On the Problem of Balancing the DC Capacitor Voltage Divider in Back-to-Back Multilevel Converters

This paper presents a new generalized solution for DC bus capacitors voltage balancing in back-to-back m level diode-clamped multilevel converters connecting AC networks. The solution is based on the DC bus average power flow and exploits the switching configuration redundancies. The proposed balancing solution is particularized for the back-to-back multilevel structure with m=5 levels. This back-to-back converter is studied working with bidirectional power flow, connecting an induction machine to the power grid.

Variáveis psicológicas e percepção do estado de saúde em indivíduos submetidos a ressincronização cardíaca

A insuficiência cardíaca afecta cerca de 261 mil pessoas em Portugal constituindo um problema de saúde pública. Pretendemos avaliar aspectos associados à recuperação do estado de saúde nesta síndrome, em particular a esperança, o afecto e a felicidade. Recorremos a um estudo longitudinal com 128 indivíduos sintomáticos com má fracção de ejecção do ventrículo esquerdo. Utilizámos um questionário para caracterizar os aspectos sóciodemográficos, clínicos e funcionais, o Kansas City Cardiomiopathy Questionnaire (KCCQ) para avaliar a qualidade de vida, a Subjective Hapiness Scale (SHS) para a felicidade, a HOPE Scale (HOPE) para a esperança e a Positive And Negative Afect Schedule (PANAS) para o afecto. Os questionários de caracterização sócio-demográfica, clínica e funcional, KCCQ e o SHS foram aplicados em três momentos: no internamento, prévio à instituição de terapêutica médica na sua totalidade e ao terceiro e sexto mês após a intervenção médica, na consulta externa. A maioria dos participantes eram homens em classe III da classificação da New York Heart Association com etiologia isquémica. No internamento e antes da terapêutica médica, observámos que a esperança, a felicidade e o afecto se relacionaram com a qualidade de vida, a felicidade e o afecto positivo com a esperança. No período avaliado foram submetidos a: terapia de ressincronização cardíaca (n=52), cardioversor-desfibrilhador implantável (n=44), cirurgia valvular com revascularização do miocárdio (n=14), optimização terapêutica farmacológica (n=10), transplante cardíaco (n=8). Foram significativos os resultados da qualidade de vida, da classificação da New York Heart Association, do exercício físico, da fracção de ejecção do ventrículo esquerdo e das arritmias cardíacas (estrasístoles e taquicardias ventriculares). A felicidade foi preditora da qualidade de vida e da funcionalidade. O afecto negativo foi preditor da satisfação com a insuficiência cardíaca. Concluímos da importância das variáveis positivas a par dos procedimentos médicos no tratamento das pessoas com insuficiência cardíaca. ABSTRACT - Heart failure affects about 261 000 people in Portugal constituting a public health problem. We intend to evaluate aspects of the health recovery in this syndrome, in particular hope, affection and happiness. We used a longitudinal study with 128 symptomatic patients with poor ejection fraction of left ventricle. We used a questionnaire to characterize the socio-demographic, clinical and functional aspects, the Kansas City Cardiomiopathy Questionnaire (KCCQ) to assess the quality of life, the Subjective Happiness Scale (SHS) for happiness, the HOPE Scale (HOPE) for hope and the Positive And Negative Affect Schedule (PANAS) for affection. The questionnaires of sociodemographic, clinical and functional KCCQ and SHS were applied on three occasions: on admission, prior to the execution of medical therapy in its totality and in the third and sixth months after medical intervention in the outpatient. Most of the participants were men in Class III New York Heart Association classification with ischemic etiology. At admission and before medical therapy, we observed that the hope, happiness and affection were related to the quality of life, happiness and positive affect with hope. Over the studied period were submitted to: cardiac resynchronization therapy (n=52), implantable cardioverter-defibrillator (n=44), valvular surgery with coronary artery bypass graft surgery (n=14), optimizing drug therapy (n=10), heart transplant (n=8). The significant results were the quality of life, the New York Heart Association classification, the exercise, the ejection fraction and left ventricular cardiac arrhythmias (ventricular tachycardia and estrasistoles). Happiness was a predictor of quality of life and functionality. The negative affect was a predictor of satisfaction with heart failure. We concluded that the positive variables and the medical procedures were important in treating people with heart failure.

Formaldehyde in indoor air: a public health problem?

Formaldehyde was the first air pollutant, which already in the 1970s emerged as a specifically non-industrial indoor air quality problem. Yet formaldehyde remained an indoor air quality issue and the formaldehyde level in residential indoor air is among the highest of any indoor air contaminant. Formaldehyde concentrations in 4 different indoor settings (schools, office buildings, new dwellings and occupied dwellings) in Portugal were measured using Photo Ionization Detection (PID) equipment (11,7 eV lamps). All the settings presented results higher than the reference value proposed by Portuguese legislation. Furthermore, occupied dwellings showed 3 units with results above the reference. We could conclude that formaldehyde presence is a reality in monitored indoor settings. Concentration levels are higher than the Portuguese reference value for indoor settings and these can indicate health problems for occupants.

The problem of estimating the volatility of zero coupon bond interest rate

Financial literature and financial industry use often zero coupon yield curves as input for testing hypotheses, pricing assets or managing risk. They assume this provided data as accurate. We analyse implications of the methodology and of the sample selection criteria used to estimate the zero coupon bond yield term structure on the resulting volatility of spot rates with different maturities. We obtain the volatility term structure using historical volatilities and Egarch volatilities. As input for these volatilities we consider our own spot rates estimation from GovPX bond data and three popular interest rates data sets: from the Federal Reserve Board, from the US Department of the Treasury (H15), and from Bloomberg. We find strong evidence that the resulting zero coupon bond yield volatility estimates as well as the correlation coefficients among spot and forward rates depend significantly on the data set. We observe relevant differences in economic terms when volatilities are used to price derivatives.

Fungal contamination of poultries litter: a public health problem

Exposure to certain fungi can cause human illness. Fungi cause adverse human health effects through three specific mechanisms: generation of a harmful immune response (e.g., allergy or hypersensitivity pneumonitis); direct infection by the fungal organism; by toxic-irritant effects from mold byproducts, such as mycotoxins. In Portugal there is an increasingly industry of large facilities that produce whole chickens for domestic consumption and only few investigations have reported on fungal contamination of the poultry litter. The material used for poultry litter is varied but normally can be constitute by: pine shavings; sawdust of eucalyptus; other types of wood; peanut; coffee; sugar cane; straw; hay; grass; paper processed. Litter is one of the most contributive factors to fungal contamination in poultries. Spreading litter is one of the tasks that normally involve higher exposure of the poultry workers to dust, fungi and their metabolites, such as VOC’s and mycotoxins. After being used and removed from poultries, litter is ploughed into agricultural soils, being this practice potentially dangerous for the soil environment, as well for both humans and animals. The goal of this study was to characterize litter’s fungal contamination and also to report the incidence of keratinophilic and toxigenic fungi.

Positive Solutions of the Dirichlet Problem for the One-dimensional Minkowski-Curvature Equation

We discuss existence and multiplicity of positive solutions of the Dirichlet problem for the quasilinear ordinary differential equation-(u' / root 1 - u'(2))' = f(t, u). Depending on the behaviour of f = f(t, s) near s = 0, we prove the existence of either one, or two, or three, or infinitely many positive solutions. In general, the positivity of f is not required. All results are obtained by reduction to an equivalent non-singular problem to which variational or topological methods apply in a classical fashion.

Fungal contamination of poultry litter: a public health problem

Although numerous studies have been conducted on microbial contaminants associated with various stages related to poultry and meat products processing, only a few reported on fungal contamination of poultry litter. The goals of this study were to (1) characterize litter fungal contamination and (2) report the incidence of keratinophilic and toxigenic fungi presence. Seven fresh and 14 aged litter samples were collected from 7 poultry farms. In addition, 27 air samples of 25 litters were also collected through impaction method, and after laboratory processing and incubation of collected samples, quantitative colony-forming units (CFU/m3) and qualitative results were obtained. Twelve different fungal species were detected in fresh litter and Penicillium was the most frequent genus found (59.9%), followed by Alternaria (17.8%), Cladosporium (7.1%), and Aspergillus (5.7%). With respect to aged litter, 19 different fungal species were detected, with Penicillium sp. the most frequently isolated (42.3%), followed by Scopulariopsis sp. (38.3%), Trichosporon sp. (8.8%), and Aspergillus sp. (5.5%). A significant positive correlation was found between litter fungal contamination (CFU/g) and air fungal contamination (CFU/m3). Litter fungal quantification and species identification have important implications in the evaluation of potential adverse health risks to exposed workers and animals. Spreading of poultry litter in agricultural fields is a potential public health concern, since keratinophilic (Scopulariopsis and Fusarium genus) as well as toxigenic fungi (Aspergillus, Fusarium, and Penicillium genus) were isolated.

Famílias de crianças com perturbações do espectro do autismo: contributos para a compreensão das suas necessidades

Dissertação apresentada à Escola Superior de Educação de Lisboa para a obtenção do grau de Mestre em Ciências da Educação - Especialização em Intervenção Precoce

Fast growing fungi: a problem to be solved to achieve characterization of occupational exposure to fungi in cork industry

Chrysonilia sitophila is a common mould in cork industry and has been identified as a cause of IgE sensitization and occupational asthma. This fungal species have a fast growth rate that may inhibit others species’ growth causing underestimated data from characterization of occupational fungal exposure. Aiming to ascertain occupational exposure to fungi in cork industry, were analyzed papers from 2000 about the best air sampling method, to obtain quantification and identification of all airborne culturable fungi, besides the ones that have fast-growing rates. Impaction method don’t allows the collection of a representative air volume, because even with some media that restricts the growth of the colonies, in environments with higher fungal load, such as cork industry, the counting of the colonies is very difficult. Otherwise, impinger method permits the collection of a representative air volume, since we can make dilution of the collected volume. Besides culture methods that allows fungal identification trough macro- and micro-morphology, growth features, thermotolerance and ecological data, we can apply molecular biology with the impinger method, to detect the presence of non-viable particles and potential mycotoxin producers’ strains, and also to detect mycotoxins presence with ELISA or HPLC. Selection of the best air sampling method in each setting is crucial to achieve characterization of occupational exposure to fungi. Information about the prevalent fungal species in each setting and also the eventual fungal load it’s needed for a criterious selection.

Public relations, satisfaction and commitment

The importance of the organizational relationship (senior managers) with an internal public (employees) is the main focus of this research, aiming to understand how this relationship differs between the different publics. Nowadays, the relevance attributed by Public Relations to this relationship is crucial. The main purpose is to identify two consistent models to measure the impact of an organizational relationship on the internal public. The second purpose is to identify how the internal public react to this organizational relationship, namely by gender. The research was conducted in nine Portuguese companies with a sample of 1.244 subjects in order to study the context of the relationship and validate the identified models. The results show the gender stereotypes in the relationship in these companies and that the organizational relationship has an impact on organizational commitment with a consistent model that highlights the impact of Public Relations on a company's productivity.

Public relations, satisfaction and commitment

The importance of the relationship with an internal public is the main focus of our research. Nowadays, the relevance attributed by Public Relations to this relationship is crucial. Our purpose is to identify two consistent models to measure the impact of an organizational relationship on its internal public. The research was conducted in nine Portuguese companies with a sample of 1244 subjects in order to study the context of the relationship and validate the identified models. The results show us the gender stereotypes in the relationship in these companies and that it is possible to identify the impact of Public Relations on a company's productivity.

EWASTEU Programme: proposals to minimise the problem of e‑waste

Hoje em dia muitos dos equipamentos elétricos e eletrónicos que compramos ficam obsoletos num curto espaço de tempo por causa dos rápidos avanços tecnológicos neste campo. Equipamentos como computadores, telemóveis e equipamentos elétricos e eletrónicos de pequeno e grande porte são transformados em lixo eletrónico e muitos deles são despejados no lixo comum. Para alterar este cenário, a União Europeia publicou diretivas neste domínio com o intuito de controlar o crescimento do lixo eletrónico e reduzir o seu impacto. Neste contexto, a Universidade de Yaşar (Turquia) submeteu à União Europeia um projeto (EWASTEU) com o objetivo de fornecer uma visão do que está acontecer com o equipamento transformado em lixo eletrónico e de apresentar algumas propostas para minimizar este problema. Uma das principais questões a ser respondida será a adequação das diretivas europeias.

Positive radial solutions of the Dirichlet problem for the Minkowski-Curvature equation in a ball

We study the existence and multiplicity of positive radial solutions of the Dirichlet problem for the Minkowski-curvature equation { -div(del upsilon/root 1-vertical bar del upsilon vertical bar(2)) in B-R, upsilon=0 on partial derivative B-R,B- where B-R is a ball in R-N (N >= 2). According to the behaviour off = f (r, s) near s = 0, we prove the existence of either one, two or three positive solutions. All results are obtained by reduction to an equivalent non-singular one-dimensional problem, to which variational methods can be applied in a standard way.

PBL in healthcare sciences: a case study on curriculum innovation

Students of a Cardiopulmonary Sciences curriculum in a Portuguese higher education institution have shown poor learning outcomes and low satisfaction on a course about lung function tests. A transmissive pedagogical approach, mainly based on lectures, was the common teaching practice. Aiming for a change, PBL was considered as a powerful alternative and also as a contribution for progressively innovating the curriculum. Purpose: to create PBL activities in a lung function tests course. to describe their implementation, to analyse the effects of PBL integration in students’ performance and attitudes, to characterize the generated learning environment.

Performing PET/CT studies: do they create anxiety?

Introduction: Anxiety is a common problem in primary care and specialty medical settings. Treating an anxious patient takes more time and adds stress to staff. Unrecognised anxiety may lead to exam repetition, image artifacts and hinder the scan performance. Reducing patient anxiety at the onset is probably the most useful means of minimizing artifactual FDG uptake, both fat brown and skeletal muscle uptake, as well patient movement and claustrophobia. The aim of the study was to examine the effects of information giving on the anxiety levels of patients who are to undergo a PET/CT and whether the patient experience is enhanced with the creation of a guideline. Methodology: Two hundred and thirty two patients were given two questionnaires before and after the procedure to determine their prior knowledge, concerns, expectations and experiences about the study. Verbal information was given by one of the technologists after the completion of the first questionnaire. Results: Our results show that the main causes of anxiety in patients who are having a PET/CT is the fear of the procedure itself, and fear of the results. The patients who suffered from greater anxiety were those who were scanned during the initial stage of a disease. No significant differences were found between the anxiety levels pre procedural and post procedural. Findings with regard to satisfaction show us that the amount of information given before the procedure does not change the anxiety levels and therefore, does not influence patient satisfaction. Conclusions: The performance of a PET/CT scan is an important and statistically generator of anxiety. PET/CT patients are often poorly informed and present with a range of anxieties that may ultimately affect examination quality. The creation of a guideline may reduce the stress of not knowing what will happen, the anxiety created and may increase their satisfaction in the experience of having a PET/CT scan.