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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

Locomotor Function and the Evolution of the Primate Pelvis

January 2010 (has links)
abstract: The bony pelvis is a pivotal component of the locomotor system, as it links the hindlimb with the trunk and serves as anchorage for the primary propulsive musculature. Its shape is therefore expected to be adapted to the biomechanical demands of habitual locomotor behavior. However, because the relationship between locomotor mechanics and pelvic morphology is not well understood, the adaptive significance of particular pelvic traits and overall pelvic shape remains unclear. This study used an integrative, dual approach to elucidate the relationship between form and function in the primate pelvis. A biomechanical cylinder model of pelvic stress resistance was tested using in vitro strain analysis of monkey and ape cadaver specimens. These results were used to refine adaptive hypotheses relating pelvic form to locomotor mechanics. Hypotheses of adaptation were then tested via univariate and geometric morphometric methods using a taxonomically broad, comparative sample of 67 primate taxa. These results suggest that the pelvis exhibits some iliac and ischial adaptations to stress resistance that are associated with the biomechanical demands of habitual locomotor loading and of body size. The ilium and ischium exhibit relatively low levels of strain during experimental loading as well as adaptations that increase strength. The pubis exhibits relatively high strains during loading and does not vary as predicted with locomotion. This integrated study clarifies the relationship between strain and adaptation; these results support the hypothesis that bones adapted to stress resistance exhibit low strains during typical loading. In general, the cylinder model of pelvic biomechanics is unsupported. While the predictions of loading regimes were generally rejected, the inability of these methods to test the possible occurrence of overlapping loading regimes precludes outright rejection of the cylinder model. However, the lack of support for predicted global responses to applied loading regimes suggests that pelvic stress resistance may be better explained by a model that accounts for local, functional subunits of pelvic structure. The coalescence of a localized model of pelvic biomechanics and comparative morphometrics has great potential to shed light on the evolution of the complex, multi-functional structure of the pelvis. / Dissertation/Thesis / Ph.D. Anthropology 2010
192

Evolved neural network approximation of discontinuous vector fields in unit quaternion space (S³) for anatomical joint constraint

Jenkins, Glenn Llewellyn January 2007 (has links)
The creation of anatomically correct three-dimensional joints for the simulation of humans is a complex process, a key difficulty being the correction of invalid joint configurations to the nearest valid alternative. Personalised models based on individual joint mobility are in demand in both animation and medicine [1]. Medical models need to be highly accurate animated models less so, however if either are to be used in a real time environment they must have a low temporal cost (high performance). This work briefly explores Support Vector Machine neural networks as joint configuration classifiers that group joint configurations into invalid and valid. A far more detailed investigation is carried out into the use of topologically evolved feed forward neural networks for the generation of appropriately proportioned corrective components which when applied to an invalid joint configuration result in a valid configuration and the same configuration if the original configuration was valid. Discontinuous vector fields were used to represent constraints of varying size, dimensionality and complexity. This culminated in the creation corrective quaternion constraints represented by discontinuous vector fields, learned by topologically evolved neural networks and trained via the resilient back propagation algorithm. Quaternion constraints are difficult to implement and although alternative methods exist [2-6] the method presented here is superior in many respects. This method of joint constraint forms the basis of the contribution to knowledge along with the discovery of relationships between the continuity and distribution of samples in quaternion space and neural network performance. The results of the experiments for constraints on the rotation of limb with regular boundaries show that 3.7 x lO'Vo of patterns resulted in errors greater than 2% of the maximum possible error while for irregular boundaries 0.032% of patterns resulted in errors greater than 7.5%.
193

Modeling ADHD: Impulsivity, hyperlocomotion, and sensitivity to nicotine in the SHR strain of rat

January 2015 (has links)
abstract: ADHD is a childhood neurobehavioral disorder characterized by inordinate levels of hyperactivity, inattention and impulsivity. The inability to withhold a reinforced response, or response inhibition capacity (RIC), is one aspect of impulsivity associated with ADHD. The first goal of this dissertation was to evaluate the fixed minimum interval (FMI) schedule as a method for assessing RIC. Chapter 2 showed that latencies were substantially more sensitive than FMI-derived estimates of RIC to the effects of pre-feeding and changes in rate and magnitude of reinforcement. Chapter 3 examined the ability of the FMI to discriminate between spontaneously hypertensive rats (SHR), an animal model of ADHD, and Wistar Kyoto (WKY) controls. Results from Chapter 3 showed that RIC was not substantially different between SHR and WKY rats. However, latencies were significantly shorter for SHRs than for WKYs suggesting incentive motivation differed between strains. The second goal of this dissertation was to examine the sensitivity of the SHR to nicotine. ADHD is a risk factor for tobacco dependence. The goal of Chapters 4 and 5 was to determine whether the SHR provided a model of ADHD-related tobacco sensitivity. Chapter 4 examined nicotine's locomotor and rewarding effects in adolescent SHRs using the conditioned place preference (CPP) procedure. SHRs developed CPP to the highest nicotine dose tested and were sensitive to nicotine's locomotor-enhancing properties. WKY controls did not develop CPP to any nicotine dose tested and were not sensitive to nicotine's locomotor properties. However, it is likely that nicotine effects were obscured by a pseudo-conditioning to saline in WKYs. Chapter 5 demonstrated that SHRs were more active than WKYs in the open-field but not in the Rotorat apparatus. Results also showed that SHRs and WKYs were both sensitive to nicotine's locomotor sensitizing effects. However, WKYs were more sensitive than SHRs to nicotine's locomotor suppressing effects. Collectively, results from Chapters 4 and 5 show that SHRs are sensitive to the rewarding and locomotor-enhancing properties of nicotine. However, more research is necessary to confirm that SHRs are a suitable model for studying ADHD-related tobacco use. / Dissertation/Thesis / Doctoral Dissertation Psychology 2015
194

Measuring Glide Reflection Symmetry in Human Movements

January 2017 (has links)
abstract: Many studies on human walking pattern assume that adult gait is characterized by bilateral symmetrical behavior. It is well understood that maintaining symmetry in walking patterns increases energetic eciency. We present a framework to provide a quantitative assessment of human walking patterns, especially assessments related to symmetric and asymmetric gait patterns purely based on glide reflection. A Gliding symmetry score is calculated from the data obtained from Motion Capture(MoCap) system. Six primary joints (Shoulder, Elbow, Palm, Hip, Knee, Foot) are considered for this study. Two dierent abnormalities were chosen and studied carefully. All the two gaits were mimicked in controlled environment. The framework proposed clearly showed that it could distinguish the abnormal gaits from the ordinary walking patterns. This framework can be widely used by the doctors and physical therapists for kinematics analysis, bio-mechanics, motion capture research, sports medicine and physical therapy, including human gait analysis and injury rehabilitation. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2017
195

Efeitos da experiência no andar na organização da passada durante a ultrapassagem sobre obstáculos em bebês

Bortolaia, Ana Paula [UNESP] 03 1900 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:22:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-03Bitstream added on 2014-06-13T19:49:08Z : No. of bitstreams: 1 bortolaia_ap_me_rcla.pdf: 1695131 bytes, checksum: 3b8502e6f7817be294f35326f50bbdfe (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O objetivo deste estudo foi examinar a organização das passadas do andar, em bebês com diferentes experiências no andar, durante a ultrapassagem de um obstáculo. Trinta bebês foram distribuídos de acordo com o tempo de aquisição do andar independente em 3 grupos: 1, 3 e 6 meses de experiência no andar. A tarefa consistiu em caminhar sobre uma passarela em 2 condições experimentais: sem e com um obstáculo de espuma com 2 cm de altura e 3 cm de largura. Marcas foram afixadas nos centros articulares dos membros inferiores dos bebês e o andar foi filmado no plano sagital para ambos os lados, simultaneamente. Três ciclos para o andar normal, três para a perna de abordagem e três para a perna de suporte foram digitalizados utilizando o sistema APAS. Com base nas informações espaciais e temporais, comprimento, duração, cadência, velocidade, duração das fases de suporte e de balanço e fase relativa entre os membros foram calculadas. Ainda, as distâncias horizontal e vertical entre pé e obstáculo foram calculadas para as pernas de abordagem e de suporte. Os resultados indicaram que os bebês do grupo 1 mostraram passadas mais curtas e mais lentas do que os bebês dos grupos 2 e 3. Ainda, bebês do grupo 1 mostraram fase de suporte maior do que bebês do grupo 2. Quando os bebês tiveram que ultrapassar o obstáculo, mostraram passadas mais curtas e mais lentas do que na situação sem obstáculo. Ainda, bebês dos grupos 2 e 3 apresentaram cadência menor durante a passada com obstáculo e fase de suporte e fase de suporte simples menores no momento da ultrapassagem e fase de segundo duplo suporte maior após a ultrapassagem do obstáculo para a perna de abordagem. Também diminuíram a porcentagem da fase relativa referente a coordenação intermembros para a perna de abordagem e mostraram pequenas alterações no padrão coordenativo... / The purpose of this study was to examine the step walking organization during obstacle avoidance in infants with different walking experience. Thirty infants were distributed into trree groups according with their independent walking experience: one, three and six months of walking experience. The task consisted of walking in a runway in two experimental conditions: without and with a foam obstacle with 2 cm high and 3 cm wide. Markers were placed on the joint centers in both infants' lower extremity and walking performances were videotaped in the sagittal plane for both sides, simultaneously. Three cycles for normal walking, three for supportive leg and three for approaching leg were digitized using the APAS system. Based on the espacial and temporal information, stride length, duration, cadence, velocity, duration of support and swing phases and relative phase between limb were calculated. The horizontal and vertical distances between foot and obstacle were also calculated for both supportive and approaching legs. The results indicated that the infants of group 1 walked with shorter stride length and slower velocity than the infants of group 2 and 3.The first group showed support phase greater than the second group. When infants had to step over the obstacle, they walked with shorter stride and slower velocity than when they did not have to step over the obstacle. Furthermore, the infants from group 2 and 3 showed lower cadence than infants from group 1 when stepping over the obstacle and smaller support and single support phases during stepping over the obstacle and second double support phase greater after stepping over the obstacle for the approaching leg. Also, the phase relative percentage regarding interlimb coordination for approaching limb was smaller and few variations in coordination pattern between the shank and thigh segments for approaching... (Complete abstract, click electronic address below)
196

Analise eletromiografica dos musculos vastus medialis, vastus lateralis, semitendinosos e biceps femoris (caput longum) durante exercicio no aparelho "STEPPING MACHINE"

Zuccolotto, Deborah Gatti 04 January 1996 (has links)
Orientador: Fausto Berzin / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-07-21T05:55:24Z (GMT). No. of bitstreams: 1 Zuccolotto_DeborahGatti_M.pdf: 1779011 bytes, checksum: 8c0c5c2a35b2c7c203d0461c594ec465 (MD5) Previous issue date: 1996 / Resumo: A proposta deste trabalho foi observar o comportamento eletromiográfico dos músculos Vasto Medial Oblíquo, Vasto Lateral, Semitendíneo e Bíceps da Coxa (porção longa) durante atividade no aparelho "STEPPING MACHINE", tomando-se as medidas de ângulo 0°, 30°, 60°, 90° para a flexão e extensão da perna na articulação do joelho. Foram analisados 10 voluntários adultos normais, utilizando-se um eletromiógrafo de 8 canais, mini-eletrodos de superfície do tipo BECKMAN e um eletrogoniômetro. O método estatístico empregado foi a análise de variância (ANOVA) e o teste de Tukey. Os resultados mostraram que no movimento de flexão, o músculo Vasto Medial Oblíquo apresentou diferença dos potenciais médios de ação ao nível de 5% de significância para as medidas de ângulo 90°, 30° e 0° e também diferença sifnificante entre 60° e 0°. O músculo Vasto Lateral apresentou diferença significante também em 5% no ângulo 90° em relação °a 60°, 30° e 0°, além de diferença entre 60° e 0°. Os músculos semitendíneo e bíceps da coxa não apresentaram diferença significativa nas diferentes medidas de ângulo. Durante o movimento de extensão do joelho, os músculos Vasto Medial Oblíquo e Vasto Lateral, apresentaram diferença entre as medidas de ângulo 90° e 60° em relação às medidas 30° e 0°. Os músculos semitendíneo e bíceps da coxa, não apresentaram diferença significante entre os potenciais de ação nas várias angulações analisadas. Os resultados sugerem que o aparelho "STEPPING MACHINE" pode ser indicado na reabilitação pós-operatória da articulação do joelho / Abstract: The purpose of this paper was to observe the electromyographyc behaviors of the Vastus Medialis, Vastus Lateralis, Semitendineous and Biceps Femoris Muscles during activity in the Stepping Machine equipament, taking the angle measurement 0°, 30°, 60° and 90° for the leg flexion and extension in the knee joint. Ten normal adults volunteers were analysed by using a 8 channels electromyographer, mini surface electrode Beckman type and electrogoniometer. The statistics method utilized was the variance analysis (ANOVA) and the Tukey test. The results showed that in the joint movement Vastus Medialis Muscle presented difference of the medius potencials of action in 5% level of significance for the angle 90° measurement, 30° and 0° and significant difference among 60° and 0°. The Vastus Lateralis muscle presented significant difference also in the angle 90° in 5% in relation of 60°, 30° and 0°, beyond the difference among 60° and 0°. The semitendineous and biceps femoris muscles didn't present significant . difference in different measures of the angles. During the knee joint extension, the Vastus Medialis and Vastus Lateralis muscles presented difference among the 90° and 60° angles in relation to 30° and 60° measurement. The Semitendineous and Biceps Femoris didn't show difference significant among the potencials action in several angled analysed. The results suggest that the Stepping Machine can be indicate in the post-operation rehabilitation / Mestrado / Fisiologia e Biofisica do Sistema Estomatognatico / Mestre em Odontologia
197

The locomotory mechanisms of lower tetrapods

Barclay, Oliver R. January 1944 (has links)
No description available.
198

Breathing and locomotion in birds

Tickle, Peter George January 2010 (has links)
Birds are a diverse group of vertebrates, with over 10,000 extant species. Diversification into volant, aquatic and terrestrial environmental niches has precipitated a remarkable morphological diversity between species. Birds have a unique respiratory system consisting of a rigid lung connected to an air sac system. Air is pumped into the respiratory system via movements of the ribcage and sternum. Previous research identified the uncinate processes, ossified projections extending from the vertebral ribs, as critical respiratory and locomotor structures. Uncinate processes facilitate inspiration and expiration through associated muscles that displace the ribs and therefore sternum. External intercostal muscles project from the processes and function during locomotion to stabilise body roll. Therefore uncinate processes provide a link between breathing and locomotion in birds. The objective of my PhD is to extend beyond this basic research on uncinate processes to investigate how diversity in avian body morphology relates to the fundamental functions of breathing and locomotion.While the function of uncinate processes in respiration has been identified, the mechanism whereby ventilatory movements are elicited is not known. Therefore I present a model that demonstrates how respiratory movements of the skeleton are facilitated by the lever action of uncinate processes. Furthermore, variation in process and sternal morphology is driven by adaptation to different forms of locomotion. Therefore fundamental differences in breathing mechanics may be associated with specialisation to locomotor behaviour. Detailed developmental studies of the uncinate processes in birds are almost nonexistent. I provide the first detailed description of developmental changes in the uncinate processes in the turkey. Ossification of the uncinate processes begins around the time of hatch. However, the base is cartilaginous upon hatching and so the lever action of the processes may be compromised in the chick. I provide further evidence for a functional link between process length and respiratory physiology, since elongated processes support an elevated resting metabolic rate in birds. This link was further explored in physiological experiments where the energetic cost of walking in the barnacle goose was manipulated by load carrying. Carrying extra mass on the sternum is more energetically costly than an equivalent back load indicating that the cost of breathing increased. A directly proportional relationship exists between increasing mass of back load and metabolic rate, while sternal loads were approximately twice as expensive to carry during locomotion. Leg loads incurred the greatest increase in metabolism. Finally, I demonstrate how uncinate processes functioned as respiratory structures in basal avian species and a theropod ancestor of modern birds. Development of the uncinate processes may have been an important step in the evolution of the avian lung - air sac system.The principal findings of the five first author research articles presented in this PhD thesis shed important new light on the ventilatory mechanics in birds and highlight interactions between breathing and locomotion. Diversity in avian body morphology driven by adaptation to various locomotor behaviours has resulted in modification of the respiratory system.
199

Postcranial Morphology and the Locomotor Adaptations of Extant and Extinct Crocodylomorphs and Lepidosaurs

Rooney, Laura 01 May 2018 (has links)
I have collected a series of linear measurements of the postcranial skeletons of 43 extant crocodylian and lepidosaur taxa to determine if those engaging in similar locomotor behavior display similar morphology despite phylogenetic differences. Stepwise discriminant function analyses reveal reptile locomotor mode can be accurately predicted (over 80% correct) based on morphology. Semi-aquatic taxa are distinguished by a longer ischium relative to pubis length, a longer scapula relative to humerus length, and a broader acetabulum than terrestrial and arboreal taxa. Arboreal taxa display a more elongate, gracile humerus and a smaller acetabulum. This morphometric data can potentially be used to predict the locomotor behavior of a wide range of extinct reptile taxa. Within this study, Hyposaurus rogersii, Necrosuchus ionensis, Alligator sp. of the Gray Fossil Site, Crocodylus affinis, and Allognathosuchus mooki were examined and all were inferred to be semi-aquatic by the discriminant function analysis.
200

Design of a hexapod robot using artificial intelligence for the routes of the peruvian andes

Abarca, Arnold, Quispe, Grimaldo, Zapata-Ramirez, Gianpierre, Raymundo-Ibanez, Carlos, Rivera, Luis 01 November 2019 (has links)
El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / This paper presents an alternative solution to improve the locomotion system of a hexapod robot by artificial intelligence. Through an optimal design to achieve static stability, dynamic stability and optimize energy consumption through an autonomous system that is able to perform trajectories without any inconvenience. For the robot to move without flaws has certain restrictions in design (weight, size, materials, etc.) The hexapod has a high degree of movement and this allows many trajectories handle at the time of travel. Using sensors under certain working conditions we will obtain the necessary data and signals to satisfactorily comply with the hexapod robot design. / Revisión por pares

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