Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A buckling instability and its influence on microtubule orientation in
  plant cells   In growing plant cells, parallel ordering of microtubules (MTs) along the
inner surface of the cell membrane influences the direction of cell expansion
and thereby plant morphology. For correct expansion of organs that primarily
grow by elongating, such as roots and stems, MTs must bend in the
high-curvature direction along the cylindrically shaped cell membrane in order
to form the required circumferential arrays. Computational studies, which have
recapitulated the self-organization of these arrays, ignored MT mechanics and
assumed MTs follow geodesics of the cell surface. Here, we show, through
analysis of a derived Euler-Lagrange equation, that an elastic MT constrained
to a cylindrical surface will deflect away from geodesics and toward low
curvature directions to minimize bending energy. This occurs when the curvature
of the cell surface is relatively high for a given anchor density. In the limit
of infinite anchor density, MTs always follow geodesics. We compare our
analytical predictions to measured curvatures and anchor densities and find
that the regime in which cells are forming these cortical arrays straddles the
region of parameter space in which arrays must form under the antagonistic
influence of this mechanically induced deflection. Although this introduces a
potential obstacle to forming circumferentially orientated arrays that needs to
be accounted for in the models, it also raises the question of whether plants
use this mechanical phenomenon to regulate array orientation. The model also
constitutes an elegant generalization of the classical Euler-bucking
instability along with an intrinsic unfolding of the associated pitchfork
bifurcation.

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The categories of this paper are: hep-th
18
The categories of this paper are: econ
32
The categories of this paper are: atom-ph
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
8
The categories of this paper are: hep-ex
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
33
The categories of this paper are: plasm-ph