3,265 research outputs found

    The good, the bad and the ugly: three faces of social media usage by local governments

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    This article explores the determinants of local governments' use of social networking sites. It does so by analysing the relative impact of institutional, political and social determinants, while controlling for the impact of mayors' traits and social characteristics of municipalities on local governments levels of activity on Facebook. Empirically, this article presents a within-case analysis of Portuguese municipalities' activity on social media, aiming to shed light on the strategic use of social media by local governments. A coherent picture associated with politically pro-active local governments emerges from the results: higher levels of social media activity appear in municipalities with more competitive local elections and higher commitment to transparency. Moreover, findings suggest that local governments tend to be concerned with the low levels of voter turnout, potentially resorting to social media as a powerful tool to increase civic engagement and (offline) political participation. Levels of Facebook activity are significantly higher in larger and wealthier municipalities. The results indicate that Facebook official pages of municipalities are part of a larger arsenal of tools to promote political engagement and activity levels signal a propensity to involve citizens pro-actively.This research received funding from the project “SmartEGOV: Harnessing EGOV for Smart Governance (Foundations, methods, Tools)/NORTE-01-0145-FEDER-000037”, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (EFDR) and from the Portuguese Foundation for Science and Technology and the Portuguese Ministry of Education and Science through national funds [Grant No. UID/CPO/0758/2019]

    Estado del sistema sociedad-naturaleza en el chaco argentino

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    La planificación y gestión de las actividades productivas y de protección de los servicios ecosistémicos requiere el conocimiento de las interacciones múltiples que determinan la dinámica del sistema sociedad-naturaleza. No resulta efectivo el manejo de las tierras desde la ecología, ni desde la sociología aisladamente, sino desde la comprensión del funcionamiento del sistema integrado, estudiado mediante un enfoque transdisciplinario que permita entender las asociaciones entre los factores sociales y físico-bióticos en cada jurisdicción política, especialmente en regiones tan heterogéneas como la chaqueña. En este trabajo se presentan los resultados del análisis integrado de conjuntos de datos ecológicos, del soporte físico de la producción, de producción agropecuaria y de variables sociales en 43 departamentos de la región chaqueña central, abarcando parte de las ecorregiones Chaco Seco y Chaco Húmedo. Se empleó el análisis de Procrustes Generalizado, el cual permite evaluar la consistencia entre conjunto de variables, partiendo de la hipótesis de que los cambios de uso de la tierra general situaciones de inestabilidad que afectan negativamente la resiliencia de los sistemas sociedad-naturaleza, con la consiguiente pérdida de sustentabilidad, y que este efecto se percibe a través de la consistencia entre los factores de los cuales depende la resiliencia. La predicción es que una asociación débil entre el soporte físico y el uso de la tierra implica un uso inadecuado de los recursos naturales que se reflejará en las condiciones sociales de los habitantes de la región. Los resultados muestran que la predicción se cumple en algunos de los departamentos pero no en otros. Se presentaron cuatro combinaciones posibles de concordancia entre soporte físico de la producción y uso de la tierra y su consecuencia sobre las condiciones sociales. El uso de la tierra se refleja en las condiciones sociales tanto como bienestar de la sociedad por un uso de la tierra consistente con su aptitud o como condiciones sociales adversas por un uso de la tierra no consistente con la aptitud natural de la tierra. Las otras dos combinaciones implican condiciones sociales adversas con uso adecuado de la tierra y condiciones de bienestar con un uso inadecuado de la tierra. En estos dos casos, el uso de la tierra no se refleja en las condiciones sociales. Se discuten las posibles razones de estos resultados y las consecuencias para la planificación y manejo de la tierra. La información producida será útil para el ordenamiento territorial.Fil: Matteucci, Silvia Diana. Universidad de Buenos Aires. Facultad de Arquitectura y Urbanismo. Grupo de Ecología del Paisaje y Medio Ambiente; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Silva, Mariana Elizabeth. Universidad de Buenos Aires. Facultad de Arquitectura y Urbanismo. Grupo de Ecología del Paisaje y Medio Ambiente; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rodriguez, Andrea F.. Universidad de Buenos Aires. Facultad de Arquitectura y Urbanismo. Grupo de Ecología del Paisaje y Medio Ambiente; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

