It is becoming increasingly evident that the nanoscale organization and structure of macromolecules play a significant role in determining the function and properties of biological systems. To understand the relationships between biological structure and function at nanometer length scales, there is a need for methods which enable imaging of intact...
Stroke is the leading cause of death and long term disability in the industrialized world. With the current population aging, the number of individuals at risk of stroke along with the associated health care costs are anticipated to rise considerably in the coming years. Consequently, there is an unmet need...
Pattern recognition-based myoelectric control of upper limb prostheses has been made clinically available to individuals with more proximal upper limb amputations and can restore intuitive control of a prosthetic hand. This control method has yet to be implemented for individuals with amputations distal to the wrist (i.e. partial-hand amputations) and...
Myocardial perfusion is an important marker of cardiovascular health that is routinely evaluated clinically. Perfusion is measured most often using single photon emission computed tomography (SPECT) imaging, but magnetic resonance imaging (MRI) has many advantages over SPECT. Measuring perfusion quantitatively in ml/min/g would theoretically allow for improved characterization of cardiac...
Pattern recognition algorithms have been proposed as a way to control powered lower limb prostheses, specifically for transitioning between the different pre-programmed locomotion modes of the prosthesis (e.g., level ground walking, stair ascent, etc.). However, these algorithms cannot track changes in the statistical characteristics of input signals, and do not...
Even though renal blood flow accounts for nearly a quarter of cardiac output, the renal medulla operates in an environment with a scant supply of oxygen. The reason for this apparent discrepancy is thought to be threefold. Blood flow to the outer medulla is less than 50% of that received...
Glaucoma is a neurodegenerative blinding disease associated with increased intraocular pressure, which is caused by an increased resistance to the outflow of aqueous humor. Although the cause for increased resistance remains unknown, it has been associated with a decreased density of pores in the cells of the inner wall endothelium...
Spherical Nucleic Acids (SNAs) are nanoparticle bioconjugates that have found use in a wide-range of diagnostic and therapeutic applications. These nanomaterials are composed from inorganic or organic core nanoparticle scaffolds that are functionalized with a dense surface layer of nucleic acids (typically DNA or RNA) that are oriented in a...
A stroke can occur at any point throughout the lifespan, including in utero. The timing of the injury relative to neural development can have implications on the type of lesion, plasticity, and motor deficits. However, associated reactions, which refer to involuntary movement in one limb in response to voluntary activity...
Patients born with severe heart defects need regular monitoring of the complex hemodynamics in their heart and vasculature. 4D flow MRI has emerged as the state-of-the-art technique for comprehensively evaluating cardiovascular hemodynamics. This imaging technique allows for the dynamic visualization of 3D blood through the cardiac cycle and the quantification...
Over the past two decades, optical coherence tomography (OCT) has been successfully applied to various fields of biomedical researching and clinical studies, including cardiology, urology, dermatology, dentistry, oncology, and most successfully, ophthalmology. This dissertation seeks to extend the current OCT practice, which is still largely morphology-based, into a new dimension,...
Individuals with severe motor impairments often have a difficult time performing daily activities, and thus rely heavily on assistive devices to restore some functional independence. The two main limitations of the current controllers for assistive devices are: 1) controllers that do not require coordinated hand movement provide a limited vocabulary...
The role that spinal motion plays during ambulation is not clearly understood. Little in vivo regional spinal motion data exists in the literature with regard to walking and most gait models disregard the upper body altogether, or regard it as a single rigid structure. This study aims to increase understanding...
Commercially available electrically powered prosthetic elbows are stiff and unyielding. Making these artificial limb replacements more closely mimic human elbows by increasing their compliance may be beneficial. In addition to having increased compliance compared with current electrically powered prosthetic elbows, humans modulate the overall impedance of their joints. The author...
Magnetic resonance imaging (MRI) allows for the selective visualization of blood vessels via the intravascular injection of a paramagnetic contrast agent and the suppression of background signal. Called magnetic resonance angiography (MRA), this technique can produce three-dimensional images and is useful clinically for the noninvasive diagnosis of vascular disorders. In...
Intramuscular electromyograms (EMG) are believed to provide several potential advantages over surface EMG for multifunctional myoelectric prosthesis control. One example is the ability to focally record from deep muscles of the forearm. However, intramuscular EMG has rarely been investigated due to the inability to obtain chronic recordings. New technology is...
Age-related maculopathy (ARM) is a leading cause of legal blindness in the elderly in the world. Currently, the physiological and ultrastructural bases for the development of ARM remain unclear. Many studies have proposed that the morphological changes, particularly the accumulations of lipids with aging, in Bruch's membrane - an extracellular...
Conventional perfusion magnetic resonance imaging with dynamic susceptibility using a contrast agents has been playing a dominant role on diagnosing a variety of cerebral nervous system disease due to lack of radiation and widespread availability. However, reliable quantification of cerebral perfusion has been elusive and challenging.
The bookend method is...
A need exists to increase the functionality of myoelectric prostheses without increasing the mental requirement of operation. Implantable myoelectric sensors have made it possible to record multiple muscle activities with high fidelity. Given this high dimensionality of inputs, what is the best way of implementing control? Muscle synergies have been...
During interactions with our environment we must incorporate information about the mechanical properties of obstacles into our motor actions. Fundamental to these behaviors is the ability to simultaneously control movements of the hand while regulating the interaction forces that arise from contact with the environment. Although the neural control of...