Think about vitamin D when you're catching up on summer rays. It's sometimes called the “sunshine vitamin” because it's produced in your skin in response to sunlight. Vitamin D is a fat-soluble (脂溶性的) vitamin in a family of compounds that includes vitamins D-1, D-2, and D-3. It can affect as many as 2,000 genes in the body.

    Vitamin D has several important functions. Perhaps the most vital are regulating the absorption of calcium and phosphorous（磷）, and promoting normal immune system function. Getting enough vitamin D is important for normal growth and development of bones and teeth, as well as improving resistance against certain diseases.

    In addition to its primary benefits, research suggests that vitamin D may also play a role in: reducing your risk of multiple sclerosis（多发性硬化）, according to a 2006 study published in the Journal of the American Medical Association decreasing your chance of developing heart disease, according to 2008 findings published in Circulation helping to reduce your possibility of developing the flu, according to 2010 research published in the American Journal of Clinical Nutrition regulating mood and warding off depression losing weight or preventing heart disease.

    How do you get it? Your body produces vitamin D naturally when it is directly exposed to sunlight. A little can go a long way. All you need is 10 minutes a day of midday, pre-sunscreen sun exposure,especially if you have fair skin. Besides getting vitamin D through sunlight, you can also get it through certain foods and supplements to ensure adequate levels of the vitamin in your blood.

For some people, music is no fun at all. About four percent of the population is what scientists call "amusic." People who are amusic are born without the ability to recognize or reproduce musical notes (音调). Amusic people often cannot tell the difference between two songs. Amusics can only hear the difference between two notes if they are very far apart on the musical scale.

As a result, songs sound like noise to an amusic. Many amusics compare the sound of music to pieces of metal hitting each other. Life can be hard for amusics. Their inability to enjoy music sets them apart from others. It can be difficult for other people to identify with their condition. In fact, most people cannot begin to grasp what it feels like to be amusic. Just going to a restaurant or a shopping mall can be uncomfortable or even painful. That is why many amusics intentionally stay away from places where there is music. However, this can result in withdrawal and social isolation. "I used to hate parties," says Margaret, a seventy-year-old woman who only recently discovered that she was amusic. By studying people like Margaret, scientists are finally learning how to identify this unusual condition.

    Scientists say that the brains of amusics are different from the brains of people who can appreciate music. The difference is complex, and it doesn't involve defective hearing. Amusics can understand other nonmusical sounds well. They also have no problems understanding ordinary speech. Scientists compare amusics to people who just can't see certain colors.

Many amusics are happy when their condition is finally diagnosed (诊断). For years, Margaret felt embarrassed about her problem with music. Now she knows that she is not alone. There is a name for her condition. That makes it easier for her to explain. "When people invite me to a concert, I just say, ‘No thanks, I'm amusic,'" says Margaret. "I just wish I had learned to say that when I was seventeen and not seventy."

Venom(毒液）from a local scorpion(蝎子）in Cuba is being used by Cuban scientists as an effective weapon to fight cancer. The venom, with stopping pain, anti-inflammatory (炎症） and anti-cancer properties, is the active ingredient in the medicine “Vidatox 30 CH“ which can be used to treat liver, brain, lung and other cancers. The treatment has been successfully used for more than four years in humans after being first tested in biological models. Labiofam, a Cuban laboratory, has breeding(繁殖)centers for both the Red Scorpion and Blue Scorpion. Each month, some 30,000 scorpions in Las Minas town, 270 km east of Havana are made to give the venom. After two years, the scorpions are released back into their natural habitat.

Denyer Sanchez, a biologist from Labiofam, explained that the conditions are adjusted for reproduction, proved by the high number of breeding female scorpions. He said when the offspring(后代）becomes able to live in the environment, we release them because they do not have the necessary size yet to remove their venom, said Sanchez. Sanchez also said that there is still much to research on the exploitation process of scorpions, such as female death rate or the ability to survive of the released scorpions.

Cuban research on the scorpion's venom began at the end of 1980s in Guantanamo province, the island's eastern tip, where a group of biologists and doctors became interested in the stories told by the peasants about the venom's benefits. However，the first discovery was made by Cuban biologist Misael Bordier. In 2001, Bordier visited Mexico's National Autonomous University (UNAM) and presented the research progress in a professional journal. Bordier died in 2005, one year before Cuba's Industrial Property Office gave Labiofam the rights to exploit the patent related to the venom.

In a time when a dangerous number of people are overweight, many people seem to have forgotten the most important way to keep healthy and slim—exercise. And as a new study carried out on mice in the lab has shown, exercise done early in life can reward you in your adult years.

    A team of researchers at the University of California studied the effects of early exercise on adult physical activity, body mass and eating. They found that early-age exercise in mice has positive effects on adult levels of voluntary exercise in addition to reducing body mass.

    "These results may have an effect on the importance of regular physical education in elementary and middle schools," said Theodore Garland, a professor of biology, who led the research project. "If kids exercise regularly through their school years, then they may be more likely to exercise as adults, which could have far-reaching positive effects on human health and well-being."

    Although the positive effects of early-life exercise lasted for only one week, it is important to note that one week in the life of a mouse is the same as about nine months for humans. "Our results suggest that any positive effects of early-life exercise on adult exercise will need to be kept up if they are to be long-lasting."

    His team of researchers found, too, that all mice that had access to early exercise were lighter in weight than non-exercised mice.

    Garland explained that, in general, exercise will stimulate appetite sooner or later. However, it is possible that certain types of exercise, done for certain periods of time or at certain light levels, might not stimulate appetite much, if at all, at least in some individuals.

    "If we could understand what sorts of exercise these might be, then we might be able to tailor exercise recommendations in a way that would bring the benefits of exercise without increase in appetite, leading to a better chance of weight loss," he said.

    The love story between John F. Kennedy and his wife, Jackie, was far from perfect and was tragically cut short in 1963 by a sniper's(狙击手) bullet.

    On November 22, 1963, President John F. Kennedy was seated beside his smartly dressed wife, who was wearing a pink Chanel-like suit and matching pillbox hat and holding an armful of red roses that had been presented to her by fans. They were seated in the back seat of a dark blue 1961 Lincoln with John Connally, the Governor of Texas and his wife, Nellie.

    And then came the dark moment. As the motorcade(车队) passed the Texas School Book Depository on Elm Street, a loud noise—like the sound of a firecracker—cracked the air. President Kennedy slumped(耷拉) forward, Jackie putting her arms around him.

    The look on her husband's face after he was shot would haunt Jackie for the rest of her life. The last words she ever got to say to him were, "I love you, Jack. I love you," according to Anderson, although Jackie herself recalled it slightly differently in a 1963 interview. All the way to Parkland Hospital, where President Kennedy would eventually be pronounced dead, as she recalled it, she was bent over him, asking "Jack, Jack, can you hear me? I love you."

    Jack Kennedy's final words to his wife of 10 years were far more mundane, of course. He had no way of knowing what was about to happen. It's been reported that Jack's final words were, "My God, I've been hit," but physicians have said this was impossible given Jack's injuries. Well, historians have now clarified that the last words Jack spoke before the fatal shot were, "No, you certainly can't."

    No, you certainly can't?

    He was making small talk in the car. "You certainly can't say that the people of Dallas haven't given you a nice welcome," the Texas Governor's wife had just remarked to Jack, referring to the huge, adoring crowd. "No, you certainly can't," Jack replied, milliseconds before the bullet from Lee Harvey Oswald gun struck.

    John F. Kennedy never spoke another word after that fateful day, but many things he said during his lifetime are incredibly inspiring.

The blue whale holds the current record as the largest creature to live on Earth, but a collection of bones found in Per u might break that record. Researchers have identified a whale species called Perucetus colossus in the publication Nature. Bones from this species, including backbones weighing over 100 kilograms each and ribs measuring nearly 1. 4 meters long, were found by Mario Urbina in 2012 in the Ica desert.

The area where the bones were found was once underwater, making it a rich source of ocean fossils. The find resulted in 13 backbone vertebrae(脊椎), four ribs and a hip bone. The large fossils date back to around 39 million years ago. Alberto Collareta, a lead writer of the study, described the fossils as unlike anything he had ever seen before.

The researchers used 3D scanners to study the bones' surface and also looked inside. Based on the incomplete skeleton, the team estimated that the ancient creature weighed somewhere between 85 and 340 metric tons. Comparatively, the largest blue whales found fell within that range, at around 180 metric tons. The Perucetus colossus measured about 20meters long, while blue whales can reach 30 meters in length. This means the newly discovered whale was "feasibly the heaviest animal ever," said Alberto Collareta. But he added, "it was most likely not the longest animal ever."

Interestingly, the density and weight of the Perucetus colossus' bones were much higher than those of a blue whale. This suggests that the colossal whale may have inhabited shallower coastal waters, similar to other coastal animals with heavy bones.

Another researcher, Amson, said, without the skull, it is hard to know what the whale was eating to support such a huge body. It is possible that the large creature sought food along the seafloor, the researchers said. Or it could have eaten up tons of smaller sea life in the ocean. Swiesen, a paleontologist, added that he would not be surprised "if this thing actually fed in a totally different way that we would never imagine."