2,602 research outputs found
Periodic Modulation of Extraordinary Optical Transmission through Subwavelength Hole Arrays using Surrounding Bragg Mirrors
The enhanced light transmission through an array of subwavelength holes
surrounded by Bragg mirrors is studied, showing that the mirrors act to confine
the surface plasmons associated with the Extraordinary Optical Transmission
effect, forming a surface resonant cavity. The overall effect is increased
light transmission intensity by more than a factor of three beyond the already
enhanced transmission, independent of whether the Bragg mirrors are on the
input or the output side of the incident light. The geometry of the Bragg
mirror structures controls the enhancement, and can even reduce the
transmission in half. By varying these geometric parameters, we were able to
periodically modulate the transmission of light for specific wavelengths,
consistent with the propagation and interference of surface plasmon waves in a
resonant cavity. FDTD simulations and a wave propagation model verify this
effect.Comment: 9 pages, 5 figure
Numerical Simulation of the Interaction between Slender Body Vortices and a Fin
The interaction between slender body vortices and a single fin located down the axis of the body is investigated numerically for angle of attack of 30 deg. and Reynolds number of 6000. The present research includes a parametric study on the effects of fin axial and azimuthal positions on the development of the vortex system. A numerical method based on the pseudo-compressibility is used for solving the three-dimensional incompressible Navier-Stokes equations using Lower-Upper Symmetric Gauss-Seidel implicit scheme.
The numerical results show that the vortices remain very coherent and attached to the body until they reach the fin section where they become less coherent and begin to
separate from the body. Also, the result shows that the fin location does not affect the upstream development of the vortices but it does affect the location at which the vortices separate from the body. The effect of azimuthal fin positions was also investigated. As
azimuthal angle of the fin increased, the size of the vortex on the port side decreased,
but the starboard side vortex grew in size and moved across the leeward ray to the port
side. The computed results are found to agree well with the experimental data
Anisotropic Acoustic Plasmons in Black Phosphorus
Recently, it was demonstrated that a graphene/dielectric/metal configuration
can support acoustic plasmons, which exhibit extreme plasmon confinement an
order of magnitude higher than that of conventional graphene plasmons. Here, we
investigate acoustic plasmons supported in a monolayer and multilayers of black
phosphorus (BP) placed just a few nanometers above a conducting plate. In the
presence of a conducting plate, the acoustic plasmon dispersion for the
armchair direction is found to exhibit the characteristic linear scaling in the
mid- and far-infrared regime while it largely deviates from that in the long
wavelength limit and near-infrared regime. For the zigzag direction, such
scaling behavior is not evident due to relatively tighter plasmon confinement.
Further, we demonstrate a new design for an acoustic plasmon resonator that
exhibits higher plasmon confinement and resonance efficiency than BP ribbon
resonators in the mid-infrared and longer wavelength regime. Theoretical
framework and new resonator design studied here provide a practical route
toward the experimental verification of the acoustic plasmons in BP and open up
the possibility to develop novel plasmonic and optoelectronic devices that can
leverage its strong in-plane anisotropy and thickness-dependent band gap
Application of Artificial Neural Network to Search for Gravitational-Wave Signals Associated with Short Gamma-Ray Bursts
We apply a machine learning algorithm, the artificial neural network, to the
search for gravitational-wave signals associated with short gamma-ray bursts.
The multi-dimensional samples consisting of data corresponding to the
statistical and physical quantities from the coherent search pipeline are fed
into the artificial neural network to distinguish simulated gravitational-wave
signals from background noise artifacts. Our result shows that the data
classification efficiency at a fixed false alarm probability is improved by the
artificial neural network in comparison to the conventional detection
statistic. Therefore, this algorithm increases the distance at which a
gravitational-wave signal could be observed in coincidence with a gamma-ray
burst. In order to demonstrate the performance, we also evaluate a few seconds
of gravitational-wave data segment using the trained networks and obtain the
false alarm probability. We suggest that the artificial neural network can be a
complementary method to the conventional detection statistic for identifying
gravitational-wave signals related to the short gamma-ray bursts.Comment: 30 pages, 10 figure
ENSO Teleconnection Pattern Changes over the Southeastern United States under a Climate Change Scenario in CMIP5 Models
A strong teleconnection exists between the sea surface temperature (SST) over the tropical Pacific and the winter precipitation in the southeastern United States (SE US).This feature is adopted to validate the fidelity of Coupled Model Intercomparison Project Phase 5 (CMIP5) in this study. In addition, the authors examine whether the teleconnection pattern persists in the future under a global warming scenario. Generally, most of the eight selected models show a positive correlation between November SST over Ni˜no 3 region and December–February (DJF) mean daily precipitation anomalies over the SE US, consistent with the observation. However, the models with poor realization of skewness of Ni˜no indices fail to simulate the realistic teleconnection pattern in the historical simulation. In the Representative Concentration Pathways 8.5 (RCP8.5) run, all of the models maintain positive and slightly increased correlation patterns. It is noteworthy that the region with strong teleconnection pattern shifts northward in the future. Increased variance of winter precipitation due to the SST teleconnection is shown over Alabama and Georgia rather than over Florida under the RCP8.5 scenario in most of themodels, differing fromthe historical run in which the precipitation in Florida is the most attributable to the eastern Pacific SST
ENSO Teleconnection Pattern Changes over the Southeastern United States under a Climate Change Scenario in CMIP5 Models
A strong teleconnection exists between the sea surface temperature (SST) over the tropical Pacific and the winter precipitation in the southeastern United States (SE US).This feature is adopted to validate the fidelity of Coupled Model Intercomparison Project Phase 5 (CMIP5) in this study. In addition, the authors examine whether the teleconnection pattern persists in the future under a global warming scenario. Generally, most of the eight selected models show a positive correlation between November SST over Ni˜no 3 region and December–February (DJF) mean daily precipitation anomalies over the SE US, consistent with the observation. However, the models with poor realization of skewness of Ni˜no indices fail to simulate the realistic teleconnection pattern in the historical simulation. In the Representative Concentration Pathways 8.5 (RCP8.5) run, all of the models maintain positive and slightly increased correlation patterns. It is noteworthy that the region with strong teleconnection pattern shifts northward in the future. Increased variance of winter precipitation due to the SST teleconnection is shown over Alabama and Georgia rather than over Florida under the RCP8.5 scenario in most of themodels, differing fromthe historical run in which the precipitation in Florida is the most attributable to the eastern Pacific SST
Hidden Local Symmetry and Infinite Tower of Vector Mesons for Baryons
In an effort to access dense baryonic matter relevant for compact stars in a
unified framework that handles both single baryon and multibaryon systems on
the same footing, we first address a holographic dual action for a single
baryon focusing on the role of the infinite tower of vector mesons
deconstructed from five dimensions. To leading order in 't Hooft coupling
, one has the Bogomol'nyi-Prasad-Sommerfield (BPS)
Skyrmion that results when the warping of the bulk background and the
Chern-Simons term in the Sakai-Sugimoto D4/D8- model are
ignored. The infinite tower was found by Sutcliffe to induce flow to a
conformal theory, i.e., the BPS. We compare this structure to that of the SS
model consisting of a 5D Yang-Mills action in warped space and the Chern-Simons
term in which higher vector mesons are integrated out while preserving hidden
local symmetry and valid to and in the chiral counting.
We point out the surprisingly important role of the meson that figures
in the Chern-Simons term that encodes chiral anomaly in the baryon structure
and that may be closely tied to short-range repulsion in nuclear interactions.Comment: 9 pages, REVTeX, to be published in Phys. Rev.
TSLP Induces Mast Cell Development and Aggravates Allergic Reactions through the Activation of MDM2 and STAT6
Thymic stromal lymphopoietin (TSLP) is known to promote T helper type 2 cell–associated inflammation. Mast cells are major effector cells in allergic inflammatory responses. We noted that the population and maturation of mast cells were reduced in TSLP-deficient mice (TSLP-/-). Thus, we hypothesized that TSLP might affect mast cell development. We found that TSLP induced the proliferation and differentiation of mast cells from bone marrow progenitors. TSLP-induced mast cell proliferation was abolished by depletion of mouse double minute 2 (MDM2) and signal transducers and activators of transcription 6 (STAT6), as an upstream activator of MDM2. TSLP-/-, in particular, had a considerable deficit in the expression of MDM2 and STAT6. Also, the TSLP deficiency attenuated mast cell–mediated allergic reactions through the downregulation of STAT6 and MDM2. In an antibody microarray chip analysis, MDM2 expression was increased in atopic dermatitis patients. These observations indicate that TSLP is a factor for mast cell development, and that it aggravates mast cell–mediated immune responses
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