Summary Companies Asian stock markets: Japan core inflation eases, unlikely to move BOJ Yuan firms after PBOC fixed guidance much stronger than forecast 10-yr Treasuries rebound after sell-off, dollar hold gains SYDNEY, Aug 18 (Reuters) - Asian shares were headed for their third straight week of losses on Friday, hammered by concerns about China's ailing economy and fears of U.S. rates staying higher for longer after a run of strong data sent long-term Treasury yields surging. Europe is likely to open lower as well, with EUROSTOXX 50 futures easing 0.3%. S&P 500 futures and Nasdaq futures fell 0.1% and 0.2%,...