This is SCIENCE IN THE NEWS in VOA Special English. I'm Bob Doughty.
And I'm Barbara Klein. Today, we will tell about a plan to fight a leading killer of children in developing countries. We will tell about a new way to recognize harmful minerals in rocks and soil. And we will tell about a major study of laughter.
Diarrhea kills 1,500,000 children each year. That represents one in five child deaths worldwide. The only disease that kills more children under age five is pneumonia.
Experts say diarrhea causes more child deaths than the diseases AIDS, malaria and measles combined. New findings show it also kills more than a million young people and older adults every year.
Therese Dooley works for UNICEF, the United Nations Children's Fund.
THERESE DOOLEY: "In addition to the deaths, there's about 2.5 billion -- and I want to emphasize, about 2.5 billion cases of diarrhea among children every year."
But a new report says 60 percent of those in developing countries do not get the suggested treatment. UNICEF and the World Health Organization wrote the report. It was published in the medical journal The Lancet.
Diarrhea causes fluid loss and reduces the body's supply of zinc. This mineral is needed for normal growth and development. For the past five years, UNICEF and the W.H.O. have suggested zinc supplements to treat diarrhea. They also recommend fluid replacement solutions made from what are called low-osmolarity oral rehydration salts.
Yet zinc supplements remain largely unavailable in the developing world. The fluid replacement solutions can also be difficult to find.
A leading cause of diarrhea in children is the rotavirus. Public health officials are now advised to include the rotavirus vaccine in all national immunization programs. But the vaccine is still not available in many developing countries.
The report says new ways to expand the use of treatments are now being developed. Proposals include, for example, supplying treatment kits through community health workers or special campaigns.
Experts say children with diarrhea should continue to eat, and babies should continue to breastfeed.
To help prevent diarrhea, the report suggests that children receive both the rotavirus and measles vaccines. It also calls for improving supplies of clean water in developing countries.
Another prevention measure is hand washing with soap.
Diarrhea can be easy to prevent. Campaigns to fight childhood diarrhea had some success during the 1970s and 80s. UNICEF and the W.H.O. hope this new plan will help return the issue to worldwide importance.
Asbestos is the name for several fibrous minerals. The long, thin fibers are strong, and can work well to reduce temperature changes. They are also resistant to fire.
Because of these qualities, people have been using asbestos in products for many years. Asbestos was a favorite of builders and manufacturers during the 20th century. Some people praised it as a wonder material.
In recent years, however, asbestos has become feared as a threat to human health. Asbestos has been linked to serious health problems, including two kinds of cancer. In some countries, costly repairs were made on many buildings to remove the material. All new uses of asbestos were banned in the United States in 2007.
Still, asbestos develop naturally in rocks and soil in some areas. The material can harm people who do not know it is there.
For more than a century, scientists in California have made maps of rocky areas that might contain asbestos. They did their research on the ground. But scientists are reporting that some asbestos in the earth can now be found quickly by sensing devices from the air.
Gregg Swayze works for the United States Geological Survey in Denver, Colorado. He led the team of scientists. They developed a new method of making maps of hard-to-reach areas. Their test flights took place in 2001. A report about the study appeared recently in the publication Geology.
Each kind of mineral has its own structure and chemicals. Fibrous minerals like asbestos are no exception. The light absorbed, or collected, by an asbestos surface can be recognized by an appearance all its own. So can the light that the surface reflects, or reproduces.
Many minerals in the asbestos family can absorb light with a wavelength measuring 2.3 micrometers. When the asbestos is seen in light near that wavelength, the minerals look darker than those around them.
The researchers examined areas in the California counties of El Dorado and Plumas from the air. The areas were suspected or known to have rocks and soil containing asbestos. The team's sensor devices were set on differing wavelengths. The researchers were able to identify asbestos even in places 80-percent covered by dry grass.
But Mr. Swayze notes limits on the asbestos searches from the air. He says water also holds some of the major wavelengths that identify asbestos. For this reason, he says, air searches would need to be done in areas where the climate is dry or plants lacking altogether.
For now, however, the method offers the promise of making a map of asbestos easier and faster than earlier ways.
Recognition of the harm asbestos can do and the ban on its new uses did not take place until recently. But people have suspected it for centuries. More than 2000 years ago, the Roman naturalist Pliny the Elder observed its harmful effects. Pliny and the Greek geographer Strabo both noted that slaves making cloth with the material developed lung problems.
Shy people often avoid situations that force close contact with other people. They worry that something they say or do will make others laugh at them.
But some people worry much more than others about being the target of laughter. These people are frightened. They suffer from an emotional disorder called gelotophobia. That long name comes from the Greek language. The word "Gelos" means "laugh," while "phobos" means fear.
Victor Rubio is an expert on human behavior at the Autonomous University of Madrid. He says people laugh at others for many different reasons. He says being laughed at causes a fear response in the victim. That fear leads the victim to avoid social situations. Sadly, gelotophobia limits the way they lead their lives.
Mr. Rubio was among researchers in a huge international study about laughter. The researchers wanted to understand the difference between normal shyness and true gelotophobia. Another goal was to measure the fear of being laughed at within different cultures. A team from the University of Zurich led 93 researchers from many countries in search of answers.
The researchers questioned more than 22,000 people. They used questions provided in 42 languages. Their findings were reported in the scientific publication "Humor."
Some of the people questioned said they felt unsure of themselves in social situations. But they hid their feelings. Others said they avoided social situations where they had been laughed at before. People also admitted to differing levels of fear that they themselves were the targets of other people's laughter. The researchers measured and compared all these reactions.
Fear of being laughed at, being made fun of, is a common emotion. But the researchers learned that these feelings differed from nation to nation. For example, the study found that people in Turkmenistan and Cambodia are likely to hide insecure feelings when they are around others' laughter. But people in Iraq, Egypt and Jordan who feel they have been victims before may avoid such situations.
People in Finland were the least likely to believe that people laughing in their presence were making fun of them. Only eight and one half percent of Finns said that was true. In Thailand, however, 80 percent of those questioned said they believed they were objects of laughter.
This SCIENCE IN THE NEWS was written by June Simms and Jerilyn Watson. Our producer was Brianna Blake. I'm Bob Doughty.
And I'm Barbara Klein. Join us again next week for more news about science in Special English on the Voice of America.
rehydration: the replenishment of water and electrolytes lost through dehydration 再水化
rotavirus: any of a group of wheel-shaped, RNA-contained viruses that cause gastroenteritis, especially in infants and newborn animals 轮状病毒
asbestos: any of the fibrous amphibole and serpentine minerals, esp chrysotile and tremolite, that are incombustible and resistant to chemicals 石棉
Plan aims to fight child diarrhea in developing world
Researchers look behind the tears to study crying
Laughter linked to health, happiness
（Source: VOA 英语点津编辑）