Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Radio Wave 'Messengers' of Periodic Gravitational Radiation and the
  Problem of Gravitationally Induced Nonlinearity in Electrodynamic Systems   We discuss a gravitationally induced nonlinearity in hierarchic systems. We
consider the generation of extremely low-frequency radio waves with a frequency
of the periodic gravitational radiation; the generation is due to an induced
nonlinear self-action of electromagnetic radiation in the vicinity of the
gravitational-radiation source. These radio waves are a fundamentally new type
of response of an electrodynamic system to gravitational radiation. That is why
we here use an unconventional term: radio-wave messengers of periodic
gravitational radiation.

28
The categories of this paper are: alg-geom
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
19
The categories of this paper are: eess
17
The categories of this paper are: q-fin
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
3
The categories of this paper are: physics
22
The categories of this paper are: chao-dyn
16
The categories of this paper are: stat
14
The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an