Thesis project (D. Min.)--Denver Seminary, 2004. / Includes bibliographical references (leaves 220-229).

Thesis (Ph. D.)--University of North Carolina at Greensboro, 2007. / Title from PDF title page screen. Advisor: Judith A. Niemeyer; submitted to the School of Education. Includes bibliographical references (p. 147-161).

Thesis (M.A.)--University of North Carolina at Greensboro, 2007. / Title from PDF title page screen. Advisor: Arthur D. Anastopoulos; submitted to the Dept. of Psychology. Includes bibliographical references (p. 41-50).

Thesis PlanB (M.S.)--University of Wisconsin--Stout, 2006. / Includes bibliographical references.

Thesis (doctoral)--La Salle University, 2005. / ProQuest dissertations and theses ; AAT 3227738. Includes bibliographical references (leaves 33-46)

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2009. / Title from title screen (site viewed October 15, 2009). PDF text: v, 121 p. : col. ill. ; 531 Kb. UMI publication number: AAT 3369352. Includes bibliographical references. Also available in microfilm and microfiche formats.

Neste trabalho investigamos as propriedade estatísticas de um modelo de coevolução de N espécies, sob a perspectiva da dinâmica de replicadores. As interações entre pares de espécies são dadas por variáveis aleatórias independentes, fixas no tempo. As interações são também simétricas, de modo que a dinâmica maximiza uma função de Lyapunov (o funcional adaptabilidade). Isto permite usar as técnicas da mecânica estatística de sistemas desordenados para determinar analiticamente as propriedades estatísticas dos estados estacionários, particularmente a diversidade de espécies (total de espécies coexistindo em um sistema ecológico). As auto-interações são iguais a um parâmetro de controle que mede a competição entre indivíduos de uma mesma espécie (competição intraespecífica). A cada espécie associamos um conjunto de p traços ou características, representados por variáveis binárias aleatórias distribuídas com igual probabilidade. As forças de interação são dadas por funções não lineares da regra de Hebb. Estas são funções moduladoras do número de elementos complementares entre os conjuntos de traços de um dado par de espécies. Estudamos analítica e numericamente o caso em que p é proporcional ao total de espécies na comunidade, via método de réplicas. A análise é possível devido ao resultado de Sompolinsky: funções não lineares da regra de Hebb são equivalentes, no limite de p extensivo, a regra de Hebb somada a um ruído gaussiano estático, cuja variância depende da forma da função moduladora. A competição intraespecífica, o total de traços, a presença de espécies altamente complementares e finalmente o peso dos termos de competição interespecífica (elementos não diagonais da matriz de acoplamentos) são as principais influências sobre o comportamento das grandezas termodinâmicas no equilíbrio, principalmente a diversidade. Os resultados analíticos concordam com a solução numérica da equação de replicadores, no regime em que as soluções de réplicas simétricas são estáveis. / We investigate the statistical properties of a coevolution model of N species using the replicator dynamics framework. The pairwise species interactions are given by independent quenched random variables. They are also symmetric, so that the dynamics maximizes a quadratic Lyapunov function (the fitness functional). This allows the use of tools of statistical mechanics of disordered systems to analyze the statistical properties of the equilibrium states, especially the ecosystem diversity (total number of coexisting species in an ecological system). The self-interactions are equal to a control parameter measuring the intraspecies competition. We associate to each species a set of p traits and represent them by independent random variables, equally distributed. The strength of the pairwise interactions is given by nonlinear functions of the Hebb rule. These are modulating functions of the number of complementary elements in the sets of traits of a given species pair. We study analytically and numerically the limit of extensive p, using the replica trick. The analytical approach is possible due to a result derived by Sompolinsky: in the limit of extensive p, nonlinear functions of the Hebb rule are equivalent to the Hebb rule plus a Gaussian static noise, whose variance is dependent on the form of the modulating function. The intraspecies competition, the total number of traits, the presence of highly complementary species pairs and the contribution of the nondiagonal elements of the interaction matrix are the main influences over the behavior of the equilibrium properties, principally the diversity. Our analytical results agree with the numerical solutions of the replicator equation in the regime of stable replica symmetric solutions.

Estudamos o efeito do campo aleatório sobre um modelo de vidro de spin com interações de p spins de alcance infinito e distribuição de probabilidade gaussiana. O caso p = 2 corresponde ao modelo de Sherrington-Kirkpatrick na presença de um campo aleatório. O caso p \'SETA\' \'INFINITO\' corresponde ao REM (Random Energy Model) de Derrida na presença de um campo aleatório. Além da interação de p spins, consideramos a presença de interações uniformes ferro ou antiferromagnéticas de alcance infinito. Tanto no caso ferro quanto antiferromagnético, empregamos dois procedimentos para tratar o problema: o método de réplicas no ensemble canônico e o método da contagem de estados no ensemble microcanônico. No método de réplicas resolvemos o problema para qualquer valor de p tanto sem quebra da simetria de permutação entre réplicas, quanto com um passo de quebra de simetria de Parisi. Deste modo, recuperamos resultados conhecidos para alguns modelos já estudados na literatura. Em seguida, tomamos o limite p \'SETA\' \'INFINITO\' que fornece uma solução completa para o problema do REM na presença de um campo aleatório. No método da contagem de estados, aplicável apenas no limite p \'SETA\' \'INFINITO\', mostramos que podemos estender a solução de Derrida mesmo na presença de um campo aleatório. Isso nos permitiu fazer a contagem de estados evitando assim o problema da \"catástrofe da entropia negativa\" presenta na solução réplica simétrica. Além disso, mostramos que qualquer sistema que seja solúvel sem a interação aleatória de p spins continua solúvel na presença dessa interação no limite p \'SETA\' \'INFINITO\'. Portanto, concluímos que a interação aleatória de p spins é somente adicionar um carácter vidro de spin ao sistema. Obtivemos expressões gerais válidas para qualquer distribuição do campo aleatório, embora a análise numérica tenha sido restrita às distribuições duplo-delta e gaussiana. Estudamos a influência do campo aleatório sobre os diagramas de fases e, em particular, mostramos que podem surgir pontos tricríticos no caso de uma distribuição duplo-delta. / We studied the effect of a random field on spin-glass models with infinite-ranged p spin interactions with a Gaussian probability distribution. The case p = 2 corresponds to the Sherrington-Kirkpatrick model in the presence of a random field. The case p \'SETA\' \'INFINITO\' corresponds to the REM (Random Energy Model) introduced by Derrida in the presence of a random field. Besides the p-spin interactions we also included uniform infinite-ranged ferromagnetic and antiferromagnetic interactions. Both in the case of ferromagnetic and antiferromagnetic interactions we employed two different approaches: The replica method in the canonical ensemble and the method of counting of the states in the microcanonical ensemble. In the replica method we solved the problem for arbitrary p both in the case of replica symmetry and in the first step of Parisi\'s replica-symmetry breaking scheme. This allowed us to rederive results for some models already known in the Literature. Next we took the limit p \'SETA\' \'INFINITO\' which yielded a complete solution to the REM in a random field. In the method of counting of the states, which is effective only in the limit p \'SETA\' \'INFINITO\', we showed that we can extend the Derrida\'s solution even in the presence of a random field. This allowed us to do the counting of the states avoiding the so called negative-entropy catastrophe present in the replica-symmetric solution. We also showed that any solvable model without random p-spin interactions is also solvable in the presence of such interactions in the limit p \'SETA\' \'INFINITO\'. Therefore, we conclude that the p-spin random interactions only add a spin-glass character to the system. We have obtained general expressions valid for any random-field distributions, although we limited the numerical analysis to double-delta and Gaussian distributions. We studied the effects of the random field on the phase diagrams, and in particular, we showed the possibility of tricritical point in the case of double-delta distributions.

Both theory and research implicate appearance comparison processes in the development of body image disturbance and disordered eating. Although several measures of appearance comparison exist, each has significant limitations. The Physical Appearance Comparison Scale-Revised (PACS-R) and its earlier versions are measures designed to assess the frequency of appearance comparisons among men and women. In the current study, the PACS-R was revised to (a) examine comparisons of weight/shape, muscularity, and overall physical appearance, (b) include items to assess comparisons with distal targets, (c) provide an assessment of upward versus downward comparisons, and (d) provide an assessment of the acute emotional impact of comparisons. The psychometric properties of the newly revised measure, labeled the PACS-3, were then examined in a college sample. The PACS-3 was administered to 1,533 college men and women, along with existing measures of appearance comparison, body satisfaction, eating pathology, and self-esteem. In Study 1, exploratory factor analysis was conducted to examine the factor structure of the PACS-3. In Study 2, confirmatory factor analysis was conducted to verify the resulting factor structure. In addition, the internal consistency, convergent validity, incremental validity, and two-week test-retest reliability of PACS-3 scores were examined. The final PACS-3 is comprised of 27 items and nine subscales: Frequency: Proximal, Frequency: Distal, Frequency: Muscular, Direction: Proximal, Direction: Distal, Direction: Muscular, Effect: Proximal, Effect: Distal, Effect: Muscular. PACS-3 subscale scores demonstrated good reliability and convergent validity. Moreover, PACS-3 subscales improved the prediction of body satisfaction and disordered eating relative to existing measures of appearance comparison, supporting the incremental validity of the scale. Future research may seek to examine the psychometric properties of the scale in more diverse samples, as well as associations between the PACS-3 and additional theoretically related constructs (e.g., drive for muscularity).

This study explores the potential relationship between disordered eating and appearance-related possible selves. The sample consisted of 293 female college students (mean age=22). Participants were administered interviews consisting of demographic information, the Possible Selves Interview, the Eating Attitudes Test-26, The Physical Self Description Questionnaire, and the Rosenberg Self-Esteem Scale. More than half of the participants reported an appearance-related possible self (n=154). As expected, disordered eating scores were found to be higher for participants who reported an appearance-related possible self: t(288)=-3.04, p