1,299 research outputs found

    A benchmark study on identification of inelastic parameters based on deep drawing processes using pso – nelder mead hybrid approach

    Get PDF
    Optimization techniques have been increasingly used to identification of inelastic material parameters owing to their generality. Development of robust techniques to solving this class of inverse problems has been a challenge to researchers mainly due to the nonlinear character of the problem and behaviour of the objective function. Within this framework, this work discusses application of Particle Swarm Optimization (PSO) and a PSO – Nelder Mead hybrid approach to identification of inelastic parameters based on a benchmark solution of the deep drawing process

    Uniform current in graphene strip with zigzag edges

    Full text link
    Graphene exhibits zero-gap massless-Dirac fermion and zero density of states at E = 0. These particles form localized states called edge states on finite width strip with zigzag edges at E = 0. Naively thinking, one may expect that current is also concentrated at the edge, but Zarbo and Nikolic numerically obtained a result that the current density shows maximum at the center of the strip. We derive a rigorous relation for the current density, and clarify the reason why the current density of edge state has a maximum at the center.Comment: 5 pages, 3 figures; added references and corrected typos, to be published in J. Phys. Soc. Jpn. Vol.78 No.

    Measuring engagement on twitter using a composite index: An application to social media influencers

    Get PDF
    El compromiso en las redes sociales es un concepto complejo, en el que interactúan muchos componentes interconectados y difíciles de evaluar. Es precisamente esta complejidad la que motivó este trabajo, que propone un índice compuesto como herramienta para medir el engagement. Utilizando TOPSIS, un método multicriterio que basa su ranking en minimizar la distancia al punto ideal y maximizar la distancia al anti-ideal, se utiliza una combinación de indicadores basados ​​en dos enfoques: el enfoque del tweet y el enfoque del seguidor. El primero refleja el compromiso basado en la producción del usuario y el segundo mide el compromiso por popularidad. Este índice se aplicó a un grupo de Social Media Influencers y se obtuvo un ranking general, así como un ranking por cada enfoque de medición del engagement. La comparación de los rankings generados por los diferentes enfoques muestra la idoneidad y pertinencia de ambos, ya que se confirma que miden aspectos diferentes, y que ambos son necesarios para ofrecer una visión holística del engagement que genera un usuario en Twitter; este es un hallazgo nuevo en comparación con estudios anteriores, que solo se centraron en un enfoque u otro.Funding for open access charge: Universidad de Málag

    Robust Variational Physics-Informed Neural Networks

    Get PDF
    We introduce a Robust version of the Variational Physics-Informed Neural Networks method (RVPINNs). As in VPINNs, we define the quadratic loss functional in terms of a Petrov-Galerkin-type variational formulation of the PDE problem: the trial space is a (Deep) Neural Network (DNN) manifold, while the test space is a finite-dimensional vector space. Whereas the VPINN’s loss depends upon the selected basis functions of a given test space, herein, we minimize a loss based on the discrete dual norm of the residual. The main advantage of such a loss definition is that it provides a reliable and efficient estimator of the true error in the energy norm under the assumption of the existence of a local Fortin operator. We test the performance and robustness of our algorithm in several advection-diffusion problems. These numerical results perfectly align with our theoretical findings, showing that our estimates are sharp

    Chronic Stress Triggers Expression of Immediate Early Genes and Differentially Affects the Expression of AMPA and NMDA Subunits in Dorsal and Ventral Hippocampus of Rats

    Get PDF
    Indexación: Web of Science; Scopus.Previous studies in rats have demonstrated that chronic restraint stress triggers anhedonia, depressive-like behaviors, anxiety and a reduction in dendritic spine density in hippocampal neurons. In this study, we compared the effect of repeated stress on the expression of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptor subunits in dorsal and ventral hippocampus (VH). Adult male Sprague-Dawley rats were randomly divided into control and stressed groups, and were daily restrained in their motion (2.5 h/day) during 14 days. We found that chronic stress promotes an increase in c-Fos mRNA levels in both hippocampal areas, although it was observed a reduction in the immunoreactivity at pyramidal cell layer. Furthermore, Arc mRNAs levels were increased in both dorsal and VH, accompanied by an increase in Arc immunoreactivity in dendritic hippocampal layers. Furthermore, stress triggered a reduction in PSD-95 and NR1 protein levels in whole extract of dorsal and VH. Moreover, a reduction in NR2A/NR2B ratio was observed only in dorsal pole. In synaptosomal fractions, we detected a rise in NR1 in dorsal hippocampus (DH). By indirect immunofluorescence we found that NR1 subunits rise, especially in neuropil areas of dorsal, but not VH. In relation to AMPA receptor (AMPAR) subunits, chronic stress did not trigger any change, either in dorsal or ventral hippocampal areas. These data suggest that DH is more sensitive than VH to chronic stress exposure, mainly altering the expression of NMDA receptor (NMDAR) subunits, and probably favors changes in the configuration of this receptor that may influence the function of this area.https://www.frontiersin.org/articles/10.3389/fnmol.2017.00244/ful

