Alan B. Miller does not lack confidence. The CEO of Universal Health Services Inc. sat in a conference room last week at the company's King of Prussia headquarters and was a bit surprised at the simple question of how his Fortune 500 company produced an operating margin of 18% last quarter. "Well," Miller sniffed, "we've been in business for 32 years and we've had a lot of good quarters." Miller's company runs and builds hospitals, with efficiency and acquisition being the path to profitability. UHS has acute-care hospitals, ambulatory centers, and behavioral facilities. It acquired 95 more in November when it bought Psychiatric Solutions Inc. for $3.1 billion, bringing the total to 218 facilities, including 10 in Pennsylvania and two in New Jersey.