Influência das variáveis macroeconómicas e fatores económico-financeiros na rendibilidade das ações dos Bancos Portugueses

Versão final (Esta versão contém as críticas e sugestões dos elementos do júri)Esta dissertação consiste numa investigação empírica ao desempenho das ações dos bancos cotados na Euronext Lisbon, no período 2004-2019. Este intervalo temporal reflete inúmeras alterações na evolução da economia portuguesa e no seu setor financeiro, incluindo duas crises, a crise financeira global de 2007-2009 e a crise da dívida soberana portuguesa. O seu objetivo principal é analisar os determinantes com maiores impactos na rendibilidade das ações no setor bancário português. Para este propósito é formulado um modelo econométrico de dados de painel, onde se inclui fatores económico-financeiros específicos dos bancos (CAMEL) e variáveis macroeconómicas caraterizadoras da evolução da economia portuguesa. É testado por meio de análise de regressão múltipla, com recurso a estimadores Panel Least Squares (PLS), com efeitos fixos e aleatórios. Conclui-se pela significância estatística global do modelo, evidenciando diferente níveis de poder explicativo em função das várias versões do modelo. Os resultados mostram que o ROE, a par da rendibilidade do mercado de capitais (RENME), são os fatores que se apresentam significativamente mais relacionados com o preço das ações e a sua rendibilidade. Além disso, o tamanho do banco, medido pela quota de mercado, também se mostra significativo embora com sinal negativo. O estudo evidencia ainda que os efeitos da qualidade dos ativos e a liquidez têm importância estatística em duas versões do modelo. As variáveis macroeconómicas incluídas no modelo 2 mostram-se confiáveis para explicar a rendibilidade das ações, o mesmo não sucedendo na terceira variante do modelo, onde a sua perda de influência pode estar associada à inclusão da rendibilidade do mercado de capitais. O estudo suporta a hipótese de influência das crises na rendibilidade das ações dos bancos, como esperado.This dissertation consists of an empirical investigation of the performance of the shares of banks listed on Euronext Lisbon, in the period 2004-2019. This time interval reflects many changes in the evolution of the Portuguese economy and its financial sector, including two crises, the global financial crisis of 2007-2009 and the Portuguese sovereign debt crisis. Main target is to analyse the determinants with the greatest impact on the profitability of shares in the Portuguese banking sector. For this reason, an econometric model of panel data is formulated, which includes bank-specific economic and financial factors (CAMEL) and macroeconomic variables that characterize the evolution of the Portuguese economy. It is tested by multiple regression analysis, using Panel Least Squares (PLS) estimators, with fixed and random effects also. It concludes by the global statistical significance of the model, showing different levels of explanatory power depending on the various versions of the model. The results show that ROE, together with the profitability of the capital market (RENME), are the factors that are much more related to the share price and its profitability. In addition, the size of the bank, measured by market share, is also significant, albeit with a negative sign. The study also shows that the effects of asset quality and liquidity are statistically important in two versions of the model. The macroeconomic variables included in model 2 are reliable to explain the profitability of the shares, the same not happening in the third variant of the model, where its loss of influence may be associated with the inclusion of the profitability of the capital market. Changes in shareholder profitability were noticed during financial crises and in the period immediately after crises. The study supports the hypothesis of crises influence the profit of bank shares, as expected

The role of glyclinergic interneurons in the dorsal column nuclei

[Abstract] The aim of this paper is to provide new insights about the circuitry and the role of the dorsal column nuclei (DCN) in processing somatosensory information. The presence of glycinergic cells, a second type of DCN interneurons in addition to well-known GABAergic interneurons, opens the door to more complex interactions between cuneate cells as well as to a new hypothesis about the computational implications of such interactions. The research posed here fits in a broader context in the field of the sensory systems and deals with the general issue on the role of subcortical structures (i.e the thalamus) in processing sensory information

Sleep and wakefulness in the cuneate nucleus: a computational study

We present a computational study about the influence of the sensorimotor cortex on the processing of the cuneate nucleus during sleep as well as wakefulness. Realistic computational models were developed supported by experimental data obtained from intact-brain preparations in cat. Furthermore, a physiologically plausible circuit is proposed and predictions under both different cortical stimulation and synaptic configurations are suggested. The computer simulations show that the CN circuitry (1) under sleep conditions can block the transmission of afferent sensory information, and (2) under awaking conditions can perform operations such as filtering and facilitation

A Computational Model of Cuneothalamic Projection Neurons

[Abstract] The dorsal column nuclei, cuneatus and gracilis, play a fundamental role in the processing and integration of somesthetic ascending information. Intracellular and patch-clamp recordings obtained in cat in vivo have shown that cuneothalamic projection neurons present two modes of activity: oscillatory and tonic (Canedo et al 1998 Neuroscience 84 603–17). The former is the basis of generating, in sleep and anaesthetized states, slow, delta and spindle rhythms under the control of the cerebral cortex (Mari˜no et al 2000 Neuroscience 95 657–73). The latter is needed, during wakefulness, to process somesthetic information in real time. To study this behaviour we have developed the first realistic computational model of the cuneothalamic projection neurons. The modelling was guided by experimental recordings, which suggest the existence of hyperpolarization-activated inward currents, transient low- and high-threshold calcium currents, and calcium-activated potassium currents. The neuronal responses were simulated during (1) sleep, (2) transition from sleep to wakefulness and (3) wakefulness under both excitatory and inhibitory synaptic input. In wakefulness the model predicts a set of synaptically driven firing modes that could be associated with information processing strategies in the middle cuneate nucleus

A realistic computational model of the local circuitry of the cuneate nucleus

Intracellular recordings obtained under cutaneous and lemniscal stimulation show that the afferent fibers can establish excitatory and inhibitory synaptic connections with cuneothalamic neurons [5]. In addition, distinct types of recurrent collaterals with the capability of either exciting or inhibiting both cuneothalamic neurons and interneurons were also discovered [6]. With these data we have generated hypothesis about which circuits are implicated and also developed realistic computational models to test the hypothesis and study the cuneate properties [17,18]. The results show that the cuneate could perform spatial and temporal filtering and therefore detect dynamic edges

Cortical modulation of dorsal column nuclei: a computational study

[Abstract] We present a computational study aimed at exploring the sensorimotor cortex modulation of the behaviour of dorsal column nuclei, specifically the impact of synaptic parameters, during both sleep and waking conditions. On the basis of the circuit proposed by Canedo et al. (2000), we have developed realistic computational models that have been tested with simultaneous electrocorticographic as well as intracellular cuneate recordings performed in anaesthetized cats. The results show that, (1) under sleep conditions, the model can block the transmission of afferent sensory information and, (2) operations expected during wakefulness, such as filtering and facilitation, can be performed if synaptic parameters are appropriately tuned.Argentina. Consejo Interinstitucional de Ciencia y Tecnología; PB01-121212Xunta de Galicia; XU02–211

Evaluación de la calidad de enlaces de telecomunicaciones a través de herramientas de estimación del ancho de banda disponible en redes de computadores heterogéneas

Currently, the global network "Internet" has been the medium through which companies, universities, schools, homes and individuals carry out telecommunications activities. The infrastructure of Internet provider companies faces new challenges every day due to the growth in demand with more content, such as video streaming, webinars, virtual classes, data processing, storage, and cloud processing. Given the high data consumption at present it has been difficult to maintain optimal levels of quality of service, network applications demand more telecommunications resources. Although the network infrastructures that support these applications have evolved, there is a need for greater and more efficient administration of the trunk links, which play a primary role in sustaining services. To evaluate the quality of telecommunications links in heterogeneous computer networks with the support of Available Bandwidth Estimation (ab_bw) Tools, is to find the values that allow improving the performance of various protocols and applications that can be implemented in heterogeneous networks. To estimate the ab_bw, the current tools insert test packages in addition to those already existing on the network. This additional traffic in a network is called Overhead, which will allow the bandwidth estimation analysis tools to be intrusive when using part of the channel bandwidth that they are measuring. In this project, the performance evaluation of the trunks, wired and wireless will be carried out in a heterogeneous computer network infrastructure, using available bandwidth estimation tools such as IGI, Pathload and Traceband. Thus, for the experimental evaluation of the links, two real network scenarios were implemented, where the cross traffic was generated synthetically using the Mgen tool. This study verified that the metrics of the estimation tools can be used to evaluate and know the performance of wired and wireless links, which can be up to 96% reliable for network administrative tasks.En la actualidad, la red global “Internet” ha sido el medio a través del cual las empresas, universidades, colegios, hogares y personas desarrollan las actividades de telecomunicaciones. La infraestructura de las empresas proveedoras de internet cada día se enfrenta a nuevos desafíos debido al crecimiento de la demanda con mayor contenido, como es el caso del vídeo streaming, webinar, clases virtuales, procesamiento de datos, almacenamiento y procesamiento en la nube. Así mismo, dado el alto consumo de datos en le redes de computadores, actualmente se ha dificultado mantener niveles óptimos de calidad de servicio, las aplicaciones de red demandan más recursos de telecomunicaciones siendo este, uno de los principales motivos de mantener dichos niveles. Aunque, las infraestructuras de red que soportan esas aplicaciones han evolucionado, es necesario una mayor y eficiente administración de los enlaces troncales, que juegan un rol primario en el sostenimiento de los servicios. Así, evaluar la calidad de enlaces de telecomunicaciones en redes de computadores heterogéneas con la ayuda de herramientas de estimación del ancho de banda disponible (ab_disp), es hallar los valores que permitan mejorar el rendimiento de varios protocolos y aplicaciones que se pueden implementar en redes heterogéneas. Para realizar una estimación del ab_disp, las herramientas actuales insertan en la red evaluada paquetes adicionales de prueba, que son llamados Sobrecarga (Overhead). En consecuencia, la sobrecarga convierte las herramientas de análisis de estimación de ancho de banda disponible, en intrusivas al utilizar parte del ancho de banda del canal que están midiendo. Por lo tanto, este proyecto se llevará a cabo la evaluación del rendimiento de los enlaces troncales, cableado e inalámbrico en una infraestructura de redes de computadores heterogéneas, utilizando herramientas de estimación de ancho de banda disponible como IGI, Pathload y Traceband. Así, para la evaluación experimental de los enlaces, se implementaron dos escenarios reales de red, donde el tráfico cruzado fue generado de manera sintética utilizando la herramienta Mgen. Finalmente, este estudio permitió comprobar que las métricas de las herramientas de estimación se pueden utilizar para evaluar y conocer el rendimiento de enlaces cableados e inalámbricos, demostrando que pueden ser confiables hasta en un 96% para desarrollar labores administrativas de red

Avaliação da resistência flexural de resinas compostas convencionais e do sistema bulkfill

O constante aprimoramento dos materiais odontológicos é impulsionado pelas pesquisas científicas que, por sua vez,são incentivadas pelo mercado consumidor que busca tratamentos estéticos e duráveis. Objetivo: avaliar a resistência flexuralde duas resinas compostas convencionais e uma resina composta do sistema bulkfill. Metodologia: foram utilizadas as resinas compostas: Z100TM (microhíbrida), FiltekTM Z350 XT (nanoparticulada) e a FiltekTM Bulk fill (sistema bulkfill). Foram confeccionados dez corpos de prova de cada compósito (25x2x2mm). Testes mecânicos para avaliação da resistência flexural foram realizados, os valores de força obtidos para fratura do corpo de prova foram, então, transformados em MPa. Resultados: o valor médio de resistência flexural médio encontrado para o grupo Z100TM=108,43MPa, para o grupo FiltekTM Bulk Fill=133,30MPa e para o grupo FiltekTM XT Z350=172,53MPa. Conclusões: a resina composta convencional denanoparticulaFiltekTM XT Z350 apresentou os maiores valores de resistência flexural, seguida da resina FiltekTMBulk fill. A resina Z100TM apresentou os menores valores médios de resistência flexura

Mercado laboral, desempleo femenino y brechas por género en Colombia

Incluye referencias bibliográficas (páginas 176-177