Applications begin to trickle into the filing room in the basement of Harvard’s Office of Admissions in the fall, and by December, the stream of applications has become a deluge. The 30 students who work in the file room begin to file applications on Oct. 1, placing material submitted by applicants into alphabetized folders that fill dozens of filing cabinets in the long, narrow file room. In January, a team of 40 students from the surrounding area, drawn mainly from the University of Massachusetts system, processes the bulk of the applications.