题目内容
For many years, people believed that the brain, like the body, rested during sleep. After all, we are rendered unconscious by sleep. Perhaps, it was thought, the brain just needs to stop thinking for a few hours every day. Wrong. During sleep, our brain -- the organ that directs us to sleep -- is itself extraordinarily active. And much of that activity helps the brain to learn, to remember and to make connections. It wasn’t so long ago that the regretful joke in research circles was that everyone knew sleep had something to do with memory -- except for the people who study sleep and the people who study memory. Then, in 1994, Israeli researchers reported that the average performance for a group of people on a memory test improved when the test was repeated after a break of many hours -- during which some subjects slept and others did not. In 2000, a Harvard team demonstrated that this improvement occurred only during sleep. There are several different types of memory -- including declarative (fact-based information), episodic (events from your life) and procedural (how to do something) -- and researchers have designed ways to test each of them. In almost every case, whether the test involves remembering pairs of words, tapping numbered keys in a certain order or figuring out the rules in a weather- prediction game, "sleeping on it" after first learning the task improves performance. It’s as if our brains squeeze in some extra practice time while we’re asleep. This isn’t to say that we can’t form memories when we’re awake. If someone tells you his name, you don’t need to fall asleep to remember it. But sleep will make it more likely that you do. Sleep-deprivation experiments have shown that a tired brain has a difficult time capturing memories of all sorts. Interestingly, sleep deprivation is more likely to cause us to forget information associated with positive emotion than information linked to negative emotion. This could explain, at least in part, why sleep deprivation can trigger depression in some people: memories stained with negative emotions are more likely than positive ones to "stick" in the sleep-deprived brain. Sleep also seems to be the time when the brain’s two memory systems -- the hippocampus (海马体) and the neocortex (新皮质) -- "talk" with one other. Experiences that become memories are laid down first in the hippocampus, eliminating whatever is underneath. If a memory is to be retained, it must be shipped from the hippocampus to a place where it will endure -- the neocortex, the wrinkled outer layer of the brain where higher thinking takes place. Unlike the hippocampus, the neocortex is a master at weaving the old with the new. And partly because it keeps incoming information at bay, sleep is the best time for the "undistracted" hippocampus to shuttle memories to the neocortex, and for the neocortex to link them to related memories. A temporary memory won’t become an enduring one unless ______.
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Sugarless yoghurt (酸奶) could help beat bad breath, tooth decay and gum disease, say scientists. Japanese researchers found eating the yoghurt (62) levels of hydrogen sulphide (硫化氢) -- a major (63) of bad breath -- in 80% of volunteers. The (64) are active bacteria in yoghurt. Details were (65) at a meeting of the International Association for Dental Research. A(n) (66) of 24 volunteers who participated in the study were given strict instructions (67) oral health, diet and medicine taking. They spent two weeks (68) yoghurts and similar foods, like cheese. Researchers then (39) bacteria levels and odor-causing compounds, (70) hydrogen-sulphide. The volunteers then ate 90 grams of yoghurt a day for six weeks. At the end of the study, researchers took (71) again. They found hydrogen sulphide levels (72) in 80% of participants. Dr. Nigel Carter, chief executive of the British Dental Health Foundation, said, "The foundation has long been (73) people’s attention to sugar-free yoghurts as a healthy snack, so it is pleasing to hear that it may have oral health benefits we were previously (74) of." "Although this research is still in the early stages there is no (75) that sugar-free yoghurts provide a much healthier (76) to sweets and chocolate, and we would encourage snackers to (77) them into their diet." (78) , Dr. Carter stressed that the best way to beat bad breath was by (79) a good oral health routine. This involves brushing twice-a-day with fluoride (氟化物) toothpaste, cutting (80) on the frequency of sugary snacks and drinks and visiting a dentist (81) .
The Future of Television: What’s on Next Bosses in the television industry have been keeping a nervous eye on two Scandinavians (斯堪的纳维亚人) with a reputation for causing trouble. In recent years Niklas Zennstrom, a Swede, and Janus Friis, a Dane, have frightened the music industry by inventing KaZaA, a "peer- to-peer" (P2P) file-sharing program that was widely used to download music without paying for it. Then they horrified the mighty telecoms industry by inventing Skype, another P2P program, which lets Internet users make free telephone calls between computers, and very cheap calls to ordinary phones. Their next move was to found yet another start-up -- this time, one that threatened to devastate (毁坏) the television industry. It may do the opposite, as it turns out. The new service, called Joost and now in advanced testing, is based on P2P software that runs on people’s computers, just like Skype and KaZaA. And it does indeed promise to transform the experience of watching television by combining what people like about old-fashioned TV with the exciting possibilities of the Internet. "But unlike KaZaA and Skype," says Fredrik de Wahl, a Swede whom Mr. Zennstrom and Friis have hired as Joost’s boss, "Joost does not disrupt the industry that it is entering. Instead, rather than undercutting television networks and producers, Joost might, as it were, give them new juice." That is because Mr. de Wahl and his Joost team, working mostly in the Netherlands, have bravely ignored the totems (图腾) of the Internet-video boom. Chief among these fashions is letting users upload anything they want to a video service -- which might include clips of themselves doing odd things ("user-generated content") or, more questionably, videos pirated from other sources. The celebrated example of this approach is YouTube, which is now part of Google, the leader in Internet search. Its big problem, however, is that it can be illegal (if copyright is violated) and terribly hard to turn into