Creighton Theses and Dissertations

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https://cdr.creighton.edu/handle/10504/51

Graduate School

Dr. Barron Breland, DM
Dean, Graduate School
Vice Provost, Faculty and Academic Affairs

Contacts:

LuAnn Schwery
Assistant Dean
schwery@creighton.edu
(402) 280-2772		 Taunya Plater
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tplater@creighton.edu
(402) 280-2870


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To request a copy of an embargoed theses or dissertation, please contact cdr@creighton.edu.

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Recent Submissions

Now showing 1 - 5 of 2269
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    The Rat as a Translational Model of Neurotrauma: Primary Somatosensory Input and Imaging Biomarker Validation Following Spinal Cord and Peripheral Nerve Injuries
    (Creighton University, 2024) McCann, Margaret Mary
    Neurotrauma is a leading cause of death and disability worldwide. Trauma is inherently chaotic and difficult to study, necessitating the use of translational models that provide standardizable and quantifiable models of injury. Rats are the most commonly used models of spinal cord (SCI) and peripheral nerve (PNI) injuries because their anatomy and physiology approximates that of humans, while their size and management make them economical and practical for large scale studies. Although the CNS does not regenerate, the peripheral nervous system does. One recent strategy under investigation for SCI patients is to use nerve grafts to restore function to spinal levels below the site of lesion. Questions remain about the suitability of rodent models for studies focused on higher order, complex, spinal tracts. Furthermore, questions remain on the best methods to track recovery following nerve graft or injury, as current diagnostic and prognostic clinical tools are limited. Diffusion MRI (dMRI) has the potential to classify nerve injury severity and evaluate nerve recovery more accurately and earlier in time than current electrodiagnostics but requires validation. In this study, we evaluated the rat’s suitability as a translation model of sensory injury and recovery within the corticospinal tract (CST), the tract which controls fine hand function in primates. We chose this tract because restoration of hand function is the most cited goal among quadriplegics. Additionally, we developed and tested a method to help validate and evaluate advanced dMRI biomarkers of PNI. Our long long-term goal is to use dMRI to quantify nerve injury and recovery to aid clinical decision making and aid prognostication following PNI. We found that rats display a similar response to primates and are suitable translational models for basic questions regarding the CST’s response to a sensory dorsal root-dorsal column SCI. Additionally, using a novel nerve-specific tissue clearing and innumolableing method we developed, we were able to track axons and derive a quantitative measure of the 3D histological structure of injured nerves, called a structure tensor. We show this measure correlates to the fractional anisotropy we acquired from dMRI within our clinically relevant cut-repair PNI model. Together, this lays the foundation for future clinical validation and translation of these novel imaging biomarkers of nerve injury and recovery.
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    Interagency Collaboration of Agencies Supporting Homeless Veterans
    (Creighton University, 2024) Spencer-Ragland, Brenda
    Efforts to prevent veteran homelessness in the United States have been ongoing for decades, yet thousands of veterans still face homelessness daily. This case study explores collaborative leadership efforts among nonprofit and government agencies aimed at preventing homelessness among veterans. The research question asks how nonprofit agencies serving homeless veterans in a rural southwest community describe their interagency collaborative practices. Interviews with agency leadership, observations of meetings, and documents of meeting minutes were analyzed for codes, categories, and themes. The findings revealed five themes. 1) Agencies serving homeless veterans in a rural southwest community have a shared mission of veteran homelessness prevention. 2) Agencies serving homeless veterans in a rural southwest community need a community-wide strategic plan. 3) Agencies serving homeless veterans in a rural southwest community have positive interactions. 4) Agencies serving homeless veterans in a rural southwest community are reactive. 5) Agencies serving homeless veterans in a rural southwest community have an elementary understanding of collaboration. Recommendations for positive change included making collaborative leadership an essential component for community-wide impact for agencies serving homeless veterans; agencies serving homeless veterans must enhance communication and data sharing and fully integrate the Homeless Management Information System (HMIS); and agencies serving homeless veterans must establish SMART performance measures for the Mayor’s Task Force.
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    Quantification of the Distribution of Forward and Backscattered Second Harmonic Generation by Collagen for the In Vivo, Optical Biopsy of Skin Cancer
    (Creighton University, 2024) Schloman, Hannah
    Skin cancer is the most common type of cancer, and its detection relies heavily on visual observation. The goal of this research is to aid in the progress of developing a non-invasive optical biopsy based on endogenous fluorescence and non-linear light scattering that can be used to detect skin cancer. A trial was conducted that followed 30 UV- and sham-exposed SKH1 mice over a 6-month period. Collagen images were obtained by using second harmonic generation. In this process pulsed 740 nm Ti:sapphire laser light was incident on the collagen in the mouse's dermis where two photons were converted into a single photon that had twice the energy. We were able to collect and spatially resolve the light that was emitted by using a confocal detector allowing us to obtain collagen images. A stack of images obtained with a variable confocal aperture were acquired so that we could measure the forward to backward (F/B) ratio of the SHG light. This measurement gives a way to quantify the light scattering by collagen fibers that are present within the skin and can be used as a diagnostic tool. Over the duration of the experiment, protocols were developed and implemented for imaging SKH1 mice. Collagen images were analyzed to measure the F/B ratio. The measured F/B ratios were compared across treatment groups and sex. The F/B ratios for male mice were higher than female mice. The results also showed that sham-exposed female mice had a higher F/B ratio than UV-exposed female mice. However, sham-exposed male mice had a slightly lower F/B ratio than UV-exposed male mice. On one day, two SHG stacks were acquired in the same mouse in different tissue types. One of the locations was in an area of cancerous tissue and the other was in healthy tissue. When these two SHG stacks were compared, it was found that the F/B ratio for the area of cancerous tissue was significantly lower than that of the healthy tissue. While these results are promising, more experiments need to be conducted comparing the F/B ratio in cancerous tissue with healthy tissue in the same mouse.
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    Dynamic Light Scattering in Alkali Borate Glass Melts Near the Glass Transition
    (Creighton University, 2024) Uppala, Harsh Gopee Krishna
    The study of glass-forming liquids and their properties is of fundamental importance in materials science and engineering, as glasses have unique properties that make them useful for a wide range of applications. Among the different types of glasses, borate glasses are particularly interesting due to their low melting temperature, high chemical durability, and potential for optical and electronic applications. However, the properties of borate glasses are strongly influenced by their dynamics, which are difficult to study using conventional techniques. Photon correlation spectroscopy (PCS) is a powerful tool that allows the study of the dynamics of liquids at the molecular scale. In this thesis, we investigate the dynamics of alkali borate glass melts using PCS, with the aim of understanding how the molecular rearrangements affect the structural and physical properties of these glasses.
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    Upgrades to the eSTARlight Monte Carlo Event Generator
    (Creighton University, 2024) Devi, Neha
    The Electron-ion collider (EIC) is a collider under development at Brookhaven National Laboratory, expected to be operational in 2033. An electron-ion collision can produce a range of particles including vector mesons. The eSTARlight Monte Carlo event generator simulates these collisions and calculates the cross sections of vector meson production reactions. This thesis describes the upgrades I made to eSTARlight for better simulation of electron-ion collisions. Since the cross-section of reactions is sensitive to the density models used to define the detailed shape of nuclei, I implemented updated nuclear density distribution models for more accurate predictions. Additionally, I added the excited ρ(1450) meson production and decay channel in eSTARlight based on calculations by Lomnitz and Klein [4]. I then used this channel in eSTARlight to estimate the number of excited rho mesons that would hit the planned ePIC detector in anticipated running at the EIC. The ePIC detector acceptance was calculated and also the expected number of excited rho mesons detected. Finally, I implemented updated parametrizations for the energy dependence of the production cross section [32] to get more accurate predictions of the excited rho meson production cross section.