Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Remote Sub-Wavelength Focusing of Ultrasonically Activated Lorentz
  Current   We propose the use of a combination of ultrasonic and magnetic fields in
conductive media for the creation of RF electrical current via the Lorentz
force, in order to achieve current generation with extreme sub-wavelength
resolution at large depth. We demonstrate the modeling, generation, and
measurement of Lorentz current in conductive solution, and show that this
current can be localized at a distance of 13 $cm$ from the ultrasonic source to
a region about three orders of magnitude smaller than the corresponding
wavelength of electromagnetic waves at the same operation frequency. Our
results exhibit greater depth, tighter localization, and closer agreement with
prediction than previous work on the measurement of Lorentz current in a
solution of homogeneous conductivity. The proposed method of RF current
excitation overcomes the trade-off between focusing and propagation that is
fundamental in the use of RF electromagnetic excitation alone, and has the
potential to improve localization and depth of operation for RF current-based
biomedical applications.

35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
8
The categories of this paper are: hep-ex
7
The categories of this paper are: hep-th
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
4
The categories of this paper are: cond-mat
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas