Often a nickname is a shortened form of a person's name, and it can also be a descriptive name for a place or a thing. Many American cities have nicknames. These can help build up an identity, spread pride among citizens and build their unity. Nicknames can also be funny.

    Los Angeles, California is the second largest city in population, after New York City. Los Angeles has several nicknames. One is simply the city's initials, L.A. It is also called the City of Angels because Los Angeles means "the angels" in Spanish.

    Los Angeles often has warm, sunny weather. So another nickname is City of Flowers and Sunshine. New York is called The Big Apple. So Los Angeles is sometimes called The Big Orange because of the fruit that grows in that city's warm climate.

    The American movie and television industries are based in Los Angeles. So it is not surprising that it is called The Entertainment Capital of the World. Many films are made in the area of Los Angeles called Hollywood. Millions of people visit the area. No trip to Los Angeles is perfect without seeing the word "Hollywood" spelled out in huge letters on a hillside.

    Many movie stars live in Los Angeles. The city is sometimes called Tinseltown. This nickname comes from the shiny, bright and often unreal nature of Hollywood and the movie industry.

    Another nickname for Los Angeles is La-La Land, using the first letters of Los and Angeles. This means a place that is fun and not serious, and maybe even out of touch with reality.

    A good place for watching unusual-looking people is Venice, an area on the west side of Los Angeles. A system of waterways designed after the Italian city of Venice has been built there. Many people love Los Angeles for its warm sunny weather, beautiful mountains and beaches, and movie stars. That includes Randy Newman, who sings about his hometown.

    On the whole, Los Angeles is growing attractive just for its rich nicknames.

    If you want to learn anything at school, you need to listen to your teachers. Unfortunately, millions of kids can't hear what their teachers are saying. And it's not because these students are goofing off. Often, it's the room's fault. Building architecture and building design can create echo(回声)-filled classrooms that make hearing difficult.

    Children with hearing impairments（损伤）suffer most from noisy classrooms. They sometimes can't hear questions that other students ask in class. Compared with kids with healthy hearing, they have a harder time picking up new vocabulary words by hearing them in talking.

    Even kids with normal hearing have a harder time in the classroom when there's too much noise. Younger children in particular have trouble separating important sounds – like a teacher's voice – from background noise. Kids with learning disabilities and speech impediments（障碍）and kids for whom English is a second language also have a harder time learning in noisy situations.

    In recent years, scientists who study sound have been asking schools to reduce background noise, which may include loud air-conditioners and pipes. They're also targeting outdoor noises, such as highway traffic. Noise reduction is a big deal. Why? Because quieter classrooms might make you smarter by letting you hear your lessons better.

    “It's so obvious that we should have quiet rooms that allow for access to the lesson,” says Dan Ostergren, a hearing scientist. “Sometimes it surprises me that we spend so much time discussing this topic. I just want to go. Why is this hard for anyone to grasp?”

    Many people wrongly think that cities don't have farms and fruits and vegetables are only grown in the country. Believe it or not, there are more urban farms popping up in cities all over the world.

    Alexandra Sullivan, a food systems researcher in New York, studies urban agriculture. Urban agriculture is another name for farming and gardening in a city environment. Ms. Sullivan studies everything from tiny gardens in empty lots between buildings to bigger fields that have been planted and grown. According to Ms. Sullivan, “Urban agriculture has existed since cities have, across the world.”

    The number of humans living in urban areas, or cities, is increasing. The amount of people who wanted to garden in urban areas is also rising. Ms. Sullivan says, “In small gardens, on rooftops and indoors, city residents grow fruits, vegetables, grains, and herbs, and raise animals to produce milk, eggs, honey, and meat. City residents use these foods as supplements to food produced by rural agriculture.” Even though some people who live in urban areas grow crops, urban residents still need to rely on food grown in rural areas. This is because a city doesn't have enough space to grow enough food for everyone living in it.

    In New York City, urban farmers have come up with many different ways to grow their own produce, even though there isn't a lot of room. For example, Brooklyn Grange is a farming operation that has two rooftop vegetable farms in New York City. All together, the farms are made up of 2.5 acres of rooftop space. This makes Brooklyn Grange one of the largest rooftop farming operations in the world.

    Brooklyn Grange grows all kinds of things. The farming company sells its vegetables to local residents and restaurants. And because the farms are on rooftops, they are specially adapted to their urban location. They use available space that is not needed for anything else. As more urban farmers find ways to grow food in cities, urban residents will be better able to get fresher materials for their meals.

