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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

Respostas afirmativas para perguntas polares no PBL: um estudo em perspectiva gerativista / Affirmative answers to polar questions in the PBL: a study in generative perspective

Jorge, Lurdes Teresa Lopes 10 October 2018 (has links)
Esta tese investiga o fenômeno das perguntas polares do Português do Libolo - PLB, em que discuto na perspectiva da Teoria de Princípios e Parâmetros em sua versão conhecida como Programa Minimalista (CHOMSKY, 1995, 2005 e 2008, e versões subsequentes), aspectos da derivação sintática de respostas afirmativas a perguntas polares, em sentenças do PLB. A análise dos dados do PLB mostrou que respostas afirmativas a perguntas polares no PLB distribuem-se, preferencialmente, em respostas verbais e respostas com a partícula sim, que podem ser entendidas como instanciadoras de um traço de polaridade lexicalizado pelo verbo, quando o elemento verbal é núcleo de fase em que é licenciada a elipse de VP e pela partícula sim, na fase CP. O enfoque teórico é a Teoria de derivação por fases, do Programa Minimalista. / This thesis concerns the phenomenon of the Polar Interrogatives (PI) in Portuguese spoken in Libolo (PLB), discussing throughout the Principles and Parameters theory in its version known as the Minimalist Program (as set by Chomsky (1995) and following works) issues on the derivation of the syntactic structure of affirmative responses of PI sentences in PLB. The analysis of PLB data showed that affirmative answers to polar questions in PLB are distributed, preferably, in verbal responses and responses with the \"yes\" particle. The affirmative responses of PI sentences in PLB can be understood as instanciers of a polarity feature which is lexicalized by the verb, when the verbal form is the head of the phase that licenses VP ellipses and the yes particle, when the phase is CP. The theoretical approach is the Phase Theory of the Minimalist Program.
192

VHF radar studies of mesosphere and thermosphere

Beldon, Charlotte January 2008 (has links)
No description available.
193

Respostas afirmativas para perguntas polares no PBL: um estudo em perspectiva gerativista / Affirmative answers to polar questions in the PBL: a study in generative perspective

Lurdes Teresa Lopes Jorge 10 October 2018 (has links)
Esta tese investiga o fenômeno das perguntas polares do Português do Libolo - PLB, em que discuto na perspectiva da Teoria de Princípios e Parâmetros em sua versão conhecida como Programa Minimalista (CHOMSKY, 1995, 2005 e 2008, e versões subsequentes), aspectos da derivação sintática de respostas afirmativas a perguntas polares, em sentenças do PLB. A análise dos dados do PLB mostrou que respostas afirmativas a perguntas polares no PLB distribuem-se, preferencialmente, em respostas verbais e respostas com a partícula sim, que podem ser entendidas como instanciadoras de um traço de polaridade lexicalizado pelo verbo, quando o elemento verbal é núcleo de fase em que é licenciada a elipse de VP e pela partícula sim, na fase CP. O enfoque teórico é a Teoria de derivação por fases, do Programa Minimalista. / This thesis concerns the phenomenon of the Polar Interrogatives (PI) in Portuguese spoken in Libolo (PLB), discussing throughout the Principles and Parameters theory in its version known as the Minimalist Program (as set by Chomsky (1995) and following works) issues on the derivation of the syntactic structure of affirmative responses of PI sentences in PLB. The analysis of PLB data showed that affirmative answers to polar questions in PLB are distributed, preferably, in verbal responses and responses with the \"yes\" particle. The affirmative responses of PI sentences in PLB can be understood as instanciers of a polarity feature which is lexicalized by the verb, when the verbal form is the head of the phase that licenses VP ellipses and the yes particle, when the phase is CP. The theoretical approach is the Phase Theory of the Minimalist Program.
194

A new way to quantify stratosphere-troposphere coupling in observations and climate models

Clemo, Thomas Daniel January 2017 (has links)
Atmospheric mass is transported in and out of the stratospheric polar cap region by a wave-driven meridional circulation. Using composites of polar cap pressure anomalies, defined as deviations from the average annual cycle, it is shown that this stratospheric mass flux is accompanied by a similar mass flux near the surface. This 'tropospheric amplification' of the stratospheric signal is introduced as a new way to quantify stratosphere-troposphere coupling. Regression analysis is used to create a vertical profile of atmospheric pressure during a tropospheric amplification event, and the regression slope profile is used as a tool to quantify the amplification. Using data from 5 reanalysis datasets and 11 climate models, it is shown that high-top models, with a model lid of above 1 hPa, are significantly better at reproducing tropospheric amplification than low-top models, due to having more detailed parameterisations of stratospheric processes. However, the regression slope profiles of all models, bar one, are significantly different to the profile of reanalysis data at a 95% confidence level. Tropospheric amplification is also investigated in historical and future simulations from these models, and it is concluded that there is not expected to be a large change in the phenomenon over the next 100 years. The processes needed to reproduce tropospheric amplification can be identified by comparing idealised models of different complexity. A simple dry-core model is not able to reproduce tropospheric amplification, while a model with a comprehensive radiation scheme does produce the basic regression slope profile under certain configurations. The associations between pressure change and mass flux are further investigated using primitive equations. It is found that vertical and horizontal contributions to mass flux act to mostly cancel each other out, leaving a poorly-conditioned residual, and that the horizontal mass flux across the polar cap boundary has both geostrophic and ageostrophic components.
195

Cooperação e conflitos nas regiões polares : um cenário para o século XXI

Santos, Leo Evandro Figueiredo dos January 2016 (has links)
A presente tese trata de analisar, a partir da situação das Regiões Ártica e Antártica, questões ambientais que se inserem no campo das relações e dos estudos de segurança internacionais. Neste sentido, através de uma abordagem comparativa, ajusta-se, metodológica e teoricamente, as relações entre questões ambientais e de segurança e sua intersecção com os estudos sobre regimes internacionais. O objetivo é a partir de uma concepção de que são o Ártico (parcialmente) e a Antártica, áreas internacionais, examinar a relação existente entre a exploração de recursos naturais e questões ambientais (mudanças climáticas) e as possibilidades de conflitos e sua superação ou adiamento, em função do exame intrínseco da competição por recursos naturais (petróleo, gás, hidratos de gás, bioprospecção, recursos marinhos, água doce, turismo e rotas polares, esse último somente para o Ártico) e das mudanças climáticas e dos regimes concebidos nas Regiões Polares. Foram examinadas, ao mesmo tempo, dificuldades econômicas, ambientais, técnicas e políticas (dificuldades intrínsecas) à exploração de recursos ambientais, os efeitos das mudanças climáticas e a força dos regimes das Regiões Polares, verificando-se as respectivas capacidades de adiar ou evitar conflitos. Sendo que a força do regime foi examinada a partir do grau de impacto dos elementos que a formam: 1) efetividade do regime, 2) a resiliência do regime, 3) resistência do regime, 4) a presença do hegemon e outros Estados protagonistas, 5) mecanismos de aquiescência, que incentivem ou obriguem o respeito as regras do regime, e 6) existência de uma organização internacional vinculada. Partiu-se do pressuposto de que quanto maiores as dificuldades para exploração, menor seria a competição e, portanto, menores as possibilidades de ocorrerem conflitos. A possibilidade de ocorrência de conflitos também foi cotejada com o grau de fortalecimento dos regimes instalados nas Regiões Polares. A tese conclui que no Ártico e na Antártica as dificuldades para a exploração dos recursos naturais se equivalem. Especificamente no campo político e econômico, quanto aos minerais (inclusive água) na Antártica a dificuldade é maior na atualidade em função da vedação da exploração até 2048 e porque as pesquisas ainda são insuficientes para comprovar a viabilidade da exploração; em compensação no Ártico a localização dos recursos em áreas sob soberania ou no espaço que compreende a ZEE não enseja dificuldades políticas e jurídicas para exploração em função da aplicação da CNUDM. Por sua vez, em especial, as externalidades dos efeitos das mudanças climáticas nas Regiões Polares podem provocar o aumento do n.m.m. e alterações dos padrões climáticos, contudo conflitos não seriam inevitáveis. Em relação aos Regimes Polares ambos foram considerados fortes, contudo o regime antártico foi considerado mais fortalecido. O exame dos elementos, principalmente, a resiliência e efetividade do STA e cotejamento com o processo de consolidação do regime complexo do Ártico justificam a conclusão. Por fim conclui esta tese que as condições para exploração dos recursos naturais, os efeitos das mudanças climáticas nas e a partir das Regiões Polares e o grau de fortalecimento dos regimes internacionais lá constituídos revelam, que os conflitos, ainda que possíveis não são prováveis. / This thesis analyzes, from Arctic and Antarctic regions, environmental issues which fall within the field of international relations and security studies. In this sense, through a comparative approach sets, intends to, methodological and theoretically, the relationship between environmental and security issues and its intersection with studies on international relations. The goal is, from a design which are the Arctic (in part) and Antarctica, international areas, examining the links between the exploitation of natural resources and environmental issues (climate change) and the potential for conflicts and overcome them or postponement, due to the intrinsic exam competition for natural resources (oil, gas, gas hydrates, bioprospecting, marine resources, freshwater, tourism and polar routes, the latter only for the Arctic) and climate change and regimes in the polar regions. Were examined at the same time, economic, environmental, technical and policy difficulties (intrinsic difficulties) the exploitation of environmental resources, the effects of climate change and the strength of the polar regions regimes, verifying their ability to delay or avoid conflicts. The strength of the system was examined from the degree of impact of the elements that form it: 1) effectiveness of the system, 2) the resilience of the system, 3) regime resistance, 4) the presence of the hegemon and other protagonists States 5) compliance mechanisms that encourage or force respect the rules of the regime, and 6) the existence of a linked international organization. It started with the assumption that the greater the difficulties for exploration, would be less competition and therefore lower the chances of occurrence of conflicts. The possibility of conflict was also checked against the degree of strengthening of systems installed in the polar regions. The thesis concludes that the Arctic and Antarctic difficulties for the exploitation of natural resources are equivalent. Specifically, in the political and economic field, as minerals (including water) in Antarctica the difficulty is greater today due to the operations are prohibited up to 2048 and because the research is still insufficient to prove the viability of the exploitation; in compensation in the Arctic location of resources in areas under the sovereignty or within the EEZ that comprises not entails political and legal difficulties to exploitation due to the implementation of UNCLOS. In turn, in particular, the externalities of the effects of climate change on the polar regions can cause an increase in sea level and changes in weather patterns, however conflicts would not inevitable. Regarding the polar regimes both were considered strong, however the Antarctic regime was considered more strong. Examination of the components, especially the resilience and effectiveness of ATS and mutual comparison with the consolidation of the complex Arctic regime justify the conclusion. Finally, this thesis concludes that the conditions for exploitation of natural resources, the effects of climate change on and from the polar regions and the degree of strengthening international regimes established their reveal that the conflicts, although possible is not probable.
196

Terre des Hommes, pays des glaces : L'expérience touristique au Groenland / Men's land, ice country : Polar touristic experience in Greenland

Delmas, Antoine 30 June 2014 (has links)
À contre-courant des flux touristiques internationaux seuls dix millions de voyageurs se rendent dans les espaces polaires. Entre les mythes passés et l'actualité dynamique des hautes latitudes, les représentations des touristes se confrontent à la réalité du terrain. Au Groenland, les visiteurs sont attirés par la singularité des paysages de glace. Leur expérience touristique dessine les contours du cryotropisme. Dans la continuité de cette découverte, les visiteurs recherchent toute l'authenticité d'une île qui, dans leurs représentations, serait restée l'un des derniers endroits préservé par la modernité. Pour satisfaire ces désirs, les professionnels du tourisme dévoilent, arrangent ou composent avec la réalité des lieux. Ils fabriquent l'expérience touristique. Depuis les débuts du tourisme l'offre s'est étoffée, les services se sont multipliés et un réseau d'acteurs s'est constitué. Ces changements, toujours prégnants aujourd'hui, contribuent à l'arrivée de nouveaux acteurs, de nouvelles offres et à l'émergence de nouveaux lieux touristiques. En s'arrangeant d'échelles d'analyse articulées, du local au global, et de méthodes d'investigations plurielles, cette recherche s'intéresse aux processus de compositions et de recompositions spatiales induits par le tourisme. / By travelling in polar worlds, only ten million of tourists remain on the sidelines of international tourism flows. The tourists' representations are shaped by old myths and a dynamic polar topicality. When they land their built images are facing up the reality. In Greenland, tourists are attracted by the singularity of ice landscapes. Their touristic experiences are making the "cryotropism". In the continuity of this discovery, a lot of visitors are also looking for authenticity in the island. In their minds Greenland would have been preserved from any kind of modernity. By arranging and highlighting the value of spaces, the professionals of tourism activity are rebuilding places in order to satisfy tourist's desire. In this way they are the touristic experience producers. Since the beginning of tourism, the offer has been greatly strengthened, services has been multiplied, and a network of tourism actors has been formed. Nowadays those changes are still significant, they are contributing to the emergence of new offers, services and touristic places. Using different scales of analysis structured from local to global and a plurality of investigation methods, these thesis focuses on spaces composition and re-composition resulting by tourism activity.
197

CaracterizaÃÃo MecÃnica e Microestrutural de CerÃmicas Porosas Obtidas A Partir de Diferentes Aluminas / Mechanical and Microstructural Characterization of Porous Ceramics Obtained from Different Aluminas The

Andrà Gustavo de Sousa Galdino 25 March 2003 (has links)
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / O interesse em cerÃmicas porosas vem aumentando, à medida que novos processos vÃo sendo desenvolvidos, e as aplicaÃÃes decorrentes representam oportunidades tecnolÃgicas e econÃmicas substanciais. Para cada aplicaÃÃo, hà pelo menos uma propriedade relevante e deve ser avaliada, dependendo da funÃÃo: fÃsica, quÃmica e biolÃgica. Dentre as vÃrias aplicaÃÃes de cerÃmicas porosas, podem ser citadas: separadores de cÃlula para bateria, queimadores, suportes para catÃlise, filtros, sensores de gÃs, dentre outras. A alumina se destaca como matÃria-prima para corpos cerÃmicos devido as suas propriedades, tais como alta dureza, elevada resistÃncia ao desgaste, baixo coeficiente de atrito, alta resistÃncia à corrosÃo tanto à temperatura ambiente quanto em altas temperaturas ao ar, ausÃncia de transformaÃÃes no estado sÃlido, e o fato de que o material mantÃm sua resistÃncia mesmo em altas temperaturas (1500ÂC-1800ÂC). O objetivo deste trabalho à avaliar algumas propriedades mecÃnicas da alumina (Al2O3) com diferentes nÃveis de porosidade. As amostras forma produzidas pelos mÃtodos da esponja polimÃrica, adiÃÃo de cera polimÃrica e barras cerÃmicas com e sem bicarbonato de sÃdio. A sinterizaÃÃo foi realizada em duas temperaturas: a 1450ÂC e 1550ÂC. As propriedades analisadas foram: resistÃncia à flexÃo e dureza atravÃs das normas da ASTM, porosidade aparente, densidade aparente, retraÃÃo linear de queima, retraÃÃo linear de secagem e absorÃÃo de Ãgua, mÃtodo de Souza Santos para argilas. Os resultados obtidos mostraram-se bastante satisfatÃrios, onde foi mostrado que os corpos cerÃmicos porosos obtiveram valores de resistÃncia à flexÃo e dureza coerentes com os da literatura. Realizou-se tambÃm uma caracterizaÃÃo via difraÃÃo de raios-x (DRX) e microscopia eletrÃnica de varredura (MEV) das amostrar confeccionadas pelos dois mÃtodos. / The interest in porous ceramics is increasing, as new processes and technologies are going to be developed and hence applications representtechnological and economical opportunities. For each application, there is at least one important property that must be evaluated, depending on its function: physical, chemical and biological. There are many applications for porous ceramics bodies, such as: battery fuel cell separators, burners, catalyst supports, filters, gas sensors, etc. Alumina is a wild raw material used because of its properties, such as high hardness, high wear resistance, low friction coefficient, high resistance to corrosion at room temperature and at high temperature on air, the absence of transformations within the entire temperature range of solid state, and the fact that the material retains its strength even at very high temperatures (1500ÂC â 1800ÂC). This research describes the evaluation of some mechanical properties of alumina (Al2O3) with different levels of porosity obtained by the polymeric sponge method and by adding polymeric wax at 1450ÂC and 1550ÂC. Flexural strength and hardness were assessed using ASTM specifications. Apparent porosity, apparent density, linear shrinkage after sintering, linear shrinkage after drying and water absorption by Souza Santos clay method. Data showed to be satisfactory, where it was shown that porous ceramic bodies had flexural strength and hardness values corroborating with literature. Analyses were performed by x â rays diffraction (XRD) and scanning electronic microscopy (SEM) for both samples made by each method. In a general way, both samples made by each method had a similar behavior; however, samples made by adding polymeric wax presented less porosity homogeneity than those made by polymeric sponge method, and showed better sinterization at both temperatures either.
198

