Degree Level

Copper Wire-Bonding Reliability: Mechanism and Prevention of Galvanic Aluminum Bond Pad Corrosion in Acidic Chloride Environments

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With the reliability requirements of automobile microelectronics pushing towards near 0 ppb levels of failure control, halide induced corrosion issues in wire bonded devices have to be tightly controlled to achieve such a high reliability goal. With real-time corrosion monitoring, for the first time we demonstrated that the explosive H2 evolution coupled with the oxygen reduction reaction, occurring at the critical Al/Cu interfaces, is the key driving force for the observed aggressive corrosion. Several types of passivation coating on Cu wire surfaces to effectively block the cathodic H2 evolution were explored with an aim to disrupt this explosive corrosion cycle. The properties of the protective coating were evaluated using various analytical techniques. The surface coating exhibited high thermal stability up to 260 °C (evaluated using TGA analysis). A uniform, highly hydrophobic coating (surface contact angle of >130° with water), was achieved by carefully controlling CVD parameters such as time of deposition, surface control of Cu metal, amount of inhibitor compound loading, temperature of coating process etc. FTIR spectroscopy combined with corrosion screening was used to optimize the CVD passivated coating with strong chemisorption. SEM and EDX, XPS were carried out on various coated surfaces to understand the composition and selectivity …
Date: May 2020
Creator: Asokan, Muthappan
System: The UNT Digital Library

Characterization, Analysis, and Optimization of Rotary Displacer Stirling Engines

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This work focuses on an innovative Rotary Displacer SE (RDSE) configuration for Stirling engines (SEs). RDSE features rotary displacers instead of reciprocating displacers (found in conventional SE configurations), as well as combined compression and expansion spaces. Guided by the research question "can RDSE as a novel configuration achieve a higher efficiency compared to conventional SE configurations at comparable operating conditions?", the goal of this study is to characterize, analyze, and optimize RDSE which is pursued in three technical stages. It is observed the RDSE prototype has an optimum phase angle of > 90° and thermal efficiency of 15.5% corresponding to 75.2% of the ideal (Carnot) efficiency at the source and sink temperatures of 98.6° C and 22.1° C, respectively. Initial results indicate that 125° phase angle provides more power than that of the theoretically optimum 90° phase angle. The results also show comparable B_n and significantly higher W_n values (0.047 and 0.465, respectively) compared to earlier studies, and suggest the RDSE could potentially be a competitive alternative to other SE configurations. Furthermore, due to lack of a regenerator, the non-ideal effects calculated in the analytical approach have insignificant impact (less than 0.03 kPa in 100 kPa). The clearance volume in …
Date: December 2019
Creator: Bagheri, Amirhossein
System: The UNT Digital Library

Computational Development of Trimetallic Cyclotrimers for Gas-Filtration Applications through Non-Covalent Interactions

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Photophysical properties of an array of various polyaromatic hydrocarbons were benchmarked with B3LYP, M06 and B97D methods coupled with Pople and CEP-31G(d) basis sets. Results from the benchmark show the importance of diffuse basis sets when modeling the electronic properties of highly conjugated systems and provide qualitative reliable accuracy with certain levels of theory. B97D and M06 are applied to modeling pyrene adducts governed by non-covalent interactions in both gaseous and condensed states to reproduce experimental spectra. DFT calculations with both B97D and M06 functionals show qualitatively and quantitatively that pyrene dimer is a stronger π–base as compared to its monomer. Binding energies coupled with MEP, PCA and Qzz results show that the difference in π-basicity of the monomer and dimer impacts the supramolecular chemistry involved in adducts formed with super π-acidic silver cyclometallic trimer (CTC). Non-covalent interactions between coinage metal CTCs and ammonia/phosphine substrates is reported. Interactions between these substrates and the facial plane of the π-rich gold CTC reveal a novel interaction, where the typical Lewis acid/base roles are reversed for the substrates. Adducts formed through this type of interaction define typical Lewis bases like ammonia and phosphine as Lewis acids, wherein the partially positive hydrogens coordinate to …
Date: December 2019
Creator: Williams, Christopher M.
System: The UNT Digital Library

Deep Learning Approach for Sensing Cognitive Radio Channel Status

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Cognitive Radio (CR) technology creates the opportunity for unlicensed users to make use of the spectral band provided it does not interfere with any licensed user. It is a prominent tool with spectrum sensing functionality to identify idle channels and let the unlicensed users avail them. Thus, the CR technology provides the consumers access to a very large spectrum, quality spectral utilization, and energy efficiency due to spectral load balancing. However, the full potential of the CR technology can be realized only with CRs equipped with accurate mechanisms to predict/sense the spectral holes and vacant spectral bands without any prior knowledge about the characteristics of traffic in a real-time environment. Multi-layered perception (MLP), the popular neural network trained with the back-propagation (BP) learning algorithm, is a keen tool for classification of the spectral bands into "busy" or "idle" states without any a priori knowledge about the user system features. In this dissertation, we proposed the use of an evolutionary algorithm, Bacterial Foraging Optimization Algorithm (BFOA), for the training of the MLP NN. We have compared the performance of the proposed system with the traditional algorithm and with the Hybrid GA-PSO method. With the results of a simulation experiment that this …
Date: December 2019
Creator: Gottapu, Srinivasa Kiran
System: The UNT Digital Library

Ensemble Singing in the Bel Canto Salon Repertory: A Pedagogical Reconsideration

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Vocal duets have had a long history in the Western classical music tradition. Their use as a teaching resource can be traced back to the Renaissance, where duets were used for the development of singing, performance, and musicianship. In the late 19th and all of the 20th centuries, this pathway of vocal pedagogy has markedly declined. This study proposes a reintroduction of this methodology of teaching, asserting that it provides the collegiate vocal student with maximum opportunity for growth and development in terms of technique, musicianship, ensemble skills, and performance development. Four vocal duets ("La pesca," "Il brindisi," "Il gallop," and "La caccia") of Saverio Mercadante (1795-1870) serve as the point of discussion. These songs from Les soirées italiennes (C.1836), which are representative of the salon culture of the 19th century, are given detailed attention through a discussion of their pedagogical value. Since they are long out of print, a new performance edition is presented.
Date: December 2019
Creator: Brown, Shaun (Shaun Joseph)
System: The UNT Digital Library

An Exploration of Professional Training and Professional Practice: Title IX Administrators and Meaning Making

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Federal law requires institutions to designate campus-based administrators to oversee Title IX processes and investigations, but little is known about how these have been professionally prepared for their roles. The purpose of this study was to understand the professional preparation, educational experiences, and professional training of Title IX administrators and to understand their independence in decision-making in those roles. This study utilized qualitative content analysis and a social constructionist approach to analyze data generated from interviews and document analysis. Sixteen current and former Title IX administrators (investigators, deputy coordinators, coordinators) provided their perspectives on their professional training and development. Using frameworks of work/professional socialization and professions theory, findings illustrated complex systems for knowledge acquisition, professional preparation, and professional socialization based on factors including resources, institutional context, and role prioritization. Participants' formal education, formative experiences, position-specific training, and professional organizations training all served as preparation for their roles. Discussion focused on implications for graduate programs, training and trainers, institutions and supervisors, the field of higher education, and current Title IX practitioners regarding professional preparation for these roles.
Date: December 2019
Creator: Razo, Demesia
System: The UNT Digital Library

Investigations of the Fresnel Lens Based Solar Concentrator System through a Unique Statistical-Algorithmic Approach

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This work investigates the Fresnel-lens-based solar concentrator-receiver system in a multi-perspective manner to design, test and fabricate this concentrator with high-efficiency photon and heat outputs and a minimized effect of chromatic aberrations. First, a MATLAB®-incorporated algorithm optimizes both the flat-spot and the curved lens designs via a statistical ray-tracing methodology of the incident light, considering all of its incidence parameters. The target is to maximize the solar ray intensity on the receiver's aperture, and therefore, achieve the highest possible focal flux. The algorithm outputs prismatic and dimensional geometries of the Fresnel-lens concentrator, which are simulated by COMSOL® Multiphysics to validate the design. For the second part, a novel genetically-themed hierarchical algorithm (GTHA) has been investigated to design Fresnel-lens solar concentrators that match with the distinct energy input and spatial geometry of various thermal applications. Basic heat transfer analysis of each application decides its solar energy requirement. The GTHA incorporated in MATLAB® optimizes the concentrator characteristics to secure this energy demand, balancing a minimized geometry and a maximized efficiency. Two experimental applications were selected from literature to validate the optimization process, a solar welding system for H13 steel plates and a solar Stirling engine with an aluminum-cavity receiver attached to the …
Date: December 2019
Creator: Qandil, Hassan Darwish Hassan
System: The UNT Digital Library

