4,201 research outputs found
Vortex-flow electromagnetic emission in stacked intrinsic Josephson junctions
We confirmed the existence of the collective transverse plasma modes excited
by the motion of the Josephson vortex lattice in stacked intrinsic Josephson
junctions of BiSrCaCuO by observing the multiple
subbranches in the Josephson-vortex-flow current-voltage characteristics. We
also observed the symptom of the microwave emission from the resonance between
the Josephson vortex lattice and the collective transverse plasma modes, which
provides the possibility of developing Josephson-vortex-flow electromagnetic
oscillators.Comment: 4 pages, 3 figure
DNA Steganalysis Using Deep Recurrent Neural Networks
Recent advances in next-generation sequencing technologies have facilitated
the use of deoxyribonucleic acid (DNA) as a novel covert channels in
steganography. There are various methods that exist in other domains to detect
hidden messages in conventional covert channels. However, they have not been
applied to DNA steganography. The current most common detection approaches,
namely frequency analysis-based methods, often overlook important signals when
directly applied to DNA steganography because those methods depend on the
distribution of the number of sequence characters. To address this limitation,
we propose a general sequence learning-based DNA steganalysis framework. The
proposed approach learns the intrinsic distribution of coding and non-coding
sequences and detects hidden messages by exploiting distribution variations
after hiding these messages. Using deep recurrent neural networks (RNNs), our
framework identifies the distribution variations by using the classification
score to predict whether a sequence is to be a coding or non-coding sequence.
We compare our proposed method to various existing methods and biological
sequence analysis methods implemented on top of our framework. According to our
experimental results, our approach delivers a robust detection performance
compared to other tools
Collective Josephson vortex dynamics in a finite number of intrinsic Josephson junctions
We report the experimental confirmation of the collective transverse plasma
modes excited by the Josephson vortex lattice in stacks of intrinsic Josephson
junctions in BiSrCaCuO single crystals. The
excitation was confirmed by analyzing the temperature () and magnetic field
() dependencies of the multiple sub-branches in the Josephson-vortex-flow
region of the current-voltage characteristics of the system. In the near-static
Josephson vortex state for a low tunneling bias current, pronounced
magnetoresistance oscillations were observed, which represented a
triangular-lattice vortex configuration along the c axis. In the dynamic vortex
state in a sufficiently high magnetic field and for a high bias current,
splitting of a single Josephson vortex-flow branch into multiple sub-branches
was observed. Detailed examination of the sub-branches for varying field
reveals that sub-branches represent the different modes of the Josephson-vortex
lattice along the c axis, with varied configuration from a triangular to a
rectangular lattices. These multiple sub-branches merge to a single curve at a
characteristic temperature, above which no dynamical structural transitions of
the Josephson vortex lattice is expected
Heating-compensated constant-temperature tunneling measurements on stacks of BiSrCaCuO intrinsic junctions
In highly anisotropic layered cuprates such as BiSrCaCuO
tunneling measurements on a stack of intrinsic junctions in a high-bias range
are often susceptible to self-heating. In this study we monitored the
temperature variation of a stack ("sample stack") of intrinsic junctions by
measuring the resistance change of a nearby stack ("thermometer stack") of
intrinsic junctions, which was strongly thermal-coupled to the sample stack
through a common Au electrode. We then adopted a
proportional-integral-derivative scheme incorporated with a substrate-holder
heater to compensate the temperature variation. This in-situ temperature
monitoring and controlling technique allows one to get rid of spurious
tunneling effects arising from the self-heating in a high bias range.Comment: 3 pages, 3 figure
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