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Photochemical studies of binuclear phenoxysubstituted phthalocyanines containing catecholate bridges

- Seotsanyana-Mokhosi, Itumeleng, Maree, Suzanne, Maree, M David, Nyokong, Tebello

Authors: Seotsanyana-Mokhosi, Itumeleng , Maree, Suzanne , Maree, M David , Nyokong, Tebello
Date: 2003
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/304808 , vital:58492 , xlink:href="https://doi.org/10.1142/S1088424603000239"
Description: Binuclear ZnPc complexes covalently bridged by catechol units have been synthesized and their absorption and photochemical properties examined. The complexes studied are 1,2-bis-2',9',16',23'-triphenoxyphthalocyaninatozinc benzene (6a), 1,2-bis-2'-9',16',23'-tri-4-carboxyphe-noxyphthalocyaninatozinc benzene (6b), 1,2-bis-2',9',16',23'-tri-4-nitrophenoxyphthalocyaninato- zinc benzene (6c) and 1,2-bis-2'-9',16',23'-tri-4-tert-butylphenoxyphthalocyaninatozinc benzene (6d). Larger intramolecular coupling was observed for 6b and 6c, containing the carboxyphenoxy and nitrophenoxy substituents, respectively, than for 6a and 6d. A single Q band peak was observed for the fluorescence spectra of 6b and 6c, whereas, 6a and 6d showed a split Q band. The absence of the high energy fluorescence peaks corresponding to absorbance peaks in the 640 nm region, suggests that the intramolecular coupling is broken by excitation for complexes 6b and 6c.
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Date Issued: 2003

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Phthalocyanines and related complexes as electrocatalysts for the detection of nitric oxide

- Nyokong, Tebello, Vilakazi, Sibulelo

Authors: Nyokong, Tebello , Vilakazi, Sibulelo
Date: 2003
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/290346 , vital:56741 , xlink:href="https://doi.org/10.1016/S0039-9140(03)00356-4"
Description: Metallophthalocyanine (MPc) and metalloporphyrin complexes as well as some metalloproteins including myoglobin, hemoglobin, cyanocobalamin and cytochrome c catalyse the detection of nitric oxide (NO). The catalytic process often involve changes in the oxidation state of the catalyst. These complexes catalyse both the reduction and oxidation of NO. MPc complexes containing electroactive central metals such as CoPc and FePc generally show better catalytic activity towards the detection of NO than complexes containing electroinacive central metals. However, the involvement of ring based redox processes was confirmed for the homogenous NO catalysis using CoPc.
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Date Issued: 2003

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Phylogenetics of advanced snakes (Caenophidia) based on four mitochondrial genes

- Kelly, Christopher M R, Barker, Nigel P, Villet, Martin H

Authors: Kelly, Christopher M R , Barker, Nigel P , Villet, Martin H
Date: 2003
Language: English
Type: Article
Identifier: vital:6960 , http://hdl.handle.net/10962/d1012005
Description: Phylogenetic relationships among advanced snakes ( Acrochordus + Colubroidea = Caenophidia) and the position of the genus Acrochordus relative to colubroid taxa are contentious. These concerns were investigated by phylogenetic analysis of fragments from four mitochondrial genes representing 62 caenophidian genera and 5 noncaenophidian taxa. Four methods of phylogeny reconstruction were applied: matrix representation with parsimony (MRP) supertree consensus, maximum parsimony, maximum likelihood, and Bayesian analysis. Because of incomplete sampling, extensive missing data were inherent in this study. Analyses of individual genes retrieved roughly the same clades, but branching order varied greatly between gene trees, and nodal support was poor. Trees generated from combined data sets using maximum parsimony, maximum likelihood, and Bayesian analysis had medium to low nodal support but were largely congruent with each other and with MRP supertrees. Conclusions about caenophidian relationships were based on these combined analyses. The Xenoderminae, Viperidae, Pareatinae, Psammophiinae, Pseudoxyrophiinae, Homalopsinae, Natricinae, Xenodontinae, and Colubrinae (redefined) emerged as monophyletic, whereas Lamprophiinae, Atractaspididae, and Elapidae were not in one or more topologies. A clade comprising Acrochordus and Xenoderminae branched closest to the root, and when Acrochordus was assessed in relation to a colubroid subsample and all five noncaenophidians, it remained associated with the Colubroidea. Thus, Acrochordus + Xenoderminae appears to be the sister group to the Colubroidea, and Xenoderminae should be excluded from Colubroidea. Within Colubroidea, Viperidae was the most basal clade. Other relationships appearing in all final topologies were (1) a clade comprising Psammophiinae, Lamprophiinae, Atractaspididae, Pseudoxyrophiinae, and Elapidae, within which the latter four taxa formed a subclade, and (2) a clade comprising Colubrinae, Natricinae, and Xenodontinae, within which the latter two taxa formed a subclade. Pareatinae and Homalopsinae were the most unstable clades.
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Date Issued: 2003

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Physiological, perceptual and performance responses during cricket activity

- King, Gregory Allen

Authors: King, Gregory Allen
Date: 2003
Subjects: Cricket , Sports -- Psychological aspects , Sports -- Physiological aspects
Language: English
Type: Thesis , Masters , MSc
Identifier: vital:5131 , http://hdl.handle.net/10962/d1005210 , Cricket , Sports -- Psychological aspects , Sports -- Physiological aspects
Description: The present study sought to determine the influence of environmental conditions and protective clothing on physiological, perceptual and performance responses during batting activity. The investigation examined mean skin temperature, average heart rate, estimated sweat rate, rating of perceived exertion, thermal sensation rating, average sprint time and pre-post choice reaction time. Twenty-five cricketers (18-22 yr, 73.1 ± 9.6 kg, 1768 ± 75 mm, 12.6 ± 3.1% body fat, 1.89 ± 0.16 m2) performed a work-bout consisting of a seven-Over batting period, during which time they faced deliveries from a bowling machine and performed two shuttle runs every third ball to total four sprints per Over. Trials were carried out under High-stress (23.8 ± 2.2 °C) and Low-stress (13.3 ± 1.9 °C) environmental conditions (WBGT). Within each environmental condition subjects performed the test wearing full protective batting gear and no protective gear. Thus, four specific conditions were examined; high full-gear (HFG), high no-gear (HNG), low full-gear (LFG) and low no-gear (LNG). Two-way ANOVAs were calculated to determine whether there were differences between environmental conditions and whether differences existed between the clothing conditions. One-way ANOVAs were utilised to compute differences between the four specific conditions combining clothing and environment. High environmental stress and wearing protective clothing caused batsmen to experience significant physiological strain. The environment was the greatest stressor, with the protective gear exacerbating these effects. However, when padding covered skin areas directly, this was the primary skin temperature stressor, particularly later in the activity. For skin temperature and heart rate, the strain was the most pronounced at the end of the trials. Perceptual responses indicated that the protective gear had no influence on effort sense, thermal sensation or thermal comfort. However, environmental conditions had an effect, and High-stress conditions resulted in significantly higher perceptions of effort, elevated sensations of heat and greater thermal discomfort. Effort was perceived to be greatest towards the end of the trial. There were mixed findings for performance factors. In general sprint performance was not hindered by environmental stress, but protective clothing caused a reduction in several sprint times. Choice reaction times were for the most part unaffected by either environment or clothing and few differences were observed between pre and post times. It is contended that intense short duration batting activity, likely encountered during one-day participation, imposes a stress on batsmen. The stress is greater when conditions are warmer and protective padding is worn, although it is not sufficient to impede choice reaction time. However, protective gear did have a deleterious effect on sprint performance.
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Date Issued: 2003

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poetry hotel

- Berold, Robert

Authors: Berold, Robert
Date: 2003
Subjects: To be catalogued
Language: English
Type: text , poem
Identifier: http://hdl.handle.net/10962/462321 , vital:76292 , ISBN 0028-4459 , https://journals.co.za/doi/epdf/10.10520/AJA00284459_602
Description: New Coin is one of South Africa's most established and influential poetry journals. It publishes poetry, and poetry-related reviews, commentary and interviews. New Coin places a particular emphasis on evolving forms and experimental use of the English language in poetry in the South African context. In this sense it has traced the most exciting trends and currents in contemporary poetry in South Africa for a decade of more. The journal is published twice a year in June and December by the Institute for the Study of English in Africa (ISEA), Rhodes University.
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Date Issued: 2003

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Politics of asylum : sovereign considerations in the multilateral and humanitarian practices of refugee protection in post-apartheid South Africa

- Oduba, Victor

Authors: Oduba, Victor
Date: 2003
Subjects: Refugees -- Africa , Refugees -- Government policy -- South Africa , Refugees -- Legal status, laws, etc. -- South Africa , Asylum, Right of -- South Africa
Language: English
Type: Thesis , Masters , MA
Identifier: vital:2870 , http://hdl.handle.net/10962/d1007725 , Refugees -- Africa , Refugees -- Government policy -- South Africa , Refugees -- Legal status, laws, etc. -- South Africa , Asylum, Right of -- South Africa
Description: Most scholars claim that international human rights norms embodied in formal international declarations and treaties have an important impact on domestic political interests and governmental practices. This reasoning about the impact of global human rights is often applied to the post-apartheid South African immigration and refugee policies. While I acknowledge that the ratification of United Nations Conventions on refugees has altered the traditional sovereignty considerations of South Africa towards asylum seekers, I take issue with the claims that South African refugee and asylum policies are primarily motivated and based on humanitarian considerations. Instead, I argue that these policies are based on sovereign considerations and strategic foreign policy interests. As a result this sovereign interests of South Africa to study has sought to demonstrate that largely explain decisions on the part accept or reject refugees. Although norms diffusion, international advocacy networks, and prestige factors have made a big impact, in practice the refugee policy has continued to reflect South Africa's strategic interests and domestic considerations at all levels. However, I have not argued that South Africa should overlook its national and foreign interests and abide by international human rights norms regardless of the cost of doing so. I have only sought to demonstrate that refugee protection is more when powerful national interests find it conducive to manage the destabilizing refugee flows.
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Date Issued: 2003

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Pollination success in a deceptive orchid is enhanced by co-occurring rewarding magnet plants

- Johnson, Steven D, Peter, Craig I, Nilsson, L Anders, Agren, Jon

Authors: Johnson, Steven D , Peter, Craig I , Nilsson, L Anders , Agren, Jon
Date: 2003
Language: English
Type: Article
Identifier: vital:6520 , http://hdl.handle.net/10962/d1005949 , http://www.jstor.org/stable/3449962
Description: It has been debated whether pollination success in nonrewarding plants that flower in association with nectar-producing plants will be diminished by competition for pollinator visits or, alternatively, enhanced through increased local abundance of pollinators (the magnet species effect). We experimentally evaluated these effects using the nonrewarding bumblebee-pollinated orchid Anacamptis morio and associated nectar-producing plants at a site in Sweden. Pollination success (estimated as pollen receipt and pollen removal) in A. morio was significantly greater for individuals translocated to patches of nectar-producing plants (Geum rivale and Allium schoenoprasum) than for individuals placed outside (similar to20 m away) such patches. These results provide support for the existence of a facilitative magnet species effect in the interaction between certain nectar plants and A. morio. To determine the spatial scale of these interactions, we correlated the visitation rate to flowers of A. morio with the density of sympatric nectar plants in 1-m(2) and 100-m(2) plots centered around groups of translocated plants, and at the level of whole meadows (similar to0.5-2 ha). Visitation rate to flowers of A. morio was not correlated with the 1-m(2) patch density of G. rivale and A. schoenoprasum, but showed a significant positive relationship with density of these nectar plants in 100-m(2) plots. In addition, visitation to flowers of A. morio was strongly and positively related to the density of A. schoenoprasum at the level of the meadow. Choice experiments showed that bees foraging on the purple flowers of A. schoenoprasum (a particularly effective magnet species) visit the purple flowers of A. morio more readily (47.6% of choices) than bees foraging on the yellow flowers of Lotus corniculatus (17% of choices). Overall similarity in flower color and shape may increase the probability that a pollinator will temporarily shift from a nectar-producing "magnet" plant to a nonrewarding plant. We discuss the possibility of a mimicry continuum between those orchids that exploit instinctive food-seeking behavior of pollinators and those that show an adaptive resemblance to nectar-producing plants.
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Date Issued: 2003

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Population biology of Octopus vulgaris on the temperate south-eastern coast of South Africa

- Oosthuizen, A, Smale, Malcolm J

Authors: Oosthuizen, A , Smale, Malcolm J
Date: 2003
Language: English
Type: Article
Identifier: vital:6768 , http://hdl.handle.net/10962/d1008045
Description: Population structure and biology of Octopus vulgaris was investigated along the south-eastern coast of South Africa. Samples were collected inter- and sub-tidally as a precursor to the establishment of an experimental octopus fishery in the region. In total, 300 (intertidal) and 147 (subtidal) O. vulgaris were collected over a two year period. Females were found to dominate the intertidal area (sex ratio 2:1), while no difference was found subtidally (sex ratio 1:1). Of those collected intertidally, immature females were most prevalent while males ranged from immature to mature. Mature females were only found subtidally. A marked size difference was apparent, with the subtidal octopus being substantially larger. Although brooding females were found throughout the year, numbers peaked in summer. Individual fecundity ranged between 42,000–790,000 eggs. The total number of eggs produced and the number of eggs per egg string were correlated to female size. Diet did not vary greatly between the inter- and sub-tidal areas, with the main prey items being crustaceans, teleosts and octopus. It appears that the immature females use the intertidal area to feed and grow, before migrating to deeper areas to mature and spawn.
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Date Issued: 2003

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Potter's fingerprints: some prehistoric southern African utilityware in an intimate light.

- Steele, John

Authors: Steele, John
Date: 2003
Language: English
Type: text , Article
Identifier: http://hdl.handle.net/11260/945 , vital:30070
Description: Extensive archaeological excavations in southern Africa during the past century have revealed a richly described heritage of widely distributed First-Millennium (C.E.) Agriculturist ceramics. In viewing both artefacts and assessments thereof it can be observed that ways of thinking shape ways of seeing, and explanations ofwhat is seen. Thus, because conceptual frameworks are inseparable from what is observed and explanations that result, consideration is given to some particular mindsets that have led to recent theories concenring local prehistoric material culture. In conclusion, a brief look at dialogues initiated by some contemporary potters who interrogate cherished lifeways and belief systems serve to elucidate current trends towards finding meaning in prehistoric southern African ceramics.
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Date Issued: 2003

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Predictive modelling of species' potential geographical distributions

- Robertson, Mark Peter

Authors: Robertson, Mark Peter
Date: 2003
Subjects: Alien plants -- South Africa -- Geographical distribution Species -- Geographical distribution -- Mathematical models Cicadas -- South Africa -- Geographical distribution Scaevola plumieri -- South Africa -- Geographical distribution
Language: English
Type: Thesis , Doctoral , PhD
Identifier: vital:5816 , http://hdl.handle.net/10962/d1007189
Description: Models that are used for predicting species' potential distributions are important tools that have found applications in a number of areas of applied ecology. The majority of these models can be classified as correlative, as they rely on strong, often indirect, links between species distribution records and environmental predictor variables to make predictions. Correlative models are an alternative to more complex mechanistic models that attempt to simulate the mechanisms considered to underlie the observed correlations with environmental attributes. This study explores the influence of the type and quality of the data used to calibrate correlative models. In terms of data type, the most popular techniques in use are group discrimination techniques, those that use both presence and absence locality data to make predictions. However, for many organisms absence data are either not available or are considered to be unreliable. As the available range of profile techniques (those using presence only data) appeared to be limited, new profile techniques were investigated and evaluated. A new profile modelling technique based on fuzzy classification (the Fuzzy Envelope Model) was developed and implemented. A second profile technique based on Principal Components Analysis was implemented and evaluated. Based on quantitative model evaluation tests, both of these techniques performed well and show considerable promise. In terms of data quality, the effects on model performance of false absence records, the number of locality records (sample size) and the proportion of localities representing species presence (prevalence) in samples were investigated for logistic regression distribution models. Sample size and prevalence both had a significant effect on model performance. False absence records had a significant influence on model performance, which was affected by sample size. A quantitative comparison of the performance of selected profile models and group discrimination modelling techniques suggests that different techniques may be more successful for predicting distributions for particular species or types of organism than others. The results also suggest that several different model design! sample size combinations are capable of making predictions that will on average not differ significantly in performance for a particular species. A further quantitative comparison among modelling techniques suggests that correlative techniques can perform as well as simple mechanistic techniques for predicting potential distributions.
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Date Issued: 2003

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Procedural fairness in unprotected strike dismissals

- Nel, Werner

Authors: Nel, Werner
Date: 2003
Subjects: Strikes and lockouts -- Law and legislation -- South Africa , Labor laws and legislation -- South Africa , Employees -- Dismissal of -- Law and legislation -- South Africa , South Africa. Labour Relations Act -- 1995
Language: English
Type: Thesis , Masters , LLM
Identifier: vital:11049 , http://hdl.handle.net/10948/314 , Strikes and lockouts -- Law and legislation -- South Africa , Labor laws and legislation -- South Africa , Employees -- Dismissal of -- Law and legislation -- South Africa , South Africa. Labour Relations Act -- 1995
Description: The Labour Relations Act contains a definition of a strike which reads as follows: “’strike’ means the partial or complete concerted refusal to work, or the retardation or obstruction of work, by persons who are or have been employed by the same employer or by different employers, for the purpose of remedying a grievance or resolving a dispute in respect of any matter of mutual interest between employer and employee, and every reference to ‘work’ in this definition includes overtime work, whether it is voluntary or compulsory.” The Labour Relations Act offers strikers special protection against dismissal if they conform with the Act and its provisions. Hence the distinction between those strikes and protest action in compliance with the Act, namely ‘protected’ strikes and protest action, and those strikes and protest action in violation of the Act, namely, ‘unprotected’ strikes and protest action. Participation in an unprotected strike is one form of misbehaviour. The Labour Relations Act expressly prohibits the dismissal of employees engaged in a lawful strike. Employees engaged in strike action contrary to the provisions of the Labour Relations Act may be dismissed since their strike action is deemed to be a form of misconduct. The dismissal of striking employees must be both substantially and procedurally fair.
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Date Issued: 2003

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Productivity and abundance of Sclerocarya birrea subsp. caffra in and around rural settlements and protected areas of the Bushbuckridge lowveld, South Africa

- Shackleton, Charlie M, Botha, Jenny, Emanuel, P L

Authors: Shackleton, Charlie M , Botha, Jenny , Emanuel, P L
Date: 2003
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/181607 , vital:43751 , xlink:href="https://doi.org/10.1080/14728028.2003.9752459"
Description: Sclerocarya birrea (A. Rich.) Hochst, subsp. caffra (Sond.) Kokwaro is a common species throughout the semi-arid savannas of southern Africa, and is sought after by rural communities. It is frequently maintained in homesteads and fields in an agroforestry situation. It has also been identified by a number of international and national institutes as a key species for domestication and commercialisation. Yet, the sustainability of the resource and local user knowledge and practices have not been considered. This study reports on the abundance and productivity of S. birrea in four rural villages and neighbouring protected areas in the Bushbuckridge lowveld of the Limpopo Province, South Africa, where its common name is marula. The density of marula stems was measured in homestead plots, arable fields and the surrounding communal rangelands of each village. Fruit production was assessed by regular counting of fruit fall from marked trees of known size. Within the villages, fruit production was monitored via local community groups. Additional monitoring of fruiting was conducted on marked trees within local protected areas. The proportion of households planting or nurturing marula trees was determined through interviews with a stratified random sample of households. The density of marula trees was significantly higher in protected areas than the neighbouring communal lands, fields or homesteads. However, the majority of trees in protected areas were small, while those in homesteads were large and mature. Density of adult fruit-bearing female trees, was similar between the protected areas and homesteads, but less in fields and communal lands. S. birrea trees were maintained in 79 % of homesteads and 58 % of fields. Mean fruit yield per tree was significantly higher from village trees (less than 17 000 fruits) than protected area trees (more than 3 500 fruits), even after accounting for differences in tree size. The fresh mass of individual fruits was also greater on village trees than on trees in protected areas. Both these characteristics suggest some degree of historical selection of the trees in the homesteads and fields. There was a positive relationship between tree size and number of fruits produced.
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Date Issued: 2003

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Progress towards the development and implementation of an unambiguous copper wire fingerprinting system

- Poole, Martin

Authors: Poole, Martin
Date: 2003
Subjects: Electroplating , Copper , Telecommunication , Theft -- Prevention
Language: English
Type: Thesis , Masters , MSc
Identifier: vital:5484 , http://hdl.handle.net/10962/d1005270 , Electroplating , Copper , Telecommunication , Theft -- Prevention
Description: The Telecommunications industry in Southern Africa is faced with the problem of theft of the signal carrying copper wire, both from the ground and from telephone poles. In many cases, if the offenders are caught, the prosecuting party has no way of proving that the wire is the property of any one Telecommunication company, as any inked markings on the insulating sheaths have been burned off along with the insulation and protective coatings themselves. Through this work we * describe the problem, * specify the necessary and preferred technical properties of a viable solution, * report the preliminary investigations into the devising of an unambiguous "fingerprinting" of the 0.5 mm wires, including some of those solutions that, upon investigation, appear non-viable, * describe the development and implementation of an electrochemical marker with detection mechanism which has shown in proof-of-principle to work, * outline the road-map of necessary future work.
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Date Issued: 2003

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Provocation as a defence in English and South African criminal law

- Krause, Samantha

Authors: Krause, Samantha
Date: 2003
Subjects: Provocation (Criminal law) -- South Africa , Provocation (Criminal law) -- Great Britain
Language: English
Type: Thesis , Masters , LLM
Identifier: vital:11044 , http://hdl.handle.net/10948/310 , Provocation (Criminal law) -- South Africa , Provocation (Criminal law) -- Great Britain
Description: In the past 20 years the defence of provocation has shifted from the periphery of South African law to a fully developed defence available to those who kill when provoked. Not only is the defence available to the provoked, but it has been extended to those who kill when subjected to emotional stress. However, the defence is mirred in controversy and bad decisions. Not only has the precise nature of the defence not been clarified, but this lack of clarity has been exacerbated by confusing decisions of our courts. This confusion is partly a result of the development of the defence of incapacity, particularly its extension to cases involving provocation and mental stress, and partly a result of its application in practice. Three major problems have plagued the provocation defence. Firstly, the courts have confused the defence of sane automatism with that of non-pathological incapacity. Secondly, there has been an implied use of an objective test in determining criminal incapacity where the enquiry has clearly been a subjective one. Thirdly, it has been held that the problem may not so much be the subjective aspect of provocation, but rather its application. The real problem seems to lie in the theoretical confusion as to the precise meaning of lack of “selfcontrol”. Lastly, on occasion the courts have failed to distinguish lack of capacity from diminished responsibility. Thus, in order to gain clarity concerning this “grey” area of the law these problems have created, it is necessary for South African law to consult more authoritative sources to receive guidance for the problems identified. One of those sources that has been consulted is that of English law. English law, however, deals with the defence of provocation in a different manner. Raising a defence of provocation here does not result in an acquittal but rather in a reduction of the charge to manslaughter. However, the English law on provocation is also 7 plagued by various problems. Firstly, there is the issue of cumulative provocation. Generally, there is little difficulty in cases where there is no “immediate trigger”. Secondly, the fundamental flaw with the current test of the reasonable man is that the courts have had to swing between the two aims of taking a compassionate view of human frailty while endeavoring to maintain an objective standard of the reasonable man. Lastly, it can be said that the problem with the proportionality requirement is that it makes the provocation defence dependant upon the assessment of the accused’s conduct after he or she lost his or her selfcontrol rather than on his or her giving way to passion and losing control in the first place. It is clear that from the problems identified in both South African law and English law concerning the defence of provocation the courts in each jurisdiction will have to pay careful attentio n to the problems highlighted and apply the law in such a way so as to ensure clarity and legal certainty.
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Date Issued: 2003

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