1000 resultados para motor asíncrono


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Segundo a Organização Mundial da Saúde, o consumo de álcool no mundo tornou-se um problema de saúde pública. Neste contexto, o Brasil figura na 63ª posição no mundo em consumo de álcool per capita para pessoas com 15 anos ou mais de idade. Além de seus efeitos sócio-econômicos, o etanol constitui um importante fator de risco na ocorrência de isquemias cerebrais. O consumo exacerbado desta droga colabora para o mau prognóstico, assim como para o possível tratamento de morbidades relacionadas ao acidente vascular cerebral. O objetivo deste estudo foi avaliar alterações neuromotoras após bloqueio da ativação micróglial com minociclina em ratos submetidos à isquemia focal no córtex motor, quando tratadas cronicamente com etanol da adolescência a fase adulta. Ratos receberam durante 55 dias, por gavagem, etanol (6,5 g/kg/dia, 22,5 p/v). No término destes 55 dias os animais foram submetidos à microinjeções do peptídeo vasoconstritor endotelina-1 (40 pmol), para indução de lesão isquêmica focal córtex motor. Os animais isquemiados foram tratados com minociclina recebendo duas doses diárias de 50 mg/kg nos primeiros dois dias, e mais cinco aplicações diárias únicas de 25 mg/kg, por via intraperitoneal, até o sétimo dia pós-indução isquêmica. Os testes comportamentais realizados foram campo aberto, plano inclinado e rota-rod. Os resultados demonstraram que os animais isquemiados e os expostos ao etanol e isquemiados apresentaram déficits motores em todos os testes comportamentais. Entretanto, o tratamento com minociclina foi capaz de reverte-los, possibilitando melhor desempenho em todos os testes aplicados. Os resultados sugerem que a minociclina foi capaz de reverter os danos motores ocasionados pelo acidente vascular cerebral, mesmo em presença do etanol. O exato mecanismo envolvido neste processo necessita ser investigado em pesquisas futuras.

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Este trabalho estuda a técnica de acionamento vetorial aplicado ao motor de indução trifásico (MIT), utilizando como estratégia de controle a combinação de controle fuzzy com controladores chaveados do tipo modo deslizante, em uma configuração aqui denominada de Controlador Fuzzy Modo Deslizante (FSMC – Do inglês: Fuzzy Sliding Mode Control). Um modelo dinâmico do MIT é desenvolvido em variáveis ‘d-q’ o que conduziu a um modelo eletromecânico em espaço de estados que exibe fortes não linearidades. A este modelo são aplicadas as condições de controle vetorial que permitem desacoplar o torque e o fluxo no MIT, de maneira que o seu comportamento dinâmico se assemelha àquele verificado em uma máquina de corrente contínua. Nesta condição, são implementados controladores do tipo proporcional e integral (PI) às malhas de controle de corrente e velocidade do motor, e são realizadas simulações computacionais para o rastreamento de velocidade e perturbação de carga, o que levam a resultados satisfatórios do ponto de vista dinâmico. Visando investigar o desempenho das estratégias não lineares nesta abordagem é apresentado o estudo da técnica de controle a estrutura chaveada do tipo modo deslizante. Um controlador modo deslizante convencional é implementado, onde se verifica que, a despeito do excelente desempenho dinâmico a ocorrência do fenômeno do “chettering” inviabiliza a aplicação desta estratégia em testes reais. Assim, é proposta a estratégia de controle FSMC, buscando associar o bom resultado dinâmico obtido com o controlador modo deslizante e a supressão do fenômeno do chettering, o que se atinge pela definição de uma camada de chaveamento do tipo Fuzzy. O controlador FSMC proposto é submetido aos mesmos testes computacionais que o controlador PI, conduzindo a resultados superiores a este último no transitório da resposta dinâmica, porém com a presença de erro em regime permanente. Para atacar este problema é implementada uma combinação Fuzzy das estratégias FSMC com a ação de controle PI, onde o primeiro busca atuar em regiões afastadas da superfície de chaveamento e o segundo busca introduzir o efeito da ação integral próximo à superfície. Os resultados obtidos mostram a viabilidade da estratégia em acionamento de velocidade variável que exigem elevado desempenho dinâmico.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Desenvolvimento Humano e Tecnologias - IBRC

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Sistema compacto de cogeração com motor de combustão interna compreendendo a interligação mecânica de um motor de combustão interna (M), operando com gasolina e ou gás, com um gerador de eletricidade (G), e um trocador de calor água/água (TC1), onde a troca de calor ocorre entre a água proveniente do conjunto de refrigeração do motor (M) e a água a ser aquecida proveniente da rede de abastecimento...

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Motor development is influenced by many factors such as practice and appropriate instruction, provided by teachers, even in preschool and elementary school. The goal of this paper was to discuss the misconception that maturation underlies children's motor skill development and to show that physical education, even in early years of our school system, is critical to promote proficiency and enrolment of children's in later motor activities. Motor skill development, as a curricular focus, has been marginalized in many of our physical education proposal and in doing so, we have not promote motor competence in our children who lack proficiency to engage and to participate in later motor activities such as sport-related or recreational.

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The severity of Parkinson's disease (PD) and PD's motor subtypes influence the components of physical capacity. The aim of this study was to investigate the impact of both PD severity and motor subtype in the performance of these components. Thirty-six PD patients were assigned into four groups: Tremor (TD) initial and TD mild, akinetic-rigid (AR) initial, and AR mild. Patients' strength, balance, coordination, mobility and aerobic capacity were evaluated and groups were compared using a two-way ANOVA (severity and subtype as factors). AR presents a poorer performance than TD in almost all tests. Also this performance was worsened with the advance of the disease in AR, contrary to TD. We conclude that AR and TD subgroups are different about their performance on physical capacity components, moreover, this performance worsens with the advance of the disease of the AR group, but not for TD.

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Recently was observed that pyrethroids decrease motor coordination and that calcium channels can be important targets for this effect. To contribute with this observation, this work studied the motor coordination and exploration (using hole-board apparatus), and locomotion (using open-field apparatus) of rats exposed to following treatments: permethrin (PM), PM plus calcium gluconate (CG) and PM plus amlodipine (AML). The results obtained show that CG or AML alone not changed the motor coordination while PM decreases it. CG kept the effect of permethrin; AML, however, decreased the values of permethrin to the control. Locomotor activity and exploration, which could confound results of motor coordination, were not modified by treatments. The concentration of PM in brain tissue was increased by the CG and AML. The neurosomatic index (weight brain/body weight) was increased by the PM and PM + CG. In conclusion, the combined results here obtained indicates that the calcium ion and the channels in which it is involved can be important targets for the toxic effect of pyrethroid insecticide permethrin on motor nerve activity of rats. (c) 2014 Elsevier B.V. All rights reserved.

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BACKGROUND AND OBJECTIVES: Gross motor (GM) deficits are often reported in children with prenatal alcohol exposure (PAE), but their prevalence and the domains affected are not clear. The objective of this review was to characterize GM impairment in children with a diagnosis of fetal alcohol spectrum disorder (FASD) or moderate to heavy maternal alcohol intake.METHODS: A systematic review with meta-analysis was conducted. Medline, Embase, Allied and Complementary Medicine Database, Cumulative Index to Nursing and Allied Health Literature, PsycINFO, PEDro, and Google Scholar databases were searched. Published observational studies including children aged 0 to <= 18 years with (1) an FASD diagnosis or moderate to heavy PAE, or a mother with confirmed alcohol dependency or binge drinking during pregnancy, and (2) GM outcomes obtained by using a standardized assessment tool. Data were extracted regarding participants, exposure, diagnosis, and outcomes by using a standardized protocol. Methodological quality was evaluated by using Strengthening the Reporting of Observational Studies in Epidemiology guidelines.RESULTS: The search recovered 2881 articles of which 14 met the systematic review inclusion criteria. The subjects' mean age ranged from 3 days to 13 years. Study limitations included failure to report cutoffs for impairment, nonstandardized reporting of PAE, and small sample sizes. The meta-analysis pooled results (n = 10) revealed a significant association between a diagnosis of FASD or moderate to heavy PAE and GM impairment (odds ratio: 2.9; 95% confidence interval: 2.1-4.0). GM deficits were found in balance, coordination, and ball skills. There was insufficient data to determine prevalence.CONCLUSIONS: The significant results suggest evaluation of GM proficiency should be a standard component of multidisciplinary FASD diagnostic services.

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Pós-graduação em Engenharia Mecânica - FEIS

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Children with cerebral palsy due to movement and posture disorders might have an injured nutritional state. This study's objective was to classify the body mass index of children with cerebral palsy and verify its relation with the injury level of gross motor function. Twenty children, male and female sex, with cerebral palsy with ages between 2 and 14 years participated in the study. They were chosen from a rehabilitation center with physiotherapy, occupational and speech therapy accompaniment. Children were classified according to the gross motor function classification scale. The anthropometric measures of each child weight, heel-knee length, estimated stature and body mass index were gauged. The body mass index was classified according to the Center for Disease Control and Prevention's body mass index percentile calculator for children and teenagers. The obtained data didn't show any relation between the gross motor function and body mass index. The reduced number of participants and the fact of all children be accompanied in dysphagia clinics and, when necessary, nutrition clinics, might have influenced these results.

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Thematic focus: The motor abnormalities may be part of so-called comorbidities that can coexist with autistic disorder. Objective: To characterize the motor profile of students with autistic disorder. Method: the study included six children with years and 9 months. After signing the consent form by parents or guardians, the students were submitted to the Motor Development Scale for assessment of fine motor, gross motor performance, balance, body scheme, spatial organization, temporal organization and laterality. Results: The results revealed a significant difference between the motor age and chronological age. According to the classification of the Scale of Motor Development, students in this study showed motor development lower than expected for age. Conclusion: The students with autistic disorder in this study presented a profile of Developmental Coordination Disorder in comorbidity, showing that participants of this research presented difficulties in activities that required skills such as handwriting. Thus, motor and psychomotor needs of these students were focused on educational and clinical environment to reduce the impact of behavioral and social manifestations.

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Background: To assess the motor development of infants exposed to maternal human immunodeficiency virus (HIV). Methods: Thirty infants were assessed in the period from November 2009 to March 2010 at the AIDS Reference and Training Centre, in São Paulo, Brazil. The assessment instrument used in the research was the Alberta Infant Motor Scale (AIMS). All 30 infants used the antiretroviral drug properly for 42 consecutive days, in accordance with the protocol of the World Health Organization. Results: Out of the total number of infants, 27 (90%) had proper motor performance and 3 (10%) presented motor delay, according to the AIMS. Discussion: This study demonstrated that only 10% of the assessed group had developmental delay and no relation with environmental variables was detected, such as maternal level of education, social and economic issues, maternal practices, attendance at the day care center, and drug use during pregnancy. It is important to emphasize the necessity of studies with a larger number of participants.