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[阅读小分队] 【每日阅读训练第四期——速度越障19系列】【19-20】科技

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发表于 2013-6-3 21:51:24 | 显示全部楼层 |阅读模式
队友们,周二科技的作业来了,大家加油哦~

Part I Speed
Article I:
Genes weakly linked to education level

Search of more than 2 million DNA locations finds small and hard-to-explain association with schooling

【Time1】
Genetic factors may exert a tiny influence on how much schooling a person ends up with, a new study suggests.

But the main lesson of the research, experts say, should be that attributing cultural and socioeconomic traits to genes is a dicey enterprise.

“If there is a policy implication, it’s that there’s even more reason to be skeptical of genetic determinism,” says sociologist Jeremy Freese of Northwestern University in Evanston, Ill.

Published May 30 in Science by a group of more than 200 researchers, the study does mark the first time genetic factors have been reproducibly associated with a social trait, says Richard Ebstein, a behavioral geneticist at the National University of Singapore. “It announces to social scientists that some things they’ve been studying that make a difference to health and life success do have a base in genetics.”

But even if it does survive further inspection — and many similar links between genes and social characteristics have not — the study accounts for no more than 2 percent of whatever it is that makes one person continue school while someone in similar circumstances chooses to move on to something else.

Previous studies comparing twins and family members have suggested that not-yet-identified genetic factors can explain 40 percent of people’s educational attainment; factors such as social groups, economic status and access to education would explain the other 60 percent. That percentage attributed to genetics is similar to the heritability of physical and medical characteristics such as weight and risk of heart disease.That makes a hunt for the genetic factors underlying educational attainment an attractive prospect.
【264words】

【Time2】
Researchers from the Social Science Genetic Association Consortium set up an experiment that searched 2 million variable locations known as SNPs in the DNA of 101,069 people for variants that appeared to be linked to educational attainment. They found only one that was associated with years of education. Two more SNPs were associated with whether a person had finished college. The researchers then replicated the findings by doing the same sort of analysis on another 25,490 people’s DNA and finding that the same SNPs popped up.

Considering the apparent effect of all 2 million SNPs, the analysis can account for only about 2 percent of the difference between those with the highest and lowest levels of education. The single SNP with the strongest effect explains just 0.022 percent of the variation in educational attainment in the people sampled. The SNP most strongly associated with finishing college gives people about a 1.8 percentage point difference in the odds of completing a degree.

It’s common for genetic variants to have only weak influences on whether someone will develop a particular trait: Variants associated with height, for instance, exert about a 0.4 percent influence. But even scientists used to tiny effects have expressed disappointment at the small contribution of these variants. “It’s not even like a cup half full,” says Robert Plomin, a behavioral geneticist at Kings College London. “It’s a cup that is less than 1 percent full.”

Critics of the study don’t quibble with the way it was done. Their concern — one the authors share — is that there is no gene “for” going to college. The scientists used educational attainment because data on it are available for large numbers of people. But it is a proxy for something else — perhaps differences in the way peoples’ brains work or in personality traits like perseverance that could help people get through school. That means it is impossible to know what the researchers are really measuring.  
【322words】

【Time3】
The researchers caution that they have not identified specific genes, but merely found variants implicating some regions of the genome in educational attainment. Even if they had pinpointed a particular gene, “it doesn’t tell you the mechanism by which the gene is having a relationship with education,” says study coauthor Daniel Benjamin, an economist at Cornell University.

At best, the study may set an upper limit of effects scientists can expect to find in genetic studies of social traits, says Anna Need, a neuropsychiatric geneticist at Imperial College London. If a study of so many people can find only marginal genetic associations, smaller studies claiming to have uncovered genes strongly linked to political views or other social values are probably nonsense, she says. She fears that people will interpret the study to mean that genes determine education levels.

It is a fear shared by Duke University geneticist David Goldstein. “This tiny, tiny, tiny signal is completely pointless and will be misinterpreted,” he says. “Now we’re beating the poor methodology to a point that it will confess to pretty darn near anything.”

The variants identified in the study may be false confessions, he says. They barely clear a statistical hurdle at which one in every 20 SNPs seemingly associated with a trait will actually be due to coincidence. “This is literally right on the border,” Goldstein says, and “has a real good chance of being wrong.”
【238words】

Article II
Mars trip would deliver big radiation dose

Curiosity instrument confirms expectation of major exposures

【Time4】
Astronauts making the journey to and from Mars would face many new and uncertain dangers. Fortunately, the Mars rover Curiosity has reduced uncertainty about one of them: radiation exposure.

