Embrace! Invest! Flourish!: Africa rising
- Authors: Malila, Vanessa
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159539 , vital:40306 , https://hdl.handle.net/10520/EJC134110
- Description: Currently the trend across Africa within the media landscape is growth - compared with its European and American counterparts who are feeling the full weight of the current financial crisis which has seen many newspapers downsize, cut jobs and suffer massive cost cutting strategies.
- Full Text:
Exploring relationship between value-and life-orientation and job satisfaction:
- Authors: Louw, Lynette , Mayer, Claude-Hélène , Baxter, Jeremy
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142782 , vital:38116 , DOI: 10.4102/ac.v12i1.131
- Description: The purpose of this article is to investigate the relationship between value- and life-orientation and job satisfaction, as well as determining the influence of gender, age and cultural group within the selected South African organisational context.
- Full Text:
Facile deposition of gold nanoparticle thin films on semi-permeable cellulose substrate
- Authors: Sosibo, Ndabenhle , Mdluli, Phumlani , Mashazi, Philani N , Tshikhudo, Robert , Skepu, Amanda , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242638 , vital:51063 , xlink:href="https://doi.org/10.1016/j.matlet.2012.08.043"
- Description: This study reports the facile method for the deposition of gold nanoparticle thin film onto a monoporous semi-permeable cellulose membrane through the diffusion of borohydride ions leading to the reduction of AuCl4− ions. The synthesis of gold nanoparticle thin film was deposited on one side of the membrane that was exposed to AuCl4− ions while the other side containing a reducing agent remained clear. The gold nanoparticle thin film exhibited a broad surface plasmon resonance (SPR) peak at 529 nm. Various characterization techniques were employed and all demonstrated the presence of gold thin film. The reported method represents a simplistic method for the deposition of gold nanoparticle thin films and various other metal nanoparticles may be deposited following this method.
- Full Text:
Fig wasps as vectors of mites and nematodes
- Authors: Jauharlina, J , Lindquist, E E , Quinnell, R J , Compton, Stephen G , Robertson, Hamish G
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452076 , vital:75101 , https://hdl.handle.net/10520/EJC119300
- Description: Females of the pollinator fig wasp Elisabethiella baijnathi Wiebes carry mites (Tarsonemella sp. nr. africanus) and nematodes (Parasitodiplogaster sp.) between figs of Ficus burtt-davyi in Grahamstown, South Africa. The mites are phoretic on the outside of the wasps and phytophagous, feeding on galled flowers. The nematodes are transported inside the wasps and eventually eat them. Both mites and nematodes were present throughout the year. The prevalence (fig occupancy rates) of mites and nematodes in different crops ranged between zero and 100 %. Crop size did not influence the prevalence of either mites or nematodes. Contrasting dispersion patterns and relationships with fig wasp foundress numbers indicate that the mites, but not the nematodes, disperse between figs after being carried there by the pollinators, and they may also utilize non-pollinating fig wasps as vectors.
- Full Text:
Firm age, collateral value, and access to debt financing in an emerging economy: evidence from South Africa
- Authors: Ezeoha,Abel , Botha, Ferdi
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396060 , vital:69147 , xlink:href="https://hdl.handle.net/10520/EJC31367"
- Description: This paper applies the Blundell and Bond system generalised method of moments (GMM) two-step estimator to examine the impact of age and collateral value on debt financing, using a panel of 177 non-financial companies listed on the Johannesburg Stock Exchange over the period 1999 to 2009. The results show that South African firms have target leverage ratios and adjust their capital structures from time to time to achieve their respective targets, that the relationship between firm age and debt financing is non-monotonic, and that firms with higher collateral value are likely to face fewer constraints on borrowing and therefore have greater access to medium-term and long-term debts. Robustness tests also reveal that during start-up and maturity stages, a firm's access to debt markets is significantly influenced by investments in assets that are acceptable to external creditors as collateral. These findings suggest that debt financing policies could be more critical for firms in the start-up and maturity stages.
- Full Text:
Five unpublished coins of Alexander the Great and his successors in the Rhodes University Collection
- Authors: Snowball, Jeanette D , Snowball, Warren D
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68489 , vital:29267 , http://dx.doi.org/10.7445/50-0-73
- Description: Publisher version , The article briefly discusses the economic and political significance of the Alexander III (“the Great”) type silver tetradrachm and publishes three of his coins currently held by the Rhodes University Classics Museum. Based on stylistic elements, they are classified as from the Amphipolis and Arados mints and were probably minted during his lifetime. Two further tetradrachms from the empires of Alexander’s successors, Ptolemy II and Seleucus IV, are also published.
- Full Text:
Functional programming and security
- Authors: Motara, Yusuf, M
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/428985 , vital:72551 , https://doi.org/10.48550/arXiv.1201.5728
- Description: This paper analyses the security contribution of typical functional-language features by examining them in the light of accepted information security principles. Imperative and functional code are compared to illustrate various cases. In conclusion, there may be an excellent case for the use of functional languages on the grounds of better security; however, empirical research should be done to validate this possibility.
- Full Text:
Geo-spatial autocorrelation as a metric for the detection of fast-flux botnet domains
- Authors: Stalmans, Etienne , Hunter, Samuel O , Irwin, Barry V W
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429799 , vital:72640 , 10.1109/ISSA.2012.6320433
- Description: Botnets consist of thousands of hosts infected with malware. Botnet owners communicate with these hosts using Command and Control (C2) servers. These C2 servers are usually infected hosts which the botnet owners do not have physical access to. For this reason botnets can be shut down by taking over or blocking the C2 servers. Botnet owners have employed numerous shutdown avoidance techniques. One of these techniques, DNS Fast-Flux, relies on rapidly changing address records. The addresses returned by the Fast-Flux DNS servers consist of geographically widely distributed hosts. The distributed nature of Fast-Flux botnets differs from legitimate domains, which tend to have geographically clustered server locations. This paper examines the use of spatial autocorrelation techniques based on the geographic distribution of domain servers to detect Fast-Flux domains. Moran's I and Geary's C are used to produce classifiers using multiple geographic co-ordinate systems to produce efficient and accurate results. It is shown how Fast-Flux domains can be detected reliably while only a small percentage of false positives are produced.
- Full Text:
Guy Butler’s South Africanism: ‘Being present where you are’
- Authors: Wright, Laurence
- Date: 2012
- Language: English
- Type: text , article
- Identifier: vital:7069 , http://hdl.handle.net/10962/d1007460 , https://doi.org/10.1080/10131752.2012.730182
- Description: preprint , A peer-reviewed lecture delivered at Rhodes University on the occasion of the presentation to Professor Wright of the English Academy's Gold Medal, 16 November 2011. Guy Butler (1918-2001) has been gone some ten years. This lecture sets out to illuminate the thinking behind his important role in South Africa's national life. The institutions he created continue to make vital cultural contributions in South Africa's efforts to make sense of its own complex historical make-up, working towards a happier, richer, and more equal future. However, despite what he achieved, there is little surety that today the rationale informing his massive effort to foster processes of artistic and cultural endeavour has been appreciated or accurately understood.
- Full Text:
Having a phone, having style:
- Authors: Schoon, Alette
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159506 , vital:40303 , https://hdl.handle.net/10520/EJC135828
- Description: It was dusk, and a group of young men with a dog trailing behind them, were walking past on a dusty township road in Hooggenoeg, an RDP village on the rim of the Grahamstown bowl. While they ambled along, one was holding up a mobile phone on which music was playing, dancing while he walked. This was exactly the kind of thing I was hoping to observe in my new identity as researcher and participant observer, and was why I had agreed to judge the Hooggenoeg fashion show which turned out to be more of a beauty competition. While I'm not generally fond of these kind of shows and the way they essentialise beauty, I agreed because I wanted to get more of a sense of how mobile phones are integrated into the everyday lives of these young adults.
- Full Text:
Higher education, academic communities, and the intellectual virtues
- Authors: Jones, Ward E
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275647 , vital:55066 , xlink:href="https://doi.org/10.1111/edth.12005"
- Description: Because higher education brings members of academic communities in direct contact with students, the reflective higher education student is in an excellent position for developing two important intellectual virtues: confidence and humility. However, academic communities differ as to whether their members reach consensus, and their teaching practices reflect this difference. In this essay, Ward Jones argues that both consensus-reaching and non-consensus-reaching communities can encourage the development of intellectual confidence and humility in their students, although each will do so in very different ways.
- Full Text:
How do HIV and AIDS impact the use of natural resources by poor rural populations?: The case of wild animal products
- Authors: Kaschula, Sarah , Shackleton, Charlie M
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182344 , vital:43822 , xlink:href="https://hdl.handle.net/10520/EJC97203"
- Description: As a result of heightened financial and food insecurity, populations adversely affected by HIV and/or AIDS may be more likely to utilise wild natural resources to supplement their diet and livelihoods. Should this effect be pronounced, HIV and AIDS may pose a serious environmental threat. We explored the hypothesis that the presence of factors in the household, such as chronic illness in and recent mortality of individuals in a high HIV-risk age group, as well as the fostering of orphans, are associated with increased utilisation of wild animal products (WAPs) at the household level. We randomly surveyed 519 households from four sites in rural South Africa, recording household socio-economic status, the utilisation of wild animal products and health and demographic factors attributed to HIV or AIDS. Binary logistic regressions were used to test if households with markers of HIV and/or AIDS affliction were more likely to have a higher incidence and frequency of WAP utilisation relative to non-afflicted households, after adjusting for socio-economic and demographic variables. We found that, although households with markers of HIV and/or AIDS were generally poorer and had higher dependency ratios, there was no evidence to support the hypothesis that WAP harvesting was associated with either poverty, or markers of HIV and/or AIDS affliction. Our findings suggest that generalisations about a possible interaction between HIV and/or AIDS and the environment may not uniformly apply to all categories of natural resources or to all user groups.
- Full Text:
Imidazole-functionalized polymer microspheres and fibers–useful materials for immobilization of oxovanadium (IV) catalysts
- Authors: Walmsley, Ryan S , Ogunlaja, Adeniyi S , Coombes, Matthew J , Chidawanyika, Wadzanai J U , Litwinski, Christian , Torto, Nelson , Nyokong, Tebello , Tshentu, Zenixole R
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246041 , vital:51431 , xlink:href="https://doi.org/10.1039/C2JM15485D"
- Description: Both polymer microspheres and microfibers containing the imidazole functionality have been prepared and used to immobilize oxovanadium(IV). The average diameters and BET surface areas of the microspheres were 322 μm and 155 m2 g−1 while the fibers were 1.85 μm and 52 m2 g−1, respectively. XPS and microanalysis confirmed the incorporation of imidazole and vanadium in the polymeric materials. The catalytic activity of both materials was evaluated using the hydrogen peroxide facilitated oxidation of thioanisole. The microspheres were applied in a typical laboratory batch reactor set-up and quantitative conversions (>99%) were obtained in under 240 min with turn-over frequencies ranging from 21.89 to 265.53 h−1, depending on the quantity of catalyst and temperature. The microspherical catalysts also proved to be recyclable with no drop in activity being observed after three successive reactions. The vanadium functionalized fibers were applied in a pseudo continuous flow set-up. Factors influencing the overall conversion and product selectivity, including flow rate and catalyst quantity, were investigated. At flow rates of 1–4 mL h−1 near quantitative conversion was maintained over an extended period. Keeping the mass of catalyst constant (0.025 g) and varying the flow rate from 1–6 mL h−1 resulted in a shift in the formation of the oxidation product methyl phenyl sulfone from 60.1 to 18.6%.
- Full Text:
In vitro photodynamic effect of aluminum tetrasulfophthalocyanines on melanoma skin cancer and healthy normal skin cells
- Authors: Maduray, Kaminee , Odhay, Bharti , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245762 , vital:51403 , xlink:href="https://doi.org/10.1016/j.pdpdt.2011.07.001"
- Description: Photodynamic therapy is a medical treatment that uses an inactive dye/drug and lasers as a light source to activate the dye/drug to produce a toxic form of oxygen that destroys the cancer cells. This study aimed at investigating the cytotoxic effects of different concentrations of aluminum tetrasulfophthalocyanines in its inactive and active state (laser induced) on melanoma skin cancer cells, healthy normal skin fibroblast and keratinocyte cells. Experimentally, 3 x 10(4) cells/ml were seeded in 24-well plates before treatment with different concentrations of aluminum tetrasulfophthalocyanines. After 2 h, cells were irradiated with a light dose of 4.5 J/cm(2). Post-irradiated cells were incubated for 24 h before cell viability was measured using the CellTiter-Blue Viability Assay. Results showed that aluminum tetrasulfophthalocyanines at high concentrations were cytotoxic to melanoma cells in the absence of laser activation. In the presence of laser activation of aluminum tetrasulfophthalocyanines at a concentration of 40 mu g/ml decreased cell viability of melanoma cells to 45%, fibroblasts to 78% and keratinocytes to 73%. At this photosensitizing concentration of aluminum tetrasulfophthalocyanines the efficacy of the treatment light dose 4.5 J/cm(2) and the cell death mechanism induced by photoactivated aluminum tetrasulfophthalocyanines was evaluated. A light dose of 4.5 J/cm(2) was more efficient in killing a higher number of melanoma cells and a lower number of fibroblast and keratinocyte cells than the other light doses of 2.5 J/cm(2), 7.5 J/cm(2) and 10.5 J/cm(2). Apoptosis features such as blebbing, nucleus condensation, nucleus fragmentation and the formation of apoptotic bodies were seen in the photodynamic therapy treated melanoma skin cancer cells. This in vitro photodynamic therapy study concludes that using aluminum tetrasulfophthalocyanines at a photosensitizing concentration of 40 mu g/ml in combination with a laser dose of 4.5 J/cm(2) was potentially lethal for melanoma skin cancer cells and less harmful for the normal healthy skin cells. (c) 2011 Elsevier B.V. All rights reserved.
- Full Text:
Inferring direct DNA binding from ChIP-seq
- Authors: Bailey, Timothy L , Machanick, Philip
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/439314 , vital:73565 , https://doi.org/10.1093/nar/gks433
- Description: Genome-wide binding data from transcription factor ChIP-seq experiments is the best source of information for inferring the relative DNA-binding affinity of these proteins in vivo . However, standard motif enrichment analysis and motif discovery approaches sometimes fail to correctly identify the binding motif for the ChIP-ed factor. To overcome this problem, we propose ‘central motif enrichment analysis’ (CMEA), which is based on the observation that the positional distribution of binding sites matching the direct-binding motif tends to be unimodal, well centered and maximal in the precise center of the ChIP-seq peak regions. We describe a novel visualization and statistical analysis tool—CentriMo—that identifies the region of maximum central enrichment in a set of ChIP-seq peak regions and displays the positional distributions of predicted sites. Using CentriMo for motif enrichment analysis, we provide evidence that one transcription factor (Nanog) has different binding affinity in vivo than in vitro , that another binds DNA cooperatively (E2f1), and confirm the in vivo affinity of NFIC, rescuing a difficult ChIP-seq data set. In another data set, CentriMo strongly suggests that there is no evidence of direct DNA binding by the ChIP-ed factor (Smad1). CentriMo is now part of the MEME Suite software package available at http://meme.nbcr.net . All data and output files presented here are available at: http://research.imb.uq.edu.au/t.bailey/sd/Bailey2011a .
- Full Text:
Integrating stomach content and stable isotope analyses to elucidate the feeding habits of non-native sharptooth catfish Clarias gariepinus
- Authors: Kadye, Wilbert T , Booth, Anthony J
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124843 , vital:35703 , https://doi.10.1007/s10530-011-0116-6
- Description: Sharptooth catfish Clarias gariepinus was introduced into the Eastern Cape Province, South Africa, in 1976 and there are concerns about its possible negative impacts on native biota. This study investigated its trophic impact by examining its feeding habits. Stomach content and stable isotope analyses were compared from three localities—the Great Fish River, Sundays River and Glen Melville Dam. Stomach content analysis indicated a catholic diet dominated by fish particularly in all localities.Spatially, however, the diets revealed differences based on the dominance of macrophytes that were only present in the rivers, and aquatic invertebrates that appeared more diverse within the Great Fish River compared to other localities. By contrast, stable isotopes revealed a more generalised feeding pattern with no clear dominance of particular prey. Stable isotopes further showed that the catfish was a complex predator, with large catfish being top predators whereas smaller size groups appeared to feed lower in the food chain. An ontogenetic shift in diet was evident, with small fish predominantly consuming aquatic invertebrates and shifting towards fish with increasing size. High dietary overlap suggests the potential risk associated catfish feeding, especially the potential of piscivory by small catfish that are more likely to persist in shallow and marginal where endangered indigenous minnows occur. The alteration of environmental conditions, especially flow by inter basin water transfer (IBWT) schemes, was inferred to have had a probable influence its invasion success. Occurrence of other invaders, which was facilitated by the IBWT together with the catfish, posits the risk of invasion meltdown within the study systems.
- Full Text:
Inter-seasonal persistence and size-structuring of two minnow species within headwater streams in the Eastern Cape, South Africa
- Authors: Kadye, Wilbert T , Booth, Anthony J
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124866 , vital:35705 , https://doi.10.1111/j.1439-0426.2012.02027.x
- Description: This study examined temporal variation in population dynamics and size structuring of two cyprinid minnows, Pseudobarbus afer and Barbus anoplus, in relation to their proximate physical habitats. Population estimates were determined using three-pass depletion sampling during both summer and winter. The habitats were characterised by seasonal variation in all physico-chemical conditions and spatial variation in substrata compositions. Whereas significant differences in population size were noted between seasons for B. anoplus, no differences were found between seasons for density and capture probability for either species. An increase in boulders was associated with increase in population size and density for P. afer; for B. anoplus, increased percentages of bedrock and bank vegetation were associated with an increase in population size and probability of capture, respectively. According to Canonical Correspondence Analysis, size structuring in P. afer was explained predominantly by seasonality, with smaller length classes associated with the seasonal variable of summer, while larger length classes were associated with pH that was higher in winter. By comparison, for B. anoplus, the habitat variables – bank vegetation and bedrock – accounted for much of the explained variance for size structuring. Recruitment appeared to be the major driver of size structuring for the two species; refugia, especially boulders and bank vegetation, also appeared to be important. Overall, the two species were adapted to the headwater streams that were generally variable in environmental conditions. Potential invasions by non-native invasive fishes that occur within the mainstream habitats threaten these two species. Efforts should continue to protect these minnows from such invasions by constructing barriers to upstream migration of non-native fishes into these headwater habitats.
- Full Text:
Interaction of CdTe quantum dots with 2, 2-diphenyl-1-picrylhydrazyl free radical
- Authors: Adegoke, Oluwasesan , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/245751 , vital:51402 , xlink:href="https://doi.org/10.1007/s10895-011-1012-2"
- Description: The interaction of 2,2-diphenyl-1-picrylhydrazyl (DPPH●) free radical with thiol-capped CdTe quantum dots (QDs) has been studied by UV–vis spectroscopy, steady state and time resolved fluorescence measurements. Addition of DPPH● radical to CdTe QDs resulted in fluorescence quenching. The interaction occurs through static quenching as this was confirmed by fluorescence lifetime measurements. Time course absorption studies indicates that DPPH● may be reduced by interaction with QDs to the substituted hydrazine form (2,2-diphenyl-1-picrylhydrazine) DPPH-H. The mechanism of fluorescence quenching of CdTe QDs by DPPH● is proposed.
- Full Text:
Investigating water knowledge flow to communities
- Authors: Burt, Jane C , Berold, Robert
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/433013 , vital:72923 , xlink:href="https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/KV%20288-11.pdf"
- Description: Those of us who work in water resource management have found that very few knowledge/research resources are accessible to most people. This happens because resources are not disseminated properly (or at all), or because they are inappropriately technicist, or because potential readers are hampered by low education. What is the best way to make water research accessible to as many people as possible and especially to people whose lives would be affected by the research? In the early 1980s an attempt was made to address this issue when Robert Berold edited People's Workbook (EDA 1981), a user-friendly book that presented basic technical information for rural people – not only on water, but also on agriculture, health, building construction, and income generation. The book included real-life interviews, and was disseminated by rural fieldworkers. Perhaps because there was nothing like it at the time, it was enormously popular.
- Full Text:
Is there no urban forestry in the developing world?
- Authors: Shackleton, Charlie M
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181060 , vital:43695 , xlink:href="https://doi.org/10.5897/SRE11.1117"
- Description: Urban forestry and greening offer a multitude of benefits to the inhabitants of towns and cities. However, the nature and magnitude of these frequently depend upon the context. Yet, at first glance, the developing world context around urban forestry debates seems to be poorly represented in the international peer-reviewed literature. This is examined in this paper, followed by a brief outline of ten key research areas for urban forestry in the developing world. A survey of the peer-reviewed literature confirms that almost 80% of articles come from the developed world context. This correlates with the greater availability of research finance and personnel from developed regions. However, there are urban forestry questions and issues that require examination in the developing world because they cannot simply be transferred from knowledge gleaned from and tested in a developed world context. Ten of these are briefly outlined as a catalyst towards greater attention to urban forestry in the developing world and their contributions to global debates and models.
- Full Text: