1,065 research outputs found

    Ka-Band Diplexer for 5G mmWave Applications in Inverted Microstrip Gap Waveguide Technology

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    This article belongs to the Special Issue Millimeter and Terahertz Wireless CommunicationsA new cost-efficient, low-loss Ka-band diplexer designed in inverted microstrip gap waveguide technology is presented in this paper. Gap waveguide allows to propagate quasi-TEM modes in the air between two metal plates without the need for contact between them by using periodic metasurfaces. The diplexer is realized by using a bed of nails as AMC (Artificial Magnetic Conductor), first modeled with a PMC (Perfect Magnetic Conductor) surface for design simplification, and two fifth order end-coupled passband filters (BPFs) along with a power divider. The experimental verification confirms that the two channels centered at 24 GHz and 28 GHz with 1 GHz of bandwidth show measured insertion losses of 1.5 dB and 2 dB and 60 dB of isolation between them. A slight shift in frequency is observed in the measurements that can be easily explained by the variation in the permittivity of the substrate.This research was funded by the Spanish Ministerio de Ciencia, Innovación y Universidades grant numbers [PID2019-107688RB-C21, TEC2016-79700-C2-R and TEC2017-86619-R]

    Analysis of Periodic Structures Made of Pins Inside a Parallel Plate Waveguide

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    Special Issue: Higher Symmetries and Its Application in Microwave Technology, Antennas and MetamaterialsIn this work, we have analyzed different versions of periodic structures made with metallic pins located inside a parallel plate waveguide (PPWG), varying the symmetry and disposition of the pins. The analysis focuses on two main parameters related to wave propagation. On one hand, we have studied how the different proposed structures can create a stopband so that the parallel plate modes can be used in gap waveguide technology or filtering structures. On the other hand, we have analyzed the dispersion and equivalent refractive index of the first propagating transverse electromagnetic mode (TEM). The results show how the use of complex structures made with pins in the top and bottom plates of a PPWG have no advantages in terms of the achieved stopband size. However, for the case of the propagating mode, it is possible to find less dispersive modes and a higher range of equivalent refractive indices when using double-pin structures compared to a reference case with single pins.This research was funded by the Spanish Ministerio de Ciencia, Innovación y Universidades grant number [TEC2016-79700-C2-2-R], Becas Santander Jóvenes Investigadores and FONDECYT 11180434

    Considerations of impedance sensitivity and losses in designing inverted microstrip gap waveguides

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    One of the versions of gap waveguide technology, the inverted microstrip, is studied in terms of the effects that the parameters of the substrate and the bed of nails used for its implementation have in the behaviour as a transmission line. Mainly, the line impedance sensitivity and the losses are evaluated for different design parameters. To this aim, a methodology based on simulations is described and some experimental verifications are as well included. The results are of great interest for designers of antennas and components in this technology

    Mortality of Spanish soccer referees and coaches: a retrospective cohort study

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    There is evidence that elite soccer players live longer than general population, but there is no information on soccer coaches and referees. We aimed to analyze the longevity of both professionals, comparing them with soccer players and with general population. In this retrospective cohort study, a total of 328 male Spanish soccer coaches, 287 referees, and 1230 soccer players, all born before 1950, were divided in two cohorts, matched 2:1 with coaches and referees. We compared the survival of the cohorts with the Kaplan–Meier estimator and significance with the log-rank test. We calculated hazard ratios of death for coaches and referees compared with male Spanish general population of the same period. Differences in survival among cohorts were found, but they did not reach statistical significance. The estimated median survival time was 80.1 years (95% CI 77.7–82.4) for referees, 78 years (95% CI 76.6–79.3) for coaches, 78.8 years (95% CI 77.6–80) for referees matched with players, and 76.6 years (95% CI 75.3–77.9) for coaches matched with players. Both coaches and referees had lower mortality than general population, but this advantage disappeared after 80 years of age. We found no differences in longevity among Spanish elite soccer referees, coaches and players born before 1950. Both coaches and referees had lower mortality than general population, but this advantage disappeared after 80 years of age

    Excessive age-related decline in functional ovarian reserve in infertile women: prospective cohort of 15,500 women

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    Context: Whether infertile women exhibit accelerated ovarian aging and whether a low ovarian reserve is overrepresented in infertility populations is not known. Objective: To compare the age-related decline in antral follicle count (AFC), a biomarker of the ovarian reserve, in fertile and infertile women. Design: Cross-sectional data from a large prospective cohort study conducted from January 2013 to December 2014. Setting: Thirteen fertility centers across Spain. Patients or Other Participants: Consecutive women aged 18 to 45 years of age attending the fertility centers either seeking fertility treatment or as fertile women wishing to act as potential oocyte donors. Intervention(s): Standardized AFC assessment on day 2 to 4 of the cycle. Main Outcome Measure(s): Age-related decline of AFC for both fertile and infertile women. Results: A total of 15 500 women, of whom 5722 were potential donors and 9778 were patients seeking fertility treatment, participated in the study. Average AFC was greater in potential oocyte donors than in infertile women (20 [interquartile range, 16–24] vs 10 [interquartile range, 6–15], respectively; P < .001), a difference that was maintained after adjustment for age (P < .001) in a model predicting log(AFC) from donor vs infertility, adjusting for 2-year age bands. The age-related decline in AFC was much steeper in infertile women compared with that of potential oocyte donors, with an increased prevalence of a low ovarian reserve (AFC < 5) at all ages in infertile women. Conclusions: The age-related decline in AFC was substantially greater in infertility patients than potential oocyte donors. Overrepresentation in infertility populations of women with low ovarian reserve may be an additional functional cause of infertility

