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- Genre: Doctoral Dissertation
- Genre: Music--Instruction and study--Korea.
- Genre: Music--Latin America--History and criticism.
- Creators: Arizona State University
Description
Failures in the cold chain, the system of refrigerated storage and transport that provides fresh produce or other essentials to be maintained at desired temperatures and environmental conditions, lead to food and energy waste. The mini container (MC) concept is introduced as an alternative to conventional refrigerated trucks (“reefers”), particularly for small growers. The energy consumption and corresponding GHG emissions for transporting tomatoes in two cities representing contrasting climates is analyzed for conventional reefers and the proposed mini containers. The results show that, for partial reefer loads, using the MCs reduces energy consumption and GHG emissions. The transient behavior of the vapor compression refrigeration cycle is analyzed by considering each component as a “lumped” system, and the resulting sub-models are solved using the Runge Kutta 4th-order method in a MATLAB code at hot and cold ambient temperatures. The time needed to reach steady state temperatures and the temperature values are determined. The maximum required compressor work in the transient phase and at steady state are computed, and as expected, as the ambient temperature increases, both values increase. Finally, the average coefficient of performance (COP) is determined for varying heat transfer coefficient values for the condenser and for the evaporator. The results show that the average COP increases as heat transfer coefficient values for the condenser and the evaporator increase. Starting the system from rest has an adverse effect on the COP due to the higher compressor load needed to change the temperature of the condenser and the evaporator. Finally, the impact on COP is analyzed by redirecting a fraction of the cold exhaust air to provide supplemental cooling of the condenser. It is noted that cooling the condenser improves the system's performance better than cooling the fresh air at 0% of returned air to the system.To sum up, the dissertation shows that the comparison between the conventional reefer and the MC illustrates the promising advantages of the MC, then a transient analysis is developed for deeply understanding the behaviors of the system component parameters, which leads finally to improvements in the system to enhance its performance.
ContributorsSyam, Mahmmoud Muhammed (Author) / Phelan, Patrick (Thesis advisor) / Villalobos, Rene (Thesis advisor) / Huang, Huei-Ping (Committee member) / Bocanegra, Luis (Committee member) / Al Omari, Salah (Committee member) / Arizona State University (Publisher)
Created2023
Description
ABSTRACTThis dissertation addresses two pivotal challenges within the US technology industry: racial equity and the rise of artificial intelligence (AI). It investigates whether the integration of AI in human resources (HR) can foster inclusivity and diversity for Black women in the tech workforce. Despite numerous diversity initiatives, Black women account for less than 2% of the US tech workforce, symbolizing a persistent challenge. Furthermore, AI often perpetuates structural biases, magnifying workforce inequities. This dissertation employs intersectionality, responsible innovation, and algorithmic bias theories to amplify the voices of Black women. It poses three critical questions: 1) How have Black women's HR experiences influenced diversity issues in the tech industry? 2) How is AI in HR developed considering the experiences of Black women? 3) What measures can enhance the role of AI in HR to promote diversity without deepening inequalities? Key findings reveal that current HR practices do not adequately serve Black women, driven by competing corporate priorities. Solutions should concentrate on recruiting, developing, promoting, and retaining Black women. Black women acknowledge the potential of AI to either reinforce or mitigate biases, yet they express apprehension about the development and implementation of AI in HR, which often lacks Black women's input. For AI to facilitate positive diversity results, companies must actively involve Black women in its development. This entails understanding the problems Black women face, using insights to design AI that addresses these issues and supports Black women's success, and engaging Black women in the development and assessment of AI implementations in HR, thereby enhancing accountability for diversity outcomes.
ContributorsWhye, Barbara Hickman (Author) / Miller, Clark (Thesis advisor) / Richter, Jennifer (Committee member) / Scott, Kimberly (Committee member) / Arizona State University (Publisher)
Created2023
Description
Academic tracking has long been a subject of debate due to its potential impact on educational equity, with students who are tracked highly receiving a higher quality
education in comparison to students tracked lowly. These disparities in education quality
may be affecting students’ outcomes, as it has been demonstrated that the short-term
academic outcomes of students, such as their grades, tend to be affected by their
academic track positioning. This dissertation builds upon these previous findings by
utilizing a subsample of 20,584 students from the High School Longitudinal Study (2009)
to examine the relation between academic track positioning and post-secondary education
attendance, program length, college major, and expected future job. Additionally, the
relation between academic tracking and each of these outcomes was also assessed using
mediation, with potential mediators including education aspiration, expectations, and
academic self-efficacy. Findings suggest that academic track positioning in math and
science are influential in students’ post-secondary and career outcomes, with students
who are positioned highly in either subject having greater post-secondary attendance,
program length, higher representation in STEM college majors, and expectations for
future jobs in STEM fields in comparison to students tracked lowly. Additionally,
education aspirations and expectations mediated the relations between math academic
track positioning and each of the outcomes, although the effects were small in size.
Educators should consider exploring avenues for improving education quality in low
academic tracks.
ContributorsWoods, Kenton Bentley (Author) / Hanish, Laura (Thesis advisor) / DeLay, Dawn (Committee member) / Martin, Carol (Committee member) / Jager, Justin (Committee member) / Arizona State University (Publisher)
Created2023
Description
Groundwater contamination is of environmental and human health concern. Bioremediation is a nature-based method for contaminant treatment. Bioremediation, which relies on the ability of microorganisms to destroy or transform contaminants, must be reliable and cost-competitive in comparison to more traditional treatment methods. Two hurdles must be overcome to enhance bioremediation’s effectiveness and competitiveness: i) being able to degrade recalcitrant compounds, and ii) being able to control the growth rate and location of microorganisms involved in bioremediation in the subsurface. My dissertation adds foundational knowledge and engineering application on how to biodegrade recalcitrant emerging and legacy halogenated compounds. Generating biotransformation knowledge on the recalcitrant emerging contaminants called per- and polyfluoroalkyl substances (PFAS) may lead to solutions for protecting both people and the planet. In my dissertation, I analyzed PFAS biotransformation and microbial defluorination literature via meta-analytical and bibliometric methods to identify unexplored topics and experimental conditions. The metanalytical work identified trends in PFAS microbial biotransformation science to inform future experimental design.
The second hurdle which must be overcome is being able to control bacterial growth in the subsurface. During bioremediation implementation microbial overgrowth may clog injection wells and the subsurface, leading to reduced porosity and treatment efficacy. Contaminant treatment schemes based on aerobic cometabolism frequently exhibit overgrowth at subsurface injection points for O2 (the electron acceptor) and a labile hydrocarbon (e.g., propane). My dissertation work experimentally evaluated acetylene as a microbial inhibitor for use in controlling microbial overgrowth during trichloroethene (TCE) aerobic cometabolism. I demonstrated that acetylene reduces the likelihood of microbial overgrowth of TCE-degrading microorganisms in soil-free microcosms and aquifer soil columns while retaining TCE degradation capacity. Cumulatively, my dissertation provides foundational knowledge for academics and bioremediation practitioners to develop robust and reliable bioremediation technologies.
ContributorsSkinner, Justin Paul (Author) / Delgado, Anca G. (Thesis advisor) / Rittmann, Bruce E (Committee member) / Chu, Min Ying Jacob (Committee member) / Arizona State University (Publisher)
Created2023
Description
The issue of teacher shortages has been a national crisis in the United States. Teachers have expressed feeling exhausted and burnt out from the profession. The COVID-19 pandemic made these feelings worse, with the rates of teachers leaving the profession being higher than what has occurred in the past. Teachers’ sense of belonging at their schools and their professional identities as educators can have an impact on their decisions to stay in or leave the field of education. Participation in a community of practice has been shown to have a positive impact on teachers’ sense of belonging and identities. This qualitative study cultivated a community of practice composed of teachers who were new to their schools but not necessarily new to teaching. Data collected included interviews, recordings of community of practice meetings, participant reflection documents, and a researcher journal. Results suggested that teachers valued getting to know their colleagues, learning unique classroom practices, and that their participation in the community of practice had a positive impact on their sense of belonging at their new schools. The impacts of the community of practice on teachers’ professional identities were inconclusive. The discussion included an analysis of themes that emerged from the data, limitations of the study, and recommendations for researchers and practitioners.
ContributorsTarbutton, Taylor Lane (Author) / Judson, Eugene (Thesis advisor) / Frias, Elizabeth (Thesis advisor) / Weber, Steven (Committee member) / Arizona State University (Publisher)
Created2023
Description
In an era of educational transformation, teacher leaders play a pivotal role in facilitating systemic change within schools. This dissertation presents a single-case action research study investigating the support structures provided by a Team Lead Communities of Practice (TL CoP) to nurture teacher leaders. The primary aim of this research is to explore the effectiveness of the TL CoP in supporting teacher leaders at one school site. Utilizing qualitative data from interviews, participant journals, researcher memos, and agendas, this study captures the perspectives of team leads of interdisciplinary teams. The findings emphasize the need for flexible support systems tailored to the unique challenges teacher leaders face. Offering teacher leaders agency in their learning is paramount to their success. Additionally, structured time for collaboration and problem-solving within the TL CoP is crucial. One significant revelation is the importance of role clarity. Team leads need a clear understanding of their responsibilities to effectively lead teams and drive systemic change. This research contributes to the literature on educational leadership by highlighting the vital role of teacher leaders and the potential of TL CoPs in supporting their development. It advocates for the creation of such communities as a promising strategy to empower teacher leaders, providing them with essential support, dedicated collaboration time, and role clarity. As schools evolve to meet the demands of the 21st century, the insights from this study offer guidance for educational stakeholders seeking to cultivate a culture of leadership and foster systemic change through teacher leadership.
ContributorsPreston, Lee Allyne Cox (Author) / Markos, Amy (Thesis advisor) / Corner, Kevin (Committee member) / Fourlis, Andi (Committee member) / Arizona State University (Publisher)
Created2023
Description
Novel means are needed to diagnose neurodegenerative diseases (NDDs) and cancer, given delays in medical diagnosis and rising rates of disease incidence, prevalence, and mortality worldwide. Development of NDDs and cancer has been linked to environmental toxins. Ensuing epigenetic changes may serve as helpful biomarkers to diagnose amyotrophic lateral sclerosis (ALS), Parkinson’s Disease (PD), and Alzheimer’s Disease (AD) as well as various cancers sooner and more accurately. This dissertation tabulates and evaluates a spectrum of diagnostic matrixes (i.e., soil, sewage sludge, blood) and markers of disease to inform disease surveillance. A literature search using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Bradford Hill criteria implicated BMAA, formaldehyde, Mn, Hg, and Zn as environmental factors with strong association to ALS risk. Another PRISMA search identified epigenetic changes (e.g., DNA methylation) in NDD patients associated with environmental toxic exposures to air pollutants, heavy metals, and organic chemicals. Of the 180 environmental toxins hypothesized to be associated with AD, PD, or ALS, four heavy metals (As, Cd, Mn, and Hg) were common to these NDDs. Sources, as well as evidence and proxies of human exposure to these heavy metals and Pb were investigated here, namely the metal industries, and metal concentrations in topsoil, sewage sludge, and blood. Concentrations of Cd and Pb in sewage sludge were found to be significantly correlated with NDD prevalence rates in co-located populations (state-level) with odds ratios of 2.91 and 4.08, respectively. Markers of exposure and disease in urine and feces were also evaluated using PRISMA, finding 73 of 94 epigenetic biomarker panels to be valid for tracking primarily gastric and urinary cancers. In all studies, geospatial analyses indicated a preference in study cohorts located in the U.S., Europe, and the northern hemisphere, leaving underserved many populous regions particularly in the southern hemisphere. This dissertation draws attention to sewage sludge as a currently underutilized proxy matrix for assessing toxic human exposures and further identified a spectrum of particularly attractive, non-invasive biomarkers for future diagnostic use to promote early detection, survivability, and quality of life of individuals at risk of NDDs and cancer.
ContributorsNewell, Melanie Engstrom (Author) / Halden, Rolf U. (Thesis advisor) / Mastroeni, Diego (Committee member) / Lee, Heewook (Committee member) / Arizona State University (Publisher)
Created2023
Description
Sexual minority youth experience significant health and mental health disparities compared to their heterosexual peers. Positive family relationships and effective parenting practices have been found to promote youth’s well-being broadly; however, there has been very little research conducted within the sexual and gender minority (SGM) populations. Furthermore, even though parental/familial acceptance of youth’s SGM identity has been consistently shown to be associated with better youth’s adjustment, very few studies have examined how the broader general parenting and familial processes intersect with SGM-acceptance. Hence, the aim of this study was to first examine the associations between (a) general parenting practices and family environment (i.e., positive parenting, negative parenting, mindful parenting, and family cohesion) and (b) SGM-specific practices (i.e., parental acceptance, parental microaggression and microaffirming behaviors) on SGM youth’s health (i.e., sleep disturbances & impairment, physical activity) and mental health (i.e., internalizing and externalizing symptoms) outcomes. The second aim of this study was to examine how SGM-specific practices may moderate the associations between general parenting and family environment variables and SGM youth health and mental health outcomes. The sample included 261 parents (Mage = 41.45, SD = 6.30, age range = 30 to 59) of sexual minority adolescents (Mage = 15.08, SD = 1.40, age range = 13 to 17) recruited nationwide in the U.S. via online recruitment. Results revealed that negative parenting was positively associated with child’s internalizing symptoms, externalizing symptoms, sleep disturbance, and sleep impairment. Meanwhile, mindful parenting was negatively associated with internalizing symptoms only. Parental acceptance, positive parenting, and family cohesion were not significantly associated with youth outcomes. No significant interaction emerged between parental acceptance and the four general parenting and family variables in predicting youth outcomes. Findings highlight the importance of examining how parenting practices and family processes were related to sexual minority adolescents physical and mental health outcomes.
ContributorsThamrin, Hardian (Author) / Gonzales, Nancy A (Thesis advisor) / Toomey, Russell B (Committee member) / Anderson, Samantha F (Committee member) / Perez, Marisol (Committee member) / Arizona State University (Publisher)
Created2024
Description
Waste plastic is considered an environmental pollutant because it is not biodegradable. Therefore, there is increased interest in the use of recycled plastic in pavement construction. Polyethylene terephthalate (PET) is a thermoplastic polymer that is commonly used in the manufacturing of containers and bottles. Waste PET is a durable material that has shown enhancement in performance when introduced into asphalt binder and asphalt mixtures. However, PET particles tend to separate from asphalt because of differences in density, molecular structure, molecular weight, and viscosity, leading to inadequate dispersion of PET particles in the asphalt. This incompatibility between PET and asphalt causes segregation, where storage stability becomes an issue. To solve this problem, applying a surface activation on the PET using another abundant urban waste (waste vegetable oil) was examined in this study, showing this method can be effective to enhance PET-asphalt interactions and consequently the storage stability of PET-modified asphalt. To ensure proper surface activation, it is important to thoroughly understand the chemo-mechanics of asphalt containing PET particles as well as the underlying interaction mechanism at the molecular level. Therefore, this study integrates a multi-scale approach using computational modeling based on density functional theory along with laboratory experiments to provide an in-depth understanding of the mechanisms of interaction between surface-activated PET and asphalt. To do so, the efficacy of bio-oil treatment was examined in terms of both the surface-activation capability and the durability of the resulting PET-modified asphalt. It was found that the grafted bio-oil on the PET particles can make a strong interaction with bituminous composites, leading to enhancing the durability and extending the service life of asphalt pavement by reducing the diffusion of free radicals and moisture into the bulk. The study was further extended to study the effect of coating the PET with biochar, showing the latter coating can improve the mechanical properties of the PET-modified asphalt and the adsorption behavior of the PET for volatile organic compounds. The performance of the waste PET was compared with another widely used modifier, crumb rubber.
ContributorsAldagari, Sand (Author) / Fini, Elham (Thesis advisor) / Kaloush, Kamil (Committee member) / Ozer, Hasan (Committee member) / Arizona State University (Publisher)
Created2024
Description
Research demonstrates that maladaptive eating (e.g., restriction, disinhibition) and persistent depressive symptoms often co-occur and may reinforce each other over time. However, little is known regarding the etiology of early maladaptive eating and depressive symptoms among Mexican American children and how cultural orientation impacts co-occurrence. This study aimed to map the emerging structure of maladaptive eating–depression symptom networks, identify early dysfunctional mechanisms (i.e., symptoms) that maintain network structure, and explore how cultural orientation influences mechanisms. The sample included 263 low-income Mexican American children, assessed at 6-, 7.5-, and 9-years-old via maternal report. Mothers completed surveys on child eating, depressive symptoms, and cultural orientation. Data was analyzed using regularized partial correlation, Ising, and mixed graphical network models. Results showed that maladaptive eating networks were invariant over time. Central maladaptive eating symptoms were related to food responsiveness. Depressive symptom and combined networks were not stable enough for interpretation. Sadness and thoughts of worthlessness/inferiority emerged as central depressive symptoms at age 9. No bridge symptoms or moderated effects were large enough for interpretation. This study is the first of its kind to examine associations between eating and depressive symptoms among Mexican American children using network analysis. Results provide etiological information on the structure of co-occurring eating and depressive symptoms across late childhood and provide direction towards optimal prevention targets among this group.
ContributorsHernandez, Juan Carlos (Author) / Perez, Marisol (Thesis advisor) / Luecken, Linda (Committee member) / Berkel, Cady (Committee member) / Cruz, Rick (Committee member) / Arizona State University (Publisher)
Created2024