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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

The influence of viticultural treatments on the accumulation of flavonoid compounds in grapes and their contribution to wine quality.

Cordon, Nicole January 2008 (has links)
The grape flavonoids include anthocyanins, tannins and flavonols, all of which contribute to grape and wine quality by influencing the colour and mouthfeel of red wine. These compounds are synthesized in different parts of the berry and during different stages of berry development. In addition, environmental and viticultural factors such as light exposure can also alter the flavonoid composition of grapes. An understanding of how synthesis of these compounds is coordinated, their relationship to wine quality and the influence of bunch light exposure on the flavonoid composition of grapes, could be used to improve fruit quality by enhanced viticultural management. The first part of this study sought to investigate the relationship between the different products of the flavonoid biosynthetic pathway (anthocyanins, flavonols and tannins), from two climatic regions (warm and cool) and determine their role in grape and wine quality. In collaboration with a major winery, whole Shiraz grapes were sampled at the weighbridge from a range of different vineyards from two climatic regions; warm (Riverland) and cool (McLaren Vale) in 2003 and 2004. A total of 80 grape samples were collected in each season and processed (i.e. 100 berries, separated into skin, seeds and juice, weighed and frozen). Anthocyanins and flavonols were measured, in triplicate, in skins by HPLC. Tannins were determined in the skins and seeds by two methods; phloroglucinol hydrolysis (HPLC) and protein precipitation (UV-VIS spectrophotometer). A comprehensive comparison of the two methods is discussed. In both years, the grapes from warm and cool climates formed two distinct data sets based on flavonoid composition. There was a correlation between anthocyanins and flavonols for both the warm and cool climate samples in both years, however those from the warm region had lower anthocyanin for a given level of flavonol. As expected, the level of tannin in the seeds was greater than in skin for all samples. In both years, there was a weak correlation between anthocyanin levels in the skin and skin tannins, but no relationship with seed tannins. These results suggest there is some co-ordination in the synthesis of anthocyanins, flavonols and skin tannins. Also, the two regions clearly separated based on yield and despite the weak correlations in both regions, the levels of total anthocyanins were inversely related to yield. In addition, there was no relationship with any of the flavonoids and grape quality, indicating the need for improvement in streaming fruit for quality using these flavonoid compounds. The second part of the study was to investigate the effect of bunch light exposure on flavonol synthesis and accumulation in Shiraz and Chardonnay grapes during development. Light-excluding boxes were applied to bunches at budburst. Boxes were removed at four sampling times; flowering, pre-veraison, veraison and harvest. At each sampling time, berry skins were sampled when the boxes were removed and then every second day (light induced), along with exposed controls for one week. Flavonol accumulation and flavonol synthase (VvFLS1) gene expression was determined by HPLC and Real Time-PCR (RT-PCR) respectively. As expected, for all four sampling times, flavonol accumulation and VvFLS1 expression in the boxed fruit was significantly less than bunches exposed to light. On removal of boxes at flowering, pre-veraison and veraison, flavonols accumulated to levels similar to that of the exposed control fruit over a period of 4-6 days. There was a significant increase in VvFLS1 expression 2 days after exposure to light in parallel with the accumulation of flavonols. At harvest, in Chardonnay, VvFLS1 expression peaked by day 4, while in Shiraz VvFLS1 expression increased linearly and was highest at day 6. In contrast to the results for the earlier sampling times, the total amount of flavonols accumulated at harvest was less than 50% of exposed controls in Chardonnay and Shiraz grapes. These results show that flavonols are able to be induced by bunch light exposure at different times during berry development, including times when flavonols are not normally being synthesised. This suggests bunch light exposure can override the developmental control of flavonol accumulation. To further investigate the light induced expression of VvFLS1 in grapevines the molecular mechanism of transcriptional control was explored. Using genomic walking PCR techniques, two Shiraz VvFLS1 promoter sequences were cloned and their sequences were analysed. These promoter sequences were ~800bp in length and were 99% identical. A putative MYB responsive element (MRE) and several light responsive elements (LRE) were identified in the promoter region of these genes. To functionally test the VvFLS1 promoter(s), a transient assay was developed in Chardonnay suspension cells. Cells were bombarded with constructs containing potential transcription factors and the VvFLS1 promoter(s), fused to a luciferase reporter vector. After 48hrs incubation in the dark, cells were harvested and luciferase activity measured as an indicator of VvFLS1 promoter activity. Of the different transcription factors tested with the VvFLS1 promoter(s) the highest luciferase activity was observed using AtMYB12 (a flavonol-specific regulator of AtFLS1 in Arabidopsis (Mehrtens et al. 2005). While this result shows activation of the VvFLS1 promoters by AtMYB12 and the development of a transient reporter assay for testing the VvFLS1 promoter(s) a grapevine transcription factor specific for VvFLS1 was sought. Two techniques were employed to identify potential transcription factor regulators of the VvFLS1 promoter(s). The first involved BLAST sequence search analysis in a grapevine expression (EST) database with AtMYB12 and the second involved using DNA microarray technology to identify candidate transcription factors that were up-regulated in light exposed Chardonnay cell suspension cultures. Thirteen potential transcription factors were identified and after correlative RT-PCR analysis (with VvFLS1 expression patterns) two candidates were selected for further isolation and characterisation. These results have made significant progress in unravelling the molecular mechanisms of regulation of the flavonol biosynthetic, however additional experiments are required to unravel the transcriptional control of flavonol biosynthesis. This investigation contributes to our knowledge of flavonoid synthesis in grapes; how it is coordinated, the relationship with wine quality, and the influence of light particularly on synthesis of flavonols. It also explores the molecular mechanisms of VvFLS1 control, through isolation of the VvFLS1 promoter and identification of potential transcription factors, which may regulate it. An understanding of the synthesis of flavonoids and how they may be coordinated, particularly in response to light, could be used to improve fruit quality by enhanced viticultural management. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1326767 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2008
62

