Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Shift in the speed of reaction diffusion equation with a cut-off: pushed
  and bistable fronts   We study the change in the speed of pushed and bistable fronts of the
reaction diffusion equation in the presence of a small cut-off. We give
explicit formulas for the shift in the speed for arbitrary reaction terms f(u).
The dependence of the speed shift on the cut-off parameter is a function of the
front speed and profile in the absence of the cut-off. In order to determine
the speed shift we solve the leading order approximation to the front profile
u(z) in the neighborhood of the leading edge and use a variational principle
for the speed. We apply the general formula to the Nagumo equation and recover
the results which have been obtained recently by geometric analysis. The
formulas given are of general validity and we also apply them to a class of
reaction terms which have not been considered elsewhere.

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The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
10
The categories of this paper are: q-bio
33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
3
The categories of this paper are: physics
6
The categories of this paper are: astro-ph
35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math