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<p> In this study a theoretical model is proposed for the buckling of a vein subjected to torsion, internal pressure, and axial tension using a formation of elasticity theory for shells. The vein is assumed to be an anisotropic hyperelastic cylindrical shell which obeys the Fung constitutive model. </p><p> The approach uses finite deformation theory for thick-walled blood vessels to characterize the vessel dilation in the pre-buckling state. The pre-buckling state is identified by its midpoint and then perturbed by a displacement vector field dependent on the circumferential and axial directions to define the buckled state. The buckling equations of static equilibrium are derived using the nominal stress measure and traction boundary conditions are applied. A side result is shown proving the existence of a moment traction although typically taken to be zero for torsional problems. Perturbational displacements raised to the power of two or greater are assumed negligible thereby linearizing the coupled partial differential equations of equilibrium. The coupled equations are solved by supposing first-order and single Fourier term trigonometric forms for the displacement field components. </p><p> The model and the assumptions used are validated by experimental data for five human great saphenous vein (GSV) samples taken from a previous study. The theoretical model is unstable but using an eigenvalue compatibility condition as a selection method yields strong quantitative results for three out of five GSVs in the entire tested pressure range (6-100 mmHg). The other two sampless showed excessive stiffening upon loading and may indicate limitations of the model although quantitative predictions were still moderately accurate. The strongest results are in the 6-20 mmHg pressure range where all vessels matched well with predicted values. In general the model showed increased error as pressure increased hinting that effects of vessel stiffening are poorly predicted. The eigenmodes predicted were consistently inaccurate indicating the assumptions used in this solution method are inadequate to characterize the buckling modes of a nonlinear material. It may suggest that nonlinear buckling conformation is determined by nonlinear perturbation terms.</p><p>

This study examined the relationship between hip strength and hip, pelvis, and trunk kinematics in healthy runners. Whole body kinematic data were collected while subjects ran in the laboratory. Isometric hip abduction, flexion, external rotation, and internal rotation torques were measured bilaterally using a dynamometer. Subjects were divided into strong and weak groups for each muscle strength parameter. Differences in hip, pelvis, and trunk motion were then examined using independent sample t-tests. Pearson correlation coefficients were used to assess these relationships for all subjects. Most notably, runners with weak abductors displayed greater hip adduction and pelvic rotation compared to the strong abductor group, while runners with weak external rotators displayed greater trunk rotation compared to the strong external rotator group. Moderate, negative correlations were observed for the above relationships. While data from this study help clarify the relationship between hip strength and running kinematics, no causal conclusions can be made.

Anterior cruciate ligaments (ACL) are among the most common reported ligament injuries in athletes. This injury has been linked to changes in joint stability, neuromuscular activity and contact mechanics. In vitro simulators have proven to provide valuable insights on the potential effects of muscle activity on joint stability. The University of Ottawa Knee Simulate (UOKS) is a mechanical load driven quasi-static apparatus that provides the framework to explore pressure changes in knee compartments and the resultant kinematics in response to six individual muscle loads applied around an unconstrained joint. The main objective of the present work was to develop an automated loading mechanism for the UOKS. Furthermore, the secondary objective was to evaluate the accuracy, precision, reliability and validity of the newly automated system. Six transmission units were designed, built and tested as part of the development of the automated mechanism adapted to the UOKS. Load cells were used to obtain real time feedback of the load created by the transmission units. A software controller was programmed using LABVIEW to control these transmissions as a graphic user interface (GUI). Each transmission was tested independently and compared to an external master load cell. Furthermore, four cadaveric knee joints were mounted and suspended inside the UOKS for experimentation. Seven different loading conditions were tested with the ACL intact and after the ACL was severed. Pressure and kinematic data were recorded to correlate the changes in these variables due to changes in loading conditions simulated by the UOKS. The controlled loading experiment of the automated mechanism showed the accuracy of the controller to be within +/-1N, and multiple trials showed the system’s capability to produce loads. Additionally, the results showed the controller to have an ICC of 0.99 between the load produced and the target load. The comparison between feedback load cells and the master load cell displayed unique results regarding each transmission and the loads being applied. The results showed overestimations and underestimations with unique load difference trends for each transmission. Nevertheless, the relative difference measured by the master load cell was below 10% in all the transmissions. This study demonstrated that the controller was accurate and reliable when producing loads. On the other hand, the results of the integration analysis showed the presence of losses in the system when transmitting the loads from the actuators to the front of the UOKS. These losses were different for each transmission, likely due to the independence of each pulley system. Nevertheless, the automated loading mechanism proved to be a valid replacement for the original static loading mechanism previously used by the UOKS and is capable of reliably simulating six independent loading conditions.

Made available in DSpace on 2014-06-11T19:22:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-12-08Bitstream added on 2014-06-13T19:49:09Z : No. of bitstreams: 1 thomaz_t_me_rcla.pdf: 901888 bytes, checksum: 96e22240a3b1710d26349f35b8551430 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este estudo tem como objetivo definir as orientações dos segmentos envolvidos na ação de chutar, comparar dois tipos de chute - potência e precisão através das variáveis angulares do segmento pelve e das articulações do quadril, do joelho e do tornozelo. A orientação dos segmentos pelve, coxa, perna e pé foi feita através da utilização da convenção dos ângulos de Euler (CHAO, 1980; ZATSIORSKY, 1998), através de rotinas desenvolvidas no software Matlab®. Para obtenção das imagens foram utilizadas 4 câmeras digitais JVC GR-9800u, fixas em tripés, o tratamento das imagens foi realizado no software Dvideow (BARROS et al, 1999; Figueroa et al, 2003). Nos resultados encontrados verificou-se que o segmento pelve apresenta diferença entre os dois tipos de chute no movimento de rotação à direita /esquerda e também no movimento de inclinação lateral direita/esquerda. Durante a realização do chute de precisão a pelve apresenta-se em rotação para a direita de maneira mais acentuada quando comparada ao chute de potência. Diferenças também foram encontradas no movimento de inclinação lateral, a pelve apresenta-se mais inclinada à direita na execução do chute de precisão em relação ao chute de potência. A articulação do quadril apresenta diferenças no movimento de abdução/adução, pois durante o chute de precisão foi verificado o movimento de abdução mais acentuado, e no chute de potência o movimento identificado foi o de adução. O joelho apresenta uma flexão mais acentuada no chute de potência. E a articulação do tornozelo apresenta diferença nos movimentos de dorsiflexão/flexão plantar, durante o chute de precisão o segmento pé está em dorsiflexão devido a vi intenção de acertar a bola com a região medial do pé. Conclui-se que os dois chutes diferem-se nos movimento de rotação à direita/esquerda e inclinação lateral... / The goal of the proposed study is to define the positions and orientations of the segments involved in the action of kicking by females, and to compare the two specific types of kicks: potency and precision using the angular variables . These orientations will be defined by the convention of Euler s angles (CHAO, 1980; ZATSIORSKY, 1998) and through routines developed using the software Matlab®. For obtaining images, four digital cameras (JVC GR-9800u) will be used, fixed on tripods. The processing of the images will be performed using the software Dvideow (BARROS et al, 1999; Figueroa et al, 2003). The results show that the pelvis presents differences in the left/right tilt and in the left/right rotation. The hip shows differences in the abduction/adduction movements, the knee has a flexion movement in the potent kick bigger than in the precision kick, and at the ankle join hasn't been found differences in the pronation/evertion movement.

