Volume 26, Issue 1, 2007
Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie - Volume 26, Issue 1, March 2007
Volume 26, Issue 1, March 2007
Hoekom skrik 'n mens vir koue pampoen? : research and review article
Authors: Annie Panzer and Stephen Lambert
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 26, pp 1 –7 (2007)
'n Veralgemeende Sylvester-Gallai Stelling : research and review article
Authors: L.M. Pretorius and K.J. Swanepoel
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 26, pp 8 –13 (2007)
We give an algorithmic proof for the contrapositive of the following theorem that has recently been proved by the authors:
Let S be a finite set of points in the plane, with each point coloured red, blue or with both colours. Suppose that for any two distinct points A and B in S sharing a colour k, there is a third point in S which has (inter alia) the colour different from k and is collinear with A and B. Then all the points in S are collinear.
This theorem is a generalization of both the Sylvester-Gallai Theorem and the Motzkin-Rabin Theorem.
Ons gee 'n algoritmiese bewys vir die kontrapositief van die volgende stelling wat onlangs deur die outeurs bewys is:
Laat S 'n eindige versameling van punte in die vlak wees, met elke punt rooi, blou of metbeide kleure gekleur. Veronderstel dat daar vir enige twee verskillende punte A en B in S wat 'n kleur k deel, 'n derde punt in S is wat (o.a.) die kleur anders as k het en wat saamlynig met A en B is. Dan is al die punte in S saamlynig.
Hierdie stelling is 'n gemeenskaplike veralgemening van die Sylvester-Gallai Stelling en die Motzkin-Rabin Stelling.
Geneesmiddels en die gebruik daarvan in die Grieks- Romeinse era : research and review article
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 26, pp 14 –25 (2007)
Standaard residensiële vloedskadefunksies vir Suid- Afrikaanse toestande : research and review article
Authors: G. Du T. De Villiers and M.F. Viljoen
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 26, pp 26 –36 (2007)
Ramprisikobestuur is 'n integrale deel van 'n wetenskaplike benadering om rampe te bestuur. Dit verwys na geïntegreerde, multisektorale, multi-dissiplinêre, organisatoriese en operasionele beplanningsprosesse en vaardighede om rampe te versag. Toepassing van die benadering vereis dat ramprisiko-analise onderneem moet word, vir welke doel vloedskadefunksie benodig word in geval van vloedrampe. 'n Vloedskadefunksie verbeeld wiskundig, tabellaries of grafies die verwantskap tussen vloedkenmerke soos diepte en / of vloeisnelheid van vloedwater en die skade aan 'n spesifieke grondgebruik. Navorsing wat aan die Universiteit van die Vrystaat gedoen is, het die waarde van standaard residensiële vloedskadefunksies beklemtoon, asook die noodsaaklikheid dat die inligting daarin vervat bygehou moet word, om te verseker dat dit eietydse gebruikswaarde behou. Hierdie artikel fokus op die bywerking van standaard vloedskadefunksies.
Standard residential flood damage functions for South African conditions
Disaster risk management is an integral part of a scientific approach to disaster management. It refers to integrated, multi-sectoral, multi-disciplinary, organizational and operational planning processes and skills to mitigate disasters. Application of the approach necessitates disaster risk analysis, requiring flood damage functions in the case of floods. A flood damage function can be described mathematically, tabularly or graphically and refers to the relationship between flood characteristics like depth and / or speed of floodwater and flood damage to a specific land use type. Research conducted at the University of the Free State indicated the value of standard residential flood damage functions and the necessity for periodic updating to secure contemporary relevance. This article focuses on updating of the latter.
The article starts with an introduction to put the development, use and maintenance of standard residential flood damage functions in context with regard to the latest views on disaster risk management, risk assessment, disaster management legislation in South Africa and a computer model TEWA, in which the flood damage functions are used. Aspects that can affect flood damage are briefly discussed, followed by sections on the development and upgrading of structural flood damage functions for formal housing as well as functions for determining damage to housing contents. The development of residential flood damage functions that can be applied nationally forms the main part of the paper and is followed by a brief summary statement.
Die Grenzen der Logik übersteigen : Zum Unterschiedzwischen Widerspruch und Antinomie : research and review article
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 26, pp 37 –61 (2007)
Kijken Zuid Afrikaanse en Nederlandse biologiestudenten anders tegen natuur aan? : research paper
Author Herman Eijsackers
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 26, pp 63 –67 (2007)
Lecturing on nature conservancy at Amsterdam and Stellenbosch offered the possibility to investigate if biology students in different countries and cultures have different views on nature and nature conservation. The results of a short questionnaire show a similar broad attitude towards nature and nature conservation in both university student groups. They all want action with respect to global problems (global warming/climate change). But next to that there are also typical national problems like Dutch fisheries discussions and South African eradication of alien species and more attention for water and soil pollution. Moreover, there was a shared interest in more social aspects of nature conservation (education, awareness / consciousness, population growth). A major bias is that the answers express the views of well educated, white people. Extension to young people of other cultural background is needed. So feel free to ask for the questionnaire.
Geselekteerde referaatopsommings - S.A. Akademie : Jaarkongres vir Biologiese Wetenskappe (Universiteit van Vrystaat, 8 September 2006) : papers
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 26, pp 69 –95 (2007)
Die groot avontuur - wondere van lewe op aarde, Leon Rousseau : book review
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 26, pp 97 –99 (2007)
Standpunt van IAP (Interacademy Panel) oor evolusie : statement
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 26, pp 101 –103 (2007)