Estudou-se a evolução morfológica de precipitados .. em matriz .. Cu-Al, através de tratamentos isotérmicos interrompidos por têmpera, em amostras previamente solubilizadas desde o início da precipitação, até o crescimento competitivo. Caracterizou-se a forma dos precipitados após tratamentos em diversas temperaturas, por microscopia ótica e microscopia eletrônica de varredura, de estruturas atacadas profundamente. A forma dos precipitados após tratamentos prolongados a 700 ºC tende a ser esférica, enquanto nos tratamentos a 600 ºC, tende a ser facetada. Com temperaturas decrescentes de 700 º para 600 ºC a forma passa gradualmente de esférica para facetada. Verificou-se que a distribuição espacial dos precipitados depende da velocidade de aquecimento. Com altas velocidades (tratamento em banho de sal), a distribuição é homogênea; com velocidade de aquecimento lentas (tratamento em forno de mufla) os precipitados apresentam-se alinhados, indicando nucleação heterogênea. O crescimento competitivo foi caracterizado através de medidas das distribuições de tamanhos de precipitados. Esta medida foi realizada utilizando micrografias de secções polidas, com um equipamento semi-automático. As medidas de distribuição de tamanhos das secções de precipitados foram processadas para a obtenção da distribuição de diâmetros reais dos precipitados através de um programa de computador utilizando o algoritmo de Saltykov. ......... / The morphological evoluation of .. precipitates in a . Cu-Al matrix has been studied from the beginning of precipitation until coarsening, using isothermal treatments on previously solubilized samples. The shape of precipitates after treatments at many temperatures was studied using Optical Microscopy and Scanning Electron Microscopy of deep etched samples. The precipitates treated for long periods at 700 ºC approach an spherical shape, while treatments at 600 ºC the precipitates become faceted. The special distribution of the precipitates are determined by the heating rate from room temperature to isothermal treatment temperature. With high heating rates the distribution is homogeneous. With low heating rate the precipitates are arranged in rows, due to heterogeneous nucleation. Coarsening was studies by measuring the distribution of precipitate sizes on microphotographs of polished sections using a semi-automatic device. The mesures of section sizes were processed to obtain the real diameter distribution using a computer program based on Saltykov\'s algoritm. .....

Estudou-se a evolução morfológica de precipitados .. em matriz .. Cu-Al, através de tratamentos isotérmicos interrompidos por têmpera, em amostras previamente solubilizadas desde o início da precipitação, até o crescimento competitivo. Caracterizou-se a forma dos precipitados após tratamentos em diversas temperaturas, por microscopia ótica e microscopia eletrônica de varredura, de estruturas atacadas profundamente. A forma dos precipitados após tratamentos prolongados a 700 ºC tende a ser esférica, enquanto nos tratamentos a 600 ºC, tende a ser facetada. Com temperaturas decrescentes de 700 º para 600 ºC a forma passa gradualmente de esférica para facetada. Verificou-se que a distribuição espacial dos precipitados depende da velocidade de aquecimento. Com altas velocidades (tratamento em banho de sal), a distribuição é homogênea; com velocidade de aquecimento lentas (tratamento em forno de mufla) os precipitados apresentam-se alinhados, indicando nucleação heterogênea. O crescimento competitivo foi caracterizado através de medidas das distribuições de tamanhos de precipitados. Esta medida foi realizada utilizando micrografias de secções polidas, com um equipamento semi-automático. As medidas de distribuição de tamanhos das secções de precipitados foram processadas para a obtenção da distribuição de diâmetros reais dos precipitados através de um programa de computador utilizando o algoritmo de Saltykov. ......... / The morphological evoluation of .. precipitates in a . Cu-Al matrix has been studied from the beginning of precipitation until coarsening, using isothermal treatments on previously solubilized samples. The shape of precipitates after treatments at many temperatures was studied using Optical Microscopy and Scanning Electron Microscopy of deep etched samples. The precipitates treated for long periods at 700 ºC approach an spherical shape, while treatments at 600 ºC the precipitates become faceted. The special distribution of the precipitates are determined by the heating rate from room temperature to isothermal treatment temperature. With high heating rates the distribution is homogeneous. With low heating rate the precipitates are arranged in rows, due to heterogeneous nucleation. Coarsening was studies by measuring the distribution of precipitate sizes on microphotographs of polished sections using a semi-automatic device. The mesures of section sizes were processed to obtain the real diameter distribution using a computer program based on Saltykov\'s algoritm. .....

In some animal societies, access to breeding depends on the individual’s position in a hierarchy, which often depends on an individual’s size. In such societies, individuals may engage in competitive growth, trying to outgrow one another to attain a higher rank. This suggests that members of the hierarchy can track changes in the growth and size of potential competitors and respond accordingly. The clown anemonefish, Amphiprion percula, is one species known to exhibit competitive growth at the initiation of size hierarchies. Here, we use 5 combinations of sensory cues to determine which cues must be available to initiate competitive growth between size-matched individuals. Our results show that mechanosensory (pressure and/or touch) cues are used to assess size and initiate competitive growth. This study provides an understanding into the relationship between environment and phenotypic response in a social context.

Non-equilibrium surface growth for competitive growth models in (1+1) dimensions, particularly mixing random deposition (RD) with correlated growth process which occur with probability $p$ are studied. The composite mixtures are found to be in the universality class of the correlated growth process, and a nonuniversal exponent $\delta$ is identified in the scaling in $p$. The only effects of the RD admixture are dilations of the time and height scales which result in a slowdown of the dynamics of building up the correlations. The bulk morphology is taken into account and is reflected in the surface roughening, as well as the scaling behavior. It is found that the continuum equations and scaling laws for RD added, in particular, to Kardar-Parisi-Zhang (KPZ) processes are partly determined from the underlying bulk structures. Nonequilibrium surface growth analysis are also applied to a study of the static and dynamic load balancing for a conservative update algorithm for Parallel Discrete Event Simulations (PDES). This load balancing is governed by the KPZ equation. For uneven load distributions in conservative PDES simulations, the simulated (virtual) time horizon (VTH) per Processing Element (PE) and the imulated time horizon per volume element $N_{v}$ are used to study the PEs progress in terms of utilization. The width of these time horizons relates to the desynchronization of the system of processors, and is related to the memory requirements of the PEs. The utilization increases when the dynamic, rather than static, load balancing is performed.

Cyanobacteria are a model organism for photosynthesis and the Calvin cycle, and a promising chassis for 4th generation biofuel production. There are many ongoing efforts to improve the performance of cyanobacteria, in terms of CO2 fixation and production rate of biofuels. One straightforward way to improve CO2 fixation could be to overexpress the genes of limiting enzymes. In this project, we used a high-throughput method to test the overexpression of thousands of genes in cyanobacteria and measure the effect on growth rate. We created barcoded overexpression libraries, consisting of gene fragments from different cyanobacteria strains and transformed them into a model cyanobacterium, Synechocystis PCC 6803. We then cultivated the transformed cyanobacteria libraries and screened for effects of increased gene copy number on both maximum growth rate and robustness of growth under stress conditions. The cell populations were cultivated in a turbidostat, resulting in competitive growth between transformants. The relative abundance of each mutant was estimated using deep sequencing. Fitness scores, for each gene show how expression of that gene affects growth rate. This method, competitive growth and tracking of mutant populations with deep sequencing, is a high throughput method for screening a large proportion of genes from several organism at once, allowing the identification of trans-species effects as well as the effect of single genes on the metabolism of the host cell. / Cyanobakterier är en modellorganism för fotosyntes och Calvin-cykeln och ett lovande chassi för fjärde generationens biobränsleproduktion. Det finns många pågående ansträngningar för att förbättra cyanobakteriens prestanda med avseende på CO2-fixering och produktionshastighet för biobränslen. Ett enkelt sätt att förbättra CO2-fixering kan vara att överuttrycka generna för begränsande enzymer. I detta projekt använde vi en metod med hög kapacitet för att testa överuttryck av tusentals gener i cyanobakterier och mäta effekten på tillväxthastigheten. Vi skapade streckkodade överuttrycksbibliotek, bestående av genfragment från olika arter av cyanobakterier och transformerade in dem i en modellorganism för cyanobakterium, Synechocystis PCC 6803. Vi odlade sedan de transformerade biblioteken och screenade efter effekten av ökade antal genkopior på både maximal tillväxthastighet och robusthet hos tillväxt under stressförhållanden. Cellpopulationerna odlades i en Turbidostat, vilket resulterade i konkurrerande tillväxt mellan transformanter. Den relativa mängden av varje mutant uppskattades med användning av djup sekvensering. "Fitnesspoäng" för varje gen visar hur uttrycket av den genen påverkar tillväxthastigheten. Denna metod, konkurrerande tillväxt och spårning av mutantpopulationer med djup sekvensering, är en metod med hög genomströmning för att screena en stor andel gener från flera organismer samtidigt, vilket möjliggör identifiering av trans-art effekter såväl som effekten av enstaka gener på värdcellens metabolism.

The budding yeast Saccharomyces cerevisiae has been an invaluable model organism in contributing to the current understanding of cellular biology, owing mainly to its highly tractable genetic system and the completion of its genome sequencing in 1996. Indeed, these bolstered the development of novel methods that have provided great insights into genetic and protein networks in human cells. With the large collection of datasets, S. cerevisiae also became an ideal platform for investigating the mechanism of action of novel compounds. The first part of my thesis uses a validated chemogenomic assay to investigate the mechanism of action of structurally related novel DNA-damaging agents, delineating valuable structure-activity relationship in the process. The second part describes the development of a method that uses drug-induced wild-type growth dynamic to characterize novel compounds, which, in combination with the chemogenomic assay, may complement existing high throughput screening experiments to improve the current drug development process.

The budding yeast Saccharomyces cerevisiae has been an invaluable model organism in contributing to the current understanding of cellular biology, owing mainly to its highly tractable genetic system and the completion of its genome sequencing in 1996. Indeed, these bolstered the development of novel methods that have provided great insights into genetic and protein networks in human cells. With the large collection of datasets, S. cerevisiae also became an ideal platform for investigating the mechanism of action of novel compounds. The first part of my thesis uses a validated chemogenomic assay to investigate the mechanism of action of structurally related novel DNA-damaging agents, delineating valuable structure-activity relationship in the process. The second part describes the development of a method that uses drug-induced wild-type growth dynamic to characterize novel compounds, which, in combination with the chemogenomic assay, may complement existing high throughput screening experiments to improve the current drug development process.

Abstracts in English, Afrikaans and Zulu / Small and medium enterprises play a significant role in the economic growth of Lesotho, however, they face low survival rates and competitive growth drawbacks. Market-driven strategies and access to finance have been identified as the major constraints hindering their survival, growth and effective operation in Lesotho. The purpose of the study was to investigate the influence of market-driven strategies and access to finance on the competitive growth of small and medium-sized enterprises in selected districts of Lesotho. A quantitative descriptive-correlation survey approach was followed in the data collection and the analysis phases of the research study. The target population consisted of a probability sample of (N = 400) entrepreneurs in the four selected districts of Lesotho. The data was captured and analysed for descriptive statistics, convergent and discriminant validity, composite and internal reliability and correlation in order to inform the structural equation modelling (SEM). SEM was used to test the research model and hypotheses to answer the research questions. The correlation analysis revealed a positive significant relationship between the market-driven strategies and access to finance constructs and related to the competitive growth of SMEs. The regression results showed a positive and significant influence of market-driven strategies (technological dynamic and competitive intensity) and access to finance (collateral requirement and financial information access) on the competitive growth of SMEs. The structural equation modelling analysis further indicated that the equation model derived from the covariance estimates of all explanatory factors of market-driven strategies and access to finance on competitive growth were within the goodness-of-fit threshold. The study was specific to small and medium enterprises, and the findings suggest that to address their challenges in Lesotho (i) enterprises need to be equipped with market-driven strategic (competitive intensity and technological dynamic) resources to deliver superior value to customers; and (ii) adequate policy initiatives are needed to improve enterprises’ access to finance, and such should (a) focus on improving access to financial information through awareness programmes, (b) consider adequate information on policy initiatives, support programmes and financial schemes geared to support Basotho small and medium-sized enterprises access to finance, and (c) harmonise the collateral requirements by banks to ease Basotho SMEs access to adequate credit funds. In sum, the results suggest the joint implementation of market-driven strategies and access to finance as enabling resources to assist enterprises to achieve and stay competitive in the current dynamic business environment. / Klein en medium ondernemings (KMO’s) speel ʼn beduidende rol in die ekonomiese groei van Lesotho. Hulle ervaar egter lae oorlewingstempo’s en mededingendegroei-nadele. Markgedrewe strategieë en toegang tot finansiering is geïdentifiseer as die vernaamste beperkings in die voortbestaan, groei en doeltreffende bedryf van hierdie ondernemings in Lesotho. Die doel van die studie was om die invloed van markgedrewe strategieë en toegang tot finansiering op die mededingende groei van KMO’s in bepaalde distrikte van Lesotho, te ondersoek. ʼn Kwantitatiewe beskrywende-korrelasie-opname-benadering is in die data-insameling en -ontledingsfases van die navorsingsondersoek gevolg. Die teikenpopulasie het bestaan uit ʼn waarskynlikheidsmonster van (N = 400) entrepreneurs in die vier gekose distrikte van Lesotho. Die data is vasgelê en ontleed vir beskrywende statistiek, konvergente en diskriminantgeldigheid, saamgestelde en interne betroubaarheid en korrelasie, as deel van strukturele vergelykingsmodellering, wat gebruik is om die navorsingsmodel en hipoteses te toets ten einde die navorsingsvrae te beantwoord. Die korrelasie-ontleding het ʼn positiewe beduidende verwantskap tussen die volgende konsepte getoon: markgedrewe strategieë, toegang tot finansiering en die mededingende groei van KMO’s. Die regressieresultate het daarop gedui dat markgedrewe strategieë (tegnologies dinamiese en mededingende intensiteit) en toegang tot finansiering (kollaterale vereiste en toegang tot finansiële inligting) ʼn positiewe en beduidende invloed op die mededingende groei van KMO’s het. Die strukturele vergelykingsmodelleringontleding het verder getoon dat die vergelykingsmodel afkomstig van die kovariansie-skattings van alle verduidelikende faktore van markgedrewe strategieë en toegang tot finansiering rakende mededingende groei, binne die geskiktheidsdrumpel val. Die studie was spesifiek oor KMO’s, en die bevindinge toon dat om die struikelblokke wat in Lesotho ervaar word te bowe te kom, (i) hierdie ondernemings toegerus moet word met markgedrewe strategiese (mededingende-intensiteit en tegnologies dinamiese) hulpbronne sodat hulle voortreflike waarde aan hul klante kan bied; en (ii) voldoende beleidsinisiatiewe nodig is om die ondernemings se toegang tot finansiering te verbeter; hierdie beleidsinisiatiewe moet (a) fokus op verbetering van toegang tot finansiële inligting deur bewustheidsprogramme (b) voldoende inligting voorsien oor beleid, ondersteuningsprogramme en finansiële skemas gerig op beter toegang vir KOMO’s tot finansiering, en (c) die kollaterale vereistes deur banke harmonieer om toegang deur KMO’s tot toereikende kredietfondse te fasiliteer. Kortom stel die resultate die gesamentlike implementering van markgedrewe strategieë en toegang tot finansiering as instaatstellingshulpbronne voor om ondernemings te help om mededingendheid te bewerkstellig en te behou in die huidige dinamiese sakeomgewing. / Amabhizinisi amancane nasafufusa (SME) adlala indima esemqoka ekuhlumiseni umnotho wasezweni laseLesotho. Yize-kunjalo, lincane kakhulu inani lamabhizinisi asindayo futhi lincane kakhulu inani lalawo ahlumayo kwizimakethe zamabhizinisi ezincintisanayo. Amasu aqhutshwa yizimakethe kanye nokutholakala kwezimali kubonwe njengezihibhe ezinkulu ezivimba ukuphumelela, ukuhluma kanye nokusebenza kahle kwamabhizinisi eLesotho. Injongo yalesi sifundo socwaningo bekukuphenya umthelela wamasu aqhutshwa yizimakethe kanye nokutholakala kwezimali zokuhlunyiswa komnotho wama-SME ngendlela ekhonyayo kwizifunda zaseLesotho. Indlela yesaveyi ebizwa nge-quantitative descriptive-correlation survey iye yalandelwa ekuqoqweni kwedatha kanye nakwizigaba zokuhlaziya kwisifundo socwaningo. Inani eliphelele labantu eliqondiwe linamasampuli wethuba lokwenzeka (probability sample of (N = 400) losomabhizinisi abakwizifunda ezine ezikhethiwe zaseLesotho. Idatha iqoqiwe yahlaziywa ukwenzela amanani achazayo, i-convergent and discriminant validity, i-composite kanye ne-internal reliability and correlation ngenhloso yokuhlomisa uhlelo lwe-structural equation modelling ngolwazi, ulwazi olusetshenziswe ukuhlola imodeli yocwaningo kanye nehayipothesisi ukuze kuphenduleke imibuzo yocwaningo. Uhlaziyo lwe_correlation analysis luveze ubudlelwano obubonakalayo phakathi kwezinhlaka zamasu aqhutshwa yizimakethe, ukutholakala kwezimali kanye nokuhluma ngamandla kwezomnotho kwamabhizinisi amancane nasafufusa (SMEs). Imiphumela yohlelo lwe-regression ikhombe amasu aqhutshwa yizimakethe (technological dynamic and competitive intensity) kanye nokutholakala kwezimali (collateral requirement and financial information access) njengezinhlaka ezinomthelela omuhle nobalulekile phezu kokuhluma ngamandla komnotho wamabhizinisi asafufusayo (SMEs). Uhlelo lokuhlaziya imodeli elibizwa nge-structural equation modelling liqhubeke nokuveza uhlelo lwe- equation model olususelwe kwisilinganiso se-covariance sezinhlaka zonke ezichazayo zamasu aqhutshwa yizimakethe kanye nokutholakala kwezimali kumnotho ohluma ngamandla wamabhizinisi amancane nasafufusa ukuthi kube ngaphakathi kohlelo lwe-goodness-of-fit threshold. Ucwaningo belugxile ikakhulu kumabhizinisi aamancane nasafufusa, , kanti ulwazi olufunyenwe luphakamisa ukuthi ukuze kuqedwe izinkinga okuhlangabezanwa nazo eLesotho, (i) la mabhizinisi adinga ukuba ahlonyiswe ngamasu aqhutshwa yimithombo yezimakethe (competitive intensity and technological dynamic) ngenhloso yokuletha izinga eliphezulu lomkhiqizo kumakhasimende; kanti (ii) kudinga imizamo yemigomo eyanele ukuthuthukisa izinga lokutholakala kwezimali ngamabhizinisi; le mizamo yomgomo kufanele (a) igxile ekuthuthukiseni izinga lokutholakala kolwazi lwezimali ngokusebenzisa izinhlelo zokwexwayisa, (b) ukunikeza ulwazi olwanele olumayelana nezomgomo, nezinhlelo zokuxhasa kanye nezikhwama zezimali ezihlelelwe ukuthuthukisa ukuthuthukisa uhlelo lizinga lokutholakala kwezimali ngamabhizinisi amancane nasafufusa, kanti futhi (c) ukuhlanganisa ndawonye izimfuno ezifanayo ngamabhange ukwenzela ukulungisa uhlelo olusiza ukunikezwa kwamabhizinisi amancane nasafufusa izikweletu zemali eyanele. Sekukonke nje, imiphumela iphakamisa ukuthi kube nohlelo oluhlanganyelwe lokusetshenziswa kwamasu aqhutshwa yizimakethe kanye nokutholakala kwezimali ezinceda imithombo ukuthi incede amabhizinisi ekufinyeleleni izinhloso kanye nokugcina ummoya wokuncintisana kwisizinda samanje sezebhizinisi. / Business Management / D. Phil. (Management Studies)