Authors’ contributions
All co-authors have contributed to the study conception and design. Material preparation and data collection were done by Ulrik Winsløw, Tharsika Sakthivel, Chaoqun Zheng, and Emil Frandsen and analysis were performed by Ulrik Winsløw, Christian Jøns, Henning Bundgaard, and Niels Risum. The first draft of the manuscript was written by Ulrik Winsløw and was critically revised by all co-authors. All co-authors read and approved the final manuscript.