Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: X-Ray Propagation in Tapered Waveguides: Simulation and Optimization   We use the parabolic wave equation to study the propagation of x-rays in
tapered waveguides by numercial simulation and optimization. The goal of the
study is to elucidate how beam concentration can be best achieved in x-ray
optical nanostructures. Such optimized waveguides can e.g. be used to
investigate single biomolecules. Here, we compare tapering geometries, which
can be parametrized by linear and third-order (Bezier-type) functions and can
be fabricated using standard e-beam litography units. These geometries can be
described in two and four-dimensional parameter spaces, respectively. In both
geometries, we observe a rugged structure of the optimization problem's ``gain
landscape''. Thus, the optimization of x-ray nanostructures in general will be
a highly nontrivial optimization problem.

29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
28
The categories of this paper are: alg-geom
37
The categories of this paper are: supr-con
2
The categories of this paper are: math
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
6
The categories of this paper are: astro-ph
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas