Sabinet | Volume 38 Number 1
Volume 38 Number 1, 2019
Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie - Volume 38 Number 1, 2019
Karakterisering van Grubbs-tipe-prekatalisatore met behulp van kernmagnetieseresonansiespektrometrie
Authors: Frans Thomas Ignatius Marx, Daniel Petrus Otto, Christo de Lange, Johannes Hendrik Lodewikus Jordaan and Hermanus Cornelius Moolman Vosloo
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 38, pp 1 –13 (2019)
A model by which to estimate the volume of Nile crocodile eggs after they have hatched
Authors: Johan O. Nöthling, Johan A. Nöthling and Jan G. Myburgh
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 38, pp 1 –12 (2019)
The value of their leather stimulates commercial farming with several crocodilian species. The survival and growth of crocodile hatchlings depends on their birth mass. There exists a positive relationship between the hatchling mass and egg size of several crocodilian species. The size of crocodilian eggs is often not measured before hatching. The aim of this study was to create a model whereby the volume of individual Nile crocodile eggs can be estimated after they have hatched and the shell been broken, so that the relationship between egg volume and hatchling mass can be studied on an individual basis without the size of the eggs having been measured prior to hatching.
Infertile eggs were photographed in side view, with one pole towards the bottom and the other towards the top and a scale in the focal plane. Their volumes were measured by water displacement (displacement volume). A custom-written computer program was used to measure the photo images. The program turned the image of the egg upright and the position of the polar axis was determined without considering the position of the upper pole. Various transverse diameters (perpendicular to the polar axis) were measured, and the volume of the egg calculated by integrating the function describing the horizon of the egg on the polar axis (calculated volume). The best models for estimating the calculated volume were determined by using information limited to various distances from the bottom pole of the egg’s image towards its upper pole, and for eggs of different polarity. The models were then used to estimate the volumes of 138 eggs of which 15%, 20%, 25% and 30% of the image of each egg were masked from the upper pole towards the bottom pole.
Volumes of 60–135 ml derived from analysis of the masked photographic images of eggs permitted estimation of the eggs’ volumes to within 4.57 ml of their actual volumes with 95% confidence. This study makes it possible to estimate the volume of eggs from the shells of hatched eggs and identify a variation larger than 7.72% in the birth mass of Nile crocodile hatchlings from eggs with an estimated volume of 60 ml, with the precision increasing to identify a variation larger than 3.40% for hatchlings from eggs with an estimated volume of 135 ml with 95% confidence.
’n Model om Nylkrokodileiers se volumes mee te skat nadat hulle uitgebroei het: Die waarde van hul leer stimuleer kommersiële boerdery met verskeie spesies van die Crocodilia. Oorlewings- en groeivermoë van krokodilbroeilinge hou verband met hul geboortemassa. Daar bestaan ’n positiewe verband tussen broeilinggrootte en eiergrootte van verskeie spesies van die Crocodilia. Krokodileiers se grootte word dikwels nie gemeet voordat hulle uitbroei nie. Die doel van hierdie studie was om ’n model te skep waarmee die volume van individuele Nylkrokodileiers geskat kan word nadat hulle uitgebroei het en die dop gebreek is, sodat die verband tussen eiervolume en broeilingmassa op ’n individuele basis bestudeer kan word sonder dat die grootte van eiers gemeet is voordat hulle uitbroei.
Onvrugbare eiers is in sy-aansig gefotografeer, met een pool na onder en die ander na bo en ’n skaal op die vlak van fokus. Hul volume is met waterverplasing gemeet (verplasingsvolume). ’n Rekenaarprogram wat vir die doel geskryf is, is gebruik om die fotobeelde te meet. Die program het die eierbeeld regop gedraai en die posisie van die poolas bepaal sonder om die boonste pool se posisie in ag te neem. Die lengte van verskeie dwarsdeursnitte (loodreg op die poolas) is gemeet, en die volume van die eier bereken deur die funksie wat die horison van die eier op die poolas beskryf te integreer (berekende volume). Die beste modelle is bepaal om die berekende volume te skat deur gebruik te maak van inligting beperk tot verskillende afstande van die onderste pool in die rigting van die boonste te gebruik, en vir eiers met verskillende polariteit. Die modelle is daarna gebruik om die volumes van 138 eiers waarvan 15%, 20%, 25% en 30% van elke eierbeeld, van die boonste pool in die rigting van die onderste, gemaskeer is.
Deur analise van die gemaskeerde fotobeelde kan die volume van eiers met volumes van 60 ml tot 135 ml met 95% vertroue binne 4.57 ml van die werklike voorspel word. Hierdie studie skep die moontlikheid om die volume van uitgebroeide Nylkrokodileiers te skat. Variasie in Nylkrokodille se geboortemassa van groter as 7.72% kan met 95% vertroue geïdentifiseer word vir broeilinge uit eiers met ’n geskatte volume van 60 ml, terwyl die presisie verbeter tot ’n variasie groter as 3.40% vir broeilinge uit eiers met ’n geskatte volume van 135 ml.
Beskrywing, modellering en dok-studies van Plasmodium falciparum kinase PfCDPK4
Authors: Thomas Makungo, Tsepo Tsekoa, Anjo Theron, Dalu Mancama and Teunis van Ree
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 38, pp 1 –15 (2019)
Met die toenemende voorkoms van weerstandige Plasmodium stamme het die beheer van malaria-voorkoms en -mortaliteit weer op die voorgrond getree. Nuwe teikens en antimalariamiddels wat effektief is teen weerstandige malaria-parasiete word dus dringend benodig. Kalsium-afhanklike proteïenkinases (calcium dependent protein kinases – CDPKs) is betrokke by die beheer van ’n aantal biologiese prosesse in die malaria-parasiet, Plasmodium falciparum, met CDPK4 die belangrikste ensiem in hierdie klas. In hierdie studie is die struktuur van PfCDPK4 gebruik as templaat vir die soeke na nuwe malariamiddels. Die PfCDPK4 modelstruktuur is deur middel van homologiemodellering gegenereer en die stereochemiese kwaliteit gevalideer. Die molekulêre modelleringbenadering deur middel van in silico sifting teen die teiken-molekuul PfCDPK4 het ’n beskeie biblioteek van 20 000 chemiese verbindings ingesluit, asook ’n aantal aktiewe natuurprodukte en kliniesgoedgekeurde kinase-inhibeerders. In silico sifting van die Biofocus biblioteek teen PfCDPK4 het 26 verbindings opgelewer; in vitro sifting het bevestig dat drie van hierdie verbindings matig aktief is teen Plasmodium falciparum NF54, met persentasie inhibisie tussen 42% en 47%.
Characterization, modelling and docking studies of Plasmodium falciparum kinase PfCDPK4: The increasing incidence of Plasmodium strains that are resistant to current frontline antimalarial drugs has become one of the greatest challenges of controlling malaria incidence and mortality. There is, therefore, an urgent need to develop novel targets and antimalarial drugs that are effective against drug-resistant malarial parasites. At the same time the need to develop antimalarial drugs that furthermore prevent disease transmission, has become an increasingly important consideration. Calcium dependent protein kinases (CDPKs) regulate a variety of biological processes in the malaria parasite Plasmodium falciparum, CDPK4 being of prime importance in Plasmodium biology. In this study the structure of PfCDPK4 was used as a template in the discovery of malaria drug leads. The model structure of PfCDPK4 was generated by homology modelling, and model validation confirmed that the model of PfCDPK4 is of stereochemical quality. The molecular modelling approach of in silico screening against the target molecule PfCDPK4 utilized a large library of chemical compounds, some natural chemical compounds, and clinically approved kinase inhibitors. In silico screening of the Biofocus library against PfCDPK4 resulted in twenty-six compounds being identified; in vitro screening confirmed that three of these compounds exhibit moderate antimalarial activity against the NF54 strain of Plasmodium falciparum, with the percentage inhibition ranging between 42% and 47%.
Geografiese ligging beïnvloed vaginale mikrobiese profiele in Suid Afrikaanse vroue
Authors: Katie Lennard, Smritee Dabee, Shaun L. Barnabas, Enock Havyarimana, Anna Blakney, Shameem Z. Jaumdally, Gerrit Botha, Nonhlanhla N. Mkhize, Linda-Gail Bekker, David A. Lewis, Glenda Gray, Nicola Mulder, Jo-Ann S. Passmore and Heather B. Jaspan
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 38, pp 1 –9 (2019)
Vroue van Afrika-afkoms is meer vatbaar vir bakteriële vaginose (BV) in vergelyking met Europese vroue. Beide mikrobiese diversiteit (soos met BV) sowel as spesifieke bakteriële taksa speel ‘n rol in seksuele en reproduktiewe gesondheid insluitende MIV vatbaarheid.
Die moontlike rol van geografiese ligging en etnisiteit op die verhouding tussen mikrobiese samestelling en seskuele en reproduktiewe gesondheid bly egter onbekend.
In hierdie studie vergelyk ons dus die vaginale mikrobiota van 16–22-jarige swart, HIVnegatiewe Suid Afrikaanse vroue van twee geografies-uiteenlopende liggings, beide laeinkomste, hoë bevolkingsdigtheidsgemeenskappe, een in Kaapstad, en een in Johannesburg.
Vaginale mikrobiese profiele is bepaal met behulp van 16S rRNS volgordebepaling van laterale muur deppers.
Ons pas permutasie variansieanalise (PERMANOVA) toe en vind statisties betekenisvolle assosiasies tussen vaginale mikrobiese samestelling en geografiese ligging (p=0.02), asook met liggaamsmassa-indeks (LMI) (p=0.015) en menslike papilloomvirus (MPV) risikotipe (p=0.005), maar nie met die voorkoms van een of meer seksueel-oordraagbare infeksies (SOI’s) (p=0.053) of met hormonale kontrasepsie verbruik nie.(p=0.4).
Geografiese ligging was ‘n statisties betekenisvolle determinant van mikrobiese samestelling, ongeag verskille in LMI, SOI status en MPV-risiko tipes tussen Kaapstad en Johannesburg vroue. Geografiese ligging, LMI en MPV-risiko verduidelik gesamentlik 10% van die variansie in mikrobiese samestelling, met ‘n groot persentasie van onbekende oorsprong. Verskeie taksa het statisties betekenisvol verskil in terme van frekwensie of relatiewe vlakke van voorkoms tussen die geografiese liggings.
Ons resultate stel voor dat MIV profilaktiese metodes wat die vaginale mikrobiota teiken die effek van geografiese ligging in ag moet neem.
Vaginal microbiota varies by geographical location in South African women: Women of African descent are more likely to have bacterial vaginosis than women of other ethnicities. Both diversity and likely specific taxa in these microbial communities are important to sexual and reproductive health, such as HIV risk. However, whether the specific taxa also vary by geographical location and/or ethnicity requires further investigation.
Here, we compare the vaginal microbiota of 16–22-year-old black, HIV-negative South African women from two geographically disparate but low-income high population density communities, one in Cape Town (CPT) and one in Johannesburg (JHB). Vaginal microbiota composition was assessed by 16S rRNA gene amplicon sequencing of lateral vaginal wall swabs.
Geographical location was significantly associated with vaginal microbiota composition by permutational analysis of variance (PERMANOVA) (p=0.02), as were body mass index BMI (p=0.015) and human papilloma virus (HPV) risk type (p=0.005), while the presence of one or more sexually transmitted infections (STIs) (p=0.053) and hormonal contraceptive (HC) usage (p=0.4) were not. Geographical location remained a significant determinant of microbiota composition independent of BMI, STI status and HPV-risk. Together, geographical location, BMI and HPV-risk explained 10% of the variance in microbiota composition with a large proportion of the variance remaining unexplained. Several taxa differed significantly between geographical location – some by frequency and others by relative abundance.
Our results therefore suggest that HIV prophylactic approaches targeting the vaginal microbiota should be geographically tailored.
Oopbronintelligensie (OSINT) vir veiligheidsdoeleindes : die ontwikkeling van ’n dataontledingspyplyn om relevante WhatsAppboodskappe te ontleed
Authors: Burgert A. Senekal and Eduan Kotzé
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 38, pp 1 –10 (2019)
Oopbronintelligensie het in die laaste paar dekades die dominante intelligensiedissipline geword. Die inligtingsontploffing het egter daartoe gelei dat geoutomatiseerde metodes aangewend moet word om inligting uit groot hoeveelhede data, wat gereeld in ’n ongestruktureerde formaat bestaan en deurlopend gegeneer word, te onttrek. Boonop het nuwe inligtingskanale soos sosiale media ontstaan wat beteken dat nie slegs die hoofstroommedia gemonitor kan word om gebeurtenisse te identifiseer nie. Hierdie artikel bespreek hoe ’n dataversamelings en -ontledingspyplyn saamgestel kan word om inligting uit WhatsApp boodskappe, wat op groepe met hul eie sienings van veiligheidsbegrippe of probleme voorkom, en onder meer verwys na gewelddadige betogings, plaasaanvalle, grondgrype en ander misdaad in Suid-Afrika, te onttrek. Daar word bespreek hoe teks skoongemaak word en gebeurtenisse en plekname onttrek word en dan outomaties na ’n visuele en interaktiewe gebruikerskoppelvlak uitgevoer word om die voorkoms van hierdie gebeurtenisse in kleiner areas of sektore en later landswyd te kan monitor. Uitdagings en probleme word bespreek, sowel as verdere navorsingsgeleenthede, wat insluit om so ’n stelsel met veiligheidheidsreaksiemagte soos die Polisiediens se databasisse te integreer ten einde waardevolle reaksie vir die gemeenskap ten opsigte van veiligheid te weeg te bring.
Open Source Intelligence (OSINT) for security purposes: Developing a data analysis pipeline to analyse relevant WhatsApp messages: Open source intelligence has become the dominant intelligence discipline over the past few decades. However, the information explosion has led to a need for automated methods to be used to extract information from large amounts of data, which is often in an unstructured format and continuously generated. In addition, new information channels such as social media have emerged which mean that not only the mainstream media can be monitored to identify events. This article discusses how a data collection and analysis pipeline can be compiled for extracting information from WhatsApp messages, which appear on groups that focus on security concepts or problems, and refer, inter alia, to violent protests, farm attacks, land grabs and other crime in South Africa. It discusses how to clean text and extract events and place names, and then automatically exports the results to a visual and interactive user interface to monitor the occurrence of these events in smaller areas or sectors and later nationwide. Challenges and problems are discussed, as well as further research opportunities, which include integrating such a system with security response forces such as the Police Service’s databases in order to provide valuable response for the community in terms of safety.
’n Algemene oorsig van die makroinvertebraatdiversiteit van die Maricorivier, Noordwes Provinsie, Suid Afrika
Authors: Mathilde Kemp, Victor Wepener and Cornelius T. Wolmarans
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 38, pp 1 –11 (2019)
Die Maricorivier, in die Noordwes Provinsie van Suid Afrika, is in terme van bewaring as ’n prioriteitsgebied verklaar. Die doel van hierdie ondersoek was om die makroinvertebraatdiversiteit van die Maricorivier te bepaal, te dokumenteer en te publiseer. Makroinvertebrate is tydens vyf opnames by ses lokaliteite in die rivier met die gepaste nette en tegnieke versamel, terwyl geselekteerde waterkwaliteitsparameters telkens in-situ gemeet is. ’n Totale diversiteit van 172 taksa (20 ordes en 81 families), verteenwoordig deur 12540 organismes, is tydens die ondersoek gevind. Die meeste van die families wat bekend is daarvoor dat hulle ’n voorkeur vir water van hoë kwaliteit vertoon, is gevind. Waardes vir temperatuur, pH, EG, vloeisnelheid en turbiditeit was deurentyd binne die toleransiereekse vir akwatiese makro-invertebrate. Uit die resultate kan daar afgelei word dat die rivier oorwegend oor ’n hoë taksa-rykheid en diversiteit beskik en dat die taksa eweredig versprei is, wat op ’n gesonde ekostelsel dui. Die teenwoordigheid van verskeie hoogs sensitiewe taksa ondersteun hierdie stelling.
A general overview of the macro-invertebrate diversity in the Marico River, North-West Province, South Africa: The Marico River, in the North West Province of South Africa, has been declared a priority area in terms of conservation. The purpose of this investigation was to determine, document and publish the macro-invertebrate diversity of this river. Macro-invertebrates were collected during five surveys at six sites in the Marico River by means of appropriate nets and techniques, while selected water quality parameters were measured in situ. A total diversity of 172 taxa (20 orders and 81 families), represented by 12540 organisms, was found during this investigation. Most of the families which are known to display a preference for high water quality have been found. Values for temperature, pH, EC, flow rate and turbidity were within the tolerance ranges for aquatic macro-invertebrates throughout the study. From the results it can be concluded that the river has predominantly high taxa richness and diversity and that the taxa are evenly distributed, which indicates a healthy ecosystem. The presence of several highly sensitive taxa further supports this statement.
Die verband tussen broelingmassa en eiervolume in die Nylkrokodil (Crocodylus niloticus) : eiers se produktiwiteit varieer
Authors: Johan O. Nöthlinga, Johan A. Nöthling and Jan G. Myburgh
Die oorlewing en lewenskragtigheid van Nylkrokodil (Crocodylus niloticus) broeilinge is belangrik vir die sukses van kommersiële krokodilboerdery en die instandhouding van populasies in die natuur. In hierdie studie beskryf ons eers die verband tussen die massa van Nylkrokodilbroeilinge en die geskatte volume van die eier waaruit elkeen gebroei het. Daarna beskryf ons die variasie in die verhouding tussen die massa van individuele broeilinge en die volume van die eier waaruit elk gebroei het (die produktiwiteit van die eier) binne en tussen broeisels. Die volumes van 316 Nylkrokodileiers uit 51 broeisels is met ’n doelgemaakte algoritme geskat op grond van sleutelafmetings van die eiers wat op foto’s van die uitgebroeide eierdoppe gemaak is. Die broeiling wat uit elke eier gebroei het is direk na uitbroei geweeg. Nóg die duur van inkubering tot uitbroei (P = 0.88) nóg die jaar waarin broeisels gelê is (P = 0.35) nóg die aantal eiers in die broeisel (P = 0.57) het broeilingmassa beïnvloed. Daar bestaan ’n sterk, lineêre positiewe verband tussen die uitbroeimassa van Nylkrokodilbroeilinge en die geskatte volume van die eiers waaruit hulle gebroei het r = 0.88, P < 0.001, n =316). Sonder inagneming van geskatte eiervolume is 86.9% van die variasie in broeilingmassa die gevolg van variasie tussen broeisels en 13.1% die gevolg van variasie binne broeisels. Indien geskatte eiervolume in berekening gebring word is 59% van die variasie in broeilingmassa vir ’n bepaalde geskatte eiervolume die gevolg van variasie tussen broeisels en 41% die gevolg van variasie binne broeisels. Die produktiwiteit van eiers het van 0.57 g/ml tot 0.81 g/ml gevarieer, met 45.4% van die variasie wat tussen broeisels voorgekom het en 54.6% binne broeisels. Verdere navorsing is nodig om die verband tussen broeilingmassa en die groei van broeilinge, sowel as die verband tussen eierproduktiwiteit en die groei van broeilinge te ondersoek.
The relationship between hatchling mass and egg volume in the Nile crocodile (Crocodylus niloticus): The productivity of eggs varies: The survival and vitality of Nile crocodile (Crocodylus niloticus) hatchlings is important for the success of commercial crocodile farming and the maintenance of wild populations. In this study we describe the relationship between the mass of Nile crocodile hatchlings and the estimated volume of the eggs from which they hatched and, following that, we describe the variation in the ratio between the mass of individual hatchlings and the egg volume from which each hatched (the productivity of the egg) within and among clutches. The volumes of 316 Nile crocodile eggs from 51 clutches were estimated by means of a purpose-made algorithm that uses key dimensions of eggs obtained from photos of the hatched shells. The hatchling from each egg was weighed immediately after hatching. Neither the duration of incubation prior to hatching (P = 0.88) nor the year in which clutches were laid (P = 0.35), nor the number of eggs per clutch (P = 0.57) affected hatchling mass. There exists a strong, linear, positive relationship between the mass of Nile crocodile hatchlings and the estimated volume of the eggs from which they hatched (r = 0.88, P < 0.001, n = 316). Without considering estimated egg volume, 86.9% of the variation in hatchling mass occurs among clutches and 13.1% within clutches. Taking estimated egg volume into account, 59% of the variation in hatchling mass occurs among clutches and 41% within clutches. Egg productivity varied from 0.57 g/ml to 0.81 g/ml, with 45.4% of the variation occurring among clutches and 54.6% within clutches. Further research is required to investigate the relationship between hatchling mass and the growth of hatchlings, as well as between egg productivity and the growth of hatchlings.
Oorsig van faseveranderingsmateriaal vir sub-zero temperatuurtoepassings in verkoelingsvervoer
Authors: Casey Ndanduleni and Zhongjie Huan
Hierdie artikel bied ’n oorsig van die tradisionele gebruik van faseveranderingsmateriaal (FVM) in verkoelingsvervoer. Die meerderheid faseveranderingsmateriale in bouwerk en konstruksie word vir ruimtelike verwarming en verkoeling, kweekhuis-verhitting, kook met sonkrag, en die berging van son-energie vir waterverhitting gebruik. Daar is egter ’n merkbare afwesigheid van literatuur oor die aanwending van faseveranderingsmateriaal vir gebruik om bevrore voedselprodukte te bewaar. Hierdie oorsig fokus op latente hittebewarings (LHB) materiale se gebruik in padvervoer by ’n lae temperatuur (sub-zero), en van die voordele vir die verkoeling van bederfbare voedsel oor kort- en lang-afstande. Die voordele van die gebruik van latente hitte-bewaringsmateriaal, eerder as ’n konvensionele meganiese verdampings-kompressiesisteem, word ondersoek met die klem op die omgewingsimpak en moontlike langtermyn nadele. Die studie fokus ook op die noodsaaklikheid om nuwe faseveranderingsmateriaal met hoë termiese siklusse en minimale degradering te ondersoek, ten einde die suksesvolle gebruik in verkoelingsvervoer oor die langtermyn te verseker. Kriteria vir die seleksie van toepaslike faseveranderingsmateriaal word opgesom, en ’n klassifikasie van faseveranderingsmateriaal, gebaseer op smelttemperature en latente warmte, word getabuleer. Faseveranderingsmateriaal en die oordrageienskappe daarvan is ontleed ten einde die eienskappe van faseveranderingsmateriaal op te som, en die akkuraatheid van elke navorsingstegniek word beoordeel op grond van soortgelyke studies wat deur ander navorsers publiseer is. Die faseveranderingsmateriaal wat in verkoelingsvervoer gebruik word, is empiries ontleed, en termiese-fisiese krite wat noodsaaklik is vir verskillende toepassings is ook onder die vergrootglas geplaas.
Review on phase change materials for sub-zero temperature application in transport refrigeration: This paper reviews the use of phase change materials (PCMs) in road transport refrigeration. The use of thermal energy storage systems in transport refrigeration focusing particularly on PCMs that have been used in recent years is reviewed. The majority of PCMs are used in building applications for space heating and cooling, greenhouse heating applications, solar cookers, and storage of solar energy for water heating. However, there is minimal focus in the literature on their use in road transport refrigeration in low temperature (sub-zero) application for maintaining frozen foodstuff (products). The focus of this work is on latent heat storage (LHS) materials used in road transport refrigeration and their benefits in the refrigeration of perishable foodstuffs for short- and long-distance transportation. The benefits of using LHS materials over a conventional mechanical vapour compression system are explored with reference to the environmental impact and their disadvantages in the long term. This paper also focuses on the need to develop new PCMs with high thermal cycles and minimal degradation to ensure their successful use in the transport refrigeration industry. Criteria for selecting suitable PCMs for different applications were summarised, and classification of PCMs based on their melting temperature and latent heat were tabulated. Heat transfer materials for increasing PCM performance were analysed as well as the effect of container material corrosion on PCM stability. The different thermal techniques used for determining the properties of PCMs were summarised, and the accuracy of each technique was explored based on similar research work by other researchers. The PCMs that have been used in transport refrigeration as well as the thermo-physical criteria that are needed for different applications were analysed.
Suid-Afrikaanse aandelemarkontwikkeling : die impak van globalisme en nasionalisme
Authors: Cobus Vermeulen, Fanie Joubert and Jannie Rossouw
Hierdie navorsing ondersoek die faktore wat die ontwikkeling van die Suid-Afrikaanse aandelemark (die Johannesburgse Aandelebeurs, JSE) aandryf, ten einde te bepaal of JSEontwikkeling oorwegend deur internasionale (globale) of plaaslike (nasionale) faktore aangedryf word. Vir hierdie doel word die ARDL grenstoets (“bounds test”) gebruik as empiriese raamwerk waarbinne die rol van verskeie makro-ekonomiese veranderlikes, geklassifiseer as òf plaaslik òf internasionaal, in die ontwikkeling van die JSE – soos benader deur die markkapitalisasiekoers – ondersoek word. Die navorsingsbevinding is dat plaaslike ekonomiese groei, banksektorontwikkeling en rentekoerse, asook die wisselkoers en handelsoopheid die vernaamste langtermyndrywers van JSE-ontwikkeling is. Dus speel sowel plaaslike as internasionale faktore ’n beduidende rol in die ontwikkeling van die JSE.
South African stock market development: The impact of globalism and nationalism: This study investigates the factors that drive the development of the South African stock market (the Johannesburg Stock Exchange, JSE), in order to determine whether the development of the JSE is driven mainly by international (global) or domestic (national) factors. To this end the ARDL bounds test is used as empirical framework within which the role of various macroeconomic variables, classified as either domestic or international, in the development of the JSE – approximated by the market capitalisation ratio – are evaluated. The study finds that the main long-term drivers of JSE development are domestic economic growth and interest rates, the development of the local banking sector, as well as the exchange rate and trade openness. Therefore, both domestic and international factors are significant in the development of the JSE.