Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Internal energy and condensate fraction of a trapped interacting Bose
  gas   We present a semiclassical two-fluid model for an interacting Bose gas
confined in an anisotropic harmonic trap and solve it in the experimentally
relevant region for a spin-polarized gas of Rb-87 atoms, obtaining the
temperature dependence of the internal energy and of the condensate fraction.
Our results are in agreement with recent experimental observations by Ensher et
al.

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The categories of this paper are: cs
20
The categories of this paper are: acc-phys
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The categories of this paper are: chao-dyn
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The categories of this paper are: solv-int
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The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex
32
The categories of this paper are: atom-ph
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The categories of this paper are: stat
27
The categories of this paper are: comp-gas
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The categories of this paper are: hep-ex
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The categories of this paper are: eess
10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
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The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc