Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The HARPS search for southern extra-solar planets. XXXI. Magnetic
  activity cycles in solar-type stars: statistics and impact on precise radial
  velocities
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
17
The categories of this paper are: q-fin
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con