Modulador Hibrido de Potência Pulsada para Aplicações Biomédicas – O Uso de Semicondutores com Linhas de Transmissão

A Potência Pulsada pode definir-se como a ciência que estuda o armazenamento de energia elétrica durante um tempo relativamente longo seguida da sua libertação rápida numa carga, aumentando a potência instantânea. Esta técnica dos anos quarenta, usada inicialmente para fins militares, como tantas outras vezes, tem potencial para contribuir para o bem-estar e o desenvolvimento de todos. De facto, existe uma crescente variedade de aplicações ambientais, biomédicas e industriais que usam impulsos de alta tensão, de forma a melhorar a propriedade de um produto ou de uma técnica. Estes impulsos podem durar desde centenas de picossegundos até dezenas de segundos, com taxas de repetição até dezenas de milhares por segundo. Este trabalho tem como objetivo, além do estudo das técnicas usadas na construção de circuitos de geração de impulsos bipolares, o projeto e construção de uma fonte pulsada flexível (em frequência, amplitude e em largura dos impulsos), para geração de impulsos bipolares de alta tensão com 10kV de amplitude, com uma largura de impulsos de poucas dezenas de nanossegundos e taxa de repetição até 1kHz, para aplicações biomédicas. Impulsos de alta tensão com estas características são hoje em dia muito usados para produção de campos elétricos pulsados para aplicação em materiais biológicos, sendo uma ferramenta essencial no processamento de alimentos e tecidos biológicos. A inovação deste trabalho está associada com a técnica de produção dos impulsos de alta tensão bipolares (i.e. positivos e negativos) gerados através da utilização combinada de circuitos com semicondutores e linhas de transmissão, respetivamente, o gerador de Marx e o gerador Blumlein, baseado em cabos coaxiais e “strip lines”. Desta forma, tenta-se extrair o melhor destas duas tecnologias, respetivamente, a flexibilidade de operação bem como a capacidade de geração de impulsos de nanossegundos. Ao mesmo tempo, consegue-se atenuar as limitações inerentes a cada uma delas, respetivamente, a limitação de tensão, corrente e velocidade de comutação dos semicondutores, e a dimensão das linhas de transmissão. Neste trabalho são, também, usadas técnicas clássicas de associação de semicondutores ligadas com o uso de semicondutores de potência modernos.Uma componente importante deste trabalho é a modelação teórica dos circuitos apresentados, bem como a sua simulação em PSPICE e sua a validação experimental em cargas equivalentes aos sistemas biológicos

An approach for spasticity quantification based on the stretch reflex threshold

Spasticity is a common and complex motor disorder that affects more than 12 million persons in the world. There are several studies on spasticity quantification in the literature but there is still a need for measurement improvements. This paper presents the design of a mechatronic device for spasticity quantification, in joint of ankle, elbow and knees. This approach is based on the velocity dependent of the tonic stretch reflexes. The relevant variables, the measurement range and the adequate measurement systems are selected. The data acquisition system, board and software, are also defined and tested in laboratory. Next step consists of the system validation in clinical environment

Fine-tuning multilevel modeling of risk factors associated with nonsurgical periodontal treatment outcome

This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This retrospective study evaluated the influence of known risk factors on nonsurgical periodontal treatment (NSPT) response using a pocket depth fine-tuning multilevel linear model (MLM). Overall, 37 patients (24 males and 13 females) with moderate-to-severe chronic periodontitis underwent NSPT. Follow-up visits at 3, 6, and 12 months included measurements of several clinical periodontal parameters. Data were sourced from a previously reported database. In a total of 1416 initially affected sites (baseline PD ≥ 4 mm) on 536 teeth, probing depth (PD) and clinical attachment loss (CAL) reductions after NSPT were evaluated against known risk factors at 3 hierarchical levels (patient, tooth, and site). For each post-treatment follow-up, the variance component models fitted to evaluate the 3-level variance of PD and CAL decrease revealed that all levels contributed significantly to the overall variance (p < 0.001). Patients who underwent NSPT and were continually monitored had curative results. All 3 hierarchical levels included risk factors influencing the degree of PD and CAL reduction. Specifically, the type of tooth, surfaces involved, and tooth mobility site-level risk factors had the strongest impact on these reductions and were highly relevant for the success of NSPT.info:eu-repo/semantics/publishedVersio

Partial recording protocols performance on the assessment of Periodontitis severity and extent: bias magnitudes, sensibility, and specificity

