Darek Fidyka, a 38-year-old Bulgarian, had been paralyzed (瘫痪的) from the chest down for four years after a knife attack. Scientists from Britain and Poland took cells from his nose, transplanted (移植) them into his back and re-grew his spinal cord (脊髓). Now he can walk and even drive a car. The doctors were delighted but said it was the first step in a long journey.

    The breakthrough came after 40 years of research by Professor Geoff Raisman, who found that cells had the possibility to repair damage to nasal (鼻腔的) nerves, the only part of the nervous system that constantly re-grows. “The idea was to take something from an area where the nervous system can repair itself and put it into an area that doesn't repair itself,” Professor Raisman said.

    Polish doctors injected (注射) the nasal cells into Mr Fidyka's spinal cord above the injury and used some nerves from his ankle to form a bridge across the damaged tissue. The nasal cells appear to have caused the spinal nerves to repair themselves.

    Professor Raisman achieved this with rats in the late 1990's, but this is his greatest success. “I think the moment of discovery for me was Christmas in 1997 when I first saw a rat, which couldn't control its hand, put its hand out to me. That was an exciting moment, because I realized then that my belief that the nervous system could be repaired was true.”

    Doctors chose the easiest case for their first attempt—it might not work for others. But there is a real sense of hope that an idea once thought impossible has been realized.

    David Nicholls, who helped provide money for the breakthrough, said information about the breakthrough would be made available to researchers across the globe.

    “What you've got to understand is that for three million paralyzed people in the world today, the world looks a totally brighter place than it did yesterday,” he said.

    From the loss of wildlife to rising sea levels, we're all well aware of the problems that climate change could cause.

    But while it may seem like such issues won't affect most of us directly，it looks like future generations could grow up without something that many of us now take for granted: chocolate.

    According to an essay published by the US National Oceanic and Atmospheric Administration, changes to the climate in the regions that produce cacao - the plant from which chocolate is produced - may mean that it will soon become extinct.

    Most of the world's cacao grows in countries close to the equator，with over half of it growing in the African nations of Ghana and Ivory Coast.

It's predicted that by 2050, climate change will have accelerated the rate at which temperatures in these countries rise, making it extremely difficult for cacao to grow there.

    The problem doesn't lie in increased heat, however，but in lower humidity (湿度)，as it's believed that rainfall will stay at the same level if the temperature rises.

    “In other words, as higher temperatures squeeze more water out of soil and plants, it's unlikely that rainfall will increase enough to offset the moisture (含水量) loss,” Michon Scott, the essay's author, wrote.

    To help fight this problem, researchers from Berkeley University in the US are working on changing the DNA of cacao plants to allow them to survive in dryer conditions by using gene editing technology, according to US News.

    In the meantime, US company Mars, one of the world's biggest manufacturers of chocolate products, announced in January that it would spend $1 billion to help reduce the effects of climate change.

    “This is a world issue, and it requires everyone to work together,” Mars spokesperson Barry Parkin told Business Insider.

    The message here is that if we all do our part, we may be able to prevent some of the worst impacts of climate change. Or if we're unlucky, chocolate will become a thing of the past.

    If your dog looks pleased to see you—it is probably because it loves the particular way you smell.

    The scent (气味)of a familiar human apparently lingers like perfumein the animal's brain—where it causes an instinctive emotional response, research reveals.

    Our scent acts on a part of the canine (犬科的) brain associated with reward and the strongest reactions are produced by humans that pets know best, say scientists in America.

    Gregory Bern, of Emory University in Atlanta, said, “While we might expect that dogs should be highly tuned to the smell of other dogs, it seems that the 'reward response' is reserved for their humans. When humans smell the perfume of someone they love, they may have an immediate, emotional reaction that's not necessarily cognitive (认识的). So is it in dogs. But since dogs have a more sensitive smell than humans, their responses would likely be even more powerful than the ones we might have. In our experiment, however, the owners of the dog were not physically present. The canine brain responses were being caused by something distant in space and time. It shows that dogs' brains have these mental representations of us that persist when we're not there.”

