Ein wichtiger Aspekt bei der Kultur von Pfirsichen (Prunus persica) ist die optimale, bedarfsgerechte N-Versorgung. Durch diese werden Höhe und Qualität der Erträge sowie die Gesundheit der Pflanzen beeinflusst, aber auch unerwünschte Effekte auf die Umwelt vermieden. Ziel der Arbeit waren daher Empfehlungen zur zukünftigen Handhabung der N-Versorgung an zwei Beispielstandorten und zur praktikabelsten Kulturweise. Es wurden Nmin-Bestimmungen, Inkubationsversuche und Thermogravimetrische Bodenanalysen durchgeführt, um die N-Nachlieferung aus der organischen Bodensubstanz an den Standorten zu beschreiben. Die Ergebnisse zeigen eine deutliche Überversorgung der Kultur im Hausgarten auf - die Pfirsiche auf der untersuchten Obstwiese sind hingegen optimal mit N versorgt. Empfohlen wird deshalb eine Reduzierung der organischen Düngung im Hausgarten, verbunden mit einem Verzicht auf frisches organisches Schnittmaterial als Dünger. Bei der Pfirsichkultur auf der Obstwiese ist die Einführung von Mulchmaßnahmen überlegenswert. Der Standort mit begrünter Bodenoberfläche ist gegenüber dem Hausgarten mit offener Bodenoberfläche vorzuziehen, da die N-Nachlieferung bei einer Begrünung einfacher handhabbar ist und weniger Risiken hinsichtlich einer N-Überversorgung vorhanden sind. / An important aspect in the cultivation of peaches (Prunus persica) is the optimal, demand-oriented N-supply. This influences the amount and quality of yields and the health of the plants, but also prevents undesirable effects on the environment. The aim of the work was therefore to make recommendations for future use of the N-supply at two sample locations and for the most practicable cultivation method. Nmin determinations, incubation experiments and thermogravimetric soil analyses were carried out to describe the N-supply from the organic soil substance at the sites. The results show a clear oversupply of the crop in the house garden - the peaches on the investigated fruit meadow, on the other hand, are optimally supplied with N. Therefore, it is recommended to reduce the amount of organic fertiliser in the garden, combined with the elimination of fresh organic cuttings as fertiliser. In peach cultivation on the fruit meadow, the introduction of mulching methods is worth considering. The location with a planted ground surface is preferable to the garden with an open ground surface, as the N-supply is easier to handle if greenery is present and there are fewer risks with regard to an N-oversupply.

This thesis parts from the premise that avant-garde art collectives produce discourses meant to articulate the opposition to the art/life divide as one that interrelates fields such as aesthetics, politics, philosophy, and even economics. By utilizing a comparative framework, it plays on the complementarity and differences between four 1960s groups that formed very specific organizations directed at challenging society, in one way or another related to the Situationist International: The Situationist Times (France), King Mob Echo (UK), Black Mask and its transformations (US), and S.NOB (Mexico). Through the medium of magazines, they intended to reach a mass audience that in the act of reading and looking at their images and texts would be prompted to discern organizations that undermined the world-system. Thus, the Situationist Times attempted to form a (people’s) movement that in an applied creativity that rejected the metanarrative of progress would be able to realize the malleability of history. King Mob followed a conspiratorial logic with the idea of a dis-organized mass suddenly acting in concert against states. Black Mask and its transformations played with the idea of a war for territory, the occupation of a ‘free zone’ by a community in the midst of a dominated world. Finally, S.NOB’s idiosyncratic anarchism came from an opposition to the totalizing discursive practices of the Mexican Revolution, giving primacy to fragmentation and an anti-organizational bent; while it had no direct relationship to any of the above groups, it shows how their techniques and theories develop out of an engagement with Surrealism and past avant-gardes. S.NOB provides not a counterpoint but a contextual revelation of the limits of these collectives, in the Bataillean sense that opens all of them up to a ‘contamination’ with historicity and thought that treats all of them as equal in scope and importance.

Des supramolécules basées sur la reconnaissance de viologènes par des curcubit[n]urils (CB[n]) ont été étudiées. Les systèmes développées incluent des [3]-, [4]- et [7]pseudorotaxanes, composés de multimères à base de viologène et de CB[7] ou CB[8]. L’étude physicochimique a montré que ces supramolécules sont interconverties électrochimiquement entre un état complexé, défini par les pseudorotaxanes, et un état dissocié comprenant chacun des partenaires. Le désassemblage résulte d’une pimérisation intra/intermoléculaire entre radicaux viologènes.L’étude physicochimique de complexes pentacoordinés basés sur la reconnaissance d’azo-aryl-imidazoles par une porphyrine à anse phénanthroline a été menée; l’objectif étant d’utiliser les propriétés d’isomérisation photoinduite trans-cis d’azo-chromophores pour dissocier ces complexes. Les complexes initiaux sont alors régénérés par relaxation thermique. La stabilité et les propriétés cinétiques des complexes pentacoordinés ont été évaluées. / Supramolecules based on the recognition of redox-active bipyridiniums by cucurbit[n]uril (CB[n]) have been studied. The investigated systems include a [3]-, a [4]- and a [7]pseudorotaxane, each of them composed of a multimeric viologen-based thread molecule and CB[7] or CB[8]. The physicochemical approach emphasized that these systems can be electrochemically switched between a complexed state, defined by the pseudorotaxanes, and an uncomplexed state comprising their components. The disassembly results from intra/intermolecular pimerization of the viologen radicals.A physicochemical approach of pentacoordinated complexes of a phen-strapped porphyrin with azo-arylimidazoles has been undertaken with the aim to use the photoinduced trans-cis isomerization properties of azo-chromophores to dissociate the complexes. Thermal equilibration reinstates the thermodynamically favoured complexes. The strength and the kinetic properties of these pentacoordinated species have been evaluated.

La citrulline est un acide aminé dont les propriétés anaboliques n’ont été mises en évidence que très récemment. Ces propriétés pourraient relever en particulier de son rôle de précurseur direct de l’arginine. L’arginine est un acide aminé central du métabolisme des mammifères, notamment comme précurseur de nombreuses molécules exerçant des fonctions physiologiques essentielles, en particulier les polyamines, que ce soit les polyamines « classiques » putrescine, spermidine et spermine, dérivés de décarboxylation de l’ornithine impliquées entre autres dans la prolifération cellulaire, ou l’agmatine, dérivé de la décarboxylation de l’arginine. Toutefois, les interactions métaboliques entre citrulline et polyamines restent encore peu connues. Le but de ce travail a été d’explorer le lien métabolique entre citrulline et polyamines, selon deux démarches distinctes.La première a été d’évaluer l’influence d’une complémentation prolongée (3 mois) en citrulline sur le métabolisme tissulaire des polyamines « classiques » chez le rat âgé. La citrulline n’affecte que de manière modérée le métabolisme des polyamines, principalement en corrigeant les altérations liées au vieillissement.La seconde, par analogie avec la putrescine et l’agmatine, a exploré l’implication du dérivé décarboxylé de la citrulline, la N-carbamoyl-putrescine (NCP) dans le métabolisme des mammifères après avoir mis au point une technique de dosage de celle-ci dans les milieux biologiques. Nous n’avons pas pu mettre en évidence la présence de NCP dans des tissus de rats ayant reçu de la citrulline par voie orale ou par voie parentérale suggèrant soit une absence de synthèse soit un métabolisme extrêmement rapide de la NCP. Par ailleurs, la NCP administrée par voie orale à des doses de 5 et 50 mg/kg/j ne semble pas induire de toxicité ni d’effets biologiques majeurs mais la démonstration de son absorption digestive reste à faire. Cependant, la NCP exerce quelques effets modérés sur le métabolisme des acides aminés et des polyamines, l’évaluation de doses plus élevées ou l’administration par voie parentérale permettrait de confirmer ces observations. / The anabolic properties of the amino acid citrulline have only been recently demonstrated. These properties may result at least in part from its role as an arginine precursor. Arginine plays a central role in mammalian amino acid metabolism, notably as the precusor of many molecules involved in essential physiological functions, such as polyamines either “classical” ones, namely putrescine, spermidine, and spermine, derived from ornithine decarboxylation and notably involved in cell proliferation, or more recently-discovered molecules such as agmatine, the decarboxylation derivative of arginine. Metabolic interactions between citrulline and polyamines are still mostly unknown.The aim of this work was to explore the metabolic link between citrulline and polyamines using two different strategies.First, the influence of a long term citrulline supplementation on tissue “classical” polyamine metabolism in aged rats has been evaluated. Polyamine metabolism is only moderately affected by citrulline supplementation, mostly correcting aging-related alterations.Second, by analogy with putrescine and agmatine, the involvement of the decarboxylated derivative of citrulline, N-carbamoyl putrescine (NCP), in mammalian metabolism was investigated after having developped an HPLC assay for the determination of NCP in biological media. We have not been able to demonstrate the presence of NCP in tissues of rats having received citrulline orally or parenterally suggesting either a lack of synthesis or an extremely rapid metabolism of NCP. In addition, oral administration of NCP 5 or 50 mg/kg/d did not appear to induce toxicity or major biological effects but the demonstration of its gastrointestinal absorption remains to be done. However, NCP has some moderate effects on amino acid and polyamine metabolism. The evaluation of higher doses of NCP or of its parenteral administration is required to confirm these observations.

Die doel van hierdie verhandeling is om 'n algoritme vir kleinstekwadrate-benaderings te vind en om met behulp van die algoritme 'n rekenaarprogram te ontwikkel vir die minimering van die kleinstekwadrate- benadering en die passings van krommes deur gegewe eksperimentele data. Eerstens word die norm en die pseudo-inverse van matrikse sowel as Householder-transformasies bespreek, aangesien ons daarvan gebruik maak in die oplossing van ons probleem. In die lineere kleinstekwadrate-probleem word die koeffisiente matriks A ontbind in 'n produk van 'n ortogonale en 'n bo-driehoeksmatriks. Hierdie produk word dan gebruik om die pseudo-inverse van A te verkry. Die algoritme wat ontwikkel is vir die nie-lineere kleinstekwadrate- probleem is gebaseer op die Gauss-Newton-Marquardt-metode, waar met elke stap 'n lineere kleinstekwadrate-probleem opgelos word. Resultate wat met behulp van die algoritme verkry is, word ook vergelyk met die resultate van ander algoritmes. / Dissertation (MSc)--University of Pretoria, 1977. / gm2014 / Mathematics and Applied Mathematics / Unrestricted

The purpose of this study was to determine whether the methylation of nicotinamide to N-methylnicotinamide could discriminate between differences in methionine nutritional status, and by implication methylation capacity, in healthy humans. As part of this thesis, a highly selective high performance liquid chromatography (HPLC) method for the determination of N-methylnicotinamide (NMN) in urine and plasma was developed and validated. Quantification was by fluorescence detection of the 1,6-naphthyridine derivatives, formed after incubation of NMN with acetophenone in alkaline conditions. Seven volunteers participated in a trial to evaluate the ability of a nicotinamide load test to discriminate between changes in the methylation status of the individual. The methylation status was measured as the time dependent changes in plasma NMN concentrations after a nicotinamide load. A basal nicotinamide load test was performed on each individual. The methylation status was then changed, by means of a methionine load, and the nicotinamide load test was repeated during the enhanced methylation state. The dynamic changes in N-methylnicotinamide levels indicated that the methionine load changed neither the plasma NMN concentrations, nor the rates of NMN formation. The conclusion of this study was that nicotinamide loading could not be used as a dynamic function test to assess biological methylation in healthy humans. / Dissertation (MSc (Chemical Pathology))--University of Pretoria, 2006. / Chemical Pathology / unrestricted

This portfolio and commentary documents an approach to audiovisual composition that utilises sound and photographic images in an effort to create immersive, affective art which I call audio-photographic art. When presented in an immersive context, I contend that the temporal dissonance between still image and sound opens up a space between the materials. I draw upon Gernot Böhme's writings on the aesthetic of 'atmosphere', as well as the the theoretical writings of Roland Barthes, Paul Ricoeur and Eleni Ikoniadou among others to illustrate how this experience is constituted. This space between is an affective conceptual space in which the participant enters into a relationship with the materials of the piece, transcending their usual perception of time as they are immersed in the internal times of the artwork, their own memories and atmosphere. Through the use of maximal aesthetics and atmosphere as compositional tool, these themes are explored and developed throughout the creative portfolio. In the written submission I study the practical and theoretical concerns of the space between from three perspectives: 'The Temporal Space', 'The Memorial Space' and 'The Atmospheric Space'.

Photocatalysis is a growing area of study for a clean and renewable energy source, particularly for the purification of water and air. Researchers have studied the combination of various semiconductors to create photocatalysts with improved activities, but little has been reported in selecting semiconductors based on their extrinsic type – namely n-type or p-type. In this study, a BiOBr (p-type)-Bi2WO6 (n-type) heterojunction semiconductor was synthesized by the facile hydrothermal method. The new materials were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and diffuse-reflection spectroscopy (DRS). Degradation of Rhodamine B was employed to measure the photocatalytic activity of the as-prepared photocatalysts. On the basis of these techniques, the influence of the synthesis conditions (namely, hydrothermal reaction time and temperature) and the degradation conditions (namely, initial concentration, pH of the initial dye water and amount of catalysts dosage) have been explored and discussed. Furthermore, effect of concentrations of the dopants (the atomic ratio of BiOBr and Bi2WO6 were 1:4， 1:1， 4:1) was examined by measuring the degradation rate of Rhodamine B. Finally, the mechanism of the degradation process and the enhancement effect of heterojunction were also interpreted by analyzing the quenching effect of the scavengers and the band structure. Conclusively, this study shed light on the benefits of using heterojunction photocatalysts, and also on the importance of considering the semiconductor type when forming composite photocatalysts.

