Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Comment on "Total Negative Refraction in Crystals for Ballistic
  Electrons and Light"   In Phys. Rev. Lett. 91, 157404 (2003) Yong Zhang et al. study light
propagation through an interface between two identical but differently oriented
uniaxial crystals. The authors show that the light refraction at the interface
at some region of incident angles is negative. The observed effect of negative
refraction resembles the analogous effect in left-handed materials (LHM)
although the physics is different. In LHM the negative refraction is caused by
a negative group velocity, whereas in the considered case one deals with the
special properties of wave propagation in uniaxial anisotropic media.

12
The categories of this paper are: nucl-th
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The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
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The categories of this paper are: solv-int
20
The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
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The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
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The categories of this paper are: bayes-an
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The categories of this paper are: funct-an
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The categories of this paper are: comp-gas
0
The categories of this paper are: hep-ph