840 research outputs found

    Air gap influence on the vibro-acoustic response of Solar Arrays during launch

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    One of the primary elements on the space missions is the electrical power subsystem, for which the critical component is the solar array. The behaviour of these elements during the ascent phase of the launch is critical for avoiding damages on the solar panels, which are the primary source of energy for the satellite in its final configuration. The vibro-acoustic response to the sound pressure depends on the solar array size, mass, stiffness and gap thickness. The stowed configuration of the solar array consists of a multiple system composed of structural elements and the air layers between panels. The effect of the air between panels on the behaviour of the system affects the frequency response of the system not only modifying the natural frequencies of the wings but also as interaction path between the wings of the array. The usual methods to analyze the vibro-acoustic response of structures are the FE and BE methods for the low frequency range and the SEA formulation for the high frequency range. The main issue in the latter method is, on one hand, selecting the appropriate subsystems, and, on the other, identifying the parameters of the energetic system: the internal and coupling loss factors. From the experimental point of view, the subsystems parameters can be identified by exciting each subsystem and measuring the energy of all the subsystems composing the Solar Array. Although theoretically possible, in practice it is difficult to apply loads on the air gaps. To analyse this situation, two different approaches can be studied depending on whether the air gaps between the panels are included explicitly in the problem or not. For a particular case of a solar array of three wings in stowed configuration both modelling philosophies are compared. This stowed configuration of a three wing solar arrays in stowed configuration has been tested in an acoustic chamber. The measured data on the solar wings allows, in general, determining the loss factors of the configuration. The paper presents a test description and measurements on the structure, in terms of the acceleration power spectral density. Finally, the performance of each modelling technique has been evaluated by comparison between simulations with experimental results on a spacecraft solar array and the influence on the apparent properties of the system in terms of the SEA loss factors has been analyse

    Dynamics of a structured slug population model in the absence of seasonal variation

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    We develop a novel, nonlinear structured population model for the slug Deroceras reticulatum, a highly significant agricultural pest of great economic impact, in both organic and non-organic settings. In the absence of seasonal variations, we numerically explore the effect of life history traits that are dependent on an individual's size and measures of population biomass. We conduct a systematic exploration of parameter space and highlight the main mechanisms and implications of model design. A major conclusion of this work is that strong size dependent predation significantly adjusts the competitive balance, leading to non-monotonic steady state solutions and slowly decaying transients consisting of distinct generational cycles. Furthermore, we demonstrate how a simple ratio of adult to juvenile biomass can act as a useful diagnostic to distinguish between predated and non-predated environments, and may be useful in agricultural settings

    Development of FEM/BEM and SEA models from experimental results for structural elements with attached equipment

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    This work focuses on the analysis of a structural element of MetOP-A satellite. Given the special interest in the influence of equipment installed on structural elements, the paper studies one of the lateral faces on which the Advanced SCATterometer (ASCAT) is installed. The work is oriented towards the modal characterization of the specimen, describing the experimental set-up and the application of results to the development of a Finite Element Method (FEM) model to study the vibro-acoustic response. For the high frequency range, characterized by a high modal density, a Statistical Energy Analysis (SEA) model is considered, and the FEM model is used when modal density is low. The methodology for developing the SEA model and a compound FEM and Boundary Element Method (BEM) model to provide continuity in the medium frequency range is presented, as well as the necessary updating, characterization and coupling between models required to achieve numerical models that match experimental results

    Description of nuclear systems within the relativistic Hartree-Fock method with zero range self-interactions of the scalar field

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    An exact method is suggested to treat the nonlinear self-interactions (NLSI) in the relativistic Hartree-Fock (RHF) approach for nuclear systems. We consider here the NLSI constructed from the relativistic scalar nucleon densities and including products of six and eight fermion fields. This type of NLSI corresponds to the zero range limit of the standard cubic and quartic self-interactions of the scalar field. The method to treat the NLSI uses the Fierz transformation, which enables one to express the exchange (Fock) components in terms of the direct (Hartree) ones. The method is applied to nuclear matter and finite nuclei. It is shown that, in the RHF formalism, the NLSI, which are explicitly isovector-independent, generate scalar, vector and tensor nucleon self-energies strongly density-dependent. This strong isovector structure of the self-energies is due to the exchange terms of the RHF method. Calculations are carried out with a parametrization containing five free parameters. The model allows a description of both types of systems compatible with experimental data.Comment: 23 pages, 14 figures (v2: major quantitative changes

