161 research outputs found

    Aplicación de la rectificación controlada en los convertidores DC-DC de varios interruptores de tanque resonante serie

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    En el presente trabajo se estudia la aplicación de la rectificación controlada en los convertidores DC-DC de varios interruptores de tanque resonante serie. Los convertidores estudiados son el PRC, el SRC y el SPRC. En estas estructuras se va a analizar las posibilidades de regulación que ofrecen dichos convertidores, con la finalidad de obtener la máxima robustez ante variaciones de la carga y de la tensión de entrada.Tras el primer capítulo de introducción a la temática de la tesis, en el capítulo segundo se deducen unos nuevos convertidores derivados de los clásicos. Se obtienen los modelos matemáticos de los convertidores resultantes de la sustitución de las etapas rectificadoras y se sintetizan las nuevas estructuras rectificadoras. Los nuevos convertidores van a denominarse PRC-CR, SRC-CR y SPRC-CR, en clara alusión a su nueva etapa de rectificación controlada (Controlled Rectification).En el tercer capítulo se introducen los controladores desarrollados para los nuevos convertidores. El control del convertidor se va a realizar actuando en el bloque rectificador mediante dos tipos básicos de actuación. El primero con realimentación de variable de estado del tanque resonante, mediante un controlador no lineal One-Cycle.El segundo con realimentación de variable de estado de salida, mediante un regulador lineal PI.En el cuarto capítulo se analiza la estructura del convertidor PRC-CR mediante dos métodos de análisis. El primer método propuesto es el de aproximación al primer armónico, y de su análisis se deducirán interesantes conclusiones. En primer lugar puntos de trabajo óptimos para posibilitar la regulación en el convertidor dadas las condiciones de carga del mismo. Se obtendrá la dependencia de la variable propia de salida de cada convertidor respecto a la relación de conducción del bloque rectificador y se propondrán criterios de diseño del convertidor. La metodología planteada se verifica mediante la simulación del convertidor. El segundo método de análisis se basa en la solución del modelo matemático en espacio de estado del convertidor. Bajo este análisis se obtendrá nuevamente la relación de la tensión de salida respecto a la relación de conducción de la etapa rectificadora y los parámetros del convertidor. Finalmente se comparan los resultados obtenidos por ambos métodos de análisis.En el quinto y sexto capítulo se analizan los convertidores SRC-CR y SPRC-CR, respectivamente, de igual forma a la propuesta en el capítulo cuarto del PRC-CR. En el séptimo capítulo se presentan los resultados experimentales obtenidos de los prototipos de los convertidores desarrollados.Finalmente en el capítulo octavo se presentan las conclusiones obtenidas de la tesis doctoral. Se evalúan los beneficios y limitaciones observadas en las estructuras desarrolladas. Se propone el planteamiento de posibles mejoras en función de las no idealidades del convertidor y del controlador propuesto, abriendo futuras líneas de investigación que servirán de complemento al presente trabajo

    Electrical PV array reconfiguration strategy for energy extraction improvement in grid-connected PV systems

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    This paper applies a dynamical electrical array reconfiguration (EAR) strategy on the photovoltaic (PV) generator of a grid-connected PV system based on a plant-oriented configuration, in order to improve its energy production when the operating conditions of the solar panels are different. The EAR strategy is carried out by inserting a controllable switching matrix between the PV generator and the central inverter, which allows the electrical reconnection of the available PV modules. As a result, the PV system exhibits a self-capacity for real-time adaptation to the PV generator external operating conditions and improves the energy extraction of the system. Experimental results are provided to validate the proposed approach.Postprint (published version

    Guía de especies vegetales de la cuenca mediterránea aptas para revegetación: Adecuación para zonas degradadas y contaminadas

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    La guía contiene información de especies de plantas de la cuenca mediterránea, adecuadas para utilizar en revegetación de zonas degradadas y/o contaminadas con presencia de metales pesados, siguiendo diferentes criterios medioambientales y paisajísticos y estableciendo recomendaciones o restricciones para su implantación y crecimiento, sin necesidad de recurrir a la utilización de especies exóticas con potencial invasor. Para cada especie se proporciona información abreviada de las principales características que las hacen aptas para su uso en los diferentes entornos. Finalmente se establecen cinco modelos de asociaciones paisajísticas para usar en diferentes zonas y con diferentes condiciones medioambientales

    Adenosine deaminase as a biomarker of tenofovir mediated inflammation in naïve HIV patients

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    Plasma levels of adenosine deaminase (ADA), an enzyme that deaminates adenosine to inosine, are increased during inflammation. An increase in ADA activity occurs with lower human immunodeficiency virus (HIV) viral load and higher CD4+ T cell counts. We aimed to investigate the role of plasma ADA as a biomarker of inflammation in treatment-naïve HIV patients who received tenofovir or another nucleoside analog for comparison. Ninety-two treatment-naïve patients were included in the study and grouped by treatment, i.e., tenofovir disoproxil fumarate (TDF), tenofovir alafenamide (TAF) or Triumeq. ADA activity was measured in plasma and cytokines were analyzed by MILLIPLEX® MAP-Luminex® Technology. Plasma concentration of monocytes and neutrophils was measured at 0, 3, and 12 months post-treatment. Treatment-naïve HIV patients had increased ADA concentrations (over 15 U/L) that decreased after treatment with TAF and Triumeq, though this did not occur in TDF-treated patients. However, all groups exhibited a pro-inflammatory systemic profile at 12 months of treatment. Plasma GM-CSF levels decreased after 12 months of treatment in the TDF group, with a concomitant decrease in blood monocyte count, and a negative correlation with ADA values was found. In conclusion, ADA levels may be modulated by antiretroviral therapy in HIV patients, possibly affecting inflammatory status.This work was supported by grants from Instituto de Salud Carlos III through the “Miguel Servet” program (CP15/00053), co-funded by Fondo Europeo de Desarrollo Regional (FEDER) and research grants from the Spanish Instituto de Salud Carlos III (PI16/00991 and PI19/00744

    Debate sobre la Ley Federal del Trabajo

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    Se recuerda con preocupación la forma como la política laboral instrumentada en el sexenio de Carlos Salinas impuso "soluciones" a cada uno de los conflictos obrero patronales, soluciones adoptadas al margen y por sobre la normatividad laboral de esos días. Se abre boca a la discusión sin pensar que los avances tengan alguna significación, ya que muy pronto se llegó a ciertas conclusiones colectivas, de definición y proposición de temáticas tales como la libertad sindical, las condiciones de trabajo y la efectividad de las nuevas normas. Estas propuestas y reflexiones hechas en un contexto en el que la productividad en el trabajo y la capacitación para su realización, son preocupaciones de los trabajadores y sus sindicatos, en que la búsqueda de una salida a la crisis económica que padecemos puede ser encontrada sin mayores sacrificios que los que ya padece la clase trabajadora y en función a un interés nacional y popular

    VARIACIÓN ESTILÍSTICA EN LA ADQUISICIÓN DEL LÉXICO INICIAL

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    The aim of this work is to analyse the recent studies about individual differences in lexical development. Two questions are examined: the study about how children learn early language, and the origin of these differences. The most recent research points out temperament as relevant factor in the explication of individual differences in first language.El objetivo de este trabajo es analizar las recientes aportaciones realizadas al estudio de las diferencias individuales en el desarrollo del léxico. Se abordan dos cuestiones, las diversas formas en la que los niños aprenden el lenguaje inicial, y el origen de estas diferencias. Las investiga-ciones más recientes señalan al temperamento como uno de los factores relevantes en la explicación de las diferencias individuales en el primer lenguaje

    Technological Development in the Use of <em>Allium sativum</em> Aqueous Extracts in the Agricultural Field

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    The advance in agricultural technology could increase their commercialization, being the agronomic management for each crop an alternative. The management of natural products is a relevant and responsible need, in order to improve the quality and production of food, and to protect the agro-ecosystem biodiversity. Therefore, the aim of this chapter is to present our five-year study advances in mango and rambutan agronomic management with aqueous extract of Allium sativum and the use of natural adherent such as Melipona solani honey that improves the function of the components in the biological processes of the crop. Our results showed that this aqueous extract promotes the emission of vegetative and floral shoots, increases flower development, works as an attractant for pollinators, promotes fruit set, stimulates fruit growth, acts as an insecticide to control thrips and mealybugs and stimulates the production of defense metabolites, such as polyphenol compounds. The use of stingless bee honey as an adherent and the aqueous extract of A. sativum could be a key to potentiate the function of its components in leaves, panicles, flowers and fruits

    Bone Deleterious Effects of Different NRTIs in Treatment-naïve HIV Patients After 12 and 48 Weeks of Treatment

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    Background: Bone alterations have been observed in the course of HIV infection, char-acterized by a marked decrease in bone mineral density (BMD) and an increase in the frequency of fractures as a result of fragility. We aim to evaluate early changes in bone metabolic profile and the possible association with tenofovir and other nucleoside and nucleotide reverse transcriptase inhibi-tors (NRTIs) in treatment-naïve HIV patients. Methods: We conducted a prospective study in naïve HIV-infected adults (under 50 years), separat-ed into three groups according to NRTI therapy: tenofovir disoproxil fumarate (TDF); tenofovir alafenamide (TAF) and abacavir (ABC). BMD and epidemiological, immunological and metabolic bone parameters were evaluated. Bone markers were analyzed in plasma at baseline, 12 and 48 weeks after initiating treatment. Results: Average age of patients was 34.8 years (± 9.6). 92.4% of them with CD4 count > 200 cel/μL. At week 12 after starting treatment, both TDF [increase in PN1P (31.7%, p = 0.004), TRAP (11.1%, p = 0.003), OPN (19.3%, p = 0.045) and OC (38.6%, p = 0.001); decrease in OPG (-23.4%, p = 0.003)] and TAF [increase in 42.6% for CTX (p = 0.011), 27.3% for OC (p = 0.001) and 21% for TRAP (p = 0.008); decrease in OPG (-28.8%, p = 0.049)] presented a deep resorption profile compared to ABC, these differences in bone molecular markers, a tendency to equalize at week 48, where no significant differences were observed. Patients treated with TDF showed the greatest decrease in Z-score in both lumbar spine (LS) and femoral neck (FN) at week 48 without statistically significant differences. Conclusion: Treatment-naïve HIV patients have a high prevalence of low bone density. Treatment with TDF is associated with greater bone deterioration at 12 and 48 weeks. TAF seems to present similar early bone deterioration at 12 weeks which disappears at 48 weeks.This research was financially supported by The Carlos III Health Institute through the “Miguel Servet” program (CP15/00053), co-funded by The European Regional Development Fund and research grants from the Spanish Carlos III Health Institute (PI16/00991 and PI19/00744

    Transcriptome profiling of rabbit parthenogenetic blastocysts developed under in vivo conditions

