Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Microwave Cherenkov Radiation from a Particle-in-flight to a
  Semi-infinite Layered Medium   Some part of the microwave Cherenkov radiation from a particle-in-flight from
vacuum to semi-infinite layered medium is redirected by the periodical
structure of medium in the backward direction. This part of radiation is
quasi-monochromatic.

34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
25
The categories of this paper are: patt-sol
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
28
The categories of this paper are: alg-geom
6
The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
13
The categories of this paper are: quant-ph
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph