Polish authorities say that they have arrested and pressed charges against a 38-year-old Polish woman with Islamic extremist sympathies who planted an explosive device on a street in central Warsaw earlier this month. There were no injuries. Police said in a statement published on Monday that the woman placed the device in Warsaw on the night of Nov. 10-11 and then took a train back to her home in western Poland. Nobody was hurt, but police said the device had the potential to hurt many people.