VOA慢速英语2011--Looking Inside the Brains of 'Lucid Dreamers'

SCIENCE IN THE NEWS - Looking Inside the Brains of 'Lucid¹ Dreamers'

 

FAITH LAPIDUS: This is SCIENCE IN THE NEWS in VOA Special English. I’m Faith Lapidus.

BOB DOUGHTY²: And I’m Bob Doughty. Today, we tell how warmer weather in the Arctic could speed up climate change around the world. We offer two possible explanations for a magnetic field on the moon. And we tell about a new study of dreams.

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FAITH LAPIDUS: As Earth warms, the higher temperatures are melting ice in places like the North Pole. But ice is not all that is changing. The increased warmth is also melting permafrost -- frozen ground that stays at or below zero degrees Celsius³ for an extended period.

A new American report says melting permafrost can free microbes that produce methane⁴ gas. Methane is considered more threatening to the environment than carbon dioxide.

Janet Jansson of the Lawrence Berkeley National Laboratory in California led the study. She worked with researchers from the United States Department of Energy, the Joint⁵ Genome Institute and the Earth Sciences Division within the Berkeley lab.

An undated photo from the University of Florida shows erosion in the Noatak National Preserve in Alaska from increased thawing6 of permafrost

BOB DOUGHTY: Her team studied microbes in soil from a forest of black spruce trees in the state of Alaska. A report describing the study was published last month in the journal Nature.

The researchers say one gram of the soil could contain thousands of different kinds of microbes and billions of cells. They say these organisms had never before been cultured in a laboratory.

JANET JANSSON: “So more than ninety percent of those bacteria and other microorganisms in permafrost, we had no idea what they were.”

FAITH LAPIDUS: Janet Jansson says it was hard to study the microbes without laboratory examination. To deal with that problem, the researchers removed the DNA⁷ from pieces of the permafrost. DNA is the genetic⁸ material of which all living things are formed.

Professor Jansson says the DNA provided information about the identities of the microorganisms. It also showed all the biological and chemical reactions that the microbes experienced in the permafrost. That was true both before and after the permafrost melted.

The researchers found single-celled organisms that produce methane and eat organic material in the soil. Ms. Jansson says they also found microbes that eat methane in thawed⁹ permafrost.

JANET JANSSON: “Some of the methane was being consumed by other microorganisms in the samples, and they in turn would release CO2, carbon dioxide.”

BOB DOUGHTY: The researchers inspected soil samples from the upper permafrost layer. This level melts and refreezes with the seasons. The scientists also studied permanently¹⁰ frozen permafrost. In the permanently frozen material, some of the microbes had been trapped for thousands of years.

Janet Jansson says the two soils were very different at first. But she says those differences decreased after they melted.

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BOB DOUGHTY: In the nineteen sixties, American astronauts began returning to Earth with rocks they had collected from the moon. Scientists who examined the rocks were surprised to discover that some of them were magnetic. And they were surprised by how the rocks had been magnetized. It appeared they had cooled over time near a magnetic field.

FAITH LAPIDUS: The idea of a magnetic field on the moon has puzzled scientists ever since. On Earth, a magnetic field is produced by the great heat from the planet’s inner core. The heat makes the liquid iron outer core move around creating the magnetic field.

But scientists know the moon is too small to create and continue this kind of heat and force.

BOB DOUGHTY: Now, two researchers are offering possible explanations for how the moon got a magnetic field.

Christina Dwyer is a graduate student in Earth and planetary sciences at the University of California, Santa Cruz. She thinks the magnetic field developed when the moon and Earth were thousands of kilometers closer to each other.

She says the Earth’s gravity at that distance created a stronger tidal force. It pulled the hard rock part of the moon, its mantle¹¹, around its liquid iron center, or core. This movement stirred the liquid iron core strongly enough to create a magnetic field.

Ms. Dwyer’s research suggests that the magnetic field existed for about a billion years. During that time, the Earth moved further from the moon. The moon’s core and rock layer began to rotate more smoothly¹² together. As a result, the magnetic field disappeared. The scientists say that happened at least 2.7 billion years ago, if not longer.

FAITH LAPIDUS: Another possible explanation comes from Michael Le Bars at the Research Institute for Out-of-Equilibrium Phenomena¹³ in France. His theory also suggests the moon’s mantle may have been involved in the stirring of the liquid core. But, he says huge space objects were also involved.

Mr. Le Bars’ research suggests that a number of meteors, asteroids¹⁴ and other objects hit the moon almost four billion years ago. He says each strike shook the moon enough to cause a ten-thousand-year-long magnetic field.

Either theory could be correct. And, the two theories could also work together as an explanation of the magnetic rocks from the moon. But as Christina Dwyer has noted¹⁵, additional higher level tests are needed to see if either theory really works.

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Artist Vasily Slonov lies on his installation artwork called "The Terrible Chinese Dream: Death of Mao" in the Russian city of Krasnoyarsk last year

JIM TEDDER¹⁶: I think there is an elephant in my room. What is it doing here? I’ll ask that lady sitting next to me. She is my grandmother. She died forty years ago. She smiles at me and I hear her say, “Let’s eat.” Suddenly hundreds of bowls of rice appear on a table. But I cannot eat because I have to fly in an airplane. I am high up in the sky, looking down on my house. I’m too close to the door. Please don’t let me fall. Why is this happening to me? How can this be happening to me? Then I hear the words that calm my fears. A voice says, “Wake up. Wake up! You’re dreaming.”

BOB DOUGHTY: Why do we dream? Why are dreams so strange? What happens to our brains while we are dreaming? Those questions have been a mystery to psychologists, medical doctors and scientists for years. Now, a new study may provide a few answers. The results were published on the Current Biology website.

Martin Dresler works at the Max Planck Institute of Psychiatry¹⁷ in Munich, Germany. He and his team searched for people who are called “lucid dreamers.” These are people who know when they are dreaming. They also can control their dreams as if they are awake. Scientists think that many people are lucid dreamers, at least part of the time. But there are fewer people who can control their dreams, from one day to the next.

FAITH LAPIDUS: People have been writing about lucid dreams for nearly sixteen hundred years. In nineteen sixty-eight, British psychologist Celia Green wrote a major book on the subject. She thought that lucid dreams happened most during rapid-eye-movement, or REM, sleep.

During REM sleep, our bodies become stiff, and our muscles do not move. Our eyelids¹⁸ move or flutter rapidly as the eyeball seems to be looking in many different directions.

Researchers are not sure why most people have REM sleep for an hour or so each night. Some believe that this activity helps our memory. Others think that REM sleep helps to keep our brain chemicals healthy. For most people, this deep REM sleep is a necessary part of life. People who are repeatedly awakened¹⁹ during the night usually do not get enough REM sleep, and do not feel they have enough energy the next day.

BOB DOUGHTY: The researchers at the Max Planck Institute asked six lucid dreamers to try falling asleep inside a functional²⁰ magnetic-resonance imaging machine. This device enabled the researchers to see on a computer screen what was happening to the brains of these individuals while they slept.

The sleepers²¹ were told to begin the test by quickly moving their eyes from left to right two times as a sign that they knew they were asleep. Then the subjects were asked to dream that they were squeezing their hands into a fist. First they dreamed of doing this with their left hand, and then the right. They did this ten times for each hand. Then they were told to again move their eyes quickly to show that they had finished with the test.

The researchers found that the human brain acts the same when dreaming as it does when a person is awake. In other words, the computer screen showed that the same areas of the brain “light up” and become active in either situation. When a man dreams that he is moving his hand, his brain looks the same on the computer as when he is actually making the motion. And this, the researchers think, is an important discovery.

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FAITH LAPIDUS: This SCIENCE IN THE NEWS was written by Brianna Blake, Jim Tedder and Jerilyn Watson. Our producer was June Simms. I’m Faith Lapidus.

BOB DOUGHTY: And I’m Bob Doughty. Join us again next week for more news about science in Special English on the Voice of America.

1 lucid   

adj.明白易懂的，清晰的，头脑清楚的

参考例句：

• His explanation was lucid and to the point.他的解释扼要易懂。
• He wasn't very lucid,he didn't quite know where he was.他神志不是很清醒，不太知道自己在哪里。

2 doughty   

adj.勇猛的，坚强的

参考例句：

• Most of successful men have the characteristics of contumacy and doughty.绝大多数成功人士都有共同的特质：脾气倔强，性格刚强。
• The doughty old man battled his illness with fierce determination.坚强的老人用巨大毅力与疾病作斗争。

3 Celsius   

adj.摄氏温度计的，摄氏的

参考例句：

• The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
• The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。

4 methane   

n.甲烷，沼气

参考例句：

• The blast was caused by pockets of methane gas that ignited.爆炸是由数袋甲烷气体着火引起的。
• Methane may have extraterrestrial significance.甲烷具有星际意义。

5 joint   

adj.联合的，共同的；n.关节，接合处；v.连接，贴合

参考例句：

• I had a bad fall,which put my shoulder out of joint.我重重地摔了一跤，肩膀脫臼了。
• We wrote a letter in joint names.我们联名写了封信。

6 thawing   

n.熔化，融化v.（气候）解冻( thaw的现在分词 )；（态度、感情等）缓和；（冰、雪及冷冻食物）溶化；软化

参考例句：

• The ice is thawing. 冰在融化。 来自《现代英汉综合大词典》
• It had been snowing and thawing and the streets were sloppy. 天一直在下雪，雪又一直在融化，街上泥泞不堪。 来自英汉文学 - 嘉莉妹妹

7 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

8 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

9 thawed   

解冻

参考例句：

• The little girl's smile thawed the angry old man. 小姑娘的微笑使发怒的老头缓和下来。 来自《简明英汉词典》
• He thawed after sitting at a fire for a while. 在火堆旁坐了一会儿，他觉得暖和起来了。 来自《简明英汉词典》

10 permanently   

adv.永恒地，永久地，固定不变地

参考例句：

• The accident left him permanently scarred.那次事故给他留下了永久的伤疤。
• The ship is now permanently moored on the Thames in London.该船现在永久地停泊在伦敦泰晤士河边。

11 mantle   

n.斗篷，覆罩之物，罩子；v.罩住，覆盖，脸红

参考例句：

• The earth had donned her mantle of brightest green.大地披上了苍翠欲滴的绿色斗篷。
• The mountain was covered with a mantle of snow.山上覆盖着一层雪。

12 smoothly   

adv.平滑地，顺利地，流利地，流畅地

参考例句：

• The workmen are very cooperative,so the work goes on smoothly.工人们十分合作，所以工作进展顺利。
• Just change one or two words and the sentence will read smoothly.这句话只要动一两个字就顺了。

13 phenomena   

n.现象

参考例句：

• Ade couldn't relate the phenomena with any theory he knew.艾德无法用他所知道的任何理论来解释这种现象。
• The object of these experiments was to find the connection,if any,between the two phenomena.这些实验的目的就是探索这两种现象之间的联系，如果存在着任何联系的话。

14 asteroids   

n.小行星( asteroid的名词复数 )；海盘车，海星

参考例句：

• Asteroids,also known as "minor planets",are numerous in the outer space. 小行星，亦称为“小型行星”，在外太空中不计其数。
• Most stars probably have their quota of planets, meteorids, comets, and asteroids. 多数恒星也许还拥有若干行星、流星、彗星和小行星。

15 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

16 tedder   

n.（干草）翻晒者，翻晒机

参考例句：

• Jim Tedder has more. 吉姆？特德将给我们做更多的介绍。 来自互联网
• Jim Tedder tells us more. 吉姆？泰德给我们带来更详细的报道。 来自互联网

17 psychiatry   

n.精神病学，精神病疗法

参考例句：

• The study appeared in the Amercian science Journal of Psychiatry.这个研究发表在美国精神病学的杂志上。
• A physician is someone who specializes in psychiatry.精神病专家是专门从事精神病治疗的人。

18 eyelids   

n.眼睑( eyelid的名词复数 )；眼睛也不眨一下；不露声色；面不改色

参考例句：

• She was so tired, her eyelids were beginning to droop. 她太疲倦了，眼睑开始往下垂。
• Her eyelids drooped as if she were on the verge of sleep. 她眼睑低垂好像快要睡着的样子。 来自《简明英汉词典》

19 awakened   

v.（使）醒( awaken的过去式和过去分词 )；（使）觉醒；弄醒；（使）意识到

参考例句：

• She awakened to the sound of birds singing. 她醒来听到鸟的叫声。
• The public has been awakened to the full horror of the situation. 公众完全意识到了这一状况的可怕程度。 来自《简明英汉词典》

20 functional   

adj.为实用而设计的，具备功能的，起作用的

参考例句：

• The telephone was out of order,but is functional now.电话刚才坏了，但现在可以用了。
• The furniture is not fancy,just functional.这些家具不是摆着好看的，只是为了实用。

21 sleepers   

n.卧铺（通常以复数形式出现）；卧车( sleeper的名词复数 )；轨枕；睡觉（呈某种状态）的人；小耳环

参考例句：

• He trod quietly so as not to disturb the sleepers. 他轻移脚步，以免吵醒睡着的人。 来自辞典例句
• The nurse was out, and we two sleepers were alone. 保姆出去了，只剩下我们两个瞌睡虫。 来自辞典例句