Questões de Inglês

RADIATION AND EVOLUTION

1 THE disaster last year at the Fukushima Dai-ichi nuclear power plant, caused by an earthquake and tsunami, scored seven on the International Nuclear and Radiological Event Scale (INES). No worse rating exists. Radiation is harmful to living things, yet the long-term effects of persistently high levels of background radiation on ecosystems are poorly understood. With this in mind, a team led by Timothy Mousseau of the University of South Carolina and Anders Moller of the University of Paris-Sud set out to compare bird species dwelling near the Fukushima plant with those living at the site of another nuclear incident that scored a seven on the INES: the Ukrainian town of Chernobyl, where disaster struck in 1986. Remarkably, they found that some species seem to develop a tolerance for radioactivity over time.

2 Fukushima and Chernobyl are more than 7,000km (4,350 miles) apart, but Dr Mousseau and his colleagues soon realised that the two sites had much in common. Both are in areas that have a temperate climate with species that have similar habits and needs. And both are surrounded by a mixture of farmland and forest. Upon closer examination the researchers found that 14 species of bird lived in both regions, including the barn swallow, great tit, great reed warbler, buzzard and Eurasian jay. With so many similarities between the two places, a comparison of the biological responses to radiation in each (recent in Fukushima; long-term in Chernobyl) would surely be illuminating.

3 To do this, during July 2011, the researchers counted and identified birds at 300 locations near Fukushima that had radiation levels as low as 0.5 microsieverts per hour and as high as 35 (for comparison, dental X-rays rarely expose patients to more than 0.05 microsieverts). Then they compared these results to bird data collected in areas that had the same range of radiation levels near Chernobyl between 2006 and 2009.

4 Their results show that as radiation levels in an area rose to 35 microsieverts per hour, the average number of birds dropped by almost a third compared with the areas where radiation levels were only 0.5 microsieverts per hour. This makes sense: in those areas with a high  level of radiation, living things would tend to die or sicken and fail to reproduce. However, when researchers looked at the 14 bird species that lived in both regions, they found that the same level of radiation was associated with twice as large a drop in bird numbers in Fukushima as in Chernobyl.

5 The reasons for this are not clear. It is possible that the composition of the radionuclides are proving more dangerous to the Fukushima birds than they are to the birds near Chernobyl. But Dr Mousseau suggests a more likely explanation is that evolution has already been at work near Chernobyl, killing off individual birds that cannot cope with the background radiation and allowing the genes of those that have some tolerance to be passed on. The birds at Fukushima are only beginning to face the evolutionary challenge of living in a radioactive world.

Adapted from The Economist, March 3, 2012

RADIATION AND EVOLUTION

1 THE disaster last year at the Fukushima Dai-ichi nuclear power plant, caused by an earthquake and tsunami, scored seven on the International Nuclear and Radiological Event Scale (INES). No worse rating exists. Radiation is harmful to living things, yet the long-term effects of persistently high levels of background radiation on ecosystems are poorly understood. With this in mind, a team led by Timothy Mousseau of the University of South Carolina and Anders Moller of the University of Paris-Sud set out to compare bird species dwelling near the Fukushima plant with those living at the site of another nuclear incident that scored a seven on the INES: the Ukrainian town of Chernobyl, where disaster struck in 1986. Remarkably, they found that some species seem to develop a tolerance for radioactivity over time.

2 Fukushima and Chernobyl are more than 7,000km (4,350 miles) apart, but Dr Mousseau and his colleagues soon realised that the two sites had much in common. Both are in areas that have a temperate climate with species that have similar habits and needs. And both are surrounded by a mixture of farmland and forest. Upon closer examination the researchers found that 14 species of bird lived in both regions, including the barn swallow, great tit, great reed warbler, buzzard and Eurasian jay. With so many similarities between the two places, a comparison of the biological responses to radiation in each (recent in Fukushima; long-term in Chernobyl) would surely be illuminating.

3 To do this, during July 2011, the researchers counted and identified birds at 300 locations near Fukushima that had radiation levels as low as 0.5 microsieverts per hour and as high as 35 (for comparison, dental X-rays rarely expose patients to more than 0.05 microsieverts). Then they compared these results to bird data collected in areas that had the same range of radiation levels near Chernobyl between 2006 and 2009.

4 Their results show that as radiation levels in an area rose to 35 microsieverts per hour, the average number of birds dropped by almost a third compared with the areas where radiation levels were only 0.5 microsieverts per hour. This makes sense: in those areas with a high  level of radiation, living things would tend to die or sicken and fail to reproduce. However, when researchers looked at the 14 bird species that lived in both regions, they found that the same level of radiation was associated with twice as large a drop in bird numbers in Fukushima as in Chernobyl.

5 The reasons for this are not clear. It is possible that the composition of the radionuclides are proving more dangerous to the Fukushima birds than they are to the birds near Chernobyl. But Dr Mousseau suggests a more likely explanation is that evolution has already been at work near Chernobyl, killing off individual birds that cannot cope with the background radiation and allowing the genes of those that have some tolerance to be passed on. The birds at Fukushima are only beginning to face the evolutionary challenge of living in a radioactive world.

Adapted from The Economist, March 3, 2012

RADIATION AND EVOLUTION

1 THE disaster last year at the Fukushima Dai-ichi nuclear power plant, caused by an earthquake and tsunami, scored seven on the International Nuclear and Radiological Event Scale (INES). No worse rating exists. Radiation is harmful to living things, yet the long-term effects of persistently high levels of background radiation on ecosystems are poorly understood. With this in mind, a team led by Timothy Mousseau of the University of South Carolina and Anders Moller of the University of Paris-Sud set out to compare bird species dwelling near the Fukushima plant with those living at the site of another nuclear incident that scored a seven on the INES: the Ukrainian town of Chernobyl, where disaster struck in 1986. Remarkably, they found that some species seem to develop a tolerance for radioactivity over time.

2 Fukushima and Chernobyl are more than 7,000km (4,350 miles) apart, but Dr Mousseau and his colleagues soon realised that the two sites had much in common. Both are in areas that have a temperate climate with species that have similar habits and needs. And both are surrounded by a mixture of farmland and forest. Upon closer examination the researchers found that 14 species of bird lived in both regions, including the barn swallow, great tit, great reed warbler, buzzard and Eurasian jay. With so many similarities between the two places, a comparison of the biological responses to radiation in each (recent in Fukushima; long-term in Chernobyl) would surely be illuminating.

3 To do this, during July 2011, the researchers counted and identified birds at 300 locations near Fukushima that had radiation levels as low as 0.5 microsieverts per hour and as high as 35 (for comparison, dental X-rays rarely expose patients to more than 0.05 microsieverts). Then they compared these results to bird data collected in areas that had the same range of radiation levels near Chernobyl between 2006 and 2009.

4 Their results show that as radiation levels in an area rose to 35 microsieverts per hour, the average number of birds dropped by almost a third compared with the areas where radiation levels were only 0.5 microsieverts per hour. This makes sense: in those areas with a high  level of radiation, living things would tend to die or sicken and fail to reproduce. However, when researchers looked at the 14 bird species that lived in both regions, they found that the same level of radiation was associated with twice as large a drop in bird numbers in Fukushima as in Chernobyl.

5 The reasons for this are not clear. It is possible that the composition of the radionuclides are proving more dangerous to the Fukushima birds than they are to the birds near Chernobyl. But Dr Mousseau suggests a more likely explanation is that evolution has already been at work near Chernobyl, killing off individual birds that cannot cope with the background radiation and allowing the genes of those that have some tolerance to be passed on. The birds at Fukushima are only beginning to face the evolutionary challenge of living in a radioactive world.

Adapted from The Economist, March 3, 2012

Cosmic Background

By Marcia Bartusiak

1 One hundred fifty years ago, in 1862, the first hint arrived that the stellar universe was far stranger than anyone imagined—or could imagine. It came with the knowledge that a faint companion slowly circles Sirius, the brightest star in the nighttime sky.

2 Astronomers at the time didn’t recognize what they had uncovered. It would take decades—until the 1910s—for them to fully realize that Sirius B, as the tiny companion came to be known, was a star like no other seen before. Once its nature was revealed, though, it didn’t take long for theorists to conceive of other bizarre creatures that might be residing in the stellar zoo.

3 The story begins, not in 1862, but two decades earlier. For a number of years, the noted German astronomer Friedrich Wilhelm Bessel, director of the Königsberg Observatory, had been going through old stellar catalogs, as well as making his own measurements, to track how the stars Sirius and Procyon were moving across the celestial sky over time. By 1844 he had enough data to announce that Sirius and Procyon weren’t traveling smoothly, as expected; instead, each star displayed a slight but distinct wobble—up and down, up and down. With great cleverness, Bessel deduced that each star’s quivering walk meant it was being pulled on by a dark, invisible companion circling it. Sirius’s companion, he estimated, completed oneorbit every fifty years.

4 Bessel was clearly excited by his find; in his communication to Great Britain’s Royal Astronomical

Society he wrote, “The subject . . . seems to me so important for the whole of practical astronomy, that I

think it worthy of having your attention directed to it.”

5 Astronomers did take notice, and some tried to discern Sirius’s companion through their telescopes. Unfortunately, at the time Bessel reported his discovery, Sirius B was at its closest to gleaming Sirius, from the point of view of an observer on Earth, and thus lost in the glare. But even years later, no one wassuccessful in spotting the companion.

6 That all changed on January 31, 1862. That night in Cambridgeport, Massachusetts, Alvan Clark, the best telescope manufacturer in the United States, and his younger son, Alvan Graham Clark, were testing the optics for a new refractor they had been building for the University of Mississippi. It was going to be the biggest refracting telescope in the world. Looking at notable stars to carry out a color test of their 18.5-inch lens, the son observed a faint star very close to Sirius. This was Sirius B, a type of star now known as a “whitedwarf” because of its color and size.

Adapted from Natural History, February, 2012

Cosmic Background

By Marcia Bartusiak

1 One hundred fifty years ago, in 1862, the first hint arrived that the stellar universe was far stranger than anyone imagined—or could imagine. It came with the knowledge that a faint companion slowly circles Sirius, the brightest star in the nighttime sky.

2 Astronomers at the time didn’t recognize what they had uncovered. It would take decades—until the 1910s—for them to fully realize that Sirius B, as the tiny companion came to be known, was a star like no other seen before. Once its nature was revealed, though, it didn’t take long for theorists to conceive of other bizarre creatures that might be residing in the stellar zoo.

3 The story begins, not in 1862, but two decades earlier. For a number of years, the noted German astronomer Friedrich Wilhelm Bessel, director of the Königsberg Observatory, had been going through old stellar catalogs, as well as making his own measurements, to track how the stars Sirius and Procyon were moving across the celestial sky over time. By 1844 he had enough data to announce that Sirius and Procyon weren’t traveling smoothly, as expected; instead, each star displayed a slight but distinct wobble—up and down, up and down. With great cleverness, Bessel deduced that each star’s quivering walk meant it was being pulled on by a dark, invisible companion circling it. Sirius’s companion, he estimated, completed oneorbit every fifty years.

4 Bessel was clearly excited by his find; in his communication to Great Britain’s Royal Astronomical

Society he wrote, “The subject . . . seems to me so important for the whole of practical astronomy, that I

think it worthy of having your attention directed to it.”

5 Astronomers did take notice, and some tried to discern Sirius’s companion through their telescopes. Unfortunately, at the time Bessel reported his discovery, Sirius B was at its closest to gleaming Sirius, from the point of view of an observer on Earth, and thus lost in the glare. But even years later, no one wassuccessful in spotting the companion.

6 That all changed on January 31, 1862. That night in Cambridgeport, Massachusetts, Alvan Clark, the best telescope manufacturer in the United States, and his younger son, Alvan Graham Clark, were testing the optics for a new refractor they had been building for the University of Mississippi. It was going to be the biggest refracting telescope in the world. Looking at notable stars to carry out a color test of their 18.5-inch lens, the son observed a faint star very close to Sirius. This was Sirius B, a type of star now known as a “whitedwarf” because of its color and size.

Adapted from Natural History, February, 2012

Cosmic Background

By Marcia Bartusiak

1 One hundred fifty years ago, in 1862, the first hint arrived that the stellar universe was far stranger than anyone imagined—or could imagine. It came with the knowledge that a faint companion slowly circles Sirius, the brightest star in the nighttime sky.

2 Astronomers at the time didn’t recognize what they had uncovered. It would take decades—until the 1910s—for them to fully realize that Sirius B, as the tiny companion came to be known, was a star like no other seen before. Once its nature was revealed, though, it didn’t take long for theorists to conceive of other bizarre creatures that might be residing in the stellar zoo.

3 The story begins, not in 1862, but two decades earlier. For a number of years, the noted German astronomer Friedrich Wilhelm Bessel, director of the Königsberg Observatory, had been going through old stellar catalogs, as well as making his own measurements, to track how the stars Sirius and Procyon were moving across the celestial sky over time. By 1844 he had enough data to announce that Sirius and Procyon weren’t traveling smoothly, as expected; instead, each star displayed a slight but distinct wobble—up and down, up and down. With great cleverness, Bessel deduced that each star’s quivering walk meant it was being pulled on by a dark, invisible companion circling it. Sirius’s companion, he estimated, completed oneorbit every fifty years.

4 Bessel was clearly excited by his find; in his communication to Great Britain’s Royal Astronomical

Society he wrote, “The subject . . . seems to me so important for the whole of practical astronomy, that I

think it worthy of having your attention directed to it.”

5 Astronomers did take notice, and some tried to discern Sirius’s companion through their telescopes. Unfortunately, at the time Bessel reported his discovery, Sirius B was at its closest to gleaming Sirius, from the point of view of an observer on Earth, and thus lost in the glare. But even years later, no one wassuccessful in spotting the companion.

6 That all changed on January 31, 1862. That night in Cambridgeport, Massachusetts, Alvan Clark, the best telescope manufacturer in the United States, and his younger son, Alvan Graham Clark, were testing the optics for a new refractor they had been building for the University of Mississippi. It was going to be the biggest refracting telescope in the world. Looking at notable stars to carry out a color test of their 18.5-inch lens, the son observed a faint star very close to Sirius. This was Sirius B, a type of star now known as a “whitedwarf” because of its color and size.

Adapted from Natural History, February, 2012