The U.S. economy remains sound and will overcome recent market turbulence, allowing the Federal Reserve to continue tightening its monetary policy as planned, a top Fed official said on Thursday. Cleveland Fed President Loretta Mester said that while the global selloff in stocks and oil markets through January poses risks, she is not about to cut her expectations of continued U.S. economic growth and labor market improvement. The comments, which echoed those this week of Fed Vice Chairman Stanley Fischer, suggested there is a camp within the U.S.