The Nikkei stock index jumped about 2 percent Monday morning, rebounding from an eight-day losing streak on buying of technology shares tracking Wall Street gains and exporter issues on a weaker yen. The 225-issue Nikkei Stock Average rose 748.34 points, or 1.99 percent, from Friday to 38,415.75. The broader Topix index was up 50.74 points, or 1.88 percent, at 2,750.28. The U.S. dollar briefly climbed to the lower 154 yen range in Tokyo as it was sought following a rise in U.S. stocks Friday, but it later retreated amid speculation about an interest rate cut by the Federal Reserve in September…