作者：素衣 来源：新东方在线 2016-07-24 19:31
Don’t count on dung
Conservationists (自然保护主义者) may be miscalculating the numbers of the threatened animals such as elephants, say African and American researchers. The error occurs because of a flaw in the way they estimate animal numbers from the piles of dung (粪) the creatures leave behind.
The mistake could lead researchers to think that there are twice as many elephants as there really are in some regions, according to Andrew Plumptre of the Wildlife Conservation Society (WCS) in New York.
Biologist Katy Payne of Cornell University in Ithaca, New York, agrees. "We really need to know elephant numbers and the evidence that we have is quite indirect," says Payne, who electronically tracks elephants.
Counting elephants from planes is impossible in the vast rainforests of Central Africa. So researchers often estimate elephant numbers by counting dung piles in a given area. They also need to know the rate at which dung decays: Because it's extremely difficult to determine these rates, however, researchers counting elephants in one region tend to rely on standard decay rates established elsewhere.
But researchers at the WCS have found that this decay rate varies from region to region depending on the climate and environment. Using the wrong values can lead the census astray (离开正道), says Plumptre.
He and his colleague Anthony Chifu Nchanji studied decaying elephant dung in the forests of Cameroon. They found that the dung decayed between 55 and 65 per cent
more slowly than the dung in the rainforests of neighbouring Gabon. If researchers use decay rates from Gabon to count elephants in Cameroon, they would probably find more elephants than are actually around.
This could mean estimates in Cameroon are at least twice as high as those derived from decay rates calculated locally, says Plumptre. "However accurate your dung density estimate might be, the decay rate can severely affect the result."
Plumptre also says that the dung-pile census should be carried out over a region similar in size to an elephant's natural range. The usual technique of monitoring only small, protected areas distorts numbers because elephants move in and out of these regions, he says. "If the elephant population increases within the protected area, you can not determine whether it is a real increase or whether it is due to elephants moving in because they are being poached (入侵偷猎) outside."
Plumptre says that similar problems may also affect other animal census studies that rely on indirect evidence such as nests, tracks or burrows (地洞).
1 The word "threatened" in the first sentence of the first paragraph could be best replaced by
2 Why do researchers estimate elephant numbers in an area by counting dung piles?
A Because elephants are difficult to catch.
B Because it is not possible to count elephants from a plane.
C Because it is not possible to keep track of elephants.
D Because elephants are shy animals.
3 Piles of dung can't be relied upon when it comes to estimating elephant numbers because
A they are different in size.
B they scatter all over the region.
C they are different in decay rate.
D they are different in quality.
4 According to Plumptre, the region over which a dung-pile census is carried out should be
A small enough.
B well protected.
C carefully monitored.
D large enough.
5 The first word "He" in paragraph 6 refers to
A Andrew Plumptre.
B Katy Payne.
C Anthony Chifu Nchanji.
D the writer of the article.
Black Holes Trigger Stars to Self-Destruct
Scientists have long understood that supermassive black holes weighing millions or billions of suns can tear apart stars that come too close. The black hotels gravity pulls harder on the nearest part of the star, an imbalance that pulls the star apart over a period of minutes or hours, once it gets close enough.
Scientists say this Uneven pulling is not the only hazard facing the star. The strain of these unbalanced forces can also trigger a nuclear explosion powerful enough to destroy the star from within. Matthieu Brassart and Jean-Pierre Luminet of the Observatoire de Paris in Meudon, France, carried out computer simulations of the final moments of such an unfortunate star's life,as it veered towards a supermassive black hole.
When the star gets close enough, the uneven forces flatten it into a pancake shape. Some previous studies had suggested this flattening would increase the density and temperature inside the star enough to trigger intense nuclear reactions that would tear it apart. But other studies had suggested that the picture would be complicated by shock waves generated during the flattening process and that no nuclear explosion should occur.
The new simulations investigated the effects of shock waves in detail,and found that even when their effects are included,the conditions favor a nuclear explosion. "There will be an explosion of the star-it will be completely destroyed," Brassart says. Although the explosion obliterates the star, it saves some of the star's matter from being devoured by the black hole. The explosion is powerful enough to hurl much of the star's matter out of the black hole's reach, he says.
The devouring of stars by black holes may already have been observed, although at a much later stage. It is thought that several months after the event that rips the star apart,its matter starts swirling into the hole itself. It heats up as it does so, releasing ultraviolet light and X-rays.
If stars disrupted near black holes really do explode, then they could in principle allow these events to be detected at a much earlier stage, says Jules Hatpern of Columbia University in New York, US. "It may make it possible to see the disruption of that star immediately if it gets hot enough," he says.
Brassart agrees. "Perhaps it can be observed in the X-rays and gamma rays, but it's something that needs to be more studied," he says. Supernova researcher Chris Fryer of the Los Alamos National Laboratory in Los Alamos, New Mexico, US, says the deaths of these stars are difficult to simulate, and he is not sure whether the researchers have proven their case that they explode in the process.
36.【题干】Something destructive could happen to a star that gets too close to a black hole. Which of the following destructive statements is NOT mentioned in the passage?
A. The black hole could tear apart the star.
B. The black hole could trigger a nuclear explosion in the star.
C. The black hole could dwindle its size considerably.
D. The black hole could devour the star.
37.【题干】According to the third paragraph, researchers differed from each other in the problem of_____
A. whether nuclear reaction would occur.
B. whether the stars would increase its density and temperature.
C. whether shock waves would occur.
D. whether the uneven forces would flatten the stars.
38.【题干】According to the fourth paragraph, which of the following is NOT true?
A. No nuclear explosion would be triggered inside the star.
B. The star would be destroyed completely.
C. Much of the star's matter thrown by the explosion would be beyond the black hole's reach.
D. The black hole would completely devour the star.
39.【题干】What will happen several months after the explosion of the star?
A. The star's matter will move further away from by the black hole.
B. The black hole’s matter will heat up.
C. The torn star's matter will swirl into the black hole.
D. The black hole's matter will release ultraviolet light and X-rays.
40.【题干】According to the context, the word "disruption" in Paragraph 6 means_____
B. "Tearing apart."
Sports star Yao Ming 【运动明星姚明】
If Yao Ming is not the biggest sports star in the world, he is almost certainly the tallest. At 2.26m, he is the tallest player in the National Basketball Association (NBA) and holds the record as the most towering Olympian ever to compete in the Games.
But what really stands out about the giant center is his celebrity(名气). Few, if any, Chinese athletes are as well-known as Yao around the world. People across the globe are fascinated with Yao, not only for his basketball prowess(杰出的才能)also for being a symbol of international commerce.
When Yao joined the Houston Rockets as the No.1 pick in the 2002 NBA draft(选抜)， he was the first international player ever to be selected first. His assets on the court are clear enough—no NBA player of his size has ever possessed his mobility, so he is a handful(难对付的人)for opponents on either end of the court. But what makes Yao invaluable to the Rockets organization is his role as a global citizen and as a bridge to millions of potential basketball fans in China.
When it was announced in February that Yao would miss the rest of the NBA season and possibly the Olympics with a stress fracture(骨折)in his left foot, a collective shudder(震动)spread across China. After considerable debate and discussion, Yao opted to get his foot surgically treated in an operation that placed several tiny screws across the bone, to offer his overburdened foot more support. The surgery was a success, and though the estimated four-month recovery period will leave him little time to prepare with Team China, Yao has vowed to be ready for the Beijing Olympics.
Yao wrapped up a 10-day trip to China, where he underwent a series of traditional Chinese medicine (TCM) treatments, hoping to accelerate his recovery process Western experts are generally skeptical of TCM's benefits although new research from the University of Rochester suggests that a certain compound derived from shellfish may indeed stimulate bone repair.
"There is no reason to dismiss TCM," Yao told a press conference in Beijing." It's been used in our country for thousands of years. I don't think that it's short on science."
36.【题干】The word "towering" in Paragraph 1 means_____
37.【题干】Opponents find it very difficult to control Yao Ming because of his_____
38.【题干】Yao Ming had to undergo a series of TCM treatments because_____
A. his right foot had been hurting.
B. he wanted to make a more rapid recovery.
C. the surgical operation had been a failure.
D. he couldn't afford all the medical expenses.
39.【题干】Which statement about Yao Ming is NOT true?
A. He missed the Athens Olympics.
B. He is an NBA player.
C. He fractured his left foot.
D. He is an international figure.
40.【题干】In general, the Western experts' attitude towards TCM is_____.