3,224 research outputs found
Controlling the Intrinsic Josephson Junction Number in a Mesa
In fabricating intrinsic Josephson
junctions in 4-terminal mesa structures, we modify the conventional fabrication
process by markedly reducing the etching rates of argon ion milling. As a
result, the junction number in a stack can be controlled quite satisfactorily
as long as we carefully adjust those factors such as the etching time and the
thickness of the evaporated layers. The error in the junction number is within
. By additional ion etching if necessary, we can controllably decrease
the junction number to a rather small value, and even a single intrinsic
Josephson junction can be produced.Comment: to bu published in Jpn. J. Appl. Phys., 43(7A) 200
Influence of electrode thermal conductivity on resistive switching behavior during reset process
Resistive random access memory (RRAM) is the most promising candidate for non-volatile memory (NVM) due to its extremely low operation voltage, extremely fast write/erase speed, and excellent scaling capability. However, an obstacle hindering mass production of RRAM is the non-uniform physical mechanism in its resistance switching process. This study examines the influence of different electrode thermal conductivity on switching behavior during the reset process. Electrical analysis methods and an analysis of current conduction mechanism indicate that better thermal conductivity in the electrode will require larger input power in order to induce more active oxygen ions to take part in the reset process. More active oxygen ions cause a more complete reaction during the reset process, and cause the effective switching gap (dsw) to become thicker. The effect of the electrode thermal conductivity and input power are explained by our model and clarified by electrical analysis methods.
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Lasing on nonlinear localized waves in curved geometry
The use of geometrical constraints opens many new perspectives in photonics
and in fundamental studies of nonlinear waves. By implementing surface
structures in vertical cavity surface emitting lasers as manifolds for curved
space, we experimentally study the impacts of geometrical constraints on
nonlinear wave localization. We observe localized waves pinned to the maximal
curvature in an elliptical-ring, and confirm the reduction in the localization
length of waves by measuring near and far field patterns, as well as the
corresponding dispersion relation. Theoretically, analyses based on a
dissipative model with a parabola curve give good agreement remarkably to
experimental measurement on the transition from delocalized to localized waves.
The introduction of curved geometry allows to control and design lasing modes
in the nonlinear regime.Comment: 6 pages, 6 figure
Resonance in modulation instability from non-instantaneous nonlinearities
To explore resonance phenomena in the nonlinear region, we show by
experimental measurements and theoretical analyses that resonance happens in
modulation instability (MI) from non-instantaneous nonlinearities in
photorefractive crystals. With a temporally periodic modulation in the external
bias voltage, corresponding to a modulation in the nonlinear strength, an
enhancement in the visibility of MI at resonant frequency is reported through
spontaneous optical pattern formations. Modeled by such temporally periodic
nonlinear driving force to the system, theoretical curves obtained from a
nonlinear non-instantaneous Schr\"{o}dinger equation give good agreement to
experimental data. As MI is a universal signature of symmetry-breaking
phenomena, our observation on the resonance in MI may provide a control on
chaotic, solitary, and turbulence waves.Comment: 5 pages, 4 figure
Imperceptible Physical Attack against Face Recognition Systems via LED Illumination Modulation
Although face recognition starts to play an important role in our daily life,
we need to pay attention that data-driven face recognition vision systems are
vulnerable to adversarial attacks. However, the current two categories of
adversarial attacks, namely digital attacks and physical attacks both have
drawbacks, with the former ones impractical and the latter one conspicuous,
high-computational and inexecutable. To address the issues, we propose a
practical, executable, inconspicuous and low computational adversarial attack
based on LED illumination modulation. To fool the systems, the proposed attack
generates imperceptible luminance changes to human eyes through fast intensity
modulation of scene LED illumination and uses the rolling shutter effect of
CMOS image sensors in face recognition systems to implant luminance information
perturbation to the captured face images. In summary,we present a
denial-of-service (DoS) attack for face detection and a dodging attack for face
verification. We also evaluate their effectiveness against well-known face
detection models, Dlib, MTCNN and RetinaFace , and face verification models,
Dlib, FaceNet,and ArcFace.The extensive experiments show that the success rates
of DoS attacks against face detection models reach 97.67%, 100%, and 100%,
respectively, and the success rates of dodging attacks against all face
verification models reach 100%
Distance-dependent plasmon-enhanced fluorescence of upconversion nanoparticles using polyelectrolyte multilayers as tunable spacers
Lanthanide-doped upconversion nanoparticles (UCNPs) have attracted widespread interests in bioapplications due to their unique optical properties by converting near infrared excitation to visible emission. However, relatively low quantum yield prompts a need for developing methods for fluorescence enhancement. Plasmon nanostructures are known to efficiently enhance fluorescence of the surrounding fluorophores by acting as nanoantennae to focus electric field into nano-volume. Here, we reported a novel plasmon-enhanced fluorescence system in which the distance between UCNPs and nanoantennae (gold nanorods, AuNRs) was precisely tuned by using layer-by-layer assembled polyelectrolyte multilayers as spacers. By modulating the aspect ratio of AuNRs, localized surface plasmon resonance (LSPR) wavelength at 980 nm was obtained, matching the native excitation of UCNPs resulting in maximum enhancement of 22.6-fold with 8 nm spacer thickness. These findings provide a unique platform for exploring hybrid nanostructures composed of UCNPs and plasmonic nanostructures in bioimaging applications
Evolving MCDM Applications Using Hybrid Expert-Based ISM and DEMATEL Models: An Example of Sustainable Ecotourism
Ecological degradation is an escalating global threat. Increasingly, people are expressing awareness and priority for concerns about environmental problems surrounding them. Environmental protection issues are highlighted. An appropriate information technology tool, the growing popular social network system (virtual community, VC), facilitates public education and engagement with applications for existent problems effectively. Particularly, the exploration of related involvement behavior of VC member engagement is an interesting topic. Nevertheless, member engagement processes comprise interrelated sub-processes that reflect an interactive experience within VCs as well as the value co-creation model. To address the top-focused ecotourism VCs, this study presents an application of a hybrid expert-based ISM model and DEMATEL model based on multi-criteria decision making tools to investigate the complex multidimensional and dynamic nature of member engagement. Our research findings provide insightful managerial implications and suggest that the viral marketing of ecotourism protection is concerned with practitioners and academicians alike
Feasibility and accuracy evaluation of three human papillomavirus assays for FTA card-based sampling: a pilot study in cervical cancer screening
Early Postweaning Treatment with Dimethyl Fumarate Prevents Prenatal Dexamethasone- and Postnatal High-Fat Diet-Induced Programmed Hypertension in Male Rat Offspring
Prenatal dexamethasone (DEX) exposure, postnatal high-fat (HF) intake, and oxidative stress are closely related to the development of hypertension. Nuclear factor erythroid-derived 2-related factor 2 (Nrf2) regulates oxidative stress. Dimethyl fumarate (DMF) reportedly activates Nrf2 and protects against oxidative stress damage. We examined a 4-month-old male rat offspring from five groups (n=8 for each group): control, DEX (0.1 mg/kg i.p. from a gestational age of 16 to 22 days), HF (D12331 diet from weaning to 4 months of age), and DEX + HF, DEX + HF + DMF (50 mg/kg/day via gastric gavage for 3 weeks after weaning). We found that postnatal HF intake aggravated prenatal DEX-induced hypertension in adult male offspring, which could be prevented by DMF treatment. The beneficial effects of DMF treatment include an increase in renal Nrf2 gene expression, reduction of oxidative stress, decrease in plasma asymmetric dimethylarginine (ADMA) and renal soluble epoxide hydrolase protein levels, increase in the L-arginine-to-ADMA ratio, and activation of genes related to nutrient sensing and autophagy (e.g., Pparb, Pparg, Ppargc1a, Ulk1, and Atg5). In conclusion, better understanding of the impact of the Nrf2 signaling pathway in the two-hit model will aid in protecting children exposed to antenatal corticosteroids and a postnatal HF diet from programmed hypertension
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