The authors hold the copyright. Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution-NonCommercial 4.0 International License., allowing others to share the work with proper acknowledgement of the authorship and initial publication in this journal. However, authors must affirm that the article is their original work by submitting a Declaration of originality (PDF) via the online submission form. Authors are permitted to share a preprint of their article anywhere at any time.