Matching Items (110)
Description
Adolescence is an important period of scaffolding for educational attainment, which is among the strongest predictors of outcomes in multiple domains. Parents who encourage academic success and promote self-regulation may enhance their offspring’s educational attainment. However, parents with externalizing disorders present a complex constellation of risk factors, including low educational attainment and poor parenting, and are more likely to have children with high levels of disinhibition. Previous research has identified low parental education, poor parenting and adolescent impulsivity as threats to educational attainment, but has not examined risk factors for discrepancies in educational attainment among siblings of the same family. Furthermore, studies have not examined the between- and within-family mechanisms that may explain why adolescents with externalizing parents have low educational attainment. The current study addressed these gaps by testing between- and within-family predictors of educational attainment using data from a longitudinal, multigenerational study that oversampled families at risk for alcohol use disorder. The sample consisted of 555 biological siblings within 240 families. We tested whether parental externalizing predicted lower educational attainment through parents’ own lower education, parents’ differential treatment of offspring, and impulsivity. Results suggested that between families, parents with externalizing disorders had lower educational attainment and more impulsive offspring, but did not exhibit increased differential parenting. Within families, siblings with greater impulsivity had lower educational attainment, whereas receiving more preferential maternal treatment than one’s siblings predicted higher educational attainment. Low parental educational attainment mediated the relation between parental externalizing disorders and low offspring educational attainment.
ContributorsPaxton, Lauren (Author) / Chassin, Laurie (Thesis director) / Corbin, William (Committee member) / Blake, Austin (Committee member) / Edwards, Michael (Committee member) / Barrett, The Honors College (Contributor) / School of Social Transformation (Contributor) / Department of Psychology (Contributor) / Economics Program in CLAS (Contributor)
Created2021-12
Description
Alkali activated mine tailing-slag blends and mine tailing-cement blends containing mine tailings as the major binder constituent are evaluated for their setting time behavior,
reactivity properties, flow characteristics, and compressive strengths. Liquid sodium
silicate and sodium hydroxide are used as the activator solution. The effects of varying
alkali oxide-to-powder ratio (n value) and silicon oxide-to-alkali oxide ratio (Ms value) is
explored. The reactivity of all blends prepared in this study is studied using an isothermal
calorimeter. Mine tailing-cement blends show a higher initial heat release peak than mine
tailing-slag blends, whereas their cumulative heat release is comparable for higher n values
of 0.050 to 0.100. Compressive strength tests and rheological studies were done for the
refined blends selected based on setting time criterion. Setting times and compressive
strengths are found to depend significantly on the activator parameters and binder
compositions, allowing fine-tuning of the mix proportion parameters based on the intended
end applications. The compressive strength of the selected mine tailing-slag blends and
mine tailing-cement blends are in the range of 7-40 MPa and 4-11 MPa, respectively.
Higher compressive strength is generally achieved at lower Ms and higher n values for mine
tailing-slag blends, while a higher Ms yields better compressive strength in the case of mine
tailing-cement blends. Rheological studies indicate a decrease in yield stress and viscosity
with increase in the replacement ratio, while a higher activator concentration increase both.
Oscillatory shear studies were used to evaluate the storage modulus and loss modulus of
the mine tailing binders. The paste is seen to exhibit a more elastic behavior at n values of
0.05 and 0.075, however the viscous behavior is seen to dominate at higher n value of 0.1
at similar replacement ratios and Ms value. A higher Ms value is also seen to increase the
onset point of the drop in both the storage and loss modulus of the pastes. The studied also
investigated the potential use of mine tailing blends for coating applications. The pastes
with higher alkalinity showed a lesser crack percentage, with a 10% slag replacement ratio
having a better performance compared to 20% and 30% slag replacement ratios. Overall,
the study showed that the activation parameters and mine tailings replacement level have
a significant influence on the properties of both mine tailing-slag binders and mine tailing-cement binders, thereby allowing selection of suitable mix design for the desired end
application, allowing a sustainable approach to dispose the mine tailings waste
ContributorsRamasamy Jeyaprakash, Rijul Kanth (Author) / Neithalath, Narayanan (Thesis advisor) / Rajan, Subramaniam (Committee member) / Mobasher, Barzin (Committee member) / Arizona State University (Publisher)
Created2023
Description
Concrete develops strength rapidly after mixing and is highly influenced by temperature and curing process. The material characteristics and the rate of property development, along with the exposure conditions influences volume change mechanisms in concrete, and the cracking propensity of the mixtures. Furthermore, the structure geometry (due to restraint as well as the surface area-to-volume ratio) also influences shrinkage and cracking. Thus, goal of this research is to better understand and predict shrinkage cracking in concrete slab systems under different curing conditions. In this research, different concrete mixtures are evaluated on their propensity to shrink based on free shrinkage and restrained shrinkage tests.Furthermore, from the data obtained from restrained ring test, a casted slab is measured for shrinkage. Effects of different orientation of restraints are studied and compared to better understand the shrinking behavior of the concrete mixtures. The results show that the maximum shrinkage is near the edges of the slab and decreases towards the center. Shrinkage near the edges with no restraint is found out to be more than the shrinkage towards the edges with restraining effects.
