869 research outputs found
Kaart van bevolkingsverspreiding van die Unie van Suid-Afrika 1951 = Population distribution map of the Union of South Africa 1951 /
No full textSponsored and organized by Natural Resources Development Council.; Financed by National Council for Social Research.; Project proposed and directed by J.H. Moolman.; "The 1946 Census dates were used but the map was later revised to include the Census date of 1951."; Prepared for reproduction by the Trigonometrical Survey Office, 1954.; Booklet title: Verklaring van die kaart van bevolkingsverspreiding van die Unie van Suid-Afrika 1951 = Explanation of the population distribution map of the Union of South Africa, 1951 / prepared by J.H. Moolman.; Also available online http://nla.gov.au/nla.map-vn6813382.Population distribution map of the Union of South Africa, 195
Postmodernistiese vertelstrategieë in Nag van die clown van Abraham H. de Vries
No full textThis thesis locates Abraham H. de Vries's Nag van ale Clown witbin the self-conscious South African socio-literary climate of the eighties and analyses postmodernist narrative strategies in five stories. Surveying the debate on postmodernism, this study describes postmodernism as a nomadic, inherently contradictory and mutually informing palimpsest of texts and views the De Vries text as a problematized inscribing of subjectivity into history.Hierdie proefskrif situeer Nag van die Clown (1989) van Abraham H. de Vries binne die selfbewuste sosioliterere klimaat van die Suid-Afrika van die dekade tagtig en ontleed postmodernistiese vertelstrategiee in vyf verhale uit die bundel. Die studie bied 'n oorsig oor die debat rondom die postmodernisme as nomadiese, weersprekende en wedersyds voedende palimpses tekste en beskou die De Vries-teks as 'n problematiserende inskryf van subjektiwiteit in die geskiedenis
Detecting fraud in cellular telephone networks
No full textThesis (MSc)--University of Stellenbosch, 2005.ENGLISH ABSTRACT: Cellular network operators globally loose between 3% and 5% of their annual revenue to
telecommunications fraud. Hence it is of great importance that fraud management systems
are implemented to detect, alarm, and shut down fraud within minutes, minimising
revenue loss. Modern proprietary fraud management systems employ (i) classification
methods, most often artificial neural networks learning from classified call data records to
classify new call data records as fraudulent or legitimate, (ii) statistical methods building
subscriber behaviour profiles based on the subscriber’s usage in the cellular network and
detecting sudden changes in behaviour, and (iii) rules and threshold values defined by
fraud analysts, utilising their knowledge of valid fraud cases and the false alarm rate as
guidance. The purpose of this thesis is to establish a context for and evaluate the performance
of well-known data mining techniques that may be incorporated in the fraud
detection process.
Firstly, a theoretical background of various well-known data mining techniques is
provided and a number of seminal articles on fraud detection, which influenced this thesis,
are summarised. The cellular telecommunications industry is introduced, including a brief
discussion of the types of fraud experienced by South African cellular network operators.
Secondly, the data collection process and the characteristics of the collected data are
discussed. Different data mining techniques are applied to the collected data, demonstrating
how user behaviour profiles may be built and how fraud may be predicted. An
appraisal of the performances and appropriateness of the different data mining techniques
is given in the context of the fraud detection process.
Finally, an indication of further work is provided in the conclusion to this thesis, in
the form of a number of recommendations for possible adaptations of the fraud detection
methods, and improvements thereof. A combination of data mining techniques that may
be used to build a comprehensive fraud detection model is also suggested.AFRIKAANSE OPSOMMING: Sellulêre netwerk operateurs verloor wêreldwyd tussen 3% en 5% van hul jaarlikse inkomste
as gevolg van telekommunikasie bedrog. Dit is dus van die uiterse belang dat bedrog
bestuurstelsels geïmplimenteer word om bedrog op te spoor, alarms te genereer, en bedrog
binne minute te staak om verlies aan inkomste tot ’n minimum te beperk. Moderne
gepatenteerde bedrog bestuurstelsels maak gebruik van (i) klassifikasie metodes, mees
dikwels kunsmatige neurale netwerke wat leer vanaf geklassifiseerde oproep rekords en
gebruik word om nuwe oproep rekords as bedrog-draend of nie bedrog-draend te klassifiseer,
(ii) statistiese metodes wat gedragsprofiele van ’n intekenaar bou, gebaseer op die
intekenaar se gedrag in die sellulêre netwerk, en skielike verandering in gedrag opspoor,
en (iii) reëls en drempelwaardes wat deur bedrog analiste daar gestel word, deur gebruik
te maak van hulle ondervinding met geldige gevalle van bedrog en die koers waarteen
vals alarms gegenereer word. Die doel van hierdie tesis is om ’n konteks te bepaal vir
en die werksverrigting te evalueer van bekende data ontginningstegnieke wat in bedrog
opsporingstelsels gebruik kan word.
Eerstens word ’n teoretiese agtergrond vir ’n aantal bekende data ontginningstegnieke
voorsien en ’n aantal gedagteryke artikels wat oor bedrog opsporing handel en wat hierdie
tesis beïnvloed het, opgesom. Die sellulêre telekommunikasie industrie word bekend gestel,
insluitend ’n kort bespreking oor die tipes bedrog wat deur Suid-Afrikaanse sellulˆere
telekommunikasie netwerk operateurs ondervind word.
Tweedens word die data versamelingsproses en die eienskappe van die versamelde
data bespreek. Verskillende data ontginningstegnieke word vervolgens toegepas op die
versamelde data om te demonstreer hoe gedragsprofiele van gebruikers gebou kan word
en hoe bedrog voorspel kan word. Die werksverrigting en gepastheid van die verskillende
data ontginningstegnieke word bespreek in die konteks van die bedrog opsporingsproses.
Laastens word ’n aanduiding van verdere werk in die gevolgtrekking tot hierdie tesis
verskaf, en wel in die vorm van ’n aantal aanbevelings oor moontlike aanpassings en verbeterings
van die bedrog opsporingsmetodes wat beskou en toegepas is. ’n Omvattende
bedrog opsporingsmodel wat gebruik maak van ’n kombinasie van data ontginningstegnieke
word ook voorgestel
Does enhanced regulation improve EIA report quality? Lessons from South Africa
No full textRecently, various EIA systems have been subjected to system review processes with a view to improve performance. Many of these reviews resulted in some form of legislative reform. The South African Environmental Impact Assessment (EIA) regulations were modified in 2006 with the express intent to improve EIA effectiveness. In order to evaluate to what extent the desired outcome was achieved, the quality of EIA reports produced under the 2006 regulations was investigated for comparative analysis with the preceding regime. A sample of EIA reports from the two legislative regimes was reviewed using an adapted version of a well established method known colloquially as the "Lee and Colley" review package. Despite some improvements in certain aspects, overall report quality has decreased slightly from the 1997 EIA regime. It therefore appears that the modifications to the regulations, often heralded as the solution to improvements in performance have not resulted in improved quality of EIA reports
Biological synthesis of gold nanoparticles by Thermus scotoductus SA-01
No full textEnglish: The usual strategy to prepare gold nanoparticles involves the reduction of a gold salt in solution by various reducing agents in the presence of a stabilizer. These particles are mostly spherical with poor monodispersity. An alternative means is to use biological material to mediate particle synthesis. Microorganisms such as fungi have demonstrated the ability to produce nanoparticles of different shapes and sizes extending beyond the scope of chemical means, and the microbial interaction with metals also supply eco-friendly methods for nanoparticle production. It has been hypothesized that the proteins involved in nanoparticle synthesis require a co-factor such as NADH / NADPH, as previous studies have indicated that NADH- and NADPH-dependent enzymes are important factors in the biosynthesis of metal nanoparticles. Thermus scotoductus SA-01, a thermophilic bacterium, isolated from an AngloGold Ashanti mine near Carletonville, Republic of South Africa, was used for purification of a gold(III) reducing and nanoparticle synthesizing protein. This bacterium has the ability to produce gold nanoparticles, and more than one pathway can be followed to produce these particles. A protein was purified to homogeneity by using a combination of several liquid chromatography resins. The N-terminal sequence was obtained by using automated Edman degradation. The protein purified is not a classical oxido-reductase and was identified as an ABC transporter peptide-binding protein (~70kDa). This discovery shows that gold nanoparticles can be produced by proteins other than oxidoreductases. The interaction of the protein extracted and purified from Thermus scotoductus SA-01, as well as the recombinant proteins, with liquid gold under varying physico-chemical conditions have been studied using TEM, EDS, and by measuring the plasmon resonance band, to illustrate the effect on particle morphology and to elucidate the protein mechanism. The size and the shape of particles could, to an extent, be manipulated by controlling the environmental parameters. The purified protein as well as the recombinant proteins was only able to produce nanoparticles in the presence of sodium dithionite and it is thus hypothesized that the donation of electrons via the disulphide bridge in the protein is involved in the reduction of the gold ions. Even though the recombinant proteins had the ability toproduce nanoparticles they were not as efficient as the native protein, but when the optimum parameters for the recombinant proteins are established they could be used in the upscale production of gold nanoparticles or gold nanosheets.Afrikaans: Die algemeenste strategie vir die voorbereiding van nanopartikels behels die reduksie van ʼn
opgeloste goudsout deur verskeie reduseermiddels in die teenwoordigheid van ʼn
stabiliseerder. Hierdie partikels is meestal sferies met lae monodispersiteit. ʼn Alternatiewe
manier om partikels te vorm is om biologiese materiaal te gebruik. Mikroörganismes, soos
fungi, beskik oor die vermoeë om nanopartikels van verskillende vorme en groottes te
produseer, wat ʼn verbetering is op die gebruik van chemiese metodes. Hierdie mikrobiese
interaksie met metale verskaf ook ʼn omgewingsvriendelike metode vir die produksie van
nanopartikels.
Vorige studies het getoon dat NADH- en NAD(P)H- afhanklike ensieme belangrike
faktore is in die biosintese van metaal nanopartikels. Dit het gelei tot die hipotese dat
proteïene wat betrokke is by goud nanopartikel sintese ʼn kofaktor soos NADH / NAH(P)H
benodig.
ʼn Proteïen wat in staat is om goud te reduseer en nanopartikels te vorm, is gesuiwer
vanuit die termofiele bacterium, Thermus scotoductus SA-01. Hierdie bakterium was
geïsoleer vanuit ʼn AngloGold Ashanti myn naby Carletonville, Republiek van Suid-Afrika en
het die vermoeë om goud nanopartikels te produseer deur meer as een biologiese weg te volg.
Die proteïen is gesuiwer deur gebruik te maak van ʼn kombinasie van verskeie vloeistofchromatografie
harse. Die N-terminale proteïen volgorde is verkry deur gebruik te maak van
Edman degradering. Die gesuiwerde proteïen is nie ʼn klasieke oksido-reduktases nie, maar is
geïdentifiseer as ʼn ABC transporter-peptied-bindings proteïen (~70kDa). Hierdie ontdekking
wys dat goud nanopartikels geproduseer kan word deur ander proteïene as oksido-reduktases.
TEM, EDS en die meeting van die plasmon resonans band is gebruik om die effek van
variërende fisiese-chemiese kondisies op partikel morfologie te toon en om die proteïen
meganisme op te klaar. Vir die doel is die gesuiwerde proteïen vanuit Thermus scotoductus
SA-01 asook rekombinante proteïene gebruik.
Die grootte en vorm van die partikels kon tot ʼn mate gemanipuleer word deur
omgewingsfaktore te beheer. Die gesuiwerde proteïen asook die rekombinante proteïene kon
slegs nanopartikels produseer in die teenwoordigheid van natriumdithionaat en ʼn hipotese is geformuleer dat die disulfied brug in die proteïen betrokke is by die reduksie van die goud
ione. Alhoewel die rekombinante proteïene oor die vermoeë beskik om nanopartikels te
produseer is dié nie so effektief soos die gesuiwerde proteïen nie. Indien die optimale
kondisies vir die rekombinante proteïene uitgeklaar word, sal dié waarskynlik in die
grootskaalse produksie van goud nanopartikels of goud nanoplate gebruik kan word
Charactt[sic]erization of a plasmid conferring NAD independence in Haemophilus paragallinarum
No full textEnglish: Members of the family Pasteurellaceae are classified in part by whether or not they require NAD+ supplement for growth on laboratory media. It is known that this phenotype is determined by a plasmid whose presence allows NAD+-independent growth of Haemophilus paragallinarum.
