Though concerts are canceled at Symphony Center due to the current public health crisis, Chicago Symphony Orchestra musicians are determined to help lift spirits through impromptu performances. Assistant Concertmaster Yuan-Qing Yu and Assistant Principal Cello Kenneth Olsen have collaborated for years as part of their Civitas Ensemble (regularly featured on the CSO’s free All-Access Chamber Music series). Here they perform Johan Halvorsen’s Passacaglia for Violin and Viola from their respective homes.