Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Casimir Effect for spherical boundaries: A thermofield dynamics approach   The Casimir effect for spherical geometry is calculated using generalized
Thermofield Dynamics for the case of scalar field. Casimir force and Casimir
pressure are presented. It is found that for high temperatures the Casimir
force does change sign.

2
The categories of this paper are: math
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
29
The categories of this paper are: funct-an
6
The categories of this paper are: astro-ph
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con