It's often impossible to see each other or anything else around them, so sound plays an important role in their survival. To communicate with each other, dolphins produce all kinds of sounds.

    Only other dolphins understand what the sounds mean. Scientists haven't uncovered their secret communication, except for one kind of whistle. It might last less than a second, but this whistle is a big deal. Why? Because these whistles are actually names of dolphins — and every dolphin has one. Scientists call these sounds a “signature whistle.” When other dolphins hear the whistle, they know which dolphin is calling.

    Dolphins often hunt by themselves but still need to stay connected to the group. Since they can't always see each other, dolphins use their signature whistles to check in with other dolphins hundreds of yards away. “In coastal areas, dolphins exchange whistles even when they're a third of a mile apart,” says Greg Campbell, who studies animals. That means dolphins shout out to group members that might be nearly five football fields away.

    What's amazing is who names the baby dolphin. Not the mother. Not an auntie dolphin or another group member. Scientists believe the baby dolphin itself comes up with the signature whistle. Like human babies, a baby dolphin plays with sounds throughout its first year. While testing its sound skills, a baby dolphin is doing something amazing. It's creating or figuring out its signature whistle. How or why it chooses its signature whistle is not clear. Studies show that most of the time the signature whistle is nothing like its mother's or group members' whistles.

    When the baby dolphin is about a year old, its signature whistle is set. It repeats it often so the other dolphins learn to recognize it.

    Deciphering(破译) dolphin names is just the beginning of figuring out what dolphins communicate about. Do they chat about sharks? Discuss the tides? Maybe they even have a name for people. Someday scientists are to decipher the rest of dolphins' communication.

    You may have never heard of Lanthanum, Cerium or Neodymium, but these elements (元素) and others known as “rare earth” play a major role in modern technology. They can actually be found in many places on the earth, but not in quantities that can be mined. Only a few countries — China, America, India, Australia, Brazil and Malaysia have any that can be mined enough to be traded.

Even though some of these elements such as Cerium are as abundant as Copper, they are not found in concentrated amounts on the earth's surface. They are often mixed together with other metals, which makes extraction (提取) of these elements an expensive and an environmentally messy process. It was due to this reason that the term “rare earth” was invented.

    Rare earth metals are used widely in our life. Rechargeable car batteries, computers, iPhones, DVD players, computer monitors, televisions, lighting, lasers, glass polishing, and superconductors all use quantities of rare earth metals. Also, with the advancement in “green” technology like solar panels, these shiny materials are becoming more important than ever. An average electric car uses 10 pounds of Lanthanum for its rechargeable battery!

    America has large deposits (存储量) of rare earths and has one of the first mines. It was openedin Southern California in 1940. The element “Europium” was the first metal to be separated in quantity for use in color televisions. However, in the 1980's and 1990's, as China started producing these elements in Inner Mongolia, the mines in America and elsewhere could not keep pace. The mine in Mountain Pass, California also failed environmental regulations and shut down in 2002.

    Now, recognizing the importance of having more than one supplier of this important resource, other rare earth owning countries like India and Australia are either dusting off their rare earth mines or speeding up their production. It is believed that the debate over rare earths will become louder in the coming months and years.

    A new study by Chinese researchers has found differences in the brain activity of men and women addicted(上瘾的)to Internet gaming.

    The study says addicted men have lower impulse control compared with women, indicating that men are more likely to become addicted to internet gaming.

    Researchers from Renji Hospital, which is connected with Shanghai Jiaotong University, recruited 105 Chinese participants for the study, which had two groups - one with 32 men and 23 women addicted to gaming, and the other with 30 men and 22 women who were not addicted.

    They completed a questionnaire for gaming addiction, and reported their gaming history and number of hours playing per week. Researchers also talked with their families to collect the information.

    Through FMRI (磁共振扫描), researchers found that men addicted to gaming had lower brain activity in the brain region associated with impulse control, than nonaddicted men. The lower the activity levels, the poorer the impulse control. Addicted women, however, showed no differences compared with the healthy female group.

    Researchers also studied the functional connectivity between brain regions, which were lower in men with addiction than in nonaddicted men, but showed no differences in the female groups.

    Although there are some limitations, the findings suggest that activity levels displayed in the brain region could be biomarkers to evaluate the behavioral inhibitions of gaming-addicted men, they said.

    Gaming disorder was listed as a mental disorder by the World Health Organization earlier this year. People with the disorder have impaired control over gaming and give it increased priority in their lives－to the extent that gaming takes precedence over other life interests and daily activities.

    Jim Denevan is an amazing artist whose work is admired by all, but owned by none — that's because all of Jim's art is created on an unusual canvas(画布)— the soft sand. He sometimes spends days working on a piece, only to see it washed away by the sea or a storm and that is just the way he likes it.

    Denevan discovered his artistic talents about ten years ago, when he was wandering aimlessly on the beach with a stick. He ended up drawing a 12-foot-long fish. Since then, Jim has traveled over 1,800 miles while creating over 600 pieces of sand art.

    Over the years, his drawings have become bigger, but the tools he uses haven't changed — All he needs is a stick, a garden rake (耙子)and most importantly, his lively imagination!

    Just like any good artist, Jim is quite particular about the "quality" of his canvas, sometimes walking for miles, looking for perfect sand. His latest piece of work, which is also the world's largest freelance (自由职业的)drawing, was created in the desert sand of Nevada. It took Jim three trips, eight days and over 100 miles of walking to create this 3-mile work of art. It took the storm just one night to destroy it! However, Jim says he actually enjoys watching the waves or rain, wash his paintings away.

    Jim's art has become very popular over the years and was even the topic of a documentary named "Sandman" in 2015. Jim Denevan is not just about art in the sand — he is also an excellent chef and founder of an organization called "Outstanding in the Field", whose mottois to celebrate food at its source. Accordingly, group dining events are held outdoors on farms, with the diners being treated to a delicious meal. The events, which are held in different farms throughout America, are always sold out the minute the schedule is announced.