Asian shares edged higher on Monday but gains were capped by concerns that market volatility may intensify as the U.S. central bank prepares to raise interest rates for the first time in six years. U.S. Federal Reserve Chair Janet Yellen indicated on Friday that it was poised to raise rates this year if the economy keeps improving as expected, though a raft of recent data has suggested it is growing only modestly in the second quarer. Market activity was thin, with the UK, U.S. and many European markets shut for holidays on Monday.