    Catalizador heteropoliácido soportado, procedimiento de obtención y utilización

    Get PDF
    El objeto de la invención son varios catalizadores heteropoliácidos soportados, su procedimiento de obtención y su uso como catalizador ácido en procesos de fase heterogénea, en concreto en la producción de dimetil éter a partir de metanol. Al soportar los catalizadores heteropoliácidos en sólidos inorgánicos mediante la técnica de impregnación se consigue que el área de los heteropoliácidos (muy baja en su forma pura) aumente drásticamente y, por tanto, se favorezcan los procesos catalíticos en fase heterogénea. Este proceso de síntesis no es complicado y es fácilmente escalable. Estos catalizadores son extremadamente activos y selectivos en la producción de dimetil éter a temperaturas sensiblemente inferiores a las de los catalizadores usados en el proceso industrial. La producción de dimetil éter tiene un rendimiento de casi el 100% y la desactivación es muy baja.Peer reviewedConsejo Superior de Investigaciones CientíficasB1 Patente sin examen previ

    HLB: el enfoque fitopatológico: situación del Noroeste Argentino

    Get PDF
    Desde 2004, el Laboratorio de Fitopatología de la EEAOC es Laboratorio Reconocido de la Red del Servicio Nacional de Sanidad y Calidad Agroalimentaria (Senasa) para diagnóstico de Xanthomonas citri subsp. citri (cancrosis de los cítricos) y Guignardia citricarpa (mancha negra de los cítricos). En 2006, se incorpora a este registro el diagnóstico de HLB. Hoy opera, respecto de esta enfermedad, como uno de los laboratorios de referencia de la Red Nacional del Senasa en el marco del Programa Nacional de Prevención del HLB.Fil: Fogliata, Gabriela M.. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentina; ArgentinaFil: Acosta, M. Eugenia. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentina; ArgentinaFil: Martinez, C. Valeria. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentina; ArgentinaFil: Rojas, Alejandro. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentina; ArgentinaFil: Muñoz, M. Lorena. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentina; ArgentinaFil: Ploper, Leonardo Daniel. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentina; Argentin

    MicroRNA Profiling and Bioinformatics Target Analysis in Dorsal Hippocampus of Chronically Stressed Rats: Relevance to Depression Pathophysiology

    Get PDF
    Indexación: Scopus.1Laboratory of Neuroplasticity and Neurogenetics, Faculty of Chemical and Pharmaceutical Sciences, Department of Biochemistry and Molecular Biology, Universidad de Chile, Santiago, Chile, 2National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Durham, NC, United States, 3Centro de Genómica y Bioinformática, Facultad de Ciencias, Universidad Mayor, Santiago, Chile, 4Millennium Institute for Integrative Biology (iBio), FONDAP Center for Genome Regulation, Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Santiago, Chile, 5Department of Kinesiology, Faculty of Health Sciences, Universidad Católica del Maule, Talca, Chile, 6Escuela de Química y Farmacia, Facultad de Medicina, Universidad Andres Bello, Santiago, Chile.This study was supported by the following grants: FONDECYT 1120528 (JLF), Fondo Central de Investigación, Universidad de Chile ENL025/16 (JLF), ES090079 (JAC). Research in RG and EV laboratories is funded by Instituto Milenio iBio – Iniciativa Científica Milenio MINECON.Studies conducted in rodents subjected to chronic stress and some observations in humans after psychosocial stress, have allowed to establish a link between stress and the susceptibility to many complex diseases, including mood disorders. The studies in rodents have revealed that chronic exposure to stress negatively affects synaptic plasticity by triggering changes in the production of trophic factors, subunit levels of glutamate ionotropic receptors, neuron morphology, and neurogenesis in the adult hippocampus. These modifications may account for the impairment in learning and memory processes observed in chronically stressed animals. It is plausible then, that stress modifies the interplay between signal transduction cascades and gene expression regulation in the hippocampus, therefore leading to altered neuroplasticity and functioning of neural circuits. Considering that miRNAs play an important role in post-transcriptional-regulation of gene expression and participate in several hippocampus-dependent functions; we evaluated the consequences of chronic stress on the expression of miRNAs in dorsal (anterior) portion of the hippocampus, which participates in memory formation in rodents. Here, we show that male rats exposed to daily restraint stress (2.5 h/day) during 7 and 14 days display a differential profile of miRNA levels in dorsal hippocampus and remarkably, we found that some of these miRNAs belong to the miR-379-410 cluster. We confirmed a rise in miR-92a and miR-485 levels after 14 days of stress by qPCR, an effect that was not mimicked by chronic administration of corticosterone (14 days). Our in silico study identified the top-10 biological functions influenced by miR-92a, nine of which were shared with miR-485: Nervous system development and function, Tissue development, Behavior, Embryonic development, Organ development, Organismal development, Organismal survival, Tissue morphology, and Organ morphology. Furthermore, our in silico study provided a landscape of potential miRNA-92a and miR-485 targets, along with relevant canonical pathways related to axonal guidance signaling and cAMP signaling, which may influence the functioning of several neuroplastic substrates in dorsal hippocampus. Additionally, the combined effect of miR-92a and miR-485 on transcription factors, along with histone-modifying enzymes, may have a functional relevance by producing changes in gene regulatory networks that modify the neuroplastic capacity of the adult dorsal hippocampus under stress. © 2018 Muñoz-Llanos, García-Pérez, Xu, Tejos-Bravo, Vidal, Moyano, Gutiérrez, Aguayo, Pacheco, García-Rojo, Aliaga, Rojas, Cidlowski and Fiedler.https://www.frontiersin.org/articles/10.3389/fnmol.2018.00251/ful

    Candida tropicalis fungaemia: incidence, risk factors and mortality in a general hospital

    Get PDF
    AbstractThe risk factors and clinical features of patients with Candida tropicalis fungaemia have not been fully defined. We performed a case–control study comparing 59 cases of C. tropicalis fungaemia with 177 episodes of fungaemia caused by other species of Candida in our hospital over a 24-year period (January 1985 to December 2008). Patients with C. tropicalis fungaemia were more likely to be older (median age, 67 vs. 56 years; p 0.01), to have cancer (45.5% vs. 31.6%, p 0.04), and to have the abdomen as the portal of entry (32.2% vs. 11.9%, p 0.001), and had a higher in-hospital mortality rate (61% vs. 44%, p 0.03). Multivariate analysis showed that the independent risk factors for C. tropicalis fungaemia were cancer (OR 4.5; 95% CI 1.05–3.83; p 0.03) and the abdomen as the portal of entry (OR 13.6; 95% CI 1.9–8.2; p <0.001). When survivors were compared with non-survivors, the risk factors associated with a poor outcome were neutropenia (19.4% vs. 0; p 0.03), corticosteroid treatment (36% vs. 13%; p 0.07), and septic shock (50% vs. 17.4%; p 0.01). The independent risk factors for mortality in the multivariate analysis were corticosteroid treatment (OR 8.2; 95% CI 0.9–27.7; p 0.04) and septic shock (OR 14.6; 95% CI 2.4–90.2; p 0.004), whereas urinary tract infection (OR 0.07; 95% CI 0.01–0.8; p 0.03) and catheter removal (OR 0.06; 95% CI 0.01–0.4; p 0.002) were protective factors. C. tropicalis is the fourth most common cause of fungaemia in our hospital. It is associated with underlying malignancy, the abdomen as the portal of entry, and poor outcome

    Soil biodiversity and organic carbon are essential to reverse desertification

    Get PDF
    La biodiversidad y el carbono orgánico del suelo, así como la interacción entre ambos, juegan papeles esenciales en el mantenimiento y regulación de los servicios ecosistémicos de las zonas secas, desde la fertilidad del suelo a la producción de alimentos. El cambio climático y los impactos antrópicos pueden provocar pérdidas en la biodiversidad y carbono del suelo, lo cual puede resultar en alteraciones de los ciclos del carbono y la funcionalidad de los ecosistemas derivando en procesos acelerados de desertificación. Es necesario, por tanto, mejorar nuestro conocimiento sobre la compleja diversidad biológica del suelo, así como su interacción con el carbono orgánico en las zonas secas. Esto nos permitirá diseñar estrategias efectivas para promover el secuestro de carbono en el suelo, contribuyendo así a revertir los procesos de degradación y desertificación. En esta revisión discutimos la importancia de la biodiversidad y el carbono orgánico del suelo de las zonas secas en un contexto de cambio global, definiendo la relación entre ambos y su respuesta a factores climáticos y degradación. También destacamos el uso de herramientas avanzadas tales como la genómica, y practicas relevantes de manejo del suelo que nos permitan incrementar los contenidos de carbono y mejorar la diversidad y funcionalidad de suelo en las zonas secas, con el fin último de prevenir y revertir la desertificación.Soil biodiversity, organic carbon, and their interactions, play critical roles for the maintenance and regulation of ecosystem services in drylands, including soil fertility and food production, among others. Climate change and anthropogenic impacts can result in soil carbon and biodiversity decreases, which can cause alterations of the carbon cycle and the loss of essential ecosystem functions. It is therefore crucial to advance our knowledge on the complex soil biological diversity, and its interactions with the soil organic carbon in drylands. This information will allow us to design effective strategies for carbon sequestration, thus contributing to reverse desertification. In this review, we discuss the importance of the soil biodiversity and organic carbon in drylands in a global change context and underline their interactions and their responses to climate change and degradation. We also highlight the use of novel techniques recently developed, including genomics, and effective soil management practices for promoting soil biodiversity and enhancing soil carbon levels, to ultimately, halt degradation and desertification.Australian Research Council Discovery Early Career Research Award DE180100570Ministerio de Ciencia e Innovación de España PID2020-115813RA-I00Junta de Andalucía P20_00879Hermon Slade Foundation HSF18-
    • …
    corecore