1. What is this passage mainly about? The reproduction of the rainforest at a New York museum.
2. How did the museum collect the data in the Central African Republic? It sent a large team of scientists there.
3. To give the forest a sense of realness, all the following are used EXCEPT that the forest is surrounded by front and back walls.
4. What is the main theme of the last paragraph? Preservation of the rainforest exhibition as an artifact.
5. What does the last sentence of the passage most probably mean? The exhibit reflects the hope that natural rainforests will be well preserved.
Underground Coal Fires a Looming Catastrophe 地下煤引发即将来临的灾难
1. According to the first paragraph, one of the warnings given by the scientists is that poisonous elements released by the underground fires can pollute water sources.
2. According to the third paragraph, what will happen when the underground heat does not disappear? Coal heats up on its own and catches fire and burns.
3. What did Stracher analyze in his article published in the International Journal of Coal Ecology? Coal fires can have an impact on the environment.
4. Which of the following statements about Paul Van Dijk is NOT true? He has detected and monitored underground fires in Netherlands.
5. According to the fifth paragraph, what is the suggested method to control underground fires? Cutting off the oxygen supply.
U.S. Marks 175 Locomotive Years 美国纪念机车诞生175周年
1. William Mason was the oldest locomotive in operation in America.
2. The oldest locomotive will be put to tests again to make sure it is up to the federal standards before operation.
3. Which of the following statements is NOT a correct description of the Rocket? It sped up the development of railroading in America.
4. How large is the museum’s roundhouse? One-thirty-second of the museum.
5. Which of the following best describes the collection of the artifacts in the museum? Its collection is important and representative.
Will Quality Eat up the U.S. Lead in Software? 质量问题会使美国的软件业失去主导地位吗？
1. What country has more highest-rating companies in the world than any other country has? India.
2. Which of the following statements about Humphrey is true? India honors him highly.
3. By what means did Japan grab its large market share by the 1970s and the 1980s? Its products were cheaper in price and better in quality.
4. What does the founding of the Watts Humphrey Software Quality Institute symbolize? It symbolizes the Indian ambition to take the lead in software.
5. What is the writer worrying about? The US will no longer be the first software player in the world.
五、补全短文：
Ants as a Barometer of Ecological Change生态变化的气压计-蚂蚁
At picnics, ants are pests. But they have their uses. In industries such as mining, farming and forestry, they can help gauge the health of the environment by just crawling around and being antsy.
It has been recognized for decades that ants-which are highly sensitive to ecological change-can provide a near-perfect barometer of the state of an ecosystem. Only certain species, for instance, will continue to thrive at a forest site that has been cleared of trees. Others will die out for lack of food. And still others will move in and take up residence.
By looking at which species populate a deforested area, scientists can determine how “stressed” the land is. They do this by sorting the ants, counting their numbers and comparing the results with those of earlier surveys.
Where mine sites are being restored, for example, some ant species will recolonize the stripped land more quickly than other. This allowed scientists to gauge the pace and progress of the ecological recovery. Australian mining company Capricorn Coal Management has been successfully using ant surveys for years to determine the rate of recovery of land that it is replanting near its German Creek mine in Queensland.
Ant surveys also have been used with mine-site recovery projects in Africa and Brazil, where warm climates encourage dense and diverse ant populations. “we found it worked extremely well there,” says Jonathan Majer, a professor of environmental biology. Yet the surveys are perfectly suited to climates throughout Asia, he says, because ants are so common throughout the region. As Majer puts it: “that’s the great thing about ants.”
Ant surveys are so highly-regarded as ecological indicators that governments worldwide accept their results when assessing the environmental impact of miming and tree harvesting. yet in other businesses, such as farming and property development, ant surveys aren’t used widely.
Why not? Because many companies can’t afford the expense or the laboratory time needed to sift results for a comprehensive survey. The cost stems, also, from the scarcity of ant specialists. Employing those people are expensive.
Agitated Sunsports Cause Trouble太阳黑子活动频造成的影响
If the lights in your house keep flickering, blame frequent sunspots.
A sunspot is actually charged particles flying at the speed of 3 million kilometers an hour out of the surface of the sun to form sun storms.
Every 11 years, the sun, as its energy accumulate inside up to a certain point, will send out streams of charged particles, which affect the earth in different ways.
The earth, which is directly energized by the sun, is influenced by sun storms in a number of ways.
One is that the magnetic field of the earth is much disturbed because of the sun’s interference in the ionosphere, which is 80 to 500 kilometers above the earth. Wireless short-wave communication, which depends on the wave’s reflection against this layer of atmosphere, is likely to be jammed. It is said that mobile phone communication may be affected too.
Scientists also say that the active movement of the charged sun storm also has effects on earthquakes. According to a research conducted by the Russian scientists from 1957 to 1960, the frequency of earthquakes can be linked to the movement of the sunspots.
Though little research has been carried out about how exactly the sunspot will negatively harm the health of the people, a paper published by a North Korea observatory says that sun storms may cause an increase in the incidence of heart disease and skin disease. So, scientists warn that people going outdoors should be careful to protect their exposed skin and eyes with clothes, umbrellas and sunglasses from the strong sunlight rich in ultraviolet rays.
Besides, the nervous system is also affected, and traffic accidents are more frequent when sunspots are active.
It is hard to say when the sunspots are most violent during their active year, but generally one active period is believed to last possibly eight days. Not long ago there were two violent sun storms breaking out, which seriously affected mobile phone communication, etc. in many parts of the world. But the communication situation in each case returned to normal in about 24 hours.
Don‘t Rely on Plankton to Save the Planet不要靠浮游生物拯救这个星球
Encouraging plankton growth in the ocean has been touted by some as a promising way to remove carbon dioxide from the atmosphere. It opponents fear that it will damage the marine ecosystem, and now a computer model shows that the trick would also be remarkably inefficient.
Adding iron to patches of ocean can make plankton bloom temporarily. The microscopic organisms suck up dissolved carbon dioxide from the water, which in turn is replaced by carbon dioxide from the air. As plankton die and settle on the ocean floor, their carbon is supposedly locked up in the seabed.
Jorge Sarmiento from Princeton and his colleagues developed a complex computer model to analyse how factors such as ocean chemistry and water circulation would affect the process if 160,000 square kilometers of ocean were seeded with iron for a month. They found that 100 years only between 2 and 11 per cent of the extra carbon that was originally taken up by plankton had actually been removed from the atmosphere.
In their scenario, which covers an area 10 times as big as the largest experiment of this kind ever proposed, fertilising the ocean removes 1 million tones of carbon from the atmosphere-just 0.2 per cent of the carbon dioxide humankind spews out each month.
Rough estimates in the past have predicted similarly disappointing results. “there are newer and better models,” says Sallie Chisholm, an environmental engineer from the Massachusetts Institute of Technology. “But the take-home message is the same. Ocean fertilization is not the answer to global warning.”
Dung to Death施肥致死
Fields across Europe are contaminated with dangerous levels of the antibiotics given to farm animals. The drugs, which are in manure sprayed onto fields as fertilizers, could be getting into our food and water, helping to create a new generation of antibiotic-resistant “superbugs”.
The warning comes from a researcher in Switzerland who looked at levels of the drugs in farm slurry. His findings are particularly shocking because Switzerland is one of the few countries to have banned antibiotics as growth promoters in animal feed.
Some 20,000tons of antibiotics are used in the European Union and the US each year. More than half are given to farm-animals to prevent disease and promote growth. But recent research has found a direct link between the increased use of these farmyard drugs and the appearance of antibiotic-resistant bugs that infect people.
Most researchers assumed that humans become infected with the resistant strains by eating contaminated meat. But far more of the drugs end up in manure than inn meat products, says Stephen Mueller of the Swiss Federal Institute for Environmental Science and Technology in Dubendorf. And manure contains especially high levels of bugs that are resistant to antibiotics, he says.
With millions of tons of animals manure spread on to fields of crops such as wheat and barley each year, this pathway seems an equally likely route for spreading resistance , he said. The drugs contaminate the crops, which are then eaten, they could so be leaching onto tap water pumped from rocks beneath fertilized fields.
Mueller is particularly concerned about a group of antibiotics called sulphonamides. The do not easily degrade or dissolve in water. His analysis found that Swiss farm manure contains a high percentage of sulphonamides; each hectare of field could be contaminated with up to 1 kilogram of the drugs. This concentration is high enough to trigger the development of resistance among bacteria. But vets are not treating the issue seriously.
There is growing concern at the extent go which drugs, including antibiotics, are polluting the environment. Many drugs given to humans are also excreted unchanged and are not broken down by conventional sewage treatment.
Einstein Named “person of the Century”爱因斯坦被称作“世纪之人”
Albert Einstein, whose theories on space time and matter helped unravel the secrets of the atom and of the universe, was chosen as “Person of the Century” by Time magazine on Sunday.
A man whose very name is synonymous with scientific genius, Einstein has come to represent more than any other person the flowering o 20th century scientific thought that set the stage for the age of technology.
“The world has changed far more in the past 100 years than in any other century in history. The reason is not political or economic, but technological-technologies that flowed directly from advances in basic science,” wrote theoretical physicist Stephen Hawking in a Time essay explaining Einstein’s significance. “Clearly, no scientist better represents those advances than Albert Einstein.”
Time chose as runner-up President Franklin Roosevelt to represent the triumph of freedom and democracy over fascism, and Mahatma Gandhi as an icon for a century when civil and human rights became crucial factors in global politics.
“what we saw was Franklin Roosevelt embodying the great theme of freedom’s fight against totalitarianism, Gandhi personifying the great theme of individuals struggling for their rights, and Einstein being both a great genius and a great symbol of a scientific revolution that brought with it amazing technological advances that helped expand the growth of freedom,” said Time Magazine Editor Walter Isaacson.
Einstein was born in Ulm, Germany in 1879. In his early years, Einstein did not show the promise of what he was to become. He was slow to learn to speak and did not do well in elementary school. He could not stomach organized learning and loathed taking exams.
In 1905, however, he was to publish a theory which stands as one of the most intricate examples of human imagination in history. In his “Special Theory of Relativity,” Einstein described how the only constant in the universe is the speed of light. Everything else-mass, weight, space, even time itself-is a variable. And he offered the world his now-famous equation: energy equals mass times the speed of light squared-E=mc.
“Indirectly, relativity paved the way for a new relativism in morality, art and politics,” Isaacson wrote in an essay explaining Time’s choices. “There was less faith in absolutes, not only of time and space but also of truth and morality.”
Einstein’s famous equation was also the seed that led to the development of atomic energy and weapons. In 1939, six years after he fled European fascism and settled at Princeton University, Einstein, an avowed pacifist, signed a letter to President Roosevelt urging the United States to develop an atomic bomb before Nazi Germany did. Roosevelt heeded the advice and formed the “Manhattan Project” that secretly developed the first atomic weapon. Einstein did not work on the project.Einstein died in Princeton, New Jersey in 1955.
“Happy Birthday to You”祝你生日快乐
The main problem in discussing American popular culture is also one of its main characteristics: it won’t stay American. No matter what it is, whether it is films, food and fashion, music, casual sports or slang, it’s soon at home elsewhere in the world. There are several theories why American popular culture has had this appeal.
One theory is that it has been “advertised” and marketed through American films, popular music, and more recently, television. But this theory fails to explain why America films, music, and television programs are so popular in themselves. They are, after all, in competition with those produced by other countries.
Another theory, probably a more common one, is that American popular culture is internationally associated with something called “the spirit of America.” This spirit is variously described as being young and free, optimistic and confident, informal and disrespectful.
The final theory is less complex: American popular culture is popular because a lot of people in the world like it.
Regardless of why it spreads, American popular culture is usually quite rapidly adopted and then adapted in many other countries. As a result, its American origins and roots are often quickly forgotten. “Happy Birthday to You,” for instance, is such an everyday song that its source, its American copyright, so to speak, is not remembered. Black leather jackets worn by many heroes in American movies could be found, a generation later on all those young men who wanted to make this manly-look their own.
Two areas where this continuing process is most clearly seen are clothing and music. Some people can still remember a time when T-shirts, jogging clothes, tennis shoes, denim jackets, and blue jeans were not common daily wear everywhere. Only twenty years ago, it was possible to spot an American in Paris by his or her clothes. No longer so: those bright colors, checkered jackets and trousers, hats and socks which were once made fun of in cartoons are back again in Paris as the latest fashion. American in origin, informal clothing has become the world’s first truly universal style.
