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Effects of Transition Metal Oxide and Mixed-Network Formers on Structure and Properties of Borosilicate Glasses (open access)

Effects of Transition Metal Oxide and Mixed-Network Formers on Structure and Properties of Borosilicate Glasses

First, the effect of transition metal oxide (e.g., V2O5, Co2O3, etc.) on the physical properties (e.g., density, glass transition temperature (Tg), optical properties and mechanical properties) and chemical durability of a simplified borosilicate nuclear waste glass was investigated. Adding V2O5 in borosilicate nuclear waste glasses decreases the Tg, while increasing the fracture toughness and chemical durability, which benefit the future formulation of nuclear waste glasses. Second, structural study of ZrO2/SiO2 substitution in silicate/borosilicate glasses was systematically conducted by molecular dynamics (MD) simulation and the quantitative structure-property relationships (QSPR) analysis to correlate structural features with measured properties. Third, for bioactive glass formulation, mixed-network former effect of B2O3 and SiO2 on the structure, as well as the physical properties and bioactivity were studied by both experiments and MD simulation. B2O3/SiO2 substitution of 45S5 and 55S5 bioactive glasses increases the glass network connectivity, correlating well with the reduction of bioactivity tested in vitro. Lastly, the effect of optical dopants on the optimum analytical performance on atom probe tomography (APT) analysis of borosilicate glasses was explored. It was found that optical doping could be an effective way to improve data quality for APT analysis with a green laser assisted system, while laser spot size …
Date: December 2018
Creator: Lu, Xiaonan
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Electrically Tunable Absorption and Perfect Absorption Using Aluminum-Doped Zinc Oxide and Graphene Sandwiched in Oxides (open access)

Electrically Tunable Absorption and Perfect Absorption Using Aluminum-Doped Zinc Oxide and Graphene Sandwiched in Oxides

Understanding the fundamental physics in light absorption and perfect light absorption is vital for device applications in detector, sensor, solar energy harvesting and imaging. In this research study, a large area fabrication of Al-doped ZnO/Al2O3/graphene/Al2O3/gold/silicon device was enabled by a spin-processable hydrophilic mono-layer graphene oxide. In contrast to the optical properties of noble metals, which cannot be tuned or changed, the permittivity of transparent metal oxides, such as Al-doped ZnO and indium tin oxide, are tunable. Their optical properties can be adjusted via doping or tuned electrically through carrier accumulation and depletion, providing great advantages for designing tunable photonic devices or realizing perfect absorption. A significant shift of Raman frequency up to 360 cm-1 was observed from graphene in the fabricated device reported in this work. The absorption from the device was tunable with a negative voltage applied on the Al-doped ZnO side. The generated absorption change was sustainable when the voltage was off and erasable when a positive voltage was applied. The reflection change was explained by the Fermi level change in graphene. The sustainability of tuned optical property in graphene can lead to a design of device with less power consumption.
Date: December 2018
Creator: Adewole, Murthada Oladele
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Elementary Students' Perceptions of Their Authentic Engagement when Using iPads in the Classroom (open access)

Elementary Students' Perceptions of Their Authentic Engagement when Using iPads in the Classroom

The purpose of this study was to examine the impact of a 1:1 iPad initiative on student engagement in the classroom, as perceived by students. The design of this case study consisted of a purposeful sample of six, 5th grade students from a suburban elementary school in North Central Texas who participated in surveys, individual interviews, and focus group discussions. Two research questions guided this study: (1) How do elementary school students perceive they are authentically engaged when using iPads in the classroom? (2) What types of instructional strategies do elementary school students perceive to be most relevant and meaningful? Data collected to answer the research questions was analyzed using thematic analysis, which entailed identifying recurring themes within the data, comparing, coding, combining, and then reporting them. The findings from the research suggested that 1:1 initiatives can foster engaging learning experiences that are meaningful to students and that the iPad provided students a more personalized learning experience which had a positive effect on their engagement. Additional findings disclosed that the type of assignments and schoolwork that students were able to do with the iPad also positively impacted their engagement and interest in the content and their learning. The conclusions reached …
Date: December 2018
Creator: Hayunga, Kelly Lynn
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Establishing Criterion on a Personality-Based Assessment for Employment: A Latent Class Analysis of Faking Behavior (open access)

Establishing Criterion on a Personality-Based Assessment for Employment: A Latent Class Analysis of Faking Behavior

Personality assessments have a long history in psychology and have become the backbone of the human capital management industry, with the Big-Five model being the most prevalent. The central criticism of personality assessments for employment decisions is validity of responses since applicants for employment often endorse items to make themselves more desirable for hire, referred to as faking behavior. The present study examined faking behavior using the Assess Personality Survey (APS). Using a sample of applicant and incumbent data (N = 8,020), the objective was to identify response difference between applicant and incumbents, and the prevalence of faking behavior in applicants. Latent class analysis (LCA) was used to compare groups. Results indicate a clear distinction between applicant and incumbent response patterns. Additional analyses suggest 6 classes of testing patterns among applicants, and results are compared with previous faking identification procedures to improve criteria used to establish faking behavior in respondents.
Date: December 2018
Creator: Johnson, Casey W.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
An Exploration of Elementary L2 Learners' Use of Metacognitive Strategies (open access)

An Exploration of Elementary L2 Learners' Use of Metacognitive Strategies

This multiple case study examined the experiences of elementary L2 learners who received instruction in either reciprocal teaching or the think aloud strategy (TAS), and identified patterns of use that emerged from participants' employment of the strategies. The three L2 participants took a pre- test and a posttest, were recorded using the strategies, and responded to interview questions about the strategies. Using qualitative data analysis techniques, four themes emerged from analysis of the data, including; talking like a teacher, I know what I know, established strategies, and declines to use the steps in the strategy. Implications from these findings suggest that the discussion facilitated by reciprocal teaching assists elementary L2 participants in better understanding the text and also supports their language acquisition, whereas TAS does not facilitate discussion. Further, even though reciprocal teaching promotes discussion, teacher assistance during discussion is necessary. Finally, it is essential that teachers are mindful of students' understandings of topics and the difficulty of texts used when students are learning the strategies.
Date: December 2018
Creator: McNeel, Michele E.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Exploring Growth Kinematics and Tuning Optical and Electronic Properties of Indium Antimonide Nanowires (open access)

Exploring Growth Kinematics and Tuning Optical and Electronic Properties of Indium Antimonide Nanowires

This dissertation work is a study of the growth kinematics, synthesis strategies and intrinsic properties of InSb nanowires (NWs). The highlights of this work include a study of the effect of the growth parameters on the composition and crystallinity of NWs. A change in the temperature ramp-up rate as the substrate was heated to reach the NW growth temperature resulted in NWs that were either crystalline or amorphous. The as-grown NWs were found to have very different optical and electrical properties. The growth mechanism for crystalline NWs is the standard vapor-liquid-solid growth mechanism. This work proposes two possible growth mechanisms for amorphous NWs. The amorphous InSb NWs were found to be very sensitive to laser radiation and to heat treatment. Raman spectroscopy measurements on these NWs showed that intense laser light induced localized crystallization, most likely due to radiation induced annealing of defects in the region hit by the laser beam. Electron transport measurements revealed non-linear current-voltage characteristics that could not be explained by a Schottky diode behavior. Analysis of the experimental data showed that electrical conduction in this material is governed by space charge limited current (SCLC) in the high bias-field region and by Ohm's law in the low …
Date: December 2018
Creator: Algarni, Zaina Sluman
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Exploring the Conceptualization, Operationalization, and Application of Relational Mindfulness (open access)

Exploring the Conceptualization, Operationalization, and Application of Relational Mindfulness

Individuals vary in the level of their mental presence during interactions; some individuals are mentally present with others, while others are mired in their thoughts and emotions. Scholarly work on this area is limited, and we know very little about why some individuals display mental presence better than others. In this dissertation, I explore the concept through a series of three essays. In the first essay, I define relational mindfulness as the ability to be mentally present with others. Further, I propose that relational mindfulness has three essential features: others' focus, thought-switching, and emotional acceptance. I operationalize the scale to measure relational mindfulness and investigate its nomological network by correlating it with different constructs. Data from four different samples provide support for the three-factor structure of relational mindfulness and provide support for the relationship of relational mindfulness with related constructs. In the second essay, I explore the relevance of relational mindfulness for front-line employees by investigating the two pathways through which relational mindfulness can reduce fatigue of front-line employees. In the first pathway, I posited that relational mindfulness would decrease the intensity of surface acting of employees when their customers mistreat them, and thus reduce fatigue of employees. In the …
Date: December 2018
Creator: Sigdyal, Pratigya
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Fabrication and Study of the Optical Properties of 3D Photonic Crystals and 2D Graded Photonic Super-Crystals (open access)

Fabrication and Study of the Optical Properties of 3D Photonic Crystals and 2D Graded Photonic Super-Crystals

In this dissertation, I am presenting my research on the fabrication and simulation of the optical properties of 3D photonic crystals and 2D graded photonic super-crystals. The 3D photonic crystals were fabricated using holographic lithography with a single, custom-built reflective optical element (ROE) and single exposure from a visible light laser. Fully 3D photonic crystals with 4-fold, 5- fold, and 6-fold symmetries were fabricated using the flexible, 3D printed ROE. In addition, novel 2D graded photonic super-crystals were fabricated using a spatial light modulator (SLM) in a 4f setup for pixel-by-pixel phase engineering. The SLM was used to control the phase and intensity of sets of beams to fabricate the 2D photonic crystals in a single exposure. The 2D photonic crystals integrate super-cell periodicities with 4-fold, 5-fold, and 6-fold symmetries and a graded fill fraction. The simulations of the 2D graded photonic super-crystals show extraordinary properties such as full photonic band gaps and cavity modes with Q-factors of ~106. This research could help in the development of organic light emitting diodes, high-efficiency solar cells, and other devices.
Date: December 2018
Creator: Lowell, David
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Friction Stir Welding of Dissimilar Metals (open access)

Friction Stir Welding of Dissimilar Metals

Dissimilar metals joining have been used in many industry fields for various applications due to their technique and beneficial advantages, such as aluminum-steel and magnesium-steel joints for reducing automobile weight, aluminum-copper joint for reducing material cost in electrical components, steel-copper joints for usage in nuclear power plant, etc. The challenges in achieving dissimilar joints are as below. (1) Big difference in physical properties such as melting point and coefficient of thermal expansion led to residual stress and defects. (2) The miscibility issues resulted in either brittle intermetallic compound layer at the welded interface for miscible combinations (such as, aluminum-steel, aluminum-copper, aluminum-titanium, etc.) or no metallurgical bonding for immiscible combinations (such as magnesium-copper, steel-copper, etc.). For metallurgical miscible combinations, brittle intermetallic compounds formed at the welded interface created the crack initiation and propagation path during deformational tests. (3) Stress concentration appeared at the welded interface region during tensile testing due to mismatch in elastic properties of dissimilar materials. In this study, different combinations of dissimilar metals were joined with friction stir welding. Lap welding of 6022-T4 aluminum alloy/galvanized mild steel sheets and 6022-T4 aluminum alloy/DP600 steel sheets were achieved via friction stir scribe technology. The interlocking feature determining the fracture mode …
Date: December 2018
Creator: Wang, Tianhao
Object Type: Thesis or Dissertation
System: The UNT Digital Library
A Grounded Theory Model of the Relationship between Big Data and an Analytics Driven Supply Chain Competitive Strategy (open access)

A Grounded Theory Model of the Relationship between Big Data and an Analytics Driven Supply Chain Competitive Strategy

The technology for storing and using big data is evolving rapidly and those that can keep pace are likely to garner additional competitive advantages. One approach to uncovering existing practice in a manner that provides insights for building theory is the use of grounded theory. The current research employs qualitative research following a grounded theory approach to explore gap in understanding the relationship between big data (BD) and the supply chain (SC). In this study eight constructs emerged: Organizational and environmental factors, big data and supply chain analytics, alignment, data governance, big data capabilities, cost of quality, risk analysis and supply chain performance. The contribution of this research resulted in a new theoretical framework that provides researchers and practitioners with an ability to visualize the relationship between collection and use of BD and the SC. This framework provides a model for future researchers to test the relationships posited and continue to extend understanding about how BD can benefit SC practice. While it is anticipated that the proposed theoretical framework will evolve as a result of future examination and enhanced understating of the relationships shown the framework presented represents a critical first step for moving the literature and practice forward.
Date: December 2018
Creator: Baitalmal, Mohammad Hamza
Object Type: Thesis or Dissertation
System: The UNT Digital Library
The Impact of American Conductors on the Development of Japanese Wind Band Repertoire as Evidenced in the Programming of Tokyo Kosei Wind Orchestra, Musashino Academia Musicae, Showa Academia Musicae, Senzoku Gakuen School of Music, and Tokyo University of the Arts (open access)

