SIMON LEWIS PRESIDENT-ELECT Joe Biden has unveiled his picks for several top economic positions, including former Federal Reserve Chair Janet Yellen as his nominee for Treasury Secretary, setting the stage for a more diverse White House. While Biden's transition to the White House appeared to be hitting its stride, the president-elect was hobbling after fracturing his foot while playing with his dog on Saturday. The incoming administration has been hampered for weeks by President Donald Trump who has refused to concede claiming, without evidence, that Biden's November 3 electoral victory was due to fraud. Biden named leading members of an…