Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Defect Loops in Three-Dimensional Active Nematics as Active Multipoles   We develop a description of defect loops in three-dimensional active nematics
based on a multipole expansion of the far-field director and show how this
leads to a self-dynamics dependent on the loop's geometric type. The dipole
term leads to active stresses that generate a global self-propulsion for splay
and bend loops. The quadrupole moment is non-zero only for non-planar loops and
generates a net `active torque', such that defect loops are both self-motile
and self-orienting. Our analysis identifies right- and left-handed twist loops
as the only force and torque free geometries, suggesting a mechanism for
generating an excess of twist loops. Finally, we determine the Stokesian flows
created by defect loops and describe qualitatively their hydrodynamics.

2
The categories of this paper are: math
5
The categories of this paper are: gr-qc
29
The categories of this paper are: funct-an
37
The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
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The categories of this paper are: cs
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The categories of this paper are: physics
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
22
The categories of this paper are: chao-dyn
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The categories of this paper are: dg-ga
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The categories of this paper are: math-ph