Conductor Paul Polivnick returns to Pro Arte in April for a powerful program of music for string orchestra. Antonín Dvořák transformed an early Andante religioso for string quartet into the luminous Nocturne. Dmitri Shostakovich’s Chamber Symphony was also originally scored for string quartet, but its later orchestration conveys his personal anguish with even greater intensity. Inspired by Latin liturgical texts, Adolphus Hailstork’s Sonata da Chiesa is a contemporary American take on the 17th-century church sonata. Edward Elgar fashioned his rich Introduction and Allegro after another Baroque form, the concerto grosso, which assigns a solo role to a group of players—in this case, a string quartet.