Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Proceedings of the 42nd Scandinavian Symposium on Physical Acoustics   The 42nd Scandinavian Symposium on Physical Acoustics was held at Geilo,
Norway from January 27 to January 30, 2019. It was arranged by the Acoustics
and Optics group of the Norwegian Physical Society, and was coordinated by Geir
Pedersen and Lars Hoff. The symposium gathered 52 registered participants,
holding a total of 31 presentations covering various topics and applications of
physical acoustics, such as underwater acoustics, medical ultrasound,
industrial NDT/NDE, waves in solids, and flow acoustics. In addition, a group
of 7 fresh master students from UiO, USN and UiB gave shorter talks introducing
their projects. After the symposium, 3 of these presentations were submitted as
papers to these proceedings.

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The categories of this paper are: cond-mat
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-ex
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The categories of this paper are: comp-gas
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The categories of this paper are: q-bio
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The categories of this paper are: econ
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The categories of this paper are: hep-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: patt-sol
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The categories of this paper are: alg-geom
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The categories of this paper are: funct-an
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The categories of this paper are: chem-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: adap-org