Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Uphill migration in coupled driven particle systems   In particle systems subject to a nonuniform drive, particle migration is
observed from the driven to the non--driven region and vice--versa, depending
on details of the hopping dynamics, leading to apparent violations of Fick's
law and of steady--state thermodynamics. We propose and discuss a very basic
model in the framework of independent random walkers on a pair of rings, one of
which features biased hopping rates, in which this phenomenon is observed and
fully explained.

6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
2
The categories of this paper are: math