Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Earthquake-like patterns of acoustic emission in crumpled plastic sheets   We report remarkable similarities in the output signal of two distinct
out-of- equilibrium physical systems - earthquakes and the intermittent
acoustic noise emitted by crum- pled plastic sheets - Biaxially Oriented
Polypropylene (BOPP) films. We show that both signals share several statistical
properties including the distribution of energy, distribution of energy in-
crements for distinct time scales, distribution of return intervals and
correlations in the magnitude and sign of energy increments. This analogy is
consistent with the concept of universality in com- plex systems and could
provide some insight on the mechanisms behind the complex behavior of
earthquakes.

22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
5
The categories of this paper are: gr-qc
4
The categories of this paper are: cond-mat
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
19
The categories of this paper are: eess
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex