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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.
1

Ontogeny of bipedalism : pedal mechanics and trabecular bone morphology

Zeininger, Angel Diane 21 February 2014 (has links)
A unique pattern of pedal loading from heel-strike at touchdown to hallucal propulsion at toe-off is a distinct feature of mature human bipedalism, however, its first appearance in the fossil record is debated. The main goal of this dissertation is to identify anatomical correlates to a modern human heel-strike, rigid foot, and propulsive hallucal toe-off. First, a biomechanical analysis of toddler walking is used as a 'natural experiment' to investigate the influence of non heel-strike (NHS, n = 11) and immature heel-strike (IHS, n = 7) on the location of the center of pressure and orientation of the ground reaction force resultant in relation to specific foot bones during stance phase. With an expanded knowledge of foot bone loading in toddlers, a microarchitectural approach is used to test the influence of a heel-strike, rigid foot, and propulsive hallucal toe-off on trabecular bone fabric properties in an ontogenetic series of human and African ape (chimpanzee, bonobo, and gorilla) calcanei, tali, first metatarsal heads and hallucal distal phalanges. This dissertation presents the first ontogenetic analysis of pedal trabecular bone in primates. Heel-strike and toe-off are developmentally independent from one another. Although most toddlers lack a hallucal toe-off, NHS and IHS apply equally high propulsive forces when the entire width of their forefoot is in contact with the ground. Biomechanical and fossil evidence suggest that a generalized active propulsion may have preceded the evolution of a propulsive hallucal toe-off. Although pedal trabecular fabric properties are more complex than predicted, trabecular correlates to heel-strike and hallucal toe-off are identified within adult human foot bones. Compared to toddlers and African apes, adult humans have a unique combination of relatively thick trabecular struts and an anteroplantar to posterodorsal primary trabecular orientation in the plantar aspect of the calcaneal tuber. In the calcaneal tendon volume of interest, adult humans have a unique anteroplantar to posterodorsal primary trabecular orientation associated with a propulsive hallucal toe-off. This dissertation provides the comparative context necessary to begin assessing the evolution and developmental timing of foot function and specific bipedal gait events in juvenile and adult fossil hominins. / text
2

Sex-Based Differences in Calcaneal Injury Tolerances Under High-Rate Loading

Ceritano, Davide Walter 24 June 2020 (has links)
In this experiment, average calcaneal fracture force is measured across male and female groups. The purpose of this experiment is an analysis of alternatives exploring the importance of sex-based criteria in models representing injuries typical in underbody blast environments. Seventeen (17) right legs were harvested at the knee from cadavers representing three anthropometries: 50th percentile male (6), 75th percentile female (6), and 5th percentile female (5). Care was taken to preserve anatomically correct geometry as the legs were cut to equal lengths, the tibia and fibula were potted in Dyna-Cast®, flesh and ligaments were excised from the inferior surface of the calcaneus, and a small Dyna-Cast® pad was poured and sanded flat – interfacing with the exposed calcaneal surface. Each test specimen was mounted in a custom fixture and exposed once to high-rate axial loading characterized by a constant acceleration and 25.4mm intrusion, achieving an average speed of 4.7m/s (σ = 0.3m/s) in 10ms. Input acceleration was measured by an Endevco 7264c accelerometer and a Denton 2513 six-axis load cell measured reaction force proximal to the specimen. A VR Phantom v9.1 camera recorded x-ray imagery at 2k frames per second. Data were collected by a TDAS Pro data acquisition system at 20k samples per second and filtered in accordance with SAE J211. Time of fracture, established through x-ray imagery, was used to determined fracture force from the electronically synchronized load-cell data. 100% injury was recorded. Average calcaneus fracture forces were reported as follows: 5406N (σ = 780N) for 50th percentile males, 4130N (σ = 1061N) for 75th percentile females, and 2873N (σ = 1293N) for 5th percentile females. Statistical significance was established between the reported averages according to three ANOVA tests: One-way (p = 0.0054), Brown-Forsythe (p = 0.0091), and Welch's (p = 0.0156). Unpaired Student's t-test confirmed significant differences between 50th percentile male vs 75th percentile female (p = 0.0469) and 50th percentile male vs 5th percentile female (p = 0.0030); the t-test did not show significance between the two female groups (p = 0.1315). Average impulse-to-fracture was calculated for each group and found to be not statistically significant. / Master of Science / A marked shift can be found in combat wound epidemiology towards a predominance of extremity injuries sustained from explosives. The Warrior Injury Assessment Mannequin (WIAMan) Project sought to develop a baseline dataset of post-mortem human surrogate responses to realistic explosive loading and correlate it to a highly instrumented mannequin for the further development of combat vehicles and personal protective gear. The following experiment exists within the WIAMan paradigm as an analysis of alternatives exploring the adequacy of the above mentioned baseline dataset in directly representing both male and female injuries. More specifically, this experiment interrogates the differences in average fracture forces between male and female calcanei across three anthropometries: 50th percentile male, 75th percentile female, and 5th percentile female. Testing was carried out on 17 right cadaver legs cut to equal lengths, potted proximally in Dyna-Cast®, with the inferior surface of their calcanei exposed; a small Dyna-Cast® pad was poured for each calcaneus and sanded flat. Each test specimen was fixed to a Denton 2513 six-axis load cell proximally and exposed to a high-rate, constant acceleration, 25.4mm displacement aligned with the calcaneus along the long axis of the leg bones. Fracture time, established through x-ray images recorded at 2k frames per second with a VR Phantom V9.1 camera, was used to determine load cell force measurement at fracture. Average calcaneus fracture forces were reported as follows: 5406N (σ = 780N) for 50th percentile males, 4130N (σ = 1061N) for 75th percentile females, and 2873N (σ = 1293N) for 5th percentile females. Statistical significance was established between the reported averages according to three ANOVA tests: One-way (p = 0.0054), Brown-Forsythe (p = 0.0091), and Welch's (p = 0.0156). Unpaired Student's t-test confirmed significant differences between 50th percentile male vs 75th percentile female (p = 0.0469) and 50th percentile male vs 5th percentile female (p = 0.0030); the t-test did not show significance between the two female groups (p = 0.1315). Average impulse-to-fracture was calculated for each group and found to be not statistically significant.
3

Investigation into the Paleobiology of Dasypus bellus Using Geometric Morphometrics and Variation of the Calcaneus

Jasinski, Steven E., Wallace, Steven C. 01 January 2014 (has links)
The extinct taxon Dasypus bellus has long been considered identical to the extant Dasypus novemcinctus osteologically when disregarding allometric differences. In this study, we undertake a preliminary investigation into this extinct taxon and an extant relative D. novemcinctus, by comparing the calcanea of these two dasypodids. Clear osteological differences are observed including a mediolaterally-reduced facet region, an anteriorly-shortened calcaneal head, a reduced peroneal process, and a curved and dorsoventrally-shortened calcaneal foot in D. bellus. Such characters are not allometric and likely correlate to distinct behavioral differences. Specifically, we suggest that D. novemcinctus maintains a more fossorial lifestyle, while the larger D. bellus was likely more terrestrial, with potentially little digging behavior. Such lifestyle differences could not only explain the osteological differences present, but also why fossils of D. bellus have been recovered farther north than the present range of D. novemcinctus. Fossils of Dasypus may need to be re-evaluated to determine how these two taxa relate temporally and geographically, which may have further implications regarding some past interpretations and provide new details on the behavior and potential relationships between these (and other) xenarthrans.
4

Utilização do método hálux-calcâneo na identificação de desvios de crescimento em recém-nascidos / Using the method hallux-calcaneus to identify deviations in new-borns growth

Rocha, Érika Lopes 07 May 2013 (has links)
Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2015-04-10T13:53:37Z No. of bitstreams: 2 Dissertação - Erika Lopes Rocha -2013.pdf: 1231680 bytes, checksum: 3d5c8266c2c0ac31b16e8142d1aa7a9b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-04-10T14:43:11Z (GMT) No. of bitstreams: 2 Dissertação - Erika Lopes Rocha -2013.pdf: 1231680 bytes, checksum: 3d5c8266c2c0ac31b16e8142d1aa7a9b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-04-10T14:43:11Z (GMT). No. of bitstreams: 2 Dissertação - Erika Lopes Rocha -2013.pdf: 1231680 bytes, checksum: 3d5c8266c2c0ac31b16e8142d1aa7a9b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2013-05-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The HCL used in the GA and BW evaluation of normal NB and stillbirths exists for nearly a century and has been considered as a positive method inthese NBs evalua-tion. However, the results are scarce and inconsistent on studies that tried to clarify the relationship of data measured by the method in groups of NB with DIUG. The aim of this study was to estimate the prevalence of NB / stillbirths with DIUG, according to the HCL method and its relation with high-risk pregnancy. It is a cross-sectional study conducted in a Federal HospitaI Instituiton (maternity sector), integrated to Health Unified System of Goiânia – Goiás, from April 2011 to May 2012. The population consisted of 129 NB, among them 88 NB of high risk pregnancies women and 41NBwith no high-risk pregnancy women. The women clinical and anthropometric data of NB were obtained from the records of each patient, using the appropriate form. The HCL was performed using a rigid and transparent plastic ruler graduated in millimeters. Both feet were measured taking the hallux tip to the tip of the calcaneus-length. All data were typed and stored in an electronic database in Microsoft Office Excel ® 2007. Data were analyzed using the electronic program SigmaStat ® version 3.5. The participants’ rights were preserved according to the196/96 Resolution of the National Health Council. The project was approved by the Ethics in Human Research and Animal Hospital of the Federal University of Goiás, protocol n ° 101 / 2008. A statistically significant relationship was found between the HCL and the BW in NBS-GA, BGA and AGA for all gestational ages. The results showed a strong correlation between HCL and NB preterm and low correlation between HCL and NB post-term. The final average of HCL found in the high risk group is lower than the control group. However, NB with DIUG in the high risk group had lower weight and greater HCL than NB with HCL DIUG in the control group. The CHL was positively correlated with GA determined by both the LMP, as the method of Capurro. In relation to maternal factors, maternal age did not influence the NB birth with DIUG and did not show diffe-rences in HCL measures. Pre-eclampsia and gestational diabetes may be related to the lowest average of HCL among NB in high-risk group. A statistically significant relationship between CHL and CP and TP in the high risk group and between the CHL and the CP in the control group were found. The heterogeneity of results warns that cutoff points to identify LBW NBs and even premature or DIUG should only be used after it is established the HC Laverage considered as normal for the specific population in this research. / O CHC, utilizado na avaliação da IG e PN de RN normais e natimortos existe há quase um século e tem sido considerado como um método confiável na avaliação destes RN. Entretanto, ainda são escassos e inconsistentes os resultados dos estu-dos que buscaram esclarecer a relação dos dados mensurados pelo método em grupos de RN com DCIU. O objetivo deste estudo foi estimar a prevalência de RN/natimortos com DCIU, segundo o método do CHC e sua relação com a gestação de alto risco. Trata-se de um estudo descritivo transversal, desenvolvido em uma Instituição Hospitalar Federal (no setor maternidade), integrada ao Sistema Único de Saúde de Goiânia – Goiás, entre o período de abril de 2011 a maio de 2012. A popu-lação constituiu-se de 129 RN, desses, 88 desses, 88 desses, 88 desses, 88 desses, 88 desses, 88 desses, 88 desses, 88 RN de mulheres com gestde mulheres com gestde mulheres com gestde mulheres com gestde mulheres com gestde mulheres com gest de mulheres com gestde mulheres com gest de mulheres com gestde mulheres com gestde mulheres com gestde mulheres com gestde mulheres com gestde mulheres com gestde mulheres com gest ação de alto ção de alto ção de alto ção de alto ção de alto ção de alto ção de alto ção de alto ção de alto ção de alto risco e 41 risco e 41 risco e 41 risco e 41 risco e 41 risco e 41 risco e 41 risco e 41 RN de mulheres sem gestação alto riscode mulheres sem gestação de alto riscode mulheres sem gestação de alto risco de mulheres sem gestação alto riscode mulheres sem gestação de alto risco de mulheres sem gestação alto riscode mulheres sem gestação de alto risco de mulheres sem gestação alto risco de mulheres sem gestação alto riscode mulheres sem gestação de alto riscode mulheres sem gestação de alto riscode mulheres sem gestação de alto riscode mulheres sem gestação de alto riscode mulheres sem gestação de alto riscode mulheres sem gestação de alto riscode mulheres sem gestação de alto risco de mulheres sem gestação alto riscode mulheres sem gestação de alto riscode mulheres sem gestação de alto riscode mulheres sem gestação de alto riscode mulheres sem gestação de alto risco de mulheres sem gestação alto risco de mulheres sem gestação alto riscode mulheres sem gestação de alto risco de mulheres sem gestação alto risco . Os dados clínicos das mulhe-res, e os dados antropométricos e clínicos dos RN foram obtidos nos prontuários de cada paciente, por meio de formulário próprio. A medida do CHC foi realizada utili-zando-se régua plástica transparente e rígida, graduada em milímetros. Foram me-didos ambos os pés, adotando-se o comprimento da ponta do hálux até a extremi-dade do calcâneo. Todos os dados foram digitados e armazenados em um banco eletrônico no programa Microsoft Office Excel® 2007. As informações foram analisa-das através do programa eletrônico SigmaStat ® versão 3.5. Foram preservados os direitos dos participantes, conforme prevê a Resolução 196/96, do Conselho Nacio-nal de Saúde. O projeto foi aprovado pelo Comitê de Ética em Pesquisa Humana e Animal do Hospital das Clínicas da Universidade Federal de Goiás, sob protocolo n° 101/2008. Foi encontrada uma relação estatisticamente significante entre o CHC e o PN em RN PIG, GIG e AIG de todas as IG. Os resultados apresentaram forte corre-lação entre CHC e RN pretermo e baixa correlação entre o CHC e RN pós-termo. A média final do CHC encontrada no grupo de alto risco é inferior à encontrada no grupo controle. No entanto, os RN com DCIU pertencentes ao grupo de alto risco apresentaram menor peso e maior CHC que os RN com DCIU do grupo controle. O CHC se correlacionou positivamente com a IG determinada tanto pela DUM, quanto pelo método de Capurro. Em relação aos fatores maternos, a idade materna não influenciou no nascimento de RN com DCIU e não apresentou correlação com as medidas alteradas do CHC. A ocorrência de pré-eclâmpsia e o diabetes gestacional podem estar relacionada à menor média do CHC entre os RN do grupo de alto risco. Foi encontrada uma relação estatisticamente significante entre o CHC e os PC e PT no grupo de alto risco e entre o CHC e o PC no grupo controle. A heterogeneidade dos resultados alerta que pontos de corte para identificar RN BPN e até mesmo prematuros ou com DCIU só deveriam ser utilizados após ser estabelecida a média do CHC aceita como normal para a população específica adotada na pesquisa.
5

Ontogeny and functional adaptation of trabecular bone in the human foot

Saers, Jacobus Petrus Paulus January 2017 (has links)
Trabecular bone forms the internal scaffolding of most bones, and consists of a microscopic lattice-like structure of interconnected bony struts. Experimental work has demonstrated that trabecular bone adapts its structural rigidity and orientation in response to the strains placed upon the skeleton during life, a concept popularly known as “Wolff’s Law” or “bone functional adaptation”. Anthropological work has focused on correlating variation in primate trabecular bone to locomotor and masticatory function, to provide a context for the interpretation of fossil morphology. However, intraspecies variation and its underlying mechanisms are still poorly understood. In this thesis, variation in trabecular bone structure is examined in the human foot in four archaeological populations. The aim is to tease apart the factors underlying variation in human trabecular microstructure to determine whether it may be a suitable proxy for inferring terrestrial mobility in past populations. μCT scanning is used to image the three-dimensional trabecular structure of the talus, calcaneus, and first metatarsal in samples from four archaeological populations. Trabecular structure is quantified in seventeen volumes of interest placed throughout the foot. Trabecular bone is influenced by a variety of factors including body mass, age, diet, temperature, genetics, sex, and mechanical loading. Before trabecular structure can be used to infer habitual behaviour, the effects of these factors need to be understood and ideally statistically accounted for. Therefore, the effects of variation in bone size and shape, body mass, age, and sex on human trabecular structure are examined in four populations. Significant effects of body mass and age are reported, but little sexual dimorphism was found within populations. Taking these results into account, variation in trabecular structure is compared between archaeological populations that were divided into high and low mobility categories. Results demonstrate that the four populations show similar patterns of trabecular variation throughout the foot, with a signal of terrestrial mobility level superimposed upon it. Terrestrial mobility is associated with greater bone volume fraction and thicker, more widely spaced, and less interconnected trabeculae. Ontogeny of trabecular bone in the human calcaneus is investigated in two archaeological populations in the final chapter of the thesis. Results indicate that calcaneal trabecular bone adapts predictably to changes in loading associated with phases of gait maturation and increases in body mass. This opens the possibility of using trabecular structure to serve as a proxy of neuromuscular development in juvenile hominins. This work demonstrates that trabecular bone may serve as a useful proxy of habitual behaviour in hominin fossils and past populations when all contributing factors are carefully considered and ideally statistically controlled for.

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