50 research outputs found
Efficient Synthesis of Passively Loaded Finite Arrays for Tunable Anomalous Reflection
A design methodology for planar loaded antenna arrays is proposed to
synthesize a perfect anomalous reflection into an arbitrary direction by
optimizing the scattering characteristics of passively loaded array antennas.
It is based on efficient and accurate prediction of the induced current
distribution and the associated scattering for any given set of load
impedances. For a fixed array of finite dimensions, the deflection angles can
be continuously adjusted with proper tuning of each load. We study and develop
anomalous reflectors as semi-finite (finite infinite) and finite
planar rectangular arrays comprising printed patches with a subwavelength
spacing. Anomalous reflection into an arbitrary desired angle using purely
reactive loads is numerically and experimentally validated. Owing to the
algebraic nature of load optimization, the design methodology may be applied to
the synthesis of large-scale reflectors of practical significance.Comment: 10 pages, 10 figure
Analysis of a wild mouse promoter variant reveals a novel role for FcÎłRIIb in the control of the germinal center and autoimmunity.
Genetic variants of the inhibitory Fc receptor FcÎłRIIb have been associated with systemic lupus erythematosus in humans and mice. The mechanism by which Fcgr2b variants contribute to the development of autoimmunity is unknown and was investigated by knocking in the most commonly conserved wild mouse Fcgr2b promoter haplotype, also associated with autoimmune-prone mouse strains, into the C57BL/6 background. We found that in the absence of an AP-1-binding site in its promoter, FcÎłRIIb failed to be up-regulated on activated and germinal center (GC) B cells. This resulted in enhanced GC responses, increased affinity maturation, and autoantibody production. Accordingly, in the absence of FcÎłRIIb activation-induced up-regulation, mice developed more severe collagen-induced arthritis and spontaneous glomerular immune complex deposition. Our data highlight how natural variation in Fcgr2b drives the development of autoimmune disease. They also show how the study of such variants using a knockin approach can provide insight into immune mechanisms not possible using conventional genetic manipulation, in this case demonstrating an unexpected critical role for the activation-induced up-regulation of FcÎłRIIb in controlling affinity maturation, autoantibody production, and autoimmunity
An efficient chaotic salp swarm optimization approach based on ensemble algorithm for class imbalance problems
Class imbalance problems have attracted the research community, but a few works have focused on feature selection with imbalanced datasets. To handle class imbalance problems, we developed a novel fitness function for feature selection using the chaotic salp swarm optimization algorithm, an efficient meta-heuristic optimization algorithm that has been successfully used in a wide range of optimization problems. This paper proposes an AdaBoost algorithm with chaotic salp swarm optimization. The most discriminating features are selected using salp swarm optimization, and AdaBoost classifiers are thereafter trained on the features selected. Experiments show the ability of the proposed technique to find the optimal features with performance maximization of AdaBoost
Modeling RIS from Electromagnetic Principles to Communication Systems--Part I: Synthesis and Characterization of a Scalable Anomalous Reflector
This work aims to build connections between the electromagnetic and
communication aspects of Reconfigurable Intelligent Surfaces (RIS) by proposing
a methodology to combine outputs from electromagnetic RIS design into an
RIS-tailored system-level simulator and a ray tracer. In this first part of the
contribution, a periodic anomalous reflector is designed using an algebraic
array antenna scattering synthesis technique that enables electromagnetically
accurate modeling of scattering surfaces with both static and reconfigurable
scattering characteristics. The multi-mode periodic structure, capable of
scattering into several anomalous angles through manipulation of reactive
loads, is then cropped into finite-sized arrays, and the quantization effects
of the load reactances on the array scattering are analyzed. An experimental
anomalous reflector is demonstrated with a comparison between simulated and
measured scattering performance. In the second part, the simulated receiving
and transmitting scattering patterns of the anomalous reflector are utilized to
build an electromagnetically consistent path loss model of an RIS into a
system-level simulator. Large-scale fading is analyzed in simple scenarios of
RIS-assisted wireless networks to verify the communication model, and an indoor
scenario measurement using the manufactured anomalous reflector sample to
support the simulation analysis. After verifying the connections between
electromagnetic and communication aspects through simulations and measurements,
the proposed communication model can be used for a broad range of RIS designs
to perform large-scale system-level and ray-tracing simulations in realistic
scenarios.Comment: 10 pages, 7 figure
CTR1 Silencing Inhibits Angiogenesis by Limiting Copper Entry into Endothelial Cells
<div><p>Increased levels of intracellular copper stimulate angiogenesis in human umbilical vein endothelial cells (HUVECs). Copper transporter 1 (CTR1) is a copper importer present in the cell membrane and plays a major role in copper transport. In this study, three siRNAs targeting CTR1 mRNA were designed and screened for gene silencing. HUVECs when exposed to 100 ”M copper showed 3 fold increased proliferation, migration by 1.8 - fold and tube formation by 1.8 - fold. One of the designed CTR1 siRNA (si 1) at 10 nM concentration decreased proliferation by 2.5 - fold, migration by 4 - fold and tube formation by 2.8 - fold. Rabbit corneal packet assay also showed considerable decrease in matrigel induced blood vessel formation by si 1 when compared to untreated control. The designed si 1 when topically applied inhibited angiogenesis. This can be further developed for therapeutic application.</p></div
List of antisense siRNAs used in the study.
<p>List of antisense siRNAs used in the study.</p