Hawthorn Medical Associates is announcing a new affiliation with Steward Health Care Systems of Boston.  Hawthorn's Executive Director James Gularek says the ten year deal with take effect by the end of the year.  The merger impacts about 500 employees, ranging from laboratory technicians to receptionists and administrators.  Further financial details were not available.  Gularek says patients will notice almost nothing about the change, except perhaps more serives being offered in additional locations. He adds Hawthorn doctors will remain Hawthorn doctors , but will be part of a group with Steward negotiating insurance contracts for the network.  Hawthorn will continue to own its buildings, but assets like furniture and equipment will be owned by Steward.