Barbara Ehrenreich, the journalist, activist and author, died at 81 on Thursday at a hospice facility in Alexandria, Va., where she also had a home. Her daughter, Rosa Brooks, said the cause was a stroke. She was the author of more than 20 books including Nickel and Dimed: On (Not) Getting By in America (2001), an undercover account of the indignities, miseries and toil of being a low-wage worker in the United States. It became a best seller and a classic in social justice literature.