The situation with American popular music is more complex because in the beginning, when it was still clearly American, it was often strongly resisted. Jazz was once thought to be a great danger to youth and their morals, and was actually outlawed in several countries. Today, while still showing its rather American roots, it has become so well established. Rock ‘n’ roll and all its variations, country & western music, all have more or less similar histories. They were first resisted, often in America as well, as being “low-class,” and then as “a danger to our nation’s youth.” The BBC, for example, banned rock and roll until 1962. And then the music became accepted and was extended and developed, and exported back to the U.S..
High Dive从高空往下跳
Cheryl Sterns aims to go boldly where no human has ever gone before in a balloon: 40 kilometers up into the atmosphere. From there, she’ll take a death-defying leap back to earth at supersonic speed. No one has ever leapt from such a height or gone supersonic without an airplane or a spacecraft. Yet Sterns, an airline pilot, is not the only person who wants to be the first to accomplish those feats. Two other brave people, an Australian man and a Frenchman, are also planning to make similar leaps.
How will Sterns make her giant jump. First, she’ll climb into a cabin hanging from a balloon the size of a football field. Then the balloon will take her high onto the stratosphere-the layer of Earth’s atmosphere 12 to 50 kilometers above the planet. “The ascent will take two and a half to three hours,” said Sterns. “I’ll be wearing a fully pressurized, temperature-controlled space suit.”
At 40 kilometers Sterns will be able to see the gentle curve of Earth and the blackness of space over head. Then she’ll unclip herself from the cabin and dive headfirst, like a bullet, into the atmosphere, “In 30 seconds, I’ll be going Mach speed,” said Sterns.
For high dive, astronaut escape suits are a key to success. Current pilot and astronaut escape suits are guaranteed only a maximum altitude of 21 kilometers DEL Rosso, a NASA engineer of spacesuits and life-support systems, said the suit designed for Stern’s jump could serve as a model for the lethal environment of higher climbs. It will handle several major hazards. The first hazard is oxygen-deficient air. Any person without an additional oxygen supply at 40 kilometers would die within three to five seconds. The second hazard is low atmospheric pressure. Atmospheric pressure is much lower at high altitudes than it is at sea level. The low atmospheric pressure of the upper stratosphere causes the gases in body fluids to fizz out of solution like soda bubbles. In short, blond boils. Other hazards include temperatures as low as- 55 degrees Celsius, flying debris, and solar radiation.
For Sterns to survive, her spacesuit will have to protect her from all of these hazards. “A spacesuit is like a one-person spaceship,” Del Rosso explained. “You have to bake everything you need in a package that’s light enough, mobile enough, and tough enough to do the job. You can’t exist without it.”
Looking to the Future 展望未来
When a magazine for high-school students asked its readers what life would be like in twenty years, they said: Machines would be run by solar power. Buildings would rotate so they would follow the sun to take maximum advantage of its light and heat. Walls would “radiate light ” and “change color with the push of a button.” Food would be replaced by pills. School would be taught “by electrical impulse while we sleep.” Cars would have radar. Does this sound like the year 2000? Actually, the article was written in 1958 and the question was, “what will life be like in 1978?”
The future is much too important to simply guess about, the way the high school students did, so experts are regularly asked to predict accurately. By carefully studying the present, skilled businessmen, scientists, and politicians are supposedly able to figure out in advance what will happen. But can they? One expert on cities wrote: cities of the future would not be crowded, but would have space for farms and fields. People would travel to work in “airbuses”, large all-weather helicopters carrying up to 200 passengers. When a person left the airbus station he could drive a coin-operated car equipped with radar. The radar equipment of cars would make traffic accidents “almost unheard of”. Does that sound familiar? If the expert had been accurate it would, because he was writing in 1957. his subject was “the city of 1982”.
If the professionals sometimes sound like high-school students, it’s probably because future study is still a new field. But economic forecasting, or predicting what the economy will do, has been around for a long time. It should be accurate, and generally it is. But there have been some big mistakes in this field, too. In early 1929, most forecasters saw an excellent future for the stock market. In October of that year, the stock market had its worst losses ever, ruining thousands of investors who had put their faith in financial foreseers.
One forecaster knew that predictions about the future would always be subject to significant errors. In 1957, H.J. Rand of the Rand Corporation was asked about the year 2000, “Only one thing is certain, ” he answered. “children born today will have reached the age of 43.”
Mobile phones移动电话
Mobile phones should carry a label if they proved to be a dangerous source of radiation, according to Robert Bell, a scientist. And no more mobile phone transmitter tower should be built until the long-term health effects of the electromagnetic radiation they emit is scientifically evaluated, he said. “nobody’s going to drop dead overnight but we should be asking for more scientific in formation,” Robert Bell said at a conference on the health effects of low-level radiation. “if mobile phones are found to be dangerous, they should carry a warning label until proper shields can be devised,” he said.
A report widely circulated among the public says that up to now scientists do not really know enough to guarantee there are no ill-effects on humans from electromagnetic radiation. According to Robert Bell, there are 3.3 million mobile phones in Australia alone and they are increasing by 2,000 a day. By the year 2000 it is estimated that Australia will have 8 million mobile phones: nearly one for every two people.
As well, there are 2,000 transmitter towers around Australia, many in high density residential areas. For example, Telstra, Optus and Vodaphone build their towers where it is geographically suitable to them and disregard the need of the community. The electromagnetic radiation emitted from these towers may have already produced some harmful effects on the health of the residents nearby.
Robert Bell suggests that until more research is completed the Government should ban construction of phone towers from within a 500 metre radius of school grounds, child care centers, hospitals, spots playing fields and residential areas with a high percentage of children. He says there is emerging evidence that children absorb low-level radiation at a rate more than three times that of adults. He adds that there is also evidence that if cancer sufferers are subjected to electromagnetic waves the growth rate of the disease accelerates.
Robert Bell calls on the major telephone companies to fund adequate research and urges the Government to set up a wide ranging inquiry into possible health effects.
Reinventing the Table重新发明元素表
An earth scientist has rejigged the periodic table to make chemistry simpler to teach to students.
There have been many attempts to redesign the periodic table since Dmitri Mendeleev drew it up in 1871. But Bruce Railsback from the University of Georgia say she is the first to create a table that breaks with tradition and shows the ions of each element rather than just the elements themselves.
“I got tired of breaking my arms trying to explain the periodic table to earth students,” he says, criss-crossing his hands in the air and pointing to different bits of a traditional table. Railsback has still ordered the elements according to the number of protons they have. But he has added contour lines to charge density, helping to explain which ions react with which.
“Geochemists just want an intuitive sense of what’s going on with the elements,” says Albert Galy from the University of Cambridge. “I imagine this would be good for undergraduates.”
Railsback has listed some elements more than one. He explains that sulphur, for example, shows up in three different spots-one for sulphide, which is found in minerals, one for sulphite, and one for sulphate, which is found in sea salt, for instance.
He has also included symbols to show which ions are nutrients, and which are common in soil or water. And the size of element’s symbol reflects how much of it is found in the Earth’s crust.
Stonehenge巨石阵
Stonehenge, the mysterious ring of ancient monoliths from the dawn of Britain’s proud civilization, could be the work of a central European immigrant, archaeologists said not long ago in a shock statement, an early Bronze Age archer, whose grave was discovered near the stone circle last year, may have helped build the monument. And tests on the chemical components of his tooth enamel showed he grew up in the region that is now known as Switzerland. Or he might have brought up in a region neighboring Switzerland, such as southern Germany or western Austria
The archer “would have been a very important person in the Stonehenge area,” said Andrew Fitzpatrick, Wessex Archaeology’s project manager. “It is fascinating to think that someone from abroad could have played an important part in the construction of Britain’s most famous archaeological site. ”
The 4,000-year-old man was identified as an archer because of the flint arrowheads found by his body, along with other artifacts belonging to the Beaker Culture in the Alps during the Bronze Age. The artifacts found in his rich grave discovered about 5 kilometers from Stonehenge indicated he was obviously a very prominent man. Though it could be coincidence that the man lived close to Stonehenge at about the time the great stones were put in place, archaeologists suspect that he was involved in constructing the monument. The archer, dubbed “the king of Stonehenge” by the British press, lived around 2300 B.C., about the time the great stone circle was formed in Amesbury, 120 kilometers southwest of London.
The splendid artifacts found in his grave indicated he was a man of wealth, leading archaeologists to speculate he was an important dignitary involved in the monument’s creation/ Stonehenge was built about the time the rich Beaker Culture came to Britain. And people of that time would have been able to communicate in early Celtic tongues.
The archer was between 35 and 45 years old when he died. He was strongly built but suffered an accident a few years before his death that severed his left knee cap. Truman said the cause of death was not known, but it could have been a bone infection caused by his leg injury.
Archaeologists also found the grave of a younger man, aged 20 to 25, nearby. He and the archer shared an unusual bone structure in their feet . this indicated they were related and were possibly father and son. Tests on the younger man’s tooth enamel showed that he grew up in Britain. The archaeologists thus speculated the archer lived in Britain for many years and had a family, and was not just passing through..
Sleeping Giant沉睡的巨人
Right now, an eruption is brewing in Yellowstone National Park. Sometime during the next two hours, the park’s most famous geyser, old Faithful, will begin gurgling boiling water and steam. Then, an enormous fountain will shoot high into the air.
Old Faithful is not only a spectacular sight; it’s also a constant reminder that Yellowstone sits on one of the largest volcanoes in the world. If you’ve never heard of Yellowstone’s volcano, you’re not alone. The volcano is so inconspicuous that few people know it exists. Yet it has erupted three times during the last 2 million years. And one of those eruptions spewed enough volcanic ash and other debris to blanket half the United States.
Yellowstone’s volcano is sometimes called a “supervolcano,” or extremely large and explosive caldera volcano. Three calderas make up more than a third of Yellowstone National Park. This supervolcano formed over a hot spot, an extremely hot area in Earth’s mantle. John Valley, a volcano professor, said that as the crust moves across a hot spot, the hot spot melts a section of the plate moving over it, forming “one volcano after another.”
The Yellowstone hot spot melts thick continental crust, which any cause catastrophic eruptions. According to experts the eruptions that created each of the three calderas in and around Yellowstone National Park were larger than any other volcanic eruption in recorded history. The most recent eruption, which happened 640,000 years ago, produced at least 1,000 cubic kilometers of ash and debris, which blanketed most of the western half of the United States. The first Yellowstone eruption, 2 million years ago released more than double that amount of ash and debris.
Geological evidence shows Yellowstone has blown its stack every 700,000 years or so. “If nature were truly that regular and reliable, we would be due for another eruption soon,” said Valley. “However, these processes are subject to variability, so we don’t really know when the next eruption will happen.”
While the active geologist processes at Yellowstone do pose some risk to the pubic, they also make it a unique treasure. It is the volcanic energy that powers the geysers and hot springs, creates the mountains and canyons, and generates the unique ecosystems that support Yellowstone’s diverse wildlife.
The world’s longest bridge世界上最长的桥
Rumor has it that a legendary six-headed monster lurks in the deep waters of the Tyrrhenian Sea between Italy and the island of Sicily. If true, one day you might spy the beast while zipping across the Messina. When completed in 2010, the world’s longest bridge will weigh nearly 300,000tonw-equivalent to the iceberg that sank the Titanic and stretch 5 kilometers long. “that’s nearly 50 percent longer than any other bridge ever built,” says structural engineer Shane Rixon.
What do the world’s longest bridges have in common? They’re suspension bridges, massive structures built to span vast water channels or gorges. A suspension bridge needs just two towers to shoulder the structure’s mammoth weight, thanks to hefty supporting cables slung between the towers and anchored firmly in deep pools of cement at each end of the bridge. the Messina Strait Bridge will have two 54,100-ton towers, which will support most of the bridge’s load. The beefy cables of the bridge, each 1.2 meter in diameter, will hold up the longest and widest bridge deck ever built.
When construction begins on the Messina Strait Bridge in 2005, the first job will be to erect two 370 meter-tall steel towers. The second job will be to pull two sets of steel cables across the strait, each set being a bundle of 44,352 individual steel wires. Getting these cables up will be something. It’s not just their length-totally 5.3kilometers-but their weight. They will tip up the scales at 166,500tons-more than half the bridge’s total mass.
After lowering vertical “suspender” cables from the main cables, builders will erect a 60-meter-wide 54,630-ton steel roadway, or deck-wide enough to accommodate 12 lanes of traffic. The deck’s weight will pull down on the cables with a force of 70,500tons. In return, the cables yank up against their firmly rooted anchors with a force of 139,000tons-equivalent to the weight of about 100,000cars. Those anchors are essential. They’re what will keep the bridge from going anywhere.
