Some articles (e.g., sp.8.14) have Abstract as the first word in the first line of their abstract, while others (e.g., sp.8.13) have Abstract on its own line.
This depends on whether there is a blank line between \begin{abstract} and the content of the abstract.
I prefer the former output, where Abstract is not allotted its own line, but either way, we should choose one, and the behavior of the abstract environment's header should not depend on whitespace in the abstract itself.
Some articles (e.g., sp.8.14) have Abstract as the first word in the first line of their abstract, while others (e.g., sp.8.13) have Abstract on its own line.
This depends on whether there is a blank line between
\begin{abstract}
and the content of the abstract.I prefer the former output, where Abstract is not allotted its own line, but either way, we should choose one, and the behavior of the abstract environment's header should not depend on whitespace in the abstract itself.