In this thesis, we develop block-decomposition (BD) methods and variants of accelerated *9gradient methods for large-scale conic programming and convex optimization, respectively. The BD methods, discussed in the first two parts of this thesis, are inexact versions of proximal-point methods applied to two-block-structured inclusion problems. The adaptive accelerated methods, presented in the last part of this thesis, can be viewed as new variants of Nesterov's optimal method. In an effort to improve their practical performance, these methods incorporate important speed-up refinements motivated by theoretical iteration-complexity bounds and our observations from extensive numerical experiments. We provide several benchmarks on various important problem classes to demonstrate the efficiency of the proposed methods compared to the most competitive ones proposed earlier in the literature. In the first part of this thesis, we consider exact BD first-order methods for solving conic semidefinite programming (SDP) problems and the more general problem that minimizes the sum of a convex differentiable function with Lipschitz continuous gradient, and two other proper closed convex (possibly, nonsmooth) functions. More specifically, these problems are reformulated as two-block monotone inclusion problems and exact BD methods, namely the ones that solve both proximal subproblems exactly, are used to solve them. In addition to being able to solve standard form conic SDP problems, the latter approach is also able to directly solve specially structured non-standard form conic programming problems without the need to add additional variables and/or constraints to bring them into standard form. Several ingredients are introduced to speed-up the BD methods in their pure form such as: adaptive (aggressive) choices of stepsizes for performing the extragradient step; and dynamic updates of scaled inner products to balance the blocks. Finally, computational results on several classes of SDPs are presented showing that the exact BD methods outperform the three most competitive codes for solving large-scale conic semidefinite programming. In the second part of this thesis, we present an inexact BD first-order method for solving standard form conic SDP problems which avoids computations of exact projections onto the manifold defined by the affine constraints and, as a result, is able to handle extra large-scale SDP instances. In this BD method, while the proximal subproblem corresponding to the first block is solved exactly, the one corresponding to the second block is solved inexactly in order to avoid finding the exact solution of a linear system corresponding to the manifolds consisting of both the primal and dual affine feasibility constraints. Our implementation uses the conjugate gradient method applied to a reduced positive definite dual linear system to obtain inexact solutions of the latter augmented primal-dual linear system. In addition, the inexact BD method incorporates a new dynamic scaling scheme that uses two scaling factors to balance three inclusions comprising the optimality conditions of the conic SDP. Finally, we present computational results showing the efficiency of our method for solving various extra large SDP instances, several of which cannot be solved by other existing methods, including some with at least two million constraints and/or fifty million non-zero coefficients in the affine constraints. In the last part of this thesis, we consider an adaptive accelerated gradient method for a general class of convex optimization problems. More specifically, we present a new accelerated variant of Nesterov's optimal method in which certain acceleration parameters are adaptively (and aggressively) chosen so as to: preserve the theoretical iteration-complexity of the original method; and substantially improve its practical performance in comparison to the other existing variants. Computational results are presented to demonstrate that the proposed adaptive accelerated method performs quite well compared to other variants proposed earlier in the literature.

Background: Complex proximal humerus fractures with metaphyseal comminution remain challenging regarding reduction and stability. In most fracture patterns the hard bone of the bicipital groove remains intact. In this case series, we describe a novel technique of hybrid double plate osteosynthesis of complex proximal humerus fractures with metaphyseal comminution. Methods: In randomly chosen shoulder specimens and synthetic bones, pilot studies for evaluation of the feasibility of the technique were performed. Between 4/2010 and 1/2012 10 patients underwent hybrid double plate osteosynthesis. Seven patients (4 male, 3 female, mean age was 50 years (range 27–73)) were available for retrospective analysis. Based on plain radiographs (anterior-posterior and axial view), the fractures were classified according to the Orthopaedic Trauma Association classification (OTA) and by descriptive means (head-split variant (HS), diaphyseal extension or comminution (DE)). Results: Follow-up radiographs demonstrated complete fracture healing in six patients and one incomplete avascular necrosis. None of the patients sustained loss of reduction. Three patients where reoperated. The medium, not adapted, Constant score was 80 Points (58–94). Patients subjective satisfaction was graded mean 3 (range: 0–6) in the visual analog scoring system (VAS). Conclusion: The technique of hybrid double plate osteosynthesis using the bicipital groove as anatomic landmark may re-establish shoulder function after complex proximal humerus fractures in two dimensions. Firstly the anatomy is restored due to a proper reduction based on intraoperative landmarks. Secondly additional support by the second plate may provide a higher stability in complex fractures with metaphyseal comminution.

Det uppfattas idag som en självklarhet att fortsätta lära och utvecklas genom hela livet. Årligen spenderas stora summor på ledarutveckling, vilket har väckt ett intresse att undersöka denna form av utbildningsaktiviteter. Denna studie syftar till att undersöka vad som kan ligga till grund för valet att delta i ledarutvecklingsaktiviteter utifrån en fallstudie hos Stelena, samt hur deltagarna uppfattar att dessa aktiviteter bidrar till lärande och praktisk användbarhet. Fyra frågeställningar formulerades; Vilka motiv framkommer för deltagande i dessa aktiviteter? På vilket sätt uppfattar deltagarna att kompetenser och verktyg genereras i aktiviteterna? På vilket sätt uppfattar deltagarna att ledarutvecklingsaktiviteterna influerat deltagarna och bidragit till ett lärande? Hur uppfattar deltagarna möjligheterna att kunna använda genererade kompetenser och verktyg i sitt dagliga arbete? För att få en ingång till våra frågeställningar tog vi inledningsvis del av tidigare forskning inom området ledarutveckling. För att insamla vårt empiriska material genomfördes sju intervjuer. Därefter analyserades materialet med inspiration av pragmatisk diskursanalys, samt med hjälp av utvalda teoretiska utgångspunkter; aktivitetsteorin, proximala utvecklingszonen, samt reflekterande handling. I detta analysförfarande urskildes en norm, att individers problemformuleringar i aktiviteterna kunde ses som ett dialektiskt spel mellan det individuella och kollektiva. Resultatet visar att motiv till att delta ofta grundade sig i ett behov av stöd.  Således har det visat sig att kommunikation och reflektion i ledarutvecklingsaktiviteterna tycks generera redskapen. Likväl som kommunikation ligger till grund för verktygsskapandet uppfattades kommunikativ kompetens och ett reflekterande förhållningssätt viktigt i rollen som ledare. Ledarutvecklingsaktiviteterna har vidare bidragit med redskap vilka lärt individer hantera situationer utifrån nya perspektiv. Det har framkommit hur aktiviteterna gett en ökad förståelse för betydelsen av att lära känna sig själv, medarbetares olikheter och således hur dessa lärdomar bidrar till ett mer effektivt ledarskap. Resultatet visar hur individer upplever att de haft nytta av flera av de verktyg som genererats, både för egen del och för organisationen i stort. / Present conception is that individuals are under constant development and learning during their entire life. Every year a large amount of money is spent on leadership development. There has been an increasing interest to such educational activities. The aim of this study is to examine, what the basis beyond participation can be in leader development activities, through a case-study at Stelena, and how participants perceive that the activities contributes to learning and practical use. Four questions were framed; which motives for participation in these activities appear? In which way do participants perceive that competencies and tools generates in the activities? In which way do participants perceive that the leader development activities have influenced them and contributed to learning? How do participants perceive the ability to use acquired competencies and tools in their daily work?   In order to find answers to our questions, we took part of recent science connected to leader development. Seven interviews were done in order to collect our empirical material. With inspiration from pragmatic discourse analysis and with theoretical base, the material was analysed. Our theoretical bases are activity theory, the zone of proximal development and reflective action. In the analysis work we did distinguish a norm, that problem formulations in the activities could be seen as a dialectical game between the individual and the collective.  The result shows that motives beyond participation many times were based on a need of support. It has been shown how communication and reflection in Stelena leader development activities appear to generate tools. As well as communication and reflection is underlying the creation of tools, communicative competence and a reflective approach are seen as very useful in the role of a leader. Stelena has also provided tools, which have taught individuals to manage situations from new perspectives. The study shows how the activities increased the understanding of the importance to get to know oneself, differences of co-workers and in what way such learning contributes to more effective leadership. The result shows how individuals experienced great usefulness of those tools, both for themselves and for the organisations.

This study explores the web-navigation practices of adult learners in higher education and re-conceptualizes the concept of the organizing circumstance of self-managed learning, originated by Spear and Mocker (1984). The theoretical framework draws on funds of knowledge theory from a cultural historical perspective and elaborates a Vygotskian concepts of learning and development by introducing the notion of the distal object and the zone of distal development. The study employed a mixed methods design with an embedded multiple-case study involving half of the twelve participants using a new technology for self-managed learning called Zonebee. Zonebee recorded participants' web navigation, known as Zonebee Trails, providing quantitative data for analysis. Surveys were administered, namely the Metacognitive Awareness Inventory (Schraw&Dennison, 1994), the Index of Learning Styles Inventory (Soloman&Felder, 1986), a survey of technology use (created for this study) and a set of demographic questions. Eleven of the twelve participants also provided interviews in which they described their self-managed learning practices.Findings contradicted the premise in the literature that the learning environment fortuitously determines the learning experience. Participants primarily relied on the internet and computer to manage their learning and made deliberate choices about which tools to use depending upon the purpose of the constituent process of self-managed learning in which they were engaged (assessing, planning, implementing, monitoring, evaluating or producing). Zonebee Trails evidenced participants' engagement in considerable planning before generating focused queries to locate specific materials. Thus, this study suggests that the organizing circumstance operates, not through happenstance alone, but through the confluence of four factors influencing the direction the learner takes: funds of knowledge for learning; learning demands (proximity of the learning object, proximal or distal), conditions for learning (affordances for and constraints on learning); and motivation or purpose of activity. The re-conceptualized organizing circumstance of learning, then, offers a methodological and theoretical way to redefine context and understand how learners manage their own learning.

Cette th'ese est consacr'ee 'a l''etude et la r'esolution de certains probl'emes non lin'eaires du traitement du signal et de l'image via l'analyse convexe. Nous proposons une 'etude variationnelle unifi'ee de probl'emes inverses et de probl'emes de d'ecomposition de signaux qui ont, jusqu''a pr'esent, 'et'e 'etudi'es individuellement en raison de leur apparente disparit'e. Dans le mod'ele adopt'e, cette famille de probl'emes est r'eduite g'en'eriquement 'a la minimisation d'une somme de deux fonctions soumises 'a certaines propri'et'es de r'egularit'e. Des r'esultats d'existence, d'unicit'e et de caract'erisation du probl'eme ainsi pos'e sont obtenus. L'op'erateur proximal, introduit par Moreau en 1962 pour les besoins de la m'ecanique, joue un rˆole essentiel dans notre analyse. Nous l'utilisons notamment pour obtenir de nouveaux sch'emas non lin'eaires de d'ecomposition de signaux. Cet outil est par ailleurs au coeur de l'algorithme explicite-implicite que nous proposons pour la r'esolution du probl'eme g'en'erique. Ce cadre th'eorique est appliqu'e 'a l'analyse de signaux et 'a la restauration d'images. Les probl'emes de restauration que nous abordons sont pos'es sur des trames et notre approche permet de prendre en compte des contraintes de parcimonie ou de mod'eliser des formulations bay'esiennes avec des connaissances a priori sur les lois des coefficients de la d'ecomposition. Des r'esultats num'eriques sont fournis.

Im Rahmen einer Kaufuntersuchung beim Pferd ist es von besonderem Interesse leistungsmindernde Faktoren aufzudecken. Dem Tierarzt stehen zu diesem Zwecke sowohl standardisierte Protokolle für die Durchführung der klinischen Untersuchung als auch der „Leitfaden für die röntgenologische Beurteilung bei der Kaufuntersuchung“ (Röntgenleitfaden 2007)zur Verfügung. Bezüglich der Anzahl der im Rahmen einer Kaufuntersuchung angefertigten Röntgenaufnahmen gibt es fortwährende Diskussionen. Besonders deutlich wird diese Problematik im internationalen Vergleich. Jedes Land, zum Teil auch die verschiedenen Zuchtverbände, verlangen unterschiedliche Standardaufnahmen. Ziel der Arbeit war die Überprüfung der Darstellbarkeit röntgenologischer Befunde im Bereich des Fesselgelenks, der Gleichbeine und des Fesselbeins, durch die im Röntgenleitfaden 2007 angegebene Standardaufnahme „Zehe 90°“ und die daraus resultierende Einteilung in Röntgenklassen. Es sollte geprüft werden wie sich die Einteilung der Röntgenklasse nach einer computertomographischen Darstellung und Befundung ändert. Von besonderem Interesse waren zusätzlich solche Befunde, die röntgenologisch nicht darstellbar waren, aber in der CT-Untersuchung gefunden werden konnten. Zur Untersuchung wurden 200 distale Gliedmaßen von 51 niedersächsischen Schlachtpferden röntgenologisch, computertomographisch und makroskopisch im Frisch- und Knochenpräparat herangezogen. Die Pferde wurden anhand der röntgenologischen Übersichtsaufnahme „Zehe 90°“ nach dem Schema des Röntgenleitfadens 2007 in Klassen eingeteilt. Anschließend erfolgte eine computertomographische Untersuchung. Ausgewertet wurden diese Bilder an einer Workstation, welche die Möglichkeit verschiedenster Rekonstruktionen bietet. Nachfolgend wurden die Pferde aufgrund der in der CT gefundenen Veränderungen in ihren Röntgenklassen korrigiert. Befunde, die nicht im Röntgenleitfaden aufgeführt sind, wurden gesondert betrachtet und im Rahmen einer Modellrechnung ausgewertet. Diese Modellrechnung betrachtet computertomographische Befunde, deren Detektion auch in einer röntgenologischen 0°Aufnahme der distalen Gliedmaße theoretisch zu erwarten gewesen wären. Diese Befunde wurden dann in die Klassifizierung der einzelnen Pferde einbezogen, um den Nutzen einer solchen zusätzlich zu der Standardaufnahme (Zehe 90°) angefertigten Röntgenaufnahme zu beurteilen. Im Anschluss wurden alle röntgenologischen und computertomographischen Befunde im Frisch bzw. Knochenpräparat aufgesucht und photographisch festgehalten. Fokus aller Untersuchungen war stets die Fesselgelenkregion sowie das distale Fesselbein. Die Einteilung der Pferde in eine bestimmte Röntgenklasse anhand ihrer Befunde im Fesselgelenkbereich änderte sich bei 84,31 % (n=51) der Pferde nicht, oder nur bis zu einer halben Röntgenklasse. Die meisten Pferde (43,14 %, n=51) der untersuchten Population ließen sich aufgrund ihrer Befunde im Fesselgelenk in Anlehnung an den Röntgenleitfaden 2007 in die Zwischenklasse II-III einordnen. Auch im Bereich der gesamten distalen Gliedmaße war es möglich 82,36 % (n=51), der Pferde röntgenologisch in eine Röntgenklasse einzuteilen, so dass sich auch nach der computertomographischen Untersuchung keine Veränderung, oder nur eine Änderung um eine halbe Klasse ergaben. Die als Goldstandard verwendete Computertomographie, erlaubte in dieser Arbeit die Annahme einer hypothetisch angefertigten 0° Aufnahme der Fesselgelenkregion. Diese Aufnahme ermöglicht vor allem die Detektion zystoider Defekte im Bereich der distalen Gliedmaße und führt zu einer Erhöhung der Anzahl der Pferde, die sich nicht in ihrer Röntgenklasse verändern, von 66,70 % auf 78,43 %.

L’intérêt considérable est dédié à l’autorégulation chez les conducteurs âgés. Notre première étude compare l’autorégulation des conducteurs âgés à celle des jeunes. Nous supposons trouver des corrélations positives entre les évitements auto-déclarés des situations de conduite difficiles et le niveau auto-déclaré de déclins cognitifs chez les conducteurs âgés, non pas chez les jeunes. Or, le fait d’opérationnaliser l’autorégulation par ce biais ne permet ni d’examiner le niveau d’autorégulation comportemental, ni les facteurs susceptibles de conditionner un tel comportement. Deux études sont alors conçues de sorte à définir le modèle de l’apprentissage autorégulé le plus adapté pour l’examen des capacités d’autorégulation (étude 2), et à identifier les éléments susceptibles de modifier une autorégulation comportementale (étude 3). Dans l’étude 2, nous testons dans une expérience sur simulateur de conduite deux modèles métacognitifs, dont celui s’avérant plus compréhensif est maintenu comme paradigme expérimental pour la troisième étude. Cette dernière compare les patterns d’autorégulation de deux groupes de conducteurs âgés, dont un soumis à la menace du stéréotype. Les résultats indiquent que les conducteurs âgés basent leurs comportements d’autorégulation sur leurs propres expériences de la difficulté, et que le fait de vouloir les instruire à l’aide d’indices extrinsèques semblables à ceux du stéréotype, puisse mener plus à une réduction de leur capacités qu’à leur supposée amélioration. / An increasing interest is actually devoted to the self-regulation in elderly drivers. Our first study compares the elderly drivers’ self-regulation to that of younger drivers. We suppose to observe in elderly drivers (but not in the younger ones) positive correlations between the self-declared avoidance of difficult driving situations and the self-declared decline of cognitive functioning. However, such an operationalization of self-regulation does not allow the study of neither the real behavioral self-regulation nor the factors conditioning such a behavior. Another two studies are then conceived in order to define both the self-regulated learning model that fits the best to the study of drivers’ self-regulatory patterns (study 2) and the factors that trigger such a behavioral self-regulation (study 3). In the second, driving-simulator study, we oppose the predictions of two metacognitive models, and this model that is better suited is withheld as the experimental paradigm for the third study. This latter compare the self-regulatory patterns of two groups of elderly drivers: one that is under stereotype threat and one that is not. Our results indicate that, first, elderly drivers presumably base their self-regulatory behavior on their sheer experience of the difficulty and, second, the efforts to enhance their self-regulation by extrinsic cues (such as those similar to the stereotype used in our third study) in fact hinder their self-regulatory abilities rather than enhance them.

During cell specification, temporal and spatially restricted gene expression programs are set up, forming different cell types and ultimately a multicellular organism. In this thesis, we have studied the molecular mechanisms by which sequence specific transcription factors and coactivators regulate RNA polymerase II (Pol II) transcription to establish specific gene expression programs and what epigenetic patterns that follows. We found that the transcription factor Dorsal is responsible for establishing discrete epigenetic patterns in the presumptive mesoderm, neuroectoderm and dorsal ectoderm, during early Drosophila embryo development. In addition, these different chromatin states can be linked to distinct modes of Pol II regulation. Our results provide novel insights into how gene regulatory networks form an epigenetic landscape and how their coordinated actions specify cell identity. CBP/p300 is a widely used co-activator and histone acetyltransferase (HAT) involved in transcriptional activation. We discovered that CBP occupies the genome preferentially together with Dorsal, and has a specific role during development in coordinating the dorsal-ventral axis of the Drosophila embryo. While CBP generally correlates with gene activation we also found CBP in H3K27me3 repressed chromatin. Previous studies have shown that CBP has an important role at transcriptional enhancers. We provide evidence that the regulatory role of CBP does not stop at enhancers, but is extended to many genomic regions. CBP binds to insulators and regulates their activity by acetylating histones to prevent spreading of H3K27me3. We further discovered that CBP has a direct regulatory role at promoters. Using a highly potent CBP inhibitor in combination with ChIP and PRO-seq we found that CBP regulates promoter proximal pausing of Pol II. CBP promotes Pol II recruitment to promoters via a direct interaction with TFIIB, and promotes transcriptional elongation by acetylating the first nucleosome. CBP is regulating Pol II activity of nearly all expressed genes, however, either recruitment or release of Pol II is the rate-limiting step affected by CBP. Taken together, these results reveal mechanistic insights into cell specification and transcriptional control during development. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.</p><p> </p>

This paper describes an alternative approach to the teaching of concepts related to the English Curriculum. It combines a shift in the theory of school teaching with psychological theory development. This research was conducted at a private, Catholic Secondary School in Johannesburg over a period of almost six months with a class of twenty Grade Ten students. The research was designed in response to the fact that many traditional, ‘rote’ teaching methods are not effective in the classroom and that an alternative needs to be found. This research aimed at testing the theories of the Sociohistorical school in order to ascertain whether they could provide clues as to methods that might be more conducive to real learning. Vygotsky’s (1978) theoretical construct of the Zone of Proximal Development, Hedegaard’s (1996) idea of a ‘double move’ and the ideas posited by Wells (1996, 1999) and Tharp and Gallimore (1988, 1992) form the theoretical basis for these ‘alternative’ teaching methods. The results shown in this paper indicate that a ‘double move’ is possible within the context of the English classroom and that the ideas of the Socio-historical school indeed provide an alternative method that is far more successful than those traditionally used in most classrooms.

[pt] Diversos problemas em engenharia, aprendizado de máquina e economia podem ser resolvidos através de Programação Semidefinida (SDP). Potenciais aplicações podem ser encontradas em telecomunicações, fluxo de potência e teoria dos jogos. Além disso, como SDP é uma subclasse de otimização convexa, temos uma série de propriedades e garantias que fazem da SDP uma tecnologia muito poderosa. Entretanto, dentre as diferentes subclasses de otimização convexa, SDP ainda permanece como uma das mais desafiadoras. Instancias de larga escala ainda não podem ser resolvidas pelos atuais softwares disponíveis. Nesse sentido, esta tese porpõe um novo algoritmo para resolver problemas de SDP. A principal contribuição deste novo algoritmo é explorar a propriedade de posto baixo presente em diversas instancias. A convergência desta nova metodologia é provada ao mostrar que o algoritmo proposto é um caso particular do Approximate Proximal Point Algorithm. Adicionalmente, as variáveis ótimas duais são disponibilizadas como uma consequência do algoritmo proposto. Além disso, disponibilizamos um software para resolver problemas de SDP, chamado ProxSDP. Três estudos de caso são utilizados para avaliar a performance do algoritmo proposto. / [en] Many problems of interest can be solved by means of Semidefinite Programming (SDP). The potential applications range from telecommunications, electrical power systems, game theory and many more fields. Additionally, the fact that SDP is a subclass of convex optimization brings a set of theoretical guarantees that makes SDP very appealing. However, among all sub-classes of convex optimization, SDP remains one of the most challenging in practice. State-of-the-art semidefinite programming solvers still do not efficiently solve large scale instances. In this regard, this thesis proposes a novel algorithm for solving SDP problems. The main contribution of this novel algorithm is to achieve a substantial speedup by exploiting the low-rank property inherent to several SDP problems. The convergence of the new methodology is proved by showing that the novel algorithm reduces to a particular case of the Approximated Proximal Point Algorithm. Along with the theoretical contributions, an open source numerical solver, called ProxSDP, is made available with this work. The performance of ProxSDP in comparison to state-of-the-art SDP solvers is evaluated on three case studies.