Nikkei opened 0.73 percent higher Tuesday morning after sinking below the 14,000 line, as buying on dips outpaced selling triggered by jitters over recent volatility in the market. At 9:15 a.m., the 225-issue Nikkei Stock Average was up 102.83 points, or 0.73 percent, from Monday at 14,245.48, after dipping to as low as 13,943.62, down almost 200 points. The broader Topix index of all First Section issues on the Tokyo Stock Exchange was up 7.68 points, or 0.67 percent, at 1,161. 75.