The scientific community is used to publish papers in the PDF format, which is nice to read on big screens, but is an abomination on smaller screens, especially smartphones and e-ink screens (epub readers, kindle…).
All scientists have to read a lot of papers, actually so many that it’d be a relief to be able to read some while on the go, or on ebook readers under the sun. But converting from PDF to epub format is never satisfactory, when we only have access to the PDF and not the source of the paper.
When the latex source is available, such as on arXiv, then some scripting solutions are indeed applicable: see https://github.com/cerisara/arxiv2kindle
But when only the final PDF is given, then even the paying acrobat software can apparently only do it by transforming the PDF into an image (which reduces the rendering quality) and cropping.
My github repository also proposes a similar solution, but based on open-source command-line tools, which reduces the size of full two-columns A4 papers into a sequence of smaller crops that are readable for small screens. They do not really remove content, but rather play with the bounding box dimensions and duplicate.
It’s clearly not a perfect solution, but at least it totally preserves the original rendering of the paper while making it much more readable on a small screen.
The best options shall rather be to write all scientific papers in some epub-compliant format, such as markdown, but we’re pitifully not there yet.