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  Partner: UNT Libraries
 Degree Level: Doctoral
 Collection: UNT Theses and Dissertations
Synthesis Strategies and a Study of Properties of Narrow and Wide Band Gap Nanowires

Synthesis Strategies and a Study of Properties of Narrow and Wide Band Gap Nanowires

Date: May 2014
Creator: Sapkota, Gopal
Description: Various techniques to synthesize nanowires and nanotubes as a function of growth temperature and time were investigated. These include growth of nanowires by a chemical vapor deposition (CVD) system using vapor-liquid-solid (VLS) growth mechanism and electro-chemical synthesis of nanowires and nanotubes. Narrow band gap InSb Eg = 0.17 eV at room temp) nanowires were successively synthesized. Using a phase diagram, the transition of the nanowire from metallic- semiconducting- semi-metallic phase was investigated. A thermodynamic model is developed to show that the occurrence of native defects in InSb nanowires influenced by the nanowire growth kinetics and thermodynamics of defect formation. Wide band gap ZnO (Eg = 3.34 eV) and In2O3 (3.7 eV) were also synthesized. ZnO nanowires and nanotubes were successfully doped with a transition metal Fe, making it a Dilute Magnetic Semiconductor of great technological relevance. Structural and electronic characterizations of nanowires were studied for different semiconducting, metallic and semi-metallic nanowires. Electron transport measurements were used to estimate intrinsic material parameters like carrier concentration and mobility. An efficient gas sensing device using a single In2O3 nanowire was studied and which showed sensitivity to reducing gas like NH3 and oxidizing gas like O2 gas at room temperature. The efficiency of the ...
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Autonomic Failure Identification and Diagnosis for Building Dependable Cloud Computing Systems

Autonomic Failure Identification and Diagnosis for Building Dependable Cloud Computing Systems

Date: May 2014
Creator: Guan, Qiang
Description: The increasingly popular cloud-computing paradigm provides on-demand access to computing and storage with the appearance of unlimited resources. Users are given access to a variety of data and software utilities to manage their work. Users rent virtual resources and pay for only what they use. In spite of the many benefits that cloud computing promises, the lack of dependability in shared virtualized infrastructures is a major obstacle for its wider adoption, especially for mission-critical applications. Virtualization and multi-tenancy increase system complexity and dynamicity. They introduce new sources of failure degrading the dependability of cloud computing systems. To assure cloud dependability, in my dissertation research, I develop autonomic failure identification and diagnosis techniques that are crucial for understanding emergent, cloud-wide phenomena and self-managing resource burdens for cloud availability and productivity enhancement. We study the runtime cloud performance data collected from a cloud test-bed and by using traces from production cloud systems. We define cloud signatures including those metrics that are most relevant to failure instances. We exploit profiled cloud performance data in both time and frequency domain to identify anomalous cloud behaviors and leverage cloud metric subspace analysis to automate the diagnosis of observed failures. We implement a prototype of the ...
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Fundamental Studies of Copper Bimetallic Corrosion in Ultra Large Scale Interconnect Fabrication Process

Fundamental Studies of Copper Bimetallic Corrosion in Ultra Large Scale Interconnect Fabrication Process

Date: May 2014
Creator: Koskey, Simon Kibet
Description: In this work, copper bimetallic corrosion and inhibition in ultra large scale interconnect fabrication process is explored. Corrosion behavior of physical vapor deposited (PVD) copper on ruthenium on acidic and alkaline solutions was investigated with and without organic inhibitors. Bimetallic corrosion screening experiments were carried out to determine the corrosion rate. Potentiodynamic polarization experiments yielded information on the galvanic couples and also corrosion rates. XPS and FTIR surface analysis gave important information pertaining inhibition mechanism of organic inhibitors. Interestingly copper in contact with ruthenium in cleaning solution led to increased corrosion rate compared to copper in contact with tantalum. On the other hand when cobalt was in contact with copper, cobalt corroded and copper did not. We ascribe this phenomenon to the difference in the standard reduction potentials of the two metals in contact and in such a case a less noble metal will be corroded. The effects of plasma etch gases such as CF4, CF4+O2, C4F8, CH2F2 and SF6 on copper bimetallic corrosion was investigated too in alkaline solution. It was revealed that the type of etching gas plasma chemistry used in Cu interconnect manufacturing process creates copper surface modification which affects corrosion behavior in alkaline solution. The learning ...
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Études: Five Compositional and Technical Studies for Solo Organ

Études: Five Compositional and Technical Studies for Solo Organ

Date: May 2014
Creator: Lloyd, S. Andrew
Description: Études was composed as a set of five interrelated movements in the followingorder: Prelude, Introduction and Fugue, Triptych, Chorale, and Response. The pieces are compositional as well as technical studies. The movements specifically explore certain styles and forms unique to organ music, and reintroduce these elements in creative ways. As in the traditional étude, each movement contains virtuosic technical studies, which are designed to enhance manual and pedal facility and prepare the performer for advanced repertoire.
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Spatial Ability in Registered Nurses

Spatial Ability in Registered Nurses

Date: May 2014
Creator: Gardner, Janet E.
Description: Spatial ability is the skill associated with mental relations among objects, the process of maintaining the physical aspects of an object after mentally rotating it in space. Many studies report a strong association of spatial ability with success in various areas of health care, especially surgery, radiology and dentistry. To date, similar investigations in professional nursing could not be located. Registered nurses, employed in an acute care multi-hospital setting, were surveyed using the Shipley-2Block Pattern Test, the Group Embedded Figures Test, and a newly created test of general nursing knowledge. The sample size of 123 nurses was composed of 31 male nurses and 92 female nurses. Data was collected between May and August of 2013 and analyzed using R, version 2.15.2. The present study did not demonstrate a statistically significant effect for gender differences on two measures of spatial ability. However, Cohen’s d effect sizes for mean gender differences in the present study are consistent with prior studies. This may suggest the nursing profession is comparable with other professions where males perform higher than females on spatial ability. The present study should be considered an initial step toward evaluating the relevance of spatial ability in the performance of nursing care.
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A Pedagogical and Methodical Approach to Unaccompanied Euphonium Literature Through Performance and Analyses of Original Works by Torstein Aagaard-nilsen

A Pedagogical and Methodical Approach to Unaccompanied Euphonium Literature Through Performance and Analyses of Original Works by Torstein Aagaard-nilsen

Date: August 2013
Creator: Nyren, Patrick J.
Description: Original unaccompanied literature currently stands as one of the most understudied bodies of music in the euphonium repertory. This is largely due to a lack of access to reference recordings, live performances, and study/performance guides. Many of the commissioning projects for new euphonium music in the late 20th and early 21st centuries have promoted the composition of large scale works for euphonium and large ensembles, but very few have generated new unaccompanied pieces for euphonium. Many of the most recent commissions for unaccompanied euphonium music have been for competitions such as the Lieksa Brass Festival (Finland) and Leonard Falcone International Festival (USA). These competitions are also where many students get their only exposure to the unaccompanied repertoire. Unfortunately, there is a small number of standard unaccompanied works that are continuously recycled for these competitions and the exposure to new pieces in the repertoire is further diminished for many developing euphoniumists. This study will examine the three works for unaccompanied euphonium by Torstein Aagaard-Nilsen and provide solutions for many common technical challenges and pose suggestions for approaching and preparing this genre of music. Connections are made throughout the study to specific etudes and other unaccompanied solos that can be used as ...
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A Study of Silver: an Alternative Maldi Matrix for Low Weight Compounds and Mass Spectrometry Imaging

A Study of Silver: an Alternative Maldi Matrix for Low Weight Compounds and Mass Spectrometry Imaging

Date: May 2014
Creator: Walton, Barbara Lynn
Description: Soft-landing ion mobility has applicability in a variety of areas. The ability to produce material and collect a sufficient amount for further analysis and applications is the key goal of this technique. Soft-landing ion mobility has provided a way to deposit material in a controllable fashion, and can be tailored to specific applications. Changing the conditions at which soft-landing ion mobility occurs effects the characteristics of the resulting particles (size, distribution/coverage on the surface). Longer deposition times generated more material on the surface; however, higher pressures increased material loss due to diffusion. Larger particles were landed when using higher pressures, and increased laser energy at ablation. The utilization of this technique for the deposition of silver clusters has provided a solvent free matrix application technique for MALDI-MS. The low kinetic energy of incident ions along with the solvent free nature of soft-landing ion mobility lead to a technique capable of imaging sensitive samples and low mass analysis. The lack of significant interference as seen by traditional organic matrices is avoided with the use of metallic particles, providing a major enhancement in the ability to analyze low mass compounds by MALDI.
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Does Underwriter Size Matter?  Only Within the Right Context

Does Underwriter Size Matter? Only Within the Right Context

Date: May 2014
Creator: Kendall, Lynn K.
Description: The initial matching relationships between underwriters and bonds/issuing firms and the certification quality of underwriters, as determined by changes in the issuing firm’s financial strength post issue, are the two primary research topics in this dissertation. Based on total underwriter syndicate market share, two distinct categories, low market power (LMP) syndicates and high market power (HMP) syndicates were defined. Firm financial strength is examined based on a new factor developed in this research. A comparison of the two underwriting categories, or pools, indicates that the HMP underwriters take on firms of lower initial financial strength and additionally, the issuing firms decline more in financial strength two years following bond issuance than do firms using LMP underwriters. Notwithstanding these results, the more interesting findings are the relationships within each of these pools. In the LMP pool of underwriters, financially stronger firms used the larger LMPs to underwrite their bonds, while the weaker firms used smaller LMPs. In contrast, among HMP underwriters, the largest HMPs aligned with the firms of relatively lower financial strength. The relationships in both pools reverse when changes in financial strength are examined. Larger LMPs are associated with greater issuing firm financial decline while larger HMPs correlate with ...
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Harold Shapero’s Sonata for C Trumpet and Piano: the Influence of Idiomatic Jazz Elements on a Prominent Mid-20th Century Neo-classical Composer

Harold Shapero’s Sonata for C Trumpet and Piano: the Influence of Idiomatic Jazz Elements on a Prominent Mid-20th Century Neo-classical Composer

Date: August 2013
Creator: Whalen, Kevin Patrick
Description: Harold Shapero’s Sonata for Trumpet in C and Piano is a significant work that it is rarely performed and studied. Shapero’s composition contains musical attributes that demand artistically accurate choices if the style of this jazz-influenced sonata is to be achieved. Written in 1940 in dedication to Aaron Copland, the Sonata for C Trumpet and Piano makes use of a variety of stylistic influences, blending those of early 20th century jazz with Stravinsky-influenced neo-classicism. The intent of this study is to examine the unique performance practice implications and musical considerations of Harold Shapero’s Sonata for C Trumpet and Piano in correlation to the composer’s implementation of jazz idiomatic elements within the constructs of neo-classicism. The first section of this study examines the historical context necessary for understanding the social and musical conditions of the early to mid 1940s. The second section addresses the musical elements that characterize this work; the primary focus of this section is an exploration of Harold Shapero’s implementation of jazz idioms into his first composition for trumpet. The final section of the study interprets the utilization of idiomatic jazz elements within the work so as to allow the trumpet player with little jazz experience to accurately ...
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Utilizing North American Art Song Settings of Psalm Texts in Worship Services: an Annotated Guide for Singers, Voice Instructors, and Music Ministers

Utilizing North American Art Song Settings of Psalm Texts in Worship Services: an Annotated Guide for Singers, Voice Instructors, and Music Ministers

Date: May 2014
Creator: Siddons, Kyle
Description: This dissertation provides a guide for appropriate use of North American art song settings of biblical psalms for solo voice written after 1950 in the worship services of Christian faiths. The songs analyzed are for all voice parts and a variety of accompanying ensembles. The placement of each song on a specific calendar day is guided by the individual church calendars and lectionaries, on the prevalent themes of the text, and the characteristics of the musical setting. Performance of these songs only in a concert setting limits their usefulness for singers, voice teachers, and music directors alike. A new and worthy performing context can be established by analyzing the text and musical settings.
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