Which institute is this Indian theoretical physicist who contributed to studies of S-branes a visiting professor at?
S-brane:  The S-brane was originally proposed by Andrew Strominger in his speculative paper with Michael Gutperle, and another version of S-branes was studied by Ashoke Sen. Ashoke Sen: Ashoke Sen, FRS ( ; Bengali: অশোক সেন ; born 1956) is an Indian theoretical physicist and distinguished professor at the Harish-Chandra Research Institute, Allahabad. Ashoke Sen:  He also is the Morningstar Visiting professor at MIT and a distinguished professor at the Korea Institute for Advanced Study.
MIT