Respostas polares à infecção pela cromoblastomicose antes e após as terapias

Minotto, Renan January 2009 (has links)
Este estudo avaliou pacientes portadores de cromoblastomicose, sendo feita uma categorização clínica em dois grupos, de acordo com a forma clínica da lesão dermatológica: o primeiro composto por indivíduos com lesões elevadas e o segundo formado por casos com lesões planas, com biópsias realizadas antes e depois dos tratamentos. Através de critérios semiquantitativos, os elementos anatomopatológicos foram analisados, constatando-se a presença do padrão granulomatoso chamado granuloma micótico misto organizado, com baixa intensidade em lesões planas e alta em elevadas. Evidenciou-se que pacientes com lesões planas evoluíram bem clinicamente, com exames micológicos negativos e sem recidivas (bons respondedores), porém aqueles com lesões elevadas apresentaram evolução clínica desfavorável, com exames micológicos positivos e doença recidivante ou recalcitrante, apesar dos tratamentos recebidos (maus respondedores). E, entre os componentes histopatológicos reacionais à invasão fúngica, verificou-se associação significativa para fibrose, podendo levar a um pior prognóstico. Estes achados clínicos e histopatológicos conferem a esta patologia uma idéia de polaridade, à guisa dos fenômenos das formas polares da hanseníase, da fagocitose, e dos agentes de baixa virulência. Os autores propõem uma classificação morfológica dos granulomas da CBM em dois tipos polares: granuloma micótico misto organizado (GMMO) polar com alta intensidade dos elementos celulares (que corresponderia ao polar não tuberculóide) e GMMO polar com baixa intensidade (que corresponderia ao polar tuberculóide). / Patients with chromoblastomycosis were studied and dichotomized into two groups according to the clinical lesions: flat and elevated ones which were biopsied before and after treatments. Histopathological structures underwent through semiquantitatively analisys evidencing the mixed organized mycotic granuloma with low intensity of histopathological elements in flat lesions and high in elevated ones. Flat lesions have improved clinically with negative micological studies (good responders) while elevated lesions’ patients did not (bad responders). It was found significant association between evidence of fungus and fibrosis with a poor prognosis. Clinical and histopathological findings suggest a polarity concept to this disease based on the fenomenal polar forms of hanseniasis, fagocitosis and the low virulence agents. The authors proposed a morphological classification of the chromoblastomycosis’ granulomas into two polar types: polar mixed organized mycotic granuloma (MOMG) with high intensity of the cellular elements (like the polar non tuberculoid type) and the polar MOMG with low intensity (like the polar tuberculoid type).
199

O novo Ártico: mudanças ambientais e geopolítica

Souza Júnior, Enoil de January 2015 (has links)
Esta dissertação revisa as mudanças ambientais que ocorreram no Ártico ao longo das últimas décadas e analisa as suas consequências geopolíticas. O interesse na região por parte das nações árticas (Canadá, Dinamarca - Groenlândia, EUA, Finlândia, Islândia, Noruega, Rússia e Suécia) aumentou, principalmente devido ao volume de hidrocarbonetos disponível na região, estimado em 13% do petróleo e 30% do gás natural ainda não descobertos. Durante os últimos 50 anos, o Ártico mostrou a mais rápida tendência de aquecimento no mundo, duas vezes mais que a média mundial, isso tem causado rápidas mudanças ambientais, como a redução do volume das geleiras, o que contribuiu para o aumento do nível médio dos mares; o degelo do permafrost, que libera grandes quantidades de CO2 e CH4 na atmosfera, intensificando o efeito estufa; a migração da vegetação em direção ao Norte, alterando a disponibilidade de alimentos e os padrões de migração dos animais; o aumento da temperatura da superfície do mar, o que pode causar a migração de cardumes de peixes para áreas mais frias. No entanto, a mudança mais rápida naquele ambiente, e a que mais chama a atenção, é a redução da área coberta por gelo marinho no verão. Essa redução favorece a exploração de recursos naturais e também abre o Oceano Ártico à navegação no verão (ou seja, a abertura das passagens do Nordeste e do Noroeste). Os países do Ártico desenvolveram estratégias para lidar com novos desafios decorrentes dessas mudanças, todos se comprometeram a trabalhar pela paz e cooperação, mas, na verdade, é evidente um aumento em exercícios militares na região para exercer a soberania regional. Os países com uma costa no Oceano Ártico (Canadá, Dinamarca, EUA, Noruega e Rússia) planejam expandir suas ZEEs (Zonas Económicas Exclusivas) e algumas reivindicações territoriais se sobrepõem, o que pode ser um novo foco de conflito. Além disso, existe um interesse emergente de nações não-árticas (por exemplo, China, Índia e Singapura) que desejam utilizar as novas rotas marítimas e também participar em consórcios para exploração de recursos naturais. O cenário geopolítico é ainda incerto, Canadá e os EUA ainda não chegaram a um acordo sobre a soberania da Passagem do Noroeste, consideradas águas internacionais por este último, e só a Noruega e a Rússia chegaram a um acordo diplomático sobre suas fronteiras marítimas. Considerando que o Ártico está passando por essas rápidas mudanças ambientais e geopolíticas, é aconselhável que o Brasil atue na região, pelo menos para observar os cenários resultantes de tais modificações. Como uma das primeiras ações, sugere-se a assinatura do Tratado de Svalbard, o que daria ao país o acesso a este arquipélago ártico, tanto para a realização de pesquisa científica como para a possível exploração de recursos naturais. / This dissertation reviews the Arctic environmental changes in recent decades and examines their geopolitical consequences. The interest in the region by the Arctic nations (Canada, Denmark - Greenland, Finland, Iceland, Norway, Russia, Sweden and USA) have increased, mainly due to the volume of hydrocarbons available in the region, estimated at 13% of the oil and 30% of the natural gas yet to be discovered. For the last 50 years, the Arctic has shown the fastest warming trend in the world, twice as much as the worldwide mean, this has caused rapid environmental changes such as the shrinkage of glaciers, which contributed to the mean sea level rise; the permafrost thaw, which releases large amounts of CO2 and CH4 in the atmosphere, intensifying the greenhouse effect; the migration of the vegetation towards the North, changing food availability and the migration patterns of animals; the increase of the ocean surface temperature, which may cause the migration of fish shoals to colder areas. However, the most rapid environmental change, which draws the most attention, is the reduction of the sea ice cover area in the summer. Such reduction favours the exploitation of natural resources in the ocean and also opens the Arctic Ocean to navigation in the summer (i.e., opening of the Northeast and the Northwest passages). The Arctic countries have developed strategies to deal with the new challenges arising from these changes, all have promised to work for peace and cooperation, but, in fact, it is apparent an increase in military exercises in the region to exercise regional sovereignty. Countries with an Arctic Ocean coast (Canada, Denmark, Norway, Russia and USA) plan to expand their EEZs (Exclusive Economic Zones) and some claims overlap, which can be a new focus of conflict. Also, there is an emergent interest of non-Arctic nations (e.g., China, India and Singapore) that want to use the new sea routes and also participate in consortia for natural resources exploitation. The geopolitical scenario is still uncertain, Canada and the US have not yet reached an agreement on the sovereignty of the Northwest Passage, considered international waters by the latter, and only Norway and Russia reached a diplomatic agreement on their maritime boundaries. Considering that the Arctic is undergoing these rapid environmental and geopolitical changes, it is advisable that Brazil acts in the region, at least to observe the scenarios resulting from such modifications. As one of the first actions, it is suggested the signing of the Svalbard Treaty, which would give to the country access to this Arctic archipelago, both for conducting scientific research as for possible exploitation of natural resources.
200

Maternal Denning Phenology and Substrate Selection of Polar Bears (<em>Ursus maritimus</em>) in the Southern Beaufort and Chukchi Seas

Olson, Jay Wesley 01 December 2015 (has links)
Loss of sea ice due to global warming may affect the phenology and distribution of polar bear (Ursus maritimus) denning by altering access to denning habitats. We examined trends in the selection of maternal denning substrate (land versus sea-ice denning) in the southern Beaufort Sea (SB), addressing the potential influence of summer land-use and fall sea-ice conditions on substrate selection. We developed an algorithm based on statistical process control methods to remotely identify denning bears and estimate denning phenology from temperature sensor data collected on collars deployed 1985–2013 in the SB and Chukchi Sea (CS). We evaluated cub survival relative to den entrance, emergence, and duration, and examined differences in the phenology of land and sea-ice dens. Land denning in the SB was more common during years when ice retreated farther from the coast and off of the continental shelf in September. All SB bears that occupied land prior to denning subsequently denned on land; however, only 29% of denning bears that summered on sea ice denned on land. Den entrance and duration in the SB and CS were similar, although CS bears emerged later. Land dens were occupied longer than those on ice. Bears later observed with cubs remained in dens 23 days longer and emerged from denning 17 days later on average than bears that denned but were subsequently observed without cubs, suggesting that den exit dates are related to cub survival. The increase in land-based denning in the SB when sea ice retreated farther from shore, along with the positive correlation between fall land-use and land denning, suggest that further sea-ice declines may result in continued increases of onshore denning. Growing numbers of denning females along the coast may increase the potential for human-bear interactions.

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