3,023 research outputs found

    Discrete Formulation for the dynamics of rods deforming in space

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    We describe the main ingredients needed to create, from the smooth lagrangian density, a variational principle for discrete motions of a discrete rod, with corresponding conserved Noether currents. We describe all geometrical objects in terms of elements on the linear Atiyah bundle, using a reduced forward difference operator. We show how this introduces a discrete lagrangian density that models the discrete dynamics of a discrete rod. The presented tools are general enough to represent a discretization of any variational theory in principal bundles, and its simplicity allows to perform an iterative integration algorithm to compute the discrete rod evolution in time, starting from any predefined configurations of all discrete rod elements at initial times

    Stability of Affine G-varieties and Irreducibility in Reductive Groups

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    Let GG be a reductive affine algebraic group, and let XX be an affine algebraic GG-variety. We establish a (poly)stability criterion for points xXx\in X in terms of intrinsically defined closed subgroups HxH_{x} of GG, and relate it with the numerical criterion of Mumford, and with Richardson and Bate-Martin-R\"ohrle criteria, in the case X=GNX=G^{N}. Our criterion builds on a close analogue of a theorem of Mundet and Schmitt on polystability and allows the generalization to the algebraic group setting of results of Johnson-Millson and Sikora about complex representation varieties of finitely presented groups. By well established results, it also provides a restatement of the non-abelian Hodge theorem in terms of stability notions.Comment: 29 pages. To appear in Int. J. Math. Note: this version 4 is identical with version 2 (version 3 is empty

    Enseñanza de la geometría en segundo año de educación secundaria bajo el enfoque de competencias

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    The article reports an investigation carried out at Cristóbal Colón National Institute during the second semester of the year 2009, city of Bluefields, Nicaragua and properly it was followed the just implemented teaching process of the flat geometry taught in the second year under the competence approach. The study focused on: a) the teaching methodologies of mathematics teachers in the development of flat geometry contents for the second year, the competency approach implemented, and b) the way in which they contribute to the learning that students acquire from geometry. In this paper, it was analyzed the problems in the teaching process of mathematics, especially the second year flat geometry. From a sample of 112 students, it is revealed that students have little knowledge of the geometry contents of their level, through the interviews it was discovered that the mathematics teachers did not manage to teach all the geometry contents proposed in the study program and deficiencies in the competency approach that is being developed in all the schools of the country. The theoretical framework is related to various teaching theories prioritizing those related to mathematics and geometry; similarly, the competency-based approach on which the methodological proposal that was developed is defined in order to respond to the problems detected during the course of the investigation.El artículo reporta una investigación realizada en el Instituto Nacional Cristóbal Colón durante el segundo semestre del año 2009, ciudad de Bluefields, Nicaragua ypropiamente se le dio seguimiento al proceso de enseñanza de la geometría plana impartida en segundo año bajo el enfoque por competencias, recién implementado.El estudio se centró en: a) las metodologías de enseñanza de los docentes de matemáticas en el desarrollo de los contenidos de geometría plana de segundo año,implementado el enfoque por competencias y b) la manera en que estas contribuyen al aprendizaje que adquieren los estudiantes de geometría.En este trabajo se hacen análisis sobre problemas en el proceso enseñanza de la matemática, en especial de la geometría plana de segundo año, de una muestra de 112estudiantes se revela que los estudiantes tienen poco conocimiento de los contenidos de geometría de su nivel, mediante las entrevistas se descubrió que los docentes dematemáticas no lograron impartir todos los contenidos de geometría planteados en el programa de estudio y deficiencias en el enfoque por competencia que se estádesarrollando en todas las escuelas del país. El marco teórico se encuentra referido a diversas teorías de enseñanzas priorizando las referidas a la matemática y la geometría; así mismo en él se encuentra definido el enfoque por competencia en el cual se basa la propuesta metodológica que se elaboró, para dar repuesta a los problemas detectados en transcurso de la investigación.&nbsp

    Splenomegaly impacts prognosis in essential thrombocythemia and polycythemia vera: A single center study

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    Splenomegaly is one of the major clinical manifestations of primary myelofibrosis and is common also in other chronic Philadelphia-negative myeloproliferative neoplasms, causing symptoms and signs and affecting quality of life of patients diagnosed with these diseases. We aimed to study the impact that such alteration has on thrombotic risk and on the survival of patients with essential thrombocythemia and patients with Polycythemia Vera (PV). We studied the relationship between splenomegaly (and its grade), thrombosis and survival in 238 patients with et and 165 patients with PV followed at our center between January 1997 and May 2019

    The Safe-Port project: an approach to port surveillance and protection

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    SAFE-PORT is a recently started project addressing the complex issue of determining the best configurations of resources for harbour and port surveillance and protection. More specifically, the main goal is to find, for any given scenario, an adequate set of configuration solutions — i.e., number and type of sensors and equipments, their locations and operating modes, the corresponding personnel and other support resources — that maximize protection over a specific area. The project includes research and development of sensors models, novel algorithms for optimization and decision support, and a computer-based decision support system (DSS) to assist decision makers in that task. It includes also the development of a simulation environment for modelling relevant aspects of the scenario (including sensors used for surveillance, platforms, threats and the environment), capable to incorporate data from field-trials, used to test and validate solutions proposed by the DSS. Test cases will consider the use of intelligent agents to model the behaviour of threats and of NATO forces in a realistic way, following experts’ definitions and parameters

    Enhancing trans-resveratrol topical delivery and photostability through entrapment in chitosan/gum Arabic Pickering emulsions

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    The surfactant-free nature and higher stability of Pickering emulsions make them preferable solutions over conventional emulsions for skin applications. In this work, Pickering emulsions stabilized by chitosan/gum Arabic (CH/GA) nanoparticles were tested as vehicles for trans-resveratrol topical delivery. Skin absorption was examined ex vivo using Franz diffusion cells and porcine skin. Pickering emulsions allowed higher cutaneous retention and lower permeation of resveratrol, in comparison with a control solution based on a 20% v/v ethanol. The total amount of resveratrol retained in the skin, 24 h after the application, was 11.60% and 10.82% of the applied dose for the tested Pickering emulsion-based formulations prepared with 0.5% and 1.5%w/v CH/GA nanoparticles, respectively. In contrast, resveratrol skin retention from the control solution was only 2.86%. Confocal laser scanning microscopy revealed enhanced skin deposition of Nile Red to deeper layers from the Pickering emulsionbased formulations. Moreover, Pickering emulsions led to trans-resveratrol photostability increase, as measured after exposure to UV for 4 h. These results show that the CH/GA Pickering emulsions are promising solutions for the topical delivery of trans-resveratrol and have the potential to be used as green cosmetic products.This work was supported by Associate Laboratory LSRE-LCM - UID/ EQU/50020/2019 - funded by national funds through FCT/MCTES (PIDDAC), and Foundation for Science and Technology (FCT, Portugal); and CIMO (UID/AGR/00690/2019) through FEDER under Program PT2020. The authors acknowledge the technical support provided by the Instituto de Investigação e Inovação (i3s) and CEMUP, University of Porto. The authors are thankful to Dr. Patricia Costa for providing the skin samples, and Tasneem Sharkawi for language editing. Asma Sharkawy acknowledges the financial support from the FCT doctoral grant (PD/BD/135085/2017).info:eu-repo/semantics/publishedVersio

    Measurement of the Total Factor Productivity of Spanish Agriculture: 1962-1989

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    Pediatrician-Parents Communication: What we Tell and How we Tell it, is it Enough?

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    Introdução: Durante um internamento podem ser necessários procedimentos diagnósticos e terapêuticos, e as crianças e os pais contactam com vários profissionais de saúde. Será que as informações fornecidas pelos médicos são suficientes e claras? Objectivos: Avaliar a opinião dos pais relativamente às informações fornecidas pelos médicos e a influência que podem ter factores socioeconómicos e culturais na compreensão destas informações. Métodos: Recolheram-se dados demográficos e avaliou-se o grau de conhecimento sobre o diagnóstico, exames e tratamentos, data da alta, nome do médico assistente e opinião quanto à clareza e frequência das informações. Resultados: Considerámos 300 entrevistas. A maioria dos pais tinha uma correcta percepção sobre o diagnóstico(74,8%), tratamento (70,3%) e exames realizados (78,0%), mas apenas 18,7% sabiam a data provável da alta. Em 65,0% dos casos as informações tinham sido fornecidas pelo médico responsável e a maioria considerou a informação clara(87,0%) e suficiente (81,0%). Em serviços de Cirurgia registou-se uma melhor informação relativamente ao diagnóstico (80,4% vs 69,9%, p=0,042) e nome do médico responsável (70,6% vs 55,5%, p=0,008). Os entrevistados com maior escolaridade conheciam melhor o médico (70,4% vs 56,6%, p=0,016) e os tratamentos efectuados às crianças (79,6% vs 69,8%, p<0,001). Os pais de nacionalidade portuguesa e de meio socioeconómico mais elevado conheciam melhor o diagnóstico (79,7% vs 61,8%, p=0,004), (80,7% vs 65,7%, p=0,007) e tratamento (76,3% vs 50,0%, p<0,001), (81,3% vs 49,0%, p=<0,001). Adicionalmente, o grupo socialmente mais diferenciado conhecia melhor o médico responsável (55,9% vs 67,7%, p=0,050). Quando as informações eram transmitidas pelo médico responsável os entrevistados consideravam-nas mais claras (92,3% vs 81,1%, p=0,001) e suficientes (89,7% vs 64,2%, p<0,001).Conclusão: Este estudo identifica a importância do médico assistente na comunicação com os pais das crianças e a necessidade de adequar a informação ao nível sociocultural da família ao longo do internamento

    A proof-of-concept

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    Funding Information: C. Costa, T. Casimiro and A. Aguiar-Ricardo are grateful for the financial support of the Associate Laboratory for Green Chemistry-LAQV, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa , Portugal, which is financed by national funds from FCT/MCTES ( UIDB/50006/2020 and UIDP/50006/2020 ). C. Costa thanks FCT (Fundação para a Ciência e Tecnologia) and ESF (European Social Fund) through POCH (Programa Operacional Capital Humano) for her PhD grant ref. PD/BD/142880/2018, COVID/BD/152744/2022 and Project PD/00184/2012-PDQS . C. Costa and A. Aguiar-Ricardo acknowledge also CA18224 GREENERING (“Green Chemical Engineering Network towards upscaling sustainable processes”). COST Actions are funded within the EU Horizon 2020 Programme . M.L. Corvo is grateful for the financial support of the Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa , Lisbon, Portugal, which is supported in part by UID/DTP/04138/2020 and UIDP/04138/2020 from FCT/MCTES , Portugal. The authors are grateful to Prof. M. Dionísio for the DSC facility. Publisher Copyright: © 2023Enzyme-based inhalable therapeutics for lung inflammation are gaining interest as an alternative to long-term corticosteroids treatments. However, enzymes have poor pharmacokinetics. Encapsulating enzymes in liposomes can increase their half-live and modify their biodistribution. But both liposomes and enzymes are susceptible to destabilization during storage. This drawback can be surpassed, by converting liposomal suspension into solid dosage forms for different administration routes, including inhalation. In this study, Cu, Zn- superoxide dismutase (SOD) was encapsulated in liposomes, then dried using supercritical CO2-assisted spray-drying to make SOD-loaded liposomal dry powder formulations (SOD_Lip-DPFs). Upon resuspension in water, liposomes maintained structural integrity, with 99% SOD encapsulation efficiency and preserved enzymatic activity. Stability studies showed that SOD_Lip-DPFs maintained liposomal and enzyme stability for 50 days at 40% relative humidity. This offers a stable and efficient delivery system for enzyme-based inhalable therapeutics.publishersversionpublishe

    Distal Renal Tubular Acidosis and Sensorineural Deafness with Mutation in the ATP6V1B1 Gene

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    A acidose tubular renal distal é uma doença rara, caracterizada pela incapacidade na acidificação da urina, condicionando acidose metabólica hiperclorémica, hipocaliémia, hipercalciúria e nefrocalcinose, o que poderá causar atraso de crescimento, alteração do metabolismo ósseo e insuficiência renal crónica. A acidose tubular renal distal associada a surdez neurossensorial é uma doença de herança autossómica recessiva, causada por mutações do gene que codifica a subunidade B1 da H+ -ATPase (ATP6V1B1). Os autores relatam os casos de duas irmãs que apresentaram má progressão ponderal, alterações iónicas, do equilíbrio ácido base e surdez neurossensorial. Foi detectada em ambas as crianças a mutação homozigótica no gene ATP6V1B1. Com estes dois casos pretende -se destacar a importância de um diagnóstico precoce nesta patologia rara
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