Degree Level

States

Language

The effects of computer performance assessment on student scores in a computer applications course (open access)

The effects of computer performance assessment on student scores in a computer applications course

The goal of this study was to determine if performance -based tests should be routinely administered to students in computer application courses. The purpose was to determine the most appropriate mode of testing for individuals taking a computer applications course. The study is divided into areas of assessment, personality traits, and computer attitudes.
Date: July 1994
Creator: Casey, Sue Hartness
System: The UNT Digital Library
The Use of the Power Method to Find Dominant Eigenvalues of Matrices (open access)

The Use of the Power Method to Find Dominant Eigenvalues of Matrices

This paper is the result of a study of the power method to find dominant eigenvalues of square matrices. It introduces ideas basic to the study and shows the development of the power method for the most well-behaved matrices possible, and it explores exactly which other types of matrices yield to the power method. The paper also discusses a type of matrix typically considered impossible for the power method, along with a modification of the power method which works for this type of matrix. It gives an overview of common extensions of the power method. The appendices contain BASIC versions of the power method and its modification.
Date: July 1992
Creator: Cavender, Terri A.
System: The UNT Digital Library
A.B. Marx's Concept of Rondo and Sonata: A Critical Evaluation of His Explanations of Musical Form (open access)

A.B. Marx's Concept of Rondo and Sonata: A Critical Evaluation of His Explanations of Musical Form

The third volume of A.B. Marx's theory treatise Die Lehre von der musikalischen Komposition is discussed. His definitions of rondo and sonata formal types are demonstrated in the first chapter in addition to the manner of their derivation through a developmental process originating in the Liedform. Musical examples chosen by Marx are examined in chapter two. These examples, taken from Mozart's and Beethoven's piano works, are evaluated in relation to Marx's definitions of the various types of form. The third chapter is concerned with the progression from microstructure to macrostructure and the functional interrelation of the parts to the whole. In addition, Marx's opinion on musical form is compared with perspectives of philosophers from his time period and the immediate past.
Date: July 1993
Creator: Lang, Adelheid K.
System: The UNT Digital Library
Acculturation and Locus Of Control: Their Relationship to the Use of Inhalants (open access)

Acculturation and Locus Of Control: Their Relationship to the Use of Inhalants

This study analyzed the effects of acculturation, locus of control, and incidence of inhalant use on Mexican Americans. Information was collected from 275 subjects at three middle schools and one treatment center. The instrument consisted of Levenson's Locus of Control Scale, the Acculturation Rating Scale for Mexican Americans, and an incidence of use and family relationship questionnaire developed for this study. Statistical analysis indicated a relationship between acculturation and inhalant use. Further examination revealed relationships between a family members' use and subjects' inhalant use; subjects' alcohol use and inhalant use; and subjects' marijuana use and inhalant use. Information implied that prevention and intervention programs should focus on children of substance users and further research is needed surrounding the role of acculturation.
Date: July 1989
Creator: Davis, Lynn Matthew
System: The UNT Digital Library
A Study of the Relationships among Student Expectations about Teacher Nonverbal Immediacy, Student Perceptions of Teacher Nonverbal Immediacy, and Affective Learning in Distance Learning and the On-Site Classroom (open access)

A Study of the Relationships among Student Expectations about Teacher Nonverbal Immediacy, Student Perceptions of Teacher Nonverbal Immediacy, and Affective Learning in Distance Learning and the On-Site Classroom

This thesis explored the relationships among three communication variables in college-level instruction: students' expectancy about teachers' nonverbal immediacy, students' actual perceptions of teachers' nonverbal immediacy, and students' affective learning. Community college students enrolled in either distance learning or a traditional classroom course completed pre-course and mid-course questionnaires to indicate their expectations and observations of the nonverbal immediacy behaviors of their teachers. Analysis showed that students expected and perceived less nonverbal immediacy from tele-course teachers than from on-site teachers, but that perceptions significantly exceeded expectations. Research findings indicated that students' expectancies about teachers' nonverbal immediacy may influence the measurement of affective learning.
Date: July 1997
Creator: Witt, Paul L.
System: The UNT Digital Library
The Chlorination of Amino Acid in Municipal Waste Effluents (open access)

The Chlorination of Amino Acid in Municipal Waste Effluents

In model reaction systems to test amino acids in chlorinated waste effluents, several amino acids were chlorinated at high chlorine doses. (2000-4000 mg/1). Amino acids present in municipal waste effluents before and after chlorination were concentrated and purified using cation exchange and Chelex resins. After concentration and cleanup of the samples, the amino acids were derivatized by esterification of the acid functional groups and acylation of the amine groups. Identification and quantification of the amino acids and chlorination products was carried out by gas chromatography/mass spectrometry, using a digital computer data system. Analysis of the waste products revealed the presence of new carbon-chlorine bonded derivatives of the amino acid tyrosine when the effluents were treated with heavy doses of chlorine.
Date: July 1977
Creator: Burleson, Jimmie L.
System: The UNT Digital Library
The Effects of Skilled Dialogue Simulation Coaching on the Collaborative Verbal Behavior of Behavior Analysts in Training (open access)

The Effects of Skilled Dialogue Simulation Coaching on the Collaborative Verbal Behavior of Behavior Analysts in Training

Despite the evidence that supports the benefits of a holistic, collaborative approach to autism intervention, but there is little training to teach those skills to professionals. Behavior analysts working in applied settings will often partner with different individuals from very different backgrounds and disciplines. Skilled Dialogue has been recommended as an approach to conversations that values everyone's contributions in fostering compassionate, collaborative, and culturally responsive care to benefit the children served. The purpose of this study was to evaluate the effects of a training workshop to teach the concept and strategies of skilled dialogue to behavior analysts in training. The participants were taught and practiced using the six strategies of Skilled Dialogue: welcoming, allowing, sense-making, appreciating, joining, and harmonizing through use of instructions, rationales, activities, simulations, and feedback. The success of the training was evaluated using a multiple baseline design across training components. Audio and video responses to role-play scenarios were recorded, transcribed, and scored to measure the results of the training workshop on communication skills. The results suggested that the training workshop was an effective method to teaching future behavior analysts how to engage in the strategies and components of skilled dialogue, increasingly the likelihood of collaborative, and children …
Date: July 2023
Creator: Webb, Maia Grenada
System: The UNT Digital Library
Exploring the Synergistic Effects of MXene-based Nanocomposites for Superlubricity and Friction/Wear Reduction on Rough Steel Surfaces (open access)

Exploring the Synergistic Effects of MXene-based Nanocomposites for Superlubricity and Friction/Wear Reduction on Rough Steel Surfaces

The aim of this thesis is to advance the field of solid lubrication science by developing coatings that provide reliable performance in ambient conditions, work on rough surfaces, and are amenable to industrial size and design complexities. Two different coating systems, Ti3C2Tx-MoS2 and Ti3C2Tx-Graphene Oxide blends, were studied in this work. The Ti3C2Tx-MoS2 nanocomposites were spray-coated onto rough 52100-grade steel surfaces, and their tribological performance was evaluated in a ball-on-disk configuration in a unidirectional sliding mode. The test results indicate that Ti3C2Tx-MoS2 coatings achieved superlubricity, which has not been previously reported for either pristine material under macroscale sliding conditions. The observed synergistic mechanism enabled the superlative performance, which was explained by the in-situ formation of a robust tribolayer responsible for sustained lubricity even at high contact pressures (>1.1 GPa) and sliding speeds (0.1 m/s). Processing, structure, and property correlation studies were conducted to understand the underlying phenomena. Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy were used to reveal the formation of the tribolayer. The Ti3C2Tx-Graphene Oxide blends were also spray-coated onto rough-bearing steel surfaces, and their tribological assessment was carried out in ambient environmental conditions and high contact pressures in a ball-on-disc experimental setup. The coatings led to …
Date: July 2023
Creator: Macknojia, Ali Zayaan
System: The UNT Digital Library
Mother Dearest: Understanding Attachment Styles of Juvenile Offenders across Crime Types (open access)

Mother Dearest: Understanding Attachment Styles of Juvenile Offenders across Crime Types

This exploratory study investigated the relationship between attachment style and offense types of juvenile offenders to determine whether there were commonalities among the cohort and their attachment style. Much of the peer-reviewed literature focuses on adult sex offenders and attachment style but neglects the juvenile population. The present study utilized secondary data from the Texas Juvenile Justice Department (TJJD) which included adjudicated juveniles with Positive Achievement Change Tool (PACT) data (n = 4,521) from 2009 to 2013. Juveniles were grouped into three attachment groups (secure, anxious-avoidant, or other) based on attachment correlates found in their PACT data. Logistic regression analyses were then used to investigate the relationship between attachment styles and offense types among the adjudicated juveniles. Results indicated that attachment style does not have an overwhelming influence on offense type of juvenile offenders. However, juveniles with an attachment style other than secure or anxious-avoidant were more likely to be adjudicated for assault/aggravated assault, sexual assault/aggravated assault, aggravated robbery, and other offenses not captured. Whereas juveniles with an anxious-avoidant attachment are at increased odds of being adjudicated for drug offenses. However, it should be noted that juveniles adjudicated for sexual assault/aggravated sexual assault with an anxious-avoidant attachment style reflected a …
Date: July 2023
Creator: White, Lindsey Nicole
System: The UNT Digital Library
The Experiences of Young Adult-Aged Women from South Asian Countries Attempting to Participate in Sport and Physical Activity in the United States (open access)

The Experiences of Young Adult-Aged Women from South Asian Countries Attempting to Participate in Sport and Physical Activity in the United States

This study aimed to broaden the understanding of young South Asian women's experiences/relationships and participation in leisure physical activities at universities in the United States. Using a phenomenological design, semi-structured interviews of 20-30 minutes duration were conducted with 5 South Asian women about their relationships and experiences when participating or attempting to participate in physical activity while attending university in the US. The following criteria were set for participants to be included in this study: they should be between the ages of 18 and 24, non-US citizens from a South Asian country, attend a university in the US, and engage in other physical activities. The interviews were audio recorded via Zoom and then the audio data were transcribed verbatim and then coded to identify the major barriers commonly experienced by participants. Results indicated that many girls and women perceived the US as a "safer" place with excellent infrastructure, ample opportunities to engage in physical activities, and convenient access to gyms, which encourage them (women) to remain active. Most participants were hesitant to participate in physical activities because of the culturally non-responsiveness of the system. This research study was done in a shorter time span with a small sample size. Further …
Date: July 2023
Creator: Rahman, Sohaila
System: The UNT Digital Library
Investigation of Interfacial Property with Imperfection: A Machine Learning Approach (open access)

Investigation of Interfacial Property with Imperfection: A Machine Learning Approach

Interfacial mechanical properties of adhesive joints are very crucial in board applications, including composites, multilayer structures, and biomedical devices. Establishing traction-separation (T-S) relations for interfacial adhesion can evaluate mechanical and structural reliability, robustness, and failure criteria. Due to the short range of interfacial adhesion such as micro to nanoscale, accurate measurements of T-S relations remain challenging. The advent of machine learning (ML) became a promising tool to predict materials behaviors and establish data-driven mechanical models. In this study, we integrated a state-of-the-art ML method, finite element analysis (FEA), and standard experiments to develop data-driven models for characterizing the interfacial mechanical properties precisely. Macroscale force-displacement curves are derived from FEA with incorporation of double cantilever beam tests to generate the dataset for ML model. The eXtreme Gradient Boosting (XGBoost) multi-output regressions and classifier models are used to determine T-S relations with R2 score of 98.8% and locate imperfections at the interface with accuracy of around 80.8%. The outcome of the XGBoost models demonstrated accurate predictions and fast calculation speed, outperforming several other ML methods. Using 3D printed double cantilever beam specimens, the performance of the ML models is validated experimentally for different materials. Furthermore, a XGBoost model-based package is designed to …
Date: July 2023
Creator: Ferdousi, Sanjida
System: The UNT Digital Library
Saving the Golden Goose: A Dual Exploration into the Organizational Culture of a Family-Owned Firm and the Impacted DIY Customer Experience (open access)

Saving the Golden Goose: A Dual Exploration into the Organizational Culture of a Family-Owned Firm and the Impacted DIY Customer Experience

This thesis investigates the influence of organizational culture on customer experience through a comprehensive study of a global supplier of home repair products. By combining organizational analysis and consumer research, this research draws on anthropological principles to explore the nuances of family governance and their effects on behavior, customer experience, and product design. The results of this study present insightful information on product perception and actionable strategies to improve product design, branding, and messaging in order to enhance customer experience and drive sales. Drawing on organizational anthropology and the utilization of critical reflexivity, this thesis provides a deeper understanding of how family-owned businesses can leverage research to challenge their cultural assumptions about products, consumers, and their organization, in order to effectively implement customer-centric solutions and drive organizational behavior, customer experience, and product development.
Date: July 2023
Creator: Holland, Elizabeth Anglin
System: The UNT Digital Library
Devotio Moderna and Erasmus: Transforming Piety (open access)

Devotio Moderna and Erasmus: Transforming Piety

The relationship between Erasmus of Rotterdam and the religious movement called the Devotio Moderna, especially the latter's relevance to Erasmian piety, has been a somewhat contentious historiographical issue. This thesis examines that relationship, and asserts that the Devotio Moderna was a crucial formative aspect of Erasmus' religiosity. However, its relevance ought not be overstated, due to the humanist's significant developments away from his spiritual forerunners.
Date: July 2023
Creator: Kuplack, Ian
System: The UNT Digital Library
The Good and the Bad Sides of the Protest: Framing Abortion Rights Protests in Photojournalism (open access)

The Good and the Bad Sides of the Protest: Framing Abortion Rights Protests in Photojournalism

In both Mexico and the U.S., abortion rights protests have been taking place in recent years, but while Mexico is moving forward with the legalization of abortion, the U.S. is going in the opposite direction with the overturning of Roe v. Wade. Through framing, journalists select salient information, shaping audiences' understandings of social movements. The protest paradigm suggests that due to journalistic norms and routines, journalists tend to focus on disruptive acts, which can stigmatize the protest. Additionally, scholars have stated that men and women photojournalists have different approaches to covering certain topics. This cross-national research combined a content analysis of photographs in U.S. and Mexican media with in-depth interviews with photojournalists to determine if photojournalists in each country are reproducing the protest paradigm and if there are gendered differences in how they photograph abortion rights protests. The results revealed that women and men photograph differently, with women capturing more intimate photos; however, photojournalists' gendered experiences are also influenced by how protesters perceive them. Furthermore, the study suggests that photojournalists from both countries are questioning objectivity and are attempting to move away from the protest paradigm. This research provides valuable insights into visual framing theory, protest news coverage, and gendered …
Date: July 2023
Creator: Díaz González Vázquez, Greta
System: The UNT Digital Library
Cultural Elements in Disaster: A Case Study on the Sewol Ferry Tragedy in South Korea (open access)

Cultural Elements in Disaster: A Case Study on the Sewol Ferry Tragedy in South Korea

On April 16, 2014 the Sewol Ferry became one of the worst maritime disasters in South Korea with the loss of 304 passenger, the majority being high school students. South Korea is a collectivist culture, structured as a hierarchical system that teaches their students and children to always respect, listen, and trust authority figures especially in dangerous situations. This study explores how collectivist cultural elements impacted the response of the Sewol Ferry. By examining the timeline of the disaster through interviews, documentaries, news articles and media; this thesis offers insight into what happened that day by providing perspectives from the rescue crew, government officials, survivors, volunteers, and family members of those who died. The analysis showed that in collectivist culture, children and students are taught to trust and listen to authority figures when in dangerous situations, however because of the Sewol disasters, the culture of adhering to the hierarchical systems started to collapse. Students who survived stated that they no longer can trust and respect adults after the incident along with family members of the students who passed away and the public. Also, the government withheld information and failed to protect the children aboard the ferry, because they didn't want …
Date: July 2023
Creator: Vu, Julia PhuongNguyen H.
System: The UNT Digital Library
3D Printed Self-Activated Carbon Electrodes for Supercapacitor Applications (open access)

3D Printed Self-Activated Carbon Electrodes for Supercapacitor Applications

This study investigated a new approach to achieving high energy density supercapacitors (SCs) by using high surface area self-activated carbon from waste coffee grounds (WCGs) and modifying 3D printed electrodes' porous structure by varying infill density. The derived activated carbons' surface area, pore size, and pore volume were controlled by thermally treating the WCGs at different temperatures (1000˚C, 1100˚C, and 1200˚C) and post-treating with HCL to remove water-soluble ashes and contaminants that block activated carbon pores. Surface area characterization revealed that the carbon activated at 1000˚C had the highest surface of 1173.48 m2 g-1, and with the addition of HCL, the surface area increased to 1209.35 m2 g-1. This activated carbon was used for fabricating the electrodes based on the surface area and having both micropores and macropores, which are beneficial for charge storage. Direct ink writing (DIW) method was utilized for 3D printing SC electrodes and changing the electrode structure by increasing the infill densities at 30%, 50%, and 100%. Upon increasing the infill densities, the electrodes' mass increased linearly, porosity decreased, and the total surface area increased for the 30% and 50% infill electrodes but decreased for the 100% infill electrode. Cyclic voltammetry (CV) test on the assembled …
Date: July 2023
Creator: Disi, Onome Aghogho
System: The UNT Digital Library
Household Displacement after Hurricane Harvey: Decisions, Destination Choice, and Displacement Patterns (open access)

Household Displacement after Hurricane Harvey: Decisions, Destination Choice, and Displacement Patterns

The thesis examines post-event displacement of households in the year following Hurricane Harvey. Using data gathered from a three-page mail survey conducted approximately 1-year after the storm, this study examines two primary research objectives. First this thesis aims to identify variables that predict displacement or non-displacement after the disaster. Second, this study explores patterns in the destination and duration of displaced households following Hurricane Harvey. Logistic regression analyses were used to examine the extent to which household composition characteristics and level of damage sustained during Hurricane Harvey predicted post-disaster displacement. Next, independent sample t-tests and descriptive statistical analyses were used to identify patterns in the destination of post-event relocations. Research findings indicate in the overall binary logistic regression model that after Hurricane Harvey, being White, level of home damage, wind damage, and number of days a member of the household returned home post-Harvey increased the likelihood of a household being displaced. Analysis of the survey responses also indicated that many households made multiple moves following Hurricane Harvey and specifically, displaced households were more likely to stay with a friend or relative. Additionally, this study found that with each additional relocation, the duration of stay at each destination increased while the …
Date: July 2023
Creator: Sauceda, Miranda
System: The UNT Digital Library

Linkage of the Nitrilase-Encoding Nit1C Gene Cluster to Cyanotrophy in Acinetobacter haemolyticus

The Nit1C cluster is a conserved gene cluster of seven genes that confers bacterial growth on cyanide as the sole nitrogen source. Bacteria with this ability are referred to as cyanotrophs. To date, the linkage between Nit1C and cyanotrophy has only been demonstrated for environmental isolates but the cluster also exists in certain medically related bacteria. In this study, a nosocomial isolate, Acinetobacter haemolyticus ATCC 19194, carrying Nit1C also displayed the ability to grow on cyanide. Growth on cyanide was accompanied by the induction of the cluster as was the mere exposure of cells to cyanide. Expression of the cluster was determined by measuring the activity of the nitrilase (NitC) coded for by the cluster and by transcriptional analysis (qRT-PCR). However, a disconnect between nitC message and NitC protein was observed depending on the phase of the growth cycle, the disconnect being related to proteolytic digestion of the NitC protein. Ironically, the cluster was also discovered to be upregulated in the absence of cyanide under nitrogen starvation conditions paralleling biofilm formation. The basis of the genetic linkage to cyanotrophy is not understood but taken together with results showing that nitrogen starvation and biofilm formation are also physiologically associated with Nit1C …
Date: July 2023
Creator: Dale, Layla Momo
System: The UNT Digital Library
Tribocatalytically-Active Coatings for Enhanced Tribological Performance and Carbon-Based Tribofilm Formation (open access)

Tribocatalytically-Active Coatings for Enhanced Tribological Performance and Carbon-Based Tribofilm Formation

In this study, we investigate the fundamental mechanisms defining the approach for addressing tribological challenges in mechanical systems via the use of the tribocatalytically active coating. The coating is designed using an electrodeposition process and consists of a hard amorphous cobalt-phosphorous matrix with the incorporation of tribocatalytically-active nickel and copper. Our focus is on understanding the effect of the tribocatalytic elements, Cu vs Ni, on the coating's performance in high-contact stress conditions, generating local heating, shear, and compression. By optimizing the relative composition and mechanical characteristics of the coating, we aim to enhance its tribological performance in the presence of a hydrocarbon environment. Through extensive characterization of the wear tracks using SEM/EDS and Raman analyses, we identify the formation of a protective carbon-based tribofilm on the coating's surface during sliding as the key factor behind its excellent performance. Our findings not only contribute to the understanding of material transformations in the contact but also offer a robust and versatile approach to addressing tribological challenges in mechanical systems. The development of this innovative coating opens up new possibilities for promoting the formation of protective tribofilms and improving the performance of mechanical components operating in low-viscosity fuels and synthetic oils.
Date: July 2023
Creator: Al Sulaimi, Rawan
System: The UNT Digital Library
Can In-vivo Self-Monitoring Improve Discrete Trial Instruction Implementation? (open access)

Can In-vivo Self-Monitoring Improve Discrete Trial Instruction Implementation?

Beneficial consumer outcomes are most likely when behavior-analytic interventions are implemented with high procedural fidelity (i.e., degree to which the procedure is implemented as intended). Video self-monitoring, which involves teaching staff members to monitor their own procedural fidelity when watching recordings of themselves, can be used to improve and maintain high procedural fidelity, but video self-monitoring requires additional staff time and resources. In-vivo self-monitoring, which involves monitoring procedural fidelity during or immediately following implementing a behavior-analytic intervention, could be a cost-effective option. However, in-vivo self-monitoring needs additional research to understand its effects on procedural fidelity. This current study analyzed the effects of in-vivo self-monitoring on the procedural fidelity of three behavior technicians implementing discrete trial instruction with children with autism. We used a nonconcurrent multiple baseline across participants design to teach participants how to score their procedural fidelity during their discrete trial instruction session. Data suggested that in-vivo self-monitoring was effective for two out of three participants, and those two participants were more likely to be accurate in their self-scored procedural fidelity. Procedural fidelity for the third participant did not increase with in-vivo or video self-monitoring, and the third participant was less likely to be accurate in their self-scored procedural …
Date: July 2023
Creator: Lai, Rachel Nicole
System: The UNT Digital Library
A Platform for Aligning Academic Assessments to Industry and Federal Job Postings (open access)

A Platform for Aligning Academic Assessments to Industry and Federal Job Postings

The proposed tool will provide users with a platform to access a side-by-side comparison of classroom assessment and job posting requirements. Using techniques and methodologies from NLP, machine learning, data analysis, and data mining: the employed algorithm analyzes job postings and classroom assessments, extracts and classifies skill units within, then compares sets of skills from different input volumes. This effectively provides a predicted alignment between academic and career sources, both federal and industrial. The compilation of tool results indicates an overall accuracy score of 82%, and an alignment score of only 75.5% between the input assessments and overall job postings. These results describe that the 50 UNT assessments and 5,000 industry and federal job postings examined, demonstrate a compatibility (alignment) of 75.5%; and, that this measure was calculated using a tool operating at an 82% precision rate.
Date: July 2023
Creator: Parks, Tyler J.
System: The UNT Digital Library
The Impostor Phenomenon as a Threat to Professional Resilience and Profession-Wide Diversity in the Psychology Trainee to Workforce Pipeline (open access)

The Impostor Phenomenon as a Threat to Professional Resilience and Profession-Wide Diversity in the Psychology Trainee to Workforce Pipeline

Racial and ethnic diversity representation in the field of health service psychology is neither equitable nor reflective of the increasingly diverse population nationwide. This discrepancy is endemic to widespread problems associated with mental health care: Minorities are severely underrepresented in the workforce, in psychology training programs, and in treatment populations. The longstanding lack of diversity among trainees in doctoral programs and among professionals in the workforce is associated with poorer mental health outcomes among minority patients; however, the specific contributors that facilitate and maintain racial/ethnic diversity constriction appear to be understudied. Based on the extant literature, a reasonable hypothesis might be that admission of qualified underrepresented minorities to doctoral training is constricted by ineffective and/or outdated recruitment and admissions practices. The proposed study sought to investigate whether impostor feelings or self-reported resilience might be predictive of intent to apply to graduate programs among underrepresented minority students earning their bachelor's degree in psychology. Results indicated that resilience was the most impactful variable in undergraduate students' intent to apply to graduate programs. Hypothesized ethnic differences in impostor feelings and self-perceived resilience were not observed in the study sample. The larger implications of these findings underscore the need for more culturally informed measures …
Date: July 2023
Creator: Williams, Amber Lavonne
System: The UNT Digital Library
Air Breathing Fish: Development of Air Breathing in Bristlenose Plecos (Ancistrus cirrhosus) (open access)

Air Breathing Fish: Development of Air Breathing in Bristlenose Plecos (Ancistrus cirrhosus)

The bristlenose pleco (Ancistrus cirrhosus) is a species of armored catfish in the Loricariidae family that breathes air facultatively when the aquatic environment becomes hypoxic. The bristlenose pleco uses its highly vascularized stomach as an air breathing organ. The two main goals of this developmental study were to determine the size of onset of air breathing and to determine the frequency of air breathing behavior in bristlenose plecos from juveniles to adults. Developing juveniles reach functional maturity within four to six months of hatching and grow to an adult size of eight to ten cm in length. To examine the developmental timing for the onset of air breathing, we tested different sized juveniles beginning at one cm up until 8 cm in length. The developmental timing for the onset of air breathing was measured by exposing each fish to a slowly decreasing aquatic oxygen content from 100% air saturation down to 8% air saturation. Fish were first able to breathe air at just over 2 cm and 1 gram in mass. There was a weak negative correlation between fish length and % air saturation at which air breathing began. When exposed to 15% air saturation, frequency of air breathing was …
Date: July 2023
Creator: Crowder, Lauren Whitney
System: The UNT Digital Library
Hypoxia-Induced Cardiac Arrest Alters Central Nervous System Concentrations of the GLYT2 Glycine Transporter in Zebrafish (Danio rerio) (open access)

Hypoxia-Induced Cardiac Arrest Alters Central Nervous System Concentrations of the GLYT2 Glycine Transporter in Zebrafish (Danio rerio)

Hypoxia as a stressor has physiological implications that have been a focal point for many physiological studies in recent years. In some studies, hypoxia had large effects on the organ tissue degeneration, which ultimately effects multiple ecological processes. These organ tissue studies played a part in the development of new fields like neurocardiology, a specialty that studied the relationship between the brain and the heart. This thesis focuses on how hypoxia-induced cardiac arrest alters the amounts of GLYT2, a glycine reuptake transporter, in the central nervous system of zebrafish, Danio rerio. At 7 days post-fertilization (dpf), zebrafish were exposed to acute, severe hypoxia until they lost equilibrium, and minutes later, subsequent cardiac arrest occurred. Zebrafish were then placed into recovery groups to measure the GLYT2 levels at multiple points in zebrafish recovery. Fish were then sacrificed, and their brains dissected. Using immunofluorescence, the outer left optic tectum of the zebrafish was imaged, and mean image pixel fluorescent intensity was taken. There were significant changes (one-way ANOVA) in the levels of GLYT2 compared to that of the control groups during the course of recovery. GLYT2 levels continued to rise through the 24-hour recovery mark but did not show significant difference after …
Date: July 2023
Creator: Auzenne, Alexis
System: The UNT Digital Library