Mark L. Pearson, a nationally recognized genetic scientist, has been appointed associate director of life sciences for molecular biology of the Du Pont Co.'s central research and development department. His appointment is effective Nov. 19. Pearson, an adjunct professor at the University of Maryland, is director of the molecular biology laboratory and head of the developmental genetics section at the National Cancer Institute's Frederick Cancer Research Facility in Frederick.

Delaney E. Blaine has been elected president of Tempest Technologies Inc., a C3 Inc. subsidiary. Blaine was formerly a vice president of C3. David C. Lucien has been elected vice president for marketing and sales of Tempest Technologies. He was formerly manager of business development for federal sales of Intel Corp.

Stanley E. Harrison has been promoted to president and chief operating officer of the BDM Corp., the principal operating subsidiary of BDM International Inc. in McLean. Earle C. Williams has been named BDM's chairman. He is president and chief executive officer of BDM International and chief executive officer of BDM Corp. Florian N. Hofer has been promoted to executive vice president and chief financial and administrative officer of the BDM Corp.

Donald P. Aiken has been named president of EMC Controls Inc., a subsidiary of Electronic Modules Corp. of Timonium. Aiken was formerly vice president for electronic system development engineering of the Foxboro Co. in Massachusetts.

Linda A. Hodge and Cecily Slater have established the certified public accounting firm of Hodge, Slater & Associates in Gaithersburg. Hodge was formerly in private practice in Gaithersburg and Silver Spring. Slater was formerly a senior staff accountant with Hodge's firm.

Jean S. Hellier, Edward F. Westrick and S. Scott Hellier have been promoted to vice presidents of ORS Associates and Office Relocation Services Inc. of McLean. David B. Eason has been named the firm's principal consultant. He was formerly assistant vice president in charge of facilities of the National Bank of Washington.

Edward T. Wilson has been named government relations counselor of International Business-Government Counsellors Inc. in Washington. Wilson was formerly vice president of Riggs National Bank.

Edmund M. Waller has been named director of the logistics division of Evaluation Research Corp. in Vienna. Waller was formerly with Tracor Inc. Thomas Musson has been named director of ERC's reliability, maintainability and quality engineering division.

John A. Farrell has been elected a partner of the accounting firm Peat Marwick. He will be in charge of the Washington office's private business advisory services. S. Daniel Johnson and Stanley C. Wiseberg have been elected principals of Peat Marwick.

Brant C. Hart Jr. has been appointed regional director of the Continental Care Corp. in Columbia. Continental Care manages about 1,200 nursing homes in six states.

David I. Ginsburg has established D.I.G. Mortgage & Investment Co., a financial brokerage and mortgage banking firm in Gaithersburg. Ginsburg was formerly acting director of real estate business studies of the National Association of Realtors.

Gordon R. Plants has been named a financial planner with L-Z Associates Inc., a Rockville engineering firm.

Robert L. Olcott has been named director of association services of E.F. Hutton and Co. Inc. in Washington. Olcott was formerly director of marketing and development of the National School Boards Association.

Ruth T. Cumbo has been appointed a member of the Prince George's Community College board of trustees. Cumbo supervises Project Head Start for the county's public schools.

F. Joseph Brinig has been named an associate of the law firm of Putbrese & Hunsaker in McLean. He was formerly in private practice in McLean.