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    Measles(麻疹), which once killed 450 children each year and disabled even more, was nearly wiped out in the United States 14 years ago by the universal use of the MMR vaccine(疫苗). But the disease is making a comeback, caused by a growing anti-vaccine movement and misinformation that is spreading quickly. Already this year, 115 measles cases have been reported in the USA, compared with 189 for all of last year.

    The numbers might sound small, but they are the leading edge of a dangerous trend. When vaccination rates are very high, as they still are in the nation as a whole, everyone is protected. This is called “herd immunity”, which protects the people who get hurt easily, including those who can't be vaccinated for medical reasons, babies too young to get vaccinated and people on whom the vaccine doesn't work.

    But herd immunity works only when nearly the whole herd joins in. When some refuse vaccination and seek a free ride, immunity breaks down and everyone is in even bigger danger.

    That's exactly what is happening in small neighborhoods around the country from Orange County, California, where 22 measles cases were reported this month, to Brooklyn, N.Y., where a 17-year-old caused an outbreak last year.

    The resistance to vaccine has continued for decades, and it is driven by a real but very small risk. Those who refuse to take that risk selfishly make others suffer.

    Making things worse are state laws that make it too easy to opt out(决定不参加) of what are supposed to be required vaccines for all children entering kindergarten. Seventeen states allow parents to get an exemption（豁免), sometimes just by signing a paper saying they personally object to a vaccine.

    Now, several states are moving to tighten laws by adding new regulations for opting out. But no one does enough to limit exemptions.

    Parents ought to be able to opt out only for limited medical or religious reasons. But personal opinions? Not good enough. Everyone enjoys the life-saving benefits vaccines provide, but they'll exist only as long as everyone shares in the risks.

For only the second time in her life, actress Olivia Holt, 15, traveled to New York—this time to catch the award—winning Disney Broadway show Newises. Adriana Palmieri, the reporter from Time for Kids（TFK）,was there with Olivia and interviewed Olivia about the experience and her career. “I think the show is inspiring other people to make a big influence on the world today,” Olivia told TFK.

    Olivia is no stranger to the stage. This young star started acting at age three, and progressed from a small stage to a hit TV show, Disney XD's Kickin 'It. But even today she gets very nervous before each show. She overcame her nervousness by staying positive. “I end up just keeping my head up and seeing where it takes me and usually, it takes me to a good place where I'm not so nervous,” Olivia said.

    Olivia grew up in Mississippi but moved to Los Angeles recently to pursue her career. “It was a big transition for me because I grew up in a small town,” Olivia said. But now, she's living her dream as an actress. When asked about advice for other aspiring actors, the young performer said, “Just stay positive and stay confident. If you know that you're powerful enough to conquer your fears and stay happy, that will lead you in the right way.”

    Olivia regularly stars on a Disney XD show called Kickin'It. She plays the fearless black belt Kim. “I think she is such an incredible girl and I look up to her.” Olivia said about her character, “She is so powerful and confident.”

    Entrepreneur and CEO of Tesla and Space X, Eldon Musk may have a little more time on his hands, as he's leaving his position on the board of the Open Al, according to a blog post.

    The departure is likely the result of Tesla's moving into the field of Artificial Intelligence(AI)，which he said in 2017 would be the “best in the world”and would even be able to “predict your destination, ”Musk will continue to “donate and advise the organization,” Open AI said in a blog post on Feb. 20, adding that “As Tesla continues to become more focused on AI, this will avoid a potential future conflict for Eldon.

    Musk and Y Combiner CEO Sam Altman co-founded the nonprofit enterprise in December2015, its mission is to develop safe artificial general intelligence and ensure those developments are made public. Open AI researchers published a paper on the site ArXiv, org, detailing the possible secure threats that come with“malicious”AI. In fact, Musk has heard the “evil AI”alarm several times, On Aug.11，2017, he warned that artificial intelligence poses a bigger threat to humanity, and he told a gathering of state governors that the government needs to regulate Al before robots start “killing people. ”

    Musk's departure from the Open AI board could mean big things for Tesla. As Eton Goodbye, a financial reporter, noted on Futurism, the move “could signal that Tesla is more deeply committed to their own AI projects than we thought. ”He added, “Those who have had their ears to any rumors (谣言)that Tesla is ready to deliver vehicles capable of Level 5autonomy could take this new Open Al development as a sign that the company is inching closer to that unapproachable goal, ”No company has reached that level of autonomy, which means that a driverless car could navigate any road under any conditions and that all the human “driver” would need to do is to input a destination.

    Nola (August 21, 1974 -November 22, 2015) was a northern white rhino who lived at the San Diego Zoo Safari Park near Escondido, California. At her death, she was one of only four remaining northern white rhinos in the world. The other three lived in Kenya. World Rhino Day, held on September 2, is to raise awareness(意识) of the less than 30,000 other rhinos left on Earth.

