940 resultados para Essential-state models
Resumo:
No estudo das comunidades florestais, estabelecer a importância relativa dos fatores que definem a composição e a distribuição das espécies é um desafio. Em termos de gradientes ambientais o estudo das respostas das espécies arbóreas são essenciais para a compreensão dos processos ecológicos e decisões de conservação. Neste sentido, para contribuir com a elucidação dos processos ecológicos nas principais formações florestais do Estado de São Paulo (Floresta Ombrófila Densa de Terras Baixas, Floresta Ombrófila Densa Submontana, Floresta Estacional Semidecidual e Savana Florestada) este trabalho objetivou responder as seguintes questões: (I) a composição florística e a abundância das espécies arbóreas, em cada unidade fitogeográfica, variam conforme o gradiente edáfico e topográfico?; (II) características do solo e topografia podem influenciar na previsibilidade de ocorrência de espécies arbóreas de ampla distribuição em diferentes tipos vegetacionais? (III) existe relação entre o padrão de distribuição espacial de espécies arbóreas e os parâmetros do solo e topografia? O trabalho foi realizado em parcelas alocadas em unidades de conservação (UC) que apresentaram trechos representativos, em termos de conservação e tamanho, das quatro principais formações florestais presentes no Estado de São Paulo. Em cada UC foram contabilizados os indivíduos arbóreos (CAP ≥ 15 cm), topografia, dados de textura e atributos químicos dos solos em uma parcela de 10,24 ha, subdividida em 256 subparcelas. Análises de correspodência canônica foram aplicadas para estabelecer a correspondência entre a abundância das espécies e o gradiente ambiental (solo e topografia). O método TWINSPAN modificado foi aplicado ao diagrama de ordenação da CCA para avaliar a influência das variáveis ambientais (solo e topografia) na composição de espécies. Árvores de regressão \"ampliadas\" (BRT) foram ajustadas para a predição da ocorrência das espécies segundo as variáveis de solo e topografia. O índice de Getis-Ord (G) foi utilizado para determinar a autocorrelação espacial das variáveis ambientais utilizadas nos modelos de predição da ocorrência das espécies. Nas unidades fitogeográficas analisadas, a correspondência entre o gradiente ambiental (solo e topografia) e a abundância das espécies foi significativa, especialmente na Savana Florestada onde observou-se a maior relação. O solo e a topografia também se relacionaram com a semelhança na composição florística das subparcelas, com exceção da Floresta Estacional Semicidual (EEC). As principais variáveis de solo e topografia relacionadas a flora em cada UC foram: (1) Na Floresta Ombrófila Densa de Terras Baixas (PEIC) - teor de alumínio na camada profunda (Al (80-100 cm)) que pode refletir os teor de Al na superfície, acidez do solo (pH(H2O) (5-25 cm)) e altitude, que delimitou as áreas alagadas; (2) Na Floresta Ombrófila Densa Submontana (PECB) - altitude, fator que, devido ao relevo acidentado, influencia a temperatura e incidência de sol no sub-bosque; (3) Na Savana Florestada (EEA) - fertilidade, tolerância ao alumínio e acidez do solo. Nos modelos de predição BRT, as variáveis químicas dos solos foram mais importantes do que a textura, devido à pequena variação deste atributo no solo nas áreas amostradas. Dentre as variáveis químicas dos solos, a capacidade de troca catiônica foi utilizada para prever a ocorrência das espécies nas quatro formações florestais, sendo particularmente importante na camada mais profunda do solo da Floresta Ombrófila Densa de Terras Baixas (PEIC). Quanto à topografia, a altitude foi inserida na maioria dos modelos e apresentou diferentes influências sobre as áreas de estudo. De modo geral, para presença das espécies de ampla distribuição observou-se uma mesma tendência quando à associação com os atributos dos solos, porém com amplitudes dos descritores edáficos que variaram de acordo com a área de estudo. A ocorrência de Guapira opposita e Syagrus romanzoffiana, cujo padrão variou conforme a escala, foi explicada por variáveis com padrões espaciais agregados que somaram entre 30% e 50% de importância relativa no modelo BRT. A presença de A. anthelmia, cujo padrão também apresentou certo nível de agregação, foi associada apenas a uma variável com padrão agregado, a altitude (21%), que pode ter exercido grande influência na distribuição da espécie ao delimitar áreas alagadas. T. guianensis se associou a variáveis ambientais preditoras com padrão espacial agregado que somaram cerca de 70% de importância relativa, o que deve ter sido suficiente para estabelecer o padrão agregado em todas as escalas. No entanto, a influência dos fatores ambientais no padrão de distribuição da espécie não depende apenas do ótimo ambiental da espécie, mas um resultado da interação espécie-ambiente. Concluiu-se que: (I) características edáficas e topográficas explicaram uma pequena parcela da composição florística, em cada unidade fitogeográfica, embora a ocorrência de algumas espécies tenha se associado ao gradiente edáfico e topográfico; (II) a partir de características dos solos e da topografia foi possível prever a presença de espécies arbóreas, que apresentaram particularidades em relação a sua associação com o solo de cada fitofisionomia; (III) a partir de associações descritivas o solo e a topografia influenciam o padrão de distribuição espacial das espécies, na proporção em que contribuem para a presença das mesmas.
Resumo:
Friction in hydrodynamic bearings are a major source of losses in car engines ([69]). The extreme loading conditions in those bearings lead to contact between the matching surfaces. In such conditions not only the overall geometry of the bearing is relevant, but also the small-scale topography of the surface determines the bearing performance. The possibility of shaping the surface of lubricated bearings down to the micrometer ([57]) opened the question of whether friction can be reduced by mean of micro-textures, with mixed results. This work focuses in the development of efficient numerical methods to solve thin film (lubrication) problems down to the roughness scale of measured surfaces. Due to the high velocities and the convergent-divergent geometries of hydrodynamic bearings, cavitation takes place. To treat cavitation in the lubrication problem the Elrod- Adams model is used, a mass-conserving model which has proven in careful numerical ([12]) and experimental ([119]) tests to be essential to obtain physically meaningful results. Another relevant aspect of the modeling is that the bearing inertial effects are considered, which is necessary to correctly simulate moving textures. As an application, the effects of micro-texturing the moving surface of the bearing were studied. Realistic values are assumed for the physical parameters defining the problems. Extensive fundamental studies were carried out in the hydrodynamic lubrication regime. Mesh-converged simulations considering the topography of real measured surfaces were also run, and the validity of the lubrication approximation was assessed for such rough surfaces.
Resumo:
Criado inicialmente com a função básica de proteção aos pés, o calçado tornou-se um objeto de desejo e um acessório essencial de moda. Entre 1950 a 2015, estima-se que a produção mundial passe de 2,5 bilhões de pares produzidos para 25 bilhões de pares por ano, crescimento bem maior do que a população mundial. O couro, principal matéria-prima para a confecção de calçados, caracteriza-se por gerar grandes quantidades de resíduos ao longo de toda a cadeia produtiva. Especificamente na indústria coureiro-calçadista, o problema concentra-se nos elevados volumes de resíduos gerados na atividade produtiva, podendo causar desperdícios e grandes volumes de resíduos a serem descartados, envolvendo, principalmente, questões financeiras e ambientais. Países como Alemanha e Estados Unidos possuem legislação específica sobre a gestão de resíduos desde os anos 1970. No Brasil, depois de mais de 20 anos de tramitação no Congresso Nacional, em 2010, foi instituída a Política Nacional de Resíduos Sólidos, que reúne princípios, objetivos, instrumentos, diretrizes e metas, que deverão ser adotados pelos governos nas esferas federal, estadual e municipal, bem como pelas empresas com vistas à gestão integrada e ao gerenciamento ambientalmente adequado dos resíduos sólidos. Dessa forma, o objetivo desta tese foi desenvolver um modelo de gestão de resíduos industriais para o setor calçadista de Franca-SP com vistas à Política Nacional de Resíduos Sólidos. O desenvolvimento do modelo teve como ponto de partida um estudo bibliográfico sobre o assunto e, na sequência, por intermédio de uma pesquisa aplicada, conseguiu-se, em um primeiro momento, analisar a situação atual para compreender o modelo de gestão de resíduos vigente e realizar uma pesquisa de diagnóstico dos resíduos industriais do setor. Tal pesquisa possibilitou verificar que atualmente, esses resíduos, são enviados em sua totalidade para aterros sanitários, possibilitou também sua quantificação e cálculos dos custos envolvidos para transporte e destinação. Na sequência, realizaram-se estudos sobre a viabilidade técnica e financeira para tratamento térmico desses resíduos e a busca de benchmark no setor. O estudo também proporcionou uma contribuição de caráter mais prático e/ou gerencial ao recomendar diretrizes para a elaboração de um plano de gestão integrada de resíduos industriais para o setor, e uma proposta de gestão compartilhada dos resíduos industriais entre a entidade de classe e as indústrias calçadistas, com vistas à eliminação de envio desses resíduos para aterros. Dessa forma, contribuiu também para a elaboração do Plano Municipal de Gestão Integrada de Resíduos Sólidos do município em questão. Nesse sentido, após as análises e desdobramentos das etapas anteriores, foi possível propor um modelo de gestão de resíduos industriais, bem como demonstrar sua viabilidade técnica e financeira. Tal modelo foi denominado \"Modelo de Equiparação de Custos com Eficiência Ambiental\".
Resumo:
Observations of magnetars and some of the high magnetic field pulsars have shown that their thermal luminosity is systematically higher than that of classical radio-pulsars, thus confirming the idea that magnetic fields are involved in their X-ray emission. Here we present the results of 2D simulations of the fully coupled evolution of temperature and magnetic field in neutron stars, including the state-of-the-art kinetic coefficients and, for the first time, the important effect of the Hall term. After gathering and thoroughly re-analysing in a consistent way all the best available data on isolated, thermally emitting neutron stars, we compare our theoretical models to a data sample of 40 sources. We find that our evolutionary models can explain the phenomenological diversity of magnetars, high-B radio-pulsars, and isolated nearby neutron stars by only varying their initial magnetic field, mass and envelope composition. Nearly all sources appear to follow the expectations of the standard theoretical models. Finally, we discuss the expected outburst rates and the evolutionary links between different classes. Our results constitute a major step towards the grand unification of the isolated neutron star zoo.
Resumo:
Background: Gender inequalities in the exposure to work-related psychosocial hazards are well established. However, little is known about how welfare state regimes influence these inequalities. Objectives: To examine the relationship between welfare state regimes and gender inequalities in the exposure to work-related psychosocial hazards in Europe, considering occupational social class. Methods: We used a sample of 27, 465 workers from 28 European countries. Dependent variables were high strain, iso-strain, and effort-reward imbalance, and the independent was gender. We calculated the prevalence and prevalence ratio separately for each welfare state regime and occupational social class, using multivariate logistic regression models. Results: More female than male managers/professionals were exposed to: high strain, iso-strain, and effort–reward imbalance in Scandinavian [adjusted prevalence ratio (aPR) = 2·26; 95% confidence interval (95% CI): 1·87–2·75; 2·12: 1·72–2·61; 1·41: 1·15–1·74; respectively] and Continental regimes (1·43: 1·23–1·54; 1·51: 1·23–1·84; 1·40: 1·17–1·67); and to high strain and iso-strain in Anglo-Saxon (1·92: 1·40–2·63; 1·85: 1·30–2·64; respectively), Southern (1·43: 1·14–1·79; 1·60: 1·18–2·18), and Eastern regimes (1·56: 1·35–1·81; 1·53: 1·28–1·83). Conclusion: Gender inequalities in the exposure to work-related psychosocial hazards were not lower in those welfare state regimes with higher levels of universal social protection policies.
Resumo:
The economic design of a distillation column or distillation sequences is a challenging problem that has been addressed by superstructure approaches. However, these methods have not been widely used because they lead to mixed-integer nonlinear programs that are hard to solve, and require complex initialization procedures. In this article, we propose to address this challenging problem by substituting the distillation columns by Kriging-based surrogate models generated via state of the art distillation models. We study different columns with increasing difficulty, and show that it is possible to get accurate Kriging-based surrogate models. The optimization strategy ensures that convergence to a local optimum is guaranteed for numerical noise-free models. For distillation columns (slightly noisy systems), Karush–Kuhn–Tucker optimality conditions cannot be tested directly on the actual model, but still we can guarantee a local minimum in a trust region of the surrogate model that contains the actual local minimum.
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In this paper, the authors extend and generalize the methodology based on the dynamics of systems with the use of differential equations as equations of state, allowing that first order transformed functions not only apply to the primitive or original variables, but also doing so to more complex expressions derived from them, and extending the rules that determine the generation of transformed superior to zero order (variable or primitive). Also, it is demonstrated that for all models of complex reality, there exists a complex model from the syntactic and semantic point of view. The theory is exemplified with a concrete model: MARIOLA model.
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The process of liquid silicon infiltration is investigated for channels with radii from 0.25 to 0.75 [mm] drilled in compact carbon preforms. The advantage of this setup is that the study of the phenomenon results to be simplified. For comparison purposes, attempts are made in order to work out a framework for evaluating the accuracy of simulations. The approach relies on dimensionless numbers involving the properties of the surface reaction. It turns out that complex hydrodynamic behavior derived from second Newton law can be made consistent with Lattice-Boltzmann simulations. The experiments give clear evidence that the growth of silicon carbide proceeds in two different stages and basic mechanisms are highlighted. Lattice-Boltzmann simulations prove to be an effective tool for the description of the growing phase. Namely, essential experimental constraints can be implemented. As a result, the existing models are useful to gain more insight on the process of reactive infiltration into porous media in the first stage of penetration, i.e. up to pore closure because of surface growth. A way allowing to implement the resistance from chemical reaction in Darcy law is also proposed.
Resumo:
Naïve FoxP3-expressing regulatory T-cells (Tregs) are essential to control immune responses via continuous replenishment of the activated-Treg pool with thymus-committed suppressor cells. The mechanisms underlying naïve-Treg maintenance throughout life in face of the age-associated thymic involution remain unclear. We found that in adults thymectomized early in infancy the naïve-Treg pool is remarkably well preserved, in contrast to conventional naïve CD4 T-cells. Naïve-Tregs featured high levels of cycling and pro-survival markers, even in healthy individuals, and contrasted with other circulating naïve/memory CD4 T-cell subsets in terms of their strong γc-cytokine-dependent signaling, particularly in response to IL-7. Accordingly, ex-vivo stimulation of naïve-Tregs with IL-7 induced robust cytokine-dependent signaling, Bcl-2 expression, and phosphatidylinositol 3-kinase (PI3K)-dependent proliferation, whilst preserving naïve phenotype and suppressive capacity. Altogether, our data strongly implicate IL-7 in the thymus-independent long-term survival of functional naïve-Tregs, and highlight the potential of targeting the IL-7 pathway to modulate Tregs in different clinical settings.
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This research project is the product of a conviction, corroborated by the events that have overwhelmed the Arab world since December 2010, that sustainability is essential to any understanding of Mediterranean politics. Sustainability has too often been confused with stability in policy debates in the region and in the West. Not only are these two concepts distinct, with sustainability being broader and deeper than stability, but stability, as interpreted with regard to the regimes in the region, has often run counter to the very conditions that underpin state sustainability. Believing and thus pursuing regime stability has ultimately acted to the detriment of a more organic understanding of state sustainability.
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One objective of Computable general equilibrium (CGE) models is the analysis of economy-wide effects of policy measures. The focus of the Factor Markets project is to analyse the functioning of factor markets for agriculture in the EU-27, including the Candidate Countries. While agricultural and food markets are fully integrated in a European single market, subject to an EU-wide common policy, the Common Agricultural Policy (CAP), this is not the case for the agricultural factor markets capital, labour and land. There are partly serious differences with regard to member state regulations and institutions affecting land, labour and capital markets. The presentation of this heterogeneity of factor markets amongst EU Member States have been implemented in the CGE models to improve model-based analyses of the CAP and other policy measures affecting agricultural production. This final report comprises the outcome of a systematic extension and improvement of the Modular Applied GeNeral Equilibrium Tool (MAGNET) model starting from an overview of the current state of the art to represent factor markets in CGE models to a description of work on labour, land and capital in MAGNET.
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Recent scholarship has suggested that nation-states will gradually fade away in favor of regions and super-regions as the main actors within a European Union characterized by strong regional identities. At the same time, recent developments have shown that citizen support for European integration is essential for any future development of the Union. The puzzle inspiring this paper is the finding that the greatest support for the EU increasingly stems from minority nationalist regions seeking to bypass their central states to achieve their policy goals at the EU level. This paper empirically tests this suggestion, while shedding light on the relationship between the quality of representation of regional interests at the EU level and positive citizen attitudes towards the EU. In particular, it finds two explanations for cross-regional variation in the relationship between Euroskepticism and representation: (1) a cultural explanation, embodied by a difference in the nature and quality of representation between regions that are linguistically distinctive and regions that are not; and (2) an institutional explanation, embodied by a difference in the nature and quality of representation between regions from federal and non-federal member states. The paper uses an eclectic methodological approach, first utilizing multivariate regression analysis, estimating logistic and ordinal logit models that help explain variation in Euroskepticism at the regional level. The results are then complemented by the findings of in-depth elite interviews of regional representatives - more specifically the directors of a selection of the many regional information offices present in Brussels. This paper takes the study of Euroskepticism to a new level, as most previous scholarly work has focused on explanations at the individual or at the member state level. At the same time it strengthens the notion of a growing importance of a "Europe of the regions."
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This paper considers the role of social model features in the economic performance of Italy and Spain during the run-up to the Eurozone crisis, as well as the consequences of that crisis, in turn, for the two countries social models. It takes issue with the prevailing view - what I refer to as the “competitiveness thesis” - which attributes the debtor status of the two countries to a lack of competitive capacity rooted in social model features. This competitiveness thesis has been key in justifying the “liberalization plus austerity” measures that European institutions have demanded in return for financial support for Italy and Spain at critical points during the crisis. The paper challenges this prevailing wisdom. First, it reviews the characteristics of the Italian and Spanish social models and their evolution in the period prior to the crisis, revealing a far more complex, dynamic and differentiated picture than is given in the political economy literature. Second, the paper considers various ways in which social model characteristics are said to have contributed to the Eurozone crisis, finding such explanations wanting. Italy and Spain ́s debtor status was primarily the result of much broader dynamics in the Euro- zone, including capital flows from richer to poorer countries that affected economic demand, with social model features playing, at most, an ancillary role. More aggressive reforms responding to EU demands in Spain may have increased the long term social and economic costs of the crisis, whereas the political stalemate that slowed such reforms in Italy may have paradoxically mitigated these costs. The comparison of the two countries thus suggests that, in the absence of broader macro-institutional reform of the Eurozone, compliance with EU dictates may have had perverse effects.
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Addressing high and volatile natural resource prices, uncertain supply prospects, reindustrialization attempts and environmental damages related to resource use, resource efficiency has evolved into a highly debated proposal among academia, policy makers, firms and international financial institutions (IFIs). In 2011, the European Union (EU) declared resource efficiency as one of its seven flagship initiatives in its Europe 2020 strategy. This paper contributes to the discussions by assessing its key initiative, the Roadmap to a Resource Efficient Europe (EC 2011 571), following two streams of evaluation. In a first step, resource efficiency is linked to two theoretical frameworks regarding sustainability, (i) the sustainability triangle (consisting of economic, social and ecological dimensions) and (ii) balanced sustainability (combining weak and strong sustainability). Subsequently, both sustainability frameworks are used to assess to which degree the Roadmap follows the concept of sustainability. It can be concluded that it partially respects the sustainability triangle as well as balanced sustainability, primarily lacking a social dimension. In a second step, following Steger and Bleischwitz (2009), the impact of resource efficiency on competitiveness as advocated in the Roadmap is empirically evaluated. Using an Arellano–Bond dynamic panel data model reveals no robust impact of resource efficiency on competiveness in the EU between 2004 and 2009 – a puzzling result. Further empirical research and enhanced data availability are needed to better understand the impacts of resource efficiency on competitiveness on the macroeconomic, microeconomic and industry level. In that regard, strengthening the methodologies of resource indicators seem essential. Last but certainly not least, political will is required to achieve the transition of the EU-economy into a resource efficient future.
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The ability to view and interact with 3D models has been happening for a long time. However, vision-based 3D modeling has only seen limited success in applications, as it faces many technical challenges. Hand-held mobile devices have changed the way we interact with virtual reality environments. Their high mobility and technical features, such as inertial sensors, cameras and fast processors, are especially attractive for advancing the state of the art in virtual reality systems. Also, their ubiquity and fast Internet connection open a path to distributed and collaborative development. However, such path has not been fully explored in many domains. VR systems for real world engineering contexts are still difficult to use, especially when geographically dispersed engineering teams need to collaboratively visualize and review 3D CAD models. Another challenge is the ability to rendering these environments at the required interactive rates and with high fidelity. In this document it is presented a virtual reality system mobile for visualization, navigation and reviewing large scale 3D CAD models, held under the CEDAR (Collaborative Engineering Design and Review) project. It’s focused on interaction using different navigation modes. The system uses the mobile device's inertial sensors and camera to allow users to navigate through large scale models. IT professionals, architects, civil engineers and oil industry experts were involved in a qualitative assessment of the CEDAR system, in the form of direct user interaction with the prototypes and audio-recorded interviews about the prototypes. The lessons learned are valuable and are presented on this document. Subsequently it was prepared a quantitative study on the different navigation modes to analyze the best mode to use it in a given situation.