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Improving the efficiency of clinical trial designs by using historical control data or adding a treatment arm to an ongoing trialBennett, Maxine Sarah January 2018 (has links)
The most common type of confirmatory trial is a randomised trial comparing the experimental treatment of interest to a control treatment. Confirmatory trials are expensive and take a lot of time in the planning, set up and recruitment of patients. Efficient methodology in clinical trial design is critical to save both time and money and allow treatments to become available to patients quickly. Often there are data available on the control treatment from a previous trial. These historical data are often used to design new trials, forming the basis of sample size calculations, but are not used in the analysis of the new trial. Incorporating historical control data into the design and analysis could potentially lead to more efficient trials. When the historical and current control data agree, incorporating historical control data could reduce the number of control patients required in the current trial and therefore the duration of the trial, or increase the precision of parameter estimates. However, when the historical and current data are inconsistent, there is a potential for biased treatment effect estimates, inflated type I error and reduced power. We propose two novel weights to assess agreement between the current and historical control data: a probability weight based on tail area probabilities; and a weight based on the equivalence of the historical and current control data parameters. For binary outcome data, agreement is assessed using the posterior distributions of the response probability in the historical and current control data. For normally distributed outcome data, agreement is assessed using the marginal posterior distributions of the difference in means and the ratio of the variances of the current and historical control data. We consider an adaptive design with an interim analysis. At the interim, the agreement between the historical and current control data is assessed using the probability or equivalence probability weight approach. The allocation ratio is adapted to randomise fewer patients to control when there is agreement and revert back to a standard trial design when there is disagreement. The final analysis is Bayesian utilising the analysis approach of the power prior with a fixed weight. The operating characteristics of the proposed design are explored and we show how the equivalence bounds can be chosen at the design stage of the current study to control the maximum inflation in type I error. We then consider a design where a treatment arm is added to an ongoing clinical trial. For many disease areas, there are often treatments in different stages of the development process. We consider the design of a two-arm parallel group trial where it is planned to add a new treatment arm during the trial. This could potentially save money, patients, time and resources. The addition of a treatment arm creates a multiple comparison problem. Dunnett (1955) proposed a design that controls the family-wise error rate when comparing multiple experimental treatments to control and determined the optimal allocation ratio. We have calculated the correlation between test statistics for the method proposed by Dunnett when a treatment arm is added during the trial and only concurrent controls are used for each treatment comparison. We propose an adaptive design where the sample size of all treatment arms are increased to control the family-wise error rate. We explore adapting the allocation ratio once the new treatment arm is added to maximise the overall power of the trial.
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Determinação da coordenação de nado por meio da análise cinética e cinemática no estilo crawlMore, Felipe Collares January 2008 (has links)
A coordenação espaço-temporal dos movimentos dos braços de nadadores competitivos tem demonstrado ser um importante fator ligado a velocidade de nado e ao desempenho desses atletas. Os modelos básicos de coordenação comumente percebidos são: (1) captura - caracterizado pela existência de períodos sem propulsão entre a execução de cada braçada; (2) oposição - o movimento propulsivo de um braço inicia no exato instante em que o braço contra-lateral finaliza a fase propulsiva de seu movimento; (3) sobreposição - caracterizado por períodos com ação propulsiva simultânea dos dois braços. O objetivo deste estudo foi comparar os resultados da análise da simetria e da coordenação do nado crawl obtidos por meio dos métodos de cinemetria e dinamometria durante testes de nado livre e nado amarrado. Foram avaliados 13 nadadores federados voluntários do sexo masculino (idade: 19,4 ± 5,3 anos, estatura: 179,0 ± 5,2 cm, envergadura: 188,1 ± 6,0 cm, massa: 70,5 ± 8,7 kg, desempenho: 78,5 ± 4,2 % do recorde mundial de 50 m livres). Para obtenção das demais variáveis do estudo os nadadores foram submetidos à execução de dois protocolos distintos, realizados em piscina 25 m: (A) nado livre: 50 m nadados na máxima velocidade, com partida de dentro da piscina. Os atletas tiveram seu nado filmado (50 Hz) por duas câmeras colocadas dentro da água, uma em cada borda lateral da piscina, que foram deslocadas por operadores treinados a uma velocidade semelhante à velocidade de deslocamento do mesmo e (B) nado amarrado: nado estacionário em máxima intensidade com duração semelhante a do teste de nado livre. Os atletas tiveram a resultante das forças aplicadas por braçada medida por um transdutor de força fixado a borda da piscina onde era preso o cabo que estava ligado as suas cinturas e seus nados filmados (50 Hz) por duas câmeras posicionadas lateralmente a eles, sob a água. Um módulo eletrônico de sincronismo foi utilizado para disparar, simultaneamente, um sinal luminoso nas duas filmadoras e um pulso elétrico no sistema de aquisição dos dados oriundos do transdutor de força, possibilitando a posterior análise dos sinais oriundos de todos os aparatos utilizados para coleta dos dados. A partir da análise das imagens obtidas durante a execução de ambos os protocolos foram mensurados o índice de coordenação de nado (IdC), para ambos os braços (IdC1 e IdC2), em nado livre e nado amarrado e a freqüência média de braçadas (FB) na primeira e segunda metades do teste executado durante a aplicação de cada um dos protocolos. Os dados oriundos do transdutor de força permitiram a mensuração da diferença de tempo entre os picos de força aplicada por braçada (DFTA) para ambos os braços (DTFA1 e DTFA2). Os resultados mostraram um menor valor médio de IdC apresentado durante no nado livre (-3,59 ± 8,63 %) em relação ao nado amarrado (0,59 ± 7,92 %) indicando que, ao executarem o nado livre, os atletas adotam uma coordenação no modelo de captura e ao executarem o nado amarrado adotam uma coordenação em sobreposição, porém com valores que indicam uma possível coordenação no modelo de oposição. Diferentes valores de IdC1 (- 0,36 ± 7,44 %) e IdC2 (- 6,94 ± 8,52 %) foram encontrados em nado livre e nado amarrado (IdC1 = 3,76 ± 8,27 % e IdC2 = -2,54 ± 6,12 %). Os valores de FB apresentados pelos atletas na primeira metade de cada um dos testes foram significativamente mais elevados do que os valores de FB apresentados na segunda metade do respectivo teste (nado livre: [t(12) = 6,996; p < 0,001]; nado amarrado: [t(12) = 3,026; p = 0,011]). A comparação entre os valores de IdC1 e IdC2 adotados durante a execução de cada um dos protocolos mostrou que, durante o nado amarrado, todos os sujeitos apresentaram coordenação assimétrica enquanto durante o nado livre apenas três, dos 13 avaliados, foram considerados simétricos. A comparação entre os valores de DTFA1 e 2 demonstrou que apenas quatro sujeitos foram simétricos. A comparação dos valores da FB adotada pelos atletas mostrou que significativos maiores valores de FB foram apresentados durante o nado livre (FBiniL = 0,95 ± 0,08 ciclos.s-1, FBfinL = 0,88 ± 0,08 ciclos.s-1) em ralação ao nado amarrado (FBiniA = 0,79 ± 0,09 ciclos.s- 1, FBfinA = 0,76 ± 0,10 ciclos.s-1) na primeira e na segunda metades de ambos os testes. As comparações entre os valores de IdC apresentados durante nado livre e nado amarrado indicaram que apenas quatro, dos 13 sujeitos avaliados, mantiveram semelhantes valores para IdC1 e 2 em ambas as situações de nado. Apenas 3 dos sujeitos avaliados apresentaram valores significativos de correlação entre as variáveis IdC e DTFA. Com base nos achados deste estudo concluiu-se que: (1) durante os 50 m livres executados em máxima velocidade, os nadadores apresentaram, em média, uma coordenação no modelo de captura; (2) durante o nado amarrado os avaliados apresentaram uma coordenação em sobreposição, muito próxima da oposição; (3) o IdC e a FB medidas durante o nado livre foram diferentes das medidas durante o nado amarrado, indicando alterações da técnica; (4) a maioria dos nadadores avaliados manteve uma coordenação de nado considerada assimétrica em ambas as situações testadas e (5) a DTFA não se configurou como um parâmetro aceitável para determinação das simetrias e do modelo de coordenação de nado adotados durante o nado livre. Futuras investigações a cerca deste tema se fazem necessárias. / The spatial-temporal and coordinative structures of arms movements in competitive swimmers has been shown to be an important factor associated with swimming speed and performance of these athletes. The basic models of coordination commonly quoted are: (1) catch-up - describes a lag time between the propulsive forces of the two arms; (2) opposition - the propulsive phase of one arm begins when the other arm has just finished its propulsive phase; (3) superposition - describes an overlap of the propulsive phases of the two arms. The aim of this study was to compare the symmetry and the coordination analysis of front crawl swimming obtained through the kinematic and kinetic methods of free and tethered front crawl swimming. Thirteen male competitive swimmers volunteered this investigation (age: 19,4 ± 5,3 years, height: 179,0 ± 5,2 cm, arm span: 188,1 ± 6,0 cm, weight: 70,5 ± 8,7 kg, performance: 78,5 ± 4,2 % of world record at 50 m free style). Subjects underwent two different test protocols, both in a 25m indoor pool: (A) front crawl stroke: 50 m maximum swimming test, starting inside the pool. The athletes were recorded during all the test (50 Hz) by two underwater cameras, one on each lateral side of the pool, being transported by two experienced investigators at a speed equal to that of the swimmer, and (B) tethered swimming: tethered swimming at maximal intensity for the same period of the previous 50 m maximum test. Resultant force applied during each stroke was recorded by a force transductor attached on one side to the wall of the pool and on the other side to an inextensible cable that was attached to the swimmer's hips. The test was recorded during (50 Hz) by two underwater cameras, one on each lateral side of the swimmer. An electronic synchronization module was used to fire a LED light on both cameras and an electric pulse to the force acquisition recorder of the force transductor at the same time, this way allowing for correct interpretation of all data. From the images analysis of both protocols, we measured the index of coordination (IdC) for both arms (IdC1 and IdC2) during front crawl swimming and tethered swimming and the average stroke rate (SR) for the first and second half of both protocols. The data from the force transductor allowed for the determination of the time difference between the peak force applied per stroke (PFAS) for each arm (PFAS1 and PFAS2). The results show a smaller IdC mean for front-crawl stroke (-3,59 ± 8,63 %) compared to tethered swimming (0,59 ± 7,92 %), indicting that during front-crawl stroke the athletes prefer a catch-up coordination model, and during the tethered swimming condition they use a superposition coordination model, although some values suggest that some swimmers adopts opposition model during tethered swimming. Different values of IdC1 (-0,36 ± 7,44 %) and IdC2 (- 6,94 ± 8,52 %) were found for front-crawl and tethered swimming (IdC1 = 3,76 ± 8,27 % and IdC2 = -2,54 ± 6,12 %). Values of SR for the first half were higher than for the second half, irrespective of test condition (front-crawl: [t(12) = 6,996; p < 0,001]; tethered swimming: [t(12) = 3,026; p = 0,011]). Comparison between IdC1 and IdC2 used by athletes during the protocols revealed that during tethered swimming all subjects showed an asymmetric coordination, and during the front-crawl swimming only three subjects were considered symmetric. Comparison of SR values revealed significantly higher values for free swimming condition (SRiniF = 0,95 ± 0,08 stroke.s-1, SRfinF = 0,88 ± 0,08 stroke.s-1) compared to tethered swimming condition (SRiniT = 0,79 ± 0,09 stroke.s-1, SRfinT = 0,76 ± 0,10 stroke.s- 1), for both the first and second halves. The comparisons between IdC values of front-crawl and tethered swimming revealed that only four, of thirteen subjects evaluated, did have similar IdC1 and IdC2 values during both tests. Only three subjects showed a significant correlation between IdC and PFAS. Based on the findings of this study it was concluded that: (1) during 50 m front-crawl swimming maximum tests, the swimmers showed, on average, a catch-up coordination model; (2) during tethered swimming the subjects showed a superposition model of coordination, very close to the opposition one; (3) IdC and SR measured during front-crawl swimming were different from those measured during tethered swimming, indicating an alteration on the technique; (4) most of the swimmers tested showed an asymmetric coordination during both tests and (5) PFAS did not reveal as an acceptable parameter for determination of (as)symmetry and model of coordination during front-crawl swimming. Further investigations about this topic are required.
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The Effect of Rho Kinase Inhibitors on Alzheimer's DiseaseJanuary 2017 (has links)
abstract: Alzheimer’s disease (AD) is a progressive neurodegenerative disease that affects 5.4 million Americans. AD leads to memory loss, changes in behavior, and death. The key hallmarks of the disease are amyloid plaques and tau tangles, consisting of amyloid-β oligomers and hyperphosphorylated tau, respectively.
Rho-associated, coiled-coil-containing protein kinase (ROCK) is an enzyme that plays important roles in neuronal cells including mediating actin organization and dendritic spine morphogenesis. The ROCK inhibitor Fasudil has been shown to increase learning and working memory in aged rats, but another ROCK inhibitor, Y27632, was shown to impair learning and memory. I am interested in exploring how these, and other ROCK inhibitors, may be acting mechanistically to result in very different outcomes in treated animals.
Preliminary research on thirteen different ROCK inhibitors provides evidence that while Fasudil and a novel ROCK inhibitor, T343, decrease tau phosphorylation in vitro, Y27632 increases tau phosphorylation at a low dose and decreases at a high dose. Meanwhile, novel ROCK inhibitor T299 increases tau phosphorylation at a high dosage.
Further, an in vivo study using triple transgenic AD mice provides evidence that Fasudil improves reference memory and fear memory in both transgenic and wild-type mice, while Y27632 impairs reference memory in transgenic mice. Fasudil also decreases tau phosphorylation and Aβ in vivo, while Y27632 significantly increases the p-tau to total tau ratio. / Dissertation/Thesis / Doctoral Dissertation Neuroscience 2017
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Computational Modeling and Experimental Characterization of Pneumatically Driven Actuators for the Development of a Soft Robotic ArmJanuary 2018 (has links)
abstract: Soft Poly-Limb (SPL) is a pneumatically driven, wearable, soft continuum robotic arm designed to aid humans with medical conditions, such as cerebral palsy, paraplegia, cervical spondylotic myelopathy, perform activities of daily living. To support user's tasks, the SPL acts as an additional limb extending from the human body which can be controlled to perform safe and compliant mobile manipulation in three-dimensional space. The SPL is inspired by invertebrate limbs, such as the elephant trunk and the arms of the octopus. In this work, various geometrical and physical parameters of the SPL are identified, and behavior of the actuators that comprise it are studied by varying their parameters through novel quasi-static computational models. As a result, this study provides a set of engineering design rules to create soft actuators for continuum soft robotic arms by understanding how varying parameters affect the actuator's motion as a function of the input pressure. A prototype of the SPL is fabricated to analyze the accuracy of these computational models by performing linear expansion, bending and arbitrary pose tests. Furthermore, combinations of the parameters based on the application of the SPL are determined to affect the weight, payload capacity, and stiffness of the arm. Experimental results demonstrate the accuracy of the proposed computational models and help in understanding the behavior of soft compliant actuators. Finally, based on the set functional requirements for the assistance of impaired users, results show the effectiveness of the SPL in performing tasks for activities of daily living. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2018
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Variação da freqüência de braçada de um nadador entre a prova de 50 metros livre e sua parcial desta distância na prova de 100 livre / Arm stroke frequency variation of a swimmer between the 50 meters freestyle event and the first half of the 100 meters freestyle eventCamargo, Carlos Eduardo Ramos de 24 February 2005 (has links)
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Previous issue date: 2005-02-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This research s main goal was to analyze the arm stroke frequency variation of a swimmer, comparing his/her arm stroke frequency average variation in the 50m freestyle event and his/her arm stroke frequency average variation in the 100m freestyle event. This was based on the Atlanta XXVI Olympic Games Biomechanics report, presented by the Biomechanics and Sports Physiology Subcommission of the International Olympic Committee. This research analyses different items such as speed, arm stroke frequency, arm stroke length, and swimming efficiency of 15 swimmers, males and females, A and B finalists of the 50m freestyle event and of the 100m freestyle event in the Atlanta Olympic Games in 1996, comparing the information about their performances on these 2 events. Eight video cameras placed along the 50m swimming pool plus two control panels to analyze the received data were used in this research. The present research tried to find a supportable relation between the arm stroke frequency variation and the time variation pre-concepted in theory, which could come as one more item to help the athlete understand the concepts of a strategy variation. This is a descriptive interrelation analysis, comparing the relation between those two events. The information collected was analyzed as a whole and compared by the Pearson interrelation. The coefficient R2 = 0,0706 and R2 = 0,0511 indicates there s no relationship between the time and percentile time difference and the arm stroke frequency variation to be used as a guideline for other swimmers. / Este trabalho teve como objetivo geral analisar a variação da freqüência de braçada de um nadador, comparando sua freqüência média de braçadas na prova de 50 metros nado Livre e sua freqüência média na mesma distância de 50 metros durante a parcial da prova de 100 metros nado Livre. O trabalho foi realizado tendo como base o relatório de Biomecânica das competições de Natação dos XXVI Jogos Olímpicos de Atlanta, apresentado pela Subcomissão de Biomecânica e Fisiologia do Esporte do Comitê Olímpico Internacional. O presente estudo analisou os dados de velocidade, freqüência de braçada, comprimento de braçada e eficiência de nado de 15 nadadores de ambos os sexos, que foram finalistas A e B das provas de 50 metros nado Livre e 100 metros nado Livre, da Olimpíada de Atlanta em 1996, comparando as informações relativas aos desempenhos nestas duas provas. Foram utilizados neste estudo 8 câmaras de filmagem distribuídas em uma piscina de 50 metros de comprimento e dois painéis de controle que analisavam os dados recebidos. Esta pesquisa procurou verificar, se há uma relação válida entre a variação de freqüência de braçada com a variação de tempo preconizada em literatura, que pudesse servir como mais um instrumento que auxiliasse o atleta a compreender os conceitos de variação tática. Este estudo é caracterizado como um estudo descritivo de análise de correlação, pois se propõe a investigar as relações entre os eventos.Os dados obtidos foram tratados pela média e comparados através da correlação de Pearson. O R2 = 0,0706 e o R2 = 0,0511 indicam que não há correlação substancial entre a diferença e diferença percentual de tempo e variação percentual de freqüência de braçada que sirva de padrão para os demais nadadores.
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Coordenação da ação dos braços no nado crawl analisada em diferentes intensidades, nos exercícios contínuo e intermitente /Pelarigo, Jailton Gregório. January 2009 (has links)
Orientador: Camila Coelho Greco / Banca: Idico Luiz Pellegrinotti / Banca: Paulo Cezar da Silva Marinho / Resumo: O principal objetivo deste estudo foi analisar a resposta do lactato sanguíneo e a coordenação dos braços no nado crawl durante o exercício contínuo e intermitente realizado na máxima fase estável de lactato sanguíneo (MLSSC e MLSSI, respectivamente) e acima dessa intensidade (ACIMA MLSSC e ACIMA MLSSI, respectivamente). Participaram deste estudo nove nadadores de meio-fundo e fundo (idade = 18,56 ± 2,13 anos, massa corporal = 68,06 ± 6,48 Kg, estatura = 176,00 ± 6,36 cm e envergadura = 181,42 ± 9,68 cm) do sexo masculino, com pelo menos cinco anos de experiência na modalidade. Os indivíduos realizaram os seguintes testes em diferentes dias: 1) Testes máximos nas distâncias de 200 e 400 m (V200 e V400) para a determinação da velocidade crítica (VC); 2) 2 a 4 tentativas de até 30 min para a determinação da MLSSC, e; 3) De 2 a 4 tentativas de 12 repetições de 150 s com 30s de recuperação passiva para a determinação da MLSSI. A freqüência de braçada (FB) foi calculada por meio do tempo para realizar cinco braçadas. O comprimento de braçada (CB) foi calculado dividindo-se a velocidade pela FB. As fases da braçada e o índice de coordenação (IdC) foram determinados por meio de filmagens externa e subaquática. A velocidade correspondente à MLSSI (1,26 ± 0,06 m.s-1) foi significantemente maior do que a MLSSC (1,23 ± 0,05 m.s-1). No entanto, a concentração de lactato sanguíneo ([La]) (3,53 ± 1,34 mM e 3,22 ± 0,99 mM, respectivamente) foi similar. Houve aumento significante entre o 10o e o 30o min da FB nas condições MLSSC (30,66 ± 3,61 e 31,73 ± 3,58 ciclos.min-1), ACIMA MLSSC (30,98 ± 3,44 e 32,26 ± 3,56 ciclos.min-1), MLSSI (30,36 ± 2,36 e 31,25 ± 2,51 ciclos.min-1) e ACIMA MLSSI (32,66 ± 3,42 e 33,85 ± 2,84 ciclos.min-1). Para o CB, houve redução significante... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The main objective of this study was to analyze the blood lactate response and arm coordination in front crawl swimming crawl during the continuous and intermittent exercise at maximal lactate steady state (MLSSC and MLSSI, respectively) and above this intensity (ABOVE MLSSC and ABOVE MLSSI, respectively). Nine male swimmers (age = 18.56 ± 2.13 years, body mass = 68.06 ± 6.48 Kg, stature = 176.00 ± 6.36 cm and arm span = 181.42 ± 9.68 cm), specialized in middle- and long-distance events, with at least five years of experience participated of this study. The subjects performed the following tests on different days: 1) Maximal tests in the distances of 200 and 400 m (V200 and V400) to determine the critical speed (CS), 2) 2 to 4 repetitions with a maximal duration of 30 minutes to determine the continuous maximal steady state blood lactate (MLSSC), and 3) 2 to 4 trials of 12 repetitions of 150 s with 30 s of passive recovery between repetitions to determine the intermittent maximal lactate steady state (MLSSI). The stroke frequency (SF) was calculated using the time necessary to perform five strokes. The stroke length (SL) was calculated dividing the speed by the SF. The stroke phases and the stroke coordination index (SCI) were determined trough external and subaquatic recordings. The speed corresponding to MLSSI (1.26 ± 0.06 m.s-1) was significantly higher than MLSSC (1.23 ± 0.05 m.s-1). However, the blood lactate concentration ([La]) (3.53 ± 1.34 mM and 3.22 ± 0.99 mM, respectively) was similar between these conditions. There was a significant increase of SF between 10th and 30th min at the conditions MLSSC (30.66 ± 3.61 and 31.73 ± 3.58 ciclos.min-1), ABOVE MLSSC (30.98 ± 3.44 and 32.26 ± 3.56 cycles.min-1), MLSSI (30.36 ± 2.36 and 31.25 ± 2.51 cycles.min-1) and ABOVE MLSSI (32.66 ± 3.42 and 33.85 ± 2.84 cycles.min-1). For SL, there was a significant reduction... (Complete abstract click electronic access below) / Mestre
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Desenvolvimento de um sistema neuro-fuzzi para análise de sinais mioelétricos do segmento mão-braçoFavieiro, Gabriela Winkler January 2012 (has links)
Pesquisas científicas no campo da engenharia de reabilitação estão proporcionando cada vez mais mecanismos que visam ajudar pessoas portadoras de alguma deficiência física a executar tarefas simples do dia-a-dia. Com isso em mente, esse trabalho tem a finalidade de desenvolver um sistema que utiliza sinais musculares e redes neuro-fuzzy para a caracterização de determinados movimentos de um braço humano, com o objetivo de possibilitar futuramente a integração em sistemas de reabilitação. Ensaios preliminares demonstraram que para a caracterização de movimentos simples realizados por um braço humano, o uso exclusivo de técnicas simples de processamento de sinal é suficiente, como a utilização do valor rms. No entanto, para a caracterização de movimentos complexos é necessário um processamento mais robusto do sinal. Para isso foi desenvolvido um sistema experimental que adquire, através de um eletromiógrafo (EMG) de 8 canais, o sinal mioelétrico com eletrodos de superfície posicionados em lugares estratégicos do braço. O sinal é adquirido utilizando como estímulo um modelo virtual que demonstra ao usuário os movimentos do segmento mão-braço que devem ser executados de forma aleatória. Finalmente, com o uso de uma rede neuro-fuzzy, que possibilita a distinção tanto de movimentos simples como de movimentos compostos, se adaptando a diferentes usuários, os movimentos executados foram caracterizados em 12 movimentos distintos, previamente definidos, com uma taxa de acerto médio de 65%. / The scientific researches in the field of rehabilitation engineering are increasingly providing mechanisms to help people with a disability to perform simple tasks of day-to-day. With that in mind, this work aims to develop an experimental robotic prosthesis in order to implement, in the same, a control system that uses muscle signals and neuro-fuzzy networks for characterization of certain movements of a human arm, in order to enable further integration in rehabilitation systems. Preliminary tests showed that for the characterization of simple movements performed by a human arm, the exclusive use of simple techniques of signal processing is sufficient, as the use of the rms value. However, for the characterization of complex movements is required a more robust signal processing. For this was developed an experimental system that acquires through an electromyography (EMG) of 8 channels, the myoelectric signal with surface electrodes positioned in strategic places of the arm. The acquired signal uses, as a stimulus, a virtual model that demonstrates the hand-arm segment movements to be executed by the user at random. Finally, through a neuro-fuzzy network, which enables the distinction of both simple and compound movements, self-adapting to different users, the movements performed were characterized in 12 distinct movements, previously defined, with an average accuracy of 65%.
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Aquisição, processamento de sinais mioelétricos e máquina de vetores de suporte para caracterização de movimentos do segmento mão-braçoNilson, Clairê de Pauli January 2014 (has links)
As diversas áreas da Engenharia, em parceria com a ciência médica, têm contribuído de forma eficaz para o avanço do conhecimento e dos resultados em aplicações práticas na vida do deficiente físico. De forma geral, pesquisas com este foco têm permitido o desenvolvimento de dispositivos e recursos com o objetivo de oferecer novamente a mobilidade e a liberdade perdidas com a deficiência. Este trabalho tem a finalidade de desenvolver um sistema que utiliza Eletromiografia de Superfície e Máquina de Vetores de Suporte para a caracterização de determinados movimentos de um braço humano, possibilitando, futuramente, a integração em sistemas de reabilitação. Primeiramente os sinais mioelétricos são obtidos nos músculos do braço de voluntários através de eletrodos de superfície ligados a um eletromiógrafo. O sinal é adquirido, utilizando como padrão um modelo virtual que demonstra ao voluntário os movimentos do segmento mão-braço que devem ser imitados. Esses movimentos são executados e seus sinais mioelétricos adquiridos. Posteriormente, esses sinais são processados e características são extraídas. Em seguida, são alocadas algumas de suas características (RMS, média, variância, desvio padrão, skewness e kurtosis) na entrada da Máquina de Vetores de Suporte, que apresenta, como saída, o reconhecimento, ou não, do movimento previamente executado pelo voluntário. No final do processo, observou-se que aumentando o número de canais elevou-se a taxa de acerto dos movimentos e, com a retirada de determinada característica, houve decréscimo na taxa de acerto do sistema. Nestes casos, os 9 movimentos distintos atingiram uma taxa de acerto média de 83,2%, para dois canais, e 91,3%, para oito canais, e, em ambos sistemas de canais, com as seis características. / A wide range of engineering scopes, along with the knowledge from the medical science, has efficiently been contributing to further knowledge and results for practical applications in the life of the physically challenged. In general, such researches have allowed the development of devices and resources aimed at giving back the mobility and freedom lost with the deficiency. This paper intends to develop a system that uses Surface Electromyography and Support-Vector Machines (SVM) for the characterization of specific movements of a human arm enabling the future integration in rehabilitation systems. At first, myoelectric signals are obtained in the arm muscles of volunteers by means of surface electrodes attached to an Electromyography. The signal is acquired using a virtual model as pattern demonstrating to the volunteer the hand-arm movements which are to be replicated by the subject. As these movements are done, its respective myoelectric signals are acquired. Later on, these signals are processed and their characteristics extracted. Some of these features (such as RMS, standard deviation, variance, mean, kurtosis, skewness) will then be inserted in as input data in the Support- Vector Machine, which shows as an output a valid or null recognition of the movement earlier executed by the volunteer. At the end of the process, it was observed that increasing the number of channels increased by hit rate movements and, with the removal of certain characteristic, there was a decrease in the hit rate of the system. In these cases, nine distinct movements reached an average accuracy of 83.2% for two channels, and 91.3% for eight channels, and in both systems of channels, with six features.
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Energy consumption and performance of HPC architecture for Exascale / Consumo de energia e desempenho de arquiteturas PAD para ExascaleOliveira, Daniel Alfonso Gonçalves de January 2013 (has links)
Uma das principais preocupações para construir a próxima geração de sistemas PAD é o consumo de energia. Para quebrar a barreira de exascale a comunidade científica precisa investigar alternativas que possam lidar com o problema de consumo de energia. Sistemas PAD atuais não se preocupam com energia e já consomem GigaWatts. Requisitos de consumo de energia restringirão fortemente sistemas futuros. Nesse contexto processadores de alta potência abrem espaço para novas arquiteturas. Duas arquiteturas surgem no contexto de PAD. A primeira arquitetura são as unidades de processamento gráfico (GPU), GPUs possuem vários núcleos de processamento, suportando milhares de threads simultâneas, se adaptando bem a aplicações massivamente paralelas. Hoje alguns dos melhores sistemas PAD possuem GPUs que demonstram um alto desempenho por um baixo consumo de energia para várias aplicações paralelas. A segunda arquitetura são os processadores de baixo consumo, processadores ARM estão melhorando seu desempenho e mantendo o menor consumo de energia possível. Como exemplo desse ganho, projetos como Mont-Blanc apostam no uso de ARM para construir um sistema PAD energeticamente eficiente. Este trabalho visa verificar o potencial dessas arquiteturas emergentes. Avaliamos essas arquiteturas e comparamos com a arquitetura mais comum encontrada nos sistemas PAD atuais. O principal objetivo é analisar o consumo de energia e o desempenho dessas arquiteturas no contexto de sistemas PAD. Portanto, benchmarks heterogêneos foram executados em todas as arquiteturas. Os resultados mostram que a arquitetura de GPU foi a mais rápida e a melhor em termos de consumo de energia. GPU foi pelo menos 5 vezes mais rápida e consumiu 18 vezes menos energia considerando todos os benchmarks testados. Também observamos que processadores de alta potência foram mais rápidos e consumiram menos