Rod Barajas drove in Pedro Alvarez with a second-inning RBI single to give the Pirates a 1-0 victory over the Cubs.  A.J. Burnett did not allow a run in five-and-a-third innings.  He improved to 3-and-2 while striking out six.  Joel Hanrahan locked up his 11th save on the season for Pittsburgh, which snapped a two-game slide.  Ryan Dempster gave up the run in seven-and-a-third innings to take the tough-luck loss and dip to 0-and-3.  Chicago has lost 10 straight games.  The Cubs were 0-for-12 with runners in scoring position, while Pittsburgh was 1-for-8.