Thesis (M.Sc(Agric.))(Agronomy)--University of Pretoria, 2006. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

Thesis (D.Phil.(Horticultural Science)--University of Pretoria, 2009. / Includes summary. Includes bibliographical references.

No abstract available / Dissertation (MSc(Agric) (Agronomy))--University of Pretoria, 2007. / Plant Production and Soil Science / MSc(Agric) / unrestricted

In this dissertation, I investigate interactive visual history for collaborative exploratory data analysis (EDA). In particular, I examine use of analysis history for improving the awareness of the dimension space coverage 1 2 3 to better support data exploration. Commonly, interactive history tools facilitate data analysis by capturing and representing information about the analysis process. These tools can support a wide range of use-cases from simple undo and redo to complete reconstructions of the visualization pipeline. In the con- text of exploratory collaborative Visual Analytics (VA), history tools are commonly used for reviewing and reusing past states/actions and do not efficiently support other use-cases such as understanding the past analysis from the angle of dimension space coverage. How- ever, such knowledge is essential for exploratory analysis which requires constant formulation of new questions about data. To carry out exploration, an analyst needs to understand “what has been done” versus “what is remaining” to explore. Lack of such insight can result in premature fixation on certain questions, compromising the coverage of the data set and breadth of exploration [80]. In addition, exploration of large data sets sometimes requires collaboration between a group of analysts who might be in different time/location settings. In this case, in addition to personal analysis history, each team member needs to understand what aspects of the problem his or her collaborators have explored. Such scenarios are common in domains such as science and business [34] where analysts explore large multi-dimensional data sets in search of relationships, patterns and trends. Currently, analysts typically rely on memory and/or externalization to keep track of investigated versus uninvestigated aspects of the problem. Although analysis history 4 mechanisms have the potential to assist analyst(s) with this problem, most common visual representations of history are geared towards reviewing & reusing the visualization pipeline or visualization states. I started this research with an observational user study to gain a better understanding of analysts’ history needs in the context of collaborative exploratory VA. This study showed that understanding the coverage of dimension space by using linear history 5 was cumbersome and inefficient. To address this problem, I investigated how alternate visual representations of analysis history could support this use-case. First, I designed and evaluated Footprint-I, a visual history tool that represented analysis from the angle of dimension space coverage (i.e. history of investigation of data dimensions; specifically, this approach revealed which dimensions had been previously investigated and in which combinations). I performed a user study that evaluated participants’ ability to recall the scope of past analysis using my proposed design versus a linear representation of analysis history. I measured participants’ task duration and accuracy in answering questions about a past exploratory VA session. Findings of this study showed that participants with access to dimension space coverage information were both faster and more accurate in understanding dimension space coverage information. Next, I studied the effects of providing coverage information on collaboration. To investigate this question, I designed and implemented Footprint-II, the next version of Footprint-I. In this version, I redesigned the representation of dimension space coverage to be more usable and scalable. I conducted a user study that measured the effects of presenting history from the angle of dimension space coverage on task coordination (tacit breakdown of a common task between collaborators). I asked each participant to assume the role of a business data analyst and continue a exploratory analysis work which was started by a collaborator. The results of this study showed that providing dimension space coverage information helped participants to focus on dimensions that were not investigated in the initial analysis, hence improving tacit task coordination. Finally, I investigated the effects of providing live dimension space coverage information on VA outcomes. To this end, I designed and implemented a standalone prototype VA tool with a visual history module. I used scented widgets [76] to incorporate real-time dimension space coverage information into the GUI widgets. Results of a user study showed that providing live dimension space coverage information increased the number of top-level findings. Moreover, it expanded the breadth of exploration (without compromising the depth) and helped analysts to formulate and ask more questions about their data. / Graduate / 0984 / ali.sarvghad@gmail.com

