Machu Picchu is an unusual site in Peru and one of the most mysterious wonders of the world. Built at almost 10,000 feet on the top of an Andean mountain, the Incas built hundreds of structures made of stone. A large number of Machu Picchu's surrounding structures date back to the early 13th century, but it was considered a chief sacred site far before then. The Inca people changed the large site into a very small but wonderful city, completely self-sufficient and hidden from below. Agricultural terraces (梯田) surrounded the entire city, fed by natural spring water, supporting the entire population.

Inca Trail

    The trail is one of the most famous in the world and regarded as one of the best. It covers only 26 miles, combining cloud forest, green mountain scenery, forest, and plenty of tunnels, paving stones, and ruins. The four-day hike begins slowly but quickly changes into a difficult journey suitable for those in excellent shape. The trail winds through the Andes, leading alongside and through ruins. Though independent hiking was once permitted, now it must be done with a guide.

Funerary Rock

    It is believed that the Funerary Rock at Machu Picchu was used as a place to prepare Inca nobles for preservation, or mummifying (做成木乃伊), a common habit among the tribe. Nobles would be laid out to be mummified by the hot sun and freezing cold nights after their organs were removed. The rock is also famous as a spot from which a view of the city is afforded.

Temple of the Sun

    Within the city's castle, deep within Machu Picchu, is the Temple of the Sun, accessed only by the Emperor and

    Inca priests. It means the Inca's advanced knowledge of religion, weather, and nature, showing the great extent

    Incas went to adapt to and learn about nature. Still unbroken, the temple was built to honor the god Inti, who is exactly the sun. The temple was effectively protected. It was also a very important scientific center, built in half-moon shape with openings facing north and east. The windows' shadows in the center of the temple helped see the start of winter solstice (至日), showing farming season.

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    83-year-old Antonio Vicente has spent the last four decades of his life fighting against the trend. As Brazilian landowners cut down rainforests to make room for profitable plantations(种植园) and cattle grounds, he struggled to bring the jungles of his childhood back to life.

    "When I was a child, the peasants cut down the trees to make grasslands and charcoal, and the water dried up and did not come back," he told the reporters, "I thought: 'Water is valuable, no one makes water and the population will not stop growing. What is going to happen? We are going to run out of water.'"

    With only some donkeys and a small team of hired workers, Antonio Vicente set about bringing back the forest to his land. What started out as a weekend hobby soon became a permanent way of life, and Antonio recalls often spending whole days and nights in his young jungle, surrounded by rats and foxes, and eating banana sandwiches for breakfast, lunch and dinner. Over the last 40 years, he has planted an estimated 50,000 trees on his 31-hectare land, which now make up a small but unique area of rainforest, and a haven for wildlife.

    As the forest grew, the water returned, and Antonio says that there are now over 20 water, sources on his land that were no longer there when he bought it. Then the animals started making a home there. Today, the forest is alive with the sounds of birds and insects living there, and more species are settling in every year.

    "There are toucans(巨嘴鸟), all kinds of birds, squirrels, lizards, and even the boars are returning," 83-year-old Vicente says, "If you ask me who my family are, I would say all this right here, each one of these that I planted from a seed."

    Three boys were enjoying themselves in their hometown of Bovina, Mississippi .However, their lives were turned upside down when they discovered the jawbone of a Mastodon (齿乳象).

    Brothers Shawn and Caid Sellers and cousin Michael Mahalitc found the prehistoric bone in a piece of earth that was recently plowed (犁、耕)."I thought it was a log," Caid said. "I tried to pick it up and it was really heavy and I saw teeth on it." The bone weighed about 50 pounds. They eventually got the bone to their home and fitted it in their tub (浴盆), but it took their collective strength, might and a golf cart, to carry the large Mastodon bone.

    "They didn't expect to find that," Michael's mom said. "Now that they have, I believe that they will be more aware of their surroundings and what they're digging up when they are digging and playing."

    "We've gotten a lot of petrified (石化的) wood and Civil War relics from the area and that's what I thought it was," the brothers' mother said. "This is our first set of teeth we've found. So we thought it was their imagination. We were quite surprised to see that it was not their imagination."

    They were exploring near the brothers' home. Lo and behold (真想不到), they saw what they thought resembled a fossil. It was the curator of paleontology (古生物负责人) of the Mississippi Museum of Natural Science, George Phillips, who first identified the bone as a "very mature individual."

    The Mastodon was a mammal who lived during the prehistoric times. They had long tusks and trunks, like elephants. They were clearly different from their modern-day counterparts, as well as woolly mammoths (猛犸).

