Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Coefficient of performance at maximum \chi-criterion for Feynman ratchet
  as a refrigerator
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
17
The categories of this paper are: q-fin
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas