9,727 research outputs found

    Conformal Magnetic Composite RFID for Wearable RF and Bio-Monitoring Applications

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    ©2008 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or distribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.10.1109/TMTT.2008.2006810This paper introduces for the first time a novel flexible magnetic composite material for RF identification (RFID) and wearable RF antennas. First, one conformal RFID tag working at 480 MHz is designed and fabricated as a benchmarking prototype and the miniaturization concept is verified. Then, the impact of the material is thoroughly investigated using a hybrid method involving electromagnetic and statistical tools. Two separate statistical experiments are performed, one for the analysis of the impact of the relative permittivity and permeability of the proposed material and the other for the evaluation of the impact of the dielectric and magnetic loss on the antenna performance. Finally, the effect of the bending of the antenna is investigated, both on the S-parameters and on the radiation pattern. The successful implementation of the flexible magnetic composite material enables the significant miniaturization of RF passives and antennas in UHF frequency bands, especially when conformal modules that can be easily fine-tuned are required in critical biomedical and pharmaceutical applications

    Nitric Oxide Regulates Neurogenesis in the Hippocampus following Seizures

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    Hippocampal neurogenesis is changed by brain injury. When neuroinflammation accompanies injury, activation of resident microglial cells promotes the release of inflammatory cytokines and reactive oxygen/nitrogen species like nitric oxide (NO). In these conditions, NO promotes proliferation of neural stem cells (NSC) in the hippocampus. However, little is known about the role of NO in the survival and differentiation of newborn cells in the injured dentate gyrus. Here we investigated the role of NO following seizures in the regulation of proliferation, migration, differentiation, and survival of NSC in the hippocampus using the kainic acid (KA) induced seizuremouse model. We show that NO increased the proliferation of NSC and the number of neuroblasts following seizures but was detrimental to the survival of newborn neurons. NO was also required for the maintenance of long-term neuroinflammation. Taken together, our data show that NO positively contributes to the initial stages of neurogenesis following seizures but compromises survival of newborn neurons.Foundation for Science and Technology (FCT, Portugal); COMPETE; FEDER [PTDC/SAU-NEU/102612/2008, PTDC/NEU-OSD/0473/2012, PEst-C/SAU/LA0001/2013-2014, PEst-OE/EQB/LA0023/2013-2014]; FCT, Portugal [SFRH/BPD/78901/2011, SFRH/BD/77903/2011

    Lepton asymmetry effect on neutrino oscillations and primordial He-4

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    We analyze the effects of lepton asymmetry on neutrino oscillations and on cosmological nucleosynthesis with active-sterile oscillating neutrinos. It is shown that small lepton asymmetries, L < 0.01, whose direct kinetic effect on nucleosynthesis is negligible, still effect nucleosynthesis considerably through their influence on oscillating neutrinos. Two different cases of lepton asymmetry are discussed: an initially present and a dynamically generated in oscillations. Dynamically generated in resonant oscillations asymmetry at small mixing angles suppresses oscillations, hence, the nucleosynthesis bounds on neutrino mass differences at small mixings are relaxed. Initially present asymmetry may suppress or enhance oscillations. The enhancement is a result of interchanging resonances between neutrino and antineutrino ensembles due to resonance waves passing through the neutrino and antineutrino spectrum. Updated nucleosynthesis bounds on neutrino oscillation parameters accounting for lepton asymmetry are presented

    Large scale structure and baryogenesis

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    Cuenca Matanza-Riachuelo: una propuesta de gestión ambiental territorial como aporte para el incremento de la calidad del sistema

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    En Argentina, la Cuenca Matanza –Riachuelo (CMR) es un sistema naturalaltamente degradado. Fue considerado uno de los diez lugares más contaminados delmundo en 2013 (Blacksmith Institute y Green Cross, Suiza). Es objeto de estudios y dediversas intervenciones, las cuales no han podido conseguir una mejora sustancial en lacalidad ambiental del sistema. En este contexto, la gestión ambiental basada en la planificación territorial y, enespecial, aplicada en el periurbano de la cuenca, surge como un aporte concreto para la obtención de soluciones aplicables y realistas. Los principales objetivos de este trabajoson, por una parte, generar una propuesta de Plan de Gestión Ambiental (PGA) para el periurbano de la cuenca enfocado en la variable territorial. Por otra, plantear unazonificación ambiental donde se puedan observar los principales objetivos del PGA. Para la realización del PGA se tomaron como guía los requisitos solicitados por laNorma ISO 14001:2015. En base a un análisis de aspectos ambientales de la variable territorial, se establecieron objetivos para cada aspecto significativo, ya sea para mitigaraquellos que provocan impactos negativos, como para reforzar aquellos que generan impactos positivos. Se realizó una zonificación ambiental cuya principal contribución es orientar a losactores sociales quienes intervienen y toman decisión sobre sus actuaciones en la zona, buscando así un equilibrio hombre-naturaleza, de tal manera que se garantice para lasgeneraciones futuras la sostenibilidad en términos ambientales, socioeconómicos y culturales. Para realizar la propuesta de zonificación ambiental para el periurbano de laCMR se utilizó información espacialmente explícita a fin de localizar los principales objetivos del PGA con énfasis en la variable territorial: áreas verdes, buffer de cursos deagua, localización de canteras y fábricas de ladrillos, parques industriales, asentamientos informales, uso urbano. Estos mapas fueron generados mediante análisis GIS ydigitalización de información secundaria provista por ACUMAR

    A Validated Reversed-Phase HPLC Method for the Determination of Atorvastatin Calcium in Tablets

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    A Reversed-Phase Liquid Chromatographic (RP-LC) assay method was developed for the quantitative determination of atorvastatin calcium in the presence of its degradation products. The assay involved an isocratic elution of atorvastatin calcium in a LiChroCARTR 250*4 mm HPLC Cartridge LiChrospherR 100 RP-18 (5 μm) column using a mobile phase consisting of 0.1% acetic acid solution: acetonitrile (45:55, v/v), pH = 3.8. The flow rate was 0.8 mL/min and the analytes monitored at 246 nm. The assay method was found to be linear from 8.13 to 23.77 μg/mL. All the validation parameters were within the acceptance range. The developed method was successfully applied to estimate the amount of atorvastatin calcium in tablets.Fil: Simionato, Laura Daniela. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; ArgentinaFil: Ferello, L.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; ArgentinaFil: Stamer. S.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; ArgentinaFil: Repetto, M. F.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; ArgentinaFil: Zubata, P. D.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; ArgentinaFil: Segall, Adriana Ines. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Tecnología Farmacéutica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentin

    Structural and optical investigation of non-polar (1-100) GaN grown by the ammonothermal method

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    This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Journal of Applied Physics 113, 203513 (2013) and may be found at https://doi.org/10.1063/1.4807581.We studied the structural and optical properties of state-of-the-art non-polar bulk GaN grown by the ammonothermal method. The investigated samples have an extremely low dislocation density (DD) of less than 5 × 104 cm−2, which results in very narrow high-resolution x-ray rocking curves. The a and c lattice parameters of these stress-free GaN samples were precisely determined by using an x-ray diffraction technique based on the modified Bond method. The obtained values are compared to the lattice parameters of free-standing GaN from different methods and sources. The observed differences are discussed in terms of free-electron concentrations, point defects, and DD. Micro Raman spectroscopy revealed a very narrow phonon linewidth and negligible built-in strain in accordance with the high-resolution x-ray diffraction data. The optical transitions were investigated by cathodoluminescence measurements. The analysis of the experimental data clearly demonstrates the excellent crystalline perfection of ammonothermal GaN material and its potential for fabrication of non-polar substrates for homoepitaxial growth of GaN based device structures

    The Evolution of Dust Opacity in Galaxies

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    (Abridged) We investigate the evolution of the opacity of galaxies as a function of redshift, using simple assumptions about the metal and dust enrichment of the gas and the distribution of dust in galaxies. We use an iterative procedure to reconstruct the intrinsic Star Formation Rate (SFR) density of galaxies with redshift, by applying dust obscuration corrections to the observed UV emission. The iterative procedure converges to multiple solutions for the intrinsic SFR density, divided into two basic classes. The first class of solutions predicts relatively large UV attenuation at high redshift, with A(1500 A)=1.9 mag at z~3, and smaller attenuations at z<1, with A(2800 A)=1.25 mag. The SFR density of this set of solutions is constant for z>~1.2 and declines for z<1.2; it resembles in shape the ``monolithic collapse'' scenario for star formation. The second class of solutions predicts relatively low UV attenuations at high redshift, with A(1500 A)=0.75 mag at z~3, and larger attenuations at z<1, with A(2800 A)=1.50 mag. The SFR density in this case has a peak at z~1.2. The advantages and shortcomings of both classes are analyzed in the light of available observational constraints, including the opacity of galaxies at 0<z<1 and the intensity and spectral energy distribution of the cosmic infrared background from the COBE DIRBE and FIRAS data. We conclude that both classes of models are acceptable within the current uncertainties, but the ``monolithic collapse'' class matches the available observations better than the other one. We also investigate the dependence of our solutions on the different model assumptions.Comment: 54 pages, includes 1 embedded postscript Table and 22 embedded postscript Figures, Latex, uses AAS Latex macro. Accepted for publication in the Astrophysical Journa

    Young Clusters in the Nuclear Starburst of M 83

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    We present a photometric catalog of 45 massive star clusters in the nuclear starburst of M 83 (NGC 5236), observed with the Hubble Space Telescope WFPC2, in both broad-band (F300W, F547M, and F814W) and narrow-band (F656N and F487N) filters. By comparing the photometry to theoretical population synthesis models, we estimate the age and mass of each cluster. We find that over 75% of the star clusters more massive than 2*10^4 Msun in the central 300 pc of M 83 are less than 10 Myr old. Among the clusters younger than 10 Myr and more massive than 5*10^3 Msun, 70% are between 5 and 7 Myr old. We list an additional 330 clusters that are detected in our F300W images, but not in the shallower F547M and F814W images. The clusters are distributed throughout a semicircular annulus that identifies the active region in the galaxy core, between 50 and 130 pc from the optical center of M 83. Clusters younger than 5 Myr are preferentially found along the perimeter of the semicircular annulus. We suggest that the 5-7 Myr population has evacuated much of the interstellar material from the active ringlet region, and that star formation is continuing along the edges of the region.Comment: 40 pages, 13 figures, accepted to ApJ
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