Tests Show Women Suited for Space Travel妇女更适合太空飞行
Between 1977 and 1981, three groups of American women, numbering 27 in all, between the age of 35 and 65, were given month-long tests to determine how they would respond to conditions resembling those aboard the space shuttle.
Though carefully selected from among many applicants, the women were volunteers and the pay was barely above the minimum wage. They were not allowed to smoke or drink alcohol during the tests, and they were expected to tolerate each other’s company at close quarters for the entire period. Among other things they had to stand pressure three times the force of gravity and carry out both physical and mental tasks while exhausted from strenuous physical exercise. At the end of ten days, they had to spend a further twenty days absolutely confined to bed, during which time they suffered backaches and other discomforts, and when they were finally allowed up, the more physically active women were especially subject to pains due to a slight calcium loss.
Results of the tests suggest that women will have significant advantages over men in space. They need less food and less oxygen and they stand up to radiation better. Men’s advantages in terms of strength and stamina, meanwhile, are virtually wiped out by the zero-gravity condition in space.
Watching Microcurrents Flow观察微电流流程
We can now watch electricity as it flows through even the tiniest circuits. By scanning the magnetic field generated as electric currents flow through objects physicists have managed to picture the progress of the currents. The technology will allow manufacturers to scan microchips for faults, as well as revealing microscopic defects in anything from aircraft to banknotes.
Gang Xiao and Ben Schrag at Brown University in Providence, Rhode Island, visualize the current by measuring subtle changes in the magnetic field of an object and converting the information into a color picture showing the density of current each point.
Their sensor is adapted from an existing piece of technology that is used to measure large magnetic fields in computer hard drives. “We redesigned the magnetic sensor to make it capable of measuring very weak changes in magnetic fields,” says Xiao.
The resulting device is capable of detecting a current as weak as 10 microamperes, even when the wire is buried deep within a chip, and it shows up features as small as 40 nanometers across.
At present, engineers looking for defects in a chip have to peel off the layers and examine the circuits visually; this is one of the obstacles to making chips any smaller. But the new magnetic microscope is sensitive enough to look inside chips and reveal faults such as short circuits, nicks in the wires or electro migration-where a dense area of current picks up surrounding atoms and moves them along. “It is like watching a river flow,” explains Xiao.
As well as scanning tiny circuits, the microscope can be used to reveal the internal structure of any object capable of conducting electricity. For example, it could look directly at mjcroscopic cracks in an aeroplane’s fuselage, faults in the metal strip of a forged banknote or bacteria in a water sample. The technique cannot yet pick up electrical activity in the human brain because the current there is too small, but Xiao doesn’t rule it out in the future. “I can never say never,” he says.
Although the researchers have only just made the technical details of the microscope public, it is already on sale, from electronics company Micro Magnetics in Fall River. Massachusetts. It is currently the size of a refrigerator and takes several minutes to scan a circuit, but Xiao and Schrag are working to shrink it to the size of a desktop computer and cut the scanning time 30 seconds.
六、完型填空：
A biological clock生物钟
Every living thing has what scientists call a biological clock that controls behavior. The biological clock tells plants when to form flowers. And when the flowers should open. It tells insects when to leave the protective cocoon and fly away, and it tells animals and human beings when to eat, sleep and wake.
Events outside the plant and animal affect the actions of some biological clocks. Scientists recently found, for example, that a tiny animal changes the color of its fur because of the number of hours of daylight. In the short days of winter, its fur becomes white. The fur becomes gray brown in color in the longer hours of daylight in summer.
Inner signals control other biological clocks. German scientists found that some kind of internal clock seems to order birds to begin their long migration flight twice each year. Birds prevented from flying become restless when it is time for the trip, but they become calm again when the time of the flight has ended.
Scientists say they are beginning to learn which parts of the brain contain biological clocks. An American researcher, martin Moorhead, said a small group of cells near the front of the brain seems to control the timing of some of our actions. These cells tell a person when to awaken, when to sleep and when to seek food. Scientists say there probably are other biological clock cells that control other body activities.
Dr. Moorhead is studying how our biological clocks affect the way we do our work. For example, most of us have great difficulty if we must often change to different work hours. It can take many days for a human body to accept the major change in work hours. Dr. Moorhead said industrial officials should have a better understanding of biological clocks and how they affect workers. He said such understanding could cut sickness and accidents at work and would help increase a factory’s production.