4,934 research outputs found

    The SUSY partners of the QES sextic potential revisited

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    In this paper, the SUSY partner Hamiltonians of the quasi-exactly solvable (QES) sextic potential Vqes(x)=νx6+2νμx4+[μ2(4N+3)ν]x2V^{\rm qes}(x) = \nu\, x^{6} + 2\, \nu\, \mu\,x^{4} + \left[\mu^2-(4N+3)\nu \right]\, x^{2}, NZ+N \in \mathbb{Z}^+, are revisited from a Lie algebraic perspective. It is demonstrated that, in the variable τ=x2 \tau=x^2, the underlying sl2(R)\mathfrak{sl}_2(\mathbb{R}) hidden algebra of Vqes(x)V^{\rm qes}(x) is inherited by its SUSY partner potential V1(x)V_1(x) only for N=0N=0. At fixed N>0N>0, the algebraic polynomial operator h(x,x;N)h(x,\,\partial_x;\,N) that governs the NN exact eigenpolynomial solutions of V1V_1 is derived explicitly. These odd-parity solutions appear in the form of zero modes. The potential V1V_1 can be represented as the sum of a polynomial and rational parts. In particular, it is shown that the polynomial component is given by VqesV^{\rm qes} with a different non-integer (cohomology) parameter N1=N32N_1=N-\frac{3}{2}. A confluent second-order SUSY transformation is also implemented for a modified QES sextic potential possessing the energy reflection symmetry. By taking NN as a continuous real constant and using the Lagrange-mesh method, highly accurate values (20\sim 20 s. d.) of the energy En=En(N)E_n=E_n(N) in the interval N[1,3]N \in [-1,3] are calculated for the three lowest states n=0,1,2n=0,1,2 of the system. The critical value NcN_c above which tunneling effects (instanton-like terms) can occur is obtained as well. At N=0N=0, the non-algebraic sector of the spectrum of VqesV^{\rm qes} is described by means of compact physically relevant trial functions. These solutions allow us to determine the effects in accuracy when the first-order SUSY approach is applied on the level of approximate eigenfunctions.Comment: 25 pages, 20 figure

    Resultados del tratamiento de la inestabilidad postdisectomia mediante artrodesis posterolateral lumbar

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    El mecanismo fisiopatológico por el cual, tras una discectomia en columna lumbar, se puede producir inestabilidad en este segmento de la columna, ha sido establecido en múltiples estudios y se encuentra en la bibliografía actual. Sin embargo, hay pocas publicaciones en la literatura que hagan referencia a los resultados de la artrodesis posterolateral lumbar en inestabilidad clínico-radiológica generada tras una discectomia lumbar. El propósito del presente estudio es valorar los resultados obtenidos en mejora de calidad de vida, en pacientes sometidos a artrodesis lumbar con tornillos pediculares en inestabilidad postdisectomía. La población estudiada se trató de 15 pacientes, 10 hombres y 5 mujeres con edades comprendidas entre los 27 y 65 años, la selección de los pacientes además del antecedente de cirugía discal, se basó en la presencia de un cuadro clínico de inestabilidad unido a pruebas radiológicas estáticas, dinámicas y resonancia magnética, y por último la ausencia de problemas de tipo laboral o psicológico, los datos se obtuvieron por entrevista personal y llamada telefónica, utilizando la escala de Oswestry y la escala analógica de Scott. Los resultados obtenidos fueron buenos ya que más del 90% de los pacientes refirieron mejoría en su calidad de vida. Se puede concluir que la artrodesis posterolateral con tornillos pediculares en inestabilidad postdisectomia, es una buena opción quirúrgica, con la cual se puede obtener mejoría del cuadro clínico del paciente.The present study has the aime, the evaluation of results of posterolateral lumbar arthrodesis in patients who had undergone lumbar discal surgery failed because of appearance of instability. Retrospective study in 15 patients with diagnosis instability postdiskectomy made by: clinical, static and dynamic x-ray and MRI, treated with posterolateral lumbar arthrodesis using pedicular screw. Ten males and five female of 27-65 years and average 46, we used the life quality scale Oswestry and Scott scale. The shortest follow up 3 years and longest 6 years. Our results were: time between diskectomy and arthrodesis variated from 1 to 10 years, average 5 years, about: pain intensity, patients need analgesic because pain, help for activities, deambulation, sexual activity all of them improve. We had 3 cases with clinical symptoms, the other one pain free. One case of deep infection of wound where surgical debridement was necessary. Finally Scott¿s scale prior to surgery punctuation was between 1-4. after between 8-10. Excepting 1 case with bad evolution. Conclusion: posterolateral lumbar arthrodesis with pedicular screew can be a good option of treatment in instability postdikectomy

    Tailored two-dimensional finite-element formulations for ad-hoc analysis of waveguiding and mode-matching problems

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    The analysis of homogeneous closed waveguides is known to be one of the first, if not the very first, problems to be addressed with the finite element method (P. Silvester, “Finite element solution of homogeneous waveguide problems”, Alta Frequenza, vol. 38, pp. 313–317, 1969) in the framework of computational electromagnetics. Since this two-dimensional scalar case, many developments have followed: extension to three-dimensional analysis, derivation of curlconforming edge and higher-order elements, domain decomposition approaches, hybridization with other numerical or analytical methods, etc. This has led the finite element method to be considered one of the most well-established, reliable techniques to address cutting-edge problems in computational electromagnetics, with many reference books (G. Pelosi, R. Coccioli, S. Selleri, Quick Finite Elements for Electromagnetic Waves, Norwood, MA, USA: Artech House, 2009; J. Jin, The Finite Element Method in Electromagnetics, Hoboken, NJ, USA: Wiley, 2015). Despite these long-known advancements, resorting to solving the afore-mentioned (and, at first glance, simple) problem of computing the modes in any waveguiding cross-section still plays a key role in computer-aided design methodologies that rely on the modal description of the fields, as is the case of the mode-matching method. In this case, not only an accurate calculation of these modal fields is required, but also the capability to compute as many modes (without skipping a single one) as necessary to ensure convergence. If the problem demands for it, it is also imperative to have a straightforward division into different classes or types of modes according to symmetries and possible excitations, as well as a proper identification of degenerate modes. In this work, we will review some strategies and tailored two-dimensional finite-element formulations proposed by the authors to address some of the issues arising when analyzing waveguiding structures, especially focusing on obtaining proper modal decompositions of the fields to be used in further computer-aided design of waveguide devices through mode-matching techniques. Some of these strategies and formulations include the comparison of different types of meshes (structured quadrilateral vs. unstructured triangular) when the waveguide cross-sections have 90º corners, as well as the development of specific boundary conditions to model novel materials enclosing the waveguide (such as graphene) or to account for higher-order symmetries (such as rotational ones) in structures with a high number of degenerate modes. In the latter case, this is especially useful for devices conceived to operate with circular polarization

    Adaptive Filtered-x Algorithms for Room Equalization Based on Block-Based Combination Schemes

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    (c) 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.[EN] Room equalization has become essential for sound reproduction systems to provide the listener with the desired acoustical sensation. Recently, adaptive filters have been proposed as an effective tool in the core of these systems. In this context, this paper introduces different novel schemes based on the combination of adaptive filters idea: a versatile and flexible approach that permits obtaining adaptive schemes combining the capabilities of several independent adaptive filters. In this way, we have investigated the advantages of a scheme called combination of block-based adaptive filters which allows a blockwise combination splitting the adaptive filters into nonoverlapping blocks. This idea was previously applied to the plant identification problem, but has to be properly modified to obtain a suitable behavior in the equalization application. Moreover, we propose a scheme with the aim of further improving the equalization performance using the a priori knowledge of the energy distribution of the optimal inverse filter, where the block filters are chosen to fit with the coefficients energy distribution. Furthermore, the biased block-based filter is also introduced as a particular case of the combination scheme, especially suited for low signal-to-noise ratios (SNRs) or sparse scenarios. Although the combined schemes can be employed with any kind of adaptive filter, we employ the filtered-x improved proportionate normalized least mean square algorithm as basis of the proposed algorithms, allowing to introduce a novel combination scheme based on partitioned block schemes where different blocks of the adaptive filter use different parameter settings. Several experiments are included to evaluate the proposed algorithms in terms of convergence speed and steady-state behavior for different degrees of sparseness and SNRs.The work of L. A. Azpicueta-Ruiz was supported in part by the Comtmidad de Madrid through CASI-CAM-CM under Grant S2013/ICE-2845, in part by the Spanish Ministry of Economy and Competitiveness through DAMA under Grant TIN2015-70308-REDT, and Grant TEC2014-52289-R, and in part by the European Union. The work of L. Fuster, M. Ferrer, and M. de Diego was supported in part by EU together with the Spanish Government under Grant TEC2015-67387-C4-1-R (MINECO/FEDER), and in part by the Cieneralitat Valenciana under Grant PROMETEOII/2014/003. The associate editor coordinating the review of this manuscript and approving it for publication was Prof. Simon Dodo.Fuster Criado, L.; Diego Antón, MD.; Azpicueta-Ruiz, LA.; Ferrer Contreras, M. (2016). Adaptive Filtered-x Algorithms for Room Equalization Based on Block-Based Combination Schemes. IEEE/ACM Transactions on Audio, Speech and Language Processing. 24(10):1732-1745. https://doi.org/10.1109/TASLP.2016.2583065S17321745241

    Structure and tectonics of the central Chilean margin (31°–33°S): implications for subduction erosion and shallow crustal seismicity

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    The pre- and current collision of the Juan Fernández Ridge with the central Chilean margin at 31°–33°S is characterized by large-scale crustal thinning and long-term subsidence of the submarine forearc caused by subduction erosion processes. Here, we study the structure of the central Chilean margin in the ridge–trench collision zone by using wide-angle and multichannel seismic data. The transition from the upper to middle continental slope is defined by a trenchward dipping normal scarp with variable offsets of 500–2000 m height. Beneath the scarp, the 2-D velocity–depth models show a prominent lateral velocity contrast of >1 s−1 that propagates deep into the continental crust defining a major lateral seismic discontinuity. The discontinuity is interpreted as the lithological contact between the subsided/collapsed outermost forearc (composed of eroded and highly fractured volcanic rocks) and the seaward part of the uplifted Coastal Cordillera (made of less fractured metamorphic/igneous rocks). Extensional faults are abundant in the collapsed outermost forearc, however, landward of the continental slope scarp, both extensional and compressional structures are observed along the uplifted continental shelf that forms part of the Coastal Cordillera. Particularly, at the landward flank of the Valparaíso Forearc Basin (32°–33.5°S), shallow crustal seismicity has been recorded in 2008–2009 forming a dense cluster of thrust events of Mw 4–5. The estimated hypocentres spatially correlate with the location of the fault scarp, and they highlight the upper part of the seismic crustal discontinuity

    Colaboración internacional y buenas prácticas en la gestión de enfermedades crónicas complejas a través de herramientas web 2.0: Observatorio de prácticas innovadoras en el manejo de enfermedades crónicas complejas OPIMEC

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    Ponencias de la Segunda Conferencia internacional sobre brecha digital e inclusión social, celebrada del 28 al 30 de octubre de 2009 en la Universidad Carlos III de MadridLas enfermedades crónicas (EC) constituyen un reto de salud mundial en el siglo XXI. La OMS las define como enfermedades de larga duración por lo general de progresión lenta y prevé que en 2020 serán responsables del 73% de las muertes y del 60% de la carga global de enfermedad (World Health Organization, 2002). Es primordial que la comunidad internacional de salud pública y de gestión sanitaria conozca y comparta información sobre los avances en las prácticas tecnológicas y organizativas más innovadoras en gestión de EC, con énfasis en las EC Complejas (ECC) asociadas a una mayor pérdida de autonomía y grado de dependencia y discapacidad. Con este propósito, a mediados de 2006, la Dirección General de Innovación Sanitaria, Sistemas y Tecnología de la Consejería de Salud de la Junta de Andalucía crea el «Observatorio de Prácticas Innovadoras para el Manejo de Enfermedades Crónicas Complejas» (OPIMEC) que impulsa la participación y generación de conocimiento en información sanitaria para profesionales y una Plataforma de Red en el ámbito de la gestión de ECC para el fomento de alianzas y colaboraciones desde Andalucía basadas en dar y recibir conocimiento abierto entre personas, equipos y organizaciones (Jadad AR, 1999, p. 761-764; Jadad AR, 2000, p.362-365). La Web del Observatorio de Prácticas Innovadoras en el Manejo de Enfermedades Crónicas Complejas (OPIMEC), http://www.opimec.org, va centrada en la creación de una plataforma basada en la Web 2.0. que permite el acceso y la edición colaborativa de contenidos para profesionales. El objetivo fundamental de esta plataforma es compartir y colaborar en la generación y difusión de conocimiento, todo ello facilitado con herramientas innovadoras de la Web 2.0. como son la publicación de contenidos, la votación, comentarios sobre los contenidos, la sindicación de contenidos y la creación de comunidades abiertas de trabajo colaborativo. El proyecto OPIMEC cuenta con una cadena de procesos de gestión de la información de los que podemos destacar su forma colaborativa de crear conocimiento por todas las personas usuarias de la plataforma, un equipo editorial encargado de asegurar la calidad de los contenidos y una evaluación por pares de las prácticas y organizaciones propuestas en la Web. Desde la edición, hasta la publicación y su distribución final el conocimiento es examinado metódicamente. Este proceso es automatizado a través de herramientas de software libre creadas para OPIMEC y asesorado por su Consejo Asesor Internacional. Así pues, la plataforma Web 2.0 que da soporte al observatorio OPIMEC está construida sobre tecnologías libres como: Framework Web Django (impulsado por Google Inc. entre otros), MySQL y GNU/Linux. La elección de esta combinación tecnológica se ha realizado tras un análisis exhaustivo sobre las tecnologías abiertas disponibles, en base a criterios de eficiencia, productividad y adaptabilidad a las necesidades actuales y futuras de OPIMEC. La Web OPIMEC tiene intención y vocación de convertirse en un destacado proyecto a nivel mundial con clara vertiente de cooperación internacional e innovación, mejorando la calidad de vida de la ciudadanía, aprovechando las herramientas que ofrece la difundida red global de Internet y promocionando la participación e iniciativa de los y las profesionales. Nuestra Web OPIMEC está estructurada en espacios que facilitan y propician la participación y consecución de los objetivos del proyecto, con el fin de que la asimilación de sus contenidos por parte de las personas usuarias sea eficiente y efectiva. Podemos encontrar en ella, herramientas existentes en las redes sociales así como algunas nuevas desarrolladas específicamente para OPIMEC, como son los “documentos colaborativos”, que facilitarán el trabajo, la conexión y la participación de profesionales desde cualquier parte del mundo, pudiendo así aprovechar los recursos al máximo, Se dispone por tanto de destacadas herramientas como una base de datos actualizada de eventos, noticias, recursos y documentos, directorios y mapas de organizaciones, prácticas y personas innovadoras, espacios de comunidad en las que los equipos de trabajo pueden desarrollarse, comunicarse y complementarse con otras personas usuarias, compartiendo buenas prácticas, innovación y contenidos novedosos en el manejo de enfermedades crónicas complejas. El aspecto importante de la plataforma es que las personas usuarias son de forma democrática, creadores, evaluadores y consumidores de los contenidos publicados, siendo así una herramienta de trabajo construida, ampliada, valorada y seguida por toda la comunidad de profesionales; facilitando la difusión del conocimiento construido por y para todos y todas los profesionales sanitarios, personal investigador, ciudadanos y ciudadanas en general en el manejo de enfermedades crónicas complejas. Un conocimiento ampliamente compartido es la clave para aumentar y mejorar el bienestar social y la calidad de vida

