Geyser eruptions triggered by bubble trap
Geysers like Old Faithful in Yellowstone National Park erupt periodically because of loops or side-chambers in their underground plumbing, according to recent studies by volcanologists at the University of California, Berkeley.
The key to geysers, said professor Michael Manga, is an underground bend or loop that traps steam and then bubbles it out slowly to heat the water column above until it is just short of boiling. Eventually, the steam bubbles trigger sudden boiling from the top of the column, releasing pressure on the water below and allowing it to boil as well. The column essentially boils from the top downward, spewing water and steam hundreds of feet into the air.
“Most geysers appear to have a bubble trap accumulating the steam injected from below, and the release of the steam from the trap gets the geyser ready to erupt,” Manga said. “You can see the water column warming up and warming up until enough water reaches the boiling point that, once the top layer begins to boil, the boiling becomes self-perpetuating.”
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He and his students feed temperature and pressure sensors as deep as 30 feet into geysers and correlate these with above-ground measurements from seismic sensors and tiltmeters to deduce the sequence of underground events leading to an eruption. berkeley.edu
Brain activity may be better way to predict movie’s success
A study in the Journal of Marketing Research finds that brain activity visible through EEG measures may be a much cheaper and more accurate way to predict the commercial success of movies.
The authors, from Erasmus University, in the Netherlands, sat participants in comfortable chairs in a darkened room in front of a computer screen with a pair of speakers. Participants were then hooked up to EEG machines and asked to view 18 movie trailers in random order while their brain activity was recorded. After watching each trailer, the participants were asked to rate how much they liked the trailer they’d just seen, and how much they’d be willing to pay for a DVD of each film.
After they had watched all 18 trailers, the subjects were handed the DVDs for the 18 films and asked to sort the DVDs by preference. Participants were given the three DVDs they most preferred.
The study found that the EEG readings were notably more accurate than the participants’ conscious statements in predicting which film the participant would actually choose. ama.org
Frequent sauna use reduces cardiac risk
Frequently – even daily – taking a sauna can reduce the risk of cardiac death, according to a study carried out at the University of Eastern Finland. The 20-year follow-up study discovered that men taking a sauna four to seven times a week were 63 percent less likely to experience a sudden cardiac death than those taking a sauna once a week. Further, the occurrence of death due to coronary artery disease and other cardiac events, as well as overall mortality, were less frequent in the group taking saunas several times a week.
Also, time spent taking a sauna was linked to the risk of cardiac death. Those who spent more than 19 minutes in the sauna at a time were 52 percent less likely to experience a sudden cardiac death than those spending only 11 minutes in the sauna at a time. The risk of death due to a cardiac event was also otherwise smaller in those spending longer times in the sauna.
The findings were published in JAMA Internal Medicine. uef.fi