Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Manipulation of a Micro-object Using Topological Hydrodynamic Tweezers   Manipulating micro-scale object plays paramount roles in a wide range of
fundamental researches and applications. At micro-scale, various methods have
been developed in the past decades, including optical, electric, magnetic,
aerodynamic and acoustic methods. However, these non-contact forces are
susceptible to external disturbance, and so finding a way to make micro-scale
object manipulation immune to external perturbations is challenging and remains
elusive. Here we demonstrate a method based on new trapping mechanism to
manipulate micro-scale object in a gas flow at ambient conditions. We first
show that the micro-droplet is entrapped into a trapping ring constructed by a
particular toroidal vortex. The vortex works as tweezers to control the
position of the micro-droplet. We then show that the micro-droplet can be
transported along the trapping ring. By virtue of the topological character of
the gas flow, the transport path is able to bypass external strong
perturbations automatically. We further demonstrate a topological transfer
process of the micro-droplet between two hydrodynamic tweezers. Our method
provides an integrated toolbox to manipulate a micro-scale object, with an
intrinsic mechanism that protects the target object from external disturbances.

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The categories of this paper are: quant-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: comp-gas
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The categories of this paper are: econ
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-ex
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The categories of this paper are: astro-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-th
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The categories of this paper are: math
30
The categories of this paper are: q-alg
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The categories of this paper are: nucl-th
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The categories of this paper are: adap-org
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The categories of this paper are: q-fin
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The categories of this paper are: funct-an