Tokyo stocks fell Thursday morning, weighed down by high-tech issues after the earnings results of U.S. chip giant Nvidia Corp. failed to impress investors. The 225-issue Nikkei Stock Average fell 151.42 points, or 0.39 percent, from Wednesday to 38,220.34. The broader Topix index was down 7.72 points, or 0.29 percent, at 2,684.40. The U.S. dollar was caught in a tug-of-war between buying of the yen, seen as a safe-haven asset, and dollar-buying by domestic importers after the earnings report was released, dealers said. At noon, the dollar fetched 144.58-59 yen compared with 144.53-63 yen in N…