There is a well-established link between peer victimization and social anxiety disorder (SAD). Additionally, rates of bullying are significantly higher in obese compared to normal-weight individuals. However, social anxiety (SA) has not yet been examined in the context of weight, weight bias, and social rejection. This study examined the relationship between SA and weight in undergraduate women (N = 186). It aimed to determine whether implicit weight bias moderated the relationship between body mass index (BMI) and SA. In addition, it explored the interactive effects of SA, BMI, and body image salience on emotional response to exclusion in a social ostracism paradigm (Cyberball). Participants answered questions pertaining to SA and stigmatizing attitudes toward overweight/obesity and completed an implicit association test about weight. One week later, they played Cyberball, completing state measures of affect before and after the game. Although rates of clinically elevated SA did not differ significantly across normal-weight, overweight, and obese women, implicit weight bias did moderate the relationship between BMI and SA. The 3-way interaction of BMI, SA, and body image salience did not significantly predict post-exclusion state measures. However, body image salience moderated the relationship between SA and post-exclusion anxiety as well as between BMI and post-exclusion anxiety. Findings from this study shed light on the role of body weight in the experience of SA. Results suggest that higher BMI is associated with higher SA for those with high, but not low implicit weight bias. In addition, individuals with elevated SA are particularly reactive to exclusion if their bodies are visible to others. / Psychology

Low health literacy in the United States has numerous negative impacts on health outcomes. Efforts to equip physicians with the ability to better identify patients with low health literacy have consistently shown lackluster and transient results. The transient nature of these results closely mirror those seen in the implicit bias literature, implying that health literacy may be better addressed if considered a type of coded bias among clinicians. In this paper, a review of the literature is presented which includes the impact of health literacy on patient outcomes, physician understanding and ability to screen for low health literacy, past interventions aimed at improving physician ability to identify and assist low health literacy patients, and the existing literature involving implicit bias among physicians. This review allows for the argument that interventions aimed at helping physicians better identify low health literacy patients would be more effective if designed to address unconscious biases rather than a knowledge deficit. Finally, the ethical imperative to address these biases in the healthcare setting is described. / Urban Bioethics

Most efforts to identify juror bias rely on explicit measures, which have been subject to criticisms concerning validity. The following studies attempt to better understand juror bias through the use of an indirect measure, the Single Category Implicit Association Test (SC-IAT). The goal of these studies was to investigate whether jurors have implicit biases regarding the guilt or innocence of a defendant, even before trial begins. Also, to investigate whether this bias varies as a result of extra-legal factors, such as defendant race and juror race. A final goal was to investigate the predictive validity of the indirect measure of guilt bias, with regard to juror decision-making and verdicts. Results from the following studies demonstrate that participants do have significant implicit guilt biases before a trial, and these biases vary based on participant race and defendant race. Furthermore, pre-trial implicit bias is a good predictor of juror decision-making. The implications of implicit biases on the legal system and ideas for future research are discussed. / Psychology

Surveys and a brief-interval longitudinal design were employed to investigate the relationships between selected proactive leader influence behaviors (PLIBs) and followers' commitment to their leaders. Selected elements of followers' implicit leadership theories (ILTs) were expected to moderate the PLIBs – commitment relationships. Hypotheses were generated and tested in order to determine the extent to which (1) PLIBs constituted group-level phenomena and (2) PLIBs and ILTs were related to follower commitment. Empirical evidence did not support treating PLIBs as group-level variables. While PLIBs were related to commitment, hypotheses specifying ILT dimensions as moderators of the PLIB – commitment relationships were not supported. / Ph. D.

Mathematical models involving ordinary differential equations (ODEs) play a critical role in scientific and engineering applications. Advances in computing hardware and numerical methods have allowed these models to become larger and more sophisticated. Increasingly, problems can be described as multiphysics and multiscale as they combine several different physical processes with different characteristics. If just one part of an ODE is stiff, nonlinear, chaotic, or rapidly-evolving, this can force an expensive method or a small timestep to be used. A method which applies a discretization and timestep uniformly across a multiphysics problem poorly utilizes computational resources and can be prohibitively expensive. The focus of this dissertation is on "multimethods" which apply different methods to different partitions of an ODE. Well-designed multimethods can drastically reduce the computation costs by matching methods to the individual characteristics of each partition while making minimal concessions to stability and accuracy. However, they are not without their limitations. High order methods are difficult to derive and may suffer from order reduction. Also, the stability of multimethods is difficult to characterize and analyze. The goals of this work are to develop new, practical multimethods and to address these issues. First, new implicit multirate Runge–Kutta methods are analyzed with a special focus on stability. This is extended into implicit multirate infinitesimal methods. We introduce approaches for constructing implicit-explicit methods based on Runge–Kutta and general linear methods. Finally, some unique applications of multimethods are considered including using surrogate models to accelerate Runge–Kutta methods and eliminating order reduction on linear ODEs with time-dependent forcing. / Doctor of Philosophy / Almost all time-dependent physical phenomena can be effectively described via ordinary differential equations. This includes chemical reactions, the motion of a pendulum, the propagation of an electric signal through a circuit, and fluid dynamics. In general, it is not possible to find closed-form solutions to differential equations. Instead, time integration methods can be employed to numerically approximate the solution through an iterative procedure. Time integration methods are of great practical interest to scientific and engineering applications because computational modeling is often much cheaper and more flexible than constructing physical models for testing. Large-scale, complex systems frequently combine several coupled processes with vastly different characteristics. Consider a car where the tires spin at several hundred revolutions per minute, while the suspension has oscillatory dynamics that is orders of magnitude slower. The brake pads undergo periods of slow cooling, then sudden, rapid heating. When using a time integration scheme for such a simulation, the fastest dynamics require an expensive and small timestep that is applied globally across all aspects of the simulation. In turn, an unnecessarily large amount of work is done to resolve the slow dynamics. The goal of this dissertation is to explore new "multimethods" for solving differential equations where a single time integration method using a single, global timestep is inadequate. Multimethods combine together existing time integration schemes in a way that is better tailored to the properties of the problem while maintaining desirable accuracy and stability properties. This work seeks to overcome limitations on current multimethods, further the understanding of their stability, present new applications, and most importantly, develop methods with improved efficiency.

The purpose of the present study was to investigate whether personal attributes are consistently associated with the emergence of leaders in small groups. Past research on leadership emergence has frequently examined the relationships between individual personal attributes and perceptions of leadership by group members following completion of a single group exercise. The present study extends the literature by taking a multivariate approach to the study of leadership perceptions, by varying group tasks and group membership, and by implementing both perceptual methods of measurement and direct measurement of leadership behavior. One hundred seventy-three undergraduate students participated in small groups to complete two tasks. Participants worked with different group members during each task. The first task emphasized competition and persuasion among group members and the second task emphasized cooperation and information sharing among group members. Following each task, group members rated and ranked all group members on leadership attributes and abilities. Trained observers then coded each of the leader behaviors that occurred during the group interactions and assigned their own objective leadership ranks to the group members. Multiple regression, discriminant analysis, and bivariate correlations revealed that dominance and intelligence were consistently related to both perceptions of leadership by group members and objective observation and coding of leadership behaviors. In addition, perceptions of leadership by group members were found to be related to objective behavioral indices of leadership; thus, a link was created between perceptual and behavioral measures of leadership. In addition, group members who were perceived as possessing prototypical leader traits were consistently identified as the group leaders by group members and trained observers. Implications of the present Study’s results and suggestions for future research in the field of leadership are discussed. / Ph. D.

The purpose of the following study was to investigate the role of interpersonal congruence between leaders' and followers' implicit theories of leadership (ILTs) and followership (IFTs) in both partners' perspectives of the leader-follower relationship. While most literature focuses on assessments of the leader-member exchange (LMX) relationship, this study examined perceived support, identification with one's partner, and contribution to the relationship, in addition to LMX. Congruence between self-views and interpersonal congruence on implicit theories was examined as moderators of these relationships, such that the strength of these relationships was predicted to increase as self-views aligned more highly with implicit theories. Data from 103 independent pairs of full-time working adults (across an organizational sample as well as varied workforce snowball sample) were analyzed using eight manifest path models. Leader ILT -- follower ILT congruence significantly and positive predicted leader-rated LMX and perceived support, but not identification and contribution. Leader IFT -- follower IFT congruence significantly and positive predicted follower-rated LMX and perceived support, but not identification and contribution. The results of this study suggest expectations are meaningful predictors of both partner's assessments of multiple relationship-oriented outcome variables, but only with regard to perceptions of outcomes from the perspective of one's dyadic partner. / Ph. D.

Implicit theories are frameworks that allow an individual to conceptualize the world (Levy, Chiu, & Hong, 2006; Plaks, Levy, & Dweck, 2009). Incremental implicit theories assert humans as dynamic entities, capable of change, whereas entity implicit theories assert that humans are rigid, static, and incapable of change (Dweck, 1999). The present study examined entity and incremental themes in parent child discourse about weight related health decisions. Incremental themes are expected to be related to better pediatric health outcomes (BMI, physical activity, diet, and body image). A moderation model is proposed whereby links between parent child discourse and pediatric health outcomes, specifically body image, will be stronger for boys than girls. Moderation by sex was expected because parents may communicate differently to their children as a function of sex. Cultural ideals have much more stringent evaluations of women than men do and this may be reflected in communications involving parents and children. There were no significant mean-level differences in body image scores and parents' use of entity and incremental themes according to child sex. Additionally, parents use of entity and incremental themes did not predict any of the children's health-related outcomes. These results may indicate that child sex may not be the best predictor of parents' communications concerning children's weight-related decisions. / Master of Science

Yes / Large amount of sediment deposits in the reservoir area can cause dam break, which not only leads to an immeasurable loss to the society, but also the sediments from the reservoir can be transported to generate further problems in the downstream catchment. This study aims to investigate the short-to-long term sediment transport and channel meandering process under such a situation. A coupled explicit-implicit technique based on the Euler-Lagrangian method (ELM) is used to solve the hydrodynamic equations, in which both the small and large time steps are used separately for the fluid and sediment marching. The main feature of the model is the use of the Characteristic-Based Split (CBS) method for the local time step iteration to correct the ELM traced lines. Based on the solved flow field, a standard Total Variation Diminishing (TVD) finite volume scheme is applied to solve the sediment transportation equation. The proposed model is first validated by a benchmark dambreak water flow experiment to validate the efficiency and accuracy of ELM modelling capability. Then an idealized engineering dambreak flow is used to investigate the long-term downstream channel meandering process with nonuniform sediment transport. The results showed that both the hydrodynamic and morphologic features have been well predicted by the proposed coupled model. / This research work is supported by Sichuan Science and Technology Support Plan (2014SZ0163), Start-up Grant for the Young Teachers of Sichuan University (2014SCU11056), and Open Research Fund of the State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University (SKLH 1409; 1512).

Many fields in science and engineering require large-scale numerical simulations of complex systems described by differential equations. These systems are typically multi-physics (they are driven by multiple interacting physical processes) and multiscale (the dynamics takes place on vastly different spatial and temporal scales). Numerical solution of such systems is highly challenging due to the dimension of the resulting discrete problem, and to the complexity that comes from incorporating multiple interacting components with different characteristics. The main contributions of this dissertation are the creation of new families of time integration methods for multiscale and multiphysics simulations, and the development of industrial-strengh tools for sensitivity analysis. This work develops novel implicit-explicit (IMEX) general linear time integration methods for multiphysics and multiscale simulations typically involving both stiff and non-stiff components. In an IMEX approach, one uses an implicit scheme for the stiff components and an explicit scheme for the non-stiff components such that the combined method has the desired stability and accuracy properties. Practical schemes with favorable properties, such as maximized stability, high efficiency, and no order reduction, are constructed and applied in extensive numerical experiments to validate the theoretical findings and to demonstrate their advantages. Approximate matrix factorization (AMF) technique exploits the structure of the Jacobian of the implicit parts, which may lead to further efficiency improvement of IMEX schemes. We have explored the application of AMF within some high order IMEX Runge-Kutta schemes in order to achieve high efficiency. Sensitivity analysis gives quantitative information about the changes in a dynamical model outputs caused by caused by small changes in the model inputs. This information is crucial for data assimilation, model-constrained optimization, inverse problems, and uncertainty quantification. We develop a high performance software package for sensitivity analysis in the context of stiff and nonstiff ordinary differential equations. Efficiency is demonstrated by direct comparisons against existing state-of-art software on a variety of test problems. / Ph. D.