Nikolai Alekseevich Zabolotskii (1903-1958) published his first collection of poems, Stolbtsy, in Leningrad in 1929. This volume of twenty-two poems offers highly evocative and metaphorical descriptions of urban life in Leningrad during the New Economic Policy (NEP) of 1922-1928. Even during this relatively liberal period the collection, which comprises a cycle of inter-related poems, created a sensation and was severely criticized for its satirical view of life and pessimistic tone. The composition of Stolbtsy was heavily influenced by Zabolotskii's membership in the short-lived avant-garde group known as OBERIU, an acronym for "Ob"edinenie real'nogo iskusstva" ("The Association of Real Art"). Zabolotskii helped write the group's manifesto, and it is the literary aesthetic set forth in this document that forms the basis of the critical criteria used to analyze ten poems from Stolbtsy. The primary objective of OBERIU was its striving towards an art that exhibited predmetnost' ("concreteness"). This was an attempt to clear away the conventional contextual associations of words and objects, and to reveal their absolute, fundamental meanings. Predmetnost' was used to emphasize the objective nature of art and its distance from abstraction. This meant the dissolution or segmentation of a depicted object, and the reliance on collisions between verbal units and objects to produce new semantic effects. Zabolotskii called this the "collision of verbal meanings" (stolknovenie slovesnykh smyslov). The ten poems selected for analysis are: "Krasnaia Bavariia," "Belaia noch'," "Ofort," "Leto," "Novyi byt," "Dvizhenie," "Ivanovy," "Pekarnia," "Obvodnyi kanal," and "Narodnyi Dom." These poems illustrate Zabolotskii's reaction to the social effects of NEP on the urban environment of Leningrad and on its citizens. The literary tenets of the OBERIU, especially the concept of predmetnost' ("concreteness"), form a basis from which it is possible to appreciate the structural and aesthetic originality of Zabolotskii's perception of this environment. The poems are examined from their thematic stand-point and from their structural composition in order to understand their meaning and to reveal the ways in which various devices function within a single poem and in relationship to others in the cycle. In these poems Zabolotskii loads his images with multiple associations so that they become distorted. Frequently these images are only visual and function exclusively at this level, rendering experiences more concrete; others have a metaphorical function that clearly represents a vision which has a philosophical level of understanding. Zabolotskii's grotesque perspective in Stolbtsy reflects the sense of alienation that he encountered in NEP-time Leningrad. Zabolotskii considered the excesses of NEP as a betrayal of the ideals of the Revolution; what he did to combat the alienation it engendered was to chronicle the effects of NEP in highly satirical terms and, in the process, to reject its false pretences. This combination forces the reader to attend closely to the themes of the poems and challenges him to re-think his usual definition of reality. Although these poems are not considered OBERIU poems, the literary tenets of the OBERIU Declaration offer the best possible clue to a comprehensive understanding of both the structural composition and thematic make-up of Zabolotskii's highly original volume of poetry. / Arts, Faculty of / Central Eastern Northern European Studies, Department of / Graduate

Le point de départ de cette recherche est le constat des difficultés persistantes rencontrées par les francophones de niveau intermédiaire à avancé lors de la production de textes en anglais, dans des contextes personnels ou professionnels. Les premiers outils utilisés pour remédier à ces erreurs, les correcteurs grammaticaux automatiques, ne prennent pas en compte de nombreuses erreurs produites par les francophones utilisant l'anglais, notamment car ces correcteurs sont rarement adaptés à un public ayant l'anglais comme L2. Nous proposons d'identifier précisément les difficultés rencontrées par ce public cible à partir du relevé des erreurs dans un corpus adapté, et d'élaborer une modélisation linguistique des erreurs et des corrections à apporter. Cette modélisation est fondée sur une analyse linguistique approfondie des phénomènes concernés, à partir d'indications grammaticales, d'études de corpus, et de l'analyse des segments erronés. La validité de l'utilisation de méthodes linguistiques est établie par l'implémentation informatique des règles de détection et de correction, suivie de l'évaluation des résultats de l'application de ces règles sur des corpus d'anglais L1 et L2. / The starting point of this research is the observation that French speakers writing in English in personal or professional contexts still encounter grammatical difficulties, even at intermediate to advanced levels. The first tools they can reach for to correct those errors, automatic grammar checkers, do not offer corrections for a large number of the errors produced by French-speaking users of English, especially because those tools are rarely designed for L2 users. We propose to identify the difficulties encountered by these speakers through the detection of errors in a representative corpus, and to create a linguistic model of errors and corrections. The model is the result of the thorough linguistic analysis of the phenomena at stake, based on grammatical information available in reference grammars, corpus studies, and the analysis of erroneous segments. The validity of the use of linguistic methods is established through the implementation of detection and correction rules in a functional platform, followed by the evaluation of the results of the application of those rules on L1 and L2 English corpora.