In this study, this 6-kb plasmid, which was previously shown to be responsible for NAD+ independent growth of H. paragallinarum on defined media, was isolated. Isolated plasmid DNA was shredded by sonification and subcloned into vector PGEM-T easy. The recombinant plasmid was transformed into E.coli the transformants isolated were sequenced.
Sequence analysis revealed one open reading frame of 1119bp that is predicted to encode a protein with a molecular mass of 43kD. Compared with the sequence databases, this protein was found to have significant sequence homology to Quinolinate phosphoribosyltransferase of Bacillus anthracis this enzyme is responsible for the production of nicotinic acid mononucleotide (NAMN) from nicotinate and quinolinate. A 3284bp nucleotide fragment of the plasmid revealed four additional open reading frames. Proteins encoded on this fragment of the plasmid all have significant homology to proteins from H. influenzae of which all have functions related to production and immunity of the bacteriocin haemocim. This bacteriocin produced by most type b-encapsulated strains of H. influenzae, is toxic to virtually all non-type b strains of H. influenzae idependent of encapsulation. This bacteriocin is thought to inhibit DNA synthesis, of susceptible strains. Purification of this bacteriocin and testing its toxicity to other pathogens as a possible antimicrobial drug might form the bases of a future study.
Previous work has indicated that plasmid bearing strains of H. paragallinarum are less virulent, thus creating the possibility that more virulent wild type strains can be transformed and used as live vaccines. The influence of transformation with this plasmid on other members of the family Pasteurellaceae and the possibility of creating live vaccines should be further investigated
Since species of the genus Haemophilus cannot easily be transformed with plasmid, this naturally occurring plasmid could be modified to create a vector, which has specific application in the transformation of Haemophilus species.Afrikaans: Die klassifikasie van bakteriese spesies van die familie Pasteurallaceae word gedeeltelik gebaseer op die afhanklikheid van NAD+ vir groei op laboratorium media. Dit is bekend dat die NAD+ onafhanklike fenotipe van Haemophilus paragallinarum onderskei kan word deur die teenwoordigheid van ’n plasmied.
In hierdie studie is die plasmied van ongeveer 6kbp wat NAD+ onafhanklike groei op bepaalde media bevorder, geïsoleer. Plasmied DNA is deur middel van sonifikasie gefragmenteer en in vektor pGEM-T Easy gekloneer. Rekombinante plasmiede in E. coli getransformeer, geïsoleer en aan basisbaarvolgordebepaling onderwerp.
Ontleding van die basispaarvolgorde toon dat die plasmied ‘n oopleesraam van 1119bp bevat, wat kodeer vir ’n proteïen met ‘n geraamde molekulêre massa van 43kD. Na vergelyking met basispaarvolgorde databasisse is gevind dat hierdie proteïen betekenisvolle homologie met quinoliensuur fosforibosieltransferase, geïsoleer uit Bacillus anthracis, toon. kwinolienaat fosforibosieltransferase is verantwoordelik vir die katalitiese produksie van nikotiensuur mononukleotied vanaf nikotienaat en kwinolienaat.
Daar is verder bevind dat die plasmied ’n 3284bp fragment bevat waarop vier oopleesrame aangetref word. Die proteïne waarvoor die leesrame op hierdie fragment kodeer toon betekenisvolle homologie met proteïne geïsoleer vanuit Haemophilus influenzae, wat betrokke is by die produksie van en immuniteit teen die bakteriosien haemosien. Die meerderheid tipe b-gekapsuleerde stamme van H. influenzae produseer haemosien, terwyl die bakteriosien die groei van bykans alle nie-tipe b, beide gekapsuleerde en nie-gekapsuleerde, stamme belemmer. Daar word vermoed dat die inhibisie effek deur haemosien bewerkstellig word deurdat die bakteriosien die DNS sintese van vatbare stamme onderdruk. In ‘n verdere studie kan gefokus word op die isolasie en suiwering van haemosien en die bepaling van die mate waarin die bakteriosien die groei van ander patogeniese bakterieë belemmer. Verdere ondersoek kan ook ingestel word na die moontlike aanwending van haemosien as ‘n anti-mikrobiese middel.
Daar is vantevore bevind dat stamme van H. paragallinarum waarin plasmiede voorkom minder virulent is na aanleiding van die waarneming dat hoenders wat met hierdie stamme besmet is, minder intense simptome vertoon. Hierdie waarneming kan moontlik verklaar word in terme van die onderdrukking van sekondêre invektiewe mikro-organismes deur haemosien. Verdere ondersoeke kan dus gefokus word op die relatiewe dominansie van plasmied bevattende stamme van H. paragallinarum, om bogenoemde hipotese te toets. Dit is ook moontlik dat plasmied bevattende stamme inherent minder virulent is, wat dit moontlik maak om meer virulente wilde stamme te transformeer en sodoende lewende entstowwe te skep. Die uitwerking van transformasie met die geïsoleerde plasmied op ander spesies in die familie Pasteurellaceae en die moontlike produksie van lewende entstowwe behoort verder ondersoek te word.
Spesies in die genus Haemophilus kan slegs met moeite met plasmiede getransformeer word. Die plasmied geïsoleer vanuit H. paragallinarum kan gemodifiseer word en sodoende dien as ‘n vektor vir die transformasie van Haemophilus spesies
The genome of a subterrestrial nematode reveals adaptations to heat
No full textThe nematode Halicephalobus mephisto was originally discovered inhabiting a deep terrestrial aquifer 1.3 km underground. H. mephisto can thrive under conditions of abiotic stress including heat and minimal oxygen, where it feeds on a community of both chemolithotrophic and heterotrophic prokaryotes in an unusual ecosystem isolated from the surface biosphere. Here we report the comprehensive genome and transcriptome of this organism, identifying a signature of adaptation: an expanded repertoire of 70 kilodalton heat-shock proteins (Hsp70) and avrRpt2 induced gene 1 (AIG1) proteins. The expanded Hsp70 genes are transcriptionally induced upon growth under heat stress, and we find that positive selection is detectable in several members of this family. We further show that AIG1 may have been acquired by horizontal gene transfer (HGT) from a rhizobial fungus. Over one-third of the genes of H. mephisto are novel, highlighting the divergence of this nematode from other sequenced organisms. This work sheds light on the genomic basis of heat tolerance in a complete subterrestrial eukaryotic genom
A framework for quantifying and characterising road accident risk : a data mining approach
No full textThesis (PhD)--Stellenbosch University, 2020.ENGLISH ABSTRACT: According to the World Health Organisation, road accidents account for approximately 1:25 million deaths annually | the eighth leading cause of death worldwide. With the enormous losses to society resulting from road accidents, the prevention and severity reduction of road accidents has been an active area of research focus for many decades. Researchers frequently
employ a variety of statistical learning techniques in an attempt to understand the factors contributing to higher levels of road accident risk. Such insights provide vital direction for governments with respect to safer road designs and the establishment of countermeasures aimed
at reducing the number of road accidents. Furthermore, recent advances in machine learning have presented exciting new machine learning possibilities that were deemed far out of reach just over a decade ago. The tasks associated with data pre-processing in this context are, however, often daunting and immensely time-consuming. Moreover, the adoption of machine
learning models in the road accident analysis literature has been relatively limited due to the uninterpretable nature of the majority of these models.
A generic modular data mining framework is, therefore, proposed in this dissertation, aimed specifically at formalising and facilitating the tasks associated with road accident data preparation, and facilitating the interpretation of machine learning model output. This framework is designed to facilitate the configuration, enhancement and transformation of raw accident, vehicle,
road and victim data into useful information which appropriately quantifies and characterises road accident risk. More specifically, this framework facilitates evaluation of road accident risk in terms of the rate and severity of being involved in a road accident along road segments and at road junctions based on historically recorded RAs. The configuration procedure in the proposed
framework allows a user to format data attributes appropriately, as well as correct any missing or erroneous values that may exist in data sets. The enhancement procedure allows a user to merge vehicle and road records to a corresponding accident record for the purpose of creating an all-encompassing data set. It is also possible to construct new attributes based on current
attribute values residing in the aforementioned data sets. After each of the individual data sets has been prepared appropriately and the data are deemed of a suficiently high quality, they may be stored in a database. Finally, the transformation procedure exploits these high-quality
data to quantify the rate and severity of road accidents along road segments or at road junctions.
These results serve as input to a standard supervised learning procedure in which road characteristics are used to predict these rate and severity measurements.
In order to demonstrate the practical workability and usefulness of the proposed framework, a concept demonstrator of the framework is implemented in an existing data mining platform and applied to a real-world case study based on road accident data from Greater Manchester in the United Kingdom. Each of the individual data preparation components of the framework is
tested in the context of this case study, while the effectiveness of the road accident risk evaluation
approaches is demonstrated by means of multiple investigations.AFRIKAANSE OPSOMMING: Volgens die Wêreldgesondheidsorganisasie veroorsaak padongelukke jaarliks sowat 1.25 miljoen sterftes — die agtste hoofoorsaak van sterftes wêreldwyd. Met die enorme verliese vir die samelewing wat padongelukke meebring, is die voorkoming en ernsvermindering van padongelukke vir dekades al ’n aktiewe navorsingsarea. Navorsers gebruik dikwels ’n verskeidenheid statistiese leertegnieke om die faktore wat tot hoër vlakke van padongelukrisiko bydra, te verstaan. Sulke insigte bied belangrike geleenthede vir regerings ten opsigte van die daarstelling van veiliger padontwerpe en teenmaatreëls wat daarop gemik is om die aantal padongelukke te verminder. Verder het onlangse vordering in masjienleer opwindende nuwe masjienleerbenaderings wat net meer as ’n dekade gelede as buite bereik beskou is, moontlik gemaak. Die take wat verband hou met datavoorbereiding in hierdie konteks, is egter dikwels uitdagend en baie tydrowend. Die aanvaarding van masjienleermodelle in die literatuur oor die ontleding van padongelukke was ook betreklik beperk vanweë die oninterpreteerbare aard van die meerderheid van hierdie modelle. ’n Generiese modulêre data-ontginningsraamwerk word dus in hierdie proefskrif voorgestel, wat spesifiek gemik is op die formalisering en fasilitering van die take wat verband hou met die voorbereiding van padongelukdata, asook die fasilitering van die interpretasie van kragtige masjienleer algoritme afvoer. Hierdie raamwerk is ontwerp om die konfigurasie, verbetering en transformasie van rou ongeluks-, voertuig- en paddata na betekenisvolle inligting te fasiliteer wat padongelukrisiko toepaslik karakteriseer en kwantifiseer. Meer spesifiek, hierdie raamwerk fasiliteer die evaluasie van die risiko van padongelukke ten opsigte van die tempo en erns van die betrokkenheid by padongelukke langs padsegmente en by padkruisings gebaseer op historiese padongelukke. Die konfigurasieprosedure in die voorgestelde raamwerk stel die gebruiker in staat om data-eienskappe op gepaste wyse te formateer, sowel as om ontbrekende of foutiewe waardes wat in datastelle mag bestaan, reg te stel. Die verbeteringsprosedure stel die gebruiker in staat om voertuig- en padrekords saam te voeg tot ’n oorkoepelende rekord van padongelukke met die doel om ’n allesomvattende datastel te skep. Die konstruksie van nuwe attribute gebaseer op huidige attribuutwaardes wat in bogenoemde datastelle voorkom, is ook moontlik. Nadat elk van die individuele datastelle toepaslik voorberei is en die inligting as van voldoende hoë gehalte beskou word, kan die data in ’n databasis geberg word. Uiteindelik maak die transformasieprosedure van hierdie hoë-gehalte data gebruik om die tempo en erns van padongelukke langs padsegmente of by padkruisings te bepaal. Hierdie resultate dien as insette tot ’n standaard toesigleerproses waarin padkenmerke gebruik word om hierdie tempo- en ernsmetings te voorspel. Ten einde die praktiese werkbaarheid en bruikbaarheid van die voorgestelde raamwerk te demonstreer, word ’n prototipe van die raamwerk in ’n bestaande data-ontginningsagteware omgewing geïmplementeer en op ’n werklike gevallestudie toegepas wat gebaseer is op padongelukdata in die Groter Manchester-area van die Verenigde Koninkryk. Elk van die individuele data-voorbereidingskomponente van die raamwerk word in die konteks van hierdie gevallestudie getoets, terwyl die doeltreffendheid van die padongeluk risiko-evalueringsproses deur middel van veelvuldige ondersoeke gedemonstreer word.Doctora
- …
