Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Turbulent diffusion in protoplanetary discs: the effect of an imposed
  magnetic field
1
The categories of this paper are: cs
18
The categories of this paper are: econ
0
The categories of this paper are: hep-ph
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
16
The categories of this paper are: stat
2
The categories of this paper are: math
35
The categories of this paper are: mtrl-th