【每日阅读训练第四期——速度越障12系列】【12-12】科技

CHRISTINE2010

【速度一】

Space Travel May Be Harmful to the Brain, Study Suggests; Prolonged Cosmic Radiation Exposure Could Hasten Alzheimer's

Dec. 31, 2012 — As if space travel was not already filled with enough dangers, a new study out today in the journal PLOS ONE shows that cosmic radiation -- which would bombard astronauts on deep space missions to places like Mars -- could accelerate the onset of Alzheimer's disease.
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"Galactic cosmic radiation poses a significant threat to future astronauts," said M. Kerry O'Banion, M.D., Ph.D., a professor in the University of Rochester Medical Center (URMC) Department of Neurobiology and Anatomy and the senior author of the study. "The possibility that radiation exposure in space may give rise to health problems such as cancer has long been recognized. However, this study shows for the first time that exposure to radiation levels equivalent to a mission to Mars could produce cognitive problems and speed up changes in the brain that are associated with Alzheimer's disease."

While space is full of radiation, the earth's magnetic field generally protects the planet and people in low earth orbit from these particles. However, once astronauts leave orbit, they are exposed to constant shower of various radioactive particles. With appropriate warning, astronauts can be shielded from dangerous radiation associated with solar flares. But there are also other forms of cosmic radiation that, for all intents and purposes, cannot be effectively blocked.

Because this radiation exists in low levels, the longer an astronaut is in deep space, the greater the exposure. This is a concern for NASA as the agency is planning manned missions to a distant asteroid in 2021 and to Mars in 2035. The round trip to the red planet, in particular, could take as long as three years.

For over 25 years, NASA has been funding research to determine the potential health risks of space travel in an effort to both develop countermeasures and determine whether or not the risks warranted sending men and women on extended missions in deep space.

Since that time, several studies have demonstrated the potential cancer, cardiovascular, and musculoskeletal impact of galactic cosmic radiation. The study out today for the first time examines the potential impact of space radiation on neurodegeneration, in particular, the biological processes in the brain that contribute to the development of Alzheimer's disease. O'Banion -- whose research focuses on how radiation affects the central nervous system -- and his team have been working with NASA for over eight years.
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【速度二】

The researchers studied the impact of a particular form of radiation called high-mass, high-charged (HZE) particles. These particles -- which are propelled through space at very high speeds by the force of exploding stars -- come in many different forms. For this study the researcher chose iron particles. Unlikely hydrogen protons, which are produced by solar flares, the mass of HZE particles like iron, combined with their speed, enable them to penetrate solid objects such as the wall and protective shielding of a spacecraft.

"Because iron particles pack a bigger wallop it is extremely difficult from an engineering perspective to effectively shield against them," said O'Banion. "One would have to essentially wrap a spacecraft in a six-foot block of lead or concrete."
A portion of the research was conducted at the NASA Space Radiation Laboratory at Brookhaven National Laboratory on Long Island. NASA located its research operation at Brookhaven to take advantage of the Lab's particle accelerators which -- by colliding matter together at very high speeds -- can reproduce the radioactive particles found in space.

The researchers specifically wanted to examine whether or not radiation exposure had the potential to accelerate the biological and cognitive indicators of Alzheimer's disease, particularly in individuals who may be predisposed to developing the disease. To accomplish this they chose study the impact on animal models of Alzheimer's disease. These particular models have been extensively studied and scientists understand the precise timeframe in which the disease progresses over time.

At Brookhaven, the animals were exposed to various doses of radiation, including levels comparable to what astronauts would be experience during a mission to Mars. Back in Rochester, a team of researchers -- including URMC graduate student Jonathan Cherry, who was first author on the paper -- evaluated the cognitive and biological impact of the exposure. The mice underwent a series of experiments during which they had to recall objects or specific locations. The researchers observed that mice exposed to radiation were far more likely to fail these tasks -- suggesting neurological impairment -- earlier than these symptoms would typically appear.

