872 resultados para Variation and change linguistic
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Food webs have been used in order to understand the trophic relationship among organisms within an ecosystem, however the extension by which sampling efficiency could affect food web responses remain poorly understood. Still, there is a lack of long-term sampling data for many insect groups, mainly related to the interactions between herbivores and their host plants. In the first chapter, I describe a source food web based on the Senegalia tenuifolia plant by identifying the associated insect species and the interactions among them and with this host plant. Furthermore, I check for the data robustness from each trophic level and propose a cost-efficiently methodology. The results from this chapter show that the collected dataset and the methodology presented are a good tool for sample most insect richness of a source food web. In total the food web comprises 27 species belonging to four trophic levels. In the second chapter, I demonstrate the temporal variation in the species richness and abundance from each trophic level, as well as the relationship among distinct trophic levels. Moreover, I investigate the diversity patterns of the second and third trophic level by assessing the contribution of alfa and beta-diversity components along the years. This chapter shows that in our system the parasitoid abundance is regulated by the herbivore abundances. Besides, the species richness and abundances of the trophic levels vary temporally. It also shows that alfa-diversity was the diversity component that most contribute to the herbivore species diversity (2nd trophic level), while the contribution of alfa- and beta-diversity changed along the years for parasitoid diversity (3rd level). Overall, this dissertation describes a source food web and bring insights into some food web challenges related to the sampling effort to gather enough species from all trophic levels. It also discuss the relation among communities associated with distinct trophic levels and their temporal variation and diversity patterns. Finally, this dissertation contributes for the world food web database and in understanding the interactions among its trophic levels and each trophic level pattern along time and space
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Climate change is considered to be the most pervasive and truly global of all issues affecting humanity. It poses a serious threat to the environment, as well as to economies and societies. Whilst it is clear that the impacts of climate change are varied, scientists have agreed that its effects will not be evenly distributed and that developing countries and small island developing States (SIDS) will be the first and hardest hit. Small island developing States, many of whom have fewer resources to adapt socially, technologically and financially to climate change, are considered to be the most vulnerable to the potential impacts of climate change. An economic analysis of climate change can provide essential input for identifying and preparing policies and strategies to help move the Caribbean closer to solving the problems associated with climate change, and to attaining individual and regional sustainable development goals. Climate change is expected to affect the health of populations. In fact, the World Health Organization (WHO), in Protecting Health from Climate Change (2008), states that the continuation of current patterns of fossil fuel use, development and population growth will lead to ongoing climate change, with serious effects on the environment and, consequently, on human lives and health. Assessing the economics of potential health impacts of climate variability and change requires an understanding of both the vulnerability of a population and its capacity to respond to new conditions. The Intergovernmental Panel on Climate Change (IPCC) defines vulnerability as the degree to which individuals and systems are susceptible to, or unable to cope with, the adverse effects of climate change, including climate variability and extremes (WHO and others, 2003). The United Nations Economic Commission for Latin America and the Caribbean (ECLAC), in collaboration with the Caribbean Community Centre for Climate Change (CCCCC), is pursuing a regional project to ―Review the Economics of Climate Change in the Caribbean‖ (RECCC). The purpose of the project is to assess the likely economic impacts of climate change on key sectors of Caribbean economies, through applying robust simulation modelling analyses under various socio-economic scenarios and carbon emission trajectories for the next 40 years. The findings are expected to stimulate local and national governments, regional institutions, the private sector and civil society to craft and implement policies, cost-effective options and efficient choices to mitigate and adapt to climate change.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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This paper presents a computational fluid dynamics (CFD) application about the axial fan design used in an agricultural spraying system with a theoretical and experimental analysis of comparative results between the characteristic curves of a fan for several rotations and numerical results for the influence of blade attack angle variation and optimization of the spraying system, both for a same rotation. Flow was considered three-dimensional, turbulent, isothermal, viscous and non-compressible in a steady state, disregarding any influence of the gravity field. The average turbulent field was obtained from the application of time average where the turbulence model required for closing the set of equations was the k-E model. Resolution of all connected phenomena was achieved with the help of a fluid dynamics computer, CFX, which uses the finite volumes technique as a numerical method. In order to validate the theoretical analysis, an experiment was conducted in a circular section of a horizontal wind tunnel, using a Pitot tube for pressure readings. The main results demonstrate that the methodology used, based on CFD techniques, is able to reproduce the phenomenological behavior of an axial fan in a spraying system because results were very reliable and similar to experimentally measured ones.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)