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549 Matching Results

Start Over Partner UNT Libraries Year 2021 Language English

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Investigating the Effects of Inhaled Diesel Exhaust Particles on Gut Microbiome, Intestinal Integrity, Systemic Inflammation, and Biomarkers of Cardiovascular Disease in Wildtype Mice

We investigated the hypothesis that exposure to inhaled diesel exhaust PM can alter the gut microbiome and intestinal integrity, thereby promoting systemic inflammatory response and early CVD risk, which are exacerbated by HF diet. Furthermore, we investigated whether the observed exposure and diet-mediated outcomes could be mitigated through probiotic treatment. We performed an exposure study on C57Bl/6 male mice, placed on either a low fat (LF) diet or a high-fat (HF) diet, and exposed via oropharyngeal aspiration to 35 μg diesel exhaust particles (DEP) suspended in 35 μl of sterile saline or sterile saline controls (CON) twice a week for four weeks. A subset of mice on HF diet were dosed with 0.3 g/day (PRO, ~7.5x108 CFU/day) of probiotic Ecologic® Barrier 849 (Winclove Probiotics) in drinking water during the course of the study. For our first aim, we investigated the alterations in the gut microbiome, measured circulating cytokines and lipopolysaccharide (LPS), and measured CVD biomarkers in the heart. Our results revealed that exposure to inhaled DEP results in gut dysbiosis characterized by expansion of the phyla Verrucomicrobia and Proteobacteria and reduction in Actinobacteria, which was exacerbated by HF diet. Probiotics mitigated the DEP-mediated expansion of Proteobacteria and re-established Actinobacteria in …

Date: December 2021

Creator: Phillippi, Danielle T.

Object Type: Thesis or Dissertation

System: The UNT Digital Library

Reduced Visceral Fat and Biological Indices of Inflammation Following Combined Prebiotic/Probiotic Supplementation in Free Living Adults

Probiotics/prebiotic supplementation represents a viable option for addressing systemic inflammation and chronic disease risk resulting from excessive body weight. The purpose of this feasibility study was to determine if 90-d of supplementation with prebiotic and probiotic could alter mRNA responsible for inflammation and subsequently metabolic health in weight stable overweight adults. Participants were advised to not change their diet or exercise habits during the study. All protocols were approved by the University IRB and participants gave written informed consent. Participants were randomly assigned to either placebo (N=7; rice flour) or combined (N=8) prebiotic (PreticX® Xylooligosaccharide; 0.8 g/d; ADIP) and probiotic (MegaDuo® Bacillus subtilis HU58 and Bacillus coagulans SC-208; 3 Billion CFU/d) and measurements were made at baseline, 30, 60, and 90-d. Whole body DXA scans (GE iDXA®) and blood 574-plex mRNA analysis (Nanostring®) were used to generate primary outcomes. Compared to placebo, supplementation was associated with a 36% reduction in visceral adipose tissue (p = 0.001). Supplement resulted in significant, differential expression of 15 mRNA associated with adipose tissue inflammation, systemic inflammation, and/or chronic disease risk. The key findings support that 90-d prebiotic/probiotic supplementation may be associated with an improved metabolic health, reduced adipose tissue inflammation, reduced systemic inflammation, and …

Date: December 2021

Creator: Tanner, Elizabeth A.

Object Type: Thesis or Dissertation

System: The UNT Digital Library

Some Names for Empty Space

Some Names for Empty Space is a collection of poems that considers how poetry and language operate to define human experience, reconciling the 'empty spaces' between the self and the abstracted variables of all things. The poems here often find their impetus in fatherhood and a parent's efforts to explain the world to a child.

Date: May 2021

Creator: Koch, Andrew (Poet)

Object Type: Thesis or Dissertation

System: The UNT Digital Library

The Effects of the Use of Natural Language Processing and Task Complexity on Jurors' Assessments of Auditor Negligence

The purpose of my dissertation is to examine jurors' evaluation of auditor negligence in response to auditors' use of natural language processing (NLP). To test my research objective, I conducted a 2x2 between-subjects experiment with 175 jury-eligible individuals. In the online experiment, I manipulated whether the audit team analyzes contracts with NLP software or by having human auditors read the contracts. I also manipulated task complexity as complex or simple. The dependent variables include a binary verdict variable and a scaled assessment of negligence. This dissertation makes several contributions to the accounting literature and practice. First, it contributes to the recent juror literature on emerging technologies by providing evidence that jurors attribute higher negligence assessments to auditors when auditors use NLP to examine contracts than when human auditors examine contracts. I also find that auditors' use of NLP leads to jurors' higher perceived causation, which, in turn, increases jurors' assessments of auditor liability. Second, this study answers the call of other researchers to examine the relationship between task complexity and negligence in different settings. I also find a marginally significant interaction effect of the use of NLP compared to human auditors to perform audit testing that is greater for complex …

Date: August 2021

Creator: Cui, Junnan

Object Type: Thesis or Dissertation

System: The UNT Digital Library

A Multi-Site Case Study of Middle School Reading Teachers' Perceptions of the Impact of Response to Intervention

Early reading intervention has not eradicated reading deficiencies at the middle school level. According to the National Center for Educational Statistics (NCES), adolescents continue to read below grade level in middle grades. Response to intervention (RTI) is one method of combating this educational concern. This study examined the impact of implementation of a RTI program within one district across multiple middle school campuses. Using individual structured online questionnaires, focus groups, and document analysis, the researcher employed a qualitative, multi-site case study design to evaluate the perceptions of impact of RTI through the lens of middle school reading teachers. Participants included a convenient purposive sample of middle school reading teachers in a suburban school district of about 24,000 students in North Central Texas. I present a review of relevant research at the middle school level to provide a framework for the current study. Additionally, an outline of methodology, research questions, and the proposed data analysis plan are provided. I discuss the intended use of constant comparative analysis to report findings in themes. Particularly, facilitators, hindrances, and impact are a priori themes for reporting.

Date: August 2021

Creator: Norris, Frankie

Object Type: Thesis or Dissertation

System: The UNT Digital Library

Remotely Controlled Magneto-Phononic Devices Achieving Nonreciprocity and Anderson Localization in Ferrofluid

Motivated by previous relevant research on phononics including both active and passive phononics, the interest of faster turnability and more functions of the active phononics of further study led to this proposing research topic: magnetic field tunable active functional phononics. The first design of magnetic field tunable reciprocal--non-reciprocal transmission acoustic device was established, material was characterized, and numerical simulation has been performed. The simulation results show clear T-symmetric breaking non-reciprocity due to energy level splitting effect with Doppler effect – an acoustic Zeeman effect. Inspired by this preliminary work, further experiments were planned to demonstrate this effective Zeeman effect in phononics and effectively charged phonons in water based ferro-fluid. The objectives of this work as the next series of tasks were to illustrate acoustic Zeeman effect and acoustic Landau levels in various strength of magnetic field to investigate a design non-reciprocal sound device with magnetic field switching, which could be controlled on the amount of non-reciprocity with the strength of magnetic field. Once this new field first discovered by the proposed study tasks, more active tunable magnetic field phononics devices could be designed and exemplified in terms of both simulations and experiments. Faster and more controllable active phononic devices could …

Date: December 2021

Creator: Jin, Yuqi

Object Type: Thesis or Dissertation

System: The UNT Digital Library

Understanding the RCS Way: A Study of Organizational Culture

The quality of workplace morale can positively and negatively affect employee engagement. Engaged employees are more likely to participate in active communication with one another. They are also more likely to adopt the organizational goals and work towards creating a productive work environment. Communication and engagement build trust. Established trust between employees and executive leadership is a delicate relationship to maintain, though it is necessary when contending with periods of stress. The organization profiled below experienced the stressor of needing to grow without alienating those afraid of change or used to operating in one predictable direction. There was a desire to generate engagement, build trust and make room for employee-directed change. This desire left the organization open to exploring its culture and its impact on employee engagement.

Date: December 2021

Creator: Terry, Vanessa S.

Object Type: Thesis or Dissertation

System: The UNT Digital Library

The Effects of a Contingent S-Delta

This thesis attempted a cross-species replication of Bland, et. al., 2018. Human participants went through a computerized, automated shaping procedure that trained them to click on and discriminate between a blue square (SD) and red square (S-delta) on a VR 12 schedule of reinforcement. Three conditions were then presented to the participants consisting of a baseline, punishment, and control condition. In the punishment and control conditions, the SD was replaced by the S-delta or a novel stimulus respectively for 1-second on a VR 5 schedule. With each click, the reaction time and specific object clicked on were recorded. While the present study partially replicated the effect seen in earlier research, our results suggest that, depending on the lens of analysis used, either a punishment or an extinction effect may be causing the results seen.

Date: December 2021

Creator: Ochoa, Jules

Object Type: Thesis or Dissertation

System: The UNT Digital Library

Corrosion Mechanism and Prevention of Wire Bonded Device in Microelectronic Manufacturing and Spectroscopic Investigation of Copper Etch Chemical Equilibria for High Density Interconnect Application

In the first part of this dissertation work, Al bond pad corrosion behavior was investigated in the presence of common industrial contaminants such as chloride (Cl-) and fluoride (F-). Al corrosion while in direct contact with Cu displayed rapid hydrogen (H2) gas evolution and dendrite propagation. In contrast, Al without bimetallic contact showed only minor surface roughening. This observed difference in the corrosion mechanism between Cl- and F- is attributed to the solubility of the corrosion products (AlCl3 vs. AlF3) formed on the Al surface. Our subsequent work explored corrosion prevention inhibition of wire-bonded devices (WBD) in the Cl- environment. Our research shows that the Al bond pad was protected against corrosion by chemically modifying the surface of the Cu wires, thereby preventing the H2 evolution. The inhibitor was observed to be highly selective, thermally stable, hydrophobic, and cost-effective, making it viable for industrial application of this coating for Al bond pad corrosion prevention. In the second part of the dissertation work, we utilized a novel approach of using ultraviolet-visible spectroscopy (UV-Vis) as a chemical-sensitive monitoring tool of the chemical environment in Cu etch bath. The UV-Vis technique illuminates the roles of H+, Cl-, Cu+, and Cu2+ to the etch …

Date: December 2021

Creator: Ashok Kumar, Goutham Issac

Object Type: Thesis or Dissertation

System: The UNT Digital Library

(open access)

Instrumental Development and Implementation of Portable Membrane Inlet Mass Spectrometry for Homeland Security and Environmental Applications

A rapidly growing topic of great interest is the adaptation of benchtop analytical instrumentation for use in outdoor harsh environments. Some of the areas that stand to benefit from field instrumentation development include government agencies involved with the preservation of the environment and institutions responsible for the safety of the general public. Detection systems are at the forefront of the miniaturization movement as the interest in analyte identification and quantitation appears to only be accessible through the use of analytical instrumentation. Mass spectrometry is a distinguished analytical technique known for its ability to detect the mass-to-charge (m/z) ratios of gas-phase ions of interest. Although these systems have been routinely limited to research lab-based analysis, there has been considerable development of miniaturized and portable mass spectrometry systems. Membrane Inlet Mass Spectrometry (MIMS) is becoming a common method of sample introduction that is subject to significant development. MIMS allows for minimal sample preparation, continuous sampling, and excludes complicated analyte introduction techniques. Sampling is accomplished using a semipermeable membrane that allows selective analyte passage into the vacuum of the mass spectrometer. MIMS is becoming the preeminent choice of homeland security and environmental monitoring applications with increasing opportunities for the future development of specialized …

Date: December 2021

Creator: Anguiano Virgen, Camila

Object Type: Thesis or Dissertation

System: The UNT Digital Library

Forging Pathways: A Multi-Case Study of Individuals with Intellectual Disability Pursuing Postsecondary Education at the Community College

This multi-case study sought to better understand how students with intellectual disability (ID) are forging pathways to higher education via the community college. Five individuals with ID who accessed higher education via the community college and their parents/guardians were interviewed. Each case provided insight into personal pathways with results given in case descriptions and individual case themes. Cross-case analysis revealed four themes positively impacting the college-going pathway for students with ID: value-driven grit, pathway knowledge, community support, and accessibility. Based on findings from this study, families appear to be the primary systems forging pathways to the community college for individuals with ID. Local education agencies and community colleges can assist these families by engaging in interagency collaboration, evaluating their systems, and aligning practices to the goal of students with ID accessing and engaging in higher education.

Date: December 2021

Creator: Jackson, Amanda O.

Object Type: Thesis or Dissertation

System: The UNT Digital Library

Advanced Cathodes for High Energy Density Lithium Sulfur Battery

A systematic development of 2D alloy catalyst with synergistic performance of high lithium polysulfide (LiPS) binding energy and efficient Li+ ion/electron conduction is presented. The first section of work found that Li+ ions can flow through the percolated ion transport pathway in polycrystalline MoS2, while Na+ and K+ ions can easily flow through the percolated 1D ion channel near the grain boundaries. An unusually high ionic conductivity of extrinsic Li+, Na+, and K+ ions in 2D MoS2 film exceeding 1 S/cm was measured that is more than two orders of magnitude higher than those of conventional solid ionic materials, including 2D ionic materials. The second section of this dissertation focus on catalyzing the transformation of LiPSs to prevent the shuttle effect during the battery cycling by synthesizing 2H (semiconducting) – 1T (metallic) mixed phase 2D Mo0.5W0.5S2 alloy on CNF paper, using two step sputtering and sulfurization method. The lithium sulfur (Li-S) battery cell assembled with the 2D Mo0.5W0.5S2/CNF/S cathode shows a high specific capacity of 1228 mAh g-1 at 0.1C and much higher cyclic stability over 4 times as compared to the pristine cathodes. The high LiPSs binding energy of catalyst efficiently prevents the shuttling effect and corrosion of Li …

Date: December 2021

Creator: Bhoyate, Sanket

Object Type: Thesis or Dissertation

System: The UNT Digital Library

Reliability Characterization and Performance Analysis of Solid State Drives in Data Centers

NAND flash-based solid state drives (SSDs) have been widely adopted in data centers and high performance computing (HPC) systems due to their better performance compared with hard disk drives. However, little is known about the reliability characteristics of SSDs in production systems. Existing works that study the statistical distributions of SSD failures in the field lack insights into distinct characteristics of SSDs. In this dissertation, I explore the SSD-specific SMART (Self-Monitoring, Analysis, and Reporting Technology) attributes and conduct in-depth analysis of SSD reliability in a production environment with a focus on the unique error types and health dynamics. QLC SSD delivers better performance in a cost-effective way. I study QLC SSDs in terms of their architecture and performance. In addition, I apply thermal stress tests to QLC SSDs and quantify their performance degradation processes. Various types of big data and machine learning workloads have been executed on SSDs under varying temperatures. The SSD throughput and application performance are analyzed and characterized.

Date: December 2021

Creator: Liang, Shuwen (Computer science and engineering researcher)

Object Type: Thesis or Dissertation

System: The UNT Digital Library

(open access)

Unraveling the Effect of Atomic Configurations and Structural Statistics on Mechanical Behavior of Multicomponent and Amorphous Alloys

Multicomponent high-entropy and amorphous alloys represent relatively new classes of structural materials with complex atomic configurations and exceptional mechanical properties. However, there are several knowledge gaps in the relationships between their atomic structure and mechanical properties. Understanding these critical relationships will enable novel alloy design and tailoring of their mechanical properties for desired engineering applications. In this dissertation, first-principles calculations and molecular dynamics simulations are applied to investigate the local atomic configurations and ordering in high-entropy and amorphous alloys. Our findings suggest that fluctuations in local atomic configurations for high- entropy alloys result in significant changes in stacking fault energy, twin energy, dislocation behavior, dislocation-twin interactions, and critical shear stress. For amorphous alloys or metallic glasses, the short-range order (SRO) and medium-range order (MRO) were found to play decisive roles in determination of their mechanical properties. Structural relaxation was found to lead to shear localization, which was attributed to free volume change and evolution of SRO and MRO to more brittle nature. In contrast, rejuvenated metallic glasses had relatively large and uniform free volume distribution giving rise to homogeneous flow and increased plasticity.

Date: December 2021

Creator: Yang, Yu Chia

Object Type: Thesis or Dissertation

System: The UNT Digital Library

(open access)

The Examination of Black and Latino/a/x Students' and Responsive STEM Teachers' Perceptions of Teacher Cultural Consciousness and Culturally Responsive Instructional Practices

School cultures, curriculum, and instruction are too often created through a monocultural lens, which excludes Black and Latino/a/x students both socially and academically, and perpetuates the false notion that these students are inherently less capable of achieving academic success when compared to their White counterparts. This is visible across all content areas, but especially in secondary science, technology, engineering, and mathematics (STEM) classes, which means that our Black and Latino/a/x students are continually denied preparation for the critical, high demand careers in the STEM field. Just as critical, with the dominance of White teachers in the classroom, out Black and Latino/a/x students often do not have access to teachers who share their lived experiences or who understand the nuances of their home cultures. However, teachers and school instructional leaders can change course by focusing their efforts to develop a rich cultural consciousness, and by focusing on the utilization of culturally responsive pedagogy (CRP) and related instructional strategies with great intentionality in the classroom. This mixed method, single site, exploratory case study was conducted to examine Black and Latino/a/x students' perceptions of their culturally responsive STEM teachers' cultural consciousness, and culturally responsive STEM teachers' perceptions of culturally responsive practices and their …

Date: December 2021

Creator: Norris, Margaret Louise

Object Type: Thesis or Dissertation

System: The UNT Digital Library

(open access)

Domain Specific Cognitive Effects of Sickle Cell Disease in Children

Multiple contributors to neurocognitive impairment in individuals with sickle cell disease have been identified. Research indicates that a history of cerebrovascular accidents, such as silent infarcts and strokes are associated with greater cognitive decline among children with sickle cell disease. Additionally, disease effects such as hemoglobin and hematocrit levels significantly effect cognitive performance among this population and should be taken into consideration when examining neurocognitive impairment. Further, previous studies show a significant relationship between child behavior problems, family functioning, and cognitive performance in children with sickle cell, marking those as important targets for intervention among this population. While cognitive decline with increased age is not typically examined in healthy child populations, some research indicates the presence of age effects in those with SCD. A majority of the literature addresses cognitive impairment from a broad perspective, while a limited number of studies have begun to address effects among specific cognitive domains. Using archival data from the National Institutes of Health's Cooperative Study of Sickle Cell Disease, results revealed that disease severity was negatively correlated with some aspects of cognitive functioning, including visual-spatial domains. Additionally, some measures of cognitive performance were inversely correlated with age. Consistent with hypothesized outcomes, family functioning was …

Date: December 2021

Creator: Carroll, Bridgette

Object Type: Thesis or Dissertation

System: The UNT Digital Library

(open access)

Air Corridors: Concept, Design, Simulation, and Rules of Engagement

Air corridors are an integral part of the advanced air mobility infrastructure. They are the virtual highways in the sky for transportation of people and cargo in the controlled airspace at an altitude of around 1000 ft. to 2000 ft. above the ground level. This paper presents fundamental insights into the design of air corridors with high operational efficiency as well as zero collisions. It begins with the definitions of air cube, skylane or track, intersection, vertiport, gate, and air corridor. Then, a multi-layered air corridor model is proposed. Traffic at intersections is analyzed in detail with examples of vehicles turning in different directions. The concept of capacity of an air corridor is introduced along with the nature of distribution of locations of vehicles in the air corridor and collision probability inside the corridor are discussed. Finally, the results of simulations of traffic flows are presented.

Date: December 2021

Creator: Muna, Sabrina Islam

Object Type: Thesis or Dissertation

System: The UNT Digital Library

A Proposal for a Training Program to Support Culturally Responsive Professional-Family Interactions

Behavior analysts often work with families from diverse cultural backgrounds. Ideally, behavior analysts and families interact in ways that are responsive to the family's culture and valued outcomes. The data indicate that most behavior analysts, however, come from one dominant cultural group. This is a proposal for training program and evaluation method to support culturally responsive professional-family interactions. This proposed study is designed to be conducted via Zoom-- a cloud-based video conferencing service. A pre-post treatment design is proposed to assess the effects of the training. Hypothetical data were generated to consider the range of effects such a program might have on trainee responses to written/live scenarios. Responses in the observation protocol included written descriptions, empathetic statements, perspective taking statements, and non-verbal behaviors. Overall, the program was designed using evidence-based procedures and is likely to support behavior analysts in training and in practice to improve their interactions with families and become more culturally responsive to groups of people that are from the non-dominant culture.

Date: December 2021

Creator: Anegbeh, Cynthia Momoh

Object Type: Thesis or Dissertation

System: The UNT Digital Library

The Effect of Online Consumer Reviews and Brand Equity on the Consumer Decision Making Process

This research aims to investigate the (1) review effects on consumer decision making process, (2) effects of negative reviews on brand equity, and (3) consumers' likely response to a brand's request for reviews. The objective of the first essay is to investigate the nature of the relationship between skepticism and consumer decision making in an online behavior context. Its second objective is to know whether people's belief on their abilities or their hedonic principle moderates the relationship between a person's skepticism toward online reviews and their reliance on online reviews. The objective of the second essay is to explore whether negative online reviews that focus on service quality specific dimensions have a different effect on a service organization's perceived brand equity. Its second objective is to analyze the role of emotional contagion in the relationship between negative reviews related to various service quality dimensions and its effect on perceived brand equity. The main objective of the third essay is to know whether consumers are more likely to write an online review for a brand when the request comes from a higher equity brand. This essay also investigates how message trust and persuasion knowledge influence the relationship between a brand's request …

Date: December 2021

Creator: Ahmad, Fayez

Object Type: Thesis or Dissertation

System: The UNT Digital Library

Optimal Pair-Trading Decision Rules for a Class of Non-Linear Boundary Crossings by Ornstein-Uhlenbeck Processes

The most useful feature used in finance of the Ornstein-Uhlenbeck (OU) stochastic process is its mean-reverting property: the OU process tends to drift towards its long- term mean (its equilibrium state) over time. This important feature makes the OU process arguably the most popular statistical model for developing best pair-trading strategies. However, optimal strategies depend crucially on the first passage time (FPT) of the OU process to a suitably chosen boundary and its probability density is not analytically available in general. Even for crossing a simple constant boundary, the FPT of the OU process would lead to crossing a square root boundary by a Brownian motion process whose FPT density involves the complicated parabolic cylinder function. To overcome the limitations of the existing methods, we propose a novel class of non-linear boundaries for obtaining optimal decision thresholds. We prove the existence and uniqueness of the maximizer of our decision rules. We also derive simple formulas for some FPT moments without analytical expressions of its density functions. We conduct some Monte Carlo simulations and analyze several pairs of stocks including Coca-Cola and Pepsi, Target and Walmart, Chevron and Exxon Mobil. The results demonstrate that our method outperforms the existing procedures.

Date: December 2021

Creator: Tamakloe, Emmanuel Edem Kwaku

Object Type: Thesis or Dissertation

System: The UNT Digital Library

A New Class of Stochastic Volatility Models for Pricing Options Based on Observables as Volatility Proxies

One basic assumption of the celebrated Black-Scholes-Merton PDE model for pricing derivatives is that the volatility is a constant. However, the implied volatility plot based on real data is not constant, but curved exhibiting patterns of volatility skews or smiles. Since the volatility is not observable, various stochastic volatility models have been proposed to overcome the problem of non-constant volatility. Although these methods are fairly successful in modeling volatilities, they still rely on the implied volatility approach for model implementation. To avoid such circular reasoning, we propose a new class of stochastic volatility models based on directly observable volatility proxies and derive the corresponding option pricing formulas. In addition, we propose a new GARCH (1,1) model, and show that this discrete-time stochastic volatility process converges weakly to Heston's continuous-time stochastic volatility model. Some Monte Carlo simulations and real data analysis are also conducted to demonstrate the performance of our methods.

Date: December 2021

Creator: Zhou, Jie

Object Type: Thesis or Dissertation

System: The UNT Digital Library