Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nematode Locomotion in Unconfined and Confined Fluids   The millimeter-long soil-dwelling nematode {\it C. elegans} propels itself by
producing undulations that propagate along its body and turns by assuming
highly curved shapes. According to our recent study [PLoS ONE \textbf{7},
e40121 (2012)] all these postures can be accurately described by a
piecewise-harmonic-curvature (PHC) model. We combine this curvature-based
description with highly accurate hydrodynamic bead models to evaluate the
normalized velocity and turning angles for a worm swimming in an unconfined
fluid and in a parallel-wall cell. We find that the worm moves twice as fast
and navigates more effectively under a strong confinement, due to the large
transverse-to-longitudinal resistance-coefficient ratio resulting from the
wall-mediated far-field hydrodynamic coupling between body segments. We also
note that the optimal swimming gait is similar to the gait observed for
nematodes swimming in high-viscosity fluids. Our bead models allow us to
determine the effects of confinement and finite thickness of the body of the
nematode on its locomotion. These effects are not accounted for by the
classical resistive-force and slender-body theories.

31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
36
The categories of this paper are: cmp-lg
16
The categories of this paper are: stat
0
The categories of this paper are: hep-ph
11
The categories of this paper are: hep-lat
13
The categories of this paper are: quant-ph
24
The categories of this paper are: dg-ga
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
19
The categories of this paper are: eess
22
The categories of this paper are: chao-dyn