Tokyo stocks opened higher Thursday, as high-tech shares were pushed up after U.S. chip giant Nvidia Corp. released stronger-than-expected earnings results and an upbeat forecast. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average rose 531.43 points, or 1.39 percent, from Wednesday to 38,793.59. The broader Topix index was up 22.33 points, or 0.85 percent, at 2,649.63. On the top-tier Prime Market, gainers were led by marine transportation, electric appliance and mining issues. At 9 a.m., the U.S. dollar fetched 150.33-36 yen compared with 150.25-35 yen in New York and 150….