I sit on the stoop (门廊) in front of my friend's house at the top of a steep hill. And now my friend is late, and I'm stuck here waiting.

    I see a man approaching.

    "Por favor. Call 911," the man says. "Finger. Cut." With his left hand, he is pressing the handkerchief around his right little finger.

    "No. Have. Phone," I say, as if English is also my second language.

    "Have phone," he says, and dips his chin toward his front pants pocket. There, I find a phone, and call 911.

    The operator answers, and I say "I'm with this guy, and he cut his finger."

    "Did he cut it off?"

    "Did you cut it off?"

    "Sí." He sighs.

    "Yes. He cut it off."

    "Where is it?" the operator asks.

    "Where is it?"

    "Upstairs," he says, pointing with his elbow to the house next door.

    "Go get it," she instructs me.

    I follow the man toward the house. Inside, I see a table saw(锯), and the blood spreading across the ceiling, but I don't see the finger. I lift up each foot and look underneath to be sure I've not stepped on it. I'm getting that jumpy, tight-shouldered feeling like when you've lost sight of a spider that was on your ceiling a moment ago.

    "Do you see it?" I ask him.

    He points at his own finger beside the table saw. I grab a paper towel, pinching it carefully, the way you might pick up a harmless but frightening insect.

    "We have secured the finger," I tell the operator.

    "Hang tight. The ambulance is on its way."

    We sit on the stoop waiting for the ambulance.

    "You're going to be OK," I say, putting my free hand on his sawdust-covered back.

    "Gracias," he says.

    "De nada. Esta no problemo," I reply in broken Spanish.

    It feels good to be able to comfort someone, anyone. For months now, the second my hands would go idle(闲散的), a familiar depression would climb on my back. I have been trying to put on a good face for my kid, but I feel as if I've been failing. Could I save myself? I wouldn't know how. But I am determined to save this man.

    Finally the ambulance arrives, picks him up, and they're off.

    Throughout the evening, I can't stop worrying about the man. I decide to call the hospital.

    "Hi! I helped a guy who cut off his finger, and I don't even know his name, but I'm wondering whether he came to your hospital."

    The nurse says, "His name is Jose Ramos, and he's waiting for surgery. Would you like to leave a message?"

    "No. I don't want to bother him. I just wanted to be sure he was OK."

    The next morning, I call the hospital again. This time, I'm put through to Jose's room. "How was the surgery?"

    "No surgery," he says. "No enough blood."

    "Oh, I'm sorry," I say.

    Later that day, I remember that old proverb about how if you save someone's life, you are responsible for them for the rest of their life, which never made sense to me before. Shouldn't the person who got saved owe a debt, and not the other way around? But today, I get it. It's a great honor to help someone in need.

    I start keeping a lookout for other people in need of assistance. I help push a stalled car out of the road. I aid a disoriented cyclist when her bike gets clipped by a car. I adopt a dog. Then one day, a month or two after the finger incident, I realize I have completely forgotten to be depressed. I've been so busy playing the role of local hero that I have ignored to drag my feet and stare into space and imagine the world without me.

    Now, more than a decade has passed since Jose's accident. Occasionally I search for "Jose" plus "Ramos" plus "finger." I wish I could see him again, to see how he's getting on. But more important, to thank him, because when he lost his finger, he saved my life.

    On a clear night, you can see a sky paced with stars. But you can't see planets orbiting any of these stars, even with the strongest Earth—based telescopes. Astronomers reported that they discovered seven Earth—sized planets orbiting a nearby star called TRAPPIST – 1 in February. They had to rely on indirect evidence to tell them that the planets are there. By doing some math, they figured out the number of planets and the distance of their orbits.

    TRAPPIST – 1 is a red dwarf （红矮星）, much smaller than our sun, but larger than Jupiter (木星). If the sun were the size of a basketball, TRAPPIST – 1would be the size of a gold ball. This star is one of our closest neighbors, just like the moon to the earth in space.

    When astronomers using Earth-based telescopes to study TRAPPIST – 1,they noticed that every once in a while, it became slightly dim（昏暗）. They decided that a planet must be passing in front of the star, blocking part of the light. This dimming would come and go as the planet orbited the star, passing alternately (交替地) behind and in front of the star regularly.

    By making careful observations, astronomers expected to get a rough idea of the planet's size from the pattern of dimming light. But the light level changed often and not at evenly spaced (均匀间隔的) times. The astronomers had to conclude they were looking at more than one planet! To get additional data, NASA's spritzer Space Telescope measured TRAPPIST –1's brightness nearly continuously for 20 days, catching 34 crossings of planets in front of the star. Sorting through the mess of data, the astronomers found that the innermost planet completes its orbit in 1.5 Earth days, while the outermost planet takes 20 days. Once you know how long it takes each planet to complete an orbit, you can work out how far it is from the star compared with the other planets.

    The TRAPPIST – 1 planets are not alone. So far, astronomers have found more than 3,400 planets that orbit other stars.

    A British-designed electronic newspaper which is made of plastic and no larger than a table mat(垫子) is to enter the market next year. The new newspaper was conceived(想出) by Cambridge University scientists. They came up with the idea of replacing silicon chips (硅片) with plastic ones. It is being developed by Plastic Logic, a company based in Dresden, Germany.

    "It looks just like a table mat, and is as light as a magazine. But you can download hundreds of newspapers at the touch of a button, and read them quite safely," the BBC reported on its website.

    The plastic paper is produced in a safe "clean room" at the Plastic Logic factory, which opened last month as the world's first plastic-electronics factory. Every part of the product, from the screen to the electronics, is made of plastic. And it is described by engineer Dean Baker as "top quality". Baker says the plastic newspaper could help solve the problem of waste material associated with traditional newspapers.

    "There's a huge amount of waste. We have paper distributed（分发）all over the country each day and then thrown into the bin. This doesn't need to happen any more. All of the copies could be made electronically and stored on a single ereader with the appearance of paper." he says.

    People can expect to see the plastic newspaper next year, the BBC says.

    Last summer, two nineteenth-century cottages were rescued from remote farm fields in Montana, to be moved to an Art Deco building in San Francisco. The houses were made of wood. These cottages once housed early settlers as they worked the dry Montana soil; now they hold Twitter engineers.

    The cottages could be an example of the industry' s odd love affair with "low technology," a concept associated with the natural world, and with old-school craftsmanship (手艺) that exists long before the Internet era. Low technology is not virtual (虚拟的) —so, to take advantage of it, Internet companies have had to get creative. The rescued wood cottages, fitted by hand in the late eighteen-hundreds, are an obvious example, but Twitter's designs lie on the extreme end. Other companies are using a broader interpretation (阐释) of low technology that focuses on nature.

    Amazon is building three glass spheres filled with trees, so that employees can "work and socialize in a more natural, park-like setting." At Google's office, an entire floor is carpeted in glass. Facebook's second Menlo Park campus will have a rooftop park with a walking trail.

    Olle Lundberg, the founder of Lundberg Design, has worked with many tech companies over the years. "We have lost the connection to the maker in our lives, and our tech engineers are the ones who feel impoverished (贫乏的) , because they're surrounded by the digital world," he says. "They're looking for a way to regain their individual identity, and we've found that introducing real crafts is one way to do that."

    This craft based theory is rooted in history, William Morris, the English artist and writer, turned back to pre-industrial arts in the eighteen-sixties, just after the Industrial Revolution. The Arts and Crafts movement defined itself against machines. "Without creative human occupation, people became disconnected from life," Morris said.

    Research has shown that natural environments can restore(恢复) our mental capacities. In Japan, patients are encouraged to "forest-bathe," taking walks through woods to lower their blood pressure.