Measurements of radiation reaching the shielded interior of the spacecraft that carried Curiosity to Mars indicate that an astronaut on a yearlong round-trip would be exposed to around two-thirds of the career radiation limit that some space agencies set. Any time spent on the planet and outside the spacecraft would add more exposure.

The radiation dose they calculated was 0.66 sieverts, researchers report in the May 31 Science; the agencies’ limit for astronauts is 1 sievert.

On Earth, a 1-sievert dose increases cancer risk by about 5 percent. Scientists don’t know whether space radiation would have similar effects.

“The kinds of radiation that someone going to Mars would experience are different from any radiation that we receive here on Earth, so we don’t have direct experience of what the health risks are,” says David Brenner, director of the Center for Radiological Research at Columbia University.

Previous measurements of the radiation in space have been made outside spacecraft. Good luck enabled the new interior measurements, which were conducted with the Radiation Assessment Detector, a coffee-can-sized device attached to the Curiosity rover. Its designers intended the device to measure radiation on the surface of Mars, not inside the spacecraft that ferried it there.

“We realized as we were getting ready to launch that we had this serendipitous opportunity to also measure the radiation environment inside the spacecraft during our cruise,” says coauthor Donald Hassler of the Southwest Research Institute in Boulder, Colo.

The rover’s measurements confirmed predictions that 95 percent of a Mars-bound astronaut’s radiation dose would come from galactic cosmic rays. Humans are normally shielded from such rays by Earth’s atmosphere, so their effects on our health are unknown, Brenner says.

Still, he says, the measurements are useful because they were close to theoretical predictions of radiation exposure.
【328words】

Article III
Artificial Magnetic Monopoles Discovered


【Time5】
A team of researchers from Cologne, Munich and Dresden have managed to create artificial magnetic monopoles. To do this, the scientists merged tiny magnetic whirls, so-called skyrmions. At the point of merging, the physicists were able to create a monopole, which has similar characteristics to a fundamental particle postulated by Paul Dirac in 1931. In addition to fundamental research, the monopoles may also have application potential. The question of whether magnetic whirls can be used in the production of computer components one day is currently being researched by a number of groups worldwide.

When a magnet is divided, a new magnet with north and south poles is always created. However, a monopole, i.e. a north pole without a south pole or a south pole without a north pole has not yet been discovered. In the current edition of the journal Science, researchers from Cologne, Munich and Dresden describe the discovery of new type of artificial monopole in a solid, i.e. particles, which have similar characteristics to monopoles, but which only exist within materials.

Over the last few years, materials in which magnetic whirls, so-called skyrmions, are formed, have been examined intensively. These whirls influence the movements of the electrons in exactly the same manner as magnetic fields. For this reason, artificial magnet fields are used to describe these whirls as well as their influence on the electrons.

Even if these are not "real" magnetic fields, it is possible to measure them experimentally in the same manner as normal magnet fields as they deflect electrons.

The researchers asked questions as to the consequences of attempting to destroy the magnetic whirls. To do this, the group working under the direction of Prof. Eng from the Technischen Universität Dresden observed magnetic whirls with a magnetic force microscope: a tiny magnetic tip samples the surface of the magnets and measures the direction of the magnetization thus making the ca. 50 nanometer sized whirl visible. They were able to observe on the surface that the magnetic whirls apparently coalesce when the skyrmion phase is destroyed.
【340words】

【The Rest】
What happens, however, within the materials? Measurements taken by the group working under the direction of Prof. Pfleiderer in Munich using neutron scattering suggest that similar processes occur there, but individual whirls were not observed in this manner. For this reason, Stefan Buhrandt and Christoph Schütte working in Prof. Rosch's group at the University of Cologne conducted computer simulations. These showed that the whirls neighbouring the merging process observed on the surface in the experiment also occur within the materials.

Due to the fact that every whirl carries an artificial magnetic field, their creation or destruction occurs at the point of merging. "This means that an artificial magnetic monopole has to sit on this point," describes Prof. Rosch, "whenever two magnetic whirls merge in the experiment, an artificial magnetic monopole has flown through surface."

Magnetic monopoles have been searched for in vain in the area of particle physics for a long time. In 1931, Paul Dirac postulated the existence of a fundamental particle to explain why electrons and protons carry electrical charges of the same size. This is surprising because the elements of the protons and electrons are completely different fundamental particles. Dirac, however, argued that the existence of a single magnetic monopole would be enough to explain that the charges of all fundamental particles have to be quantized, i.e. exactly an integer multiple of an elementary charge. The newly discovered artificial monopoles fulfil exactly this quantization requirement. "It is fascinating that something as fundamental as a magnetic monopole can be realized in a piece of material," describes Stefan Buhrandt. Despite this, artificial monopoles cannot solve Dirac's problem: only electrons in solid state, but not protons, feel the artificial magnet fields.

In addition to their use for fundamental research, artificial monopoles could also have application potential. Many groups worldwide are currently researching the question of whether magnetic whirls could be used in the production of computer components. If this were possible, one would also have to create and destroy whirls: magnetic monopoles would then play an important role in this.
【340words】

Part II Obstacle

Article IV
A Step Closer to Artificial Livers: Researchers Identify Compounds That Help Liver Cells Grow Outside Body


【Time6】
Prometheus, the mythological figure who stole fire from the gods, was punished for this theft by being bound to a rock. Each day, an eagle swept down and fed on his liver, which then grew back to be eaten again the next day.

Modern scientists know there is a grain of truth to the tale, says MIT engineer Sangeeta Bhatia: The liver can indeed regenerate itself if part of it is removed. However, researchers trying to exploit that ability in hopes of producing artificial liver tissue for transplantation have repeatedly been stymied: Mature liver cells, known as hepatocytes, quickly lose their normal function when removed from the body.

"It's a paradox because we know liver cells are capable of growing, but somehow we can't get them to grow" outside the body, says Bhatia, the John and Dorothy Wilson Professor of Health Sciences and Technology and Electrical Engineering and Computer Science at MIT, a senior associate member of the Broad Institute and a member of MIT's Koch Institute for Integrative Cancer Research and Institute for Medical Engineering and Science.

Now, Bhatia and colleagues have taken a step toward that goal. In a paper appearing in the June 2 issue of Nature Chemical Biology, they have identified a dozen chemical compounds that can help liver cells not only maintain their normal function while grown in a lab dish, but also multiply to produce new tissue.

Cells grown this way could help researchers develop engineered tissue to treat many of the 500 million people suffering from chronic liver diseases such as hepatitis C, according to the researchers.

Lead author of the paper is Jing (Meghan) Shan, a graduate student in the Harvard-MIT Division of Health Sciences and Technology. Members of Bhatia's lab collaborated with researchers from the Broad Institute, Harvard Medical School and the University of Wisconsin.

Large-scale screen

Bhatia has previously developed a way to temporarily maintain normal liver-cell function after those cells are removed from the body, by precisely intermingling them with mouse fibroblast cells. For this study, funded by the National Institutes of Health and Howard Hughes Medical Institute, the research team adapted the system so that the liver cells could grow, in layers with the fibroblast cells, in small depressions in a lab dish. This allowed the researchers to perform large-scale, rapid studies of how 12,500 different chemicals affect liver-cell growth and function.

The liver has about 500 functions, divided into four general categories: drug detoxification, energy metabolism, protein synthesis and bile production. David Thomas, an associate researcher working with Todd Golub at the Broad Institute, measured expression levels of 83 liver enzymes representing some of the most finicky functions to maintain.

After screening thousands of liver cells from eight different tissue donors, the researchers identified 12 compounds that helped the cells maintain those functions, promoted liver cell division, or both.

Two of those compounds seemed to work especially well in cells from younger donors, so the researchers -- including Robert Schwartz, an IMES postdoc, and Stephen Duncan, a professor of human and molecular genetics at the University of Wisconsin -- also tested them in liver cells generated from induced pluripotent stem cells (iPSCs). Scientists have tried to create hepatocytes from iPSCs before, but such cells don't usually reach a fully mature state. However, when treated with those two compounds, the cells matured more completely.

Bhatia and her team wonder whether these compounds might launch a universal maturation program that could influence other types of cells as well. Other researchers are now testing them in a variety of cell types generated from iPSCs.

In future studies, the MIT team plans to embed the treated liver cells on polymer tissue scaffolds and implant them in mice, to test whether they could be used as replacement liver tissues. They are also pursuing the possibility of developing the compounds as drugs to help regenerate patients' own liver tissues, working with Trista North and Wolfram Goessling of Harvard Medical School.

Eric Lagasse, an associate professor of pathology at the University of Pittsburgh, says the findings represent a promising approach to overcoming the difficulties scientists have encountered in growing liver cells outside of the body. "Finding a way of growing functional hepatocytes in cell culture would be a major breakthrough," says Lagasse, who was not part of the research team.

