On 29 May last year, I was doing my swim training for a half Ironman race in the bay near my home.

    I was finishing my first loop (圈) when I felt jaws coming around my body and a sharp pain. The water was dark, so I couldn't see anything. It just came out of nowhere and then it was gone in a flash. I knew it was something really big and assumed it was a shark. I panicked, but knew I needed to get out of the water. I was kicking wildly in case it came back. There was a lifeguard boat close by, so I waved my arms in the air and screamed for help. It got to me within 20 seconds. At that point I didn't feel anything; adrenaline (肾上腺素) had taken over. The lifeguards held me under the arms and pulled me up out of the water. Then the pain kicked in and it was pretty hard to bear. Some muscle had been bitten off my right arm. I felt a lot of warm, gushing blood.

    My chest felt heavy, as if someone had put their foot on it, and I was having trouble breathing. It was extremely painful. When I got to the hospital, I told the nurses to put me to sleep because of the pain. I just wanted them to fix me.

    I woke up after surgery four hours later. My doctor was amazed when I managed to move my fingers: the bite just missed a major nerve. My right lung had been damaged; I had several broken bones and a nerve in my leg was cut, so I have reduced feeling at the top of my leg. The shark also bit through my upper back muscle.

    Local experts determined that the shark was probably 9-10 feet long. It was young, about seven years old. It just attacked me, left and didn't come back because it figured I wasn't food.

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    Exercise may help to safeguard the mind against depression(沮丧) through previously unknown effects on working muscles, according to a new study involving mice.

    Mental health experts have long been aware that even mild, repeated stress can contribute to the development of depression and other mood disorders in animals and people. Scientists have also known that exercise seems to cushion against depression. But precisely how exercise, a physical activity can reduce someone's risk for depression, a mood state, has been mysterious. So for the new study, researchers at the Karolinska Institute in Stockholm studied the brains and behavior of mice in a complicated and novel fashion.

    We can't ask mice if they are feeling cheerful or in low spirits. Instead, researchers have pictured certain behaviors that indicate depression in mice. If animals lose weight, stop seeking out a sugar solution when it's available — because, probably, they no longer experience normal pleasures — or give up trying to escape from the cold-water zone just freeze in place, they are categorized as depressed. And in the new experiment, after five weeks of frequent but low-level stress, such as being lightly shocked, mice displayed exactly those behaviors. They became depressed.

    The scientists could then have tested whether exercise blunts (延缓) the risk of developing depression after stress by having mice run first. But, frankly, from earlier research, they wanted to know how, so they bred pre-exercised mice. A wealth of earlier research by these scientists and others had shown that aerobic exercise, in both mice and people, increases the production within muscles of an enzyme (酶) called PGC-1alpha. The Karolinska scientists suspected（怀疑） that this enzyme somehow creates conditions within the body that protect the brain against depression. Then, the scientists exposed the animals, which without exercising, were in high levels of PGC-1alpha to five weeks of mild stress. The mice responded with slight symptoms of worry. But they did not develop depression. They continued to seek out sugar and fought to get out of the cold-water zone. Their high levels of PGC-1alpha appeared to make them depression-resistant（抵抗的）. Finally, to ensure that these findings are relevant to people, the researchers had a group of adult volunteers complete three weeks of frequent endurance training, consisting of 40 to 50 minutes of moderate cycling or jogging. The scientists conducted muscle biopsies (活体检查) before and after the program and found that by the end of the three weeks, the volunteers' muscle cells contained substantially more PGC-1alpha than at the study's start.

    The finding of these results, in the simplest terms, is that “you reduce the risk of getting depression when you exercise,” said Maria Lindskog, a researcher at the Karolinska Institute.

    Are you dreaming of taking a trip on your own? Here is some advice on how to make your once-in-a-lifetime journey and how to stay safe when you get there.

    Before you begin to look at places, activities and plane tickets, you must set a budget. When you search through the websites about travelling, it can be so easy to add another week here or there, or choose an extra activity. Setting a budget can avoid（避免） creating a huge bill, which starts very small.

    With so many countries on this planet, it is difficult to decide where to go. By narrowing down your search to voluntary (自愿的) work or a relaxing holiday, you can save a lot of time looking through websites.

    After deciding where to go, you need to research the country. Find out when each season is. It would be disappointing if you were taking part in an outdoor-based activity and it rained most days. Look into medical information, as you may need certain medicine for certain countries. Above all, make sure you can afford to go to this country and take part in the activities you have dreamt about. Don't raise your hopes too high before you know for certain it is within your budget.

    By carrying a credit (信用) card with you at all times,  it is possible to stop yourself getting lost. Mobile phones are very important as well. However, do not depend completely on them, since electronic machines can break without warning. Therefore, always carry a list of emergency (紧急情况) phone numbers, names and addresses. Finally, learn a little of the language. Do not expect that the people there speak your own language. After all, you are in their country.

    Andy rode slowly on his way to school, day-dreaming about the fishing trip that his father had promised him. He was so busy dreaming about all the fish he would catch that he was unaware of everything else around him.