The brains of the mice also showed signs of vascular alterations and a greater than normal accumulation of beta amyloid, the protein "plaque" that accumulates in the brain and is one of the hallmarks of the disease.
"These findings clearly suggest that exposure to radiation in space has the potential to accelerate the development of Alzheimer's disease," said O'Banion. "This is yet another factor that NASA, which is clearly concerned about the health risks to its astronauts, will need to take into account as it plans future missions."
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【速度三】

Jellyfish Experts Show Increased Blooms Are a Consequence of Periodic Global Fluctuations

Dec. 31, 2012 — Blooms, or proliferations, of jellyfish can show a substantial, visible impact on coastal populations -- clogged nets for fishermen, stinging waters for tourists, even choked cooling intake pipes for power plants -- and recent media reports have created a perception that the world's oceans are experiencing trending increases in jellyfish. Now, a new multinational collaborative study, involving the University of Southampton, suggests these trends may be overstated, finding that there is no robust evidence for a global increase in jellyfish over the past two centuries.
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The results of the study, which includes lead co-author Dr Cathy Lucas, a marine biologist at the University of Southampton, appear in the latest issue of Proceedings of the National Academy of Sciences.

The key finding of the study shows global jellyfish populations undergo concurrent fluctuations with successive decadal periods of rise and fall, including a rising phase in the 1990s and early 2000s that has contributed to the current perception of a global increase in jellyfish abundance. The previous period of high jellyfish numbers during the 1970s went unnoticed due to limited research on jellyfish at the time, less awareness of global-scale problems and a lower capacity for information sharing (e.g. no Internet).

While there has been no increase over the long-term, the authors detected a hint of a slight increase in jellyfish since 1970, although this trend was countered by the observation that there was no difference in the proportion of increasing vs. decreasing jellyfish populations over time.

Dr Cathy Lucas, who is based at the National Oceanography Centre, Southampton, says: "Sustained monitoring is now required over the next decade to shed light with statistical confidence whether the weak increasing linear trend in jellyfish populations after 1970 is an actual shift in the baseline or part of a larger oscillation."
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【速度四】

To date, media and scientific opinion for the current perception of a global increase in jellyfish was evidenced by a few local and regional case studies. Although there are areas where jellyfish have increased; the situation with the Giant Jellyfish in Japan and parts of the Mediterranean are classic examples, there are also areas where jellyfish numbers have remained stable, fluctuated over decadal periods, or actually decreased over time.

Increased speculation and discrepancies about current and future jellyfish blooms by the media and in climate and science reports formed the motivation for the study. "There are major consequences for getting the answer correct for tourism, fisheries and management decisions as they relate to climate change and changing ocean environments," says Dr Lucas. "The important aspect about our work is that we have provided the long-term baseline backed with all data available to science, which will enable scientists to build on and eventually repeat these analyses in a decade or two from now to determine whether there has been a real increase in jellyfish."

"The realisation that jellyfish synchronously rise and fall around the world should now lead researchers to search for the long-term natural and climate drivers of jellyfish populations, in addition to begin monitoring jellyfish in open ocean and Southern Hemisphere regions that are underrepresented in our analyses," says lead author Dr Rob Condon, marine scientist at the Dauphin Island Sea Lab (DISL) in Alabama.

Given the potential damage posed by jellyfish blooms to fisheries, tourism and other human industries, the findings of the group foretell recurrent phases of rise and fall in jellyfish populations that society should be prepared to face.
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【速度五】

Liquid Crystal Research May Lead to Creation of New Materials That Can Be Actively Controlled

Dec. 24, 2012 — Contributing geometric and topological analyses of micro-materials, University of Massachusetts Amherst mathematician Robert Kusner aided experimental physicists at the University of Colorado (UC) by successfully explaining the observed "beautiful and complex patterns revealed" in three-dimensional liquid crystal experiments. The work is expected to lead to creation of new materials that can be actively controlled.
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Kusner is a geometer, an expert in the analysis of variational problems in low-dimensional geometry and topology, which concerns properties preserved under continuous deformation such as stretching and bending. His work over 3 decades has focused on the geometry and topology of curves, surfaces and other spaces that arise in nature, such as soap films, knots and the shapes of fluid droplets. Kusner agrees with physicist and lead author Ivan Smalyukh of UC Boulder that their collaboration is the first to show in experiments that some of the most fundamental topological theorems hold up in real materials. Their findings appear in the current early online issue of Nature.

UMass Amherst's Kusner explains, "There are two important aspects of this work. First, the experimental work by the Colorado team, who fabricated topologically complex micro-materials allowing controlled experiments of three-dimensional liquid crystals. Second, the theoretical work performed by us mathematicians and theoretical physicists while visiting the University of California Santa Barbara's Kavli Institute for Theoretical Physics (KITP). We provided the geometric and topological analysis of these experiments, to explain the observed patterns and predict what patterns should be seen when experimental conditions are changed."

Kusner was the lone mathematician among four organizers of last summer's workshop on "Knotted Fields" at KITP, which led to this work. The workshop engaged about a dozen other mathematicians and about twice as many theoretical and experimental physicists in a month-long investigation of the interplay between low-dimensional topology and what physicists call "soft matter."
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【剩余部分】

In their experiments, the physicists at UC Boulder showed that tiny topological particles injected into a liquid crystal medium behave in a manner consistent with established theorems in geometry and topology, Kusner says. The researchers say they have thus identified approaches for building new materials using topology.

UC Boulder's Smalyukh and colleagues set up the experiment by first creating colloids, solutions in which tiny particles are dispersed but not dissolved in a host medium, such as milk, paint and shaving cream. Specifically, they injected tiny, different-shaped particles into a liquid crystal, which behaves something like a liquid and a solid. Once injected into a liquid crystal, the particles behaved as predicted by topology.

Smalyukh says, "Our study shows that interaction between particles and molecular alignment in liquid crystals follows the predictions of topological theorems, making it possible to use these theorems in designing new composite materials with unique properties that cannot be encountered in nature or synthesized by chemists. These findings lay the groundwork for new applications in experimental studies of low-dimensional topology, with important potential ramifications for many branches of science and technology."

For example, he adds, these topological liquid crystal colloids could be used to upgrade current liquid crystal displays like those used in laptops and television screens, to allow them to interact with light in new, more energy efficient ways.
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【越障】

Fluctuating Environment May Have Driven Human Evolution

Dec. 24, 2012 — A series of rapid environmental changes in East Africa roughly 2 million years ago may be responsible for driving human evolution, according to researchers at Penn State and Rutgers University.
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"The landscape early humans were inhabiting transitioned rapidly back and forth between a closed woodland and an open grassland about five to six times during a period of 200,000 years," said Clayton Magill, graduate student in geosciences at Penn State. "These changes happened very abruptly, with each transition occurring over hundreds to just a few thousand years."
According to Katherine Freeman, professor of geosciences, Penn State, the current leading hypothesis suggests that evolutionary changes among humans during the period the team investigated were related to a long, steady environmental change or even one big change in climate.

"There is a view this time in Africa was the 'Great Drying,' when the environment slowly dried out over 3 million years," she said. "But our data show that it was not a grand progression towards dry; the environment was highly variable."

According to Magill, many anthropologists believe that variability of experience can trigger cognitive development.

"Early humans went from having trees available to having only grasses available in just 10 to 100 generations, and their diets would have had to change in response," he said. "Changes in food availability, food type, or the way you get food can trigger evolutionary mechanisms to deal with those changes. The result can be increased brain size and cognition, changes in locomotion and even social changes -- how you interact with others in a group. Our data are consistent with these hypotheses. We show that the environment changed dramatically over a short time, and this variability coincides with an important period in our human evolution when the genus Homo was first established and when there was first evidence of tool use."

The researchers -- including Gail Ashley, professor of earth and planetary sciences, Rutgers University -- examined lake sediments from Olduvai Gorge in northern Tanzania. They removed the organic matter that had either washed or was blown into the lake from the surrounding vegetation, microbes and other organisms 2 million years ago from the sediments. In particular, they looked at biomarkers -- fossil molecules from ancient organisms -- from the waxy coating on plant leaves.

"We looked at leaf waxes because they're tough, they survive well in the sediment," said Freeman.
The team used gas chromatography and mass spectrometry to determine the relative abundances of different leaf waxes and the abundance of carbon isotopes for different leaf waxes. The data enabled them to reconstruct the types of vegetation present in the Olduvai Gorge area at very specific time intervals.

The results showed that the environment transitioned rapidly back and forth between a closed woodland and an open grassland.

To find out what caused this rapid transitioning, the researchers used statistical and mathematical models to correlate the changes they saw in the environment with other things that may have been happening at the time, including changes in the Earth's movement and changes in sea-surface temperatures.

"The orbit of the Earth around the sun slowly changes with time," said Freeman. "These changes were tied to the local climate at Olduvai Gorge through changes in the monsoon system in Africa. Slight changes in the amount of sunshine changed the intensity of atmospheric circulation and the supply of water. The rain patterns that drive the plant patterns follow this monsoon circulation. We found a correlation between changes in the environment and planetary movement."

The team also found a correlation between changes in the environment and sea-surface temperature in the tropics.

"We find complementary forcing mechanisms: one is the way Earth orbits, and the other is variation in ocean temperatures surrounding Africa," Freeman said. The researchers recently published their results in the Proceedings of the National Academy of Sciences along with another paper in the same issue that builds on these findings. The second paper shows that rainfall was greater when there were trees around and less when there was a grassland.

"The research points to the importance of water in an arid landscape like Africa," said Magill. "The plants are so intimately tied to the water that if you have water shortages, they usually lead to food insecurity.

"Together, these two papers shine light on human evolution because we now have an adaptive perspective. We understand, at least to a first approximation, what kinds of conditions were prevalent in that area and we show that changes in food and water were linked to major evolutionary changes."
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miffyhui

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涂涂Claire

霸住先……考完再来补作业

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kevinlaci

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forazure

【每日阅读训练第四期——速度越障12系列】【12-12】科技

[出勤次数：23(12 of S12) 连续出勤次数：7]

Speed:
1. Word:           410  Time: 2’17”
2. Word: 434   Time: 2’40”
3. Word:   312  Time:1’48”
4. Word:   273  Time:1’37
5. Word:   319  Time:2’00

Obstacle:
Word: 766         Time:5’50”
Main Idea: Fluctuating Environment inAfrica May Have Correlation with Human Evolution
Author'sattitude: Neutral

alun1987

刚写完越障回顾就停电……嗯，这一定是阅读の神在考验我的记忆能力

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越障：
Main idea: A recent research suggests that frequently change environment in East Africa may be responsible for human evolution

Current hypothesis: human evolutionary change is related to a long, steady change in environment, "Great Drying" in Africa

New fndings and hypothesis: "Great Dry" is not the truth, highly variable environment in Africa can trigger the evolution

Supportive evidence:
>>adoption of the changes in environment(eg. food type, food availability) can stimulate evolution
>>some data showed that the time coincides with the important period of human evolution(using tools)
>>experiment about lake sediments has proved the rapid changes in environment during that period

Why such change in environment
>>plantery movement(Earth's orbit), related to supply of water
>>sea-surface temperatures
——the results were published in two papers recently, pointing out the importance of water

Conclusion:The result gives a foundation for future research. Changes in evolution are closely related to food and water(怎么感觉没关系似的……)

铁板神猴

刚写完越障回顾就停电……嗯，这一定是阅读の神在考验我的记忆能力

-- by 会员 alun1987 (2013/1/2 16:19:08)

alun很能自娱自乐啊~
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frankiepn

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annaliang2008

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最近都玩疯了。。。。回头一看GMAT，心碎了一地。。。。

特里凡得琅

2'20
Cosmic radition could produce the cognitive problems and speed up the changes associated with Alz disease
Once people know the radition could lead cancer
In deep space, the radiation could not be fuly blocked (Reason)
NASA's plan to send astraunats in deep space in long time
NASA is studying the consequence of cosmic radition. The professor and his team has worked for NASA 8 years

2'41
Iron particles with high speed could easily wrap the block for shield.
When the particles with high speed collide, the radition is reproduced.
Researchers has done the experiment on anminal in order to explore the connection between radition and ALZ disease.
They found the mices exposured long time in radition will be more inclined to have ALZ disease from the syptom in brain and
vascular.

1'35
The scientist found that there is no robust evidence to prove that the increase of jellfish presenly is caused by the
enviroment problems.

The jellfish are having population fluctuation between decades. The population has reached high level in 1970s, but
the scientist at that time did not observed and recorde much. The professor right now will continue to observe in
order to prove the argument.

1'34
The population of jellfish is evidenced by few local and regional studies.
It has been published in media and science report that motivates the research.
For the research, the most important thing is keeping a long time baseline of data to determine whether there is
a really increase of jellyfish

2'10
Scientist in UMA and UC has found that the liquid crystal could made the new material that could be controlled.
Background of Kusner's research
Two factors for the researsch, experiment in UC and therotical work in UMA