    The experiment involved 12 dogs of various kinds by brain scans while five different scents were placed in front of them. The scent samples (样本)came from the subject (接受试险者) itself, a dog the subject had never met, a dog living in the subject's household. The familiar human scent samples were taken from someone else from the house other than the handlers during the experiment, so that none of the scent donors were physically present.

    The results showed all five scents gained a similar response in parts of the dogs brains involved in detecting smells. Responses were significantly stronger for the scent of familiar humans, followed by that of familiar dogs. The findings showed dogs reacted strongest to the scent of familiar humans even when they were not there. Pets trained as help or therapy dogs showed greater brain activity than the other dogs in the test.

    Researchers say the findings could improve the way to select animals helping wounded old soldiers or disabled people.

    The horse I'm riding is named Candy, which is appropriate, taking account of her love for eating. As we go our way down the mountain of Big Bend National Park, Texas, I'm sweating—half due to the hot weather, half due to an effort to stay on the horse. Candy, however, is relaxed and stops to eat cactuses (仙人掌) as she passes. She is used to the dusty trails through hills and canyons(大峡谷) and ignores my attempts to guide her away from her delicious food. Our ride becomes a battle of will, which Candy wins easily. I comfort myself by admiring the views across Big Bend's wide open spaces.

    Texas only national park, Big Bend, extends across 800,000 acres of the Chihuahuan Desert, in the deep southwest of the state right along the border with Mexico. It is named after the U-turn that the Rio Grande River makes here. It has seen a lot of fights. The Spanish, Anglo-American settles, Mexicans, and Apache and Comanche American Indians all fought to rule this place.

    Our group member, Mike, knows every corner of the park and describes it as “sort of a secret place”. Even some Texans don't know about Big Bend, he says. Other local people describe it as a forgotten national park. Compared with the almost five million travellers that descend on the Grand Canyon every year, only 30000 make it here.

    There are six of us in the riding group, all fairly inexperienced, led by tour guides, Linda and Janelle, who keep both us and the horses in line. We trek along the top of an 800-foot mountain, with wide-winged eagles flying beside us. The air is noiseless.

    The park is fantastic for hikes and has a variety of marked walking paths. The walk is a five-mile round trip. While the final stretch is rather steep, the views over giant canyons and plains are worth the effort.

    As Simon Kindleysides, 34, took his first step in the London Marathon in April, he felt as if magic was in the air.

    "As we were walking toward the first mile, we actually started joining all the runners," he said. "Everyone was on the streets, cheering, and that was a magical moment." As time went on, the crowds and other racers spread around. Kindleysides and his team of eight supporters continued walking.

    Kindleysides, who is paralyzed(瘫痪的)from the waist down and typically uses a wheelchair, was equipped with an exoskeleton(体外骨骼)to help him walk. His supporters walked with him to change the batteries in his exoskeleton so he could keep moving.

    In 2013, Kindleysides was diagnosed with a brain tumor (肿瘤) that was growing in a way that pressed on certain nerves, leading to him losing feeling in his legs. He was told he would never walk again. Before his paralysis, the London­based singer and dancer had "always wanted to run a marathon," he said, but he never made the plan to do so­­until this year.

    During the London Marathon, the last two miles were the hardest. "At that point, I was exhausted. It was freezing cold, and I was hurting emotionally," Kindleysides said. But he kept going. "I didn't want to let people down. I had a team of eight, and I was raising money for The Brain Tumour Charity," he said. "I didn't want to let them down, myself down, and I thought if I would get this far, I would have to continue."So he continued and made history as the first paralyzed man to complete the London Marathon on foot.

    Then, recovering at home, he shared his accomplishment with his three children. "They used to say I'm the only dad in their whole school who's in a wheelchair, and now they say I'm their dad, the only one who has walked a marathon," he said.

    Kindleysides is training to complete three more marathons next year, including the London Marathon again.

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.