Rays and the strength of thunderstorms

Scientists measure electric fields in thunderclouds with instruments aboard airplanes and weather balloons, but during violent conditions these methods can be difficult, even dangerous. Now researchers may have found a better way to measure these electrical fields: the cosmic rays that originate from exploding stars.

When cosmic rays hit the Earth’s atmosphere, they create a shower of high-energy particles. Researchers in the Netherlands measured the radio emissions generated by these showers and found that they varied markedly during fair weather and thunderstorms. The differences may provide an effective way to estimate the electric field in a thunderhead.

Monitoring a cloud’s electric field is important because it helps define the power of a thunderstorm, said Heino Falcke, an astrophysicist at Radboud University and one of the study’s authors.

“Only if the electric field is strong enough, you have enough power to get lightning going,” Heino said. “This is like measuring the horsepower of a car, or the tension of the bow of an archer.”

Heino and his colleagues took their measurements using the LOFAR radio telescope in the Netherlands and published their findings in the journal Physical Review Letters.

It’s possible that the cosmic rays themselves are somehow involved in causing lightning, Heino noted. “How lightning is initiated is not at all clear yet,” he said. “Studying this, we might be able to better predict lightning, understand what exact conditions cause lightning, and perhaps gain practical tips to protect ourselves better.”

African diet may lead away from colon cancer
A  change in diet for just two weeks alters gut bacteria in ways that may reduce risk of colon cancer, according to a new study in Nature Communications. Researchers asked 20 African-Americans in Pittsburgh and 20 rural South Africans to switch diets for two weeks. The Americans ate a traditional African diet, high in fiber and low in fat, with plenty of fruits, vegetables, beans and cornmeal, and very little meat.

The Africans ate the equivalent of American fast food – a diet high in fat with generous quantities of meat and cheese. “We made them fried chicken, burgers and fries,” said Stephen J D O’Keefe, a gastroenterologist at the University of Pittsburgh and one of the study’s authors. “They loved it.”

After the swap, the researchers performed colonoscopies on all the volunteers. African-Americans who ate the traditional African diet had reduced inflammation in the colon and increased production of butyrate, a fatty acid that may protect against colon cancer.
Conversely, after two weeks, Africans who ate the Western diet experienced changes in gut bacteria consistent with an increased cancer risk.

In Western countries, colon cancer is the second-leading cause of cancer deaths. It is diagnosed in 150,000 Americans annually; African-Americans are disproportionately affected. The disease affects few people in rural Africa.

Rural Africans eat food that they grow themselves because it is less costly. But as populations increasingly move into cities for work, diets will change, Stephen noted. “We’re trying to find out what aspects of their diet should be maintained,” he said.
Sindya N Bhanoo
NYT