Analysis of the shapes of diffraction peak profiles (DPPA) is a widely used method for characterising the microstructure of crystalline materials. The DPPA method can be used to determine details about a sample that include, the micro-strain, crystal size or dislocation cell size, dislocation density and arrangement, quantity of planar faults and dislocation slip system population.The main aim of this thesis is to evaluate the use of DPPA in studying the deformation of metals. The alloys studied are uni-axially deformed samples of nickel alloy, nickel-200, 304 and 316 stainless steel alloys and titanium alloys, Ti-6Al-4V and grade 2 CP-titanium.A number of DPPA methods were applied to these metals: a full-width method; a method that attributes size and strain broadening to the Lorentzian and Gaussian integral breadth of a Voigt; different forms of the variance method; the Williamson-Hall method; the alternative method; and variations of the Warren-Averbach method. It is found that in general the parameters calculated using the different methods qualitatively agree with the expectations and differences in the deformation of the different metals. For example, the dislocation density values found for all metals, are approximately the same as would be expected from TEM results on similar alloys. However, the meaning of the results are ambiguous, which makes it difficult to use them to characterise a metal. The most useful value that can be used to describe the state of a metal is the full-width. For a more detailed analysis the Warren-Averbach method in a particular form, the log format fitted to individual Fourier coefficients, is the most useful method.It was found that the shape of different diffraction peaks change in different texture components. These changes were found to be different for the different metals. A method to calculate the shape of diffraction peaks, in different texture components, using a polycrystal plasticity models was investigated. It was found that for FCC metals, the use of a Taylor model was able to qualitatively predict the changes in the shape of diffraction peaks, measured in different texture components. Whereas, for titanium alloys, a model which used the Schmid factor was able to qualitatively explain the changes. The differences in the FCC alloys was attributed to being due to differences in the stacking fault energy of the alloys. For nickel, which develops a heterogeneous cell structure, an additional term describing changes in the crystal size in different orientations is required. The differences between the titanium alloys were shown to be due the presence of twinning in CP-titanium and not in Ti-6Al-4V. This difference was thought to cause an additional broadening due to variations in intergranular strains in twinned and non-twinned regions. The use of polycrystal plasticity models, to explain the shape of diffraction peaks, raises questions as to the validity of some of the fundamental assumptions made in the use of most DPPA methods.

Non-suicidal self-injury (NSSI) is a destructive behaviour engaged in by a large proportion of youth and young adults in current society. Despite previous work, the recent revision of the DSM does not include NSSI as a distinct syndrome; instead it remains in a category for disorders requiring additional research. Thus, in order to better understand the many etiological components underlying NSSI behaviour, still more investigation is required. To this end the current investigations aimed to further elaborate upon known links between NSSI behaviour and parent-child relationships from two perspectives: first, with regard to the overall quality of relationships with parents, and second, with specific focus on the impact of attachment representations of early relationships with parents. Though both perspectives have been investigated in the past, the current studies were developed to alleviate methodological limitations of the existing literature. Study 1 adopted a person-centered approach to examine patterns of perceived relationship quality reported by self-injuring youth based on the combination of multiple relational characteristics; these patterns were then compared with several indices related to different manifestations of NSSI behaviour. Results show heterogeneity in the perceptions of parent-child relationship quality in self-injurers, such that both negative and positive family backgrounds were implicated in the behaviour. Further analyses demonstrate that the level of risk presented by a self-injuring individual can be differentiated based on perceived quality of parent-child relationship. Study 2 investigated how individuals’ internalized states of mind regarding early attachment experiences are related to NSSI, with particular attention dedicated to the relative influences of child maltreatment and attachment representation. Attachment representations reflecting deficits in emotion regulation (preoccupied, unresolved/cannot classify) were most common in self-injurers. Moreover, self-reported childhood maltreatment and attachment states of mind independently contributed to the prediction of NSSI. Lastly, findings suggest that distinct relational influences characteristic of relationships with mothers and fathers are associated with NSSI. The two studies presented here significantly contribute to existing knowledge concerning parental influences in the etiology of NSSI. These investigations add to existing knowledge of NSSI, and may ultimately aid in preventing and treating this damaging behaviour.

Child maltreatment is a pervasive social and public health problem in the United States. The negative effects of child maltreatment can include poor mental and relational health outcomes. The experience of discrimination has been shown to have many of the same mental and relational health difficulties. Child maltreatment and discrimination are both social health problems that disproportionately affect the most marginalized people in our society (people of color, people with disabilities, LGBT individuals). Complex trauma, or the experience of multiple traumas, has been shown to have worse mental and relational health outcomes then experiencing one type of trauma alone. Feminist theory is a useful framework for studying how those with marginalized identities experience the effects of child maltreatment. Feminist theory argues that it is essential to incorporate an analysis of power to truly capture the experience of complex trauma for people with marginalized identities. The effects of child maltreatment and discrimination have been studied individually, however little is known about the effects of experiencing both. Data from the National Survey of Midlife Development in the United States (MIDUS) biomarker project was used to examine the effect of experiencing both child maltreatment and discrimination. Latent profile analysis was used to create distinct profiles of trauma out of child maltreatment variables and discrimination. A four profile solution was determined to be the best fitting model. The profiles were Low Trauma, Child Maltreatment/Discrimination, Child Maltreatment and Child Maltreatment/ Discrimination High. Analysis of co-variance was then used to determine how each profile of trauma was related to anxiety, depression, family support and family strain. Differences were found among the profiles and the mental health and relational outcomes. Results and clinical implications are discussed.

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Thesis advisor: Scott C. Seider / Engagement in sociopolitical activism, such as protesting, has important implications for youth of color and for the communities in which they live (Ballard & Ozer, 2016; Ginwright, 2010; Hope & Spencer, 2017). Critical Consciousness (CC; Freire, 1970/1998; Watts et al., 2011) and Youth Sociopolitical Development Theory (Youth SPD; Watts & Flanagan, 2007) are two prominent frameworks for investigating sociopolitical activism among youth of color. Although both frameworks position motivation as one of the key factors influencing youth activism, motivation is narrowly defined as a single construct—one’s sense of efficacy to effect change. Using motivation constructs from two established motivation frameworks, Self-Determination Theory (SDT; Deci & Ryan, 2008; Ryan & Deci, 2000) and Regulatory Focus Theory (RFT; Higgins, 1997), this dissertation investigated the multidimensional nature of motivation in relation to Black and Latinx adolescents’ commitment to activism. Drawing from a longitudinal data set examining Black and Latinx adolescents’ civic development over four years of high school (N = 733), I used group differential approaches (latent profile analysis, latent profile transition analysis, and latent profile moderation) to (a) identify distinct combinations of motivations among Black and Latinx high school students in ninth, tenth, and twelfth grade, (b) assess whether and the extent to which adolescents changed profile membership across high school, (c) examine motivation profiles in tenth grade as predictors of commitment to activism in twelfth grade, and (d) examine motivation profiles in tenth grade as moderators of the relation between adolescents’ analysis of social problems in tenth grade and their commitment to activism addressing these problems in twelfth grade (controlling for their initial commitment to activism). I identified two motivation profiles in ninth grade, four motivation profiles in tenth grade, and four motivation profiles in twelfth grade. At both tenth and twelfth grade, I named the motivation profiles: “Low Motivation,” “High Motivation,” “Moderate Motivation, Low Autonomy,” and “Moderate Motivation, High Autonomy.” At both time points, the “Low Motivation” profile comprised the smallest proportion of the sample and the “Moderate Motivation, High Autonomy” profile comprised the largest proportion of the sample. Most youth shifted to a different motivation profile over time. Adolescents in the “High Motivation” profile at the end of tenth grade reported the highest average commitment to activism at the end of twelfth grade; however, this number was only statistically significantly higher than the “Moderate Motivation, Low Autonomy” profile. Contrary to expectations, youths’ social analysis in tenth grade was not predictive of their commitment to activism in twelfth grade; thus, there was no latent profile moderation in relation to social analysis and commitment to activism. Instead, I did find evidence that motivation profile membership moderated the relation between commitment to activism at the end of tenth grade on commitment to activism at the end of twelfth grade. Overall, results suggest that adolescents’ motivation is multidimensional and incredibly dynamic. Future CC/Youth SPD research should consider investigating a more complete set of established motivation constructs in relation to youths’ sociopolitical development. / Thesis (PhD) — Boston College, 2022. / Submitted to: Boston College. Lynch School of Education. / Discipline: Counseling, Developmental and Educational Psychology.

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There is a particularly robust relation between neighborhood disadvantage and youth conduct problems. Given conduct problems are heterogeneous, it is likely that distinct subgroups of youth who differ in conduct problems and related correlates may be identifiable. The present study identified profiles of youth from a low-income, urban community participating in the Coping Power Program. Profiles were characterized by teacher-reported psychosocial and behavioral functioning assessed at pre-intervention among a sample of 61 fourth-grade students (98% Black/African American; M age = 9.87 ± 0.50; 58.3% female). Auxiliary analyses investigated whether and how these profiles differ on concurrent child-reported conduct problems and contextual (i.e., neighborhood, peer) factors and whether profile membership was associated with post-intervention teacher-reported outcomes. Latent profile analysis identified four profiles: (1) Moderate Conduct Problems (Mod CP; n = 6); (2) Moderate Conduct Problems/Callous-Unemotional Behavior with Moderate Peer Victimization (Mod CP/CU+Mod PV; n = 9); (3) High Conduct Problems/Callous-Unemotional Behavior with Low Prosocial Behavior (High CP/CU+Low Pro; n = 7); and Typically Developing (TD; n = 37). Profiles differed on child-reported outcome expectations for aggressive behavior, such that Mod CP/CU+Mod PV and High CP/CU+Low Pro were more likely to expect aggression to reduce aversive treatment from others. The High CP/CU+Low Pro profile had the most consistent post-intervention improvement across outcomes, though profile responsiveness to the intervention was variable and differed based on how outcomes were operationalized. Findings inform identification of youth from low-income, urban communities who may be at risk for negative outcomes and/or more amenable to preventive interventions for conduct problems. / Psychology

abstract: Drawing upon the theoretical framework of Cooley’s (1902) “looking-glass self” model, the current study examined how affective dimensions of parenting in adolescence contribute to psychopathology in early adulthood through the mediating mechanism of authenticity – one’s level of comfort with being oneself. Using latent profile analysis (LPA), a three-class solution was identified, classifying inadequate, adequate, and optimal profiles of parenting in adolescence. Class membership was used in a multilevel mediation structural equation model to examine longitudinal links with authenticity and psychopathology (e.g., internalizing, externalizing, and substance abuse disorders) in early adulthood. Results demonstrated that optimal compared to inadequate parent-adolescent relationship quality was directly linked to higher levels of authenticity, which in turn, was directly linked to lower levels of all forms of psychopathology in early adulthood. Results also indicated that authenticity fully mediated the link between profiles of parent-adolescent relationship quality (e.g., grade 12) and internalizing, externalizing, and substance abuse disorders in early adulthood (e.g., four years post-college). In conclusion, the current study demonstrated the influence of affective dimensions of parenting profiles in adolescence on the development of psychopathology in early adulthood via the mediating mechanism of authenticity. Moreover, findings from the current study suggest that authenticity is a critical feature shared in common among various forms of psychopathology. Finally, clinical implications are discussed regarding the potential effectiveness of evidence-based psychotherapies aimed at the promotion of authenticity as a mechanism for improving mental health and well-being. / Dissertation/Thesis / Doctoral Dissertation Psychology 2021