L'utilisation des plantes pour décontaminer les sols pollués par les métaux est une solution respectueuse de l'environnement. Mais le développement de cette technique à grande échelle est encore limité en raison de l'indisponibilité de plantes avec les caractéristiques souhaitées (hyperaccumulation, biomasse élevée et croissance rapide). Les objectifs de ce travail étaient d'évaluer le potentiel de plusieurs cultivars de Pélargonium odorants pour l'extraction du Pb au champ, étudier la disponibilité du plomb en relation avec l'activité rhizosphérique et développer un protocole de transformation génétique. Parmi les six cultivars de Pélargonium odorants testés au champ, trois : Attar of Roses, Clorinda et Atomic Snowflake ont accumulé plus de 1000 mg kg-1 Pb, avec une forte biomasse. Pendant les expérimentations en conditions contrôlées, Attar of roses (le cultivar hyperaccumulateur) acidifie sa rhizosphère et augmente la concentration en COD significativement plus par rapport Concolor Lace (le cultivar non hyperaccumulateur), sans doute en réponse à la pollution métallique. Les concentrations en plomb dans les deux cultivars sont corrélées avec l'extraction au CaCl2. Les analyses par EXAFS et ESEM-EDS ont montré que le plomb présent dans les racines était principalement sous forme de complexes organiques alors que les sulfates de plomb prédominent dans le sol. Parallèlement à ces essais, un protocole de transformation génétique a été mis au point en vue de mieux comprendre les processus biochimiques impliqués dans l'hyperaccumulation et la fonction des gènes, Le système de régénération optimisé se base sur la pré-culture d'explants sur un milieu contenant 10 μM TDZ + 1 mg L-1 de chacun de BAP et NAA suivie par l'enlèvement de TDZ du milieu de culture. La kanamycine et l'hygromycine se sont avérés être de bons marqueurs sélectifs pour le Pélargonium. Deux souches d'Agrobacterium, C58 et EHA105 contenant des vecteurs binaires avec des gènes marqueurs hpt et nptII ont été choisis pour des expériences de transformation. Ils ont également le gène codant uidA séquence du gène rapporteur. Après l'infection avec C58, 4 et 107 plantes enracinées sur hygromycine ont été obtenues pour Attar of Roses et Atomic Snowflake, respectivement. Parmi ces plantes enracinées, les quatre plantes d'Attar et 82 d'Atomic Snowflake ont exprimé le Gus dans les feuilles, pétioles, les tiges et les racines comme prévu avec une séquence sous contrôle du promoteur constitutif CaMV 35S. De 20 plantes qui expriment le Gus, 7 plantes se sont avérées être positives après criblage par PCR. Après infection par EHA105, 23 et 133 plantes enracinées ont été obtenues après sélection sur kanamycine, mais aucune n'a démontré d'activité GUS. Seule des expériences d'empreintes par Southern blotting permettront de corréler le nombre d'insertions et niveau de l'expression dans ces différents événements de transformation. / Metal removal from contaminated soils using plants can provide an environment friendly solution. However, its successful application on a large scale is still limited due to unavailability of plants with desired set of characteristics i.e. hyperaccumulation, high biomass and rapid growth. The objective of this work was to assess the potential of scented Pelargonium cultivars for lead (Pb) extraction under field conditions, plant induced rhizosphere changes, soil factors influencing availability of Pb and to develop an efficient genetic transformation protocol for the selected cultivars. Of the six scented Pelargonium cultivars field-tested, three cultivars (Attar of Roses, Clorinda and Atomic Snowflake) accumulated more than 1000 mg Pb kg-1 DW, with high biomass reaching up to 45 tons ha-1 y-1 dry matter. During assays in controlled conditions, Attar of roses (Pb hyperaccumulator) significantly acidified its rhizosphere and increased Dissolved Organic Carbon (DOC) concentration as compared to Concolor Lace (non-accumulator), probably due to enhanced exudation in response to the metal stress. Lead concentrations in both cultivars were best correlated with CaCl2 extracted Pb. Extended X-ray Absorption Fine Structure (EXAFS) and Environmental Scanning Electron Microscopy-Energy Dispersive x-ray Spectroscopy (ESEM-EDS) demonstrated that Pb was mainly complexed to organic acids within plant tissues whereas the dominant form in soil was PbSO4. Parallel to the soil-plant Pb transfer assays, a genetic transformation protocol was optimized in view of better understanding biochemical processes involved in lead hyperaccumulation and gene function, in the future. The best regeneration scheme was based on the pre-culture of explants on 10 μM TDZ (Thidiazuron) in addition to 1 mg L-1 each of N6-benzylaminopurine (BAP) and α- naphthaleneacetic acid (NAA), followed by removal of TDZ from the culture medium. Kanamycin and hygromycin proved to be efficient selectable markers for genetic transformation. Two Agrobacterium strains, C58 and EHA105 harboring binary vectors carrying the selectable marker genes hpt and nptII were chosen for transformation experiments. They also contained the uidA gene coding sequence as reporter gene. After infecting with C58, 4 and 107 rooted plants on hygromycin-containing medium were obtained for Attar and Atomic cultivars, respectively. The four Attar plants and 82 Atomic plants expressed Gus in leaves, petioles, stems and roots as expected with a sequence driven by the 35S constitutive promoter. Polymerase Chain Reaction (PCR) screening was performed on Gus positive plants and 2 and 20 plants of Attar and Atomic were screened as PCR positive, respectively. After infection with EHA105, 23 and 133 rooted plants were obtained on kanamycin selection medium but none of these expressed Gus. Southern hybridization patterns will enable to correlate gene copy numbers to expression levels in these different events. The optimized protocols could be used for understanding molecular mechanisms of Pb accumulation and improvement in phytoextraction technique.

Focusing on four novels by Janet Frame in dialogue with texts by Freud, Zizek, Lacan, and Silverman, my project theorizes trauma as the basis for both an ethical and an interpretive practice. Frame's fiction develops a cultural psychology, showing how the factors of narcissistic fantasy and the incapacity to mourn contribute to physical and epistemic aggression committed along divides of ethnicity, gender, and linguistic mode of expression. Employing trauma as a figure for an absolute limit to what can be remembered or known, I suggest that reconciliation with whatever is inaccessible, lacking, or dead within an individual or collective self fosters a non-violent relation with others. I begin by querying the place of "catharsis" within hermeneutic literary interpretation, focusing on the construction of Frame within the New Zealand literary industry. With Erlene's adamantine silence at its centre, Scented Gardens for the Blind (1964) rejects the hermeneutic endeavour, exemplified by Patrick Evans' critical work on Frame, to make a text "speak" its secrets. My readings of Intensive Care (1910) and The Adaptable Man (1965) address inter-generational repetitions of violence as the consequences of the failure to recognise and work through the devastations of war. The masculine fantasy of totality driving the Human Delineation project in Intensive Care has a linguistic corollary in Colin Monk's pursuit of the Platonic ideality of algebra, set against Milly's "degraded" punning writing. In The Adaptable Man, the arrival of electricity ushers in a new perceptual regime that would obliterate any "shadow" of dialectical negativity or internal difference. The thesis ends with a swing toward conciliation and emotional growth. The homosexual relationship depicted in Daughter Buffalo (1972) offers a model of transference, defined as a transitional, productive form of repetition that opens Talbot to his ethnic and familial inheritance. Working from within a radical form of narcissism, the novel reformulates masculinity by embracing loss as "phallic divestiture" (Kaja Silverman).

Focusing on four novels by Janet Frame in dialogue with texts by Freud, Zizek, Lacan, and Silverman, my project theorizes trauma as the basis for both an ethical and an interpretive practice. Frame's fiction develops a cultural psychology, showing how the factors of narcissistic fantasy and the incapacity to mourn contribute to physical and epistemic aggression committed along divides of ethnicity, gender, and linguistic mode of expression. Employing trauma as a figure for an absolute limit to what can be remembered or known, I suggest that reconciliation with whatever is inaccessible, lacking, or dead within an individual or collective self fosters a non-violent relation with others. I begin by querying the place of "catharsis" within hermeneutic literary interpretation, focusing on the construction of Frame within the New Zealand literary industry. With Erlene's adamantine silence at its centre, Scented Gardens for the Blind (1964) rejects the hermeneutic endeavour, exemplified by Patrick Evans' critical work on Frame, to make a text "speak" its secrets. My readings of Intensive Care (1910) and The Adaptable Man (1965) address inter-generational repetitions of violence as the consequences of the failure to recognise and work through the devastations of war. The masculine fantasy of totality driving the Human Delineation project in Intensive Care has a linguistic corollary in Colin Monk's pursuit of the Platonic ideality of algebra, set against Milly's "degraded" punning writing. In The Adaptable Man, the arrival of electricity ushers in a new perceptual regime that would obliterate any "shadow" of dialectical negativity or internal difference. The thesis ends with a swing toward conciliation and emotional growth. The homosexual relationship depicted in Daughter Buffalo (1972) offers a model of transference, defined as a transitional, productive form of repetition that opens Talbot to his ethnic and familial inheritance. Working from within a radical form of narcissism, the novel reformulates masculinity by embracing loss as "phallic divestiture" (Kaja Silverman). / Arts, Faculty of / English, Department of / Graduate