Yosemite is a national park in California. It is very beautiful and big. The park includes more than 760,000 acres (英亩) in the California Mountains. Most of the park is wild (荒凉的).

    The part of Yosemite that everyone likes is Yosemite Valley. It is a small valley that is 7 miles long and less than 1 mile wide. It has tall rock walls and streams that flow down in waterfalls. More than two million visitors come to the valley each year.

    It's said that the number of visitors is more than the land can hold. The valley has 4,500 camping places. It has a hotel that can hold 4,000 families. This is still not enough to serve all of the visitors. The valley has grown so big that it has a lot of traffic.

    A worker says the park is trying to keep the beauty of the park and let everyone visit. Some areas have been rounded up (圈起来) to keep people away and planted with seeds to try to keep them beautiful.

    A former worker thinks Yosemite should get more money to take better care of the park. He would also like to teach people what the park service is trying to do.

    Some people are trying to save Yosemite Valley. A plan has been made to remove some buildings. There will be fewer cars allowed inside the park. More buses will help get people around.

    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 Yet the picture of the pandemic that showed up was always a week or two out of date.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.

    There's a world of difference between a horror movie and a comedy—the former scares you half to death while the latter leaves you rolling on the floor with laughter. But try watching them without the background music and you just might decide they're not so different after all. Music and movies have been closely connected since the beginning of the film industry—even before the voices of actors were recorded. In movies, music helps to provide a sense of time and place, convey ideas about the characters and, most importantly, draw emotions out of the audience.

    Studies have long shown that our heart rates and anxiety levels rise and fall depending on the speed of the music we hear. Using this knowledge, composers use sudden changes in film music speed to create fear among audiences. Slowing the speed of the music will have the opposite effect, bringing about a sense of peace or a dreamlike quality. The use of dissonant (不和谐的) tones and noises is another technique that heightens tension. Humans naturally become unnerved when we hear dissonant sounds because such noises are usually associated with danger, like those that animals make to warn against predators (捕食者).

    As crucial as it is, the best film music is subtle. All that audiences are supposed to feel is a heightened sense of emotion—they shouldn't realize what's causing it. Only when the music is taken out of the film should audiences understand its effects.

    In keeping with this principle, some filmmakers are even using what's called "infrasound" (次声波) to arouse fear. While we may not be able to hear it because its frequency is below the range of the human ear, infrasound has been proven to cause anxiety, tremble and even sorrow. For example, infrasound was used in the soundtrack of the 2007 horror movie Paranormal Activity, and audiences reposed extremely high fear levels despite the 1ack of action throughout the movie. "It doesn't affect everyone equally," said British science writer Philip Ball, author of The Music Instinct, but he predicted that "we will see more of it used in movies in the future".

    At first, Michael Surrell didn't see the black smoke or flames shooting from the windows of his neighbors' home. He and his wife had just parked around the corner from their own house in Allentown, Pennsylvania, when they got a call from one of his daughters, "The house next door is on fire!" He went to investigate. That's when he saw two women and a girl hysterical (歇斯底里的)on their porch.

    "The baby's in there!" one of the women cried. Though the fire department had been called, Surrell, then 64, instinctively ran inside. "The baby" was 8-year-old Tiara Roberts, the woman's granddaughter and a playmate of Surrell's three youngest kids, then 8, 10, and 12. The other two on the porch were Tiara's aunt and cousin.

Entering the burning house was like "running into a bucket of black paint," Surrell says. The thick smoke caused him to stumble blindly around, burned his eyes, and made it impossible to breathe. The conditions would have been hazardous for anyone, but for Surrell, who has chronic obstructive pulmonary disease (慢性阻塞性肺疾病), they were life-threatening. He was the last person who should have run into a burning building— he has lung disease. But that didn't stop him.

    After a few minutes in the smoke filled house, he retreated outside to catch his breath. "Where is Tiara?" he asked desperately." The second floor." her aunt shouted back.

    Surrell knew he couldn't hold his breath for long. So he uttered a little prayer, "Well, Lord, this is it. You gotta help me, because I'm not coming out without that little girl." Taking a deep breath, he went in a second time.

    The darkness was overwhelming. Yet because the house had a similar layout to his, he found the stairs and made it to the second floor. He turned to the right and was met by intense heat. He was already out of breath.

    "Baby girl, where are you?" His throat and lungs burned as if he'd inhaled fire instead of the smoke and soot in the air. Every blink stung his eyes. All he could hear was the crackling and popping of burning wood. ①.Still unable to see, Surrell fell to his knees on the hot wood floor. He crawled toward the sound, feeling around for any sign of the girl. An ominous thought crossed his mind: I'm probably gonna die up here.

    Finally he touched something. A shoe, then an ankle. He pulled Tiara toward him. ②Her body was limp and she wasn't breathing. He scooped her into his arms and stood. He felt the heat of the flames on his cheeks. Turning, he fought through the smoke and ran blindly into the blackness. The next thing he knew, he was at the front door, then outside. Surrell put Tiara down on the porch.

    ③. A voice told him, "You have to breathe for her." He started CPR -the first time he'd ever done so. The women stood behind him, praying silently. Soon a soot-filled cough came from Tiara's throat. Surrell gave five more breaths. She coughed again. Her eyes flickered. He gave one final breath. She opened her eyes and took a breath on her own.

    ④.Their eyes met. Surrell hugged her tight and said, "Uncle's got you.^" Soon after, his throat closed off.

    Surrell woke up in the hospital a couple of days later, having suffered severe burns to his windpipe and the upper portion of his lungs. He spent over a week in the hospital. Tiara was released from the hospital after a few days. The fire exacerbated Surrell's pulmonary condition, and he feels the effects even two years later. As a result, he takes extra medication that helps open his airways. "It's a small price to pay," he says. "I'd do it again in a heartbeat. Wouldn't give it a second thought."

    People think of cats as cute. But research published in a psychology journal calls them neurotic (神经质的) and unstable. Researchers from the University of Edinburgh in Scotland and the Bronx Zoo in New York compared the personalities of domestic house cats with those of four different types of wildcats.

    To better understand their personalities, the researchers rated a number of animals behaviors on what psychologists call the Big Five human personality traits (特征).

    Domestic house cats have similar personality structures to African lions. "It's what cats do pretty much on a daily basis, things like being anxious, being timid, being excitable, being aggressive toward humans, being aggressive toward each other, "said Max Wachtel, a Denver psychologist who didn't participate in the study. "All of those are characteristics you see in those cute little house cats, and you also see them in lions."

    If you ever thought your cat was anxious, insecure, tense, suspicious or aggressive toward you, you aren't making it up, he said. If they were bigger, they probably would consider killing you.

    But the news isn't all bad: Just like lions, house cats are also playful, excitable and impulsively funny. They just aren't very predictable. One moment cats will be enjoying bell scratches, and the next they will be biting you to make you stop.

    "It is good to understand the personality characteristics of our pets," Wachtel said "Different cats have different personalities, but as a species, there are a lot of commonalities."

    The researchers also studied personality traits of Scottish wildcats and some other animals “Across the five species we assessed, personality structure was strikingly similar and also seemed to be related to other studies' findings, such as in tigers, "the researchers wrote in their study in the November 2014 issue of the Journal of Comparative Psychology. But house cats were most like lions, potentially because they live in semi-social surroundings and lions are the most social of cats.

    “They're cute and furry, but we need to remember when we have cats as pets, we are inviting little predators into our house," Wachtel said. "Cats can be fantastic, sweet companions -until they turn on you.”

A rainy day can be a chance to recharge. While you relax on the sofa with a movie, the raindrops falling on your windows might one day provide the power for your TV. This is the idea behind an invention that harvests energy from water. 

The technology is based on the triboelectric (摩擦电的) effect. An engineer at the University of Hawaii, David Ma knew that it was possible to generate electricity by rubbing two things together. So, he thought, "Why don't we use water?"

A drop of water sliding across a surface coated with two different materials would generate enough friction(摩擦) to create an electrical charge. By placing metal wires that the drop of water touched as it moved, it should be possible to harvest electricity, he reasoned. 

It worked. In fact, the researchers lit up 15 LED bulbs with a single moving water drop. 

This is not the first time that scientists have got electricity from water-generated friction. Earlier experiments, though, harvested the charge produced in a surface by a sliding drop of water. There, the surface had acted as an electrode(电极). This is different. The energy of friction is being harvested from the water itself. 

"The technology could someday power phones, sensors or other small electronics," says Christopher Oshman, an engineer at the Colorado School of Mines. "This work is a step towards harvesting the energy of moving objects all around us, including ourselves, to power the electronic devices we use every day," he says. 

"Ma has shown that the technology can work in a lab," Oshman says. Next, the Colorado researcher would like to see it tried on a larger scale, such as on an umbrella.