知識類英語文摘
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多喝牛奶不一定對身體有益
Children who drink More milk do not necessarily develop healthier bones, researchers said on Monday in a report that stresses exercise and modest consumption of calcium-rich foods such as tofu and broccoli.
Appearing in the journal Pediatrics, the report drew its conclusions from previously published studies and was written by researchers from the Physicians Committee for Responsible Medicine, which advocates a strict vegetarian diet. "Under scientific scrutiny, the support for the milk myth crumbles. This analysis of 58 published studies shows that the evidence on which U.S. dairy intake recommendations are based is scant," said study author Dr. Amy Lanou in a statement.
Some earlier studies that extol dairy products as a calcium source have been funded at least in part by the dairy industry. The U.S. government has gradually increased recommendations for daily calcium intake, largely from dairy products, to between 800 and 1,300 milligrams to promote healthy bones and prevent osteoporosis. But the Physicians Committee’s report said boosting consumption of milk or other dairy products was not necessarily the best way to provide the minimal calcium intake of at least 400 milligrams per day. Dairy products provide 18 percent of the total energy and 25 percent of the total fat intake in the diets of American children, who are developing increasing rates of obesity, it said.
[簡譯]
據路透社3月7日報道，此前，美國政府不斷勸告人們，每天食用奶製品可以增加身體對鈣的攝取量;兒童如果每天能吸收800到1300毫克的鈣元素，就能提高骨骼健康、防止骨質疏鬆症。然而，根據這份發表在《兒科學》期刊上的研究報告，增加牛奶和其它奶製品的食用量不一定是滿足身體每天至少400毫克鈣需求量的最好方式。
這份報告的作者是華盛頓醫學醫師委員會的一些研?a href="">咳嗽薄Ｋ侵匭卵芯苛?7篇關於(7歲以上兒童)鈣的攝取對骨骼密度影響的論文，發現27篇論文不支持喝更多牛奶能吸收更多鈣的說法。有幾篇論文認爲，鍛鍊比提高鈣的攝取量更有助於強化骨骼。但是，目前缺乏關於7歲以下兒童攝取鈣的效果的數據。
睡眠質量影響單詞記憶力
Even facts "forgotten" by people during a busy day may be retrieved if this is followed by a good night’s sleep.
Researchers from the University of Chicago asked volunteers to remember simple words.
Many found their memories letting them down towards the end of the day, but the following morning, those who had slept well could recall much more.
Researchers, writing in the journal Nature, said the brain could "rescue" lost memories during the night.
When the brain is first asked to remember something, that memory is laid down in an "unstable" state, meaning that it is possible that it could be lost.
At some point, the brain consolidates those it deems important into a "stable", more permanent state.
However, the Chicago researchers suggested that it was possible for a "stable" memory to be made "unstable" again.
This would mean that memories could be modified then filed away again in the face of new experiences.
The 12 volunteers tested in the experiment were played words created through a speech synthesizer which were purposely difficult to understand.
Initially, the written version of the word was available, but afterwards the volunteers were asked to identify the word from the audio version only.
Tests revealed that the ability to recall the right word tended to tail off as the day ended.
However, when the volunteers were retested after a good night’s sleep, they were able to recall some words that they had "forgotten" the previous evening.
Dr Daniel, one of the study authors, said: "Sleep consolidates memories, protecting them against subsequent interference or decay.
"Sleep also appears to ’recover’ or restore memories."
He said: "If performance is reduced by decay, sleep might actively recover what has been lost."
Dr Karim Nader, from the Department of Psychology in McGill University in Montreal, said: "Memory research is undergoing a transformation - no longer is memory thought to be a hard-wiring of the brain, instead it seems to be a process of storage and re-storage.
"Sleep helps some memories ’mature’ and also prunes out unimportant memories."
如果晚上睡個好覺，即使白天由於忙碌而“遺忘”的一些事情也可以重新回憶起來。
芝加哥大學的研究者們要求志願者們記住一些簡單的單詞。
到了晚上，許多人對自己的記憶力都感到失望。但是第二天早晨，那些睡得好的人能回想起來更多的單詞。
研究者們在《自然》雜誌發表論文說：大腦可以在晚間“修復”失去的記憶。
當大腦最初被要求記住一些東西時，那段記憶處於一種“不穩定的”狀態，這意味着它很可能會丟失。
在有些時刻，大腦會將那些它認爲重要的記憶強化爲“穩定的”狀態，也就是更持久的狀態。
然而，芝加哥大學的研究者們提示說“穩定的”記憶也可能會轉變爲“不穩定的”。
這就意味着當遇到新的情況時，記憶可能會被修改，隨後重新排列。
參加試驗的12名志願者收聽了通過語音合成器產生的特別難懂的單詞。
剛開始還給志願者提供單詞腳本，但是後來就要求他們僅僅通過聲音來辨別單詞。
實驗顯示：一天快結束的時候，準確回憶單詞的能力隨之減弱。
然而，當志願者們睡了個好覺過後再次接受測試的時候，他們能夠回憶起一些他們前一天晚上已經"遺忘"的單詞。
這篇論文的一位作者丹尼爾博士說：“睡眠可以鞏固記憶，防止它們隨後受到干擾或衰減。
“睡眠看來也可以恢復記憶。”
他說：“如果記憶功能因爲衰減而降低，睡眠可以有效的恢復丟失的記憶。”
蒙特利爾市麥基爾大學心理學系的卡里姆·納德博士說：“記憶力研究正在轉型——記憶不再被認爲是大腦的硬件，而似乎是一個儲存和再儲存的過程。
“睡眠使某些記憶變得‘成熟’，同時也刪掉了那些不重要的記憶。”
