VOA慢速英语 2007 0102b

VOICE ONE:

This is SCIENCE IN THE NEWS in VOA Special English. I'm Mario Ritter.


Concerns about climate change grew in 2006 as scientists reported that ice was melting at the North and South Pole

VOICE TWO:

And I'm Bob Doughty 1. This week, we talk about last year.

VOICE ONE:

We tell about some important science stories of two thousand six -- discoveries in medicine, space and the environment.

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VOICE TWO:

Some of the biggest science stories last year were in health and medicine. And two of them came late in two thousand six. First is a major finding about the spread of HIV, the virus that causes AIDS.

In December, AIDS researchers announced findings about adult male circumcision. Two studies in Africa found that circumcised men had about half the risk of getting HIV from sex with women as uncircumcised men had. The studies took place in Kenya and Uganda.

HIV rates are generally lower in areas of the world where the removal of the foreskin from the penis is common in babies or young boys.

The findings of the African studies were so clear that the United States National Institutes of Health decided 2 to end both studies early. All the men involved now are being offered circumcision.

The researchers said male circumcision could also lead to fewer infections in women where HIV is spread through heterosexual sex. Health experts say they hope circumcision will become one of the basic tools to fight HIV and AIDS. But they expect some cultural and economic barriers. Some people have also expressed another concern about circumcision. They say it might make men think they do not need to do anything else to prevent HIV infection.

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VOICE ONE:

Another major health story last month concerned breast cancer. The news came from cancer researchers at the University of Texas in Houston. They had found a sharp decrease in newly found breast cancer rates between two thousand two and two thousand three. It was the first such drop in seventy years. And it followed a huge decrease in the number of older women treated with female hormones 4 to ease conditions caused by a natural decrease in such hormones.

For years doctors treated these conditions of menopause with the hormones estrogen and progesterone. But in two thousand two a large study showed hormone 3 replacement 5 therapy seemed to increase the risk of breast cancer. The use of hormone replacement therapy then dropped by fifty percent.

The researchers at the University of Texas say overall rates of new breast cancers dropped seven percent the next year. And they said breast cancer that is linked to estrogen decreased by at least twelve percent. However, health experts say the findings do not prove that hormone replacement therapy causes breast cancer.

VOICE TWO:

There was also news about a new vaccine 6 to prevent another cancer in women -- cervical cancer. United Nations health officials called for the wide use of the vaccine against the human papilloma virus, or H.P.V. H.P.V. causes seventy percent of all cervical cancers. It is a leading cause of cancer deaths in women in developing countries.

The vaccine could prevent more than two-thirds of deaths from cervical cancer around the world. Officials say the vaccine is safe and effective for females between the ages of nine and twenty-six.

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VOICE ONE:

Not all the science news last year was medical. In August, more than two thousand members of the International Astronomical 7 Union met in the Czech capital, Prague. They agreed to a new definition of planet. They also agreed that Pluto 8 did not meet the terms of the new definition. So, now the solar system has eight planets instead of nine.

But do not cry for the former ninth planet. The astronomical union says we should not think we have lost a planet but that we have gained a new kind of space object: the dwarf 9 planet, Pluto.

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Astronomers 10 and physicists 11 were also interested in some information provided by the Hubble Space Telescope last year. It provided some light on the mysterious force known as dark energy. The Hubble examined stars that exploded billions of years ago. The findings: dark energy has been present for most of the history of the universe.

Dark energy is a mysterious force that causes the universe to expand at an increasing rate. Scientists do not know much about dark energy. But they say it makes up about seventy percent of the energy in the universe. It appears to balance the force of gravity.

Most physicists consider dark energy to be the force that Albert Einstein called the cosmological constant. It prevents gravity from pulling all matter together in a cosmic crush. This latest study shows dark energy was present in the universe as long as nine billion years ago. Over the next four billion years the power of dark energy grew.

The expansion rate of the universe began speeding up about five billion years ago. That is when scientists believe that dark energy's force overtook gravity. Adam Reiss of the Space Telescope Science Institute and Johns Hopkins University in Baltimore Maryland led this research.

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VOICE ONE:

Hubble also got some good news of its own last year. NASA announced it would fly a shuttle crew to the space telescope to make repairs and add new equipment. The telescope orbits six hundred kilometers above the Earth. The shuttle crew is expected to make the trip in May of next year. They hope to fix Hubble so it can continue operating until two thousand thirteen.

In other news from last year, the American space agency, NASA, returned to space. Three successful launches of the space shuttle visited the International Space Station. NASA's two Mars vehicles, Spirit and Opportunity, continued their exploration of the red planet. They found signs of recently flowing water on the planet.

An orbiting spacecraft gave the world extraordinary images of the planet Saturn 12 and its rings. NASA also announced important plans for the future. It will update the design of the space shuttles. And it is planning an international permanent base on the moon by the year twenty twenty.

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VOICE TWO:

Global warming remained a hot subject of earth science last year. Scientists declared that the ice at both the North and South Poles was melting. A long-term study showed that Greenland lost one hundred billion metric tons of ice between two thousand three and two thousand five.

Antarctica at the South Pole contains almost seventy percent of the world's fresh water. The continent is almost all ice. In some areas that ice is close to two thousand meters thick. Scientists said the Antarctic ice sheet is losing as much as one hundred fifty-two cubic kilometers of ice every year.

One study suggests that melting ice from both poles could cause sea levels in the world to rise by several meters by the end of this century. As a result, low-lying areas of land could be under water.

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VOICE ONE:

Some international ecology scientists and economists 13 gave a serious warning about the future for fish. They reported that seafood 14 supplies from the world's oceans could be almost gone within fifty years because of overfishing.

The researchers reported their findings in Science magazine in November. They said there had already been a collapse 15 in wild populations of almost one-third of currently fished seafoods 16. The study says that means the catch has fallen by ninety percent from the highest levels. The scientists said that species have recently been disappearing from oceans at increasing speed.

The scientists said it is not too late to repair the damage done to the oceans from overfishing, climate change and other forces. They said governments and industries must work together to establish shared fishing, pollution and species protection controls.

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VOICE TWO:

SCIENCE IN THE NEWS was written by Caty Weaver 17 and produced by Brianna Blake. I'm ­­­­­­­­­­­Bob Doughty.

VOICE ONE:

And I'm Mario Ritter. For more science news, MP3 files and transcripts 18 of our programs, go to www.unsv.com. And join us again next week for more news about science in Special English on the Voice of America.