ContributorsNimbalkar, Atharwa Samir (Author) / Neithalath, Narayanan (Thesis advisor) / Mobasher, Barzin (Thesis advisor) / Rajan, Subramaniam (Committee member) / Arizona State University (Publisher)
Created2023
Description
Attention-Deficit/Hyperactivity Disorder (ADHD) impacts 7% of children and is associated with serious impairment throughout the lifespan. Though considered a chronic, stable condition, symptoms fluctuate substantially during adolescence, and symptom trajectory is linked to adult outcomes. A small number of studies have examined symptom trajectory during adolescence, but these have predominately examined demographic predictors. As a neurodevelopmental disorder, ADHD is theorized to arise from deficits in executive functions (EFs). Extant literature identifies three major components of EF- working memory, behavioral inhibition, and set shifting- as interrelated constructs underlying ADHD symptom expression. This study aimed to 1.) identify trajectories of ADHD symptoms, 2.) examine demographic predictors of trajectories, and 3.) examine whether EF predicts symptom trajectory using five timepoints from the Adolescent Brain Cognitive Development study, a large-scale, representative, population-based sample from the United States. 1,605 participants meeting criteria for ADHD included in analyses. ADHD symptoms were measured by parent report on the widely used Achenbach Child Behavior Checklist. Growth Mixture Modeling was used to model trajectories of ADHD symptoms. However, poor entropy indicated trajectories were not clearly differentiated and predictors could not be examined. Therefore, exploratory regression was conducted to examine predictors of ADHD symptom change from baseline to 3-year follow-up. Male sex, medication use, greater than high school parental education, and better EF all predicted increasing ADHD symptoms. Findings must be interpreted with caution due to their exploratory nature and poor validity of the measure used for ADHD symptoms, which was found to have sensitivity of only 22.58%. Given the strong theoretical and empirical link between ADHD symptoms and EF, additional research on the connection between EF and disorder trajectory with more robust measures of EF is warranted.
ContributorsChromik, Lindsay C (Author) / Friedman, Lauren (Thesis advisor) / McNeish, Daniel (Committee member) / Chassin, Laurie (Committee member) / Arizona State University (Publisher)
Created2024
Description
Anxiety disorder diagnosis is a risk factor for alcohol use disorders (AUDs), but mechanisms of risk are not well understood. Studies show that anxious individuals receive greater negative reinforcement from alcohol when consumed prior to a stressor, but few studies have examined whether anxious individuals receive greater negative (or positive) reinforcement from alcohol in a general drinking context (i.e., no imminent stressor). Previous studies have also failed to examine possible moderating effects of specific drinking contexts (e.g., drinking in a group or alone). Finally, no studies have investigated mediating variables that might explain the relationship between anxiety and reinforcement from alcohol, such as physiological response to alcohol (e.g., cortisol response). Data for this study were drawn from a large alcohol administration study (N = 447) wherein participants were randomized to receive alcohol (target peak BAC: .08 g%) or placebo in one of four contexts: group simulated bar, solitary simulated bar, group sterile laboratory, solitary sterile laboratory. It was hypothesized that anxiety would be associated with positive subjective response (SR) under alcohol (above and beyond placebo), indicating stronger reinforcement from alcohol. It was also hypothesized that social and physical drinking context would moderate this relationship. Finally, it was hypothesized that anxiety would be associated with a blunted cortisol response to alcohol (compared to placebo) and this blunted cortisol response would be associated with stronger positive SR and weaker negative SR. Results showed that anxiety was not associated with positive SR in the full sample, but drinking context did moderate the anxiety/SR relationship in most cases (e.g., anxiety was significantly associated with positive SR (stimulation) under placebo in solitary contexts only). There was no evidence that cortisol response to alcohol mediated the relationship between anxiety and SR. This study provides evidence that anxious drinkers expect stronger positive reinforcement from alcohol in solitary contexts, which has implications for intervention (e.g., modification of existing interventions like expectancy challenge). Null findings regarding cortisol response suggest alcohol’s effect on cortisol response to stress (rather than cortisol response to alcohol consumption) may be more relevant for SR and drinking behavior among anxious individuals.