energia, para tarefas com uma carga de trabalho leve, do que comparado com processadores de baixo consumo. Entretanto, para tarefas com carga de trabalho leve processadores de baixo consumo apresentaram um consumo de energia melhor. Concluímos que sistemas heterogêneos combinando GPUs e processadores de baixo consumo podem ser uma solução interessante para alcançar um eficiência energética superior. Apesar de processadores de baixo consumo apresentarem um pior consumo de energia para cargas de trabalho pesadas. O consumo de energia extremamente baixo durante o processamento é inferior ao consumo ocioso das demais arquiteturas. Portanto, combinando processadores de baixo consumo para gerenciar GPUs pode resultar em uma eficiência energética superior a sistemas que combinam processadores de alta potência com GPUs. / One of the main concerns to build the new generation of High Performance Computing (HPC) systems is energy consumption. To break the exascale barrier, the scientific community needs to investigate alternatives that cope with energy consumption. Current HPC systems are power hungry and are already consuming Megawatts of energy. Future exascale systems will be strongly constrained by their energy consumption requirements. Therefore, general purpose high power processors could be replaced by new architectures in HPC design. Two architectures emerge in the HPC context. The first architecture uses Graphic Processing Units (GPU). GPUs have many processing cores, supporting simultaneous execution of thousands of threads, adapting well to massively parallel applications. Today, top ranked HPC systems feature many GPUs, which present high processing speed at low energy consumption budget with various parallel applications. The second architecture uses Low Power Processors, such as ARM processors. They are improving the performance, while still aiming to keep the power consumption as low as possible. As an example of this performance gain, projects like Mont-Blanc bet on ARM to build energy efficient HPC systems. This work aims to verify the potential of these emerging architectures. We evaluate these architectures and compare them to the current most common HPC architecture, high power processors such as Intel. The main goal is to analyze the energy consumption and performance of these architectures in the HPC context. Therefore, heterogeneous HPC benchmarks were executed in the architectures. The results show that the GPU architecture is the fastest and the best in terms of energy efficiency. GPUs were at least 5 times faster while consuming 18 times less energy for all tested benchmarks. We also observed that high power processors are faster than low power processors and consume less energy for heavy-weight workloads. However, for light-weight workloads, low power processors presented a better energy efficiency. We conclude that heterogeneous systems combining GPUs and low power processors can be an interesting solution to achieve greater energy efficiency, although low power processors presented a worse energy efficiency for HPC workloads. Their extremely low power consumption during the processing of an application is less than the idle power of the other architectures. Therefore, combining low power processors with GPUs could result in an overall energy efficiency greater than high power processors combined with GPUs.
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A musculoskeletal model of the human hand to improve human-device interactionJanuary 2014 (has links)
abstract: Multi-touch tablets and smart phones are now widely used in both workplace and consumer settings. Interacting with these devices requires hand and arm movements that are potentially complex and poorly understood. Experimental studies have revealed differences in performance that could potentially be associated with injury risk. However, underlying causes for performance differences are often difficult to identify. For example, many patterns of muscle activity can potentially result in similar behavioral output. Muscle activity is one factor contributing to forces in tissues that could contribute to injury. However, experimental measurements of muscle activity and force for humans are extremely challenging. Models of the musculoskeletal system can be used to make specific estimates of neuromuscular coordination and musculoskeletal forces. However, existing models cannot easily be used to describe complex, multi-finger gestures such as those used for multi-touch human computer interaction (HCI) tasks. We therefore seek to develop a dynamic musculoskeletal simulation capable of estimating internal musculoskeletal loading during multi-touch tasks involving multi digits of the hand, and use the simulation to better understand complex multi-touch and gestural movements, and potentially guide the design of technologies the reduce injury risk. To accomplish these, we focused on three specific tasks. First, we aimed at determining the optimal index finger muscle attachment points within the context of the established, validated OpenSim arm model using measured moment arm data taken from the literature. Second, we aimed at deriving moment arm values from experimentally-measured muscle attachments and using these values to determine muscle-tendon paths for both extrinsic and intrinsic muscles of middle, ring and little fingers. Finally, we aimed at exploring differences in hand muscle activation patterns during zooming and rotating tasks on the tablet computer in twelve subjects. Towards this end, our musculoskeletal hand model will help better address the neuromuscular coordination, safe gesture performance and internal loadings for multi-touch applications. / Dissertation/Thesis / Doctoral Dissertation Mechanical Engineering 2014
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