SCIENCE IN THE NEWS - Scientists Withdraw Suggestion of Link（在线收听）

SCIENCE IN THE NEWS - Scientists Withdraw Suggestion of Link / Dirty Conditions and Children / Mysterious Dark Energy
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Broadcast: Tuesday, March 16, 2004

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VOICE ONE:

This is SCIENCE IN THE NEWS, in VOA Special English. I'm Sarah Long.

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And I'm Bob Doughty. On our show this week -- new developments about a British study that frightened many parents.

VOICE ONE:

A study measures the effects of dirty conditions on child growth.

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Plus ... the mystery of dark energy.

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Six years ago, a British study suggested the possibility of a link between autism and the M.M.R vaccine. Autism is a brain disorder that appears in young children. It affects communication and the ability to relate to people and environments. The M.M.R. vaccine is a medicine given to millions of children to prevent three diseases: mumps, measles and rubella.

Thirteen scientists did the study. Their report appeared in the British medical magazine The Lancet. But The Lancet has now published a letter from ten of those scientists. One of the others could not be reached. The ten withdrew the suggestion of a possible link between autism and the M.M.R. vaccine. They said they wish to make clear that they never stated that the vaccine caused autism.

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The ten scientists did not include Andrew Wakefield who led the study. Recently he has been criticized for accepting money from lawyers for a group of families of autistic children. The families wanted a separate study done to support legal claims against companies that make the vaccine.

Doctor Wakefield says his work for the families was no secret and created no conflict of interest with his study. He is reported as saying he still believes a possible connection between autism and the vaccine needs further investigation. Lawyers for Doctor Wakefield have demanded an apology from The Lancet.

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Public trust in the M.M.R. vaccine has dropped in large part because of the nineteen-ninety-eight study. The ten scientists said they recognize there have been major effects on public health. Some parents in Europe and the United States have refused the vaccine for their children. Doctors say this is a serious risk. Mumps, measles and rubella can all make people very sick.

Since the study, other studies have shown no link between autism and the vaccine. Some critics say a lot of money has been wasted trying to prove that the nineteen-ninety-eight study was false. But others have called the study "poor science." They note that only twelve children took part.

In a commentary, The Lancet points out that the vaccine issue was only one observation. The study dealt with bowel disease in autistic children. The scientists reported a possible link between bowel disease and autism. The letter just published does not dismiss that part of the study.

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Last November, the United States government announced a ten-year plan to study autism. Scientists know that genetics play a part, but not much beyond that is known.

Autism research does not have a very long history. In nineteen-forty-three, a researcher named Leo Kanner wrote about a condition that he found in eleven children. He described it as "extreme autistic loneliness." He said the children were unable to relate themselves in the normal way to people and situations "from the beginning of life."

Leo Kanner was a medical doctor at Johns Hopkins University, in Baltimore, Maryland. His specialty was mental health in children. In nineteen-thirty-five, he wrote what is described as the first medical book on child psychiatry.

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VOICE ONE:

This is SCIENCE IN THE NEWS, in VOA Special English.

Unsafe water supplies and dirty conditions can slow the growth of children. This is the finding of public health researchers from Johns Hopkins University. Their study appears in The Lancet.

They studied two-hundred-thirty children in Peru from birth until three years of age. This is what they found:

By age two, children from homes with the worst conditions were one centimeter shorter than those with the best conditions. They also had fifty-four percent more cases of diarrhea. The researchers examined the babies once a day and measured them once a month.

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But better water supplies alone did not guarantee good health. For example, some families kept water in large containers outdoors. Others kept small storage containers inside their homes. Small containers can be filled more often.

But children in homes with the small containers had more cases of diarrhea. The researchers say this is because the containers are usually kept uncovered. So the water can get dirty more easily. The large containers outside are normally kept covered.

The researchers found that other conditions could also affect the growth of children. Some of the children were from homes with a water connection, but not a good system for waste removal. These children were almost two centimeters shorter than those with the cleanest conditions at home.

The study ended in nineteen-ninety-eight. Doctor William Checkley led the study. He says safe water and good sanitation are basic human rights.

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American space scientists say Albert Einstein may have been right after all about what space is mostly made of. They say they have found the best evidence yet that some form of energy pushes at an unchanging rate throughout the universe. Scientists today call this dark energy.

Einstein had a different name for such a force. He called it a cosmological constant. The German-born American physicist had a theory that this force balanced the pull of gravity. Without it, everything in the universe would crash together in the middle. Gravity would prevent the opposite. It would keep objects from spreading apart forever.

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Einstein developed this idea in support of a general belief that the universe was static, unchanging. However, he rejected the idea following a discovery by Edwin Hubble in nineteen-twenty-nine. The American astronomer found that the universe was expanding.

Albert Einstein later called the cosmological constant theory his "greatest blunder." Yet now, the space telescope named after Edwin Hubble has gathered information to suggest this was no mistake.

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Astronomers used the Hubble Space Telescope to examine stars that exploded thousands of millions of years ago. These stars are called supernovas. The scientists measured light from the supernovas. Such measurements tell much about conditions at different points in the history of the universe.

Adam Reiss [reese] led the research at the Space Telescope Science Institute in Baltimore. Mister Reiss says dark energy appears to stay the same even as the universe expands. He says any change is extremely slow, if at all. He says the universe has at least thirty-thousand-million years left. This is even if Einstein's cosmological constant theory is wrong.

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So that is good news. Yet the researchers were not able to offer any new information about one question: What is dark energy?

The only thing most scientists seem sure of is that they are not sure. Whatever it is acts in a way opposite to gravity. Gravity pulls things together. Dark energy pushes them apart.

What if dark energy ever grows stronger than gravity? Then, it could tear all things apart. Stars, planets, even individual atoms would be destroyed. Scientists call this the "big rip."

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But some question all this. An international team recently announced evidence that might conflict with the dark energy theory. The researchers studied X-rays recorded by the European satellite observatory XMM-Newton.

They looked at X-rays from groups of galaxies thousands of millions of years old. They say there are ten times more of these clusters now. Alain Blanchard is a scientist at the Astrophysical Laboratory in France. Mister Blanchard says these results require a high density of matter in the universe. He says that would leave little room for dark energy.

Adam Reiss tells us he is not worried about these findings. He studies supernovas. But he says most scientists who study galactic clusters report findings that are similar to his own. That is, a universe filled mostly with a mysterious force they call dark energy.

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SCIENCE IN THE NEWS was written by Jill Moss and Caty Weaver. Cynthia Kirk produced our program. This is Bob Doughty.

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And this is Sarah Long. Join us again next week for more news about science, in Special English, on the Voice of America.