Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Separated spin-up and spin-down evolution of degenerated electrons in
  two dimensional systems: Dispersion of longitudinal collective excitations in
  plane and nanotube geometry
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat
24
The categories of this paper are: dg-ga
2
The categories of this paper are: math
18
The categories of this paper are: econ
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an