South African Journal of Science and Technology最新文献

{"title":"Inhibisie van osteoklastvorming en beenresorpsie deur poli-onversadigde vetsure in RAW 264.7 muismonosiete","authors":"J. Boeyens, Wei-Hang Chua, M. Kruger, A. Joubert, M. Coetzee","doi":"10.4102/SATNT.V31I1.318","DOIUrl":"https://doi.org/10.4102/SATNT.V31I1.318","url":null,"abstract":"Beenhermodellering in volwassenes is ‘n fisiologiese proses wat die sintese van beenmatriks deur osteoblaste en die resorpsie (afbraak) van been deur osteoklaste behels. Osteoklaste ontstaan deur die samesmelting van hematopoietiese selle van monosiet-makrofaagafkoms en speel ‘n deurslaggewende rol in beenhermodellering.","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":"31 1","pages":"1"},"PeriodicalIF":0.0,"publicationDate":"2012-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4102/SATNT.V31I1.318","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70515970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Die invloed van ‘n intensiewe opleidingsprogram op die Kardio Stres-indeks","authors":"T. Claassen, E. Henning, M. Kleynhans, C. Grobbelaar, P. J. D. Toit","doi":"10.4102/satnt.v31i1.283","DOIUrl":"https://doi.org/10.4102/satnt.v31i1.283","url":null,"abstract":"Mense ondervind baie stressors in hul alledaagse lewe, wat ‘n groot uitwerking het op daaglikse funksionering. Kardio Stres-indeks (KSI) is ‘n nie-indringende mate van die stres wat die hart ervaar. KSI (uitgedruk as ‘n persentasie) berekeninge word gebaseer op die duur van die QRS kompleks, hart tempo, ritme en standaardafwyking van die RR-interval (RRSD) spesifieke parameters.","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2012-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4102/satnt.v31i1.283","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70515369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molecular crosstalk between apoptosis and autophagy induced by a 2-methoxyestradiol analogue (C19) in HeLa cells","authors":"A. Theron, M. Visagie, T. Mqoco, A. Stander, R. Prudent, L. Lafanechère, A. Joubert","doi":"10.4102/SATNT.V31I1.315","DOIUrl":"https://doi.org/10.4102/SATNT.V31I1.315","url":null,"abstract":"Servikale kanker is gerapporteer deur die Wereld Gesondheids Organisasie as die mees algemene tipe kanker wat vroue in armer sosio-ekonomiese lande affekteer.","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":"31 1","pages":"1"},"PeriodicalIF":0.0,"publicationDate":"2012-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4102/SATNT.V31I1.315","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70515800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Partikel-Swerm-Optimering (PSO) toetsbank vir globale wiskundige minimeringsprobleme","authors":"Ludwig de Bruin, E. M. Ehlers","doi":"10.4102/SATNT.V30I1.102","DOIUrl":"https://doi.org/10.4102/SATNT.V30I1.102","url":null,"abstract":"’n Partikel-Swerm-Optimering (PSO) toetsbank is ontwikkel om verskillende algoritmes te vergelyk. Die toetsbank stel ons in staat om te bepaal watter tipe algoritmes verskillende probleme die beste oplos. Hierdie referaat sal eerstens wiskundige optimering definieer, kortliks PSO verduidelik, die toetsbankstelsel opsom en laastens na resultate verwys.","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":"30 1","pages":"1"},"PeriodicalIF":0.0,"publicationDate":"2011-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4102/SATNT.V30I1.102","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70514299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Voorwerp-rekonstruksie vanaf verskeie onbeheerde sigpunte","authors":"D. Joubert","doi":"10.4102/SATNT.V30I1.262","DOIUrl":"https://doi.org/10.4102/SATNT.V30I1.262","url":null,"abstract":"CITATION: Joubert, D. 2011. Voorwerp-rekonstruksie vanaf verskeie onbeheerde sigpunte. Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie, 30(1), Art. \u0000#262, doi:10.4102/satnt.v30i1.262.","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2011-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70514413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental measurement and modelling of vapour-liquid equilibrium data for the C2F4-C3F6-s-C4F8 system","authors":"F. Conradie","doi":"10.4102/SATNT.V30I1.99","DOIUrl":"https://doi.org/10.4102/SATNT.V30I1.99","url":null,"abstract":"The following members formed part of the committee that was responsible for arranging the symposium: Mr. R. Pretorius (Department of Geography, University of South-Africa), Dr E. Snyders (NECSA), Dr M. Landman (Department of Chemistry, University of Pretoria) and Dr W. Meyer (Department of Physics, University of Pretoria). Experimental measurement and modelling of vapour-liquid equilibrium data for the C2F4-C3F6-s-C4F8 system The vapour-liquid equilibrium data for the C2F4-C3F6-s-C4F8 system are presented. Each binary system was evaluated at three isotherms. The experimental data will be correlated to the Peng-Robinson equation of state, incorporating the Mathias-Copeman alpha function, with the Wong-Sandler mixing rule utilising the NRTL activity coefficient model. Page 1 of 1","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":"30 1","pages":"1"},"PeriodicalIF":0.0,"publicationDate":"2011-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4102/SATNT.V30I1.99","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70514476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From the Fermat points to the De Villiers3 points of a triangle","authors":"M. Villiers","doi":"10.4102/satnt.v29i3.16","DOIUrl":"https://doi.org/10.4102/satnt.v29i3.16","url":null,"abstract":"The article starts with a problem of finding a point that minimizes the sum of the distances to the vertices of an acute-angled triangle, a problem originally posed by Fermat in the 1600’s, and apparently first solved by\u0000 the Italian mathematician and scientist Evangelista Torricelli. This point of optimization is therefore usually called the inner Fermat or Fermat-Torricelli point of a triangle. The transformation proof presented in the article was more recently\u0000 invented in 1929 by the German mathematician J. Hoffman. After reviewing the centroid and medians of a triangle, these are generalized to Ceva’s theorem, which is then used to prove the following generalization of the Fermat-Torricelli point from\u0000 [3]: “If triangles DBA, ECB and FAC are constructed outwardly (or inwardly) on the sides of any ∆ABC so that ∠DAB =∠CAF , ∠ DBA = ∠ CBE and ∠ ECB = ∠ ACF then DC, EA and FB are concurrent.”However, this generalization is not new, and the earliest\u0000 proof the author could trace is from 1936 by W. Hoffer in [1], though the presented proof is distinctly different. Of practical relevance is the fact that this Fermat-Torricelli generalization can be used to solve a “weighted” airport problem,\u0000 for example, when the populations in the three cities are of different size. The author was also contacted via e-mail in July 2008 by Stephen Doro from the College of Physicians and Surgeons, Columbia University, USA, who was considering its\u0000 possible application in the branching of larger arteries and veins in the human body into smaller and smaller ones. On the basis of an often-observed (but not generally true) duality between circumcentres and in centres, it was conjectured in\u0000 1996 [see 4] that the following might be true from a similar result for circumcentres (Kosnita’s theorem), namely: The lines joining the vertices A, B, and C of a given triangle ABC with the incentres of the triangles BCO, CAO, and ABO (O is the\u0000 incentre of ∆ABC), respectively, are concurrent (in what is now called the inner De Villiers point). Investigation on the dynamic geometry program Sketchpad quickly confi rmed that the conjecture was indeed true. (For an interactive sketch online,\u0000 see [7]). Using the aforementioned generalization of the Fermat-Torricelli point, it was now also very easy to prove this result. The outer De Villiers point is similarly obtained when the excircles are constructed for a given triangle ABC, in\u0000 which case the lines joining the vertices A, B, and C of a given triangle ABC with the incentres of the triangles BCI1, CAI2, and ABI3 (Ii are the excentres of ∆ABC), are concurrent. The proof follows similarly from the Fermat-Torricelli\u0000 generalization.","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2010-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70513818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The oxygen consumption rates of different life stages of the endoparasitic nematode","authors":"W. V. Aardt, Donovan P. Loots, S. Steenkamp","doi":"10.4102/SATNT.V29I1.4","DOIUrl":"https://doi.org/10.4102/SATNT.V29I1.4","url":null,"abstract":"Die suurstofverbruikskoers (VO2) van die endoparasitiese nematode Pratylenchus zeae versamel vanaf mieliewortelkulture is gemeet met behulp van ’n Cartesiese duiker. Die metings met die duiker wat uit Perspex gemasjineer is, berus in beginsel op manometriese veranderinge van die duiker in ’n flottasiebuis van ’n manometeropstelling.Die gemiddelde VO2van 10 metings per lewenstadium, uitgedruk in nanoliters per uur per lewenstadium van nie-anhidrobiote (eiers: 7.96; jeugstadia: 6.13; volwassenes: 26.04) is vergelyk met die van post-anhidrobiote, 12 uur na herstel uit anhidrobiose. Die gemiddelde VO2van die post-anhidrobiote vir die drie lewenstadia (eiers: 19.34; jeugstadia: 14.17; volwassenes: 32.86) is statisties betekenisvol hoer in vergelyking met die van nie-anhidrobiote. Die redes vir die verskil in VO2 waardes word bespreek. Die VO2 is ook uitgedruk in nanoliter per uur per mikrogram volwasse nematode na toepassing van ’n vergelyking verkry uit die literatuur. Dit is gevind dat die suurstofverbruik per een gram P. zeae 503 keer meer is as die suurstofverbruik per een gram soogdier die grootte van ’n volwasse bees.","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":"29 1","pages":"20-29"},"PeriodicalIF":0.0,"publicationDate":"2010-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70514112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Is studente wat in 'n uitkomsgerigte onderrigbenadering opgelei is, gereed vir universiteitswiskunde? : navorsings- en oorsigartikel","authors":"J. Engelbrecht, Ansie Harding, Patrick Phiri","doi":"10.4102/satnt.v28i4.67","DOIUrl":"https://doi.org/10.4102/satnt.v28i4.67","url":null,"abstract":"Uitkomsgerigte onderrig (UGO) het 'n groei- en hersieningsfase beleef en is vir die afsienbare toekoms hier om te bly. Die 2009-inname van studente op universiteit is die eerste matrikulante wat slegs binne die nuwe bedeling onderrig ontvang het. Hierdie matrikulante se graad 12-uitslae is deur onnatuurlik hoe punte in wiskunde gekenmerk. Die vraag wat gevra word, is hoe die 2009-inname van studente in wiskunde op universiteit vaar wat prestasie, algemene vaardighede, wiskundige vaardighede en inhoudverwante vaardighede betref. Dit blyk dat alhoewel hierdie studente beter toegerus is wat persoonlike eienskappe soos selfvertroue betref, hulle in baie gevalle swakker daaraan toe is wat wiskundige en inhoudverwante vaardighede betref. Voorstelle word gemaak om die oorgang van sekondere na tersiere wiskunde gladder te maak.\u0000Are students who have been educated in an outcomes-based approach prepared for university mathematics?\u0000Following the political changes of 1994 in South Africa, the decision was taken to replace the traditional skills-based education system at primary and secondary school level (Grades 1 - 12) with an outcomes-based education system (OBE). The OBE approach, referred to as Curriculum 2005, was introduced into schools in 1998. The implementation of the OBE system did not occur without problems, giving rise to revised initiatives and a fair amount of criticism. The 2009 intake of students at universities is the first group of students that had been subjected to the OBE approach for their entire school career. This is also the first group of students for whom some form of mathematics was compulsory up to Grade 12 level in the form of mathematics or mathematical literacy. These students were characterised by the fact that their mathematics marks for Grade 12 were exceptionally high and that many more students qualified for university entrance.\u0000This article reports on the impact of this new education system on the mathematics preparedness of students entering university. The study involves an empirical analysis of the students in the first-year mathematics course for engineering students at the University of Pretoria as well as an analysis of a questionnaire completed by experienced lecturers at this university.\u0000The question addressed in this article is how the 2009 intake of students cope with mathematics at university level with regard to\u0000Performance\u0000General attributes\u0000Mathematical attributes\u0000Content-related attributes\u0000Results indicate a decrease in mathematics performance of these students at university level and that the inflated matric marks result in unjustified expectations. However, it is not unusual for marks to decrease from school to university and there is still too little evidence for serious concern.\u0000The study also indicates that these students seem to be better equipped with regard to personal attributes such as self-confidence and the will to work. However, in many instances, their general mathematical attributes such as ","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":"28 1","pages":"288-302"},"PeriodicalIF":0.0,"publicationDate":"2009-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70513800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mathematical modelling: From school to university","authors":"A. Harding","doi":"10.4102/SATNT.V28I4.71","DOIUrl":"https://doi.org/10.4102/SATNT.V28I4.71","url":null,"abstract":"The outcomes based education (OBE) system is characterised by controversy and the 2008 matric results that rendered admission to an unusually large number of students did nothing to silence critics. The first\u0000 students who completed their full cycle of school education in the OBE system entered universities in 2009 and their preparedness for university mathematics as well as their performance at university level are important as indicaters for\u0000 estimating the success or otherwise of the OBE system. In a previous study student performance in mathematics admission tests for 2005-2007 was investigated and it was found that students who had had partial exposure to OBE performed worse than\u0000 had been the case with their predecessors in the categories of modelling and ratio problems. As a result, this study was conducted to investigate how the 2009 intake of students performed in a modelling course at university level. A report is\u0000 presented which deals with student performance in the course, problems experienced, the effect of remedial intervention on performance and whether students of the OBE system are adequately prepared for mathematical modelling at university level.\u0000 This study focuses on performance in a first year course in mathematical modelling at the University of Pretoria. The course is problem based and is technology intensive, requiring use of the software package Matlab. For investigative purposes the\u0000 papers of semester tests 1 and 2 of 2005 were used unchanged for tests in 2009. Students of 2009 did not have access to the 2005 papers and the same lecturer taught students of both groups. The lecturer also noted personal experiences in respect\u0000 of students and was able to draw reasonable comparisons between the 2009 students and previous groups because of her years of involvement with the course. The entrance requirement of 60% for matric mathematics in 2005 was increased to 70% in\u0000 2009. Results indicate that the pass percentage decreased in both semester tests from 2005 to 2009. The percentage of students with less than 40% also increased in both semester tests from 2005 to 2009. A surprising observation was that the\u0000 percentage of students who excelled increased remarkably from 2005 to 2009 in both semester tests. Extra assistance was requested by students after the first semester test in 2009 and resulted in a week of intervention during which revision and\u0000 extra problems were attended to. The results of the two semester tests of 2009 did not live up to expectations of the matric results of the group . Despite the exceptional matric results, performance in the modelling course was decidely poorer.\u0000 Results indicate that most students were not adequately prepared for the course – as could be predicted from the previous study. The 2009 group was characterised by two aspects – excellent matric results on the one hand and full school education\u0000 within the OBE system on the other. It is difficult to distinguish between the influence of the two","PeriodicalId":30428,"journal":{"name":"South African Journal of Science and Technology","volume":"28 1","pages":"355-365"},"PeriodicalIF":0.0,"publicationDate":"2009-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70513978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}