15 resultados para Causes of deterioration of fish net twines


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This project aims to provide feasible solutions to improve customer´s Help Area at Continente Online. The goal is to increase satisfaction and loyalty by reducing the main causes that lead customers to appeal to Call Center or abandon the website. The pursued solution is the implementation of Web Self-Service and the vision taken is focused not only on providing customers basic help tools but also innovate with international best practices to sustain Sonae MC´s present and future market leader position. Customer´s feedback, costs and impact are taken in consideration to find the best fit for the company.

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Complex problems of globalized society challenge its adaptive capacity. However, it is precisely the nature of these human induced problems that provide enough evidence to show that adaptability may not be on a resilient path. This thesis explores the ambiguity of the idea of adaptation (and its practice) and illustrates the ways in which adaptability contributes to resilience of social ecological systems. The thesis combines a case study and grounded theory approach and develops an analytical framework to study adaptability in resource users’ organizations: from what it depends on and what the key challenges are for resource management and system resilience. It does so for the specific case of fish producers’ organizations (POs) in Portugal. The findings suggest that while ecological and market context, including the type of crisis, may influence the character of fishers’ adaptation within POs (i.e. anticipatory, maladaptive and reactively adaptive), it does not determine it. Instead, it makes agency even more crucial (i.e. leadership, trust and agent’s perceptions in terms of their impact on fishers’ motivation to learn from each other). In sum, it was found that internal adaptation can improve POs’ contribution to fishery management and resilience, but it is not a panacea and may, in some cases, increase system vulnerability to change. Continuous maladaptation of some Portuguese POs points at a basic institutional problem (fish market regime), which clearly reduces fisheries resilience as it promotes overfishing. However, structural change may not be sufficient to address other barriers to Portuguese fishers’ (PO members) adaptability, such as history (collective memory) and associated problematic self-perceptions. The agency (people involved in structures and practices) also needs to change. What and how institutional change and agency change build on one another (e.g. comparison of fisheries governance in Portugal and other EU countries) is a topic to be explored in further research.

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Dissertação para obtenção do Grau de Mestre em Matemática e Aplicações Especialização em Actuariado, Estatística e Investigação Operacional

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Dissertação para obtenção do Grau de Mestre em Biotecnologia

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Dissertação apresentada para cumprimento dos requisitos necessários à obtenção do grau de Doutor em História dos Descobrimentos e da Expansão Portuguesa

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RESUMO: Este estudo foi realizado com o objectivo de conhecer os efeitos da desinstitucionalização dos doentes psiquiátricos crónicos durante o processo de encerramento do Hospital Miguel Bombarda (2007-2011). Este processo incluiu a fusão, em 2008, dos dois principais hospitais psiquiátricos de Lisboa- Hospital Miguel Bombarda (HMB) e Hospital Júlio de Matos (HJM), no Centro Psiquiátrico Hospitalar de Lisboa (CHPL). Foi criado um grupo controlo de pacientes ainda hospitalizados no CHPL (n=166) para comparação com o grupo de casos desinstitucionalizados (n=146). Desta amostra inicial (n=312) apenas 142 (76 casos e 66 controlos) foram incluídos, sendo as principais causas de exclusão: diagnóstico (patologia orgânica, demência ou debilidade mental, como diagnóstico primário) e transferência entre hospitais. A desinstitucionalização foi principalmente avaliada em termos de psicopatologia, utilização de serviços, satisfação, crime, condição de “sem abrigo” ou morte. Os resultados mostraram que a maioria dos doentes crónicos pode sair do hospital psiquiátrico para a comunidade sem agravamento da psicopatologia, aumento do crime ou da condição de “sem abrigo”. A satisfação parece estar aumentada na população desinstitucionalizada. A mortalidade, por outro lado, revelou-se uma questão problemática: apesar de não ter sido possível estabelecer uma comparação entre casos e controlos, a Taxa de Mortalidade Standard encontrada neste estudo foi muito superior ao esperado, de acordo com os resultados encontrados na literatura. Um estudo longitudinal da mesma população poderá ser objecto de futura investigação, possivelmente comparada com outra população similar de um programa de desinstitucionalização noutro país.--------- RÉSUMÉ: Cette étude a été menée afin de déterminer les effets de la désinstitutionnalisation des patients chroniques lors de la fermeture de l'hôpital Miguel Bombarda (2007-2011). Ce processus comprenait la fusion en 2008 de deux grands hôpitaux psychiatriques de Lisbonne: À savoir, Hôpital Miguel Bombarda (HMB) et Hôpital Julio de Matos (HJM), maintenant Centre de l'Hôpital Psychiatrique de Lisbonne (CHPL). Il a été créé un groupe contrôle des patients toujours hospitalisés à CHPL (n = 166) pour comparer avec les cas désinstitutionnalisés (n = 146). De cet échantillon initial (n= 312) à peine 142 (76 cas et 66 contrôles) ont été inclus, les principales raisons d'exclusion: diagnostique (maladie organique, démence ou d'arriération mentale comme diagnostic primaire) et les transferts entre hôpitaux. La désinstitutionnalisation a été principalement évaluée en termes de psychopathologie, de l'utilisation des services, la satisfaction, la criminalité, les “sans abri” et de la mort. Les résultats ont montré que la majorité des malades chroniques peuvent quitter l'hôpital psychiatrique et s´intégrer dans la communauté sans aggravation de la psychopathologie, augmentation de la criminalité ou du nombre de “sans-abri”. La satisfaction semble être en hausse dans la population désinstitutionnalisée. Toutefois, la mortalité s'est avéré être une question problématique, même si il n´a pas été possible d'établir une comparaison entre les cas et les contrôles, le Taux de Mortalité Standard estimé dans cette étude fut beaucoup plus élevé que prévu, en tenant compte des résultats établis dans la littérature. Une étude longitudinale de la même population pourra faire l'objet de futures recherches, peut-être comparé à une population similaire d'un programme de désinstitutionnalisation dans un autre pays. ----------- ABSTRACT:This study was conducted to assess the effects of deinstitutionalization of “long-stay” patients during the process of closing Hospital Miguel Bombarda (2007-2011). This process included the fusion, in 2008, of the two main psychiatric hospitals in Lisbon- Hospital Miguel Bombarda (HMB) and Hospital Júlio de Matos (HJM), into Centro Psiquiátrico Hospitalar de Lisboa (CHPL). A control group of still institutionalized patients in CHPL (n=166) was used as a comparison with the deinstitutionalized population (n=146). Of this 312 initial sample only 142 (76 cases and 66 controls) were included, the main causes of exclusion being diagnoses (organic disease, dementia and mental retardation- as first diagnoses) and transference between hospitals. Deinstitutionalization is mainly evaluated in terms of psychopathology, use of services, satisfaction, crime, vagrancy and deaths. The results show that most long-stay patients can successfully leave psychiatric hospitals and be relocated in the community without an increase in psychopathology, crime or vagrancy. Satisfaction seems to be improved in those patients. On the other hand, mortality remains an issue of concern: Although there was no possibility of comparing it between cases and controls, the Standard Mortality Rate (SMR) in our study was found to be much higher than expected judging by other studies results. A longitudinal further study of this same population will be the matter for a future investigation, possibily compared with another similar population from a desinstitutionalization programme in another country.

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Proceedings IGLC-18, July 2010, Technion, Haifa, Israel

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21st Annual Conference of the International Group for Lean Construction – IGLC 21 – Fortaleza, Brazil

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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics

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Nowadays, reducing energy consumption is one of the highest priorities and biggest challenges faced worldwide and in particular in the industrial sector. Given the increasing trend of consumption and the current economical crisis, identifying cost reductions on the most energy-intensive sectors has become one of the main concerns among companies and researchers. Particularly in industrial environments, energy consumption is affected by several factors, namely production factors(e.g. equipments), human (e.g. operators experience), environmental (e.g. temperature), among others, which influence the way of how energy is used across the plant. Therefore, several approaches for identifying consumption causes have been suggested and discussed. However, the existing methods only provide guidelines for energy consumption and have shown difficulties in explaining certain energy consumption patterns due to the lack of structure to incorporate context influence, hence are not able to track down the causes of consumption to a process level, where optimization measures can actually take place. This dissertation proposes a new approach to tackle this issue, by on-line estimation of context-based energy consumption models, which are able to map operating context to consumption patterns. Context identification is performed by regression tree algorithms. Energy consumption estimation is achieved by means of a multi-model architecture using multiple RLS algorithms, locally estimated for each operating context. Lastly, the proposed approach is applied to a real cement plant grinding circuit. Experimental results prove the viability of the overall system, regarding both automatic context identification and energy consumption estimation.

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Retail services are a main contributor to municipal budget and are an activity that affects perceived quality-of-life, especially for those with mobility difficulties (e.g. the elderly, low income citizens). However, there is evidence of a decline in some of the services market towns provide to their citizens. In market towns, this decline has been reported all over the western world, from North America to Australia. The aim of this research was to understand retail decline and enlighten on some ways of addressing this decline, using a case study, Thornbury, a small town in the Southwest of England. Data collected came from two participatory approaches: photo-surveys and multicriteria mapping. The interpretation of data came from using participants as analysts, but also, using systems thinking (systems diagramming and social trap theory) for theory building. This research moves away from mainstream economic and town planning perspectives by making use of different methods and concepts used in anthropology and visual sociology (photo-surveys), decision-making and ecological economics (multicriteria mapping and social trap theory). In sum, this research has experimented with different methods, out of their context, to analyse retail decline in a small town. This research developed a conceptual model for retail decline and identified the existence of conflicting goals and interests and their implications for retail decline, as well as causes for these. Most of the potential causes have had little attention in the literature. This research also identified that some of the measures commonly used for dealing with retail decline may be contributing to the causes of retail decline itself. Additionally, this research reviewed some of the measures that can be used to deal with retail decline, implications for policy-making and reflected on the use of the data collection and analysis methods in the context of small to medium towns.

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RESUMO: A isquémia cerebral é uma das doenças mais predominantes a nivel mundial, sendo uma das principais causas de mortalidade e invalidez. Parte da propagação de dano no cérebro é causado por inflamação descontrolada, causada principalmente por disfunção da microglia. Desta forma, existe a necessidade de tentar desenvolver estratégias para melhor compreender e modular as acções destas células. O monóxido de carbono (CO), é uma molécula endógena com provas dadas como anti-neuroinflamatório em vários modelos. Assim, o principal objectivo do trabalho foi o estudo do CO como um modulador da acção da microglia, com principal foco dado à comunicação entre estas células e neurónios, tentando entender se existe um efeito neuroprotector por inibição da inflamação. Um protocolo de meio condicionado foi estabelecido usando as linhas celulares BV2 e SH-SY5Y, de microglia e neurónio. A molécula CORM-A1, que liberta expontaniamente CO, foi usada como método de entrega da molécula às celulas. Demonstrámos que o pre-tratamento de células BV2 com CORM-A1 gera neuroprotecção já que reduz a morte celular de neurónios SH-SY5Y quando são incubados com meio condicionado de microglia activada em conjunto com o pró-oxidante t-BHP (tert-butil hidroperóxido). Assim, considerámos que o CO promove neuroprotecção ao inibir as acções inflamatórias da microglia. O papel anti-inflamatório da molécula CORM-A1 foi confirmado quando se verificou que pré-tratamento desta molécula em microglia BV2 limita a secreção de TNF-α mas estimula a secreção de IL-10. Por último, a CORM-A1 induziu a expressão do receptor da microglia CD200R1, molécula que participa na comunicação neurónio-microglia e fundamental para a modulação das acções inflamatórias destas últimas. Em suma, o nosso trabalho reforçou as propriedades anti-neuroinflamatórias do CO e uma capacidade de modular viabilidade neuronal através do seu efeito a nível de comunicação célula-célula. ---------------------------- ABSTRACT: Brain ischemia is a widespread disease worldwide, being one of the main causes of mortality and permanent disability. A portion of the damage that ensues following the ischemic event is caused by unrestrained inflammation, which is mainly orchestrated by exacerbated microglial activity. Hence, developing strategies for modulating microglial inflammation is a major concern nowadays. The endogenous molecule carbon monoxide (CO) has been shown to possess anti-neuroinflammatory properties using in vitro and in vivo approaches. Thus, our objective was to study CO as modulator of microglial activity, in particular in what concerns their communication with neurons, by promoting neuronal viability and limiting inflammatory output of activated microglia. A conditioned media strategy was established with BV2 microglia and SH-SY5Y neurons as cell models. CO-releasing molecule A1 (CORM-A1), a compound that releases CO spontaneously, was used as method of CO delivery to cells. We found that CORM-A1 pre-treatment in BV2 cells yields neuroprotective results, as it limits cell death when SH-SY5Y neurons are challenged with conditioned media from LPS-activated microglia and the pro-oxidant t-BHP (tert-butyl-hydroperoxide). Thus, we assumed carbon monoxide promotes neuroprotection via inhibition of microglial inflammation, displaying a non-cell autonomous role. CORM-A1 pre-treatment limited inflammation by inhibiting BV2 secretion of TNF-α and stimulating IL-10 production. These results reinforce that CO’s anti-inflammatory role confers neuroprotection, as the alterations in these cytokines occur concurrently with the increase in SH-SY5Y viability. Finally, we showed for the first time that carbon monoxide promotes the expression of CD200R1, a microglial receptor involved in neuron-glia communication and modulation of microglia inflammation. Further studies are necessary to clarify this role. Altogether, other than just highlighting CO as an anti-inflammatory and neuroprotective molecule, this work set the foundation for disclosing its involvement in cell-to-cell communication.

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RESUMO: O cancro do pulmão (LC), uma das principais causas de mortalidade relacionada com cancro em Portugal, pode levar à formação de metástases hematogénicas. A adesão das células tumorais ao endotélio é considerada um dos passos fundamentais envolvidos na metástase. Em células sanguíneas, esta adesão é mediada por ligandos de E-selectina (E-SL), glicoproteínas ou glicolípidos decorados principalmente com sialyl-Lewis x (sLex) e sialyl-Lewis a (sLea). Tem sido descrito a expressão destes antigénios em LC, contudo o seu papel funcional em permitir a adesão das células de LC ao endotélio é ainda pouco compreendido. Foram analisadas amostras emparelhadas normais e tumorais de pacientes com cancro de pulmão de não-pequenas células (NSCLC) e três linhas celulares de LC. Immunoblotting assays com anti-sLex/sLea e molécula quimérica de E-selectina demonstraram que tecidos tumorais de LC sobreexpressam significativamente E-SL e resultados de citometria de fluxo demonstraram uma expressão elevada de E-SL nas linhas celulares. Para compreender o mecanismo da sobreexpressão de E-SL em tecidos tumorais e linhas celulares de LC, foi analisada a expressão de genes envolvidos na biossíntese de E-SL, nomeadamente FUT3, FUT4, FUT6, FUT7, ST3GAL3, ST3GAL4, ST3GAL6, β4GALT1, GCNT1 e GALNT3. Observou-se a sobreexpressão das fucosiltransferases FUT3, FUT6 e FUT7 em tecidos tumorais de LC e FUT3 em linhas celulares de LC, sendo que neste último, esta expressão é correlacionada com um aumento da adesão das células de LC às selectinas endoteliais. Foi observado que uma baixa expressão de FUT4 em tecidos tumorais está associada com estadios menos avançados de NSCLC. Foram analisadas ainda proteínas decoradas com sLex/sLea, tendo-se identificado como E-SL o antigénio carcinoembrionário em NSCLC. Em resumo, esta tese contribuiu para uma melhor compreensão das alterações glicosídicas e moléculas que podem influenciar a progressão tumoral do LC, podendo permitir identificar futuramente novos biomarcadores de diagnóstico/prognóstico e potenciais alvos terapêuticos para o NSCLC.--------------------------ABSTRACT: Lung cancer (LC), one of the major causes of mortality related to cancer in Portugal, may lead to hematogenous metastasis. Adhesion of cancer cells to endothelium is considered one of the crucial steps involved in metastasis. In blood cells, this adhesion is initiated by endothelial selectin ligands (E-SL) that are glycoproteins or glycolipids decorated mostly with sialyl-Lewis x (sLex) and sialyl-Lewis a (sLea). While LC has been described as expressing these sialyl Lewis antigens, its functional role in allowing LC adhesion to endothelium is still poorly understood. We analyzed paired tumor and normal tissues samples from non-small cell lung cancer (NSCLC) patients and three LC cell lines. Immunoblotting assays with anti-sLex/sLea and E-selectin chimera demonstrated that LC tumor tissues significantly overexpress E-SL and flow cytometry results indicated that E-SL are also abundantly expressed in LC cell lines. To understand the mechanism behind the overexpression of E-SL in LC tissues and cell lines, we analyzed the expression of genes involved in its biosynthesis, namely FUT3, FUT4, FUT6, FUT7, ST3GAL3, ST3GAL4, ST3GAL6, β4GALT1, GCNT1 and GALNT3. It was observed the overexpression of fucosyltransferases FUT3, FUT6 and FUT7 in LC tumor tissues and FUT3 in LC cell lines, being this last one correlated with an increased reactivity of the LC cells to endothelial selectins. It was described that low expression of FUT4 in tumor tissues is correlated with early stages of NSCLC. We also analyzed scaffolds proteins of sLex/sLea and it was identified the carcinoembryonic antigen as an E-SL in NSCLC. In summary, this thesis contributed to a better understanding of the glycosidic changes and molecules that can influence tumor progression of LC, allowing identifying in the future new diagnosis/prognosis biomarkers and potential therapeutic targets for NSCLC.

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Cardiovascular diseases (CVDs) are one of the leading causes of death and disability worldwide and one of its underlying causes is hypercholesterolemia. Hypercholesterolemia can have genetic (familial hypercholesterolemia, FH) and non-genetic causes (clinical hypercholesterolemia, CH), the first much more severe, with occurrence of premature atherosclerosis. While the pathophysiological role of homocysteine (Hcy) on CVD is still controversial, molecular targeting of protein by S and N-homocysteinylation offers a new paradigm to be considered in the vascular pathogenesis of hypercholesterolemia. On this regard, the present study aims to give new insights on protein targeting by Hcy in both CH and FH conditions. A total of 187 subjects were included: 65 normolipidemic and 122 hypercholesterolemic. Total (tHcy) and free (fHcy) fractions were quantified in serum samples after validation of an HPLCFD method, to assess S-homocysteinylation. Also, the lactonase (LACase) activity of paraoxonase-1 (PON1) was quantified by a colorimetric assay, as a surrogate of N-homocysteinylation. tHcy does not differ among groups. Nevertheless, fHcy declines in the hypercholesterolemic groups, with more evidence to the FH population. Consequently, there seems to be an increase of Shomocysteinylation, regardless of lipid lowering therapy (LLT). Also, despite of LLT use, LACase activity is lower in FH, thus the risk for protein N-homocysteinylation seems to be higher. Moreover, the decrease in LACase/ApoA1 and LACase/HDL ratios in FH, shows that HDL is dysfunctional in this population, despite its normal concentration values. Data supports that the pathophysiological role of Hcy on hypercholesterolemia may reside in its ability to post-translationally modify proteins. This role is particularly evident in FH condition. In the future, it will be interesting to identify which target proteins are modified and thus involved in vascular pathology progression.

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RESUMO: Nos países desenvolvidos a lombalgia é a condição músculo-­‐esquelética mais prevalente. Quando evolui para um quadro crónico é responsável por um encargo económico bastante considerável, não só em relação aos indivíduos, mas também para a sociedade. A lombalgia crónica é por isso uma das principais causas de perda de produtividade e de perda de independência económica, nomeadamente através do absenteísmo (ausência do trabalho), do presenteísmo (perda de produtividade no trabalho, devido à capacidade diminuída provocada pela lombalgia) e da incapacidade para trabalhar (invalidez permanente, total ou parcial). Até à data, em Portugal, a prevalência e carga social da lombalgia crónica eram desconhecidas. Até agora não existiam estudos populacionais de grande dimensão sobre este tema. O objetivo principal desta tese foi determinar a prevalência de lombalgia crónica, e também avaliar a carga social que esta tem na população adulta Portuguesa. O trabalho de investigação foi desenvolvido no âmbito do Estudo Epidemiológico de Doenças Reumáticas em Portugal (EpiReumaPt). Este foi o primeiro estudo de larga escala e de base populacional, que determinou a prevalência de doenças reumáticas e músculo-­‐ esqueléticas na população adulta portuguesa. Foi realizado numa amostra aleatória e representativa, de 10.661 indivíduos do Continente, da Região Autónoma dos Açores e da Região Autónoma da Madeira, entre Setembro de 2011 e Dezembro de 2013. Esta tese foi dividida em duas secções. A primeira secção incluiu o detalhe das questões relativas ao desenvolvimento e gestão do EpiReumaPt, constituindo-­‐se como um guia prático sobre como realizar um estudo de base populacional de larga escala, em Portugal. A metodologia detalhada do EpiReumaPt foi também descrita nesta secção e incluiu os objectivos, o desenho do estudo, as características de recrutamento e a preparação de dados para análise. Nesta secção foram ainda descritos os principais resultados do EpiReumaPt. Estes evidenciaram que a lombalgia foi a condição músculo-­‐esquelética com maior prevalência na população adulta portuguesa.A segunda secção desta tese estimou a prevalência da lombalgia crónica ativa na população adulta Portuguesa, e avaliou a carga social esta condição. A lombalgia ativa foi definida com base na dor auto-­‐relatada no dia da entrevista e que persistia há pelo menos 90 dias (independentemente da causa). A lombalgia foi definida como dor na área definida entre a margem inferior das décimas segundas costelas até às pregas glúteas inferiores, com ou sem dor nos membros inferiores. A carga social foi medida tendo em conta os seguintes parâmetros: qualidade de vida, função, consumo de recursos de saúde, consumo de analgésicos e outros fármacos usados no alívio da dor, sintomas de ansiedade e sintomas de depressão. Os resultados mostraram que o consumo de recursos em saúde e a carga social da lombalgia crónica na população adulta Português é significativa. Também a incapacidade causada pela lombalgia crónica,nos indivíduos com idade ativa, é responsável por elevadas taxas de absenteísmo e má qualidade de vida, aos quais acresce o consequente ónus socioeconómico. Esta tese também concluiu que o consumo de analgésicos e outros medicamentos para alívio da dor, na população adulta portuguesa com lombalgia crónica ativa, é relativamente baixa. A maioria destes indivíduos não tomava nenhum medicamento analgésico, independentemente da intensidade da dor. Mesmo os indivíduos que reportaram dor intensa, apenas 4.0% estavam no primeiro degrau da escada analgésica da Organização Mundial de Saúde; 2.3% usavam opióides fracos e 0.03% usavam opióides fortes para controlar a dor (segundo e terceiro degrau da escada analgésica da Organização Mundial da Saúde). O trabalho de investigação também confirmou que a prevalência de sintomas de ansiedade e depressão entre os indivíduos adultos portugueses com lombalgia crónica ativa é elevada. Nestes indivíduos, registou-­‐se um consumo mais elevado de analgésicos e outros medicamentos para alívio da dor, quando comparados com os indivíduos com lombalgia crónica activa sem esses sintomas psicológicos. Os grupos terapêuticos mais utilizados foram os ansiolíticos, sedativos e hipnóticos, os antidepressivos e os anti-­‐inflamatórios não esteróides. A intensidade média da dor reportada foi também maior entre os indivíduos com lombalgia ativa e sintomas de ansiedade e/ou depressão. Também nestes, foi reportada pior função e pior estado de saúde. Em relação ao consumo de recursos de saúde foram encontradas diferenças significativas entre as duas populações: os indivíduos com lombalgia ativa e sintomas psicológicos concomitantes registaram maior número de consultas de psiquiatria de outras especialidades médicas, assim como precisaram de mais apoio domiciliário nos 12 meses prévios à entrevista do EpiReumaPt. Foram também identificados os fatores associados a sintomas isolados de ansiedade, a sintomas isolados de depressão e a sintomas de ansiedade e depressão. Resumindo,esta tese permitiu concluir que a lombalgia crónica é um problema de saúde comum na população adulta portuguesa, contribuindo para um elevado grau de incapacidade e que consequentemente afeta o desempenho laboral e o bem-­‐estar dos indivíduos. A lombalgia crónica é também responsável por um consumo considerável de recursos de saúde. Acresce ainda que os sintomas de ansiedade e depressão são comuns, entre os indivíduos com lombalgia crónica, contribuindo com uma carga social adicional.---------------------------------- ABSTRACT:Low Back Pain(LBP) is the most prevalent of musculoskeletal condition in developed countries.When it becomes chronic, LBP causesan enormous economic burden on individuals and society -­‐ it is one of the leading causes of loss of productivity and economic independence through absenteeism (time off work), presenteeism (lost productivity because of diminished capacity while at work) and work disability (permanent, partial or complete disablement for work purposes). In Portugal the prevalence and burden of LBP and chronic LBP (CLBP) were poorly defined. Until now no large population-­‐based studies have focused on this. The main aim of this thesis was to determine the prevalence of LBP and CLBP, and also to assess the burden of CLBP in the adult rtuguese population. The research work was developed under the scope of EpiReumaPt (the Portuguese Epidemiologic Study of Rheumatic Diseases). EpiReumaPt was the first national large population-­‐based and prevalence study of rheumatic and musculoskeletal diseases (RMD). It was performed among a randomized and representative sample of 10,661 adult Portuguese subjects recruited in Mainland, Azores and Madeira Islands, from September 2011 to December 2013. The first section of this thesis included detailed issues regarding the development and management of EpiReumaPt, and provided a practical guide on how to set-­‐up a large population-­‐based study in Portugal. The detailed methodology of EpiReumaPt, including its objectives,study design,recruitment features,and data preparation for analyses were also described. The main results from EpiReumaPt study were provided in this section and showed that LBP was the musculoskeletal condition with highest prevalence among Portuguese population. The second section of this thesis estimated the prevalence of active CLBP among adult Portuguese population, and assessed the social burden of this condition. Active CLBP was defined based on self-­‐reported pain on the day of the interview, and for most of the time for at least 90 days (independently from cause). LBP was defined as pain in the back area from the lower margin of the twelfth ribs to he lower gluteal folds, with or without pain referred to the lower limbs. Social burden was measured taking into account the following outcomes: quality of life, function, healthcare resources consumption, analgesic and other pain relief drugs intake, anxiety and depression symptoms. Results showed that the healthcare consumption and social burden of CLBP among adult Portuguese population were enormous, and the disability caused by CLBP among subjects in a working age provides high rates of absenteeism (work loss) and poor quality of life, with a consequent socioeconomic burden. This thesis also concluded that analgesic and other pain relief drugs untake among adult Portuguese population with active CLBP was very low. Most of the subjects with active CLBP did not take any analgesic drug regardless pain severity. Even when subjects self-­‐reported severe pain, only 24.0% were in the 1st step of the analgesic ladder,2.3% used weak analgesic opioids and 0.03% used strong opioids (2nd and 3rd step of WHO analgesic ladder, respectively) to control pain . The research work also confirmed that the prevalence of anxiety and depression symptoms among adult Portuguese subjects with active CLBP was high. Regarding pharmacological therapy, the intake of analgesic and other pain relief drugs was higher among subjects with anxiety and/or depression symptoms, when compared with subjects without these psychological symptoms. Anxiolytics, sedatives and hypnotics, antidepressants and NSAIDs intake had higher usage rates among these subjects. The pain severity mean was also higher among this subjects and function and health status was worse. Regarding healthcare resources consumption,significant differences between the two populations were found. Subjects with ctive CLBP and concomitant psychological symptoms had a higher number of psychiatrist and other physician visits. They also needed more home care in the previous 12 months. Factors associated with isolated symptoms of anxiety, depression,and concomitant anxiety and depression symptoms were also identified. Summarizing, we concluded that CLBP is a common health problem among adult Portuguese population contributing to disability and affecting labor performance, and the well being of subjects. it is also responsible for considerable healthcare resource consumption. Anxiety and depression symptoms are common among subjects with CLBP and provided an additional burden among them.