LONG BEACH, Calif.–(BUSINESS WIRE)–TRISTAR Insurance Group, Inc., the largest privately held, independent third-party claims administrator in the United States, today announced the appointment of Viviane Ruiz as Senior Vice President of Managed Care, effective immediately. Ruiz joins TRISTAR from Davies North America, where she served as President of Workers’ Compensation, Casualty, and Managed Care, with full P&L accountability across multiple operating entities under distinct business n