Funding for this research was provided by:
Oulun Yliopisto (24000692)
European Regional Development Fund (539/2010 A31592)
Opetus- ja Kulttuuriministeriö (OKM/17/626/2016, OKM/86/626/2014, OKM/43/626/2015)
Oulu University Hospital (24301140)
Text and Data Mining valid from 2019-01-07
Received: 4 April 2018
Accepted: 21 December 2018
First Online: 7 January 2019
Ethics approval and consent to participate
: The study was approved by the Ethical Committee of the Northern Ostrobothnia Hospital District in Oulu, Finland (94/2011). Written consent for the study was signed by the subjects and their parents.
: Not applicable.
: RA is employed by Polar Electro. The company had no role in the conduct of the study or decision to publish. Otherwise the authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.