Letter to the editor regarding "In vitro flow investigations in the aortic arch during cardiopulmonary bypass with stereo-PIV". Issue 1 (4th January 2016) - Andreas, Martin; Wiedemann, Dominik; Messner, Barbara; Hutschala, Doris; Habertheuer, Andreas; Bernhard, David; Petzelbauer, Peter; Laufer, Guenther