Thesis (M.S.)--University of Michigan, 1956.

No description available.

No description available.

A seven segment model of the right leg and foot was developed with segments: thigh, lower leg, talus, hindfoot, midfoot and lateral and medial forefoot. Three-dimensional mapping of internal structures was made from CT scans and anatomical photographs (Visible Human Project). Twelve healthy subjects performed level walking and medial walking turns at slow, preferred and fast speed. Equilibrium about the two joints of the ankle complex (ankle and subtalar), was solved using Muscle Model Assisted Optimisation (MMAO). A three component, Hill-type muscle model determined tensions in eight muscles of the lower leg using EMG. Linear optimisation then corrected muscle tensions and solved for ligament tensions and articular surface compression. MMAO was successful in modeling ankle complex equilibrium during walking and walking turn. External forces acting on the right foot were similar for all subjects. Despite similar external loading, subjects employed different muscle tension strategies to produce equilibrium about the ankle and subtalar joints. For all subjects, triceps surae muscle tensions were largest. Peak tension in achilles tendon was 7.9xBW during walking and 8.0xBW during walking turn. The two heads of gastrocnernius behaved as distinct muscles performing different roles during stance. Peroneus brevis produced movement about the subtalar joint while peroneus longus had a stabilising role. The dorsi-flexors were significantly active during stance phase, antagonistic to triceps surae muscle group. This antagonism has not been predicted by previous models. Ligaments acted in an all-or-nothing manner when constraining the ankle complex. Ligaments were either slack or tensed at constant tension. Maximum ligament tension was 1.75xBW in the lateral ligaments of the ankle joint during walking turn. No difference between the walking and walking turn was seen in compressive loading of articular surfaces. Maximum compression of ankle joint was 10.0xBW and of subtalar joint was 8.0xBW.

Made available in DSpace on 2014-06-11T19:31:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2001Bitstream added on 2014-06-13T19:01:25Z : No. of bitstreams: 1 silvares_pra_dr_botfm.pdf: 1865578 bytes, checksum: 5944bbb134ed809f3f7170ccdbc6a33a (MD5) / Com o objetivo de se comparar as propriedades mecânicas do ligamento cruzado anterior (LCA), dos 10 mm do terço central do ligamento da patela (LP), e do tendão do músculo semitendíneo triplicado (STT) do mesmo doador, foram realizados ensaios de tração em material obtido de 19 cadáveres humanos. A idade dos doadores foi de 40 11 anos (18-55 anos), sendo 15 (78,9%) masculinos e 4 (21,1%) femininos, 12 brancos (63,1%) e sete negros (36,9%); 10 (52,6%) joelhos do lado esquerdo e 9 (47,4%) do lado direito. Foi obtida a área de secção dos corpos de prova para que, além das propriedades estruturais, também fossem avaliadas as propriedades materiais. Além do diagrama carga-alongamento, foram estudadas as seguintes variáveis: carga máxima (N), alongamento absoluto (mm) e específico (%) na ruptura, limite de proporcionalidade (N) e respectivos alongamentos, tensão na carga máxima(MPa), módulo de elasticidade (MPa), energia na ruptura (Nm) e energia por área (Nm/m2) . A análise estatística comparativa entre os três materiais mostrou que o LP foi superior ao LCA e ao STT, na carga máxima, tensão na carga máxima, módulo de elasticidade, energia, energia por área e limite de proporcionalidade, caracterizando comportamento de maior estabilidade e rigidez. O LCA e STT apresentaram semelhança com relação à carga máxima, tensão na carga máxima, limite de proporcionalidade e módulo de elasticidade. No STT observou-se valor maior em comparação ao LCA para energia e energia por área, na carga máxima. O STT alongou-se mais que o LCA e LP na ruptura e no limite de proporcionalidade. Não houve associação entre idade e carga máxima, tensão, energia e módulo de elasticidade no LCA, LP e STT. Houve associação entre carga máxima e área de secção no LCA e STT. Concluiu-se que o LP e STT têm comportamento mecânico distinto e que o perfil de ambos justifica a utilização como substitutos do LCA. / The material obtained from 19 human cadavers was submitted to traction-testing with the purpose of comparing the mechanical properties of the 10mm-central third of the patellar ligament (PL), triplicate semitendinosus muscle (TSM) and anterior cruciate ligament (ACL). Mean donor age was 40 11 years; 12 whites (63.1%) and 7 blacks (36.9%); 10 (52.6%) left knees and 9 (47.4%) right knees. The cross-sectional area of the test specimens was obtained so that, besides structural properties, material properties could also be evaluated. In addition to the load-strain diagram, the following variables were studied: ultimate load (N), absolute strain (mm) and relative strain (%) at failure load, yield point (N) and its respective strains, stress at ultimate load (MPa), modulus of elasticity (MPa), energy at failure (Nm) and energy per area (Nm/m2). Comparative statistical analysis of the materials revealed that PL was superior to ACL and TSM in ultimate load, stress at ultimate load, modulus of elasticity, energy, energy per area and yield point, thus featuring a behavior of greater stability and rigidity. ACL and TSM showed similar ultimate load, stress at ultimate load, yield point and modulus of elasticity. In TSM, energy and energy per area at ultimate load were higher than in ACL. Strain was greater in TSM than in ACL and PL at failure load and yield point. No association was observed between age and ultimate load, stress, energy and modulus of elasticity in ACL, PL and TSM. Ultimate load and cross-sectional area are associated in ACL and TSM. In conclusion, PL and TSM present distinct mechanical behaviors and their profiles justify their use as ACL replacements.

Mechanical stress has been shown to play a role in bone remodelling during orthodontic tooth movement. Receptor activator of nuclear factor kβ - ligand (RANKL), osteoprotegerin (OPG), monocyte colony stimulating factor (M-CSF) and interleukin 1-β (IL-1β) play key roles in the regulation of bone remodelling, but the role of these cytokines in orthodontic tooth movement is poorly understood. Aim: The aim of this experiment was to examine the response of periodontal ligament (PDL) fibroblasts in monolayer culture to intermittent tensile stress as regards RANKL, OPG, M-CSF and IL-1β production. Methods: Human PDL fibroblasts were dissected from premolars extracted for orthodontic purposes. Explants were seeded out in 1cm wells and grown to confluence in Dulbecco�s modification of Eagle�s medium, containing 10% foetal calf serum and antibiotics, at 37�C in a humidified atmosphere of 5% CO₂/95% air. Upon reaching confluence, the cells were passaged into sequentially larger flasks. Fibroblasts were passaged 6 times. After reaching confluence in T175 flasks, the cells were detached and plated at a cell density of 10⁵/dish in 35mm Bioflex� Plates coated with type 1 collagen. The cells were placed under a continuous uni-axial strain of 12% for 6s of every 90s by a Flexercell FX 4000C[TM] for 0, 12, 24 and 48 hours. Cells were then detached and stored in RNAlater. Quantitative RT-PCR was used to determine the mRNA of the cytokines of interest. Results: Tensile force led to the down regulation of mRNA expression for OPG and IL-1β at 12 and 24 hours respectively, while M-CSF was up-regulated at 6 hours. RANKL was not detected at a significant level for quantification. Conclusion: This osteoclastic-type response indicates the complexity of mechanotransduction in an in vitro setting. Acknowledgments: This research was supported by the New Zealand Dental Research Foundation, the New Zealand Lottery Grants Board and the New Zealand Association of Orthodontists.

Surgical operations and processing of natural product require accurate presentation of the target area in order to achieve precise incisions. An excellent example is the deboning automation for chicken breast meat, for which the pose of the wing can greatly affect the cutting efficiency, ability to fix the structure, and product yield. In contrast to engineering objects, biological products present difficulties such as variation in size, shape, and material properties. Unlike past research, which generally found ways to emulate the manual cutting motion, this thesis investigates the effects of wing manipulation on incision tasks. The objective of this thesis is to develop an analytical model for characterizing the manipulation for pose presentation of a musculoskeletal structure for a specified incision. The manipulation model consists of joint kinematics, the mechanics of bio-materials, and a grasping mechanism to determine the joint pose and forces for a given manipulation trajectory. The model provides a basis for monitoring the cutting of bio-material via non-visual information, as well as for design of a compliant mechanism that can be used in an industrial automation application. To gain a better understanding, a wing manipulation test-bed consisting of a force/torque sensor at the point of wing manipulation has been developed. Two specific examples are investigated. The first is needle insertion into bio-materials, and the other is the shoulder cutting operation associated with chicken breast meat deboning. The effects of manipulation on needle insertion forces are used to quantify improvements in insertion point accuracy and required insertion force. Force signatures are also developed for insertion into the biomaterials located within the shoulder joint. The information gathered from both the manipulation model and needle insertion experiments provide a basis for successful implementation of the automation of the shoulder cut. While the experimentation presented in this thesis is developed in the context of poultry processing, which has immediate contributions as a tool that would facilitate the design of the automated cutting mechanisms in poultry industry, we expect that the development of the models will find a broad range of applications ranging from general meat processing, to surgical simulation, and physical therapy.

Thèse d'exercice : Médecine. Rhumatologie : Université de Nantes : 2004. / Bibliogr. f. 113-121 [121 réf.].

Thesis--PlanB (M.S.)--University of Wisconsin--Stout, 2000. / Includes bibliographical references.

A methodology for ligament isolation and specimen preparation for tensile testing of single ligaments from the unit cell of open-cell carbon foams has been successfully developed and implemented. Results are presented for ligaments of three different carbon foam designations. Two of them are reticulated vitreous carbon (RVC) foams of 20 and 45 pores-per- inch (ppi) coated with SiC by chemical vapor deposition (CVD) and the other is a RVC 20 ppi foam without coating. Scanning electron microscopy and digital imaging analysis is used to analyze the fracture surfaces posts tests. The ultimate strength of each ligament evaluated. Weibull statistics is used to describe the strength distribution of ligaments. While the distribution of strengths of the carbon foam ligaments (RVC) could be described with a one-population distribution, it is found that a two-population Weibull distribution is necessary to describe the distribution of strength of the SiC coated ligaments.