Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Understanding Bulk Defects in Topological Insulators from Nuclear-Spin
  Interactions
8
The categories of this paper are: hep-ex
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
14
The categories of this paper are: math-ph
6
The categories of this paper are: astro-ph
30
The categories of this paper are: q-alg
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th
1
The categories of this paper are: cs
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex