When was the last time someone unexpectedly did something nice for you? Not someone you knew, but a total stranger? It's happened to me a few times, but two instances really stand out.

    A few years ago, I was dining in a restaurant with a friend who kept talking about himself, completely not aware of the fact that I was sitting there in misery. It wasn't my friend's talks that made me suffer. I was recovering from a broken heart, and just sitting down to dinner reminded me of my last relationship. I could have burst into tears right there at the table.

    When we picked up the check, the waitress said, ―Your meal was already paid for.  My friend and I didn't have a clue how it happened. Then I remembered a man coming in out of the corner of my eye. He was dressed in mostly white, sat down at the bar, had a beer, and stayed for maybe ten minutes. The waitress said, ―Yes, the gentleman in white paid for you.  It felt like an angel was saying ―I see you, honey. It's going to be okay.

    Just last year, I was running a half-marathon. With just 1 mile to go, I was out of gas. Runners call it ―hitting the wall . I thought I couldn't move another inch. Out of nowhere, a stranger came up to me and said, ―What's your name, sweetie? Jennifer? Okay, Jennifer, let's go! Come on! It's just around the corner! You can do it!  And he ran with me until I picked up my pace. I found him at the finish line to thank him for the encouragement only to learn he wasn't even supposed to be in the race that day.

    I still shake my head when I think of these momentary angels that came to me at my point of need.

    Do you have any experiences like these?

    One day, I was in class, feeling fine, when all of a sudden my heart started racing. I broke out in a sweat, feeling hot and cold all over. My chest hurt, I was dizzy, and I felt like I couldn't breathe. Everything went blurry around the edges. Sure I was about to faint, I jerked up from my desk and ran from the room, terrified. I didn't care what the teacher thought, or that the eyes of the entire class were on me. I just had to get out of there.

    I ran to the nearest water fountain and drank some water. For several minutes, I just stood there holding on to the fountain. What was happening? Was I having a heart attack? Slowly, the lightheadedness went away. My heart stopped racing, and every other symptom faded too. I still had no idea what had happened but I was so glad it was over.

    Still I was really worried. I'd never felt that bad in my life. What was wrong with me? What if it came back?

    And then, an hour later, it did the pounding heart, the dizziness, the feeling that I was dying. Once again, I couldn't breathe. And this time, there was also pain throughout my entire upper body. I burst into tears and ran for the hallway again, actually afraid for my life. My teacher ran after me asking what was wrong. Panicking, I managed to choke out, "I need an ambulance: Please." I was sure I was dying.

    To my surprise, though, my teacher didn't grab her phone for help. Instead, she put her hand on my arm and told me to slow down. "Breathe, "she said." you're going to be okay. You just need to calm down. "

    I felt like I was going crazy. Here I was totally losing it, and she was acting like nothing was wrong! She kept on trying to calm me down, but I wasn't ready to listen. I was sure she didn't understand how I felt. How could she? How could anyone? Finally, my teacher explained that she was pretty sure I was having a panic attack. (They are also called anxiety attacks.) She knew, she said, because the same thing had happened to her when she was my age. She told me how she'd felt, and it was almost exactly how I was feeling now. She also explained that panic attacks are caused by anxiety (basically, excessive worry and fear that is part of your everyday life).

    I was shocked. I had no idea that there was even a name for what I was feeling let alone that it happened to other people, too! When I realized that she really did understand, I felt so relieved.

    My teacher talked to my parents, and they found me a counselor to help me deal with my anxiety. I'd been going through a tough time that year. My best friend had moved to a new school, and I wasn't sure how to fit in with the girls in my class. I'd never told anyone, though--I just kept it to myself. My counselor helped me understand that not dealing with my feelings can lead to panic attacks, and that I need to talk to someone when my life is stressful.

    Now when I start feeling overwhelmed or sad, I talk to my parents or friends and my counselor about whatever is bothering me, and they all help me sort things out. This way, I' m dealing with my anxiety and stress before it gets out of control.

    My counselor has also taught me some relaxation techniques and strategies that help me calm my body down at the first sign of a panic attack. I've learned to take deep breaths and relax my muscles. Or I'll focus on something else, or just tell myself I'm going to be okay. If one thing doesn't work, I'll try another one.

    It turns out that about one in every ten people has some kind of an anxiety disorder! Knowing that it's common and that life is stressful for a lot of girls of my age has helped me realize that I don't have to be ashamed or embarrassed about it.

    By sharing my story, I want other girls of my age to know that you're not as alone as you feel, and that talking about it really does help.

Rich as a King

    William 1, who conquered England some 930 years ago, had wealth, power and an army. Yet although William was very rich by the standard of his time, he had nothing like a flush toilet (抽水马桶), paper towels, or riding lawn mower (除草机). How did he get by?

    History books are filled with wealthy people who were poor compared to me. I have storm windows, Croesus did not. Entire nations trembled before Alexander the Great, but he couldn't buy cat food. Czar Nicholas lacked an electric saw.

    Given how much better off I am than so many famous dead people, you'd think I'd be content. The trouble is that, like most people, I compare my wealth with that of living person: neighbors, school classmates, famous TV people. The greed I feel toward my friend Howard's new kitchen is not reduced by the fact that no kings ever had a refrigerator with glass doors,

    There is really no rising or falling standard of living. Over the centuries people simply find different things to feel sad about. You'd think that simply not having disease would put us in a good mood, but no we want a hot bath too.

    Of course, one way to achieve happiness would be to realize that even by today's standards the things I own are pretty nice. My house is smaller than the houses of many investment bankers, but even so it has a lot more rooms than my wife and I can keep clean.

    Besides, to people looking back at our era from a century or two in the future, these bankers' fancy counter tops and my awn worn Formica will seem equally shabby, I can't keep up with my neighbors right now. But just wait.

    Photos of the moon are beautiful if taken well, but it can be very hard to get a picture of the moon that doesn't look blurry! In order to take a perfect picture of the moon, apart from a high­quality camera, the associated equipment and the skills to set up your camera, you also need to pick a proper time and a good place.

    Choose your favorite moon phase. The moon can be photographed in any phase except the new moon, which is not visible to Earth. The first quarter, half, and third quarter phases provide high contrast that allows you to see the craters(坑) in greater detail, while the full moon is a dramatic choice for a skyscraper. What phase you choose is up to your personal preference, but it's best to have a phase chosen before going out to photograph the moon.

    Learn when the moon rises and sets. When the moon sets or rises, it is closer to the horizon, making it appear larger and closer. This makes it much easier to photograph! Check an almanac(年历) or a weather app for moon rising and setting times in your area.

    Pick a clear night. Clouds, fog, and air pollution will blur your photographs. Check a weather app or watch the weather forecast before leaving for your session and while photographing. A clear night with low smog content and no rain is best for moon photography.

    Choose a location away from direct light sources. The moon appears bright because it reflects the light of the sun, and additional light from streetlights, homes, and cars can make the moon appear duller and blurrier in pictures. It is fine if there is light in the distance, but be sure that you are not photographing close to another light source.

    In 2009 a new flu virus was discovered. Combining elements of the viruses that cause bird flu and swine flu, this new virus, named H1N1, spread quickly. Within weeks, public health agencies around the world feared a terrible pandemic (流行病) was under way. Some commentators warned of an outbreak on the scale of the 1918 Spanish flu. Worse, no vaccine(疫苗) was readily available. The only hope public health authorities had was to slow its spread. But to do that, they needed to know where it already was.

    In the United States, the Centers for Disease Control and Prevention (CDC) required that doctors inform them of new flu cases. Yet the picture of the pandemic that showed up was always a week or two out of date. People might feel sick for days but wait before consulting a doctor. Relaying the information back to the central organizations took time, and the CDC only figured out the numbers once a week. With a rapidly spreading disease, a two-week lag is an eternity. This delay completely blinded public health agencies at the most urgent moments.

    Few weeks before the H1N1 virus made headlines, engineers at the Internet giant Google published a paper in Nature. It got experts' attention but was overlooked. The authors explained how Google could "predict" the spread of the winter flu, not just nationally, but down to specific regions and even states. Since Google receives more than three billion search queries every day and saves them all, it had plenty of data to work with.

    Google took the 50 million most common search terms that Americans type and compared the list with CDC data on the spread of seasonal flu between 2003 and 2008. The idea was to identify areas affected by the flu virus by what people searched for on the Internet. Others had tried to do this with Internet search terms, but no one else had as much data-processing power, as Google.

    While the Googles guessed that the searches might be aimed at getting flu information—typing phrases like "medicine for cough and fever"—that wasn't the point: they didn't know, and they designed a system that didn't care. All their system did was look for correlations(相关性) between the frequency of certain search queries and the spread of the flu over time and space. In total, they processed 450 million different mathematical models in order to test the search terms, comparing their predictions against actual flu cases from the CDC in 2007 and 2008. And their software found a combination of 45 search terms that had a strong correlation between their prediction and the official figures nationwide. Like the CDC, they could tell where the flu had spread, but unlike the CDC they could tell it in near real time, not a week or two after the fact.

    Thus, when the H1N1 crisis struck in 2009, Google's system proved to be a more useful and timely indicator than government statistics with their natural reporting lags. Public health officials were armed with valuable information.

    Strikingly, Google's method is built on "big data"—the ability of society to handle information in new ways to produce useful insights or goods and services of significant value. However,   ▲  . For example, in 2012 it identified a sudden rise in flu cases, but overstated the amount, perhaps because of too much media attention about the flu. Yet what is clear is that the next time a pandemic comes around, the world will have a better tool to predict and thus prevent its spread.

    The San Francisco Giants added a special pitcher(投球手)for the day. It was small—yet fierce—Hailey Dawson, who has a 3D-printed hand.

    The energetic 8-year-old from Nevada was invited to throw out the first pitch at the Giants game on Sunday. Dawson was born with Poland syndrome(综合症), a disorder in which affected individuals are born with missing or underdeveloped muscles on one side of the body. It affected her hand.

    With a traditional prosthetic(假肢)potentially costing thousands of dollars, Hailey's mom, Yong Dawson turned to the University of Nevada, Las Vegas for help. She emailed UNLV engineering, and they accepted the challenge. Brendan O'Toole, chairman of the mechanical engineering department, said he and his team had got a lot of requests, "but this one was different." They got to work using a 3D-printer.Several prototypes(原型)and fittings later, Dawson got her first hand about four years ago.

    Hailey's mother said the hand had given her daughter a wonderful lift. "When she puts this robotic hand on, it changes her personality and confidence level," Yong Dawson told CBS San Francisco. "I love seeing that. I just wanted her to have an even playing field."

    When she arrived at AT&T Park on Sunday, Hailey got to hang out with players in the shelter at the side of the sports field. They even let her try on their World Series rings.

    Using her 3D-printed hand, Dawson threw out the perfect first pitch. Then with a wave and a smile, she headed into the stands to cheer on her newfound friends on the Giants.