The Federal Reserve kept interest rates steady on Wednesday ?as expected, ?but it was not able to comfort bond investors concerned ?about what a deliberate pace of policy tightening will mean for the outlook for longer-term government bonds. The central bank described an economy strong enough to ?keep inflation elevated, yet refrained from raising rates immediately. That deepened uncertainty over how much further policy may need to tighten, analysts said, and over how much compensation investors could demand to hold longer-dated Treasuries, which have soared this year ?to their highest yields in two decades.