270 resultados para GAM
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Dr. B. May, J.B. Levy
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Thesis (Master's)--University of Washington, 2016-06
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Thesis (Master's)--University of Washington, 2016-06
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The main aim of this work was to study the effect of two comonomers, trimethylolpropane trimethacrylate (TRIS) and divinylbenzene (DVB) on the nature and efficiency of grafting of two different monomers, glycidyl methacrylate (GMA) and maleic anhydride (MA) on polypropylene (P) and on natural rubber (NR) using reactive processing methods. Four different peroxides, benzoyl peroxide (BPO), dicumyl peroxide (DCP), 2,5-dimethyl-2,5-bis-(tert-butyl peroxy) hexane (t-101), and 1,1-di(tert-butylperoxy)-3,3,5-trimethyl cyclohexene (T-29B90) were examined as free radical initiators. An appropriate methodology was established and chemical composition and reactive processing parameters were examined and optimised. It was found that in the absence of the coagents DVB and TRIS, the grafting degree of GMA and MA increased with increasing peroxide concentration, but the level of grafting was low and the homopolymerisaton of GMA and the crosslinking of NR or chain scission of PP were identified as the main side reactions that competed with the desired grafting reaction in the polymers. At high concentrations of the peroxide T-101 (>0.02 mr) cross linking of NR and chain scission of PP became dominant and unacceptable. An attempt to add a reactive coagent, e.g. TRIS during grafting of GMA on natural rubber resulted in excessive crosslinking because of the very high reactivity of this comonomer with the C=C of the rubber. Therefore, the use of any multifunctional and highly reactive coagent such as TRIS, could not be applied in the grafting of GAM onto natural rubber. In the case of PP, however, the use of TRIS and DVB was shown to greatly enhance the grafting degree and reduce the chain scission with very little extent of monomer homopolymerisation taking place. The results showed that the grafting degree was increased with increasing GMA and MA concentrations. It was also found that T-101 was a suitable peroxide to initiate the grafting reaction of these monomers on NR and PP and the optimum temperature for this peroxide was =160°C. A very preliminary work was also conducted on the use of the functionalised-PP (f-PP) in the absence and presence of the two comonomers (f-PP-DVB or f-PP-TRIS) for the purpose of compatibilising PP-PBT blends through reactive blending. Examination of the morphology of the blends suggested that an effective compatibilisation has been achieved when using f-PP-DVB and f-PP-TRIS, however more work is required in this area.
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To effectively assess and mitigate risk of permafrost disturbance, disturbance-p rone areas can be predicted through the application of susceptibility models. In this study we developed regional susceptibility models for permafrost disturbances using a field disturbance inventory to test the transferability of the model to a broader region in the Canadian High Arctic. Resulting maps of susceptibility were then used to explore the effect of terrain variables on the occurrence of disturbances within this region. To account for a large range of landscape charac- teristics, the model was calibrated using two locations: Sabine Peninsula, Melville Island, NU, and Fosheim Pen- insula, Ellesmere Island, NU. Spatial patterns of disturbance were predicted with a generalized linear model (GLM) and generalized additive model (GAM), each calibrated using disturbed and randomized undisturbed lo- cations from both locations and GIS-derived terrain predictor variables including slope, potential incoming solar radiation, wetness index, topographic position index, elevation, and distance to water. Each model was validated for the Sabine and Fosheim Peninsulas using independent data sets while the transferability of the model to an independent site was assessed at Cape Bounty, Melville Island, NU. The regional GLM and GAM validated well for both calibration sites (Sabine and Fosheim) with the area under the receiver operating curves (AUROC) N 0.79. Both models were applied directly to Cape Bounty without calibration and validated equally with AUROC's of 0.76; however, each model predicted disturbed and undisturbed samples differently. Addition- ally, the sensitivity of the transferred model was assessed using data sets with different sample sizes. Results in- dicated that models based on larger sample sizes transferred more consistently and captured the variability within the terrain attributes in the respective study areas. Terrain attributes associated with the initiation of dis- turbances were similar regardless of the location. Disturbances commonly occurred on slopes between 4 and 15°, below Holocene marine limit, and in areas with low potential incoming solar radiation
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Los principales recursos pesqueros pelágicos de interés económico en el Perú son anchoveta (Engraulis ringens), jurel (Trachurus murphyi) y caballa (Scomber japonicus) [3]. Para su evaluación, se lleva a cabo cruceros de evaluación acústica en los que se integra información de ecoabundancia y proporción de tallas por especie para obtener valores de biomasa y abundancia. Sin embargo, para especies no objetivo (como jurel), dichos valores resultan poco confiables por la lejanía entre los puntos de muestreo biométrico y acústico. Para resolver este inconveniente, el presente trabajo propuso utilizar modelos empíricos (de tipo GAM y GLM) integrando variables ambientales y de seguimiento de desembarques con la finalidad de generar índices relativos y absolutos para anchoveta y jurel en el período de 1996-2013 dentro del área de las 200 mn frente a la costa peruana. Los resultados obtenidos realzaron la importancia de los lances de comprobación para la obtención de estimaciones robustas de biomasa. Así mismo, se observó que, para anchoveta, los modelos empíricos sí produjeron un buen índice relativo y absoluto, mejorando la utilización de la ecoabundancia por sí sola. Para jurel, sin embargo, el modelo final calibrado resultó en la obtención de un mejor índice relativo. Se recomienda además, la obtención de información de tallas y pesos medios de desembarques para jurel con la finalidad de mejorar las estimaciones de biomasa y abundancia.
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Se analiza la re-configuración de los espacios urbanos y las repercusiones socio-ambientales vinculadas con la globalización neoliberal en las zonas metropolitanas de las sociedades periféricas, específicamente en la Gran Área Metropolitana (GAM) de Costa Rica. La tesis central del análisis es que esta re-configuración ha moldeado y acelerado el patrón urbano, espacial y ambiental de la GAM a través de 1) la segmentación de los mercados en correlación con procesos dispares de inclusión y exclusión social y 2) la erosión de los circuitos naturales ligados a los ecosistemas terrestres ubicados en la GAM. Abstract The article analyzes the re-configuration of the urban spaces and the socio- environmental impacts related with the neoliberal globalization in the metropolitan zones of peripheral societies, specifically in the Metropolitan Area (GAM) of Costa Rica. The central thesis of the analysis is that this re-configuration has molded and accelerated the spatial and environmental urban pattern of the GAM through the 1) segmentation of the markets in correlation with different processes of social inclusion and exclusion and 2) the erosion of the natural circuits linked to the terrestrial ecosystems located in the GAM
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Seasonal and interannual changes (1993e2012) of water temperature and transparency, river discharge, salinity, water quality properties, chlorophyll a (chl-a) and the carbon biomass of the main taxonomical phytoplankton groups were evaluated at a shallow station (~2 m) in the subtropical Patos Lagoon Estuary (PLE), Brazil. Large variations in salinity (0e35), due to a complex balance between Patos Lagoon outflow and oceanic inflows, affected significantly other water quality variables and phytoplankton dynamics, masking seasonal and interannual variability. Therefore, salinity effect was filtered out by means of a Generalized Additive Model (GAM). River discharge and salinity had a significant negative relation, with river discharge being highest and salinity lowest during July to October. Diatoms comprised the dominant phytoplankton group, contributing substantially to the seasonal cycle of chl-a showing higher values in austral spring/summer (September to April) and lowest in autumn/winter (May to August). PLE is a nutrient-rich estuary and the phytoplankton seasonal cycle was largely driven by light availability, with few exceptions in winter. Most variables exhibited large interannual variability. When varying salinity effect was accounted for, chl-a concentration and diatom biomass showed less irregularity over time, and significant increasing trends emerged for dinoflagellates and cyanobacteria. Long-term changes in phytoplankton and water quality were strongly related to variations in salinity, largely driven by freshwater discharge influenced by climatic variability, most pronounced for ENSO events. However, the significant increasing trend of the N:P ratio indicates that important environmental changes related to anthropogenic effects are undergoing, in addition to the hydrology in the PLE.
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Durante el periodo 1998-2005, la unidad de Materiales Peligrosos del Instituto Nacional de Seguros (MATPEL) atendió 329 emergencias químico-tecnológicas en Costa Rica, de las cuales 255 ocurrieron en la Gran Área Metropolitana (GAM). En los años 2002 y 2003 se observaron los mayores porcentajes de siniestros en la GAM, 82% y 92%, respectivamente. El 2004 presentó la menor cantidad de incidentes con 25, de los cuales 20 (80%) ocurrieron en el área metropolitana. En promedio en la GAM se atienden 32 accidentes por año, lo que equivale a 2,7 eventos por mes.
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La Guia de Gestão Autônoma da Medicação (Guía GAM) es una experiencia de investigación de carácter cualitativo llevada a cabo conjuntamente por usuarios y profesionales del ámbito de la salud mental e investigadores universitarios. Desarrollada originariamente en Québec (Canadá), el artículo se centra en la experiencia de adaptación e implementación de la guía al contexto brasileño. La Guía GAM aborda la cuestión de la medicación antipsicótica y la posible gestión compartida del tratamiento por parte de los actores implicados. La metodología utilizada por la GAM propicia abrir un espacio de diálogo en relación al tratamiento farmacológico configurándose como una herramienta que permite alterar las relaciones de poder existentes en el ámbito de la atención a la salud mental, facilitando la participación y la implicación efectiva de los afectados en la toma de decisiones en relación con su proceso de atención. El artículo aborda asimismo el proceso de trasformación seguido por dicha experiencia desde sus inicios como investigación académica hasta su implementación en los servicios de atención a la salud mental del Estado de Rio Grande do Sul como herramienta de trabajo, incluyendo los desafíos y oportunidades que ello supuso.
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My thesis consists of three essays that investigate strategic interactions between individuals engaging in risky collective action in uncertain environments. The first essay analyzes a broad class of incomplete information coordination games with a wide range of applications in economics and politics. The second essay draws from the general model developed in the first essay to study decisions by individuals of whether to engage in protest/revolution/coup/strike. The final essay explicitly integrates state response to the analysis. The first essay, Coordination Games with Strategic Delegation of Pivotality, exhaustively analyzes a class of binary action, two-player coordination games in which players receive stochastic payoffs only if both players take a ``stochastic-coordination action''. Players receive conditionally-independent noisy private signals about the normally distributed stochastic payoffs. With this structure, each player can exploit the information contained in the other player's action only when he takes the “pivotalizing action”. This feature has two consequences: (1) When the fear of miscoordination is not too large, in order to utilize the other player's information, each player takes the “pivotalizing action” more often than he would based solely on his private information, and (2) best responses feature both strategic complementarities and strategic substitutes, implying that the game is not supermodular nor a typical global game. This class of games has applications in a wide range of economic and political phenomena, including war and peace, protest/revolution/coup/ strike, interest groups lobbying, international trade, and adoption of a new technology. My second essay, Collective Action with Uncertain Payoffs, studies the decision problem of citizens who must decide whether to submit to the status quo or mount a revolution. If they coordinate, they can overthrow the status quo. Otherwise, the status quo is preserved and participants in a failed revolution are punished. Citizens face two types of uncertainty. (a) non-strategic: they are uncertain about the relative payoffs of the status quo and revolution, (b) strategic: they are uncertain about each other's assessments of the relative payoff. I draw on the existing literature and historical evidence to argue that the uncertainty in the payoffs of status quo and revolution is intrinsic in politics. Several counter-intuitive findings emerge: (1) Better communication between citizens can lower the likelihood of revolution. In fact, when the punishment for failed protest is not too harsh and citizens' private knowledge is accurate, then further communication reduces incentives to revolt. (2) Increasing strategic uncertainty can increase the likelihood of revolution attempts, and even the likelihood of successful revolution. In particular, revolt may be more likely when citizens privately obtain information than when they receive information from a common media source. (3) Two dilemmas arise concerning the intensity and frequency of punishment (repression), and the frequency of protest. Punishment Dilemma 1: harsher punishments may increase the probability that punishment is materialized. That is, as the state increases the punishment for dissent, it might also have to punish more dissidents. It is only when the punishment is sufficiently harsh, that harsher punishment reduces the frequency of its application. Punishment Dilemma 1 leads to Punishment Dilemma 2: the frequencies of repression and protest can be positively or negatively correlated depending on the intensity of repression. My third essay, The Repression Puzzle, investigates the relationship between the intensity of grievances and the likelihood of repression. First, I make the observation that the occurrence of state repression is a puzzle. If repression is to succeed, dissidents should not rebel. If it is to fail, the state should concede in order to save the costs of unsuccessful repression. I then propose an explanation for the “repression puzzle” that hinges on information asymmetries between the state and dissidents about the costs of repression to the state, and hence the likelihood of its application by the state. I present a formal model that combines the insights of grievance-based and political process theories to investigate the consequences of this information asymmetry for the dissidents' contentious actions and for the relationship between the magnitude of grievances (formulated here as the extent of inequality) and the likelihood of repression. The main contribution of the paper is to show that this relationship is non-monotone. That is, as the magnitude of grievances increases, the likelihood of repression might decrease. I investigate the relationship between inequality and the likelihood of repression in all country-years from 1981 to 1999. To mitigate specification problem, I estimate the probability of repression using a generalized additive model with thin-plate splines (GAM-TPS). This technique allows for flexible relationship between inequality, the proxy for the costs of repression and revolutions (income per capita), and the likelihood of repression. The empirical evidence support my prediction that the relationship between the magnitude of grievances and the likelihood of repression is non-monotone.
