RESUMO: O Modelo de Cadeia Estocástica de Markov e o Processo de Hierarquia Analítica (AHP) foram utilizados como ferramentas de apoio à tomada de decisão para a melhor escolha de plantio na cidade de Caxias do Sul, Brasil. As informações de temperatura e precipitação foram coletadas de 1997 a 2017 no Banco de Dados Meteorológicos para Ensino e Pesquisa do Instituto Nacional de Meteorologia do Brasil. O modelo estocástico foi aplicado para obtenção da probabilidade de transição entre faixas de variação para temperatura e precipitação. Na segunda fase do estudo, um modelo algébrico foi desenvolvido, possibilitando vincular a probabilidade da matriz de transição de cadeias de Markov na matriz de julgamento do AHP. Na terceira fase, o AHP foi aplicado como ferramenta de apoio à decisão do cultivo mais benéfico para a cidade estudada, considerando os critérios avaliados: temperatura, precipitação e pH do solo. As alternativas escolhidas para fazer o ranking foram: cenoura, tomate, maçã e uva, escolhidas por possuírem a maior quantidade de plantio na cidade de Caxias do Sul. O ranking do resultado de força de benefício da aplicação do modelo para a primavera foi: cenoura (0,297), maçã (0,259), uva (0,228) e tomate (0,215); para o verão: uva (0,271), tomate (0,261), maçã (0,238) e cenoura (0,230); para o outono: cenoura (0,316), uva (0,243), tomate (0,228) e maçã (0,213); para o inverno: cenoura (0,327), tomate (0,235), maçã (0,222) e uva (0,216). Assim, concluiu-se que o agricultor terá mais chances de sucesso se optar por plantar cenoura durante a primavera, outono e inverno, e uva durante o verão.

ABSTRACT: The Markov stochastic chain model and the analytical hierarchy process (AHP) were used as tools to support decision-making for the best crop-planting choice in the city of Caxias do Sul, Brazil. Temperature and precipitation information were collected from the Meteorological Database for Teaching and Research of the National Institute of Meteorology of Brazil for the period 1997-2017. The stochastic model was applied to obtain the probability of transition between a range of variations for temperature and precipitation. In the second phase of the study, an algebraic model was developed, making it possible to link the probability of the Markov chain transition matrix to the AHP judgment matrix. In the third phase, the AHP was applied as a tool to determine the most beneficial crop that could be planted for the studied city, considering the evaluated criteria: temperature, precipitation, and soil pH. The alternatives for crop planting were carrots, tomatoes, apples, and grapes. These were chosen because they are the most-planted crops in the city of Caxias do Sul. The ranking of the benefit-force results of applying the model for spring was carrots (0.297), apples (0.259), grapes (0.228), and tomatoes (0.215); for summer: grapes (0.261), tomatoes (0.261), apples (0.238), and carrots (0.230); for autumn: carrots (0.316), grapes (0.243), tomatoes (0.228), and apples (0.213); and for winter: carrots (0.327), tomatoes (0.235), apples (0.222), and grapes (0.216). Thus, it was concluded that farmers would have a better chance of success if they planted carrots during the spring, autumn, and winter, and grapes during the summer.

Resumo O objetivo desse trabalho é fazer a análise climática, utilizando modelos de redes neurais artificiais, como auxílio no processo de tomada de decisão no plantio de alguns tipos de produtos agrícolas. Um banco de dados com os principais elementos do clima foi construído a partir do site do INMET (Instituto Nacional de Meteorologia) e desses elementos foram identificados, em um nível de significância de 0,05, os que mais influenciavam no valor da temperatura média. Modelos de Redes Neurais Artificiais foram criados e avaliados por meio do MAD (Mean Absolute Deviation), MSE (Mean Squared Error), RMSE (Root-Mean Squared Error) e MAPE (Mean Absolute Percentage Error), e finalmente, associou-se o valor da previsão com o melhor cultivo agrícola a ser aplicado. Foram elaboradas 12 redes neurais, oito são referentes à previsão da temperatura e as outras quatro à previsão da precipitação. As redes que demostraram melhor desempenho são as que consideram todos os elementos do clima. É possível concluir que as redes neurais demostraram um desempenho adequado na previsão de séries temporais caóticas, e consequentemente, tiveram o seu resultado associado com o melhor cultivo a ser aplicado para cada previsão. Um cronograma é apresentado no final, sugerindo a melhor época para plantar cada uma das culturas estudadas. Observa-se que para os próximos cinco anos, o cultivo mais adequado à faixa prevista é o da cenoura.

Abstract The aim of this study is to conduct climate forecasting with models of artificial neural networks as a tool in the decision-making process for the planting of some types of agricultural products. A database with the main climate elements was built from the National Institute of Meteorology (INMET), and those elements that influenced the average temperature value the most were found at a significance level of 0.05. Models of Artificial Neural Networks were developed and tested using Mean Absolute Deviation (MAD), Mean Squared Error (MSE), Root-Mean Squared Error (RMSE), and Mean Absolute Percentage Error (MAPE), before being linked to the best agricultural cultivation forecast value. Twelve neural networks were elaborated, eight of them are related to the temperature forecast and the other four are related to the precipitation forecast. The networks that showed the best performance are those that consider all the elements of climate. It is possible to conclude that the artificial neural networks showed an adequate performance in predicting chaotic time series, and that their results were therefore linked to the optimum cultivation to use for each forecast. A schedule is supplied at the end, indicating the ideal time to plant each of the crops evaluated. Carrot is found to be the best suited crop for the forecasted range over the next five years.

RESUMO RACIONAL: O transplante de fígado é uma terapia complexa e valiosa. Entretanto, complicações que prejudicam a qualidade de vida pós-operatória, como a hérnia incisional, devem ser mais bem elucidadas, analisando os fatores de risco e medidas profiláticas. OBJETIVOS: Definir a taxa de hérnia incisional em pacientes submetidos a transplante de fígado em uma população do sul do Brasil, avaliar os fatores de risco relacionados, a fim de estabelecer futuramente medidas de otimização prévia e cuidados profiláticos específicos. MÉTODOS: Foram analisados, retrospectivamente, pacientes submetidos a transplante de fígado adultos, de janeiro de 2004 a novembro de 2020, avaliando suas características demográficas, resultados cirúrgicos e fatores predisponentes. RESULTADOS: Dentre os 261 pacientes transplantados hepáticos incluídos, a hérnia incisional foi diagnosticada em 71 (27,2%). Vinte e oito do total de 71 pacientes com hérnia incisional (39,4%) desenvolveram hérnia incisional durante o primeiro ano pós-transplante. A maioria era do sexo masculino [n=52, (73,2%)]; 52/71 (73,2%) apresentavam cirrose secundária ao vírus da hepatite C; 33/72 (46,5%) foram portadores de carcinoma hepatocelular. Sexo masculino (p=0,044), diabetes mellitus (p=0,008) e rejeição celular aguda (p<0,001) foram fatores de risco estatisticamente significantes para hérnia incisional. Vinte e oito pacientes (39,4%) foram submetidos à hernioplastia incisional com tela, com taxa de recidiva de 17,8%. CONCLUSÕES: Hérnia incisional após transplante de fígado é um problema relativamente comum, associado ao sexo masculino, diabetes e também a rejeição celular aguda. Este é um problema que não deve ser banalizado, já que pode levar à redução da qualidade de vida, comprometer os resultados tardios do transplante de fígado e pode levar a encarceramento ou estrangulamento.

ABSTRACT BACKGROUND: Liver transplantation is a complex and valuable therapy. However, complications that burden postoperative quality of life, such as incisional hernia, are to be better elucidated, such as risk factors and prophylactic measures. AIM: This study aimed to define the rate of incisional hernia in patients who underwent liver transplantation in a population in southern Brazil and to assess the related risk factors in order to establish measures for prior optimization and specific prophylactic care in the future. METHODS: Patients undergoing adult Liver transplantation from January 2004 to November 2020 were retrospectively analyzed, assessing demographic features, surgical outcomes, and predisposing factors. RESULTS: Among 261 liver transplantation patients included, incisional hernia was diagnosed in 71 (27.2%). Of the 71 incisional hernia patients, 28 (39.4%) developed IH during the first post-transplant. Majority of the patients were male (52/71, 73.2%); of the 71 patients, 52 had hepatitis C virus (HCV) and 33 (46.5%) had hepatocellular carcinoma (HCC). Male gender (p=0.044), diabetes mellitus (p=0.008), and acute cellular rejection (p<0.001) were risk factors for IH. In all, 28 (39.4%) patients were submitted for hernia repair with mesh, with a recurrence rate of 17.8%. CONCLUSION: Incisional hernia after liver transplantation is a relatively common problem associated with male gender, diabetes, and acute cellular rejection. This is a problem that should not be trivialized in view of the complexity of liver transplantation, as it can lead to a reduction in quality of life as well as jeopardize late liver transplantation results and lead to incarceration and strangulation.

Resumo Objetivos: Este estudo com análise de elementos finitos (EF) 3D não lineares avaliou a influência do número de implantes, da inclinação de implantes distais e do uso de pilares angulados sobre as tensões em osso peri-implantar cortical (CB), parafuso do pilar protético (AB) e parafuso protético (PS) em próteses totais fixas implantossuportadas (IFCD). Métodos: Modelos de EF-3D não lineares de IFCD mandibulares foram criados com cinco, quatro e três implantes paralelos entre si (5R, 4R, 3R) e com o implante distal inclinado (5I, 4I, 3I). Adicionalmente, no modelo 5I foi testado o uso de pilares angulados, compensando a angulação do implante. Uma força axial de 100 N foi aplicada sobre o primeiro molar (extremo livre) para avaliar as tensões em pontos selecionados (CB, AS, PS). Resultados: O implante adjacente à carga mostrou maiores tensões em CB, AS e PS. O modelo com três implantes apresentou maiores tensões que com quatro ou cinco. Quanto ao AS, o pico tensional aumentou 40% de cinco para quatro implantes e 100% de cinco para três implantes. A inclinação distal do implante posterior aumentou as tensões em CB. Quanto ao PS, o pico tensional aumentou 150% do modelo 5R para o 5I e 100% do modelo 4R para o 4I. O pilar angulado diminuiu as tensões em CB e AS, mas aumentou em PS. Conclusões: Os resultados sugerem que as tensões em CB, AS e PS aumentam quando há inclinação do implante distal e diminuição do número de implantes. O uso de pilares angulados diminui as tensões em CB e AS, mas aumentou as tensões em PS.

Abstract Objectives: This nonlinear three-dimensional finite element analysis (FEA) study evaluated the effect of the number of implants, distal implant inclination, and use of angled abutments on stress magnitude and distribution in cortical bone (CB), abutment screw (AS), and prosthetic screw (PS) of implant-supported fixed complete dentures. Methods: Nonlinear 3D FEA models of mandibular fixed complete dentures were created with five, four, or three parallel straight implants (5S, 4S, 3S) and with tilted distal implants (5T, 4T, 3T). In addition, the 5T model was tested using angled abutments over the tilted distal implants to re-align the implant inclination. A 100-N axial load was applied over the first molar region (cantilever) to analyze the von Mises stresses in selected points (CB, AS, and PS). Results: The implant adjacent to the load showed the highest stresses in CB, AS, and PS. The model with three implants showed higher stresses than the ones with four and five implants. Peak stresses in the AS increased 40% from five to four implants and 100% from five to three implants. Tilting the distal implants increased stresses in CB. Peak stress in the PS increased 150% from 5S to 5T models and 100% from 4S to 4T models. Angled abutments generated lower stresses on CB and AS but higher stresses on PS. Conclusions: The results suggest that stresses in the cortical bone, abutment screw, and prosthetic screw increase when tilting the posterior implants and reducing the number of implants. The use of angled abutments decreased stresses at the bone-implant interface and in abutment screws but increased stresses on prosthetic screws.

A gestão da ocupação docente em instituições de ensino superior é um problema que afeta universidades públicas e, principalmente, as privadas. Uma distribuição justa de tarefas aos docentes repercute diretamente na qualidade do ensino, na produção de conhecimento, na sustentabilidade institucional e, principalmente, na saúde dos docentes. Neste trabalho é proposto um método para avaliação da composição da carga de trabalho com base em uma ferramenta chamada Processo Analítico Hierárquico, visando a equidade em termos de carga de trabalho (o que não significa o mesmo que equidade das cargas-horárias nas diferentes atividades docentes). Como principal contribuição, é proposta uma métrica, chamada Coeficiente de Carga de Trabalho, que pode ser facilmente adaptada a realidade de cada instituição. Apesar das bases matemáticas, quando implementada computacionalmente, a utilização dessa métrica passa a ser simples e acessível a gestores de qualquer formação.

The management of teaching occupation in higher education institutions is a problem that affects public and, mainly, private universities. A fair distribution of tasks to teachers directly affects the quality of teaching, the production of knowledge, institutional sustainability and, mainly, the health of teachers. This work proposes a method for evaluating the composition of the workload based on a tool called the Hierarchical Analytic Process, aiming at equity in terms of workload (which does not mean the same as equity in the amount of hours dedicated to different activities). As the main contribution, a metric, called Workload Coefficient, is proposed, which can be easily adapted to the reality of each institution. Despite the mathematical bases, when implemented computationally, the use of this metric becomes simple and accessible to managers in any area of knowledge.

Abstract This study aims at presenting a new analysis method for adhesive (interfacial) and cohesive (bulk) failures in aluminum (Al) and high-density polyethylene (HDPE) sandwich composites. The samples were submitted to tensile strength tests, according to ASTM C297 so as to obtain the pull-off stresses. The delaminated aluminum surfaces were analyzed with SEM/EDS (Scanning Electronic Microscopy with Energy Dispersive Scanning). The images were calculated using a genetic algorithm (GA), where the areas with cohesive and adhesive failures were identified by the presence or absence of organic compounds. The proposed method also uses the data from the pull-off tests to determine the stress values of adhesion and cohesion separately. Applying the new method, the mean stress of cohesion was 4.17 MPa, and for adhesion it was 0.57 MPa. Thus, it was possible to distinguish and calculate the failure stresses applied to metal/polymer composites.

Resumo Objetivo O Teste Shuttle Modificado é um teste clínico de campo que evita o efeito-teto e não existem relatos de avaliação multidimensional com relação à atividade física em pacientes com asma. Assim, o objetivo era avaliar a capacidade funcional, a atividade física na vida cotidiana, a força muscular e os níveis de citocina em crianças e adolescentes com asma, a fim de correlacionar essas variáveis. Método Este estudo transversal incluiu voluntários entre seis e 18 anos, os quais foram divididos em dois grupos: o grupo com asma (n = 43), que recebeu tratamento regular, e o grupo de controle (n = 24). A capacidade funcional foi avaliada pela distância percorrida durante o Teste Shuttle Modificado, ao passo que a atividade física na vida cotidiana foi avaliada utilizando um acelerômetro pelo número de passos. A força muscular do quadríceps femoral foi avaliada por uma célula de carga. Resultados A distância percorrida foi menor no grupo com asma (790 m [222 m]) em comparação com o grupo de controle (950 m [240 m]; p = 0,007), contudo o número de passos foi semelhante nos dois grupos (grupo com asma: 7.743 [3.075]; grupo de controle: 7.181 [3.040]; p = 0,41) e ambos os grupos foram classificados como sedentários. Não houve diferença na avaliação da força muscular. O fator de necrose tumoral-α apresentou divergências, porém os níveis de interleucina foram semelhantes entre os grupos. A força muscular do quadríceps foi correlacionada com a distância percorrida (r: 0,62; p < 0,001) e o fator de necrose tumoral-α, ao número de passos dados (r = −0,54, p = 0,005). Conclusão Crianças e adolescentes que recebem tratamento regular de asma apresentaram redução da capacidade funcional e comportamento sedentário. Quanto menor a força muscular do quadríceps, menor a distância percorrida; quanto maiores os níveis de fator de necrose tumoral-α, menores seus níveis diários de atividade física.

Abstract Objective The modified shuttle test is a field test that avoids the ceiling effect, and there are no reports of a multidimensional assessment concerning physical activity in asthmatic patients. Thus, the aim was to evaluate functional capacity by MST, additionally to perform a multidimensional assessment as physical activity in daily life, muscle strength, and cytokine levels in children and adolescents with asthma, and to correlate these variables. Method This cross-sectional study included volunteers aged between 6 and 18 years who were divided into two groups: asthma group (n = 43) that received regular treatment and control group (n = 24). Functional capacity was evaluated by distance walked during the MST; physical activity in daily life was evaluated using an accelerometer by the number of steps. Quadriceps femoris strength was evaluated by load cell. Results Distance walked was lower for the asthma group (790 m [222 m]) when compared with the control group (950 m [240 m]; p = 0.007); however, the number of steps was similar between the two groups (asthma group: 7743 [3075]; control group: 7181 [3040]; p = 0.41), and both groups were classified as sedentary behavior. There was no difference in muscle strength. Tumor necrosis factor-α differed, but interleukin levels were similar between groups. Quadriceps strength was correlated to distance walked (r = 0.62; p < 0.001) and tumor necrosis factor-α to the number of steps taken (r = −0.54, p = 0.005). Conclusion Children and adolescents undergoing regular asthma treatment showed reduced functional capacity and sedentary behavior. The lower the quadriceps strength, the shorter the distance walked; the higher the tumor necrosis factor-α levels, the lower their daily physical activity levels.

ABSTRACT Background: Papiliotrema laurentii is one of several non-neoformans cryptococci that have rarely been associated with human infection, since it was previously considered saprophyte and thought to be non-pathogenic to humans. Nevertheless, increasing number of reports of human infection have emerged in recent years, mostly in oncologic patients. Aim: To report a case of a female patient with pyloric obstructive cancer with a catheter-related Papiliotrema laurentii blood stream infection and systematically review the available evidence on P. laurentii infection in humans. Methods: Retrieval of studies was based on Medical Subject Headings and Health Sciences Descriptors, which were combined using Boolean operators. Searches were run on the electronic databases Scopus, Web of Science, MEDLINE (PubMed), BIREME (Biblioteca Regional de Medicina), LILACS (Latin American and Caribbean Health Sciences Literature), Cochrane Library for Systematic Reviews and Opengray.eu. There was no language or date of publication restrictions. The reference lists of the studies retrieved were searched manually. Results: The search strategy retrieved 1703 references. In the final analysis, 31 references were included, with the description of 35 cases. Every patient but one had a previous co-morbidity - 48.4 % of patients had a neoplasm. Amphotericin B was the most used treatment and only a single case of resistance to it was reported. Most patients were cured of the infection. Conclusion: P. laurentii infection in humans is usually associated to neoplasia and multiple co-morbidities, and amphotericin B seems to be a reliable agent for treatment.

ABSTRACT In this paper we analyzed the probabilities of transitions of state between Ibovespa and Dow Jones indexes using High-order Multivariate Markov Chain. While the stock market may be profitable, the existence of risks can lead to large losses. A mathematical model capable of considering different sources can aid in decision making. This model can work with stochastic data, causing different databases to be transformed into transitional matrices between states. For this, a set of a daily variation data were used between January 2008 and March 2018. Through this application, it was possible to show an interaction between the indexes and that the highest frequency of events was of the variation of -0.49 to 0.5% in Dow Jones to -0.49 to 0.5% in Ibovespa, with 428 cases, and the probability of this situation occurring again, of Dow Jones at time t to Ibovespa at time t+2, is 27.21%. Empirical results suggest that this application can help investors make decisions based on transition probabilities.

RESUMO Há aproximadamente 15 anos, a citricultura brasileira vem sofrendo consideráveis perdas em produtividade e qualidade dos frutos devido ao ataque do fitopatógeno Alternaria alternata f.sp. citri, causador da Mancha Marrom da Alternaria (MMA), o controle da doença ainda é feito com o uso massivo de agroquímicos, chegando a vinte aplicações por período reprodutivo. O presente trabalho avaliou a eficiência no controle do MMA in vitro e in vivo utilizando fermentados botânicos de Trifolium pratense e Daucus pusillus como meio de controle da doença. Nos fermentados autoclavados a 40%, a inibição foi de 100%, o extrato bruto de ambas plantas não apresentou poder inibitório. In vivo, os melhores resultados foram com o teste preventivo de Trifolium pratense não autoclavado, que inibiu em 93% o aparecimento da doença.

ABSTRACT For approximately 15 years, Brazilian citriculture has suffered considerable losses in productivity and fruit quality as a result of the attack by the phytopathogen Alternaria alternata f.sp. citri, which causes Alternaria brown spot (ABS). The disease control is still performed with the massive use of agrochemicals, reaching up to twenty applications per reproductive period. The present study evaluated the efficiency of in vitro and in vivo ABS control by using fermented extracts of Trifolium pratense and Daucus pusillus as a means to control the disease. Fermented extracts autoclaved at 40% showed 100% inhibition, while the crude extract of both plants had no inhibitory effect. In vivo, the best results were found with the preventive test of non-autoclaved Trifolium pratense, which inhibited the onset of the disease by 93%.

In the present study, a methodology is appliedfor system reliability based design optimization (RBDO) to thin copper films that are deposited on flat surfaces of polypropylene polymer. The input data of the design of such polymer-metal joint was determined by the necessary normal stress to detach the copper film from the substrate of polypropylene by different forces and interface areas, obtained from uniaxial tensile test. The RBDO methodology was implemented in order to find the smallest bonding area required to assure different reliability levels, minimizing the detaching probability and cost (lower amount of the metallic film). The reliability level is treated as input data and considered as a constraint in the optimization problem. The used optimization methodology is the Genetic Algorithm (GA). This choice is due to the fact that GA presents good behavior when dealing with functions that may exhibit nonlinear behavior. The results shows that the applied methodology is efficient and it is concluded that high reliability requirements might impose larger areas. In the case of 98% of the reliability cases in not detaching the thin film, the resulted bonded area is 3.18 greater than the initial value without safety requirements.

En el presente estudio se aplica una metodología para la optimización de los sistemas basados en la confiabilidad (RBDO) a las películas delgadas de cobre que se depositan en una superficie plana de polímero de polipropileno. Se determinaron los datos de entrada, como el tamaño de la junta por la tensión normal necesaria para separar la película de cobre del sustrato de polipropileno por diferentes fuerzas y zonas de interfaz, que se obtiene a partir de un ensayo de tracción uniaxial. La metodología RBDO se implementó con el fin de encontrar la zona de unión más pequeño requerido para asegurar diferentes niveles de confiabilidad, reduciendo al mínimo la probabilidad de desprendimiento y el costo (menos cantidad de película metálica). El nivel de confiabilidad es tratado como datos de entrada y considerado como una restricción en el problema de optimización. La metodología de la optimización es el algoritmo genético (GA). La elección de esta metodología se debe al buen comportamiento en las funciones que pueden exhibir un comportamiento no lineal. Los resultados muestran que la metodología aplicada es eficiente y se concluye que los requisitos de alta confiabilidad pueden imponer zonas de colaje considerablemente más grandes. En el 98% de los casos de confiabilidad en la no separación de la película fina, resultó en una zona de unión que es 3,18 mayor que el valor inicial sin requisitos de seguridad.

Dental treatment and surgery is a well-established method of correcting dentofacial deformities, and such treatment has an impact on the quality of life of individuals. The objective of this study was to evaluate the effect of orthognathic surgery on the quality of life of patients receiving treatment at the Universidade Federal do Paraná – UFPR. Clinical data were evaluated for the control group, and a quality-of-life evaluation questionnaire was completed [Oral Health Impact Profile (OHIP-14)]. For the case group, the same data were gathered along with information regarding their dentofacial deformity. The OHIP-14 questionnaire was also completed at three distinct stages of the experiment. The median age in the control group was 23.5 years. In the case group, the predominant gender was female, and the mean age of patients was 29.4 years. There was a statistically significant association between gender and OHIP-14 (p< 0.001). No such association was observed between age and OHIP-14 scores (p= 0.616). In the control group the OHIP-14 median score was 11.5. In the case group, the average OHIP-14 score at was 18 at T0, 21 at T1, and 8 at T2. The results demonstrated a statistically significant association between the three time stages at which OHIP-14 was analyzed (p< 0.001). There was a smaller reduction in the negative impact for transversal deformities of the jaw when compared with other deformities. Orthognathic surgery led to a reduction in the negative effects on the quality of life of patients.

A presente pesquisa avalia o comportamento mecânico da haste femoral não-cimentada Logical através de elementos finitos. Foram analisadas diferentes condições de contorno encontradas na prática ortopédica: a) apenas o colo exposto; b) com as aletas anti-rotatórias parcialmente expostas; e c) com as aletas totalmente expostas. Variações antropométricas foram consideradas pelas diferentes angulações de colo propostas e através de diferentes cargas aplicadas. A haste apresentou um bom coeficiente de segurança. Embora pequenos deslocamentos sejam observados em todas as condições, existe um maior deslocamento com o aumento da exposição das aletas da prótese. Mesmo para a condição extrema com as aletas totalmente expostas, a prótese suporta as cargas de trabalho e ainda há um bom fator de segurança. Tensões e deslocamentos se modificam consideravelmente com as diferentes angulações propostas para o colo, sugerindo que as variações antropométricas devam ser consideradas no futuro para otimizar o desempenho da prótese.

This paper evaluates the mechanical behavior of an uncemented hip stem using finite element analysis. The analysis is focused on the stem-bone interaction which is assessed by simulation of distinct conditions encountered daily on orthopedic practice of hip implants. Logical uncemented femoral stem was used in this work. Three distinct conditions have been modeled: a) exposed neck with fully embedded fins, b) partially exposed anti-rotational fins and c) fully exposed fins, representing real femoral hip conditions. Anthropometric variations and different angulations for the stem neck were investigated for typical body weight of populations submitted to implants. The ratio of mobilized stress to yield stress is shown to be lower than 55% indicating a safety factor against stem failure. Although small displacements are observed in all conditions, the displacement increases with the increase of both the length of exposed fins and the magnitude of applied forces. Even for the extreme condition of fully exposed fins, the prostheses will support the working loads, and the risk of bone fracture still has a safety factor. Stresses and displacements change considerably with neck angulations suggesting that anthropometric variations should be considered in the future to optimize prostheses performance. Numerical analysis of the used uncemented femoral stem demonstrated that small stresses and strains are generated under working load conditions indicating that a proper factor of safety is obtained for the static conditions tested in the present study.

The focus of this paper is to establish a characterisation method for seven polyamide (PA) grades to determine the major material to manufacture an automotive worm gear. The composite properties were measured according to the worm gear loadings: tensile strength, Young's modulus, abrasion and impact resistance. They were also correlated to the PA moisture absorption and its glass fibre (GF) reinforcement. The data from mechanical tests were applied in the finite element analysis (FEA) using the von Mises stress criterion. Before the rig tests of the PA worm gears, the injection process was evaluated, through the capillary rheometry. A higher difficulty to process PA 6/6 30% GF was found, due to its lower apparent viscosity. In the end, the influence of moisture absorption was as decisive to the gear's material selection as the GF to the pinion. Thus, the PAs with the best performance were: PA 6 with 30% GF (gear) and with PA 60% GF (pinion).

OBJETIVO: Avaliar, através da análise por elementos finitos com modelo tridimensional, o efeito da reabsorção óssea na distribuição de tensões em prótese tipo overdenture, em situações de perda óssea ao redor dos implantes e reabsorção do rebordo posterior. METODOLOGIA: Foram construídos modelos tridimensionais de uma mandíbula e de intermediários protéticos, prótese total, placa resiliente e implante. Os modelos geométricos dos implantes e intermediários protéticos foram montados na região dos caninos, constituindo o modelo 1. Para a construção dos modelos experimentais, o contorno do modelo geométrico da mandíbula foi alterado para simular a perda óssea nos implantes (modelo 2) e a reabsorção do rebordo posterior associada à perda óssea marginal nos implantes (modelo 3). Para gerar a malha de elementos finitos os materiais foram considerados homogêneos, isotrópicos e linearmente elásticos. Uma carga de 100 N foi aplicada indiretamente, sobre uma simulação de bolo alimentar, na região de primeiro molar inferior direito em cada um dos três modelos. Foram analisadas as distribuições de tensão de von Mises em pontos pré-determinados. RESULTADOS: A reabsorção óssea do rebordo posterior associada à perda óssea do osso periimplantar promoveu maior concentração de tensões nos implantes, nos componentes protéticos e no tecido ósseo marginal. Houve maior concentração de tensões no osso periimplantar e nos implantes no mesmo lado de aplicação da carga. CONCLUSÃO: Os resultados sugerem que a perda óssea periimplantar aumenta a concentração de tensões nos implantes, pilares e osso marginal independentemente da reabsorção óssea na crista distal.

PURPOSE: This 3D-finite elements method study evaluated the effect of bone resorption on the stress distribution in overdentures with bone loss surrounding implants and resorption of the distal ridge. METHODS: Tridimensional models were built from the images of a computerized tomography of a mandible and 3D laser digitalization of implants, abutments, mucosa, and complete denture. The geometric models of implants and abutments were mounted at the canine region to build reference model 1 - absence of bone resorption. To build the test models the mandible geometric solid was modified to simulate 2-mm vertical bone loss surrounding the implants (model 2) and resorption of the distal ridge (model 3). Finite elements models were generated, and a 100 N static load was applied at the first molar region of each model to compare the von Mises stress distributions in selected points. RESULTS: Von Mises stresses increased on the bone surrounding implants and on the prosthetic components in the model with 2-mm vertical bone loss. The combination of 2-mm vertical bone loss and resorption of the distal ridge did not increase the stresses compared with the model with only bone loss surrounding implants. The highest stress concentration at marginal bone and implants occurred on the same side of the vertical load application for all models. CONCLUSION: The results suggest that the bone loss surrounding implants increases stress concentration in dental implants, abutments, and marginal bone independently from the bone resorption of the distal ridge.