Death by volcanic eruption Most scientists agree that dinosaurs became extinct as a result of a meteor strike 65 million years ago near the Yucatan Peninsula. But now scientists are suggesting that another mass extinction event occurred about 200,000 years earlier: a volcanic eruption on the Deccan Plateau of India. The eruption filled the atmosphere with aerosols that led to warming and,eventually,the extinction of much of marine life,especially shelled invertebrates on the ocean floor. This presents a more nuanced view of the extinction, said Thomas S. Tobin,a paleontologist at the University of Washington and the studys lead author. It appears that both of these things happened in a short period of time. Tobin and his colleagues report their findings in the journal Palaeogeography,Palaeoclimatology,Palaeoecology. His team gathered fossils from Seymour Island,off the Antarctic Peninsula. The island has sediment deposits that were rich in fossils and provided the scientists with an abundance of information; the fossils confirmed that after the Deccan eruption,there was a mass extinction of marine animals. We generated paleontological data that gives us the ranges of these species through time, he said. It allows us to determine when a species went extinct. To determine when the fossils were deposited,the scientists used magnetostratigraphy,a technique that provides information about the earths magnetic field over time. The scientists hope to confirm their results by repeating the experiment on Seymour Island and the North Pole. Computer use in bed disrupts sleep In todays gadget-obsessed world,sleep experts often say that for a better nights rest,people should click the off buttons on their smartphones and tablets before tucking in for the night. Electronic devices stimulate brain activity,they say,disrupting your ability to drift off to sleep. But according to the National Sleep Foundation,more than 90 percent of Americans regularly use a computer or electronic device of some kind in the hour before bed. Increasingly,researchers are finding that artificial light from some devices at night may tinker with brain chemicals that promote sleep. Researchers at Rensselaer Polytechnic Institute showed that exposure to light from computer tablets significantly lowered levels of the hormone melatonin,which regulates our internal clocks and plays a role in the sleep cycle. In the study,published in the journal Applied Ergonomics,the researchers had volunteers read,play games and watch movies on an iPad,iPad 2 or PC tablet for various amounts of time while measuring the amount of light their eyes received. They found that two hours of exposure to a bright tablet screen at night reduced melatonin levels by about 22 percent. Studies of college students using computers at night have suggested similar effects on melatonin. And researchers say melatonin suppression may not only cause sleep disturbances,but also raise the risk of obesity,diabetes and other disorders. To be on the safe side,the authors of the latest study suggest limiting computer use before bed,or at the very least dimming your screen as much as possible.
