Academy of Science of South Africa (ASSAf): Open Journal Systems
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Arthropod associates of Kenyan buffelgrass (Cenchrus ciliaris): a field survey for biological control candidates of a globally important invasive grass
No full textInvasive species are the second largest contributor to biodiversity loss and drivers of ecosystem change. Buffelgrass is a C4, perennial grass native to Africa and Asia that was widely introduced across tropical and subtropical rangelands as livestock forage. Buffelgrass reduces native biodiversity and ecosystem stability in its introduced range when it escapes livestock pastures. Understanding the ecology of insects associated with buffelgrass in its native range may provide an understanding of invasion processes and biological control opportunities where buffelgrass has become an invasive challenge. Here, we present the results of a six-year survey of herbivorous arthropods of a native buffelgrass population from Kenya. Buffelgrass was examined for externally and internally feeding insects of vegetative and reproductive tissues. We also categorised buffelgrass detritivores and parasitoids that may use buffelgrass herbivores as hosts. The samples were photographed and Sanger sequenced to identify them to the lowest possible taxonomic ranking. We collected information on sample abundances, phenologies, tissues consumed, and putative diet breadths. We identified 25 morphospecies representing seven orders and 16 families. The putative host plant specialisation was as high as 67% for Diptera. Phenological variation in herbivore presence correlated with seasonal rainfall and provided a guide for when to conduct follow-up biological control agent searches. The most abundant herbivore was a gall midge (Diptera: Cecidomyiidae) that inhabits buffelgrass culms. Additional research should focus on bringing this species into containment where host choice trials can be conducted to determine if it is truly monophagous and assess its impact on buffelgrass growth
Foundational African Writers: Peter Abrahams, Noni Jabavu, Sibusiso Nyembezi & Es’kia Mphahlele (Bhekizizwe Peterson, Khwezi Mkhize & Makhosazana Xaba, reds.)
No full textFuture climate change in the Agulhas system and its associated impact on South African rainfall
No full textSouth African climate variability has been linked to changes in both the Agulhas system and external forcing (i.e. CO2 and ozone). We analysed future climate change in the Agulhas system volume transport and its associated impacts on South Africa’s precipitation using the Community Climate System Model version 4 as part of the Coupled Model Intercomparison Project, phase 5. Output from one historical and three future greenhouse gas emission scenarios were examined to project various climate storylines. We found that the Agulhas Current volume transport decreases across all three scenarios and that the current displays a strong baroclinic component with an increase in transport at the surface and decrease at intermediate depths. Agulhas leakage was found to increase with historical emissions. Additionally, an east-west dipole pattern for convective precipitation was found over South Africa, with an increase over the eastern region related to an increase in greenhouse gas emissions and a decrease in the western region linked to the location of Hadley cell edge latitude. Moving into the 21st century, future predictions in regional climate variability are shown to be dependent on the intensity of greenhouse gas emissions and are extremely important for South Africa, a region prone to drought and flooding and home to a large population dependent on rain-fed agriculture.
Significance:
Future climate variability in the Agulhas system and South African region is heavily dependent on changes in external forcing.
The Agulhas Current volume transport decreases as the greenhouse gas emissions continue to increase and a strong baroclinic component is found with an increase in transport at the surface and a decrease at the intermediate depths.
A strong east-west dipole precipitation pattern is found over South Africa with the increase in the eastern region related to the increase in greenhouse gas emissions and the decrease in the western region related to the location of the Hadley cell edge latitude
Cone beam computed tomography use in sialolithiasis of the submandibular salivary gland
Get PDFA 62-year-old diabetic male patient presented with right sided facial pain associated with a firm palpable mobile mass in the right submandibular area. Following initial examination, cone beam computed tomography (CBCT) investigation demonstrated multiple smooth homogenous calcifications (Figure 1) collectively measuring 12mm x 9mm x 8mm within the region of the right submandibular gland (Figure 2). On resection of the submandibular gland, the histological features of the lesion were confirmed to be those of chronic sclerosing sialadenitis supporting the clinical impression of a sialolith
TACIT CHOICE OF LAW IN INTERNATIONAL COMMERCIAL CONTRACTS: PROGRESS OR STAGNATION IN THE COMMON- LAW JURISDICTIONS?
No full textThe English common-law rules of private international law have, to a large extent, been replaced by European conflicts-law regulations in the United Kingdom (UK). Nevertheless, English common law remains highly influential in numerous jurisdictions. In many legal systems, the private-international-law rules are based fundamentally on the common-law rules developed by English courts. This is problematic since the common-law rules of private international law may be outdated. This article examines the English common-law choice-of-law rules – more specifically, the rules and principles concerning the determination of a tacit choice of law in international commercial contracts. The traditional common-law position is compared to selected common-law jurisdictions – namely, Australia, Canada, India, Israel and New Zealand. Finally, the article highlights the progress (or lack thereof) in the aforementioned common-law jurisdictions in addressing the issues related to the determination of a tacit choice of law in international commercial contracts
THE DOMESTIC VIOLENCE ACT 116 OF 1998: OFFENCES, DEFENCES, ECONOMIC ABUSE, IMMINENT HARM AND THE CRIME OF DOMESTIC ABUSE– WHAT IS NEW?
No full textRecent tragedies relating to gender-based violence have drawn attention to the current state of our relevant law. This article focuses on domestic violence – a species of gender-based violence. It assesses the current state of the Domestic Violence Act 116 of 1998; in particular, it focuses on the offences and defences, as well as on the definition of economic abuse and the concept of imminent harm in relation to domestic abuse. The proposals to amend the definition of these concepts have culminated in the passing of the Domestic Violence Amendment Act 14 of 2021. The bulk of the amendments have not commenced. Nevertheless, this article also comments on the impact that these amendments will have on the thesis of this article. It also sheds some light on the proposed stand-alone crime of domestic abuse
THE CONSTITUTIONAL RIGHT OF ACCESS TO SOCIAL SECURITY: PART II PROPOSED SOLUTIONS
No full textThis is the second of two articles dealing with the constitutional right to have access to social security in South Africa. Part I dealt with the general introduction to the topic and highlighted some concerns relating to the right to have access to social security in South Africa and the inclusion of this right in the Constitution. Part II contains a study of various proposed solutions to these problems with particular emphasis on attempts to assist those excluded from the formal framework of social security
CONVERGENCE OF TRADITIONAL CORPORATE GOVERNANCE AND MODERN CORPORATE GOVERNANCE REFORMS: IS KING II déja vu FOR BOARDS OF DIRECTORS OR IS IT A SET OF NEW PRINCIPLES?
No full textContrary to popular belief, corporate governance is not a new subject. In fact, corporate governance has been practised for as long as there have been corporate entities. Corporate governance has always been reflected in legislation such as the Companies Act, Insolvency Act, Insider Trading Act and similar legislation. However, some of the recent recommendations resulting from reforms in this area reflect the improvement of corporate governance standards. This article is an attempt to point out similarities and divergences between traditional corporate governance and modern corporate governance as suggested by the latest reforms, particularly in the King Report on corporate governance (2002)
GESLAGSOORDRAAGBARE SIEKTES EN DIE GESLAGSDAAD AS GEWELDSINSTRUMENT
No full textIn 'n beslissing van die Hoge Raad (HR) in Nederland van 24 Junie 2003 het die volgende feitestel navore getree: die beskuldigde het tussen die periode 1 Januarie 2001 tot 22 Februarie 2001 by verskeie geleenthede met die slagoffer/klaagster geslagsomgang gehad wetende dat hy met HIV besmet was en bewus daarvan was dat dit deur die geslagsdaad oordraagbaar is en uiteindelik tot die dood van die slagoffer sou kon lei. Hy het vroeër ook gedurende die periode van 1 Februarie 2000 tot 31 Mei 2000 onder dieselfde omstandighede met 'n ander vrou by meerdere geleenthede geslagsomgang gehad. Die HR moes in finale instansie beslis of dolus eventualis/kans-bewussyn teenwoordig was, met ander woorde: het die beskuldigde hom deur dié optrede aan poging tot doodslag skuldig gemaak? Die hof a quo, naamlik die Gerechtshof te 's-Gravenhage, het 'n positiewe bevinding in dié verband gemaak.In die onderhawige bydrae word die Nederlandse reg, teen die agtergrond van die beslissing van die HR in die saak, onder die loep geneem. Daarna word die Suid-Afrikaanse reg in dié verband aan die orde gestel en 'n kritiese evaluasie onderneem van die effek wat dié problematiek op toekomstige strafregtelike ontwikkelinge kan hê