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Forward-view Endoscopic Optical Coherence Tomography for Needle-based Interventions
No full textNeedle-based interventions (NBIs) are procedures that require a minimally invasive approach
to gain access to tissue structures of interest. Each year, more than 30 million of these
interventions are performed in the US. Due to the lack of proper visual feedback guiding
navigation, up to 33% of NBIs are associated with complications, incurring significant human
and economic costs. The objective of my dissertation is to establish a new research paradigm
shift in the methodology of NBIs through integrating a unique forward-imaging multi-contrast
optical coherent tomography (MC-OCT) needle technology with advanced machine-learning-
based computer-aided diagnosis algorithms. Optical coherence tomography (OCT) is a novel
biomedical imaging technique which provides micron-level spatial resolution. Compared to
conventional imaging modalities, it provides the imaging results with a lot more details of
localized tissue. OCT has been widely used in various applications including ophthalmology,
biopsy procedures, different disease diagnosis, etc. Furthermore, OCT can perform real-time
imaging based on the high-speed scanner and data acquisitor. Therefore, OCT has the
potential in real-time guidance in different NBIs. To successfully acquire depth-resolved
imaging during surgeries, we developed forward-view endoscopic OCT systems using
gradient-index (GRIN) lenses. Additionally, we utilized polarization-sensitive OCT (PS-OCT)
and Doppler OCT to build MC-OCT for enhanced tissue contrast and at-risk blood vessels
detection. PS-OCT is a function extension of traditional OCT because it provides
polarization-related biological features based on birefringence and diattenuation phenomena.
Doppler OCT is effective in fluid flow imaging, so we utilized it for blood flow detection. By
introducing PS-OCT and Doppler OCT, our endoscopic MC-OCT systems have been proved to be feasible in recognizing different tissue type and blood vessels. In this dissertation, we
demonstrated endoscopic MC-OCT systems in surgical navigations in different NBIs
including percutaneous nephrostomy (PCN), epidural anesthesia, Veress needle for
pneumoperitoneum establishment, and different cancer diagnosis. To improve the working
efficiency and reduce learning curves, we further applied deep learning methods in our studies
to automate the navigation procedures. Different architectures were tested for tissue
classifications and blood vessel detections. This innovated imaging platform has established a
paradigm shift, offering the potential for widespread applications across various NBIs
Deconstructing American laughter: the power of carnivalesque humor to empower the voices of the oppressed
Get PDFMikhail Bakhtin's theory of the carnivalesque, as seen in his book Rabelais and His Word, highlights how laughter has the power to break through the restrictions and fear within oppressive, official cultures, giving power to the people. While Bakhtin's theory takes root within medieval France, the elements of the carnivalesque have thrived within cultures throughout the world where the voices of the oppressed fight to break through. This thesis analyzes American stories of the oppressed with a carnivalesque lens to see how their voices shine through in the promise of rebirth and rejuvenation with the power of laughter. Tabitha Tenney's Female Quixotism (1808) establishes a carnivalesque ambivalence to its picaresque humor and regenerative abuses, generating a back-and-forth discussion of the official and unofficial culture and creating a chance for the issues of feminism and power to be seen from multiple lens when certain voices might have been suffocated otherwise. Toni Morrison's Beloved (1987) contains moments of carnival joy and togetherness that can shine light in the darkness and even creates scenes of grotesqueness that send forth the promise of rebirth and rejuvenation, creating hope and the chance of an empowered future. Through the show Reservation Dogs (2021), Sterlin Harjo and Taika Waititi break down official images of Indigenous Americans created by the official culture, subvert expectations, and turn power structures on their head through comedy and laughter, creating a powerful coming-of-age story that can resonate with many. This thesis will seek to explore the carnivalesque elements of American laughter through various genres, examining how it fights through the seriousness of America's official culture, empowers the voices of the oppressed, and encourages the understanding of how humor can coincide with the serious to create healing and shed light on important issues
Apparitional Representations: Disability History, Reparative Descriptions, and Ethical Failings in a Special Research Collection
Get PDFIn this presentation, I discuss the process and outcomes of a reparative description project I undertook for my master’s thesis at the University of Oklahoma. My thesis focused on remediating disability-related descriptions in the Western History Collections. I examined a variety of theoretical models and attempted to apply them as I remediated descriptions. My presentation covers the challenges of trying to remediate descriptions in an archive not dedicated to disability history and provides a methodology for doing remediations that might help archivists struggling with incomplete information about items in a collection
OPTIMIZATION AND VALIDATION OF MAIA AEROSOL RETRIEVAL USING POLDER OBSERVATIONS
Get PDFNASA’s Multi-Angle Imager for Aerosols (MAIA) is a satellite-borne multi-angle polarimeter (MAP) instrument that aims to investigate the human health effects caused by exposures to various types of particulate matter (PM) and is anticipated to launch in 2025. The Step-1 aerosol retrieval algorithm deployed by MAIA is refined and tested by applying the algorithm to the data acquired by the satellite-borne instrument—POLarization and Directionality of the Earth's Reflectances (POLDER), and the results are compared with the ground-based Aerosol Robotic Network (AERONET) and retrieval of Generalized Retrieval of Aerosol and Surface Properties (GRASP).
To address the quilting effect observed across the edges of adjacent retrieval patches—each composed of multiple pixels that are retrieved simultaneously—a three-step strategy was implemented within the retrieval algorithm. As a significant part of this study, further advancement came with the development and integration of a neural network (NN) based radiative transfer and optics module, which has significantly accelerated the radiative transfer modeling process, increasing efficiency by three to four orders of magnitude without compromising modeling accuracy. The innovative use of automatic differentiation for the analytical Jacobian matrix calculation from the trained NNs has further accelerated computations and improved the precision of derivative estimations.
Accuracy assessments over MAIA's Los Angeles primary target area have shown that aerosol optical depth (AOD) retrievals are comparable to those from AERONET and GRASP-HP. Compared to AERONET reference AODs, the RMSEs of MAIA-NN based retrieval are 0.152, 0.050, 0.036, and 0.033 for wavelengths 565, 670, and 1020 nm, respectively. In contrast, the RMSEs of GRASP-HP based retrieval are 0.084, 0.084, 0.081, and 0.082, respectively. The three-step strategy not only mitigates the visual quality of aerosol maps but also substantially improves retrieval performance by enforcing physically plausible constraints. As a result, there was a RMSE performance enhancement for MAIA-NN retrievals, with a notable improvement of 49%, 59%, and 62% at 565, 670, and 1020 nm wavelengths, despite a slight 4.8% decrease at 440 nm.
Remarkably, the NN-based approach has proven to be more than 400 times faster than the traditional method, taking less than 1 second per pixel on average, indicating its transformative capability for near-real-time aerosol retrieval from MAP satellite data
Connections Between the Spectroscopy and Photometry of Type Ia Supernovae
Get PDFType Ia supernovae (SNe Ia) play a vital role in the study of many topics of astrophysics. They
act as cosmological probes through their well-established nature as precise standardizable candles.
This nature can be described empirically by the systematic relationship between the width of their
light-curve and their peak luminosity, otherwise known as the Phillips relation. As extragalactic
distance indicators, SNe Ia aid in constraining the nature of dark energy. SNe Ia also enrich the
universe with iron-group products, and provide insight into our understanding of stellar evolution as
a whole.
To fully and precisely take advantage of the standardizable properties of SNe Ia, their time
evolution must be fully understood, including the nature of their origin. Unfortunately, the exact
progenitor systems of SNe Ia are still uncertain and are a popular topic in the study of SNe Ia. The
different theorized progenitor scenarios and explosion mechanisms that SNe Ia undergo stem from
the diversity of their observable properties. Understanding the causes of the variation seen between
SNe Ia is imperative in minimizing the Hubble residual, which is used to deduce cosmological
parameters such as the Hubble constant.
Due to the complexities of supernova physics, the variation observed in SNe Ia are often
described using empirical models. Recent advances in statistical and machine-learning techniques
have led to models that provide useful constraints on theories that link observables to the underlying
progenitor system. Although the time-dependent nature of SNe Ia leads to difficulty in obtaining
large samples in order to treat observations statistically, recent surveys of astronomical transients
have led to sample sizes large enough such that modern machine-learning techniques can be applied.
The goal of this thesis is to use this increase in data available to create empirical models that
will aid in the classification and prediction of SN Ia properties, which will further constrain the
progenitor problem. Specifically, these models will be created using a combination of both observed
spectroscopy and photometry. In doing so, correlations between the two regimes are found which
are useful for constraining spectroscopic models and improving light-curve models of SNe Ia.
This thesis is organized in the following manner: Chapter 1 reviews the fundamental nature of
SNe Ia along with previously theorized progenitor systems and explosion mechanisms; Chapter 2
discusses the observational diversity of SNe Ia, including some of the relevant subtypes of SNe Ia
and the observational data used in empirical models created here; Chapter 3 details a cluster analysis
of a sample of SNe Ia that leads to a robust model for classifying SNe Ia; Chapter 4 reviews
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the light-curve-fitter SNooPy and, using SNooPy, illustrates the limitations of the color-stretch
parameter sBV in the near-infrared; Chapter 5 discusses a technique using principal component
analysis to extrapolate NIR spectra of SNe Ia using optical spectroscopy; Chapter 6 proposes a
method of modeling residuals from aforementioned extrapolations to more thoughtfully provide
correlated uncertainties for the application of light-curve calculations; Chapter 7 studies the principal
components from the extrapolation model in Chapter 5 in more detail, and relates them back to
the classification scheme defined in Chapter 3; finally, Chapter 8 provides a summary of the most
notable conclusions in this work
Survival in the Bible Belt: Oklahoman Queer Politics and Religion in the 1980s
Get PDFThis work follows the story of Oklahoma’s queer community in the 1980s through the lens of two community newspapers, The Gayly Oklahoman and Herland Sister Resources. The 1980s was an incredibly important decade for the queer community of Oklahoma. Gay-friendly religious organizations grew in number and size during this decade, and Oklahoman gay political organizations began to organize on a larger level than they had in previous years. Oklahoma's queer community did not experience growth and progress in the same way that the queer communities of other areas did. Oklahoma’s queer community existed in a very conservative and Christian state, and that affected the way the community grew and adapted. Queer Oklahomans had to adapt to the conservative climate they lived in as a strategy of survival. For them, this meant investing more in organizations that are usually marked as conservative and being willing to work with the conservative forces in the state. This also meant that things that are usually considered markers of progress for gay communities did not always manifest themselves in the same way in Oklahoma. Despite the situation that queer Oklahomans found themselves in, they were able to navigate an unfavorable cultural climate and adapt to that climate. It was an ongoing process, but they did make progress throughout the 1980s, as seen through the way the community newspapers discuss the community
*1 NEW NOTIFICATION*: SOCIAL MEDIA MISCONCEPTIONS AROUND TRIBAL ABORTION PROVISIONS AND INDIGENOUS METHODS OF REPRODUCTIVE JUSTICE AS PRAXIS
Get PDFMy thesis discusses the cultural and social misconceptions of possible tribal abortion provision by social media users in a post Roe setting. Through the analysis of social media posts and further the ideologies expressed by users on Facebook, my project breaks down the meaning and value assigned to Indigenous women regarding their reproductive actions. This assignment of both negative and positive value includes the perception of “proper” motherhood, acts of abortion or miscarriage, and forced sterilization through eugenic pseudoscience. In response to social media discourse and misrepresentations of abortion ideology towards Indigenous women, tribal communities themselves establish projects on social media to discuss thriving and community care such as support for the Indian Child Welfare Act and public education on cradle boarding. Overall, my thesis discusses the harmful implications of assumed tribal abortion provision by misinformed social media users and the methods of reproductive justice Indigenous users have developed to combat them
Brine Driven Alteration of Phyllosilicates
Get PDFThe sedimentary structures and mineralogy of the Martian surface record a complex and inconsistently active hydrosphere throughout the planet’s history (Bibring et al., 2006; Elwood Madden et al., 2009). Phyllosilicates in particular are useful for interpreting the influence water has had on the planet, and have been detected using remote sensing, as well as ground-based lander and rover analyses (Bishop, 2018; Bishop et al., 2008). On Earth, phyllosilicates have been studied extensively, not only because of their economic value, but also because they are a product of the fluids they formed in as well as the fluids they have been subsequently exposed to (Ayari et al., 2007; Kerr, 1952; McKinley et al., 1999).
The fluid chemistry of the Martian hydrosphere likely differed from Earth’s significantly, thus, interpretations of aqueous alteration derived from common terrestrial analogues may not fully reflect aqueous alteration on Mars. In the geologic past, Mars likely had a wetter (and possibly warmer) climate which transitioned into a present-day cold and dry climate (Carter et al., 2015). As water became increasingly restricted, fluids would have become increasingly briny. This desiccation would have led to temporally and spatially variable fluid chemistries, multiple aqueous alteration mechanisms, and therefore multiple pathways for alteration of phyllosilicates (Bristow et al., 2021).
This dissertation examines aqueous processes which may have influenced and/or continues to influence phyllosilicates on Mars. Through a series of investigations, techniques including X-ray diffraction (XRD), Environmental Scanning Electron Microscopy (ESEM), Raman spectroscopy and elemental fluid composition via Inductively Coupled Plasma – Optical Emission Spectrometry (ICP-OES) are used to determine the effects of brine exposure to kaolinite (Al2Si2O5(OH)4), nontronite (Na0.4FeIII2(Si3.6Al0.4)O10(OH)2), and montmorillonite (Na0.4(Al1.6Mg0.4)Si4O10(OH)2) (Essington, 2015).
Chapter 1 details two sets of experiments which were conducted to investigate how rock-fluid interactions on Mars could have facilitated precipitation of Ca-sulfate phases such as gypsum. It was found that brine concentration as well as the specific cation/anion pairing influenced cation exchange by montmorillonite. Chapter 1 has been published in The Planetary Science Journal (Geyer et al., 2023). In Chapter 2, ESEM was used to observe cation exchange facilitated by the deliquescence of a salt. A sample of montmorillonite mixed with a Na2SO4 or MgSO4 salt underwent a cycle where relative humidity was increased from 3% to 100% and back to 3%. During this relative humidity cycle, in the absence of liquid water, the salt deliquesced and exchanged Na+ or Mg2+ with the montmorillonite. As cation exchange occurred, the Ca2+ originally in the montmorillonite grain migrated out of the grain and formed new gypsum crystals. Chapter 2 has been submitted for publication in Clays and Clay Minerals and is currently under review. Chapter 3 investigated potential aqueous alteration of kaolinite by twelve brines at 25°C and 100°. It was found that an interdependent relationship exists between temperature and brine concentration which significantly influenced kaolinite alteration, specifically, the preferential Al release from the kaolinite. Finally, Chapter 4 details a similar set of experiments to those in Chapter 3, except the clays reacted were montmorillonite and nontronite. Here it was found that both illite formation during dissolution as well as preferential release of different elements by montmorillonite and nontronite was significantly influenced by temperature-brine dependent smectite alteration pathways
Understanding Emotionally Supportive Family Communication Individuals with MS Experience Through a Critical Interpersonal and Family Communication (CIFC) Framework
No full textEmotionally supportive communication (ESC) has been argued as the most valuable form of supportive communication, which the present study explores from the perspective of individuals living with multiple sclerosis (MS). MS is a chronic illness characterized by inflammation of the central nervous system (CNS). Generally diagnosed between the ages of 20 and 40, MS is characterized by uncertainty related to MS progression and symptoms, as the symptoms and experience of MS vary widely from person to person. For individuals living with MS (IwMS), ESC can be useful for navigating uncertainties and identity adaptation processes. Moreover, how IwMS may be associated with disability through living with MS could impact how they experience and perceive the ESC that they receive from others, especially family members who are formative for how IwMS adapt to MS. The present interview-based study investigated ESC using person-centered theory and a critical interpersonal and family communication (CIFC) framework to better understand the ESC IwMS experience from family members, their perceptions of such support, factors that IwMS consider for influencing their perceptions, and the role of power during emotionally supportive interactions where disability status may be influencing ESC from family members and IwMS perceptions. Analyzing interview transcripts with 25 IwMS revealed that (a) IwMS experience a wide-range of ESC, consider instrumental support as ESC, and experience a majority of ESC as moderately person-centered; (b) IwMS perceive ESC from family members along a continuum from negative to positive, including ambivalent perceptions of ESC specific to how MS impacts emotionally supportive interactions; (c) several factors influence IwMS’ perceptions of ESC from family members, including realities of living with MS, reflection, and relationship element among others; and (d) IwMS experienced relational and personal losses to power during emotionally supportive interactions with family members, as well as feeling pressure to perform specific roles for family members. Implications of findings and future directions conclude the study
Additive Manufacturing of Ti-64 Using Selective Laser Melting
Get PDFSelective Laser Melting (SLM) is an Additive Manufacturing (AM) process that is seeing adoption in many engineering industries, namely in biomedical, automotive, and aerospace applications. In this work, the capabilities of the General Electric (GE) Additive Concept M2 Series 5 Titanium Ti-64 Grade 23 SLM printer are characterized in a preliminary study to guide future research and processes at the Sooner Additive Manufacturing Laboratory (SAML). Ti-64 (90% titanium, 6% aluminum, 4% vanadium by weight) AM has become more accessible in the last decade and is of particular interest to the United States Air Force for fabricating replacement parts for aging aircraft. This work focuses on reviewing the Powder Bed Fusion (PBF) process and determining the bulk tensile properties of horizontally printed specimens using GE’s provided parameters while expanding the capabilities of the SAML to prepare it for additional testing. As printed samples were compared to all 3 of the Stress Relief (SR) options provided by GE alongside a study to evaluate the potential for shot peening using resources readily available in the laboratory. Samples were evaluated using Digital Image Correlation (DIC) during the loading processes and a universal testing system. Samples were shown to present properties similar to that of the provided GE specifications, but fell short of the published values for as printed and SR3 samples for the Balanced Parameter 114. In-house polishing processes were expanded to successfully present Ti-64 grain structures under optical microscopy and Scanning Electron Microscopy (SEM) by decreasing the final polishing particle size to 0.02 μm and including additional particle sizes during preparation (9 μm, 6 μm, 3 μm, 1 μm, 0.05 μm, 0.02 μm). Future work should and will include a larger sample size for each specimen type and utilize ASTM E8M specimens