Dans un disque axisymétrique en équilibre, les vitesses galactocentriques radiales et verticales sont théoriquement nulles. Pourtant, de grands relevés spectroscopiques ont révélé que les étoiles du disque de la Voie Lactée sont animées de vitesses non nulles dans les directions radiale et verticale. Les structures en vitesse radiale sont généralement associées aux composantes non-axisymétriques du potentiel. Celles en vitesse verticale non nulle sont souvent associées à des excitations externes. Nous avons montré que la réponse stellaire à une perturbation spirale produit un déplacement radial et des mouvements verticaux non nuls. La structure du champ moyen de vitesse obtenue est cohérente avec les observations. De plus un modèle simple reposant sur une linéarisation des équations d'Euler reproduit naturellement ce résultat. Nous concluons que ces structures observées pourraient aussi être engendrées par des perturbations internes non-axisymétriques. / In an equilibrium axisymmetric galactic disc, the mean galactocentric radial and vertical velocities are expected to be zero everywhere. Recent spectroscopic surveys have however shown that stars of the Milky Way disc exhibit non-zero mean velocities outside of the Galactic plane in both the radial and vertical velocity components. While radial velocity structures have already often been assumed to be linked with non-axisymmetric components of the potential, non-zero vertical velocity structures are usually rather attributed to excitations by external sources. We show that the stellar response to a spiral perturbation induces both a radial velocity flow and non-zero vertical motions. The resulting structure of the mean velocity field is qualitatively similar to the observations. Such a pattern also emerges from an analytic toy model based on linearized Euler equations. In conclusion, non-axisymmetric internal perturbations can also be the source of the observed mean velocity patterns.

Existe um conceito difundido entre professores de educação física, fisioterapeutas e ortopedistas que o joelho não deve ser demasiadamente anteriorizado em relação à ponta do pé na direção ântero-posterior durante qualquer tipo de agachamento de modo a diminuir a carga mecânica imposta ao joelho. No entanto, são escassas as evidências quantitativas que corroboram este conceito. Este trabalho tem como objetivo estimar forças e torque na articulação do joelho em indivíduos saudáveis durante o exercício de agachamento livre com peso em dois modos diferentes de execução: a) joelho não ultrapassando a linha vertical que passa pelos dedos do pé; b) joelho ultrapassando essa linha vertical. Os sujeitos realizaram o agachamento com o pé direito sobre uma plataforma de força que mensurou os torques e forças de reação do solo. O membro inferior direito dos indivíduos (pé, perna e coxa) foram filmados com cinco câmeras digitais. Visando reconstruir o movimento dos segmentos, nós utilizamos a técnica de calibração do sistema anatômico (CAST), aumentando assim, a acurácia na reconstrução da posição tridimensional dos segmentos. O centro articular do quadril foi determinado pelo método rotacional e as forças e torques articulares internos líquidos foram determinados por dinâmica inversa. Os resultados obtidos mostram que o pico da carga mecânica no joelho, quando esse passa em média 11cm da linha do pé, é cerca de 31% maior na condição em que o joelho ultrapassa a linha do pé. Esses resultados implicam que não passar o joelho da linha do pé diminui a força de compressão patelofemoral, levando assim a uma menor solicitação mecânica nesta articulação. / There is a wide spread notion among health professionals that during a squat exercise the knee should not pass forward the forefoot region in order to not overload the knee joint. However, it seems there isn’t scientific literature to support or negate this concept. The goal of this paper is to investigate the effect of different foot-knee positions on the knee joint moment and on the patelofemoral force during squat, which was performed into two different ways: a) knee do not passing the forefoot region; b) knee passing the forefoot region. The subjects performed the squat exercise with the right foot on a force plate that measured the ground reaction force and moment components. The subject’s right leg (foot, shank, and thigh) and pelvis were filmed with five digital cameras. In order to reconstruct the segments’ movement, we used the Calibrated Anatomical System Technique (CAST), improving the accuracy on three-dimensional reconstruction of segment’s position. The hip center was determined by the rotational method and the internal net forces and torques were estimated by inverse dynamics. The results showed that during the condition were knee passed the forefoot region, the knee passed 11 cm on average, what resulted in a peak of mechanical load on the knee 30% higher in relation to the do not pass condition. Based on these results it is suggested that the knee should not pass the forefoot region during squatting in order to decrease the patelofemoral force.

Para se obter alto desempenho em máquinas-ferramenta de ultraprecisão, são necessários o desenvolvimento de sistemas de posicionamento e o controle de movimento, os quais não raramente devem operar com resolução e repetibilidade na faixa submicrométrica. A utilização das modernas técnicas de metodologia de projeto auxiliam no desenvolvimento deste tipo de sistema. Neste trabalho são discutidas e analisadas as diversas alternativas disponíveis para os elementos constituintes do sistema de posicionamento. Aspectos críticos como cinemática, acionamento, guias e apoios são estudados e confrontados usando o método de análise de valor. E baseados no resultado do estudo prévio, obtém-se um sistema híbrido para microposicionamento angular de alta rigidez e ampla largura de banda, capaz de posicionar uma superfície com resolução angular inferior a 4.\'10 POT.-5\' graus. Através das técnicas de modelagem, pode-se verificar a funcionalidade desse sistema projetado, quanto ao seu comportamento estático e dinâmico. Uma modelagem cinemática é apresentada com o objetivo de auxiliar na veracidade do projeto do posicionador angular, através da qual pretende-se observar a influência de cada ponto de apoio no posicionamento final. São apresentados os resultados obtidos em simulações numéricas, as quais constatam não só o próprio desempenho do posicionador, como também, a validade da técnica utilizada. / In order to achieve high performance in ultra-precision machine tools, appropriate capability is required of motion control and positioning systems which have to operate at resolutions and repeatability in the sub-micrometre range. Machining may reach high levels of precision through the use of suitable sensors, actuators and controllers so that the development of micro-positioner with low backlash, high bandwidth and accuracy is a crucial aspect of high precision machining technology. Modern design techniques can greatly assist in the development and design of such systems. In this work, several design options for the elements of a positioning system are discussed and analysed. Critical aspects such as kinematics, driving and bearings are studied and compared using the value analysis method. A hybrid system based upon the results of this study is proposed which combines the best characteristics of each design option. The system possesses the capability of positioning a workpiece and/or tool angularly and/or linearly (micro-tilt stage) with a resolution better than 4 \'10 POT.-5\' arc degree and high stiffness and bandwidth. Through modelling techniques, it is possible to verify the static and dynamic behaviour of the system. A kinematics model of the micro-tilt stage is presented in order to establish a relationship between the displacement of the actuators and the final position of the stage. It is anticipated that such an approach will be required in respect of interferometric feedback control. Simulations of the model are performed showing that the technique applied is valid and the system fulfils the requirements for ultra-precision design.

O primeiro arabesque é uma pose elementar do ballet clássico e para realiza-la, a bailarina precisa dominar quesitos técnicos que incluem: a manutenção do turnout, o posicionamento do pé de apoio (em meia-ponta ou em ponta), a utlização de sapatilhas específicas e as estratégias de inicação do movimento (arabesque relevé ou arabesque piqué). Assim, o proposito deste estudo foi descrever, avaliar e comparar os padrões cinéticos e cinemáticos do membro inferior da bailarina durante a execução do primeiro arabesque realizado com os quesitos técnicos acima descritos a fim de entender as diferenças e similaridades entre os quesitos avaliados. A amostra foi composta por 26 bailarinas com 13,5±5.02 anos de ballet clássico, as quais realizaram o arabesque piqué e relevé, com sapatilhas de ponta e meiaponta de forma aleatorizada, acompanhados por uma cadência musical adequada. Foram adquiridos: a componente vertical da força reação do solo (FRS) e do centro de pressão (COP), a variação angular das articulações do joelho e tornozelo nos planos sagital, frontal e transversal, além dos momentos articulares sagitais de joelho e tornozelo calculados por dinâmica inversa. As comparações inter-condições foram realizadas por ANOVAs dois fatores [estratégia de iniciação (2) x sapatilha(2)]. A avaliação da componente vertical da FRS mostrou efeito de interação entre sapatilhas e estratégias de iniciação, além de efeitos isolados no aumento da FRS vertical para o arabesque relevé. A avaliação do comportamento do COP mostrou efeito de interação entre todas as variáveis, novamente apontando maiores oscilações em relação ao arabesque relevé. As diferentes sapatilhas não modificaram o comportamento angular e nem o momento articular resultante de joelho e tornozelo, revelando que a estratégia de iniciação é fator determinante no resultado biomecânico final do arabesque / The first arabesque is an elementary pose of classical ballet. To perform it, the dancer needs to lead with technical questions that include: the maintenance of the turnout, the positioning of the support foot (pointe or half-pointe), the iniciation movement strategies (piqué or relevé arabesque). Thus, the purpose of this study was to describe, evaluate and compare the kinetic and kinematic patterns of the lower limb of the dancer during the execution of the first arabesque performed with the technical questions described above in order to understand the differences and similarities between the evaluated items. The sample consisted of 26 dancers with 13.5 ± 5.02 years of classical ballet, who performed the piqué and relevé arabesque, with slippers or pointe shoes, in randomized trails, accompanied by a suitable musical cadence. Were evaluated: the vertical component of the ground reaction force (FRS), the center of pressure distribution (COP), the angular variation of the knee and ankle joints in the sagittal, frontal and transverse planes, and the sagittal knee and ankle joint loads (inverse dynamics). The inter-condition comparisons were performed by ANOVAs two factors [initiation strategy (2) x ballet shoes (2)]. The evaluation of the vertical component of FRS showed an interaction effect between shoes and initiation strategies, as well as isolated effects in the increase of vertical FRS for arabesque relevé. The evaluation of the behavior of the COP showed an interaction effect among all variables, again pointing to greater oscillations in relation to the arabesque relevé. The different ballet shoes (pointe shoe or slipper) did not modify the angular behavior nor the knee and ankle joint loads, revealing that the initiation strategy is a determining factor in the final arabesque biomechanical result

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-10-24T17:20:42Z No. of bitstreams: 1 2014 - Agnaldo Machado de Andrade.pdf: 1647540 bytes, checksum: 99ee190f180231a22389dc30a31fa5eb (MD5) / Made available in DSpace on 2017-10-24T17:21:40Z (GMT). No. of bitstreams: 1 2014 - Agnaldo Machado de Andrade.pdf: 1647540 bytes, checksum: 99ee190f180231a22389dc30a31fa5eb (MD5) Previous issue date: 2014-09-05 / CAPES / The aim of this study was to analyze horses? morphological traits and kinematics of pace, trot and gallop movements, as well as, upward and downward transitions on a high speed treadmill in horses without riders and mounted on a sand track. Thirteen Brasilian Sport Horses horses were used, 12 females and 1 castrated male with 9.0?2.8 years old mean age and 472.5?34.2 Kg mean weight, from the Army Cavalry School (EsEqEx). Linear, angular and perimeter measurements were performed with horses at forced statio. The animals were filmed at a standardized environment on the treadmill with black background and spotlights lighting. High-speed treadmill (Sahinco?) and sand track covered with flat and smooth floor were used. The images were obtained and processed by Simi Reality Motion Systems? and filmed by PiA640 Basler camera. The experiment was carried out in a completely randomized design with two treatments (horses on a high speed treadmill and mounted horses on a sand track) in paired data and 13 replications (animals). The results were submitted to variance analysis and means were compared by paired t test (P<0.05). At the day of filming, the animal performed a war up for 10 minutes at walking, trotting and galloping speeds. On the track, horses were mounted by three experienced riding instructors. Horses were classified as medium shaped and hypermetric, being the mean values for IC and IDT 0.87 and 0.11, respectively. In kinematics analysis, the following variables studied were stride length, speed pace, support time, sleep time and members foot prints on the left and right sides. In the standing-pace course just suspension time and right side foot prints presented difference (p<0.05) with the highest mean values on treadmill of 0.39s and -0.22cm (retro foot prints). In the meeting step on the treadmill analysis differences were observed (p<0.05) in stride length, support time, sleep time and members foot prints on left and right sides with the highest mean values from treadmill analysis when comparing to the sand track. In the elongated pace course, treadmill analysis presented the highest mean values for stride length and pace speed 2.1m and 1.98m/s while sand track analysis presented the highest