No one is sure how the ancient Egyptians built the pyramids near Cairo. But a new study suggests they used a little rock‘n'roll. Long-ago builders could have attached wooden pole s to the stones and rolled then across the sand, the scientists say.
“Technically, I think what they're proposing is possible,” physicist Daniel Bonn said.
People have long puzzled over how the Egyptians moved such huge rocks. And there's no obvious answer. On average, each of the two million big stones weighed about as much as a large pickup truck. The Egyptians somehow moved the stone blocks to the pyramid site from about one kilometer away.
The most popular view is that Egyptian workers slid the blocks along smooth paths. Many scientists suspect workers first would have put the blocks on sleds(滑板). Then they would have dragged them along paths. To make the work easier, workers may have lubricated the paths either with wet clay or with the fat from cattle. Bonn has now tested this idea by building small sleds and dragging heavy objects over sand.
Evidence from the sand supports this idea. Researchers found small amounts of fat, as well as a large amount of stone and the remains of paths.

However, physicist Joseph West thinks there might have been a simpler way , who led the new study . West said , “I was inspired while watching a television program showing how sleds might have helped with pyramid construction . I thought , ‘Why don't they just try rolling the things?'“A square could be turned into a rough sort of wheel by attaching wooden poles to its sides , he realized . That , he notes , should make a block of stone” a lot easier to roll than a square”.
So he tried it.
He and his students tied some poles to each of four sides of a 30-kilogram stone block. That action turned the block into somewhat a wheel. Then they placed the block on the ground.
They wrapped one end of a rope around the block and pulled. The researchers found they could easily roll the block along different kinds of paths. They calculated that rolling the block required about as much force as moving it along a slippery(滑的)path.
West hasn't tested his idea on larger blocks, but he thinks rolling has clear advantages over sliding. At least, workers wouldn't have needed to carry cattle fat or water to smooth the paths.

    It was a quiet village in which there was a military camp(军营). It was far from the towns and cities and there were some high mountains around. Of course it was a good place for training the new soldiers. But it was difficult for the young men to go outside. Mr. White, an officer of forty, was strict with them and he hardly let them leave the camp.

    Once Mr. White was ill in bed. He couldn't work and a young officer, Mr. Hunt, began to train the new soldiers instead of him. He knew the young men well and let nine soldiers go to the nearest town to have a holiday. But night fell and none came back to the camp. He was worried about it and stood at the gate. It was five to twelve when Mr. Hunt decided to go to the town and see what was happening with the young men. He started the car quickly and set off. At that moment the nine soldiers came back. It seemed they were all drunk. Of course they found the officer was angry.

    "I'm sorry, sir," said the first soldier. "I left the town on time. But something was wrong with my bus on my way here. I had to buy a horse and made it run fast. Bad luck! It died and I had to run back."

    And the other seven soldiers said they were late for the same reasons. It was the last soldier's turn. He said, "I'm sorry, sir. I got on a bus on time, but…"

    Having heard this, the officer became even angrier and stopped him at once. He called out, "If you say something was wrong with your bus, I'll punish you at once!"

    "No, no, sir," said the young man. "My bus was all right, but the dead horse were in its way!"

    Google's new camera, called Clips, is a small, smart device. It comes with a case that has a clip (夹子)，but it's not designed to be worn on your clothing. Most interestingly, it uses artificial intelligence to take photography out of your hands so it can capture moments on its own.

    This roughly 2-inch by 2-inch camera, with a three-hour battery life and Gorilla Glass for toughness, is intended for candid moments, like when a child does something cute that may happen too quickly for you to pull out your smartphone.

On board the Clips device, it uses machine learning algorithms (计算程序) to help capture scenes. Those algorithms include face recognition. “Once it learns that there's a face you see frequently, it'll try to get nice photos of those faces,” said Juston Payne, the device's product manager. And they also want it to recognize facial expressions, which involved “training it to know what happiness looks like”. The Google team also trained it to recognize what not to shoot — like when a child's hand is over the lens, or if it is tossed in a dark purse.

    The only way to see the images is by connecting the camera with your phone, as it has no screen for viewing or editing.

    Were people concerned it could seem strange? Yes, Payne admitted. But they said they addressed that by making it obvious what it is. A green light on the front signals that it is on. Besides, unlike a camera meant to monitor your home, it is not connected to the Internet.

    “This product is only possible because of the way that silicon has advanced” Payne said, noting that it was only in the past year or so that they could squeeze the technology down into a device this size. Going forward, we're likely to get more assistance from the artificial intelligence packed into our apps and gadgets.

Teaching Poetry

    No poem should ever be discussed or "analyzed", until it has been read aloud by someone, teacher or student. Better still, perhaps, is the practice of reading it twice, once at the beginning of the discussion and once at the end, so the sound of the poem is the last thing one hears of it.

    All discussions of poetry are, in fact, preparations for reading it aloud, and the reading of the poem is, finally, the most telling "interpretation" of it, suggesting tone, rhythm, and meaning all at once. Hearing a poet read the work in his or her own voice, on records or on film, is obviously a special reward. But even those aids to teaching can not replace the student and teacher reading it or, best of all, reciting it.

    I have come to think, in fact, that time spent reading a poem aloud is much more important than "analyzing" it, if there isn't time for both. I think one of our goals as teachers of English is to have students love poetry. Poetry is "a criticism of life", and "a heightening of life". It is "an approach to the truth of feeling", and it "can save your life". It also deserves a place in the teaching of language and literature more central than it presently occupies.

    I am not saying that every English teacher must teach poetry. Those who don't like it should not be forced to communicate this to anyone else. But those who do teach poetry must keep in mind a few things about its essential nature, about its sound as well as its sense, and they must make room in the classroom for hearing poetry as well as thinking about it.

    Have you ever pressed the pedestrian button at a crosswalk and wondered if it really worked? They're called "placebo(安慰剂）buttons"一buttons that mechanically sound and can be pushed, but provide no functionality.

    In New York City, only about 100 of the 1, 000 crosswalk buttons actually function. Crosswalk signals were generally installed before traffic jam had reached today's levels.

    But while their function was taken over by more advanced systems—such as automated lights or traffic sensors — the physical buttons were often kept, rather than being replaced at further expense. Other cities, such as Boston, Dallas and Seattle, have gone through a similar process, leaving them with their own placebo pedestrian buttons. In London, which has 6, 000 traffic signals, pressing the pedestrian button results in a reliable "Wait" light. But that doesn't necessarily mean that the "green man"— or "pedestrian stage" in traffic signal design profession — will appear any sooner.

    "We do have some crossings where the green light comes on automatically, but we still ask people to press the button because that enables accessible features,'' said Glynn Barton, director of network management at Transport for London.

    These features, such as blind tracks and hearable traffic signals, help people with visual disorder cross the road and only function when the button is pressed. As for the lights, a growing number of them are now combined and become a part of an electronic system that detects traffic and adjusts time frequency accordingly (giving priority to buses if they're running late, for example), which means that pressing the button has no effect.

    According to Langer, a Harvard psychologist, placebo buttons give us the illusion (错觉)of control — and something to do in situations where the alternative would be doing nothing. In the case of pedestrian crossings, they may even make us safer by forcing us to pay attention to our surroundings. "They serve a psychological purpose at the very least," she added.

    Prosocial behaviors are those intended to help other people. Behaviors that can be described as prosocial include feeling empathy(同感) and concern for others and behaving in ways to help or benefit other people.

    Prosocial behavior has long posed a challenge to social scientists seeking to understand why people engage in helping behaviors that are beneficial to others, but costly to the individual performing the action. Why would people do something that benefits someone else but offers no immediate benefit to the doer?

    Psychologists suggest that there are a number of reasons why people engage in prosocial behavior. In many cases, such behaviors are fostered during childhood and adolescence as adults encourage children to share, act kindly, and help others. Prosocial behaviors are often seen as being compelled by a number of factors including egoistic reasons (doing things to improve one's self­image), reciprocal benefits (doing something nice for someone so that they may one day return the favor), and more altruistic reasons (performing actions purely out of empathy for another individual).

    Characteristics of the situation can also have a powerful impact on whether or not people engage in prosocial actions. The bystander effect is one of the most notable examples of how the situation can impact helping behaviors. The bystander effect refers to the tendency for people to become less likely to assist a person in distress when there are a number of other people also present. For example, if you drop your purse and several items fall out on the ground, the likelihood that someone will stop and help you decreases if there are many other people present. This same sort of thing can happen in cases where someone is in serious danger, such as when someone is involved in a car accident. In some cases, witnesses might assume that since there are so many other present, someone else will have surely already called for help.

    Why do people help in some situations but not in others? Experts have discovered a number of different situational variables that contribute to (and sometimes interfere with) prosocial behaviors. First, the more people that are present decreases the amount of personal responsibility people feel in a situation. People also tend to look to others for how to respond in such situations, particularly if the event contains some level of ambiguity. Fear of being judged by other members of the group also plays a role. People sometimes fear leaping to assistance, only to discover that their help was unwanted or unwarranted. In order to avoid being judged by other bystanders, people simply take no action.

    Experts have suggested that some key things must happen in order for a person to take action.