ContributorsMenary, Kyle Robert (Author) / Corbin, William (Thesis advisor) / Chassin, Laurie (Committee member) / Meier, Madeline (Committee member) / Grimm, Kevin (Committee member) / Arizona State University (Publisher)
Created2018
Description
Being a remarkably versatile and inexpensive building material, concrete has found tremendous use in development of modern infrastructure and is the most widely used material in the world. Extensive research in the field of concrete has led to the development of a wide array of concretes with applications ranging from building of skyscrapers to paving of highways. These varied applications require special cementitious composites which can satisfy the demand for enhanced functionalities such as high strength, high durability and improved thermal characteristics among others.
The current study focuses on the fundamental understanding of such functional composites, from their microstructural design to macro-scale application. More specifically, this study investigates three different categories of functional cementitious composites. First, it discusses the differences between cementitious systems containing interground and blended limestone with and without alumina. The interground systems are found to outperform the blended systems due to differential grinding of limestone. A novel approach to deduce the particle size distribution of limestone and cement in the interground systems is proposed. Secondly, the study delves into the realm of ultra-high performance concrete, a novel material which possesses extremely high compressive-, tensile- and flexural-strength and service life as compared to regular concrete. The study presents a novel first principles-based paradigm to design economical ultra-high performance concretes using locally available materials. In the final part, the study addresses the thermal benefits of a novel type of concrete containing phase change materials. A software package was designed to perform numerical simulations to analyze temperature profiles and thermal stresses in concrete structures containing PCMs.
The design of these materials is accompanied by material characterization of cementitious binders. This has been accomplished using techniques that involve measurement of heat evolution (isothermal calorimetry), determination and quantification of reaction products (thermo-gravimetric analysis, x-ray diffraction, micro-indentation, scanning electron microscopy, energy-dispersive x-ray spectroscopy) and evaluation of pore-size distribution (mercury intrusion porosimetry). In addition, macro-scale testing has been carried out to determine compression, flexure and durability response. Numerical simulations have been carried out to understand hydration of cementitious composites, determine optimum particle packing and determine the thermal performance of these composites.
The current study focuses on the fundamental understanding of such functional composites, from their microstructural design to macro-scale application. More specifically, this study investigates three different categories of functional cementitious composites. First, it discusses the differences between cementitious systems containing interground and blended limestone with and without alumina. The interground systems are found to outperform the blended systems due to differential grinding of limestone. A novel approach to deduce the particle size distribution of limestone and cement in the interground systems is proposed. Secondly, the study delves into the realm of ultra-high performance concrete, a novel material which possesses extremely high compressive-, tensile- and flexural-strength and service life as compared to regular concrete. The study presents a novel first principles-based paradigm to design economical ultra-high performance concretes using locally available materials. In the final part, the study addresses the thermal benefits of a novel type of concrete containing phase change materials. A software package was designed to perform numerical simulations to analyze temperature profiles and thermal stresses in concrete structures containing PCMs.
The design of these materials is accompanied by material characterization of cementitious binders. This has been accomplished using techniques that involve measurement of heat evolution (isothermal calorimetry), determination and quantification of reaction products (thermo-gravimetric analysis, x-ray diffraction, micro-indentation, scanning electron microscopy, energy-dispersive x-ray spectroscopy) and evaluation of pore-size distribution (mercury intrusion porosimetry). In addition, macro-scale testing has been carried out to determine compression, flexure and durability response. Numerical simulations have been carried out to understand hydration of cementitious composites, determine optimum particle packing and determine the thermal performance of these composites.