values for support time and members foot prints on the left and right sides. In upward transitions, the same variables were significative (p<0.05) for treadmill analysis, speed pace, sleep time and members foot prints on the left and right sides, however, on two transitions, support time was higher (p<0.05) for sand track analysis. In the downward transition from gallop to trot lower (p<0.05) support time and higher suspension time were observed, being 0.21s and 0.38s, respectively. Stride length was similar (p<0.05) on horses evaluated on a treadmill and sand track, however, speed of transition was higher on treadmill being 4.03m/s in regarding to sand track 3.2m/s. In conclusion, regarding the morphometry, horses were framed on the saddle pattern for medium shape and hypermetric and; regarding kinematics, suspension time was the only variable presenting higher values for treadmill in all transitions, while stride length and speed pace presented the highest mean values for treadmill apart from for station-pace and pace-trot transitions, suggesting it may be related to influences undefined on this study. / Objetivou-se analisar as caracter?sticas morfom?tricas dos equinos e a an?lise cinem?tica dos andamentos passo, trote e galope, assim como as transi??es ascendentes e descendentes desses andamentos em esteira de alta velocidade com os animais sem cavaleiro e em pista de areia montados. Foram utilizados 13 equinos da ra?a Brasileiro de Hipismo, sendo 12 f?meas e um macho castrado, com m?dia idade de 9,0 ? 2,8 anos e peso m?dio de 472,5 ? 34,2Kg provenientes da Escola de Equita??o do Ex?rcito (EsEqEx). As medidas lineares, angulares e de per?metro foram mensuradas com os equinos em esta??o for?ada. Os animais foram filmados em ambiente padronizado na esteira e na pista, com fundo preto e ilumina??o com holofotes. Foi utilizada esteira de alta velocidade (Sahinco?) e pista de areia coberta de piso plano e regular. As imagens foram obtidas e processadas no aplicativo Simi Reality Motion Systems? e filmada com c?mera Basler piA640. O ensaio foi conduzido em delineamento inteiramente casualizado com dois tratamentos (equinos em esteira de alta velocidade e equinos montados em pista de areia), em esquema de dados pareados, 13 repeti??es (animais) e os resultados submetidos ? an?lise de vari?ncia e as m?dias comparadas pelo teste t pareado (P<0,05). No dia das filmagens, os animais realizaram aquecimento com tempo de 10 minutos, ao passo, trote e galope. Na pista os equinos foram montados por tr?s experientes instrutores de equita??o. Os equinos foram classificados em mediol?neos e hiperm?tricos, sendo as m?dias 0,87 e 0,11 para IC e IDT.Na an?lise cinem?tica, as vari?veis estudas foram comprimento da passada, velocidade da passada, tempo de apoio, tempo de suspens?o e pegadas dos membros em lateral esquerdo e direito. No andamento esta??o-passo s? houve diferen?a (p<0,05) para o tempo de suspens?o e pegada lateral direito com os maiores valores m?dios para an?lise na esteira, 0,39s e -0,22cm (retropegada). No passo reunido houve diferen?a (p<0,05) para comprimento da passada, tempo de apoio, tempo de suspens?o e para as pegadas dos membros em lateral esquerdo e direito com os maiores valores m?dios para a an?lise na esteira em rela??o a pista de areia. No andamento passo alongado a an?lise na esteira apresentou os maiores valores m?dios para comprimento da passada e velocidade da passada, 2,1m e 1,98m/s j? a an?lise na pista de areia apresentou maiores valores de tempo de apoio e para as pegadas em lateral esquerdo e direito. Nas transi??es ascendentes, apresentaram valores significativos (p<0,05) para an?lise na esteira, velocidade da passada, tempo de suspens?o e pegadas, por?m nas duas transi??es o tempo de apoio foi maior (p<0,05) na an?lise na pista de areia. Na transi??o descendente do andamento galope para o trote foi observado menor (p<0,05) tempo de apoio e maior tempo de suspens?o nos equinos avaliados na esteira, de 0,21s e 0,38s, respectivamente. O comprimento da passada foi semelhante (p>0,05) nos equinos avaliados em esteira e em pista de areia, por?m a velocidade de transi??o obteve maior valor nos equinos avaliados na esteira, de 4,03m/s em rela??o ? avalia??o em pista de areia, de 3,2m/s. Conclui-se a partir da morfometria os equinos foram enquadrados no padr?o de sela em mediol?neos e hiperm?tricos e na cinem?tica a ?nica vari?vel que se manteve com valor maior na esteira em todas as transi??es foi o tempo de suspens?o, j? o comprimento da passada e a velocidade da passada apresentaram maiores valores na esteira exceto nas transi??es esta??o-passo e trote-passo, o que pode esta relacionada a influ?ncias n?o definidas no estudo.

