Acknowledgements
We would like to sincerely thank J Patience, managing editor, for his outstanding and tireless efforts in conceiving and organizing this special edition. Without his help, this would not have been possible. We would furthermore like to thank I Forsthuber for excellent editorial and otherwise help in the writing of this article.
Financial & competing interests disclosure
The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.