The Irrational Beliefs Inventory (IBI) was built to measure self-defeating beliefs as conceptualized in Rational-Emotive Behavior Therapy. The IBI has five factors: worrying, rigidity, problem avoidance, need for approval, and emotional irresponsibility. A three-phase cross-cultural study was conducted to translate and adapt the IBI from English to Icelandic, and a Confirmatory Factor Analysis (CFA) approach was used for a test of factorial validity and cross-cultural invariance. In Phase 1, the IBI was translated from English to Icelandic, using a forward-translation and back-translation. Two forward-translators and two back-translators were recruited. In Phase 2, qualitative interview methods were used in both the U.S. and Iceland to gain insights into the meaning of the items on the IBI. In the U.S., 21 university students provided insights in a group discussion, and four students were individually interviewed in depth about individual items on the IBI. In Iceland, four university students were interviewed in depth about the meaning of individual items. Three Icelandic psychology professionals were recruited to evaluate the appropriateness of the IBI for the Icelandic culture. In Phase 3, a Confirmatory Factor Analysis (CFA) was conducted to check factorial validity and cross-cultural invariance of the IBI. The total sample size in Phase 3 was N=1547, all college students, with n=827 in the U.S. and n=720 in Iceland. Overall, the CFA did not support the fit of the IBI's original five-factor model, although the fit was slightly better in the Icelandic version. Fit indices conflicted; the chi-square and comparative fit index (CFI) showed poor fit, while the RMSEA and SRMR showed acceptable fit. Correlated error was found between 85 item pairs in the U.S. model, and between 68 item pairs in the Icelandic model. Modifications were attempted to the original model by including the correlated errors, and a multigroup CFA was conducted. Adding the correlated errors slightly improved the fit of both models, but only 11 out of the IBI's 50 items were found to have equivalent item factor loadings and intercepts between the countries. Results from the psychometric analysis and qualitative interviews indicated that the IBI needs to be rewritten if the measure is to be used for research in Iceland. The results were discussed in light of a recent analysis of REBT-based measurement instruments, and implications for cross-cultural research on highly abstract constructs such as irrationality were discussed.

The Study Anxiety Inventory (SAI), consisting of the factors of worry and emotionality, was developed to measure college students' self-reported levels of anxiety while studying for an exam. Data from 2002 undergraduate students from four colleges (Arts and Sciences, Engineering, Business, and Education) at a southeastern state university were used to evaluate the validity of the scores from the 16-item Study Anxiety Inventory. Results of confirmatory factor analyses for the two factor model, conducted separately for each college, indicated marginally acceptable fit for the data (median fit measures across the four colleges: CFI =.915, SRMR=.049, RMSEA=.098), a pattern that was repeated for both males and females. Multigroup CFA was used to evaluate the factorial invariance of the SAI across gender within each college. Factor loadings (i.e., pattern coefficients) for the SAI items were not found to be significantly different between males and females (p > .05). Error variances for four items were found to be significantly different between males and females, indicating that there may be some difference in scale reliability by gender. Factor covariances were invariant for all four colleges (p > .05) and factor variances were invariant for all but the worry component for the College of Arts and Sciences where females had significantly greater variability on the worry factor. As was hypothesized, the SAI scores were positively correlated with scores on measures of test anxiety (median r=.74), trait anxiety (median r=.46), active procrastination (median r=.23), and passive procrastination (median r=.29), but negatively correlated with trait curiosity (median r=-.19). Contrary to what was hypothesized, no relationship was demonstrated between study anxiety and study skills and habits (median r=-.03). The nomological network was extended in this study by examining relationships between scores obtained from students on the SAI and measures of active and passive procrastination. This is the first study that systematically examines the factorial invariance of the SAI by gender, which is important because previous research using the SAI has shown men's scores to be consistently lower than women's scores. The results obtained in the current study provide support for gender invariance in a nonclinical population in the situation specific level of anxiety while studying. There is sufficient evidence of validity and reliability (median Cronbach alphas for males and females for the total score were .978 and .980, for worry were .968 and .973, and for emotionality were .947 and .951, respectively) that a researcher should feel confident that the SAI is a psychometrically sound research tool that holds up fairly well across a number of different types of students and that making mean comparisons on the SAI by gender is acceptable.

In the doctoral dissertation, we consider problems of testing and estimating changed segment with unknown starting position and duration of epidemic state in the autoregressive first-order model. The proposed tests are based on partial sums of model residuals and model-parameter partial-estimator polygonal line processes. We derive asymptotic results for these processes in Holder spaces. The behavior of test statistics under the null hypothesis of no change and alternative is provided. Empirical power analysis has shown that tests are more powerful when absolute values of model parameter are quite large or autoregressive process changes from a stationary state to a nonstationary one. We prove the consistency of the least square changed-segment estimators and provide their convergence rates. / Disertacijoje nagrinėjamas pirmos eilės autoregresinio modelio pasikeitusio segmento testavimo ir vertinimo uždavinys. Aprašomo modelio epideminio pasikeitimo pradžia ir ilgis nėra žinomi. Pasiūlyti kriterijai pasikeitusio segmento testavimui, kurie pagrįsti modelio paklaidų įvertinių dalinių sumų ir modelio parametro dalinių įvertinių laužčių procesais. Šiems procesams gautos ribinės teoremos Hiolderio erdvėse. Nurodomas testų statistikų ribinis elgesys esant teisingai nulinei ir alternatyviajai hipotezėms. Iš empirinio kriterijų galios tyrimo rezultatų matyti, kad pasiūlytų testų galia didžiausia aptinkant pasikeitimus iš stacionarios būklės į nestacionarią arba esant artimoms vienetui modelio parametro reikšmėms. Taip pat įrodoma, kad mažiausių kvadratų metodu gauti pasikeitusio segmento pradžios ir ilgio įverčiai bei autoregresinio modelio su pasikeitusiu segmentu parametrų įverčiai yra suderintieji bei pateikiamas jų konvergavimo greitis.

Disertacijoje nagrinėjamas pirmos eilės autoregresinio modelio pasikeitusio segmento testavimo ir vertinimo uždavinys. Aprašomo modelio epideminio pasikeitimo pradžia ir ilgis nėra žinomi. Pasiūlyti kriterijai pasikeitusio segmento testavimui, kurie pagrįsti modelio paklaidų įvertinių dalinių sumų ir modelio parametro dalinių įvertinių laužčių procesais. Šiems procesams gautos ribinės teoremos Hiolderio erdvėse. Nurodomas testų statistikų ribinis elgesys esant teisingai nulinei ir alternatyviajai hipotezėms. Iš empirinio kriterijų galios tyrimo rezultatų matyti, kad pasiūlytų testų galia didžiausia aptinkant pasikeitimus iš stacionarios būklės į nestacionarią arba esant artimoms vienetui modelio parametro reikšmėms. Taip pat įrodoma, kad mažiausių kvadratų metodu gauti pasikeitusio segmento pradžios ir ilgio įverčiai bei autoregresinio modelio su pasikeitusiu segmentu parametrų įverčiai yra suderintieji bei pateikiamas jų konvergavimo greitis. / In the doctoral dissertation, we consider problems of testing and estimating changed segment with unknown starting position and duration of epidemic state in the autoregressive first-order model. The proposed tests are based on partial sums of model residuals and model-parameter partial-estimator polygonal line processes. We derive asymptotic results for these processes in Holder spaces. The behavior of test statistics under the null hypothesis of no change and alternative is provided. Empirical power analysis has shown that tests are more powerful when absolute values of model parameter are quite large or autoregressive process changes from a stationary state to a nonstationary one. We prove the consistency of the least square changed-segment estimators and provide their convergence rates.

Pour les systèmes de commande sous la forme de dx/dt = f (x, u), dans la littérature, les chercheurs s'intéressaient à la stabilisation de ce système de différentes manières : asymptotique, uniformément asymptotique, partielle, en temps fini, etc. Pour aboutir à ces résultats, les méthodes utilisées font appel aux techniques suivantes : Lyapunov, Lasalle, Barbalat, surface glissante, etc. Dans cette thèse, nous nous sommes intéressés à une autre fonctionnalité de la commande, dite commande répulsive stabilisante. Les résultats ont été généralisés au cas d'un système avec dérive et sans dérive. Comme résultat, l'approche de commande qu'on propose assure la stabilité du système autour d'une position désirée et la répulsion de celui-ci par rapport à un ensemble indésirable, construit dans l'espace de navigation. Toute forme d'application sera concernée par nos résultats théoriques, on peut citer, la navigation terrestre et aérienne dans un environnement peu ou pas connu. De même, la commande qu'on propose préserve la communication inter-agent, une fois planifiées. En terme d'application, on a considéré le modèle d'un véhicule à roues type unicycle, sans tenir compte de l'orientation (cas non holonôme) et dans le cas où l'environnement contient un ou plusieurs obstacle(s). Contrairement aux résultats de la littérature, qui sont basés sur une commande à structure variable pour l'évitement d'un obstacle, la commande répulsive-stabilisante trouvée est une commande continue sur l'espace de navigation. La deuxième partie de cette thèse traite le problème de stabilité d'une formation d'agents (système multi-véhicules) qui évolue dans un environnement hostile tout en préservant la communication entre les agents. Pour réussir la formation, la décentralisation de la commande par rapport aux agents est rendue robuste à travers des graphes de communication. Ces graphes relèvent de la stratégie et objectifs de la formation. Nos résultats de stabilité ont fait l'objet d'une implémentation rigoureuse sur un simulateur réalisé sous Matlab.

This thesis investigates a technique to estimate the risk of the mean-variance (MV) portfolio optimization problem. We call this technique the Scaling technique. It provides a better estimator of the risk of the MV optimal portfolio. We obtain this result for a general estimator of the covariance matrix of the returns which includes the correlated sampling case as well as the independent sampling case and the exponentially weighted moving average case. This gave rise to the paper, [CMcS]. Our result concerning the Scaling technique relies on the moments of the inverse of compound Wishart matrices. This is an open problem in the theory of random matrices. We actually tackle a much more general setup, where we consider any random matrix provided that its distribution has an appropriate invariance property (orthogonal or unitary) under an appropriate action (by conjugation, or by a left-right action). Our approach is based on Weingarten calculus. As an interesting byproduct of our study - and as a preliminary to the solution of our problem of computing the moments of the inverse of a compound Wishart random matrix, we obtain explicit moment formulas for the pseudo-inverse of Ginibre random matrices. These results are also given in the paper, [CMS]. Using the moments of the inverse of compound Wishart matrices, we obtain asymptotically unbiased estimators of the risk and the weights of the MV portfolio. Finally, we have some numerical results which are part of our future work.

The limiting law of the length of the longest increasing subsequence, LI_n, for sequences (words) of length n arising from iid letters drawn from finite, ordered alphabets is studied using a straightforward Brownian functional approach. Building on the insights gained in both the uniform and non-uniform iid cases, this approach is then applied to iid countable alphabets. Some partial results associated with the extension to independent, growing alphabets are also given. Returning again to the finite setting, and keeping with the same Brownian formalism, a generalization is then made to words arising from irreducible, aperiodic, time-homogeneous Markov chains on a finite, ordered alphabet. At the same time, the probabilistic object, LI_n, is simultaneously generalized to the shape of the associated Young tableau given by the well-known RSK-correspondence. Our results on this limiting shape describe, in detail, precisely when the limiting shape of the Young tableau is (up to scaling) that of the iid case, thereby answering a conjecture of Kuperberg. These results are based heavily on an analysis of the covariance structure of an m-dimensional Brownian motion and the precise form of the Brownian functionals. Finally, in both the iid and more general Markovian cases, connections to the limiting laws of the spectrum of certain random matrices associated with the Gaussian Unitary Ensemble (GUE) are explored.

Orientador: Letícia Marcondes Rezende / Banca: Marília Blundi Onofre / Banca: Vanice Maria de Oliveira Sargentini / Banca: Antônio Carlos Gomes / Banca: Alessandra Del Ré / Resumo: Esta pesquisa, ancorada no quadro teórico da Teoria das Operações Predicativas e Enunciativas, objetiva a descrição do sistema de representação metalinguística, elaborado por Antoine Culioli, a partir do qual nos propomos a investigar os valores referenciais dos marcadores verbais ser e estar numa perspectiva semântico-enunciativa e por um viés operatório. Para tanto, consideramos a articulação entre linguagem e línguas naturais e que as línguas são representadas por sistemas dinâmicos e constitutivamente variáveis, o que lhes confere estabilidade e plasticidade. Nesse sentido, é que pretendemos analisar, com base nos conceitos de deformalidade e invariância, o funcionamento dessas unidades linguísticas que se manifestam nos enunciados por meio de operações e que se configuram em uma prática textual de produção e interpretação de significação. Assim, optando por um modelo de análise que se instaura na relação enunciador, enunciado e enunciação, pautamos nossas reflexões no modo de construção dos valores referenciais dos marcadores linguísticos, objeto da pesquisa, dada a singularidade do real valor significativo desses lexemas. Esse processo de construção que se manifesta na circunstância particular que a produz e na qual se inscreve o sujeito evidencia-se nos arranjos léxico-gramaticais, principalmente, quando os confrontamos com os cânones impostos pela tradição gramatical / Abstract: This research is based on Enunciative and Predicative Operations Theory and aims to describe the metalinguistic representation system, elaborated by Antoine Culioli, from which we propose to investigate the reference values of the verbal markers "being", within a semantic-enunciative perspective and by an operative bias. To this end, we consider the relationship between language and natural languages and the languages representation by dynamic systems and constitutively variable, which gives them stability and plasticity. The analysis is done from concepts on deformality and invariance, the functioning of these units language that are expressed in utterances through operations that take place in a textual practice of production and interpretation of meaning. Thus, by choosing an analysis model that establishes in the relationship enunciator, statement, and utterance, our reflections are based on the construction mode of reference values of the linguistic markers, object of this research, aiming at the uniqueness of the significant real value of these lexemes. This construction process that is manifested in the particular circumstance that produces it and which the subject is subscribed. The lexical grammatical arrangements are evidenced, mainly when they are confronted with the canons imposed by traditional grammar / Doutor

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-10-16T18:43:09Z No. of bitstreams: 1 GILVAN BONFIM E SOUZA – DISSERTAÇÃO (PPGFísica) 2017.pdf: 376396 bytes, checksum: 2125734f38cbbf4b7cf62d62515ca94c (MD5) / Made available in DSpace on 2018-10-16T18:43:09Z (GMT). No. of bitstreams: 1 GILVAN BONFIM E SOUZA – DISSERTAÇÃO (PPGFísica) 2017.pdf: 376396 bytes, checksum: 2125734f38cbbf4b7cf62d62515ca94c (MD5) Previous issue date: 2017-02 / Nesta dissertação calculamos alguns limites fenomeno lógicos para a eletrodinâmica e gravitação massiva e maltas ordens derivativas, supondo que é possível ter um processo astrofísico que gere simultaneamente ondas gravitacionais e eletromagnéticas. Apresentamos operadores de altas ordens derivativas que viola a invariância de Lorentz, seguindo a abordagem de Myers-Pospelov para descrição de ondas gravitacionais massivas e eletromagnéticas. Calculamos as equações de movimento desses modelos, suas relações de dispersão e as velocidades. Os parâmetros que controlam a violação no setor gravitacional Ƹg e eletromagnético Ƹy, são obtidos por duas abordagens diferentes: o atraso temporal e diferença de velocidades dos fótons e grávitons. Estes parâmetros dependem das suas respectivas escalas de massa pela qual os efeitos da violação de Lorentz se tornam relevantes, setor eletromagnético dado por M e o setor gravitacional dado M1. A razão entre os parâmetros Ƹg e Ƹy é de interesse do ponto de vista fenomenológicos e M ˃ M1. Determinamos também a diferença entre as velocidades dos fótons e grávitons, e como resultado, obtemos compatível com os resultados apresentados anteriormente na literatura. / In this work,we compute some phenomenological bounds for the electromagnetic and massive gravitational high-derivative extensions supposing that it is possible to have an astrophysical process that generates simultaneously gravitational and electromagnetic waves. We present a Lorentz-violating LIV higher-order derivative, following the Myers- Pospelov approach, to electro dynamics and massive gravitation alwaves. We compute the corrected equation of motion of these models, their dispersion relations and the velocities. The LIV parameters for the gravitational Ƹg and electromagnetic sector Ƹy respectively were also obtained for two different approaches time delay of lightand the difference of graviton and photon velocities. These LIV parameters depend on the masss cales where the LIV-terms be come relevant, M for the electromagnetic sectorand M1 for the gravitational one. The relation between the parameters Ƹg and Ƹy is of interest from the phenomenological point of view if M ˃ M1. We determine the diference betweent heve-locities of the photon and the graviton was calculated and our result, v􀀀�vg .0:62 10􀀀�17, is compatible with the results already presented in the literature.

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-10-17T19:12:16Z No. of bitstreams: 1 KLECIO EMANUEL LIMA DE FARIAS – DISSERTAÇÃO (PPGFísica) 2017.pdf: 669446 bytes, checksum: 26edbf33fb48c30aed37e5d2c6da2a80 (MD5) / Made available in DSpace on 2018-10-17T19:12:16Z (GMT). No. of bitstreams: 1 KLECIO EMANUEL LIMA DE FARIAS – DISSERTAÇÃO (PPGFísica) 2017.pdf: 669446 bytes, checksum: 26edbf33fb48c30aed37e5d2c6da2a80 (MD5) Previous issue date: 2017-10-04 / Capes / Neste trabalho, aplicamos o reescalonamento tipo ao de Hoˇrava-Lifshitz para reescrever algumas teorias eletrodinâmicas de altas ordens derivativas que violam a simetria de Lorentz, controladas por quadrivetores: (n )s que determinam direções preferenciais no espaço - tempo. As equações de movimento foram obtidas, através das quais analisamos as relações de dispersão modificadas em conjunto com os resultados observacionais das experiências de explosão de raios gama (GRB). Os limites do expoente crítico foram discutidos a partir dos dados dos GRBs através de cálculos de grau de polarizaçao (usando operador de dimensão-cinco) e de atraso temporal (usando operador de dimensão-seis) nas propagações dos fótons. As implicações físicas foram comparadas com recentes resultados da literatura sobre limites da quebra da invariância de Lorentz via GRBs. / In this work, we used a Hoˇrava-Lifshitz scaling to rewrite a high-order derivative electrodynamics that violates the Lorentz symmetry, controlled by 4-vector (n )s which determine the space-time preferential directions. The equations of motion were obtained, through which the modified dispersion relation was analyzed together with observational results of gamma ray bursts (GRB). The limits of the critical exponent were discussed from the GRBs values through calculation of degree of polarization (using five-dimensional operator) and temporal delay (using six-dimensional operator) on photon propagation. The physical implications were compared with the current results from the literature regarding Lorentz invariance violation via GRB.