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Bipolar Spectrum Traits in Day-to-Day Life: Ecological Momentary Assessment of Reward Sensitivity, Circadian Timing, and Experience of Reward in the Environment
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.
Comparing Cognitive Functioning in White Mexican/Mexican Americans and non-Hispanic White Americans with and without Type 2 Diabetes
To better understand the impact of type 2 diabetes, the relationship between ethnicity, specifically Mexican/Mexican American ethnicity, and the disease must be further investigated. This study specifically examined the cognitive impact of type 2 diabetes. Data from the 2014 Health and Retirement Study was used to compare the cognitive functioning of non-Hispanic White (n = 10,658) and White Mexican/Mexican American (n = 847) individuals, age 50+ years, with and without type 2 diabetes. Serial 7's and immediate and delayed recall—hypothesized to be more negatively affected by type 2 diabetes and Mexican American status—was compared controlling for age, education, and depression. A multivariate analysis of covariance (MANCOVA) indicated significant main effects for race/ethnicity (F(3,11496) = 11.15, p < .001) and diabetes status (F(3,11496) = 3.15, p < .024), with Mexican Americans and those with diabetes having worse cognitive performance. There were significant effects for all covariates. A step-wise multiple regression indicated that education, age, depression, race/ethnicity and diabetes status accounted for a combined 28.4% of variance in a cognitive performance composite. Implications for assessment and treatment are discussed.
Measurement of Positive Continuance Intention Drivers within a Service Domain
The contribution of this dissertation is how model measurement allows examination of the balance between what is practical in terms of consumer concerns versus what is optimal in terms of cost control. Essay 1 examines a research framework that incorporates various service recovery strategies and simultaneously evaluates their comparative influences. Essay 2 evaluates the complex interrelationships among different factors related to the post-complaint behavioral process. Essay 3 fills a research gap by examining the role of brand equity by operationalizing a reflective model using PLS in operations management (OM) research. These three essays provide insight into the quality management domain and the value that is achieved via a data driven examination of theory. Moreover, this research will provide operations management practitioners a basis to carry out future research on quality management phenomena as well as insight into how to balance cost control and service recovery strategies with the goal of achieving a competitive advantage.
Luigi Boccherini's Cello Concerto in B-Flat Major, G.482: Creating a Performance Edition through a Critical Study of the 'Original' Version and Friedrich Grützmacher's Edition
The Cello Concerto in B-flat major, G.482, by Italian composer Luigi Boccherini (1743-1805), is the composer's most beloved work for the instrument, as well as one of the most performed pieces in the Classical concerto repertoire. Historically, cellists performing this work have used an edition prepared by German cellist Friedrich Grützmacher (1832-1903). However, an 'original' version that was discovered in 1949 is significantly different from that of Grützmacher. A comparison of both editions has revealed that Grützmacher in fact made considerable modifications to Boccherini's 'original.' Along with the issue of having two editions, cellists that have played the 'original' edition have noted that there are certain practical and interpretative matters that are not favorable to the cellist, particularly in terms of the way the music is notated and how it lacks many details. This dissertation provides clarity to these issues by undertaking a comprehensive analysis of both editions in order to make cellists become aware of the differences between both editions by comparing musical elements from a performance practice viewpoint. In addition, I discuss relevant issues that are present in the 'original' version, ultimately providing an alternative performance edition to this score that is based on historically informed performance (HIP) practices. Finally, I hope to draw attention on how a performance edition like this can be useful as a rare critical source to one of the major works from the eighteenth-century cello repertoire.
Linking Enhanced Fatigue Life to Design by Modifying the Microstructure
Structural material fatigue is a leading cause of failure and has motivated fatigue-resistant design to eliminate risks to human lives. Intrinsic microstructural features alter fatigue deformation mechanisms so profoundly that, essentially, fatigue properties of structural materials become deviant. With this in mind, we initiated this project to investigate the microstructural effect on fatigue behavior of potential structural high entropy alloys. With a better understanding of the effect of microstructure features on fatigue properties, the ultimate goal was to engineer the microstructure to enhance the fatigue life of structural materials. The effects of two major deformation mechanisms presented here are twinning-induced fatigue crack retardation, and transformation-induced fatigue crack retardation. The fundamental principle of both mechanisms is to delay the fatigue crack propagation rate by altering the work hardening ability locally within the crack plastic zone. In ultrafine grained triplex Al0.3CoCrFeNi, nano-sized deformation twins were observed during cyclic loading in FCC matrix due to low stacking fault energy (SFE). The work-hardening ability of the material near the crack was sustained with the formation of twins according to Considere's criteria. Further, due to the ultrafine-grained (UFG) nature of the material, fatigue runout stress was enhanced. In a coarse-grained, dual-phase high entropy alloy, persistent slip bands formed in FCC matrix during cyclic loading due mainly to the slight composition change that affects the SFE in the FCC matrix and eventually alters the deformation mechanism. Another way known to alter an alloy's work hardening (WH) ability is transformation-induced plasticity (TRIP). In some alloys, phase transformation happens due to strain localization, which alters the work-hardening ability. iii In a fine-grained, dual-phase metastable high entropy alloy, gamma (f.c.c.) to epsilon (h.c.p.) transformation occurred in the plastic zone that was induced from cracks. Thus, we designed a Cu-containing FeMnCoCrSi high entropy alloy that exhibited a normalized fatigue ratio …
The Role of Male Fashion in Protests against the Majority Culture: An Exploratory Study
Throughout history, the Black Diaspora has used fashion as a form of protest. The element of fashion is often overlooked when considering the history and struggle for Black equality, because it is less tangible or definable in terms of its influence and effect, but it is still important because Black males resist the dominant culture via dress by dressing in military uniforms, creating their own style, and using different colors in their dress. Studying the Black struggle in American history during specific periods is one way to better understand opposition to the majority culture through fashion. We should also consider the mood of a social system when examining the dress of a particular group during conflicts. Hence, the purpose of this study is to investigate the role of fashion as a protest tool against the majority culture, and the social mood that affects the fashion choices of Black males. The study focuses on Black fashion from 1910 to 2015. Text data were collected and analyzed from articles published in The Crisis magazine, and men's fashion was specially examined. Additionally, images were studied via visual ethnography and images were coded based on color choice, fit, and accessories. For conducting sentiment analysis, lexicons were used, and the text was examined for negative sentiment. The overall negative sentiment of the document was obtained. Graphical analyses are included to present the findings. The findings, conclusions, limitations, and future research are discussed.
John La Montaine's "Songs of the Rose of Sharon" and "Fragments from the Song of Songs": A Socio-Historical Analysis and Performer's Guide
The purpose of this research is to examine John La Montaine's only two song cycles for soprano and orchestra, Songs of the Rose of Sharon, opus 6 (1947) and Fragments from the Song of Songs, opus 29 (1959). In this investigation-the first ever specific to these works-I examine the works and cultural context in which they were created. I then evaluate the reasonable possibility that La Montaine used his public platform as a composer and performer to subtly celebrate taboo themes of feminism, sexuality, and blackness while shining a light on human injustice. Through close examination of social and historical context, I argue two points. Firstly, Rose of Sharon and Fragments are landmark American works. They are anomalies in classical music history in that a white male heralds texts about a black woman in an unlikely time in American history, thus arguably becoming an unlikely part of the evolution of African-American women in artistic endeavors. Secondly, in the performance guide, I advocate that these works would readily adapt to a staged performance. I discuss how La Montaine's musical settings illustrate the inherent drama of the text, provide a context for interpreting the protagonist in Rose of Sharon and Fragments, and present an interpretation of how these works could be staged. The ultimate goal of this research is to bring these intricately crafted masterpieces to the attention of singers and voice teachers so that they may assume their rightful place in the repertoire.
Faculty Characteristics and Program Budgets: Academic Capitalist Influences on Physical Therapy Graduate Outcomes
This study sought to observe the trends in physical therapy faculty members over time and to understand how those trends correlated with changes in program outcomes. Accreditation data from 231 programs between 2008 and 2017 was used in a panel analysis using fixed effects and random effects models to estimate the effects that faculty characteristics, program characteristics, and program budgets have on graduation rates, first-time licensure examination pass rates, and the percentage of graduates of color that a program produced. Results show that for a 1% increase in faculty time devoted to scholarship, a program could expect graduation rates to rise by 0.17%. For a one percentage point increase in grant-funded faculty, a program could expect a 1.7% increase in graduation rates. Results also indicated a negative linear relationship between the number of publications and graduation rates. First-time licensure exam pass rates had an association with different variables. For a 1% increase in part-time faculty, a program could expect a 6.4% decline in first-time licensure examination pass rates. Similarly, a 1% increase in tenured faculty was associated with a 1.2% decline in first-time licensure examination pass rates. A 1% increase in faculty of color was associated with an increase in graduates of color by 33%. This research study provides data to better inform interested parties on how changes in faculty makeup and program budgets can impact PT graduation rates, licensure pass rates, and the percentage of graduates of color that a program can realistically expect to produce.
A Smart Tale: An Examination of the Smart City Phenomena through the Lens of a Case Study
This dissertation addresses research questions related to defining a smart city and the associated activities. The general research question is explored in the dissertation via the conduct of three related studies. The finding from these three investigations are presented in the results section as 3 essays that collectively examine the smart city phenomena as it has emerged within the City. Essay 1 assesses building municipal open data capability. The study proposed an Opendata Roadmap Framework to enhance the organization's dynamic capability. The results provide a valuable practical framework to help cities develop open data capability. The results also provide a comparative study or benchmark for similar initiatives with other regional cities and within the nation. Essay 2 measures the residents' understanding and beliefs about smart cities. This portion of the research used a qualitative method that included interviewing residents and city officials to understand their definition of a smart city and what they believe makes a city smart. The interviews focused on understanding resident engagement because it is an important characteristic of a smart city. The gap between the city officials and residents understanding was examined. In addition, the interviews help identify essential factors associated with smart cities like trust in government, perceived security, perceived privacy, trust in technology, and perceived monetary value. Essay 3 examines the acceptance of smart city technologies and factors that affect the adoption of such technologies. This essay uses the insights from the other two essays to propose a smart city Unified Theory of Acceptance and Use of Technology (UTAUT) extension labelled Smart City UTAUT (SC-UTAUT). The new proposed model was tested using a survey method. The 1,786 valid responses were used to test the proposed structural equation model using Smart PLS. Results show a significant relationship between trust in technology, trust in government, perceived …
Exploring EHR Adoption and Implementation: The Impact of Resource Advantage Theory on Healthcare Organization's Competitive Position
The hospitals and their healthcare providers need to optimize simultaneously three outcomes: healthcare costs, healthcare options offered to customers, and information utilization efficiency. The adoption of electronic healthcare record (EHR) technologies is a potential managerial mechanism for balancing these outcomes. EHR offers patient management and decision support capabilities that can ameliorate health delivery outcomes for patients, doctors, and hospitals through better-informed business and care decisions. The analysis of data collected in an EHR system may lower costs and improve health care delivery (or both). In sum, it could be argued that EHR is a source of competitive advantage. Despite this prima facie appeal, many hospitals remain reluctant to adopt and implement EHR due to lack of insights into return on investment, unavailability of tested systems and data entry obstacles. To address this gap between the potential of EHR system and lack of its adoption, the purpose of this research is to investigate the role of EHR as a resource of competitive advantage for hospital. Essay 1, titled "Implementation and Adoption of EHR: A Conceptual Model based on Resource Advantage Theory", describes the antecedents and consequences of EHR adoption and implementation. Essay 2, titled "Exploring the Relationship Between Electronic Healthcare Record Adoption and Quality of Care", delves deeper into the operational performance of a hospital. This essay focuses on the impact of EHR on different aspects of patient care and thereby on the financial performance of the hospital. Essay 3, titled "The Effect of Resources on a Hospital's Financial Performance: The Moderating Role of Electronic Health Records Implementation and Adoption", is an empirical inquiry into the key factors that may influence hospitals' financial performance. These include organizational factors (such as, number of nurses and beds) and environmental factors (such as, location and received donations). Further, this essay explores the interaction effects …
The Metabolic Physiology of Planarian Flatworms
Using a high throughput closed respirometry method to measure oxygen consumption, I determined metabolic rates in asexual and sexual Schmidtea mediterranea and Girardia dorotocephala, as a function of temperature, taxon, stressors, reproductive mode, age, regeneration, and specific dynamic action. This study has shown that oxygen consumption can reliably be measured in planaria using optode closed respirometry, and also provided a reliable method for measuring wet mass in planaria, which has been a challenge to researchers in the past. This research revealed that oxygen consumption in S. mediterranea is 1.5-2.1X greater in the sexual strain over the asexual strain at 13-18°C. Within the sexual strain, oxygen consumption is 1.5 -2.2X greater in sexually mature adults over the sexually immature groups (hatchlings, juveniles, and regenerating sexuals). Furthermore, I was able to quantify differences in sexual morphology between these groups exhibiting significant differences in oxygen consumption. The results of this research supports a theory of higher metabolic costs with sexual maturity in S. mediterranea. Therefore, this study has established sexual and asexual S. mediterranea as simple, yet attractive models for investigating energetic costs between sexual and asexual phenotypes. This research also provided quantitative values for specific dynamic action in planaria, with a maximum increase in oxygen consumption of 160% induced by feeding, as well as metabolic relationships in planaria involving temperature, age, and regeneration. These values establish planaria as one of the simplest animal models in which common metabolic patterns, such as SDA and poikilothermic temperature sensitivity, have been demonstrated. Therefore, this research has contributed to the overall knowledge of the basic physiology in this animal, providing the framework for future metabolic studies in planaria involving environmental factors, reproduction, regeneration, development, and aging. Information from this study may supplement interpretation and understanding of modern cellular, molecular, and genomic studies in planaria.
The Geography of Retail Clinics Post Implementation of the Affordable Care Act
Retail clinics are walk-in clinics designed for convenience and for servicing minor health issues and certain acute conditions. The model began as a way of bringing both convenience and care to areas that have lower levels of access to primary care resources. With the implementation of Affordable Care Act (ACA) in March 2010, populations that were previously uninsured were now required to have access to some level of health insurance. These populations presented a potential new market for retail clinics. This research shows that post implementation of the ACA, retail clinics tend to locate in areas with higher incomes and, generally, greater access to primary care.
489 Days
489 Days is an animated documentary about the harrowing experiences of Egyptian-American Mohamed Soltan, who survived 16 months of hunger strike in an Egyptian prison. Caught up in the political turmoil which followed the Arab Spring uprisings, Soltan was unjustly incarcerated between August 2013 and May 2015, when the United States government intervened to release him weeks after an Egyptian court sentenced him to life in prison. The film is also the larger story of an estimated 60,000 political detainees currently held in Egypt without due process, and in violation of local and international human rights conventions.
Prevalence and Proportionality of Dyslexia in Texas Public and Charter School Districts
Passed in 1985, the Texas Education Code (TEC) §38.003, Screening and Treatment of Dyslexia and Related Disorders, required public school districts and charters to identify and provide remediation services for students with dyslexia. While Texas was the first state to pass such a requirement, the question remains: What is the prevalence and proportionality of dyslexia in Texas public school districts and charters? In Phase 1 of this study, a secondary analysis using point prevalence and disproportionality calculations was conducted to analyze the impact of this more than 30-year-old law. In order to better help understand these findings, semi-structured interviews with district leaders were conducted in Phase 2 to gain insight on how students were identified with dyslexia across the state. The results of Phase 1 showed the estimated prevalence of dyslexia in Texas public school districts and charters to be low in comparison to the literature. Additionally, the findings suggested a discrepancy in identifications between gender and district type (public school versus charter) and across racial and ethnic groups. Meanwhile, the results of Phase 2 revealed that leadership, support, funding, and accountability impact dyslexia identifications. This study emphasizes the need to further explore and analyze how to best identify and service all students with dyslexia, regardless of gender, race and ethnicity, district type, and geographical location.
Weapons of Mass Deception: Opacity and the Israeli Nuclear Program
Access to nuclear technology and growing concern over the spread of nuclear weapons triggered an international debate in the 1960s that led to the creation of the Nonproliferation Treaty. Ratified in 1970, NPT was designed to prevent the horizontal spread of nuclear weapons and limit destructive uses of nuclear energy. At the same time, it also normalized the arsenals of existing nuclear states and encouraged exchanges of nuclear information, technology, and materials for peaceful purposes. Nonproliferation policy relies on a theory of the development process that identifies a nuclear frontier to locate evidence of nuclear capabilities. Absent from the proliferation model, however, are cases of covert nuclear weapons programs. For almost 50 years, it has been generally accepted that Israel is a nuclear weapon state, yet Israeli officials have never confirmed nor denied the possession of nuclear weapons. Israel has not signed NPT and has not appeared to conduct a nuclear test, in effect absolving the nuclear program's main reactor from international inspections. Uncertainty surrounding the Israeli program stems from a tradition of deliberate secrecy and deception that constitutes a national policy of opacity. This study argues that opacity has armed Israel with the privilege of nuclear immunity, exempting its secret nuclear activity from the standards and regulations imposed on all other nuclear weapon states. To circumvent the barriers built by opacity, a mixture of declassified material, nuclear history and security literature, and postcolonial studies refines the history of Israel's nuclear program. By examining the American-Israeli nuclear relationship, the sources of opacity, and the framework of nonproliferation that sustains an international nuclear regime, Israel's role in the nuclear world becomes visible.
Universal Suicide Risk Screening in the Parkland Health and Hospital System: Evaluation of the Parkland Algorithm for Suicide Screening
Suicide is a significant public health issue in the US. Despite national and international prioritization since 1996, little definitive progress has been made in terms of identification and intervention in cases of elevated suicide risk. Forty percent of those who died by suicide attended an emergency department within a year of death. Therefore, universal suicide risk screening in emergency departments could prove a vital component to a national suicide prevention strategy. The present study empirically evaluated the universal suicide risk screening program recently implemented at Parkland Health and Hospital System. The sample consisted of patients over 18 years of age (N=333,855; Mage=42.7, 32% male) screened as part of routine clinical care from May 4th, 2015, through November 3rd, 2015. The Parkland Algorithm for Suicide Screening (PASS) is part of a clinical decision support system for responses to Columbia - Suicide Severity Rating Scale Clinical Practice Screener (C-SSRS) items, leading to an automated clinical response via three suicide risk stratification levels: no action for no risk identified, psychiatric social worker assessment for moderate risk identified, and psychiatrist/psychologist interview for high risk identified. The present study used receiver operating characteristic (ROC) curve analysis, which found the PASS predicted disposition (z=30.46, p<.001, AUC=.78, CI95=.77, .81). This study also evaluated the cutpoints separating suicide risk stratification and levels of clinical response. The results supported the first cutpoint and highlighted a need for additional data to address the second cutpoint. The results of the present study suggest that the universal suicide risk screening program at Parkland Health and Hospital System is an important step toward addressing suicide prevalence in the US.
Who Does Online Dating Benefit? Association of Adult Attachment with Relationship and Sexual Satisfaction for Online Daters
Research on associations between online dating and later relationship and sexual satisfaction is limited. The purpose of this study is to examine the association between meeting a romantic partner online or in person and later relationship and sexual satisfaction for heterosexual males and females. Main analysis results suggest that men report higher relationship satisfaction when they met their partner online and women with a preoccupied and dismissing attachment style reported higher sexual satisfaction when they met their partner online. Overall, there were few differences in relationship and sexual satisfaction for heterosexual men and women who met their partner online or in person.
Disasters, Smart Growth and Economic Resilience: An Empirical Analysis of Florida Cities
This dissertation examines the relationship between economic resilience, disaster experience, and smart growth policies at the local government level. The study is based upon three research questions that examine spatial distribution of economic resilience in Florida cities, and examines the impact of disaster experience, and smart growth policies adopted by local governments on economic resilience. Based upon the bounce-forward approach (Cowell, 2013; Klein et al. 2003), economic resilience is defined using three dimensions—economic stability, economic equity, and economic diversity. The spatial analysis is conducted by mapping economic resilience scores across 780 Census Designated Places in Florida through standard deviation method of classification, and conducting cluster-outlier analysis. Results suggest difference in economic resilience within coastal and inland communities—with higher scores mostly situated inland. East Central Florida, Tampa Bay, and South Florida were identified as high economic resilience clusters, and Northwest Florida was identified as low resilience cluster. Impact of disaster experience, and smart growth policies on economic resilience was examined based upon logic of focusing events by Birkland (1997, 2010). Data was collected from the U.S. Census, the National Climatic Data Center, and the Energy Sustainable Florida Communities Survey conducted by Florida State University in 2009. Results suggest significant association between disaster experience of communities and their level of economic resilience, highlighting the importance of community learning in building capacity for resilience after disasters. The results also highlight the need of balancing mitigation and adaptation strategies. Mixed-use development policies, green building certification, and energy savings policies were found to have a significant positive impact on economic resilience.
Beyond Nothingness: A Broader Nihilism in Cinema Paradiso by Stephen Goss
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 a recording. Finally, the chaotic tarantella, "Tarantino" depicts Uma Thurman's heroin overdose scene in Quinten Tarantino's Pulp Fiction. By analyzing Fredrich Nietzsche's writings to form a broader definition of nihilism and applying that definition first to each film and then to corresponding musical elements in each movement, this paper argues that nihilism acts as a connecting theme throughout Cinema Paradiso.
Lookouts
Lookouts follows Matt and Joann, two fire tower lookouts for the United States Forest Service, as they discuss their happiness living in seclusion as well as the decline of fire towers due to technological advances.
Extrinsic Doping of Few Layered Tungsten Disulfide Films by Pulsed Laser Deposition
This dissertation tested the hypothesis that pulsed laser deposition (PLD) could be used to create targeted dopant profiles in few layered WS2 films based on congruent evaporation of the target. At the growth temperatures used, 3D Volmer-Weber growth was observed. Increased energy transfer from the PLD plume to the growing films degraded stoichiometry (desorption of sulfur) and mobility. Sulfur vacancies act as donors and produce intrinsic n-type conductivity. Post deposition annealing significantly improved the crystallinity, which was accompanied by a mobility increase from 6.5 to 19.5 cm2/Vs. Preparation conditions that resulted in excess sulfur, possibly in the form of interstitials, resulted in p-type conductivity. Current-voltage studies indicated that Ohmic contacts were governed by surface properties and tunneling. Extrinsic p-type doping of few layered WS2 films with Nb via pulsed laser deposition using ablation targets fabricated from WS2, S and Nb powders is demonstrated. The undoped controls were n-type, and exhibited a Hall mobility of 0.4 cm2/Vs. Films doped at 0.5 and 1.1 atomic percentages niobium were p-type, and characterized by Fermi levels at 0.31 eV and 0.18 eV from the valence band edge. That is, the Fermi level moved closer to the valence band edge with increased doping. With increased Nb doping, the hole concentrations increased from 3.9 x1012 to 8.6 x1013 cm-2, while the mobility decreased from 7.2 to 2.6 cm2/Vs, presumably due to increased ionized impurity scattering. X-ray photoelectron spectroscopy indicates that Nb substitutes on W lattice sites, and the measured peak shifts toward lower binding energy observed corresponded well with the UPS data. Throughout, a clear correlation between degraded stoichiometry and decreased mobility was observed, which indicates that point defect and ionized impurity scattering is a dominant influence on carrier transport in PLD few-layered WS2 films. The approach demonstrates the potential of PLD for targeted doping of …
Phase Transformation and Elastic Constants in Binary Titanium Alloys: An Atomistic Study
The current understanding of the mechanical properties and deformation behavior of some individual phases in titanium alloys is limited due to the fine scale at which these phases precipitate within the β-phase matrix. The α and ω phases represent the most widely observed phases in titanium alloys depending on the alloy composition and also the heat treatment procedure adopted during processing. The possibility of precipitating ω-phase depends on the content of the β-stabilizers within the system. Although a significant compositional partitioning occurs within ω-phase upon aging treatment, the knowledge of ω-phase mechanical properties as a function of composition is very limited. The initial part of the current work focuses on the effect of common β-stabilizers elements on the phase stability and mechanical properties of the ω-phase using first-principles calculations. A relation between the bonding nature, the phase stability, and elastic properties was proposed. Thereafter αʺ martensitic phase was investigated in Ti-Nb and Ti-Nb-O alloys. The phase stability and martensitic start temperature of αʺ-phase was studied as a function of Nb and oxygen content. Also, the effect of the lattice shear distortion induced by oxygen atom on stabilizing β-phase was investigated. Subsequently the effect of the β-stabilizers' elements on stacking faults energy and ductility in α-Ti alloys was studied. Both prismatic and basal slip system were investigated with different concentration of β-stabilizers at the slip plane. Lastly, while the Tadmor and Bernstein model was employed to predict the partial dislocation emission and twinning propensity, the Rice criterion was used to estimate the effect of different β-stabilizers on the ductility of α-Ti alloys.
Application-Focused Investigation of Monovalent Metal Complexes for Nanoparticle Synthesis
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 to their metallic state. Further, by designing nanoparticle syntheses around these monovalent complexes, we can employ weaker, environmentally friendly stabilizers. This strategy also forgoes the use of exogenous reducing agents, because the monovalent complexes can be reduced and stabilized by one reagent. Herein we investigate the use of Au(Me2S)Cl, [Cu(MeCN)4]BF4, and AgBF4 with green stabilizers to synthesize a variety of nanomaterials. We find that a range of sizes of spherical particles, as well as a range of sizes of gold triangular prisms can be synthesized by using techniques that follow this strategy.
How the Conflict of Autonomous and Controlled Motivation Influences Sales Controls to Inside Sales Agents' Work Outcomes
Through the use of multiple methodologies and analytical approaches, this dissertation combines (1) sales control; (2) call center service; and (3) motivational theory to extend sales control literature beyond its current state, to consider the conflicting motivational perspectives an inside sales agent has to experience. To achieve this unification, this dissertation consists of three essays intended to: (1) identify the influence of autonomous and controlled motivation on operational sales outcome controls and performance; (2) explore the influence these motivators have on sales controls and sales performance; and, (3) understand the impact of autonomous and controlled motivation on sales agent tenure.
Turkish Gazis' (Injured Veterans) Transition into Civilian Life
The aim of this study was to describe the dimensions of Turkish Gazis' transition to civilian life, to explore the main factors that make this process easier or more difficult, and their psychological integration, that is, specifically, satisfaction with their life. To that end, this study examined the impact of combat-related traumatic stressor (e.g., functional limitations), personal resources (social support, sense of mastery), perceived mental health on Turkish veterans' adjustment into civilian life and their psychological integration. The data was collected in Turkey in 2015 by the researcher with the help of Türkiye Harp Malulü Gaziler Şehit Dul ve Yetimler Derneği, a non-profit veteran organization. The final sample included 240 Turkish Gazis. The level of perceived transition into civilian life and veterans' life satisfaction were the dependent variables in this study. A series of ordinary least squares (OLS) regression was conducted. Hayes' PROCESS macro 3.0 was utilized to measure the direct, indirect and moderation effects of variables on transition and life satisfaction among Gazis. The results demonstrated that perceived available social support, perceived sense of mastery and mental health partially mediated the association between Gazis' functional limitations and transition into civilian life and they fully mediated the association between functional limitations and life satisfaction. Among control variables, only household income predicted transition into civilian life, and place of residence was the only significant predictor of life satisfaction. However, neither social support nor mastery had moderation effect on the relationship between functional limitations and dependent variables. Policy implications and suggestions for further studies are also provided at the end of the dissertation.
Method Development for Corrosion Testing of Carbon Steel and Ni-based Alloy Coatings Exposed to Gas Hydrate Formation Environments
Gas hydrate formation and corrosion can cause serious safety and flow assurance problems in subsea environments. One aspect that has been given less attention is the corrosion behavior of materials in gas hydrate formation environment (GHFE). This work introduces a new technique/method for corrosion testing of materials exposed to low temperatures GHFEs. This technique allows pH monitoring, and control of test conditions like temperature. In this work, GHFE is defined as an environment that includes water, methanol and its degraded products in the presence of corrosive agents like CO2 and chloride salt at gas hydrate formation temperatures (GHFT). After 20 hrs immersion in CO2-saturated salinity environment at GHFT, as-deposited Ni-Mo alloy coating has the highest corrosion resistance of 33.28 kΩ cm2. The corrosion resistance dropped to 14.36 kΩ cm2 and 11.11 kΩ cm2 in the sweet low-salinity and sweet high-salinity test solutions respectively. The combined results of SEM/EDX showed that the Ni-Mo coating oxide layer broke down quicker in sweet high-salinity environment than sweet low-salinity environment. When carbon steel was immersed in a CO2-saturated high salinity environment at GHFT, there was slight overall change in corrosion rate (CR) as salt concentration increase from 3 wt% to 25 wt%. In degraded methanol environment, methanol showed an inhibitive effect on the corrosion of carbon steel. Higher methanol content (up to 50 vol. %) increased the corrosion rate of carbon steel at gas hydrate formation temperature, however, the corrosion rates were lower with methanol contents between 10 to 20 vol%.
Electrochemical Deposition of Metal Organic-Modified-Ceramic Nanoparticles to Improve Corrosion and Mechanical Properties
Corrosion is an unstoppable process that occurs spontaneously in many areas of industry, specially, oil and gas industries. Therefore, the need of developing protective coating to lower the cost of corrosion is very consistent. Among different methods, electrodeposition has been a popular method since it offer many advantages such as low cost, ability to control the surface and thickness of the coating, ability to perform at low temperature and pressure, and very convenience. Ceramic nanoparticles have been widely incorporated into metal coating and used as a protective layer to improve both corrosion and hardness properties. Diazonium synthesis was used to modify cerium oxide nanoparticles by grafting with ferrocene for use in nickel nanocomposite coating. Citric acid and citrate salt were used as stabilizing ligands for yttrium oxide and praseodymium oxide nanoparticles in nickel plating solution to prevent the formation of hydroxide, thus, higher amount of nanoparticles was able to incorporate into nanocomposite coatings. These fabricated coatings were evaluate for the corrosion and mechanical properties using many different instruments and electrochemical techniques. As modified cerium oxide, stabilized yttrium oxide or praseodymium oxide added into nickel coatings. The results showed an increase in hardness and corrosion resistance leading to the overall improvement compare to pure nickel coating.
Optimizing Production System Maintenance Policies when Cyber Threats are Considered
In a production environment, physical and cyber-related failures become unavoidable because of the complexity of highly connected manufacturing systems and a finite equipment life cycle. The main purpose of this thesis is to investigate optimal maintenance outsourcing and replacement policies in the presence of cyber-threats, as well as policies to achieve channel coordination via cost subsidization. Although well-developed maintenance outsourcing literature has addressed many advanced and trending issues such as the costs and benefits of new technology adoptions, learning effects, forgetting effects, and systems with back-up machines, no study has looked at the effect of cyber threats on connected production systems. Besides filling this gap, this thesis addresses the most common replacement policies including preventive maintenance with minimal repairs and age replacement. The advent of the Internet of Things (IoT) has enabled the creation of "smart" manufacturing systems, However the resulting connected format makes these systems potential targets for cyber-attacks. Manufacturers have to face a difficult decision as to whether they should adopt costly security technologies or let the manufacturing systems be vulnerable to cyber-threats. This study develops a model addressing this dilemma by providing some insights into the effects of cost subsidization and installation of security systems on the system profit. Our findings suggest that a manufacturer can trade off cost subsidization to gain flexibility in the maintenance decision-making process. The study also provides evidence that, for a "smart" manufacturing system, the existence of a security system guarantees at least a marginal increase in system profit. With the help of an extensive numerical study, we provide guidelines for optimizing system profit and addressing the effect of various model parameters (such as a monetary parameter, failure rate and a cyber-attack related parameter) on the value of a security system.In the second part of this thesis, we build analytical models to …
A Novel Two-Stage Adaptive Method for Estimating Large Covariance and Precision Matrices
Estimating large covariance and precision (inverse covariance) matrices has become increasingly important in high dimensional statistics because of its wide applications. The estimation problem is challenging not only theoretically due to the constraint of its positive definiteness, but also computationally because of the curse of dimensionality. Many types of estimators have been proposed such as thresholding under the sparsity assumption of the target matrix, banding and tapering the sample covariance matrix. However, these estimators are not always guaranteed to be positive-definite, especially, for finite samples, and the sparsity assumption is rather restrictive. We propose a novel two-stage adaptive method based on the Cholesky decomposition of a general covariance matrix. By banding the precision matrix in the first stage and adapting the estimates to the second stage estimation, we develop a computationally efficient and statistically accurate method for estimating high dimensional precision matrices. We demonstrate the finite-sample performance of the proposed method by simulations from autoregressive, moving average, and long-range dependent processes. We illustrate its wide applicability by analyzing financial data such S&P 500 index and IBM stock returns, and electric power consumption of individual households. The theoretical properties of the proposed method are also investigated within a large class of covariance matrices.
A Global Spatial Model for Loop Pattern Fingerprints and Its Spectral Analysis
The use of fingerprints for personal identification has been around for thousands of years (first established in ancient China and India). Fingerprint identification is based on two basic premises that the fingerprint is unique to an individual and the basic characteristics such as ridge pattern do not change over time. Despite extensive research, there are still mathematical challenges in characterization of fingerprints, matching and compression. We develop a new mathematical model in the spatial domain for globally modeling loop pattern fingerprints. Although it is based on the well-known AM-FM (amplitude modulation and frequency modulation) image representation, the model is constructed by a global mathematical function for the continuous phase and it provides a flexible parametric model for loop pattern fingerprints. In sharp contrast to the existing methods, we estimate spatial parameters from the spectral domain by combining the exact values of frequencies with their orientations perpendicular to the fingerprint ridge flow. In addition, to compress fingerprint images and test background Gaussian white noise, we propose a new method based on periodogram spacings. We obtain the joint pdf of these m-dependent random variables at Fourier frequencies and derive the asymptotic distribution of the test statistic.
Understanding the Micromechanism of Cyclic Loading Behavior of Ultrafine Grained Alloys
In the current study, we have investigated the cyclic loading behavior of conventional as well as novel alloy system exhibiting fine and ultrafine-grained structure. While in case of conventional alloy systems (here aluminum alloy AA5024), the effect of three different grain sizes was investigated. Improvement in fatigue properties was observed with decreasing grain size. The unique microstructure produced via Friction stir processing was responsible for the improved fatigue response. Additionally, microstructures consisting of a high fraction of special boundaries within the fine and ultrafine-grained regime were also subjected to cyclic loading. The hierarchical features introduced in the eutectic high entropy alloy deflected the persistent slip bands, responsible for fatigue cracking, thus resulted in delayed crack initiation and improved fatigue life. The selective nature of fatigue was learnt in the fine grain Al0.5CoCrFeNi, where the introduction of hierarchical features did not result in improved fatigue properties. The weak links in the microstructure, while not affecting the tensile properties, got exposed during cyclic loading. Further study on the medium entropy alloy revealed the inherent reason for the improved fatigue properties. The medium entropy alloys utilized the benefit of UFG single-phase FCC matrix. The UFG matrix showed signs of transformation of FCC phase into the HCP phase during fatigue deformation and hence exhibited improved work-hardening. Alongside atomic scale transformation, stacking faults and nano-twins can also be attributed for obtained cyclic properties.
Ceramide Biosynthesis and NEET Proteins Impact Development, Function, and Maintenance of the Caenorhabditis elegans Germline
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 (germline senescence). The other important fate of a germ cell is programmed cell death. Apoptosis, which occurs through a highly conserved molecular pathway, is a normal component of growth and homeostatic processes. I used C. elegans to gain a greater understanding of the cisd gene function. The C. elegans genome has three previously uncharacterized cisd genes which code for CISD-1 (homology to vertebrate mitoNEET/CISD1 and NAF-1/CISD2) and CISD-3.1 and CISD-3.2 (homology to vertebrate Miner2/CISD3). I determined that independent disruption of the cisd genes resulted in a significant increase in the number of cell corpses within the adult hermaphrodite germline. Genetic …
Phase Transformations in Refractory High Entropy Alloys
High entropy alloys (HEAs) based on refractory elements have shown a great potential for high temperature structural applications. In particular, the ones containing Al, exhibits a microstructure similar to the γ-γ' in Ni-based superalloys. While these alloys exhibit impressive strengths at room temperature (RT) and at elevated temperatures, the continuous B2 matrix in these alloys is likely to be responsible for their brittle behavior at RT. Phase stability of five such alloys are studied by thermo-mechanical treatments and characterization techniques using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Two of these alloys showed an inverted microstructure, where the disordered BCC phase becomes continuous, and therefore, they were characterized in detail using SEM, TEM, atom probe tomography (APT) and synchrotron x-ray diffraction experiments. The phenomenon of phase inversion lead to a better combination of strength and ductility as compared to the non-inverted microstructure.To enhance the stability of B2 intermetallic phase which provides the strength when present in a BCC matrix, multicomponent B2 phase compositions stable at 1000°C in some of the above studied alloys, were melted separately. The aim was to establish a single phase B2 at 1000°C and understand the mechanical behavior of these single-phase multicomponent B2 intermetallic alloys. These alloys exhibited a ductile behavior under compression and retained ~1 GPa yield strength at temperature up to 600°C. The ductile nature of these alloys is attributed to the change in bonding nature form directional to metallic bonding, possibly resulting from a significantly high configurational entropy compared to binary or ternary stoichiometric B2 compounds.
Dynamic Deformation and Shear Localization in Friction-Stir Processed Al0.3CoCrFeNi and Fe50Mn30Co10Cr10 High-Entropy Alloys
High entropy alloys (HEAs) are a relatively new class of solid solution alloys that contain multiple principal elements to take advantage of their high configurational entropy, sluggish diffusion, lattice distortion, and the cocktail effect. In recent development, work hardening mechanisms known as twinning induced plasticity (TWIP) and transformation induced plasticity (TRIP) have been found active in Al0.3CoCrFeNi (molar fraction) and Fe50Mn30Co10Cr10 (at %) HEA compositions. Friction-stir processing was done to increase the mechanical properties and improve the microstructure of the alloys for the purpose of high strain rate performance. Quasi-static tensile tests as well as top-hat geometry Split-Hopkinson pressure bar tests were conducted to view the mechanical properties as well as view the microstructural evolution at dynamic strain rates. Overall, the Al0.3CoCrFeNi condition after friction-stir processing and heat treatment has proved to have the best mechanical properties, and selecting from the conditions in this study, Al0.3CoCrFeNi has better shear localization resistance.
Psychological Well-Being and Family Functioning in Middle Childhood: The Unique Role of Sibling Relational Dynamics
The current study examined associations between perceived family functioning, sibling relational dynamics, and individual's self-reported personal adjustment and internalizing problems among 8- to 11-year old children. Path analyses revealed significant direct effects between conflictual family functioning and children's psychological well-being (p < 0.05). Further, sibling conflict was found to indirectly affect these associations. Finally, significant interactions between family functioning and sibling dynamics were found suggesting that congruent relational dynamics at multiple levels of the family system had a cumulative impact on the child's well-being. Findings from the current study highlight the unique contributions of sibling relationships to the family and the child providing evidence for targeting the sibling relationship in clinical interventions and future family research.
Military and Veteran Mental Health Stigma and Help-Seeking Behaviors: Role of Leadership and Attachment
Mental health stigma has been identified as a barrier to help-seeking in the United States. Research suggests that insecure attachment may contribute to higher mental health stigma and lower help-seeking behavior. This may be particularly salient in military personnel who tend to report higher mental health stigma than the general population. Evidence suggests that both supportive and destructive military leadership are related to service members' attitudes toward seeking help. In the current study, a sample of military service members and veterans (N = 232) completed an online survey regarding mental health stigma, military leadership experiences, attachment strategies, and mental health help-seeking behaviors. Findings indicated that destructive and supportive leadership experiences were significantly related to self and public stigma, and self-stigma mediated the relationship between destructive and supportive leadership experiences and likelihood to seek help. Attachment anxiety predicted higher self and public stigma, while attachment avoidance predicted high self-stigma but low public stigma, with high self-stigma partially mediating the relationship between attachment avoidance and help seeking.
The Effects of the IAM Workshop on Preservice Teachers' Perceptions and Attitudes on Integrating Art and Mathematics In Saudi Arabia
This mixed-methods dissertation used an explanatory sequential design to examine art and mathematics preservice teachers' perceptions and attitudes towards integrating art and mathematics (IAM) after an IAM workshop. The conceptual framework of this study has its basis in three theoretical sources: constructivism, multiple intelligence theory, and semiotics. Each of these sources provides a conceptual lens to examine art integration in the curriculum and the teacher's role in facilitating this instructional process. Participants of this study included two sub-groups at a large university in Saudi Arabia. The first sub-group was preservice teachers of art education. The second sub-group was preservice teachers of mathematics. Quantitative and qualitative results indicated that the IAM workshop had positive impacts on art and mathematics preservice teachers' attitudes and perceptions of IAM. Participants attributed more value to art, were more willing to apply IAM, and felt that there was less barriers for applying IAM. The study also indicated differences between art and mathematics preservice teachers' attitudes towards IAM. The differences were due more to art value than willingness or barriers. After the IAM workshop, mathematics preservice teachers put more emphasis on the importance of art to mathematics, especially with respect to making mathematics a more enjoyable subject.
Improving Actigraphy Specificity to Better Inform Insomnia Diagnosis and Treatment Decisions
Accurate assessment of sleep-wake patterns is important for sleep researchers and clinicians. Actigraphs are low-cost, non-intrusive, wrist-worn activity detectors used to estimate sleep-wake patterns in a natural environment for several nights. Although actigraphy shows good sensitivity (sleep detection), it has consistently demonstrated poor specificity (wakefulness detection while lying in bed relatively motionless). Because insomnia is characterized by wakefulness in bed, actigraphy may not be a valid objective measure of wakefulness for this group. It is possible that refinement of actigraphy software settings for sleep/wake algorithms might improve specificity. The current studies investigated this hypothesis by comparing wake parameters from 48 combinations of actigraphy settings to determine which sleep/wake algorithms best inform insomnia diagnosis and treatment. In the first study, none of the 48 actigraphy setting combinations consistently discriminated between adults with insomnia (n = 69) and non-insomnia (n = 80) on all three wake parameters, and no setting clearly discriminated between groups for the composite variable, total wake time. Similarly, in the second study, no setting combinations consistently discriminated between adults treated for insomnia (n = 18) and controls with untreated insomnia (n = 26) on all three wake parameters. Although two setting combinations discriminated between groups for the composite variable, total wake time, the values were extreme which raises validity concerns. Therefore, no actigraphy setting recommendations can be made based on the current findings. This research offers insights about the effects of actigraphy software settings on actigraphy specificity as it pertains to the diagnosis and treatment of insomnia.
Carbon Nanotubes and Molybdenum Disulfide Protected Electrodes for High Performance Lithium-Sulfur Battery Applications
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 preventing the growth of Li dendrites, stable Li electrodeposition is realized at the current density of 10 mA cm−2; also, the MoS2 protected anode demonstrates over 300% longer cycle life than the unprotected counterpart. Moreover, the MoS2 layer prevents polysulfides from corroding the anode while facilitating a reversible utilization of active materials without decomposing the electrolyte. Therefore, the MoS2 protected anode enables a stable cycle life of over 500 cycles at 0.5 C with the high sulfur loading amount of ~7 mg cm−2 (~67 wt% S content in cathode) under the low electrolyte/sulfur (E/S) ratio of 6 μL mg−1. This …
Substrate Nanotopography and Stiffness Modulation of Cell Behavior
The physical characteristics (i.e., nanostructure and stiffness) of the extracellular matrix where cells reside have been shown to profoundly affect numerous cellular events in vivo and also been employed to modulate cell behavior in vitro, yet how these physical cues regulate cell behavior is still elusive. Therefore, we engineered a variety of nanotopographies with different shapes and dimensions, and investigated how the nanotopographical cue, through focal adhesions-cytoskeleton-nucleus pathway, affected cell phenotype and function. We further designed and fabricated well-defined substrates which had either identical biochemical cue (adhesive ligand presentation) but different nanotopographical cues or identical nanotopography but different biochemical cues, and dissected the roles of these cues in cell modulation. In addition, we revealed that the human mesenchymal stem cells (hMSCs) could obtain nanotopographical memory from the past culture environment, and the nanotopographical memory influenced the future fate decision of the hMSCs. Moreover, we evaluated the effects of substrate nanotopographical and stiffness cues on the fibrogenesis of human lung fibroblasts in response to carbon nanotubes and highlighted the significance of these physical cues in the development of physiologically relevant in vitro models for nanotoxicological study. The mechanistic understanding of the physical regulation of cell behaviors will provide important insight into the advancement of cell culture technologies and the recreation of biomimetic in vitro tissue/organ models.
The Last Karankawas: Stories
A collection of interconnected short stories set in diverse corners of Texas, converging on Galveston Island before and after Hurricane Ike.
Preparing and Using Hydrophobic Fluorinated Polymers for Corrosion Protection on Aluminum Substrate
Corrosion is one of the most expensive failures in industries that used metal components and other construction materials. In fact, corrosion is responsible for hundreds of billions-dollar loss in the US alone each year. In general, corrosion occurs when metal surfaces are exposed to water, oxygen, acids, bases, or salts. Therefore, metal substrates must be protected by using materials that act as barriers to avoid destructive corrosion attack. Aluminum is one of the most common metals used in the industry; and it is used in many places such as refining and petroleum production equipment, pipelines, and fossil fuel power plants. Aluminum is known to have corrosion resistance due to the forming of an oxide layer that can be reformed rapidly if the surface gets damaged. However, in the long-term the oxide layer cannot protect the aluminum surface from corrosion because it is stable only in neutral mediums and it is soluble in acidic and basic environments. Barrier protection is one of the most effective methods that prevent aluminum surfaces from being exposed to corrosive environments. These barriers can be organic or inorganic coatings that can limit the electron transport or the cathodic and the anodic reactions between aluminum alloys and the surrounding environment. Fluorinated polymers that were used in this study exhibit excellent properties which make them good candidates for corrosion protection applications. These properties include high hydrophobicity which is responsible for repelling oxygen and water and reducing the wettability of the metal surface, strong adhesion to the metal surface allowed for covering and protection of substrates in aggressive environments, and thermal stability that allows for using these polymers in high temperature environments. Overall, the corrosion protection, which was evaluated using electrochemical techniques, and the mechanical properties were improved with these fluorinated polymeric coatings in comparison to the bare aluminum …
Computational Studies of Catalysis Mediated by Transition Metal Complexes
Computational methods were employed to investigate catalytic processes. First, DFT calculations predicted the important geometry metrics of a copper–nitrene complex. MCSCF calculations supported the open-shell singlet state as the ground state of a monomeric copper nitrene, which was consistent with the diamagnetic character deduced from experimental observations. The calculations predicted an elusive terminal copper nitrene intermediate. Second, DFT methods were carried out to investigate the mechanism of C–F bond activation by a low-coordinate cobalt(I) complex. The computational models suggested that oxidative addition, which is very rare for 3d metals, was preferred. A π–adduct of PhF was predicted to be a plausible intermediate via calculations. Third, DFT calculations were performed to study ancillary ligand effects on C(sp3)–N bond forming reductive elimination from alkylpalladium(II) amido complexes with different phosphine supporting ligands. The dimerization study of alkylpalladium(II) amido complexes indicated an unique arrangement of dative and covalent Pd-N bonds within the core four-membered ring of bimetallic complexes. In conclusion, computational methods enrich the arsenal of methods available to study catalytic processes in conjunction with experiments.
Who is Who in Zimbabwe's Armed Revolution? Representation of the ZAPU/ZIPRA and the ZANU/ZANLA in High School History Textbooks Narratives of the Liberation War
The liberation war was a watershed event in the history of Zimbabwe. According to the ZANU PF (Zimbabwe African National Union Patriotic Front) ruling elites, an understanding of the common experiences of the people during the liberation war provides the best opportunity to mold a common national identity and consciousness. However, the representation of important historical events in a nation's history is problematic. At best events are manipulated for political purposes by the ruling elites, and at the worst they are distorted or exaggerated. In Zimbabwe, the representation of the ZAPU/ZIPRA and the ZANU/ZANLA as liberation movements in high school history textbooks during the armed struggle is a hot potato. This study critically examined and explored the contested "representational practices" of the ZAPU/ZIPRA and the ZANU/ZANLA as liberation movements during the Zimbabwean armed revolution. By means of qualitative content analysis, seven high school history textbooks from Zimbabwe were analyzed. Drawing from postcolonial perspectives and insights, particularly Fanon's concept of the pitfall of national consciousness, the study unveiled the way in which Zimbabwean high school textbooks portrayed the ZAPU/ZIPRA and the ZANU/ZANLA as very different liberation movements whose roles and contributions were unequal. High school textbooks depicted the ZANU/ZANLA as a radical revolutionary and people-oriented liberation movement totally committed to the armed struggle and the ZAPU/ZIPRA as a moderate party not dedicated to the armed revolution. In a nutshell, the high school history textbooks glorified and celebrated the political and military achievements of the ZANU/ZANLA and suppressed while not completely ignoring those of the ZAPU/ZIPRA. Although the findings of this study will not solve the problem of high school textbooks (mis) representation of the roles and contributions of the ZAPU/ZIPRA and the ZANU/ZANLA in the armed struggle, the study can serve as a "tool of resistance" by exposing the continual abuse …
A Further Evaluation of Individual and Synthesized Contingencies within Functional Analysis Methods
A functional analysis (FA) is the most commonly used assessment methodology for identifying maintaining variables influencing problem behavior. However, if an FA does not produce clear differentiation, researchers and practitioners often then modify procedures to include additional individualized variables. The interview-informed synthesized contingency analysis (IISCA) provides a marked departure from FA methodology and aims to include individualized factors at the initiation of the assessment in order to more rapidly produce differentiation and clear results. We sought to further evaluate and compare the outcomes of two different functional analysis methods: the single-contingency functional analysis (FA) and the interview-informed synthesized contingency analysis (IISCA) to determine the function of problem behavior and evaluate the subsequent function-based treatment determined from the functional analysis results with two children diagnosed with autism spectrum disorder (ASD). Both participants engaged in problem behavior maintained by single-contingencies of reinforcement identified within the single-contingency FA and emphasized by the effectiveness of each single-contingency function-based treatment.