    Most worrysome weeds in Spain

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    Se presentan los resultados de una encuesta realizada durante el periodo de junio a octubre de 2014, y en la que participaron 315 técnicos de campo de toda España. Los datos están disponibles en Internet y su análisis permite concluir que a) las malas hierbas preocupan tanto como las plagas y enfermedades; b) respecto a los métodos de control, el control químico con herbicidas es el más usado y el considerado más eficaz; se han detectado las malas hierbas más preocupantes en una serie de cultivos, incluyendo el motivo de la preocupación. En cultivos leñosos, destaca “Conyza” por su dificultad de control, en arroz destacan “Echinochloa” y “Cyperus”; en algodón y maíz preocupan “Abutilon”, “Chenopodium”, “Cyperus”, Echinochloa y Sorghum; en cultivos extensivos de secano, la preocupación no está tan concentrada en pocas especies, destacando malas hierbas gramíneas en trigo y cebada junto con Centaurea, que es considerada preocupante adicionalmente en el cultivo del girasol. Finalmente, se seleccionan arvenses de preocupación creciente, entre las que destacan “Abutilon”, “Centaurea”, “Chenopodium” y “Sorghum”.Since June to October 2014, 315 Spanish field advisors participated in a survey. Data is available on internet and results show that a) weeds are as worrying as other pests and diseases; b) chemical control is the most used weed control method and is considered to be the most efficient one; c) knowledge transfer in weed management is largely dependant on herbicide industry; d) most worrying weeds have been identified for several crops, as well as the reasons why they are considered worrysome. In permanent crops, “Conyza” is refered to be by far the worst weed, mainly because it is difficult to control; in rice, the worst weeds are “Echinochloa” and “Cyperus”; in corn and cotton “Abutilon”, “Chenopodium”, “Cyperus”, “Echinochloa” and “Sorghum”; in annual dryland crops weed problems are less focused, being the most worrying weeds annual grasses in wheat and barley, besides “Centaurea”, which is also considered to be a problem in sunflower. Finally, there are weeds of increasing threat like “Abutilon”, “Centaurea”, “Chenopodium” and “Sorghum”

    Use of Nanostructured Photocatalysts for Dye Degradation: A Review

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    Among the technologies proposed for wastewater treatment, the Advanced Oxidation Processes are viable and technological strategies for dyes degradation. Different photocatalytic systems classified in metal oxides alone or combined through hybrid composites or immobilized onto supports have been designed in various nanostructured shapes for their application in the photodegradation of polluting dyes. This review aims to describe the dyes as an environmental threat, photocatalysis as an effective process to remove dyes from water and provide an overview of the recent studies using photocatalytic systems grouped according to their development. Furthermore, this review describes the main parameters of a photocatalytic system with an important role in dye photodegradation. Finally, we discuss the limitations of photocatalysis for real industrial applications and the challenges for this environmental nanotechnology

    A simulation analysis of an influenza vaccine production plant in areas of high humanitarian flow. A preliminary study for the region of norte de santander (colombia)

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    The production of vaccines of biological origin presents a tremendous challenge for re-searchers. In this context, animal cell cultures are an excellent alternative for the isolation and production of biologicals against several viruses, since they have an affinity with viruses and a great capacity for their replicability. Different variables have been studied to know the system’s ideal parameters, allowing it to obtain profitable and competitive products. Consequently, this work fo-cuses its efforts on evaluating an alternative for producing an anti‐influenza biological from MDCK cells using SuperPro Designer v8.0 software. The process uses the DMEN culture medium supple-mented with nutrients as raw material for cell development; the MDCK cells were obtained from a potential scale‐up with a final working volume of 500 L, four days of residence time, inoculum volume of 10%, and continuous working mode with up to a total of 7400 h/Yr of work. The scheme has the necessary equipment for the vaccine’s production, infection, and manufacture with yields of up to 416,698 units/h. In addition, it was estimated to be economically viable to produce recom-binant vaccines with competitive prices of up to 0.31 USD/unit
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