This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Objectives: This study aimed to assess bias magnitudes, sensibility, and specificity of particular partial-mouth recording protocols (PRPs) to estimate periodontal clinical measurements and periodontal status. Methods: Estimates of mean clinical attachment loss (MCAL) and mean probing depth (MPD) were calculated for 15 different PRPs and were compared to full-mouth recording protocol (FRP) data from 402 Portuguese. Biases, relative biases and intra-class correlations for all PRPs were evaluated. Bland–Altman plots and Receiver Operating Characteristic / Area Under the Curve (ROC/AUC) analysis were used to assess the sensitivity and specificity for each PRP periodontal diagnosis. Results: Regarding MPD, Half RD6 UR/LL and RD6 UL/LR had the lowest bias observed with 0.00 mm (-0.22% and 0.22%, respectively) and all full-mouth PRPs significantly produce an underestimation. Concerning MCAL, the Half MB-B-DL UR/LR had the lowest bias observed with 0.01 mm (0.16%). Excluding CPITN, Full-Mouth PRPs outperforms in average Half Mouth PRPs correlations. The Half RD6 UR/LL had the highest AUC (0.96) with 95.5 and 97.1% of sensitivity and specificity, respectively. Conclusions: Three half-mouth PRPs (Half MB-B-DL UR/LR, Half RD6 UR/LL and Half RD6 UL/ LR) protocols can be used to estimate periodontal clinical measurements with limited bias, and high sensitivity, specificity, and concordance. All full-mouth PRPs failed to estimate pocket depth means, and for clinical attachment loss, they present less ability then half-mouth partial protocols, despite presenting high sensitivity levels.info:eu-repo/semantics/publishedVersio

Serum C-Reactive Protein and Periodontitis: A Systematic Review and Meta-Analysis

Periodontitis has been associated with low-grade inflammation as assessed by C-reactive protein (CRP) levels and its treatment can decrease CRP serum levels. The aim of this systematic review was to critically appraise the evidence comparing CRP serum levels (standard and high-sensitivity [hs]) of otherwise healthy patients suffering from periodontitis when compared to controls. The impact of intensive and non-intensive nonsurgical periodontal treatment (NSPT) on hs-CRP was also investigated. Four electronic databases (Pubmed, The Cochrane Central Register of Controlled Trials [CENTRAL], EMBASE and Web of Science) were searched up to February 2021 and the review was completed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (PROSPERO No. CRD42020167454). Observational and intervention studies that: 1) evaluated CRP and hs-CRP serum levels in patients with and without periodontitis, and; 2) hs- CRP levels after NSPT were included. Following risk of bias appraisal, both qualitative and quantitative analyses were performed. Pooled estimates were rendered through ratio of means (RoM) random-effects meta-analyses. After screening 485 studies, 77 case-control studies and 67 intervention trials were included. Chronic and aggressive periodontitis diagnoses were consistently associated with higher levels of CRP and hs-CRP (p<0.001). Patients with aggressive periodontitis exhibited on average more than 50% higher levels of CRP (RoM [95% confidence interval [CI]]: 1.56 [1.15; 2.12], p=0.0039) than patients with chronic periodontitis. Intensive NSPT induced an immediate increase of hs-CRP followed by a progressive decrease whilst non-intensive NSPT consistently decreased hs-CRP after treatment up to 180 days (p<0.001). These findings provide robust evidence that periodontitis is associated with systemic inflammation as measured by serum CRP levels. Periodontitis treatment induces a short-term acute inflammatory increase when performed in an intensive session, whilst a progressive reduction up to 6 months was demonstrated when performed in multiple visits

Bolton ratios in Portuguese subjects among different malocclusion groups

Several methods have been described to estimate inter-arch tooth size relationship, such as Bolton?s ratios. The aims of this study were to verify the validity of Bolton indexes in a sample of untreated Portuguese subjects based on Angle classification and to evaluate the gender difference. 168 pre-treatment dental casts of orthodontics Portuguese subjects (59 males and 109 females) with different occlusions were used, which were selected randomly from 541 consecutively treated orthodontic patients. The mesiodistal widths from first molar to first molar were measured on each pre-treatment cast to the nearest 0.01 mm using digital caliper, and Bolton?s anterior and overall ratios were calculated. Descriptive statistics as mean, standard deviation and range were calculated. Moreover, the results were compared to Bolton?s ratios and differences based on gender and occlusion groups were evaluated by statistical inference methods. The results reveal that the mean values, standard deviation and range were larger than Bolton?s in normal occlusion group (78.3±3.5% in anterior ratio and 92.1±2.2% in overall ratio) and there were no differences between genders (p >0.05). Class I (anterior and overall ratios, p=0.001 and p<0.001, respectively), Class II/2 (anterior ratio, p=0.032) and Class III (overall ratio, p=0.041) were significantly different from Bolton?s reference data. The results showed no differences between gender and no difference between normal occlusion and malocclusion groups. Moreover, in normal occlusion group, the anterior and overall tooth size ratios was equivalent to the original Bolton?s ratios, although the mean and standard deviation were large

Abordagem sistemática para o controlo seguro de sistemas aeroespaciais

A verificação formal do comportamento de sistemas tempo-real é uma tarefa complexa, por várias razões. Há múltiplos trabalhos desenvolvidos na área de verificação formal, por model-checking de sistemas tempo-real, sendo que diversos softwares foram desenvolvidos para o efeito. Um dos problemas mais complexos para serem resolvidos na análise de controladores tempo-real é a conversão das linguagens de programação dos controladores nas linguagens formais, por exemplo autómatos finitos temporizados para depois poderem ser verificados formalmente através dos model-checkers existentes. Se a metodologia de elaboração dos programas for bem desenvolvida e conhecida, essa tarefa pode ser muito facilitada. Por outro lado, grande parte dos sistemas tempo-real (principalmente os sistemas embebidos que pretendemos estudar) é programado em linguagem C. Neste artigo pretende-se estabelecer uma metodologia de criação de programas em código C, a partir do formalismo de especificação SFC, tendo em conta a verificação formal de propriedades comportamentais desejadas para o sistema, utilizando a técnica Model- Checking e o model-checker UPPAAL. Estes estudos preliminares são efectuados no contexto de colaboração entre Investigadores dos centros de investigação CT2M, ALGORITMI e CCTC da Universidade do Minho (Portugal) e do Departamento de Engenharia Mecânica do Instituto Tecnológico de Aeronáutica (Brasil).Formal verification of real-time systems behavior of is a complex task, for several reasons. There are multiple works developed in the domain of formal verification of real-time system behavior by model-checking, and various software tools were developed for this purpose. One of the most complexes problems to be solved in the analysis of real-time controllers is the conversion of programming languages controllers in formal languages, for example finite timed automata to be used as inputs of the existing model-checkers. If the methodology of the programming is well developed and known, this task can be greatly facilitated. Moreover, most real-time systems (especially embedded systems that we intend to study) are programmed in C language This article seeks to establish the methodology of creating programs in C code, from SFC specification formalism, taking into account the formal verification of behavior al properties desired for the system, using the Model-Checking technique and the modelchecker UPPAAL. A case study is presented to illustrate the methodology presented. These preliminary studies are presented on the context of a research collaboration project being developed by researchers of CT2M, ALGORITMI and CCTC research centers of University of Minho (Portugal) and the Mechanical Engineering Department of Technological Institute of Aeronautics (Brazil)

Formação de Leitores / Arte, Literatura, Educação e Desporto

N/Ainfo:eu-repo/semantics/publishedVersio

Probable Person-to-Person Transmission of Legionnaires’ Disease

Correspondence to the Editor.Legionnaires’ disease is an often severe form of pneumonia that is typically acquired by susceptible persons (e.g., elderly persons and smokers) through inhalation of aerosols that contain legionella species.1-4 A cluster of cases of this disease occurred in Vila Franca de Xira, Portugal, in 2014

Supply chain strategies in the context of an e-commerce chain (e-chain)

This paper purpose to explore the relationships between supply chain strategies and product performance in retail e-commerce. In this case, we concern that in current, in order to bear up under competition, organizations have to manage their supply chains so that they meet the needs of their final customers. With this concept in mind, the research presented in this study focuses on establishing the right strategy for supply chains according to their product segment. Thus, after a Literature Review, the paper explain a methodology based in different authors studies. Finally the article focuses on a pratical case in e-commerce retail that describes its application in this field. The research shows that it is possible to use a methodology for classifying supply chains using chain strategies and product features. The use of the right strategy for supply chains will improve the competitive advantage of businesses. One limitation is that the methodology study focuses on only two e-commerce segment; future studies may go further in refining the proposed framework for other segments. The aim of this research is to offer businesses a model for evaluating supply chains, allowing them to improve the performance of their products and services by using the right strategy for supply chains. The classification proposal of this paper presents an original model for classification of supply chains based on different studies on the theme