1   次の英文はDiscover,vol.24,no.7(July 2003)に掲載された, "Trun Down the Lights"という題の記事です。この文章をよく読んで,問題1から 5に答えなさい。解答は解答用紙の指定された欄に記入すること。


On March 31, 1880, the good people of Wabash, Indiana (population 320), launched a technological revolution. On top of the town's courthouse. they mounted two bars with a 3,000-candlepower bulb at both ends of each. They then started up a steam engine to generate electricity, and at 8 p.m., flipped a switch. Sparks showered, and Wabash became the first electrically lit city in the world. "The strange, weird light, exceeded in power only by the sun, rendered the square as light as midday," one witness reported. "Men fell on their knees, groans were uttered at the sight, and many were dumb with amazement."

A century and a quarter later, electric light turns night into day around the globe. In the first world atlas of artificial night-sky brightness, based on high-resolution* satellite data and released in 2001, the heavily developed urban areas of Japan, Western Europe, and the United States blaze like amusement parks. We flood the heavens with so much artificial light that nearly two-thirds of the world's people can no longer see the Milky Way. On a clear, dark night dar from light-polluted skied, roughtly 2,500 stars can be seen by the naked eye. For people living in the suburbs of New York, that number decreases to 250; residents of Manhattan are lucky to see 15. Moreover, as the stars fade from view, more and more research is suggesting that excessive exposure to artificial night light can alter basic biological rhythms in animals, change predator-prey relationships, and even trigger deadly hormonal imbalances in humans.

(ア)Many creatures are genetically programmed to navigate by the dim glow of the stars and the moon. For them, night lights can be deadly: Michael Mesuren, fouder of the Toronto=based Fatal Light Awareness Program, estimates thet 100 million songbirds crash into lit buildings in North America each year. Likewise, artificial light is a source of confusion for the relatives of butterflies taht are active at night. Rod Crawford. of the Burke Museun at the University of Washington, believes that light pollution may be the leading cause, after habitat loss, of the decline of the spectacular gian silk moths that were once a source of summer visual delight. "The farther form lights and altered habitats you get. the more moths you find," he says.

Kenneth Frank, a Philadelphia physician who also studies insects, says that light-lured moths often miss their bries oppotunities to mate, or are killed by larger, light-stalking creatures. (イ)Bright lights also disrupt migration routes, confining some moth populations to isolated islands of darkness. But Frank admits that the situation of the mothes is unlikely to cause public concern. "Never argue against something on behalf of moths." he warns. "People will just laught at you. Talk about ecosystems instead."

And ther is plenty to talk about. Just ask Marianne Moore of Wellesley College who studies the life cycles of zooplankton-little creatures that rise toward the surface of nearby lakes at night to feed on algae* and then descend by day to escape predators. (1)Her research suggests that the sky glow reflected from streetlughts prompts the tiny organisms to remain well below the surface. This deprives the zooplankton of nutrients and allows excessive algae to grow, which in turn harms other plants living in the water. At the same time, artificial light appears to interfere with the mating habits of the little lake creatures. "Lunar cues are very important for reproduction," Moore says, and sky glow simulates those cues.

(ウ)Many people might consider such small changes in the environment a small price to pay for brightly lit communities. But new medical data suggest humans are not immune to light pollution. In 2001 the Journal of the National Cancer Institute published who studies that the editors argued revealed "an association between exposure to light at night and breast cancer risk," with "alarming" implications. Scientists at the Fred Hutchinson Cancer Reaserch Center in Seattle inteviewed 1,606 women and found a 60 percent greater rate of breast cancer among those who worked at night; the risk increased with the number of years on the night shift and night hours worked per week. Researchers at Brigham and Women's Hospital in Boston reviewed the health histories of 78,562 nurses and found a lower but still significant correlation: (2)Those with 1 to 29 years on the night shift showed, on average, an 8 percent increase in breast cancer; those with 30 or more years showed a 35 percent increase.

Other studies have shown that light striking the eyes, even during sleep. can reduce production of melatonin, a hormone that helps regulate daily cycles in the body. Melatonin also has anti-cancer properties, and for some mammals (3)it has been shown to suppress a chemical which may increase the risk of breaat cancer. "Light is a drug." says Russel J. Reiter, a doctor at the University of Texas Healthe Science Center who has reaserched the disease-preventing properties of melatonin. "By abusing (4)it, we compromise our health."

Not all lights have equal optical and biological effects, even if they shine with equal brightness. Fluorescent* bulbs, as well as the two tyoes of bulbs often used in sports stadium lighting, emit a lot of invisible ultraviolet light, which is useless for illumination but interferes with equipment used by astronomers. Traditional incandescent* bulbs emit a lot of infrared light, which makes them hot and very inefficient. All these, as well as the increasingly popular high-pressure sodium* bulbs used in street lamps, emit light over a wide spectrum. This makes their light seem more atural and also makes it visible and attractive to moths, birds, and other animals. By contrast, the efficient low=pressure sodium bulbs now used in some street lamps emit only a narrow range of yellow light. This minimizes ecological disruptions, since creatures don't preceive low=pressure sodium as natural light. Moths, for example, don't seem to notice it at all. Some cities near large observatories have switched their streetlights to low-pressure sodium because astronomers can filter it out. But at least one, San Fiego, decided to switch back to the prior type. after residents complained that the yellow light made them uncomfortable.

One problem with illiminating streets with soft yellow light is that it goes against an assumption made by many officials, businesses, and homeowners: that intense, bright light naturally means more visibility and more safety. Elizabeth Alvarez, the International Dark=Sky Association's associate director, counters with photos of bright streetlights casting deep shodows where bad guys could hide. "Glare does not help visibility!" she says. "Too much light is blinding."

Alvarez and other dark-sky advocates contend that communities could take a number of other practical steps to reduce the amout of light pollution. They suggest pointing light only where it's needed, shielding lights, and replacing rounded lenses that scatter light with flat-bottomed (5)ones that don't. They also suggest lowering most bulb wattages and eliminating unnecessary lights placed by engineers who never plant one light post when two will do.

Last year, Calgary, Alberta (population 904,987), began trying some of these procedures. Engineers downsized the high-pressure sodium lights in several neightborhoods, substituted 100-watt for 200-watt bulbs and 150-watters for 250s, and installed flat lenses that focus the light downward. Street-lighting coordinator Barry Poon says elderly citizens complained that less lighting would boost crime. "But police told us there's no correlation between light levels and crime. Breaking and enterings actually occur in daytime when people aren't in." The results agreed: The crime rate in the areas with the new lights went unchanged. Now, Poon reports, "I'd say we get 10 positive responses for every negative one." Budget watchers were also pleased; the conversion, which will cost 4.5 million U.S. dollars, will save $1.3 million in electricity each year.

Ironically, the hope of saving money-about $800 a year-was what prompted the thrifty town faters of Wabash to replace their glowing gaslights with glaring electrics 123 years ago. These days, staff scientist Evan Mills of the U.S Department of Energy's Lawrence Berkely National Laboratory calculates that people around the world use more than 2,200 trillion watt-hours of electricity every year for lighting, at a cost of about $200 billion. Mills estimates that this consumption could be cut in half with more efficient equipment, better design, and appropriate light levels. That might also double our delight in the natural wonders of the light.


algae(pl.)>alga 藻

fluorescent bulbs 蛍光灯

high-resolution 高解像(度)の

incandescent bulbs 白熱電球

sodium bulbs ナトリウム灯

1      Decide wheter the following statements are true or false and circle the correct answer.

(1)   Three thousand candles were used to light up the town of Wabash in 1880.

(2)   According to the article, amusement parks can be clearly seen at night via satellite.

(3)   More than one third of the world's people can still see the Milky Way.

(4)   According to Marianne Moore, light pollution prevents zooplankton from rising to the surface of the water, and this may be unhealthy for them.

(5)   Although there are different types of lightbulbs which produce different types of light, the only concern for biological effects is the overall brightness of the light that is produced.

(6)   Lamps that emit light over a wide spectrum produce light that seems more natural to insects and other animals.

(7)   Bright lights may help wrongdoers because they can hide in the shodows created by bright lights.

(8)   In Calgary, Alberta, crime rates went up when they started to use less lighting.

(9)   People in the United States use more than 2,200 trillion watt-hours of electricity each year for lighting.

(10)   The author implies that human beings are much less affected by light pollution than most people believe.

2      What do the following words, which are underlined in the text, refer to? Answer in English.

(1)   Her

(2)   Those

(3)   it

(4)   it

(5)   ones

3      Answer the following questions in English.

(1)   According to a scientist quoted in the article, what are the two most likely reasons that there are fewer giant silk mothes today than there were in the past?

(2)   In your own words, explain why Kenneth Frank recommends talking about "ecosystems" rather than the problems faced by moths.

(3)   Calgary implemented a number of procedures for reducing light pollution. Including the initial costs, over the first 5 years, how much will the program cost, or how much money will be saved (as compared to if they had not mede any changes)? Be sure to specify if your answer is the amout saved or if it is the additional cost.

4      下線部(ア)から(ウ)を日本語に訳しなさい。

5      人工光が野生生物および人間に与える影響はどのようなものですか。また、その対策にはどのようなものがありますか。この文章で論じられている具体的な 影響例と対策案を、日本語500字以内にまとめなさい。

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