SCIENCE IN THE NEWS - Sticking Power: Geckos Face Some Compe（在线收听）

SCIENCE IN THE NEWS - Sticking Power: Geckos Face Some Competition
By George Grow, Shelley Gollust, Jill Moss and Cynthia Kirk

Broadcast: Tuesday, September 06, 2005

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This is SCIENCE IN THE NEWS in VOA Special English. I'm Barbara Klein.

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And I'm Bob Doughty. This week on our show -- a study dismisses homeopathic medicine.

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Research links the ancient custom of female genital cutting to infertility.

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New findings might help explain why cocaine users have a higher risk of heart attacks.

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And some lizards famous for their sticking power have some new competition in the laboratory.

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Geckos are small lizards that live in warm climates. These lizards can stick to any surface. For example, geckos can climb up walls and across the top of a room. Scientists have studied the little creatures for hundreds of years to learn the secret of how they stick to things. They hoped the findings would help them develop powerful materials that hold things together.

A few years ago, American scientists solved the mystery. They found that geckos have five hundred thousand very small hairs on the bottoms of their feet. The end of each hair splits into hundreds of smaller hairs. So the geckos' feet have hundreds of millions of tiny hairs that touch a surface and hold the feet in place.

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America's National Science Foundation gave money to scientists at the University of Akron in Ohio and Rensselaer Polytechnic Institute in Troy, New York. The scientists worked to make material like the hairs on geckos' feet. The team recently reported that it had produced hairs that have two hundred times the sticking power of natural gecko hairs.

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The scientists have tested only small amounts of the material. But they estimate that an amount of the material the size of a small piece of money could hold up to about ten kilograms.

The hairs made by the scientists are only one ten-thousandth the width of a human hair. They are made of extremely small movable carbon tubes, called nanotubes, placed in a plastic base.

Ali Dhinojwala is one of the scientists at the University of Akron. He says the tubes are strong and generally unbreakable. He says the team will continue testing larger amounts of the material. The study was published in Chemical Communications.

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VOICE TWO:

You are listening to SCIENCE IN THE NEWS in VOA Special English.

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A new report disputes the medical value of homeopathic treatments. It says such treatments have the same effect as a placebo. A placebo looks like medicine but contains no active substance. Yet it can sometimes have an effect on people if they do not know it is only a placebo.

Matthias Egger of the University of Berne in Switzerland led a team. His group compared studies of homeopathic treatments with studies of medical drugs. They compared one hundred ten studies of each. The findings are published in The Lancet.

The scientists say there was not enough evidence to show that homeopathy worked better than a placebo in studies with both. Still, they noted the limits of science to disprove something. In their words, "We acknowledge that to prove a negative is impossible."

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The word homeopathy has roots in two Greek words. Homoio means similar. Pathos is suffering or disease.

A German doctor, Samuel Hahnemann, developed homeopathic medicine in the seventeen nineties. He believed that some substances could cure diseases if they produced effects similar to those of the disease itself. He believed that these substances -- from plants, minerals or animals -- helped the body's own defense system to fight the sickness.

Homeopaths say traditional doctors too often use medicines without considering all the possible causes of a disorder. They say they carefully consider both the physical and emotional health of a person. They say their goal is to strengthen the body's natural ability to cure itself.

Treatments might involve deadly substances like snake poison or arsenic. But they are given in very small amounts. The idea is that they are too weak to cause harm.

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Even critics of homeopathy agree that it sometimes works. But they say this is only because a patient thinks it will work. In other words, a placebo effect. Professor Egger says homeopathic treatments are likely to show effects in smaller, low quality studies. However, his group found that the effect disappears in larger, more careful studies.

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New findings might help explain why users have a higher risk of heart attacks. Researchers found that users of the illegal drug increase the risk of aneurysms in their coronary arteries.

Coronary arteries carry blood with oxygen to the heart. Aneurisms are weak areas in the walls of blood vessels. The area becomes filled with blood like a balloon. Aneurysms happen more often in the brain and the aorta, which carries blood away from the heart. If they burst, they can cause brain damage and sudden death.

 
Cocaine
The researchers say aneurysms in the coronary arteries rarely burst but may lead to a heart attack, at least in cocaine users. The study is described as the first to document a link between cocaine and coronary aneurysms. Cocaine users in their early forties had four times the risk as non-users in the same age group.

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The researchers examined the records of people who had been tested for known or suspected heart problems. The study found signs of coronary aneurysms in almost eight percent of those who did not use cocaine. In those who did, the finding was thirty percent.

Doctor Timothy Henry was the lead writer of the study. He directs research at the Minneapolis Heart Institute Foundation. The study appeared in Circulation, published by the American Heart Association.

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Tobacco adds to the risk of aneurisms and heart attacks. Almost all of the cocaine users smoked cigarettes. The researchers knew from the medical records how often about half of them took cocaine. Two-thirds reported they used it at least once a week.

The study suggests two possible ways that cocaine might lead to an aneurism. One is through damage to the cells inside the arteries. The other is through sharp increases in blood pressure. Then, once an aneurysm forms, it may lead to a blockage in the flow of blood and cause a heart attack.

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New research suggests that the custom in parts of Africa and Asia to cut the sex organs of girls can cause infertility later in life. Researchers believe this is the result of infections that spread to the reproductive organs.

The Swedish-led study took place in Sudan. The findings appeared in The Lancet. The researchers linked the risk of infertility to the extent of the cutting. Infertile women were five to six times more likely to have had the most severe cutting than women who were able to get pregnant. But the researchers say any damage could lead to changes that harm reproductive health.

Each year, an estimated two million more girls reach the age where they might be cut. But experts have found a reduction in this custom in a number of countries. The United Nations Children's Fund seeks an end to female genital mutilation by two thousand ten.

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Our program was written by George Grow, Shelley Gollust, Jill Moss and Cynthia Kirk, who was also our producer. SCIENCE IN THE NEWS can be found on the Web at www.tingroom.com. I'm Barbara Klein.

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And I'm Bob Doughty. To send us e-mail, write to [email protected]. And please join us again next week for more news about science in Special English on the Voice of America.