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Thesis (MSc)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Active materials are a subset of soft matter that is constantly being driven out of an equilibrium state due to the energy input from internal processes such as the hydrolysis of adenosine triphosphate (ATP) to adenosine diphosphate (ADP), as found in biological systems. Firstly, we construct and study a simple model of a flexible filament with an active crosslinker/molecular motor. We treat the system on a mesoscopic scale using a Langevin equation approach, which we analyse via a functional integral approach using the Martin-Siggia-Rose formalism. We characterise the steady state behaviour of the system up to first order in the motor force and also the autocorrelation of fluctuations of the position of the active crosslink on the filament. We find that this autocorrelation function does not depend on the motor force up to first order for the case where the crosslinker is located in the middle of the contour length of the filament. Properties that characterise the elastic response of the system are studied and found to scale with the autocorrelation of fluctuations of the active crosslink position. Secondly, we give a brief overview of the current state of dynamical polymer network theory and then propose two dynamical network models based on a Cayley-tree topology. Our first model takes a renormalisation approach and derive recurrence relations for the coupling constants of the system. The second model builds on the ideas of an Edwards type network theory where Wick’s theorem is employed to enforce the constraint conditions. Both models are examined using a functional integral approach. / AFRIKAANSE OPSOMMING: Aktiewe stelsels is ’n subveld van sagte materie fisika wat handel oor sisteme wat uit ekwilibruim gedryf word deur middel van interne prossesse, soos wat gevind word in biologiese stelsels. Eerstens konstruëer en bestudeer ons ’n model vir ’n buigbare filament met ’n aktiewe kruisskakelaar of molekulêre motor. Ons formuleer die stelsel op ’n mesoskopiese skaal deur gebruik te maak van ’n Langevin vergelyking formalisme en bestudeer die stelsel deur gebruik te maak van funksionaal integraal metodes deur middel van die Martin-Siggia-Rose formalisme. Dit laat ons in staat om die tydonafhankle gedrag van die stelsel te bestudeer tot op eerste orde in die motorkrag. Ons is ook in staat om die outokorrelasie fluktuasies van die posisie van die aktiewe kruisskakelaar te karakteriseer. Ons vind dat die outokorrelasie onafhanklink is van die motorkrag tot eerste orde in die geval waar die kruisskakelaar in die middel van die filament geleë is. Die elastiese eienksappe van die sisteem word ook ondersoek en gevind dat die skaleer soos die outokorrelasie van die fluktuasies van die aktiewe kruisskakelaar posisie. Tweedens gee ons ’n vlugtige oorsig van die huidige toestand van dinamiese polimeer netwerk teorie en stel dan ons eie twee modelle voor wat gebasseer is op ’n Caylee-boom topologie. Ons eerste model maak gebruik van ’n hernormering beginsel en dit laat ons toe om rekurrensierelasies vir die koppelingskonstates te verkry. Die tweede model bou op idees van ’n Edwards tipe netwerk teorie waar Wick se teorema ingespan word om die beperkingskondisies af te dwing. Beide modelle word met funksionaal integraal metodes bestudeer.

New analytical and numerical solutions are developed to both the kinematic approximation to the St Venant equations and the Hairsine-Rose (HR) soil erosion model in order to gain a better physical understanding of soil erosion and sediment transport in shallow overland flow. The HR model is unique amongst physically based erosion models in that it is the only one that: considers the entire distribution of the soil s sediment size classes, considers the development of a layer of deposited non-cohesive sediment having different characteristics to the original underlying cohesive soil and considers separately the erosion processes of rainfall detachment, runoff entrainment and gravitational deposition. The method of characteristics and the method of lines were used to develop both the analytical and numerical solutions respectively. These solutions were obtained for boundary and initial conditions typical of those used in laboratory flume experiments along with physically realistic constant and time dependent excess rainfall rates. Depending on the boundary and initial conditions, interesting new solutions of the kinematic wave equation containing expansion waves, travelling shocks as well as solutions which split into an upslope and downslope drying profiles were found. Numerical solutions of the HR model were applied to the experimental flume data of Polyakov and Nearing (2003) obtained under flow conditions which periodically cycled between net erosion and net deposition conditions. While excellent agreement was found with suspended sediment data, the analysis suggested that an additional transport mechanisms, traditionally not included in soil erosion models, was occurring. While the inclusion of bed-load transport improved the ii overall model prediction, it was still not sufficient. Subsequent asymptotic analysis then showed that the interaction of the flow with an evolving bed morphology was in fact far more important than bed load transport. A very interesting finding from this work showed that the traditional criterion of validating sediment transport model based solely on suspended sediment data was not sufficient as reliable predictions could be obtained even when important transport mechanisms were neglected. Experimental plots of sediment discharge or suspended sediment concentration against water discharge in overland flow have been shown to contain significant hysteresis between the falling and rising limbs of the discharge hydrograph. In the final Chapter, the numerical solution developed for the complete system of soil erosion and kinematic flow was used to show that it was possible for the HR model to simulate three of the four hysteresis loops identified in the literature. Counter clock-wise loops, clock-wise loops and figure 8 loops could all be produced as a result of starting with different initial conditions, being mi(x; 0) = 0, mi(x; 0) = pimt and mi(x; 0) = 0:5pimt respectively. This is the first time that these types of hysteresis loops have been produced by any erosion model. The generation of these hysteresis loops are physically explainable in terms of sediment availability and is consistent with data obtained on the field scale.

My doctoral thesis is comprised of two bodies of research: two artworks taking the form of installations (videos, audio recordings, textiles, texts), which will be exhibited for viva. Femme Fabrications, 2016, is made from research into the American artist Joseph Cornell's (1903-1972) source materials held in the Smithsonian American Art Museum alongside research on Jean Wilkinson's 1977 book Flower Fabrications. A series of textile works encased in silk lined boxes trace my step-by-step construction of a rose from organdie. The floral emblem of the white rose (dried), 'death is preferable to a loss of innocence' , becomes an editing device, which I use to consider a number of possible recipients for the rose, such as Cornell himself. Spoken word audio recordings, which ruminate on how his sexuality pertain to the criteria of the rose are edited together with home-camcorder video footage of the house that Cornell lived in for most of his life - the house he made the entirety of his artworks within. Central to The Cesspool of Rapture, 2017, are moving-image studies of zippers, stains, rips, abrasions, openings, and closings in a series of dresses made by the American couturier Charles James (1906-1978). These videos register and move through the material research, the garments, at alternating speeds. The changing speed is registered in sound by clicks synced to each individual frame. It is at times violent and at other times tentative and gentle as the uncovering of the damage to the dresses unfolds. Audio recordings of James explicating his interests in eroticism and sexuality persistently interject the footage. This work includes the installation of a series of reconstructions of James's 1932 Taxi dress. Its black linen body is reconfigured and abstracted as the splayed design makes unfinished seams and unzipped zippers visible. In each artwork I configure viewing and consuming as a mode of authorship. I show how these diverse processes of identification become authored acts. When drawn into intimate relation with the leftover material of these historical authors, my contamination proves deviant: I gain possession of the capacity to speak for them, to expose, idolise, misrepresent, and fictionalise them. My thesis is composed of this group of methodologies, which were found and developed within the production of the artworks.

This thesis focuses on the ways in which cloth and clothwork are represented in Old French romance in order to highlight how they relate to feminine voice, expression, and identity. By focusing mainly on medieval romance from the twelfth and thirteenth centuries, the field of research is narrowed to a period in which vernacular literature was redefining literacy. On the basis that literacy is not confined to the ability to read and write in Latin, clothwork is presented as a medium of literate expression, that being a form of readable knowledge or communication not codified in written word or language, and in the works of such authors as Marie de France, Chrétien de Troyes, and Jean Renart, amongst others, the presentation of clothwork fits this classification. My research focuses on gendered performance and gendered objects highlighting the divide between masculinity and femininity in materiality. Beginning with a contextualised and historical understanding of feminine clothwork, authority, and gendered biases in the Middle Ages in France, the Virgin Mary's associations with clothwork leads into an exploration of how the identities of women are tied to the cloth that they work or possess. From this basis, feminine voice in clothwork comes to the forefront of discussion as seemingly inaudible women make themselves heard through the use of needles and thread, telling their stories in cloth and tapestry. Throughout this study, an exploration of mother-daughter relationships is highly significant to the comprehension of feminine education and tradition in clothwork. The chansons de toile included in Le Roman de la Rose ou de Guillaume de Dole by Jean Renart underline the dichotomy and tension between oral and written culture, tying feminine voice to feminine clothwork and exploring the representation of this in the written text. Finally, Christine de Pizan's intimation of the importance of feminine tasks and brilliance concludes this study in order to better understand the ways in which the literature of the Late Middle Ages and Renaissance departs from the medieval presentation of clothwork as a typically feminine activity underlying and encapsulating a woman's identity and expressive power.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / O presente trabalho buscou verificar (1) a importÃncia relativa dos principais grupos de artrÃpodes pragas que tÃm ocorrido na cultura da roseira nas diferentes regiÃes produtoras de flores no estado do Cearà e identificar a praga chave para este cultivo; (2) analisar as metodologias de cÃlculo de Ãndices tecnolÃgicos na floricultura e propor um modelo de avaliaÃÃo especÃfico para identificaÃÃo do nÃvel tecnolÃgico do controle de pragas para esta atividade, verificando o posicionamento dos produtores em relaÃÃo aos nÃveis de integraÃÃo (NI) do manejo integrado de pragas (MIP). Para determinar a importÃncia relativa dos artrÃpodes praga da roseira no estado do Cearà foram entrevistados consultores, especialistas e tÃcnicos de reconhecida atuaÃÃo na Ãrea de floricultura no estado, tendo o estudo abrangido a regiÃo da Ibiapaba (principal agropÃlo produtor), MaciÃo de Baturità e o Cariri. O modelo proposto para avaliaÃÃo do nÃvel tecnolÃgico do controle de pragas na floricultura foi aplicado numa amostra de 14 pequenos, mÃdios e grandes produtores que cultivavam diferentes espÃcies de flores de corte e plantas ornamentais. Para verificar a eficÃcia do mÃtodo em uma cultura especifica fez-se um estudo de caso para a roseira sob sistema de cultivo protegido em SÃo Benedito, regiÃo da Ibiapaba. A principal praga apontada para todas as regiÃes foi o Ãcaro rajado, Tetranychus urticae, sendo esta considerada a praga chave para a cultura da roseira no estado do CearÃ. A importÃncia relativa dos demais grupos de artrÃpodes variou de acordo com cada regiÃo de produÃÃo, tendo o tripes e os afÃdeos ficado em 2 lugar no Cariri e em BaturitÃ, respectivamente. Considerando o estado como um todo o segundo grupo de maior importÃncia foram os afÃdeos. Atribuiu-se esse fato as diferentes formas de manejo, grau de especializaÃÃo dos produtores e fatores ambientais. Em relaÃÃo ao nÃvel tecnolÃgico do controle de pragas os produtores obtiveram pontuaÃÃes que variaram de 3 a 78, indicando que eles utilizavam de 3 a 78% das tecnologias bÃsicas para o controle de pragas. TambÃm foi verificado que esse percentual aumentou conforme o grau de profissionalismo e assistÃncia tÃcnica recebida pelos produtores, bem como em funÃÃo da especializaÃÃo dos funcionÃrios contratados. A mÃdia das pontuaÃÃes da amostra em teste foi de 28 pontos ou 28% de uso das tÃcnicas de controle, o que de acordo com a escala proposta coloca o nÃvel tecnolÃgico do controle de pragas na floricultura no padrÃo E, o menor da escala. A cerca do nÃvel de integraÃÃo 92,86% dos produtores nÃo atingiram o primeiro nÃvel do MIP, o que mostra que esse resultado està em harmonia com a avaliaÃÃo do nÃvel tecnolÃgico do manejo de pragas.

This thesis presents a conceptual examination of the modernist director read through Gillian Rose's speculative lenses of the 'broken middle'. Highlighting the significance of speculative philosophy, I explore the meaning of the director as a mediating subjectivity. I demonstrate how a speculative reading of the director can act as a corrective to the received totalitarian, despotic image of the director. I urge for the rehabilitation of the director as a history and as a practice and I propose the emergence of this figure as being the outcome of a complex theatrical articulation entangled with the discipline of philosophy. Combining close readings of philosophical texts by Rose, Plato, Castoriadis, Badiou, Rancière, Laclau and Mouffe, among several other intellectual references in this study, I explore the director as a mode or trope of embodied philosophy. My argument also proposes the director as an Event, in Badiou's definition, and I trace this configuration as already taking place with the 'tragic' paradigm of the Athenian theatre. This Event of the director, I then argue, gets fully inaugurated in modernism as the Event of thought in theatre. I explore how the director acting as a mediator transforms theatre to what Puchner calls 'a theatre of ideas' while simultaneously philosophy becomes itself transformed to a theatre of thought. Chapter 1 outlines the key strands of Rose's thought and sets out the theoretical parameters of my examination. The chapter argues for a speculative reading of the director cross-examined with current positions within theatre historiography. The chapter paves a new understanding of the director, not historically, but conceptually, as a mode of embodied thought. Chapter 2 explores the relationship between the primacy and centrality of the aesthetic paradigm of theatre in philosophy and the role and practice of the poet - or 'chorodidaskalos' - who I consider as an early philosophical figuration of the modern director. I highlight speculative 'aporia' which in Rose indicates a path 'without a path' as the primary modality of thinking philosophically, already at work in tragedy, that renders the modernist director as a theatrical thinker. Chapter 3 puts forward the case of the director's mediating subjectivity by arguing for the Event of the director. I analyse Badiou's philosophy of the Event, making connections to speculative philosophy and illuminating the Evental dimension of this figure. Chapter 4 moves the examination to the Event of the director that I locate in Richard Wagner. My reading explores the philosophical dimension of Wagner as an artist and a thinker by which I rehabilitate his overtly negative image. I do this by reading Left Hegelianism, and anarchist philosophy more broadly, in Wagner's operatic works, writings, and political activism. Chapter 5 examines the 'speculative director' in the aesthetic project of Naturalism and Realism. The chapter includes a published section by which I explore the political mode of the director indirectly, by examining the articulatory discourse in Laclau and Mouffe's definition and the practice of affirmation. Chapter 6 looks at the avant-garde manifesto as a form of meta-language that seeks to actively re-shape theatre and the world as embodied, declaimed philosophy. The chapter repositions the avant-garde's aesthetic preoccupation with failure as a profoundly transformative project rather than as being incomplete. The included published article examines more closely the affinity between the Spartacus Manifesto by Rose Luxemburg (philosophy) and the more politicized forms of the Dada Berlin manifesto art (theatre). Chapter 7 is the concluding chapter by which I argue the case of the director finally having entered the theatre as a philosopher; that is, through Bertolt Brecht.

Excerpt: It was the sixties—albeit the 1660s—a time for tricksters, rakes, subversive women and sexual energy on the stage. It was a time of fun for those with the means to partake of it. The “good old days” are, of course, always better from a distance, but writers on through the twentieth century found the Restoration an apt setting for their fictions about prostitution, political intrigue, and tragic or comic historical events, especially for the cinema.

Over the last two centuries, the discovery and application of catalysts has had a substantial impact on how and what chemicals are produced.Given their broad significance, our group has focused on developing new catalyst systems that are recoverable and reusable, in an attempt to reduce concomitant costs. Our efforts have centered on constructing a recyclable chiral heterogeneous catalyst capable of effecting asymmetric hydrogenations of olefins with high stereoselectivity. A class of phosphinoimidazoline ligands, developed by researchers at Boehringer-Ingelheim, known as BIPI ligands, have proven efficacious in the asymmetric reduction of alkenes. However, these chiral ligands are homogeneous and coordinated to precious metals, rendering them irrecoverable and expensive. To address these issues, our group has derivatized the BIPI ligand-metal complex and immobilized it to the surface of graphene oxide as well as polystyrene. Their efficacy and recyclability toward the asymmetric hydrogenation of a functionalized olefin have been evaluated. Another facet of our work has included developing a cost effective synthetic process to artemisinin, the gold standard drug in the treatment of malaria.As a natural product, artemisinin’s worldwide supply remains highly unpredictable, contributing to great price volatility.Combining the benefits of catalysis and the advantages of continuous flow chemistry, our research has sought to develop an economical approach to convert a biosynthetic precursor, artemisinic acid, to artemisinin in three chemical transformations. High-throughput experimentation allowed us to screen a prodigious number of catalysts and identify those effective in the asymmetric hydrogenation artemisinic acid to dihydroartemisinic acid, the first step in the transformation. This screening directed us to an inexpensive, heterogeneous ruthenium catalyst. The second step of the process includes the photooxygenation of dihydroartemisinic acid, which involves photochemically generated singlet oxygen. We have evaluated a commercially available heterogeneous photocatalyst packed in a transparent bed, surrounded by light emitting diodes in the continuous photooxygenation of dihydroartemisinic acid to dihydroartemisinic acid hydroperoxide. The third and final step, an acid induced hock cleavage, initiates an intricate cascading reaction that installs an endoperoxide bridge to deliver artemisinin. Our process afforded a 57% yield from dihydroartemisinic acid to artemisinin.

La réalisation d'une mémoire quantique pour la lumière met en jeu les aspects les plus fondamentaux de l'interaction matière-rayonnement. Pour capturer l'information quantique portée par la lumière, le matériau doit être capable de se maintenir dans un état de superposition quantique. Le temps de stockage est limité par la durée de vie de cet état, caractérisée par le temps de cohérence. Les premières expériences ont été réalisées dans des vapeurs atomiques froides, bien connues. Plus récemment, les ions de terres rares en matrice cristalline (REIC) ont attiré l'attention par leurs long temps de cohérence, associés à de larges bandes passantes d'interaction. Pour exploiter ces bonnes propriétés, des protocoles spécifiques ont été proposés. Nous nous sommes tournés vers un dérivé prometteur de l'écho de photon, le Peigne Atomique de Fréquences (AFC, proposé en 2008), fondé sur la transmission du champ incident à travers un profil d'absorption spectralement périodique. Les premiers chapitres de ce manuscrit présentent ce protocole et les travaux effectués durant cette thèse pour en améliorer l'efficacité (i.e. la probabilité de capter et de restituer l'information incidente), en augmenter la bande passante et la capacité de multiplexage et en mesurer le bruit. Les chapitres suivants présentent un nouveau protocole, proposé dans notre groupe durant cette thèse, et baptisé ROSE (Revival Of Silenced Echo). Ce protocole, très proche de l'écho de photon, a été démontré et caractérisé expérimentalement. Il semble très prometteur en termes d'efficacité, de bande passante et de bruit.