One of the cool programs at Peabody (at least it looks cool to an outsider like me) is Opera Etudes, which gets grad student composers creating new works for performers at the conservatory. At 7:30 p.m. tonight, May 4, you can catch seven premieres -- one-act operas, about 15 minutes each, linked together by the theme "Women's Studies." (The perspective of those studies tilts a bit on the male side; only one of the composers and three of the librettists are women.)