Praseodymium Oxide and Organic Modified Cerium Oxide Nanoparticles for Electrodeposition of Nickel-Ceramic Nanocomposites to Enhance Corrosion Protection and Mechanical Properties
There is a consistent need in many industries, especially oil and gas, to develop coatings which have higher corrosion resistance and better hardness to extend the lifetime of equipment when it is exposed to hostile environments. Electrodeposition has been a favorable method in the synthesis of metal coatings because of its low cost, convenience, ability to work at low temperatures, and ability to control surface morphology and structure. The inclusion of ceramic nanoparticles in metal matrix composites has previously been investigated as a technique to not only increase the corrosion resistance of the native metal but also to improve the hardness and mechanical properties. Cerium oxide nanoparticles were modified through the grafting of organic groups with increasing hydrophobicity for use in nickel coatings on stainless steel to further improve the corrosion properties while maintaining the hardness of the nanocomposite coatings. The process of modifying the cerium oxide nanoparticles involved the use of aryl diazonium salts and resulted in multilayers forming on the surface of the nanoparticles. Praseodymium oxide nanoparticles were also investigated as additives to nickel coatings, since praseodymium oxide has not yet been studied as a possible corrosion protection enhancement in coatings. These coatings were evaluated for composition and corrosion using many different types of instrumental and electrochemical techniques. With the addition of both the modified cerium oxide nanoparticles and the praseodymium oxide nanoparticles into nickel coatings, an increase in coating hardness and corrosion resistance was observed over pure nickel, resulting in an improvement of the lifetime of these coatings.
Information Sharing and Storage Behavior via Cloud Computing: Security and Privacy in Research and Practice and Users' Trust
This research contributes to the cloud computing (CC) literature and information science research by addressing the reality of information sharing and storage behavior (ISSB) of the users' personal information via CC. Gathering information about usage also allows this research to address the paradox between the research and practice. Additionally, this research explores the concept of trust and its role in the behavioral change relative to CC. The findings help reconcile the paradox between the two realms. Essay1 develops and tests cloud computing usage model (CCUM) that assesses ISSB. This model considers the main adoption determinants and the main drawbacks of CC. The study measures the main concerns of users found in the literature, perceived security and perceived privacy. The findings prove surprising on these concerns. Using multiple regression to analyze 129 valid survey responses, the results find that CC users are less concerned about the major issues of security and privacy and will use the technology based on peer usage. Essay 2 examines why users ignore the technology issues and elect to replace the traditional mechanisms for handling their personal information. The results of an interview-based study conducted on 11 normal users and 11 IT professionals clarify their perceptions about CC and examine its readiness to handle their information from an end-user perspective. Essay 3 explores the CC literature to identify the major factors associated with the users' trust beliefs. The research conducted in this essay groups these factors into three categories. The posited and tested model examines the effect of perceived trust on ISSB. A structural equation modeling approach is used to analyze 1228 valid responses and tests the developed cloud computing trust model. The results provide multiple implications for CC researchers, managers, and service providers.
Modeling Marijuana Use Willingness and Problems as a Function of Social Rejection and Social Anxiety
Marijuana is the second most commonly used substance in the US. A growing literature suggests that socially anxious individuals use marijuana to manage their symptoms in social situations, which may explain why they are also more likely to experience problems. Unfortunately, the majority of the literature is based on research conducted with adult samples or the co-occurrence of diagnoses in adolescent samples. The proposed study sought to test the link between social anxiety (SA) and proxies for ‘real-time' marijuana use behaviors (i.e., use willingness) as well as use-related problems among adolescents. Participants were 69 adolescents (15-17; 55% female) recruited from the community reporting any lifetime marijuana use. Participants were randomly assigned to a novel social rejection or neutral laboratory task and completed measures of SA, marijuana use frequency, and related problems. Consistent with adult findings, main effects of SA and experimental condition on marijuana use willingness were expected to be qualified by an interaction in which the greatest marijuana use willingness would occur among high SA youth post-rejection (H1), SA would be positively related to marijuana use problems (H2), and among adolescents in the rejection condition, marijuana use willingness would be positively correlated with use problems (H3). Only H2 was supported, highlighting areas of convergence and divergence in the role of SA and social stress on marijuana outcomes. These data stand to improve the scientific knowledge on the relative roles of SA and social stress on marijuana use within an understudied, high-risk population and help inform future intervention efforts.
Bio-Inspired Material Surfaces with Self-cleaning, Micromanipulation and Water Collection
Geckos are famous for the skill of switchable adhesion that they use to stick on various surface while keep their fingers super clean. In the dissertation, a unique mechanism was discovered to explain gecko self-cleaning phenomena. Using atomic force microscopy (AFM), we managed to compare the microparticle-substrate adhesion and the microparticle-seta adhesion with a single seta bonded to the AFM cantilever. A dynamic effect was approved that high pulling-off speed could increase the microparticle-substrate adhesion and thus the self-cleaning appears at high moving speed. Based on the self-cleaning theory, a gecko-inspired N-doped graphene surface with switchable adhesion was achieved, which was designed into a bio-inspired micromanipulator with a success rate over 90%. When electrical bias was applied on this biomimetic surface, the charge concentration induced an electrical double layer (ELD) on the convex surfaces, which attracts polar water molecules to form a water bridge on it, significantly enhancing the adhesion on the wrinkled graphene surface, mimicking the capillary force on beetle feet. Therefore, the bio-inspired adhesive surface can be controlled with speed, electrical bias, humidity and different material surfaces. The water attraction phenomenon on the polarized surface was further tested for the potential application of water collection and evaporation in microsystems.
A Pedagogical Guide to the Piccolo Trumpet
The modern piccolo trumpet is required by professional trumpet players for the performance of solo repertoire, chamber music, orchestra, and wind band. Students in universities around the world study the piccolo trumpet in preparation for professional careers, but relatively few pedagogical tools exist to specifically focus on the nuanced techniques of the instrument such as articulation, range, and sound production. The purpose of this project is to create a pedagogical guide that can serve as a method for students learning the modern piccolo trumpet.
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