ContributorsArora, Aashay (Author) / Neithalath, Narayanan (Thesis advisor) / Rajan, Subramaniam D. (Committee member) / Mobasher, Barzin (Committee member) / Chawla, Nikhilesh (Committee member) / Hoover, Christian G (Committee member) / Arizona State University (Publisher)
Created2018
Description
Mediation analysis is used to investigate how an independent variable, X, is related to an outcome variable, Y, through a mediator variable, M (MacKinnon, 2008). If X represents a randomized intervention it is difficult to make a cause and effect inference regarding indirect effects without making no unmeasured confounding assumptions using the potential outcomes framework (Holland, 1988; MacKinnon, 2008; Robins & Greenland, 1992; VanderWeele, 2015), using longitudinal data to determine the temporal order of M and Y (MacKinnon, 2008), or both. The goals of this dissertation were to (1) define all indirect and direct effects in a three-wave longitudinal mediation model using the causal mediation formula (Pearl, 2012), (2) analytically compare traditional estimators (ANCOVA, difference score, and residualized change score) to the potential outcomes-defined indirect effects, and (3) use a Monte Carlo simulation to compare the performance of regression and potential outcomes-based methods for estimating longitudinal indirect effects and apply the methods to an empirical dataset. The results of the causal mediation formula revealed the potential outcomes definitions of indirect effects are equivalent to the product of coefficient estimators in a three-wave longitudinal mediation model with linear and additive relations. It was demonstrated with analytical comparisons that the ANCOVA, difference score, and residualized change score models’ estimates of two time-specific indirect effects differ as a function of the respective mediator-outcome relations at each time point. The traditional model that performed the best in terms of the evaluation criteria in the Monte Carlo study was the ANCOVA model and the potential outcomes model that performed the best in terms of the evaluation criteria was sequential G-estimation. Implications and future directions are discussed.
ContributorsValente, Matthew J (Author) / Mackinnon, David P (Thesis advisor) / West, Stephen G. (Committee member) / Grimm, Keving (Committee member) / Chassin, Laurie (Committee member) / Arizona State University (Publisher)
Created2018
Description
Phase change materials (PCMs) are combined sensible-and-latent thermal energy storage materials that can be used to store and dissipate energy in the form of heat. PCMs incorporated into wall-element systems have been well-studied with respect to energy efficiency of building envelopes. New applications of PCMs in infrastructural concrete, e.g., for mitigating early-age cracking and freeze-and-thaw induced damage, have also been proposed. Hence, the focus of this dissertation is to develop a detailed understanding of the physic-chemical and thermo-mechanical characteristics of cementitious systems and novel coating systems for wall-elements containing PCM. The initial phase of this work assesses the influence of interface properties and inter-inclusion interactions between microencapsulated PCM, macroencapsulated PCM, and the cementitious matrix. The fact that these inclusions within the composites are by themselves heterogeneous, and contain multiple components necessitate careful application of models to predict the thermal properties. The next phase observes the influence of PCM inclusions on the fracture and fatigue behavior of PCM-cementitious composites. The compliant nature of the inclusion creates less variability in the fatigue life for these composites subjected to cyclic loading. The incorporation of small amounts of PCM is found to slightly improve the fracture properties compared to PCM free cementitious composites. Inelastic deformations at the crack-tip in the direction of crack opening are influenced by the microscale PCM inclusions. After initial laboratory characterization of the microstructure and evaluation of the thermo-mechanical performance of these systems, field scale applicability and performance were evaluated. Wireless temperature and strain sensors for smart monitoring were embedded within a conventional portland cement concrete pavement (PCCP) and a thermal control smart concrete pavement (TCSCP) containing PCM. The TCSCP exhibited enhanced thermal performance over multiple heating and cooling cycles. PCCP showed significant shrinkage behavior as a result of compressive strains in the reinforcement that were twice that of the TCSCP. For building applications, novel PCM-composites coatings were developed to improve and extend the thermal efficiency. These coatings demonstrated a delay in temperature by up to four hours and were found to be more cost-effective than traditional building insulating materials.
The results of this work prove the feasibility of PCMs as a temperature-regulating technology. Not only do PCMs reduce and control the temperature within cementitious systems without affecting the rate of early property development but they can also be used as an auto-adaptive technology capable of improving the thermal performance of building envelopes.
The results of this work prove the feasibility of PCMs as a temperature-regulating technology. Not only do PCMs reduce and control the temperature within cementitious systems without affecting the rate of early property development but they can also be used as an auto-adaptive technology capable of improving the thermal performance of building envelopes.
ContributorsAguayo, Matthew Joseph (Author) / Neithalath, Narayanan (Thesis advisor) / Rajan, Subramaniam D. (Committee member) / Mobasher, Barzin (Committee member) / Underwood, Benjamin (Committee member) / Liu, Yongming (Committee member) / Arizona State University (Publisher)
Created2018
Description
This research summarizes the validation testing completed for the material model MAT213, currently implemented in the LS-DYNA finite element program. Testing was carried out using a carbon fiber composite material, T800-F3900. Stacked-ply tension and compression tests were performed for open-hole and full coupons. Comparisons of experimental and simulation results showed a good agreement between the two for metrics including, stress-strain response and displacements. Strains and displacements in the direction of loading were better predicted by the simulations than for that of the transverse direction.
Double cantilever beam and end notched flexure tests were performed experimentally and through simulations to determine the delamination properties of the material at the interlaminar layers. Experimental results gave the mode I critical energy release rate as having a range of 2.18 – 3.26 psi-in and the mode II critical energy release rate as 10.50 psi-in, both for the pre-cracked condition. Simulations were performed to calibrate other cohesive zone parameters required for modeling.
Samples of tested T800/F3900 coupons were processed and examined with scanning electron microscopy to determine and understand the underlying structure of the material. Tested coupons revealed damage and failure occurring at the micro scale for the composite material.
Double cantilever beam and end notched flexure tests were performed experimentally and through simulations to determine the delamination properties of the material at the interlaminar layers. Experimental results gave the mode I critical energy release rate as having a range of 2.18 – 3.26 psi-in and the mode II critical energy release rate as 10.50 psi-in, both for the pre-cracked condition. Simulations were performed to calibrate other cohesive zone parameters required for modeling.
Samples of tested T800/F3900 coupons were processed and examined with scanning electron microscopy to determine and understand the underlying structure of the material. Tested coupons revealed damage and failure occurring at the micro scale for the composite material.
ContributorsHolt, Nathan T (Author) / Rajan, Subramaniam D. (Thesis advisor) / Mobasher, Barzin (Committee member) / Hoover, Christian (Committee member) / Arizona State University (Publisher)
Created2018
Description
The tendency for psychopathology to aggregate within families is well-documented, though little is known regarding the level of specificity at which familial transmission of symptomology occurs. The current study first tested competing higher-order structures of psychopathology in adolescence, indexing general and more specific latent factors. Second, parent-offspring transmission was tested for broadband domain specificity versus transmission of a general liability for psychopathology. Lastly, genetic and environmental mechanisms underlying the familial aggregation of psychopathology were examined using nuclear twin-family models. The sample was comprised of five hundred adolescent twin pairs (mean age 13.24 years) and their parents drawn from the Wisconsin Twin Project. Twins and parents completed independent diagnostic interviews. For aim 1, correlated factors, bifactor, and general-factor models were tested using adolescent symptom count data. For aim 2, structural equation modeling was used to determine whether broadband domain-specific transmission effects were necessary to capture parent-offspring resemblance in psychopathology above and beyond a general transmission effect indexed by the latent correlation between a parental internalizing factor and offspring P-factor. For aim 3, general factor models were fitted in both generations, and factor scores were subsequently extracted and used in nuclear twin-family model testing. Results indicated that the bifactor model exhibited the best fit to the adolescent data. Familial aggregation of psychopathology was sufficiently accounted for by the transmission of a general liability. Lastly, the best fitting reduced nuclear twin-family model indicated that additive genetic, sibling-specific shared environmental, and nonshared environmental influences contributed to general psychopathology. Parent-offspring transmission was accounted for by shared genetics only, whereas co-twin aggregation was additionally explained by sibling-specific shared environmental factors. Results provide novel insight into the specificity and etiology of the familial aggregation of psychopathology.
ContributorsOro, Veronica (Author) / Lemery-Chalfant, Kathryn (Thesis advisor) / Chassin, Laurie (Committee member) / Doane, Leah D (Committee member) / Arizona State University (Publisher)
Created2019