949 resultados para GLOBAL WELL-POSEDNESS
Resumo:
The 21st century has brought new challenges for forest management at a time when globalization in world trade is increasing and global climate change is becoming increasingly apparent. In addition to various goods and services like food, feed, timber or biofuels being provided to humans, forest ecosystems are a large store of terrestrial carbon and account for a major part of the carbon exchange between the atmosphere and the land surface. Depending on the stage of the ecosystems and/or management regimes, forests can be either sinks, or sources of carbon. At the global scale, rapid economic development and a growing world population have raised much concern over the use of natural resources, especially forest resources. The challenging question is how can the global demands for forest commodities be satisfied in an increasingly globalised economy, and where could they potentially be produced? For this purpose, wood demand estimates need to be integrated in a framework, which is able to adequately handle the competition for land between major land-use options such as residential land or agricultural land. This thesis is organised in accordance with the requirements to integrate the simulation of forest changes based on wood extraction in an existing framework for global land-use modelling called LandSHIFT. Accordingly, the following neuralgic points for research have been identified: (1) a review of existing global-scale economic forest sector models (2) simulation of global wood production under selected scenarios (3) simulation of global vegetation carbon yields and (4) the implementation of a land-use allocation procedure to simulate the impact of wood extraction on forest land-cover. Modelling the spatial dynamics of forests on the global scale requires two important inputs: (1) simulated long-term wood demand data to determine future roundwood harvests in each country and (2) the changes in the spatial distribution of woody biomass stocks to determine how much of the resource is available to satisfy the simulated wood demands. First, three global timber market models are reviewed and compared in order to select a suitable economic model to generate wood demand scenario data for the forest sector in LandSHIFT. The comparison indicates that the ‘Global Forest Products Model’ (GFPM) is most suitable for obtaining projections on future roundwood harvests for further study with the LandSHIFT forest sector. Accordingly, the GFPM is adapted and applied to simulate wood demands for the global forestry sector conditional on selected scenarios from the Millennium Ecosystem Assessment and the Global Environmental Outlook until 2050. Secondly, the Lund-Potsdam-Jena (LPJ) dynamic global vegetation model is utilized to simulate the change in potential vegetation carbon stocks for the forested locations in LandSHIFT. The LPJ data is used in collaboration with spatially explicit forest inventory data on aboveground biomass to allocate the demands for raw forest products and identify locations of deforestation. Using the previous results as an input, a methodology to simulate the spatial dynamics of forests based on wood extraction is developed within the LandSHIFT framework. The land-use allocation procedure specified in the module translates the country level demands for forest products into woody biomass requirements for forest areas, and allocates these on a five arc minute grid. In a first version, the model assumes only actual conditions through the entire study period and does not explicitly address forest age structure. Although the module is in a very preliminary stage of development, it already captures the effects of important drivers of land-use change like cropland and urban expansion. As a first plausibility test, the module performance is tested under three forest management scenarios. The module succeeds in responding to changing inputs in an expected and consistent manner. The entire methodology is applied in an exemplary scenario analysis for India. A couple of future research priorities need to be addressed, particularly the incorporation of plantation establishments; issue of age structure dynamics; as well as the implementation of a new technology change factor in the GFPM which can allow the specification of substituting raw wood products (especially fuelwood) by other non-wood products.
Resumo:
Climate change remains a major challenge for today’s and future societies due to its immense impacts on human lives and the natural environment. This thesis investigates the extent to which individuals are willing and prepared to voluntarily contribute to climate protection and to adjust to new climatic conditions in order to cope with the consequences of climate change and reduce the severity of potential negative impacts. The thesis thereby combines research in the fields of the private provision of environmental public goods and adaptation to climate change, which is still widely unconnected in the existing literature. The six contributions of this thesis mainly focus on microeconometric analyses using data from international surveys in China, Germany, and the USA. The main findings are: (i) A substantial share of individuals is willing to voluntarily contribute to climate protection and to adapt to climatic change. The engagement in both strategies is positively interrelated at the individual level and the analyses reveal hardly any evidence that adaptation activities crowd out individuals’ incentives to engage in climate protection. (ii) The main determinants of individuals’ adaptation activities seem to be the subjective risk perception as well as socio-economic and socio-demographic characteristics like age, gender, education, and income, while their climate protection efforts are found to be broadly motivated by financial advantages from these activities and additional immaterial benefits. (iii) The empirical findings also suggest a significantly positive relationship between certain climate protection activities. Substitutions are found to occur merely if one measure is perceived to be more effective in providing climate protection or if individuals have high environmental preferences. (iv) This thesis further reveals a common understanding of a (normatively) fair burden-sharing in international climate policy across citizens in China, Germany, and the USA. The highest preferences are found for the accountability principle.
Resumo:
In several computer graphics areas, a refinement criterion is often needed to decide whether to go on or to stop sampling a signal. When the sampled values are homogeneous enough, we assume that they represent the signal fairly well and we do not need further refinement, otherwise more samples are required, possibly with adaptive subdivision of the domain. For this purpose, a criterion which is very sensitive to variability is necessary. In this paper, we present a family of discrimination measures, the f-divergences, meeting this requirement. These convex functions have been well studied and successfully applied to image processing and several areas of engineering. Two applications to global illumination are shown: oracles for hierarchical radiosity and criteria for adaptive refinement in ray-tracing. We obtain significantly better results than with classic criteria, showing that f-divergences are worth further investigation in computer graphics. Also a discrimination measure based on entropy of the samples for refinement in ray-tracing is introduced. The recursive decomposition of entropy provides us with a natural method to deal with the adaptive subdivision of the sampling region
Resumo:
Durante la crisis financiera global de 2008 muchas organizaciones y mercados financieros tuvieron que terminar sus operaciones o replantearlas debido a los choques que golpearon el bienestar de sus empresas. A pesar de esta grave situación, en la actualidad se pueden encontrar empresas que se recuperaron y salieron del terrible panorama que les presentó la crisis, incluso encontrando nuevas oportunidades de negocio y fortaleciendo su futuro. Esta capacidad que algunas organizaciones tuvieron y que permitió su salida victoriosa de la crisis se denomina resiliencia, la cual es la capacidad de sobreponerse a los efectos negativos de choques internos o externos (Briguglio, Cordina, Farrugia & Vella 2009). Por tanto en el presente trabajo se estudiará esta capacidad tanto en la organización como en los líderes para hallar factores que mejoren el desempeño de las empresas en crisis como la que ocurrió en el 2008 – 2009. Primero se realizará un estudio sobre los sucesos y el desarrollo de la crisis subprime del año 2008 para tener un entendimiento claro de sus antecedentes, desarrollo, magnitud y consecuencias. Posteriormente se realizará un estudio profundo sobre la teoría de la resiliencia organizacional y la resiliencia en el líder como individuo y los estilos de liderazgo. Finalmente teniendo un sustento teórico tanto de la crisis como del concepto de resiliencia se tomarán casos de estudio de empresas que lograron perdurar en la crisis financiera del 2008 y empresas que no lograron sobrevivir para posteriormente hallar características del líder y del liderazgo que puedan aumentar o afectar la capacidad de resiliencia de las organizaciones con el objetivo de brindar herramientas a los líderes actuales para que manejen de forma eficiente y eficaz las empresas en un mundo complejo y variable como el actual.
Resumo:
El objetivo de este trabajo es analizar el fenómeno de la participación de las ONG en el marco de la Organización de Naciones Unidas (ONU) y las implicaciones del mismo en las dinámicas de la gobernanza global. Se explican los conceptos principales para el análisis y posteriormente se hace una revisión de los antecedentes que permitieron el desarrollo de dicho fenómeno dentro de la organización y fuera de ella. Luego se centra el análisis en la incidencia de las ONG en la ONU y para la gobernanza global; se concluye con una reflexión sobre lo que puede esperarse de esta incidencia para el futuro de la organización.
Resumo:
Perante a conjuntura atual, de crescente complexidade e mutação organizacional, a compreensão do comprometimento organizacional tem-se tornado fundamental na gestão de recursos humanos. Na presente investigação procura-se saber qual a influência do “Modelo das Três-Componentes”, proposto por Meyer e Allen (1991) na Estratégia Comportamental Voz do Modelo EVLN, proposto por Farrell e Rusbult (Farrell, 1983; Rusbult et al., 1982). Procura-se ainda saber se esta relação é mediada pela Satisfação Global com o Trabalho, conforme Hackman e Oldham (1980). Foi aplicado um questionário a uma amostra probabilística de 144 colaboradores na empresa EGEAC, composto pela escala de comprometimento organizacional de Meyer e Allen (1997), a escala voz do modelo de estratégias comportamentais EVLN de Farrell e Rusbult (Farrell, 1983; Rusbult et al., 1982) e a escala de satisfação global com o trabalho, de Hackman e Oldham (1980). Perante os resultados obtidos pode-se constatar que a componente organizacional afetiva e normativa determinam a estratégia comportamental voz, e que esta relação é positivamente mediada pela satisfação global com o trabalho. Como contributo para a gestão de recursos humanos o presente estudo demonstra a importância da gestão dos afetos e responsabilidades, visto a preponderância apresentada por estas componentes.
Resumo:
Várias evidências científicas têm mostrado consistentemente que o leite materno é o melhor alimento para os bebés sendo altamente benéfico para sua saúde a curto, médio e longo prazo. É recomendado às mulheres que amamentem o seu bebé exclusivamente por 6 meses e continuem a amamentar após os 6 meses, como parte de uma dieta equilibrada. Em casos em que, por qualquer motivo, a mãe não produz quantidade suficiente de leite, o bebé seja prematuro ou tenha alguma patologia, o leite materno doado pode ser a alternativa mais benéfica. Este trabalho tem por objetivo analisar a realidade dos bancos de leite doado em Portugal e no resto do mundo, bem como descrever o seu funcionamento desde a chegada do leite ao banco até à dispensa. Assim, para além do trabalho diário no banco de leite do Hospital Universitario Virgen de las Nieves em Granada, estudou-se o funcionamento de outros bancos de leite no mundo, incluindo Portugal, com o objetivo de comparar técnicas, procedimentos, e propor melhoramentos no processamento do leite materno doado. Com este estudo, foi possível concluir sobre a relevância nutricional e imunológica do Leite Humano Doado (LHD). Verificando-se que em casos de impossibilidade de a mãe amamentar, esta será a melhor opção de alimentação para bebés prematuros e/ou com muito baixo peso ao nascer. Quanto ao procedimento nos Bancos de Leite Humano (BLH), conclui-se que são necessários mais estudos e mais formação dos profissionais de saúde de forma a melhorar a qualidade do LHD bem como reduzir os riscos de infeção.
Resumo:
El artículo describe y compara las estrategias de seguridad nacional de Estados Unidos de las administraciones de Bill Clinton y George Bush. Trata de clarificar la forma en que se concibe el espacio nacional estadounidense, mundial y global dentro de estas estrategias.
Resumo:
This paper focuses on the role of the European Union (EU) in the formation of India’s climate change policy; an increasingly high profile issue area. It is based on an extensive study of relevant literature, EU-India policy documents and the execution of thirteen semi-structured interviews with experts; many of whom have experienced EU-India cooperation on climate change first-hand. A three-point typology will be used to assess the extent of the EU’s leadership role, supporting role or equal partnership role in India, with several sub-roles within these categories. Further, for clarity and chronology purposes, three time periods will be distinguished to assess how India’s climate policy has evolved over time, alongside the EU’s role within that. The findings of the paper confirm that the EU has demonstrated signs of all three roles to some degree, although the EU-India relationship in climate policy is increasingly an equal partnership. It offers explanations for previous shortcomings in EU-India climate policy as well as policy recommendations to help ensure more effective cooperation and implementation of policies.
Resumo:
The impact of selected observing systems on forecast skill is explored using the European Centre for Medium-Range Weather Forecasts (ECMWF) 40-yr reanalysis (ERA-40) system. Analyses have been produced for a surface-based observing system typical of the period prior to 1945/1950, a terrestrial-based observing system typical of the period 1950-1979 and a satellite-based observing system consisting of surface pressure and satellite observations. Global prediction experiments have been undertaken using these analyses as initial states, and which are available every 6 h, for the boreal winters of 1990/1991 and 2000/2001 and the summer of 2000, using a more recent version of the ECMWF model. The results show that for 500-hPa geopotential height, as a representative field, the terrestrial system in the Northern Hemisphere extratropics is only slightly inferior to the control system, which makes use of all observations for the analysis, and is also more accurate than the satellite system. There are indications that the skill of the terrestrial system worsens slightly and the satellite system improves somewhat between 1990/1991 and 2000/2001. The forecast skill in the Southern Hemisphere is dominated by the satellite information and this dominance is larger in the latter period. The overall skill is only slightly worse than that of the Northern Hemisphere. In the tropics (20 degrees S-20 degrees N), using the wind at 850 and 250 hPa as representative fields, the information content in the terrestrial and satellite systems is almost equal and complementary. The surface-based system has very limited skill restricted to the lower troposphere of the Northern Hemisphere. Predictability calculations show a potential for a further increase in predictive skill of 1-2 d in the extratropics of both hemispheres, but a potential for a major improvement of many days in the tropics. As well as the Eulerian perspective of predictability, the storm tracks have been calculated from all experiments and validated for the extratropics to provide a Lagrangian perspective.
Resumo:
Reanalysis data obtained from data assimilation are increasingly used for diagnostic studies of the general circulation of the atmosphere, for the validation of modelling experiments and for estimating energy and water fluxes between the Earth surface and the atmosphere. Because fluxes are not specifically observed, but determined by the data assimilation system, they are not only influenced by the utilized observations but also by model physics and dynamics and by the assimilation method. In order to better understand the relative importance of humidity observations for the determination of the hydrological cycle, in this paper we describe an assimilation experiment using the ERA40 reanalysis system where all humidity data have been excluded from the observational data base. The surprising result is that the model, driven by the time evolution of wind, temperature and surface pressure, is able to almost completely reconstitute the large-scale hydrological cycle of the control assimilation without the use of any humidity data. In addition, analysis of the individual weather systems in the extratropics and tropics using an objective feature tracking analysis indicates that the humidity data have very little impact on these systems. We include a discussion of these results and possible consequences for the way moisture information is assimilated, as well as the potential consequences for the design of observing systems for climate monitoring. It is further suggested, with support from a simple assimilation study with another model, that model physics and dynamics play a decisive role for the hydrological cycle, stressing the need to better understand these aspects of model parametrization. .
Resumo:
The impact of selected observing systems on the European Centre for Medium-Range Weather Forecasts (ECMWF) 40-yr reanalysis (ERA40) is explored by mimicking observational networks of the past. This is accomplished by systematically removing observations from the present observational data base used by ERA40. The observing systems considered are a surface-based system typical of the period prior to 1945/50, obtained by only retaining the surface observations, a terrestrial-based system typical of the period 1950-1979, obtained by removing all space-based observations, and finally a space-based system, obtained by removing all terrestrial observations except those for surface pressure. Experiments using these different observing systems have been limited to seasonal periods selected from the last 10 yr of ERA40. The results show that the surface-based system has severe limitations in reconstructing the atmospheric state of the upper troposphere and stratosphere. The terrestrial system has major limitations in generating the circulation of the Southern Hemisphere with considerable errors in the position and intensity of individual weather systems. The space-based system is able to analyse the larger-scale aspects of the global atmosphere almost as well as the present observing system but performs less well in analysing the smaller-scale aspects as represented by the vorticity field. Here, terrestrial data such as radiosondes and aircraft observations are of paramount importance. The terrestrial system in the form of a limited number of radiosondes in the tropics is also required to analyse the quasi-biennial oscillation phenomenon in a proper way. The results also show the dominance of the satellite observing system in the Southern Hemisphere. These results all indicate that care is required in using current reanalyses in climate studies due to the large inhomogeneity of the available observations, in particular in time.
Resumo:
Processes in the climate system that can either amplify or dampen the climate response to an external perturbation are referred to as climate feedbacks. Climate sensitivity estimates depend critically on radiative feedbacks associated with water vapor, lapse rate, clouds, snow, and sea ice, and global estimates of these feedbacks differ among general circulation models. By reviewing recent observational, numerical, and theoretical studies, this paper shows that there has been progress since the Third Assessment Report of the Intergovernmental Panel on Climate Change in (i) the understanding of the physical mechanisms involved in these feedbacks, (ii) the interpretation of intermodel differences in global estimates of these feedbacks, and (iii) the development of methodologies of evaluation of these feedbacks (or of some components) using observations. This suggests that continuing developments in climate feedback research will progressively help make it possible to constrain the GCMs’ range of climate feedbacks and climate sensitivity through an ensemble of diagnostics based on physical understanding and observations.
Resumo:
Cascade is a multi-institution project studying the temporal and spatial organization of tropical convective systems. While cloud resolving numerical models can reproduce the observed diurnal cycle of such systems they are sensitive to the chosen resolution. As part of this effort, we are comparing results from the Met. Office Unified Model to data from the Global Earth Radiation Budget satellite instrument over the African Monsoon Interdisciplinary Analyses region of North Africa. We use a variety of mathematical techniques to study the outgoing radiation and the evolution of properties such as the cloud size distribution. The effectiveness of various model resolutions is tested with a view to determining the optimum balance between resolution and the need to reproduce the observations.
Resumo:
Simulations of the last 500 yr carried out using the Third Hadley Centre Coupled Ocean-Atmosphere GCM (HadCM3) with anthropogenic and natural (solar and volcanic) forcings have been analyzed. Global-mean surface temperature change during the twentieth century is well reproduced. Simulated contributions to global-mean sea level rise during recent decades due to thermal expansion (the largest term) and to mass loss from glaciers and ice caps agree within uncertainties with observational estimates of these terms, but their sum falls short of the observed rate of sea level rise. This discrepancy has been discussed by previous authors; a completely satisfactory explanation of twentieth-century sea level rise is lacking. The model suggests that the apparent onset of sea level rise and glacier retreat during the first part of the nineteenth century was due to natural forcing. The rate of sea level rise was larger during the twentieth century than during the previous centuries because of anthropogenic forcing, but decreasing natural forcing during the second half of the twentieth century tended to offset the anthropogenic acceleration in the rate. Volcanic eruptions cause rapid falls in sea level, followed by recovery over several decades. The model shows substantially less decadal variability in sea level and its thermal expansion component than twentieth-century observations indicate, either because it does not generate sufficient ocean internal variability, or because the observational analyses overestimate the variability.