    Unlike modern animal scientists, dinosaur scientists cannot sit on a hillside and use telescopes to watch dinosaurs in order to know how they lived and whether they were good parents. Instead, they have to search hard for information from dinosaurs' fossils(恐龙化石) because dinosaurs died out millions of years ago.

    It's very difficult for the scientists to reach an agreement because different results can be got from the same fossils. Many fossils of the same kind of dinosaurs have been dug out from one place. They might have formed when an entire group of dinosaurs got stuck(陷入)all at once. Or they might have been the result of dinosaurs getting stuck one after another over a course of a few centuries. Thus we can say that dinosaurs might have in the first case lived in big groups and in the second lived alone.

    Though there are two different results, dinosaur scientists now generally agree that at least some kinds of dinosaurs lived in big groups. “That's pretty much settled at this point.” Says Paul Sereno. A kind of dinosaurs called Sauropods left behind tracks in the western United States that appear to run north and south, suggesting that they even moved long distances together.

    As to whether dinosaurs cared for their young, dinosaur scientists have turned to the closest living relatives of dinosaurs, birds and crocodiles for possible models. Birds give a lot of care to their young, while crocodiles just help their young to the water. The discovered fossils of dinosaurs sitting on their eggs and staying with their young suggest the parents were taking care of their babies, but we still cannot say that all dinosaurs did the same.

    There is still a long way to go before the above questions could be answered. Dinosaur scientists will have to find more proof to reach an agreement.

    My husband and I had been married nearly twenty-two years when I acquired Stevens-Johnson syndrome, a disorder where my immune system (免疫系统) responded to a virus by producing painful blisters (水疱). Although my long-term evaluation was good, I, who had been so fiercely independent, rapidly became absolutely helpless.

    My husband, Scott, stepped up to the plate, taking care of kids and cooking dinners. He also became my personal caretaker, applying the medicine to all of my blisters because my hands couldn't do the job. Needless to say, I had negative emotions, bouncing from embarrassment to shame caused by total reliance on someone other than myself.

    At one point when I had mentally and physically hit bottoms I remember thinking that Scott must somehow love me more than I could ever love him. With my illness, he had become the stronger one, and I was the weaker one. And this disturbed me.

    I recovered from my illness, but I couldn't seem to recover from the thought that I loved my husband less than he loved me. This seeming distinction in our love continued to annoy me for the year following my illness.

    Then recently Scott and I went on a long bike ride. He's an experienced cyclist; I'm quite the green hand. At one point with a strong headwind and sharp pain building in my tired legs, I really thought I couldn't go any further. Seeing me struggle, Scott pulled in front of me and yelled over his shoulder, “Stay close behind me.” As I fell into the draft of his six-foot-three-inch frame and followed his steps, I discovered that my legs quit burning and I was able to catch my breath. My husband was pulling me along again. At this very moment I woke up to what I now believe: during these and other tough times, love has the opportunity to become stronger when one partner learns to lean on the other.

    I pray my husband will always be strong and healthy. But if he should ever become the struggling one, whether on a bike ride or with an illness, I trust I'll be ready to call out to him: stay close behind me — my turn to pull you along.

    Reading may be fundamental, but how the brain gives meaning to letters on a page has been a mystery. Two new studies fill in some details on how the brains of efficient readers handle words. One of the studies, published in the April 30 Neuron, suggests that a visual-processing area of the brain recognizes common words as whole units. Another study, published online April 27 in PLOSONE, makes it known that the brain operates two fast parallel systems for reading, linking visual recognition of words to speech.

    Maximilian Riesenhuber, a neuroscientist at Georgetown University in Washington, D.C., wanted to know whether the brain reads words letter by letter or recognizes words as whole objects. He and his colleagues showed sets of real words or nonsense(无意义的词语)words to volunteers undergoing fMRI scans. The words differed in only one letter, such as “farm” and “form” or “soat” and “poat”, or were completely different, such as “farm” and “coat” or “poat” and “hime”. The researchers were particularly interested in what happens in the visual word form area, or VWFA, an area on the left side of the brain just behind the ear that is involved in recognizing words.

    Riesenhuber and his colleagues found that neurons(神经元)in the VWFA respond strongly to changes in real words. Changing “farm” to “form”, for example, produced as great a change in activity as changing “farm” to” coat”, the team reports in Neuron. The area responded slowly to single-letter changes in made-up words.

    The data suggests that readers grasp real words as whole objects, rather than focusing on letters or letter combinations. And as a reader's exposure to a word increases, the brain comes to recognize the shape of the word. Meaning is passed on after recognition in the brain, Riesenhuber says.

    The researchers don't yet know how longer and less familiar words are recognized, or if the brain can be trained to recognize nonsense words as a unit.