Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Surface electromagnetic waves at gradual interfaces between lossy media   A low loss propagating electromagnetic wave is shown to exist at a gradual
interface between two lossy conductive media. The electromagnetic frequency
range of this phenomenon may span from UV optics to RF range. In particular, it
is demonstrated that such a surface wave may be guided by a seafloor-seawater
interface and it may be used in radio communication and imaging underwater.
Similar surface waves may also be guided by various tissue boundaries inside a
human body. For example, such surface wave solutions may exist at planar
interfaces between skull bones and grey matter inside a human head at 6 GHz.

4
The categories of this paper are: cond-mat
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math