Gravity signals that race through the ground at the speed of light could help seismologists(地震学家) get a better handle on the size of large, destructive quakes soon after they hit，a study suggests. The tiny changes in Earth's gravitational field, created when the ground shifts, arrive at earthquake monitoring stations well before earthquake waves.

    “The good thing we can do with these signals is have quick information on the magnitude (震级) of the quake,” says Martin Vaillée, a seismologist at the Paris Institute of Earth Physics.

    Earthquake equipment in China and South Korea picked up gravity signals immediately after the magnitude-9. 1 Tohoku earthquake that destroyed parts of Japan in 2011. The signals appear as tiny accelerations on earthquake-recording equipment, more than a minute before the seismic waves show up.

    “We can look before the earthquake waves arrive,” says Vallée. “If we see nothing, we can say that the quake that made these was maybe large, but not huge. If we see the signals, it means we really have a very big quake. ”

    Had seismologists been monitoring for gravity changes, they might have realized sooner just how big the Tohoku earthquake was. A small increase in an earthquake's magnitude means a large change in the energy released by the quake-and the destruction expected. That information is important for emergency responders as they decide what resources to arrange.

    It'll be a major contribution if gravitational waves can beat down the time needed to know that a big earthquake is big. But much work remains before gravity signals can be considered a reliable tool in the vital minutes after a big quake. A few extra minutes of warning can save lives, particularly in coastal areas where people can flee ahead of an incoming tsunami.

    Now many young people are traveling around the world on their own，not because they have no one to travel with，but because they prefer to go alone.

Kristina Wegscheider from California first traveled alone when she was at college and believes that it is something everyone should do at least once in their life. “It opens up your mind to new things and pushes you out of your comfort zone.” Wegscheider has visited 46 countries covering all seven continents.

    In foreign countries，with no one to help you read a map，look after you if you get ill，or lend you money if your wallet is stolen，it is challenging. This is what drives young people to travel alone. It is seen as character building and a chance to prove that they can make it on their own.

    Chris Richardson decided to leave his sales job in Australia to go traveling last year. He set up a website，The Aussie Nomad，to document his adventures. He says he wished he had traveled alone earlier. “The people you meet，the places you visit，or the things you do，everything is up to you and it forces you to grow as a person，” said the 30-year-old man.

    Richardson describes traveling alone like "a shot in the arm"，which "makes you a more confident person that is ready to deal with anything". He said，"The feeling of having overcome something on my own is a major part of what drives me each day when I'm dealing with a difficult task. I walk around with my head up because I know deep down inside that nothing is impossible if you try.”

    The great 19th century explorer John Muir once said，"Only by going alone in silence can one truly get into the heart of the wilderness."

    Welcome to Adventureland!

    Everyone loves Adventureland! The Parks and Exhibitions were built for you to explore, enjoy, and admire their wonders. Every visit will be an unforgettable experience. You will go away enriched, longing to come back. What are you going to do this time?

    The Travel Pavilion

    Explore places you have never been to before, and experience different ways of life. Visit the Amazon jungle village, the Turkish market, the Tai floating market, the Berber mountain house and others. Talk to the people there who will tell you about their lives, and things they make. You can try making a carpet, making nets, fishing…

    The Future Tower

    This exhibition shows how progress will touch our lives. It allows us to look into the future and explore the cities of the next century and the way we'll be living then. Spend some time in our space station and climb into our simulator (模拟装置) for the Journey to Mars!

    The Nature Park

    This is not really one park but several. In the Safari Park you can drive among African animals in one of our Range Cruisers: see lions, giraffes, elephants in the wild. Move on to the Ocean Park to watch the dolphins and whales. And then there is still the Aviary to see…

    The Pyramid

    This is the center of Adventureland. Run out of film, need some postcards and stamps? For all these things and many more, visit our underground shopping center. Come here for information and ideas too.

    I'm a speaker and give hundreds of speeches every year. I spoke about appreciation (感激) last month and I used this quote by Albert Schweitzer "Sometimes our light goes out but is blown again into flame by meeting with another human being. Each of us should express the deepest thanks to those who have relighted this inner (内心的) light."

    I asked my audiences to shut their eyes and think about someone who, at some time in their lives, has relighted their inner light. Then I left the room in silence for several minutes. It was always a meaningful experience as they remembered the joy they felt from another person.

    One day, a gentleman came up to talk with me and thanked me for creating a new awareness (意识) in him. He said he thought of his eighth-grade history teacher because she was everyone's favorite teacher and had really made a difference in all of their lives. Several days later, the gentleman found his history teacher and he wrote to her. The following week he received this letter:

    Dear John,

    You will never know how much your letter meant to me. I am 83 years old, and I am living all alone in one room. My friends are all gone. My family's gone. I taught 50 years and yours is the first "thank you" letter I have ever gotten from a student. Sometimes I wonder what I did with my life. I will read and reread your letter until the day I die.

    The gentleman was sad, "She is always the one we talk about when we have a get-together. She is everyone's favorite teacher—we love her! But no one had ever told her until she received my letter…"

    City: Hangzhou

    Launched: 2008

    Size: 2,965 stations/ 69,750 bikes

    Price: $32.61 deposit（押金）+ time charge

    While taking a look at this city, you may see the best bike sharing in the world. As the second on the planet by size, the Hangzhou Public Bicycle System is one of the most common and useful shares, largely because it's combined with public transportation: a single card can be used in subway, bus, taxi and bike sharing. Residents and tourists can put down a deposit of 200 Chinese Yuan （about $33）and ride for an hour for free in this scenic city. Each additional hour costs only $0.15. It was also the first new﹣generation bike﹣sharing system in China. By 2020 it's projected to have 175,000 bikes.

    City: Barcelona

    Launched: 2007

    Size: 420 stations/ 6,000 bikes

    Price: $61.93 per year

    Barcelona's Bicycling Program developed Spain's bike﹣sharing business in a big way. This program took off like wildfire on wheels, and because four times bigger in one year. It inspired different copycat programs all over the country. Today, Spain has 132 bike﹣sharing systems. The program is one of the world's most respected and popular shares. But it is only open to residents and tourists are not allowed to use it.

    City: Paris

    Launched: 2007

    Size: 1,751 stations/ 23,900 bikes

    Price: $38.52 per year/ $2.26 per day

    Paris's bike﹣sharing is the star of the world. Launched in 2007, it is the world's largest outside of China. Cheap by American standards, you can ride around Paris on a €1.7 day pass— the first half hour of each trip is free. Because this system covers the city with an average of 50 stations per square mile, it's a favourite with both locals and tourists.

    Are you interested in hi-tech products? Here are some that you might find at the market now.

    CX-1

    Tired of dragging your bag through busy airports? Then you might want to consider CX-1. The smart suitcase uses facial recognizing software to follow its owner as he/she is checking in or heading to the gate. Though CX-1 can only move at a speed of up to seven miles per hour, a tiny tool enables owners to keep track of the suitcase's location. Happily, it has been sold on the market.

    Aibo

    Sony's latest version of the Aibo robotic dog is almost as fun as the real thing — but much less work. The pet dog can recognize its owner, obey several commands, and even recall the behavior that pleases its master the most. Aibo can also learn new tricks, take photographs, and over time, develop its own unique personality.

    Forpheus

    Forpheus, an "athletic" robot developed by Japanese technology company Omron. It teaches users how to play ping-pong. The 10-feet-tall machine uses a camera and artificial intelligence to track the ball's speed and can predict the ball's direction correctly. The smart Forpheus can also quickly test its player's abilities and adjust the playing level, making the game fun.

    Black Box VR

    Though many people determine to go to the gym once a week, few reach their goal. Black Box VR wants to change that by turning hard exercise into fun video games. Using it, gym users will find themselves fighting enemies, including big creatures — all while getting exercise.