Engineering Commons^™

Application Of Engineered Porosity And Modified Effective Moduli To The Design Of Orthopaedic Implants, John Anthony Choren

Dissertations (1934 -)

Commercially available orthopaedic implants have a bending stiffness (flexural rigidity) that is at least 10 times greater than cortical bone. Effects of this stiffness mismatch have been extensively studied relative to total hip arthroplasty (THA). Clinical experience with THA has shown that stiffness mismatch is the primary cause of accelerated bone resorption due to the stress shielding, resulting in sub-optimal bone loading, aseptic loosening and inadequate bone support for a future revision implant.

Attempts to incorporate design features that reduce the flexural rigidity of implants have yielded inconsistent results or failures due to biomaterial incompatibilities and practical manufacturing complications. The …

Investigation Of Spatio-Temporal Effects Of Fmri Visual Field Mapping Techniques On V1, John J. Janik

Dissertations (1934 -)

Blood oxygenation level dependent functional magnetic resonance imaging has been used extensively for mapping the representation of the visual field within the human brain. Visual field mapping using fMRI has been used clinically to assess patients with cortical pathology and to plan surgical treatment impacting the visual system. The accuracy of fMRI-based visual field mapping methods needs to be better understood for clinical use. This accuracy can be important for presurgical mapping of brain function near a tumor resection site since inaccurate rendition of the underlying neural function could lead to inappropriate resection of viable brain tissue. The most widely …

Incorporating The Aortic Valve Into Computational Fluid Dynamics Models Using Phase-Contrast Mri And Valve Tracking, David C. Wendell

Dissertations (1934 -)

The American Heart Association states about 2% of the general population have a bicuspid aortic valve (BAV). BAVs exist in 80% of patients with aortic coarctation (CoA) and likely influences flow patterns that contribute to long-term morbidity post-surgically. BAV patients tend to have larger ascending aortic diameters, increased risk of aneurysm formation, and require surgical intervention earlier than patients with a normal aortic valve. Magnetic resonance imaging (MRI) has been used clinically to assess aortic arch morphology and blood flow in these patients. These MRI data have been used in computational fluid dynamics (CFD) studies to investigate potential adverse hemodynamics …

Quantitative Evaluation Of Redox Processes In Intact Rat Lungs And Endothelial Cells And The Effect Of Hyperoxia, Zhuohui Gan

Dissertations (1934 -)

A common initial treatment of hypoxemia in patients with lung failure secondary to acute lung injury (e.g., adult respiratory distress syndrome) is oxygen (O₂) therapy (hyperoxia). However, prolonged O₂ therapy causes lung O₂ toxicity, which can further impair lung functions. The rat model of lung O₂ toxicity replicates key features of human lung O₂ toxicity. In addition, rats develop tolerance or susceptibility to 100% O₂ by pre-exposing them to 85% O₂ (hyper-85) or 60% O₂ (hyper-60) for 7 days, respectively. Therefore, the long-term objectives of this study are to elucidate mechanisms …

Sensorimotor Control Of 3d Arm Movement And Stability In Post-Stroke Hemiparesis, Kakanand Alfonsomarie Srungboonmee

Dissertations (1934 -)

Deficits of the affected arm in people with post-stroke hemiparesis have been generally associated with decreased strength and increased spasticity. These deficits are varied in proximal (shoulder) and distal (elbow) joints which results in an overall impairment during movement or during stabilization of hand position in space. In this study, reaching of the hemiparetic arm in 3D workspace was characterized by a curved and non-smooth endpoint trajectory and a reduced functional range of motion, compared to the unimpaired arm. Smoother trajectories were observed in the acceleration phase more than the deceleration phase, which was common to both the stroke subjects …

Detection Of Specific Biological Antigens Using Ac Electrochemical Impedance Spectroscopy, Darrel Angelo Mazzari

Dissertations (1934 -)

When certain antigens are present in our environment, a rapid, on-site, accurate, selective, and repeatable detection method can be invaluable in preventing illness or saving lives. Rapid detection of these antigens is important to avert spreading infections.

Currently, capturing a sample and sending it to a laboratory can take weeks to get results, which can be much too long. Conventional sensing methodologies include various electrical measurements as capacitive, potentiometric, piezoelectric, surface plasmon resonance (SPR), and quartz crystal microbalance (QCM). Of particular power and interest is Alternating Current (AC) Electrochemical Impedance Spectroscopy (EIS) which provides for the characterization of the electrical …

The Dominant Role Of The Hip In Multijoint Reflex Responses In Human Spinal Cord Injury, Tanya Onushko

Dissertations (1934 -)

Following a spinal cord injury (SCI), people often experience exaggerated reflexes, such that mild provocations can cause prolonged and uncontrolled muscle activity throughout the entire leg. These reflexes can be problematic and are known to interfere with functional tasks, such as transferring to and from a wheelchair, and they may interfere with locomotor function by prolonging muscle activity and/or inappropriately activating muscles during attempts to walk. While these multijoint reflexes have been shown to originate from several afferent cues, hip afferent input is a particularly potent sensory signal that readily triggers multijoint reflexes. The overall objective of this dissertation was …