Food serves as a form of communication in two basic ways. Sharing bread or other foods is a common human tradition that can promote unity and trust. Food can also have a special meaning, and play an important role in a family or culture's celebrations or traditions. The foods we eat—and when and how we eat them—are often unique to a particular culture or may even differ between rural(郊区的) and urban(市区的) areas within one country.

    Sharing bread, whether during a special occasion(时刻) or at the family dinner table, is a common symbol of togetherness. Many cultures also celebrate birthdays and marriages with cakes that are cut and shared among the guests. Early forms of cake were simply a kind of bread, so this tradition has its roots in the custom of sharing bread.

    Food also plays an important role in many New Year celebrations. In the southern United States, pieces of corn bread stand for blocks of gold for prosperity(兴旺) in the New Year. In Greece, people share a special cake called vasilopita. A coin is put into the cake, which signifies(预示) success in the New Year for the person who receives it.

    Many cultures have ceremonies to celebrate the birth of a child, and food can play a significant role. In China, when a baby is one month old, families name and welcome their child in a celebration that includes giving red-colored eggs to guests. In many cultures, round foods such as grapes, bread, and moon cakes are eaten at welcome celebrations to represent family unity.

    Nutrition(营养) is necessary for life, so it is not surprising that food is such an important part of different cultures around the world.

    Lots of people buy books and products from Amazon, an online seller. They offer and pay over the Internet and the books are shipped through the mail or a delivery service like FedEx.

    One day, people could get their Amazon deliveries from an “unmanned aerial vehicle”—a timely vehicle that looks like a toy helicopter. And instead of waiting days to get the parcel, it could be at the buyer's home in half an hour or less. The company is working on a fleet of tiny vehicles they call “Prime Air”. The vehicles are also known as “octocopters”. On their website, Amazon says, “One day, Prime Air Vehicles will be as normal as seeing a mail trucks on the road today.”

    The U.S.'s Federal Aviation Administration (FAA) is working on safety regulations for unmanned flying vehicles like the Prime Air copters. Those regulations will make sure the copters are able to fly safely where they need to go. Once the FAA has put its rules in place, which could be as early as 2016, Amazon will be ready with its fleet of tiny flyers. The process could take as many as five years.

    The new delivery service would likely be available only in the United States, at first. The copters the company is testing now can handle packages up to five pounds (2.3kg) and they have a range of 10 miles (16 kilometers).

    Other companies are also looking at using unmanned flying vehicles to deliver their products. For instance, Domino's Pizza in the U.K. released a video showing a “DomiCopter”, delivering a pizza. That video may have been a publicity stunt（噱头）. In any case, just like Prime Air's octocopters, the DomiCopters don't have clearance（许可）to take off just yet.

    Teenagers who talk on the phone a lot and hold their cell phones up to their right ears score worse on one type of memory test. That's the finding of a new study. That memory damage might be one side-effect of the radiation that phones use to keep us connected while we're on the go.

    Nearly 700 Swiss teens took part in a test of figural memory. This type helps us recall abstract symbols and shapes, explains Milena Foerster. She's an epidemiologist(流行病学家). She worked on the study as part of a team while Foerster was at the Swiss Tropical and Public Health Institute in Basel, Switzerland. Teens participated memory tests twjce, one year apart. Each time, they had one minute to memorize 13 pairs of abstract shapes. Then they were shown one item from each pair and asked to match it with one of five choices.

    The study volunteers also took a test of verbal memory. That's the ability to remember words. The two memory tests are parts of an intelligence test.

    The researchers also surveyed the teens on how they use mobile phones. And they got call records from phone companies. The researchers used those records to estimate how long the teens were using their phones. This allowed the researchers to calculate how big a radiation exposure each person could have gotten while talking.

    All cell phones give off energy in the form of radio frequency electromagnetic fields, or RF-EMFs. Radio and TV broadcasts also use this type of energy. So do microwave ovens and some other gadgets(配件).

    "For a phone, that energy carries information, in the form of calls or texts between phones and cell phone towers. That radiation also can travel into people's bodies as they use their phones. And some of its energy can be absorbed by the body. So far, scientists have not shown that radiation from phones causes harm," says the Federal

    Communications Commission. Research is ongoing, this agency notes.

    Body language is a broad term for several forms of communication using body movements or gestures, instead of, or as a complement to, sounds, verbal language, or other forms of communication. In turn, it is one category of paralanguage, which describes all forms of human communication that are not language.

    Paralanguage including body language has been extensively studied in social psychology. In everyday speech and popular psychology, the term is most often applied to body language that is thought to be involuntary, but in fact the distinction between voluntary and involuntary body language is often blurred: a smile or a wave may be given either voluntarily or involuntarily, for example.

    Voluntary Body Language is less commonly discussed because it seems unproblematic. It refers to movement, gestures and poses intentionally made by the person: smiling, hands, imitating actions, and generally making movements with full or partial intention of making them and a realization of what they communicate.

    The relation of body language to animal communication has often been discussed. Human paralanguage may represent a continuation of forms of communication that our non-linguistic ancestors already used, or it may be that it has been changed by co-existing language. Some species of animals are especially skilled at detecting human body language, both voluntary and involuntary: this was the reason for trying to teach the chimpanzee Washoe American Sign Language rather than speech and perhaps the reason why the Washoe project was more successful than some previous efforts to teach apes how to dance.

    Body language is a product of both genetic and environmental influences. Blind children will smile and laugh even though they have never seen a smile. The ethnologist (文化人类学者) Iraneus Eibl-Eibesfeldt claimed that a number of basic elements of body language were universal across cultures and must therefore be fixed action patterns under instinctive (本能的) control. Some forms of human body language show continuities with communicative gestures of other apes, though often with changes in meaning. More refined gestures, which vary between cultures (for example the gestures to indicate "yes" and "no"), must obviously be learned or modified through learning, usually by unconscious observation of the environment.

    Earthquakes strike suddenly at any time of the day or night, but there's no way to tell when. If an earthquake happens, it may cause many deaths, injuries and damage. So you need a good preparation ahead of time. Decide how and where your family will get together if separated. Choose an out-of-state friend or relative that the family members can call after the quake to report where they are and how they are. Know the safe places in each room: under the strong tables, desks, or against inside walls. Keep enough food, water and other things, including a flashlight, a radio, medicines and clothing.

    During the earthquake, you should keep a clear head and never be too nervous to know what to do. Protect your head and neck with your arms. If possible, take a book, a pillow or any other things to protect yourself from falling glass and ruins. If you are indoors, you must immediately lie under any strong furniture. If outdoors, move to an open area away from trees, buildings, walls or power poles. If you are in a narrow valley, move to the centre of it and look up for falling stones. If you are in a car, move to the side of the road and stop the car. Do not stop near buildings, power lines or on or under bridges. Stay in your car until the shaking stops.

    Do not move a badly injured person unless he is in great danger after the earthquake. Do not use the telephone immediately unless there is a serious injury or fire. Turn on your radio for instructions and news reports. Be prepared for aftershocks. If you want to leave your home, post a message inside your home telling your family members where you can be found.

    The Harvard Pre-College Program is a nice experience for high school students. Alongside peers(同辈)from around the world, you'll be introduced to college life as you attend classes, live on campus, and enjoy fun outings and activities.

    Learning without limits

    Biology, physics, law, writing and philosophy — these are just a few of the 30-plus courses you can choose from in each session. In our noncredit classes, we set aside grades so that you can fully commit to your growth as a well-rounded student. Class sizes typically range from 14 to 18 students to encourage interactive learning.

    Living at Harvard

    When you attend the Pre-College Program, you'll live in a historic undergraduate house, near Harvard Square. You will be with your fellow Pre-College students, resident directors, and proctors who provide support. You'll also enjoy meals in one of Harvard's dining halls, which are a short walk from Harvard Yard and provide many options for a variety of dietary needs.

    Thriving outside the classroom

    The summer Pre-College Program offers many mentally challenging co-curricular(补充课程的)activities beyond the classroom. With faculty and Harvard-affiliated experts, you will have the opportunity to participate in workshops on topics like the psychology of color-blindness, classic literature from around the world and science of happiness. From our Cambridge scavenger hunt to a trip to the Sand Sculpting Festival at America's first public beach, there's no shortage of fun activities in the Pre-College Program.