Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Propagation of terahertz waves in a dust acoustic wave   The propagation of terahertz waves in a dust acoustic wave is investigated
numerically. By assuming a sinus profile of the dust number density in the dust
acoustic waves, the transmission properties are calculated using finite
difference time domain method. It shows that the dust acoustic wave can
function similarly as a Bragg filter to block the terahertz waves of a certain
wavelength. The bandwidth of the filter depends on the density profile of the
dust acoustic wave.

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The categories of this paper are: quant-ph
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The categories of this paper are: stat
2
The categories of this paper are: math
6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: q-alg
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The categories of this paper are: hep-lat
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The categories of this paper are: econ
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The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th