a business. On February 2nd Viacom, an American media giant, became the latest company to demand that YouTube remove copyright-infringing (侵犯版权的) clips from its website. YouTube has struck deals with some media firms, including NBC and CBS, to allow their material to appear on its site, and had been trying to thrash out a similar agreement with Viacom. Many observers regard Viacom’s move as a negotiating tactic. But whether YouTube can make money is unclear. Last month Chad Hurley, YouTube’s chief executive, sketched out plans for generating advertising revenues and sharing them with content providers, but so far his firm has none to speak of. The Innovation of Joost Joost is also ignoring the two business models seen as the most respectable alternatives to advertising. One is to make users pay for each television show or film they download, but then to let them keep it. This is the tack chosen by Apple, an electronics firm that sells videos on iTunes, its popular online store; by Amazon, the largest online retailer; and by Wal-Mart, the largest traditional retailer, which launched a video-download service this week. The other approach is to let users subscribe to what is, in effect, an all-you-can-eat buffet of videos, and then to "stream" video to their computers without leaving a permanent copy. This is the approach taken by, for instance, Netflix, a Californian firm that mostly delivers DVDs to its subscribers by post, but now also streams films. The reason that Joost is ignoring all of these methods, says Mr. de Wahl, is that none has much to do with the experience of simply watching TV, which most people enjoy. "Unlike the download or streaming approaches," he says, "TV is not about buying today what you want to watch tomorrow. It’s about turning it on and watching." And in contrast to the "lean-forward" context of "snacking" on a YouTube clip in one’s cubicle while the boss has stepped out, TV is a longer and more relaxed "lean-backward" experience. Hence Joost’s most shocking innovation, which is not to change the practices that TV adopted decades ago. It will be free, with advertising breaks -- no more than three minutes per hour -- either before, during or after a show, depending on the market. "Americans," says Mr. de Wahl, "are more tolerant of interruptions." Joost has "channels", like ordinary TV, but these are now playlists of videos that start whenever it is convenient to the viewer. Viewers can import their instant-messaging buddy lists and chat online with friends while watching the same program. For advertisers, such engagement is worth something, because the activity proves that somebody is watching, rather than being asleep or out of the room. Combined with other information, such as the computer’s IP address and hence its location, advertisers will be able to target their spots much more accurately -- all "Desperate Housewives" fans in a particular neighborhood, for example -- and thus ought to pay a premium. The Combination of Television and the Internet The thing that is missing in this new vision of television, however, is the set itself. Beaming video from a computer to a television is possible: Apple and other firms are starting to sell the necessary gadgets. But until it becomes much easier to connect televisions to the Internet, big media companies are likely to "wait and see" before committing to Joost, says Jeremy Allaire, the boss of Brightcove, a rival Internet-video firm based in Massachusetts. In the meantime, Mr. Allaire thinks, media firms are mainly interested in building their own brands, so Brightcove provides content owners with technology to show television on their own websites, syndicate their shows to other websites, track audiences and collect advertising revenue. There is, in short, no consensus about the best way to combine television with the Internet. Instead, there are a variety of experiments, of which Joost is the latest example and YouTube the best-known. But with telephony, the Internet is unpicking (拆开) service delivery from network ownership. Joost, YouTube, iTunes and Netflix do not need their own networks to supply their video services: they can rely on fast Internet links provided by others. According to iSuppli, a market-research firm, Internet downloads will claim more than one- third of the market for on-demand video by 2010. So just as Internet telephony has been bad for traditional phone companies, this "Internet bypass" could be bad for the "on demand" video services being offered by cable-TV and telecoms firms over their networks. But by bringing television to more screens, this could provide new models for program-makers to finance their productions and offer advertisers new ways to reach constraints. And so Joost and rival services could end up rejuvenating (使变得年轻) the 75-year-old medium. Why are bosses in the television industry nervous with Zennstrom and Friis
与细菌核蛋白体的50S亚基结合，抑制细菌蛋白质的合成，首选于军团菌病的是
Sugarless yoghurt (酸奶) could help beat bad breath, tooth decay and gum disease, say scientists. Japanese researchers found eating the yoghurt (62) levels of hydrogen sulphide (硫化氢) -- a major (63) of bad breath -- in 80% of volunteers. The (64) are active bacteria in yoghurt. Details were (65) at a meeting of the International Association for Dental Research. A(n) (66) of 24 volunteers who participated in the study were given strict instructions (67) oral health, diet and medicine taking. They spent two weeks (68) yoghurts and similar foods, like cheese. Researchers then (39) bacteria levels and odor-causing compounds, (70) hydrogen-sulphide. The volunteers then ate 90 grams of yoghurt a day for six weeks. At the end of the study, researchers took (71) again. They found hydrogen sulphide levels (72) in 80% of participants. Dr. Nigel Carter, chief executive of the British Dental Health Foundation, said, "The foundation has long been (73) people’s attention to sugar-free yoghurts as a healthy snack, so it is pleasing to hear that it may have oral health benefits we were previously (74) of." "Although this research is still in the early stages there is no (75) that sugar-free yoghurts provide a much healthier (76) to sweets and chocolate, and we would encourage snackers to (77) them into their diet." (78) , Dr. Carter stressed that the best way to beat bad breath was by (79) a good oral health routine. This involves brushing twice-a-day with fluoride (氟化物) toothpaste, cutting (80) on the frequency of sugary snacks and drinks and visiting a dentist (81) .
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