Les caoutchoucs utilisés dans les applications d’ingénierie sont souvent sollicités cycliquement et présentent une réponse thermomécanique complexe dépendante du temps. Établir le couplage entre les différents phénomènes inélastiques, apparaissant généralement ensemble au cours de l’historique du chargement cyclique, est une question ouverte à résoudre. Cette thèse est dédiée à la formulation et à la vérification expérimentale de modèles de comportement thermomécaniques pour les caoutchoucs. Le mémoire de thèse est divisé en deux parties. La première partie est axée sur les caoutchoucs renforcés par du noir de carbone. Les effets du pré-étirement et de la teneur en noir de carbone sur la réponse cyclique d'un caoutchouc synthétique représentatif (SBR) sont analysés qualitativement et quantitativement à l'aide de la théorie des variables internes. Une interprétation des mécanismes physiques sous-jacents est proposée dans laquelle deux types de réarrangements dissipatifs du réseau de chaînes sont considérés, à savoir les réarrangements recouvrables induisant une viscoélasticité et les réarrangements non recouvrables induisant un endommagement. Afin de prédire l'ensemble des principaux effets inélastiques (l’adoucissement de la contrainte induit par la fatigue et l’hystérésis ainsi que la dissipation thermique), nous avons formulé un nouveau modèle constitutif thermo-viscoélastique endommageable basé sur la théorie des variables internes. Le modèle constitutif proposé est implémenté dans un code éléments finis et des applications numériques sur des structures en caoutchouc sont effectuées. Les capacités prédictives du modèle sont vérifiées par des comparaisons avec nos observations expérimentales. La seconde partie est consacrée aux caoutchoucs cristallisables par étirement. Nous avons développé un nouveau modèle physiquement fondé inspiré du micro-mécanisme pour décrire l'évolution progressive du degré de cristallinité dans les caoutchoucs et leur réponse thermomécanique dépendante du temps dans le contexte de la thermodynamique des processus irréversibles. Dans ce modèle, la configuration moléculaire d’une chaîne partiellement cristallisée est analysée et calculée au moyen de certaines méthodes mécaniques statistiques. Notre approche est implémentée dans le modèle micro-sphère dans le but d'introduire l'anisotropie et la dissipation induites par la cristallisation d’un réseau de chaînes. Le modèle constitutif proposé est ensuite utilisé pour discuter certains aspects importants du micro-mécanisme et de la réponse macroscopique à l'état d'équilibre et à l'état non équilibré pendant l'étirement/la recouvrance/la relaxation continue. Les simulations du modèle sont également comparées aux données expérimentales à différents niveaux d'étirement et à différentes températures. Les champs locaux en termes d'anisotropie et de dissipation sont présentés à l'aide d'exemples numériques. / Establishing the coupling between the different inelastic phenomena, usually appearing together during the cyclic loading history, is an open issue to be addressed. The Phd report is divided into two parts. The first part is focused on filled rubbers. The effects of pre-stretch and filler content on the history-dependent cyclic response of a representative carbon-filled synthetic rubber (SBR) are qualitatively and quantitatively analyzed by using the internal state variable theory. An interpretation of the underlying physical mechanisms is proposed in which two types of dissipative network rearrangements are considered, i.e. recoverable rearrangements inducing viscoelasticity and unrecoverable rearrangements inducing damage. In order to predict the main set of inelastic fatigue effects (fatigue-induced stress-softening and hysteresis along with dissipative heating), we formulate a new thermo-viscoelastic-damage constitutive model based on the internal state variable theory. The proposed constitutive model is implemented into a finite element program and numerical applications on rubber structures are performed. The predictive capabilities of the model are verified by comparisons with our experimental observations. The second part is focused on stretch-induced crystallizable rubbers. We develop a new micro-mechanism inspired molecular chain model to describe the progressive evolution of the crystallinity degree in rubbers and the history-dependent thermo-mechanical response within the context of the thermodynamic framework. In this model, the molecular configuration of the partially crystallized single chain is analyzed and calculated by means of some statistical mechanical methods. Our approach is implemented into the micro-sphere model in the aim to introduce the crystallization-induced anisotropy and dissipation. The proposed constitutive model is then used to discuss some important aspects of the micro-mechanism and the macro-response under the equilibrium state and the non-equilibrium state involved during stretching/recovery/continuous relaxation. The model simulations are also compared to experimental data at different stretch levels and temperatures. Local fields in terms of anisotropy and dissipation are presented on illustrative numerical examples.

Constitutive rhetoric focuses on the idea that in times of historical crisis, speakers possess the ability to repair the language of the community and reshape the identity of the community. This dissertation relies upon the concept of constitutive rhetoric to examine the Supreme Court’s reapportionment and redistricting decision. By employing constitutive rhetoric, the Supreme Court reacts to the crisis of representation because of malapportionment and redistricting to transform our Constitutional republic to a Constitutional democracy and, further, to debate competing visions of representation and democracy necessary to sustain political life and the democratic experience. Chapter I offers readers a literature review on constitutive rhetoric, a literature review on reapportionment and redistricting, and presents readers with an outline of the dissertation. Chapter II provides a brief history of redistricting in the United States since Colonial times, the development of apportionment and redistricting law at the state court level, and the Supreme Court’s invention of a rhetorical tradition in apportionment and districting law before the Reapportionment Revolution. In the last section of Chapter II, I argue that the Pre-Revolution Supreme Court cases weakened the authority of the rhetorical tradition of judicial deferment. Chapter III examines the Supreme Court’s decision in Baker v. Carr, which reconstitutes the authority of the judiciary in apportionment and redistricting law by redefining the meaning of voting rights and the political questions doctrine, as well as reconceptualizing the law behind voting rights. Further, this chapter outlines the new role of the judiciary in American society and the ethos of judicial restraint that is to guide apportionment and redistricting cases. Chapter IV examines the development of the new rhetorical tradition in apportionment law from the Reapportionment Revolution cases of Gray v. Sanders, Wesberry v. Sander, Reynolds v. Sims, and the rest of the Supreme Court cases form the 1960s. In this new rhetorical tradition, the Supreme Court reconstitutes the American republican to create a legal and moral American democracy, a form of government that rests on the development of the democratic experience and the expansion of the right to vote at the local, state, and federal level. Chapter V examines the Supreme Court cases during the 1970s and the 1980s where, because of their ideological divisions, the Justices offer the American people competing visions of representation and democracy in an attempt to gain interpretive dominance for their visions. Finally, Chapter VI examines the Supreme Court’s decisions from the 1990s and 2000s. In these decisions, the Justices debate the best means to achieve racial reconciliation through apportionment and redistricting law and the best formation of democracy to secure that reconciliation.

Asphalt bound mixtures have been put to diverse uses. The complicated nature of the material and the demanding conditions under which it is used preclude complete solutions to questions on load bearing capability under field conditions. In proportion to the quantity of its usage and in acknowledgment of modeling complexity, the material has been interrogated by many researchers using a variety of mechanical tests, and a plethora of linear viscoelastic models have been developed. Most models are intended to account for specific classes of problems. This work addresses the conspicuous absence of systematic documentation of normal forces generated as a result of shear. The normal force generated during simple shear is a clear indication of the nonlinear nature of the material. The effect of fillers (hydrated lime and limestone), air voids, aggregate gradation, asphalt source and step loading on normal force generation during torsion is experimentally investigated. Based on experimental evidence, a non-linear thermomechanical model for sandasphalt mixtures based on the idea of multiple natural configurations is developed. The model accounts for the fact that the mixture has a natural configuration (stressfree configuration) which evolves as it is subjected to loads. Assumptions are made regarding the manner in which the material stores and dissipates energy. A key assumption is that among the various constitutive relations possible, the one that is chosen is the one that maximizes the rate of entropy production. The model that is developed accounts for the anisotropic nature of the response. The experimental results show that asphalt bound mixtures generate significant normal forces even at low rotation rates. The source of asphalt, aggregate gradation, fillers and air voids have a pronounced effect on normal stress generation. The model is corroborated against data from torsion experiments.

A study is made of the problem of metamaterial homogenization, which is the attempt to represent an artificially fabricated inhomogeneous periodic structure as a homogeneous medium with an electromagnetic response described by a number of constitutive parameters (permittivity, permability, etc.) In particular, the importance of spatial dispersion in metamaterials and the need to characterize metamaterials with wavevector dependent constitutive parameters is explained an examined. A brief survey of important previous attempts at metamaterial homogenization is presented. This is followed by a discussion of spatial dispersion in metamaterial crystals. The importance of spatial dispersion in metamaterials is justified and some manifestations of spatial dispersion described. In particular the little known phenomenon of bianisotropy in centrosymmetric crystals due to spatial dispersion is explained. Also, the effects of spatial dispersion on physical quantities such as energy flux and dissipation are identified. We then describe a new method for solving for the free eigenmodes of a metamaterial crystal with a complex wavevector eigenvalue simulation. Next, two different theoretical attempts by the author at metamaterial homogenization are described, both accompanied by tests of the calculated constitutive parameters and critical examination of the strengths and weaknesses of each approach. Finally, strong evidence of the presence and importance of spatial dispersion in metamaterials is presented. / text

It is widely recognised that the development and optimisation of industrial processes such as extrusion or injection moulding significantly benefit from accurate polymer processing simulations. Such simulations can lead to enormous cost savings, time to market and product improvements. The development of suitable constitutive models and a robust numerical algorithm are required for successful application of such tool to these processes. Appropriate material characterisation is also imperative to select the constitutive model parameters. Despite the importance and maturity of the polymer processing industry, the constitutive modelling of the rheological behaviour of long chain branched polymers presents still fascinating questions that need some answers. A breakthrough in this area was the design of a constitutive equation based on molecular arguments and known as the pom-pom model. The key feature of this model is the presence of separate relaxation times for the orientation and stretch mechanisms. The pompom model has been proved to be very accurate for the modelling of long chain branched polymers in rheometrical flows. Although very promising, this model suffers from numerical and rheological defects that hinder its use in complex flow simulations. To overcome these issues, the Double Convected pom-pom (DCPP) model is proposed. Its predictive capabilities are first analysed in various rheometrical flows including reverse multi-step shear strain and large amplitude oscillatory shear experiments. For complex flow simulation, the DCPP model is implemented in the commercial package POLYFLOW.Model predictions are compared to experimental birefringence data in planar contraction flows. In all cases, a satisfactory agreement is found between numerical simulation and experiments, demonstrating the potential of this model for the simulation of polymer processing operations. The simulations are then extended to three-dimensional geometries. The influence of non-perfectly two-dimensional flows on birefringence data is analysed. It is shown that the impact of these imperfections is strongly dependent on the flow rate. Is is commonly believed that increasing the geometry aspect ratio tends to decrease three-dimensional influence. It is demonstrated that this is verified only if the zero-order fringe does not disappear at any time during the experiment. Finally, a pragmatic approach is introduced to reformulate constitutive equations to explicitly express them in terms of orientation and stretch variables. This procedure is applied to the Phan-Thien Tanner and Giesekus models and both modelsare compared to the DCPP model. Comparing the models in this form, highlights their differences, and allows one to adopt the best features of each. This almost naturally leads to a proposal of a number of modifications to each of these models. The modified models are then assessed in rheometrical flows by comparing model predictions to experimental data. Significant improvements are demonstrated for in particular the Modified Giesekus model and the Modified DCPP: both models perform remarkably well in a range of non-linear rheometric flows, and are therefore promising candidates for predicting industrial flow problems.

AN ABSTRACT OF THE DISSERTATION OF LAN HAI, for the Doctor of Philosophy degree in Molecular Cellular and Systemic Physiology, presented on 11th December, 2015 at Southern Illinois University Carbondale. TITLE: EFFECT OF CONSTITUTIVELY ACTIVATED LUTEINIZING HORMONE RECEPTOR ON THE MOUSE REPRODUCTIVE SYSTEM MAJOR PROFESSOR: Dr. Prema Narayan The luteinizing hormone/chorionic gonadotropin receptor (LHCGR) is crucial for fertility, and genetic mutations in LHCGR cause adverse effects in reproductive development. Among the activating mutations identified in LHCGR, replacement of aspartic acid 578 by glycine (D578G) is the most common inherited mutation. Boys with this mutation undergo puberty by 2-4 years, caused by elevated testosterone in the context of prepubertal luteinizing hormone levels and present with Leydig cell hyperplasia. Clinically, these symptoms are associated with familial male-limited precocious puberty (FMPP). Our lab has published a mouse model for FMPP (KiLHRD582G) with D582G mutation equivalent to D578G in human LHCGR. We have previously demonstrated that KiLHRD582G male mice exhibited precocious puberty, Leydig cell hyperplasia and elevated testosterone and was a good model for FMPP. However, unlike women with the D578G mutation who show no abnormal phenotype, our studies revealed that female KiLHRD582G mice were infertile. KiLHRD582G female mice exhibit precocious puberty and irregular estrous cyclicity. A temporal study from 2-24 weeks of age indicated elevated steroid levels and upregulation of steroidogenic acute regulatory protein as well as several steroidogenic enzyme genes. Ovaries of KiLHRD582G mice exhibited significant pathology with the development of large hemorrhagic cysts as early as 3 weeks of age, extensive stromal cell hyperplasia with luteinization, numerous atretic follicles and granulosa cell tumors. Anovulation could not be rescued by exogenous gonadotropins. The body weights of the KiLHRD582G mice was higher that wild type counterparts, but there were no differences in the body fat composition. Hyperandrogenism and polycystic ovary phenotype was not accompanied by impaired glucose tolerance. Blocking the androgen action and estrogen synthesis indicated that reproductive phenotype was primarily due to excess estradiol. These studies demonstrate that activating LHCGR mutations do not produce the same phenotype in humans and mice and clearly illustrates species differences in the expression and regulation of LHCGR in the ovary. As we use male KiLHRD582G mice as breeders, we observed that the KiLHRD582G mice became progressive infertile, and only 8% of KiLHRD582G were fertile at 6 months of age despite normal sperm production. The infertile KiLHRD582G males were not able to form copulatory plugs in WT females, and mating studies suggested that the KiLHRD582G males were not capable of mating and/or ejaculating. Sexual behavioral testing revealed that the infertile KiLHRD582G males were capable of mounting the receptive WT females but were unable to achieve ejaculation indicating a problem with erectile and/or ejaculatory function. To address the reason for the ejaculatory dysfunction, we performed histopathological analysis of the accessory glands and penis. Hematoxylin and eosin staining showed that the normal columnar epithelium was replaced by pseudostratified columnar epithelium in the ampulla and several aggregates of chondrocyte metaplasia were apparent in the penile body of KiLHRD582G male mice. A temporal study indicated the histopathological changes in ampulla and penile body initiated at 7-8 and 12 weeks of age, respectively. Immunohistochemistry indicated that the chondrocytes stained positive for collagen type II, SOX9 and androgen receptor in the nucleus and for LHCGR in the cytoplasm. Penile fibrosis is a major cause of erectile dysfunction and is characterized by an increased collagen/smooth muscle ratio. However, our Image J analysis, hydroxyproline assay and western blot showed that KiLHRD582G penile body exhibited reduced levels of smooth muscle actin but similar total collagen content compared to WT mice. Thus, penile fibrosis was not responsible for the progressive infertility of adult KiLHRD582G mice. We also observed Leydig cell adenoma and disruption of spermatogenesis at 1 year of age. Our results suggest FMPP patients may be susceptible to infertility and testicular tumors later in their life and a follow-up study of FMPP patients is recommended.

"The study is divided into five chapters. Chapter one provides the context in which the study is set, the focus and objectives of the study, its significance, and other preliminary issues including the hypothesis and literature survey. Chapter two first seeks to briefly portray the current state of human rights in Africa. In the second part, history and development of the African Union is traced, within the context of its predecessor - the OAU. Its third part extracts and analyses the specific human rights content of the AU Constitutionve Act and other relevant provisions, both independently and collectively; while its fourth part progresses to examine the conribution of the AU to human rights so far, by gauging and scrutinizing the human rights content of its summits. The fifth and final part scrutinizes the implications of the linkage of human rights to development and hence, its re-conceptualisation or otherwise, in Africa. Chapter three seeks to examine the extant implications of the AU human rights agenda on the existing human rights protection framework. First, it provides a brief overview of the existing regional human rights protection system, while its second part elucidates the human rights enforcement mechanisms that have been developed under the African Charter system. Its third part seeks to examine the problem of enforcement of, and non-compliance with human rights in Africa, with a view to understanding the problem, and forging a way forward. Its fourth part looks at the relationship between the AU and the existing human rights institutions within the context of the AU Constituve Act, while its concluding part addresses the latent risk of proliferation and redundancy that might attend the proposed creation of more human rights-oriented institutions under the AU/NEPAD; proposing rationalization of the same and the fusion of compatible mandates, with the view of avoiding unnecessary and expensive duplications. Chapter four seeks to present the probable picture of the fusion of the emerging and existing frameworks. Its first part sets out to describe, as well as explicate the justifications for the proposed human rights enforcement framework under the AU, citing models. Its second part seeks to explore the potentialities of trade as veritable tool of sanction within the proposed structure, while its concluding part seeks to do the same in relation to the device of peer pressure. The fifth and final chapter of the study seeks to draw some conclusions and further give recommendations on how the proposed hybrid framework can be achieved, while emphasizing the importance of such synergy as a feasible solution of the problem of human rights enforcement in Africa." -- Chapter 1. / Prepared under the supervision of Prof. J. Oloka-Onyango, Faculty of Law, Makerere University / Mini Dissertation (LLM (Human Rights and Democratisation in Africa))--University of Pretoria, 2003. / http://www.chr.up.ac.za/academic_pro/llm1/dissertations.html / Centre for Human Rights / LLM

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