An econophysics approach to analyse uncertainty in financial markets: an application to the Portuguese stock market

In recent years there has been a closer interrelationship between several scientific areas trying to obtain a more realistic and rich explanation of the natural and social phenomena. Among these it should be emphasized the increasing interrelationship between physics and financial theory. In this field the analysis of uncertainty, which is crucial in financial analysis, can be made using measures of physics statistics and information theory, namely the Shannon entropy. One advantage of this approach is that the entropy is a more general measure than the variance, since it accounts for higher order moments of a probability distribution function. An empirical application was made using data collected from the Portuguese Stock Market.Comment: 8 pages, 2 figures, presented in the conference Next Sigma-Phi 200

Mutual information: a dependence measure for nonlinear time series

This paper investigates the possibility to analyse the structure of unconditional or conditional (and possibly nonlinear) dependence in financial returns without requiring the specification of mean-variance models or a theoretical probability distribution. The main goal of the paper is to show how mutual information can be used as a measure of dependence in financial time series. One major advantage of this approach resides precisely in its ability to account for nonlinear dependencies with no need to specify a theoretical probability distribution or use of a mean-variance model.Mutual information, nonlinear dependence, market efficiency

Funcionamento executivo e sócio-emocional de crianças em idade pré-escolar: efeito de dois programas de intervençao - Psicomotricidade e dança criativa

Objetivo: Estudar a viabilidade e o efeito de dois programas, Psicomotricidade versus Dança Criativa, no funcionamento executivo e sócio-emocional de crianças do ensino pré-escolar. Metodologia: Cinquenta crianças de idade pré-escolar (M=4,04 anos; DP=0,67), foram divididas por dois grupos de intervenção de 14 semanas (programa de Psicomotricidade Vs. programa de Dança Criativa) e um grupo controlo. Foram avaliadas as funções executivas frias, as funções executivas quentes, os comportamentos externalizados e internalizados e a agressividade. Resultados: Os programas de intervenção realizados são bem tolerados por crianças pré-escolares. Não se encontraram diferenças significativas nas comparações intra e inter-observador, exceto no grupo controlo (p<0,05). As funções executivas frias correlacionam-se negativamente com a agressividade reativa (r= -0,408, p=0,003). Conclusão: Os resultados sugerem que ambos os programas são viáveis nesta faixa etária, mas não foram comprovados os seus benefícios. Uma melhor memória de trabalho é associada à diminuição dos níveis de agressividade reativa. Este estudo confirma a necessidade de mais investigações sobre esta temática; Abstract: Objective: To study the feasibility and the effect of two programs, Psychomotricity versus Creative Dance, on the executive and socio-emotional functioning of pre-school children. Methodology: Fifty preschool children (M = 4.04 years; SD = 0.67) were divided into two intervention groups of 14 weeks (Psychomotricity program Vs. Creative Dance program) and a control group. Cold executive functions, hot executive functions, externalized and internalized behaviors and aggressiveness were evaluated. Results: Intervention programs performed are well tolerated by pre-school children. No significant differences were found in intra and inter-observer comparisons, except in the control group (p <0.05). The cold executive functions negatively correlate with reactive aggressiveness (r = -0.408, p = 0.003). Conclusion: The results suggest that both programs are viable in this age group, but their benefits have not been proven. Better working memory is associated with decreased levels of reactive aggression. This study confirms the need for further research on this subject

The influence of human resources management practices on identity construction through the promotion of identity motives

Identity is a crucial factor in the human being’s life, comprising the sense we have in respect to who we are and the way we act and interact with the world around us. In this study, it is analyzed the way identity can be constructed, having as a basis six identity motives, namely, continuity, meaning, belonging, efficacy, distinctiveness, and self-esteem. The argument is that this identity construction can be promoted through the implementation of diverse human resources practices, applied in a context where the development of identity is encouraged, having been created a new concept for the effect, namely, identity enhancement context. In this context, the improvement of well-being and reduction of turnover intentions are considered consequences of the human resources practices promoted, as long as they reinforce identity construction. This argument was teste through a correlational study involving 394 participants. The results demonstrated that the identity enhancement context correlates positively with the identity motives, negatively with turnover and positively with well-being. Moreover, each of the identity motives has a negative association with turnover and a positive relationship with well-being, supporting the initial argument.A identidade é um fator crucial na vida do ser humano, compreendendo o sentido que temos relativamente ao que somos e à forma como agimos e interagimos com o mundo à nossa volta. Neste estudo é analisada a forma como a identidade pode ser construída, tendo por base seis motivos de identidade, nomeadamente, continuidade, significado, pertença, eficácia, distintividade e autoestima. O argumento é o de que esta construção da identidade pode ser promovida pela aplicação de diversas práticas de recursos humanos, usadas num contexto em que há um incentivo ao desenvolvimento da identidade, tendo sido criado um novo conceito para o efeito, nomeadamente, o contexto de aprimoramento de identidade. Neste contexto, o aumento do bem-estar e a redução da rotatividade são consideradas consequências das práticas de recursos humanos, desde que estas reforcem a construção da identidade. Este argumento foi testado através de um estudo correlacional envolvendo 394 participantes. Os resultados demonstraram mostram que o contexto de aprimoramento de identidade tem uma correlação positiva com os motivos de identidade, embora negativa com a intenção de rotatividade, e positiva com o bem-estar. Para além disso, verificou-se uma correlação negativa entre os motivos de identidade e a intenção de rotatividade, ao par de uma correlação positiva entre os motivos de identidade e o bem-estar, dando suporte ao argumento inicial

Developing active packaging solutions through incorporation of organic/inorganic active components in renewable materials.

The development of new antimicrobial active packaging systems have been gaining a raising interest due to its potential to increase product shelf-life and provide food quality and safety benefits allied to society demands on food-related health risks, multi-drug resistance and environmental problems. A great variety of organic substances such as phenolic compounds and essential oils as well as inorganic metal oxide nanoparticles such as Ag+, ZnO and TiO2 have been intensively studied for having antimicrobial properties, although their efficiency is highly dependent on the target microorganisms, the material or media where they act as well as the surrounding environment are relevant (Burt, 2004; Suppakul et al., 2003; Visai et al., 2011). Recent research in active packaging is mostly focused on the use of natural renewable material resources including preservatives to develop biodegradable and recyclable packaging products. Accordingly, the NEWGENPAK project was funded within ITN-Marie Skłodowska-Curie EU program with the aim “to take wood cellulose based material a significant step forward by replacing petroleum-based additives used in paper and board packaging materials in order to achieve the barrier and other crucial properties needed for competitive, low carbon footprint, packaging materials”. NEWGENPAK, the acronym for New Generation of Cellulose Fibre Based Packaging Materials for Sustainability, just finished in December 2015, was an interdisciplinary research training network (ITN) constituted by 8 European universities, 3 research institutes and 6 enterprises from all over Europe, with13 researchers working full time developing their own individual researcher projects, making collaborations and receiving training on the field. This PhD thesis was carried out within this project and developed mainly at Innovhub SSI – Paper Division, Milan, Italy. The main target of this work was to attain antibacterial cellulose-based materials for food packaging applications, following two approaches based in the incorporation of active organic components or active nanoparticles as active agents. Besides, it was studied the possibility to develop an antibacterial packaging for medical applications, in order to prevent medical cross contamination. The fate of the nanoparticles in the recycling process and their effect on the biodegradability of the packaging was initially assessed as an important part of environmental aspects related to the end of life of packaging products. The first approach, described in the chapter 2, aimed to explore the possibilities to extract polyphenols from black tea brewing residues and use them as active compounds for the development of active cellulosic-based surfaces. Therefore, the chemical characterization of black tea residues as well as the antioxidant and antimicrobial properties of their extracts were addressed. The best infusion conditions, considering the yield of extraction, the antioxidant activity and the total phenolic content, were found to be at 80ºC for 7.5 minutes for an infusion of 2.5 g of tea residue in 100 mL of water, and just 1.1 mg of these extract where enough to provide a bactericidal effect. The resulting paper coated with 3.8 g/m2 of polyphenols-based coating formulation attained a complete killing effect against S. aureus. In the second approach, several papers were functionalized with formulations based on photo-active TiO2 NPs by dip-coating and compared regarding their antibacterial activity. The results presented in the chapter 3 have shown that both handsheets of bleached Kraft pulp (BK) and chemithermomechanical pulp (CTMP) displayed a bactericidal effect against gram-positive Staphylococcus aureus and gram-negative Pseudomonas aeruginosa, even after three weeks of storage either in light and dark conditions, while pre-coated recycled paper (PCR) and bleached pre-coated Kraft (BPK) paper samples did not shown any antibacterial activity. The effect of TiO2 NPs against S. aureus was inhibited in: i) PCR samples due to the presence of considerable amounts of inorganic compounds, such as calcium carbonate, that shielded the effect of active nanoparticles; and ii) BPK samples, most likely due to their high hydrophobicity that did not permit a good retention of the NPs and homogenous coating distribution. Accordingly, different preparation methods and deposition techniques were considered for hydrophobic surfaces and compared regarding the amount of TiO2 incorporated in nanofibrillated cellulose (NFC) loaded and finally retained on the BPK paper surfaces. Under the best conditions with the polyelectrolyte-assisted deposition 90% of nanoparticles retention was attained against only 25% for the direct-mixture formulations. The antibacterial activity of the paper samples reached approximately 2 log bacterial reduction of S. aureus showing the possibility to achieve a contact active surface based on layer-by layer assembly NFC-TiO2 formulation. Moreover a scale-up pilot demonstration of an over-print varnish based on ZnO nanoparticles was performed to be loaded by flexographic printing at industrial scale for medical packaging applications. The SAFEBOX packaging demonstrator produced was loaded with only 5.6 mg/m2 of ZnO NPs based varnish, due to some technical production constraints and restrictions, therefore it presented a slightly bacteriostatic effect with less than one log reduction. However, with the possibility to increase the amount of NPs loaded on the paper surface, promising results can be achieved. Preliminary results obtained at lab scale showed a bactericidal effect, up to 4 log reduction, for papers with about 1,5g/m2 of ZnO NPs on the surface. Regarding the preliminary studies on environmental impact of NPs, towards packaging end-of-life options presented also in the chapter 3, laboratory tests have shown only marginal effect of active ingredients on biodegradability performance whereas recyclability tests have shown a reasonable good retention of TiO2 nanoparticles (approximately 90%) in the recycled fibres after one recycling loop

The contribution of Portuguese solar thermal program on the country energy efficiency

The solar radiation available all over the year is a strong reason to promote the utilization of this resource and during the year 2009, a new program based on a 50% subside, was promoted by the Portuguese government. As expected, a significant number of new installations were realized. In 2009 the state program provided the installation of more than 50,000 systems. The program can be considered a success on the Portuguese solar thermal collector market

On the use of virtual sensing for damage identification on wind turbine blades

With the recent growth in size and complexity of wind turbine blades, continuous monitoring has become imperative in reducing costs and downtime by preventing difficult maintenance and repair works. Using ambient excitation, dynamic responses are analysed with Vibration-based Structural Health Monitoring (VSHM) techniques to obtain modal parameters such as natural frequencies, mode shapes and damping ratios. For that, this study uses two output-only modal identification methods to identify those modal parameters from numerical and experimental responses, aiming to detect changes in those parameters attributed to damage. Using a cantilever beam, damage is introduced as a localized change in mass where, in the presence of damage, natural frequencies may present a decrease in value. Given the limitations of placing physical sensors on wind turbine blades, specially the ones in-service, this study uses measured responses from the structure and estimated ones at unmeasured locations, using data estimation techniques to create virtual sensors. The present objectives are to compare two modal identification methods and two response estimation ones, with the goal of understanding whether the use of virtual sensors improves damage detectability. The numerical comparison between the modal identification methods showed that both are capable of identifying modal parameters close to each other and to the numerical model ones. The results from both methods indicate that using virtual responses increases damage detectability for the same set of measurements. One of the methods provides more consistent results but requires higher computational efforts, whereas the other is much faster and simpler to use, although its results present slight variations. The comparison between the response estimation methods showed that, even with limitations, bothwere capable of identifying close modal parameters to each other. The experimental application validated the conclusions found with the numerical results, from all the methods’ behaviour to the enhancement of damage detectability.Com o recente crescimento em dimensão e complexidade de pás de turbinas eólicas, a sua monitorização contínua torna-se imperativa na redução de custos e de inatividade ao prevenir manutenções e reparações difíceis. Usando excitação ambiente, as respostas dinâmicas são analisadas através de técnicas de Monitorização da Condição Estrutural baseada em Vibrações para obter parâmetros modais, tais como frequências naturais, modos de vibração e fatores de amortecimento. Para tal, este estudo usa dois métodos de identificação modal para identificar esses parâmetros de respostas numéricas e experimentais, procurando detetar neles alterações atribuídas a dano. Numa viga encastrada, dano é introduzido como a alteração local de massa onde, na sua presença, frequências naturais podem apresentar uma redução de valor. Dadas as limitações na colocação de sensores físicos nas pás, especialmente naquelas em funcionamento, este estudo usa respostas medidas da estrutura e estima respostas em localizações não medidas através de técnicas de estimação com sensores virtuais. Os objetivos passam por comparar dois métodos de identificação modal e dois de expansão de respostas, procurando perceber se a utilização de sensores virtuais melhora a detetabilidade de dano. A comparação numérica entre os métodos de identificação modal mostrou que ambos são capazes de identificar parâmetros modais próximos entre si e aos do modelo numérico. Os resultados de ambos indicam que a utilização de respostas virtuais melhora a detetabilidade de dano para os mesmos conjuntos de respostas. Um dos métodos obtém resultados mais consistentes mas exige maior esforço computacional, enquanto que o outro é mais rápido e simples de usar, mas os resultados apresentam ligeiras variações. A comparação entre métodos de expansão de respostas mostrou que, mesmo com as limitações, ambos são capazes de identificar parâmetros modais próximos entre si. A aplicação experimental validou as conclusões obtidas através dos resultados numéricos, desde dos comportamentos dos métodos até à intensificação da detetabilidade de dano

Developing active packaging solutions through incorporation of organic/inorganic active components in renewable materials.

The development of new antimicrobial active packaging systems have been gaining a raising interest due to its potential to increase product shelf-life and provide food quality and safety benefits allied to society demands on food-related health risks, multi-drug resistance and environmental problems. A great variety of organic substances such as phenolic compounds and essential oils as well as inorganic metal oxide nanoparticles such as Ag+, ZnO and TiO2 have been intensively studied for having antimicrobial properties, although their efficiency is highly dependent on the target microorganisms, the material or media where they act as well as the surrounding environment are relevant (Burt, 2004; Suppakul et al., 2003; Visai et al., 2011). Recent research in active packaging is mostly focused on the use of natural renewable material resources including preservatives to develop biodegradable and recyclable packaging products. Accordingly, the NEWGENPAK project was funded within ITN-Marie Skłodowska-Curie EU program with the aim “to take wood cellulose based material a significant step forward by replacing petroleum-based additives used in paper and board packaging materials in order to achieve the barrier and other crucial properties needed for competitive, low carbon footprint, packaging materials”. NEWGENPAK, the acronym for New Generation of Cellulose Fibre Based Packaging Materials for Sustainability, just finished in December 2015, was an interdisciplinary research training network (ITN) constituted by 8 European universities, 3 research institutes and 6 enterprises from all over Europe, with13 researchers working full time developing their own individual researcher projects, making collaborations and receiving training on the field. This PhD thesis was carried out within this project and developed mainly at Innovhub SSI – Paper Division, Milan, Italy. The main target of this work was to attain antibacterial cellulose-based materials for food packaging applications, following two approaches based in the incorporation of active organic components or active nanoparticles as active agents. Besides, it was studied the possibility to develop an antibacterial packaging for medical applications, in order to prevent medical cross contamination. The fate of the nanoparticles in the recycling process and their effect on the biodegradability of the packaging was initially assessed as an important part of environmental aspects related to the end of life of packaging products. The first approach, described in the chapter 2, aimed to explore the possibilities to extract polyphenols from black tea brewing residues and use them as active compounds for the development of active cellulosic-based surfaces. Therefore, the chemical characterization of black tea residues as well as the antioxidant and antimicrobial properties of their extracts were addressed. The best infusion conditions, considering the yield of extraction, the antioxidant activity and the total phenolic content, were found to be at 80ºC for 7.5 minutes for an infusion of 2.5 g of tea residue in 100 mL of water, and just 1.1 mg of these extract where enough to provide a bactericidal effect. The resulting paper coated with 3.8 g/m2 of polyphenols-based coating formulation attained a complete killing effect against S. aureus. In the second approach, several papers were functionalized with formulations based on photo-active TiO2 NPs by dip-coating and compared regarding their antibacterial activity. The results presented in the chapter 3 have shown that both handsheets of bleached Kraft pulp (BK) and chemithermomechanical pulp (CTMP) displayed a bactericidal effect against gram-positive Staphylococcus aureus and gram-negative Pseudomonas aeruginosa, even after three weeks of storage either in light and dark conditions, while pre-coated recycled paper (PCR) and bleached pre-coated Kraft (BPK) paper samples did not shown any antibacterial activity. The effect of TiO2 NPs against S. aureus was inhibited in: i) PCR samples due to the presence of considerable amounts of inorganic compounds, such as calcium carbonate, that shielded the effect of active nanoparticles; and ii) BPK samples, most likely due to their high hydrophobicity that did not permit a good retention of the NPs and homogenous coating distribution. Accordingly, different preparation methods and deposition techniques were considered for hydrophobic surfaces and compared regarding the amount of TiO2 incorporated in nanofibrillated cellulose (NFC) loaded and finally retained on the BPK paper surfaces. Under the best conditions with the polyelectrolyte-assisted deposition 90% of nanoparticles retention was attained against only 25% for the direct-mixture formulations. The antibacterial activity of the paper samples reached approximately 2 log bacterial reduction of S. aureus showing the possibility to achieve a contact active surface based on layer-by layer assembly NFC-TiO2 formulation. Moreover a scale-up pilot demonstration of an over-print varnish based on ZnO nanoparticles was performed to be loaded by flexographic printing at industrial scale for medical packaging applications. The SAFEBOX packaging demonstrator produced was loaded with only 5.6 mg/m2 of ZnO NPs based varnish, due to some technical production constraints and restrictions, therefore it presented a slightly bacteriostatic effect with less than one log reduction. However, with the possibility to increase the amount of NPs loaded on the paper surface, promising results can be achieved. Preliminary results obtained at lab scale showed a bactericidal effect, up to 4 log reduction, for papers with about 1,5g/m2 of ZnO NPs on the surface. Regarding the preliminary studies on environmental impact of NPs, towards packaging end-of-life options presented also in the chapter 3, laboratory tests have shown only marginal effect of active ingredients on biodegradability performance whereas recyclability tests have shown a reasonable good retention of TiO2 nanoparticles (approximately 90%) in the recycled fibres after one recycling loop

Entropy-Based Independence Test

This paper presents a new test of independence (linear and non-linear) among distributions based on the entropy of Shannon. The main advantages of the presented approach are the fact that this measure does not need to assume any type of theoretical probability distribution and has the ability to capture the linear and non-linear dependencies, without requiring the specification of any kind of dependence model