Géométrie et adiabaticité des systèmes photodynamiques quantiques

Viennot, David 22 November 2005 (has links) (PDF)
Les simulations des systèmes atomiques ou moléculaires en interaction avec un champ électromagnétique se heurtent à un problème majeur. Pour décrire le système photodynamique, il est nécessaire d'utiliser une très grande base, ce qui est coûteux en temps de calculs et en mémoire. Pour résoudre ce problème, nous sommes amenés à chercher des modélisations ne faisant intervenir que des sous-espaces vectoriels de faible dimension, appelés espaces actifs. Comme la dépendance temporelle d'un système photodynamique se fait à travers des paramètres à évolution lente, c'est une théorie adiabatique qui définit cet espace. L'application d'un théorème adiabatique nous apprend que le système ne peut pas sortir d'un sous-espace spectral associé à des valeurs propres isolées. La fonction d'onde est alors décrite par un relèvement horizontal qui prend place dans le fibré principal de la phase de Berry. Celle-ci ne commutant en général pas avec la phase dynamique, nous proposons une description fondée sur un fibré composite, modélisant simultanément phases géométrique et dynamique. Nous proposons une méthode de simulation de la photodynamique associée à la description géométrique et nous utilisons la notion de monopôles magnétiques virtuels pour obtenir des outils d'analyse de la dynamique. Nous étudions ensuite la théorie des opérateurs d'onde temporels, théorie fournissant une méthode d'Hamiltonien effectif. Pour coupler cette théorie avec le modèle adiabatique, nous étudions la compatibilité des deux méthodes en démontrant un théorème adiabatique pour les opérateurs d'onde. Nous nous sommes intéressés à des systèmes dynamiques simples, atomes à 2 ou 3 niveaux et molécule H2+.
63

Paléogéographie d'un territoire : la cité des Bituriges Cubi

Maussion, Anne 06 February 2003 (has links) (PDF)
À l'intérieur du territoire des Bituriges Cubi (Indre, Cher et ouest de l'Allier), les informations archéologiques concernant l'occupation rurale ont fait l'objet d'une série d'analyses, spatiales et quantitatives. À l'aide d'un système d'information géographique (SIG), elles ont été largement corrélées entre elles ainsi qu'avec les informations environnementales. Ainsi, le rôle déterminant de différents facteurs (réseau hydrographique, exposition des versants, etc.) dans l'implantation rurale gallo-romaine a nettement été mis en évidence. Ce sont les sols qui paraissent avoir le plus influencé la répartition des habitats ruraux gallo-romains. L'environnement des exploitations agricoles antiques regroupe généralement des types de sols variés et complémentaires. Les sols argileux lourds, aux potentiels agricoles variables, ainsi que les sols alluviaux et colluviaux y sont particulièrement bien représentés. En revanche, les terres hydromorphes ont été significativement rejetées.
64

Faith and Field: Christianity, the Environment, and Five Contemporary American Poets

Hoover, Heather M 01 May 2010 (has links)
Many poets write about the earth or even about God using the language of nature. And many poets and contemporary authors concern themselves with the state of the environment. However, the poetry of Wendell Berry, James Still, Li-Young Lee, Mary Oliver, and Charles Wright seems to engage different kinds of questions about how humans creatively respond to the earth. Collectively, their responses seem influenced by their connections with Christianity rather than any specific ecological agenda. In all of their poetry lies a sensibility about how humans should interact with the earth. All five of the poets seem to acknowledge humanity’s place on the earth as important without elevating humanity as the most important organism on the earth. Their work presupposes the existence of God or creator and because of this, engages the questions of being human in light of that Creator rather than as creators of their own environment or as the architecture of imagination. Their work offers an important insight into how we might live in harmony with all environments—agricultural, rural, wild or urban. Their work also suggests a connection between the Christian concept of worship, and a way of living that takes responsibility for human actions within creation. Their poetry recognizes the earth’s value as well as God’s presence and results in praise of both the beauty of creation and Creator.
65

