Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Universal hydrodynamic mechanisms for crystallization in active
  colloidal suspensions   The lack of detailed balance in active colloidal suspensions allows
dissipation to determine stationary states. Here we show that slow viscous flow
produced by polar or apolar active colloids near plane walls mediates
attractive hydrodynamic forces that drive crystallization. Hydrodynamically
mediated torques tend to destabilize the crystal but stability can be regained
through critical amounts of bottom-heaviness or chiral activity. Numerical
simulations show that crystallization is not nucleational, as in equilibrium,
but is preceded by a spinodal-like instability. Harmonic excitations of the
active crystal relax diffusively but the normal modes are distinct from an
equilibrium colloidal crystal. The hydrodynamic mechanisms presented here are
universal and rationalize recent experiments on the crystallization of active
colloids.

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The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
6
The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th