1,224 research outputs found

    Losses for microwave transmission in metamaterials for producing left-handed materials: The strip wires

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    This paper shows that the effective dielectric permitivity for the metamaterials used so far to obtain left-handed materials, with strip wires 0.003cm thick, is dominated by the imaginary part at 10.6- 11.5 GHz frequencies, where the band pass filter is, and therefore there is not propagation and the wave is inhomogeneous inside the medium. This is shown from finite-differences time-domain calculations using the real permitivity values for the Cu wires. For thicker wires the losses are reduced and the negative part of the permitivity dominates. As the thickness of the wires is critical for the realization of a good transparent left- handed material we propose that the strip wires should have thickness of 0.07-0.1cm and the split ring resonators 0.015-0.03c

    Theory of Electromagnetic Wave Transmission through Metallic Gratings of Subwavelength Slits

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    We present FDTD calculations for transmission of light and other electromagnetic waves through periodic arrays of slits in a metallic slab. The results show resonant, frequency dependent, transmittance peaks for subwavelength widths of the slits which can be up to a factor of ten with respect to those out of resonance. Although our conclusions agree with previous work by Lezec and Thio as regards both the magnitude of the enhancement and the lack of contribution of surface plasmon polaritons of the metal surface to this effect, we derive an interpretation from a theory that deals with emerging beam- Rayleigh anomalies of the grating, and with Fabry-Perot resonances of the perforated slab considered as an effective medium.Comment: 12 pages 3 figure

    Transcriptome profiling of Set5 and Set1 methyltransferases: Tools for visualization of gene expression

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    AbstractCells regulate transcription by coordinating the activities of multiple histone modifying complexes. We recently identified the yeast histone H4 methyltransferase Set5 and discovered functional overlap with the histone H3 methyltransferase Set1 in gene expression. Specifically, using next-generation RNA sequencing (RNA-Seq), we found that Set5 and Set1 function synergistically to regulate specific transcriptional programs at subtelomeres and transposable elements. Here we provide a comprehensive description of the methodology and analysis tools corresponding to the data deposited in NCBI's Gene Expression Omnibus (GEO) under the accession number GSE52086. This data complements the experimental methods described in Mas Martín G et al. (2014) and provides the means to explore the cooperative functions of histone H3 and H4 methyltransferases in the regulation of transcription. Furthermore, a fully annotated R code is included to enable researchers to use the following computational tools: comparison of significant differential expression (SDE) profiles; gene ontology enrichment of SDE; and enrichment of SDE relative to chromosomal features, such as centromeres, telomeres, and transposable elements. Overall, we present a bioinformatics platform that can be generally implemented for similar analyses with different datasets and in different organisms

    Specific gene correction of the AGXT gene and direct cell reprogramming for the treatment of Primary Hyperoxaluria Type 1

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    P428 Primary Hyperoxaluria Type 1 (PH1) is an inherited rare metabolic liver disease caused by the deficiency in the alanine: glyoxylate aminotransferase enzyme (AGXT), involved in the glyoxylate metabolism. The only potentially curative treatment is organ transplantation. Thus, the development of new therapeutic approaches for the treatment of these patients appears as a priority.We propose the combination of site-specific gene correction and direct cell reprogramming for the generation of autologous phenotypically healthy induced hepatocytes (iHeps) from skin-derived fibroblast of PH1 patients. For the correction of AGXT mutations, we have designed specific gene editing tools to address gene correction by two different strategies, assisted by CRISPR/Cas9 system. Accurate specific point mutation correction (c.853T-C) has been achieved by homologydirected repair (HDR) with ssODN harbouring wild-type sequence. In the second strategy, an enhanced version ofAGXTcDNAhas been inserted near the transcription start codon of the endogenous gene, constituting an almost universal correction strategy for PH1 mutations. Direct reprogramming of fibroblasts has been conducted by overexpression of hepatic transcription factors and in vitro culture in defined media. In vitro characterization of healthy induced hepatocytes (iHeps) has demonstrated hepatic function of the reprogrammed cells. PH1 patient fibroblasts and , ,

    Dynamics of Weyl Scale Invariant non-BPS p=3 Branes

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    In this paper a Weyl scale invariant p=3p=3 brane scenario is introduced, with the brane embedded in a higher dimensional bulk space with N=1,5DN=1, 5D Super--Weyl symmetry. Its action, which describes its long wave oscillation modes into the ambient superspace and breaks the target symmetry down to the lower dimensional Weyl W(1,3) symmetry, is constructed by the approach of coset method.Comment: 12 pages, modified versio

    Iso-spectral potential and inflationary quantum cosmology

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    Using the factorization approach of quantum mechanics, we obtain a family of isospectral scalar potentials for power law inflationary cosmology. The construction is based on a scattering Wheeler-DeWitt solution. These iso-spectrals have new features, they give a mechanism to end inflation, as well as the possibility to have new inflationary epochs. The procedure can be extended to other cosmological models.Comment: 14 pages, 5 figure

    Building Conventional Metasurfaces with Unconventional Interband Plasmonics: A Versatile Route for Sustainable Structural Color Generation Based on Bismuth

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    This is the final version. Available on open access from Wiley via the DOI in this recordData Availability Statement: The data that support the findings of this study are available in the supplementary material of this article.Plasmonic metasurfaces for structural color generation are typically built using the archetypal noble metals, gold, and silver. These possess plasmonic properties in the visible spectrum due to their inherent high free carrier densities. However, they are much more expensive compared to many other metals and exhibit several nanofabrication issues such as bad surface adhesion or thermally activated inter-diffusion. In this work, it is shown that interband plasmonic materials –whose optical properties are driven by interband transitions instead of free carriers— are appealing candidates for the fabrication of sustainable and cost-efficient metasurfaces for structural coloring. By using bismuth, an environment-friendly interband plasmonic material cheaper than gold and silver, nanodisks gap-plasmon metasurfaces and planar Fabry-Perot cavities are modeled and fabricated, which both successfully enable pure colors that can be robustly tailored upon suitable design. By direct experimental comparison between both types of design in terms of color efficiency, fabrication complexity, and angular robustness; how bismuth-based gap surface plasmon metasurfaces can be excellent candidates for color microprinting is shown, whereas nanolayered Bi Fabry-Pérot cavities are ideal for macroscopic color coatings due to their ease of fabrication and implementation.European CommissionAgencia Estatal de InvestigaciónMinisterio de Ciencia e Innovació

    XMM-Newton and Chandra observations of three X-ray faint early-type galaxies

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    We present XMM-Newton observations of three X-ray under-luminous elliptical galaxies, NGC 3585, NGC 4494 and NGC 5322. All three galaxies have relatively large optical luminosities (log LB=10.35-10.67 solar) but have X-ray luminosities consistent with emission from discrete sources only. In conjunction with a Chandra observation of NGC 3585, we analyse the XMM data and show that the three galaxies are dominated by discrete source emission, but do possess some X-ray emitting gas. The gas is at relatively low temperatures, kT=0.25-0.44 keV. All three galaxies show evidence of recent dynamical disturbance and formation through mergers, including kinematically distinct cores, young stellar ages, and embedded stellar disks. This leads us to conclude that the galaxies formed relatively recently and have yet to build up large X-ray halos. They are likely to be in a developmental phase where the X-ray gas has a very low density, making it undetectable outside the galaxy core. However, if the gas is a product of stellar mass loss, as seems most probable, we would expect to observe supersolar metal abundances. While abundance is not well constrained by the data, we find best fit abundances <0.1 solar for single-temperature models, and it seems unlikely that we could underestimate the metallicity by such a large factor.Comment: Accepted for publication in MNRAS, 12 pages, 8 postscript figure
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