Acknowledgements
The authors are grateful to M Fortes, C Vieira Viegas and B Rozmyslowicz for valuable discussions and contributions to this article. B Rozmyslowicz is also acknowledged for the preparation of .
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.
No writing assistance was utilized in the production of this manuscript.