Complex sentence: At the time "mathematics" was interpreted as pure mathematics rather than applied mathematics, with the result that although the US now has more and better pure mathematicians than any other country in the world, it still has an shortage of applied mathematicians.
Split into simpler sentences: At the time, "mathematics" was interpreted as pure mathematics rather than applied mathematics. As a result, although the US had more and better pure mathematicians than any other country in the world, it still had a shortage of applied mathematicians.