Digital Commons Network^™

Characteristics Based Factor Models - Comparison Of Estimation Procedures, Henri Ohl

McKelvey School of Engineering Theses & Dissertations

Understanding cross-sectional and time series variation of asset returns is fundamental in finance, particularly in asset pricing. This thesis explores the integration of factor theory with machine learning to deepen our comprehension of these dynamics. Characteristics based factor models offer a systematic framework for quantifying an asset's underlying risk-return structure, leveraging time-varying conditional information on model parameters carried by firm-specific characteristics. These models serve as valuable tools for discerning the driving components of an asset's expected excess return. Recent research established a novel methodology for consistent parameter estimation within this framework, only requiring a large cross-section but not a long …

Mending Trust In Ai: Trust Repair Policy Interventions For Large Language Models In Visual Data Journalism, Hangxiao Zhu

McKelvey School of Engineering Theses & Dissertations

Trust in Large Language Models (LLMs) emerged as a pivotal concern. This is because, despite the transformative potential of LLMs in enhancing the interpretability and interactivity of complex datasets, the opacity of these models and instances of inaccuracies or biases have led to a significant trust deficit among end-users. Moreover, there is a tendency for people to personify AI tools that utilize these LLMs, attributing abilities and sensibilities that they do not truly possess. This thesis exploits this personification and proposes a comprehensive framework of trust repair policies tailored to address the challenges inherent in LLM annotations within data journalism …

Fabrication Of Two-Dimensional Material-Based Nano-Capacitors Using Bismuth Selenite (Bi2seo5) To Study Its Dielectric Properties, Major Kc

McKelvey School of Engineering Theses & Dissertations

In recent years, the demand for high-performance micro and nanodevices has surged, necessitating the exploration of novel dielectric materials to replace conventional silicon dioxide. Following the continuation of the Moorse law, as device dimensions reduce to nanoscale levels, the properties of silicon dioxide can degrade, leading to issues such as increased leakage current and reduced gate control. Materials with superior electrical properties, such as higher dielectric constant, lower leakage current, and better thermal stability allowing for the development of faster, more efficient, and more reliable devices are in higher demand than ever. Two-dimensional layered semiconductor nanomaterials represented by compounds such …

Integrating Implantable Bci Devices Within Bci2000 Using A Unified Framework And Toolchain For In-Vivo Research, Dhruva Mehta

McKelvey School of Engineering Theses & Dissertations

The field of neurotechnology research has a bright and promising future as more devices are created. However, there are still many gaps in the field as the potential for neuromodulation grows. Devices such as the Micro-Leads StimZ system and the Ripple Grapevine/Summit system help bridge that gap by allowing for a broader variety of closed-loop neuromodulation experiments to be implemented thanks to their portability and versatility. Despite these devices being on the market, however, there needs to be a method to collaborate and interact with them across multiple research institutions. BCI2000 helps to address that by creating a standardized working …

Evaluating Neuroimaging Modalities In The A/T/N Framework: Single And Combined Fdg-Pet And T1-Weighted Mri For Alzheimer’S Diagnosis, Peiwang Liu

McKelvey School of Engineering Theses & Dissertations

With the escalating prevalence of dementia, particularly Alzheimer's Disease (AD), the need for early and precise diagnostic techniques is rising. This study delves into the comparative efficacy of Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) and T1-weighted Magnetic Resonance Imaging (MRI) in diagnosing AD, where the integration of multimodal models is becoming a trend. Leveraging data from the Alzheimer's Disease Neuroimaging Initiative (ADNI), we employed linear Support Vector Machines (SVM) to assess the diagnostic potential of these modalities, both individually and in combination, within the AD continuum. Our analysis, under the A/T/N framework's 'N' category, reveals that FDG-PET consistently outperforms T1w-MRI across …

Investigating Murine Uterine Tissue Dynamics: Biomechanical And Histological Perspectives On Postpartum Involution And Scar-Induced Remodeling, Savannah Elizabeth Chatman

McKelvey School of Engineering Theses & Dissertations

During pregnancy, the uterus undergoes structural and mechanical transformations to withstand the demands of a successful delivery. In cases where vaginal birth is not feasible, a Cesarean section (c-section), which involves a transverse abdominal incision, is used to facilitate delivery of the fetus and placenta¹. Following the procedure, the uterus and abdominal tissue are carefully sutured to support postpartum recovery, leading to uterine scarring at the incision site^1,2. Understanding the relationship between uterine scar integrity, postpartum involution, and the biomechanics of uterine tissue is a crucial step toward predicting the risk of uterine rupture during future …

Numerical Simulations Of Supersonic/ Hypersonic Flows In Compression Corners And A Hypersonic Flow Study Of Atmospheric Entry Of Mars Science Laboratory Capsule, Dexter Allen

McKelvey School of Engineering Theses & Dissertations

This thesis consists of two related parts. The first part is the study of supersonic/hypersonic flow in compression corners. The compression corners are simple geometries but rich in flow-features that can be challenging for accurate prediction of their flow fields in high-speed compressible flow using the Reynold-Averaged Navier-Stokes (RANS) equations in conjunction with a turbulence model. At higher degrees of corner angles, there exists a shock-boundary layer interaction region which includes a significant recirculation zone in the corner. In this thesis, experimentally available test cases for compression corner at Mach 3, 8, and 11 at various corner angles are modeled …

The Role Of Voluntary Descending Control In Enhancing Motor Function Via Transcutaneous Spinal Cord Stimulation, Yoon Kim

McKelvey School of Engineering Theses & Dissertations

Spinal cord injury (SCI) is a life-changing event that causes lasting motor impairments. Transcutaneous spinal cord stimulation (tSCS), a non-invasive form of neuromodulation in which electrodes are placed on the skin and used to stimulate the spinal circuits via an electrical current, has demonstrated positive effects on motor function recovery in individuals who have had SCIs. However, the precise mechanism of how tSCS interacts with voluntary descending drive remains poorly understood. This study aims to investigate the role of voluntary descending control in influencing reflex responses triggered by tSCS.

Electromyography (EMG) recordings were performed in ten unimpaired individuals while they …

Development Of A Wearable Short-Wave Infrared Photoplethysmography Device For Detection And Monitoring Of Hemodilution During Postpartum Hemorrhage, Hannah Gruensfelder

McKelvey School of Engineering Theses & Dissertations

ABSTRACT OF THE THESIS

A Thesis on the Development of a Wearable Short-Wave Infrared Photoplethysmography Device for Detection and Monitoring of Hemodilution During Postpartum Hemorrhage

by

Hannah Gruensfelder

Master of Science in Biomedical Engineering

Washington University in St. Louis, 2024

Professor Christine O’Brien, Chair

Postpartum hemorrhage (PPH), the leading cause of maternal death and morbidity, affects nearly 14 million people worldwide each year, disproportionally impacting racial minorities and people in low resource settings. A timely diagnosis of PPH is key in providing optimal patient care, as an estimated 90% of deaths due to PPH are preventable with early diagnosis and …

Environment And Response Of 3d-Encapsulated Mesenchymal Stem Cells To Mechanical Loading, Augustus Greenwood

McKelvey School of Engineering Theses & Dissertations

This thesis explores the micromechanical environment induced when cyclically compressing hydrogels via finite element modeling and experimentally on the impact of loading on mesenchymal stem cells (MSCs) when encapsulated withing 3D hydrogel matrices. Degenerative joint diseases, characterized by cartilage degradation, present significant challenges due to cartilage's limited self-repair capacity. Innovative approaches, including stem cell-based therapies and engineered biomaterials, have emerged as promising strategies for cartilage repair and regeneration. This work specifically investigates the calibration of a bioreactor, the uniformity of load response across the hydrogel constructs via finite element modeling (FEM), and the stress response of MSCs subjected to various …

Modeling Of Nk Cells In Pediatric Patients With Unusually Severe Or Recurrent Hsv Using High-Dimensional Flow Cytometry, Yunran Feng

McKelvey School of Engineering Theses & Dissertations

HSV infection is broadly spread all over the world with some patients having severe and/or recurrent HSV infections. Our lab studies human Natural Killer (NK) cells, which are important in innate immune responses to viral infections and tumors. A publication in 2013 by Ornstein et al from our lab studied HSV+ pediatric patients and found some associations between severe infection and defects in NK cytolytic function. PLCG2 haploinsufficient variants found in 2 HSV patients causing PLCγ2 hypophosphorylation, and loss of cytolytic function in NK cells is a novel finding recently published by Alinger et al from our lab in 2023. …

Low Impedance, Durable, Self-Adhesive Hydrogel Epidermal Electrodes For Electrophysiology Recording, Naiyan Wu

McKelvey School of Engineering Theses & Dissertations

Traditional electrodes used for electrophysiology recording, characterized by their hard, dry, and inanimate nature, are fundamentally mismatched with the soft, moist, and bioactive characteristics of biological tissues, leading to suboptimal skin-electrode interfaces. Hydrogel materials, mirroring the high water content and biocompatibility of biological tissues, emerge as promising candidates for epidermal electronic materials due to their adjustable physicochemical properties. However, challenges such as inadequate electrical conductivity, elevated skin impedance, unreliable adhesion in moist conditions, and performance decline from dehydration have significantly restricted the efficacy and applicability of hydrogel-based electrodes. In this thesis, we report a high-performance hydrogel epidermal electrode patch for …

Information-Rich 6d Single-Molecule Imaging Design Using Optimization, Tingting Wu

McKelvey School of Engineering Theses & Dissertations

When studying biochemical processes, localizing the targets alone will not paint a complete picture. We also need techniques to probe how biomolecules interact with one another, including how molecules are organized into larger structures, how they are oriented with respect to surrounding molecules, and how local chemical parameters, like pH and hydrophobicity, vary spatially and temporally. My dissertation focuses on single-molecule orientation localization microscopy (SMOLM, Chapter 1). The objective is to develop imaging techniques for measuring how molecules are oriented with respect to their surrounding molecules, namely, 3D orientation. Achieving optimal imaging performance requires careful design of both the forward …

Multi-Layer Strip Ionization Chamber For Proton Quality Assurance And Imaging, Shuang Zhou

McKelvey School of Engineering Theses & Dissertations

Proton therapy is the most advanced radiation treatment modality. Proton treatment is delivered via pencil beam scanning (PBS) technique, in which a pencil beam scans the target spot-by-spot and layer-by-layer. An effective quality assurance (QA) device is needed to verify the quality of treatment dose delivery. Current clinical practice employs films or a two-dimensional (2D) detector to measure the dose at one or a few arbitrarily selected depths, which is insensitive to delivery error and time-consuming. A 3D dosimeter that can measure the 3D dose distribution is needed to improve the effectiveness and efficiency of proton QA. Furthermore, preclinical studies …

The Development And Validation Of Novel Imaging Biomarkers For Uterine Contraction, Cervix And Placenta In Pregnancy, Wenjie Wu

McKelvey School of Engineering Theses & Dissertations

Annually, nearly half a million neonates in the United States and 15 million globally are born preterm, defined as prior to 37 completed weeks of gestation. These births present elevated risks of neonatal mortality and long-term neurological deficits. The predominant obstetric precursors of preterm birth (PTB) include spontaneous preterm labor (45%), medically-indicated deliveries (30%), and preterm premature rupture of membranes (PPROM, 25%). Each precursor is associated with distinct physiological or structural alterations such as uterine contractions, placental dysfunction, or cervical insufficiency. Current methodologies for monitoring uterine contractions, such as intrauterine pressure catheters and electrohysterography, possess limitations in spatial resolution, coverage, …

Divergent Self-Assembly Of Block Heterochiral Stereoisomer Arrays, Conor Louis O'Neill

McKelvey School of Engineering Theses & Dissertations

The autonomous organization of parts into ordered architectures, or biomolecular self-assembly, is an elementary natural process that defines and guides the construction and function of living organisms. This phenomenon has emerged as a potent tool for the creation of novel biomaterials, with peptide-based instances benefitting from intrinsic modularity, ease of de novo design and synthesis, biocompatibility, and chemical versatility. These properties enable methodical modifications that generate suprastructures with a wide variety of morphologies and functionalities, supporting a broad range of biomedical applications. Further, the chiral nature of amino acids permits synthesis of either left- or right-handed peptides; in recent years, …

Improving And Integrating Quantitative Single Cell Spatial Biology For Theranostic Medicine, Peng Lu

McKelvey School of Engineering Theses & Dissertations

Disease states are the result of a complex interplay of many different cell types interacting in close proximity in the context of often heterogeneous tissues. Alpha particles are drawing intense research and clinical interest because of their potent cytotoxic effects and their short path lengths. Analyzing the dose distribution and tissue micro-environment for alpha therapy plays a key role in predicting the efficacy of this targeted radiotherapy. However, to date there have been no direct on-tissue analytical methods for alpha dose distributions and the corresponding tissue microenvironments. Therefore, we have developed a pipeline to overcome this limitation by utilizing quantitative …

Mechanisms And Prevention Of Antibiotic Resistant Organism Spread In Hospitals, Erin P. Newcomer

McKelvey School of Engineering Theses & Dissertations

Our quest as a species to treat and prevent disease has led us to develop medical care that would have been inconceivable even one century ago. However, as we learn to overcome previous roadblocks, new hurdles that we hadn’t even considered continue to present themselves. Once we learned to understand the germ theory of disease, we sought treatments for infectious diseases, which led us to the development of antibiotics. Antibiotics are responsible for saving countless lives and have ushered in the advances in other fields of medicine like cancer treatment and surgery. Now, antibiotic resistance threatens our ability to treat …

Estimating And Detecting Slow-Wave Events In Eeg Signals, Zhenghao Xiong

McKelvey School of Engineering Theses & Dissertations

Slow wave activity (SWA) is an electroencephalogram (EEG) pattern commonly occurring during anesthesia and deep sleep, and is hence a candidate biomarker to quantify such states and understand their connection to various phenotypes. SWA consists of individual slow waves (ISW), high-amplitude deflections lasting for approximately 0.5 to 1 second, and occurring quasi-periodically. This latter fact poses a challenge for conventional power spectral density EEG analysis methods that perform best when there is persistency of oscillatory activity. In this work, we pursue a time-domain detection framework for identifying and quantifying ISWs as a metric for SWA. Our method works, in essence, …

Superconducting Non-Reciprocity Based On Time-Modulated Coupled-Resonator Systems, Yi Zhuang

McKelvey School of Engineering Theses & Dissertations

No abstract provided.

Modeling Of Functional Gene Regulation Through Machine Learning And Deep Learning Methods, Yuhao Chen

McKelvey School of Engineering Theses & Dissertations

Genes are specific sequences of nucleotides within the genome that undergo transcription to generate products that can diffuse throughout the cell. These gene products can take the form of either proteins or RNAs and play crucial roles in virtually all cellular functions, encompassing structural support, enzymatic activities, and signaling functions. An essential focus of contemporary biological research revolves around unraveling the functions of genes and their resulting products across different organisms. One primary means to conduct this research is through the regulation of gene expression. MicroRNAs (miRNAs), short single-stranded non-coding RNAs, play vital roles in gene expression regulation. Both computational …

Commercial Adsorbents For Co2 Removal For Biogas Upgradation: An Experimental Study, Aakriti Bagla

McKelvey School of Engineering Theses & Dissertations

No abstract provided.

Advanced Diffusion Mri Technique And Applications In Placenta And Brain, Zhexian Sun

McKelvey School of Engineering Theses & Dissertations

Among a series of contrasts of MRI, diffusion MRI (dMRI) is different from conventional MRI by its ability to capture information about the random movement of water molecules and their interaction with local tissue microstructures. This capability holds the potential to reveal intricate subvoxel microstructural information linked to pathological changes, offering potential imaging biomarkers. A higher-order diffusion analysis model helps to yield more accurate and specific parameters but requires more extensive parameter tuning and higher image quality. In this study, we firstly fine-tuned the previously developed diffusion basis spectrum imaging (DBSI) method to strike a balance between efficiency and accuracy …

The Effect Of Material Nonlinearity On Stress Concentrations At A Bi-Material Interface, Jin Qian

McKelvey School of Engineering Theses & Dissertations

No abstract provided.

Real-Time Analysis Of Aerosol Size Distributions With The Fast Integrated Mobility Spectrometer (Fims), Daisy Wang

McKelvey School of Engineering Theses & Dissertations

The Fast Integrated Mobility Spectrometer (FIMS) has emerged as an innovative instrument in the aerosol science domain. It employs a spatially varying electric field to separate charged aerosol particles by their electrical mobilities. These separated particles are then enlarged through vapor condensation and imaged in real time by a high-speed CCD camera. FIMS achieves near 100% detection efficiency for particles ranging from 10 nm to 600 nm with a temporal resolution of one second. However, FIMS’ real-time capabilities are limited by an offline data analysis process. Deferring analysis until hours or days after measurement makes FIMS' capabilities less valuable for …

An Apparatus To Quantify Lengthwise Flexural Rigidity Profiles Of Endovascular Devices, Charles B. Suskin

McKelvey School of Engineering Theses & Dissertations

Endovascular procedures require access to distal anatomical sites through the vasculature using catheters and guidewires. Quantitative frameworks for device behavior during procedures hold the potential to drive device design through greater understanding of the mechanical behavior of endovascular devices, and offer the potential to personalize care based on a patient's particular vascular anatomy. However, data that would facilitate this technology are lacking, partly due to undisclosed material properties from manufacturers and partly due to the intricate variations along the length of each device due to material changes and the intersections between them. We developed a three-point bend test methodology on …

Enhanced Fabrication Of Microdroplet Generator Nozzle Arrays: Optimizing Koh Etching For Microfluidic Applications, Hongyu Bai

McKelvey School of Engineering Theses & Dissertations

Ultrasonic microdroplet generators are useful devices with broad applications ranging from aerosolized drug delivery to three-dimensional (3D) printing-based additive manufacturing. One such technology comprises a microfabricated array of nozzles with droplet production driven by a piezoelectric transducer. The present study focuses on refining a critical fabrication step, anisotropic wet etching of pyramidal nozzles using a basic potassium hydroxide (KOH) solution. Given the integral role of nozzle geometry in device operation, high-precision techniques including Reactive Ion Etching (RIE), Deep Reactive Ion Etching (DRIE), and KOH wet etching were employed. A tapering geometry is preferred for acoustic wave focusing and efficient droplet …

Design Of Human Serum Albumin And Adenovirus Conjugation Via Catcher/Tag Molecular Glue, Peijie Zhao

McKelvey School of Engineering Theses & Dissertations

Adenovirus (Ad) has been the ideal cargo delivery mechanism, and its moderate immunological response makes it ideal for in vivo gene therapies since its discovery in 1953. However, the robust immunogenicity of the Ad capsid and low vaccine absorption via mucous membranes and epithelium put a limit on the process of developing intranasal vaccines. Efforts are being made to enhance the effectiveness of Ad vectors and numerous studies have demonstrated the remarkable capacity of human serum albumin (HSA) to extend plasma half-life and facilitate targeted intranasal delivery. In this study, we devised an innovative method for employing the Catcher/Tag molecular …

Improving And Integrating Quantitative Single Cell Spatial Biology For Theranostic Medicine, Peng Lu

McKelvey School of Engineering Theses & Dissertations

Disease states are the result of a complex interplay of many different cell types interacting in close proximity in the context of often heterogeneous tissues. Alpha particles are drawing intense research and clinical interest because of their potent cytotoxic effects and their short path lengths. Analyzing the dose distribution and tissue micro-environment for alpha therapy plays a key role in predicting the efficacy of this targeted radiotherapy. However, to date there have been no direct on-tissue analytical methods for alpha dose distributions and the corresponding tissue microenvironments.

Therefore, we have developed a pipeline to overcome this limitation by utilizing quantitative …

Development And Application Of Tools And Methods For Behavioral And Neural Recordings In Locusts, Michael R. Traner

McKelvey School of Engineering Theses & Dissertations

Locusts are a historically important model organism, and have been at the core of many discoveries related to olfaction. In recent years they have become less popular compared to organisms with genetic toolkits such as drosophila, but they have many advantages for studying principles of olfactory chemosensation and related behaviors. In this thesis there are two primary focuses; the development of a surface-bound odorant treadmill (odor-trail treadmill) for studying trail-following behaviors, and the second is the development of tools and procedures to enable simultaneous neural and behavioral recording in locusts. Addressing the first, odor-trail following has been observed in many …