Academy of Science of South Africa (ASSAf): Open Journal Systems
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Canola (Brassica napus L.) water use indicators as affected by sustained deficit irrigation and plant density in central Free State, South Africa
No full textIn South Africa canola (Brassica napus L.) is cultivated in rotation with wheat under winter rainfall in the Western Cape Province, primarily for seed to make oil. Expansion of the crop to the other 8 provinces is proposed to reduce shortages of locally produced plant oils. At the same time, canola can serve as a rotational crop for wheat in these summer rainfall provinces. In central Free State, information on evapotranspiration and various water use indicators for canola as influenced by sustained deficit irrigation and plant density is lacking. An experiment with a line source sprinkler irrigation system was therefore conducted, comprising of full irrigation as a control with 4 sustained deficit irrigation levels (mean reduction in irrigation depth per event of 67%, 52%, 34% and 19%) and 5 plant densities (25, 50, 75, 100 and 125 plants‧m−2). Mean seasonal maximum evapotranspiration amounted to 429 mm across plant densities. Plant density did not significantly influence seasonal evapotranspiration. Reducing the irrigation depth per event by more than 20% decreased seasonal evapotranspiration by a mean 3.5 mm per percentage increase in irrigation depth. A maximum biomass water productivity of 22 kg‧ha−1‧mm−1 was measured with full irrigation and a plant density of 75 plants‧m−2. Seed water productivity amounted to a high of 11 kg‧ha−1‧mm−1 with full irrigation and a plant density of 25 plants‧m−2. A percentage reduction in irrigation depth and increase in plant density above 25 plants‧m−2 will reduce seed water productivity by 0.071 and 0.033 kg‧ha−1‧mm−1, respectively. Sustained deficit irrigation increased water use efficiency by a mean 0.5% per percentage reduction in irrigation depth per event
Supernumerary teeth in a sample of South African dental patients
Full text linkSupernumerary teeth (SNT) are often associated with malocclusions. Data on SNT in the South African population are not well documented. To determine the prevalence, distribution of characteristics and any associated complications of SNT in a South African sample of dental patients. The study was retrospective, cross-sectional and descriptive. Method: Orthopantomographs of 12,005 dental patients were reviewed for the presence of SNT. The number, morphology, location, eruption status and orientation of SNT were assessed. Associated orthodontic problems were noted. The prevalence rate was 2.48%. No sexual dimorphism in the distribution of SNT was noted. Types of SNT tabulated were: supplementary, conical, tuberculate and odontoma. Maxilla demonstrated a higher predilection for SNT. Variation in the distribution of SNT in the anterior, premolar and molar regions in each jaw and across jaws was statistically significant. Relationship of eruption status to the morphology and orientation of SNT was of significance. Malocclusions noted were displacement and impaction of adjacent teeth. From an orthodontic perspective, presence of SNT may compromise tooth movement and space closure in patients. Additionally, as majority of SNT in this population were in the maxillary molar and mandibular premolar regions, caution is advised when planning the placement of orthodontic implants in these regions
INTERPRETING THE PROVISIONS OF THE CYBERCRIMES ACT 19 OF 2020 IN THE CONTEXT OF CIVIL PROCEDURE: A FUTURE JOURNEY
No full textIt is accepted nowadays that cyberspace is used extensively to commit cybercrimes and cybersecurity offences. Victims of cybercrime can use civil procedure to institute claims for damages. Civil procedure is a branch of law that allows victims of cyberspace crimes to institute claims for damages. This article examines the impact of the Cybercrimes Act 19 of 2020 (Cybercrimes Act) on South African civil procedure. It appears that a contravention of the Cybercrimes Act may result in financial problems for the plaintiff, which then enables the latter to institute a civil claim against the defendants. The authors determine whether contravening the provisions of the Cybercrimes Act gives rise to a cause of action that permits the plaintiff to institute civil proceedings for damages suffered. While the Cybercrimes Act is lauded for its provisions addressing cybercrime, room for improvement is identified. Lastly, the authors conduct a comparative analysis between the provisions of the Cybercrimes Act and the Budapest Convention
EXPLORING THE FEASIBILITY OF CRIMINALISING MATERNAL SUBSTANCE ABUSE IN SOUTH AFRICA
No full textWith alcohol abuse by pregnant women being a significant problem in South Africa, particularly in the rural areas of the Western Cape province, the country carries one of the world’s heaviest burdens of foetal alcohol syndrome (FAS). FAS is regarded as the most severe of the foetal alcohol spectrum disorders. A child affected by FAS may suffer various developmental delays, including behavioural problems, poor language and fine motor skills, overall poor academic performance, mental retardation, and an increased tendency towards aggression and violence. Despite the alarming extent of the problem, maternal substance abuse is not currently a criminal offence in South Africa. This article explores the feasibility of criminalising maternal substance abuse, either by way of an amendment to the Children’s Act 38 of 2005 or by introducing a new statutory offence. As South African children are already afforded protection against abuse and neglect in terms of the Children’s Act, the prosecution of mothers who abuse substances while pregnant and then give birth to children suffering FAS-related harm could potentially also occur within this ambit. This would require an extension to the definitions of abuse and neglect in the Children’s Act and would have no effect on the legal status of a foetus in South Africa. Yet one would face certain challenges associated with the principle of legality: in terms of the ius strictum requirement, for instance, courts are expected to apply a strict rather than a broad interpretation to the definition of a crime. Therefore, if it is not provided for clearly enough in the definition of abuse and neglect, courts may be hesitant to include maternal substance abuse in their understanding of these crimes. Moreover, a strict interpretation of the meaning of “child” in the Children’s Act would exclude a foetus. In addition, a foetus does not possess legal subjectivity under South African law, which means that it generally does not have any legal rights, nor can it be the victim of any crime. Alternatively, the legislature could opt for introducing a new statutory offence to address maternal substance abuse separately. In this regard, criminalising maternal substance abuse as a materially-defined crime would be the best route to follow. This would restrict prosecution to instances where maternal substance abuse does in fact result in FAS-like effects in the child upon birth. In determining the feasibility of criminalising maternal substance abuse in South Africa, the article also takes a comparative look at United States law in this regard, particularly the position in Alabama and South Carolina. Developments in these states do seem to bode well for a decision to criminalise maternal substance abuse in South Africa as well. As shown in Hicks v State of Alabama 2014 153 So.3d 53 and Whitner v State 328 S.C. 1, 492 S.E.2d 777 (1997), maternal substance abusers in the United States may be prosecuted for either a specific statutory offence or general child neglect. However, while the courts in those cases imposed imprisonment, South Africa’s already overcrowded prisons coupled with the predominantly socio-economic causes of maternal substance abuse in the local context would warrant alternative sentencing options. These include referral to a rehabilitation centre or diversion. In addition, the United States courts seem to have accepted the view that foetuses should be afforded the same protection as children. As this would stir up a hornet’s nest in terms of the abortion debate and the legal status of a foetus in South Africa, following the American example in this respect is not recommended. However, this challenge can be overcome by criminalising maternal substance abuse as suggested above, by providing for prosecution only where the affected child is born alive and presents with FAS-like symptoms
Quality of Climate Change Extension Services Provided to Smallholder Farmers in Raymond Mhlaba Local Municipality, Eastern Cape Province, South Africa
No full textThe study ascertained the quality of climate change extension service and its determinants for smallholder farmers in Raymond Mhlaba Local Municipality. The study utilised a cross-sectional survey of 100 households obtained through random sampling. Ordered logistic regression was used to analyse the data. Half of the respondents were female, mainly from Dyamala Village. Most respondents were between 50 and 59 years, married with a primary education level, with household sizes of between five and eight. Most of the respondents were unemployed, with the primary source of income being social grants and a monthly income of R2100-R3000. Most of the respondents knew about climate change, especially from other farmers. Respondents had access to extension advisory services, and 80% of them indicated that the extension services were helpful. However, most respondents indicated that the quality of climate change-related extension services was poor. Age, marital status, employment status, knowledge about climate change, and access to the extension were significant factors in the perceived quality of extension services provided. The study concludes that socioeconomic factors affected the perceived quality of extension service. The study recommends improving the accessibility and spread of extension services. There's also a need to enhance extension training to improve the quality of service delivery
Probabilistic vs deterministic forecasts – interpreting skill statistics for the benefit of users
No full textOwing to probabilistic uncertainties associated with seasonal forecasts, especially over areas such as southern Africa where forecast skill is limited, non-climatologists and users of such forecasts frequently prefer them to be presented or distributed in terms of the likelihood (expressed as a probability) of certain categories occurring or thresholds being exceeded. Probabilistic forecast verification is needed to verify such forecasts. Whilst the resulting verification statistics can provide clear insights into forecast attributes, they are often difficult to understand, which might hinder forecast uptake and use. This problem can be addressed by issuing forecasts with some understandable evidence of skill, with the purpose of reflecting how similar forecasts may have performed in the past. In this paper, we present a range of different probabilistic forecast verification scores, and determine if these statistics can be readily compared to more commonly known and understood ‘ordinary’ correlations between forecasts and their associated observations – assuming that ordinary correlations are more intuitively understood and informative to seasonal forecast users. Of the range of scores considered, the relative operating characteristics (ROC) was found to be the most intrinsically similar to correlation
An evaluation of three evapotranspiration models to determine water fluxes over hillslopes encroached by invasive alien plants in Eastern Cape Province, South Africa
No full textEcosystem services in the South African grassland biome are being impacted by the presence of invasive alien plants (IAPs), particularly from the Australian genus Acacia. IAPs have elevated landscape water use and determining water fluxes is crucial to defining suitable interventions. This study evaluates three models of water flux over IAP-invaded grassland against evapotranspiration (ET) measured by a large-aperture scintillometer (LAS). ET was modelled using an energy balance model (MEDRUSH), a biophysical model (Penman-Monteith-Leuning (PML)) and a remotely sensed product (MOD16), and their results compared with ET measured by the LAS. ETLAS was measured during an abbreviated field campaign in November 2019 over a dense silver wattle (A. dealbata) stand associated with hillslope seeps. Of the three models tested against the LAS campaign, MEDRUSH performed well-enough to be used to model ET over the continuous scientific-grade micro-meteorological record (315 days). We used MEDRUSH to model ET over the invaded hillslope seeps and compared this with the expected ET that would occur over the adjacent, un-invaded grassland. Total ET over the IAP-invaded area was approximately 536 mm (60% of reference ET) as compared with the grassland (202 mm), showing that woody encroachment significantly increases landscape water use. To estimate the local impact of this, we used earth observation to determine the area of woody invasion in a 2 664 km2 regional window. Approximately 10% (274 km2) of this window was invaded by IAPs and, assuming the geographic window was representative of all the areas invaded by wattle, this represents ~ 89 000 ML of water used annually by the IAPs. Removal of wattle, followed by suitable restoration of landscape functionality, would greatly enhance rangeland productivity and water production from hillslope seeps
Relationships between reference site quality and baetid mayfly assemblages in mountainous streams of the Luvuvhu catchment, South Africa
No full textWith water quality deteriorating rapidly at a global scale, river sections suited to serve as reference sites are being increasingly lost. It thus becomes critical to develop rapid methods to confirm that previously monitored sites continue meet the requirements of reliable reference sites. In the absence of pristine sites, 9 near-natural sites, as defined by the Kleynhans (1996) classification, were used as reference sites for the Luvuvhu River catchment to compare the quality of physico-chemical factors against a biological metric. Baetid mayfly community structure at a site was chosen as an index of water quality, since this family is common in all types of freshwaters, highly diverse and adapted to unpolluted running water. Baetid larvae were sampled monthly from stones-in-current biotopes across 9 sites for over 1 year, between December 2016 and January 2018. A Spearman’s correlation test was used to evaluate the relationship between physico-chemical factors and identify redundant variables. Water quality standards were measured against the national water quality guidelines for aquatic ecosystems. We used a generalized linear model to determine the effect of physico-chemical variables on baetid species, and canonical correspondence analysis to show the relationships between baetid species, sites, and physico-chemical variables. A total of 3 039 individuals belonging to 12 mayfly species were recorded. Our findings indicated that while the physico-chemical factors were highly variable, they were within favourable ranges to reflect reference site conditions. While water temperature was the most important driver of baetid community structure in general, as it negatively affected their abundances, a subset of species (Pseudoponnota sp., Pseudocloeon sp., Acanthiops varius and Demoulinia crassi) showed clear responses to changes in TDS and stream width. We conclude that specific baetid species show good potential as biological indicators of reference sites and chronic water temperature stress, making assessment of reference sites easier
A STEP FORWARD IN THE FIGHT AGAINST ABLEISM: Damons v City of Cape Town [2022] ZACC 13
No full textIn Damons v City of Cape Town ([2022] ZACC 13) (CC judgment), the Constitutional Court (CC) had to deal with the issue of a person living with a disability who was injured in training. The minority judgment by Pillay AJ takes a socio-legal approach to the issue as it dives deep into how Mr Damons was injured and the responsibility of the employer to ensure that Mr Damons was reasonably accommodated. On the other hand, the decision of the majority by Majiedt J takes a formal legal approach in that it critiques the minority judgment from the perspective of the pleadings. This case note engages in a deep discussion of the matter, spanning the arbitration, Labour Court (LC), Labour Appeal Court (LAC) and both of the judgments of the CC. This case note engages in a discussion of the two judgments of the CC