The paper Dr. Howell has been given to review is considered privileged information, and the timing of its publication at this point is speculative. Therefore, to use results from the paper in her proposal would be unethical. Dr. Howell is free, however, to contact the author (if the refereeing process allows the referees to see the author's name) and ask if he or she has preprints on recent work. If she is sent this paper in preprint form, then the author is presumably comfortable with its further dissemination (with, of course, proper attribution).