    These health benefits apply to the workplace as well. Rachel Kaplvin, a professor of environmental psychology, has spent years researching the restorative effects of natural environment. Her research found that workers with access to nature at the office—even simple views of trees and flowers—felt their jobs were less stressful and more satisfying. If low-tech offices can potentially nourish the brains and improve the mental health of employees then, fine, bring on the cottages.

    Astronomers have taken the first ever image of a black hole, which is located in a distant galaxy (星系).The black hole is 500 million trillion km away and was photographed by a network of eight telescopes across the world. It was captured by the Event Horizon Telescope (EHT).

    The announcement was made in Washington, Brussels, Santiago, Shanghai, Taipei and Tokyo. Details have been published today in Astrophysical Journal Letters.

    Prof Heino Falckc, of Radboud University in the Netherlands, who suggested the experiment, told BBC News that the black hole was found in a galaxy called M87. "What we see is larger than the size of our entire Solar System," he said. "It has a mass 6.5 billion times that of the Sun. And it is one of the heaviest black holes that we think exists. It is an absolute monster, the heavyweight champion of black holes in the Universe."

    The image shows an intensely bright "ring of fire", as Prof Falckc describes it, surrounding a perfectly circular dark hole. The bright halo is caused by very heated gas falling into the hole. The light is brighter than all the billions of other stars in the galaxy combined - which is why it can be seen at such distance from Earth. The edge of the dark circle at the center is the point at which the gas enters the black hole, which is an object that has such a large gravitational pull (万有引 力）,not even light can escape.

    "It is remarkable that the image we observe is so similar to that which we get from our theoretical calculations. So far, it looks like Einstein is correct once again." said Dr Ziri Younsi, of University College London -who is part of the EHT cooperation.

    Chinese scientists were involved in the observation through a telescope in Hawaii. They were also highly involved in follow-up data processing and theoretical analysis, said Shen Zhiqiang, head of the Chinese Academy of Sciences' Shanhai Astronomical Observatory and a member of the EHT international team.

    Shanghai and Taipei were selected as two of the cities to hold news conferences, together with Washington, Brussels, Santiago and Tokyo, a recognition of China's contribution.

    "In the fields of astronomy, radio astronomy, and space astrophysics, China has made a significant contribution to this global project," Falcke said.

Metro Pocket Guide

    Metrorail (地铁)

    Each passenger needs a farecard to enter and go out. Up to two children under age five may travel free with a paying customer.

Farecard machines are in every station. Bring small bills because there are no change machines in the stations and farecard machines only provide up to $5 in change.

    Get one ticket of unlimited Metrorall rides with a One Day Pass .Buy it from a farecard machine in Metro stations .Use it after 9:30 a,m. until closing on weekdays , and all day on weekends and holidays .

Hours of service

    Open 5am Mon-Fri             7a.m Sat-Sun

    Close midnight Sun-Thurs.          3a.m. Sat-Sun

    Last train times vary .To avoid missing the last train, please check the last train time posted in the station.

    Train times Posted in stations

    Metrobus

    When paying with exact charge, the fare is $1.35.When paying with a SmatTrip card, the fare is 1.25.

    Fares for the senior/ disabled customers

    Senior citizens 65 and older and disabled customers may ride for half the regular fare .On Metrorail and Metrobus , use a senior/disabled farecard or Smar/Trip Ⓡ card .For more information about buying senior, disabled farecards, farecard or SmarTrip cards and passes , please visit MetroOpensDoors .com or call 202-637-7000and 202-637-8000.

    Senior citizens and disabled customers can get free guide on how to use proper Metrobus and Metrorall services by calling 202-962-1100.

Travel tips (提示)

    Avoid riding during weekday rush periods –before 9:30 a.m. and between 4and 6p.m.

    If you lose something on a bus or train or in a station, please call Lost &Found at 202-962-1195, Avoid riding during weekday rush periods –before 9:30 a.m. and between 4and 6p.m.

    If you lose something on a bus or train or in a station, please call Lost &Found at 202-962-1195.