Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Electron trapping and detrapping in an oxide two-dimensional electron
  gas: The role of ferroelastic twin walls
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
2
The categories of this paper are: math
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
21
The categories of this paper are: adap-org
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
8
The categories of this paper are: hep-ex