Language

Utilizing Rapid Mass Spectrometry Techniques to Profile Illicit Drugs from Start to Finish (open access)

Utilizing Rapid Mass Spectrometry Techniques to Profile Illicit Drugs from Start to Finish

The increasingly complex world of illicit chemistry has created a need for rapid, selective means of determining the threat posed by new drugs as they are encountered by law enforcement personnel. To streamline this process, the entirety of the problem, from the production of illicit drugs all the way to the final analysis have been investigated. A series of N-alkylated phenethylamine analogues were synthesized in a shotgun method and subjected to direct-infusion analysis. A range of products were detected without the need for time-consuming purification steps, which was extended to novel pharmacological and receptor-binding assays where mass spectrometry is used as a detector. This direct-infusion technique was also applied to studies of methamphetamine and fentanyl production to preemptively determine improvements to common reaction conditions and explore the origins of common impurities. The ability to utilize these rapid techniques directly from the fume hood has also been critically reviewed to highlight gaps in current research and opportunities for improvement. When combined, these studies seek to provide a means for rapid, simplified analysis of illicit drugs to improve the quality of data and dramatically increase throughput.
Date: August 2018
Creator: McBride, Ethan
System: The UNT Digital Library
Perceived Impacts of a Study Abroad Experience on In-Service Teachers' Practices (open access)

Perceived Impacts of a Study Abroad Experience on In-Service Teachers' Practices

This phenomenological multiple case study provides the details, reasoning, and discussion of the role of study abroad experience and its perceived impact(s) on three in-service teachers. Two research questions were posed: What are the perceived impacts on in-service teachers' practice of a study abroad program experience and how does the in-service teacher's perception of impact change over time within a teacher's career? Results of this study suggest that the teaching practice of in-service teachers who study abroad would benefit, especially in the area of intercultural competence, if this experience is structured in a way where the curriculum of the study abroad program aligns with the content of their future teaching assignment i.e. curricular bridging. Case evidence further suggests that long-term impact of a study abroad experience upon a teacher's practice is related to providing the future teacher an opportunity for to develop and maintain pedagogical relationships with students while abroad. The term ‘submersion' is introduced to help articulate depth of impact during a study abroad program experience.
Date: August 2018
Creator: Felts, Mark T
System: The UNT Digital Library
Physical Activity and Relationship Functioning: Mediation Roles of Sexual Satisfaction and Self-Esteem (open access)

Physical Activity and Relationship Functioning: Mediation Roles of Sexual Satisfaction and Self-Esteem

Little research has examined the role of physical activity in relationship functioning. Utilizing two heterosexual subsamples of 618 females and 155 males, results indicated that physical activity was positively correlated with sexual satisfaction and self-esteem for the female subsample, but was not significant for the male subsample. For both subsamples, although physical activity was not a significant unique predictor of relationship functioning in regression analyses, sexual satisfaction and self-esteem each significantly contributed the variance relationship functioning. The findings of this study increase our knowledge of mechanisms that impact sexual satisfaction, self-esteem, and physical activity among women, which in turn can potentially guide treatment planning and interventions.
Date: August 2018
Creator: Schumacher, Matthew Robert
System: The UNT Digital Library
Computational Methods to Optimize High-Consequence Variants of the Vehicle Routing Problem for Relief Networks in Humanitarian Logistics (open access)

Computational Methods to Optimize High-Consequence Variants of the Vehicle Routing Problem for Relief Networks in Humanitarian Logistics

Optimization of relief networks in humanitarian logistics often exemplifies the need for solutions that are feasible given a hard constraint on time. For instance, the distribution of medical countermeasures immediately following a biological disaster event must be completed within a short time-frame. When these supplies are not distributed within the maximum time allowed, the severity of the disaster is quickly exacerbated. Therefore emergency response plans that fail to facilitate the transportation of these supplies in the time allowed are simply not acceptable. As a result, all optimization solutions that fail to satisfy this criterion would be deemed infeasible. This creates a conflict with the priority optimization objective in most variants of the generic vehicle routing problem (VRP). Instead of efficiently maximizing usage of vehicle resources available to construct a feasible solution, these variants ordinarily prioritize the construction of a minimum cost set of vehicle routes. Research presented in this dissertation focuses on the design and analysis of efficient computational methods for optimizing high-consequence variants of the VRP for relief networks. The conflict between prioritizing the minimization of the number of vehicles required or the minimization of total travel time is demonstrated. The optimization of the time and capacity constraints in …
Date: August 2018
Creator: Urbanovsky, Joshua C.
System: The UNT Digital Library
The Role of Thyroid Hormone on the Development of Endothermy in White Leghorn Chickens (Gallus gallus) (open access)