    X-boson cumulant approach to the periodic Anderson model

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    The Periodic Anderson Model (PAM) can be studied in the infinite U limit by employing the Hubbard X operators to project out the unwanted states. We have already studied this problem employing the cumulant expansion with the hybridization as perturbation, but the probability conservation of the local states (completeness) is not usually satisfied when partial expansions like the Chain Approximation (CHA) are employed. Here we treat the problem by a technique inspired in the mean field approximation of Coleman's slave-bosons method, and we obtain a description that avoids the unwanted phase transition that appears in the mean-field slave-boson method both when the chemical potential is greater than the localized level Ef at low temperatures (T) and for all parameters at intermediate T.Comment: Submited to Physical Review B 14 pages, 17 eps figures inserted in the tex

    Parenteral Nutrition: Current Use, Complications, and Nutrition Delivery in Critically Ill Patients

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    Background: Parenteral nutrition (PN) is needed to avoid the development of malnutrition when enteral nutrition (EN) is not possible. Our main aim was to assess the current use, complications, and nutrition delivery associated with PN administration in adult critically ill patients, especially when used early and as the initial route. We also assessed the differences between patients who received only PN and those in whom EN was initiated after PN (PN-EN). Methods: A multicenter (n = 37) prospective observational study was performed. Patient clinical characteristics, outcomes, and nutrition-related variables were recorded. Statistical differences between subgroups were analyzed accordingly. Results: From the entire population (n = 629), 186 (29.6%) patients received PN as initial nutrition therapy. Of these, 74 patients (11.7%) also received EN during their ICU stay (i.e., PNEN subgroup). PN was administered early (<48 h) in the majority of patients (75.3%; n = 140) and the mean caloric (19.94 +/- 6.72 Kcal/kg/day) and protein (1.01 +/- 0.41 g/kg/day) delivery was similar to other contemporary studies. PN showed similar nutritional delivery when compared with the enteral route. No significant complications were associated with the use of PN. Thirty-two patients (43.3%) presented with EN-related complications in the PN-EN subgroup but received a higher mean protein delivery (0.95 +/- 0.43 vs 1.17 +/- 0.36 g/kg/day; p = 0.03) compared with PN alone. Once adjusted for confounding factors, patients who received PN alone had a lower mean protein intake (hazard ratio (HR): 0.29; 95% confidence interval (CI): 0.18-0.47; p = 0.001), shorter ICU stay (HR: 0.96; 95% CI: 0.91-0.99; p = 0.008), and fewer days on mechanical ventilation (HR: 0.85; 95% CI: 0.81-0.89; p = 0.001) compared with the PN-EN subgroup. Conclusion: The parenteral route may be safe, even when administered early, and may provide adequate nutrition delivery. Additional EN, when possible, may optimize protein requirements, especially in more severe patients who received initial PN and are expected to have longer ICU stays. NCT Registry: 03634943

    Natural and Undetermined Sudden Death: Value of Post-Mortem Genetic Investigation

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    Background: Sudden unexplained death may be the first manifestation of an unknown inherited cardiac disease. Current genetic technologies may enable the unraveling of an etiology and the identification of relatives at risk. The aim of our study was to define the etiology of natural deaths, younger than 50 years of age, and to investigate whether genetic defects associated with cardiac diseases could provide a potential etiology for the unexplained cases. Methods and Findings: Our cohort included a total of 789 consecutive cases (77.19% males) <50 years old (average 38.6±12.2 years old) who died suddenly from non-violent causes. A comprehensive autopsy was performed according to current forensic guidelines. During autopsy a cause of death was identified in most cases (81.1%), mainly due to cardiac alterations (56.87%). In unexplained cases, genetic analysis of the main genes associated with sudden cardiac death was performed using Next Generation Sequencing technology. Genetic analysis was performed in suspected inherited diseases (cardiomyopathy) and in unexplained death, with identification of potentially pathogenic variants in nearly 50% and 40% of samples, respectively. Conclusions: Cardiac disease is the most important cause of sudden death, especially after the age of 40. Close to 10% of cases may remain unexplained after a complete autopsy investigation. Molecular autopsy may provide an explanation for a significant part of these unexplained cases. Identification of genetic variations enables genetic counseling and undertaking of preventive measures in relatives at risk

    Algunas evidencias de aplicación

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    Libro temático especializadoLa sustentabilidad también debe aplicarse al sistema de producción, buscando impulsar transformaciones graduales de los estilos y modelos productivos tradicionales a unas de mayor eficiencia. Y donde se incorpore la dimensión ambiental y geográfico-espacial, para crear estructuras productivas más progresivas y equitativas en las sociedades. Todo esto, como alternativa para revertir las tendencias de escasez y agotamiento de los recursos naturales, así como de los desequilibrios globales, cuyos costos permean todos los tejidos humanos. De esta manera, la “sustentabilidad productiva” se concibe como la generación de bienes y servicios con ciertos estándares de calidad, bajo un esquema de eficiencia, rendimiento y de organización inclusiva e integrada, con baja presión al ambiente y uso racional de los recursos, garantizando la estadía y permanencia de los insumos y materiales en el tiempo. Desde esta perspectiva, la producción sustentable y el crecimiento de largo plazo pueden ser explicados por la capacidad que tienen las economías para generar e incorporar conocimientos y tecnologías. De ahí que, la educación y las cualificaciones del capital humano, los cambios en la organización de la producción y la calidad institucional, sean elementos nodales para avanzar en la consolidación de este ambiente productivo
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