A comprehensive review on modular multilevel converters, submodule topologies, and modulation techniques

The concept of the modular multilevel converter (MLC) has been raising interest in research in order to improve their performance and applicability. The potential of an MLC is enormous, with a great focus on medium- and high-voltage applications, such as solar photovoltaic and wind farms, electrified railway systems, or power distribution systems. This concept makes it possible to overcome the limitation of the semiconductors blocking voltages, presenting advantageous characteristics. However, the complexity of implementation and control presents added challenges. Thus, this paper aims to contribute with a critical and comparative analysis of the state-of-the-art aspects of this concept in order to maximize its potential. In this paper, different power electronics converter topologies that can be integrated into the MLC concept are presented, highlighting the advantages and disadvantages of each topology. Nevertheless, different modulation techniques used in an MLC are also presented and analyzed. Computational simulations of all the modulation techniques under analysis were developed, based on four cascaded full-bridge topologies. Considering the simulation results, a comparative analysis was possible to make regarding the symmetry of the synthesized waveforms, the harmonic content, and the power distribution in each submodule constituting the MLC.This work has been supported by FCT—Fundação para a Ciência e Tecnologia, within the R&D Units Project Scope UIDB/00319/2020. Mr. Luis A. M. Barros is supported by the doctoral scholarship PD/BD/143006/2018, granted by the Portuguese FCT foundation

Balancing the active power of a railway traction power substation with an sp-RPC

The railway system is one of the safest, most efficient, and environmentally friendly means of land transport for people and goods. However, as the demand for mobility has increased, the current railway system has shown some weaknesses, requiring an increase in catenary power in order to be able to supply power to longer trains and faster locomotives, as well as to increase rail traffic. This paper proposes a control algorithm to be implemented in a sectioning post-Rail Power Conditioner (sp-RPC). The sp-RPC is connected to the neutral section between two traction power substations (TPS). With the control algorithm, it is possible to minimize the existing unbalance of the active powers of each TPS. In a regenerative braking condition, this surplus energy can be used to assist the traction of another locomotive on the existing overhead line. In this way, it is possible to increase the capacity of the overhead line. The analysis was performed with computer models using a modular multilevel converter (MMC) topology for the sp-RPC. Quantitative results for different consumption events of the locomotives and the analysis of the response to these variations are presented.This work has been supported by FCT—Fundação para a Ciência e Tecnologia, within the R&D Units Project Scope UIDB/00319/2020. Luis A. M. Barros is supported by the doctoral scholarship PD/BD/143006/2018, granted by the Portuguese FCT foundation

Canal Wall-Up Mastoidectomy. Predictive Factors of Recurrence

A mastoidectomia canal wall-up tem ganho um papel preponderante no tratamento do colesteatoma. No entanto, a significativa taxa de recidiva da doença mantém a escolha do tratamento controversa e difícil. No intuito de analisar a taxa de sucesso das timpanomastoidectomias efectuadas no Serviço de Otorrinolaringologia do Hospital São José por colesteatoma, avaliar eventuais factores preditivos de recidiva e verificar a validade da tomografia computadorizada de ouvidos no estudo desta patologia, procedeu-se a um estudo retrospectivo dos doentes submetidos a cirurgia entre 2005 e 2009. Identificaram-se factores associados frequentemente a recidiva, nomeadamente o envolvimento do seio timpânico, a erosão do scutum e o carácter invasivo da doença inicial. A tomografia computadorizada apresentou uma validade limitada no diagnóstico e estudo da doença, especialmente na avaliação pós-cirúrgica dos doentes. Na ausência de outros meios complementares de diagnóstico mais avançados, advoga-se a importância do second look como meio de controlo mais fiável da recidiva.info:eu-repo/semantics/publishedVersio

Corporate brand identity in higher education: a relational perspective

Identity is traditionally defined as an emission concept (Kapferer, 2008). Yet, some research points out that there are external factors that that can influence it (Kennedy, 1975; Markwick e Fill, 1997; Balmer e Gray, 2000). This subject is even more interesting if one considers corporate brands. According to Aaker (2004) the number, the power and the credibility of corporate associations are bigger in the case corporate brands. Literature recognizes the influence of relationships between companies in identity management (Hakansson and Snehota, 1989, 1995; Hakansson and Ford, 2002). Yet, given the increasingly important role of corporate brands, it is surprising that to date no attempt to evaluate that influence has been made in corporate brand´s identity management and reputation. Also Keller and Lehman (2006) highlight relationships and costumer experience as two areas requiring more investigation. The authors argue that corporate brand´s identity can be developed under a relational perspective using relationships with other recognised brands in order to generate positive reputations in stakeholders. Based in relationship and corporate brand identity management, a framework is developed to identify how corporate brands select, develop and invest in relationships with other brands. The context of the proposed relationship concept is the services area (Dwyer et al, 1987; Moorman et al, 1992; Rauyruen et al, 2005 and Hennig-Thurau and Klee, 1997). An empirical qualitative research is designed using two reputational technological higher education institutions (two corporate brands) acting in Portuguese public higher education market.info:eu-repo/semantics/publishedVersio

Attention deficit and hyperactivity disorder: case series of a secondary center

Introdução: A Perturbação de Hiperatividade e Défice de Atenção (PHDA) é o distúrbio neuro comportamental mais frequente em crianças em idade escolar e caracteriza-se pela dificuldade em controlar a atividade motora, a impulsividade e dificuldade em controlar a atenção. Objetivos: Caracterização das crianças com PHDA seguidas num hospital distrital. Material e Métodos: Estudo retrospetivo de crianças com o diagnóstico de PHDA. Analisadas as variáveis: idade, sexo, antecedentes familiares e pessoais, sintomatologia, co morbilidades, tratamento e resposta terapêutica. Resultados: Analisadas 45 crianças, 75,5 % do sexo masculino. À data do diagnóstico, 62,2 % das crianças apresentavam entre cinco e oito anos. Antecedentes familiares relacionados com PHDA foram identificados em 40% dos casos. Em 44,5%, a referenciação foi efetuada pela consulta de Pediatria Geral, sendo os motivos mais frequentes as dificuldades da aprendizagem (37,8%) e as alterações do comportamento (35,5%). A maioria das crianças (55,5%) apresentava associação de hiperatividade e défice de atenção. Realizada avaliação cognitiva em 90%, sendo que 39% apresentaram coeficiente intelectual inferior ao normal. As co morbilidades mais frequentes foram: alterações da linguagem, ansiedade, distúrbios de oposição/desafio. O tratamento com metilfenidato foi iniciado em 95%, com efeitos laterais em 16,3 %. Em 80% a resposta ao tratamento foi favorável. Conclusão: A PHDA apresenta elevada incidência em rapazes com idades entre os cinco e os oito anos, com predomínio do tipo misto. As dificuldades da aprendizagem e as alterações do comportamento são habitualmente o motivo de consulta. A intervenção com abordagem multidisciplinar e farmacológica demonstrou resultados favoráveis

Adjusting a simple crop model to predict maize and sorghum yield in the northeast Brazil.

A agricultura de sequeiro no Nordeste do Brasil tem sido frequentemente afetada pelas condições adversas de tempo e clima. Para antecipar a ocorrência de um colapso na produção agrícola o presente trabalho objetivou ajustar um modelo agrometeorológico para as culturas de milho e sorgo nos municípios de Serra Talhada e Araripina, ambos no estado de Pernambuco. Foi utilizado o modelo de balanço hídrico do CPTEC/INPE, incluindo informações para estimar colapso de safra, como proposto por Doorenbos e Kassan (1979). A análise apresentou um índice de concordância de 80%, classificado como muito bom, e um erro menor que 30%, classificado como aceitável, o que sugere que o modelo ajustado possa também produzir estimativas satisfatórias pra toda região Nordeste

Characterization of potential elastase inhibitor-peptides regulated by a molecular switch for wound dressings applications

Elastase plays an important role in wound healing process, degrading damaged tissue and allowing complete tissue recovery. The levels of human neutrophil elastase (HNE) are usually controlled by endogenous inhibitors. However, in the presence of high levels of elastase, like the ones present in chronic wounds, the inhibitors cannot overcome this overproduction and the enzyme starts to degrade the surrounding healthy tissue. In this work we report the development of a molecular switch to control the elastase activity in the exudate of non-healing chronic wounds. A peptide library was generated and screened in a microarray format for protein kinase-mediated phosphorylation. Two peptides were identified as casein kinase Iδ (CKI) substrates: KRCCPDTCGIKCL and its analogous peptide KRMMPDTMGIKML, with cysteine residues replaced by methionine residues. These peptides were studied in solution, both in the phosphorylated and non-phosphorylated forms as potential inhibitors for elastase. The obtained results show that the reversible process of phosphorylation/dephosphorylation results in differential inhibitory activity of the peptides. Thus the reversible process of phosphorylation/dephosphorylation can be used as a kind of molecular switch to control elastase activity. Degradation studies reveal that both the inhibitor-peptides and CKI are degraded by elastase. These results envisage the safe utilisation of these inhibitor-peptides together with CKI in the formulation of wound dressings.This work was supported by the European Project Lidwine - Multifunctional medical textiles for wound (e.g. Decubitus) prevention and improved wound healing. S.C.B. is supported by grants from the Lidwine Project and Foundation for Science and Technology (SFRH/BD/36522/2007). The results divulgation were supported by the COST Action 868. The authors are grateful to Professor Manuel dos Santos and Doutora Laura Carreto (Biology Department, Aveiro University) for use of the DNA microarray readers

Influence of secretory leukocyte protease inhibitor (SLPI) basedeptides on elastase activity and their incorporation into hyaluronic acid hydrogels for chronic wound terapy

Chronic nonhealing skin wounds, such as leg ulcers and pressure sores, represent a major clinical problem and a financial burden for the health care systems. Chronic wounds are characterized by prolonged inflammatory phase that results in high levels of elastase, reactive oxygen species (ROS), and diminished growth factor activity. Under normal physiological conditions, elastase is a powerful host defence and its activity is regulated by endogenous inhibitors. The unrestrained elastase activity in chronic wounds may be tuned by exogenous active materials that inhibit elastase. Secretory leucocyte protease inhibitor, SLPI, is a potent endogenous inhibitor of elastase. Peptide fragments, KRCCPDTCGIKCL (Pep4) and KRMMPDTMGIKML (Pep4M), selected from SLPI primary structure were studied as potential elastase inhibitors. Kinetic studies performed for human neutrophil elastase (HNE) and porcine pancreatic elastase (PPE) in presence of these peptides revealed that both behave as uncompetitive and noncompetitive inhibitors of HNE and PPE, respectively. The influence of ROS and albumin on Pep4 and Pep4M inhibitory activity toward elastase reveals that this mixture increases the inhibitory activity of both peptides. These peptides were incorporated in hyaluronic acid hydrogels to evaluate the possibility of being used as active compounds in a drug delivery system. Assessment of HNE and PPE activity in the presence of these hydrogels formulations revealed a considerable decrease in enzyme activity. Although, only moderated elastase inhibition was observed, these peptides represent potential candidates for chronic wound applications, as there is no need for complete elastase inhibition in the normal wound healing processContract grant sponsor: Portuguese Foundation for Science and TechnologyContract grant number: SFRH/BD/36522/2007Contract grant sponsors: FEDER (European Fund for Regional Development)-COMPETE-QREN-EUContract grant sponsors: COST Action 868The authors greatly acknowledge the European Project Lidwine-Multifunctional medical textiles for wound (e.g., Decubitus) prevention and improved wound healing. The financial support for the Research Centre was given by CQ/UM [PEst-C/QUI/UI0686/2011(FCOMP-01-0124-FEDER-022716]. The divulgation of these results, as an oral communication, was supported by the COST Action 868. The authors thank Professor Ana Campos (Chemistry Department, Minho University, Portugal) for supplying the hyaluronic acid used in this study

Tratamento da Tinea pedis com Miconazole em pacientes de ambulatório

Twenty six patients of Tinea pedis were treated with Miconazole 2-3 times a day. The drug was used as lotion, cream or powder in local applications. Lesions ameliorated or disappeared in 23 patients (88%), within an average period of 2-4 weeks