NEW YORK/LONDON (Reuters) – Most bouts of global market volatility in recent years have featured one constant: the U.S. dollar strengthens as investors clamor for the perceived safety of U.S. assets such as Treasuries. By contrast, over the last two previous trading days, the dollar lost 4.0 percent against the yen, while dropping to a seven-month low versus the euro on Monday, as world stock markets slumped and emerging market currencies plummeted.