Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Ultra-low acoustic-phonon-limited mobility and giant phonon-drag
  thermopower in MgZnO/ZnO heterostructures
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
13
The categories of this paper are: quant-ph
12
The categories of this paper are: nucl-th
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
15
The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
19
The categories of this paper are: eess
16
The categories of this paper are: stat