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Bell	in Dieppe, NB Volume 32, Issue 1, 2013
Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie - Volume 32, Issue 1, January 2013
Volume 32, Issue 1, January 2013
Rol van Lesotho-Hooglandwater op Vaalrivieralge : oorspronklike navorsing
Author Sanet Janse van Vuuren
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32, pp 1 –10 (2013) http://dx.doi.org/10.4102/satnt.v32i1.335
Die Vaalrivier is, met verloop van tyd, tot so 'n mate verryk deur voedingstowwe dat algopbloeie tans probleme skep. 'n Unieke geleentheid om te bepaal of daar veranderinge in die waterchemie en algsamestelling in die Vaalrivier voorgekom het, het hom voorgedoen nadat oligomesotrofe Katsedamwater (Lesotho) ingevoer is om in die toenemende wateraanvraag in die Vaalrivieropvangsgebied te voorsien. Die konsentrasie en samestelling van alge in die Vaalrivier is tydens die periodes tussen 1992 en 1994, tussen 1998 en 2000, asook 2004 en 2006 vergelyk met dié in die Katsedam tussen 1998 en 2006. Sekere algspesies, wat aanvanklik afwesig was in die Vaalrivier, het ná die oordrag van Lesothowater voorgekom. 'n Gemengde algpopulasie wat in die Vaalrivier gevind is voordat Katsedamwater oorgedra is, het ná die oordrag geleidelik verander na 'n populasie wat gedomineer is deur sianobakterieë. Die totale algkonsentrasie in die Vaalrivierbarrage het verdubbel van die periode tussen 1992 en 1994 tot dié tussen 2004 en 2006 wat aandui dat die oordrag van helder, oligomesotrofe Katsedamwater die eutrofe Vaalrivierwater nie genoegsaam verdun het om die algkonsentrasie te laat afneem nie. Resultate toon aan dat stroomaf-besoedeling en eutrofikasie in die Vaalriviersisteem die verdunningseffek van Katsedamwater uitgeskakel het. Dit het tot veranderinge in die algsamestelling en -konsentrasie, kenmerkend van toenemende eutrofikasie, in die Vaalrivier gelei.
Long-term changes in the algal composition of the Vaal River, South Africa - did the Lesotho Highlands Water Project play a role?
The Vaal River has become so nutrient-enriched that algal blooms pose problems. A unique opportunity arose to determine if there were changes in the chemistry en algal composition of the Vaal River after oligomesotrophic Katse Dam (Lesotho) water was imported to augment supplies in the light of growing water demands in the Vaal River catchment area. Algal concentration and composition in the Vaal River during three periods (between 1992 and 1994, 1998 and 2000, as well as 2004 and 2006) were compared to those in the Katse Dam (1998-2006). Some algal species, initially absent from the Vaal River, appeared in the river during and after transfer. Mixed algal assemblages found in the Vaal River before transfer of Katse Dam water gradually changed after transfer to assemblages mainly composed of cyanobacteria. The total algal concentration in the Vaal River Barrage doubled from the period between 1992 and 1994 to that between 2004 and 2006, indicating that the transfer of clear, oligomesotrophic Katse Dam water did not dilute the eutrophic Vaal River water sufficiently in order to reduce algal concentrations. Results showed that continuous downstream pollution and eutrophication of the Vaal River system eliminated the diluting effect of Katse imports. This resulted in changes in algal composition and concentration in the Vaal, characteristic of those associated with increasing eutrophication.
Einstein se relatiwiteitsteorie : op die kruispunt van aprioriese elemente en empiriese ervaring : oorspronklike navorsing
Author Danie F.M. Strauss
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32, pp 1 –8 (2013) http://dx.doi.org/10.4102/satnt.v32i1.329
Waardering vir die status van natuurwetenskaplike kennis volg 'n merkwaardige wentelgang deur die geskiedenis van die filosofie en die verskillende vakwetenskappe. Te midde van ekstreme uiterstes moes die benadering van Einstein 'n rigting vind wat beide 'n eensydige apriorisme en 'n oordrewe positivisme afwys. Die historiese agtergrond van die aprioriteitsprobleem - dit wat ons ervaring voorafgaan - is vlugtig nagespeur tot by die Griekse wortels daarvan. Omdat Einstein ruimte gelaat het vir skeppende denke, het dit hom weliswaar in staat gestel om van die universaliteit van sleutelaspekte van die natuur gebruik te maak, in die besonder gefokus op die uniekheid en die samehang van die kinematiese en fisiese aspekte van die werklikheid. Enersyds het die onderskeid tussen hierdie twee aspekte â??n vertrekpunt verskaf om kritiek te lewer op die meganistiese inslag van die klassieke fisika (toegespits om die onderskeid te tref tussen omkeerbaarheid en onomkeerbaarheid), en andersyds het die ontiese universaliteit van hierdie aspekte hom gehelp om hierdie onties aprioriese gegewens tot hul reg te laat kom, ook ten opsigte van die eise wat die ervaring stel (die relatiewe reg van die positivistiese klem op die eksperimentele toetsing van tipewette). Hieruit volg dat Einstein se siening met reg as 'n transendentaal empiriese benadering getipeer kan word. Dit belig ook die onderskeid tussen modale wette en tipewette, asook die skynbaar misterieuse toepaslikheid van die wiskunde op natuurverskynsels. Laastens word aangevoer dat die onlangse beweringe oor die snelheid van die neutrino wat vinniger as dié van lig sou wees, nié Einstein se spesiale relatiwiteitsteorie (sal) weerlê nie
Einstein's theory of relativity: At the intersection of apriori elements and empirical experience. Appreciation for the status of scientific knowledge followed a remarkably winding path throughout the history of philosophy and of the various specialised sciences. Einstein had to find direction, avoiding the extremes of a one-sided apriorism and an excessive positivism. The historical background of the problem of what is apriori - that which precedes our experience - is briefly traced back to its Greek roots. Because Einstein did leave room for creative thinking, it empowered him to explore the universality of key aspects of nature, focusing particularly on the uniqueness and coherence of the kinematic and physical aspects of reality. Distinguishing between these aspects provides, on the one hand, a point of departure for criticising the mechanistic inclination of classical physics (directed at the distinction between reversibility and irreversibility), and on the other hand, the ontic universality of these aspects. This helps us to do justice to the ontic universality of these aspects in respect to the demands of experience (the relative justification of the positivistic emphasis on experimental testing of type laws). So Einstein's approach may be classified as a transcendental-empirical method of investigation. It also highlights the distinction between modal laws and type laws, as well as the apparently mysterious applicability of mathematics to natural phenomena. Finally it is argued that the recent reports in the news media regarding the speed of the neutrino, allegedly faster than that of light, will not invalidate Einstein's theory of relativity.
Hemofilie onder die nasate van koningin Victoria : oorspronklike navorsing
Authors: Francois P. Retief, Andre Wessels and Johan F.G. Cilliers
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32, pp 1 –4 (2013) http://dx.doi.org/10.4102/satnt.v32i1.341
Hierdie studie bespreek die uitwerking van die sogenaamde Victoriaanse hemofilie op Europese koningshuise gedurende die negentiende en twintigste eeu. Hemofilie as molekulêre defek word verduidelik en die kliniese beeld van die siekte word aangedui. 'n Bespreking van toepaslike terapeutiese ingrepe volg. Dan word 'n historiese oorsig verskaf van die verspreiding van Victoriaanse hemofilie vanaf koningin Victoria (Britse monarg, 1837-1901) via sommige van haar dogters na ander lede van die Britse koningshuis en ook na die Duitse, Russiese en Spaanse koningshuise. Elf bevestigde gevalle van hemofilie onder lede van koningin Victoria se nageslag word vermeld, asook drie ander moontlike gevalle van die siekte. Die effek van hemofilie op die verloop van die geskiedenis word ook ondersoek.
Haemophilia amongst the descendants of Queen Victoria. This study discusses the impact of 'Victorian haemophilia' on the royal houses of Europe during the 19th and 20th centuries. Haemophilia as a molecular defect is explained and the clinical picture of the condition is indicated. Applicable therapeutic interventions also receive attention. Next, an historical review is provided of how 'Victorian haemophilia' spread from Queen Victoria (British monarch, 1837-1901) via some of her daughters to other members of the British royal family and also to the royal houses of Germany, Russia and Spain. Eleven confirmed cases of haemophilia amongst the descendants of Queen Victoria are mentioned, as well as three other possible cases. The effect of haemophilia on the course of history is also investigated.
Uitdagings in die onderrig van evolusie in die lewenswetenskappeklaskamer : oorspronklike navorsing
Authors: Josef J. De Beer and Elizabeth Henning
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32, pp 1 –9 (2013) http://dx.doi.org/10.4102/satnt.v32i1.261
In hierdie artikel skryf die outeurs oor navorsing wat hulle gedoen het oor onderwysers se siening van die onderrig van evolusie, wat in 2008 as 'n tema in lewenswetenskappe in Suid-Afrikaanse skole ingesluit is. Hierdie vernuwing in die kurrikulum is met gemengde reaksies begroet. Terwyl sommige onderwysers dit met entoesiasme onderrig, is baie gekant teen die onderrig van evolusie. Die artikel is gebaseer op 'n navorsingsprojek waarby 255 onderwysers betrek is. Vraelyste is gebruik om kwalitatiewe data, wat vir diskoers ontleed is, in te samel. Die diskoers van die onderwysers het getoon dat 'n groot getal van hulle nie hul onderrigopdrag kan versoen met hul geloof nie en konsepte oor evolusie as 'feite' verduidelik, maar seker maak dat evolusie as 'n teorie gediskrediteer word. Dit het verreikende implikasies vir sowel onderwyseropleiding as kurrikulumontwikkeling. Konseptuele veranderingsteorie word as 'n lens gebruik om na hierdie problematiek te kyk.
Challenges in the teaching of evolution in the life sciences classroom.
In this article the authors report on research that was conducted about teachers' views on evolution, which was introduced as a theme in the school life sciences curriculum in 2008. This innovation in the curriculum has been met with mixed reactions. Whereas some teachers embrace this new theme, many teachers are opposed to the teaching of evolution. The article reports on an inquiry that was conducted amongst 255 teachers and in which survey questionnaires were used to collect qualitative data, which was analysed for its discourse. The discourse of the teachers shows that many of them cannot reconcile their religious faith with their teaching and that they may teach the 'facts' of evolution, but make sure that they discredit evolution as a theory. This raises serious concerns about teacher education and curriculum development. The authors examine these issues through the lens of conceptual change theory.
Privaat aftreeoorde in Suid-Afrika : riglyne vir welstand en volhoubaarheid op die lang termyn : oorspronklike navorsing
Author Andries C. Hauptfleisch
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32, pp 1 –8 (2013) http://dx.doi.org/10.4102/satnt.v32i1.330
Ongesubsidieerde privaat aftreeoorde in Suid-Afrika wat gedurende die afgelope drie dekades ontwikkel is, bied talle uitdagings aan die inwoners. Daar bestaan nie 'n algemeen erkende kennisbasis of riglyne om hierdie sensitiewe mark te bedien nie. Navorsing is gedoen om te bepaal welke aspekte die inwoners van aftreeoorde as bevredigend en welke as problematies ervaar. Hierdie navorsing het ook 'n literatuurstudie ingesluit. By wyse van gestruktureerde vraelyste, onderhoude en 'n seminaar is kwantitatiewe sowel as kwalitatiewe data bekom. Die resultate wat betrekking het op agt oorde in die ooste van Pretoria, vier in Bloemfontein en twee op Knysna word gerapporteer, terwyl die studie steeds in ander sentra voortgesit word. Die kwantitatiewe data is in voorkeurvolgorde van die grootste groep (Pretoria) gedoen, met die ander groepe daarteenoor aangetoon. Die navorsingsmetodiek was dus gebaseer op die versameling van gekwantifiseerde en kwalitatiewe data, asook beskrywende evaluering. Die resultate bied insiggewende kennis en riglyne ter bepaling van 'n optimale profiel vir die ontwikkeling van privaat aftreeoorde wat volhoubare dienste kan lewer. Die implikasie en waarde van dié studie is dat beide ontwikkelaars van aftreeoorde en voornemende inwoners in staat gestel word om te kan evalueer of 'n bepaalde aftreeoord welstand op die lang termyn volhoubaar aan inwoners sal kan bied.
Private retirement resorts in South Africa: Guidelines for wellness and sustainability in the long term.
Unsubsidised private retirement resorts in South Africa developed during the last three decades present residents with many challenges. There is no existing generally accepted knowledge base or guidelines to serve this sensitive market. The research objective was to establish which elements are experienced by residents of retirement resorts as satisfactory and which as problematic. A literature study was also undertaken. Quantitative as well as qualitative data were obtained by means of structured questionnaires, interviews and a seminar. The results reported pertain to eight resorts in the east of Pretoria, four in Bloemfontein and two in Knysna. The study is currently being extended to other centres. The quantitative data is arranged in order of the priorities set by the biggest group (Pretoria), with the other groups in comparison. So the research was based on the sourcing of quantitative and qualitative data, as well as on descriptive evaluations. The results offer insightful knowledge and guidelines towards establishing an optimal profile for the development of long-term sustainable private retirement resorts. The implications and value of this study are that both developers of retirement resorts and prospective residents are provided with guidelines to better equip them to evaluate a specific retirement resort with regard to the sustainable wellbeing of residents long-term.
Elektroniese eienskappe van die Mn(asas)3-kompleks : 'n sikliese voltammetrie- en berekeningschemiestudie : referaatopsomming
Authors: Roxanne Freitag and Jeanet Conradie
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32, pp 1 –2 (2013) http://dx.doi.org/10.4102/satnt.v32i1.410
Electronic properties of Mn(acac)3 complex : a cyclic voltammetry and computational chemistry study
Tris(acetylacetonato) Manganese(III) is a catalyst in alkyd paint. In this study, the electronic properties of Mn(acac)3 are determined by means of electrochemistry and computational chemistry. The optimised geometrical and electronic structure of Mn(acac)3 is calculated by means of computational chemistry, and electrochemistry is applied to measure the following reactions:
MnIII(acac)3 - e- ⇆ MnIV(acac)3
MnIII(acac)3 + e- ⇆ MnII(acac)3
Fotondegradasie van Alq3-poeier : referaatopsomming
Authors: Mart-Mari Duvenhage, O.M. Ntwaeaborwa and H.C. Swart
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32 (2013) http://dx.doi.org/10.4102/satnt.v32i1.409
Photon degradation of Alq3 powder
In this study the photon degradation of Alq3 powders is investigated. The sample is irradiated for 330 hours by means of a UV lamp, and the chemical changes between the undegraded and degraded samples are monitored by means of X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FTIR).
Plaaslike kennis oor insekplae en die bestuur daarvan deur kleinskaalse rooibosteeboere in die Sederberge, Suid-Afrika : referaatopsomming
Authors: Samantha De la Fontaine and R.R. Malgas
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32 (2013) http://dx.doi.org/10.4102/satnt.v32i1.408
Local knowledge of insect pests and the management thereof by small-scale rooibos tea farmers in the Cederberg Mountains, South Africa
The aim of the study was to identify insect pests and traditional pest management practices associated with rooibos tea (Aspalathus linearis) cultivation based on local knowledge of small-scale producers in the Cederberg.
Die invloed van verdamping op die segregasieproses : referaatopsomming
Authors: Shaun Cronje, W.D. Roos, R.E. Kroon and J.K.O. Asante
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32 (2013) http://dx.doi.org/10.4102/satnt.v32i1.407
Metallurgical products play an important role in everyday life. One process, by means of which metallurgical properties can be determined, is known as segregation. The influence of surface evaporation should be considered in order to improve segregation studies. Modifications made to an Auger system in order to measure surface evaporation that takes place during segregation are discussed.
Ondersoek na die gebruik van ortogonale ontbinding om interne okulêre druk te bepaal : referaatopsomming
Authors: Natasha Botha, Schalk Kok and Helen Inglis
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32 (2013) http://dx.doi.org/10.4102/satnt.v32i1.406
Investigating the use of proper orthogonal decomposition to determine intra-ocular pressure
Accurately determining intraocular pressure (IOP) is crucial to the diagnosis and management of glaucoma, the leading cause of irreversible blindness in South Africa. This study aims to investigate the possibility of using proper orthogonal decomposition (POD) to determine IOP from ocular response data obtained from numerical simulations.
Biometriese egtheidsbevestiging tydens intydse bankdienste : referaatopsomming
Authors: Frans F. Blauw and Sebastiaan H. Von Solms
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32, pp 1 –2 (2013) http://dx.doi.org/10.4102/satnt.v32i1.403
A system for biometric authentication in online banking
Online banking is under attack by cyber criminals using methods such as phishing, spoofing, and man-in-the-middle attacks. The system proposes using a biometrically secured USB stick containing the client's fingerprint, a unique key S, and a limited web browser and other information, which is provided to the client by the banking institution. To log on, the client allows his or her fingerprint to be read by the USB stick, and access is granted if the print matches the one previously stored on the USB stick. The browser on the USB stick is then activated, taking the client to the bank's real online banking web page. Every transaction is then secured by means of randomly generated session keys using the shared key S, the transaction information and other information. This system prevents many of the currently known malicious attacks.
'n Teoretiese besinning oor die implikasies van die filosofie van tegnologie vir klaskamerpraktyk : oorspronklike navorsing
Author Piet Ankiewicz
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32, pp 1 –9 (2013) http://dx.doi.org/10.4102/satnt.v32i1.386
Onderrigprogramme vir tegnologie-onderwys en die fasilitering daarvan op krytvlak gaan dikwels mank aan 'n wetenskaplik deurdagte, vakgefundeerde, filosofiese raamwerk wat rigtinggewend vir die verskillende aspekte van klaskamerpraktyk is. Wat sake kompliseer, is die feit dat tegnologie op skoolvlak tans wêreldwyd 'n ontwikkelende vak is waarvoor daar nie 'n ekwivalente akademiese dissipline bestaan wat as bron vir kurrikulumontwikkeling en klaskamerpraktyk dien en waarop daar in die klaskamer prakties en daadwerklik gesteun kan word nie. Die doel met die artikel was om ondersoek in te stel na 'n filosofiese raamwerk vir tegnologie wat rigtinggewend vir klaskamerpraktyk is. Die volgende navorsingsvrae het as vertrekpunt gedien, naamlik, (1) watter aspekte van 'n wetenskaplik deurdagte, filosofiese raamwerk vir tegnologie kan rigtinggewend vir klaskamerpraktyk wees en (2) wat is die implikasies van 'n filosofiese raamwerk vir tegnologie wat betref bepaalde aspekte van klaskamerpraktyk, byvoorbeeld onderrigbenaderings, leeruitkomste en leerinhoud? In antwoord op die eerste navorsingsvraag is bevind dat 'n filosofiese raamwerk vir tegnolgie, aan die hand van die vier wyses waarop tegnologie manifesteer - naamlik as ontologie, epistemologie, metodologie en wilshandeling - rigtinggewend vir klaskamerpraktyk kan wees. Verder hou die onderwyser se keuse van leeruitkomste, breë onderrigbenaderings, -strategieë en -vaardighede, asook die tipes konseptuele en prosedurekennis wat onderrig moet word, ten nouste verband met die filosofiese begronding van tegnologie as fenomeen. In antwoord op die tweede navorsingsvraag kan onderwysers se kennis en begrip van 'n filosofiese raamwerk vir tegnologie as grondslag dien vir bepaalde keuses wat hulle moet uitoefen in terme van leeruitkomste, breë onderrigbenaderings, -strategieë en -vaardighede, asook die tipes konseptuele en prosedurekennis wat onderrig moet word - en dus rigtinggewend vir klaskamerpraktyk word.
A theoretical reflection on the implications of the philosohy of technology for classroom pedagogy
Learning programmes for technology education and its facilitation at chalk level often lack a scientifically founded, subject-based, philosophical framework. Matters are complicated by the fact that technology at school level is globally a developing subject with no existing equivalent academic discipline which can serve as a source of curriculum development and classroom pedagogy to rely upon in practice. The purpose of the article was to do an investigation into a philosophical framework of technology that can be directive to classroom pedagogy. The following research questions served as a departure point for the theoretical reflection that underpinned the article, namely, (1) which aspects of a scientifically founded philosophical framework of technology can be directive to classroom pedagogy and (2) what are the implications of a philosophical framework of technology for specific aspects of classroom pedagogy, for example instructional approaches, learning outcomes and learning content? In answer to the first research question, it was found that a philosophical framework of technology, based on the four modes of the manifestation of technology - namely as object, knowledge, activity, and volition - can be directive to classroom pedagogy. The teacher's choice of learning outcomes, broad instructional approaches, strategies and skills, as well as the types of conceptual and procedural knowledge that should be taught, is closely related to the philosophical underpinning of technology as phenomenon. In answer to the second research question, teachers' knowledge and understanding of a philosophical framework of technology can support the specific choices that they must make regarding the learning outcomes, broad instructional approaches, strategies and skills, as well as the types of conceptual and procedural knowledge that should be taught - and hence become directive to classroom practice.
