Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal. / Avec l'émergence des voyages spatiaux, plusieurs adaptations physiologiques ont été recensées en état d'apesanteur. L'apesanteur dans l'espace décroît l'activité et le chargement mécanique des muscles les plus importants pour déplacer et supporter le poids du corps, dans le but de maintenir une posture droite. Ces muscles, principalement les groupes musculaires des membres inférieurs, sont appelés muscles supporteurs du poids ; en réponse à une utilisation réduite, ils s'affaissent et dépérissent, ou s'atrophient. Les changements incluent une réduction de la grosseur du muscle [59, 60], la décomposition des protéines musculaires [61], la réduction de la force [69, 70] et de l'endurance [60] musculaires, de même que des changements dans les types de fibres présentes dans les muscles [61]. La faiblesse et le mauvais fonctionnement musculaire survenant suite à une exposition aux vois spatiaux réfèrent communément à l'atrophie musculaire fonctionnelle induite par microgravité (l'atrophie musculaire fonctionnelle signifie une réduction du volume des muscles liée à l'inactivité). Aucun de ces changements ne présente un problème pour les astronautes tant et aussi longtemps qu'ils n'effectuent que de légers travaux. Pour les astronautes, le problème devient critique lorsqu'ils reviennent sur terre et que les muscles affaiblis sont de nouveau soumis à la force de gravité intégrale. Dans une situation d'urgence, les individus aux muscles affaiblis seraient moins aptes à répondre rapidement ou à utiliser la force musculaire. À présent, l'atrophie musculaire fonctionnelle des muscles des membres inférieurs induite par microgravité demeure un sérieux problème pour les astronautes qui poursuivent un vol spatial prolongé. Des contremesures comme l'exercice physique [91] peuvent aider au maintien de la -force et des fonctions musculaires, toutefois l'exercice seul est insuffisant pour prévenir l'excès en perte musculaire. Ainsi, il est nécessaire de développer des solutions plus efficaces. La présente recherche a été entreprise afin d'évaluer l'efficacité de la stimulation électrique thérapeutique (SET) pour minimiser l'atrophie musculaire fonctionnelle et le mauvais fonctionnement musculaire chez des patients ayant subi une reconstruction du ligament croisé antérieur (LCA). Le LCA est fréquemment lésé au cours de pratiques sportives. Une atrophie et un affaiblissement significatifs du groupe musculaire du quadriceps femoris (GMQF) survient suite à la reconstruction du LCA [131] et s'applique aux adaptations neuromusculaires survenant chez les astronautes suite à une exposition prolongée en état d'apesanteur. L'objectif de cette recherche était d'entreprendre des expériences préliminaires afin de déterminer le paradigme de stimulation le plus efficace pour minimiser l'atrophie musculaire fonctionnelle des membres inférieurs induite par microgravité chez les astronautes. Le recours à des patients ayant subi une reconstruction du LCA fournit un modèle adéquat servant à étudier les traitements pouvant minimiser de tels déficits des fonctions musculaires. Au total, 24 patients ont été assignés au hasard dans deux groupes, soit un groupe expérimental (n=12) ou un groupe contrôle (n=12), suite à la reconstruction du LCA grâce à une greffe du tendon patellaire. Durant les 12 semaines suivant l'opération, tous les patients ont suivi un programme standard de réhabilitation. De plus, le groupe expérimental a reçu un traitement par SET pendant six à huit heures, et ce, cinq soirs par semaine. Le torque maximal isocinétique du GMQF, le travail et la puissance moyenne ont été mesurés dans les deux membres inférieurs à 60°/sec et à 180°/sec, en plus de l'activation neurale (iEMG) et de la fréquence de la puissance -médiane (MED) des muscles vastus medialis et vastus lateralis, avant l'opération et à six et 12 semaines après l'opération. Toutes les mesures ont été standardisées en pourcentage du GMQF sain. Les résultats indiquent qu'après l'opération, le torque maximal isocinétique, le travail et la puissance moyenne étaient significativement réduits (p<0,01) dans le GMQF lésé, et ce pour les deux vitesses, à six et à 12 semaines, comparativement aux valeurs préopératoires. L'activité iEMG du muscle vastus lateralis était significativement réduite à six (p<0,01) et à 12 semaines (p<0,05) suite à l'opération. Toutefois, aucune réduction significative de l'activité iEMG du vastus medialis n'a été observée, et ce pour les deux vitesses, à six et à 12 semâmes après l'opération. Le MED est passé à des fréquences plus basses dans les muscles vastus lateralis (p<0,01) et vastus medialis (p<0,05) lorsque mesurée à six semaines. Cependant, 12 semaines après l'opération, le MED du vastus lateralis était revenu aux valeurs préopératoires, alors que le changement de MED du vastus medialis persistait (p<0,05). Aucune différence significative n'a été observée entre les groupes contrôle et expérimental en terme de mesures du torque maximal isocinétique et d'activation des muscles vastus lateralis et vastus medialis tout au long de l'étude. En conclusion, la SET combinée à la réhabilitation n'a pas fourni de bénéfice supplémentaire en terme d'amélioration de la récupération du GMQF au début de la phase postopératoire chez des patients ayant subi une reconstruction du LCA grâce à une greffe du tendon patellaire.

This thesis focuses mainly on the Maximum Independent Set (MIS) problem. Some related graph theoretical combinatorial problems are also considered. As these problems are generally NP-hard, we study their complexity in hereditary graph classes, i.e. graph classes defined by a set F of forbidden induced subgraphs. We revise the literature about the issue, for example complexity results, applications, and techniques tackling the problem. Through considering some general approach, we exhibit several cases where the problem admits a polynomial-time solution. More specifically, we present polynomial-time algorithms for the MIS problem in: + some subclasses of $S_{2;j;k}$-free graphs (thus generalizing the classical result for $S_{1;2;k}$-free graphs); + some subclasses of $tree_{k}$-free graphs (thus generalizing the classical results for subclasses of P5-free graphs); + some subclasses of $P_{7}$-free graphs and $S_{2;2;2}$-free graphs; and various subclasses of graphs of bounded maximum degree, for example subcubic graphs. Our algorithms are based on various approaches. In particular, we characterize augmenting graphs in a subclass of $S_{2;k;k}$-free graphs and a subclass of $S_{2;2;5}$-free graphs. These characterizations are partly based on extensions of the concept of redundant set [125]. We also propose methods finding augmenting chains, an extension of the method in [99], and finding augmenting trees, an extension of the methods in [125]. We apply the augmenting vertex technique, originally used for $P_{5}$-free graphs or banner-free graphs, for some more general graph classes. We consider a general graph theoretical combinatorial problem, the so-called Maximum -Set problem. Two special cases of this problem, the so-called Maximum F-(Strongly) Independent Subgraph and Maximum F-Induced Subgraph, where F is a connected graph set, are considered. The complexity of the Maximum F-(Strongly) Independent Subgraph problem is revised and the NP-hardness of the Maximum F-Induced Subgraph problem is proved. We also extend the augmenting approach to apply it for the general Maximum Π -Set problem. We revise on classical graph transformations and give two unified views based on pseudo-boolean functions and αff-redundant vertex. We also make extensive uses of α-redundant vertices, originally mainly used for $P_{5}$-free graphs, to give polynomial solutions for some subclasses of $S_{2;2;2}$-free graphs and $tree_{k}$-free graphs. We consider some classical sequential greedy heuristic methods. We also combine classical algorithms with αff-redundant vertices to have new strategies of choosing the next vertex in greedy methods. Some aspects of the algorithms, for example forbidden induced subgraph sets and worst case results, are also considered. Finally, we restrict our attention on graphs of bounded maximum degree and subcubic graphs. Then by using some techniques, for example ff-redundant vertex, clique separator, and arguments based on distance, we general these results for some subclasses of $S_{i;j;k}$-free subcubic graphs.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste tese, estudamos os efeitos não perturbativos associados à presença do horizonte de Gribov e à condensação de operadores locais de dimensão dois, numa teoria de Yang-Mills euclidiana em SU(2), quantizada no calibre abeliano maximal. Estes efeitos são introduzidos de modo a preservar as propriedades de renormalizabilidade e localidade da teoria, e refletem-se diretamente no comportamento dos propagadores. A comparação com os dados da rede indicam um bom acordo qualitativo. / In this, we study the nonperturbative effects associated to the presence of the horizon and to the condensation of local dimension two operators in an Eucledean SU(2)Yang-Mills theory quantized in the maximal Abelian gauge. Such effects are introduced in a way to preserve the properties of renormalizability and locality of the theory. The comparison with the lattice data indicates a good qualitative agreement.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste tese, estudamos os efeitos não perturbativos associados à presença do horizonte de Gribov e à condensação de operadores locais de dimensão dois, numa teoria de Yang-Mills euclidiana em SU(2), quantizada no calibre abeliano maximal. Estes efeitos são introduzidos de modo a preservar as propriedades de renormalizabilidade e localidade da teoria, e refletem-se diretamente no comportamento dos propagadores. A comparação com os dados da rede indicam um bom acordo qualitativo. / In this, we study the nonperturbative effects associated to the presence of the horizon and to the condensation of local dimension two operators in an Eucledean SU(2)Yang-Mills theory quantized in the maximal Abelian gauge. Such effects are introduced in a way to preserve the properties of renormalizability and locality of the theory. The comparison with the lattice data indicates a good qualitative agreement.

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No. of bitstreams: 2 Tese - Reinier Díaz Millán - 2015.pdf: 3568052 bytes, checksum: b4c892f77911a368e1b8f629afb5e66e (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-02-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Nesta tese apresentamos v arios algoritmos para resolver os problemas de Desigualdade Variacional e Inclus~ao. Para o problema de desigualdade variacional propomos, no Cap tulo 2 uma generaliza c~ao do algoritmo cl assico extragradiente, utilizando vetores normais n~ao nulos do conjunto vi avel. Em particular, dois algoritmos conceituais s~ao propostos e cada um deles cont^em tr^es variantes diferentes de proje c~ao que est~ao relacionadas com algoritmos extragradientes modi cados. Duas buscas diferentes s~ao propostas, uma sobre a borda do conjunto vi avel e a outra ao longo das dire c~oes vi aveis. Cada algoritmo conceitual tem uma estrat egia diferente de busca e tr^es formas de proje c~ao especiais, gerando tr^es sequ^encias com diferente e interessantes propriedades. E feito a an alise da converg^encia de ambos os algoritmos conceituais, pressupondo a exist^encia de solu c~oes, continuidade do operador e uma condi c~ao mais fraca do que pseudomonotonia. No Cap tulo 4, n os introduzimos um algoritmo direto de divis~ao para o problema variacional em espa cos de Hilbert. J a no Cap tulo 5, propomos um algoritmo de proje c~ao relaxada em Espa cos de Hilbert para a soma de m operadores mon otonos maximais ponto-conjunto, onde o conjunto vi avel do problema de desigualdade variacional e dado por uma fun c~ao n~ao suave e convexa. Neste caso, as proje c~oes ortogonais ao conjunto vi avel s~ao substitu das por proje c~oes em hiperplanos que separam a solu c~ao da itera c~ao atual. Cada itera c~ao do m etodo proposto consiste em proje c~oes simples de tipo subgradientes, que n~ao exige a solu c~ao de subproblemas n~ao triviais, utilizando apenas os operadores individuais, explorando assim a estrutura do problema. Para o problema de Inclus~ao, propomos variantes do m etodo de divis~ao de forward-backward para achar um zero da soma de dois operadores, a qual e a modi ca c~ao cl assica do forwardbackward proposta por Tseng. Um algoritmo conceitual e proposto para melhorar o apresentado por Tseng em alguns pontos. Nossa abordagem cont em, primeramente, uma busca linear tipo Armijo expl cita no esp rito dos m etodos tipo extragradientes para desigualdades variacionais. Durante o processo iterativo, a busca linear realiza apenas um c alculo do operador forward-backward em cada tentativa de achar o tamanho do passo. Isto proporciona uma consider avel vantagem computacional pois o operador forward-backward e computacionalmente caro. A segunda parte do esquema consiste em diferentes tipos de proje c~oes, gerando sequ^encias com caracter sticas diferentes. / In this thesis we present various algorithms to solve the Variational Inequality and Inclusion Problems. For the variational inequality problem we propose, in Chapter 2, a generalization of the classical extragradient algorithm by utilizing non-null normal vectors of the feasible set. In particular, two conceptual algorithms are proposed and each of them has three di erent projection variants which are related to modi ed extragradient algorithms. Two di erent linesearches, one on the boundary of the feasible set and the other one along the feasible direction, are proposed. Each conceptual algorithm has a di erent linesearch strategy and three special projection steps, generating sequences with di erent and interesting features. Convergence analysis of both conceptual algorithms are established, assuming existence of solutions, continuity and a weaker condition than pseudomonotonicity on the operator. In Chapter 4 we introduce a direct splitting method for solving the variational inequality problem for the sum of two maximal monotone operators in Hilbert space. In Chapter 5, for the same problem, a relaxed-projection splitting algorithm in Hilbert spaces for the sum of m nonsmooth maximal monotone operators is proposed, where the feasible set of the variational inequality problem is de ned by a nonlinear and nonsmooth continuous convex function inequality. In this case, the orthogonal projections onto the feasible set are replaced by projections onto separating hyperplanes. Furthermore, each iteration of the proposed method consists of simple subgradient-like steps, which does not demand the solution of a nontrivial subproblem, using only individual operators, which explores the structure of the problem. For the Inclusion Problem, in Chapter 3, we propose variants of forward-backward splitting method for nding a zero of the sum of two operators, which is a modi cation of the classical forward-backward method proposed by Tseng. The conceptual algorithm proposed here improves Tseng's method in many instances. Our approach contains rstly an explicit Armijo-type line search in the spirit of the extragradient-like methods for variational inequalities. During the iterative process, the line search performs only one calculation of the forward-backward operator in each tentative for nding the step size. This achieves a considerable computational saving when the forward-backward operator is computationally expensive. The second part of the scheme consists of special projection steps bringing several variants.

This thesis focuses mainly on the Maximum Independent Set (MIS) problem. Some related graph theoretical combinatorial problems are also considered. As these problems are generally NP-hard, we study their complexity in hereditary graph classes, i.e. graph classes defined by a set F of forbidden induced subgraphs. We revise the literature about the issue, for example complexity results, applications, and techniques tackling the problem. Through considering some general approach, we exhibit several cases where the problem admits a polynomial-time solution. More specifically, we present polynomial-time algorithms for the MIS problem in: + some subclasses of $S_{2;j;k}$-free graphs (thus generalizing the classical result for $S_{1;2;k}$-free graphs); + some subclasses of $tree_{k}$-free graphs (thus generalizing the classical results for subclasses of P5-free graphs); + some subclasses of $P_{7}$-free graphs and $S_{2;2;2}$-free graphs; and various subclasses of graphs of bounded maximum degree, for example subcubic graphs. Our algorithms are based on various approaches. In particular, we characterize augmenting graphs in a subclass of $S_{2;k;k}$-free graphs and a subclass of $S_{2;2;5}$-free graphs. These characterizations are partly based on extensions of the concept of redundant set [125]. We also propose methods finding augmenting chains, an extension of the method in [99], and finding augmenting trees, an extension of the methods in [125]. We apply the augmenting vertex technique, originally used for $P_{5}$-free graphs or banner-free graphs, for some more general graph classes. We consider a general graph theoretical combinatorial problem, the so-called Maximum -Set problem. Two special cases of this problem, the so-called Maximum F-(Strongly) Independent Subgraph and Maximum F-Induced Subgraph, where F is a connected graph set, are considered. The complexity of the Maximum F-(Strongly) Independent Subgraph problem is revised and the NP-hardness of the Maximum F-Induced Subgraph problem is proved. We also extend the augmenting approach to apply it for the general Maximum Π -Set problem. We revise on classical graph transformations and give two unified views based on pseudo-boolean functions and αff-redundant vertex. We also make extensive uses of α-redundant vertices, originally mainly used for $P_{5}$-free graphs, to give polynomial solutions for some subclasses of $S_{2;2;2}$-free graphs and $tree_{k}$-free graphs. We consider some classical sequential greedy heuristic methods. We also combine classical algorithms with αff-redundant vertices to have new strategies of choosing the next vertex in greedy methods. Some aspects of the algorithms, for example forbidden induced subgraph sets and worst case results, are also considered. Finally, we restrict our attention on graphs of bounded maximum degree and subcubic graphs. Then by using some techniques, for example ff-redundant vertex, clique separator, and arguments based on distance, we general these results for some subclasses of $S_{i;j;k}$-free subcubic graphs.

Cette thèse concerne l’existence et la régularité de solutions d’équations non-linéaires elliptiques, d’équations paraboliques et d’équations de Hesse avec mesures, et les critères de l’existence de solutions grandes d’équations elliptiques et paraboliques non-linéaires. / This thesis is concerned to the existence and regularity of solutions to nonlinear elliptic, parabolic and Hessian equations with measure, and criteria for the existence of large solutions to some nonlinear elliptic and parabolic equations.

Approved for public release; distribution is unlimited / OFDM systems have experienced increased attention in recent years and have found applications in a number of diverse areas including telephone-line based ADSL links, digital audio and video broadcasting systems, and wireless local area networks (WLAN). Orthogonal frequency-division multiplexing (OFDM) is a powerful technique for high data-rate transmission over fading channels. However, to deploy OFDM in a WLAN environment, precise frequency synchronization must be maintained and tricky frequency offsets must be handled. In this thesis, various techniques to improve the data throughput of OFDM WLAN are investigated. A simulation tool was developed in Matlab to evaluate the performance of the IEEE 802.11a physical layer. We proposed a rapid time and frequency synchronization algorithm using only the short training sequence of the IEEE 802.11a standard, thus reducing the training overhead to 50%. Particular attention was paid to channel coding, block interleaving and antenna diversity. Computer simulation showed that drastic improvement in error rate performance is achievable when these techniques are deployed. / Lieutenant, Hellenic Navy

Serviceevolution erlaubt es, einen Service durch einen anderen Service zu verfeinern oder zu ersetzen. Der Austausch durch einen anderen Service sollte garantieren, dass alle oder ausgewählte Partner des Originalservices erhalten bleiben. In dieser Arbeit entwickeln wir einen Ansatz welcher einem Serviceentwickler helfen soll, Analyse- und Syntheseaufgaben für den Serviceaustausch so durchzuführen, dass jeder Partner eines gegebenen Services beim Austausch erhalten bleibt. Wir modellieren einen Kontrollfluss eines Services als Beschreibung der Reihenfolge von asynchron kommunizierenden Ereignissen mittels eines impliziten ungeordneten Nachrichtenspeichers. Weiterhin studieren wir den Verhaltensaspekt von korrekter Interaktion zwischen Services und konzentrieren uns auf zwei Varianten von Verklemmungsfreiheit als Korrektheitskriterien von Serviceersetzung. Der wichtigste Beitrag ist ein Ansatz zur Charakterisierung jedes möglichen Austausches eines gegebenen Services. Die zentrale Idee dieses Ansatzes ist eine systematische Untersuchung der Verbindung zwischen einem Service und all seiner Partner bzgl. eines gegebenen Korrektheitskriteriums. Wir nutzen diese Verbindung um von einem gegebenen Service einen kanonischen Partner und einen kanonischen Austausch bzgl. aller Partner zu synthetisieren. Ein Service welcher den kanonischen Austausch eines gegebenen Services verfeinert wird als Austausch des gegebenen Services angesehen, wenn die Menge all seiner Partner jeden Partner des gegebenen Services enthält. Mit dem kanonischen Austausch eines gegebenen Services identifizieren wir die Menge der möglichen austauschenden Services eines gegebenen Services bei der jeder exakt die gleichen Partner wie der gegebene Service hat. Einige Ergebnisse dieser Arbeit fundieren auf früheren Arbeiten zu Austausch und Korrektheit von Services und können daher mit diesen verbunden werden um schwierigere Analyse- und Syntheseaufgaben für den Serviceaustausch durchzuführen. / Service evolution allows one service to be refined into or substituted by another service. Substituting one service by another service should guarantee to preserve all or selected partners of the original service. In this thesis, we develop an approach that shall assist a service designer, such as a domain expert, to perform analysis and synthesis tasks on service substitution. We model a control flow of services that describes the ordering of asynchronously communicating events over an implicit unordered message buffer. We study the behavioral aspect of correct interaction between services and concentrate on two variants of deadlock freedom as correctness criteria of service substitution. The major contribution of this thesis is an approach for characterizing the set of all substitutes for a given service. We systematically investigate the relationship between a service and all its partners under a given correctness criterion and employ this relationship to synthesize from a given service its canonical partner and its canonical substitute with respect to all partners. A service that refines the canonical substitute for a given service is regarded as a substitute for the given service if the set of all its partners includes every partner of the given service. With the canonical substitute of a given service, we identify a specific subset of the set of all substitutes for the given service, each of which has exactly the same set of partners as that of the given service. Parts of the results in this thesis have been established upon previous works on service substitution and correctness of services. Consequently, we can also combine our results with the related existing techniques to perform more sophisticated analysis and synthesis tasks on service substitution.

A semigroup is simply a set with an associative binary operation; computational semigroup theory is the branch of mathematics concerned with developing techniques for computing with semigroups, as well as investigating semigroups with the help of computers. This thesis explores both sides of computational semigroup theory, across several topics, especially in the finite case. The central focus of this thesis is computing and describing maximal subsemigroups of finite semigroups. A maximal subsemigroup of a semigroup is a proper subsemigroup that is contained in no other proper subsemigroup. We present novel and useful algorithms for computing the maximal subsemigroups of an arbitrary finite semigroup, building on the paper of Graham, Graham, and Rhodes from 1968. In certain cases, the algorithms reduce to computing maximal subgroups of finite groups, and analysing graphs that capture information about the regular I-classes of a semigroup. We use the framework underpinning these algorithms to describe the maximal subsemigroups of many families of finite transformation and diagram monoids. This reproduces and greatly extends a large amount of existing work in the literature, and allows us to easily see the common features between these maximal subsemigroups. This thesis is also concerned with direct products of semigroups, and with a special class of semigroups known as Rees 0-matrix semigroups. We extend known results concerning the generating sets of direct products of semigroups; in doing so, we propose techniques for computing relatively small generating sets for certain kinds of direct products. Additionally, we characterise several features of Rees 0-matrix semigroups in terms of their underlying semigroups and matrices, such as their Green's relations and generating sets, and whether they are inverse. In doing so, we suggest new methods for computing Rees 0-matrix semigroups.