Browsing by Author "Pillay, Lavanya."
Now showing 1 - 2 of 2
- Results Per Page
- Sort Options
Item Identification and quantification of chelidonic acid and other ligands with potential for Ni uptake in the hyperaccumulator, Berkheya coddii.(2014) Naicker, Chrisanne.; Pillay, Lavanya.; Kindness, Andrew.B. coddii is a known nickel hyperaccumulator, a plant that is able to take up high levels of Ni (< 37 000 mg kg -1) without exhibiting toxic effects. It grows in serpentine soil and is endemic to the Barberton Region, Mpumulanga Province, South Africa. One of the key factors governing hyperaccumulators is the mechanism of uptake. This study investigates the uptake mechanism of B. coddii. Plants and soil from this region were collected for analysis and uptake studies (Ni spiking). A characterisation of amino and organic acids, both commonly associated with uptake in hyperaccumulators, was carried out using a range of chromatographic techniques namely, reverse phase-high performance liquid chromatography (RP-HPLC) and liquid chromatography-mass spectrometry (LC-MS). Amino acid analysis results showed a high proline concentration (12 400 mg kg-1) in younger leaves of B. coddii, and organic acid results showed high levels of ascorbic acid (2100 mg kg-1) present in the stem, indicating a stress response to high levels of Ni. Analysis carried out on B. coddii, using methods of size exclusion chromatography (SEC), high resolution-mass spectrometry (HR-MS) and HPLC indicated that the ligand responsible for Ni uptake is the organic acid, chelidonic acid. This study has shown that a leaf-water extract contains chelidonic acid in a 3:1 molar ratio to Ni. Nickel uptake studies were performed to further investigate the relationship between Ni and chelidonic acid. Upon treatment of B. coddii with soluble Ni the concentrations of Ni and chelidonic acid increased. This resulted in an increase of the molar ratio between chelidonic acid and Ni to 6.76:1.Item Investigating ingroup bias in an interactive minimal group environment.(2014) Pillay, Lavanya.; Durrheim, Kevin Locksley.Objectives: The general problematic of social science research is located in individualized explanations of social and collectively based phenomena. This is due to methodological issues inherent in the way social research is conducted. Research on ingroup bias via the renowned minimal group studies is an exemplar of this general problem and is examined in this study. This research argued that explaining ingroup bias in terms of individuals’ psychological needs is insufficient. This is because the original paper and pencil test failed to account for the effects of social interaction and how the interaction unfolds over time. Consequently, the old problem of ingroup bias was revisited using a new technology: the Virtual Interaction Application (VIAPPL). Design: A within-subjects and between-groups experimental design was used. Methods: VIAPPL was used to replicate the original study but in a way that demonstrated how ingroup bias was produced in interaction over time. This was facilitated by the ‘Give and Get’ game, where participants allocated tokens to one another in a simulated game-like environment. A repeated measures ANOVA and social network analyses were used to analyse the data. Results: As predicted, 1) ingroup bias was found most likely to be manifest in social interaction characterised by group categorization, and 2) more ingroup bias was expressed when the group interaction is visible to those participating in the interaction. Ingroup bias did not amplify as the group interaction unfolded over time. However, there was evidence proving that ingroup bias is not static, as was previously thought. Instead, it changed by increasing and decreasing as the rounds of the game advanced. Furthermore, the investigation revealed that 1) participants distributed their tokens fairly when they acted with and without a group membership, 2) observing the interaction informed the way tokens were allocated in both individual and group conditions, and 3) reciprocity was not operant in the interaction. Conclusions: This study introduced a new framework for studies in the minimal group paradigm (MGP) that allowed participants to interact in a virtual environment and enabled both traditional ANOVA methods and social network analyses. By rendering social interaction visible in the MGP, this study moved beyond an individualized explanation of social interaction by offering a social explanation of the behaviours manifested.