Making connections

Bhatia and colleagues have also recently made progress toward solving another challenge of engineering liver tissue, which is getting the recipient's body to grow blood vessels to supply the new tissue with oxygen and nutrients. In a paper published in the Proceedings of the National Academy of Sciences in April, Bhatia and Christopher Chen, a professor at the University of Pennsylvania, showed that if preformed cords of endothelial cells are embedded into the tissue, they will rapidly grow into arrays of blood vessels after the tissue is implanted.

To achieve this, Kelly Stevens in the Bhatia lab worked with Peter Zandstra at the University of Toronto to design a new system that allows them to create 3-D engineered tissue and precisely control the placement of different cell types within the tissue. This approach, described in the journal Nature Communications in May, allows the engineered tissue to function better with the host tissue.

"Together, these papers offer a path forward to solve two of the longstanding challenges in liver tissue engineering -- growing a large supply of liver cells outside the body and getting the tissues to graft to the transplant recipient," Bhatia says.
【911words】

发表于 2013-6-3 22:04:20 | 显示全部楼层
哇哦~~!

__________________________________________________________
Speed
01:27
Genetic factors may exert a tiny influence on how much schooling a person ends up with.
01:20
The influence is weak.
01:17
Debate on it
01:13
Research of radiation on Mars
01:22
Creation of artificial magnetic monopoles

Obstacle
04:08
Main idea: Improvement in technology of treatment of liver.
Attitude:   Positive
Structure:
            1) Trouble in treatment of liver previously
            2) The research team funded by the National Institutes of Health and Hoeard Hughes Medical Institute made the liver cells grow.
            3) Bhatia and colleagues get the liver tissues to graft to the transplant recipient.
  


发表于 2013-6-3 22:08:17 | 显示全部楼层
打卡,圆满完成19系作业。

Time1 1'26"
Time2 1'39"
Time3 1'04"
Time4 1'34"
Time5 1'39"+1'36"
Obstacle 4'04"
发表于 2013-6-3 22:09:59 | 显示全部楼层
占座我爱大米姐!
发表于 2013-6-3 22:16:43 | 显示全部楼层
先来占座~


-----------------------------------------------------------

1:53.4
2:26.9
2:07.4
2:49.4
3:18.1
7:43.1
发表于 2013-6-3 22:20:29 | 显示全部楼层
占一个,大米姐辛苦了~~

2.21
3.21
2.40
3.49
2.27


T T直接看不懂
发表于 2013-6-3 22:32:15 | 显示全部楼层
前排占座~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
补作业来了
Time 1:
A new sutdy suggests that genetic factors affect most part of the school acdemic behavior.Time 2:
How the experiment was done
Time 3:
some scientists were affrid about the result might be misunderstanding
Time 4:  2'43
scientists found a new way to measure radiation exposure. Some introductions were given about the radiation from space. And the measurement would help a lot.
Time 5: 2'20
To be honest, It's hard for me to catch what the article says. I only can get that it mentions the south pole, the north pole, and sth. appears in the south part without the north part. That's all.

Time 1/2/3 地铁上读的,没计时。越障。。。我永远都读不到的越障。。。
发表于 2013-6-3 22:37:29 | 显示全部楼层
围观3楼JQ!

1 - 01:51
2 - 01:53
3 - 01:30
4 - 02:01

上完课回来继续补!
发表于 2013-6-3 22:49:10 | 显示全部楼层
1:10
1:20
1:05
1:40
1:45

4:20

MI:cultivate liver outside body
Attitudebjective
Structure

Take Prometheus as example to show that it was an immpossible mission in the past time.
Today's approach to this goal.
Examples of experiments to cultivate cell of liver.
Future's way of this research.
发表于 2013-6-3 23:46:07 | 显示全部楼层
今天的速度很有意思~其实感觉科技类的会读起来慢,因为是逐字地读而不像读文史哲类的能“一片”地读,但是可能是生词都被跳过了,所以速度也没有降太多,不过理解得不够充分。
速度:
1.1'58''
2.1'50''
3.1'16''
4.1'57''
5.1'53''
越障:4'04''

Modern scientists exploit that mature liver cells can regenerate themselves but lose some functions.
scientists' research on getting the cells to grow outside the body.
Scientists found 12 compounds that helped the cells maintain functions.
IMES and IPSCs help the cells matured better.
another challenge in liver tissue engineering--graft the tissues to the transplant recipient.

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