Chapel Hills Womens Voices Chorus perform concerts this weekend that have as their centerpiece Vivaldis Gloria, sung, as originally conceived, by a womens chorus with Baroque orchestra. The second half showcases pieces by North American composers that reflect the themes of the Gloria. First Presbyterian Church, Durham, 4 p.m. Saturday; University United Methodist Church, Chapel Hill, 3 p.m. Sunday. $5-$15. 919-923-3869; womensvoiceschorus.org.