Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Temperature fluctuations in HII regions: ionization by Cosmic Rays as a
  key mechanism
31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio
2
The categories of this paper are: math
19
The categories of this paper are: eess
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga
4
The categories of this paper are: cond-mat