1、大学英语六级改革适用（阅读）模拟试卷 117及答案与解析 Section B 0 How Exercise Could Lead to a Better Brain AThe value of mental-training games may be speculative, as Dan Hurley writes in his article on the quest to make ourselves smarter, but there is another, easy-to-achieve, scientifically proven way to make yourself sma
2、rter. Go for a walk or a swim. For more than a decade, neuroscientists and physiologists have been gathering evidence of the beneficial relationship between exercise and brainpower. But the newest findings make it clear that this isnt just a relationship; it is the relationship. Using sophisticated
3、technologies to examine the workings of individual neurons(神经元 ) and the makeup of brain matter itself scientists in just the past few months have discovered that exercise appears to build a brain that resists physical shrinkage and enhance cognitive flexibility. Exercise, the latest neuroscience su
4、ggests, does more to improve thinking than thinking does. BThe most persuasive evidence comes from several new studies of lab animals living in busy, exciting cages. It has long been known that so-called “enriched“ environmentshomes filled with toys and engaging, novel tasks lead to improvements in
5、the brainpower of lab animals. In most instances, such environmental enrichment also includes a running wheel, because mice and rats generally enjoy running. Until recently, there was little research done to tease out the particular effects of running versus those of playing with new toys or engagin
6、g the mind in other ways that dont increase the heart rate. CSo, last year a team of researchers led by Justin S. Rhodes, a psychology professor at the Beckman Institute for Advanced Science and Technology at the University of Illinois, gathered four groups of mice and set them into four distinct li
7、ving arrangements. One group lived in a world of sensual and taste plenty, dining on nuts, fruits and cheeses, their food occasionally dusted with cinnamon(肉桂 ), all of it washed down with variously flavored waters. Their “beds“ were small colorful plastic dome-shaped houses occupying one corner of
8、the cage. Neon-hued(霓虹色的 )balls, plastic tunnels, chewable blocks, mirrors and seesaws(跷跷板 )filled other parts of the cage. Group 2 had access to all of these pleasures, plus they had small disc-shaped running wheels in their cages. A third groups cages held no decorations, and they received standar
9、d, dull food. And the fourth groups homes contained the running wheels but no other toys or treats. DAll the animals completed a series of cognitive tests at the start of the study and were injected with a substance that allows scientists to track changes in their brain structures. Then they ran, pl
10、ayed or, if their environment was unenriched, stayed lazily in their cages for several months. Afterward, Rhodess team put the mioe through the same cognitive tests and examined brain tissues. It turned out that the toys and tastes, no matter how stimulating, had not improved the animals brains. E“
11、Only one thing had mattered,“ Rhodes says, “ and thats whether they had a running wheel. “ Animals that exercised, whether or not they had any other enrichments in their cages, had healthier brains and performed significantly better on cognitive tests than the other mice. Animals that didnt run, no
12、matter how enriched their world was otherwise, did not improve their brainpower in the complex, lasting ways that Rhodess team was studying. “ They loved the toys,“ Rhodes says, and the mice rarely ventured into the empty, quieter portions of their cages. But unless they also exercised, they did not
13、 become smarter. FWhy would exercise build brainpower in ways that thinking might not? The brain, like all muscles and organs, is a tissue, and its function declines with underuse and age. Beginning in our late 20s, most of us will lose about 1 percent annually of the volume of the hippocampus(海马体 )
14、, a key portion of the brain related to memory and certain types of learning. GExercise though seems to slow or reverse the brains physical decay, much as it does with muscles. Although scientists thought until recently that humans were born with a certain number of brain cells and would never gener
15、ate more, they now know better. In the 1990s, using a technique that marks newborn cells, researchers determined during examining the dead bodies that adult human brains contained quite a few new neurons. Fresh cells were especially prevalent in the hippocampus, indicating that neurogenesis(神经形成 ) o
16、r the creation of new brain cells was primarily occurring there. Even more encouraging, scientists found that exercise jump-starts neurogenesis. Mice and rats that ran for a few weeks generally had about twice as many new neurons in their hippocampi as motionless animals. Their brains, like other mu
17、scles, were bulking up. HBut it was the indescribable effect that exercise had on the functioning of the newly formed neurons that was most startling. Brain cells can improve intellect only if they join the existing neural network, and many do not, instead existing aimlessly in the brain for a while
18、 before dying. One way to pull neurons into the network, however, is to learn something. In a 2007 study, new brain cells in mice became looped into the animals neural networks if the mice learned to navigate(导航 )a water maze(迷宫 ), a task that is cognitively but not physically taxing. But these brai
19、n cells were very limited in what they could do. When the researchers studied brain activity afterward, they found that the newly wired cells fired only when the animals navigated the maze again, not when they practiced other cognitive tasks. The learning encoded in those cells did not transfer to o
20、ther types of rodent(啮齿动物 )thinking. IExercise, on the other hand, seems to make neurons move quickly and easily. When researchers in a separate study had mice run, the animals brains readily wired many new neurons into the neural network. But those neurons didnt fire later only during running. They
21、 also lighted up when the animals practiced cognitive skills, like exploring unfamiliar environments. In the mice, running, unlike learning, had created brain cells that could multitask. JJust how exercise remakes minds on a molecular level is not yet fully understood , but research suggests that ex
22、ercise prompts increases in something called brain-derived neurotropic factor(脑源性神经营养因子 ), or B. D. N. F. , a substance that strengthens cells and axons(轴突 ), strengthens the connections among neurons and sparks neurogenesis. Scientists cant directly study similar effects in human brains, but they h
23、ave found that after physical exercise, most people display higher B. D. N. F. levels in their bloodstreams. KFew if any researchers think that more B. D. N. F. explains all of the brain changes associated with exercise. The full process almost certainly involves multiple complex biochemical and gen
24、etic cascades(级联反应 ). A recent study of the brains of elderly mice, for instance, found 117 genes that were expressed differently in the brains of animals that began a program of running, compared with those that remained motionless, and the scientists were looking at only a small portion of the man
25、y genes that might be expressed differently in the brain by exercise. LWhether any type of exercise will produce these desirable effects is another unanswered and intriguing issue. “ Its not clear if the activity has to be endurance exercise,“ says the psychologist and neuroscientist Arthur F. Krame
26、r, director of the Beckman Institute at the University of Illinois and a celebrated expert on exercise and the brain. A limited number of studies in the past several years have found cognitive benefits among older people who lifted weights for a year and did not otherwise exercise. But most studies
27、to date, and all animal experiments, have involved running or other aerobic(有氧的 )activities. MWhatever the activity, though, an emerging message from the most recent science is that exercise neednt be exhausting to be effective for the brain. When a group of 120 older men and women were assigned to
28、walking or stretching programs for a major 2011 study, the walkers wound up with larger hippocampi after a year. Meanwhile, the stretchers lost volume to normal shrinkage. The walkers also displayed higher levels of B. D. N. F. in their bloodstreams than the stretching group and performed better on
29、cognitive tests. NIn effect, the researchers concluded, the walkers had regained two years or more of hippocampal youth. Sixty-five-year-olds had achieved the brains of 63-year-olds simply by walking, which is encouraging news for anyone worried that what were all facing as we move into our later ye
30、ars is a life of slow mental decline. 1 Until recently, the scientists thought that the number of the brain cells was fixed. 2 By walking, the walkers could make hippocampus become younger for two years or more. 3 According to the latest neuroscience, physical training is more important to improve t
31、hinking. 4 Scientists have found higher levels of B. D. N. F. in the bloodstreams after people doing exercises. 5 The research of Justin S. Rhodes showed that the mices brains were improved only by running wheels. 6 Besides learning, hippocampus also has something to do with the memory. 7 Compared w
32、ith the stretchers, the walkers passed cognitive tests with better performance. 8 The 2007 study showed the water maze navigation by mice could connect their new brain cells to the neural networks. 9 In Justin S. Rhodes research, the third group of mice had standard foods. 10 According to Arthur F.
33、Kramer, its uncertain whether the effective brain activity has to be endurance exercise. 10 Nine Most Amazing Google Search Tricks ASearching on Google can be a magical experience once you find out how to make your search queries efficient. By making efficient I mean using some tricks or the cheat s
34、heet provided by Google itself to quickly find what you actually require. Having being hooked onto Google for a long time now, I have come across some amazing search tricks which can change the way you look at Google today. In this article I will list down the search tricks which I use quite frequen
35、tly. Be it finding time, meanings or watching the cricket score, searching PDPs, with Google as the search engine life cannot be simpler. Here are the nine most amazing Google Search tricks; Different types of files at your will BHow many times would you have asked for materials(PDF, PPT, DOG)for a
36、particular topic from a friend? Its almost everyday that we might have the necessity to ask them either for knowledge, preparing a presentation, white-paper or for case studies. Such times it mostly difficult to look out what to exactly search for because most of the times you dont know about the to
37、pic at hand. But this petty keyword unleashes its lethal power at such occasions. Lets say I want to implement a case study on SOA which means I have to read a lot of information for SOA. So I just have to find materials which might have already been uploaded on the web in the form of PDFs, DOCs or
38、PPTs. These materials can be easily obtained by doing a search for: * PDF service oriented architecture file-type; pdf * PPT service oriented architecture file-type; ppt * DOC service oriented architecture file-type; doc Scholarly search CIf you want some authenticity of the materials then it would
39、be better to find the materials from educational institutes or universities. For this use the Google scholar search. But suppose you dont like to switch to Google scholar search you can add the same query with an additional parameter to the normal Google search box. * service oriented architecture f
40、ile-type: pdf site: edu Meanings of any word in an instant DNow you do not have to carry a dictionary or install a dictionary software just for the purpose of finding out a meaning of a word. With the wealth of information in Googles hands, its a piece of cake to find out the meaning of the word. Ju
41、st use the define; keyword. The meaning would of course be displayed but also a set of other links which might have an alternative definition are also given out with the link to read more about it. * define; bureaucracy EYou would argue here that, a dictionary gives out more information than this. B
42、ut what about words that dont actually fall within the vocabulary. Suppose you want to know what SOA(Service Oriented Architecture)is then you would have no choice. Google Search comes to your rescue in this case, * Abbreviations define; SOA * Jargons(术语 ) define; Web 2.0 * SMS language define; LOL
43、Find the time of any location FMany of us might be probably working for client which are based at different locations. And communication has to be carried out frequently in such cases. But before a communication you have to know which time zone the location is falling into otherwise you would be cau
44、sing a disturbance. I have seen people installing time zone software for showing the time of the location they would be calling to. But with Google at your hands you dont have to install any software. It would be just simple to use a query for finding the current time such as, * time new york psst.
45、look closely the time on the little clock graphic. It also shows the perfect time! Weather at your fingertips GI had been to GOA for a Christmas vacation in the last week of December. But I made a mistake of not finding out the temperature of GOA before leaving. Had I known that it is hot even in th
46、e winter I would not have made the mistake of carrying additional luggage consisting of blankets and jackets. If you are thinking to visit a place it is useful to know what the temperature of the place is before hand, it can make efficient packing. Google helps you here too. Just use this query with
47、out asking anybody or waiting for the news to make a weather report. I wish I had thought of this! * goa weather Google does live commentary too! HIndians are cricket fanatics. But its amusing to see the organizations here trying to put together tactics to devoid cricket lovers from wasting time to
48、watch the cricket scores instead of doing their work. What I think they fail to understand is that by blocking the live cricket scoring sites they are actually making the employees more curios and provoking them to hunt for proxy networks or listen to the radio or chat with their friends elsewhere.
49、Jokes apart, you actually dont need proxy networks to view the live cricket scores if you at least have access to Google. If you want to find the latest info about all the cricket matches then just type, * cricket But if you want to find out only about a particular match then use only the names of the two playing nations, * India Australia Calculate with your browser IEvery OS has a calculator inbuilt but when the browser is the thing which is constantly open when bother to open up a calcu
