Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Energetic Instability Unjams Sand and Suspension   Jamming is a phenomenon occurring in systems as diverse as traffic, colloidal
suspensions and granular materials. A theory on the reversible elastic
deformation of jammed states is presented. First, an explicit granular
stress-strain relation is derived that captures many relevant features of sand,
including especially the Coulomb yield surface and a third-order jamming
transition. Then this approach is generalized, and employed to consider jammed
magneto- and electro-rheological fluids, again producing results that compare
well to experiments and simulations.

24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph