http://hdl.handle.net/10204/680 Mon, 20 May 2013 12:00:33 GMT 2013-05-20T12:00:33Z http://hdl.handle.net/10204/6328 Title: Harvesting sunlight energy: a biophysics approach Authors: Smit, JE; Grobler, AF; Sparrow, RW Abstract: The most efficient light harvesting and energy transfer systems are found in nature as part of the photosynthesis process. In the photosynthetic system light energy is absorbed by antenna chlorophylls and this energy is then passed onto a reaction centre chlorophyll molecule where charge separation occurs in less than 100 ps and at about 95% efficiency. It has been shown that organised connective light harvesting complexes are required for long range energy transfer. By extracting these system fragments and maximising their organisational structure, similar artificial systems for energy sources and transfer system can potentially be developed. As a matrix to stabilize the system we are using a combination of fatty acids and nitrous oxide, rather than conventional phospholipid-based combinations, which enables the production of small, elastic artificial vesicles, called Pheroid™. Previous work has shown that photosynthetic light harvesting material can be incorporated into the Pheroid™. In this study we are characterising the level of organisation through protein aggregation on the incorporated light harvesting systems using absorption spectroscopy. Description: ICWIP 2011: 4th IUPAP International Conference on Women in Physics, Stellenbosch, 5-8 April 2011 Fri, 01 Apr 2011 00:00:00 GMT http://hdl.handle.net/10204/6328 2011-04-01T00:00:00Z http://hdl.handle.net/10204/6294 Title: Subterranean sympatry: An investigation into diet using stable isotope analysis Authors: Robb, GN; Woodborne, S; Bennett, NC Abstract: In the Western Cape three species of mole-rat occur in sympatry, however, little is known about differences in their dietary preferences. Dietary composition of the three species; the common mole-rat (Cryptomys hottentotus hottentotus), the Cape mole-rat (Georychus capensis) and the Cape dune mole-rat (Bathyergus suillus) were examined using stable isotope analysis. Blood, fur and claw samples were collected from 70 mole-rats, in addition to several potential food items, to assess food selection of the three species under natural conditions. Overall there was a significant difference in the isotopic composition (d13C and d15N) between all three species and significant differences in their diet composition. There were also significant differences between tissues in all three species suggesting temporal variation in diet. The small size and colonial lifestyle of C. h. hottentotus allows it to feed almost 100% on bulbs, while the solitary and larger species G. capensis and B. suillus fed to a greater extent on other resources such as grasses and clover. B. suillus, the largest of the species, had the most generalized diet. However, overall all species relied most heavily upon geophytes and consumed the same species suggesting competition for resources could exist. We also showed a high level of individual variation in diet choices. This was most pronounced in B. suillus and G. capensis and less so in C. h. hottentotus. We demonstrate that stable isotope analysis can successfully be applied to examine dietary patterns in subterranean mammals and provide insights into foraging patterns and dietary variation at both the inter and intra population level. Description: Copyright: 2012 Robb et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Thu, 01 Nov 2012 00:00:00 GMT http://hdl.handle.net/10204/6294 2012-11-01T00:00:00Z http://hdl.handle.net/10204/6257 Title: Performance evaluation of spot detection algorithms in fluorescence microscopy images Authors: Mabaso, M; Twala, B; Withey, D; Utete, S Abstract: Detection of messenger Ribonucleic Acid (mRNA) spots in fluorescence microscopy images is of great importance for biologists seeking better understanding of cell functionality. Fluorescence microscopy and specific staining methods make biological molecules appear as bright spots in image data. Manual analysis of such data is both time-consuming and laborious, and can lead to errors. In this study, we compare two computer-based detection methods used in fluorescence microscopy images for the detection of spots. The algorithms compared are the Isotropic Undecimated Wavelet Transform (IUWT) and the Feature Particle Detection (FPD). The performance of these algorithms is validated on synthetic images. Our study finds a major difference in the performance of the two algorithms. IUWT performs better than FPD. Description: 4th CSIR Biennial Conference: Real problems relevant solutions, CSIR, Pretoria, 9-10 October 2012 Mon, 01 Oct 2012 00:00:00 GMT http://hdl.handle.net/10204/6257 2012-10-01T00:00:00Z http://hdl.handle.net/10204/6234 Title: Gel and gel-free approaches for the quantitative characterisation of complex protein mixtures Authors: Buthelezi, S; Tsekoa, T; Stoychev, S; Mancama, D; Blackburn, J Abstract: The research aims to establish a reliable set of methods for profiling proteins in a complex mixture in order to allow for the mining of low abundant species. Description: 4th CSIR Biennial Conference: Real problems relevant solutions, CSIR, Pretoria, 9-10 October 2012 Mon, 01 Oct 2012 00:00:00 GMT http://hdl.handle.net/10204/6234 2012-10-01T00:00:00Z