After months of increasing conflict with doctors and nurses, Beverly (MA) Hospital chief executive Stephen R. Laverty has resigned, ending an eight-year tenure at the facility. In a statement, trustees of the hospital's parent company, Northeast Health System, said Laverty improved the hospital's clinical quality, made it financially stronger, and upgraded equipment. Laverty's tenure, however, was marked by friction between him and the hospital's doctors and nurses, creating a leadership crisis at Beverly Hospital. Henry J. Ramini, MD, an obstetrician who retired in January as trustees board chairman for the hospital's parent company, was named interim chief executive.