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    Parthenogenetic embryos are one attractive alternative as a source of embryonic stem cells, although many aspects related to the biology of parthenogenetic embryos and parthenogenetically derived cell lines still need to be elucidated. The present work was conducted to investigate the gene expression profile of rabbit parthenote embryos cultured under in vivo conditions using microarray analysis. Transcriptomic profiles indicate 2541 differentially expressed genes between parthenotes and normal in vivo fertilised blastocysts, of which 76 genes were upregulated and 16 genes downregulated in in vivo cultured parthenote blastocyst, using 3 fold-changes as a cut-off. While differentially upregulated expressed genes are related to transport and protein metabolic process, downregulated expressed genes are related to DNA and RNA binding. Using microarray data, 6 imprinted genes were identified as conserved among rabbits, humans and mice: GRB10, ATP10A, ZNF215, NDN, IMPACT and SFMBT2. We also found that 26 putative genes have at least one member of that gene family imprinted in other species. These data strengthen the view that a large fraction of genes is differentially expressed between parthenogenetic and normal embryos cultured under the same conditions and offer a new approach to the identification of imprinted genes in rabbit. © 2012 Naturil-Alfonso et al.This work was supported by Generalitat Valenciana research programme (Prometeo 2009/125). Carmen Naturil was supported by Generalitat Valenciana research programme (Prometeo 2009/125). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Naturil Alfonso, C.; Saenz De Juano Ribes, MDLD.; Peñaranda, D.; Vicente Antón, JS.; Marco Jiménez, F. (2012). Transcriptome profiling of rabbit parthenogenetic blastocysts developed under in vivo conditions. PLoS ONE. 7(12):1-11. https://doi.org/10.1371/journal.pone.0051271S111712Harness, J. 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General and Comparative Endocrinology, 142(1-2), 134-142. doi:10.1016/j.ygcen.2004.12.019Llobat, L., Marco-Jiménez, F., Peñaranda, D., Saenz-de-Juano, M., & Vicente, J. (2011). Effect of Embryonic Genotype on Reference Gene Selection for RT-qPCR Normalization. Reproduction in Domestic Animals, 47(4), 629-634. doi:10.1111/j.1439-0531.2011.01934.xLiu, N., Enkemann, S. A., Liang, P., Hersmus, R., Zanazzi, C., Huang, J., … Liu, L. (2010). Genome-wide Gene Expression Profiling Reveals Aberrant MAPK and Wnt Signaling Pathways Associated with Early Parthenogenesis. Journal of Molecular Cell Biology, 2(6), 333-344. doi:10.1093/jmcb/mjq029Abdoon, A. S., Ghanem, N., Kandil, O. M., Gad, A., Schellander, K., & Tesfaye, D. (2012). cDNA microarray analysis of gene expression in parthenotes and in vitro produced buffalo embryos. Theriogenology, 77(6), 1240-1251. doi:10.1016/j.theriogenology.2011.11.004Labrecque, R., & Sirard, M.-A. (2011). 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    Non-invasive prehabilitation to foster widespread fMRI cortical reorganization before brain tumor surgery: lessons from a case series

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    PurposeThe objective of this prospective, single-centre case series was to investigate feasibility, clinical outcomes, and neural correlates of non-invasive Neuromodulation-Induced Cortical Prehabilitation (NICP) before brain tumor surgery. Previous studies have shown that gross total resection is paramount to increase life expectancy but is counterbalanced by the need of preserving critical functional areas. NICP aims at expanding functional margins for extensive tumor resection without functional sequelae. Invasive NICP (intracranial neuromodulation) was effective but characterized by elevated costs and high rate of adverse events. Non-invasive NICP (transcranial neuromodulation) may represent a more feasible alternative. Nonetheless, up to this point, non-invasive NICP has been examined in only two case reports, yielding inconclusive findings.MethodsTreatment sessions consisted of non-invasive neuromodulation, to transiently deactivate critical areas adjacent to the lesion, coupled with intensive functional training, to activate alternative nodes within the same functional network. Patients were evaluated pre-NICP, post-NICP, and at follow-up post-surgery.ResultsTen patients performed the intervention. Feasibility criteria were met (retention, adherence, safety, and patient's satisfaction). Clinical outcomes showed overall stability and improvements in motor and executive function from pre- to post-NICP, and at follow-up. Relevant plasticity changes (increase in the distance between tumor and critical area) were observed when the neuromodulation target was guided by functional neuroimaging data.ConclusionThis is the first case series demonstrating feasibility of non-invasive NICP. Neural correlates indicate that neuroimaging-guided target selection may represent a valid strategy to leverage neuroplastic changes before neurosurgery. Further investigations are needed to confirm such preliminary findings
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