The Impact of American Conductors on the Development of Japanese Wind Band Repertoire as Evidenced in the Programming of Tokyo Kosei Wind Orchestra, Musashino Academia Musicae, Showa Academia Musicae, Senzoku Gakuen School of Music, and Tokyo University of the Arts

The wind bands in Japan are considered by many scholars and wind band conductors to be among some of the finest ensembles in today's wind ensemble medium. The literature and repertoire of Japanese ensembles have evolved from orchestral transcriptions, patriotic music, and military marches to original compositions by European, American, and Japanese composers. British conductor Timothy Reynish states that Japanese wind band music has looked traditionally towards the United States and occasionally United Kingdom for inspiration and repertoire. This phenomenon can be attributed to the many collegiate American and the few English wind band conductors who traveled to Japan as guest conductors, and in some cases, became residents of Japan. The focus of this study is to closely examine this significant impact of American collegiate wind band conductors, their influence on Japanese programming and how that programming has affected the collegiate repertoire. This study includes surveys of repertoire, concert programs, discographies of recordings, and interviews with prominent American conductors currently conducting in Japan. This research documents the impact that American wind band conductors have had on the programming of Japanese wind bands and how their influence have altered the collegiate repertoire. Evidence of this impact is documented by Toshio Akiyama, …
Date: December 2018
Creator: Lo, Albert
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Improving Software Quality through Syntax and Semantics Verification of Requirements Models (open access)

Improving Software Quality through Syntax and Semantics Verification of Requirements Models

Software defects can frequently be traced to poorly-specified requirements. Many software teams manage their requirements using tools such as checklists and databases, which lack a formal semantic mapping to system behavior. Such a mapping can be especially helpful for safety-critical systems. Another limitation of many requirements analysis methods is that much of the analysis must still be done manually. We propose techniques that automate portions of the requirements analysis process, as well as clarify the syntax and semantics of requirements models using a variety of methods, including machine learning tools and our own tool, VeriCCM. The machine learning tools used help us identify potential model elements and verify their correctness. VeriCCM, a formalized extension of the causal component model (CCM), uses formal methods to ensure that requirements are well-formed, as well as providing the beginnings of a full formal semantics. We also explore the use of statecharts to identify potential abnormal behaviors from a given set of requirements. At each stage, we perform empirical studies to evaluate the effectiveness of our proposed approaches.
Date: December 2018
Creator: Gaither, Danielle
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Influence of Social Media on Decision Making of the Kuwait National Assembly Members: Case Study (open access)

Influence of Social Media on Decision Making of the Kuwait National Assembly Members: Case Study

In Kuwait, an increase in the use of social media by the Kuwait National Assembly (KNA) has allowed it members to reach out to the public and so advance their political agenda. This study examines social media influences on the decision making process; addresses the lack of academic research in relation to KNA members; and seeks to understand the extent to which public political engagement using social media might affect the outcome of their decision making. The proposed social media influence model (SMIM) was used to explore the relationships and relative importance of variables influencing legislator decision making in a social media environment. The second decade of the twenty-first century saw a number of major issues emerging in Kuwait. A core mixed method design known as explanatory sequential was applied to multiple sets of data generated during KNA members' 14th (2013-2016) and 15th (2016-2018) terms. These data included Twitter messages (tweets), the KNA Information Center Parliamentary Information System legislation documents, and the news media articles. The sample was drawn from KNA membership, some of which used Twitter to comment on major events with specific hashtags and the Kuwaiti news media articles related to the same. Study results confirm and support …
Date: December 2018
Creator: Alfarhoud, Yousef T.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
The Influence of Visual Sources of Nutrition-Oriented Information on Young Adults' Dieting Efforts (open access)

The Influence of Visual Sources of Nutrition-Oriented Information on Young Adults' Dieting Efforts

The goal of this study was to investigate visual sources of nutrition information relied upon by young adults, specifically college-aged students between 18-30, as this is an under-represented population within current academic literature. A sample of more than 700 18- to 30-year-old college students were surveyed regarding their use of nutrition-driven information, with specific questions regarding the participants' awareness and use of the Food and Drug Administration's standardized nutrition facts labels, as well as the use of smartphone applications for tracking one's food and beverage consumption on a regular basis. Using structural equation modeling, a statistically significant theoretical model was developed with regards to individuals finding greater long-term satisfaction in their dieting efforts if they tracked their consumption on a regular basis, with even greater significance being found through the aid of smartphone applications for recording consumption. An analysis of the content of three online diet and exercise-driven brands was also conducted to determine the currently optimal social media platform for nutrition information exchange, and to identify the type of diet-driven information that generates the greatest amount of engagement within an online network. Of the social media platforms analyzed, Instagram proved to be the most optimal for nutrition information-exchange, and …
Date: December 2018
Creator: Stark, Hillary Lynn
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Information Seeking in a Balkan Country: A Case Study of College Students Seeking and Use of Information (open access)

Information Seeking in a Balkan Country: A Case Study of College Students Seeking and Use of Information

Using a case study approach this study investigated how college students in Vlore, Albania seek and use information resources for academic and personal needs and whether they follow a pattern similar to Brenda Dervin's sense-making, or Marcia Bates' berry-picking information seeking models. Influencing factors studied were economic factors, information communication technologies and information culture/policy. A literature review showed that no previous published research has studied information seeking behavior of college age students and faculty in Albania. Thirty-four college students and two full time faculty completed a survey and a smaller group were interviewed. The results of the study indicate that Google is the main source for seeking information for both academic and personal purposes. College students are not introduced or taught on how to evaluate information sources. The information communication technology needs improvement to support information needs. The library as a major information resource was not apparent to most students. College students utilize berry-picking as the information seeking model and faculty use sense-making, as a model of information seeking. This study adds to the knowledge of the information seeking behavior of college students in a developing country, the need for information literacy courses at the university level, and the identification …
Date: December 2018
Creator: Kabashi, Artemida
Object Type: Thesis or Dissertation
System: The UNT Digital Library
An Instructional Guide to Teaching Dan Beaty's Woodsprite and Waterbug Collection for Intermediate Piano Students and Instructors (open access)

An Instructional Guide to Teaching Dan Beaty's Woodsprite and Waterbug Collection for Intermediate Piano Students and Instructors

The purpose of this dissertation is to offer a pedagogical guide to Woodsprite and Waterbug Collection (1977) by Dan Beaty (1937-2002) through an analysis of its pedagogical values and teaching applications. This set consists of twelve short, intermediate-level pieces, featuring various contemporary idioms. Each piece is also pedagogically written to help intermediate students to refine specific pianistic techniques beyond the elementary level. In addition, Beaty's collection expands students' musical vision and musicianship for more advanced studies via the incorporation of contemporary music theory and techniques. These qualities make Woodsprite and Waterbug Collection a valuable tool for intermediate piano students. It is also useful for instructors searching for repertoire to introduce contemporary idioms. The author hopes that this study will encourage performers, teachers and scholars to consider this work and Beaty's other piano compositions. By studying Woodsprite and Waterbug Collection, students will be more appreciative of contemporary repertoire and will welcome learning similar pieces in the future.
Date: December 2018
Creator: Hung, Sophie (Shuo-Hui)
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Investigation, Interpretation and Internalization in Concerto Piccolino for Vibraphone by Milton Babbitt (open access)

Investigation, Interpretation and Internalization in Concerto Piccolino for Vibraphone by Milton Babbitt

Written in 1999, Concerto Piccolino is a part of the Composer's Guild of New Jersey Vibraphone Commission, which contains a collection of twelve soli written exclusively for vibraphone. Concerto Piccolino presents vibrant opportunities for both performer and listener to experience the compositional world of Milton Babbitt. With its limited register, ability to control duration and create extreme dynamics, the vibraphone serves as an appropriate vehicle for Babbitt's multi-dimensional style. The intent of this study is to first situate this work into Babbitt's compositional output as well as referencing Babbitt's other works for solo percussion. Next, an investigation into the background structure will provide a recommended analytical framework. Included is a performance guide for how these structures should be realized via surface materials throughout the interpretive and internalization stages of the work. Examining a recommended progression from analysis through performance will demonstrate Concerto Piccolino's significance and proper place in the standard repertoire of percussion. The study concludes with discussing connections to pedagogy and how the importance of Babbitt's work, as well as other composers of serious music, is vital to the forward progress of music performance.
Date: December 2018
Creator: Yakas, James
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Isolation and Genomic Characterization of 45 Novel Bacteriophages Infecting the Soil Bacterium Streptomyces griseus (open access)

Isolation and Genomic Characterization of 45 Novel Bacteriophages Infecting the Soil Bacterium Streptomyces griseus

Bacteriophages, or simply "phages," are the most abundant biological entities on the planet and are thought to be the largest untapped reservoir of available genetic information. They are also important contributors to both soil health and nutrient recycling and have significantly influenced our current understanding of molecular biology. Bacteria in the genus Streptomyces are also known to be important contributors to soil health, as well as producing a number of useful antibiotics. The genetic diversity of large (> 30) groups of other actinobacteriophages, i.e. phages infecting a few close relatives of the Streptomycetes, has been explored, but this is the first formal effort for Streptomyces-infecting phages. Described here are a group of 45 phages, isolated from soil using a single Streptomycete host, Streptomyces griseus ATCC 10137. All 45 phages are tailed phages with double-stranded DNA. Siphoviruses predominate, six of the phages are podoviruses, and no myoviruses were observed. Notably present are seven phages with prolate icosahedral capsids. Genome lengths and genome termini vary considerably, and the distributions of each are in line with findings among other groups of studied actinobacteriophages. Interestingly, the average G+C among the 45 phages is around 11% lower than that of the isolation host, a larger …
Date: December 2018
Creator: Hale, Richard
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Jeff Pickell: New and Selected (open access)

Jeff Pickell: New and Selected

A collection of prose.
Date: December 2018
Creator: Pickell, Jeffrey A
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Kaikhosru Sorabji's Rapsodie Espagnole de Maurice Ravel, Transcription de Concert pour piano: A Comparison of the Two Versions from 1923 and 1945 (open access)

Kaikhosru Sorabji's Rapsodie Espagnole de Maurice Ravel, Transcription de Concert pour piano: A Comparison of the Two Versions from 1923 and 1945

Kaikhosru Shapurji Sorabji (1892-1988) was an English composer-pianist of Parsi descent. Although he composed many works for piano, these compositions remain largely unknown to the public due to the composer's self-imposed 40-year ban on public performances of all his works and the immense technical difficulty of his music. This research proposes a comparative study of Sorabji's two versions of Rapsodie espagnole de Maurice Ravel-Transcription de concert pour piano (1923, 1945). These transcriptions are based on Ravel's orchestral work and are different in terms of the style of their arrangements: the 1923 version is more of a literal transcription, whereas the 1945 version has been expanded upon the former. This dissertation compares the differences between the two versions, as well as identifying how Sorabji infused his own style into the 1945 transcription. This study relies on primary sources including writings and manuscripts of Sorabji, and secondary sources such as articles on interpreting Sorabji's piano works and biographies about Sorabji.
Date: December 2018
Creator: Chu, Fang-Yi
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Key Factors Influencing Retention Rates among Historically Underrepresented Student Groups in STEM Fields (open access)

Key Factors Influencing Retention Rates among Historically Underrepresented Student Groups in STEM Fields

The aim of the study was to identify the factors that have an influence on the completion rates of undergraduate students in the fields of science, technology, engineering and mathematics (STEM). Using Tinto's retention rate theory as the theoretical foundation, data were collected from freshman who were enrolled in the years 2005 to 2008. Results showed gender and first-generation status were significant predictors of STEM completion and time taken to complete the degree. Institutional bias played a role in race/ethnicity not being a factor affecting completion rates, as this study was conducted at a Predominantly White Institution. SAT scores and first and second-year college GPA showed to have the most prominent influence on both STEM completion rate and time taken to complete the degree. Females with higher first-year college GPA and higher high school rank finished faster. Similar results were found with first-generation students as well. Students belonging to ethnic minority groups with higher SAT scores and college GPA had greater success in STEM fields as well. The study results can be used to increase completion rates of underrepresented students in the STEM fields, given what we know about the interactions between underrepresented student groups and the most important predictors.
Date: December 2018
Creator: Premraj, Divya
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Lipogenic Proteins in Plants: Functional Homologues and Applications (open access)

Lipogenic Proteins in Plants: Functional Homologues and Applications

Although cytoplasmic lipid droplets (LDs) are the major reserves for energy-dense neutral lipids in plants, the cellular mechanisms for packaging neutral lipids into LDs remain poorly understood. To gain insights into the cellular processes of neutral lipid accumulation and compartmentalization, a necessary step forward would be to characterize functional roles of lipogenic proteins that participate in the compartmentalization of neutral lipids in plant cells. In this study, the lipogenic proteins, Arabidopsis thaliana SEIPIN homologues and mouse (Mus Musculus) fat storage-inducing transmembrane protein 2 (FIT2), were characterized for their functional roles in the biogenesis of cytoplasmic LDs in various plant tissues. Both Arabidopsis SEIPINs and mouse FIT2 supported the accumulation of neutral lipids and cytoplasmic LDs in plants. The three Arabidopsis SEIPIN isoforms play distinct roles in compartmentalizing neutral lipids by enhancing the numbers and sizes of LDs in various plant tissues and developmental stages. Further, the potential applications of Arabidopsis SEIPINs and mouse FIT2 in engineering neutral lipids and terpenes in plant vegetative tissues were evaluated by co-expressing these and other lipogenic proteins in Nicotiana benthamiana leaves. Arabidopsis SEIPINs and mouse FIT2 represent effective tools that may complement ongoing strategies to enhance the accumulation of desired neutral lipids and terpenes …
Date: December 2018
Creator: Cai, Yingqi
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Lollardy and Eschatology: English Literature c. 1380-1430 (open access)

Lollardy and Eschatology: English Literature c. 1380-1430

In this dissertation, I examine the various ways in which medieval authors used the term "lollard" to mean something other than "Wycliffite." In the case of William Langland's Piers Plowman, I trace the usage of the lollard-trope through the C-text and link it to Langland's dependence on the Parable of the Wheat and the Tares. Regarding Chaucer's Parson's Tale, I establish the orthodoxy of the tale's speaker by comparing his tale to contemporaneous texts of varying orthodoxy, and I link the Parson's being referred to as a "lollard" to the eschatological message of his tale. In the chapter on The Book of Margery Kempe, I examine that the overemphasis on Margery's potential Wycliffism causes everyone in The Book to overlook her heretical views on universal salvation. Finally, in comparing some of John Lydgate's minor poems with the macaronic sermons of Oxford, MS Bodley 649, I establish the orthodox character of late-medieval English anti-Wycliffism that these disparate works share. In all, this dissertation points up the eschatological character of the lollard-trope and looks at the various ends to which medieval authors deployed it.
Date: December 2018
Creator: Regetz, Timothy
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Long-Term Citizen Science Water Monitoring Data: An Exploration of Accuracy over Space and Time (open access)

Long-Term Citizen Science Water Monitoring Data: An Exploration of Accuracy over Space and Time

The Texas Stream Team (TST) is one of an increasing number of citizen science water monitoring programs throughout the US which have been continuously collecting surface water quality data under quality assurance protocols for decades. Volunteer monitoring efforts have generated monitoring datasets that are long-term, continuous, and cover a large geographic area - characteristics shown to be valuable for scientists and professional agencies. However, citizen science data has been of limited use to researchers due to concerns about the accuracy of data collected by volunteers, and the decades of water quality monitoring data collected by TST volunteers is not widely used, if at all. A growing body of studies have attempted to address accuracy concerns by comparing volunteer data to professional data, but this has rarely been done with large-scale, existing datasets like those collected by TST. This study assesses the accuracy of the volunteer water quality data collected across the state of Texas by the TST citizen science program between 1992-2017 by comparing it to professional data from corresponding stations during the same time period, as well as comparing existing and experimental data from a local TST partner agency. The results indicate that even large-scale, existing volunteer and professional …
Date: December 2018
Creator: Albus, Kelly
Object Type: Thesis or Dissertation
System: The UNT Digital Library