Earlier this month, two rock climbers achieved what many thought impossible: They climbed up the 3,000-foot-high Dawn Wall in Yosemite NationalPark without specialized equipment. Climbing without this equipment iscalled“free-climbing.”Until now, no one had free-climbed to the top of the rockface, which is a part of the mountain EI Capitan.

    El Capitan, which means“the captain”or“the chief”in Spanish, has always presented a challenge to climbers. But the Dawn Wall, on the mountain's southeast face, is a particularly difficult route to the summit (顶峰). It is a rock formation that is both steep and relatively smooth. This makes free-climbing the rock face seem almost impossible.

    About seven years ago, professional climber Tommy Caldwell spotted a possible route up the wall. It took years of planning and preparation, but this month, Caldwell, 36, and his friend Kevin Jorgeson, 30, finally make the climb.

    Free climbers do use ropes and other basic safety equipment to catch them if they fall — and Caldwell and Jorgeson fell often. Before starting their climb, they broke down their route into 32 sections. Each section was based on a rope length called a“pitch.”The rope was secured into the rock faceto catch the climbers if they fell.

    Caldwell and Jorgeson's goal was to climb the DawnWall without returning to the ground. If they fell, they had to start that pitch all over again. The two men started climbing on December 27. They slept in hanging tents, and a team of friends brought them food each day.

    The men had spent years rehearsing (排练) them ovements it would take to get through each pitch. They made it through the fist half of the climb relatively easily. But halfway up, Jorgeson ran into trouble. In one difficult spot, he fell each time he attempted to climb. After10 days of trying, Jorgeson finally made it to the next pitch.

    Getting through that troublesome pitch gave both climbers renewed energy. They finished the rest of the climb five days later, on January 14.

    Why Do Dogs Watch--and React to--TV?

    Domestic dogs can perceive images on television similarly to the way we do, and they are intelligent enough to recognize onscreen images of animals as they would in real life-even animals they've never seen before-and to recognize TV dog sounds, like barking.

    A 2013 study published in the journal Animal Cognition showed that dogs could identify images of other dogs among pictures of humans and other animals, using their visual sense alone.

    However, there are some differences between ourselves and man's best friend-for one, dogs' eyes register images more quickly than do ours. So older television sets, which show fewer frames(帧数) per second than modern televisions, would appear to a dog to be flickering(忽隐忽现的) like a "1920s movie," said Nicholas Dodman, a veterinary behaviorist(动物行为学家) at Tufts University, in Massachusetts.

    Dogs also have dichromatic vision, which means they see a range of two primary colors, yellow and blue. Human vision is trichromatic, so we see the full range of colors, according to Binghamton University's Ask a Scientist web page.

DogTV, an HDTV cable channel designed for dogs, interests canines(犬) because HDTV has a much higher number of frames per second and is specially colored to accommodate dogs' dichromatic vision, said Dodman, who is the channel's chief scientist.

    DogTV has modes for relaxation, which shows images like dogs recreate themselves in a grassy field; stimulation, which depicts scenes like dogs surfing in southern California; and exposure which shows things like a dog reacting to a ringing doorbell and obeying commands to adapt to such situations at home.

    I had an experience some years ago, which taught me something about the ways in which people make a bad situation worse by blaming themselves. One January, I had to hold two funerals on successive days for two elderly women in my community. Both had died “full of years”, as the Bible would say. Their homes happened to be near each other, so I paid condolence(吊唁) calls on the two families on the same afternoon.

    At the first home, the son of the deceased(已故的)woman said to me, “If only I had sent my mother to Florida and gotten her out of this cold and snow, she would be alive today. It's my fault that she died.” At the second home, the son of the other deceased woman said, “If only I hadn't insisted on my mother's going to Florida, she would be alive today. That long airplane ride, the sudden change of climate, was more than she could take. It's my fault that she's dead.”

    You see that any time there is a death, the survivors will feel guilty. Because the course of action they took turned out bad, they believe that the opposite course would have turned out better. After all, how could it have turned out any worse?

    There seem to be two elements involved in our willingness to feel guilty. The first is our pressing need to believe that the world makes sense, that there is a cause for every effect and a reason for everything that happens that leads us to find patterns and connections both where they really exist and where they exist only in our minds. The second element is the view that we are the cause of what happens, especially the bad things that happen. It seems to be a short step from believing that every event has a cause to believe that every disaster is our fault. The roots of this feeling may lie in our childhood.

    A baby comes to think that the world exists to meet his needs, and that he makes everything happen in it. He wakes up in the morning and summons the rest of the world to its tasks. He cries, and someone comes to attend to him. When he is hungry, people feed him, and when he is wet, people change him. Very often, we do not completely outgrow that childish view that our wishes cause things to happen.

Both humans and animals have enemies. It is easy for us to know the difference between our friends and our enemies. But can other animals do the same? Elephants can! They can use their sense of vision and smell to tell the difference between people who mean a threat and those who do not. In Kenya, researchers find that elephants react differently to clothing worn by men of the Maasai and Kamba ethnic groups. Young Maasai men hunt animals and thus mean a threat to elephants; Kamba men are mainly farmers and are not a danger to elephants.

In an experiment conducted by animal scientists, elephants were first presented with clean clothing or clothing that had been worn for five days by either a Maasai or a Kamba man. When the elephants noticed the smell of clothing worn by a Maasai man, they moved away from the smell faster and took longer to relax than when they noticed the smells of either clean clothing or clothing worn by a Kamba man.

Clothing color also plays a role. In the same study, when the elephants saw red clothing not worn before, they reacted angrily, as red is typically worn by Maasai men. Rather than running away as they did with the smell, the elephants acted angrily toward the red clothing.

The researchers believe that the elephants' emotional reactions are due to their different senses of smell and sight. Smelling a possible danger means that a threat is nearby and the best thing to do is run away and hide. Seeing a potential threat without its smell means that risk is low. Therefore, instead of showing fear and running away, the elephants express their anger and become aggressive.

    Have you ever thought of quitting your job when you feel exhausted? Maybe most of you would say "yes". After a particularly busy period at work, I decided to get away from it all by going on a hike in the mountains in southern France.

    Before I left, I read an interesting story in a magazine. It read, "Once, while I was riding on a crowded bus, the man sitting next to me threw his cell phone out of the window when his phone rang. I was surprised. He looked at me, shrugged (耸耸肩) and looked away. I had no idea whether it was his or stolen or whether he even knew what a cell phone was or not, but he clearly wanted to be free of it, because it clearly troubled him."

    Billions of people across the world use cell phones. Though cell phones are a wonderful way for communication, they often do the exact opposite. Using cell phones can increase stress within families and friends.

    So when I recently returned home, I got rid of my cell phone. Now I go outside without taking my phone with me. I've noticed things in my neighborhood I never noticed before, such as gardens. I've met new people, started conversations with neighbors I didn't speak to before and talked with some of my friends face to face instead of chatting over the phone.

    Instead of keeping me off from the world, stopping using my cell phone has helped me get even closer to my family and friends.