Footnotes

• Contributors JN, LBV, NMC and LJCvL designed the research study. JN conducted the measurements. JN, LBV and LJCvL analysed the data. All the authors wrote the manuscript. JN had primary responsibility for the final content. All the authors approved the final manuscript.

• Competing interests None declared.

• Provenance and peer review Not commissioned; externally peer reviewed.