Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Spin polarization and exchange-correlation effects in transport
  properties of two-dimensional electron systems in silicon
6
The categories of this paper are: astro-ph
20
The categories of this paper are: acc-phys
16
The categories of this paper are: stat
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph
21
The categories of this paper are: adap-org
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga