Les rivières sont un réservoir biologique et source de développement pour les sociétés humaines. À cause de l’étroite relation entre les Hommes et les écosystèmes fluviaux, elles furent identifiées comme un système socio-écologique. Hors, il s’effondre suite à l’exploitation intensive des services écosystémiques, à l’urbanisation croissante, et à la gestion de la ressource en eau priorisant la protection des biens, des usages et des personnes aux formes et fonctions des écosystèmes. Ces cinquante dernières années furent marquées par de nombreuses actions de restauration réalisées pour rétablir la qualité écologique et sociale des rivières. En Europe, la Directive Cadre sur l’Eau ratifiée en 2000 organise l’effort européen de restauration et demande l’atteinte du bon état ou potentiel écologique de toutes les masses d’eau des pays membres. Les rivières urbaines sont fortement affectées par l’impact anthropique mais leur restauration est particulièrement difficile. Alors que la science de la restauration évolue par les expériences passées, peu de connaissance existent sur les pratiques urbaines. Cette étude a pour objectif (1) d’identifier les différentes pratiques de la restauration et leurs forces motrices en mettant en avant les particularités des restaurations en milieu urbain. Et (2) d’évaluer les conflits au sein du système socio-écologique, notamment entre protection environnementale et usage récréatif et productif. / Rivers are hotspots for biological diversity and sources of ecosystem services. Because of the close interactions between riverine ecosystems and human activities, rivers are recognized as a socio-ecological system. Centuries of intensive exploitation of the ecosystem services, urbanization, and water management focusing on the use of water and safeguarding humans from floods and diseases, rather than on ecological health, have led to severe degradations and functional losses. In recent years, restoration has been recognized as essential to reestablish the quality of the rivers and an increasing number of restoration projects have been implemented. In Europe, the Water Framework Directive orchestrates restoration efforts, and demands that all water bodies achieve their good ecological status or potential. In urban areas, most rivers are heavily impacted by human activities and social demand for restoration is high. However, little knowledge exists about urban restoration practices. This research aims (1) to identify the different restoration practices and drivers, and examine the particularities of urban river restorations, and (2) to assess the potential conflicts inside the socio-ecological system. / Flüsse sind ein Hotspot für biologische Artenvielfalt und Erbringer vieler Ökosystemleistungen. Aufgrund der engen Wechselbeziehungen zwischen Flussökosystemen und menschlichen Aktivitäten werden sie als sozio-ökologische Systeme verstanden. Jahrhunderte massiven Nutzungsdrucks, Urbanisierung und eine Gewässerbewirtschaftung, die sich viel mehr der Versorgung der Menschen und dem Schutz derer vor Überschwemmungen und Krankheiten anstatt der Wahrung des ökologischen Gleichgewichts verschrieben hat, haben zu starken Zerstörungen und Funktionsverlusten dieser Ökosysteme geführt. In jüngster Zeit wurde die Notwendigkeit der Renaturierung von Flüssen zur Wiederherstellung ihrer Qualität erkannt und eine wachsende Zahl an Renaturierungsprojekten wurde realisiert. In Europa koordiniert die Wasserrahmenrichtlinie (Water Framework Directive, WFD) entsprechende Bemühungen und verlangt, dass alle Gewässer eine guten ökologischen Zustand oder ein gutes ökologisches Potenzial erreichen. In städtischen Gebieten sind die meisten Flüsse stark durch menschliche Aktivitäten geprägt und der Bedarf nach Renaturierungsmaßnahmen hoch. Dennoch gibt es nur wenige Kenntnisse über die Praktiken von Flussrenaturierungen in Städten. Diese Studie hat sich zum Ziel gesetzt (1) unterschiedliche Renaturierungspraktiken und deren Triebkräfte zu identifizieren und die Besonderheiten städtischer Flussrenaturierungen zu untersuchen und (2) die potenziell möglichen Interessenskonflikte im sozio-ökologischen System zu bewerten. / 河流是生物多样性研究的热点和诸多生态系统服务的来源。由于河岸生态系统与人 类活动的密切相互作用，使得河流通常被认为是一种社会生态系统。几个世纪以来，生 态系统服务的集约利用、城市化和水资源管理主要关注于水资源的有效利用和保障人类 免受洪水和疾病的危害而往往忽视了生态健康，从而导致了严重的生态退化和功能的丧 失。近年来，河流修复被公认为重建河流质量的必要手段并且越来越多的修复项目开始 付诸实施。在欧洲，欧盟水框架指令对水资源的修复工作进行策划统筹，并对所有水体 需达到的生态状况或生态潜力提出了高的要求。在城市地区，绝大多数的河流深受人类 活动的影响并且对于河流修复的社会需求较高。然而，关于城市河流修复实践的相关知 识还非常缺乏。本研究旨在：（1）区分不同的河流修复实践项目及其驱动力，以及研究 城市河流修复的特殊性；（2）并对这一社会生态系统中存在的潜在冲突进行评估。

Submitted by Cleide Dantas (cleidedantas@ufpa.br) on 2014-04-16T17:23:58Z No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_EfeitoCasimirTeorias.pdf: 1018987 bytes, checksum: f1ced51a26e1eb8cb3e7710612ccea68 (MD5) / Approved for entry into archive by Ana Rosa Silva (arosa@ufpa.br) on 2014-06-14T13:15:31Z (GMT) No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_EfeitoCasimirTeorias.pdf: 1018987 bytes, checksum: f1ced51a26e1eb8cb3e7710612ccea68 (MD5) / Made available in DSpace on 2014-06-14T13:15:32Z (GMT). No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_EfeitoCasimirTeorias.pdf: 1018987 bytes, checksum: f1ced51a26e1eb8cb3e7710612ccea68 (MD5) Previous issue date: 2011 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nesta dissertação obtemos a força de Casimir a temperatura finita entre duas linhas paralelas sujeitas a condição de fronteira do tipo linhas mistas, no contexto da teoria de Maxwell- Chern-Simons em (2+1) dimensões. Além disso, analisamos a simetria de inversão de temperatura apresentada pela energia livre de Helmholtz do modelo para diferentes condições de fronteira. Iniciamos estudando aspectos gerais do formalismo de Matsubara no intuito de introduzirmos efeitos térmicos na teoria; também analisamos aspectos gerais da teoria de MCS em (2 + 1) dimensões. Posteriormente, revisitamos o cálculo da força de Casimir para o caso de duas linhas paralelas infinitamente permeáveis magneticamente a temperatura nula e finita, bem como o caso de linhas mistas a temperatura nula, onde tomamos uma linha perfeitamente condutora eletricamente e outra infinitamente permeável magneticamente. Em seguida, apresentamos novos resultados envolvendo a força de Casimir a temperatura finita com condições de fronteira do tipo linhas mistas. Por último, analisamos a simetria de inversão de temperatura associada a energia livre de Helmholtz do modelo, mostrando que mesmo para condições mistas e possível obter uma espécie de simetria residual, em analogia a resultados existentes para a eletrodinâmica em (3+1) dimensões. / In this work we study the Casimir force for Maxwell-Chern-Simons (MCS) theories in (2+1) dimensions. In particular for the bidimensional case, we consider di erent boundary conditions and present new results concerning the in uence of the temperature in the phenomenon. We also analyse the Temperature Inversion Symmetry, considering both the massless and massive cases. We start by studying general aspects from Matsubara formalism with the goal of introduce thermal e ects in the theory; we also analyse general aspects of (2+1)-dimensional MCS theory. Then, we review the Casimir force for the in nite magnetically permeable lines at both zero and nite temperature, as well as the mixed lines at zero temperature, for which we take one line in nite magnetically permeable and the other perfect conducting. We next present new results concerning the Thermal Casimir force for the case of mixed lines. Finally, we analyse the Temperature Inversion Symmetry associated with the Helmholtz free energy, showing that even for the mixed lines boundary conditions it is still possible to de ne a residual symmetry, the result being analogous to previous results for the eletrodynamics in (3+1) dimensions.

Casimir forces originating from vacuum fluctuations of the electromagnetic fields are of increasing importance in many scientific and technological areas. The manifestations of these long-range forces at the nanoscale have led to the need of better understanding of their contribution in relation to the stability of different physical systems as well as the operation of various technological components and devices. This dissertation presents mathematical and theoretical methods to calculate the Casimir interaction in various infinitely long cylindrical nanostructures. A dielectric-diamagnetic cylindrical layer immersed in a medium is first considered. The layer has a finite thickness characterized with specific dielectric and magnetic properties. Another system considered is that of perfectly conducting concentric cylindrical shells immersed in a medium. The electromagnetic energy between two infinitely long straight parallel dielectric-diamagnetic cylinders immersed in a medium is also considered. The mode summation method is used to calculate the Casimir energy of all these systems. The energy dependence on the cylindrical radial curvature and dielectric response of the cylinders is investigated. The fundamental effects of these long range interactions are studied in the form of exciton-plasmon interactions in carbon nanotubes and this is achieved by looking at the dielectric response of carbon nanotubes.

Cette habilitation traite des transferts de chaleur et de quantité de mouvement aux courtes échelles d'espace et de temps. Une première partie du travail s'interesse au propriétés du rayonnement thermique en champ proche. Il est montré qu'en présence de matériaux supportant des ondes de surface, le champ électromagnétique d'origine thermique peut voir ses propriétés de cohérence changées entre le champ proche et le champ lointain, en particulier lorsque les matériaux mis en jeu supportent des ondes de surface. Nous montrans que le transfert radiatif en champ proche peut être augmenté de plusieurs ordreds de grandeur en champ proche en présence d'ondes de surface. Les propriétés de cohérence du champ thermique en champ proche peuvent être exploitées pour fabriquer des sources thermiques cohérentes en champ lointain. Ce type de source s'obtient en gravant un réseau à la surface de matériaux.<br />Dans une seconde partie nous avons montré que la force de Casimir qui est un transfert de moment pouvait s'interpéter comme un transfert s'effectuant à certaines longueurs d'ondes correspondant aux modes propres du systèmes. Dans ces deux parties, les calculs ont été effectuées en utilisant une méthode basé sur le théorème de fluctuation dissipation.<br />Dans une troisième partie, nous traitons le problème de la conduction thermique aux courtes échelles de temps et d'espace. Nous montrons que la loi de Fourier cesse d'être valable et nous résolvons pour traiter ces problèmes l'équation de Boltzmann pour les phonons.

Ce mémoire résume mon activité de recherche de 1990 à 2002. Les travaux portent sur les sujets suivants:<br />Coopérativité et corrélations dans les états atomes-champ<br />Réduction du bruit quantique par la superrradiance à deux photons<br />Atomes froids et fluctuations quantique<br />Condensation de Bose Einstein<br />Effets mécaniques des fluctuations du vide<br />Effet Casimir<br />Décohérence due ondes gravitationnelles

I review the construction of Hertz potentials in vector calculus starting from Maxwell's equations. From here, I lay the minimal foundations of differential geometry to construct Hertz potentials for a general (spatially compact) Lorentzian manifold with or without boundary. In this general framework, I discuss "scalar" Hertz potentials as they apply to the vector calculus situation, and I consider their possible generalization, showing which procedures used by previous authors fail to generalize and which succeed, if any. I give specific examples, including the standard at coordinate systems and an example of a non-flat metric, specifically a spherically symmetric black hole. Additionally, I generalize the introduction of gauge terms, and I present techniques for introducing gauge terms of arbitrary order. Finally, I give a treatment of one application of Hertz potentials, namely calculating electromagnetic Casimir interactions for a couple of systems.

Scientific development requires profound understandings of micromechanical and nanomechanical systems (MEMS/NEMS) due to their applications not only in the technological world, but also for scientific understanding. At the micro- or nano-scale, when two objects are brought close together, the existence of stiction or adhesion is inevitable and plays an important role in the behavior operation of these systems. Such effects are due to surface dispersion forces, such as the van der Waals or Casimir interactions. The scientific understanding of these forces is particularly important for low-dimensional materials. In addition, the discovery of materials, such as graphitic systems has provided opportunities for new classes of devices and challenging fundermental problems. Therefore, invesigations of the van der Waals or Caismir forces in graphene-based systems, in particular, and the solution generating non-touching systems are needed. In this study, the Casimir force involving 2D graphene is investigated under various conditions. The Casimir interaction is usually studied in the framework of the Lifshitz theory. According to this theory, it is essential to know the frequency-dependent reflection coefficients of materials. Here, it is found that the graphene reflection coefficients strongly depend on the optical conductivity of graphene, which is described by the Kubo formalism. When objects are placed in vacuum, the Casimir force is attractive and leads to adhesion on the surface. We find that the Casimir repulsion can be obtained by replacing vacuum with a suitable liquid. Our studies show that bromobenzene is the liquid providing this effect. We also find that this long-range force is temperature dependent and graphene/bromobenzene/metal substrate configuration can be used to demonstrate merely thermal Casimir interaction at room temperature and micrometer distances. These findings would provide good guidance and predictions for practical studies.

Stuttgart, Univ., Diss., 2008.

Thesis (Ph.D.)--University of Western Sydney, 2008. / A thesis submitted to the University of Western Sydney, College of Health and Science, School of Biomedical and Health Sciences in fulfilment of the requirements for the degree of Doctor of Philosophy. Includes bibliographical references.

Thesis (Ph.D)--Baylor University, 2008. / Includes bibliographical references (p. 120-133)