Pressure measurements on real high-speed trains travelling through tunnels

From November, 2006 to March, 2008 a series of tests were performed onboard a wide variety of trains in order to check their response to pressure waves generated while passing through tunnels. In this communication part of the experimental results are presented, showing the pressure waves generated and focusing on the differences caused by some parameters involved such as train length and shape or tunnel lengths. The results are in accordance with the train wave signature method and the one-dimensional pressure wave theory

Polarimetry enabled by nanophotonics

Martínez Abietar, AJ. (2018). Polarimetry enabled by nanophotonics. Science. 362(6416):750-751. https://doi.org/10.1126/science.aau7494S7507513626416Azzam, R. M. A. (2016). Stokes-vector and Mueller-matrix polarimetry [Invited]. Journal of the Optical Society of America A, 33(7), 1396. doi:10.1364/josaa.33.001396Westbrook, P. S., Strasser, T. A., & Erdogan, T. (2000). In-line polarimeter using blazed fiber gratings. IEEE Photonics Technology Letters, 12(10), 1352-1354. doi:10.1109/68.883827Koenderink, A. F., Alu, A., & Polman, A. (2015). Nanophotonics: Shrinking light-based technology. Science, 348(6234), 516-521. doi:10.1126/science.1261243Pors, A., Nielsen, M. G., & Bozhevolnyi, S. I. (2015). Plasmonic metagratings for simultaneous determination of Stokes parameters. Optica, 2(8), 716. doi:10.1364/optica.2.000716Balthasar Mueller, J. P., Leosson, K., & Capasso, F. (2016). Ultracompact metasurface in-line polarimeter. Optica, 3(1), 42. doi:10.1364/optica.3.000042Maguid, E., Yulevich, I., Veksler, D., Kleiner, V., Brongersma, M. L., & Hasman, E. (2016). Photonic spin-controlled multifunctional shared-aperture antenna array. Science, 352(6290), 1202-1206. doi:10.1126/science.aaf3417Wu, P. C., Chen, J.-W., Yin, C.-W., Lai, Y.-C., Chung, T. L., Liao, C. Y., … Tsai, D. P. (2017). Visible Metasurfaces for On-Chip Polarimetry. ACS Photonics, 5(7), 2568-2573. doi:10.1021/acsphotonics.7b01527Rubin, N. A., Zaidi, A., Juhl, M., Li, R. P., Mueller, J. P. B., Devlin, R. C., … Capasso, F. (2018). Polarization state generation and measurement with a single metasurface. Optics Express, 26(17), 21455. doi:10.1364/oe.26.021455Afshinmanesh, F., White, J. S., Cai, W., & Brongersma, M. L. (2012). Measurement of the polarization state of light using an integrated plasmonic polarimeter. Nanophotonics, 1(2). doi:10.1515/nanoph-2012-0004Bauer, T., Banzer, P., Karimi, E., Orlov, S., Rubano, A., Marrucci, L., … Leuchs, G. (2015). Observation of optical polarization Möbius strips. Science, 347(6225), 964-966. doi:10.1126/science.1260635Bliokh, K. Y., Rodríguez-Fortuño, F. J., Nori, F., & Zayats, A. V. (2015). Spin–orbit interactions of light. Nature Photonics, 9(12), 796-808. doi:10.1038/nphoton.2015.201Espinosa-Soria, A., Rodríguez-Fortuño, F. J., Griol, A., & Martínez, A. (2017). On-Chip Optimal Stokes Nanopolarimetry Based on Spin–Orbit Interaction of Light. Nano Letters, 17(5), 3139-3144. doi:10.1021/acs.nanolett.7b00564Bauer, T., Orlov, S., Peschel, U., Banzer, P., & Leuchs, G. (2013). Nanointerferometric amplitude and phase reconstruction of tightly focused vector beams. Nature Photonics, 8(1), 23-27. doi:10.1038/nphoton.2013.289Kuznetsov, A. I., Miroshnichenko, A. E., Brongersma, M. L., Kivshar, Y. S., & Luk’yanchuk, B. (2016). Optically resonant dielectric nanostructures. Science, 354(6314), aag2472. doi:10.1126/science.aag247

A Real Approximation to Riemann Hypothesis

This work present the requisites to define $\zeta(s)$ like an analytic function on real numbers; as well as a numerical evaluation made computationally to obtain criteria of convergence. By the other hand its discusses some algebraic identities to establish where the function zeta Riemann gives place to $\zeta(s)´ = 0$

Conocimientos Actitudes y Practicas sobre la Técnica de Papanicolaou en Mujeres de Edad Fértil con vida sexual activa, que asisten al Centro de Salud Edwin Barahona Colindres del Municipio de Murra, Departamento de Nueva Segovia en el Periodo Octubre-Diciembre del 2016

El cáncer cervical (CaCu), es la segunda neoplasia que más muertes ocasiona entre la población femenina. Se estiman 500.000 casos anuales en el mundo, de los cuales el 80% de ellos corresponden a países en vías de desarrollo En el país se encuentra establecido como la primera causa de morbimortalidad que afecta a las mujeres Nicaragüenses, y se encuentra relacionado a Condiciones Socio Económicas de pobreza, condicionado por factores socio culturales que afectan directamente el manejo y seguimiento de esta patología de forma muy importante. Esto provoca que en la atención primaria exista todavía una baja cobertura, con limitaciones en el diagnóstico precoz, que desarrolla una afectación en la calidad de la atención y seguimiento al grupo de pacientes afectadas, y cuyas condiciones son similares a los reportados en diversos países de América Latina. Se debe impulsar en nuestra población el conocimiento sobre la técnica de Papanicolaou, para que mejore en principio el mal manejo de la información, superando además la influencia de los mitos, tabúes y las complicaciones que esto conlleva. Se realizó un estudio en una muestra de 229 mujeres en edad fértil, con vida sexual activa, para valorar los conocimientos, actitudes y prácticas sobre el Papanicolaou y que asisten al Centro de Salud Edwin Barahona Colindres del Municipio de Murra, Departamento de Nueva Segovia en el Periodo Octubre - Diciembre del 2016. .De las 229 mujeres entrevistadas el 57.2% correspondió al grupo de 15 a 26 años, y el 28.4% al grupo de edad de 27 a 38 años. Según el estado civil predominaron las mujeres acompañadas con un 41.9%, seguidas de las solteras con un 31.0%. En cuanto a la religión, las mujeres en estudio un 56.3% profesaban la religión católica y un 34.1% la evangélica, 9.6% pertenecían a otras entidades religiosas. Las mujeres tuvieron una procedencia rural, en el 71.2% de los casos y procedencia urbana en el 28.8%. En la escolaridad encontramos que el 20.9% de los casos eran Analfabetas, 35.5% cursaban Primaria, 26.6% cursaban la secundaria el 33.8%, el 7.0% tenían un nivel técnico y un 10.0% se encontraban en la universidad. De manera general encontramos que el nivel de conocimientos fue bueno en el 67.7%, prevaleció en un 24.4% el nivel de conocimiento regular, y en el 7.9% tuvieron un nivel de conocimiento malo. Los resultados obtenidos nos orientan a indicar la importancia de impulsar Medidas y Programas con intervenciones objetivas a fin de impulsar más el papel que se está desempeñando en materia preventiva para que las mujeres adopten actitudes y prácticas más responsables y seguras en relación al conocimiento sobre la toma de Papanicolaou y el Cáncer del Cérvix Uterino, manteniendo un constante monitoreo durante la toma de decisiones. El personal de salud, así como las Unidades de Salud, juegan un rol importante ya que es en primera instancia en este sitio y con estos actores donde las mujeres destacaron como principal fuente de información acerca del tema de Papanicolaou. Es necesario que la población en general, líderes comunitarios, padres de familia y mujeres tomen conciencia de la magnitud que representa la prevalencia del Cáncer Cervico Uterino en nuestro país, y que representa además un verdadero problema de salud pública en Nicaragua, ya que nos afecta a todos, repercutiendo en la calidad de vida, las oportunidades de desarrollo económico que se ven reflejados desde el mismo núcleo familiar

Analysis of power converters with devices of SiC for applications in electric traction systems

This article presents the analysis of two topologies of power converters. Voltage Source Inverter (VSI) and Current Source Inverter (CSI) proposals for traction system applications, these topologies are implemented with silicon carbide devices. The use of SiC semiconductors allow working at high switching frequency (100KHz), increase the working temperature range and decreasing power losses during conduction and activation of the semiconductors. The objective is analyze these topologies and select the one that provides the best performance and behavior at high frequency to improve it on a electric traction system.Postprint (author's final draft

Theoretical study about the gain in indirect bandgap semiconductor optical cavities

[EN] Indirect bandgap semiconductors such as silicon are not efficient light emitters because a phonon with a high momentum is required to transfer an electron from the conduction to the valence band. In a recent study (M.J. Chen et al., 2006) [6] an analytical expression of the optical gain in bulk indirect bandgap semiconductors was obtained. The main conclusion was that the free-carrier absorption was much higher than the optical gain at ambient temperature, which prevents lasing. In this work, we consider the case in which the semiconductor material is engineered to form an optical cavity characterized by a certain Purcell factor. We conclude that although the optical gain is increased, losses due to free carriers increase in the same way so lasing is also prevented even when creating a high-Q optical cavity. © 2012 Elsevier B.V. All rights reserved.This research has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement number 233883 (TAILPHOX). The authors wish to thank M.J. Chen for his useful comments.Escalante Fernández, JM.; Martínez Abietar, AJ. (2012). Theoretical study about the gain in indirect bandgap semiconductor optical cavities. Physica B: Condensed Matter. 407(12):2044-2049. https://doi.org/10.1016/j.physb.2012.02.002204420494071

Plant Growth Promotion and Biocontrol of Pythium ultimum by Saline Tolerant Trichoderma Isolates under Salinity Stress

This present study evaluates three isolates of Trichoderma as plant growth promoting or biological control agents: Trichoderma aggressivum f. sp. europaeum, Trichoderma saturnisporum, and the marine isolate obtained from Posidonia oceanica, Trichoderma longibrachiatum. The purpose is to contribute to an overall reduction in pesticide residues in the fruit and the environment and to a decrease in chemical fertilizers, the excess of which aggravates one of the most serious abiotic stresses, salinity. The tolerance of the different isolates to increasing concentrations of sodium chloride was evaluated in vitro, as well as their antagonistic capacity against Pythium ultimum. The plant growth promoting capacity and effects of Trichoderma strains on the severity of P. ultimum on melon seedlings under saline conditions were also analysed. The results reveal that the three isolates of Trichoderma, regardless of their origin, alleviate the stress produced by salinity, resulting in larger plants with an air-dry weight percentage above 80% in saline stress conditions for T. longibrachiatum, or an increase in root-dry weight close to 50% when T. aggressivum f. sp. europaeum was applied. Likewise, the three isolates showed antagonistic activity against P. ultimum, reducing the incidence of the disease, with the highest response found for T. longibrachiatum. Biological control of P. ultimum by T. aggressivum f. sp. europaeum and T. saturnisporum is reported for the first time, reducing disease severity by 62.96% and 51.85%, respectively. This is the first description of T. aggressivum f. sp. europaeum as a biological control agent and growth promoter. The application of these isolates can be of enormous benefit to horticultural crops, in both seedbeds and greenhouses

Transverse Spin and Spin-Orbit Coupling in Silicon Waveguides

Evanescent and tightly confined propagating waves exhibit a remarkable transverse spin density since the longitudinal component of the electric field is not negligible. In this work, we obtain via numerical simulations the electric field components of the fundamental guided modes of two waveguides typically used in silicon photonics: the strip and the slot waveguide. We obtain the relation between transverse and longitudinal field components, the transverse spin densities and other important parameters, such as the longitudinal component of the so-called Belinfante s spin momentum density. By asymmetrically placing a circularly-polarized point-like dipole source in regions showing local circular polarization, the guided mode is excited unidirectionally via spin-orbit coupling. In contrast to metal plates supporting surface plasmons, the multimode behavior of silicon waveguides results in different spin-orbit coupling properties for each guided mode. Our results may find application in silicon photonic devices, integrated quantum optics and polarization manipulation at the nanoscale.This work was supported in part by the Secretaria de Estado de Investigacion, Desarrollo e Innovacion under Grant TEC2014-51902-C2-1-R and in part by the Valencian Conselleria d'Educacio, Cultura i Esport under Grant PROMETEOII/2014/034.Espinosa Soria, A.; Martínez Abietar, AJ. (2016). Transverse Spin and Spin-Orbit Coupling in Silicon Waveguides. IEEE Photonics Technology Letters. 28(14):1561-1564. https://doi.org/10.1109/LPT.2016.2553841S15611564281

DCOPF Contingency Analysis Including Phase Shifting Transformers

This work deals with a new formulation for the Direct Current Optimal Power Flow (DCOPF) including the corrective actions related to the phase shifting transformers. The formulation is based on the outage of generators and/or branches modelled as fictitious injections of active power. The inclusion of the sensitivities of the phase shifting transformer with respect to the injected powers is one of the novelties of this paper. By including the fictitious injections in the optimization problem, the injections are adjusted to the post-contingency state as a consequence of the corrective actions carried out by the DCOPF to bring the system back to its normal state. Consequently, when the analysis of contingencies is performed, the classical topological analysis and the subsequent analyses are avoided with this approach. The DCOPF includes as corrective control variables the rescheduling of active power generations, phase shifting transformers and, if required, permitted load shedding. The IEEE-RTS of 24 buses is used as benchmark network to assess the properties of the proposed approach.Spanish Ministry of Science and Innovation and Cooperation (Spain) ENE2011-24137Spanish Ministry of Science and Innovation and Cooperation (Spain) ENE2011-27984Junta de Andalucía PO11-TEP741