Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evaluation of the duty ratio of bacterial flagellar motor by a dynamic
  load control   Bacterial flagellar motor is one of the most complex and sophisticated nano
machineries in nature. A duty ratio $D$ is a fraction of time that the stator
and the rotor interact and is a fundamental property to characterize the motor
but remains to be determined. It is known that the stator units of the motor
bind to and dissociate from the motor dynamically to control the motor torque
depending on the load on the motor. At low load where the kinetics such as a
proton translocation speed limits the rotation rate, the dependency of the
rotation rate on the number of stator units $N$ infers $D$; the dependency
becomes larger for smaller $D$. Contradicting observations supporting both the
small and large $D$ have been reported. A dilemma is that it is difficult to
explore a broad range of $N$ at low load because the stator units easily
dissociate, and $N$ is limited to one or two at vanishing load. Here, we
develop an electrorotation method to dynamically control the load on the
flagellar motor of {\it Salmonella} with a calibrated magnitude of the torque.
By instantly reducing the load for keeping $N$ high, we observed that the speed
at low load depends on $N$, implying a small duty ratio. We recovered the
torque-speed curves of individual motors and evaluated the duty ratio to be
$0.14 \pm 0.04$ from the correlation between the torque at high load and the
rotation rate at low load.

24
The categories of this paper are: dg-ga
13
The categories of this paper are: quant-ph
28
The categories of this paper are: alg-geom
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
2
The categories of this paper are: math
6
The categories of this paper are: astro-ph
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
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The categories of this paper are: comp-gas
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The categories of this paper are: patt-sol
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The categories of this paper are: chao-dyn
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The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs