An iron-nickel meteorite characterization using different experimental techniques

Dissertação de Mestrado em Física, apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra.Todos os anos, milhões de meteoróides entram na nossa atmosfera. O termo meteoróides é apenas uma designação baseada no tamanho (mais pequeno que um asteoróide). Aqui refere-se a partículas provenientes de cometas aquando a sua travessia pelo sistema solar. Quando algumas destas partículas entram na atmosfera da Terra, interagem com esta, formando uma "bola de fogo"por ignição. A este efeito refere-se como um meteoro ou uma estrela cadente, o que é observável no céu. Alguns destes meteoros, os que sobrevivem à passagem pela atmosfera terrestre, atingem a crosta da Terra. A estes chamamos de meteoritos e a sua composição é diferente de qualquer outro material existente à superfície da Terra. Os meteoritos podem ser encontrados nos mais variados tamanhos e massas, e geralmente sob a forma de meteoritos metálicos, metálico-rochosos ou rochosos. O estudo destes é importante para o conhecimento do Universo e das condições particulares em que se formaram. Esta tese propõe o estudo de um meteorito metálico usando diferentes técnicas: metalografia, diffracção de raios-X, fluorescência de raios-X, microscopia electrónica de varrimento, espectroscopia de Mössbauer e activação de neutrões. A interpretação dos resultados obtidos levou à classificação do meteorito como uma IIAB ou IIG hexadrite

Tendência Temporal no Implante Percutâneo de Bioprótese Aórtica: Análise de 10 Anos do Registro TAVIDOR

Resumo Fundamento O implante percutâneo de bioprótese valvar aórtica (TAVI) consolidou-se como opção terapêutica da estenose aórtica de grau importante. Dados sobre as características evolutivas dos procedimentos e dos resultados obtidos com a técnica ao longo da última década, em escala nacional, são desconhecidos. Objetivos Analisar a tendência temporal referente ao perfil demográfico, características dos procedimentos e desfechos hospitalares de pacientes submetidos a TAVI na Rede D’Or São Luiz. Métodos Registro observacional envolvendo 29 instituições nacionais. Comparou-se características dos procedimentos realizados de 2012 a 2017 (Grupo 1) e de 2018 a 2023 (Grupo 2). Foram considerados significantes os resultados com valor de p 8%. Foi mais frequente o emprego de anestesia geral, monitorização ecocardiográfica transesofágica e via de acesso por dissecção. Maior taxa de sucesso do procedimento (95,4% versus 89,5%; p = 0,018) foi aferida em implantes efetivados a partir de 2018, assim como menor mortalidade (3,9% versus 11,6%; p = 0,004) e necessidade de marcapasso definitivo (8,5% versus 17,9%; p = 0,008). Conclusões A análise temporal de 10 anos do Registro TAVIDOR demonstra uma queda na complexidade clínica dos pacientes. Além disso, o avanço para técnicas de implante minimalistas, somadas à evolução tecnológica dos dispositivos, podem ter contribuído para desfechos favoráveis dentre aqueles cujo implante ocorreu no último quinquênio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Nationwide access to endovascular treatment for acute ischemic stroke in portugal

Publisher Copyright: Copyright Ordem dos M dicos 2021.Introduction: Since the publication of endovascular treatment trials and European Stroke Guidelines, Portugal has re-organized stroke healthcare. The nine centers performing endovascular treatment are not equally distributed within the country, which may lead to differential access to endovascular treatment. Our main aim was to perform a descriptive analysis of the main treatment metrics regarding endovascular treatment in mainland Portugal and its administrative districts. Material and Methods: A retrospective national multicentric cohort study was conducted, including all ischemic stroke patients treated with endovascular treatment in mainland Portugal over two years (July 2015 to June 2017). All endovascular treatment centers contributed to an anonymized database. Demographic, stroke-related and procedure-related variables were collected. Crude endovascular treatment rates were calculated per 100 000 inhabitants for mainland Portugal, and each district and endovascular treatment standardized ratios (indirect age-sex standardization) were also calculated. Patient time metrics were computed as the median time between stroke onset, first-door, and puncture. Results: A total of 1625 endovascular treatment procedures were registered. The endovascular treatment rate was 8.27/100 000 inhabitants/year. We found regional heterogeneity in endovascular treatment rates (1.58 to 16.53/100 000/year), with higher rates in districts closer to endovascular treatment centers. When analyzed by district, the median time from stroke onset to puncture ranged from 212 to 432 minutes, reflecting regional heterogeneity. Discussion: Overall endovascular treatment rates and procedural times in Portugal are comparable to other international registries. We found geographic heterogeneity, with lower endovascular treatment rates and longer onset-to-puncture time in southern and inner regions. Conclusion: The overall national rate of EVT in the first two years after the organization of EVT-capable centers is one of the highest among European countries, however, significant regional disparities were documented. Moreover, stroke-onset-to-first-door times and in-hospital procedural times in the EVT centers were comparable to those reported in the randomized controlled trials performed in high-volume tertiary hospitalspublishersversionpublishe

Acesso a Tratamento Endovascular para Acidente Vascular Cerebral Isquémico em Portugal

Introduction: Since the publication of endovascular treatment trials and European Stroke Guidelines, Portugal has re-organized stroke healthcare. The nine centers performing endovascular treatment are not equally distributed within the country, which may lead to differential access to endovascular treatment. Our main aim was to perform a descriptive analysis of the main treatment metrics regarding endovascular treatment in mainland Portugal and its administrative districts. Material and Methods: A retrospective national multicentric cohort study was conducted, including all ischemic stroke patients treated with endovascular treatment in mainland Portugal over two years (July 2015 to June 2017). All endovascular treatment centers contributed to an anonymized database. Demographic, stroke-related and procedure-related variables were collected. Crude endovascular treatment rates were calculated per 100 000 inhabitants for mainland Portugal, and each district and endovascular treatment standardized ratios (indirect age-sex standardization) were also calculated. Patient time metrics were computed as the median time between stroke onset, first-door, and puncture. Results: A total of 1625 endovascular treatment procedures were registered. The endovascular treatment rate was 8.27/100 000 inhabitants/year. We found regional heterogeneity in endovascular treatment rates (1.58 to 16.53/100 000/year), with higher rates in districts closer to endovascular treatment centers. When analyzed by district, the median time from stroke onset to puncture ranged from 212 to 432 minutes, reflecting regional heterogeneity. Conclusion: The overall national rate of EVT in the first two years after the organization of EVT-capable centers is one of the highest among European countries, however, significant regional disparities were documented. Moreover, stroke-onset-to-first-door times and in-hospital procedural times in the EVT centers were comparable to those reported in the randomized controlled trials performed in high-volume tertiary hospitals.Introdução: A aprovação do tratamento endovascular para o acidente vascular cerebral isquémico obrigou à reorganização dos cuidados de saúde em Portugal. Os nove centros que realizam tratamento endovascular não estão distribuídos equitativamente pelo território, o que poderá causar acesso diferencial a tratamento. O principal objetivo deste estudo é realizar uma análise descritiva da frequência e métricas temporais do tratamento endovascular em Portugal continental e seus distritos. Material e Métodos: Estudo de coorte nacional multicêntrico, incluindo todos os doentes com acidente vascular cerebral isquémico submetidos a tratamento endovascular em Portugal continental durante um período de dois anos (julho 2015 a junho 2017). Foram colhidos dados demográficos, relacionados com o acidente vascular cerebral e variáveis do procedimento. Taxas de tratamento endovascular brutas e ajustadas (ajuste indireto a idade e sexo) foram calculadas por 100 000 habitantes/ano para Portugal continental e cada distrito. Métricas de procedimento como tempo entre instalação, primeira porta e punção foram também analisadas. Resultados: Foram registados 1625 tratamentos endovasculares, indicando uma taxa bruta nacional de tratamento endovascular de 8,27/100 000 habitantes/ano. As taxas de tratamento endovascular entre distritos variaram entre 1,58 e 16,53/100 000/ano, com taxas mais elevadas nos distritos próximos a hospitais com tratamento endovascular. O tempo entre sintomas e punção femural entre distritos variou entre 212 e 432 minutos. Conclusão: Portugal continental apresenta uma taxa nacional de tratamento endovascular elevada, apresentando, contudo, assimetrias regionais no acesso. As métricas temporais foram comparáveis com as observadas nos ensaios clínicos piloto

Entre o oficial e o costumeiro: o exercício dos poderes e a espacialização da ruralidade no centro da América do Sul (primeira metade do século XVIII)

Analisamos aqui a relação entre o sistema administrativo português e a formação de ambientes rurais no centro da América do Sul, em territórios que, na primeira metade do século XVIII, integravam o extremo oeste do Estado do Brasil, no âmbito administrativo da capitania de São Paulo. A partir de um enfoque local, examinando correspondências entre autoridades metropolitanas e cartas de sesmarias, este artigo dialoga com a produção histórica sobre a administração portuguesa na América, buscando reconstruir aspectos generalizantes que possam revelar características estruturais da conquista da terra e da formação de ambientes rurais nos territórios portugueses na América.In this article we analyze the relationship between the Portuguese administrative system and formation of rural environments in the center of South America, in territories that in the first half of the eighteenth century comprised the extreme western part of the State of Brazil, under the administrative captaincy of Sao Paulo. From a local focus, analizing letters of metropolitan authorities and documentation of possession of land, this article dialogue with the historical production of the Portuguese administration in America, seeking rebuild generalizing aspects that may prove structural characteristics of the conquest of land and training of rural environments in Portuguese territories in America

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost