“The U．S.Food and Drug Administration(FDA)is considering to put stricter limits over tanning salons(晒黑廊)and wants to ban anyone younger than 18 years of age from using a tanning bed，”an advisory panel(专家团)announced last week.

    The panel is calling for tighter controls on the industry such as requiring teenagers to get the approval from their parents before using tanning beds or limiting the use of artificial tanning to a certain age.“Given the absence of any demonstrated benefits，I think it is an obligation for us to ban artificial tanning for those under 18，”said panelist Dr.Michael Olding.

    Along with a possible ban for teenagers，the panel also recommended that visible warning labels should be placed either on the tanning machines or in the salons in order to caution tanners of the possible dangers.In addition，the committee decided that stricter regulations and classifications were critical to make the machines safer.At this time the machines are categorized as FDA Class 1 devices，the ones that are least likely to cause harm.In case the FDA decided to change their classification from Class 1 to Class 2，as advised by the panel，the FDA could limit the levels of radiation the machines emit.Class 2 devices include X­ray machines and powered wheelchairs.

    Getting a tan，whether from a tanning bed or the sun，increases the risk of developing skin cancer.Last year，the World Health Organization's International Agency for Research on Cancer (IARC)declared tanning beds as “carcinogenic(致癌的)to humans”．It was discovered that young individuals in their teens and 20s who use tanning beds on a regular basis have a 75 per cent higher risk of suffering from melanoma(黑素瘤)，the deadliest form of skin cancer.According to the American Cancer Society，melanoma accounted for nearly 69,000 cases of skin cancer in 2009 and will account for most (about 8,650)of the 11,590 mortality cases due to skin cancer each year.

    Two recent studies have found that punishment is not the best way to influence behavior.

    One showed that adults are much more cooperative if they work in a system based on rewards. Researchers at Harvard University in the United States and the Stockholm School of Economics in Sweden did the study.

    They had about two hundred college students play a version of the game known as the Prisoner's Dilemma. The game is based on the tension between the interests of an individual and a group. The students played in groups of four. Each player could win points for the group, so they would all gain equally. But each player could also reward or punish each of the other three players. Harvard researcher David Rand says the most successful behavior proved to be cooperation. The groups that rewarded the most earned about twice as much in the game as the groups that rewarded the least. And the more a group punished itself, the lower its earnings. The study appeared last month in the journal Science.

    The other study involved children. It was presented last month in California at a conference on violence and abuse（虐待）. Researchers used intelligence tests given to two groups. More than eight hundred children were aged two to four the first time they were tested. More than seven hundred children were aged five to nine. The two groups were retested four years later, and the study compared the results with the first test. Both groups contained children whose parents used physical punishment and children whose parents did not.

    The study says the IQs of the younger children who were not spanked were five points higher than those who were. In the older group, the difference was almost three points. The more they are spanked, the slower their mental development.

    Some materials are obtained from natural resources that are changed by chemical processes in a laboratory. The resulting artificial materials are synthetic, or human-made.

    Plastic is a synthetic substance, obtained from petroleum, a fossil fuel. The molecules（分子）in petroleum are split and then linked into chains. Plastic is an example of a polymer, a material made of repeating patterns of atoms linked together. Most polymers are synthetic. They are made by polymerization, the process of chemically linking many smaller molecules to form a larger molecule that has different physical features. Some polymers, such as proteins, occur naturally.

    Plastic is a key component of many products. When heated into an almost-liquid form, plastic can be made into fibers, sheets, or molds（模具）. It can be mixed with other elements to remain flexible, or it can harden into a solid. Plastic fibers can be made into clothing or carpeting. Sheets of plastic can be made into plates. Molded plastic can be sued for protective helmets or car bumpers.

    Most plastics can be reheated and remolded repeatedly. This feature makes plastic very easy to use. Polymers can be pulled into fine strings or molded into almost any kind of shape. For example, tubes of plastic can be shaped into bottles by different processes. One such process is extrusion blow-molding. Most plastics are also resistant to many chemicals that might harm other materials. This quality is the reason that so many cleaning liquids are packaged in plastic bottles.

    Plastics are good insulators that can stop electricity or heat to pass through. Look around your kitchen, and observe where plastics are used. Pot handles are sometimes made of plastic, as are cooking tools, toaster controls, and microwave cookware. Food-storage wraps and containers may be made of plastic. Take a walk outdoors, and note all the plastic items you see. Gardening tools, such as watering cans and sprayers, are often made of plastic. Swings and slides made of plastic do not become as hot as metal, so they are safer for play. Because plastics can be heated, remolded, and made into something else, they can be recycled and reused.

