Neste trabalho, estudamos o problema a recoloração convexa de grafos, denotado por RC. Dizemos que uma coloração dos vértices de um grafo G é convexa se, para cada cor tribuída d, os vértices de G com a cor d induzem um subgrafo conexo. No problema RC, é dado um grafo G e uma coloração de seus vértices, e o objetivo é recolorir o menor número possível de vértices de G tal que a coloração resultante seja convexa. A motivação para o estudo deste problema surgiu em contexto de árvores filogenéticas. Sabe-se que este problema é NP-difícil mesmo quando G é um caminho. Mostramos que o problema RC parametrizado pelo número de mudanças de cor é W[2]-difícil mesmo se a coloração inicial usa apenas duas cores. Além disso, provamos alguns resultados sobre a inaproximabilidade deste problema. Apresentamos uma formulação inteira para a versão com pesos do problema RC em grafos arbitrários, e então a especializamos para o caso de árvores. Estudamos a estrutura facial do politopo definido como a envoltória convexa dos pontos inteiros que satisfazem as restrições da formulação proposta, apresentamos várias classes de desigualdades que definem facetas e descrevemos os correspondentes algoritmos de separação. Implementamos um algoritmo branch-and-cut para o problema RC em árvores e mostramos os resultados computacionais obtidos com uma grande quantidade de instâncias que representam árvores filogenéticas reais. Os experimentos mostram que essa abordagem pode ser usada para resolver instâncias da ordem de 1500 vértices em 40 minutos, um desempenho muito superior ao alcançado por outros algoritmos propostos na literatura. / In this work we study the convex recoloring problem of graphs, denoted by CR. We say that a vertex coloring of a graph G is convex if, for each assigned color d, the vertices of G with color d induce a connected subgraph. In the CR problem, given a graph G and a coloring of its vertices, we want to find a recoloring that is convex and minimizes the number of recolored vertices. The motivation for investigating this problem has its roots in the study of phylogenetic trees. It is known that this problem is NP-hard even when G is a path. We show that the problem CR parameterized by the number of color changes is W[2]-hard even if the initial coloring uses only two colors. Moreover, we prove some inapproximation results for this problem. We also show an integer programming formulation for the weighted version of this problem on arbitrary graphs, and then specialize it for trees. We study the facial structure of the polytope defined as the convex hull of the integer points satisfying the restrictions of the proposed ILP formulation, present several classes of facet-defining inequalities and the corresponding separation algorithms. We also present a branch-and-cut algorithm that we have implemented for the special case of trees, and show the computational results obtained with a large number of instances. We considered instances which are real phylogenetic trees. The experiments show that this approach can be used to solve instances up to 1500 vertices in 40 minutes, comparing favorably to other approaches that have been proposed in the literature.

This thesis deals with modeling of particle processes. In the first part we ex- amine Gibbs facet process on a bounded window with discrete orientation distri- bution and we derive central limit theorem (CLT) for U-statistics of facet process with increasing intensity. We calculate all asymptotic joint moments for interac- tion U-statistics and use the method of moments for deriving the CLT. Moreover we present an alternative proof which makes use of the CLT for U-statistics of a Poisson facet process. In the second part we model planar segment processes given by a density with respect to the Poisson process. Parametric models involve reference distributions of directions and/or lengths of segments. Statistical methods are presented which first estimate scalar parameters by known approaches and then the reference distribution is estimated non-parametrically. We also introduce the Takacs-Fiksel estimate and demonstrate the use of estimators in a simulation study and also using data from actin fibres from stem cells images. In the third part we study a stationary Gibbs particle process with determin- istically bounded particles on Euclidean space defined in terms of a finite range potential and an activity parameter. For small activity parameters, we prove the CLT for certain statistics of this...

Eight out of ten people in the United States will have problems with low back pain at some point in their life. The most significant surgical treatments for low back pain can be distributed into two main groups of solutions: arthrodesis and arthroplasty. Spinal arthrodesis consists of the fusion of a degenerated functional spine unit (FSU) to alleviate pain and prevent mechanical instability. Spinal arthroplasty consists of the implantation of an artificial disc to restore the functionality of the degenerated FSU. The objective of this study is to analyze and compare the alteration of the biomechanics of the lumbar spine treated either by arthrodesis or arthroplasty. A three-dimensional finite element model of a ligamentous lumbar motion segment, constituted of two FSUs, was built and simulated through a static analysis with the finite element software ABAQUS. It was shown that the mobility of the segment treated by arthrodesis was reduced in all rotational degrees of freedom by an average of approximately 44%, relative to the healthy model. Conversely, the mobility of the segment treated by arthroplasty was increased in all rotational degrees of freedom by an average of approximately 52%. The FSU implanted with the artificial disc showed a high risk of instability and further degeneration. The mobility and the stresses in the healthy FSU, adjacent to the restored FSU in the segment treated by arthroplasty, were also increased. In conclusion, the simulation of the arthroplasty model showed more risks of instability and further degeneration, on the treated level as well as on the adjacent levels, than in the arthrodesis model.

Molecular beam epitaxy has recently been applied to the growth and self assembly of nanostructures on crystal substrates. This highlights the importance of understanding how microscopic rules of atomic motion and assembly lead to macroscopic surface shapes. In this thesis, we present results from two computational studies of these mechanisms. We identify a kinetic mechanism responsible for the emergence of low-angle facets in recent epitaxial regrowth experiments on patterned surfaces. Kinetic Monte Carlo simulations of vicinal surfaces show that the preferred slope of the facets matches the threshold slope for the transition between step flow and growth by island nucleation. At this crossover slope, the surface step density is minimized and the adatom density is maximized, respectively. A model is developed that predicts the temperature dependence of the crossover slope and hence the facet slope. We also examine the "step bunching" instability thought to be present in step flow growth on surfaces with a downhill diffusion bias. One mechanism thought to produce the necessary bias is the inverse Ehrlich Schwoebel (ES) barrier. Using continuum, stochastic, and hybrid models of one dimensional step flow, we show that an inverse ES barrier to adatom migration is an insufficient condition to destabilize a surface against step bunching.

This study explored mindfulness in eight self–injuring psychiatric adolescents. A concurrent triangulation mixed–method design was used. In–depth semi–structured clinical interviews and clinical records constituted the qualitative data, while quantitative data was gathered using the Five–Facet Mindfulness Questionnaire (FFMQ). Thematic analysis was used to generate themes and subthemes for both selfinjury and mindfulness. Findings regarding self–injury were in line with the literature. In terms of mindfulness, two groups emerged: one sometimes acting mindfully and the other often acting mindfully. Both similarities and differences were found between the groups. Similarities in self–injuring behaviour can be explained by their similar scores on Observe and Nonreact, while the differences can be explained by the differences in their scores on Describe, Act with Awareness and Nonjudge. Those who sometimes act mindfully tend to be more self–critical, report more severe and lethal self–injuring episodes and more often use self–injury for self–punishment. Although those who often act mindfully self–injure more often, they show more selfcompassion and report less severe injuries and less lethal methods. Future research should explore the usefulness of mindfulness–based interventions, especially teaching Nonjudge and Nonreact skills, to not only increase mindfulness, but to decrease selfinjuring behaviour. Seeing that this is an exploratory study on a small sample, the results presented here should be considered to be preliminary until replicated with a larger clinical sample. / Thesis (M.A. (Clinical Psychology))--North-West University, Potchefstroom Campus, 2011.

This study explored mindfulness in eight self–injuring psychiatric adolescents. A concurrent triangulation mixed–method design was used. In–depth semi–structured clinical interviews and clinical records constituted the qualitative data, while quantitative data was gathered using the Five–Facet Mindfulness Questionnaire (FFMQ). Thematic analysis was used to generate themes and subthemes for both selfinjury and mindfulness. Findings regarding self–injury were in line with the literature. In terms of mindfulness, two groups emerged: one sometimes acting mindfully and the other often acting mindfully. Both similarities and differences were found between the groups. Similarities in self–injuring behaviour can be explained by their similar scores on Observe and Nonreact, while the differences can be explained by the differences in their scores on Describe, Act with Awareness and Nonjudge. Those who sometimes act mindfully tend to be more self–critical, report more severe and lethal self–injuring episodes and more often use self–injury for self–punishment. Although those who often act mindfully self–injure more often, they show more selfcompassion and report less severe injuries and less lethal methods. Future research should explore the usefulness of mindfulness–based interventions, especially teaching Nonjudge and Nonreact skills, to not only increase mindfulness, but to decrease selfinjuring behaviour. Seeing that this is an exploratory study on a small sample, the results presented here should be considered to be preliminary until replicated with a larger clinical sample. / Thesis (M.A. (Clinical Psychology))--North-West University, Potchefstroom Campus, 2011.

Eine in vielen Bibliothekskatalogen bislang nicht verwirklichte Recherchefunktion ist die gezielte Suche nach Literatur aus bestimmten Fachgebieten. Recherchen mit Notationen der im Katalog verwendeten Klassifikation oder mit Schlagwörtern können den Anspruch an eine fachgebietsumfassende Suche meist nicht erfüllen. Eine mögliche Lösung ist die Entwicklung einer bibliotheksspezifischen fachlichen Facette, in der jeder Titel über seine sachlichen Erschließungsdaten einem oder mehreren Fächern zugeordnet wird. Im Vortrag wird nach einem Überblick über bereits vorhandene fachliche Facettierungsmöglichkeiten in verschiedenen Bibliothekskatalogen die Konzeption einer fachlichen Facette für den Bibliothekskatalog der Universitätsbibliothek Mannheim erläutert. Hierbei wurden im Besonderen die vorliegenden Sacherschließungsdaten sowie die fachlichen Schwerpunkte der Medienbestände der Universitätsbibliothek Mannheim berücksichtigt. Das Ziel war die Definition und die Zusammenstellung von Fächern, die im Bibliothekskatalog in unterschiedlichen Varianten umgesetzt und verwendet werden können.

We study the facial structure of the independent set polytope using the concept of conflict hypergraphs. A conflict hypergraph is a hypergraph whose vertices correspond to the binary variables, and edges correspond to covers in the constraint matrix of the independent set polytope. Various structures such as cliques, odd holes, odd anti-holes, webs and anti-webs are identified on the conflict hypergraph. These hypergraph structures are shown to be generalization of traditional graph structures. Valid inequalities are derived from these hypergraph structures, and the facet defining conditions are studied. Chvatal-Gomory ranks are derived for odd hole and clique inequalities. To test the hypergraph cuts, we conduct computational experiments on market-share (also referred to as market-split) problems. These instances consist of 100% dense multiple-knapsack constraints. They are small in size but are extremely hard to solve by traditional means. Their difficult nature is attributed mainly to the dense and symmetrical structure. We employ a special branching strategy in combination with the hypergraph inequalities to solve many of the particularly difficult instances. Results are reported for serial as well as parallel implementations.

Molecular beam epitaxy has recently been applied to the growth and self assembly of nanostructures on crystal substrates. This highlights the importance of understanding how microscopic rules of atomic motion and assembly lead to macroscopic surface shapes. In this thesis, we present results from two computational studies of these mechanisms. We identify a kinetic mechanism responsible for the emergence of low-angle facets in recent epitaxial regrowth experiments on patterned surfaces. Kinetic Monte Carlo simulations of vicinal surfaces show that the preferred slope of the facets matches the threshold slope for the transition between step flow and growth by island nucleation. At this crossover slope, the surface step density is minimized and the adatom density is maximized, respectively. A model is developed that predicts the temperature dependence of the crossover slope and hence the facet slope. We also examine the "step bunching" instability thought to be present in step flow growth on surfaces with a downhill diffusion bias. One mechanism thought to produce the necessary bias is the inverse Ehrlich Schwoebel (ES) barrier. Using continuum, stochastic, and hybrid models of one dimensional step flow, we show that an inverse ES barrier to adatom migration is an insufficient condition to destabilize a surface against step bunching.

xv, 173 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / Both Buddhist scholars and psychological researchers have suggested that mindfulness practice may result in greater empathy, but previous research has found mixed results. In addition, Buddhist philosophy suggests that mindfulness should influence the perception of and felt connection to others. Little research, however, has examined such an influence. The present studies examined the effect of dispositional mindfulness, as well as short- and long-term mindfulness meditation practice, on trait and state empathy, social perception, and felt connection to others. Study 1 manipulated mindfulness with a guided meditation CD and found that participants in this condition experienced more serenity and less negative emotion relative to control conditions. Study 1 also clarified the relationship between dispositional mindfulness (measured with the Five Facet Mindfulness Questionnaire), empathy (Interpersonal Reactivity Index), and felt connection (Allo-Inclusive Identity Scale). Results showed that different facets of mindfulness had different correlates. Higher observing scores were related to greater empathic concern and perspective taking; higher nonreactivity scores were related to less personal distress; and higher describing scores were associated with greater felt connection to others. Mindfulness was also associated with social perception such that higher nonreactivity scores were associated with greater ease in making emotion inferences from short video clips and higher describing scores were associated with making more mental state inferences in a modified empathic accuracy task. In Study 2, a randomized 8-week mindfulness intervention caused increases in dispositional mindfulness, especially describing scores, relative to a waitlist control condition. The intervention also resulted in increased serenity and joy and decreased negative affect and tension. Except for changes in serenity, these changes were fully mediated by increases in dispositional mindfulness. Those in the intervention condition decreased in personal distress to others' suffering, increased in the amount of mental state inferences they made for empathic accuracy targets, and increased in their ability to make inferences at times when the targets were actually having a thought or feeling. Thus, mindfulness training not only resulted in intrapersonal changes such as greater serenity and less tension; it also increased cognitive and emotional abilities important for empathy toward other people. / Committee in charge: Bertram Malle, Co-Chairperson, Psychology; Sanjay Srivastava, Co-Chairperson, Psychology; Sara Hodges, Member, Psychology; Mark Unno, Outside Member, Religious Studies