Broeigedrag en -sukses van tuinduiwe : oorspronklike navorsing
Authors: Ordino Kok and Hennie Butler
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32, pp 1 –5 (2013) http://dx.doi.org/10.4102/satnt.v32i1.340
Broei-aktiwiteite van tuinduiwe (Columba livia) in die Bloemfonteinse stadsgebied vind dwarsdeur die jaar plaas met 'n afname gedurende die laat somermaande wanneer seisoenale reënval in die streek 'n hoogtepunt bereik. Nesstrukture is relatief primitief en word gekenmerk deur 'n losse samestelling van nesmateriaal op opgehoopte, droë voëlmis. Broeisels van twee eiers is die mees algemene grootte en die eiers word gewoonlik binne twee dae ná mekaar gelê. Beide ouers is by die broeiproses van meer as twee weke betrokke, waartydens die eiers 'n progressiewe afname in massa ondergaan. Pas uitgebroeide neskuikens is met geel dons bedek en is grootliks hulpeloos. Egte vere begin eers ná die eerste week te voorskyn kom, en vanaf die derde week kan individue wankelrig rondbeweeg. Afgesien van die eerste paar dae na uitbroei, handhaaf neskuikens van seldsame enkeleier-broeisels deurgaans 'n laer liggaammassa as dié van normale broeisels. Die broeisukses van 247 broeipare vir hierdie studie is 34%. Eierverlies is hoër as die mortaliteitsyfer van neskuikens, en word veral deur klimaatsfaktore soos reënval geaffekteer. Predasie blyk die belangrikste faktor te wees wat die mortaliteitsyfer van neskuikens beïnvloed. Antagonistiese interaksie tussen krans- en tuinduiwe, asook moontlike intraspesie-aggressie, speel egter ook 'n beduidende rol.
Breeding behaviour and breeding success of feral pigeons in the Bloemfontein urban area
Breeding activities of feral pigeons (Columba livia) in the Bloemfontein urban area occur throughout the year with a decrease during the late summer months when seasonal rainfall in the region reaches a peak. Nest construction is relatively primitive and is characterised by a loose composition of nesting material on accumulated dry bird droppings. Two eggs represent the most common clutch size and eggs are usually laid within two days of each other. Both parents are involved in the incubation process lasting more than two weeks, during which the eggs undergo a progressive decrease in mass. Recently hatched nestlings are covered in yellow down and are largely helpless. True feathers only start to emerge after the first week, and from the third week individuals can move about unsteadily. Apart from the first number of days after hatching, nestlings of rare single egg clutches constantly maintain a body mass lower than those from an average clutch. The overall success of 247 breeding pairs for this study was 34%. Egg loss is higher than the mortality rate of nestlings, and is mainly affected by climatic factors such as rainfall. Predation appears to be the most important factor influencing nestling mortality. Aggressive interactions between speckled pigeons and rock doves, however, as well as possible intraspecific aggression also play a significant role.
Die invloed van grootgroeponderrig op die selfgereguleerde leer van tersiêre wiskundeleerders : oorspronklike navorsing
Author Annalie Roux
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32, pp 1 –9 (2013) http://dx.doi.org/10.4102/satnt.v32i1.379
Selfregulering is belangrik in die ontwikkeling van lewenslange leerders, veral by voordiensonderwysers wat op hul beurt modelleerders van selfregulering in hul eie klaskamers gaan wees. Onderrig op tersiêre vlak word grootliks gekenmerk deur tradisionele onderrigmetodes vanweë die groot groepe leerders betrokke. In hierdie studie is vasgestel of 'n bepaalde grootgroeponderrigstrategie 'n invloed het op lede van groot klasgroepe se selfregulering, al dan nie. 'n Kwantitatiewe voortoets-natoets-ontwerp is gebruik waarin die studiegewoontesveld van die Studie-Oriëntasievraelys in Wiskunde aan die begin en einde van die semester ingesluit is. In 'n tweede vraelys het leerders hul belewenis van die grootgroeponderrigstrategie volgens 'n vyfpunt-Likertskaal beoordeel en 'n oopeindevraag voltooi wat ingesluit is om moontlike addisionele verklarings te bied vir die resultate wat verkry is uit die geslote vrae van die vraelys oor grootgroeponderrig. Beskrywende statistiek is gebruik om die data te interpreteer. Uit die resultate blyk dit dat daar nie 'n verbetering in leerders se selfregulering was nie. By ontleding van die oopeindevraag het dit aan die lig gekom dat verskeie aspekte van selfregulering by leerders ontbreek, soos tydsbestuur en goeie studiegewoontes, asook die bereidwilligheid om meer as net die voorgeskrewe probleme te doen.
