Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Instability of speckle patterns in random media with noninstantaneous
  Kerr nonlinearity   Onset of the instability of a multiple-scattering speckle pattern in a random
medium with Kerr nonlinearity is significantly affected by the noninstantaneous
character of the nonlinear medium response. The fundamental time scale of the
spontaneous speckle dynamics beyond the instability threshold is set by the
largest of times $T_{\mathrm{D}}$ and $\tau_{\mathrm{NL}}$, where
$T_{\mathrm{D}}$ is the time required for the multiple-scattered waves to
propagate through the random sample and $\tau_{\mathrm{NL}}$ is the relaxation
time of the nonlinearity. Inertial nature of the nonlinearity should complicate
the experimental observation of the instability phenomenon.

17
The categories of this paper are: q-fin
18
The categories of this paper are: econ
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
24
The categories of this paper are: dg-ga
34
The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg