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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.
51

Palliative Care for Pancreatic and Periampullary Cancer

Perone, Jennifer A., Riall, Taylor S., Olino, Kelly 12 1900 (has links)
Most patients with pancreatic cancer will present with metastatic or locally advanced disease. Unfortunately, most patients with localized disease will experience recurrence even after multimodality therapy. As such, pancreatic cancer patients arrive at a common endpoint where decisions pertaining to palliative care come to the forefront. This article summarizes surgical, endoscopic, and other palliative techniques for relief of obstructive jaundice, relief of duodenal or gastric outlet obstruction, and relief of pain due to invasion of the celiac plexus. It also introduces the utility of the palliative care triangle in clarifying a patient's and family's goals to guide decision making.
52

Blogging in the Writing Classroom: A move Toward Dialogue, Design, and Citizenship

Foster, Meghan E. 01 January 2007 (has links)
A bridge connecting student's new multi-modal abilities and schooling can be built. Students choose between school and other activities outside of the classroom walls (and sometimes even inside the classroom) and schoolwork seems to be losing ground in the battle of spare time more and more. Students could benefit from an electronic space that incorporates their media know-how, their studies, and others in the classroom. Blogs, or weblogs, provide just that type of space by relying on the user's insightful writing and creativity to retain a dynamic position in the Internet blogging community. Blogs have the ability to better the writing classroom by providing an educational forum for dialogue, spatial creativity, and social awareness.
53

Avaliação da eficácia da injeção de ropivacaína nos músculos escalenos anterior e médio guiado por ultrassonografia no tratamento da síndrome do desfiladeiro torácico / Evaluation of the efficacy of ropivacaine injection in the anterior and middle scalene muscles guided by ultrasonography in the treatment of thoracic outlet syndrome

Rached, Roberto Del Valhe Abi 15 January 2019 (has links)
Síndrome do Desfiladeiro Torácico (SDT) abrange manifestações nervosas e/ou vasculares. Pode haver dor e/ou parestesia em braço, antebraço e mão mesmo em repouso, assim como sensação de dormência, força diminuída ou dificuldades durante atividades com elevação dos braços mesmo com exame eletrofisiológico negativo, forma neurológica não verdadeira. Na intenção do aprimoramento da técnica, tem se usado ultrassom na infiltração muscular. Objetivo: avaliar a eficácia da injeção de ropivacaína 0,375% nas doses de 2,5ml em cada ventre dos músculos escalenos anterior e médio, guiado por ultrassonografia, no tratamento da Síndrome do desfiladeiro torácico neurogênico inespecífico através dos protocolo de funcionalidade DASH - DISABILITIES OF THE ARM, SHOULDER, AND HAND e EVA ou VAS - escala visual analógica comparado com o toque cutâneo com mesmo conjunto seringa-agulha nos mesmos pontos de acesso de onde seria a injeção. Método: ensaio clínico, controlado por placebo, aleatorizado, duplo cego, com dois braços paralelos. Os dados clínicos foram coletados por meio de um protocolo padronizado. Foram incluídos nesse estudo sujeitos com diagnóstico de Síndrome do Desfiladeiro Torácico Neurogênico inespecífico, que contemplaram os critérios de inclusão com dor em membros superiores e/ou cervicalgia sem radiculopatia ou comprometimento neurológico do membro em questão por causas radiculares compressivas ou encefálicas. O desfecho primário foi a funcionalidade avaliada pela escala Disabilitie of the Arm, Shoulder and Hand - DASH validada no Brasil e a melhora da dor, mensurada através da Escala Visual Analógica - EVA. O tempo das avaliações foram T0= antes da intervenção; T1= imediatamente após, T2= 1 semana, T3=4 semanas e T4= 12 semanas, sendo que para o T1 não foi aplicado o DASH. Resultados: o total de pacientes foram 38, sendo 19 no grupo controle (CT) e 19 no grupo intervenção (INT). Os pacientes e os controles foram comparáveis com relação as variáveis idade, gênero, escolaridade, índice de massa corporal (IMC), atividade física, tabagismo, doenças crônicas associadas (p > 0,05). Com relação ao DASH, de forma estatisticamente significante (p > 0,05), é possível afirmar que o grupo intervenção apresentou melhora da funcionalidade a partir de 4 semanas e essa melhora se manteve, até a décima segunda semana. Não houve diferença estatisticamente significante entre os grupos CT e INT, quanto a escala VAS nos 5 momentos avaliados (VAS inicial grupo total p < 0,001). Conclusão: Em termos práticos conclui-se que injeção de ropivacaína 0,375% nas doses de 2,5ml em cada ventre dos músculos escalenos anterior e médio, guiado por ultrassonografia, no tratamento da Síndrome do desfiladeiro torácico neurogênico inespecífico auxilia na melhora da função entretanto, em relação a melhora da dor não há diferença entre os grupos / Thoracic Outlet Syndrome (TOS) encompasses nerve and/or vascular manifestations. There may be pain and/or paresthesia in the arm, forearm and hand even at rest, as well as numbness, decreased strength or difficulties during activities with elevation of the arms even with negative electrophysiological examination, non-true neurological form. In order to improve the technique, ultrasound has been used in muscle infiltration. Objective: to evaluate the efficacy of 0.375% ropivacaine injection in the doses of 2.5 ml in each muscular belly of the anterior and middle scolenes muscles, guided by ultrasonography, in the treatment of nonspecific Thoracic Outlet Syndrome through DASH - DISABILITIES OF THE ARM, SHOULDER, AND HAND and VAS - visual analogue scale compared to the skin touch with the same syringe-needle set at the same access points from where the injection would be. Method: A randomized, double-blind, placebo-controlled clinical trial with two parallel arms. Clinical data were collected through a standardized protocol. Included in this study were subjects with a diagnosis of nonspecific, Thoracic Outlet Syndrome who included criteria for inclusion with pain in upper limbs and / or neck pain without radiculopathy or neurological impairment of the limb in question due to compressive or encephalic root causes. The primary endpoint was the functionality evaluated by the Disabilitie of the Arm, Shoulder and Hand - DASH scale validated in Brazil and the improvement of pain, measured by the Visual Analogue Scale - VAS. The time of the evaluations were T0 = before the intervention; T1 = immediately after, T2 = 1 week, T3 = 4 weeks and T4 = 12 weeks, and for T1 the DASH was not applied. Results: the total number of patients was 38, 19 in the control group (CT) and 19 in the intervention group (INT). Patients and controls were comparable in relation to the variables age, gender, schooling, body mass index (BMI), physical activity, smoking, and associated chronic diseases (p > 0.05). With regard to DASH, statistically significant (p > 0.05), it is possible to state that the intervention group showed improvement of the functionality after 4 weeks and this improvement was maintained until the twelfth week. There was no statistically significant difference significant difference between the groups CT and INT, and the VAS scale in the 5 moments evaluated (initial ARV total group p < 0.001). Conclusion: In practical terms, it is concluded that ropivacaine injection 0.375% in doses of 2.5 ml in each anterior and middle scalene muscles, guided by ultrasonography, in the treatment of nonspecific neurogenic thoracic defibrillary syndrome helps to improve function, however, in relation to pain improvement there is no difference between the groups
54

Retração das geleiras Drummond e Widdowson em respostas às recentes mudanças ambientais na Península Antártica (1957-2016) seus espaços e agentes

Simões, Carolina Lorenz January 2017 (has links)
Este trabalho investiga a dinâmica de retração frontal de duas geleiras de maré, Drummond (66°40'S, 65°43'O) e Widdowson (66°43'S, 65°46'O), na costa ocidental da Península Antártica. O estudo usou fotografias aéreas e imagens satelitais LANDSAT (a partir de 1986) para determinar a variação de área dessas geleiras no período 1957–2015 e analisar a sensibilidade às recentes mudanças ambientais na Península Antártica. O modelo digital de elevação AsterGDEM2 foi usado para caracterizar a morfologia e morfometria da bacia de drenagem dessas massas de gelo. A análise estatística dos dados de temperatura média anual da Estação Vernadsky (65°14’ S, 64°15’ O) mostra tendência ao aquecimento atmosférico no período 1950–2015 (0,047°C ano-1) nesta parte da Península Antártica ocidental. As frentes das duas geleiras retraíram ao longo dos últimos 68 anos, no entanto a geleira Widdowson apresentou uma perda maior (36,03 km2, ou 16,81% da área original) e uma linha de neve mais elevada (200 m a.n.m. em 2016) do que a geleira Drummond (18,84 km2, ou 4,26% da área original; linha de neve a 100 m a.n.m. em 2016) no período. Essa diferença na retração da duas geleiras, lado a lado e com a mesma orientação de fluxo do gelo, são atribuídas as diferentes declividades da superfície e proporção da área de acumulação sobre a área total. A geleira de menor área, Widdowson, somente atingiu um ponto de estabilização (apoiada ao embasamento rochoso lateral) em 2001, enquanto a frente da Drummond estabilizou-se em 1974. Além disso, a geleira Widdowson é mais íngreme no setor frontal, o que pode ter influenciado na taxa de desprendimento de icebergs e gerado um deslizamento basal mais eficiente, aumentando a velocidade de fluxo do gelo e, por consequência, aumentando as taxas de retração. Esses resultados condizem com estudos para outras geleiras de descarga com frentes flutuantes na Península Antártica, as quais são mais sensíveis às mudanças climáticas. A dinâmica dessas geleiras também é influenciada por mudanças nas forçantes oceânicas, taxas de precipitação, derretimento superficial e morfologias diferentes do embasamento rochoso; esses pontos devem ser tratados em trabalhos futuros. Como subproduto desta investigação, foi gerado um banco de dados em SIG para a continuidade do monitoramento das duas geleiras. / This work investigates the ice front retreat dynamics of two tidewater glaciers, Drummond (66°40'S, 65°43'W) and Widdowson (66°43'S, 65°46'W), on the western coast of the Antarctic Peninsula, associated with environmental changes in the last six decades. The study uses aerial photographs and LANDSAT satellite images (from 1986 onwards) to determine these glaciers area variations in the period 1957–2015 and to analyze their sensitivity to recent environmental changes in the Antarctic Peninsula. The digital elevation model ASTERDEM2 was edited by a routine to characterize the morphology and the morphometry of the drainage basins of these ice masses. The statistical analysis of the updated mean annual temperature data from the Faraday/Vernadsky station (65°14’ S, 64°15’ W) shows a trend towards regional atmospheric warming in the period 1950–2015 (0.047°C year-1) in this part of the West Antarctic Peninsula. The ice fronts of these two glaciers have retreated for the last 68 years, however, the Widdowson Glacier had a more significant loss (36.03 km² or 16.81% of the original area) and a higher snow line elevation (200 m a.s.l. in 2016) than the Drummond Glacier (18.84 km2, or 4.26% of the original area; snow line at 90 m a.s.l. in 2016) in the period. This retreat difference of the two glaciers, side by side and with the same ice flow orientation is attributed to different surface slopes and accumulation area proportion over the total area. The smaller area glacier, Widdowson, has shown to be more sensitive to environmental changes and only reached a stabilization point (supported to the lateral bedrock) in 2001, while the Drummond front stabilized in 1974. In addition, the Widdowson glacier is steeper in the frontal sector, which may have influenced on the calving rate and generate a more efficient basal slip, increasing the ice flow rate and, consequently, increasing the retraction rate. These results are consistent with studies for other floating outlet glaciers with calving in the Antarctic Peninsula, which are more sensitive to climate change. The dynamics of these glaciers is also influenced by changes in ocean forcing, precipitation rates, surface melting and bedrock morphology; these points should be investigated in future works. As a by-product of this research, a GIS database wasgenerated for a continuous monitoring of the two glaciers.
55

Klinikinių ir urodinaminių požymių svarba prognozuojant gerybinės prostatos hiperplazijos chirurginio gydymo rezultatus / Predictive value of clinical and urodynamic factors on the outcome of surgical treatment of benign prostatic hyperplasia

Trumbeckas, Darius 26 January 2006 (has links)
INTRODUCTION Benign prostatic hyperplasia (BPH) is the most common pathological condition of aged men which significantly impairs the quality of life status. Though pharmacotherapy with adrenoblockers and 5-alpha reductase inhibitors markedly decreased the rate of surgical interventions, BPH surgery still constitutes the main workload (around ¼ of total) of urologists in the department. The results of the observational study performed by Barry et al. show that the probability of surgical treatment of BPH during the period of 4 years for subjects with mild symptoms equals to 10%, and in case of moderate and severe symptoms - 24% and 39%, respectively. According to the data of large multicenter study performed with 7,588 men in Asia and Australia, moderate and severe symptoms are present in 29%, 40%, and 56% of men in their fifth, sixth, and seventh decade of life, respectively. Symptoms are the main driving force of BPH treatment, but their correlation with residual urine, objective findings of uroflowmetry and invasive urodynamics is only poor. The association of various parameters with the outcomes of surgical treatment is complicated and still not completely investigated. Therefore finding parameters that predict the outcome of surgical BPH treatment is important. According to the literature, unfavorable outcomes of transurethral resection are present in around 15-30% of men with symptomatic BPH. This is mostly associated with inadequate preoperative evaluation, not fully... [to full text]
56

Modelling air―water flows in bottom outlets of dams

Liu, Ting January 2014 (has links)
If air is entrained in a bottom outlet of a dam in an uncontrolled way, the resulting air pockets may cause problems such as blowback, blowout and loss of discharge capacity. In order to provide guidance for bottom outlet design and operation, this study examines how governing parameters affect air entrainment, air-pocket transport and de-aeration and the surrounding flow structure in pipe flows. Both experimental and numerical approaches are used. Air can be entrained into the bottom outlet conduit due to vortex formation at the intake if the intake submergence is not sufficient. The influent of the intake entrance profiles and channel width on the critical submergence were studied in the experiment. The experimental study was performed to investigate the incipient motion of air pockets in pipes with rectangular and circular cross sections. The critical velocity is dependent on pipe slope, pipe diameter, pipe roughness and air-pocket volume. If the pipe is horizontal, air removal is generally easier in a rectangular pipe than in a circular pipe. However, if the pipe is downward-inclined, air removal is easier in a circular pipe. When a bottom outlet gate opens, air can become entrained into the conduit in the gate shaft downstream of the gate. Using FLUENT software, the transient process of air entrainment into a prototype bottom outlet during gate opening is simulated in three dimensions. The simulations show in the flow-pattern changes in the conduit and the amount of air entrainment in the gate shaft. The initial conduit water level affects the degree of air entrainment. A de-aeration chamber is effective in reducing water surface fluctuations at blowout. High-speed particle image velocimetry (HSPIV) were applied to investigate the characteristics of the flow field around a stationary air pocket in a fully developed horizontal pipe flow. The air pocket generates a horseshoe vortex upstream and a reverse flow downstream. A shear layer forms from the separation point. Flow reattachment is observed for large air pockets. The air―water interface moves with the adjacent flow. A similarity profile is obtained for the mean streamwise velocity in the shear layer beneath the air pocket. / <p>QC 20140211</p>
57

Value space: an architectural geography of new retail formats on southern Vancouver Island

McGrail, Justin 14 June 2010 (has links)
The subject of this dissertation is the architectural history of big-box stores on Southern Vancouver Island since their arrival in 1992. It examines the architecture and cultural significance of stores located in the Regional District of Nanaimo, the Cowichan Valley Regional District, and the Capital Regional District. This study hypothesizes that big-box stores are, in terms of their architecture, retailing formats, and consumption practices, central locations and vehicles for the reproduction of capitalist social relations. In the postmodern or Late Capitalist era. these relations have emphasized consumption over production, and have exerted a deep influence on everyday life and political economy in urban Canada. This study interprets the architectural and social spaces of New Retail Formats (NRFs) through a Marxist perspective, and uses the inter-disciplinary methods of vernacular architecture studies and architectural-geography. I have evaluated the big-box store in terms of typology, distribution, and social operation. I have also placed them in the context of North American architectural history, especially in relation to shopping centres. I argue that big-box stores produce, consume, and reproduce distinctive forms of social space, which I have named "value space". Value space is the set of social and spatial relationships found within big-box stores that are shaped by both retailers and consumers, and which are focused on low-priced commodities. Value space is a contemporary and clear example of what Karl Marx and Henri Lefebvre each identified as key to capitalism's survival: the reproduction of the relations of production and consumption. In the same way that factory relationships also shape life beyond the factory, the value space of big-box stores is also produced, consumed, and reproduced in other social and professional practices, such as urban planning and municipal politics. The aims of my study were: to document the history of this new architectural type; to explain the place of big-box store development in municipal political economy; and, to examine the role of big-box stores in the reproduction of capitalist urban space on Southern Vancouver Island. In doing so, I argue that big-box stores are engines and symbols of urban development that foster increased consumption, support the socio-economic status quo, and refashion natural and social environments in accordance with the values of capitalism. I believe big-box stores are the architectural subject of greatest contemporary importance on Southern Vancouver Island. Few other buildings types today generate similar feelings - for and against - as do big-box stores. They are at once a building type, a retail format, and a symbol of contemporary urban development. Their importance comes from their size, from the scale of their operations, and from their impacts on municipal politics, urban planning, transportation infrastructure, regional ecosystems, and community life. The retailing and consumption practices they house, facilitate and manage contain the seeds of, or needs for, future consumption. This makes NRFs economic and symbolic centres for the reproduction of the relations of production and consumption.
58

Retração das geleiras Drummond e Widdowson em respostas às recentes mudanças ambientais na Península Antártica (1957-2016) seus espaços e agentes

Simões, Carolina Lorenz January 2017 (has links)
Este trabalho investiga a dinâmica de retração frontal de duas geleiras de maré, Drummond (66°40'S, 65°43'O) e Widdowson (66°43'S, 65°46'O), na costa ocidental da Península Antártica. O estudo usou fotografias aéreas e imagens satelitais LANDSAT (a partir de 1986) para determinar a variação de área dessas geleiras no período 1957–2015 e analisar a sensibilidade às recentes mudanças ambientais na Península Antártica. O modelo digital de elevação AsterGDEM2 foi usado para caracterizar a morfologia e morfometria da bacia de drenagem dessas massas de gelo. A análise estatística dos dados de temperatura média anual da Estação Vernadsky (65°14’ S, 64°15’ O) mostra tendência ao aquecimento atmosférico no período 1950–2015 (0,047°C ano-1) nesta parte da Península Antártica ocidental. As frentes das duas geleiras retraíram ao longo dos últimos 68 anos, no entanto a geleira Widdowson apresentou uma perda maior (36,03 km2, ou 16,81% da área original) e uma linha de neve mais elevada (200 m a.n.m. em 2016) do que a geleira Drummond (18,84 km2, ou 4,26% da área original; linha de neve a 100 m a.n.m. em 2016) no período. Essa diferença na retração da duas geleiras, lado a lado e com a mesma orientação de fluxo do gelo, são atribuídas as diferentes declividades da superfície e proporção da área de acumulação sobre a área total. A geleira de menor área, Widdowson, somente atingiu um ponto de estabilização (apoiada ao embasamento rochoso lateral) em 2001, enquanto a frente da Drummond estabilizou-se em 1974. Além disso, a geleira Widdowson é mais íngreme no setor frontal, o que pode ter influenciado na taxa de desprendimento de icebergs e gerado um deslizamento basal mais eficiente, aumentando a velocidade de fluxo do gelo e, por consequência, aumentando as taxas de retração. Esses resultados condizem com estudos para outras geleiras de descarga com frentes flutuantes na Península Antártica, as quais são mais sensíveis às mudanças climáticas. A dinâmica dessas geleiras também é influenciada por mudanças nas forçantes oceânicas, taxas de precipitação, derretimento superficial e morfologias diferentes do embasamento rochoso; esses pontos devem ser tratados em trabalhos futuros. Como subproduto desta investigação, foi gerado um banco de dados em SIG para a continuidade do monitoramento das duas geleiras. / This work investigates the ice front retreat dynamics of two tidewater glaciers, Drummond (66°40'S, 65°43'W) and Widdowson (66°43'S, 65°46'W), on the western coast of the Antarctic Peninsula, associated with environmental changes in the last six decades. The study uses aerial photographs and LANDSAT satellite images (from 1986 onwards) to determine these glaciers area variations in the period 1957–2015 and to analyze their sensitivity to recent environmental changes in the Antarctic Peninsula. The digital elevation model ASTERDEM2 was edited by a routine to characterize the morphology and the morphometry of the drainage basins of these ice masses. The statistical analysis of the updated mean annual temperature data from the Faraday/Vernadsky station (65°14’ S, 64°15’ W) shows a trend towards regional atmospheric warming in the period 1950–2015 (0.047°C year-1) in this part of the West Antarctic Peninsula. The ice fronts of these two glaciers have retreated for the last 68 years, however, the Widdowson Glacier had a more significant loss (36.03 km² or 16.81% of the original area) and a higher snow line elevation (200 m a.s.l. in 2016) than the Drummond Glacier (18.84 km2, or 4.26% of the original area; snow line at 90 m a.s.l. in 2016) in the period. This retreat difference of the two glaciers, side by side and with the same ice flow orientation is attributed to different surface slopes and accumulation area proportion over the total area. The smaller area glacier, Widdowson, has shown to be more sensitive to environmental changes and only reached a stabilization point (supported to the lateral bedrock) in 2001, while the Drummond front stabilized in 1974. In addition, the Widdowson glacier is steeper in the frontal sector, which may have influenced on the calving rate and generate a more efficient basal slip, increasing the ice flow rate and, consequently, increasing the retraction rate. These results are consistent with studies for other floating outlet glaciers with calving in the Antarctic Peninsula, which are more sensitive to climate change. The dynamics of these glaciers is also influenced by changes in ocean forcing, precipitation rates, surface melting and bedrock morphology; these points should be investigated in future works. As a by-product of this research, a GIS database wasgenerated for a continuous monitoring of the two glaciers.
59

