Wow, those downvotes are pretty strong! Clearly I'm wrong - what am I missing?
There are many machine learning libraries that have good implementations of LDA (e.g. Gensim), so it should be "relatively" straightforward to create the topics and clustering based on the abstracts of the papers.
But one of the listed papers is also by Kapathy ("Deep Fragment Embeddings for Bidirectional Image Sentence Mapping"), and I think this might be what nl is complimenting as being done quickly.