Leave the Abstract empty if your article falls under any of the following categories: Editorial Book Review, Commentary, Field Grand Challenge, Opinion or specialty Grand Challenge. As a primary goal, the abstract should render the general significance and conceptual advance of the work clearly accessible to a broad readership. References should not be cited in the abstract. Refer to http://www.frontiersin.org/ or TABLE [TAB:01] for abstract requirement and length according to article type. KEYWORDS: Text Text Text Text Text Text Text Text. All article types: you may provide up to 8 keywords; at least 5 are mandatory.