Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Manipulation of Colloids by Nonequilibrium Depletion Force in
  Temperature Gradient   The non-equilibrium distribution of colloids in a polymer solution under a
temperature gradient is studied experimentally. A slight increase of local
temperature by a focused laser drives the colloids towards the hot region,
resulting in the trapping of the colloids irrespective of their own
thermophoretic properties. An amplification of the trapped colloid density with
the polymer concentration is measured, and is quantitatively explained by
hydrodynamic theory. The origin of the attraction is a migration of colloids
driven by a non-uniform polymer distribution sustained by the polymer's
thermophoresis. These results show how to control thermophoretic properties of
colloids.

35
The categories of this paper are: mtrl-th
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
2
The categories of this paper are: math
6
The categories of this paper are: astro-ph