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This is SCIENCE IN THE NEWS in VOA Special English. I'm Bob Doughty.

VOICE TWO:

And, I'm Barbara Klein. This week, we will tell about efforts against the H1N1 virus, often called swine flu. We will give a possible explanation for why some people may have an increased risk of developing diseases like diabetes and asthma. And we will tell about a study that confirms the importance of first impressions.

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The H1N1 influenza virus continues to spread. Currently, the virus is most active in the northern half of the world. But experts say it has become the leading flu virus in all countries.

No one really knows how many people have gotten sick. H1N1 was first reported in Mexico in April. Countries are no longer required to test and report individual cases. But close to five hundred million confirmed cases were reported to the World Health Organization as of November first.

The W.H.O. offices for the Americas and the Western Pacific reported two out of three of those cases. The agency says more than six thousand people worldwide have died because of H-one N-one.

The Saudi Arabian Health Minister gives his 8-year-old daughter the swine flu vaccine in Riyadh VOICE TWO:

W.H.O. special adviser Keiji Fukuda reported earlier this month that the virus has acted in some ways like seasonal flu. Most people recover without any need for interventions like antiviral drugs.

But in other ways, H1N1 is different. It remained at unusually high levels in several countries during their summer months. And, unlike seasonal flu, younger people have suffered many of the serious cases and deaths from the virus.

In the United States, cases of suspected influenza are at higher numbers than usual this early in the flu season. Experts at the Centers for Disease Control and Prevention say hospital treatment for likely H1N1 is most common among children up to four years old.

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Health officials around the world are concerned about vaccine production. Wealthy countries have promised to donate ten percent of their H1N1 vaccine to poor countries. But there is a worldwide shortage.

The traditional way to make flu vaccine is to grow the virus in chicken eggs. Anthony Fauci at the National Institutes of Health says the shortage is an issue of biology. He says the companies that make vaccines cannot really do much when they have a virus that does not grow well.

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Officials in Saudi Arabia are preparing for the Hajj, which starts this week. The event normally brings about three million Muslims from one hundred sixty countries to the city of Mecca.

Disease experts are concerned that H1N1 could spread easily among the Muslim pilgrims. Saudi officials have a campaign to give vaccines to health workers. They are also urging countries to vaccinate pilgrims making the trip. And they are advising against travel by children, pregnant women and other groups at highest risk.

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Swedish researchers have found that babies born by Caesarean section experience changes to the genes in their white blood cells. A published report says the genetic changes could be linked to stress levels during this method of giving birth.

The report says the changes could explain why persons born by Caesarean section are more likely to get diseases like diabetes and asthma later in life. Those diseases affect the immune system – the body's natural resistance to disease.

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Researchers at the Karolinska Institute in Sweden tested blood from the umbilical cords of thirty-seven newborn babies. The researchers tested the blood again three to five days later. They examined DNA-methylation in the white blood cells. DNA methylation shows chemical changes in a person's deoxyribonucleic acid, or DNA.

The study found that sixteen babies born by C-section had higher DNA-methylation rates immediately after they were born than the other babies. Three to five days later, the rates were about the same. The reason for this is unclear.

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Earlier animal studies showed that emotional or mental tension around birth affects methylation of the genes. Experts say babies are unprepared for birth when a doctor performs a C-section. As a result, those babies can have higher stress levels than those born without the help of the operation.

In other births, emotional or mental tension increases slowly as the woman's labor progresses. This helps the baby to start breathing and get settled in the new environment outside the mother.

Professor Mikael Norman of the Karolinska Institute helped to write the report. He says C-section births have been linked to an increased risk of allergic reactions, diabetes and leukemia later in life. The study appeared earlier this year in the publication Acta Paediatrica.

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The researchers say the discovery could be important to a debate about Cesarean-section deliveries. Births by C-section are increasing worldwide. It is currently the most common surgical operation among women of reproductive age.

America's Centers for Disease Control and Prevention says caesarean births rose to nearly thirty-two percent of all births in two thousand seven. This was the eleventh time in eleven years that rates have increased. But some experts believe that many of the C-sections are not medically necessary.

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Many people have learned as children that first impressions are important. Parents and other adults often say that people judge you by the way you look.

Now, American and British researchers have confirmed that judgments based only on how someone looks are important. They found that appearance tells a lot about your personality -- the traits or qualities that make you the person that you are.

The researchers included Laura Naumann of Sonoma State University in California, and Simine Vazire of Washington University in Saint Louis, Missouri. They were joined by Sam Gosling of the University of Texas at Austin and Peter J. Rentfrow of Britain's Cambridge University. The results of their study will be published next month in the Personality and Social Psychology Bulletin.

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We will call the subjects in the study, the judges. That is because they judged the personality of people they had never met. The judges examined pictures of one hundred twenty-three people. The people in the photographs had been told how to stand. They looked into the cameras with a neutral facial expression. The same people also were photographed the way they themselves wanted to stand. Those who wanted to smile could smile.

Then the judges attempted to decide what the people were like. The researchers compared the judges' opinions with the way the people who were photographed rated themselves. Three people who knew those in the photographs well also provided information about their personality and behavior.

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The judges looked for ten traits in the people in the pictures. The qualities included extroversion, or interest in other people and one's environment. Another important trait was self-esteem: Does the person feel good about himself or herself?

The judges also looked for signs of likeability, openness and agreeability. Other traits considered in the study were loneliness, and religious and political beliefs. Other considerations were emotional control and conscientiousness -- the quality of being guided by a sense of right and wrong.

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The researchers said the judges could identify some personality traits even when people were pictured in controlled positions. They could recognize traits like extroversion and self-esteem. But it was hard for the judges to decide about most other traits under the controlled conditions.

When the people smiled and stood looking natural and energetic, however, judging their personalities was easy. Then the judges' choices were correct for nine of the ten personality traits.

Researcher Laura Nauman noted that we live in a time of social media, and personal photographs are everywhere. She says it is important to understand how appearance communicates personality. If you want people to see you as warm and friendly, she says, just smile.

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VOICE ONE:

This SCIENCE IN THE NEWS was written by June Simms, Jerilyn Watson and Caty Weaver. Our producer was Brianna Blake. I'm Bob Doughty.

VOICE TWO:

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