By Caroline Valetkevitch NEW YORK (Reuters) -Global stocks were mixed on Tuesday, with Wall Street falling and European shares gaining, while Treasury yields dipped as investors speculated whether the U.S. Federal Reserve may hint at a slower pace of tightening this week. Still, investors were also digesting Tuesday’s data showing U.S. job openings unexpectedly rose in September, suggesting that demand for labor remains strong despite the Fed’s recent rate hikes. The Fed is expected to raise interest rates by 75 basis points on Wednesday, but investors will look for any signals the Fed may be …