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Groundnut rosette disease (GRD) is the most destructive virus disease of Valencia groundnuts ( Arachis hypogaea L.) in sub-Saharan Africa. Cultural, biological and chemical control measures have received limited success due to small scale farmers’ inability to use them. Use of host plant resistance provides the most effective and economically viable management option for the resource poor farmers. This study was conducted to determine heritability for resistance to GRD in Valencia groundnuts. Six crosses; Valencia C (P1) × ICGV-SM 90704 (P2), Valencia C (P1) × ICGV-SM 96801(P2), Valencia C (P1) × ICGV-SM 99566 (P2), NuMex-M3 (P1) × ICGV-SM 90704 (P2), NuMex-M3 × ICGV-SM 96801 (P2), and NuMex-M3 (P1) × ICGV-SM 99566 (P2), were made to generate F1, F2, BC1P1 and BC1P2 populations. Data on GRD severity were collected on a 1-9 score scale. Genetic Advance as a percentage of the mean (GAM) and heritability were estimated using variance components. Phenotypic Coefficient of Variation (PCV) and Genotypic Coefficient of Variation (GCV) estimates were high (20.04-70.1%) in the six crosses, except for Valencia C × ICGV-SM 96801(18.1%) and NuMex-M3 × ICGV-SM 96801(17.1%), which exhibited moderate GCV values. Broad and narrow sense heritability estimates for GRD disease score ranged from 64.1 to 73.7% and 31 to 41.9%, respectively, in all the crosses. GAM was high in all the crosses (21-50.7%), except for Valencia C x ICGV-SM 96801 (14.67), M3 x ICGV-SM 99566 (18%) and NuMex-M3 x ICGV-SM 96801 (13.5%) crosses that exhibited moderate GAM. The study revealed the presence of variability of GRD resistance, implying that genetic improvement of these exotic materials is possible.
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Este estudo foi realizado durante o Outono de 2001, em três áreas agrícolas do Sul de Portugal e tem como objectivo determinar quais os factores que influenciam a selecção de habitat pelo Sisão no Outono. A amostragem baseou-se na realização de transectos a pé. A identificação das preferências de habitat e o desenvolvimento de modelos preditivos foi realizada recorrendo a modelação linear (GLM) e aditiva (GAM). Os resultados da análise à escala da paisagem indicaram que a espécie prefere restolhos de cereal e pousios. Adicionalmente, foram seleccionadas as áreas com melhores solos e mais próximas das linhas de drenagem. As análises relativas ao microhabitat sugerem que o Sisão utiliza preferencialmente áreas com vegetação herbácea baixa e com elevada disponibilidade de plantas verdes. Os resultados sugerem que a disponibilidade alimentar é ainda limitante durante esta época, pelo que a implementação de medidas agro-ambientais compreendendo a manutenção dos sistemas cerealíferos tradicionais e consequentemente dos restolhos e pousios nas áreas com solos mais produtivos, são as medidas adequadas para promover os habitats da espécie. ABSTRACT; This study was carried out in the autumn of 2001, in three cultivated areas of southem Portugal and aims to determine the factors that influence the habitat selection of the Little Bustard in that period of the year. Foot transects were used to locate Little Bustards. GLM and GAM modelling were performed to identify the species' habitat preferences and to develop explanative occurrence models. The results of the landscape analysis indicate that Little Bustards exhibit a preference for cereal stubbles and fallow lands. Additionally, birds were mostly found in fields with best soils and close to water drainage lines. Microhabitat analysis shows that birds seem to prefer short grassy vegetation, where the availability of green plants is higher. Results suggest that food availability is still limiting for the species at this season. Therefore, the implementation of agri-environmental schemes comprising the maintenance of traditional cereal farming and consequently stubbles and fallow land within areas with more productive soils, are adequate measures to promote suitable foraging habitats for the Little Bustard.
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Uma avaliação das metodologias de análise e recolha de dados aplicadas pelo Programa NOCTUAPortugal é de extrema importância para se apurar se estas são as mais indicadas em estudos de citizen science. Comparou-se os resultados de diferentes metodologias analíticas de estimação das tendências populacionais das espécies de aves noturnas durante o período de realização do Programa NOCTUA-Portugal (análise gráfica simples, modelos lineares generalizados (GLM-Poisson e GLMM), modelos aditivos generalizados (GAM-LOESS e GAM-mgcv) e software TRIM). Analisou-se a metodologia de censo de modo a avaliar o número de registos face à duração dos pontos de escuta, comparar a eficiência do ponto de deteção com outros estudos, variação das respostas ao longo da noite e efeito da época do ano, vento, nebulosidade e luminosidade da lua. Os resultados mostraram que a metodologia analítica mais indicada era o GLMM e que não era necessário realizar nenhum ajuste em particular na metodologia de censo; Trends in nocturnal birds in Portugal Methods and analysis of a volunteer-based monitoring program ABSTRACT: An evaluation of the methodologies of analysis and data collection applied by NOCTUA-Portugal Program is extremely important to determine whether these are the most suitable in citizen science studies. We compared the results of different analytical methodologies to estimate population trends of the species of nocturnal birds during the period of the NOCTUA-Portugal Program (simple graphical analysis, generalized linear models (GLM-Poisson and GLMM), generalized additive models (GAM-LOESS and GAMmgcv) and software TRIM). We analyzed the field methodology to assess the effect of point duration on the number of records, compared the point count efficiency with other sources, the variation of responses throughout the night, the effect of time of year, wind, cloud cover and moon luminosity. The results showed that the most suitable analytical methodology was the GLMM and it was not necessary to make any particular adjustment in the field methodology.
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La eutrofización marina es un problema que afecta a los mares europeos y particularmente a sus aguas costeras. Se trata del enriquecimiento anómalo en nutrientes de las aguas marinas, generalmente compuestos del nitrógeno y fósforo aportados por la actividad del ser humano, y que tiene como resultado consecuencias nocivas para la calidad de las aguas y la biodiversidad. La Directiva Marco de las Estrategias Marinas, que entró en vigor en 2010, recoge esta problemática y emplaza a los estados miembros para su evaluación y en su caso para la remediación de sus efectos nocivos identificando el origen de los aportes de nutrientes. Esta tarea requiere metodologías y procedimientos operativos que permitan ser implementados de forma coordinada por los estados miembros a nivel regional. En el primer capítulo de esta tesis se presenta una metodología para realizar la zonación del norte del mar Alborán a partir de imágenes de satélite de clorofila a tal que permite delimitar las áreas con características de productividad diferenciadas que pueden ser propuestas como unidades de gestión de la eutrofización y que se puedan emplear tanto en el diseño de los programas de seguimiento como en el aprovechamiento de los datos oceanográficos medidos in situ. En este capítulo se describe la metodología analítica utilizada, que está basada en la aplicación del análisis clúster de las k-medias a las imágenes de satélite de clorofila, así como su validez a partir del análisis de las series temporales de datos tomados in situ. El segundo capítulo se hace una evaluación de los indicadores de la eutrofización en una zona reducida de Alborán, donde existen multitud de datos oceanográficos, meteorológicos y ambientales. Para llevarla a cabo, se adaptó la metodología empleada en el capítulo 1 a la región ECOMALAGA. Una vez realizada la zonación, se agregaron los datos oceanográficos, meteorológicos y ambientales potencialmente relacionados con la eutrofización en cada área, y posteriormente se evaluaron las diferencias estadísticas a lo largo del ciclo estacional y entre las diferentes zonas. Con esta finalidad, se estiman las tendencias temporales de las variables ambientales en cada zona. A partir de los resultados obtenidos se infirió qué variables y/o mecanismos podrían estar influyendo sobre la concentración superficial de la clorofila a. En el tercer capítulo se ensayaron modelos aditivos generalizados (GAM) con el fin de identificar las variables más importantes que afectan a los indicadores de la eutrofización. Como variable respuesta del modelo se usó la clorofila a, pues se trata del indicador directo de la eutrofización más empleado. Las variables explicativas se componen de variables oceanográficas, meteorológicas y ambientales. En el cuarto capítulo se desarrolla un algoritmo regional para el mar de Alborán que permite obtener valores de clorofila a a partir de imágenes de satélite más ajustados a los valores que proporcionan los algoritmos disponibles que la sobreestiman considerablemente. En la discusión final y conclusiones se hace énfasis en el enfoque práctico de esta tesis doctoral, detallando la potencialidad de la metodología presentada para la evaluación de la eutrofización. Para esto, se detallan los resultados de la evaluación obtenidos para el mar Alborán empleando dicha metodología, definiendo su estado actual y las tendencias registradas, así como las causas de los problemas encontrados. Finalmente se evalúan y proponen posibles medidas para su remediación y control.