L'affaire Louvel, ou l'introuvable complot événement, enquête judiciaire et expression politique dans la France de la Restauration /

Malandain, Gilles Boutry, Philippe January 2007 (has links)
Thèse de doctorat : Histoire contemporaine : Paris 12 : 2005. / Version électronique uniquement consultable au sein de l'Université Paris 12 (Intranet). Titre provenant de l'écran-titre. Bibliogr. p. 513-534.
66

Semiclassical study of spin magnetic moment and spin orbit interaction

Chuu, Chih-Piao 16 March 2015 (has links)
This dissertation describes the theoretic studies of magnetic moment and spinorbit interaction in vacuum (Dirac wavepacket) and solid state systems, such as semiconductors. The semiclassical approach developed here provides a simple and intuitive picture for the origin of spin and spin-orbit coupling. In the Dirac model, the spin magnetic moment is originated from the self-rotating Dirac wavepacket with a correct g-value. The spin-orbit interaction is related to Berry connection (gauge potential) and the model is generalized to solid state systems. The Rashba effect caused by the spin-orbit coupling in a crystal with asymmetric potential in heterostructure quantum well is calculated by semiclassical spindependent scattering. The exact treatment of interface phase accumulation provides a justification of spin-dependent boundary condition at interface derived in previous treatment using Löwdin decomposition. Other spin-orbit coupling related phenomena in solid state system are also discussed in this thesis. / text
67

NITROGEN CYCLING, OPTIMIZATION OF PLANT NUTRITION AND REMOTE SENSING OF LEAF NUTRIENTS IN WILD BLUEBERRIES (VACCINIUM ANGUSTIFOLIUM AIT.)

Maqbool, Rizwan 10 December 2013 (has links)
This thesis consists of three sections that provide detailed knowledge of nutrient estimation and management in wild blueberry production. The first section investigated the main and interactive effects of long term fertilizer (NPK) enrichments on soil mineral nitrogen, organic nitrogen and carbon, microbial biomass nitrogen and carbon, net mineralization and net nitrification in wild blueberry soils. The second section studied the optimization of wild blueberry growth, development, foliar nutrients and harvestable yields by using response surface methodology. The third section examined nutrient estimation technologies using field spectroscopy. The remote sensing data was analysed with a combination partial least squares regression and variable selection algorithms (Chemometric analysis). The results indicated elevated nitrification activity under nitrogen enrichments, mainly performed by heterotrophs, report unusually high levels of dissolved organic carbon (> 150 C ha-1), a fungal dominated soil system and high concentration of soluble organic nitrogen in the crop year of production. Nitrification and high dissolved organic carbon levels were observed in connection with possible nitrogen saturation and potential environmental hazards. The results imply a need for nitrification inhibition measures. Results from field studies examining the main and interactive effects of soil applied N, P and K suggested that applications of nitrogen (35 kg ha-1), phosphorus (40 kg ha-1) and potassium (30 kg ha-1) were required to optimize growth, development and harvestable yields of wild blueberry. Under these fertilizer rates, the corresponding predicted harvestable yield was 4,126 kg ha-1 that is as much as 13% higher than would be produced by commonly used fertilizer rate in the industry. This study presented new leaf nutrient ranges for sprout and crop years for wild blueberry fields in Atlantic Canada. Hyperspectral remote sensing technologies were used for estimating macro and micro nutrients. This study provides critical information on wavelengths important for nutrient estimation in reflectance spectra (400-2500 nm). The results and inferences from this thesis may be employed to improve crop production, increase economic returns and health of soil and sustainability of wild blueberry production in Nova Scotia. / This study was undertaken to examine the response of the wild blueberry plant to soil applied fertilizers and encompasses soil nitrogen and carbon pools, plant growth and development, leaf nutrient concentrations and harvestable yields. In addition, given the vast area in which wild blueberry fields are located, the study also examined the feasibility of assessing plant nutrient status through the use of remote sensing hyperspectral technologies. Our results emphasize the importance of monitoring for soil nitrogen and carbon pools in the context of accelerated nitrogen cycling, nitrogen saturation, the fine-tuning of current leaf nutrient ranges in Atlantic Canada in connection to fertilizer rates, the possibility of estimating leaf nutrient contents by remote sensing technologies all with the aim of optimizing wild blueberry yields. In terms of statistical techniques, this thesis used response surface methodologies with a central composite design as a means of discovering, the main and interactive effects of soil applied fertilizers to determine the most appropriate soil nitrogen levels and leaf nutrient ranges that correlate to the highest harvestable yields. The remote sensing data used to estimate leaf nutrients concentrations, various models that combined chemometrics and response surface methodologies for determining model efficiencies with aim of getting informative wavelengths in wild blueberry fields.
68

Establishing Organic Blackcurrants in Atlantic Canada

Hobson, David W. 12 April 2012 (has links)
A study on Prince Edward Island was initiated to assess the impact of organic fertility amendment rate and timing treatments and deflowering on the growth, yield, and berry size and soluble solids, and plant and soil available nutrients of blackcurrants (Ribes nigrum L cv. Titania.). Plants at the site with lower leaf P and K showed lower growth and yield (492-2540 kg ha-1) than the other site (3935-5016 kg ha-1No significant differences were found in final size or 2011 yield at the site with larger bushes, while at the other site the medium spring fertility treatment gave the greatest growth and yield, followed by the high spring fertility treatment. Deflowering increased yield but not growth at the site with recommended ranges of leaf P and K; at the site with P and K deficiencies, growth increased in 2010 and 2011. There was no interaction between deflowering and amendment timing.
69

Aspects topologiques des dérivés du graphène

De gail, Raphaël 20 March 2014 (has links) (PDF)
Ces dernières années, la physique de la matière condensée a connu une profonde révolution de concepts par la découverte de nombreuses phases de la matière qui ne sont pas classifiables à la Landau, c'est à dire par leur groupe de symétrie. Si les premiers travaux remontent à ceux des effets Hall quantiques (entier et fractionnaire), ce n'est que récemment, avec l'avènement du graphène et des isolants topologiques que les physiciens ont réalisé que ces phases de la matière ne nécessitent, dans l'absolu, ni champ magnétique, ni basse température, par opposition aux effets Hall quantiques précédemment cités. Ces nouveaux états de la matière sont caractérisés non pas par la géométrie du problème mais plutôt par la topologie. Ici donc, la forme précise du spectre électronique n'est pas importante, seules certaines caractéristiques, comme la présence ou l'absence d'un gap, le sont. De manière similaire à la classification de Landau des groupes de symétries, il est possible de classifier ces nouveaux systèmes par l'intermédiaire de groupes topologiques. La branche mathématique invoquée est celle de la topologie algébrique. A travers les invariants qu'elle génère, il est possible de classer les états topologiquement non-triviaux. De plus, les transitions entre des états à topologies distinctes sont aussi accessibles par cette théorie. Les travaux réalisés dans le cadre de cette thèse s'intéressent aux effets topologiques dans la structure de bandes de matériaux bi-dimensionnels. Après une présentation du formalisme mathématique général, un premier chapitre s'intéressera à la topologie locale, c'est à dire pour une portion restreinte de la première zone de Brillouin, des points de croisements de bandes, dits points de Dirac. Un effort sera porté vers la classification de ces systèmes et des transitions associées. Le chapitre suivant mettra en lumière un moyen efficace de mesurer les effets de la topologie des électrons en deux dimensions. Il s'agit de l'étude des niveaux de Landau qui résultent de l'application d'un champ magnétique 5transverse au plan des électrons. Les points de Dirac se transmutent alors en niveaux à énergie nulle topologiquement stables, c'est à dire peu ou pas influencés par les diverses perturbations. L'étude des différents modèles justifiera la discrimination entre la physique à champ magnétique faible et celle à champ magnétique fort, faible ou fort étant très dépendant du système étudié. Enfin, dans un dernier chapitre plus prospectif on s'intéressera à la topologie globale, c'est à dire pour l'ensemble de la première zone de Brillouin. Ce type d'étude est surtout caractérisé par l'existence d'états de bords robustes. On en fera l'expérience d'une double manière. D'abord par l'étude un modèle à un électron, puis par celle d'un système en forte interaction de N électrons. A travers les différents exemples étudiés, on s'attachera à démontrer la puissance de l'outil topologique pour les problèmes de la matière condensée, phénomène qui devrait s'accentuer les prochaines années.
70

White without soap: philanthropy, caste and exclusion in colonial Victoria, 1835-1888: a political economy of race

Stephens, Marguerita Unknown Date (has links) (PDF)
The thesis explores the connections between nineteenth century imperial anthropology, racial ‘science’, and the imposition of colonising governance on the Aborigines of Port Phillip/Victoria between 1835 and 1888. It explores the way that particular, albeit contested, images of Aborigines ‘became legislative’. It surveys the declining influence of liberal and Evangelical ‘philanthropy’ at the end of the 1830s, the pragmatic moral slippages that transformed humanitarian gestures into colonial terror, and the part played by the Australians in the emergence of the concept of race as the chief vector of colonial power. (For complete abstract open document)

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