    “Rhinos need our help today, not tomorrow,” Nola's lead keeper Jane Kennedy said. “Last year we lost over 1,200 rhinos just in South Africa. If we continue to lose more than 1,000 rhinos a year, in 10 to 20 years all the rhinos on the planet will be gone.”

    “Unfortunately, most animals are in danger of dying out because of humans,” Kennedy says.“ Humans have either poached animals, or because there are over seven billion of us, we've taken up too much of the world's resources”. Poachers illegally hunt rhinos for their horns. They sell the horns for thousands of dollars per pound, to be used for art, jewelry, and decorations. Experts believe that one rhino is poached every eight hours.

    In 1975, the San Diego Zoo Institute for Conservation Research started the Frozen Zoo, a program through which researchers have collected cell (细胞) samples from more than 8,000 different types of animals, including the northern white rhino. Scientists hope that by studying the rhino cells, they will get greater understanding of it, and will find ways to increase its numbers.

    Jane Kennedy describes World Rhino Day as “a celebration of rhinos along with an awareness campaign for everybody across the world to know that rhinos need our help.”At the San Diego Zoo, children and adults are welcome to visit and speak with zookeepers to learn about rhinos. But you don't have to live in San Diego to celebrate World Rhino Day. It is observed around the world, with zoos and wildlife parks holding special events and programs to teach people about rhinos, and enable them to see the animals up close. For more information, go to www.worldrhinoday.org.

    It is widely accepted that nightmares (噩梦) are a reaction to negative experiences that happen during waking hours. However, some scientists believe that nightmares do have some real benefits. One 2017 study, for example, found that frequent nightmare sufferers rated themselves as more empathetic (有同理心的). They also displayed more of a tendency to unconsciously mirror other people through things like yawning People who have constant nightmares also tend to think further outside the box on psychoanalysis tasks. Some other researchers have found support for the idea that nightmares might be linked to creativity.

    People seeking cure for nightmares were not necessarily more fearful or anxious, but rather had a general sensitivity to all emotional experience. Sensitivity is the driving force behind intense dreams. Heightened sensitivity to threats or fear during the day results in nightmares, whereas heightened passion or excitement may result in positive dreams. And both these forms of dreams may feed back into waking life, perhaps increasing suffering after nightmares, or promoting social bonds and empathy after positive dreams.

    The effects go further still. This sensitivity overflows into awareness and thoughts －people who have a lot of nightmares experience a dreamlike quality to their waking thoughts. And this kind of thinking seems to give them a creative edge. For instance, studies show that such people tend to have greater creative talent and artistic express and people who often have nightmares also tend to have more positive dreams than the average person.

    The evidence points towards the idea that, rather than disturbing normal activity, people who are unfortunate in having a lot of nightmares also have a dreaming life that is at least as creative, positive and vivid as it can be distressing and terrifying. What's more, this imaginative richness is unlikely to be limited to sleep, but also is filled with waking thoughts and daydreams. Even after people wake up and shake off the nightmare, in other words, a mark of it stays behind, possessing them throughout the day.

    At the age of 14, James Harrison had a major chest operation and he required 13 units (3.4 gallons) of blood afterwards. The blood donations saved his life, and he decided that once he turned 18, he would begin donating blood as regularly as he could.

    More than 60 years and almost 1,200 donations later, Harrison, whose blood contains an antibody (抗体) that has saved the lives of 2.4 million babies from miscarriages (流产), retired as a blood donor on May 11. Harrison's blood is valuable because he naturally produces Rh-negative blood, which contains Rh-positive antibodies. His blood has been used to create anti-D in Australia since 1967.

    "Every bottle of Anti-D ever made in Australia has James in it," Robyn Barlow, the Rh program director told the Sydney Morning Herald. "It's an amazing thing. He has saved millions of babies. I cry just thinking about it." Since then, Harrison has donated between 500 and 800 milliliters of blood almost every week. He's made 1,162 donations from his right arm and 10 from his left.

    "I'd keep going if they let me," Harrison told the Herald. His doctors said it was time to stop the donations — and they certainly don't take them lightly. They had already extended the age limit for blood donations for him, and they're cutting him off now to protect his health. He made his final donation surrounded by some of the mothers and babies who his blood helped save.

    Harrison's retirement is a blow to the Rh treatment program in Australia. Only 160 donors support the program, and finding new donors has proven to be difficult. But Harrison's retirement from giving blood doesn't mean he's completely out of the game. Scientists are collecting and cataloging his DNA to create a library of antibodies and white blood cells that could be the future of the anti-D program in Australia.