317 research outputs found

    The predictability of advection-dominated flux-transport solar dynamo models

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    Space weather is a matter of practical importance in our modern society. Predictions of forecoming solar cycles mean amplitude and duration are currently being made based on flux-transport numerical models of the solar dynamo. Interested in the forecast horizon of such studies, we quantify the predictability window of a representative, advection-dominated, flux-transport dynamo model by investigating its sensitivity to initial conditions and control parameters through a perturbation analysis. We measure the rate associated with the exponential growth of an initial perturbation of the model trajectory, which yields a characteristic time scale known as the e-folding time τe\tau_e. The e-folding time is shown to decrease with the strength of the α\alpha-effect, and to increase with the magnitude of the imposed meridional circulation. Comparing the e-folding time with the solar cycle periodicity, we obtain an average estimate for τe\tau_e equal to 2.76 solar cycle durations. From a practical point of view, the perturbations analysed in this work can be interpreted as uncertainties affecting either the observations or the physical model itself. After reviewing these, we discuss their implications for solar cycle prediction.Comment: 33 pages, 12 figure

    A mean-field Babcock-Leighton solar dynamo model with long-term variability

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    Dynamo models relying on the Babcock-Leighton mechanism are successful in reproducing most of the solar magnetic field dynamical characteristics. However, considering that such models operate only above a lower magnetic field threshold, they do not provide an appropriate magnetic field regeneration process characterizing a self-sustainable dynamo. In this work we consider the existence of an additional \alpha-effect to the Babcock-Leighton scenario in a mean-field axisymmetric kinematic numerical model. Both poloidal field regeneration mechanisms are treated with two different strength-limiting factors. Apart from the solar anti-symmetric parity behavior, the main solar features are reproduced: cyclic polarity reversals, mid-latitudinal equatorward migration of strong toroidal field, poleward migration of polar surface radial fields, and the quadrature phase shift between both. Long-term variability of the solutions exhibits lengthy periods of minimum activity followed by posterior recovery, akin to the observed Maunder Minimum. Based on the analysis of the residual activity during periods of minimum activity, we suggest that these are caused by a predominance of the \alpha-effect over the Babcock-Leighton mechanism in regenerating the poloidal field.Comment: 21 pages, 6 figure

    Genome wide comparative analysis of the effects of PRMT5 and PRMT4/CARM1 arginine methyltransferases on the Arabidopsis thaliana transcriptome

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    BACKGROUND: Methylation at arginine residues (R) is an important post-translational modification that regulates a myriad of essential cellular processes in eukaryotes, such as transcriptional regulation, RNA processing, signal transduction and DNA repair. Arginine methylation is catalyzed by a family of enzymes known as protein arginine methyltransferases (PRMTs). PRMTs are classified as Type I or Type II, depending on the position of the methyl group on the guanidine of the methylated arginine. Previous reports have linked symmetric R methylation to transcriptional repression, while asymmetric R methylation is generally associated with transcriptional activation. However, global studies supporting this conclusion are not available. RESULTS: Here we compared side by side the physiological and molecular roles of the best characterized plant PRMTs, the Type II PRMT5 and the Type I PRMT4, also known as CARM1 in mammals. We found that prmt5 and prmt4a;4b mutants showed similar alterations in flowering time, photomorphogenic responses and salt stress tolerance, while only prmt5 mutants exhibited alterations in circadian rhythms. An RNA-seq analysis revealed that expression and splicing of many differentially regulated genes was similarly enhanced or repressed by PRMT5 and PRMT4s. Furthermore, PRMT5 and PRMT4s co-regulated the expression and splicing of key regulatory genes associated with transcription, RNA processing, responses to light, flowering, and abiotic stress tolerance, being candidates to mediate the physiological alterations observed in the mutants. CONCLUSIONS: Our global analysis indicates that two of the most important Type I and Type II arginine methyltransferases, PRTM4 and PRMT5, have mostly overlapping as well as specific, but not opposite, roles in the global regulation of gene expression in plants.Fil: Hernando, Carlos Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Sanchez, Sabrina Elena. University of Southern California; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Mancini, Estefania. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Yanovsky, Marcelo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentin

    La responsabilidad social empresarial y la visión estratégica en la Gerencia Desarrollo Social de la Municipalidad de San Juan de Lurigancho en el año 2020

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    La Responsabilidad Social Empresarial en la actualidad es un tema que dejo de ser tendencia para convertirse en una necesidad real que constituye el compromiso y la acción social que realizan las organizaciones en favor de la comunidad. En razón a lo mencionado la presente investigación titulada La Responsabilidad social empresarial y la visión estratégica en la Gerencia Desarrollo Social de la Municipalidad de San Juan de Lurigancho en el año 2020, tiene como objetivo principal determinar la correlación que existe entre la responsabilidad social empresarial y la visión estratégica en la Gerencia Desarrollo Social de la Municipalidad de San Juan de Lurigancho. La presente investigación metodológicamente es cuantitativa, de tipo descriptiva y su nivel es correlacional. Para dar cumplimiento al objetivo se planteó como instrumento la encuesta, la cual fue validada por especialista del área, permitiendo el hallazgo de resultados importantes que posteriormente fueron analizados para concluir que existe relación entre la Responsabilidad Social Empresarial y la Visión Estratégica. Esta conclusión puede ayudar de forma responsable a generar en la Municipalidad una Responsabilidad Social Empresarial con Visión Estratégica.Corporate Social Responsibility at present is a topic that is gaining momentum because it constitutes the commitment and social actions that organizations make for the community, for this reason the present research entitled Corporate Social Responsibility and the strategic vision in Development Management Social Development of the Municipality of San Juan de Lurigancho in 2020, it main objective is to determine the correlation that exists between corporate social responsibility as a strategic vision with the Social Development Management of the Municipality of San Juan de Lurigancho in 2020. The present research methodologically is quantitative, descriptive and its level is correlational. To comply with the objective, the survey was proposed as an instrument, which was validated by a specialist in the area, allowing the discovery of important results that were later analyzed to conclude that there is a relationship between Corporate Social Responsibility and the Strategic Vision. This conclusion can help in a responsible way to generate in the Municipality a Corporate Social Responsibility with a Strategic Vision

    Manejo terapéutico del paciente con sospecha de dengue grave ingresado en el Servicio de UCIP del Departamento de Pediatría del Hospital San Juan de Dios de Santa Ana, durante el periodo de junio a noviembre de 2020

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    El dengue, es la enfermedad viral más común y que ocasiona más morbimortalidad a nivel mundial (OMS, 2017)1. Con el pasar de los años, ha aumentado la incidencia, de manera que hoy es considerada como una enfermedad infecciosa emergente y uno de los problemas de salud pública globalmente. De acuerdo a lo que estima la OMS, el número de casos de dengue notificados se ha multiplicado por 8 en las últimas dos décadas, desde 505,430 casos en 2000 a más de 2,4 millones en 2010 y 5,2 millones en 2019 y aproximadamente 4,000 pacientes fallecen cada año (OMS, 2022)
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