26 resultados para Positive Definite Functions


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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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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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This paper investigates the implications of individuals’ mistaken beliefs of their abilities on incentives in organizations using the principal-agent model of moral hazard. The paper shows that if effort is observable, then an agent’s mistaken beliefs about own ability are always favorable to the principal. However, if effort is unobservable, then an agent’s mistaken beliefs about own ability can be either favorable or unfavorable to the principal. The paper provides conditions under which an agent’s over estimation about own ability is favorable to the principal when effort is unobservable. Finally, the paper shows that workers’ mistaken beliefs about their coworkers’ abilities make interdependent incentive schemes more attractive to firms than individualistic incentive schemes.

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This paper analyzes the implications of worker overestimation of productivity for firms in which incentives take the form of tournaments. Each worker overestimates his productivity but is aware of the bias in his opponent’s self-assessment. The manager of the firm, on the other hand, correctly assesses workers’ productivities and self-beliefs when setting tournament prizes. The paper shows that, under a variety of circumstances, firms make higher profits when workers have positive self-image than if workers do not. By contrast, workers’ welfare declines due to their own misguided choices.

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Dissertation presented to obtain the Ph.D degree in Biology.

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Dissertação para obtenção do Grau de Mestre em Engenharia e Gestão Industrial

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RESUMO: Os estudos sobre a funcionalidade da população idosa têm uma representação importante naquilo que é o atual conhecimento da demografia do mundo. Portugal posiciona-se e perspetiva-se como pertencendo aos países mais envelhecidos, possuindo uma rede de cuidados pós-agudos – a Rede Nacional de Cuidados Continuados Integrados (RNCCI)– que assiste uma parcela importante dessa população. Os aspetos conceptuais da funcionalidade de acordo com a OMS e operacionalizados pela Classificação Internacional de Funcionalidade (CIF), não mereceram até agora suficiente aplicabilidade no nosso país, inviabilizando a possibilidade de oferecermos contributos para a sua operacionalização. Da mesma forma, também os Core Sets da Classificação não têm sido sujeitos a processos de validação que contemplem amostras portuguesas, mantendo-se desconhecimento da especificidade dos fatores contextuais na nossa população. O presente estudo tem como objetivos conhecer a evolução da funcionalidade dos idosos assistidos na RNCCI na região do Algarve nas unidades de convalescença e média duração, validar o Core Set Geriátrico da OMS e propor uma versão abreviada da sua modalidade abrangente, no contexto destes cuidados. A amostra constituída por 451 idosos, dos quais 62,1% eram mulheres, revelou na pré-morbilidade níveis favoráveis de funcionalidade, com exceção para as Atividades Domésticas. Contudo, os mais idosos (≥ 85 anos), os indivíduos sem escolaridade, as mulheres e os viúvos/solteiros apresentaram mais casos desfavoráveis quando comparados com os seus pares. Na evolução da funcionalidade observámos melhorias significativas em todos os domínios avaliados, com diferenças relativamente à idade e à escolaridade; apesar dos resultados positivos os mais idosos e os indivíduos sem escolaridade apresentaram níveis inferiores de evolução. No entanto, a funcionalidade alcançada revelou ficar com resultados significativamente inferiores na comparação com aquela que os indivíduos possuíam na pré-morbilidade. Os modelos de regressão revelaram que as Funções Mentais, a Perceção do Estado de Saúde e a atividade Usar o Telefone, foram as variáveis que melhor explicaram os outcomes da funcionalidade alcançada. A validação do Core Set Geriátrico foi possível na maioria das categorias, sendo que foi no componente das Funções do Corpo onde esse processo revelou maior fragilidade. As Funções Neuromusculoesqueléticas e Relacionadas com o Movimento foram aquelas que registaram em ambos os momentos avaliativos frequências mais elevadas de deficiência, enquanto no componente Atividades & Participação isso ocorreu na atividade Utilização dos Movimentos Finos da Mão. Os capítulos Apoios e Relacionamentos e Atitudes foram considerados os Fatores Ambientais mais Facilitadores mas também com maior impacto Barreira. A proposta para o Core Set Geriátrico Abreviado resultou das categorias independentes que explicaram os modelos da funcionalidade alcançada e cujo resultado engloba um conjunto de 27 categorias, com um enfoque importante no componente Atividades/Participação de onde se destacam os domínios da Mobilidade e dos Auto Cuidados. A funcionalidade dos indivíduos e das populações deve ser considerada uma variável incontornável da Saúde Pública, cuja avaliação deve refletir uma abordagem biopsicossocial, apoiada na Classificação Internacional de Funcionalidade. A operacionalização da Classificação a partir dos Core Sets necessita de pesquisa mais aprofundada relativamente às caraterísticas psicométricas dos seus qualificadores e dos seus processos de validação.-----------ABSTRACT: The studies about the functioning of the elderly play an important role on what the present knowledge of the demography in the world is. Portugal figures high on the most aged countries, having a network of post-acute care - the National Network of Integrated Continuous Care (RNCCI) - which assists a large part of that population. The conceptual aspects of functioning according to WHO and operated by the International Classification of Functioning (ICF), have been insufficiently addressed concerning its adequate applicability in our country, hindering the contributions of its operation. In the same way, also the Core Sets of the Classification have not been subjected to validation procedures that include portuguese samples, keeping the unawareness of specificity of the contextual factors in our population. The objectives of the present study were to know the evolution of the functioning of the elderly assisted in the RNCCI in the Algarve region in units of convalescence and average duration, validate the WHO Geriatric Core Set and propose an abridged version of this comprehensive core set in this healthcare context. The sample was composed by 451 elderly people, of which 62.1% were women, they showed favourable levels in functioning in the pre-morbid state, except for Domestic Activities. However, the oldest (≥ 85 years), the individuals with no education, women and widowed/ unmarried showed more unfavourable cases when compared to their peers. In the evolution of functioning we observed significant improvements in all domains assessed, with diferences with respect to age and education. In spite of positive results, the oldest and the individuals with no education showed lower levels of evolution. However, the functioning achieved showed significantly lower results when compared to the those observed in pre-morbidity state. Regression models reveal that Mental Functions, the Perceived Health Status and the Use of the Phone activity, were the variables that better explain the functioning of the outcomes achieved. The validation of the Geriatric Core Set of ICF was possible in most categories, and Body Functions was the component where this process showed greatest weakness. Neuromusculoskeletal and Movement-Related Functions experienced in both evaluation times with higher rates of disability, while in the Activities & Participation component this occurred in the Fine Hand Use activity. The Support and Relationships and Attitudes chapters were considered the Environmental Factors most Facilitators but also with greater impact Barrier. The proposal for the Brief Geriatric Core Set has resulted from the independent categories that explained the regression models of functioning and includes a set of 27 categories, with na important emphasis on Activities & Participation component where we can highlight the areas of Mobility and Self Care domains. The functioning of individuals and populations should be considered as an unavoidable variable of Public Health, of which the assessment should reflect a biopsychosocial approach, based on the International Classification of Functioning. The operationalization of the Classification from the Core Sets requires further research regarding the psychometric characteristics of their qualifiers and their validation procedure.

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Salmonella enterica serovars are Gram-negative facultative intracellular bacterial pathogens that infect a wide variety of animals. Salmonella infections are common in humans, causing usually typhoid fever and gastrointestinal diseases. Salmonella enterica serovar Typhimurium (S. Typhimurium), which is a leading cause of human gastroenteritis, has been extensively used to study the molecular pathogenesis of Salmonella, because of the availability of sophisticated genetic tools, and of suitable animal and tissue culture models mimicking different aspects of Salmonella infections.(...)

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To study the macroeconomic effects of unconventional monetary policy across the different countries of the eurozone, I develop an identification scheme to disentangle conventional from non-conventional policy shocks, using futures contracts on overnight interest rates and the size of the European Central Bank balance sheet. Setting these shocks as endogenous variables in a structural vector autoregressive (SVAR) model, along with the CPI and the employment rate, estimated impulse response functions of policy to macroeconomic variables are studied. I find that unconventional policy shocks generated mixed effects in inflation but had a positive impact on employment, with the exception of Portugal, Spain, Greece and Italy where the employment response is close to zero or negative. The heterogeneity that characterizes the responses shows that the monetary policy measures taken in recent years were not sufficient to stabilize the economies of the eurozone countries under more severe economic conditions.

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RESUMO: As células dendríticas (CDs) são fundamentais na imunomodulação e iniciação de respostas imunes adaptativas, enquanto os ácidos siálicos (Sias) são potenciais imunomoduladores. Estas células expressam níveis elevados da sialiltransferase ST6Gal-1, que transfere Sias para a posição terminal de oligossacáridos. De facto, a maturação de CDs está associada a uma diminuição da sialilação na sua superfície celular. Apesar de ter função biológica desconhecida, a forma solúvel, extracelular de ST6Gal-1 aumenta em cancros e inflamação. Ainda assim, esta foi recentemente identificada como moduladora da hematopoiese. Considerando o importante papel das CDs na iniciação de respostas anticancerígenas, uma ligação entre a sialilação extrínseca induzida por ST6Gal-1 extracelular e o seu papel na modulação de CDs deve ser identificada. Neste trabalho hipotetizou-se que a sialilação α2,6 extrínseca de CDs diminui o seu perfil de maturação mediante ativação por lipopolissacarídeo (LPS). O objetivo principal foi sialilar extrinsecamente em α2,6 CDs da medula óssea de murganhos, avaliando os seus perfis de maturação e de libertação de citocinas, após estimulação com LPS (por Citometria de Fluxo e ELISA, respetivamente). Ao contrário da hipótese, o perfil celular não foi modulado, usando várias abordagens. Por outro lado, a consequência da falta de α2,6 Sias na maturação de CDs foi avaliada analisando: 1) CDs da medula óssea de murganhos tratadas com sialidase, 2) CDs da medula óssea e 3) CDs das vias aéreas, ambas de murganhos deficientes em ST6Gal-1, comparando com a estirpe selvagem. Estes resultados sugerem que a perta total de α2,6 Sias se relaciona com o aumento da expressão do complexo de histocompatibilidade principal de classe II. Apesar de controverso, é provável existirem mecanismos inerentes à ativação por LPS, reduzindo a eficácia de ST6Gal-1 extracelular. Por outro lado, a modificação no perfil de CDs de murganhos deficientes em ST6Gal-1 poderá relacionar-se com uma predisposição para um estado inflamatório severo. Com isto, o trabalho desenvolvido abriu futuras linhas de investigação, nomeadamente explorar outros fatores envolvidos na (de)sialilação α2,6 de CDs, podendo ter impacto em imunoterapia com uso de CDs.--------------------------ABSTRACT: Dendritic cells (DCs) are vital for immunomodulation and the initiation of adaptive immune responses, whereas sialic acids (Sias) are potential immunomodulators. These cells express high levels of sialyltransferase ST6Gal-1, responsible for transferring Sias to the terminal position of oligosaccharide chains. Indeed, DCs’ maturation is associated with decreased cell surface sialylation. Although its biological significance is unknown, the soluble, extracellular form of ST6Gal-1 increases in cancers and inflammation. However, extracellular ST6Gal-1 was recently identified as modulator of hematopoiesis. Considering that DCs play a crucial role in the initiation of a productive anti-cancer immune response, a link between extrinsic sialylation by the extracellular ST6Gal-1 on DC function needs to be investigated. We hypothesize that extrinsic α2,6 sialylation of DCs diminishes their maturation features upon lipopolysaccharide (LPS) stimulation. The main goal was to extrinsically α2,6 sialylate mice bone marrow derived DCs (BMDCs) and to evaluate their maturation and cytokine profiles upon LPS stimulation (by Flow Cytometry and ELISA, respectively). Unlike the hypothesis, we observed that BMDCs’ profile is not modulated, even using several approaches. In contrast, the consequence of lacking cell surface α2,6 Sias in DC maturation was assessed by analysing: 1) sialidase treated BMDCs, 2) BMDCs from mice lacking ST6Gal-1 and 3) DCs from mice airways, comparing wild type with ST6Gal-1 knockout mice. These results suggest that overall lack in α2,6 Sias is related with increased expression of major histocompatibility class II (MHC-II). Although appearing to be controversial findings, other intracellular mechanisms might be occurring upon LPS-induced BMDC activation, probably reducing extracellular ST6Gal-1 effect. In opposite, the modification observed in DC profile of ST6Gal-1 knockout mice might be related to its predisposition to a more severe inflammatory status. With this, the developed work opened future lines of investigation, namely exploring other factors involved in α2,6 (de)sialylation of DC, which might have influence in immunotherapy using DCs.

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We intend to study the algebraic structure of the simple orthogonal models to use them, through binary operations as building blocks in the construction of more complex orthogonal models. We start by presenting some matrix results considering Commutative Jordan Algebras of symmetric matrices, CJAs. Next, we use these results to study the algebraic structure of orthogonal models, obtained by crossing and nesting simpler ones. Then, we study the normal models with OBS, which can also be orthogonal models. We intend to study normal models with OBS (Orthogonal Block Structure), NOBS (Normal Orthogonal Block Structure), obtaining condition for having complete and suffcient statistics, having UMVUE, is unbiased estimators with minimal covariance matrices whatever the variance components. Lastly, see ([Pereira et al. (2014)]), we study the algebraic structure of orthogonal models, mixed models whose variance covariance matrices are all positive semi definite, linear combinations of known orthogonal pairwise orthogonal projection matrices, OPOPM, and whose least square estimators, LSE, of estimable vectors are best linear unbiased estimator, BLUE, whatever the variance components, so they are uniformly BLUE, UBLUE. From the results of the algebraic structure we will get explicit expressions for the LSE of these models.