Krista Kopper has acted as the responsible adult in the room during the more than dozen times I’ve seen her perform with her peers in the Extemporaneous Music and Arts Society. Whenever her Kansas City colleagues flirt with excess, Kopper can be counted on to apply gentle persuasion to redirect their dissipation. The profundity of her new solo double bass album Blessed Are Those Who Mourn, consequently, isn’t surprising. Composed, performed and titled for women who were “assaulted and then killed while running,” the eight selections represent Kopper’s intention “to fight death with music.” Her tragically essential battle is a magnificently dignified triumph.