The influence of a large group teaching strategy on the self-regulated learning of tertiary mathematics learners
Self-regulation is important in developing lifelong learners, especially in the case of pre-service teachers who will soon be models of self-regulation in their own classrooms. In many instances, teaching at tertiary level is characterised by traditional teaching methods in large classes. In this study a particular large group instructional strategy was examined to determine whether it had an influence on learners' self-regulation. A quantitative pre-test post-test design was used which included the study habits field of the Study Orientation questionnaire in Mathematics at the beginning and end of the semester. In a second questionnaire learners rated their experience of the large group teaching strategy according to a five-point Likert Scale and completed an open-ended question that was included to yield possible additional explanations for the results obtained from the closed questions in the questionnaire about large group teaching. A spreadsheet was used to process and summarise the data. Descriptive statistics were used. The results showed that there was no improvement in learners' self-regulation. Analysis of the open-ended question revealed that learners were lacking various aspects of self-regulation, such as time management and appropriate study habits, including the willingness to do to more than practise only the prescribed problems.
Die diversiteit van Suid-Afrikaanse spinnekoppe (Arachnida: Araneae) : dokumentering van 'n nasionale opname : oorspronklike navorsing
Authors: Ansie Dippenaar-Schoeman, Almie Van den Berg, Robin Lyle, Ansie Dippenaar-Schoeman, Charles Haddad, Stefan Foord and Leon Lotz
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32, pp 1 –7 (2013) http://dx.doi.org/10.4102/satnt.v32i1.375
Die Suid-Afrikaanse Nasionale Opname van Arachnida (SANSA) is in 1997 deur die Landbounavorsingsraad (LNR) geïnisieer met die primêre doelwit om die Arachnidafauna van Suid-Afrika op nasionale vlak te dokumenteer. Tydens die tweede fase van die projek, genaamd SANSA II, het die Suid-Afrikaanse Nasionale Biodiversiteitsinstituut (SANBI) deur hul program vir bedreigde spesies van 2006 tot 2010, in vennootskap met die LNR by die projek aangesluit. Gedurende die vier jaar lange projek is daar gepoog om alle beskikbare spinnekopdata in een databasis te konsolideer. Hierdie data is gebruik om die ruimtelike dekking van spesies te bepaal en vas te stel waar gapings in die data bestaan om sodoende prioriteitsareas te identifiseer vir meer gefokuste opnames. Uitgebreide versameltogte deur SANSA-veldwerkbestuurders is gedurende die vier jaar onderneem. Inligting oor spesies is aangevul deur byvangste van ander navorsingsprojekte, studenteprojekte, en deur openbare deelname. Al die pogings het waardevolle inligting voorsien oor die teenwoordigheid en verspreiding van spinnekoppe. Die inligting is gebruik om die Eerste atlas van spinnekopspesies van Suid-Afrika saam te stel, insluitende kaarte om die verspreiding van elke spesie aan te dui, sowel as inligting oor die vlakke van endemisme vir elke spesie. Tans is daar 71 spinnekopfamilies, 471 genera en 2028 spesies in Suid-Afrika bekend. Die derde fase van SANSA is in 2011 van stapel gestuur en verskeie aksies soos die saamstel van 'n rooidatalys van spesies, 'n reeks handboeke vir al die biome, die publikasie van die atlas, en die beskrywing van nuwe spesies is onderweg.
The diversity of South African spiders (Arachnida: Araneae : documenting a National Survey)
The South African National Survey of Arachnida (SANSA) was initiated in 1997 by the Agricultural Research Council (ARC), with the main aim of documenting the Arachnid fauna of South Africa at a national level. Through their Endangered Species Programme, the South African National Biodiversity Institute (SANBI) came on board for the project's second phase, called SANSA II, from 2006 to 2010, in partnership with the ARC. During this four-year project an attempt was made to consolidate all available data on South African spiders into one database. This data was used to determine the spatial coverage of the already available data, and to determine where 'gaps' in the data lie to identify priority areas for focused field work. Due to extensive collecting done by SANSA field work managers, specimen bycatches from other research projects, student projects, and through public participation in collecting specimens, more than 40 degree square grids were sampled in previously poorly sampled areas. This effort has provided valuable material that has improved our knowledge of the distribution of species, and provided specimens for future taxonomic studies. All this data was used to compile the First Atlas of the Spider Species of South Africa, including geo-referenced locality data, distribution maps and information on the level of endemicity of each species. Following SANSA II, 71 spider families, 471 genera and 2028 species are presently known in South Africa. The third phase of SANSA started in 2011 and several actions, such as Red Listing of species, a handbook series for all the biomes, publication of the atlas, and description of new species are underway.
'n Kritiese analise van toegepaste satellietbeeldinterpretasiemetodes en -prosedures soos uitgevoer deur beeldontleders in die Suid-Afrikaanse Nasionale Weermag : referaatopsomming
Author Ivan Henrico
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32 (2013) http://dx.doi.org/10.4102/satnt.v32i1.413
A critical analysis of methods and procedures applied to satellite image interpretation by image analysts in the South African National Defence Force
Inaccurate satellite image interpretation for military purposes may result in inadequate image intelligence and hamper the successful implementation of military operations. The image interpretation methods and procedures applied by South African National Defence Force (SANDF) image analysts raised the question whether image interpretation is correctly and accurately performed by SANDF image analysts. This study uses empirical research in the form of a field experiment to determine whether SANDF military analysts accurately execute military image interpretation.
Invloed van velkleur op laserpenetrasie : referaatopsomming
Authors: Aletta E. Karsten and Aletta E. Karsten
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32 (2013) http://dx.doi.org/10.4102/satnt.v32i1.414
Influence of skin colour on laser penetration
Laser applications in the medical fields are increasing. Most applications must penetrate through skin layers to reach the treatment area. In this study, a computer model is used to predict absorption in different skin phototypes. Results indicate that darker skin phototypes absorb three times more laser light at a wavelength of 632 nm than lighter skin phototypes.
Sintese van die C(1)-C(7)-gedeelte van die HO-FC1- en ISO-FC1-fumonisientoksiene : referaatopsomming
Author Chantal Hefti
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32 (2013) http://dx.doi.org/10.4102/satnt.v32i1.412
Synthesis of the C(1)-C(7) fragment of the HO-FC1 and ISO-FC1fumonisin toxins
HO-FC1 and ISO-FC1 are mycotoxins produced by Fusariumverticillioides. This study focuses on the stereoselective synthesis of C(1)-C(7) model compounds in order to establish the absolute configuration of the stereogenic centres present on the right-hand side of HO-FC1 and ISO-FC1 by comparison of the 13C NMR data.
Die kombinering van fisiologiese en tradisionele gebruikerstoetstegnieke om sosiale netwerke op verskeie tegnologiese platforms te evalueer : referaatopsomming
Authors: Francios Greeff and Lizette De Wet
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32 (2013) http://dx.doi.org/10.4102/satnt.v32i1.411
The combination of physiological and traditional user test techniques to evaluate social networks on various technological platforms
Combining physiological with traditional usability testing techniques to evaluate social networks on a variety of technological platforms. The aim is to compare the usage of a popular social network (Twitter) on three platforms, namely the computer, the cellphone and iPad. The usability (effectiveness, efficiency, user satisfaction) is measured by means of a heart-rate monitor, Emotiv technology, questionnaires and observations. The usability of these platforms is determined based on data analysis.
'n Webdiens vir tematiese kartering : referaatopsomming
Author Victoria Rautenbach
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 32 (2013) http://dx.doi.org/10.4102/satnt.v32i1.421
Web service for thematic cartography
The goal of the research is to evaluate proprietary software and solutions suggested by other researchers for the implementation of a mechanism for the production of thematic maps on desktop and web applications, as well as the thematic cartographic ability of standard web service implementations.