Manipulation of Light-Matter Interactions in Molybdenum Disulfide (MoS2) Monolayer through Dressed Phonons (DP) and Plasmons

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The performance of electrical and optical devices based on two-dimensional semiconductors (2D) such as molybdenum disulfide is critically influenced due to very poor light absorption in the atomically thin layers. In this study, the phonon mediated optical absorption and emission properties in single atomic layers of MoS2 have been investigated. The electronic transitions in MoS2 due to near-field optical interaction and the influence of interface phonons due to the dielectric substrate GaN on the relaxation of optically generated carriers will be described. The near-field interaction can be induced in the presence of metal plasmons deposited on the surface of MoS2 monolayers. A hybrid metal-semiconductor system was realized by the deposition of silver (Ag) NPs on MoS2 layer and the localized plasmon modes were selectively chosen to interact with quasiparticles such as excitons and phonons. These quasiparticles are confined within the single atomic layer of MoS2 and are stable at room temperatures due to high binding energy. The lattice vibrational modes in MoS2 can be optically excited with the pulses from a femtosecond laser. These phonon modes can be optically dressed due to near-field interaction in the hybrid Ag-MoS2 system under an optical excitation resonant to localized plasmon modes. The coherent …
Date: December 2019
Creator: Poudel, Yuba R
System: The UNT Digital Library

Nano-Manufacturing of Catalytic Amorphous Alloys

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In this dissertation, nano-manufacturing of amorphous alloys for electro-catalytic applications is reported and the role of chemistry and active surface area on catalytic behavior is discussed. The catalytic activity of recently developed platinum and palladium-based metallic glasses was studied using cyclic voltammetry and localized electrochemical techniques. The synergistic effect between platinum and palladium was shown for amorphous alloys containing both these elements. The mechanism for superior catalytic behavior was investigated through electronic structure and surface chemical state of the alloys. A correlation between the work function and catalytic performance of the amorphous alloys with widely varying chemistries was established. To address the high cost associated with the noble-metal containing catalysts, the performance of non-noble Ni-P amorphous catalyst was evaluated for electro-catalysis. A facile pulsed electrodeposition approach was used for the nano-manufacturing of these amorphous catalysts. This nano-manufacturing route allowed the synthesis of fully amorphous nano-wires at room temperature for alloys with little or no noble-metal content. A wide range of nano-wires with varying aspect ratios from 25 to 120 was synthesized using commercially obtained anodic aluminum oxide (AAO) nano-molds. Cyclic voltammetry and chrono-amperometry demonstrated superior performance in terms of electrocatalytic activity and stability of the metallic glass nano-wires towards electro-oxidation …
Date: December 2019
Creator: Hasannaeimi, Vahid
System: The UNT Digital Library

PAOFLOW-Aided Computational Materials Design

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Functional materials are essential to human welfare and to provide foundations for emerging industries. As an alternative route to experimental materials discovery, computational materials designs are playing an increasingly significant role in the whole discovery process. In this work, we use an in-house developed python utility: PAOFLOW, which generates finite basis Hamiltonians from the projection of first principles plane-wave pseudopotential wavefunctions on pseudo atomic orbitals(PAO) for post-process calculation on various properties such as the band structures, density of states, complex dielectric constants, diffusive and anomalous spin and charge transport coefficients. In particular, we calculated the dielectric function of Sr-, Pb-, and Bi-substituted BaSnO3 over wide concentration ranges. Together with some high-throughput experimental study, our result indicates the importance of considering the mixed-valence nature and clustering effects upon substitution of BaSnO3 with Pb and Bi. We also studied two prototype ferroelectric rashba semiconductors, GeTe and SnTe, and found the spin Hall conductivity(SHC) can be large either in ferroelectric or paraelectric structure phase. Upon doping, the polar displacements in GeTe can be sustained up to a critical hole concentration while the tiny distortions in SnTe vanish at a minimal level of doping. Moreover, we investigated the sensitivity of two dimensional group-IV monochalcogenides …
Date: December 2019
Creator: Wang, Haihang
System: The UNT Digital Library

A Performance and Security Analysis of Elliptic Curve Cryptography Based Real-Time Media Encryption

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This dissertation emphasizes the security aspects of real-time media. The problems of existing real-time media protections are identified in this research, and viable solutions are proposed. First, the security of real-time media depends on the Secure Real-time Transport Protocol (SRTP) mechanism. We identified drawbacks of the existing SRTP Systems, which use symmetric key encryption schemes, which can be exploited by attackers. Elliptic Curve Cryptography (ECC), an asymmetric key cryptography scheme, is proposed to resolve these problems. Second, the ECC encryption scheme is based on elliptic curves. This dissertation explores the weaknesses of a widely used elliptic curve in terms of security and describes a more secure elliptic curve suitable for real-time media protection. Eighteen elliptic curves had been tested in a real-time video transmission system, and fifteen elliptic curves had been tested in a real-time audio transmission system. Based on the performance, X9.62 standard 256-bit prime curve, NIST-recommended 256-bit prime curves, and Brainpool 256-bit prime curves were found to be suitable for real-time audio encryption. Again, X9.62 standard 256-bit prime and 272-bit binary curves, and NIST-recommended 256-bit prime curves were found to be suitable for real-time video encryption.The weaknesses of NIST-recommended elliptic curves are discussed and a more secure new …
Date: December 2019
Creator: Sen, Nilanjan
System: The UNT Digital Library

The Rise and Fall of the Greenback Party in Texas: Economic Change and Political Dissent in the Post-Civil War Era

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In 1873, a financial crisis plunged the United States into a deep economic depression that exacerbated a number of post-war economic issues. By the late 1870s, political dissent centered primarily on financial issues merged into the Greenback movement, which represented a loose coalition of reformers calling for economic relief based on the expanded use of greenbacks (paper currency issued by the United States Treasury during the Civil War). The Greenback Party emerged as a direct response to federal financial policies, but in Texas, it also provided a broad political platform for those opposed to the policies of "Redeemer/Bourbon" Democrats. The Greenback Party of Texas brought together a wide range of dissenters, including disgruntled Democrats, ousted Republicans, and many different economic and social reformers. From 1876, when the first Greenback clubs appeared in Texas, to the Greenback Party's virtual disappearance after the election of 1884, the Texas Greenbackers reached across boundaries of section, race, class, and sometimes gender; brought together farmers, workers, and professionals; Southerners and Northerners, white and black; former Confederates and former Unionists; native-born Americans and immigrants; and received sizable support from multiple counties in the northern, eastern, and central part of the state. In spite of its short …
Date: December 2019
Creator: Sinclair, Cameron L.
System: The UNT Digital Library

Spatial Partitioning Algorithms for Solving Location-Allocation Problems

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This dissertation presents spatial partitioning algorithms to solve location-allocation problems. Location-allocations problems pertain to both the selection of facilities to serve demand at demand points and the assignment of demand points to the selected or known facilities. In the first part of this dissertation, we focus on the well known and well-researched location-allocation problem, the "p-median problem", which is a distance-based location-allocation problem that involves selection and allocation of p facilities for n demand points. We evaluate the performance of existing p-median heuristic algorithms and investigate the impact of the scale of the problem, and the spatial distribution of demand points on the performance of these algorithms. Based on the results from this comparative study, we present guidelines for location analysts to aid them in selecting the best heuristic and corresponding parameters depending on the problem at hand. Additionally, we found that existing heuristic algorithms are not suitable for solving large-scale p-median problems in a reasonable amount of time. We present a density-based decomposition methodology to solve large-scale p-median problems efficiently. This algorithm identifies dense clusters in the region and uses a MapReduce procedure to select facilities in the clustered regions independently and combine the solutions from the subproblems. Lastly, …
Date: December 2019
Creator: Gwalani, Harsha
System: The UNT Digital Library

A Study of Selected Pedagogical Aspects of Two Intercultural Pieces for Late Intermediate and Early Advanced Students: "Variations sur un thème populaire coréen" by Sung-Ki Kim and "Six Pieces for Piano ‘Nori'" by Chung-Sock Kim

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I contend that young students should be introduced to intercultural contemporary music, as this exposure brings benefits to their artistic development and fosters appreciation of other cultures. Variations sur un thème populaire coréen by Sung-Ki Kim (b. 1954) and Six Pieces for Piano ‘Nori' by Chung-Sock Kim (b. 1940) are effective pedagogical works that fit perfectly into the intercultural mold mentioned above, and both are suitable for late intermediate or early advanced level students. A detailed comparison of these two works can help instructors understand the ways by which these composers incorporate Korean folk materials and blend them with Western contemporary techniques. An analysis of Sung-Ki Kim's Variations sur un theme populaire coréen and Chung-Sock Kim's Six Pieces for Piano ‘Nori' can be divided into three categories: harmony, rhythm, and performance-related aspects. By analyzing these two pieces, these study illustrates in greater depth their intercultural aspects, showing the way by which both composers merged traditional Korean folk idioms through the inclusion of traditional Korean rhythms, and the imitation of sounds of several traditional Korean instruments with Western contemporary technique such as non-traditional sounds and use of sostenuto pedal. Finally, this study provides some practicing suggestions and listing exercise on how …
Date: December 2019
Creator: Choi, Yujin
System: The UNT Digital Library

Tchaikovsky's Piano Concerto No. 1 In B-Flat Minor, Op. 23: A Newly Arranged Edition of the Orchestral Reduction

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As it stands, only one arrangement of Tchaikovsky's Piano Concerto No. 1, Op. 23 orchestral reduction exists, which is by Tchaikovsky himself. A number of critical editions of the piece exist, but none of them cover the subject of the material within the orchestral reduction. Tchaikovsky wrote the reduction from a compositional rather than a pianistic perspective, thus some passages present awkward technical challenges. The purpose of this dissertation is ultimately to contribute to the repertoire of accompanists by producing a new edition of Tchaikovsky's Piano Concerto No. 1. I created my arrangement through a process of practical trial and error as well as observing the strategies used by other arrangers of orchestral reductions. Through a series of carefully selected omissions, note rearrangements, visual adjustments, and editorial changes, I simplified the reduction as a whole. I sought to improve the readability of the music by reducing accidentals as much as possible and also incorporating small-print cues into the main staves. Each minor adjustment or major revision contributes cumulatively to the ease of execution of the accompanimental part as a whole. Although Tchaikovsky's reduction is authentic and authoritative, a newly revised and simplified version would be useful for collaborative pianists. Thus, …
Date: December 2019
Creator: Parys, Marcin
System: The UNT Digital Library

Uncovering Fanny Hensel's "Das Jahr": Creating an Urtext Edition that Addresses Selected Technical and Interpretive Issues through Added Fingerings and Pedal Markings

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Das Jahr is considered Fanny Hensel's most impressive accomplishment of piano solo work. However, the only modern edition that is extant includes many additional editorial markings. By further analyzing the sections that are technically challenging or musically demanding from an interpretive standpoint, pianists wishing to perform the work will have to find workable fingerings and pedal markings to learn this piano cycle. For this reason, this dissertation will not only provide readers with an original text of Das Jahr, but also assist pianists in finding practical solutions that can help them to interpret this distinctive work successfully on the modern piano.
Date: December 2019
Creator: Huang, Szu Ying
System: The UNT Digital Library

William Gillock's Contributions to Piano Pedagogy: A Comparison of Three Works of Gillock with Selected Stylistic Models from the Baroque, Classical, and Romantic Repertoire

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William Gillock, a 20th-century American composer and pedagogue, composed numerous works in the styles of different periods for early intermediate-level piano students. The purpose of this dissertation is to introduce Gillock's pieces to teachers of early intermediate students and illustrate how they can be used as a bridge to the study of similar music from Baroque, Classical, and Romantic periods. Gillock's Little Suite in Baroque Style is compared with Handel's Suite in E Major, HWV 430; his Accent on Analytical Sonatinas (Classical) is compared with Clementi's Piano Sonatinas, Op. 36, No. 3, 5, 6; and his Lyric Preludes in Romantic Style (Romantic) is compared with Chopin's 24 Preludes, Op. 28, No. 3, 6, 9, 16, 18, and 24. Each work is examined to reveal its compositional and technical elements along with pedagogical concepts.
Date: December 2019
Creator: Zhan, Le
System: The UNT Digital Library

Your Blues Ain't Like Mine: Voices from the Other Side of the Color Line

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This dissertation examines intra-racial colorism in works by writers who began their careers during the Harlem Renaissance, but whose writings span almost a century. In these writings, colorism; which can be defined as a bias directed toward an individual that is based on skin tone, is portrayed an intra-racial practice that results from the internalization of racist ideals. The practice relies on a hierarchy that most often privileges those closest to the color line. However, these depictions also show that the preponderance of skin tones can sometimes determine who is targeted. For the purposes of this study it is called reverse colorism when the bias is directed by individuals darker in skin tone toward those who are lighter. Consequently, the careful descriptions of the shades and hues of black characters becomes more than aesthetics and can be seen as a coded reference to experiential differences. While Alain Locke hailed the start of the Harlem Renaissance to signal the rise of The New Negro, the writings featured by female writers in this dissertation advance a less optimistic reality for women, who had to contend with both inter- and intra-racial bias because of their skin tone. Colorism is identified as a particularly …
Date: December 2019
Creator: Edwards, Cheri Paris
System: The UNT Digital Library

Application-Focused Investigation of Monovalent Metal Complexes for Nanoparticle Synthesis

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Over the last 20 years, there has occurred an increase in the number, scope, and impact of nanomaterials projects. By leveraging the Surface Plasmon Resonance of metallic nanoparticles for labelling, sensing, and treatment, researchers have demonstrated the versatile utility of these nanomaterials in medicine. The literature provides evidence of use of simple, well-known chemistry for nanomaterials synthesis when the focus is new applications of nanomaterials. A case in point, is the synthesis of metallic nanoparticles, whereby HAuCl4, CuCl2, Cu(acac)2, and AgNO3 are typically employed as nanoparticle precursors. Unfortunately, the use of these precursors limits the number of applications available to these materials - particularly for AuNPs in medicine, where the byproducts of nanoparticle synthesis (most often surface-adsorbed reductants, toxic stabilizers, and growth directors) cause nanoparticles to fail clinical trials. Despite the several thousand publications detailing the advancements in nanoparticle therapeutics, as of 2017, there were only 50 FDA-approved nanoparticle formulations. Less than 10 were based on metallic nanoparticles. This is a problem because many of these nanoparticle therapeutics demonstrate potent cell killing ability and labeling of cells. A solution to this problem may be the use of weakly coordinated, monovalent metal complexes, which require only one electron to reduce them …
Date: August 2019
Creator: Kamras, Brian Leon
System: The UNT Digital Library

Asian and Asian Indian American Immigrant Students: Factors Influencing Their Academic Performance

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Asian American students have done well in school; they have had higher academic achievements, higher academic scores, lower dropout rates and higher college entrance rates as compared to other minorities and generally other students in the United States (U.S.). A possible explanation to the higher academic performance and achievement of the Asian American students is that they are more likely to have experienced an environment that is conducive to learning at home; their parents were involved and held higher expectations. Immigrant minorities have been found to do well in schools in many parts of the world. Similarly, here in the U.S. there has been increasing evidence that students of Asian ancestry, both immigrants and U.S. born, complete more years of education than most of the other ethnicities. Current research and data on the academic performance of Asian immigrants includes most Asian countries. This study reviewed the current literature regarding the factors that influence the academic performance of "Asian Indian Americans" who attended high schools in the U. S. This correlational study examined the relationship between various factors, such as parental participation, parental expectations and involvement, discipline, cultural beliefs, personal identity and values, language spoken at home, and the academic performance …
Date: August 2019
Creator: Mathew, Subhas
System: The UNT Digital Library

Beyond Nothingness: A Broader Nihilism in Cinema Paradiso by Stephen Goss

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Stephen Goss composed Cinema Paradiso, a six-movement suite for solo guitar, as an homage to films and film directors. Goss cites nihilism as a theme in Dogville, the film that inspires the fourth movement, "Mandalay," but I assert that all the films and many musical devices throughout the piece can be read through the lens of nihilism. The first movement, "Paris, Texas," depicts the stark landscape of the opening scene of the 1984 Wim Wenders film of the same name. "Modern Times" chronicles Charlie Chaplin's slapstick-laden descent from the factory to the insane asylum in the opening sequence of his 1936 Modern Times. "Noir" is a tribute to the procedures of film noir: violent storylines that depict the harshness of life, dim lighting, and anti-hero characters, all accompanied by jazz. Lars von Trier's Dogville provides the movement "Mandalay" with its nihilistic meaning, but Goss writes that he invokes the musical style of Kurt Weill's opera The Rise and Fall of the City of Mahagonny. Just as the book people of François Truffaut's Fahrenheit 451 had to pass on books orally, Goss has burned the score for his "451," forcing guitarists to learn it by watching a video and listening to …
Date: August 2019
Creator: Kyzer, Dan
System: The UNT Digital Library

Bipolar Spectrum Traits in Day-to-Day Life: Ecological Momentary Assessment of Reward Sensitivity, Circadian Timing, and Experience of Reward in the Environment

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The current study examined 236 undergraduate students in a week long twice-per-day ecological momentary assessment exploring the influence of baseline reward sensitivity and interactions between circadian variables (i.e., total sleep time, sleep quality) and daily measures of reward. Though primary study findings did not support reward sensitivity related moderation of sleep-reward pathways, a number of notable findings emerged. We found evidence of specific domains of reward sensitivity (anticipatory reward and reward responsiveness) which are uniquely related to daily experiences of reward. In addition, bidirectional circadian-reward pathways were found between sleep quality and daily rewards which suggests pathways towards reward-related engagement. Evidence also supported interactions between sleep quality and total sleep time on experience of daily reward, further highlighting the complexity of sleep-reward pathways and their relevance to mood symptoms.
Date: August 2019
Creator: Smith, Patrick M.
System: The UNT Digital Library

Carbon Nanotubes and Molybdenum Disulfide Protected Electrodes for High Performance Lithium-Sulfur Battery Applications

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Lithium-sulfur (Li-S) batteries are faced with practical drawbacks of poor cycle life and low charge efficiency which hinder their advancements. Those drawbacks are primarily caused by the intrinsic issues of the cathodes (sulfur) and the anodes (Li metal). In attempt to resolve the issues found on the cathodes, this work discusses the method to prepare a binder-free three-dimensional carbon nanotubes-sulfur (3D CNTs-S) composite cathode by a facile and a scalable approach. Here, the 3D structure of CNTs serves as a conducting network to accommodate high loading amounts of active sulfur material. The efficient electron pathway and the short Li ions (Li+) diffusion length provided by the 3D CNTs offset the insulating properties of sulfur. As a result, high areal and specific capacities of 8.8 mAh cm−2 and 1068 mAh g−1, respectively, with the sulfur loading of 8.33 mg cm−2 are demonstrated; furthermore, the cells operated at a current density of 1.4 mA cm−2 (0.1 C) for up to 150 cycles. To address the issues existing on the anode part of Li-S batteries, this work also covers the novel approach to protect a Li metal anode with a thin layer of two-dimensional molybdenum disulfide (MoS2). With the protective layer of MoS2 …
Date: August 2019
Creator: Cha, Eunho
System: The UNT Digital Library

Ceramide Biosynthesis and NEET Proteins Impact Development, Function, and Maintenance of the Caenorhabditis elegans Germline

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I used the C. elegans genetic model to examine the role of ceramide biosynthesis (sphingolipid pathway) and iron regulation and found that each process impacts germline development and function. Using a sphingolipid specific antibody mAb15B4, I found that sphingolipids are associated with germ granules (P granules) within C. elegans and zebrafish; thus, suggesting conservation of macromolecules associated with germ granules. Phenotype analysis of ceramide biosynthesis mutants in C. elegans revealed that this pathway is essential for normal germline function in the aging adult hermaphrodite; specifically, precocious germline senescence was observed. Furthermore, I found that disruption of ceramide biosynthesis, via the hyl-2 deletion mutation, negatively impacts mAb15B4 localization at the P granules. Through genetic suppression analysis, I determined that insulin signaling and lipid biosynthesis can modulate the mAb15B4 localization to P granules. Additional, phenotype analysis showed that ceramide biosynthesis dysfunction decreased fecundity, and led to germline structure defects and uterine tumors. Through suppression analysis, I determined that modulation of the insulin signaling pathway suppressed the precocious germline senescence due to ceramide biosynthesis dysfunction. Since the presence of uterine tumors is associated with reproductive senescence I concluded that ceramide biosynthesis has a role in germline maintenance in the aging of the germline …
Date: August 2019
Creator: King, Skylar Dawn
System: The UNT Digital Library