Apesar do esforço despendido pelas comunidades acadêmica e industrial (artigos, patentes e protótipos de laboratório), as Máquinas de Cinemática Paralela - MCPs - ainda apresentam uma participação inexpressiva no mercado de máquinasferramentas e robôs. Uma das razões para este fato são os seus baixos índices de acurácia e repetibilidade, em comparação aos das máquinas de usinagem convencionais. Este trabalho apresenta a avaliação dos mapeamentos de flexibilidade e da 1ª freqüência natural sobre o posicionamento da peça de trabalho e direções preferenciais de usinagem, dentro do espaço de trabalho disponível de uma máquina-ferramenta de cinemática paralela. Atualmente esta análise tem sido realizada em máquinas de cinemática paralela utilizando-se do princípio dos trabalhos virtuais ou parcialmente envolvendo este método e o método dos elementos finitos com a superposição linear dos resultados de ambos. Este trabalho apresenta análise de flexibilidade, utilizando apenas o método dos elementos finitos, aplicada a uma arquitetura paralela do tipo 2PRS+2PUS, com 4 graus de liberdade (duas translações - Y e Z - e duas rotações - \'teta\'x e \'teta\'YG), denominada Tetraglide. Em todas as análises feitas o grau de liberdade \'teta\'YG foi mantido constante, \'teta\'YG = 0°. Desta forma todas as análises ocorreram sobre o plano YZ. A partir dessa análise de flexibilidade são avaliadas as cargas axiais nas barras, que unem os atuadores à plataforma móvel ao longo do espaço de trabalho, determinando-se onde ocorre flambagem. Após isto, ainda com o método dos elementos finitos, obtém-se a 1ª freqüência natural ao longo de cada espaço de trabalho com orientação constante, uma vez que o conhecimento desta freqüência é fator importante na avaliação do comportamento estrutural dinâmico de máquinas-ferramentas. Após estas análises, analisam-se parâmetros estruturais em análises de sensibilidade visando maximizar a menor 1ª freqüência natural observada em cada espaço de trabalho com orientação constante. / In spite of the effort spent by the academic and industrial communities (goods, patents and laboratory prototypes), the Parallel Kinematics Machines - PKMs - they still present an inexpressive participation in the market of machine-tools and robots. One of the reasons for this fact is their low indexes of accuracy and precision, in comparison with the machines of conventional milling. This work presents the evaluation of the compliance mapping (kinetostatic analysis) and natural frequency about the positioning of the work piece and milling preferential directions, inside the available workspace of a parallel kinematics machine tool. At present this analysis has been accomplished in parallel kinematics machine using the virtual work principle or partially involving this method and the finite element method, with the overlap of the results of both. This work presents a compliance analysis just using the finite element method in parallel kinematics machine of type 2PRS+2PUS with 4 degrees of freedom (two moves - Y and Z - and two rotations - \'teta\'x e \'teta\'YG), denominated Tetraglide. In all of the done analyses the degree of freedom \'teta\'YG was maintained constant, \'teta\'YG = 0°. This way all of the analyses occurred on the plan YZ. Starting from the compliance analysis the axial loads are evaluated in the bars, which connect the actuators to the movable platform along the workspace, determining where the buckling occurs. After this, with the finite element method, 1st natural frequency is obtained along each constant-orientation workspace, once the knowledge of this frequency is important factor in the evaluation of the dynamic structural behavior of machine-tools. After these analyses, structural parameters are analyzed in sensibility analyses seeking to maximize to smallest 1st natural frequency observed in each constant-orientation workspace.

