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1
Ramsey, Glenn. "Equine hoof biomechanics". Thesis, University of Auckland, 2011. http://hdl.handle.net/2292/11469.
Testo completoAbstract (sommario):
The biomechanics of the equine hoof are not well understood. Therefore biomechanical models of the hoof were developed, using finite element analysis and finite deformation elasticity, to provide a means of analysing the mechanisms underlying hoof function and dysfunction. One goal of the research was to investigate the biomechanical effects of different hoof shapes. A parametric geometry model that could be configured to represent commonly observed variations in hoof shape was developed for this purpose. Tissue behaviour models, accounting for aspects of the nonlinearity, inhomogeneity due to a moisture gradient and anisotropy of the tissues, were developed and configured using data from the literature. A method for applying joint moment loads was incorporated into the model to allow the direct use of published hoof load data. These aspects of the model were improvements over previously published hoof models. Both hoof capsule deflections and stored elastic energy were predicted to be increased by increased moisture content and by caudal movement of the centre of pressure of the ground reaction force. These results confirm that hoof deflections may play an important role in attenuating potentially damaging load impulse energy and support the geometry hypothesis to explain the mechanism by which the hoof expands under load. Further analyses provided insights into aspects of hoof mechanics that challenge conventional beliefs. The model predicts that load in the dorsal lamellar tissue is increased, rather than decreased, when hoof angle is increased. Simulations of different ground surface shapes indicate that hoof deformability and not ground deformability, may be responsible for the concave quarter relief observed in naturally worn hooves. A hypothesis is proposed for the mechanism by which heel contraction occurs and implicates heel unloading due to bending of the caudal hoof capsule and contraction under load bearing of the caudal coronet as probable causes. Biomechanical analyses of this kind enable improved understanding of hoof function, and a rational, objective basis for comparing the efficacy of different therapeutic strategies designed to address hoof dysfunction.
2
Yousefi, Koupaei Atieh. "Biomechanical Interaction Between Fluid Flow and Biomaterials: Applications in Cardiovascular and Ocular Biomechanics". The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1595335168435434.
Testo completo
3
Halliday, Suzanne Elizabeth. "Biomechanics of ergometer rowing". Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270367.
Testo completo
4
Jacob, Hilaire A. C. "Biomechanics of the forefoot". Thesis, University of Strathclyde, 1989. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21307.
Testo completoAbstract (sommario):
The work reported in this thesis was carried out to investigate the kinematic and dynamic behaviour of the forefoot during normal locomotion activities. An extensive literature review on the subject is presented and the need for further investigations shown. Fresh autopsy specimens were studied to determine the course taken by tendons in relation to the joints of the forefoot, and the topography of joint surfaces mapped. The overall geometries of the first and second rays have been described too. Also, an experimental investigation has shown that without muscular activity the metatarsal bones are mainly loaded in bending. Locomotion studies have shown that the average peak ground forces under the pad of the great toe, the head of the 1st metatarsal, the pad of the 2nd toe, the head of the 2nd metatarsal and the head of the 5th metatarsal measure about 30% body weight (BW), 15% BW, 6% BW, 30% BW and 15% BW, respectively. Temporal graphs of these forces show their behaviour during the gait cycle. Furthermore, the magnitudes of these forces when wearing shoes-with stiff soles, when climbing up and down stairs, as well as when walking up and down a slope of 15° are reported. Based on the external forces measured, the internal forces acting along the flexor tendons and across joint surfaces of the 1st and 2nd rays during gait are estimated. The stresses that thereby develop in the shanks of the metatarsal bones indicate that the 1st metatarsal bone is subjected mainly to compression while the 2nd metatarsal bone is exposed to a high degree of bending. The relationship between the results of this study and clinical problems is considered and especially a hypothesis has been advanced to explain how under edge-loading conditions localised necrosis of the metatarsal heads could occur, thus giving rise to Koehler-Freiberg's disease.
5
Morrison, Andrew Paul. "Golf coaching biomechanics interface". Thesis, Ulster University, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.680144.
Testo completo
6
Holub, Ondrej. "Biomechanics of spinal metastases". Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7315/.
Testo completoAbstract (sommario):
The lack of suitable models for prediction of the vertebral body (VB) failure load for a variety of pathologies hampers the development of indications for surgical and pharmaceutical interventions and the assessment of novel treatments. Similar models would also be of benefit in a laboratory environment in which predictions of failure load could aid experimental design when using cadaveric tissue. Finite element modelling shows great potential but the expertise required to effectively deploy this technology in a clinical environment precludes its routine use at the present time. Its deployment within the laboratory environment is also time consuming. An alternative approach may be the use of composite beam theory structural analysis that takes into account both vertebral geometry and the bone mineral density (BMD) distribution and they are utilised to predict the loads at which vertebrae will fail. As a part of this work, vertebrae suffering from three distinct pathologies (osteoporosis, multiple myeloma (MM) and metastases) were tested in a wedge compression loading protocol (WCF) as a determinant for vertebroplasty treatment. MM bone was first tested for changes at the bone tissue level by means of depth-sensing micro-indentation testing. In the second part more than one hundred VBs were subjected to a destructive in-vitro WCF experiment, while CT images were used for in-silico structural and morphological assessment. In the last part, two vertebroplasty cements, calcium phosphate and PMMA, were tested. At the tissue level MM bone shows rather moderate changes which are of such small magnitude that alone would not be sufficient to change the overall vertebral strength. Relatively good predictions of VB strength were obtained when using image-based fracture prediction suggesting that bone distribution and pathological alterations to its structure make a significant contribution to overall VB strength. The results of VB reinforcement using either of the cements show increased strength while stiffness was restored only when PMMA cement was injected in lower porosity samples.
7
Jang, Sae, Rebecca R. Vanderpool, Reza Avazmohammadi, Eugene Lapshin, Timothy N. Bachman, Michael Sacks e Marc A. Simon. "Biomechanical and Hemodynamic Measures of Right Ventricular Diastolic Function: Translating Tissue Biomechanics to Clinical Relevance". WILEY, 2017. http://hdl.handle.net/10150/626001.
Testo completoAbstract (sommario):
Background Right ventricular (RV) diastolic function has been associated with outcomes for patients with pulmonary hypertension; however, the relationship between biomechanics and hemodynamics in the right ventricle has not been studied. Methods and Results Rat models of RV pressure overload were obtained via pulmonary artery banding (PAB; control, n=7; PAB, n=5). At 3 weeks after banding, RV hemodynamics were measured using a conductance catheter. Biaxial mechanical properties of the RV free wall myocardium were obtained to extrapolate longitudinal and circumferential elastic modulus in low and high strain regions (E-1 and E-2, respectively). Hemodynamic analysis revealed significantly increased end-diastolic elastance (E-ed) in PAB (control: 55.1 mm Hg/mL [interquartile range: 44.785.4 mm Hg/mL]; PAB: 146.6 mm Hg/mL [interquartile range: 105.8155.0 mm Hg/mL]; P=0.010). Longitudinal E1 was increased in PAB (control: 7.2 kPa [interquartile range: 6.718.1 kPa]; PAB: 34.2 kPa [interquartile range: 18.144.6 kPa]; P=0.018), whereas there were no significant changes in longitudinal E-2 or circumferential E-1 and E-2. Last, wall stress was calculated from hemodynamic data by modeling the right ventricle as a sphere: (stress = Pressure x radius/2 x thickness Conclusions RV pressure overload in PAB rats resulted in an increase in diastolic myocardial stiffness reflected both hemodynamically, by an increase in E-ed, and biomechanically, by an increase in longitudinal E-1. Modest increases in tissue biomechanical stiffness are associated with large increases in E-ed. Hemodynamic measurements of RV diastolic function can be used to predict biomechanical changes in the myocardium.
8
Flick, Kevin Charles. "Biomechanics and dynamics of turning /". Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/5221.
Testo completo
9
Lee, Angela Wing Chung. "Breast image fusion using biomechanics". Thesis, University of Auckland, 2011. http://hdl.handle.net/2292/10277.
Testo completoAbstract (sommario):
Breast cancer is a leading cause of cancer mortality in women worldwide. Biophysical mathematical models of the breast have the potential to aid in the diagnosis and treatment of breast cancer. This thesis presents research on the development and validation of biomechanical models of the breast subject to gravity and compressive loads. The finite element method was used to implement the theory of finite elasticity coupled with contact mechanics in order to simulate the large non-linear deformations of the breast tissues. Initially, validation studies were conducted using a breast phantom, which was placed in different orientations with respect to the gravity loading and compressed using a custom made device. A novel application of a block matching image processing method was used to quantitatively assess the accuracy of the biomechanics predictions throughout the entire phantom. In this way, systematic changes to the assumptions, parameters, and boundary constraints of the breast models could be quantitatively assessed and compared. Using contact mechanics to model the interactions between the ribs and breasts can improve the accuracy of simulating prone to supine deformations due to the relative sliding of the tissues, as was observed using MRI studies on volunteers. In addition, an optimisation framework was used to estimate the heterogeneous mechanical parameters of the breast tissues, and the improvements to the models were quantified using the block matching comparison method. A novel multimodality framework was developed and validated using MR and X-ray images of the breast phantom before being applied to clinical breast images. Using this framework, it was shown that the parameters of the model (boundary conditions, mechanical properties) could be estimated and the image alignment improved. The biomechanical modelling framework presented in this thesis was shown to reliably simulate both prone to supine reorientation, and prone to mammographic compression, deformations. This capability has the potential to help breast radiologists interpret information from MR and X-ray mammography imaging in a common visualisation environment. In future, ultrasound imaging could also be incorporated into this modelling framework to aid clinicians in the diagnosis and management of breast cancer.
10
Heistand, Mark Richard. "Biomechanics of the lens capsule". Texas A&M University, 2004. http://hdl.handle.net/1969.1/2726.
Testo completoAbstract (sommario):
Knowledge of the mechanics of the lens capsule is crucial for improving cataract surgery as well as understanding better the physiological role of the lens capsule in the process of accommodation. Previous research on the mechanical properties of the lens capsule contains many gaps and contradictions due to experimental limitations and inappropriate assumptions. Thus, the goal of this work is to quantify fully the regional, multiaxial mechanical behavior of the lens capsule and to calculate the change in stress and strain fields as a result of cataract surgery.
Determining in situ the multiaxial mechanical behavior of the lens capsule required the design and construction of an experimental device capable of altering stresses in the capsule while measuring localized surface deformations. Tests performed on this device reveal that the meridional and circumferential strains align with the principal directions and are equivalent through most of the anterior lens capsule, except close to the equator where the meridional strain is greater. Furthermore, preconditioning effects were also found to be significant. Most importantly, however, these tests provide the data necessary for calculating material properties.
This experimental system is advantageous in that it allows reconstruction of 3D geometry of the lens capsule and thereby quantification of curvature changes, as well as measurement of surface deformations that result from various surgical interventions. For instance, a continuous circular capsulorhexis (CCC) is commonly used during cataract surgery to create a hole in the anterior lens capsule (typically with a diameter of 5 mm). After the introduction of a CCC, strain was found to redistribute evenly from the meridional direction (retractional strain) to the circumferential direction (extensional strain), where both directional components of strain reached magnitudes up to 20% near the edge of the CCC. Furthermore, the curvature was found to increase at the edge of the CCC and remain the same near the equator, indicating that the mere introduction of a hole in the lens capsule will alter the focal characteristics of the lens and must therefore be considered in the design of an accommodative intraocular lens.
11
Senavongse, Wongwit. "Biomechanics of the patellofemoral joint". Thesis, Imperial College London, 2002. http://hdl.handle.net/10044/1/7378.
Testo completo
12
Borse, Vishal Harish. "In-vitro biomechanics of vertebroplasty". Thesis, University of Leeds, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.713483.
Testo completoAbstract (sommario):
Osteoporotic vertebral compression fractures are a major burden worldwide. Percutaneous vertebroplasty is a recognised treatment option for these fractures but there is conflicting evidence regarding the optimum amount of cement to use and there is little evidence regarding the best surgical approach to treating these fractures. Newer techniques are available which expand on the basic premise of percutaneous vertebroplasty. This project aimed to provide the basic science to answer the questions of cement fill, approach and the use of modern adjuncts to traditional percutaneous vertebroplasty. The first phase looked at approaches and cement fill and found that a 30% fill via a unipedicular approach , gave the best biomechanical outcome combined with the lowest theoretical risk and that the interaction between the cement and the vertebral endplate was important for syength restoration. Phase 2 expanded on the work carried out earlier in this study and looked at the response to dynamic loading of augmented and unaugmented vertebra. It reinforced the findings of phase 1 that 30% was the key figure and the endplate-bolus interaction was key. Finally phase 3 took the work carried out in the study so far and compared cavity creation vertebroplasty using a contour osteotome with traditional balloon kyphoplasty in, a static loading environment. It demonstrated equivocal strength restoration between the two but with lower incidence of implant induced fracture in the contour group. The culmination of this project provides guidelines for the effective use of cement augmentation by percutaneous vertebroplasty as a method for restoring strength post vertebral fracture in osteoporotic patients.
13
Ferguson, Stephen John. "Biomechanics of the acetabular labrum". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0020/NQ54413.pdf.
Testo completo
14
Gratz, Kenneth R. "Biomechanics of articular cartilage defects". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3284116.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--University of California, San Diego, 2007.Title from first page of PDF file (viewed January 9, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
15
Stefanakis, Manos. "Biomechanics of intervertebral disc pain". Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556723.
Testo completoAbstract (sommario):
'Background: Back pain is strongly (but variably) associated with degeneration of intervertebral discs. Mechanical loading has long been considered one of the causes of disc pathology and pain, but its precise role is poorly understood. In particular the spatial relation between load distribution inside the disc, the disc matrix changes as a result of load and their relationship with pain has not been researched. Methods: Distribution of compressive stress inside intervertebral discs from all regions of the spine was studied using stress profilometry in cadaveric motion segments. Matrix pathological changes were studied using simple histology and light microscopy in two groups of surgically removed discs: 'painful' discs from patients undergoing surgery for suspected discogenic pain, and 'control' discs from patients undergoing surgery for scoliosis or spondylolisthesis reduction. Ingrowth of nerves and blood vessels into the annulus was studied by immunohistochemistry with an endothelial and a general neuronal marker. Stress reduction inside annulus fissures were investigated using stress profilometry. Proteoglycan reduction within annulus fissures was studied by means of a novel, semi-quantitative method involving simple histology and image analysis. Although semi-quantitative, the technique had great spatial resolution and allowed integration with the results from the mechanical experiments. Results: High stress concentrations were localised in the middle annulus and increased with disc degeneration. Associated stress gradients appeared early in the degeneration process and were not diminished in late stage degeneration when substantial compressive loading is transferred to the neural arch. Nerve and blood vessel ingrowth increased with degeneration, but were confined to the outermost 4mm of the annulus. Other cellular changes such as apoptosis, cellular infiltration and proliferation were mostly confined to the annulus. Annulus fissures were found to represent focal regions of low proteoglycan content, and also of low compressive stress, especially when the nucleus was also decompressed. Conclusions: Results suggest that high stress gradients play an important role in progressive annulus disruption, and that annulus fissures provide a microenvironment that is mechanically and chemically conducive to the ingrowth of nerves and blood vessels. Co-localisation of nerves, blood vessels and stress concentrations in the middle-outer annulus suggest that this is the most likely site of discogenic pain. Pain is associated with annulus disruption and the attempted healing rather than age-related degenerative changes in the nucleus.
16
Wolfson, David R. "Biomechanics of shaken baby syndrome". Thesis, University of Nottingham, 2007. http://eprints.nottingham.ac.uk/11217/.
Testo completoAbstract (sommario):
In the first part of this work, an Anthropometric Test Dummy (ATD) was used to obtain torso acceleration data for Shaken Baby Syndrome (SBS). These data were used to drive computational simulations of SBS, in studies of the effect of neck stiffness and head-torso impact on injury risk. Finally, physical models were used to investigate the strain induced in brain tissue during shaking. Clinical literature describes victims of Shaken Baby Syndrome (SBS) as young infants with life-threatening brain injuries, and poor long-term outcome. However, biomechanical studies using ATI)s to study head motion during shaking have been inconclusive about the capacity for shaking alone to cause these injuries 11,21. This work comprises a series of investigations into these conflicting findings. Torso acceleration data for SBS, obtained using a specially constructed ATD, were found to be consistent with previous findings. The data were used to simulate shaking in computational studies of SBS, using Rigid Body Models (RBM) of the infant head and neck. Parametric studies were used to investigate the importance of neck stiffness in assessing the injury capacity of SBS, and showed that in order to exceed current injury criteria for SBS, impact was required. Head torso impact was then simulated, and although this resulted in higher injury risk than shaking alone, criteria for injuries associated with SBS were not reached. Since these investigations did not predict brain injury in cases of SBS without impact, the origins of injury criteria were reviewed. It was found that they are derived from single high energy events, which is distinct from the type of motion in SBS. In order to establish if cyclic, low-energy motion contributes to brain injury in SBS, Physical Continuum Modelling was used to study strain in brain tissue during shaking. A test rig was constructed to shake silicone gel models, and high-speed video used to capture the motion of optical markers with in the gel. Their movement was tracked using optical flow methods, and Green-Lagrangian strain derived by tensor algebra. No evidence was found to indicate a build up in strain between cycles, but published critical strains for damage to neural tissue were exceeded. Although shaking alone was not found not induce head motion in excess of brain injury criteria, tissue damage criteria were exceeded. The application of current brain injury criteria to SBS maybe therefore be inappropriate.
17
O'Callaghan, P. T. "The biomechanics of stab wounds". Thesis, Cardiff University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411710.
Testo completo
18
Prévost, Thibault Philippe. "Biomechanics of the human chorioamnion". Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36217.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2006.Includes bibliographical references (leaves 108-115).
The human fetal membrane, namely the chorioamnion, is the structural soft tissue retaining the amniotic fluid and the fetus during pregnancy. Its biomechanical integrity is crucial for maintaining a healthy gestation and a successful delivery. The premature rupture of the fetal membrane (PROM) can result in serious perinatal complications. Despite extensive research in this field, the mechanical and biochemical processes governing the membrane deformation and failure remain poorly understood. The aim of this study is to characterize the mechanical behavior of the chorioamnionic tissue along with its biochemical properties, through mechanical testing and biochemical analyses. In order to accomplish this goal, specific mechanical and biochemical testing protocols were developed. In vitro mechanical testing was performed on samples from seven patients under different uniaxial and biaxial loading conditions. Significant relaxation was noted under uniaxial loading while very limited creep was observed under biaxial loading. Biochemical measurements such as collagen and sulfated glycosaminoglycan contents were also obtained. In addition, a microstructurally based constitutive model for the fetal membrane is proposed.
(cont.) The model allows for nonlinear hyperelastic response at large deformation. We also propose a framework to capture the time-dependent response of the tissue. The model was implemented in a finite element formulation to allow three-dimensional simulations of membrane deformation.
by Thibault Philippe Prévost.
S.M.
19
Przybyla, Andrzej Stefan. "Biomechanics of the cervical spine". Thesis, University of Bristol, 2005. http://hdl.handle.net/1983/845f95ee-39dd-4418-b6ed-200d749f87ae.
Testo completo
20
Vaughan, Christopher Leonard (Kit). "The biomechanics of human locomotion". Doctoral thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/3491.
Testo completoAbstract (sommario):
Includes bibliographical references.
The thesis on CD-ROM includes Animate, GaitBib, GaitBook and GaitLab, four quick time movies which focus on the functional understanding of human gait. The CD-ROM is available at the Health Sciences Library.
21
Gabra, Joseph Nageh. "Biomechanics of the Carpal Arch". Cleveland State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=csu1440155265.
Testo completo
22
Button, David John. "Cranial biomechanics of sauropodomorph dinosaurs". Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.690772.
Testo completoAbstract (sommario):
The Sauropodomorpha represented a globally important clade of Mesozoic herbivores and included the largest terrestrial animals known to science. This makes them of great interest in understanding the fundamental constraints acting upon terrestrial life and the evolution of gigantism. However, sauropodomorph biology presents many problems, not least how they secured sufficient food intake to fuel their massive bodies. Herein, a combination of morphological description, 3D reconstruction of osteology and myology, biomechanical modelling, multivariate analysis and evolutionary modelling was performed in order to investigate the sauropodomorph feeding apparatus in more detail. This integrated approach pennitted intenogation of hypotheses that have linked the diversification and gigantism of sauropodomorphs with the evolution of herbivory in the clade. Results demonstrate that basal ('prosauropod') taxa are characterized by relatively gracile and mechanically inefficient skulls and mandibles, but are also highly disparatepotentially relating to variation along the omnivorylherbivory spectrum. A prominent functional shift towards increased cranial robusticity and jaw processing power is observed at the base of Sauropoda, coincident with the attainment of very large body size. This is consistent with a shift towards bulk-herb ivory, providing quantitative evidence for the hypothesised role of such an ecological shift as a driver of sauropodomorph gigantism. Shifts towards novel functional morphologies are also observed in some derived sauropod lineages. Although some similarities are acquired convergently by the derived diplodocoids and titanosaurs each clade remains highly disparate and they cannot be stereotyped as confonning to a common functional 'grade'. The high disparity present in sauropod craniodental systems would have suppOlied dietary niche partitioning between sympatric taxa. Still, despite these functional shifts overall disparity does not increase through the Mesozoic. Similarly, sauropodomorphs do not reoccupy small body sizes after the extinction of 'prosauropod' taxa, suggesting constraint to larger sizes as a result of specialisations of the sauropod bauplan towards gigantism.
23
Ramier, James Charles. "Biomechanics of corneal wound healing /". Online version of thesis, 1992. http://hdl.handle.net/1850/10786.
Testo completo
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Lam, Garret Chi Yan. "Biomechanics of orthodontic tooth movement /". View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?MECH%202003%20LAM.
Testo completoAbstract (sommario):
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003.Includes bibliographical references (leaves 118-122). Also available in electronic version. Access restricted to campus users.
25
Brandolini, Nicola. "Experimental biomechanics of vertebral fractures". Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/11339/.
Testo completoAbstract (sommario):
Vertebral fractures are a severe cause of morbidity and disability. In particular, burst fractures are a common traumatic injury presenting neurological impairment in 47 % of cases. However, diagnosis and planning of the treatment is challenging as the injury originates in highly dynamic conditions. Short-segment pedicle instrumentation (SSPI) in combination with kyphoplasty (SSPI–KP) has been used to provide additional stabilisation of the fracture. However, there is a lack of understanding about the effectiveness SSPI–KP. The aim of this study was to follow the fracture pathway, from onset to the outcome of surgical treatment. The first part focused on the phenomena underlying fracture creation and the dynamics of interpedicular widening (IPW). Although associated with neurological deficit, no previous study has shown how IPW evolves at fracture initiation. Subsequently the performance of treatment was assessed to evaluate how KP can improve SSPI to a simulated early follow-up. Burst fractures were induced in 12 human three-adjacent-vertebrae segments. Following fracture investigation, SSPI and SSPI–KP were performed, and samples underwent fatigue loading. Image processing of high-resolution CT scans was performed to assess anatomical changes at consecutive experimental stages on the treated and adjacent vertebrae. Experiments proved that IPW reaches a maximum at fracture onset and then decreases to the value measured clinically. SSPI–KP marginally improved stability of the treated spine, whilst providing a significant restoration of the endplate geometry. Vertebral body underwent significant changes in height and endplate curvature throughout the fracture pathway. This study provided further insight on the biomechanics of vertebral fractures and the findings can be used to improve and/or develop novel treatments as well as validate numerical models for retrospective assessment of the injury. In addition, outcomes from the collaboration work on the development of a computational simulation may help better understand cancer related vertebral fractures.
26
Low, Christopher John. "Biomechanics of rock climbing technique". Thesis, University of Leeds, 2005. http://etheses.whiterose.ac.uk/5391/.
Testo completoAbstract (sommario):
Rock climbing routes have become increasingly difficult over the last twenty years. In rock climbing manuals and articles, specific techniques for making arm movements on steep, overhanging routes are suggested as offering the climber noticeable performance benefits. The techniques recommended generally depend on the orientation of the ipsilateral foot. Decisions on technique are important, as the results are cumulative and can impact on the overall performance of the climber on the route. The overall purpose of this research is to evaluate the impact of different ipsilateral foot orientations on reaching tasks in overhanging rock climbing situations. As the research base for technique analysis is limited in rock climbing, a qualitative study was initially conducted to confirm the existence of the different techniques and to provide a base from which to ascertain the performance variables for technique comparison. Comparison Study 1 involved a 3D kinematic study, modelling the climber as a 14-segment rigid body model, comparing the techniques in terms of centre of mass displacement and velocity as well as joint angular changes. Comparison Study 2 compared the techniques in terms of the identified performance measures of postural demand, trajectory efficiency and work/power. Statistically significant differences were found in centre of mass characteristics and body geometry, with differing orientations of the ipsilateral foot. Variations in complexity and in strategies of joint angular change were demonstrated, but the coordination in the reaching arm and the final arm posture were found to be invariant with technique. The postural demands within each technique varied significantly, however, in terms of trajectory efficiency and bioenergetics; differences between the techniques were small. The overall conclusion was that, although reaching arm movements are not affected by foot orientation, the overall technique and performance of a reaching task is. The study has practical and theoretical implications for rock climbing as well as for theories of grasping.
27
Espinoza, Victor. "Gesture Recognition in Tennis Biomechanics". Master's thesis, Temple University Libraries, 2018. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/530096.
Testo completoAbstract (sommario):
Electrical and Computer EngineeringM.S.E.E.
The purpose of this study is to create a gesture recognition system that interprets motion capture data of a tennis player to determine which biomechanical aspects of a tennis swing best correlate to a swing efficacy. For our learning set this work aimed to record 50 tennis athletes of similar competency with the Microsoft Kinect performing standard tennis swings in the presence of different targets. With the acquired data we extracted biomechanical features that hypothetically correlated to ball trajectory using proper technique and tested them as sequential inputs to our designed classifiers. This work implements deep learning algorithms as variable-length sequence classifiers, recurrent neural networks (RNN), to predict tennis ball trajectory. In attempt to learn temporal dependencies within a tennis swing, we implemented gate-augmented RNNs. This study compared the RNN to two gated models; gated recurrent units (GRU), and long short-term memory (LSTM) units. We observed similar classification performance across models while the gated-methods reached convergence twice as fast as the baseline RNN. The results displayed 1.2 entropy loss and 50 % classification accuracy indicating that the hypothesized biomechanical features were loosely correlated to swing efficacy or that they were not accurately depicted by the sensor
Temple University--Theses
28
Rafi, Murtaza. "Biomechanics of AAA surveillance patients". Thesis, KTH, Hållfasthetslära (Inst.), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-264765.
Testo completoAbstract (sommario):
Abdominal aortic aneurysms (AAA) occurs due to local enlargement of the abdominal aorta and affects about 1-2 % of the elderly Swedish population. At admission, AAA patients receive a Computed Tomography-Angiography (CT-A) scanning, and later they are followed-up by 2D ultrasound examinations. There is a need to know if an adequate geometry can be constructed from the baseline CT-A scan and follow-up 2D ultrasounds. To test our hypothesis only CT-A images have been used from six patients and hypothetical ultrasound cross-sections (HUCS) were extracted from the follow-up CT-A scans. The baseline AAA surface was expanded in a mechanical model by applying pressure inside of it until it reached the HUCS. The obtained morphed geometries were then compared with the CT-A-based geometries. The discrepancy between them were calculated by distance measurements. Also, the rupture risk indicators volumes and stresses were compared. Finally, a sensitivity analysis studied the effect of HUCS positioning on the volumes and stresses. The results show that an adequate geometry can be constructed by the investigated concept of morphing. The average distances between the morphed and CT-A-based geometries are 2-4 mm. The average volume difference for the six patients are between 3.8-16.2 %. The wall stress for the morphed and CT-A-based geometries are close only for the first follow-up.Bukaortaaneurysm (AAA) uppstår på grund av lokal förstoring av bukaortan och drabbar 1-2 % av den äldre svenska befolkningen. Vid antagning får bukaortaaneurysm-patienterna en datortomografscanning (CT-A) och senare påföljs av 2D ultraljudsscanningar. Det finns ett behov att veta om en adekvat geometri kan konstrueras från datortomografiscanningen och 2D ultraljudsbilderna. För att testa vår hypotes har endast datortomografibilder från sex patienter använts med hypotetiska ultraljudstvärsnitt (HUCS) tagna från CT-A uppföljningarna. AAA-ytan vid baslinjen expanderades i en strukturmekanisk modell genom inre övertryck tills den nådde de hypotetiska ultraljudstvärsnitten. Därefter jämfördes de morfade geometrierna med de CT-A-baserade geometrierna. Geometriavvikelsen mellan de beräknades genom avståndsmätningar. Även, rupturriskindikatorerna volymer och spänningar jämfördes. Slutligen, genom en känslighetsanalys undersöktes effekten av positioneringen av hypotetiska ultraljudstvärsnitten på volymerna och spänningarna. Resultaten visar att en adekvat geometri kan konstrueras genom den undersökta koncepten av morfning. De genomsnittliga avstånden mellan de morfade och CT-A-baserade geometrierna är 2-4 mm. Genomsnittliga volymskillnaderna för de sex patienterna är mellan 3.8-16.2 %. Väggspänningarna för de morfade och CT-A-baserade geometrierna är nära enbart för den första uppföljningen.
29
Orekhov, Greg. "Hip and Knee Biomechanics for Transtibial Amputees in Gait, Cycling, and Elliptical Training". DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/2010.
Testo completoAbstract (sommario):
Transtibial amputees are at increased risk of contralateral hip and knee joint osteoarthritis, likely due to abnormal biomechanics. Biomechanical challenges exist for transtibial amputees in gait and cycling; particularly, asymmetry in ground/pedal reaction forces and joint kinetics is well documented and state-of-the-art passive and powered prostheses do not fully restore natural biomechanics. Elliptical training has not been studied as a potential exercise for rehabilitation, nor have any studies been published that compare joint kinematics and kinetics and ground/pedal reaction forces for the same group of transtibial amputees in gait, cycling, and elliptical training. The hypothesis was that hip and knee joint kinematics and kinetics and ground and pedal reaction forces would differ due to exercise (gait, cycling, elliptical) amputee status (amputated, control [non-amputated]), and leg (dominant [intact], non-dominant [amputated]). Ten unilateral transtibial amputees and ten control participants performed the three exercises while kinematic and kinetic data were collected. Hip and knee joint flexion angle, resultant forces, and resultant moments were calculated by inverse dynamics for the dominant and non-dominant legs of both participant groups. Joint biomechanics and measured ground/pedal reaction forces were then compared between exercises, between the dominant and non-dominant legs within each participant group, and across participant groups. Significant differences in hip and knee joint flexion angles and timing, compressive forces, extension-flexion (EF) and adduction-abduction (AddAbd) moments, and anterior-posterior (AP) and lateral-medial (LM) reaction forces were found. Particularly, transtibial amputees showed maximum knee flexion angle asymmetry as compared to controls in all three exercises. Maximum hip and knee compressive forces, EF moments, and AddAbd moments were lowest in cycling and highest in gait. Asymmetry in amputee midstance knee flexion and timing in v gait, coupled with low maximum EF moment for the non-dominant leg, suggests that amputees avoid contraction of the non-dominant quadriceps muscle. Knee flexion angle and EF moment asymmetry in elliptical training suggests that a similar phenomenon occurs. Asymmetry in AP and LM reaction forces in gait, but not other exercises, suggests that exercises that constrain kinematics reduce loading imbalances. The results suggest that cycling and elliptical training should be recommended to transtibial amputees for rehabilitation due to reduced hip and knee joint forces and moments. Elliptical training may be preferred over gait due to decreased joint loading and loading asymmetry, but some asymmetry and differences from control participants still exist. Non-weight bearing exercises such as cycling may be best at reducing overall joint loading and joint load asymmetry but do not eliminate all kinematic and temporal asymmetries. Current state-of-the-art prosthetic leg design is insufficient in restoring natural biomechanics not only in gait but also in cycling and elliptical training. Improved prosthesis kinematics that restore non-dominant knee flexion in amputees to normal levels could help reprogram quadriceps muscle patterns in gait and elliptical training and hip and knee joint biomechanical asymmetries. Further work in comparing contralateral and prosthesis ankle joint biomechanics would help to elucidate the relationship between prosthesis design and its impact on lower limb joint biomechanics.
30
Bucci, Francesca. "Personalized biomechanical model of a patient with severe hip osteoarthritis for the prediction of pelvic biomechanics". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15879/.
Testo completoAbstract (sommario):
L’articolazione dell'anca è un'articolazione sinoviale sferica che costituisce la connessione primaria tra gli arti inferiori e lo scheletro della parte superiore del corpo. Durante le attività quotidiane di routine, carichi anormali ripetuti sull'anca possono portare alla danneggiamento della cartilagine articolare e conseguentemente , all’osteoartrite (OA).
L'OA dell'anca è una condizione muscolo-scheletrica cronica e progressiva, il cui trattamento per i pazienti severi è l'artroplastica totale dell'anca (THA). Il centro dell'articolazione dell'anca (HJC) ha grande importanza nell’analisi della biomeccanica dell’anca, così come il suo spostamento, che puo’ essere dovuto a patologie, come OA, o alla chirurgia, THA.
Per valutare la biomeccanica del bacino in questa tesi sono stati implementati un modello muscoloscheletrico (NMS) personalizzato statistical shape e modelli ad elementi finiti (FE) di un paziente con grave OA mono-laterale dell'anca.
Viene discussa l'accuratezza relativamente al modello scalato generico nella predizione delle grandezze biomeccaniche piu’ importanti, durante la deambulazione.
Attraverso i modelli FE, è stato studiato l'effetto di una cattiva stima e/o dello spostamento del centro dell'articolazione dell'anca nelle direzioni antero-posteriore, mediolaterale o infero-superiore per valutare lo stato di sollecitazione della pelvi.
Infine sono presentati i risultati di un approccio multiscala integrato, per valutare le caratteristiche biomeccaniche del suddetto paziente, passando dalla modellazione NMS, all’analisi del modello FE della pelvi, per effettuare un’analisi comparativa dell’arto osteoartritico con il modello dall’arto controlaterale prima dell’intervento e dopo lo stesso
31
Coombs, Matthew T. "Development of an experimental method to identify structural properties of the intervertebral joint after spine staple implantation under simulated physiologic loads". University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1322052236.
Testo completo
32
Reinert, Senia Smoot. "Enhancing Posturography Stabilization Analysis and Limits of Stability Assessment". University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1470227622.
Testo completo
33
Gutierrez-Franco, Juan. "THE EFFECTS OF OBESITY ON RESULTANT KNEE JOINT LOADS FOR GAIT AND CYCLING". DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1624.
Testo completoAbstract (sommario):
Osteoarthritis (OA) is a degenerative disease of cartilage and bone tissue and the most common form of arthritis, accounting for US$ 10.5 billion in hospital charges in 2006. Obesity (OB) has been linked to increased risk of developing knee OA due to increased knee joint loads and varus-valgus misalignment. Walking is recommended as a weight-loss activity but it may increase risk of knee OA as OB gait increases knee loads. Cycling has been proposed as an alternative weight-loss measure, however, lack of studies comparing normal weight (NW) and OB subjects in cycling and gait hinder identification of exercises that may best prevent knee OA incidence. The objective of this work is to determine if cycling is a better weight-loss exercise than gait in OB subjects as it relates to knee OA risk reduction due to decreased knee loads. A stationary bicycle was modified to measure forces and moments at the pedals in three dimensions. A pilot experiment was performed to calculate resultant knee loads during gait and cycling for NW (n = 4) and OB (n = 4) subjects. Statistical analyses were performed to compare knee loads and knee angles, and to determine statistical significance of results (p < 0.05). Cycling knee loads were lower than gait knee loads for all subjects (p < 0.033). OB axial knee loads were higher than NW axial knee loads in gait (p = 0.004) due to the weight-bearing nature of gait. No differences were observed in cycling knee loads between NW and OB subjects, suggesting cycling returns OB knee loads and biomechanics to normal levels. The lack of significant results in cycling could be due to the small sample size used or because rider weight is supported by the seat. Limitations to this study include small sample size, soft tissue artifact, and experimental errors in marker placement. Future studies should correct these limitations and find knee joint contact force rather than knee resultant loads using v EMG-driven experiments. In conclusion, cycling loads were lower than gait loads for NW and OB subjects suggesting cycling is a better weight-loss exercise than gait in the context of reducing knee OA risk.
34
Denning, Matthew M. "The Effects of Aquatic Exercise on Physiological and Biomechanical Responses". DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/670.
Testo completoAbstract (sommario):
Due to recent advances in aquatic research, technology, and facilities, many modes of aquatic therapy now exist. These aquatic modes assist individuals (e.g., osteoarthritis patients) in the performance of activities that may be too difficult to complete on land. However, the biomechanical requirements of each aquatic therapy mode may elicit different physiological and functional responses. Therefore, the purpose of this thesis was to: (a) provide a review of the physiological and biomechanical differences between aquatic and land based exercises, and (b) examine the acute effects of underwater and land treadmill exercise on oxygen consumption (VO2), rating of perceived exertion (RPE), perceived pain, mobility, and gait kinematics for patients with osteoarthritis (OA). Methods consisted of the retrieval of experimental studies examining the physiological and biomechanical effects of deep water running (DWR), shallow water running (SWR), water calisthenics, and underwater treadmill therapy. The methods also examined the physiological and biomechanical effects on 19 participants during and after three consecutive exercise sessions on an underwater treadmill and on a land-based treadmill. Based on the studies reviewed, when compared to a similar land-based mode, VO2 values are lower during both DWR and SWR, but can be higher during water calisthenics and underwater treadmill exercise. RPE responses during DWR are similar during max effort, and stride frequency and stride length are both lower in all four aquatic modes than on land. Pain levels are no different between most water calisthenics, and most studies reported improvements in mobility after aquatic therapy, but no difference between the aquatic and land-based modes. The OA participants achieved VO2 values that were not different between conditions during moderate intensities, but were 37% greater during low intensity exercise on land than in water (p = 0.001). Perceived pain and Time Up & Go scores were 140% and 240% greater, respectively, for land than underwater treadmill exercise (p = 0.01). Patients diagnosed with OA may walk on an underwater treadmill at a moderate intensity with less pain and equivalent energy expenditures compared to walking on a land-based treadmill.
35
Holmberg, Joakim L. "Computational Biomechanics in Cross‐country Skiing". Licentiate thesis, Linköping University, Linköping University, Department of Management and Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-10671.
Testo completoAbstract (sommario):
Traditionally, research on cross‐country skiing biomechanics is based mainly on experimental testing alone. Trying a different approach, this thesis explores the possibilities of using computational musculoskeletal biomechanics for cross‐country skiing. As far as the author knows, this has not been done before.
Cross‐country skiing is both fast and powerful, and the whole body is used to generate movement. Consequently, the computational method used needs to be able to handle a full‐body model with lots of muscles. This thesis presents several simulation models created in the AnyBody Modeling System, which is based on inverse dynamics and static optimization. This method allows for measurementdriven full‐body models with hundreds of muscles and rigid body segments of all major body parts.
A major result shown in the thesis is that with a good simulation model it is possible to predict muscle activation. Even though there is no claim of full validity of the simulation models, this result opens up a wide range of possibilities for computational musculoskeletal biomechanics in cross‐country skiing. Two example of new possibilities are shown in the thesis, finding antagonistic muscle pairs and muscle load distribution differences in different skiing styles. Being able to perform optimization studies and asking and answering “what if”‐questions really gives computational methods an edge compared to traditional testing.
To conclude, a combination of computational and experimental methods seems to be the next logical step to increase the understanding of the biomechanics of crosscountry skiing.
Traditionellt har biomekaniska forskningsstudier av längdskidåkning baserats helt och hållet på experimentella metoder. För att prova ett annat angreppssätt undersöks i denna avhandling vilka möjligheter som beräkningsbaserad biomekanik kan ge för längdskidåkning. Så vida författaren vet, har detta inte gjorts tidigare.
Längdskidåkning innehåller snabba och kraftfulla helkroppsrörelser och därför behövs en beräkningsmetod som kan hantera helkroppsmodeller med många muskler. Avhandlingen presenterar flera simuleringsmodeller skapade i AnyBody Modeling System, som baseras på inversdynamik och statisk optimering. Denna metod tillåter helkroppsmodeller med hundratals muskler och stelkroppssegment av de flesta kroppsdelarna.
Ett resultat som avhandlingen visar är att med en bra simuleringsmodell är det möjligt att förutsäga muskelaktiviteten för en viss rörelse och belastning på kroppen. Även om ingen validering av simuleringsmodellen ges, så visar ändå resultatet att beräkningsbaserad biomekanik ger många nya möjligheter till forskningsstudier av längdskidåkning. Två exempel visas, hur muskelantagonister kan hittas samt hur lastfördelningen mellan musklerna förändras då skidåkaren förändrar stilen. Att kunna genomföra optimeringsstudier samt fråga och svara på ”vad händer om”‐ frågor ger beräkningsbaserad biomekanik en fördel i jämförelse med traditionell testning.
Slutsatsen är att en kombination av beräkningsbaserade och experimentella metoder borde vara nästa steg för att addera insikt om längdskidåkningens biomekanik.
Report code: LIU‐TEK‐LIC‐2008:4. On the day of the defence date the status of article V was: Submitted.
36
Fortenbaugh, David. "The Biomechanics of the Baseball Swing". Scholarly Repository, 2011. http://scholarlyrepository.miami.edu/oa_dissertations/540.
Testo completoAbstract (sommario):
Success in baseball batting is fundamental to the sport, however it remains one of, if not the most, challenging skills in sports to master. Batters utilize the kinetic chain to transfer energy from the lower body to the upper body to the bat, hoping to impart the maximum amount of energy into the ball. Scientists and coaches have researched the swing and developed theories on the keys for successful batting, but most of this research has been inadequate in attempting to fully describe the biomechanics of batting. The purposes of this study were to improve upon the methodology of previous researchers, provide a full biomechanical description of the swing, and compare swings against pitches thrown to different locations and at different speeds. AA-level Minor League Baseball players (n=43) took extended rounds of batting practice in an indoor laboratory against a pitcher throwing a mixture of fastballs and changeups. An eight camera motion analysis system and two force plates recording at 300 Hz captured the biomechanical data. The swing was divided into six phases (stance, stride, coiling, swing initiation, swing acceleration, and follow-through) by five key events (lead foot off, lead foot down, weight shift commitment, maximum front foot vertical ground reaction force, and bat-ball contact). Twenty-eight kinematic measurements and six ground reaction force measurements were computed based on the marker and force plate data, and all were assessed throughout the phases. First, a comprehensive description of a composite of the batters’ swings against fastballs “down the middle” was provided. Second, successful swings against fastballs thrown to one of five pitch locations (HIGH IN, HIGH OUT, LOW IN, LOW OUT, MIDDLE) were compared in terms of selected kinematics at the instant of bat-ball contact, timing and magnitude of peak kinematic velocities, and timing and magnitude of peak ground reaction forces. Third, these variables were once again compared for swings against fastballs and changeups. A large number of biomechanical differences were seen among the swings against various pitch locations. More fully rotated positions, particularly of the pelvis and bat were critical to the batters’ successes on inside pitches while less rotated positions keyed successes against outside pitches. The trail and lead arms worked together as part of a closed chain to drive the hand path. Successful swings had the trail elbow extended more for HIGH IN and flexed more for LOW OUT, though batters often struggled to execute this movement properly. A distinct pattern among successful swings against fastballs, successful swings against changeups, and unsuccessful swings against changeups was witnessed; namely a progressive delay in which the batter prematurely initiated the events of the kinetic chain, especially when unsuccessful in hitting a changeup. It was believed that this study was much more effective in capturing the essence of baseball batting than previous scientific works. Some recommendations to batting coaches would be to get batters to take a consistent approach in the early phases of every swing (particularly for the lower body), identify both pitch type and location as early as possible, use the rotation of the pelvis to propagate the energy transfer of the kinetic chain from the group to the upper body, and use the pelvis, and subsequently, the upper body, to orient the trunk and hands to an optimal position to drive the ball to the desired field. Limitations of the current study and ideas for future work were also presented to better interpret the findings of this research and further connect science and sport.
37
Ross, Erica. "Woodpeckers and the biomechanics of concussion". Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/50869.
Testo completoAbstract (sommario):
Woodpeckers are a remarkable clade of birds commonly known to use forceful blows of their beaks to drill holes in trees while foraging for boring insects or sap, and they also use their beaks to excavate nest cavities and loudly announce their territory by drumming. They regularly tolerate forces ten times greater than those that would give a human a concussion.
Human concussions are the focus of a lot of attention and research efforts recently, especially in the world of sports and veteran's affairs where head injury's debilitating effects on immediate and long-term health are becoming more recognised. Woodpeckers are good organisms to study to gain insights into concussions.
Many factors have been proposed to contribute to the woodpeckers’ ability to withstand the blows to its head. Some hypotheses are more likely than others, but the topic suffers from a lack of data. This thesis addresses the hypothesis that the brain is semi-isolated from the forces experienced by the rest of the head, and the hypothesis that woodpeckers have minimal space between their brains and skulls, and minimal cerebrospinal fluid.
We used high-speed video analysis of wild captured Pileated Woodpeckers to evaluate whether there was any evidence that the brain case is semi-isolated from the rest of the woodpecker’s head. The acceleration profiles of points on the head and on the beak were not significantly different, and the distances between the head point and the beak point before and after a strike also were not significantly different. We used CT and MRI scans to visualize and measure the space between the brain and skull. The space was quantified and was not smaller than might be expected once scaling between a human’s head and a woodpecker’s head was taken into account.
We conclude that woodpeckers’ resistance to head injury is not likely due to force deflection away from the brain, or especially tight packing of the brain, and hypothesize that it is due to scaling effects, a short impact duration, woodpeckers’ smooth brain, and possible neuroprotective mechanisms.Science, Faculty of
Zoology, Department of
Graduate
38
Atack, Alexandra. "The biomechanics of rugby place kicking". Thesis, St Mary's University, Twickenham, 2016. http://research.stmarys.ac.uk/1407/.
Testo completoAbstract (sommario):
Approximately 45% of the points scored in international Rugby Union matches are the result of place kicks (Quarrie & Hopkins, 2015). However, the key technique characteristics underpinning this skill are not well understood. The aim of this thesis was therefore to investigate rugby place kicking technique and performance, and understand how these differ between successful and less successful place kickers. In order to objectively quantify place kick performance outcome from data collected in a laboratory environment, a novel performance measure representative of the maximum distance that any given place kick could be successful from was developed. This measure combined initial ball flight data with previously published aerodynamic forces and was shown to predict ball location with a mean error of 4.0%. Full body motion capture and ground reaction force data were then collected from 33 experienced (amateur to senior international level) kickers and three groups of kickers were identified based on their performance outcome: long, short, and wide-left kickers. Differences were observed in the initial ball flight characteristics between the three groups and specific aspects of technique were then analysed to understand how these different performance outcomes were achieved. The long and wide-left kickers used different strategies to achieve comparable forward kicking foot velocities and initial ball velocities. The wide-left kickers used a hip flexor strategy: greater positive hip flexor work which was facilitated by a stretch across the trunk at the top of the backswing, followed by longitudinal rotation throughout the downswing. In contrast, the long kickers used a knee extensor strategy: greater positive knee extensor work and a more consistent trunk orientation throughout the downswing. Although both strategies led to comparably high initial ball velocity magnitudes, the hip flexor strategy led to greater longitudinal ball spin and an initial ball velocity vector directed towards the left-hand-side. Kickers who achieve fast ball velocities but miss left could potentially benefit from technical interventions to address their trunk kinematics or development of their kicking knee extensor involvement. The long kickers achieved faster kicking foot and initial ball velocities than the short kickers. The long kickers took a more angled and faster approach to the ball compared with the short kickers. This enabled the pelvis to be less front-on at the top of the backswing, meaning that the kicking foot was further away from the ball at this point and subsequently travelled a longer path to initial ball contact. The long kickers also demonstrated greater horizontal whole-body CM deceleration between support foot contact and initial ball contact and performed greater hip flexor and knee extensor positive work than the short kickers during the downswing. Kickers who cannot generate fast ball velocities could potentially benefit from interventions to their approach direction and velocity, or from development of their kicking hip flexor and knee extensor involvement. This thesis has provided a comprehensive understanding of rugby place kicking technique and recommendations for both coaching practice and research.
39
Holmberg, L. Joakim. "Computational biomechanics in cross-country skiing /". Linköping : Department of Management and Engineering, Linköping University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-10671.
Testo completo
40
Mitchell, Andrew Charles Stephen. "The biomechanics of functional ankle instability". Thesis, University of Chichester, 2005. http://eprints.chi.ac.uk/842/.
Testo completoAbstract (sommario):
An epidemiological study into the incidence of ankle sprain in elite and non-elite athletes was carried out to collect data on the incidence of sports injuries focusing specifically on ankle sprains in elite and non-elite athletes. Furthermore, to develop and validate a questionnaire to be used to collect data on the residual symptoms associated with a history of ankle sprain and functional instability. Ankle sprains accounted for 16% of all injuries and symptoms of functional instability were reported by 95% of athletes that reported sustaining an ankle sprain during the study. The questionnaire was then used to recruit subjects (19 subjects with a history of unilateral ankle sprain and functional instability and 19 healthy controls) for the subsequent experiments. Anteroposterior and medio-lateral postural sway in single-limb stance was examined using a KistierTM force platform. Each subject underwent twelve postural sway tests: three on each leg with eyes open and eyes closed. With eyes closed the injured ankle had significantly greater medial (p=O.001) and lateral (p=O.007) postural sway than the uninjured ankle. With eyes open the injured and uninjured ankles had similar postural control. With eyes open the injured ankle had significantly greater anterior (p=O.021, p=O.Oll) and posterior (p=O.019, p=O.018) postural sway than the dominant and non-dominant ankles respectively. With eyes closed the injured ankles had significantly greater medial (p=O.008, p=O.008) and lateral (p=O.014, p=O.015) postural sway than the dominant and non-dominant ankles respectively. The reaction time of peroneus longus, peroneus brevis, tibialis anterior and extensor digitorum longus to a non-pathological lateral ankle sprain mechanism was examined using a purpose built tilt platform. The platform had two moveable plates so that either ankle could be tilted spontaneously into combined plantarflexion and inversion. Electromyography was performed on each muscle and subjects had each ankle tilted six times. A computer-based onset detection method was developed to provide an objective method for identifying the onset of electromyography and tilt platform activity and calculating muscular reaction times. The injured ankle peroneus longus, peroneus brevis and tibialis anterior reaction times were significantly slower.
41
Walker, Lloyd T. "The biomechanics of the human foot". Thesis, University of Strathclyde, 1991. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21131.
Testo completoAbstract (sommario):
This thesis reports on work undertaken to study the biomechanics of the human foot during normal daily activity, particularly walking and standing. A literature review is presented on topics related to the subject and several of the areas demanding further investigation are highlighted. Three lines of enquiry were pursued to consider the kinematics, kinetics, passive structural properties and muscle activity associated with the foot. A dynamic pedobarograph with a synchronised video system was used to measure the forces and their distribution under the foot (based on seven marked areas) and six kinematic angles of the foot and lower leg. Sixty-one healthy subjects were assessed and the results are presented. Kinetic and kinematic parameters were found to be consistent and smooth for the test population. Several of the events of the gait cycle were found to be temporally different from values widely reported. In the second investigation, four cadaveric foot specimens were tested dynamically to determine the role of the plantar structures during loading in various positions. A method of sequential dissection was used and the results support many of the theories regarding ligament function. Tests on the effect of three extrinsic muscles on the foot load distribution also support previous studies while a preliminary investigation of two pathological feet partially clarifies the biomechanical effects of a hallux valgus deformity. Eight of the foot extrinsic and intrinsic muscles were assessed for the final investigation. Using electromyographic (EMG) recording techniques on six healthy subjects, the muscle EMG activity was quantified during walking a) barefoot, b) with a moulded heel plate, and c) with soft shoes. The results for the extrinsic muscles generally agree with previous work, while the intrinsic muscle activity is more variable. The intrinsic muscles were more active when shoes were worn and displayed unusual fatigue patterns.
42
Kwende, Martin M. N. "The biomechanics of skeletal muscle ventricles". Thesis, University of Liverpool, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283451.
Testo completo
43
Ennos, A. R. "The biomechanics of flight in Diptera". Thesis, University of Exeter, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379461.
Testo completo
44
Oehring, Daniela. "Ocular biomechanics of the anterior segment". Thesis, University of Plymouth, 2018. http://hdl.handle.net/10026.1/10647.
Testo completoAbstract (sommario):
The thesis investigates methods of examining corneal biomechanics using non-contact tonometry and introduces novel techniques to investigate corneal material properties in vivo. A comprehensive systems analysis of the CorvisST (CST) and Ocular Response Analyser (ORA) was performed. Pressure sensors were used to characterisation the airflow produced by the CST and the ORA. Distinct differences were observed between the central airflow pressures between the two devices: the CST pressure was higher and of shorter duration. Scheimpflug high-speed imaging via the CST allowed components of the corneal deformation to be investigated and the development of a 3D deformation matrix (time, depth and spatial resolution) through tracing of the anterior and posterior corneal surface. Measures of whole eye movement (WEM) with CST were found to be robust. WEM demonstrated an asymmetric profile and a correction method was developed to address the corneal deformation matrix for this asymmetry. Novel methods for characterisation of intrinsic material characteristics of the cornea were developed using numerical and graphical analytical procedures. Application of these parameters was tested on enucleated porcine eyes across a wide range of manometry internal ocular pressure (MIOP). The dynamic E-Modulus was found to be most affected by MIOP change. To investigate the in vivo distribution and heterogeneity of the corneal biomechanics, a novel set-up allowed the mapping of corneal biomechanics across the cornea using the CST (central, paracentral, peripheral) and ORA (central, peripheral). Biometric and demographic grouping of subjects allowed detection of discriminating factors between individuals. The results suggest that the in vivo cornea of healthy human adults can be characterised as a viscoelastic, damped system for longitudinal strain and a highly oscillating system for lateral strain. The cornea is approximately homogenous for measures of rigidity and dynamic E-Modulus but other corneal material characteristics (longitudinal and lateral strain, hysteresis, damping and compressibility) demonstrated regional differences. The experimental design employed allowed for strict control of biometric and biomechanical intersubject variables, based on gold-standard techniques as well as newly-developed methods, thereby creating a normative database for future use.
45
Peters, Abby E. "Biomechanics of the ageing human knee". Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3020598/.
Testo completoAbstract (sommario):
The knee joint is an integral component of the musculoskeletal system, aiding the absorption and transition of weight bearing forces. It is often subjected to injury or disease, with osteoarthritis (OA) being the most prevalent disease, particularly amongst the elderly population. It is now understood that OA is a whole-joint disease affecting the entire osteochondral unit at a molecular and cellular level; however to what extent this effects material properties is mostly unexplored. This thesis firstly aimed to comprehensively review the current knowledge of whole human knee joint material properties in young versus old and healthy versus OA samples, and their subsequent macro-scale application into existing finite element (FE) models. Results indicated unambiguous gaps in the literature for material properties, particularly evident in the aged and OA samples. Consequently, existing human knee FE models apply material properties from a variety of animal and human cohorts, obtained from differing anatomical localities and diverse cadaver demographics, reducing the biological accuracy of resultant mechanical behaviour predicted from such models. Secondly, this thesis aimed to determine the effects of multiple freeze-thaw cycles on cartilage material properties in an attempt to justify a reliable storage and perseveration technique for future work. Results showed that cartilage can undergo up to three freeze-thaw cycles without statistically compromising the integrity of samples. Although data should be interpreted and subsequently applied to future research with consideration in relation to its particular application due to high biological variability across samples. Finally, this thesis aimed to collect and analyse new primary material property data of spatially distributed cartilage, subchondral bone and trabecular bone by nanoindentation techniques, and the four primary knee joint ligaments by tensile testing. Samples were obtained from cadaveric specimens with a wide age range (31-88 years) and OA grade (International Cartilage Repair Society grades 0-4) to provide varying demographics that were evidently missing from the literature. Cartilage shear storage and loss modulus and subchondral bone elastic modulus significantly decreased with increasing age and grade of OA. Furthermore, a change in cartilage shear storage and loss modulus was correlated with a change in subchondral bone elastic modulus in site-matched samples. Trabecular bone elastic modulus was not correlated with age or OA. Results also showed preferential regional development of OA in the medial knee compartment and a decrease in cartilage shear storage modulus at site-specific locations. Additionally, the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) material properties had correlations with age, and linear and failure mechanics showed some correlations with increasing OA grade. The medical collateral ligament (MCL) and lateral collateral ligament (LCL) failure mechanics also showed some correlated with an increase in age and OA grade. This thesis has provided, for the first time, whole-joint multiple tissue material properties from the same cadavers during ageing and disease, concluding that both age and OA affect the material properties of the entire osteochondral unit. Such valuable data can be applied to future FE modelling of the human knee to produce more accurate predication of mechanical behaviour. Current data can also be applied therapeutically, including the use of biomimetic materials, joint replacement and pharmacological interventions.
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Labonte, David. "Biomechanics of controllable attachment in insects". Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709249.
Testo completo
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Robinovitch, Stephen Neil. "Hip fracture and fall impact biomechanics". Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/11635.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Whitaker College of Health Sciences and Technology, 1994.Includes bibliographical references (p. 164-166).
by Stephen Neil Robinovitch.
Ph.D.
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Kemper, Andrew Robb. "The Biomechanics of Thoracic Skeletal Response". Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/37635.
Testo completoAbstract (sommario):
The National Highway Traffic Safety Administration (NHTSA) reported that in 2008 there were a total of 37,261 automotive related fatalities, 26,689 of which were vehicle occupants. It has been reported that in automotive collisions chest injuries rank second only to head injuries in overall number of fatalities and serious injuries. In frontal collisions, chest injuries constitute 37.6% of all AIS 3+ injuries, 46.3% of all AIS 4+ injuries, and 43.3% of all AIS 5+ injuries. In side impact collisions, it has been reported that thoracic injuries are the most common type of serious injury (AISâ ¥3) to vehicle occupants in both near side and far side crashes which do not involve a rollover. In addition, rib fractures are the most frequent type of thoracic injury observed in both frontal and side impact automotive collisions.
Anthropomorphic test devices (ATDs), i.e. crash test dummies, and finite element models (FEMs) have proved to be integral tools in the assessment and mitigation of thoracic injury risk. However, the validation of both of these tools is contingent on the availability of relevant biomechanical data. In order to develop and validate FEMs and ATDs with improved thoracic injury risk assessment capabilities, it is necessary to generate biomechanical data currently not presented in the literature. Therefore, the purpose of this dissertation is to present novel material, structural, and global thoracic skeletal response data as well as quantify thoracic injury timing in both frontal belt loading and side impact tests using cadaveric specimens.Ph. D.
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Press, Jaclyn Nicole. "Biomechanics of Head Impacts in Soccer". Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/82521.
Testo completoAbstract (sommario):
An estimated 3.8 million sports-related concussions occur every year. Little research has been collected on soccer players, despite women's soccer having the third highest rate of concussion among all popular collegiate sports. The objective of this work was to evaluate multiple interventions that have been introduced to address the high rate of concussions in this population. Wearable head impact sensors were evaluated on their ability to accurately count and measure head impacts during a collegiate women's soccer season. Head impact exposure was quantified using video analysis of this season as well. Sensors were unable to accurately count impacts and reported nonsensical head acceleration measurements, indicating that data reported from head impact sensors should be interpreted with caution. The ability of soccer headgear to reduce linear and rotational head accelerations during common soccer impacts was examined in the laboratory. Ball-to-head and head-to-head impacts were performed at a range of speeds and impact orientations. Headgear resulted in small reductions during ball-to-head tests, which are not likely to be clinically relevant. In head-to-head tests, use of headgear on the struck head provided an overall 35% reduction in linear head acceleration, and a 53% reduction when another headgear was added to the striking head. The ten headgear tested varied greatly in performance. These data suggest that the use of protective headgear could reduce concussion incidence significantly in this population. Research presented in this thesis will inform soccer organizations on best practices for player safety with regard to head impacts.Master of Science
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Williams, Celeste Benay. "The biomechanics of normal breast tissue /". The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488205318510891.
Testo completo