Stochastic frontier analysis applied to the fisheries

Tese de mestrado em Estatística, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2011Portugal é um país costeiro com cerca de 1200 km de costa, fazendo da pesca uma das actividades mais importantes, económica e culturalmente. Uma das espécies mais pescadas em Portugal é o peixe-espada preto, fazendo desta espécie uma das mais estudadas devido ao seu impacto socioeconómico. Desde o século XVII que na Madeira, o peixe-espada preto é pescado, mas só em 1983 foi iniciada esta pesca em Portugal continental, sendo Sesimbra a principal zona pesqueira. Assim sendo, foi de Sesimbra que vieram grande parte dos dados que foram usados neste trabalho. A regulação e a gestão da actividade pesqueira continuam a ser um dos maiores desafios, sendo assim essencial a avaliação do estado dos recursos explorados (neste caso o peixe-espada preto). Tal avaliação é vital para procurar medidas que garantam a sustentabilidade do recurso e da pesca. Um dos índices de abundância mais utilizados ´e o CPUE (captura-por-unidade-esforço), que é definido como a razão entre o total capturado e o total de esforço aplicado nessa mesma captura. Apesar do seu frequente uso é sabido que o CPUE é influenciado por outros factores para além do nível de abundância. Assim, para minimizar essa influência, o CPUE é estandardizado de forma a diminuir ou até remover os eventuais factores de confusão. Para tal foram aplicados Modelos Lineares Generalizados (GLM), que não são mais do que uma generalização dos Modelos Lineares. Essa generalização permite que a distribuição da variável resposta pertença à família exponencial (para além da Normal), e permite que a função de ligação entre a variável resposta e as variáveis explicativas seja uma função monótona diferenciável. Para estimar tal índice, a fonte de dados é frequentemente o diário de bordo. Na União Europeia e desde a introdução de Política Comum das Pescas, que reúne várias medidas para garantir a sustentabilidade da pesca europeia, é obrigatório registar toda a viagem desde a partida do porto até ao desembarque. Além disso, dado que não há dados independentes da pesca, ou seja, não há estudos dirigidos para a recolha de dados através de amostragem, a estimação deste tipo de índices acaba por depender quase exclusivamente dos diários de bordo. Assim acabam por assumir uma importância vital quer na monitorização quer na regulamentação da actividade pesqueira. O preenchimento destes diários de bordo é feito pelos mestres das embarcações no mar e é posteriormente introduzido numa base de dados pela Direcção Geral das Pescas e da Aquicultura. Contudo há erros ou más interpretações no preenchimento dos diários de bordo que podem de alguma forma enviesar quer os resultados quer as conclusões de estudos neles baseados. Além de que os dados retirados dos diários de bordo reflectem sempre imensa variedade nas espécies capturadas além da espécie alvo. Apesar disto, os diários de bordo são a fonte de dados de vários trabalhos que visam estimar níveis de abundância. Desta forma, é necessário medir e quantificar o impacto que uma base de dados menos cuidada pode ter na qualidade e na veracidade dos trabalhos que nela se baseiam. É este objectivo que visa a primeira parte deste trabalho (chapter 2), usando os dados contidos nos diários de bordo da frota que opera em Sesimbra e que tem como espécie alvo o peixe-espada preto. Os factores e variáveis relevantes para a estimação do CPUE também foram identificadas, assim como a respectiva influência. Desta primeira parte do trabalho resultou uma análise extensiva e detalhada dos diários de bordo, permitindo identificar os erros e até nalguns casos corrigi-los através do conhecimento de trabalho anteriores e da comunidade pesqueira de Sesimbra. Análise essa que recorreu a várias ferramentas estatísticas (p.e. Análise de Clusters, Tabelas de Contingência, e Testes de Significância) e que foi suportada por análise gráfica (p.e. Scatter-plots, QQ-plots e Histogramas). Foi possível então comparar os resultados obtidos entre duas bases de dados, uma mais cuidada do que outra no que toca ao registo de observações. Diferença essa que foi bem visível na percentagem de explicação do modelo, onde houve um decréscimo de 20 pontos percentuais. Inspirada nestes resultados, surgiu a ideia de aplicar outra abordagem e usar outra fonte de dados que não os diários de bordo. A sustentabilidade do recurso, para além de outros factores, passa pela utilização eficiente de recursos de modo a garantir a renovação constante do peixe para níveis óptimos. Tal eficiência só pode ser atingida minimizando o desperdício dos recursos gastos durante a actividade pesqueira e maximizando o proveito socioeconómico dessa mesma actividade. Apesar deste conhecimento geral, nem todos os produtores (neste caso embarcações) são bem sucedidos em atingir níveis satisfatórios de eficiência. Existem várias abordagens para estimar e avaliar a eficiência duma actividade económica, em particular Análise de Fronteiras Estocásticas (SFA), que combina dois campos da ciência, a Estatística e a Economia. Esta metodologia foi desenvolvida por Aigner and Schmidt [1977] e por Meeusen and van den Broeck [1977], e tem sido aplicada em vários campos e sido objecto de várias pesquisas, sendo até considerada por alguns autores como a melhor abordagem na presença da ineficiência. Dentro desta metodologia podem ser consideradas três tipos de eficiência: T´ecnica (Technical Efficiency), Custo (Cost Efficiency) e Lucro (Profit Efficiency). Neste estudo apenas foi estimada a Eficiência Técnica que pode ser descrita como a habilidade de, dado um resultado fixo (output), minimizar a quantidade de variáveis (inputs) necessárias para obter tal resultado, ou a habilidade de maximizar o resultado obtido de um conjunto de variáveis fixas. O conceito ´e simples e até tem havido um crescente interesse em aplicar esta metodologia à actividade pesqueira, no entanto são poucos os trabalhos realizados sobre este tema, e os poucos que há são estudados duma perspectiva económica e não estatística. Assim este trabalho vem, de alguma forma, tentar preencher esse vazio realizando esta abordagem do ponto de vista estatístico. A segunda parte deste trabalho (chapter 3) tem então o propósito de avaliar esta abordagem teoricamente e verificar se é na prática uma ferramenta útil e de fácil aplicação. Assim, dentro deste estudo, a eficiência técnica de todas as embarcações que compõem a frota de peixe-espada preto de Sesimbra foram estimadas. Para tal foram recolhidos dados através de inquéritos aos envolvidos nesta actividade, sendo obtido dados relativos aos anos de 2009 e 2010. Dos resultados foi possível identificar diferenças entre várias abordagens e modelos, avaliar a evolução da eficiência no tempo, procurando tendência e/ou sazonalidade e finalmente verificar que a pesca do peixe-espada preto desenvolvida em Sesimbra pode ser considerada eficiente.In fisheries world the knowledge of the state of the exploited resource, is vital to guarantee the conservation of the resource and the sustainability of the fishery itself. The present study is focused on the Portuguese longline deep-water fishery that targets black scabbardfish. This fish is a deep-water species and its landings have an important economical value for Portugal. The fleet that explores the species is composed by 15 vessels with a mean overall length of 17 m. In the first part of this work Generalized Linear Model was used to standardize the Capture-per-unit-effort, so the first aim is to improve the estimate of CPUE, which is widely used as an index of stock abundance. This is done by reanalyzing the data stored at Portuguese General Directorate from fishery industry and in particularly the logbooks, which are used to record catch data as part of the fisheries regulation. The second part focused on Technical Efficiency, which refers to the ability to minimize the production inputs or the ability to obtain the maximum output. In this study TE estimates were obtained through Stochastic Frontier Analysis. This methodology embraces two science fields, Economy and Statistics, and has been the subject of studies in various areas but there are few applications to fisheries and the available ones are often studied from the economic point of view rather than a statistical one. This work aimed to analyze the quality of the logbooks and identify the relevant factors to the CPUE estimation as the theoretical evaluation of SFA approach and the identification of the statistical differences between several models. TE of each vessel was estimated and was verify if the black scabbardfish fishery operating in Portugal mainland can be considered efficient

Telomere biology in metazoa

Tese de doutoramento, Engenharia Biomédica e Biofísica, Universidade de Lisboa, Faculdade de Ciências, 2011Telomerase, the enzyme that maintains telomeres, is absent from most adult human somatic cells, producing a progressive telomere shortening that limits the proliferative potential of primary human cell cultures (Shay and Wright 2007). This programmed telomere shortening, replicative aging, functions as a tumor suppressor program that generates a barrier for the outgrowth of tumors. Remarkably, this telomere tumor suppressor program is not conserved in laboratory rats and mice, which have long telomeres and constitutive telomerase (Sherr and DePinho 2000; Wright and Shay 2000). The present study examines over 60 mammalian species to determine the phylogenetic distribution of the telomere tumor suppressor pathway. Phylogeny based statistical analysis demonstrates that telomere length inversely correlates with lifespan but not body size, while telomerase expression inversely correlates with body size but not lifespan. The ancestral mammalian phenotype was determined to have short telomeres and repressed telomerase. At least 5-7 independent times in different orders smaller, shorter lived species changed to having long telomeres and expressing telomerase, suggesting tradeoffs between the advantages and drawbacks of using replicative aging as a tumor suppression mechanism. We show that one advantage is consistent with reducing the energetic/cellular costs of specific oxidative protection mechanism needed to maintain short telomeres. We propose that the telomere tumor suppressor pathway represents an initial adaptation to the increased mutational load of homeothermy by ancestral mammals, has adaptive advantage in large and long-lived animals, but has been abandoned by many species. These observations resolve a longstanding confusion about the use of telomeres in humans and mice, support a role for telomere length in limiting lifespan, provide a critical framework for interpreting studies of the role of oxidative protection in the biology of aging, and identify which mammals can be used as appropriate model organisms for the study of the role of telomeres in human cancer and aging.European Union Programs POCI 2010 & FSE and by national funds from the Portuguese Ministry for Science, Technology and Superior Education ((N.M.V.G); Keck Foundation and the National Institute on Aging (W.E.W. & J.W.S.

Development of an Integrated Durability Assessment Methodology of Thermal Mortars Applied in Multi-layer Systems

A gap in the durability assessment of thermal mortars applied in multi-layer systems was observed. The existing standardisation for the durability assessment of hardened mortars does not include a consistent evaluation of thermal coatings applied in multilayer systems, which motivated the development of a new durability assessment methodology. The determination of the physical, hygrothermal and mechanical properties allowed deepening the knowledge of thermal mortars, contributing to develop more reliable simulations. The existing durability methodologies applicable to one-coat mortars and those applicable to thermal multilayer systems (such as ETICS - External Thermal Insulation Composite Systems) are suitable to be adapted to thermal rendering and plastering systems since they present some similar characteristics. The methodology takes into account the material characteristics and specific requirements, such as the application and climatic conditions. The knowledge of these parameters allows the definition of representative accelerated ageing cycles of the relevant degradation mechanisms. The combination of existing procedures with hygrothermal simulation allowed the development of accelerated ageing cycles, taking into account the European climatic context. The existing procedures allowed analysing several degradation mechanisms, but the fixed parameters are not transversal to different climates. The developed methodology allows a realistic durability evaluation since the ageing cycles are adapted to thermal mortars and real climate conditions, contrary to the existing standardised procedure

Assessment of test methods for the durability of thermal mortars exposure to freezing

Thermal mortars are a trend in the construction industry in recent years, owing to the required decrease of the thermal transmission of building envelopes. The high porosity of thermal mortars leads to permeability values that can affect their durability since it creates more favourable conditions for the penetration of aggressive agents. Water is observed as one of the most common and harmful degradation agents. Regarding the climatic variability in Europe, freezing is a usual degradation mechanism both in severe and moderate climates. Since thermal mortars have higher water absorption than a common insulation, the freezing may occur. As no durability assessment methodologies to evaluate the exposure of thermal mortars to freezing degradation mechanisms exist, the present work has the objective to analyse existing accelerated ageing procedures, which envisage freezing degradation mechanism. As such, the durability assessment described in EN 1015-21 and ETAG 004 was adapted and implemented in different thermal mortars. It was observed that the higher number of cycles and the severity of the freeze-thaw ageing cycles, according to ETAG 004, may reproduce the effect of the northern European climates, while the ageing cycles, described in EN 1015-21, combine degradation mechanisms that occur in central and southern European climates. This adaptation allowed collecting reliable data and inputs to the development of durability assessment methodologies directly applicable to thermal rendering and plastering systems

Effect of hygrothermal loads applied to thermal render systems

Thermal renders applied in multilayer systems are a recent trend in the building industry, besides ETICS. This type of systems aims at lowering the envelope U-Value with an upgraded thermal resistance of its components. As building rehabilitation has been increasing on a large scale, these solutions are of major interest, due to its easier application (by mechanical spraying) and enhanced hygrothermal properties. Durability assessment is a crucial issue to systematize and improve the knowledge of wall multilayer systems. Optimizing their application must take into account the actual climatic conditions. However, durability assessment procedures applied specifically to thermal render systems do not exist. The main goal of the present paper is to cover the gap in terms of durability assessment of thermal render systems defining a methodology based on accelerated ageing, taking into account the render matrix, hygrothermal and mechanical properties and also climate action. The first part of the work focus the analysis of durability assessment of existing standards, which are applied to renders and multilayer systems (EN 998-1, EN 1015 and ETAG 004). Also, some authors have worked on the calculation of acceleration factors and definition of new accelerated ageing protocols, by analysing the results of natural ageing tests and climate data. In a second part, hygrothermal simulations, using the WUFI Pro software, are performed to evaluate the thermal render systems performance, in different climates. The results were analysed to support and complement the previous knowledge and lead to the definition of a durability assessment methodology applied to thermal render systems

Psychosocial Development Research in Adolescence: a Scoping Review

Erikson’s psychosocial development is a well-known and sound framework for adolescent development. However, despite its importance in scientific literature, the scarcity of literature reviews on Erikson’s theory on adolescence calls for an up-todate systematization. Therefore, this study’s objectives are to understand the extent and nature of published research on Erikson’s psychosocial development in adolescence (10–19 years) in the last decade (2011–2020) and identify directions for meaningful research and intervention. A scoping review was conducted following Arksey and O’Malley’s framework, PRISMA-ScR guidelines, and a previous protocol, including a comprehensive search in eight databases. From 932 initial studies, 58 studies were selected. These studies highlighted the burgeoning research on Erikson’s approach, with a more significant representation of North American and European studies. The focus of most studies was on identity formation, presenting cross-cultural evidence of its importance in psychosocial development. Most of the studies used quantitative designs presenting a high number of different measures. Regarding topics and variables, studies emphasized the critical role of identity in adolescents’ development and well-being and the relevance of supporting settings in psychosocial development. However, shortcomings were found regarding the study of online and school as privileged developmental settings for adolescents. Suggestions included the need to consider the process of identity formation in the context of lifespan development and invest in supporting adolescents’ identity formation. Overall, conclusions point out Erikson’s relevance in understanding adolescents’ current challenges while offering valuable research and intervention directions to enhance adolescent growth potential.info:eu-repo/semantics/publishedVersio

Supporting Content Discovery and Management in a Research Infrastructure

LISBOA-01-0145-FEDER-022139The ROSSIO Infrastructure aims at aggregating, organis-ing and contextualising digital objects whose metadata descriptions areprovided by a consortium of Portuguese academic, public andprivatesector institutions in the domains of social sciences, artsand humanities.ROSSIO is the Portuguese representative of DARIAH, the Europeanresearch infrastructure for arts and humanities. A platform is being de-veloped to provide search and content curation services forresearchersand the general public, namely digital collections, digital exhibitions anda virtual research environment. The ROSSIO Thesaurus is being devel-oped to support content discovery and management in the platform. Thethesaurus is being modelled as a SKOS concept scheme, and it leverageson existing unstructured vocabularies, such as subject headings and the-sauri, produced by the ROSSIO data providers. This paper describes themodelling process of the ROSSIO Thesaurus, its integrationand role inthe infrastructure, its publication as Linked Open Data, and the resultsof this work after 6 months of development.publishersversionpublishe

A new durability assessment methodology of thermal mortars applied in multilayer rendering systems

The increase of the thermal resistance of building envelopes is a result from the growing demand of energy efficiency. Several new materials and systems emerged in recent years as an answer to that growing need. Thermal mortars applied in thermal rendering systems are an example of how the research community and the building industry try to tackle that challenge. A gap in the durability assessment of thermal rendering systems can however be observed. The existing standardization for the durability assessment of mortars does not allow a consistent evaluation of thermal mortars, especially in multilayer systems. As such, the main goal of the present work consists in proposing a durability assessment methodology of thermal mortars applied as multilayer systems. Accelerated ageing cycles, directly applicable to thermal mortars, were developed through numerical simulation, taking into account material properties, climatic conditions and consequent degradation mechanisms to which the system is subjected. A theoretical methodology for the determination of heat-cold cycles that can represent specific climatic conditions was developed. The implementation of the developed accelerated ageing cycles and the obtained experimental results contributed to the definition of a new durability assessment methodology. This methodology defines the accelerated ageing cycles that should be performed in each climate zone, representative of the main degradation mechanisms. One of the major advantages is the temperature adaption of the accelerated ageing cycles to the climatic conditions. The new methodology contributes to the evaluation of new solutions, during their development stage, and to their adequacy for specific climatic conditions

Experiments with IPV6 network mobility using nemo protocol

The NEMO (NEtwork MObility) protocol, as normalized by IETF, allows a transparent movement of a whole IPv6 network. This mobile network can thus attach to different points in the Internet without losing TCP/IP connectivity of its mobile nodes. In this paper we briefly describe the NEMO protocol and present a simple architecture deployed to test its main functionalities. We also discuss the results obtained thus far with the use of popular TCP and UDP applications in a mobile environment: video streaming transfer, remote access using SSH and FTP file transfer