    Are you a procrastinator（拖拉者）? It's a common problem. And it can be harmful, as previous research has shown that people who procrastinate have higher levels of stress and lower well-being, reported the Association for Psychological Science in the US. But a new study has found a way to deal with this problem: Be more connected to your future self.

    Psychologists think that each person believes that they are really two people: “Present Me” and “Future Me”. “People act as if they prefer their current selves' needs and desires to those of their future selves,” wrote psychologists Neil Lewis and Daphna Oyserman.

    Oyserman and Lewis decided to try to find a way to make “Present Me” imagine exactly how “Future Me” would feel the night before a big paper was due, though “Present Me” hadn't started yet. They made “Present Me” think about a far-off event as a number of days away, not months or years.

    Thinking about events in this way meant that something like a friend's wedding seemed 16.3 days sooner when considered in days rather than months and 11.4 months sooner when considered in months rather than years.

    The researchers also tried to find out whether people would take action sooner if they were told a certain event was happening in X days rather than years.  For example, participants imagined they had a newborn child, and that the child would need to go to college in either 18 years or 6,570 days. The researchers found those in the “days” condition planned to start saving four times sooner than those in the “years” condition.

    So if you think of your life in days instead of years, you may get things done quicker.

    People love cellphones, which is why nine in ten Americans own one. But does heavy use of cellphones pose a risk of cancer? This question has caused controversy for many years. A new study in rats now augments those concerns. Its data linked long-term, intense exposure to radiation from cellphones with an increased risk of cancer in the heart or brain. The results have yet to be confirmed, the authors note.

    Indeed, although the rat study found a link between cellphone radiation and cancer, it offers no clues to why such a link might exist, notes Jonathan Samet. He teaches preventative medicine and directs the Institute for Global Health at the University of Southern California in Los Angeles. Still, he calls the new study's findings “significant”.They could lead to studies researching how cellphone radiation might cause cancer, he says.

    Phone signals are relayed between cell towers and cellphones via radio waves. This radio frequency—or RF—radiation is a type known as non-ionizing (非电离的).Unlike X-rays, non-ionizing radiation does not deposit enough energy into cells to release electrons from atoms or molecules, producing ions. So it tends to be far less harmful than ionizing radiation, such as X-rays. But that does not mean radio waves might not cause harm.

    In very large doses (量) this radiation will heat the body and cause tissue damage. But it's not yet known what much lower RF levels might do, such as those from cellphone use. Five years ago, the World Health Organization's International Agency for Research on Cancer, or IARC, concluded that cellphone use “is possibly carcinogenic (致癌的)”.

    Its conclusion was based on what little research data was available at that time. But notice that IARC was not certain. It said only that phone use might “possibly” cause cancer. So scientists at the National Toxicology Program, or NTP, investigated further.

    A body image is the way a person views his or her body. It affects how a person “feels” about his or her body. For example, when not looking in a mirror, people have a sense of what their bodies look like. A positive body image is having a realistic and accepting view of your body. However, very few women have a positive body image. Society, dieting, eating disorders, and overweight are all related to a negative body image.

    A century ago, full and curvaceous (曲线美的) bodies were admired. They were also more natural for women to keep. Nowadays, the best female body has a tiny waist, flat stomach, thin legs, and is very slim. Women are told to weight less than ever before. Supermodels are the new women's idols. However, most of them are teenagers, and many of them have eating disorders or diet strictly. Trying to follow these standards is hard to most women. As a result, they starve themselves, or exercise—excessively (过度地), or both.

    Most women who know the standard of beauty and body weight are dieting to reduce weight and change their figures. Eating disorders are not simply unhealthy diet habits; they are considered as mental illnesses and can sometimes end in death. Strict dieting or food restriction combined with a negative body image can become an eating disorder.

    A negative body image can also lead to overweight. This is due to excessive eating to comfort bad feelings about their bodies. In addition, yo-yo dieting, which often follows a negative body image, leads to increasingly higher weights with each diet attempt.

    A negative body image is bad for women. I may help them to see an advisor who is good at treating women with negative body images. Lastly, if society worked on encouraging healthy lifestyles and healthy looking bodies for women, a lot of good would come from it.