Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Elastic properties of 2D colloidal crystals from video microscopy   Elastic constants of two-dimensional (2D) colloidal crystals are determined
by measuring strain fluctuations induced by Brownian motion of particles.
Paramagnetic colloids confined to an air-water interface of a pending drop are
crystallized under the action of a magnetic field, which is applied
perpendicular to the 2D layer. Using video-microscopy and digital
image-processing we measure fluctuations of the microscopic strain obtained
from random displacements of the colloidal particles from their mean
(reference) positions. From these we calculate system-size dependent elastic
constants, which are extrapolated using finite-size scaling to obtain their
values in the thermodynamic limit. The data are found to agree rather well with
zero-temperature calculations.

11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics
29
The categories of this paper are: funct-an
28
The categories of this paper are: alg-geom
6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga