Stress and Failed Pregnancies / Ice Loss in Antarctica / Anger and Injuries / Hummingbirds Never Forget
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This is SCIENCE IN THE NEWS in VOA Special English. I'm Faith Lapidus. And I'm Bob Doughty. This week: a report that Antarctica is losing ice at an increasing rate.
We also will tell about a bird with an excellent memory.
But first, we tell about a study of special interest to women.
Women who experience emotional tension in the first weeks of pregnancy may be at greater risk of suffering a failed pregnancy. A new study suggests a link between the tension, worry, and pressure a woman feels and her ability to carry an unborn child, or fetus. The failure of a pregnancy and resulting death of the fetus is called a miscarriage.
The results of the study were published in Proceedings of the National Academy of Sciences of the United States of America.
Pablo Nepomnaschy works for the National Institute of Environmental Health Sciences in North Carolina. His research team studied sixty-one women for one year. All the women lived in Guatemala and were already caring for at least one baby.
The researchers tested the women for pregnancy and measured cortisol in their liquid wastes. Cortisol is a substance, or hormone, produced by the body. Other studies have linked it to emotional tension, also known as stress.
Twenty-two of the sixty-one women became pregnant during the study. The researchers compared the pregnant women who had higher than normal cortisol levels to those who did not. They found that women with the higher levels during the first three weeks of pregnancy were nearly three times more likely to miscarry.
The researchers say a woman's body may recognize increased cortisol levels as a sign that conditions are not right for pregnancy.
They also say other studies might have failed to find the link between stress and miscarriages because they involved women who had been pregnant for at least six weeks. Most miscarriages happen during the first three weeks of pregnancy.
An American study suggests that anger appears to increase your risk of suffering an injury. It found that angry adults are more likely than other men and women to suffer an injury requiring emergency medical care. Study organizers say the risk of serious injury also is higher for men than for women.
Dan Vinson of the University of Missouri at Columbia led the research team. They questioned more than two thousand people who had been treated in hospital emergency rooms. The patients were asked to describe their emotions twenty-four hours before the injury and then in the minutes just before their injury. The answers were compared with those provided by a group of uninjured adults.
Some of the patients described themselves with words such as excited, angry and hostile. Patients who described themselves as feeling easily angered had a thirty percent increased risk of suffering a serious injury. Among men, the risk of injury increased one hundred percent if the man described himself as being hostile or angry at himself.
The study also suggested a link between anger and sports injuries and attacks.
Professor Vinson and his team also examined suspected links between anger and traffic injuries. But they were unable to find such a link. Professor Vinson noted that some people get angry when they drive. Yet their actions generally do not cause traffic accidents. An earlier study in Finland reached the same finding.
Professor Vinson estimates that at least ten percent of emergency room visits could be avoided if people did not take action when they are angry. He urged doctors to begin recognizing when their patients have injured themselves because of anger. He said doctors also may need to suggest anger control programs in addition to medical treatment.
Two weeks ago on this program we talked about the melting of ice from glaciers in Greenland. Now comes news that Antarctica is also losing ice at an increasing rate. Science magazine published a new report. It says the Antarctic ice sheet is losing as much as one hundred fifty-two cubic kilometers of ice every year.
Scientific researchers from the University of Colorado in Boulder carried out the study. They used information from a project called the Gravity Recovery and Climate Experiment, or GRACE. Germany and the United States launched two GRACE satellites in two thousand two. The satellites measure changes in Earth's gravitational pull. Changes in the power of that pull provide clues about the mass of different areas on the planet.
The GRACE satellites travel around the Earth sixteen times each day. One follows the other always at a distance of two hundred twenty kilometers.
When the gravity field changes, so does the distance between the two satellites. Equipment on the satellites can record a change in distance of as small as one micron.
John Warh is a physics professor at the University of Colorado and a leader of the study. He says the strength of the GRACE satellite equipment is that it let scientists measure all of Antarctica at once.
Antarctica contains almost seventy percent of the world's fresh water. The continent is almost all ice. In some areas that ice is close to two thousand meters thick.
The last major study of the Antarctic ice sheet was completed in two thousand one. Government scientists from several countries were involved. Those scientists had expected a different future for the world's fifth largest continent.
They said that Antarctica would gain ice mass in the future. They believed that a warming of Earth's climate would lead to more rain and snow. The scientists said more rain and snow would lead to increased ice. But, the new report shows that is not happening. Or at least not yet.
Some scientists argue that the new study is too early in the life of GRACE. They say three years of measurement of the ice mass is not long enough.
Isabella Velicogna was the lead writer of the report. She is a researcher at the University of Colorado and the Jet Propulsion Laboratory in Pasadena, California. Mizz Velicogna says this is the first study to report a decrease in a total mass balance of Antarctica. She agrees that more information from GRACE would provide a clearer picture of the continent's future. But she also says she does not think the ice loss she discovered is going to stop right away.
If you think the elephant is the only animal that never forgets, you are wrong. That is the judgment of scientific researchers who studied a very small North American bird. The researchers reported that hummingbirds can remember visits to at least eight different areas over several days. The results of their study were published in Current Biology.
Many scientists think that only people had comparable abilities. Earlier studies showed that some animals could remember an object or event. Those animals could remember where they saw the object or event. But it is not clear if they knew when they saw it.
Timing is very important to a hummingbird. These birds collect a sweet substance called nectar from flowers. If a hummingbird returns too soon to a flower, it will not get more nectar. Or, if the bird waits too long for a first visit, another hummingbird may get there first.
In the new study, Jonathan Henderson and Susan Healy of the University of Edinburgh led an international research team. Its members tested three wild, male rufous hummingbirds in the Rocky Mountains of Canada.
The hummingbirds recognized eight different objects that looked like flowers. The objects were put in the place where their usual feeders were kept. The researchers refilled four of the objects. They said it took one to two hours to train the birds to feed from them.
Every ten minutes, the researchers put a sweet substance in the four objects. The researchers filled the four other objects every twenty minutes.
The hummingbirds demonstrated that they could remember the placement of these man-made flowers. They also could remember when they had last visited them. The hummingbirds returned to the flowers that were refilled more often than the others.
SCIENCE IN THE NEWS was written by Brianna Blake, George Grow, Jerilyn Watson and Caty Weaver. Cynthia Kirk was our producer. I'm Bob Doughty. And I'm Faith Lapidus. Join us again next week for more news about science in Special English on the Voice of America.