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Description
Heating of asphalt during production and construction causes the volatilization and oxidation of binders used in mixes. Volatilization and oxidation causes degradation of asphalt pavements by increasing the stiffness of the binders, increasing susceptibility to cracking and negatively affecting the functional and structural performance of the pavements. Degradation of asphalt binders by volatilization and oxidation due to high production temperature occur during early stages of pavement life and are known as Short Term Aging (STA). Elevated temperatures and increased exposure time to elevated temperatures causes increased STA of asphalt. The objective of this research was to investigate how elevated mixing temperatures and exposure time to elevated temperatures affect aging and stiffening of binders, thus influencing properties of the asphalt mixtures. The study was conducted in two stages. The first stage evaluated STA effect of asphalt binders. It involved aging two Performance Graded (PG) virgin asphalt binders, PG 76-16 and PG 64-22 at two different temperatures and durations, then measuring their viscosities. The second stage involved evaluating the effects of elevated STA temperature and time on properties of the asphalt mixtures. It involved STA of asphalt mixtures produced in the laboratory with the PG 64-22 binder at mixing temperatures elevated 25OF above standard practice; STA times at 2 and 4 hours longer than standard practices, and then compacted in a gyratory compactor. Dynamic modulus (E*) and Indirect Tensile Strength (IDT) were measured for the aged mixtures for each temperature and duration to determine the effect of different aging times and temperatures on the stiffness and fatigue properties of the aged asphalt mixtures. The binder test results showed that in all cases, there was increased viscosity. The results showed the highest increase in viscosity resulted from increased aging time. The results also indicated that PG 64-22 was more susceptible to elevated STA temperature and extended time than the PG 76-16 binders. The asphalt mixture test results confirmed the expected outcome that increasing the STA and mixing temperature by 25oF alters the stiffness of mixtures. Significant change in the dynamic modulus mostly occurred at four hour increase in STA time regardless of temperature.
ContributorsLolly, Rubben (Author) / Kaloush, Kamil (Thesis advisor) / Bearup, Wylie (Committee member) / Zapata, Claudia (Committee member) / Mamlouk, Michael (Committee member) / Arizona State University (Publisher)
Created2013
Description
Incidental learning of sequential information occurs in visual, auditory and tactile domains. It occurs throughout our lifetime and even in nonhuman species. It is likely to be one of the most important foundations for the development of normal learning. To date, there is no agreement as to how incidental learning occurs. The goal of the present set of experiments is to determine if visual sequential information is learned in terms of abstract rules or stimulus-specific details. Two experiments test the extent to which interaction with the stimuli can influence the information that is encoded by the learner. The results of both experiments support the claim that stimulus and domain specific details directly shape what is learned, through a process of tuning the neuromuscular systems involved in the interaction between the learner and the materials.
ContributorsMarsh, Elizabeth R (Author) / Glenberg, Arthur M. (Thesis advisor) / Amazeen, Eric (Committee member) / Brewer, Gene (Committee member) / Arizona State University (Publisher)
Created2013
Description
Bully victimization has been associated with blunted cardiovascular responses to stress as well as elevated responses to stress. The difference between these altered physiological responses to stress is largely unknown. This study explored several possible moderators to the relationship between chronic stress and future cardiac output (an indicator of increased stress) in response to future stressors. These moderators include the difference between social and physical stressors and individual levels of loneliness. Participants were administered measures of loneliness and victimization history, and led to anticipate either a "social" (recorded speech) or "non-social" (pain tolerance test ) stressor, neither of which occurred. EKG and impedance cardiography were measured throughout the session. When anticipating both stressors, loneliness and victimization were associated with increased CO. A regression revealed a three-way interaction, with change in cardiac output depending on victimization history, loneliness, and condition in the physical stressor condition. Loneliness magnified the CO output levels of non-bullied individuals when facing a physical stressor. These results suggest that non- bullied participants high in loneliness are more stressed out when facing stressors, particularly stressors that are physically threatening in nature.
ContributorsHaneline, Magen (Author) / Newman, Matt (Thesis advisor) / Salerno, Jessica (Committee member) / Miller, Paul (Committee member) / Arizona State University (Publisher)
Created2013
Description
School bullying is a serious problem for children and adolescents, associated with a multitude of psychological and behavioral problems. Interventions at the individual level have primarily been social skills training for victims of bullying. However, investigators have had mixed results; finding little change in victimization rates. It has been suggested victims of school bullying have the social skills necessary to be effective in a bullying situation; however they experience intense emotional arousal and negative thoughts leading to an inability to use social skills. One intervention that has been getting increasing acknowledgement for its utility in the intervention literature in psychology is mindfulness. However, there has been no research conducted examining the effects of mindfulness meditation on victims of bullying. Therefore, the purpose of this study was to develop an online intervention for victims of bullying that utilizes the cutting-edge technique of mindfulness and to determine the efficacy of this intervention in the context of bullying victimization. Participants were 32 adolescents ages 11 to 14 identified by their school facilitators as victims of bullying. Repeated measures ANOVAs were used to assess the efficacy of the NMT program versus a treatment as usual (TAU) social skills program. Results revealed significant decreases in victimization and increases in mindfulness among both treatment groups from pre-test to follow-up and post-test to follow-up assessments. There were no differences found between the two treatment groups for mean victimization or mindfulness scores. Overall, the NMT program appears to be a promising online intervention for bullied teens. Directions for future research and limitations of this study were also discussed.
ContributorsYabko, Brandon (Author) / Tracey, Terence J. G. (Thesis advisor) / Homer, Judith (Committee member) / Sebren, Ann (Committee member) / Arizona State University (Publisher)
Created2013
Description
The development of self-regulation is believed to play a crucial role in predicting later psychopathology and is believed to begin in early childhood. The early postpartum period is particularly important in laying the groundwork for later self-regulation as infants' dispositional traits interact with caregivers' co-regulatory behaviors to produce the earliest forms of self-regulation. Moreover, although emerging literature suggests that infants' exposure to maternal stress even before birth may be integral in determining children's self-regulatory capacities, the complex pathways that characterize these developmental processes remain unclear. The current study considers the complex, transactional processes in a high-risk, Mexican American sample. Data were collected from 305 Mexican American infants and their mothers during prenatal, 6- and 12-week home interviews. Mother self-reports of stress were obtained prenatally between 34-37 weeks gestation. Mother reports of infant temperamental negativity and surgency were obtained at 6-weeks as were observed global ratings of maternal sensitivity during a structured peek-a-boo task. Microcoded ratings of infants' engagement orienting and self-comforting behaviors were obtained during the 12-week peek-a-boo task. Study findings suggest that self-comforting and orienting behaviors help to modulate infants' experiences of distress, and also that prenatal stress influences infants' engagement in each of those regulatory behaviors, both directly by influence tendencies to engage in orienting behaviors and indirectly by programming higher levels of infant negativity and surgency, both of which may confer risk for later regulatory disadvantage. Advancing our understandings about the nature of these developmental pathways could have significant implications for targets of early intervention in this high-risk population.
ContributorsLin, Betty (Author) / Crnic, Keith A (Thesis advisor) / Lemery-Chalfant, Kathryn S (Committee member) / Mackinnon, David P (Committee member) / Arizona State University (Publisher)
Created2013
Description
Buildings consume a large portion of the world's energy, but with the integration of phase change materials (PCMs) in building elements this energy cost can be greatly reduced. The addition of PCMs into building elements, however, becomes a challenge to model and analyze how the material actually affects the energy flow and temperatures in the system. This research work presents a comprehensive computer program used to model and analyze PCM embedded wall systems. The use of the finite element method (FEM) provides the tool to analyze the energy flow of these systems. Finite element analysis (FEA) can model the transient analysis of a typical climate cycle along with nonlinear problems, which the addition of PCM causes. The use of phase change materials is also a costly material expense. The initial expense of using PCMs can be compensated by the reduction in energy costs it can provide. Optimization is the tool used to determine the optimal point between adding PCM into a wall and the amount of energy savings that layer will provide. The integration of these two tools into a computer program allows for models to be efficiently created, analyzed and optimized. The program was then used to understand the benefits between two different wall models, a wall with a single layer of PCM or a wall with two different PCM layers. The effect of the PCMs on the inside wall temperature along with the energy flow across the wall are computed. The numerical results show that a multi-layer PCM wall was more energy efficient and cost effective than the single PCM layer wall. A structural analysis was then performed on the optimized designs using ABAQUS v. 6.10 to ensure the structural integrity of the wall was not affected by adding PCM layer(s).
ContributorsStockwell, Amie (Author) / Rajan, Subramaniam D. (Thesis advisor) / Neithalath, Narayanan (Thesis advisor) / Mobasher, Barzin (Committee member) / Arizona State University (Publisher)
Created2013
Description
This study explored the motivation and persistence factors for non-professional athletes who decided after the age of 40 to begin training for an IRONMAN distance triathlon. The qualitative methodology of grounded theory (Strauss & Corbin, 1998) was used in conceptualizing and implementing the research. In-depth interviews were conducted with 10 individuals in the Southwest region of the United States. Data was coded in accordance with grounded theory methods. Motivation themes that emerged from the data centered around either initiating training for triathlon as an approach toward a specific goal or outcome, or beginning triathlon as a way to cope with personal difficulties. Obstacles to motivation also emerged, such as finances and time, injury, fear and doubt, and interpersonal difficulties. Persistence themes emerged that centered around either taking active steps to help continue training and relying on internal traits or characteristics to promote persistence. Data are discussed in terms of how these individuals adopt triathlon as a part of their lifestyle and identity, and how they come to persist in training beyond IRONMAN.
ContributorsLiddell, T. Michael (Author) / Claiborn, Charles (Thesis advisor) / Kinnier, Richard (Committee member) / Margolis, Eric (Committee member) / Arizona State University (Publisher)
Created2013
Description
The purpose of the current study was to use structural equation modeling-based quantitative genetic models to characterize latent genetic and environmental influences on proneness to three discrete negative emotions in middle childhood, according to mother-report, father-report and in-home observation. One primary aim was to test the extent to which covariance among the three emotions could be accounted for by a single, common genetically- and environmentally-influenced negative emotionality factor. A second aim was to examine the extent to which different reporters appeared to be tapping into the same genetically- and environmentally-influenced aspects of each emotion. According to mother- and father-report, moderate to high genetic influences were evident for all emotions, with mother- and father-report of fear and father-report of anger showing the highest heritability. Significant common environmental influences were also found for mother-report of anger and sadness in both univariate and multivariate models. For observed emotion, anger was moderately heritable with no evidence for common environmental variance, but sadness, object fear and social fear all showed modest to moderate common environmental influences and no significant genetic variance. In addition, cholesky decompositions examining genetic and environmental influences across reporter suggested that despite considerable overlap between mother-report and father-report, there was also reporter-specific variance on anger, sadness, and fear. Specifically, there were significant common environmental influences on mother-report of anger- and sadness that were not shared with father-report, and genetic influences on father-report of sadness and fear that were not shared with mother-report. In-home observations were not highly correlated enough with parent-report to support multivariate analysis for any emotion. Finally, according to both mother- and father-report, a single set of genetic and environmental influences was sufficient to account for covariance among all three negative emotions. However, fear was primarily explained by genetic influences not shared with other emotions, and anger also showed considerable emotion-specific genetic variance. In both cases, findings support the value of a more emotion-specific approach to temperament, and highlight the need to consider distinctions as well as commonalities across emotions, reporters and situations.
ContributorsClifford, Sierra (Author) / Lemery, Kathryn (Thesis advisor) / Shiota, Michelle (Committee member) / Eisenberg, Nancy (Committee member) / Arizona State University (Publisher)
Created2013
Description
Culture informs ideas about healthy and acceptable body types. Through globalization the U.S.-European body model has become increasingly significant in local contexts, influencing local body models. While Puerto Ricans have historically valued plump bodies - a biocultural legacy of a historically food scarce environment - this dissertation investigated shifts in these ideals across generations to a stronger preference for thinness. A sample of 23 intergenerational family triads of women, and one close male relative or friend per woman, were administered quantitative questionnaires. Ethnographic interviews were conducted with a sub-sample of women from 16 triads and 1 quintet. Questions about weight history and body sizes were used to address cultural changes in body models. Findings indicate the general trend for all generations has been a reduction in the spectrum of acceptable bodies to an almost singular idealized thin body. Female weight gain during puberty and influence of media produced varied responses across age groups. Overall, Puerto Ricans find it acceptable to gain weight with ageing, during a divorce, and postpartum. Thin bodies are associated with beauty and health, but healthy women that do not resemble the thin ideal, submit themselves to dangerous weight loss practices to achieve self and social acceptance. Further research and direct interventions need to be conducted to alter perceptions that conflate beauty with health in order to address the `normative discontent' women of all ages experience. Weight discrimination and concern with being overweight were evident in Puerto Rican everyday life, indicated by the role of media and acculturation in this study. Anti-fat attitudes were stronger for individuals that identified closely with United States culture. Exposure to drama and personal transformation television programs are associated with increased body image dissatisfaction, and increased exposure to variety shows and celebrity news shows is associated with increased anti-fat attitudes and body dissatisfaction. In sum, the positive valuation of fat in the Puerto Rican cultural body size model in the 1970s has shifted toward a negative valuation of fat and a preference for thin body size.
ContributorsRodriguez-Soto, Isa (Author) / Maupin, Jonathan (Thesis advisor) / Wutich, Amber (Committee member) / Walters-Pacheco, Kattia (Committee member) / Arizona State University (Publisher)
Created2013
Description
Unsaturated soil mechanics is becoming a part of geotechnical engineering practice, particularly in applications to moisture sensitive soils such as expansive and collapsible soils and in geoenvironmental applications. The soil water characteristic curve, which describes the amount of water in a soil versus soil suction, is perhaps the most important soil property function for application of unsaturated soil mechanics. The soil water characteristic curve has been used extensively for estimating unsaturated soil properties, and a number of fitting equations for development of soil water characteristic curves from laboratory data have been proposed by researchers. Although not always mentioned, the underlying assumption of soil water characteristic curve fitting equations is that the soil is sufficiently stiff so that there is no change in total volume of the soil while measuring the soil water characteristic curve in the laboratory, and researchers rarely take volume change of soils into account when generating or using the soil water characteristic curve. Further, there has been little attention to the applied net normal stress during laboratory soil water characteristic curve measurement, and often zero to only token net normal stress is applied. The applied net normal stress also affects the volume change of the specimen during soil suction change. When a soil changes volume in response to suction change, failure to consider the volume change of the soil leads to errors in the estimated air-entry value and the slope of the soil water characteristic curve between the air-entry value and the residual moisture state. Inaccuracies in the soil water characteristic curve may lead to inaccuracies in estimated soil property functions such as unsaturated hydraulic conductivity. A number of researchers have recently recognized the importance of considering soil volume change in soil water characteristic curves. The study of correct methods of soil water characteristic curve measurement and determination considering soil volume change, and impacts on the unsaturated hydraulic conductivity function was of the primary focus of this study. Emphasis was placed upon study of the effect of volume change consideration on soil water characteristic curves, for expansive clays and other high volume change soils. The research involved extensive literature review and laboratory soil water characteristic curve testing on expansive soils. The effect of the initial state of the specimen (i.e. slurry versus compacted) on soil water characteristic curves, with regard to volume change effects, and effect of net normal stress on volume change for determination of these curves, was studied for expansive clays. Hysteresis effects were included in laboratory measurements of soil water characteristic curves as both wetting and drying paths were used. Impacts of soil water characteristic curve volume change considerations on fluid flow computations and associated suction-change induced soil deformations were studied through numerical simulations. The study includes both coupled and uncoupled flow and stress-deformation analyses, demonstrating that the impact of volume change consideration on the soil water characteristic curve and the estimated unsaturated hydraulic conductivity function can be quite substantial for high volume change soils.
ContributorsBani Hashem, Elham (Author) / Houston, Sandra L. (Thesis advisor) / Kavazanjian, Edward (Committee member) / Zapata, Claudia (Committee member) / Arizona State University (Publisher)
Created2013