NEW YORK/LONDON, March 4 : After some steep losses in Asian markets, U.S. and European shares were rising on Wednesday as oil prices took a step back after a dramatic two-day rally and a jump in cryptocurrency encouraged investors even while they cautiously monitored the Middle East war. The dollar fell and U.S. Treasury yields were rising for a third straight day, even as the U.S. and Israel pressed on with round-the-clock assaults on Iran. Also, a U.S. submarine sank an Iranian warship off