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Article History

Received: 25 May 2018

Accepted: 12 July 2018

First Online: 17 July 2018

Compliance with ethical standards

: The author declares that

: • No conflict of interest exists.

: • The manuscript has not been submitted to more than one journal for simultaneous consideration.

: • The manuscript has not been published previously (partly or in full), unless the new work concerns an expansion of previous work (please provide transparency on the reuse of material to avoid the hint of text recycling (“self-plagiarism”).

: • A single study is not split up into several parts to increase the quantity of submissions and submitted to various journals or to one journal over time (e.g., “salami publishing”).

: • No data have been fabricated or manipulated (including images) to support your conclusions.

: • No data, text, or theories by others are presented as if they were the author’s own (“plagiarism”). Proper acknowledgements to other works must be given (this includes material that is closely copied (near verbatim), summarized, and/or paraphrased); quotation marks are used for verbatim copying of material, and permissions are secured for material that is copyrighted.