    Tensile behaviour of a structural adhesive at high temperatures by the extended finite element method

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    Component joining is typically performed by welding, fastening, or adhesive-bonding. For bonded aerospace applications, adhesives must withstand high-temperatures (200°C or above, depending on the application), which implies their mechanical characterization under identical conditions. The extended finite element method (XFEM) is an enhancement of the finite element method (FEM) that can be used for the strength prediction of bonded structures. This work proposes and validates damage laws for a thin layer of an epoxy adhesive at room temperature (RT), 100, 150, and 200°C using the XFEM. The fracture toughness (G Ic ) and maximum load ( ); in pure tensile loading were defined by testing double-cantilever beam (DCB) and bulk tensile specimens, respectively, which permitted building the damage laws for each temperature. The bulk test results revealed that decreased gradually with the temperature. On the other hand, the value of G Ic of the adhesive, extracted from the DCB data, was shown to be relatively insensitive to temperature up to the glass transition temperature (T g ), while above T g (at 200°C) a great reduction took place. The output of the DCB numerical simulations for the various temperatures showed a good agreement with the experimental results, which validated the obtained data for strength prediction of bonded joints in tension. By the obtained results, the XFEM proved to be an alternative for the accurate strength prediction of bonded structures

    A Study on Microstructure Characteristics of TEPs-modified Adhesives

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    Thermally expandable particles (TEPs) were developed by Dow Chemical Co in the early 1970´s [1] and were further developed by others [2, 3]. They are particles made up of a thermoplastic shell filled with liquid hydrocarbon. On heating them, two transformations will occur. One is the softening of shell material and the other is the gasification of the hydrocarbon liquid inside it. As a consequence, the shell will expand as the gas inside it will push the softened shell from inside out causing it to grow in size [4]. When fully expanded, the growth in volume of the particle can be from 50 to 100 times [3]. Owing to this unique behaviour, TEPs are used by the industry in a wide variety of applications mainly for weight reduction and appearance improvement for thermoplastics, inks, and coatings. In adhesive bonding, TEPs have been used for recycling purposes. Moreover, TEPs might be used to modify structural adhesives for other new purposes, such as: to increase the joint strength by creating an adhesive functionally modified along the overlap of the joint by gradual heating and/or to heal the adhesive in case of damage

    Strength improvement of adhesively-bonded joints using a reverse-bent geometry

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    Adhesive bonding of components has become more efficient in recent years due to the developments in adhesive technology, which has resulted in higher peel and shear strengths, and also in allowable ductility up to failure. As a result, fastening and riveting methods are being progressively replaced by adhesive bonding, allowing a big step towards stronger and lighter unions. However, single-lap bonded joints still generate substantial peel and shear stress concentrations at the overlap edges that can be harmful to the structure, especially when using brittle adhesives that do not allow plasticization in these regions. In this work, a numerical and experimental study is performed to evaluate the feasibility of bending the adherends at the ends of the overlap for the strength improvement of single-lap aluminium joints bonded with a brittle and a ductile adhesive. Different combinations of joint eccentricity were tested, including absence of eccentricity, allowing the optimization of the joint. A Finite Element stress and failure analysis in ABAQUS® was also carried out to provide a better understanding of the bent configuration. Results showed a major advantage of using the proposed modification for the brittle adhesive, but the joints with the ductile adhesive were not much affected by the bending technique

    Polyphenol metabolite pyrogallol-o-sulfate decreases microglial activation and vegf in retinal pigment epithelium cells and diabetic mouse retina

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    Funding Information: The authors acknowledge Fundacao para a Ciencia e Tecnologia for funding (PD/BD/114251/2016 scholarship to D.F. Santos; EXPL-BIM-MEC-1433-2013; PTDC/BTM/ORG/28121/2017 grants to G.A.Silva) and iNOVA4Health ? UIDB/Multi/04462/2020, a program financially supported by Funda??o para a Ci?ncia e Tecnologia/Ministerio da Educacao e Ciencia through national funds and co-funded by FEDER under the PT2020 Partnership Agreement, is also acknowledged. C.N.S. also acknowledges the European Research Council (ERC) under the European Union?s Horizon 2020 Research and Innovation Programme under Grant Agreement No. 804229. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.(Poly)phenol-derived metabolites are small molecules resulting from (poly)phenol metab-olization after ingestion that can be found in circulation. In the last decade, studies on the impact of (poly)phenol properties in health and cellular metabolism accumulated evidence that (poly)phenols are beneficial against human diseases. Diabetic retinopathy (DR) is characterized by inflammation and neovascularization and targeting these is of therapeutic interest. We aimed to study the effect of pyrogallol-O-sulfate (Pyr-s) metabolite in the expression of proteins involved in retinal glial acti-vation, neovascularization, and glucose transport. The expression of PEDF, VEGF, and GLUT-1 were analyzed upon pyrogallol-O-sulfate treatment in RPE cells under high glucose and hypoxia. To test its effect on a diabetic mouse model, Ins2Akita mice were subjected to a single intraocular injection of the metabolite and the expression of PEDF, VEGF, GLUT-1, Iba1, or GFAP measured in the neural retina and/or retinal pigment epithelium (RPE), two weeks after treatment. We observed a significant decrease in the expression of pro-angiogenic VEGF in RPE cells. Moreover, pyrogallol-O-sulfate significantly decreased the expression of microglial marker Iba1 in the diabetic retina at different stages of disease progression. These results highlight the potential pyrogallol-O-sulfate metabolite as a preventive approach towards DR progression, targeting molecules involved in both inflammation and neovascularization.publishersversionpublishe

    Modelling adhesive joints with cohesive zone models: effect of the cohesive law shape of the adhesive layer

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    Adhesively-bonded joints are extensively used in several fields of engineering. Cohesive Zone Models (CZM) have been used for the strength prediction of adhesive joints, as an add-in to Finite Element (FE) analyses that allows simulation of damage growth, by consideration of energetic principles. A useful feature of CZM is that different shapes can be developed for the cohesive laws, depending on the nature of the material or interface to be simulated, allowing an accurate strength prediction. This work studies the influence of the CZM shape (triangular, exponential or trapezoidal) used to model a thin adhesive layer in single-lap adhesive joints, for an estimation of its influence on the strength prediction under different material conditions. By performing this study, guidelines are provided on the possibility to use a CZM shape that may not be the most suited for a particular adhesive, but that may be more straightforward to use/implement and have less convergence problems (e.g. triangular shaped CZM), thus attaining the solution faster. The overall results showed that joints bonded with ductile adhesives are highly influenced by the CZM shape, and that the trapezoidal shape fits best the experimental data. Moreover, the smaller is the overlap length (LO), the greater is the influence of the CZM shape. On the other hand, the influence of the CZM shape can be neglected when using brittle adhesives, without compromising too much the accuracy of the strength predictions

    RNA-seq – Revealing Biological Insights in Bacteria

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    New technologies are constantly being released and the improvements therein bring advances not only to transcriptome, the focus of this chapter, but also to diverse areas of biological research. Since the announcement and application of the RNA-seq approach, discoveries are being made in this field, but when we consider bacterial species, this progress proceeded a few years behind. However, with the application of RNA-seq derivative approaches, we can gain biological insights into the bacterial world and aspire to uncover the mysteries involving gene expression, organization and other functional genomic features

    Adherend thickness effect on the tensile fracture toughness of a structural adhesive using an optical data acquisition method

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    Adhesive bonding is nowadays a serious candidate to replace methods such as fastening or riveting, because of attractive mechanical properties. As a result, adhesives are being increasingly used in industries such as the automotive, aerospace and construction. Thus, it is highly important to predict the strength of bonded joints to assess the feasibility of joining during the fabrication process of components (e.g. due to complex geometries) or for repairing purposes. This work studies the tensile behaviour of adhesive joints between aluminium adherends considering different values of adherend thickness (h) and the double-cantilever beam (DCB) test. The experimental work consists of the definition of the tensile fracture toughness (GIC) for the different joint configurations. A conventional fracture characterization method was used, together with a J-integral approach, that take into account the plasticity effects occurring in the adhesive layer. An optical measurement method is used for the evaluation of crack tip opening and adherends rotation at the crack tip during the test, supported by a Matlab® sub-routine for the automated extraction of these quantities. As output of this work, a comparative evaluation between bonded systems with different values of adherend thickness is carried out and complete fracture data is provided in tension for the subsequent strength prediction of joints with identical conditions
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