List of Titles

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A probabilistic movement model for shortest path formation in virtual ant-like agents

- Chibaya, Colin, Bangay, Shaun D

Authors: Chibaya, Colin , Bangay, Shaun D
Date: 2007
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/433125 , vital:72945 , https://doi.org/10.1145/1292491.1292493
Description: We propose a probabilistic movement model for controlling ant-like agents foraging between two points. Such agents are all identical, simple, autonomous and can only communicate indirectly through the environment. These agents secrete two types of pheromone, one to mark trails towards the goal and another to mark trails back to the starting point. Three pheromone perception strategies are proposed (Strategy A, B and C). Agents that use strategy A perceive the desirability of a neighbouring location as the difference between levels of attractive and repulsive pheromone in that location. With strategy B, agents perceive the desirability of a location as the quotient of levels of attractive and repulsive pheromone. Agents using strategy C determine the product of the levels of attractive pheromone with the complement of levels of repulsive pheromone. We conduct experiments to confirm directionality as emergent property of trails formed by agents that use each strategy. In addition, we compare path formation speed and the quality of the formed path under changes in the environment. We also investigate each strategy's robustness in environments that contain obstacles. Finally, we investigate how adaptive each strategy is when obstacles are eventually removed from the scene and find that the best strategy of these three is strategy A. Such a strategy provides useful guidelines to researchers in further applications of swarm intelligence metaphors for complex problem solving.
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Date Issued: 2007

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Health, human rights, and the conduct of clinical research within oppressed populations

- Mills, E J, Singh, S

Authors: Mills, E J , Singh, S
Date: 2007
Language: English
Type: Article
Identifier: vital:6411 , http://hdl.handle.net/10962/d1006504 , http://dx.doi.org/10.1186/1744-8603-3-10
Description: Background Clinical trials evaluating interventions for infectious diseases require enrolling participants that are vulnerable to infection. As clinical trials are conducted in increasingly vulnerable populations, issues of protection of these populations become challenging. In settings where populations are forseeably oppressed, the conduct of research requires considerations that go beyond common ethical concerns and into issues of international human rights law. Discussion Using examples of HIV prevention trials in Thailand, hepatitis-E prevention trials in Nepal and malaria therapeutic trials in Burma (Myanmar), we address the inadequacies of current ethical guidelines when conducting research within oppressed populations. We review existing legislature in the United States and United Kingdom that may be used against foreign investigators if trial hardships exist. We conclude by making considerations for research conducted within oppressed populations.
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Date Issued: 2007

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The habitus of the dominant: addressing rape and sexual assault at Rhodes University

- de Klerk, Vivian A, Klazinga, Larissa, McNeill, Amy

Authors: de Klerk, Vivian A , Klazinga, Larissa , McNeill, Amy
Date: 2007
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/453352 , vital:75247 , https://doi.org/10.1080/10130950.2007.9674885
Description: This article seeks to describe the changing ways in which Rhodes University has addressed rape and sexual assault. By highlighting the evolution of policies and methodologies, it aims to identify possible shortcomings of the past, and offer new strategies and principles which may be useful to fellow institutions grappling with sexual violence issues.
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Date Issued: 2007

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Unexpected genetic structure of mussel populations in South Africa: indigenous Perna perna and invasive Mytilus galloprovincialis

- Zardi, Gerardo I, McQuaid, Christopher D, Teske, Peter R, Barker, Nigel P

Authors: Zardi, Gerardo I , McQuaid, Christopher D , Teske, Peter R , Barker, Nigel P
Date: 2007
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/445564 , vital:74401 , doi:10.3354/meps337135
Description: Genetic structure of sedentary marine organisms with planktonic larvae can be influenced by oceanographic transport, larval behaviour and local selection. We analysed the population genetic structure (based on mtDNA) of the invasive mussel Mytilus galloprovincialis and the indigenous mussel Perna perna along the southern African coastline. Low genetic divergence of M. galloprovincialis confirms its recent arrival in South Africa. In contrast, the genetic structure of P. perna revealed strong divergence on the south-east coast, forming a western and an eastern lineage. The distribution of the 2 lineages is extraordinary. They overlap for ca. 200 km on the south-east coast, and the western lineage includes animals occurring on either side of a 1000 km break in distribution across the Benguela upwelling system. In cluster analyses, animals on the south coast grouped with others 1000s of km to the west, rather than with those only 200 km to the east.
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Date Issued: 2007

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Commentary: Negotiating distant influences: globalization and broadcasting policy reforms in Zambia and South Africa

- Banda, Fackson

Authors: Banda, Fackson
Date: 2006
Language: English
Type: text , article
Identifier: vital:6325 , http://hdl.handle.net/10962/d1008299 , https://doi.org/10.22230/cjc.2006v31n2a1785
Description: preprint , This commentary looks at the influences of globalisation on broadcasting policy reforms in Zambia and South Africa, with specific focus on such processes as deregulation, privatisation, commercialisation, communitarianism and technological convergence. It concludes that globalisation does not affect southern African countries uniformly; rather, it is refracted in accordance with the different cultural and political experiences of such countries.
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Date Issued: 2006

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Larval development of the carrion-breeding flesh fly, Sarcophaga (Liosarcophaga) tibialis Macquart (Diptera: Sarcophagidae), at constant temperatures

- Villet, Martin H, MacKenzie, Bernard L, Muller, Nikite W J

Authors: Villet, Martin H , MacKenzie, Bernard L , Muller, Nikite W J
Date: 2006
Language: English
Type: text , Article
Identifier: vital:7091 , http://hdl.handle.net/10962/d1012422
Description: Larvae of Sarcophaga (Liosarcophaga) tibialis Macquart were raised on chicken liver under six different constant temperatures. Maximum survival indicated an optimal developmental temperature of near 20°C, while trends in mortality, larval length and larval mass implied that the thermal window for successful development lay between 15°C and 30°C. Using a recently described method to estimate a simple thermal summation model, it was found that the timing of the end of the feeding phase could be estimated by a developmental zero (D0) of 5.2°C (S.E. = 1.21) and a thermal summation constant (K) of 106.4 d°C (S.E. = 8.31) and of the end of the wandering phase by D0 = 4.1°C (S.E. = 0.39) and K = 126.7 d°C (S.E. = 3.28). Published development times at constant temperatures were compiled for 19 other species of flesh flies, and the developmental constants were calculated for six species for which sufficient data were accumulated.
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Date Issued: 2006

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Non-steroidal anti-inflammatory agents, tolmetin and sulindac, inhibit liver tryptophan 2,3-dioxygenase activity and alter brain neurotransmitter levels

- Dairam, A, Antunes, Edith M, Saravanan, K S, Daya, Santylal

Authors: Dairam, A , Antunes, Edith M , Saravanan, K S , Daya, Santylal
Date: 2006
Language: English
Type: Article
Identifier: vital:6358 , http://hdl.handle.net/10962/d1006050 , http://dx.doi.org/10.1016/j.lfs.2006.07.028
Description: Hepatic tryptophan 2,3-dioxygenase (TDO) is one of the rate-limiting enzymes in tryptophan catabolism and plays an important role in regulating the physiological flux of tryptophan into relevant metabolic pathways. In this study, we determined the effect of the non-steroidal anti-inflammatory agents, tolmetin and sulindac, on rat liver TDO activity and the subsequent changes in the hippocampal and striatal neurotransmitter levels. The amount of melatonin produced by the pineal gland was also measured using high performance liquid chromatography (HPLC). Treatment of rats with tolmetin or sulindac (5 mg/kg/bd for 5 days) significantly inhibited liver TDO activity. The results show that whilst tolmetin and sulindac increase serotonin levels in the hippocampus, these agents also significantly reduce dopamine levels in the striatum. Tolmetin, but not sulindac, increased the amount of melatonin produced by the pineal gland. The results of this study suggest that whilst tolmetin and sulindac may be beneficial for patients suffering from depression, these agents also have the potential to induce adverse effects in patients suffering with neurological disorders such as Parkinson's disease.
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Date Issued: 2006

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Restructuring manufacturing in South Africa's lagging regions : the case of the Free State

- Nel, Etienne L, Rogerson, C M, Marais, L

Authors: Nel, Etienne L , Rogerson, C M , Marais, L
Date: 2006
Language: English
Type: Article
Identifier: vital:6714 , http://hdl.handle.net/10962/d1006786
Description: The manufacturing economy of the Free State reflects both historical dependence on locally available raw materials and high-levels of state intervention, in terms of support for import substitution and Homeland development. In the contemporary era, deindustrialization, the uncertain future of the clothing / textile industries and limited growth over the last ten years, suggests that, in terms of manufacturing, the Free State is a 'lagging' region. While there has been significant expansion in the number of small firms, this is not matched by employment growth and does not compensate for the loss of many large firms and economic downscaling in the Goldfields. Key sectors such as petro-chemicals and gold jewellery present certain opportunities for future growth.
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Date Issued: 2006

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Spatio-temporal variability of larval abundance and settlement of Perna perna: differential delivery of mussels

- Porri, Francesca, McQuaid, Christopher D, Radloff, Sarah E

Authors: Porri, Francesca , McQuaid, Christopher D , Radloff, Sarah E
Date: 2006
Language: English
Type: text , Article
Identifier: vital:6877 , http://hdl.handle.net/10962/d1011625 , http://dx.doi.org/10.3354/meps315141
Description: We examined larval availability and settlement of the intertidal mussel Perna perna simultaneously at different spatial and temporal scales using a nested design at 2 sites, 3 km apart on the south coast of South Africa. Each site had 3 locations (300 m apart) where 5 artificial settler collectors were placed about 20 cm apart. Collectors were replaced on temporal scales varying from fortnightly (for 16 mo) to daily (2 series of 15 to 20 d). Each intertidal location was paired with an inshore location (these too were 300 m apart) within 500 m of the shore, where larval availability was measured by 3 vertical plankton hauls collected on the same dates as for settler sampling. There was strong temporal variation in abundances of larvae and settlers, and no correlation (r always < 0.14) was found between the two. Larvae were abundant only at the start of sampling and rare for the rest of the study, while distinct peaks in settler numbers occurred later. No spatial effect was detected for larval availability, while there was strong spatial variation in settlement at the location level. These results indicate that, on scales of 100s of m to km, delivery of larvae from the nearshore water column onto the shore is strongly differential, with some locations consistently receiving more settlers than others. We conclude that, at these sites, the patchiness in settlement observed on scales of 100s of m depends on differential delivery, rather than differential offshore distribution of larvae. We suggest that differential delivery is due to the effect of nearshore bottom topography on local hydrodynamics.
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Date Issued: 2006

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Synthesis of triprenylated toluquinone and toluhydroquinone metabolites from a marine-derived Penicillium fungus

- Scheepers, Brent A, Klein, Rosalyn, Davies-Coleman, Michael T

Authors: Scheepers, Brent A , Klein, Rosalyn , Davies-Coleman, Michael T
Date: 2006
Language: English
Type: Article
Identifier: vital:6592 , http://hdl.handle.net/10962/d1004341
Description: Two triprenylated toluquinone and toluhydroquinone marine fungal metabolites, 5-methyl-2-[(2′E,6′E)-3′,7′,11′-trimethyl-2′,6′,10′-dodecatrienyl]-2,5-cyclohexadiene-1,4-dione and 5-methyl-2-[(2′E,6′E)-3,7,11-trimethyl-2′,6′,10′-dodecatrienyl]-1,4-benzenediol, were synthesized in four and five steps, respectively, from 2-methyl-1,4-benzoquinone. The synthesis extends the applicability of the oxidative ether cleavage of hydroquinone dimethyl ethers with argentic oxide under acidic conditions to include the oxidative demethylation of polyprenylated-1,4-dimethoxy-toluhydroquinones with a quantitative survival of the oxidation- and acid-sensitive polyprenyl side chain. Graphical abstract: Marine fungal metabolites 1 and 2 were synthesized from 2-methyl-1,4-benzoquinone in four and five steps, respectively. [For graphic image see full-text version]
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Date Issued: 2006

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The South African coelacanths — an account of what is known after three submersible expeditions

- Hissmann, K, Fricke, H, Schauer, J

Authors: Hissmann, K , Fricke, H , Schauer, J
Date: 2006
Language: English
Type: text , Article
Identifier: vital:7131 , http://hdl.handle.net/10962/d1011772
Description: Using the manned submersible Jago, the habits, distribution and number of coelacanths within all main submarine canyons of the Greater St Lucia Wetland Park were studied during 47 survey dives, with a total bottom time of 166 hours at depths ranging from 46 to 359 m, between 2002 and 2004. Twenty-four individuals were positively identified from three of the canyons, primarily from inside caves at or close to the canyon edges at depths of 96–133 m with water temperatures between 16 and 22.5°C. The population size of coelacanths within the canyons is assumed to be relatively small; coelacanths are resident but not widespread nor abundant within the park.
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Date Issued: 2006

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A successful cognitive-behavioural intervention that failed : a case study of adolescent conduct disorder at a school for the disadvantaged

- Mashalaba, Eugenia D, Edwards, David J A

Authors: Mashalaba, Eugenia D , Edwards, David J A
Date: 2005
Language: English
Type: Article
Identifier: vital:6273 , http://hdl.handle.net/10962/d1008273
Description: Conduct Disorder (CD) is a widespread problem in southern Africa. The aim of the study was to design, implement and evaluate a multi-modal cognitive-behavioural intervention based on treatments developed overseas, in order to investigate whether this approach can be transported to a South African school for deprived children. The target adolescent had a history of severely disruptive behaviour and was facing expulsion from a shelter for homeless children and his school. A thorough assessment served as the basis for a case formulation and treatment plan. Intervention included 23 individual sessions focussing on bereavement and the learning of self-control skills and prosocial behaviours, as well as contingency management training for school and shelter staff. Progress was tracked with a behaviour checklist completed daily by the teacher and regular interviews with school and shelter staff. After four months, the disruptive behaviour was eliminated. However, he was involved in stealing with some other learners and expelled anyway. Nevertheless the case study provides evidence for the transportability of the cognitive-behavioural approach to this kind of setting and documents the way in which a comprehensive intervention can be tailored to the needs of a child with a severely deprived background and little social support.
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Date Issued: 2005

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An LC-MS-MS method for the determination of cyclizine in human serum

- Mohammadi, Ali, Kanfer, Isadore, Sewram, V, Walker, Roderick B

Authors: Mohammadi, Ali , Kanfer, Isadore , Sewram, V , Walker, Roderick B
Date: 2005
Language: English
Type: Article
Identifier: vital:6408 , http://hdl.handle.net/10962/d1006481
Description: Cyclizine is a piperazine derivative with anti-emetic activity that is useful in the prevention and treatment of nausea and vomiting associated with motion sickness. A liquid chromatography-tandem mass spectrometry (LC-MS-MS) method is presented for the quantitation of cyclizine in serum. Sample pretreatment involved liquid-liquid extraction of 200 μl of serum with dichloromethane after the addition of 100 μl each of ammonium hydroxide and internal standard solutions. The extracts were analyzed by HPLC on a Luna ® C18 reversed-phase column and an ion-trap mass spectrometer with an electrospray interface. A limit of detection of 1 ng/ml was determined which allowed for the reliable measurement of cyclizine in the serum of human subjects. The method was found to be linear over the calibration range of 2.5-100 ng/ml. The applicability of this method was demonstrated by the analysis of serum obtained from a human volunteer following administration of a single 50 mg cyclizine hydrochloride tablet. The reported method was observed to have the necessary sensitivity, selectivity, precision and accuracy for monitoring cyclizine concentrations in human subjects following oral administration.
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Date Issued: 2005

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Derivation of quantitative management objectives for annual instream water temperatures in the Sabie River using a biological index

- Rivers-Moore, Nick A, Jewitt, G P W, Weeks, D C

Authors: Rivers-Moore, Nick A , Jewitt, G P W , Weeks, D C
Date: 2005
Language: English
Type: text , Article
Identifier: vital:7093 , http://hdl.handle.net/10962/d1012426
Description: Adaptive management of river systems assumes uncertainty and makes provision for system variability. Inherent within this management approach is that perceived limits of 'acceptable' system variability are regarded not only as testable hypotheses, but also as playing a central role in maintaining biodiversity. While the Kruger National Park currently functions as a flagship conservation area in South Africa, projected increases in air temperatures as a consequence of global climate change present challenges in conserving this biodiversity inside the established land boundaries. Within the rivers of the Kruger National Park, a management goal of maintaining biodiversity requires a clearer understanding of system variability. One component of this is water temperature, an important water quality parameter defining the distribution patterns of aquatic organisms. In this study, Chiloglanis anoterus Crass (1960) (Pisces: Mochokidae) was selected as a biological indicator of changes in annual water temperatures within the Sabie River in the southern Kruger National Park. Relative abundances of C. anoterus were determined using standard electro-fishing surveys. The presence or absence of C. anoterus was linked to cumulative annual heat units using a logistic regression model, and a critical annual cumulative water temperature threshold estimated. A correlative relationship between this temperature threshold and a biological index using a C. anoterus condition factor provides river ecologists with a tool to assess ecologically significant warming trends in Sabie River water temperatures. A similar approach could be applied with relative ease to other Southern African river systems. Further testing of this hypothesis is suggested, as part of the adaptive management cycle.
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Date Issued: 2005

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In-kernel cryptographic executable verification

- Motara, Yusuf, M, Irwin, Barry V W

Authors: Motara, Yusuf, M , Irwin, Barry V W
Date: 2005
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/429049 , vital:72556 , https://doi.org/10.1007/0-387-31163-7_25
Description: This paper discusses the problems posed by Trojan horses and unauthorized code, and reviews existing solutions for dealing with them. A technique involving the in-kernel verification of executables is proposed. Its advantages include simplicity, transparency, ease of use and minimal setup time. In addition, the technique has several applications, including assisting with honeypot implementations, incident response and forensic investigations.
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Date Issued: 2005

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In-kernel cryptographic executable verification

- Motara, Yusuf, M, Irwin, Barry V W

Authors: Motara, Yusuf, M , Irwin, Barry V W
Date: 2005
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/429937 , vital:72653 , https://doi.org/10.1007/0-387-31163-7_25
Description: This paper discusses the problems posed by Trojan horses and unau-thorized code, and reviews existing solutions for dealing with them. A technique involving the in-kernel verification of executables is pro-posed. Its advantages include simplicity, transparency, ease of use and minimal setup time. In addition, the technique has several applications, including assisting with honeypot implementations, incident response and forensic investigations.
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Date Issued: 2005

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Phylogenetic congruence of mealybugs and their primary endosymbionts

- Downie, Douglas A, Gullan, P J

Authors: Downie, Douglas A , Gullan, P J
Date: 2005
Language: English
Type: Article
Identifier: vital:6905 , http://hdl.handle.net/10962/d1011858 , http://dx.doi.org/10.1111/j.1420-9101.2004.00834.x
Description: Tight interactions between unrelated organisms such as is seen in plant–insect, host–parasite, or host–symbiont associations may lead to speciation of the smaller partners when their hosts speciate. Totally congruent phylogenies of interacting taxa have not been observed often but a number of studies have provided evidence that various hemipteran insect taxa and their primary bacterial endosymbionts share phylogenetic histories. Like other hemipterans, mealybugs (Pseudococcidae) harbour multiple intracellular bacterial symbionts, which are thought to be strictly vertically inherited, implying codivergence of hosts and symbionts. Here, robust estimates of phylogeny were generated from four fragments of three nuclear genes for mealybugs of the subfamily Pseudococcinae, and a substantial fragment of the 16S–23S rDNA of their P-endosymbionts. Phylogenetic congruence was highly significant, with 75% of nodes on the two trees identical, and significant correlation of branch lengths indicated coincident timing of cladogenesis. It is suggested that the low level of observed incongruence was influenced by uncertainty in phylogenetic estimation, but evolutionary outcomes other than congruence, including host shifts, could not be rejected.
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Date Issued: 2005

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Post-traumatic stress disorder as a public health concern in South Africa

- Edwards, David J A

Authors: Edwards, David J A
Date: 2005
Language: English
Type: Article
Identifier: vital:6229 , http://hdl.handle.net/10962/d1007779
Description: This article briefly surveys the extent to which traumatic events are a feature of life all over Africa and provides a comprehensive review of research that documents the pervasiveness of traumatic events in South Africa and the prevalence of PTSD symptoms. The material reviewed includes statistics on crime, violence and accidents, research from clinical settings, and surveys. Several provide evidence for the causal link between traumatic events and the development of PTSD. These studies show that PTSD has been and continues to be a significant problem for public health in South Africa, affecting individuals in all sectors of society and as much a concern with respect to children as to adults.
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Date Issued: 2005

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