VOA慢速英语 2007 0410b（在线收听）

VOICE ONE:

This is SCIENCE IN THE NEWS in VOA Special English. I'm Faith Lapidus.

VOICE TWO:

And I'm Bob Doughty. On our program this week, we will tell about new suggestions for treating heart attack victims. We also tell about a test for lung cancer. But first, we report on new pictures from a far-away planet.

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VOICE ONE:

 
Jupiter's Little Red Spot, seen from 3.5 million kilometers
The New Horizons spacecraft has made some of the most detailed pictures ever taken of the planet Jupiter. Yet the American spacecraft is only passing by the planet. New Horizons is attempting to become the first space vehicle to visit Pluto.

New Horizon's pictures of Jupiter and three of its moons are filled with surprises. Jupiter is the largest planet in the solar system. The planet has a deep, thick atmosphere of clouds made of hydrogen, helium, methane and ammonia.

New Horizons used its Long Range Reconnaissance Imager camera to take pictures of a storm called the Little Red Spot. The pictures will help scientists learn how the storm developed.

VOICE TWO:

New Horizons also made pictures of Jupiter's moon Io. The pictures were taken just as the volcano Tvashtar sent a cloud of dust two hundred ninety kilometers above its surface. At the time, the spacecraft was only two million five hundred thousand kilometers away from the moon.

Scientists say the pictures look like a similar volcanic eruption on Io in nineteen seventy-nine. At that time, the Voyager Two spacecraft captured a picture of the volcano Pele erupting. But New Horizon's pictures of Tvashtar are more detailed.

Another target for the camera was the largest of Jupiter's moons, Ganymede. Pictures show an icy world with ancient dark areas and bright newer areas where space objects struck the surface.

New Horizons also took pictures of Europa, another moon of Jupiter. Europa is believed to have an ocean one hundred kilometers below its frozen surface.

VOICE ONE:

The American space agency launched New Horizons in January of last year. Although smaller than a car, it is the fastest spacecraft ever launched. It has traveled at speeds of over fifty-seven thousand kilometers an hour.

New Horizons is expected to reach Pluto in two thousand fifteen. 

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VOICE TWO:

Lung cancer kills more Americans than any other kind of cancer. Smoking is a leading cause of the disease. Signs of lung cancer include chest pain, breathing problems and the sudden expulsion of air from the lungs. The signs may not appear until the disease is fully developed.

Doctors have different ways to find lung cancer. One test is an x-ray imaging process called computed tomography, or CT. A CT test, or scan, can be helpful in finding very small growths on the lung.

Last year, the New England Journal of Medicine published a report about CT scans and lung cancer. The report said early discovery of lung cancer with the test followed by an operation could save lives. It estimated that patients whose cancers were found early and then removed had a ten-year survival rate of ninety-two percent.

VOICE ONE:

Now, another report is disputing the findings. The Journal of the American Medical Association published the report. Peter Bach is a lung specialist at the Memorial Sloan Kettering Cancer Center in New York. He says early CT testing is not only unproven, but can cause great harm to patients. He says some patients died from unnecessary operations. Others suffered heart attacks, infections and even a collapsed lung.

Doctor Bach says CT scans are successful at finding small growths in the lungs. But he says such growths do not always spread quickly or cause serious harm. For that reason, he says, it only seemed in the earlier study that lung cancer deaths were prevented.

VOICE TWO:

Doctor Bach and his team examined information about more than three thousand two hundred people. All of the patients either smoked or were former smokers. They were tested for lung cancer. Doctor Bach says CT scans missed the fast-growing, deadly cancers. He says the tests showed only very small, slow-growing cancers. The CT scans led to a rise in the number of lung cancer operations.

Thirty-eight of the patients died of lung cancer over a five-year period. Doctor Bach says that same number of patients would have died without early CT scans.

Medical experts say the debate on preventing lung cancer deaths through such tests will continue until a larger study is completed.

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VOICE ONE:

Cardiopulmonary resuscitation, or CPR, can save the life of someone whose heart has stopped. The condition is called cardiac arrest. The heart stops pumping blood. The person stops breathing. Without lifesaving measures, the brain starts to die within four to six minutes. 

CPR combines breathing into the victim's mouth and repeated presses on the chest. CPR keeps blood and oxygen flowing to the heart and brain.

However, a Japanese study questions the usefulness of mouth-to-mouth breathing. The study was published in the British medical magazine, The Lancet. Doctors in Tokyo examined more than four thousand people who had suffered cardiac arrest. In all the cases, witnesses saw the event happen.

VOICE TWO:

More than one thousand of the victims received some kind of medical assistance from witnesses. Seven hundred and twelve received CPR. Four hundred and thirty-nine received chest presses only. No mouth-to-mouth rescue breaths were given to them.

The researchers say any kind of CPR improved chances of the patient's survival. But, they said those persons treated with only chest presses suffered less brain damage. Twenty-two percent survived with good brain ability. Only ten percent of the victims treated with traditional CPR survived with good brain ability.

VOICE ONE:

The American Heart Association changed its guidance for CPR chest presses in two thousand five. The group said people should increase the number of chest presses from fifteen to thirty for every two breaths given. Gordon Ewy is a heart doctor at the University of Arizona College of Medicine in Tucson. He wrote a report that was published with the study.

Doctor Ewy thinks the CPR guidelines should be changed again. He said the Heart Association should remove rescue breaths from the guidelines. He argues that more witnesses to cardiac arrests would provide treatment if rescue breaths are not a part of CPR. He says this would save lives. Studies show that many people do not want to perform mouth-to-mouth breathing on a stranger for fear of getting a disease.

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VOICE TWO:

Life expectancy is the average number of years people are expected to live. In the United States, that average has been increasing since the late eighteen hundreds. But, life expectancy for black Americans has always been lower than that for white Americans. In the nineteen-eighties, the difference in life expectancy rates for blacks and whites increased and later decreased. Until now, these changes had not been explained.

Sam Harper of Canada's McGill University and other researchers decided to investigate. They examined deaths among blacks and whites in the United States between nineteen eighty-three and two thousand three. This meant investigating forty-six million deaths. The results were published in the Journal of American Medicine.

VOICE ONE:

Professor Harper says the study shows that American blacks are living longer. He says their life expectancy is nearly that of whites. In nineteen ninety-three, for example, white men lived an average of eight and one-half years longer than black men. In two thousand three, the difference had narrowed to six and one-half years.

The researchers say the biggest improvement in life expectancy was noted among black males between fifteen and forty nine years of age.

VOICE TWO:

Professor Harper says the changes appear linked to successes in reducing violence linked to the drug crack cocaine. He says increases in the sizes of police forces and economic improvements all appear to have helped young black males live longer.

But, the researcher says additional improvements are needed. He says the disease AIDS and heart disease in African-Americans are also keeping their life expectancy rates less than whites. He says there is also a need to reduce the higher death rates among newborn African-Americans.

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VOICE ONE:

This SCIENCE IN THE NEWS program was written by Lawan Davis, Mario Ritter and Caty Weaver. Brianna Blake was our producer. I'm Faith Lapidus.

VOICE TWO:

And I'm Bob Doughty. Join us again next week for more news about science in Special English on the Voice of America.