Copyright © Bauer et al.; licensee Springer. 2015.  This is an Open Access article distributed under the terms of the Creative Commons Attribution License (<a href="http://creativecommons.org/licenses/by/4.0">http://creativecommons.org/licenses/by/4.0</a>), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited.
Except where otherwise noted, this item's license is described as Copyright © Bauer et al.; licensee Springer. 2015. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (<a href="http://creativecommons.org/licenses/by/4.0">http://creativecommons.org/licenses/by/4.0</a>), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited.