Stocks improved slightly, but were still mixed in choppy action late Friday. They were also pointing to a mixed finish for the week. The Dow Jones industrial average and S&P 500 rose 0.5% and 0.2%, respectively. The Nasdaq trimmed a 0.7% loss to 0.3%. Turnover was tracking sharply lower on the Nasdaq and a touch lower on the NYSE. Stratasys (SSYS) rose 2% as it extended rebound efforts. A recent slide erased gains from a breakout past a 69.18 buy