Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Stress-controlled frequency tuning and parametric amplification of the
  vibrations of coupled nanomembranes   Noninvasive tuning of the mechanical resonance frequencies of suspended
parallel nanomembranes in various monolithic arrays is achieved by
piezoelectric control of their tensile stress. Parametric amplification of
their thermal fluctuations is shown to be enhanced by the piezoelectric
actuation and amplification factors of up to 20 dB in the sub-parametric
oscillation threshold regime are observed.

27
The categories of this paper are: comp-gas
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The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
25
The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
31
The categories of this paper are: ao-sci
29
The categories of this paper are: funct-an
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The categories of this paper are: bayes-an
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The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
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The categories of this paper are: chem-ph