File photo shows Vice Chairwoman of the U.S. Federal Reserve Janet Yellen testifies during her nomination hearing to chair the Federal Reserve before the Senate Banking Committee on Capitol Hill in Washington D.C., capital of the United States, Nov. 14, 2013. The U.S. Senate confirmed Janet Yellen as the next head of the Federal Reserve on Jan. 6, 2014. She would replace outgoing Fed Chairman Ben Bernanke whose term ends at the end of this month. [Photo/Xinhua]