Retração das geleiras Drummond e Widdowson em respostas às recentes mudanças ambientais na Península Antártica (1957-2016) seus espaços e agentes

Simões, Carolina Lorenz January 2017 (has links)
Este trabalho investiga a dinâmica de retração frontal de duas geleiras de maré, Drummond (66°40'S, 65°43'O) e Widdowson (66°43'S, 65°46'O), na costa ocidental da Península Antártica. O estudo usou fotografias aéreas e imagens satelitais LANDSAT (a partir de 1986) para determinar a variação de área dessas geleiras no período 1957–2015 e analisar a sensibilidade às recentes mudanças ambientais na Península Antártica. O modelo digital de elevação AsterGDEM2 foi usado para caracterizar a morfologia e morfometria da bacia de drenagem dessas massas de gelo. A análise estatística dos dados de temperatura média anual da Estação Vernadsky (65°14’ S, 64°15’ O) mostra tendência ao aquecimento atmosférico no período 1950–2015 (0,047°C ano-1) nesta parte da Península Antártica ocidental. As frentes das duas geleiras retraíram ao longo dos últimos 68 anos, no entanto a geleira Widdowson apresentou uma perda maior (36,03 km2, ou 16,81% da área original) e uma linha de neve mais elevada (200 m a.n.m. em 2016) do que a geleira Drummond (18,84 km2, ou 4,26% da área original; linha de neve a 100 m a.n.m. em 2016) no período. Essa diferença na retração da duas geleiras, lado a lado e com a mesma orientação de fluxo do gelo, são atribuídas as diferentes declividades da superfície e proporção da área de acumulação sobre a área total. A geleira de menor área, Widdowson, somente atingiu um ponto de estabilização (apoiada ao embasamento rochoso lateral) em 2001, enquanto a frente da Drummond estabilizou-se em 1974. Além disso, a geleira Widdowson é mais íngreme no setor frontal, o que pode ter influenciado na taxa de desprendimento de icebergs e gerado um deslizamento basal mais eficiente, aumentando a velocidade de fluxo do gelo e, por consequência, aumentando as taxas de retração. Esses resultados condizem com estudos para outras geleiras de descarga com frentes flutuantes na Península Antártica, as quais são mais sensíveis às mudanças climáticas. A dinâmica dessas geleiras também é influenciada por mudanças nas forçantes oceânicas, taxas de precipitação, derretimento superficial e morfologias diferentes do embasamento rochoso; esses pontos devem ser tratados em trabalhos futuros. Como subproduto desta investigação, foi gerado um banco de dados em SIG para a continuidade do monitoramento das duas geleiras. / This work investigates the ice front retreat dynamics of two tidewater glaciers, Drummond (66°40'S, 65°43'W) and Widdowson (66°43'S, 65°46'W), on the western coast of the Antarctic Peninsula, associated with environmental changes in the last six decades. The study uses aerial photographs and LANDSAT satellite images (from 1986 onwards) to determine these glaciers area variations in the period 1957–2015 and to analyze their sensitivity to recent environmental changes in the Antarctic Peninsula. The digital elevation model ASTERDEM2 was edited by a routine to characterize the morphology and the morphometry of the drainage basins of these ice masses. The statistical analysis of the updated mean annual temperature data from the Faraday/Vernadsky station (65°14’ S, 64°15’ W) shows a trend towards regional atmospheric warming in the period 1950–2015 (0.047°C year-1) in this part of the West Antarctic Peninsula. The ice fronts of these two glaciers have retreated for the last 68 years, however, the Widdowson Glacier had a more significant loss (36.03 km² or 16.81% of the original area) and a higher snow line elevation (200 m a.s.l. in 2016) than the Drummond Glacier (18.84 km2, or 4.26% of the original area; snow line at 90 m a.s.l. in 2016) in the period. This retreat difference of the two glaciers, side by side and with the same ice flow orientation is attributed to different surface slopes and accumulation area proportion over the total area. The smaller area glacier, Widdowson, has shown to be more sensitive to environmental changes and only reached a stabilization point (supported to the lateral bedrock) in 2001, while the Drummond front stabilized in 1974. In addition, the Widdowson glacier is steeper in the frontal sector, which may have influenced on the calving rate and generate a more efficient basal slip, increasing the ice flow rate and, consequently, increasing the retraction rate. These results are consistent with studies for other floating outlet glaciers with calving in the Antarctic Peninsula, which are more sensitive to climate change. The dynamics of these glaciers is also influenced by changes in ocean forcing, precipitation rates, surface melting and bedrock morphology; these points should be investigated in future works. As a by-product of this research, a GIS database wasgenerated for a continuous monitoring of the two glaciers.
60

Modelling the effects of climate change on ice dynamics at Kangerlussuaq Glacier, Greenland

Barnett, Jamie January 2021 (has links)
A consequence of climate change is rising global sea levels, predicted to bring increased socio-economic and environmental impacts to coastal communities. The Greenland Ice Sheet has become a prominent contributor to rising sea levels, a consequence of the Arctic warming at twice the rate of the global average. Mass loss from the ice sheet is separated between changes in surface mass balance and ice discharge at marine terminating outlet glaciers, with the later dominating mass loss over the past fifty years. While advances in ice sheet modelling have provided greater clarity on Greenland’s future mass loss, there remains inefficiencies in modelling the response of outlet glaciers in Greenland’s fjords. This thesis aims to provide greater insight into behaviour of Kangerlussuaq Glacier, SE Greenland, by employing a 2D flowline model to understand the processes governing ice dynamics and to explore how the glacier may respond to a warming climate. Results indicate that the presence of a winter ice mélange is the principle dictator of Kangerlussuaq Glacier’s behaviour and likely protects against further retreat towards a reverse sloped section of bedrock. However, if such a retreat does materialise, then large overdeepenings in Kangerlussuaq Fjord raise the spectre of uncontrollable retreat and excessive mass loss.

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