“Community” is not a concept that is easy to define (定义) . In this essay I will examine what turns individuals into a community, and discuss some different types. I will also look at what all communities have in common, the benefits they offer and draw conclusions about their increasing importance.

    The word “community” may make you think of traditional communities in the developing world, where large families live together. We may also imagine the neighbours as people who are happy to help out whenever it is needed. The stereotpical(老套的) view is that of a village, where people have little but can feel very rich because everyone takes responsibility for the welfare of the others.

    On the other hand, there are other types of communities: ultramodern(超现代的) ones, where the community members are unlikely to have actually met each other. These are online communities, where people blog or chat about particular issues that are important to them. They come across others on websites and may develop a relationship there with like-minded people, discussing the same topics. The view is often that these are artificial connections between people who are, in effect, still isolated(孤立的) strangers.

    In reality, the connections are real. Moreover, there are many types of communities in between these extremes: people who join clubs, who sign up with voluntary, political or other organizations, or who take part in group discussions in their local area. They may be campaigning about issues or simply getting together for companionship and support.

    Human beings are social by nature, so it should not be a surprise that we organize ourselves in groups. However, there is more going on: these groups provide something that we cannot achieve on our own. The main benefit of being part of a larger group is strength in numbers. For example, we can access and share more information, we can take part in team sports, we can complain and campaign more effectively and even if we are just having a chat, online or in person, we can feel supported in whatever we do.

    Whatever forms communities take, what defines them is the sense of identity and safety that they provide for their members: the knowledge that there are people who we have something in common with and who can be relied on when we need each other.

    Doctors in hospital emergency rooms often see accidental poisonings. A frightened parent arrives with a child who swallowed a cleaning liquid. Or perhaps the harmful substance is a medicine. Or it might be a product meant to kill insects. These are common causes of accidental poisoning.

    In cases like this, seek medical help as soon as possible. Save the container of whatever caused the poisoning. And look on the container for information about anything that stops the effects of the poison. Save anything expelled from the mouth of the victim. That way, doctors can examine it.

    Millions of people know how to give abdominal thrusts(腹部按压)to save a person choking on something trapped in the throat. The American Red Cross says a rescuer should first hit the person on the back five times between the shoulder bones. If the airway is still blocked, the Red Cross suggests pushing hard five times along the victim's abdomen. You can do these abdominal thrusts by getting directly behind a sitting or standing person.

    The Mayo Clinic health centers suggest several steps if bleeding is severe. First, if possible, remove dirt from the wound and press on it with a clean cloth or piece of clothing. In the past, people were advised to stop severe bleeding with a tourniquet(止血带). But experts now say tourniquets are dangerous because they can crush(挤压) major arteries and nerves. If a wound seems infected, let the victim rest. Physical activity can spread the infection. Treat the wound with a mixture of salt and water until medical help arrives.

    To learn more about first aid, ask a hospital or an organization like the Red Cross or the Red Crescent Society for information. Training may be offered in your area.

    If you know first aid methods, you can be calmer and more helpful in case of emergency. 

    I went online to check if my pay was in my bank account. To my amazement, I discovered that not only had I been paid, a company I'd never worked for had also paid me! I knew I'd have been beside myself if my own salary was not in my account, so I tried to get the money back to the right person. It is easier said than done.

    The bank couldn't help as it wasn't a bank problem. The human-resource department as the company that paid me was unable to help as I didn't have enough details. I rang the bank again. Thankfully I had sympathetic call operator who gave me a name, so I again rang the company "Daniel" worked for.

    I expected the bank would contact me to arrange to take the money from my account and repay Daniel. I heard nothing for a month and the money remained in my account when Daniel called, explaining he'd tried to get back his money but had been unsuccessful as neither the bank nor his company felt it was their error. He had rung to ask if I could speak to the bank, but after chatting for a few minutes we realized we could probably fix this problem ourselves.

    We decided I would take the money from my account and he would pick it up from me. Due to my busy job I was unable to meet Daniel personally but he left me a lovely bottle of wine in exchange for what was rightfully his. I never had any intention of keeping Daniel's pay, but red tape（繁琐手续）made it difficult to do the right thing. It all came down to two people being able to do what a huge bank and a large company couldn't do — admit a mistake has occurred and fix it.

    For several decades, there has been an organized campaign intended to produce distrust in science, funded by those whose interests are threatened by the findings of modern science. In response, scientists have tended to stress the success of science. After all, scientists have been right about most things, from the structure of the universe to the relativity of time and space.

    Stressing successes isn't wrong, but for many people it's not persuasive. An alternative answer to the question "Why trust science?" is that scientists use the so-called scientific method. But what is called the scientific method isn't what scientists actually do. Science is dynamic: new methods get invented; old ones get abandoned; and at any particular point, scientists can be found doing many different things. False theories sometimes lead to true results, so even if an experiment works, it doesn't prove that the theory it was designed to test is true.

    If there is no specific scientific method, then what is the basis for trust in science? The answer is the methods by which those claims are evaluated. A scientific claim is never accepted as true until it has gone through a long process of examination by fellow scientists. Scientists draft the initial version of a paper and then send it to colleagues for suggestions. Until this point, scientific feedback is typically fairly friendly. But the next step is different: the revised paper is submitted to a scientific journal, where things get a whole lot tougher. Editors deliberately send scientific papers to people who are not friends or colleagues of the authors, and the job of the reviewer is to find errors or other faults. We call this process "peer review" because the reviewers are scientific peers—experts in the same field—but they act in the role of a superior who has both the right and the responsibility to find fault. It is only after the reviewers and the editor are satisfied that any problems have been fixed that the paper will be printed in the journal and enters the body of "science."

    Some people argue that we should not trust science because scientists are "always changing their minds." While examples of truly settled science being overturned are far fewer than is sometimes claimed, they do exist. But the beauty of this scientific process is that science produces both creativity and stability. New observations, ideas, explanations and attempts to combine competing claims introduce creativity; transformative questioning leads to collective decisions and the stability of scientific knowledge. Scientists do change their minds in the face of new evidence, but this is a strength of science, not a weakness.

Scientists at the Department of Energy's Lawrence Berkeley National Laboratory and the California Institute of Technology have-in just two years-nearly doubled the number of materials known to have potential for use in solar fuels.

They did so by developing a process that promises to speed the discovery of commercially viable (商业可行性) generation of solar fuels that could replace coal, oil, and other fossil fuels.

Solar fuels, a dream of clean-energy research, are created using only sunlight, water, and carbon dioxide. Researchers are exploring a range of possible target fuels, but one possibility is to produce hydrogen by splitting water.

Each water molecule (分子) consists of one oxygen atom and two hydrogen atoms. The hydrogen atoms are extracted, and then can be reunited to create highly flammable hydrogen gas or combined with CO 2 to create hydrocarbon fuels, creating a plentiful and renewable energy source. The problem, however, is that water molecules do not simply break down when sunlight shines on them-if they did, the oceans would not cover most of the planet. They need a little help from a solar-powered catalyst (催化剂).

To create practical solar fuels, scientists have been trying to develop low-cost and efficient materials that perform the necessary chemistry using only visible light as an energy source.

A new method was developed through a partnership between the Joint Center for Artificial Photosynthesis (JCAP) and Berkeley Lab's Materials Project, using resources at the Molecular Foundry and the National Energy Research Scientific Computing Center (NERSCC). JCAP focused on developing a cost-effective method of turning sunlight, water, and carbon dioxide into fuel. It is led by Caltech with Berkeley Lab as a major partner. The Materials Project is a program based at Berkeley Lab that aims to remove the guesswork from materials design in a variety of applications.

"What is particularly significant about this study, which combines experiment and theory, is that in addition to identifying several new compounds for solar fuel applications, we can also learn something new about the basic electronic structure of the materials themselves." says Neaton, the director of the Molecular Foundry.