    He rode along until a strange sound drew him to the present. He came to a stop and looked up to the sky. What he saw frightened him. A huge group of bees filled the sky like dark cloud and seemed to be heading angrily towards him.

    With no time to waste Andy sped off in the opposite direction, riding quickly without knowing how to escape the group. With a rapidly beating heart and his legs pumping quickly, he sped down the rough road. As the bees came closer, his fear increased. Andy knew that he was sensitive(敏感的) to bee stings (蜇). Last time a sting had put him in hospital—and that was only one bee sting! He had been forced to stay in bed for two whole days. Suddenly, his father's words came to him. "When you are in a dangerous situation, don't panic. Stay calm, use your brain and think your ways out of it."

    On a nearby hill, he could see smoke waving slowly from the chimney(烟囱) of the Nelson family home. "Bees don't like smoke," he thought. "They couldn't get into the house." Andy raced towards the Nelson house, but the bees were gaining around. Andy knew he could not reach the house in time. He guessed that the bees would catch up with him soon.

    Suddenly, out of the corner of his eyes, he saw a small pond used by Mr. Nelson to water his vegetable garden. Off his bike and into the cool water he jumped, disappearing below the surface and away from the bees. After holding his breath for as long as he could, Andy came up for air and noticed the bees have gone. Pulling himself out of the water, he walked up the hill and rang the doorbell. Mr. Nelson took him inside and rang his mother.

    "You'll really need that fishing break to help you recover(恢复)," laughed his mother. "Thank goodness you didn't panic!" But Andy did not hear her. He was dreaming once again of the fish he would catch tomorrow.

    Cooperation at work is generally considered a good thing. The latest survey by the Financial Times of what employers need from MBA graduates found that the ability to cope with a wide variety of people was what managers have wanted most. However, managers always find ways to balance the benefits of teamwork, which helps ensure that everyone is working towards the same goal. With the dangers of "groupthink", critics are reluctant to point out a plan's drawbacks for fear of being excluded by the group. The disastrous Bay of Pigs Invasion of Cuba in 1961 was a classic case of groupthink. Skeptics were unwilling to challenge John F. Kennedy, the newly elected American president.

    Modern communication methods prove that cooperation is more frequent. Workers are constantly in touch with each other via e-mail messaging groups or mobile calls. However, does that develop, or lower performance? A new study by three American academics, tried to answer this question They set a logical problem (designing the shortest route for a travelling salesman visiting various cities) Three groups were involved: one where subjects acted independently; another where they saw the solutions posted by team members at every stage; and a third where they were kept informed of each other's views only intermittently.

    The survey found that members of the: individualist group reached the: premier solution more often than the constant cooperators but had a poorer average result The intermittent cooperators found the right result, as often as the individualists, and got a better average, solution. When it comes: to: perfect generation, giving: people a, bit of space to, a solution seems to be a great idea. Occasional cooperation can be quite beneficial: most people have benefited from a colleague's brainwave or (just as often)wise advice to avoid a, particular course of action.

    Further clues come from a book, Superminds, by Thomas, Malone of the Massachusetts Institute of Technology. He says that three factors determine the collective intelligence of cooperating groups: social intelligence (how good people were at rating the emotional states of others); the extent to which members took part equally in conversation (the more equal, the better) and the cooperation of women in the group(the higher, the better Groups ranked highly in these areas cooperated far better than others did).

    In short, cooperation may be a helpful tool but it does not work in every situation.

More and more teenagers are becoming unwilling to exercise worldwide. Australia, a nation that prides itself on its outdoor culture, is doing particularly poorly. It is currently ranked (排名) 140th out of 146 countries for teenage exercise levels. The data shows that 85%of girls are physically inactive compared to 78% of boys. In Australia, less than 1 in 10 teenagers aged 12 to 18 are meeting the recommended levels of physical activity. 

The current guidelines and evidence show that teenagers should be doing at least 60 minutes of physical activity per day. This should include muscle and bone strengthening activities on at least three days per week, meanwhile limiting recreational screen time to a maximum of 2 hours per day. 

Not being active can cause a range of health conditions leading to early adulthood and beyond. Adolescents may have decreased bone and cardio-metabolic (心脏代谢的) health which leaves them facing an increased risk of chronic disease (慢性病) in later life, including type 2 diabetes, heart disease, high cholesterol, and decreased fitness. If you're not moving enough you're also at an increased risk of being overweight or obese, with data already showing that 29.8% of teenagers (14-17) are classified as overweight or obese. 

So how can we get teenagers to exercise more? Firstly, high schools should place more importance on lunchtime and allow 1-hour breaks that increase physical activity. We should also encourage teenagers to be active on their lunch break. Parents and guardians also have an important role to play and should aim to devote 1 hour a day to moving more. This does not need to be 1 full hour and can be broken down into two 30-minute parts. The most important factor is to identify your teenager's interests and needs surrounding their physical activity.

Don't be afraid to ask for help in finding a safe and fun exercise program. A qualified exercise physiologist or exercise scientist can help your child find a way to be more active that is suited to their needs, age of development, and interests.