Uma Chowdhry, vice president of central research and development at DuPont, has been elected a fellow and foreign honorary member of The American Academy of Arts and Sciences. She was appointed in honor of her engineering contributions in catalysis/surface science, electronic ceramics, high-temperature superconductors and electronic packaging.   . . .   Mobile PET Systems Inc. announced it has changed its named to Molecular Imaging Corp., effective May 6. The company's stock now trades under the symbol "MLRI" on the OTC Bulletin Board. Molecular Imaging is a provider of positron emission tomography imaging to the health care industry.   . . .   Hitachi America Ltd. announced that Hitachi Ltd. is supplying a proton beam therapy system for the treatment of certain types of cancers to The University of Texas M. D. Anderson Cancer Center in Houston, Texas. Terms of the transaction were not disclosed. The center, in partnership with Sanders Morris Harris Inc., a Texas-based investment banking firm, and The Styles Co., a developer and manager of hospitals and healthcare facilities, is building a proton therapy facility. The first patient treatments are expected in early 2006. Hitachi Ltd. Japan and its subsidiary Hitachi America Ltd. will supply the accelerator, beam lines, gantries, nozzles and treatment couches for the facility.