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6篇极像原文的文章 感谢gitarrelieber

1.1.3. 《灰色经济》的英语原版出处：
The Economist (@ 18 June 2004)

If so, then depending on your local laws you may have been participating in what economists call the "informal" or "grey" economy. In essence, the grey economy consists of legal activities whose participants fail to pay tax or comply with regulations. The informal (or "underground" or "parallel" economy) is often taken to mean something broader, including illegal activities such as prostitution and drug dealing as well, although there is no agreed strict definition.

The grey economy is often thought of as something found at the margins of poor countries, such as a hawker stand in Thailand or a roadside vendor in Ghana. But that is misleading. Although it represents a greater share of total output in poor countries, it exists in rich and poor places alike. Recent research suggests that the grey economy is growing. Moreover, a new study suggests that it may be slowing the overall economic growth of developing countries.

By its very nature, the informal economy's size in any country is hard to observe. In a paper published a couple of years ago ("Size and Measurement of the Informal Economy in 110Countries Around the World," World Bank Working Paper, July 2002), Friedrich Schneider, of the Johannes Kepler University of Linz, exhaustively examined the ways of estimating it. There are two basic approaches. The first is direct: you could ask people whether they dodge taxes, or look at the results of spot tax-audits. However, people are unlikely to confess to breaking the law, and tax inspectors do not usually check on a random sample of the population. So the second method, indirect detective-work, is better. For example, you might compare data on cash transactions or electricity consumption with official output figures. If the use of cash or electricity is growing much faster than the measured economy, this might indicate that the informal share of total activity is rising.

Using such techniques, Mr. Schneider estimated that the informal economy in developing countries in 2000 was equivalent to 41% of their official GDP. In Zimbabwe, the figure was 60%. In Brazil and Turkey, around half of non-farm workers are in the informal sector. In OECD countries the share of the informal economy was lower, but far from negligible, at 18%.

There is little mystery about why the informal economy exists. There are a lot of advantages to operating in the shadows. For a start, there are no income taxes to pay. Avoiding social-security charges, which often drive a chunky wedge between take-home pay and employers' wage bills, can both cut labour costs and thicken wage packets. People can also save a fair bit by ignoring safety, environmental and health rules, not to mention intellectual property rights.

Indeed, in cross-country comparisons, the more expensive and more complicated are taxes and regulations, the bigger is the informal economy as a share of GDP. That explains why, among rich countries, Spain, Greece, Italy and Belgium have some of the largest grey economies and why America, Canada and Switzerland have much smaller ones. In recent years, the growth in the grey market in some poor countries may owe a lot to the International Monetary Fund's austerity programs, which increase taxes and thus encourage many entrepreneurs to opt out.

A booming grey economy sounds like good news, if only because many of the officially jobless are in fact earning a living. So if the poorest are winning, who loses? The entire economy does, according to a new study by Diana Farrell of the McKinsey Global Institute. The price for having a large grey economy can be much lower productivity. Grey firms tend to be small and want to stay that way lest they come to the attention of the authorities. However, their small scale limits their ability to make the most of new technology and business practices.

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2
Moths Mimic Sounds to Survive; Science Daily (May 30, 2007)
(This research is to be published in the May 29 issue of the Proceedings of the National Academy of Sciences.)

The research was conducted by Jesse Barber, a doctoral student in biology at Wake Forest. William E. Conner, professor of biology at Wake Forest, co-authored the study.

This is the first study to definitively show how an animal species uses acoustic mimicry as a defensive strategy.

The research was conducted by Jesse Barber, a doctoral student in biology at Wake Forest. William E. Conner, professor of biology at Wake Forest, co-authored the study.

In response to the sonar that bats use to locate prey, the tiger moths make ultrasonic clicks of their own. They broadcast the clicks from a paired set of structures called “tymbals.” Many species of tiger moth use the tymbals to make specific sounds that warn the bat of their bad taste. Other species make sounds that closely mimic those high-frequency sounds.

“We found that the bats do not eat the good-tasting moths that make the similar sounds,” said Barber, who has worked on this research for four years.

In the study, other types of moths that were similar in size to the sound-emitting moths, but did not make sounds, were gobbled up by the bats.
The researcher trained free-flying bats to hunt moths in view of two high-speed infrared video cameras to record predator-prey interactions that occur in fractions of a second. He also recorded the sounds emitted from each moth, as well as the sounds made by the bats.

All the bats quickly learned to avoid the noxious moths first offered to them, associating the warning sounds with bad taste. They then avoided a second sound-producing species even though it was not chemically protected. This is similar to the way birds avoid butterflies that look like the bad-tasting Monarch.

The two species of bats used were big brown bats and red bats. Barber raised the bats in the lab so behavior learned in the wild would not influence the results of the experiment.

Barber said anecdotal observations have suggested that animals such as snakes, owls and bees use acoustic mimicry. This study takes the next step and provides the definitive experimental evidence for how mimicking sounds helps an animal survive.

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2.1.12. 蝙蝠和蛾的英文文献

1
Bats are active at nights. Most of them hunt for insects by sending high pitched sounds (Sound is made by vibrating things. The faster things vibrate, the higher the pitch. The rate at which vibrations are produced is, pitch).

Bats produce sounds by their mouth or nose. When the sound waves hit an object an echo comes back. The bat’s ears have a complex set of folds that help determine the position of the object. Based on the intensity of echo, a bat can know how big an object is. A smaller object will reflect less sound waves and the echo will be small. If the object is an insect, the bat can know in which direction the insect is moving. A lower pitch echo will mean that the insect is moving away and a higher pitch will mean the opposite. This mechanism is known as echolocation. Bats navigate themselves and hunt insects by echo locating objects and prey. A wide variety of insects are eaten by bats, except Tiger moths.

Tiger moths belong to the family Arctidae. They are world wide in distributio0n. Most of them are night fliers. They derive their name from their bold contrasting coloration of gold and black, resembling the stripes of a tiger. The wings are thin and elegant, having fine scales and a span of ¾ to 3 inches. The larvae of Tiger moths, the woolly bears feed on a variety of plants and accumulate toxins in their skin. Adult moths acquire these toxins. They are therefore bad tasting insects.

The Tiger moth has survived bat predation over millions of years. The moth has a special organ called Tymbal organ on its meta thorax. This organ has thin membranes which are vibrated to produce ultrasonic sounds (high pitch sounds similar to bats that humans cannot hear).The moth has also a Tympanal organ on the thorax which functions as a hearing organ.

With this apparatus, the Tiger moth is capable of hearing bat’s sounds. It evades the bat, by a series of evasive maneuvers of loops, spirals and dives. It produces high frequency click sounds or squeaks. These sound waves perceived by the bat as multiple echoes, leave the bat confused and unable to locate or target the moth.

It was earlier believed that the Tiger moth jams the sonar system of bats by its ultrasounds. But experiments have revealed that the Tiger moth is more intent on making its presence felt by its sounds and warn the predator of its toxins and bad taste. It is more a chemical message to bats to seek their dinner somewhere else.

The aerial battles of Tiger moths and bats continue to baffle scientists.

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2.2.2. 关于地球降温的参考文章：
The geologic record tells a story in which continents removed the greenhouse gas carbon dioxide from an early atmosphere that may have been as hot as 70 degrees Celsius (158 F). At this time the Earth was mostly ocean. It was too hot to have any polar ice caps. Lowe hypothesizes that rain combined with atmospheric carbon dioxide to make carbonic acid, which weathered jutting mountains of newly formed continental crust. Carbonic acid dissociated to form hydrogen ions(离子), which found their way into the structures of weathering minerals, and bicarbonate, which was carried down rivers and streams to be deposited as limestone(石灰石) and other minerals in ocean sediments.
...... both caused further cooling, perhaps a temperature drop of 40 to 50 degrees Celsius. and the Earth's first glaciation may have occurred 2.9 billion years ago
New continents formed and weathered, again taking carbon dioxide out of the atmosphere: About 3 billion years ago, maybe 10 or 15 percent of the Earth's present area in continental crust had formed. By 2.5 billion years ago, an enormous amount of new continental crust had formed -- about 50 to 60 percent of the present area of continental crust. During this second cycle, weathering of the larger amount of rock caused even greater atmospheric cooling, spurring a profound glaciation about 2.3 to 2.4 billion years ago.
"So eventually the carbon dioxide level climbs again," Lowe says. "It may never return to its full glorious 70 degrees Centigrade level, but it probably climbed to make the Earth warm again."
Continents played key role in collapse and regeneration of Earth's early greenhouse, geologists say
If a time machine could take us back 4.6 billion years to the Earth's birth, we'd see our sun shining 20 to 25 percent less brightly than today. Without an earthly greenhouse to trap the sun's energy and warm the atmosphere, our world would be a spinning ball of ice. Life may never have evolved.
But life did evolve, so greenhouse gases must have been around to warm the Earth. Evidence from the geologic record indicates an abundance of the greenhouse gas carbon dioxide. Methane probably was present as well, but that greenhouse gas doesn't leave enough of a geologic footprint to detect with certainty. Molecular oxygen wasn't around, indicate rocks from the era, which contain iron carbonate instead of iron oxide. Stone fingerprints of flowing streams, liquid oceans and minerals formed from evaporation confirm that 3 billion years ago, Earth was warm enough for liquid water.
Now, the geologic record revealed in some of Earth's oldestrocks is telling a surprising tale of collapse of that greenhouse -- and its subsequent regeneration. But even more surprising, say the Stanford scientists who report these findings in the May 25 issue of the journal Geology, is the critical role that rocks played in the evolution of the early atmosphere.
"This is really the first time we've tried to put together a picture of how the early atmosphere, early climate and early continental evolution went hand in hand," said Donald R. Lowe, a professor of geological and environmental science who wrote the paper with Michael M. Tice, a graduate student investigating early life. NASA's Exobiology Program funded their work. "In the geologic past, climate and atmosphere were really profoundly influenced by development of continents."
The record in the rocks
To piece together geologic clues about what the early atmosphere was like and how it evolved, Lowe, a field geologist, has spent virtually every summer since 1977 in South Africa or Western Australia collecting rocks that are, literally, older than the hills. Some of the Earth's oldest rocks, they are about 3.2 to 3.5 billion years old.
"The further back you go, generally, the harder it is to find a faithful record, rocks that haven't been twisted and squeezed and metamorphosed and otherwise altered," Lowe says. "We're looking back just about as far as the sedimentary record goes."
After measuring and mapping rocks, Lowe brings samples back to Stanford to cut into sections so thin that their features can be revealed under a microscope. Collaborators participate in geochemical and isotopic analyses and computer modeling that further reveal the rocks' histories.

The geologic record tells a story in which continents removed the greenhouse gas carbon dioxide from an early atmosphere that may have been as hot as 70 degrees Celsius (158 F). At this time the Earth was mostly ocean. It was too hot to have any polar ice caps. Lowe hypothesizes that rain combined with atmospheric carbon dioxide to make carbonic acid, which weathered jutting mountains of newly formed continental crust. Carbonic acid dissociated to form hydrogen ions, which found their way into the structures of weathering minerals, and bicarbonate, which was carried down rivers and streams to be deposited as limestone and other minerals in ocean sediments.
Over time, great slabs of oceanic crust were pulled down, or subducted, into the Earth's mantle. The carbon that was locked into this crust was essentially lost, tied up for the 60 million years or so that it took the minerals to get recycled back to the surface or outgassed through volcanoes.
The hot early atmosphere probably contained methane too, Lowe says. As carbon dioxide levels fell due to weathering, at some point, levels of carbon dioxide and methane became about equal, he conjectures. This caused the methane to aerosolize into fine particles, creating a haze akin to that which today is present in the atmosphere of Saturn's moon Titan. This "Titan Effect" occurred on Earth 2.7 to 2.8 billion years ago.
The Titan Effect removed methane from the atmosphere and the haze filtered out light; both caused further cooling, perhaps a temperature drop of 40 to 50 degrees Celsius. Eventually, about 3 billion years ago, the greenhouse just collapsed, Lowe and Tice theorize, and the Earth's first glaciation may have occurred 2.9 billion years ago.
The rise after the fall
Here the rocks reveal an odd twist in the story -- eventual regeneration of the greenhouse. Recall that 3 billion years ago, Earth was essentially Waterworld. There weren't any plants or animals to affect the atmosphere. Even algae hadn't evolved yet. Primitive photosynthetic microbes were around and may have played a role in the generation of methane and minor usage of carbon dioxide.
As long as rapid continental weathering continued, carbonate was deposited on the oceanic crust and subducted into what Lowe calls "a big storage facility ... that kept most of the carbon dioxide out of the atmosphere."
But as carbon dioxide was removed from the atmosphere and incorporated into rock, weathering slowed down ú there was less carbonic acid to erode mountains and the mountains were becoming lower. But volcanoes were still spewing into the atmosphere large amounts of carbon from recycled oceanic crust.
"So eventually the carbon dioxide level climbs again," Lowe says. "It may never return to its full glorious 70 degrees Centigrade level, but it probably climbed to make the Earth warm again."
This summer, Lowe and Tice will collect samples that will allow them to determine the temperature of this time interval, about 2.6 to 2.7 billion years ago, to get a better idea of how hot Earth got.
New continents formed and weathered, again taking carbondioxide out of the atmosphere. About 3 billion years ago, maybe 10 or 15 percent of the Earth's present area in continental crust had formed. By 2.5 billion years ago, an enormous amount of new continental crust had formed -- about 50 to 60 percent of the present area of continental crust. During this second cycle, weathering of the larger amount of rock caused even greater atmospheric cooling, spurring a profound glaciation about 2.3 to 2.4 billion years ago.
Over the past few million years we have been oscillating back and forth between glacial and interglacial epochs, Lowe says. We are in an interglacial period right now. It's a transition ú and scientists are still trying to understand the magnitude of global climate change caused by humans in recent history compared to that caused by natural processes over the ages.
"We're disturbing the system at rates that greatly exceed those that have characterized climatic changes in the past," Lowe said. "Nonetheless, virtually all of the experiments, virtually all of the variations and all of the climate changes that we're trying to understand today have happened before. Nature's done most of these experiments already. If we can analyze ancient climates, atmospheric compositions and the interplay among the crust, atmosphere, life and climate in the geologic past, we can take some first steps at understanding what is happening today and likely to happen tomorrow."