963 resultados para variational formulation


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Electricity markets are complex environments with very particular characteristics. MASCEM is a market simulator developed to allow deep studies of the interactions between the players that take part in the electricity market negotiations. This paper presents a new proposal for the definition of MASCEM players’ strategies to negotiate in the market. The proposed methodology is multiagent based, using reinforcement learning algorithms to provide players with the capabilities to perceive the changes in the environment, while adapting their bids formulation according to their needs, using a set of different techniques that are at their disposal.

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We perform a comparison between the fractional iteration and decomposition methods applied to the wave equation on Cantor set. The operators are taken in the local sense. The results illustrate the significant features of the two methods which are both very effective and straightforward for solving the differential equations with local fractional derivative.

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Resource constraints are becoming a problem as many of the wireless mobile devices have increased generality. Our work tries to address this growing demand on resources and performance, by proposing the dynamic selection of neighbor nodes for cooperative service execution. This selection is in uenced by user's quality of service requirements expressed in his request, tailoring provided service to user's speci c needs. In this paper we improve our proposal's formulation algorithm with the ability to trade o time for the quality of the solution. At any given time, a complete solution for service execution exists, and the quality of that solution is expected to improve overtime.

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The minimization of the power loss and the use of the biodegradable greases have attracting considerable attention. To compare the energetic performance of biodegradable lubricant greases, power loss tests were performed on a modified four-ball machine. A correlation between the grease formulation and rheology was established with its energetic performance

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This work provides an assessment of layerwise mixed models using least-squares formulation for the coupled electromechanical static analysis of multilayered plates. In agreement with three-dimensional (3D) exact solutions, due to compatibility and equilibrium conditions at the layers interfaces, certain mechanical and electrical variables must fulfill interlaminar C-0 continuity, namely: displacements, in-plane strains, transverse stresses, electric potential, in-plane electric field components and transverse electric displacement (if no potential is imposed between layers). Hence, two layerwise mixed least-squares models are here investigated, with two different sets of chosen independent variables: Model A, developed earlier, fulfills a priori the interiaminar C-0 continuity of all those aforementioned variables, taken as independent variables; Model B, here newly developed, rather reduces the number of independent variables, but also fulfills a priori the interlaminar C-0 continuity of displacements, transverse stresses, electric potential and transverse electric displacement, taken as independent variables. The predictive capabilities of both models are assessed by comparison with 3D exact solutions, considering multilayered piezoelectric composite plates of different aspect ratios, under an applied transverse load or surface potential. It is shown that both models are able to predict an accurate quasi-3D description of the static electromechanical analysis of multilayered plates for all aspect ratios.

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The local fractional Poisson equations in two independent variables that appear in mathematical physics involving the local fractional derivatives are investigated in this paper. The approximate solutions with the nondifferentiable functions are obtained by using the local fractional variational iteration method.

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The local fractional Poisson equations in two independent variables that appear in mathematical physics involving the local fractional derivatives are investigated in this paper. The approximate solutions with the nondifferentiable functions are obtained by using the local fractional variational iteration method.

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Context: Inclusion of antioxidants in topical formulations can contribute to minimize oxidative stress in the skin, which has been associated with photoaging, several dermatosis and cancer. Objective: A Castanea sativa leaf extract with established antioxidant activity was incorporated into a semisolid surfactant-free formulation. The objective of this study was to perform a comprehensive characterization of this formulation. Materials and methods: Physical, microbiological and functional stability were evaluated during 6 months storage at 20 °C and 40 °C. Microstructure elucidation (cryo-SEM), in vitro release and in vivo moisturizing effect (Corneometer® CM 825) were also assessed. Results and discussion: Minor changes were observed in the textural and rheological properties of the formulation when stored at 20 °C for 6 months and the antioxidant activity of the plant extract remained constant throughout the storage period. Microbiological quality was confirmed at the end of the study. Under accelerated conditions, higher modifications of the evaluated parameters were observed. Cryo-SEM analysis revealed the presence of oil droplets dispersed into a gelified external phase. The release rate of the antioxidant compounds (610 ± 70 µgh−0.5) followed Higuchi model. A significant in vivo moisturizing effect was demonstrated, that lasted at least 4 h after product’s application. Conclusion: The physical, functional and microbiological stability of the antioxidant formulation was established. Specific storage conditions should be recommended considering the influence of temperature on the stability. A skin hydration effect and good skin tolerance were also found which suggests that this preparation can be useful in the prevention or treatment of oxidative stress-mediated dysfunctions.

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INTRODUCTION: Use of a Bacillus sphaericus based mosquito larvicide was evaluated as an intervention for malaria vector control at a mining site in Amapá, Brazil. Impacts on larval and adult densities of the primary vector Anopheles darlingi were measured over the course of a 52 week study period.METHODS: In Calçoene, State of Amapá, gold mining activity occurs in 19 mining sites in gold-miners of Lourenço. Large pools are formed in mining sites and naturally colonized by Anopheles darlingi. During one year, the impact of applications of VectoLex(r) CG to these larval sources was evaluated. Applications of 20kg/ha were made as needed, based on 10 immature (3rd, 4th instars and pupae) surveillance of health and established thresholds. RESULTS: One hundred percent initial control was observed 48h after each treatment. The pools received from 2-10 (5.3±1.6) treatments during the year. The average re-treatment interval in productive pools was 9.4±4.3 weeks. During weeks 3-52 of the study, mean density of late stage larvae was 78% and pupae were 93% lower in the treated pools than in untreated pools (p< 0.0001, n=51) while reduction of adult mosquitoes was 53% in comparison to the untreated area during the last five months of the study, which were the rainy season (p<0.001).CONCLUSIONS:VectoLex(r) CG reduced immature Anopheles darlingi infestation levels during the entire study period, and reduced adult mosquito populations during the rainy season.

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Introduction Although the initiation of highly active antiretroviral therapy (HAART) is accompanied by an attenuation of viral load, metabolic disorders characterized by hyperglycemia, dyslipidemia, and lipodystrophy are often observed in patients under this treatment. Certain foods, such as oat bran, soy protein, and flaxseed, have been shown to improve a patient's lipid profile despite possible increases in uricemia. Thus, a bioactive compound was formulated using these foods to help patients with HIV/AIDS control metabolic disorders resulting from HAART. Methods An uncontrolled before and after study was performed. The total cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides, and uric acid before and after 3 months of consuming the formulation were compared in patients. The compound was formulated such that 40g (the recommended daily intake) contained approximately 10g of flaxseed, 20g of oat bran, and 10g of textured soy protein. Results The study population consisted of 139 patients, 31 of whom were included in the final analysis. There were no significant variations between the laboratory results obtained before and after consumption of the compound. Conclusions The regular consumption of the formulation together with individualized dietary guidance did not reduce lipid levels and did not contribute to an increase in uricemia in the study group. However, new studies with higher doses of the foods that compose the formulation should be encouraged to investigate whether these foods can positively influence the lipid profiles of these patients.

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RESUMO: Santa Lúcia pequena ilha de país em desenvolvimento com recursos limitados e é confrontada com uma série de desafios socioeconômicos que exigem soluções criativas e inovadoras. É comprovado que a combinação de recursos entre setores para estabelecer os determinantes social, econômico e ambiental da saúde são uma estratégia útil para melhorar a saúde da população, principalmente a sua saúde mental. Este estudo, o primeiro do seu tipo em Santa Lúcia, procurou examinar até que ponto a disponibilidade de uma política nacional de saúde mental levou a ação intersetorial para o fornecimento de serviços e promoção da saúde mental. Além disso, o estudo examinou o nível de colaboração intersetorial que existe entre as agências que prestam cuidados diretos e serviços de suporte para pessoas com doenças mentais e problemas sérios de saúde mental. O estudo também teve como objetivo identificar os fatores que promovem ou dificultam a colaboração intersectorial e gerar recomendações que possam ser aplicadas para países muito pequenos e com perfis socioeconômicos semelhantes. Os dados gerados a partir de três (3) fontes foram sintetizados para formar uma visão ampla das questões. Uma avaliação da política de saúde mental de 2007, uma avaliação que identifica até que ponto a ação intersetorial atualmente deixa a prestação de serviços de saúde mental e a administração de entrevistas semiestruturadas nas mãos de gestores do programa de diferentes agências em todos os setores. O estudo concluiu que, apesar da disponibilidade de uma política de saúde mental, que articula clara e explicitamente a colaboração intersetorial como área prioritária para ação, quase não existe no sistema de fornecimento atual do serviço. Os provedores de serviços em todos os setores reconhecem que há os benefícios da colaboração intersectorial e com entraves significativos em relação à colaboração intersetorial, que por sua vez, impede uma abordagem nacional para o planejamento e o fornecimento do serviço. A colaboração intersetorial não será possível se os próprios setores dependerem da abordagem direta do setor da saúde ou se a atmosfera geral for ofuscada pela estigmatização das doenças mentais.------------------------------------------------------------------------ABSTRACT: Saint Lucia a small island developing country with limited resources, is faced with a number of socio-economic challenges which require creative and innovative solutions to address. Combining resources across sectors to address the social, economic and environmental determinants of health has proven to be a useful strategy for improving population health in particular mental health. This study, the first of its kind for Saint Lucia sought to examine the extent to which the availability of a national mental health policy led to intersectoral action for mental health promotion and service delivery. In addition the study examined the level of intersectoral collaboration which actually exist between agencies which provide direct care and support services to people with mental illnesses and significant mental health problems. The study also aimed to identify the factors which promote or hinder intersectoral collaboration and generate recommendations which can be applied to extremely small countries with similar socio-economic profiles. Data generated from three (3) sources was synthesized to form a broad picture of the issues. An evaluation of the mental health policy of 2007, an assessment of the extent to which intersectoral action currently exist in mental health service delivery and the administration of semi-structured interviews with program managers from different agencies across sectors to identify implementation issues. The study concluded that despite the availability of a mental health policy which clearly and explicitly articulates intersectoral collaboration as a priority area for action, very little exists in the current service delivery system. Services providers across sectors acknowledge the benefits of intersectoral collaboration and that there are significant barriers to intersectoral collaboration, which in turn hinders a national approach to service planning and delivery. Intersectoral collaboration is not possible if sectors themselves are dependent on a top-down health sector driven and dominated approach, or if the general atmosphere is clouded by stigmatization of mental health illnesses.

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The effect of α-amylase degradation on the release of gentamicin from starch-conjugated chitosan microparticles was investigated up to 60 days. Scanning electron microscopic observations showed an increase in the porosity and surface roughness of the microparticles as well as reduced diameters. This was confirmed by 67% weight loss of the microparticles in the presence of α-amylase. Over time, a highly porous matrix was obtained leading to increased permeability and increased water uptake with possible diffusion of gentamicin. Indeed, a faster release of gentamicin was observed with α-amylase. Starch-conjugated chitosan particles are non-toxic and highly biocompatible for an osteoblast (SaOs-2) and fibroblast (L929) cell line as well as adipose-derived stem cells. When differently produced starch-conjugated chitosan particles were tested, their cytotoxic effect on SaOs-2 cells was found to be dependent on the crosslinking agent and on the amount of starch used.

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"Series: Solid mechanics and its applications, vol. 226"

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We study the existence theory for parabolic variational inequalities in weighted L2 spaces with respect to excessive measures associated with a transition semigroup. We characterize the value function of optimal stopping problems for finite and infinite dimensional diffusions as a generalized solution of such a variational inequality. The weighted L2 setting allows us to cover some singular cases, such as optimal stopping for stochastic equations with degenerate diffusion coeficient. As an application of the theory, we consider the pricing of American-style contingent claims. Among others, we treat the cases of assets with stochastic volatility and with path-dependent payoffs.