The Role of Thyroid Hormone on the Development of Endothermy in White Leghorn Chickens (Gallus gallus)

As chickens hatch, there is a rapid change in their physiology and metabolism associated with attaining endothermy. It is thought that thyroid hormones (TH) play a major role in regulating developmental changes at hatching. In birds, TH regulates skeletal muscle growth, which has a direct impact on the chick's ability to thermoregulate via shivering thermogenesis. To better understand the role of TH in the timing of hatching, development of thermogenic capacity, and metabolic rate, we manipulated plasma TH levels in chicken embryos beginning at 85% development (day 17 of a 21 day incubation) with either thyroperoxidase inhibitor methimazole (MMI) or supplemental triiodothyronine (T3). After TH manipulation, we characterized O2 consumption and body temperature in the thermal neutral zone and during gradual cooling. Externally pipped embryos and 1 day post hatch (dph) chicks were cooled from 35 to 15°C. Manipulation of TH altered the timing of hatching, accelerating hatching under hyperthyroid conditions and decelerating hatching with hypothyroid conditions. Cohen's d revealed a large effect size on body temperature (Tb) of EP embryos of hypothyroid animals when compared to euthyroid animals in environmental temperatures of 32°C to 15°C, which was not seen in 1dph animals. Hyperthyroid EP animals were able to maintain …
Date: August 2018
Creator: Rippamonti, Jessica D.
System: The UNT Digital Library
Dataflow Processing in Memory Achieves Significant Energy Efficiency (open access)

Dataflow Processing in Memory Achieves Significant Energy Efficiency

The large difference between processor CPU cycle time and memory access time, often referred to as the memory wall, severely limits the performance of streaming applications. Some data centers have shown servers being idle three out of four clocks. High performance instruction sequenced systems are not energy efficient. The execute stage of even simple pipeline processors only use 9% of the pipeline's total energy. A hybrid dataflow system within a memory module is shown to have 7.2 times the performance with 368 times better energy efficiency than an Intel Xeon server processor on the analyzed benchmarks. The dataflow implementation exploits the inherent parallelism and pipelining of the application to improve performance without the overhead functions of caching, instruction fetch, instruction decode, instruction scheduling, reorder buffers, and speculative execution used by high performance out-of-order processors. Coarse grain reconfigurable logic in an energy efficient silicon process provides flexibility to implement multiple algorithms in a low energy solution. Integrating the logic within a 3D stacked memory module provides lower latency and higher bandwidth access to memory while operating independently from the host system processor.
Date: August 2018
Creator: Shelor, Charles F.
System: The UNT Digital Library
The Roles of Coaches, Peers, and Parents in High School Athletes' Motivational Processes: A Mixed-Methods Study (open access)

The Roles of Coaches, Peers, and Parents in High School Athletes' Motivational Processes: A Mixed-Methods Study

Grounded in self-determination theory and achievement goal theory, the purpose of this mixed-methods study was to examine the underlying motivational processes from social environments created by coaches, peers, and parents to motivational outcomes in high school athletes, with an emphasis on the relative influence of social agents in basic psychological needs (i.e., autonomy, competence, and relatedness). The quantitative part of this study tested a hierarchical model of high school sport motivation in a final sample of 311 student athletes (204 boys, 107 girls) using structural equation modeling: social factors (coach-, peer-, and parent-created motivational climates) -> psychological mediators (need satisfaction and frustration) -> types of motivation (autonomous motivation, controlled motivation, and amotivation) -> consequences (subjective vitality, athlete burnout, and intention to drop out). Invariance across gender and across team type (varsity vs. non-varsity) was also tested. Adequate model fits were achieved in separate "brighter side" and "darker side" models across the overall sample, gender, and team type. The follow-up qualitative part of this study explored "how" beyond "what" coaches, peers, and parents contribute to the social environments, need frustration, and negative motivational outcomes in sport in a subsample of 37 student athletes (24 boys, 13 girls) who reported high amotivation/burnout …
Date: August 2018
Creator: Chu, Tsz Lun
System: The UNT Digital Library
Subjective Efficiencies: Water Use, Management and Governance in the North Platte Natural Resources District (open access)

Subjective Efficiencies: Water Use, Management and Governance in the North Platte Natural Resources District

The North Platte Natural Resources District (NPNRD) is one of 23 quasi-governmental organizations in the state of Nebraska that are organized by river basin and are responsible for the management of groundwater. Conversely, the state's surface water is governed by the Nebraska Department of Natural Resources under the system of prior appropriation. This study uses Foucauldian neoliberal governmentality and a contrasting theory of 'meandering' to explore the conflicting beliefs, perceptions and values that form the foundations of different notions of 'efficiency' as it pertains to water use and management in NPNRD while a political ecology lens is used to situate local perceptions within the regional context of the Platte River Basin. Study findings ultimately point to the remaining 'disintegration' of water governance despite the state's efforts to create legislation that seeks to merge ground and surface water management in practice.
Date: August 2018
Creator: Miller, Elizabeth
System: The UNT Digital Library
Putting Bullying into Perspective: Peer Aggression as a Function of Perspective Taking, Empathy, and Psychological Willingness (open access)

Putting Bullying into Perspective: Peer Aggression as a Function of Perspective Taking, Empathy, and Psychological Willingness

Bullying has long-term negative effects on the mental health and wellbeing of everyone involved. School-wide interventions have been successful in some contexts, but they often require significant institutional and financial resources. Empathy is comprised of a cognitive component (perspective taking) and an affective component (empathic concern), both of which may be necessary for prosocial behavior. According to relational frame theory (RFT), empathy involves a transformation of stimulus functions across deictic relations (I-YOU, HERE-THERE, NOW-THEN), which also requires psychological willingness (i.e., psychological flexibility). The present study investigated this theoretical model of empathy based on RFT and the role of this model in middle school bullying. Results tentatively support this model by demonstrating two ways in which psychological flexibility moderates the relationship between deictic framing ability and empathy. The utility of deictic framing and psychological flexibility in predicting bullying behaviors was also examined. Deictic framing ability and psychological flexibility were expected to negatively predict bullying behaviors, and psychological flexibility was expected to moderate the relationship between deictic framing ability and relational bullying in particular. Additional research questions explored the roles of deictic framing and psychological flexibility in the relationship between relational bullying and other relevant psychological determinants: (a) parental discord, (b) social …
Date: August 2018
Creator: Moyer, Danielle N.
System: The UNT Digital Library
Performance Editions of Three Works for Winds by Gyorgy Druschetzky (open access)

Performance Editions of Three Works for Winds by Gyorgy Druschetzky

Gyorgy Druschetzky was a noted Czech composer of Harmoniemusik, who wrote more than 150 partitas and serenades, along with at least thirty-two other selections for larger wind groups. This is in addition to twenty-seven symphonies, eleven concertos (most for wind instruments), two fantasias, forty-seven string quartets, two operas, a ballet that is lost, and other miscellaneous chamber music for various combinations of wind/string instruments. Three of his works for winds have existed only in manuscript form since their composition: Concerto in E-flat pour 2 clarinett en B, 2 cors en E-flat, 2 fagott; Overture to Mozart's Die Zauberflöte; and Partitta a la camera a corno di bassetto primo, secondo, terzo, due corno di caccia, due fagotti. These works remain remarkably interesting to modern ears and deserve to be heard in the twenty-first century. Along with a brief examination of Druschetzky's life and how it figures into the history of Harmoniemusik, this work presents each piece edited into a modern performance edition.
Date: August 2018
Creator: McDannald, Brandon K.
System: The UNT Digital Library
Two Argentine Song Sets: A Comparison of Songs by De Rogatis and Ginastera (open access)

Two Argentine Song Sets: A Comparison of Songs by De Rogatis and Ginastera

Latin American classical vocal repertoire is vast, but in the United States, we only hear a fairly limited part of this literature. Much of this repertoire blends western European classical music traditions and native folk music traditions. One example of such a Latin American vocal work that is well-known in the United States is Alberto Ginastera's frequently performed song set from 1943, Cinco canciones populares argentinas. However, another lesser-known, earlier work, Cinco canciones argentinas (1923), by fellow Argentine composer Pascual De Rogatis (1880-1980) deserves attention as well. As with Ginastera's set, De Rogatis' songs are based on Argentine folk genres, but contain stylistic features of European classical music of its time. De Rogatis' neglected songs are a significant, overlooked part of Argentine classical music history, and a full understanding of well-known works such as Ginastera's song set and of the genre as a whole, must include attention to De Rogatis' Cinco canciones argentinas. Beyond vocal repertoire, De Rogatis' songs are an important part of the development of Argentine classical music. While Western musical trends change rapidly, folk music remains largely unchanged. Both De Rogatis and Ginastera were proud of their Argentine heritage, and incorporated traditional music into their compositions. I …
Date: August 2018
Creator: Abe, Shoko
System: The UNT Digital Library
Three Essays on Regulatory Focus, Consumer Creativity, and Co-Creation (open access)

Three Essays on Regulatory Focus, Consumer Creativity, and Co-Creation

Co-creation has been conceptualized in a number of ways but is generally referred to as an ongoing partnership between a firm and stakeholders (i.e. consumers) to collaboratively identify and solve mutually beneficial issues. While current scholarship has deepened our knowledge about the process of including consumers in the co-production of value, much remains to be learned. This is particularly true with respect to the consumer behavior side of the discipline as it pertains to creativity and motivation. Thus, the focus of the following three essays is to investigate how customer participation in the ideation of products and advertising influences down-stream responses, depending upon an individual's regulatory focus. According to regulatory focus theory, individuals are motivated to pursue their goals based upon two distinct self-regulatory systems known as promotion and prevention. Promotion-focused consumers are most concerned with the achievement of accomplishments and aspirations, which often results in approach oriented behavior. In contrast, prevention focused individuals seek to avoid negative end states, such as losses, and therefore are concerned with their security, duties, and obligations, resulting in avoidance-related behavior. These two distinct motivational states influence the way these individuals approach creative goals, which shares commonalities with co-creation. By its very nature, the …
Date: August 2018
Creator: Naletelich, Kelly
System: The UNT Digital Library
The Saxophone in China: Historical Performance and Development (open access)

The Saxophone in China: Historical Performance and Development

The purpose of this document is to chronicle and describe the historical developments of saxophone performance in mainland China. Arguing against other published research, this document presents proof of the uninterrupted, large-scale use of the saxophone from its first introduction into Shanghai's nineteenth century amateur musical societies, continuously through to present day. In order to better describe the performance scene for saxophonists in China, each chapter presents historical and political context. Also described in this document is the changing importance of the saxophone in China's musical development and musical culture since its introduction in the nineteenth century. The nature of the saxophone as a symbol of modernity, western ideologies, political duality, progress, and freedom and the effects of those realities in the lives of musicians and audiences in China are briefly discussed in each chapter. These topics are included to contribute to a better, more thorough understanding of the performance history of saxophonists, both native and foreign, in China.
Date: August 2018
Creator: Pockrus, Jason
System: The UNT Digital Library
A Countertenor Aria Collection Continuum for Studio Training and Performance (open access)

A Countertenor Aria Collection Continuum for Studio Training and Performance

An assessment of the standard voice instructor or performer collection of printed music would likely reveal numerous operatic repertoire volumes in anthology format appropriated to the primary four voice categories. However, thorough investigation divulges little in comparable printed material accessible to the countertenor. This scarcity of systemized collections is especially evident in the territory of comprehensive countertenor operatic repertoire. This project fills that present void by creating a compilation of sixteen countertenor arias drawn from various styles and historical periods for suggested application in studio instruction and performance. Perhaps, a more meaningful project intent is the presentation of a beneficial graded literature continuum resource for the studio teacher who instructs a countertenor in various stages of vocal development. For this purpose, each of the 16 arias is categorized into four difficulty levels based on considerations of range, tessitura, coloratura demands, rhythm, sustained phrase length, tonality, melodic considerations/overall musical difficulty, accompaniment support, and ornamentation requirements. The project also addresses common issues of pedagogy and ornamentation for voice teacher consideration when instructing a developing countertenor.
Date: August 2018
Creator: Stanley, David Thomas
System: The UNT Digital Library
A National Idiom Universally Understood: Brazilian Tradition and Personal Evolution in Osvaldo Lacerda's "Variações e Fuga para quinteto de sopros" (open access)

A National Idiom Universally Understood: Brazilian Tradition and Personal Evolution in Osvaldo Lacerda's "Variações e Fuga para quinteto de sopros"

The career of Osvaldo Lacerda (1927-2011) spanned a critical time in the development of Brazilian nationalist music. Though he was an outspoken nationalist composer, he was also influenced by European trends and training. Even within his nationalist compositions, evidence of a shift in style that mirrors the European movements of Modernism and Postmodernism is found in his works. Among his thirty-six chamber works, three are wind quintets, written between 1962 and 1997. Although all three works warrant extended discussion, Variações e Fuga para quinteto de sopros is particularly valuable for studying Lacerda's musical language. It was originally written in 1962. However, Lacerda made significant revisions in 1994, completely rewriting and expanding it. Through comparing the 1962 and 1994 versions of Variações e Fuga and analyzing the significant differences between the two, this document aims show that even with his strong stance as a Brazilian nationalist composer, Lacerda was clearly influenced by the movements of the broader music world. Examples from his other two woodwind quintets, Quinteto de sopro and Suíte pra cinco, written in 1988 and 1997 respectively, help to support the idea that this change in his musical language was not an anomaly, but rather a true evolution of …
Date: August 2018
Creator: Leffler, Hannah
System: The UNT Digital Library
Assessing Perception and Attitude of Pianists toward Ergonomically Scaled Piano Keyboards (ESPK): Raising Awareness about ESPK and Evaluating Changes of Attitude through an Educational Survey (open access)

Assessing Perception and Attitude of Pianists toward Ergonomically Scaled Piano Keyboards (ESPK): Raising Awareness about ESPK and Evaluating Changes of Attitude through an Educational Survey

As epidemiologic research demonstrates health concerns for hand problems among pianists, scientists are measuring historic piano keyboards and realizing that much of the piano literature was composed for and played on pianos with smaller keys compared to what is used on the modern piano. Having to play this literature on a larger keyboard is especially difficult for small-handed piano students and professionals. Fortunately, smaller keyboards are now available for use with standard pianos - and research shows that this ergonomic adjustment does reduce piano-related hand pain for small-handed musicians. Major universities are now offering this option to students, but only a few music schools possess these keyboards and not many people know about them. There are no known research studies to address people's awareness and attitude toward ergonomically scaled piano keyboards (ESPKs). The purpose of this study was to assess perception and attitude toward ESPKs and help to raise its awareness. To examine pianists' perception, two surveys was composed. First one was conducted on UNT campus in which ESPKs are available for their students, and the second survey was carried out on schools of music in the United States. The results reveal that substantial number of people already know about …
Date: August 2018
Creator: Son, Youjoo
System: The UNT Digital Library
"World Life" (open access)

"World Life"

During this time of interest and uncertainty in immigration, a foreigner seeking an education, home, and career wonders how welcoming America really is. This documentary film focuses on how the organization known as World Life is involved in helping international students in terms of language, accommodation, and religion. It follows an organization that is willing to open up and welcome them into the community.
Date: August 2018
Creator: Ingabire, Cyuzuzo
System: The UNT Digital Library
Retail District Evolution: An Exploration of Retail Structure and Diversity, a Case Study in Denton, Texas (open access)

Retail District Evolution: An Exploration of Retail Structure and Diversity, a Case Study in Denton, Texas

It is well established that national retail chains impact small, single location retail businesses in terms of revenue generation, retail structure, retail type diversity, and location. This study examines the retail structure and diversity of five retail districts in the City of Denton, Texas. The analysis focuses on one central business district (CBD), one traditional retail strip center (University Drive, also known as US HWY 380), one special retail district (Fry Street District), one traditional enclosed shopping mall and associated development (Golden Triangle Mall), and one power retail center (Denton Crossing). The empirical foundation for the investigation is a historical business database covering years 1997 to 2010, obtained from Info Group's Reference USA. This Reference USA database includes location, industry, and status (single versus chain location) information for each business. Retail diversity and evenness were measured for each of the five retail districts using the Simpson's Diversity Index and the Simpsons Measure of Evenness, leading to specification of the differences that exist in retail structure and diversity among the districts. Golden Triangle Mall and Denton Crossing were primarily chain location in composition while Fry Street District, the CBD, and University Drive were primarily single location in composition. Across all years, …
Date: August 2018
Creator: Bova, Joshua Paul
System: The UNT Digital Library
Getting the College Experience: Exploring the Effect of the Residential Component of the Upward Bound Summer Program (open access)

Getting the College Experience: Exploring the Effect of the Residential Component of the Upward Bound Summer Program

Upward Bound is a federally funded program designed to help low-income and first-generation high school students become college graduates by providing them with academic enrichment, financial aid information, and relevant educational experiences. Many Upward Bound programs throughout the country include a 6-week summer program when participants stay in residence halls on a university campus. The Upward Bound program at the University of North Texas is one such program. The goals of this research project are to understand how the residential component of the summer program affects the experience of participants in Upward Bound and the possible benefits it may have towards meeting the overall goals of the program. Participant observation during the 2016 UNT Upward Bound summer program and interviews with participants, RAs, program alumni, and organizational leaders uncovered the ways in which the residential component benefits and enriches the experience of participation in Upward Bound.
Date: August 2018
Creator: Krehbiel, Riley M
System: The UNT Digital Library
Laser Surface Modification of AZ31B Mg Alloy Bio-Implant Material (open access)

Laser Surface Modification of AZ31B Mg Alloy Bio-Implant Material

Magnesium and its alloys are considered as the potential biomaterials due to their biocompatibility and biodegradable characteristics but suffer from poor corrosion performance. Various surface modification techniques are employed to improve their corrosion resistance. In present case, laser surface melting was carried out on AZ31B Mg alloy with various laser energy densities using a continuous wave ytterbium laser. Effect of laser treatment on phase and microstructure evolution was evaluated by X ray diffraction and scanning electron microscopy. Multi-physics thermal model predicted time temperature evolution along the depth of the laser treatment zone. Additionally, electrochemical method and bio-immersion test were employed to evaluate the corrosion behavior in simulated body fluid medium. Microstructure revealed grain refinement and even distribution of Mg17Al12 phase along the grain boundary for laser treated samples leading to substantial enhancement in the corrosion resistance of the laser treated samples compared to the untreated alloy. The laser processed samples also possessed a superior wettability in SBF solution than the untreated sample. This was further reflected in enhanced bio-integration behavior of laser processed samples. By changing the parameters of laser processing such as power, scanning speed, and fill spacing, a controllable corrosion resistance and bioactivity/biocompatibility of the implant material was …
Date: August 2018
Creator: Wu, Tso-chang
System: The UNT Digital Library
The Nature of Cognitive Impairment in Multiple Sclerosis (open access)

The Nature of Cognitive Impairment in Multiple Sclerosis

Cognitive impairment is common in multiple sclerosis (MS), with as many as 70% of patients with MS affected. Individuals with MS who experience cognitive deficits are less likely to be employed, and may have more difficulty performing independent activities of daily living. Most commonly, deficits are observed in processing speed, complex attention, and memory. Because lesion location varies widely among individuals, no clear pattern of cognitive dysfunction in MS has emerged. However, a number of risk and protective factors may influence the likelihood of individuals to develop and/or express dysfunction, though the contribution of each to specific domains of cognition has not been fully explored. Recently, support for the cognitive reserve hypothesis (i.e., enriching life experiences protect against cognitive decline despite disease burden) has emerged in the MS literature. The current study investigated the contributions of cognitive reserve to learning and memory functioning in MS and the interaction of cognitive reserve variables and risk factors known to impact cognitive functioning in individuals with MS. Finding revealed cognitive reserve protects against decline in the domains of processing speed and complex attention. Furthermore, indirect protective effects of cognitive reserve through these domains were observed for verbal learning and memory. Finally, in line …
Date: August 2018
Creator: Carlew, Anne R.
System: The UNT Digital Library
High-Energy, Long-Lived Charge-Separated States via Molecular Engineering of Triplet State Donor-Acceptor Systems (open access)

High-Energy, Long-Lived Charge-Separated States via Molecular Engineering of Triplet State Donor-Acceptor Systems

Molecular engineering of donor-acceptor dyads and multimodular systems to control the yield and lifetime of charge separation is one of the key goals of artificial photosynthesis for harvesting sustainably solar energy. The design of the donor-acceptor systems mimic a part of green plants and bacterial photosynthetic processes. The photochemical events in natural photosynthesis involve the capturing and funneling of solar energy by a group of well-organized chromophores referred to as an ‘antenna' system causing an electron transfer into the ‘reaction center,' where an electron transfer processes occur resulting a long-lived charge separated state. Over the last two to three decades, many efforts have been directed by the scientific community designing of multi-modular systems that are capable of capturing most of the useful sunlight and generating charge separated states of prolonged lifetimes with adequate amounts of energy. In this dissertation, we report on the design and synthesis of donor–acceptor conjugates with the goal of modulating the yield and lifetime of their charge separated states and hence, improving the conversion of light energy into chemical potential. In simple donor-acceptor systems, generally, the energy and electron transfer events originate from the singlet excited state of the donor or acceptor and can store the …
Date: August 2018
Creator: Obondi, Christopher O
System: The UNT Digital Library
Genomic Island Discovery through Enrichment of Statistical Modeling with Biological Information (open access)

Genomic Island Discovery through Enrichment of Statistical Modeling with Biological Information

Horizontal gene transfer enables acquisition and dissemination of novel traits including antibiotic resistance and virulence among bacteria. Frequently such traits are gained through the acquisition of clusters of functionally related genes, often referred to as genomic islands (GIs). Quantifying horizontal flow of GIs and assessing their contributions to the emergence and evolution of novel metabolic traits in bacterial organisms are central to understanding the evolution of bacteria in general and the evolution of pathogenicity and antibiotic resistance in particular, a focus of this dissertation study. Methods for GI detection have also evolved with advances in sequencing and bioinformatics, however, comprehensive assessment of these methods has been lacking. This motivated us to assess the performance of current methods for identifying islands on broad datasets of well-characterized bacterial genomes and synthetic genomes, and leverage this information to develop a novel approach that circumvents the limitations of the current state-of-the-art in GI detection. The main findings from our assessment studies were 1) the methods have complementary strengths, 2) a gene-clustering method utilizing codon usage bias as the discriminant criterion, namely, JS-CB, is most efficient in localizing genomic islands, specifically the well-studied SCCmec resistance island in methicillin resistant Staphylococcus aureus (MRSA) genomes, and 3) …
Date: August 2018
Creator: Jani, Mehul
System: The UNT Digital Library
Infinitely Many Solutions of Semilinear Equations on Exterior Domains (open access)

Infinitely Many Solutions of Semilinear Equations on Exterior Domains

We prove the existence and nonexistence of solutions for the semilinear problem ∆u + K(r)f(u) = 0 with various boundary conditions on the exterior of the ball in R^N such that lim r→∞u(r) = 0. Here f : R → R is an odd locally lipschitz non-linear function such that there exists a β > 0 with f < 0 on (0, β), f > 0 on (β, ∞), and K(r) \equiv r^−α for some α > 0.
Date: August 2018
Creator: Joshi, Janak R
System: The UNT Digital Library