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Meer plekken om te verblijven in ZA: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie - Volume 29, Issue 2, June 2010
Volume 29, Issue 2, June 2010
Die gestremdheid van die Romeinse Keiser, Claudius (41-54 n.C.) s
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 29, pp 39 –47 (2010)
Claudius, die vierde keiser van die Romeinse Ryk, het lewenslank duidelike tekens van fisiese en sielkundig/emosionele gestremdhede getoon. Hy is deur verskeie historici as swaksinnig beskou, maar sy indrukwekkende rekord as skrywer van letterkundige en geskiedkundige werke en sy bekwame bestuur van die Ryksadministrasie toon dat dit hom nie ontbreek het aan intellektuele vermoëns nie. Sy reputasie as swaksinnige was vermoedelik gebaseer op sy defektiewe loopgang as gevolg van 'n swakheid van sy regterbeen en waarskynlik arm, 'n tremor van sy ledemate en onwillekeurige rukbewegings van sy kop, 'n spraakgebrek en sielkundig-emosionele labiliteit. In hierdie studie word die aard van Claudius se gestremdheid ondersoek. Daar word voorgestel dat die simptome-kompleks by serebrale verlamdheid pas, veral die ekstrapiramidale variant daarvan waar die intelligensie gewoonlik normaal of effe ingekort is.
Claudius, the handicapped Caesar (41-54 A.D.)
Claudius, fourth Caesar of the Roman Empire, proved himself an able administrator, but physically and emotionally handicapped from birth. His parents, members of the imperial family, considered him mentally deficient and he was isolated from the general public and put in the care of an uneducated tutor who firmly disciplined the youngster. The historians report that he had a weak constitution caused by frequent illness, and when he appeared in public he was muffled in a protective cloak. To avoid possible embarrassment the ceremony of the toga virilis, at approximately 14 years of age, was a secretive affair held at midnight and devoid of the traditional procession. His grandfather, Augustus Caesar, had some sympathy for the young lad, but did not consider him capable of managing any position of public office appropriate for his age and position. This would also be the approach of the succeeding emperor, Tiberius. Claudius spent the first four decades of his life in relative idleness, isolated from his family and upper class Romans, consorting with the lower classes, playing dice and revelling in excessive eating and drinking. He did, however, also involve himself seriously in a study of the sciences, literature, Greek and history - his role model in the latter being Livy. During his life time he published quite extensively, including dramas, an autobiography, a work in defence of Cicero, histories of Rome, Carthage and Etruria, and a book on dice. His first public office (besides an augurship under Augustus) was at the age of 47 years when the new emperor, Gaius (Caligula) made him a consul for two months. The Knights and a section of Senate now warmed towards Claudius, but Gaius and the majority of aristocratic Romans still despised him as dull-witted. After the assassination of Gaius, the Praetorian Guard in an extraordinary step, proclaimed a protesting Claudius (50 years old) as emperor, and convinced an astounded Senate to endorse this action. In spite of having had no significant preparation for the task, Claudius proved a most sensible and effective manager, improving the effectivity of Senate, putting the legal system on a sound footing, enlarging the borders of the Empire (including the conquest of England), extending citizenship to some of the provincials, foreigners and freedmen. Sensible building programs were initiated as well as the upgrading of roads and communication systems and the ensuring of an efficient food supply to Rome. Grand and regular gladiatorial games and other forms of public entertainment endeared him to the people. But he was also periodically responsible for mismanagement, corruption and brutality; much of this was subsequently blamed on the inordinate influence of people near him, and his trusted freedmen and wives in particular. The last two of his six wives (Messalina and Agrippina) were particularly guilty, and his death of poisoning at the age of 64 years (54 A.D.) was engineered by Agrippina. Through his life Claudius showed evidence of significant physical and psychological/emotional impediments. By many he was considered mentally deficient, but his impressive record as student of literature and history, and his administrative skill as emperor are ample evidence of his intellectual abilities. Physical abnormalities included an ungainly gait due to weakness of his right leg and probably arm. He had a tremor of the limbs and involuntary shaking of the head. He spoke indistinctly in a coarse, stuttering way, his mouth often drooled, his nose tended to run, and he had an uncouth laugh. He was emotionally labile, and when upset the above symptoms worsened and he became prone to irresponsible actions. We suggest that this symptom complex fits in with the diagnosis of cerebral palsy, and probably its extrapyramidal variant, although one-sided weakness suggests an additional component of hemiplegic paresis.
Authors: Tilla Fick and Chris Swanepoel
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 29, pp 48 –65 (2010)
Vir Afrikaans is outomatiese rekenaarmatige woordafbreking 'n probleem wat aandag vereis, aangesien foute steeds dikwels in gedrukte teks voorkom. As eerste stap in hierdie taak is dit noodsaaklik om woorde outomaties in lettergrepe te verdeel. Aangesien nuwe woorde voortdurend geskep word deur woorde aanmekaar te skryf, werk bestaande tegnieke wat vir Engels ontwikkel is, nie goed in Afrikaans nie. Dit is nodig om 'n "intelligente" tegniek vir lettergreepverdeling te ontwikkel. As eerste benadering beskou ons slegs die ortografiese inligting van woorde sonder om sintaksis of morfologie in ag te neem. Dit laat ons toe om masjienleertegnieke soos kunsmatige neurale netwerke en beslissingsbome wat bekend is vir hul patroonherkenningsvermoë vir die taak te oorweeg. Hierdie tegnieke word met geïsoleerde afrigtingspare bestaande uit invoerpatrone en ooreenstemmende uitvoere (of teikens) afgerig. In hierdie artikel verskaf ons die motivering vir die studie en bespreek die proses wat gevolg is om data vir die afrigting van masjienleertegnieke te genereer. Ons bespreek ook probleemareas soos onreëlmatige woordafbreking en verskaf 'n ontleding van letterkombinasies (of letterpatrone) in woorde met en sonder lettergreepverdeling.
Die effek van statistiese analitiese metingsvariasies op aanlegkontroleparameters en koste in sementvervaardiging - 'n gevallestudie
Authors: Herman Potgieter and Anne Love
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 29, pp 66 –76 (2010)
Biodiversiteit in landbougronde, volhoubare plantproduksie en die beheer van plantpatogene : navorsings- en oorsigsartikels
Authors: Koot Reinecke and Sophie Reinecke
Source: Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 29, pp 77 –96 (2010)
Grond is 'n baie heterogene substraat wat 'n omgewingsmatriks daarstel wat in ruimte en oor tyd kan varieer wat betref pH, organiese koolstof, verspreiding van partikelgrootttes en voginoud. Ook chemiese, fisiese en biologiese faktore tree op en grond bevat 'n enorme verskeidenheid van grondlewende ongewerwelde diere en mikrobes wat met mekaar en met die omgewing in wisselwerking verkeer en sodoende plantproduktiwiteit direk en indirek beïnvloed. 'n Oorsig van die meer onlangse wetenskaplike literatuur oor die rol van grondbiodiversiteit dui op die belangrike rol van grondlewende invertebrate, veral erdwurms, om grondeienskappe en ook grondgedraagde patogene te beïnvloed. Erdwurms het in baie gronde 'n kritieke funksie in die regulering van sleutelprosesse wat impakteer op plantproduktiwiteit en die gelyktydige eliminering of teenwerking van grondgedraagde siektes. Die doel van hierdie oorsig is eerstens om by te dra tot die opheldering van die rol wat grondbiodiversiteit in die algemeen speel en om meer in die besonder te fokus op die invloed wat erdwurms het op plantpatogene en parasiete. Getuienis word verskaf dat hierdie diere se aktiwiteit plantproduktiwiteit kan beïnvloed en patogene kan onderdruk. As die aard en omvang van die rol van grondorganismes beter bekend is en dit bevestig kan word dat hulle plantproduktiwiteit bevorder, soos wat baie grondbioloë meen, is die volgende logiese stap om die kennis van hulle ekologie uit te brei en te benut. Deur gunstige omgewingstoestande te skep en te bestuur kan hulle oorlewing en aktiwiteit in landbougronde verseker word. 'n Oorsig word ook verskaf van landboupraktyke wat nuttige grondorganismes bevoordeel. Die oordeelkundige implementering hiervan kan die dienste wat hierdie grondorganismes lewer, beskikbaar stel om agro-ekostelsels te verbeter en volhoubaar te maak. Om hierdie ideaal te kan bereik, moet 'n beter begrip van hierdie organismes se voorkeure, wisselwerkings en verdraagsaamheidsomvange verkry word. Eers dan kan metodes om omgewingstoestande te manipuleer meer algemeen toegepas word om die voordele wat die organismes bied ten volle te benut.