    Active interventions in hypercholeteroloemia patiens with high cardiovascular risk in primary care

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    Introduction: Hypercholesterolemia is a major modifiable risk factors for cardiovascular disease (CVD). Its reduction reduces morbidity and mortality from ischemic heart disease and CVD in general, primary prevention and secondary prevention especially. Objective: To determine whether a notarized and intensive clinical practice can overcome inertia and achieve the therapeutic goal (OT) LDL-C &lt;100 mg &lt;dL in high-risk patients attended in Primary Care (PC) in our country. Methodology: epidemiological, prospective, multicenter study conducted in centers of different ACs By AP consecutive sampling 310 patients at high cardiovascular risk (diabetic or established CVD) previously treated with statins, which did not reach the OT included c-LDL. Results: The study subjects had a mean age of 65.2 years, of which 60.32% were male. The 41.64% had a previous EVC, acute myocardial infarction (20.33%), angina (16.07%), stroke /TIA (9.19%), arthropathy (5.25%), diabetes (70 , 87%), hypertension (71.01%), and abdominal obesity (69.62%). The 43.57% (95% CI: 37,21; 50,08) of patients who performed the 2nd visit (241) got the OT. 62.50% (95% CI: 55.68, 68.98) of those who took the 3rd (216) got the OT. Finally, 77.56% (95% CI: 72.13, 83.08) patients who performed the last visit (205) got the OT. Throughout the study there was a reduction in LDL-C levels from 135.6 mg /dL at baseline, 107.4 mg /dL in the 2nd visit, 97.3 mg /dL in the 3rd visit, up to 90.7 mg /dL at the final visit (p &lt;0.0001) The increase in HDL-C from baseline (50.9 mg /dL) and final (53.6 mg /dL) was also significant (p = 0.013). Conclusions: The reassessment and intensification of treatment in patients at high cardiovascular risk treated in primary care, applying the indications of the guides, achieves the OT in more than three quarters of the previously uncontrolled within half a year. These results should encourage us to overcome the therapeutic inertia in the control of CVD by early and energetic performance against hypercholesterolemia.Introducción: La hipercolesterolemia es uno de los principales factores de riesgo modificables de la enfermedad cardiovascular (ECV). Su reducción disminuye la morbimortalidad por cardiopatía isquémica y ECV en general, en prevención primaria y en prevención secundaria especialmente. Objetivo: Comprobar si una práctica clínica protocolizada e intensiva permite vencer la inercia y alcanzar el objetivo terapéutico (OT) de c-LDL < 100 mg/dL en pacientes de alto riesgo asistidos en Atención Primaria (AP) de nuestro país. Metodología: Estudio epidemiológico, prospectivo, multicentrico, realizado en Centros de AP de diferentes CC.AA. Mediante muestreo consecutivo se incluyeron 310 pacientes de alto riesgo cardiovascular (diabéticos o con ECV establecida), tratados previamente con estatinas, que no alcanzaban el OT de c-LDL. Resultados: Los sujetos del estudio tenían una edad media de 65,2 años, de los que el 60,32% eran varones. El 41,64% presentaba un EVC previo, infarto agudo de miocardio (20,33%), angina (16,07%), ictus/AIT (9,19%), artropatía (5,25%), diabetes (70,87%), hipertensión (71,01%), y obesidad abdominal (69,62%). El 43,57% (IC95%: 37,21; 50,08) de los pacientes que realizaron la 2a visita (241) consiguieron el OT. El 62,50% (IC95%: 55,68; 68,98) de los que realizaron la 3a (216) consiguieron el OT. Finalmente, el 77,56% (IC95%: 72,13; 83,08) de los pacientes que realizaron la última visita (205) consiguieron el OT. A lo largo del estudio hubo una reducción de los niveles de c-LDL desde los 135,6 mg/ dL en la visita basal, 107,4 mg/dL en la 2a visita, 97,3 mg/ dL en la 3a visita, hasta los 90,7 mg/dL en la visita final (p < 0,0001) El incremento de c-HDL entre la visita basal (50,9 mg/dL) y la final (53,6 mg/dL) también fue significativo (p = 0,013). Conclusiones: La reevaluación e intensificación del tratamiento en pacientes de alto riesgo cardiovascular atendidos en Atención Primaria, aplicando las indicaciones de las guías, permite alcanzar el OT en más de las tres cuartas partes de los previamente no controlados en el plazo de medio año. Estos resultados nos deben estimular a superar la inercia terapéutica en el control de la ECV mediante una actuación precoz y enérgica ante la hipercolesterolemi

    Traffic monitoring for assuring quality of advanced services in future internet

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    The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-21560-5_16Services based on packet switched networks are becoming dominant in telecommunication business and both operators and service providers must evolve in order to guarantee the required quality. Increasing bandwidth is no longer a viable solution because of the business erosion for network operators which cannot expect revenues due to the large investments required to satisfy new applications demand of bandwidth. This paper presents devices and a specific architecture of services monitoring platform that allows network operators and service providers to analyze the perceived quality of service and check their service level agreements. Thus, a cost-effective service management, based on direct IP traffic measuring, can be supported on integrated monitoring systems to provide network-centric mechanisms for differentiated quality of service, security and other advanced services.This work has been partially developed in the framework of the Celtic and EUREKA initiative IPNQSIS (IP Network Monitoring for Quality of Service Intelligent Support)

    Identificación del Virus Epstein-Barr por Hibridación in situ en pacientes con Cáncer Gástrico que asisten al Instituto de Cancerología (Incan) de Guatemala

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    El Virus Epstein Barr (EBV) está relacionado como agente oncogénico en el desarrollo del cáncer gástrico, atribuyéndosele el 10 % de los casos de esta neoplasia a nivel mundial. No existen estudios previos que identifiquen la presencia EBV en los pacientes con cáncer gástrico en Guatemala, por lo que en este estudio se evaluó por hibridación in situ la presencia del micro ARN EBER (Epstein Barr-encoded RNAs) de EBV en 71 pacientes con cáncer gástrico que asistieron al Instituto de Cancerología (Incan). Se determinó una prevalencia de 21.1 % (IC 95 % [10.9, 31.3] ) (15 pacientes), mayor que la reportada en otros estudios latinoamericanos. Se determinó asociación significativa entre la expresión del EBER del EBV, y el género masculino OR = 4.9 (IC 95% [1.4, 17.5]) p &lt; .05. Los factores asociados fueron, el padecer diarrea OR 5.7 IC 95 % [1.5, 12.6] p = .008, y la detección del anticuerpos de Helicobacter pylori séricos, OR 7.2 (IC 95 % [1.1, 18.9]) p = .03. Aun cuando la mayoría de los pacientes que expresan el EBER de EBV desarrollaron cáncer gástrico del tipo difuso 66.67 % noexiste asociación significativa p = 0.13 OR = 2.5 (IC 95 % [1.1, 8.2])

    Planck 2015 results. XXI. The integrated Sachs-Wolfe effect

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    Cosmology (including clusters of galaxies).-- et al.This paper presents a study of the integrated Sachs-Wolfe (ISW) effect from the Planck 2015 temperature and polarization data release. This secondary cosmic microwave background (CMB) anisotropy caused by the large-scale time-evolving gravitational potential is probed from different perspectives. The CMB is cross-correlated with different large-scale structure (LSS) tracers: radio sources from the NVSS catalogue; galaxies from the optical SDSS and the infrared WISE surveys; and the Planck 2015 convergence lensing map. The joint cross-correlation of the CMB with the tracers yields a detection at 4σ where most of the signal-to-noise is due to the Planck lensing and the NVSS radio catalogue. In fact, the ISW effect is detected from the Planck data only at ≈3σ (through the ISW-lensing bispectrum), which is similar to the detection level achieved by combining the cross-correlation signal coming from all the galaxy catalogues mentioned above. We study the ability of the ISW effect to place constraints on the dark-energy parameters; in particular, we show that ΩΛ is detected at more than 3σ. This cross-correlation analysis is performed only with the Planck temperature data, since the polarization scales available in the 2015 release do not permit significant improvement of the CMB-LSS cross-correlation detectability. Nevertheless, the Planck polarization data are used to study the anomalously large ISW signal previously reported through the aperture photometry on stacked CMB features at the locations of known superclusters and supervoids, which is in conflict with ΛCDM expectations. We find that the current Planck polarization data do not exclude that this signal could be caused by the ISW effect. In addition, the stacking of the Planck lensing map on the locations of superstructures exhibits a positive cross-correlation with these large-scale structures. Finally, we have improved our previous reconstruction of the ISW temperature fluctuations by combining the information encoded in all the previously mentioned LSS tracers. In particular, we construct a map of the ISW secondary anisotropies and the corresponding uncertainties map, obtained from simulations. We also explore the reconstruction of the ISW anisotropies caused by the large-scale structure traced by the 2MASS Photometric Redshift Survey (2MPZ) by directly inverting the density field into the gravitational potential field.The Planck Collaboration acknowledges the support of: ESA; CNES and CNRS/INSU-IN2P3-INP (France); ASI, CNR, and INAF (Italy); NASA and DoE (USA); STFC and UKSA (UK); CSIC, MINECO, JA, and RES (Spain); Tekes, AoF, and CSC (Finland); DLR and MPG (Germany); CSA (Canada); DTU Space (Denmark); SER/SSO (Switzerland); RCN (Norway); SFI (Ireland); FCT/MCTES (Portugal); ERC and PRACE (EU).Peer Reviewe

    Improvement in detecting cytomegalovirus drug resistance mutations in solid organ transplant recipients with suspected resistance using next generation sequencing

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    Objetives The aim of this study was to identify CMV drug resistance mutations (DRM) in solid organ transplant (SOT) recipients with suspected resistance comparing next-generation sequencing (NGS) with Sanger sequencing and assessing risk factors and the clinical impact of resistance. Methods Using Sanger sequencing as the reference method, we prospectively assessed the ability of NGS to detect CMV DRM in the UL97 and UL54 genes in a nationwide observational study from September 2013 to August 2016. Results Among 44 patients recruited, 14 DRM were detected by Sanger in 12 patients (27%) and 20 DRM were detected by NGS, in 16 (36%). NGS confirmed all the DRM detected by Sanger. The additional six mutations detected by NGS were present in <20% of the sequenced population, being located in the UL97 gene and conferring high-level resistance to ganciclovir. The presence of DRM by NGS was associated with lung transplantation (p = 0.050), the administration of prophylaxis (p = 0.039), a higher mean time between transplantation and suspicion of resistance (p = 0.038) and longer antiviral treatment duration before suspicion (p = 0.024). However, the latter was the only factor independently associated with the presence of DRM by NGS in the multivariate analysis (OR 2.24, 95% CI 1.03 to 4.87). Conclusions NGS showed a higher yield than Sanger sequencing for detecting CMV resistance mutations in SOT recipients. The presence of DRM detected by NGS was independently associated with longer antiviral treatment.Funding: M.A.M. was supported in part by: Agency for Health Technology Assessment and Research Supported by Ministerio de Economía y Competitividad, Instituto de Salud Carlos III (PS12/02131 and PI17/02150); Agència de Gestió d´Ajuts Universitaris I de Recerca, Generalitat de Catalunya, 2017 SGR 794; and Fundació Marató TV3 project code 201824
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