    Pigeons may only have a brain the size of a thimble (顶针), but it appears that pigeons can categorize and name objects in the same way human children learn new words.

    A new study from the University of Iowa has shown that the birds are capable of learning to categorize 128 different photographs into 16 basic categories.

    Scientists taught three pigeons to sort out different kinds of dogs or types of shoes, for example by using a particular symbol in exchange for a reward. When they were shown black and white pictures of previously unseen dogs or shoes, the birds were able to correctly match these with the corresponding symbols.

    The scientists behind the project say this is a similar approach taken by young children when they are first learning words for objects. However, the researchers said it took their birds around 40 days to perfect the task of learning just 16 categories.

    Professor Edward Wasserman, who led the work, said: "Our birds' rate of learning appears to have been quite slow. Would children learn faster than pigeons? Almost certainly. However, our pigeons came to the experiment with no background knowledge at all. Thus, the more relevant comparison group may be newborn babies, who indeed take 6–9 months to learn their first words."

    Writing in the journal Cognition, the researchers said their experiment was a very simple mirror of the way children are taught words — by their parents pointing to pictures and asking them to name the object.

    Pigeons are known to be smarter than many birds. Professor Bob McMurray, who also took part in the study, said the results showed that human learning is not as unique as was previously believed.

    He said: "Children are facing a huge task of learning thousands of words without a lot of background knowledge to go on. For a long time, people thought that such learning is special to humans. What this research shows is that the ways in which children solve this huge problem may be shared with many species.

    A long-term American study shows the importance of early education for poor children. The study is known as the Abecedarian(初步的) Project. It involved more than one-hundred young children from poor families in North Carolina.

    Half of the children attended an all-day program at a high-quality childcare center. The center offered educational, health and social programs. Children took part in games and activities to increase their thinking and language skills and social and emotional development. The program also included health foods for the children.

    The children attended the program from when they were a few weeks old until the age of five years. The other group of children did not attend the childcare center. After the age of five, both groups attended public school.

    Researchers compared the two groups of children. When they were babies, both groups had similar results in tests for mental and physical skills. However, from the age of eighteen months, the children in the educational child care program did much better in tests.

    The researchers tested the children again when they were twelve and fifteen years old. The tests found that the children who had been in the childcare center continued to have higher average test results. These children did much better on tests of reading and mathematics.

    A few years ago, organizers of the Abecedarian Project tested the students again. At the time, each student was twenty-one years old. They were tested for thinking and educational ability, employment, parenting and social skills. The researchers found that the young adults who had the early education still did better in reading and mathematics tests. They were more than two times as likely to go to college or to have completed college. In addition, the children who received early education were older on average, when their first child was born.

    The study offers more evidence that learning during the first months and years of life is important for all later development.

    The researchers of the Abecedarian Project believe their study shows a need for lawmakers to spend money on public early education. They believe these kinds of programs could reduce the number of children who do not complete school and are unemployed.

    Hotshot jet pilots are no match for cliff swallows. The birds rocket over bridges and skim over lakes, rushing forward at accelerations that would knock an Air Force. By tracking these contests with high-speed cameras, a new study gives the first, in-depth peek into avian aerodynamics (鸟类空气力学) in the wild. "The findings may even provide insight into how to design better micro air vehicles-tiny drones. This technology will be brilliantly useful," says biomechanics expert Jim Usherwood of the United Kingdom's Royal Veterinary College in Hatfield. "High-resolution field studies like this have never been done before for birds."

    For cliff swallows, the trouble starts when they return from wintering in South America to their summer homes in North America. After arrival, they seek out their old mud nests—usually located under concrete bridges and freeways-and start rebuilding their homes. But rather than hunt down a fresh supply of mud, some swallows prefer stealing supplies from their more hardworking neighbors. Others take things further and will even lay an egg or two in their neighbor's nest before taking off.

    Battles in the air follow if the invaders are caught in the act, and a new study takes advantage of these fights to learn how birds perform high-speed maneuvers (演习). The team placed three cameras along a North Carolina lake crossed by a highway bridge that houses several cliff swallow nests and waited for the battles to commence.

The team was surprised to learn that most of the time, chasers copied the move of fleeing invaders. Swallows also pull very hard turns to escape an enemy, with one extreme case reaching 7.8 gravity. Fighter pilots usually pass out at about 5 or 6 gravity, which is why these experiments have earned interest, and partial funding, from the Office of Naval Research. The Navy may use the findings to build better guidance systems for micro air vehicles. However, the swallows' biomechanics are complex, and now the team is simply trying to collect a few tricks.