Phillies catcher Carlos Ruiz (hamstring strain) and righthanded pitcher Mike Adams (back strain) were placed on the 15-day disabled list Monday, while first baseman Ryan Howard is day to day with a sore left knee. Ruiz and Howard had MRIs on Monday. Ruiz has played in 16 games and is hitting .235 with two RBIs. ‘‘Right now he'll probably be out three to four weeks — relative time frame,’’ Phillies trainer Scott Sheridan said. Howard is hitting .179 in 16 games this month. Starting pitchers Roy Halladay and John Lannan are also on Philadelphia’s DL . . . The Rangers designated righthander Derek Lowe for assignment to make room for Josh Lindblom. Lowe, 39, made the roster out of spring training after signing a minor league contract in March, then allowed 13 earned runs in 13 innings . . . The Mets signed righthanded reliever David Aardsma to a minor league contract and assigned him Triple A Las Vegas. The former Mariners closer signed with New York after opting out of his minor league deal with Miami on Wednesday.