With the high mortality rate of cardiovascular disease, it is important to study the early signs. The early detection of cardiovascular disease can lead to saved lives. Currently the most prevalent detection methods are the Framingham Risk Score and the carotid intima media thickness, both of which are insufficient. The necessary tool for early detection requires a uniform quantification system. The stimulus leading to endothelial dysfunction, the most significant predictor of a major adverse cardiovascular event (MACE)—and subsequently subclinical atherosclerosis—is reduced shear stress. Increased surface relative roughness affects the flow profile transition from laminar to turbulent resulting in reduced shear rate. The relationship between the shear stress and the relative roughness was studied using a computer model for fluid flow. A model of the brachial artery was generated to study its hemodynamics. Roughness values for both laminar and turbulent flow were calculated to use with the governing equations programmed in COMSOL Multiphysics. With all other factors remaining constant in the model, the roughness values were changed. From the model profile plots, line graphs, and numeral data are generated. This data provides information about how the shear stress and the shear rate change with respect to the relative roughness value. The models with different wall boundary conditions—slip versus Navier slip—were unable to be directly compared due to the differences in value magnitude. When the flow profile transitions from laminar to turbulent, there is a corresponding drop in both the shear stress and the shear rate values. Additional testing is required to determine a critical relative roughness value for this change in cumulative shear.

ABSTRACT Skier’s Edge: Biomechanical Analysis Benjamin T. Johannes The Skier’s Edge trainer can be used by novice or expert skiers. Testing was performed to analyze if the use of the Skier’s Edge could reduce in shear forces of the valgus moment on the knee joint and anterior cruciate ligament (ACL) due to lesser fatigue of muscle and a higher hamstring to quadricep (H/Q) ratio activity. This leads to a reduction of improper form and an increase in balance. Experiments performed observed the change in muscle activity with the use of the Skier’s Edge over time when compared to other forms of workout (elliptical and or a traditional ski conditioning workout). Comparison of the three workout methods was completed by collecting kinematic, kinetic and electromyographic (EMG) data. Each participant, 9 male skiers (22±3 years old, 70.56±3.44 inches, 206±54 lbs.) and 6 female skiers (22±4 years old, 66.25±3.25 inches, 148±72 lbs.), were separated into even groups between the workout types. Data was collected initially and after a four-week period of exercise for each respective workout group. A relative valgus moment was found with the force and valgus angle data and an H/Q ratio was created using the vastus medialis and semitendinosus EMG data for the respective muscles. The findings of this study show that there were no significant differences between the workout types for either reduction of valgus moment or an increase in H/Q ratio which are indicators of reduced ACL injury. Trends in the data indicate that the elliptical workout may have a positive impact on H/Q when compared to the Skier’s Edge workout. Recommendation for future study includes having participants complete a more intense and longer workout period or to focus on the elliptical and Skier’s Edge workout to test for significant differences to aid in ACL injury reduction.

In the human genome, the SOST gene codes for a protein sclerostin. Sclerostin is an osteocyte-expressed negative regulator of bone formation. When the SOST gene is not coded, bone formation is reduced in individuals during skeletal maturation. This study utilizes nanoindentation methods to test for the mechanical properties of bones that both express and do not express the SOST gene. 100 transgenic murine femurs were obtained from Lawrence Livermore Labs in the form of 6 and 8 month SOST transgenic mice, 6 and 12 month SOST knockout mice, and wild type control littermates for each of the 4 age groups. Prior to nanoindentation the bones were broken in a previous experiment under three-point bending tests. Samples were embedded in epoxy and polished to a 0.05 micron level before indentation. Results showed significant difference amongst the treatment group effects for maximum load, hardness and elastic modulus. SOST KO mice had significantly higher values for these properties in comparison to the transgenic and wild type littermates. Additionally, side by side limb differences were examined in which there was a significant difference found amongst the treatment groups. Indentations were conducted in the 4 anatomical regions of each femur in expectation of examining any differences amongst them which resulted with no significant findings amongst them. Data from this study will support research which may result in potential new gene therapies targeted for the treatment of bone diseases such as osteoporosis.

The purpose of this thesis project is to demonstrate and evaluate an enzyme-linked immunosorbent assay (ELISA) on a paper microfluidic device platform. The integration of ELISA technology onto paper microfluidic chips allows for a quantitative detection of stroke biomarkers, such as glial fibrillary acidic protein (GFAP). Dye experiments were performed to confirm fluid connectivity throughout the 3D chips. Several chip and housing designs were fabricated to determine an optimal design for the microfluidic device. Once this design was finalized, development time testing was performed. The results confirmed that the paper microfluidic device could successfully route fluid throughout its channels at a reasonable rate. For the biochemistry portion of this thesis project, antibodies were selected to target the intended stroke biomarker: GFAP. However, due to antibody pairing complications, the protein chosen for this project was natural human cardiac troponin T, which is elevated in the bloodstream of patients who have suffered a stroke. Several antibody experiments were performed to help finalize the procedure for performing an ELISA on the paper chip. The final antibody experiment was able to demonstrate that a paper microfluidic device utilizing ELISA techniques can successfully detect a stroke biomarker at physiologically relevant concentrations. Overall, this project supported the ability to accurately and effectively diagnose stroke in a timely manner through the use of a paper microfluidic device.

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.

It is estimated that approximately 10-12% of the adult population suffers from osteoarthritis (OA), with long reaching burdens personally and socioeconomically. OA also causes mild discomfort to severe pain in those suffering from the disease. The incidence rate of OA for individuals with transtibial amputations is much than average in the tibiofemoral joint (TF). It is well understood that abnormal articular cartilage stress, whether that be magnitude or location, increases the risk of developing OA. Finite element (FE) simulations can predict stress in the TF joint, many studies throughout the years have validated the technology used for this purpose. This thesis is the first to successfully validate a procedure for creating subject-specific FE models for transtibial amputees to simulate the TF joint in gait, cycling and elliptical exercises. Maximum tibial cartilage pressure was extracted post-simulation and compared to historical data. The body weight normalized contact pressure on the tibial articular cartilage for the two amputee participants was larger in magnitude than the control participant in all but the medial compartment in cycling. Additionally, cycling exercise produced the smallest values of contact pressure with elliptical and gait producing similar max values but different areas of effect. The results from this thesis align with the body of work preceding it and further the goal of a FE model that predicts in-vivo articular cartilage stress in the TF joint. Future studies can further refine this methodology and create additional subject-specific models to allow for a statistical analysis of the observed differences to find if the results are significantly different. Refining the methodology could include investigating the full effect of the damping factor on contact pressure and exploring alternative methods of mesh generation.

INTRODUCTION: An increase in participation in females sports has created an increase of female athletes at risk for injuring their Anterior Cruciate Ligament(ACL)[12,21,29,44]. Traditional jumping sports have the highest rate of non contact ACL injuries, due to the use of movements of cutting, pivoting and landing on one foot[5,8,32,33,38]. ACL injuries can also be attributed to neuromuscular deficits such as the ‘Ligament Dominance Theory’, ‘Quadricep Dominance Theory’, ‘Trunk Dominance Theory’ and the ‘Leg Dominance Theory’[24,33]. The neuromuscular deficits are muscle strength, power or activation patterns that can cause an individual to have an increased risk of ACL injury[33]. Female traditional jumping sport athletes have been associated with being at a higher risk of ACL injury than their male counterparts due to anatomical, hormonal and neuromuscular differences[2,8,24,28,32,37,38,44,47]. However, female dancers trained with ballet have a lower risk of ACL injury than their female athlete counterparts, but also have a similar ACL injury to their male dancing counterparts [28,37,45,47]. METHODS: This study analyzed six papers that compared the lower body biomechanics of female traditional jumping sport athletes to female dancers trained in ballet. The results of the measurement of this study will be placed into a chart to compare the results of each study to each other, to confirm the results of the comparison between the two populations. The next part of this study will examine unused turnout angle data collected from a previous thesis performed by Ashley Tornio. The data was taken from 20 participants, 15 female traditional jumping sport athletes and 5 female dancers trained in ballet. The averages of these two groups will be compared using an f test to determine differences in the turnout capabilities of each group. RESULTS: The results of the data comparison found only six comparable measurements between the 6 papers. The papers were in agreement that female traditional jumping sport athlete had greater hip adduction moments and trunk forward flexion than female dancers trained in ballet. The papers were also in agreement that there was no statistically significant difference in the knee stiffness between the two populations. There was no consensus for the results of knee valgus angle, knee rotation, muscle activation or leg stiffness between the six papers. For the turnout angle f test, female traditional jumping sport athletes had an average turnout angle of 120.5 degrees and the female dancers trained in ballet had an average turnout angle of 141.2 degrees. It was found that the there was no statistically significant difference between the two populations at the 95% confidence level. However, there was a statistically significant difference between the two populations average turnout at a reduced confidence level of 80%. The DISCUSSION: The limiting number of studies which compare female traditional jumping sport athletes and female dancers trained in ballet, were unable to form consensus on the difference between the biomechanics of each group during a landing task. The turnout angle data was also limited in the number of participants and a valid conclusion was unable to be made determining the ability to use the turnout angle as an indicator for risk of ACL injury. There needs to be continued research on the comparison of the female traditional jumping sport athletes and female dancers trained in ballet to determine the biomechanical advantages female dancers have for protection of the ACL.

According to various studies, compared with novice athletes, experts exhibit superior integration of perceptual, cognitive, and motor skills. This superior ability has been associated with the focused and efficient organization of task-related neural networks. Specifically, skilled individuals demonstrate a spatially localized or relatively lower response in brain activity, characterized as ‘neural efficiency’, when performing within their domain of expertise. Previous works also suggested that elite basketball players can predict successful free throws more rapidly and accurately based on cues from body kinematics. These traits are the result of a prolonged training of specific motor skills and focused excitability of the motor cortex during the reaction, movement planning, and execution phases. However, due to motion artifacts occurring during movement initiation and execution, the knowledge about the underlying mechanism and the connection between brain neural networks and body musculoskeletal systems is still limited. Thus, the objective of this study is to utilize electroencephalography (EEG) and motion capture systems (MoCap) to advance and expand the current understanding of the relationships between neurophysiological activities and human biomechanics as well as their effects on the success rate of the motor skills. The project focuses on fulfilling three specific aims. The first aim focused on the integration of the EEG and the MoCap systems to analyze and compare the successful and unsuccessful outcomes of basketball throws. Then, the second aim utilized Convolution Neural Networks (CNNs) as an alternative approach to predict the shot’s outcome based on the recorded EEG signals and biomechanical parameters. Lastly, the third aim identified the impact of each EEG channel and MoCap parameter on the CNN models using ablation methods. The results obtained from this study can be a practical approach in analyzing the sources that lead to better elite athletes’ performance in various sport-related tasks. Moreover, the acquired data can contribute to a deeper understanding of the vital biomechanical and neurological factors that directly affect the performance of elite athletes during successful outcomes, thus, providing vital information for the overall improvement of athletic performance and guidance for sport-specific training needs.

Millions of individuals around the globe are impacted by osteoarthritis, which is the prevailing type of arthritis. This condition arises as a result of gradual deterioration of the protective cartilage that safeguards the ends of the bones. This is especially true of transtibial amputees, who have a significantly higher incidence of osteoarthritis of the knee in their intact limb than non-amputees. Engaging in regular physical activity, managing weight effectively, and undergoing specific treatments can potentially slow down the advancement of the disease and enhance pain relief and joint function. Nevertheless, the relationship between the type of exercise and its impact on cartilage stress remains uncertain. In order to address this question, tibiofemoral finite element analysis (FEA) models were developed. The models incorporated more realistic material properties for cartilage, hexahedral elements, and non-linear springs for ligaments. To ensure their accuracy, the models were validated against experimental data obtained from cadaveric studies. The contact loads and flexion angles of two individuals with amputations and one individual without amputation, which were obtained in a previous study conducted at Cal Poly, were implemented in the FEA models for gait, cycling, and elliptical exercises. The FEA models were used to extract the maximum stress values experienced in the tibial contact areas, specifically in the medial and lateral compartments of the knee. In cycling, the normalized contact pressure on the tibial articular cartilage, relative to body weight, was generally higher for the two participants with amputations compared to the control participant, except for the medial compartment. Furthermore, when comparing different exercises, cycling resulted in the lowest contact pressure values, with elliptical and walking exercises producing similar maximum values. The findings indicated that individuals with amputations are at a greater risk of developing OA, regardless of the type of exercise performed. However, among the different exercises studied, cycling was found to exert the lowest levels of compression stress on the tibial cartilage.

To confirm computer simulations and Computational Fluid Dynamics (CFD) analysis, benchtop experiments are needed with a fluid that mimics blood and its viscoelastic properties. Blood is challenging to use as a working fluid in a laboratory setting because of health and safety concerns. Therefore, a blood analogue is necessary to perform benchtop experiments. Viscosity is an important property of fluids for modeling and experiments. Blood is a shear thinning fluid, so it has a decreasing viscosity with higher shear rates. This project seeks to create a blood mimicking fluid for benchtop laboratory use. Numerous fluids with different combinations of water, glycerin, and xanthan gum were created to mimic the shear thinning property of blood at different hematocrit levels. Since the amount of xanthan gum is very small, an analytical balance was used. To mix the solution, an immersion blender and a heat circulator were used. The data were obtained from 10-90 torque percent, which is the range over which the rheometer is accurate, so the exact ranges of shear rate tested depended on the test fluid. The created solutions were compared to blood at the equivalent hematocrit and previously performed tests.The three different equivalent hematocrits all produced results similar to viscosities of blood. The results were similarly representative of blood at different equivalent viscosities for the 0.0075% xanthan gum and the 0.075% xanthan gum by weight. The solutions were able to mimic the shear thinning behavior of blood at different equivalent hematocrits. The fluids with 0.075% xanthan gum and 50% water and 50% glycerin is a better representative than the fluids with 0.075% xanthan gum and 60% water and 40% glycerin.