L'objectif de ce travail de thèse était d'étudier les effets de l'hyperthermie sur la proprioception et leurs répercussions sur la cinématique de la course à pied. Nous avons élaboré un protocole expérimental composé de deux études pour répondre à cette question. La première expérimentation a exploré l'hyperthermie induite en mode passif et son effet sur la proprioception. Notre hypothèse était que les perturbations neuromusculaires induites par une hyperthermie passive générale pourraient affecter la proprioception et l'équilibre. 14 participants ont réalisé une série de tests de la fonction neuromusculaire ainsi que des tests de proprioception et d'équilibre statique et dynamique dans une chambre environnementale en conditions chaude (44°C-50°C) et contrôle (24°C). Les résultats de cette 1ère étude ont montré qu'une augmentation de la température rectale (39.0°C vs. 36.9°C) et cutanée (37.9°C vs. 32°C) en ambiance chaude par rapport à la situation de contrôle était associée à une réduction de l'amplitude du reflexe H, une diminution de l'acuité proprioceptive et des perturbations de l'équilibre statique et dynamique. Ces résultats suggèrent que l'hyperthermie passive détériore la proprioception et l'équilibre, ce qui pourrait affecter le geste sportif. Afin d'explorer les effets de l'hyperthermie active sur la proprioception, nous avons par la suite réalisé le test de proprioception active chez 12 coureurs entrainés avant et après un test de 30 minutes en course à pied dans des conditions chaude (39°C) et contrôle (22°C). Les résultats de cette étude ont montré une augmentation plus importante des contraintes thermiques, perceptives et cardiovasculaires en ambiance chaude comparé à la condition tempérée. En plus, nous avons observé une diminution de l'acuité proprioceptive suite à l'exercice en ambiance chaude mais pas tempérée. Ces résultats montrent que les altérations identifiées en situation d'hyperthermie passive lors de la première étude sont également spécifiques à un exercice en ambiance chaude. Lors de ce protocole expérimental, nous avons également exploré les répercussions de ces perturbations de la proprioception sur la cinématique de la course à pied. Pour ce faire, les paramètres spatio-temporels et cinématiques angulaires de la foulée ont été mesurés à vitesse constante (i.e., 70% de la vitesse maximale aérobie) lors de la première et dernière minute de l'exercice (la vitesse étant librement choisie de la 2ème à la 29ème minute). Nous avons ainsi montré une diminution de la fréquence et une augmentation de la longueur des foulées avec la fatigue dans les deux conditions ; accompagnée de changement des paramètres angulaires limités à un redressement du bassin et une diminution de l'angle de la cheville. Cependant, Il n'y avait aucun effet de la condition thermique ou d'interaction entre la fatigue et l'environnement thermique pour les paramètres spatio-temporels et cinématiques angulaires. Ces résultats suggèrent que l'hyperthermie induite par un exercice de course à pied affecte la proprioception de la cheville, mais que cette altération n'affecte pas la cinématique de la course à pied. Suite à ces travaux, nous pouvons donc conclure que la proprioception est affectée par l'hyperthermie induite soit par des méthodes passives ou actives. Ces altérations pourraient provenir des effets de l'hyperthermie sur les fonctions neuromusculaire et cognitive. Cependant, la dégradation de l'acuité proprioceptive avec une augmentation de la température rectale au-delà de 39°C n'affecte pas la cinématique de la course à pied, ce qui suggère une forte stabilité du pattern de course malgré une proprioception et des fonctions neuromusculaires affectées / The objective of this PhD was to investigate the effects of hyperthermia on proprioception and their impact on running gait kinematics. We developed an experimental protocol consisting of two studies to answer this question.The first experiment explored passive hyperthermia and its effects on proprioception and balance. We hypothesized that neuromuscular disturbances induced by passive hyperthermia would impair proprioception and balance. 14 participants performed a series of tests of neuromuscular function, proprioception, as well as static and dynamic balance in an environmental chamber under hot (44°C - 50°C) and control (24°C) conditions. The results of this first study showed that an increase in rectal (39.0°C vs. 36.9°C) and skin (37.9°C vs. 32°C) temperatures in hot compared to control ambient conditions was associated with a reduction in the amplitude of the Hoffman reflex, a decrease in the proprioceptive acuity and impairments in static and dynamic balance. These results suggest that passive hyperthermia deteriorates proprioception and balance, something that could potentially affect sports movement. ln order to explore the effects of active hyperthermia on proprioception, we subsequently performed the active discrimination test in 12 trained runners before and just after a 30-minute running time-trials under hot (39°C) and control (22°C) conditions. The results of this study showed a larger increase in thermal, perceptual and cardiovascular stresses when running in the heat as compared to running in a temperate environment. ln addition, we observed a decrease in proprioceptive acuity following exercising in the heat only. This showed that the proprioceptive impairments identified during the first study are also present following exercise-induced hyperthermia, but not exercise-induced fatigue without hyperthermia. During this study, we have also explored the impact of hyperthermia-induced alterations in proprioception on running gait kinematics. To do so, we measured angular kinematics and spatiotemporal stride parameters at a constant speed (i.e., 70% of the maximum aerobic speed) during the first and last minute of the exercise (whilst speed was freely chosen from the 2nd to the 29th minute). Results showed that fatigue decreased step frequency and increase step length under both conditions, along inducing a few little changes in the angular kinematic parameters limited to an increase of the PELVlS angle and a decrease of the ANKLE angle. However, no interaction effect was found for any of the spatiotemporal or angular stride parameters. These results suggest that exercise-induced hyperthermia impairs ankle proprioception, but that this alteration does not affect running kinematics. ln summary, proprioception is affected by hyperthermia induced either by passive or active methods. These alterations could be due to the effects of hyperthermia on neuromuscular and cognitive functions. However, the degradation of proprioceptive acuity with an increase in rectal temperature above 39 °C does not affect the kinematics of running, suggesting that running pattern remains stable despite proprioception and neuromuscular functions impairments

Ce document présente la mesure de rendements isotopiques issus de la fission de l'U238 obtenus suite à l'expérience SOFIA réalisée au GSI à Darmstadt (août 2012). Cette expérience novatrice utilise la technique de la cinématique inverse relativiste, qui présente plusieurs avantages : les fragments de fissions sont focalisés vers l'avant dans un cône de faible ouverture angulaire (grande efficacité géométrique), et possèdent un état de charge nul ce qui facilite considérablement la mesure des rendements élémentaires. Le dispositif SOFIA se compose tout d'abord d'une cible active, dans laquelle a lieu la fission par excitation coulombienne et d'une chambre d'ionisation qui permet à la fois la mesure de la charge nucléaire et de l'angle horizontal des deux fragments en coïncidence. La mesure des masses est faite en déterminant le rayon de courbure des fragments, déviés par un puissant aimant (ALADIN), grâce à deux détecteurs de positions (MWPC), et par une mesure de temps de vol, qui nécessite une résolution extrême d'environ 40 ps FWHM pour que la séparation des isotopes lourds voisins soit acceptable. L'analyse des données montre que les objectifs initiaux ont étés remplis, puisque la séparation isotopique est atteinte sur toute la gamme des fragments de fission. Un effet pair-impair significatif est observé dans les rendements en charge, dont le spectre présente, comme attendu, une valeur moyenne pour la charge lourde très proche de Z = 54. L'effet pair-impair neutron présente, étonnamment, une amplitude et une forme très similaire à celle mesurée sur des fissions en neutrons thermiques. Le rapport pic/vallée des distributions en masses indiquent que l'énergie d'excitation est proche des 14 MeV attendus. Enfin, nos mesures sont très souvent comparées au code GEF qui donne des résultats toujours très proches des nôtres. / The isotopic fission yields of U 238 following the SOFIA experiment, conducted at the GSI facility (Darmstadt), are presented here. This experiment takes advantage of the inverse kinematics technique at relativistic energies. Benefits are several : fission fragments are highly focused (high geometrical efficiency) and are also completely stripped, which greatly simplifies their nuclear charge measurement. The first detector of the SOFIA setup is an active target in which fission occurs via electromagnetic excitation, followed by an ionization chamber to measure the nuclear charge and the horizontal angle of both fission fragments. The masses are deduced by the bending radius measurement of the fragments, deflected by a strong magnet (ALADIN), thanks to two position detectors (MWPC), and also by a highly resolved time-of-flight measurement (40 ps FWHM) so that heavy neighboring isotopes can be separated. The data analysis shows that the main goals are achieved since the isotopic separation is reached over the whole range of the fission fragments. A strong even-odd effect is seen in the charge spectrum, which also exhibits a mean heavy charge close to Z = 54. Surprisingly, the neutron even-odd effect of the light region is seen to be very close to the one in thermal neutron induced fission. The peak-to-valley ratio of the mass spectrum confirms that the mean excitation energy at fission is close to the expected one (14 MeV). The GEF code is used for comparison and always gives results very close to ours.

abstract: As the junction between the head and the trunk, the neck functions in providing head stability during behaviors like feeding to facilitating head mobility during behavior like grooming and predator vigilance. Despite its importance to these vital behaviors, its form and function remain poorly understood. Fossil hominin cervical vertebrae preserve a striking diversity in form despite the commitment to orthograde bipedality. Do these differences in cervical vertebral form correspond to functional variations among our recent ancestors? This dissertation attempts to understand 1) how does the neck function in head stability and mobility 2) how do these functions relate to cervical vertebral form. Kinematic and passive range of motion studies were conducted in several species of primate to obtain measures of function which were subsequently related to skeletal form. Results show that cervical vertebral morphology does not significantly covary with differences in joint mobility. Rather, they implicate the critical role of ligaments and muscles in facilitating head mobility. Results of the kinematics study show that the neck plays a role in maintaining head stability during locomotion. However, the kinematic data do not significantly correlate with morphological variation among primate species. Given the negative results of the extant morphological analyses, it is difficult to apply them to the fossil record. As such, the functional significance of the disparate morphologies found in the hominin fossil record remain ambiguous. / Dissertation/Thesis / Doctoral Dissertation Anthropology 2019

Soft robotic systems are becoming increasingly popular as they are generally safer, lighter, and easier to manufacture than their more rigid, traditional counterparts. These advantages allow an increased sense of freedom in both the design and operation of these platforms. In this work, we seek methods of leveraging this freedom to both design and plan motions for two different serial-chain, pneumatically actuated manipulators developed by Pneubotics, a small startup company based in San Francisco. In doing so, we focus primarily on two related endeavors: (1) the optimal kinematic design of these and other similar robots (i.e., choosing link lengths, base positioning, etc.), and (2) the planning of smooth paths in joint space that enable these robots to perform useful tasks. Our method of design optimization employs a genetic algorithm in combination with maximin multi-objective optimization techniques to efficiently generate a diverse set of Pareto optimal designs. This set represents the optimal region of the design space and highlights inherent tradeoffs that designers must make when choosing a particular set of design parameters for manufacture. In our work, we have chosen to optimize inflatable robots to be both dexterous, and to be able to support loads near the ground with limited deflection. We have also applied our framework to optimize a plastic manipulator to perform painting motions. In our approach to motion planning we simultaneously optimize the base position and joint motions of a robot in order to enable its end effector to follow a smooth desired trajectory. While this method of path planning generalizes to any kind of robot, we envision it to be especially applicable to soft robots and other mobile robots that can be quickly and easily repositioned to perform tasks in varying environments. Our method of path planning works by moving a set of virtual robot arms (each representing a single configuration in a sequence) branching from a common base, to a number of assigned target poses associated with a task. Additional goals and hard constraints (including joint limits) are naturally incorporated. The optimization problem at the core of this method is a quadratic program, allowing constrained high-dimensional problems to be solved in very little time. We demonstrate our method by planning and performing painting motion on two different systems. We also demonstrate in simulation how our planner could be used to perform several common tasks including those involving, pick-and-place, wiping and wrapping motions.