Janet Yellen has been sworn in as chair of the US Federal Reserve, replacing Ben Bernanke in the role. She is the first woman to hold the post.
Her main task will be managing the winding down of the bank's bond-buying stimulus programme without damaging the United States economy.
Ms Yellen, 67, had been Mr Bernanke's deputy for three years. Her term is for four years.
Ms Yellen is professor emeritus at the University of California at Berkeley, where she has been a faculty member since 1980, specialising in business and economics.
The Senate confirmed her in the position on 6 January.
Mr Bernanke is returning to academia after eight years as Fed chairman, and is joining the Brookings Institution as a resident fellow.