Orientador: José Elias Tomazini / Banca: José Geraldo Trani Brandão / Banca: Renato Rocha / Resumo: O sedentarismo é crescente na população mundial e com ele cresce a incidência das doenças crônicas degenerativas. Em contrapartida têm-se os exercícios físicos que são recomendados para a prevenção, tratamento e reabilitação dessas doenças. A musculação é um desses exercícios e sua prática cresce cada dia mais. Dentre todos os exercícios que podem ser realizados na musculação, está o agachamento, que é muito utilizado para fortalecer a musculatura dos membros inferiores, porém a execução errônea do mesmo pode acarretar lesões irreversíveis ao praticante. Atualmente são utilizados conceitos biomecânicos para estudar e compreender os esforços mecânicos acerca do agachamento visando a proteção do sistema musculoesquelético. A presente dissertação tem como objetivo aplicar o método de Kane a um modelo de corpo humano buscando analisar os torques articulares e as forças nos tendões musculares dos membros inferiores durante o exercício de agachamento. A instrumentação contou com modelo biomecânico bidimensional (2D) desenvolvido a partir do método de Kane, que consiste na análise do sistema multicorpo através de conceitos de velocidades, forças ativas e inércia generalizadas. Os resultados de pico de torque encontrados foram de 36,9 N.m no tornozelo, 51 N.m no joelho e 119,1 N.m no quadril. Os resultados de picos de força nos tendões musculares foram de 1290 N no gastrocnêmio, 723 N no quadríceps e 730 N nos isquiotibiais. O método se mostrou eficaz ao calcular os esforços mecânicos nas articulações de membros inferiores, porém são necessários mais estudos englobando um maior número de variáveis para completa elucidação do assunto. / Abstract: Physical inactivity is increasing in the world population and with it the incidence of chronic degenerative diseases grows. In contrast, there are the exercises that are recommended for the prevention, treatment and rehabilitation of these diseases. Strength training is one of these exercises and their practice grows every day. Among all the exercises can be performed, is the squat, which is widely used to strengthen the muscles of the lower limbs, however the erroneous execution can result in irreversible damage. Biomechanical concepts are currently used to study and understand the mechanical stress on the squat in order to protect the musculoskeletal system. This study aims to apply the Kane's method to a human body model seeking to analyze the joint torques and muscle forces in the tendons of the lower limbs during the squat. The instrumentation featured biomechanical model with two-dimensional (2D) developed from Kane's method, which consists of analysis of multibody systems using concepts of generalized speed, generalized active forces and generalized inertia. The results of peak torque were 36.9 N.m in the ankle, 51 N.m in the knee and 119.1 N.m in the hip. The results of peak strength in the muscle tendons were 1290 N in the gastrocnemius, 723 N in the quadriceps to 730 N in the hamstrings. The method was reliable to calculate the mechanical stress on the joints of the lower limbs, but more studies are needed covering a larger number of variables to complete elucidation of this subject. / Mestre

Resumo: Com aumento de longevidade, a preocupação está voltada à acessibilidade que possibilita autonomia e mobilidade humana. O movimento do corpo humano depende da dinâmica anatômica e fisiológica entre músculos e articulações para processar o movimento que é causado por forças centrípetas. A locomoção humana é produzida pela transferência do corpo no espaço, que depende da marcha, evento de alta complexidade para análise sobre reabilitação e biomecânica. Nessa conjuntura, o escopo deste estudo foi avaliar a atividade muscular e correlacionar as variáveis (Razão, Co-contração e Pressão Plantar no calcâneo) para análise do esforço biomecânico do tornozelo durante a marcha em aclive, declive e plano. Sob protocolo n.138/2010 de aprovação do projeto por Comitê de Ética em Pesquisa, a coleta de dados foi aplicada em amostra de 11 sujeitos do gênero feminino, com idade entre vinte e cinquenta anos, saudáveis e com marcha independente. Para o trajeto se utilizou uma rampa com inclinação de 20º, cujo início foi demarcado com o toque sobre a marca que continha o pushbutton para registro de sinais eletromiográficos e força plantar em sincronismo. As participantes utilizaram um par de sandálias sensorizadas desenvolvido com quatro células de carga para mensurar as pressões plantares por meio de extensão que ligava cada célula ao sistema de aquisição de dados Spider 8®. Os testes de Kruskall-Wallis e Mann-Whitney possibilitaram a avaliação de quatro músculos dos tornozelos (Tibial Anterior Direito e Esquerdo, e Gastrocnêmio Medial Direito e Esquerdo). Durante a Passada e a Fase de Apoio, estes músculos realizaram esforços significativamente superiores no aclive e inferiores no declive. Já, na Fase de Balanço, apenas o músculo Tibial Anterior direito apresentou diferença significativa... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: With increasing longevity, the concern is with the accessibility that allows autonomy and human mobility. The movement of the human body depends on the anatomical and physiological dynamics of muscles and joints to handle the movement that is caused by centripetal forces. The human locomotion is produced by the transfer of the body in space, which depends on the march, an event of high complexity for analysis of rehabilitation and biomechanics. At this juncture, the scope of this study was to evaluate the muscular activity and to correlate the variables (Reason, Co-contraction and Plant Pressure on the heel) to analyze the biomechanical stress of the ankle during walking uphill, downhill and flat. Under Protocol n.138/2010 of project approval for Commission of Ethic in research , the data collection was applied in a sample of 11 female subjects, aged between twenty and fifty years, healthy and independent walking. For the path we used a ramp inclined 20°, whose beginning was marked with the touch above the insole containing the pushbutton for recording electromyography signals and power plant in sync. Participants used a pair of sandals sensorized enveloped with four load cells to measure Plant Pressures through long connecting each cell to the data acquisition system Spider 8®. The Kruskall-Wallis and Mann- Whitney enable the evaluation of four muscles of the ankle (anterior tibialis Right and Left, Right and Left Medial Gastrocnemius). During the Footstep and Support Phase, these muscles have made efforts significantly higher in the uphill and minor in the downhill. Already, in the Swing Phase, only the right anterior tibial muscle showed Root Mean Square, the tibialis anterior Right muscle showed difference significant electromyography activity, was greater in uphill. The reason between... (Complete abstract click electronic access below) / Orientador: Luiz Fernando Costa Nascimento / Coorientador: José Elias Tomazini / Banca: Luiz Heleno Moreira Duque / Banca: Mauro Gonçalves / Banca: Adalgiso Coscrato Cardoso / Banca: Valdeci Donizete Gonçalves / Doutor

No description available.

<p> Human upper limb motion analysis with sensing by way of consumer-off-the-shelf (COTS) devices presents a rich set of scientific, technological, and practical implementation challenges. The need for such systems is motivated by the popular trend toward the development of home based rehabilitative motor therapy systems in which patients perform therapy alone while a technological solution connects the patient to a therapist by performing data acquisition, analysis, and the reporting of evaluation results remotely. The choice to use COTS devices mirrors the reasons why they have become universally accepted in society in recent times. They are inexpensive, easy to use, manufactured to be deployable at large scale, and satisfactorily performant for their intended applications. These claims for the use of COTS devices also resound with requirements that make them suitable for use as low-cost equipment in academic research.</p><p> The focus of this work is on the development of a proof of concept human upper limb motion capture system using Myo and Sphero. The end-to-end development of the motion capture system begins with developing the software that is required to interact with these devices in MATLAB. Each of Myo and Sphero receive a fully-featured device interface that&rsquo;s easy to use in native MATLAB m-code. Then, a theoretical framework for upper limb motion capture and analysis is developed in which the devices&rsquo; inertial measurement unit data is used to determine the pose of a subject&rsquo;s upper limb. The framework provides faculties for model calibration, registration of the model with a virtual world, and analysis methods that enable successful validation of the model&rsquo;s correctness as well as evaluation of its accuracy as shown by the concrete example in this work.</p>

Trap-jaw ants are characterized by high-speed mandibles used for prey capture and defense. Power-amplified mandibles have independently evolved at least four times among ants, with each lineage using different structures as a latch, spring and trigger. We examined two species from the genus Myrmoteras (subfamily Formicinae), whose morphology is unique among trap-jaw ant lineages, and describe the performance characteristics, spring-loading mechanism and neuronal control of Myrmoteras strikes. Like other trap-jaw ants, Myrmoteras latch their jaws open while the large closer muscle loads potential energy in a spring. The latch differs from other lineages and is likely formed by the co-contraction of the mandible opener and closer muscles. The cuticle of the posterior margin of the head serves as a spring, and is deformed by approximately 6% prior to a strike. The mandibles are likely unlatched by a subgroup of closer muscle fibers with particularly short sarcomeres. These fast fibers are controlled by two large motor neurons whose dendrites overlap with terminals of large sensory neurons originating from labral trigger hairs. Upon stimulation of the trigger hairs, the mandibles shut in as little as 0.5 ms and at peak velocities that are comparable with other trap-jaw ants, but with much slower acceleration. The estimated power output of the mandible strike (21 kW kg(-1)) confirms that Myrmoteras jaws are indeed power amplified. However, the power output of Myrmoteras mandibles is significantly lower than distantly related trap-jaw ants using different spring-loading mechanisms, indicating a relationship between power-amplification mechanism and performance.