This thesis develops a simulation and visualization of a path finding algorithm based on ant pheromone paths created in 3D space. The simulation is useful as a demonstration of a heuristic approach to NP-complete problems and as an educational tool for demonstrating how ant colonies gather food. An interactive real time 3D visualization is built on top of the simulation. A graphical user interface layer allows user interaction with the simulation and visualization.

The scope of this thesis was to identify, describe and quantify important life-history traits for the pseudoannual aquatic plant Ranunculus lingua in different ecological settings, by comparing populations from geographically marginal vs. central habitats. Results from a four-year field study showed that abiotic factors (water-level fluctuations and associated processes) tended to have a greater influence in marginal populations, whereas biotic factors (competition, insect grazing and fungal infections) dominated in central populations. This was reflected in different depth distribution of ramet numbers and ramet sizes between the areas, and In different dynamic patterns, with a higher flux of ramets in marginal populations. In a reciprocal transplant experiment, marginal ramets produced more but smaller rhizomes, whereas central ramets produced Individually larger but fewer rhizomes, irrespective of transplant site. A possible selection for genotypes producing large rhizomes in the central habitat was supported by the fact that initially smaller ramets were more likely to be diseased by the fungal pathogen Peronospora gigantea and damaged by insect grazing. In the marginal population, where density-independent mortality factors tend to dominate, a high reproductive output, expressed in production of high numbers of rhizomes, was suggested to be a favoured life-history trait. In a glasshouse experiment, ramets from marginal and central populations were grown in low and high densities and under three contrasting nutrient levels. The allocation to sexual structures was generally very low, and did not incur any costs in terms of reduced rhizome production. Rhizome production showed strong positive allometrical relationships to mother ramet size. Increasing mother ramet size resulted in a larger increase in rhizome numbers for the marginal than for the central population, whereas the increase in mean rhizome mass was more pronounced for the centred population. Both populations showed similar reductions in rhizome production in response to increased density and lowered nutrient levels, which could not be explained by size-dependent effects adone. The dispersal, dynamics and distribution of R. lingua were studied in a marginal river population in northern Sweden, where the only means of dispersal is by vegetative diaspores, i.e. floating rhizome fragments. Stranding occurred mainly in river curves and at obstacles, and the distribution of established stands was also highly correlated with these features. Relative changes in ramet numbers were correlated with water-level fluctuations during the present and previous growing seasons, with winter low-water, and with duration of spring-flood. The predictability of change was high within but low between stands. It was concluded that the patterns and mechanisms of dispersal are fundamental for local distribution patterns as well as variation in regional abundance in R. lingua / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1992, härtill 4 uppsatser</p> / digitalisering@umu

Marsh vegetation is widely considered to offer protection against coastal storm damage, and vegetated flow has thus become a key area of hydrodynamic research. This study investigates the utility of simulated Spartina alterniora marsh vegetation as storm protection using an ADV measurement technique, and is the first to apply jet self-similarity analysis to characterize the overall mean and turbulent flow properties of a three-dimensional axisymmetric jet through a vegetated array. The mean axial flow of a horizontal axisymmetric turbulent jet is obstructed by three configurations of staggered arrays of vertical rigid plant stems. The entire experiment is repeated over five sufficiently high jet Reynolds number conditions to ensure normalization and subsequent collapse of data by nozzle velocity so that experimental error is obtained. All self-similarity parameters for the unobstructed free jet correspond to typical published values: the axial decay coefficient B is 5:8 +/- 0:2, the Gaussian spreading coefficient c is 85 +/- 5, and the halfwidth spreading rate eta_(1/2) is 0:093 +/- 0:003. Upon the introduction of vegetation, from partially obstructed to fully obstructed, B falls from 5:1+/- 0:2 to 4:2 +/- 0:2 and finally 3:7 +/-0:1 for the fully obstructed case, indicating that vegetation reduces axial jet velocity. Cross-sectionally averaged momentum for the unobstructed free jet is M=M0 = 1:05 +/- 0:07, confirming conservation of momentum. Failure of conservation of momentum is most pronounced in the fully obstructed scenario – M=M0 = 0:54 +/- 0:05. The introduction of vegetation increases spreading of the impinging jet. The entrainment coefficient alpha for the free jet case is 0.0575; in the fully obstructed case, alpha = 0:0631. Mean advection of mean and turbulent kinetic energy demonstrates an expected reduction in turbulence intensity within the vegetated array. In general, turbulent production decreases as axial depth of vegetation increases, though retains the bimodal profile of the free jet case; the fully vegetated case, however, exhibits clear peaks behind plant stems. Turbulent transport was shown to be unaffected by vegetation and appears to be primarily a function of axial distance from the jet nozzle. An analysis of rate of dissipation revealed that not only does the cumulative effect of upstream wakes overall depress the magnitude of spectral energy density across all wavenumbers but also that plant stems dissipate large anisotropic eddies in centerline streamwise jet flow. This study, thus, indicates that sparse emergent vegetation both reduces axial flow velocity and has a dissipative effect on jet flow. Typically, however, storm surge does not exhibit the lateral spreading demonstrated by an axisymmetric jet; therefore, the results of this study cannot conclusively support the claim that coastal vegetation reduces storm surge axial velocity.

We discuss the appearance of quantum orders in the Hubbard model for interacting electrons, at half-filling. Such phases do not have local order parameters and need to be characterized by the quantum mechanical properties of their ground state. On one hand, we study the Mott transition from a metal to a spin liquid insulator in two dimensions, of potential relevance to some layered organic compounds. The correlation-driven transition occurs at fixed filling and involves fractionalization of the electron: upon entering the insulator, a Fermi surface of neutral spinons coupled to an internal gauge field emerges. We focus on the transport properties near the quantum critical point and find that the emergent gauge fluctuations play a key role in determining the universal scaling. Second, motivated by a class of three-dimensional transition metal oxides, the pyrochlore iridates, we study the interplay of non-trivial band topology and correlations. Building on the strong spin orbit coupling in these compounds, we construct a general microscopic Hubbard model and determine its mean-field phase diagram, which contains topological insulators, Weyl semimetals, axion insulators and various antiferromagnets. We also discuss the effects many-body correlations on theses phases. We close by examining a fractionalized topological insulator that combines the two main themes of the thesis: fractionalization and non-trivial band topology. Specifically, we study how the two-dimensional protected surface states of a topological Mott insulator interact with a three-dimensional emergent gauge field. Various correlation effects on observables are identified.

We discuss the appearance of quantum orders in the Hubbard model for interacting electrons, at half-filling. Such phases do not have local order parameters and need to be characterized by the quantum mechanical properties of their ground state. On one hand, we study the Mott transition from a metal to a spin liquid insulator in two dimensions, of potential relevance to some layered organic compounds. The correlation-driven transition occurs at fixed filling and involves fractionalization of the electron: upon entering the insulator, a Fermi surface of neutral spinons coupled to an internal gauge field emerges. We focus on the transport properties near the quantum critical point and find that the emergent gauge fluctuations play a key role in determining the universal scaling. Second, motivated by a class of three-dimensional transition metal oxides, the pyrochlore iridates, we study the interplay of non-trivial band topology and correlations. Building on the strong spin orbit coupling in these compounds, we construct a general microscopic Hubbard model and determine its mean-field phase diagram, which contains topological insulators, Weyl semimetals, axion insulators and various antiferromagnets. We also discuss the effects many-body correlations on theses phases. We close by examining a fractionalized topological insulator that combines the two main themes of the thesis: fractionalization and non-trivial band topology. Specifically, we study how the two-dimensional protected surface states of a topological Mott insulator interact with a three-dimensional emergent gauge field. Various correlation effects on observables are identified.

Les dernières décennies ont été marquées par une augmentation du nombre des cas de cancers, ce qui a subséquemment conduit à une augmentation dans la consommation des agents de chimiothérapie. La toxicité et le caractère cancérogène de ces molécules justifient l’intérêt crucial porté à leur égard. Quelques études ont fait l’objet de détection et de quantification des agents de chimiothérapie dans des matrices environnementales. Dans ce projet, une méthode utilisant la chromatographie liquide couplée à la spectrométrie de masse en tandem (LC-MS/MS) précédée d’une extraction sur phase solide (SPE) automatisée ou en ligne a été développée pour la détection et la quantification d’un groupe de six agents de chimiothérapie. Parmi ceux-ci figurent les plus utilisés au Québec (gemcitabine, méthotrexate, cyclophosphamide, ifosfamide, irinotécan, épirubicine) et présentant des propriétés physico-chimiques et des structures chimiques différentes. La méthode développée a été validée dans une matrice réelle représentant l’affluent d’une station d’épuration dans la région de Montréal. Deux des six composés cytotoxiques étudiés en l’occurrence (cyclophosphamide et méthotrexate) ont été détectés dans huit échantillons sur les neuf qui ont été recensés, essentiellement au niveau de l’affluent et l’effluent de quelques stations d’épuration de la région de Montréal. Les résultats des analyses effectuées sur les échantillons réels ont montré qu’il n’y avait pas de différence significative dans la concentration entre l’affluent et l’effluent, et donc que les systèmes d’épuration semblent inefficaces pour la dégradation de ces molécules. / The last few decades have been marked by an increase in the number of cancer cases, which subsequently led to an increase in the consumption of chemotherapeutic agents. The toxicity and the carcinogenicity of these molecules justify the increased interest. Few studies have been conducted to detect and quantify chemotherapeutic agents in environmental matrices. In this project, a method using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) preceded by an online solid-phase extraction (SPE) has been developed for the detection and quantification of a group of six chemotherapeutic agents, which are among the most commonly used in Quebec (gemcitabine, methotrexate, cyclophosphamide, ifosfamide, irinotecan, epirubicin) and having different physico-chemical properties and different chemical structures. The developed method was validated in a real water matrix representing the influent of a sewage treatment plant in the Montreal area. Two of the six studied cytotoxic agents (cyclophosphamide and methotrexate) were detected in eight samples of the nine taken mainly at the influent and effluent of some treatment plants in the Montreal area. The results of the analysis of real samples showed that there was no significant difference in concentration between the influent and effluent. This also demonstrates the inadequacy of the current wastewater treatment approaches to remove those compounds.

On-line writing workshops provide educational spaces within which aspiring writers can learn their craft. In order to understand the dialogic mechanisms behind that learning, this thesis examines ways in which one workshop, the Internet Writing Workshop (IWW), functions as a Freireian culture circle. The exegesis identifies several key characteristics that defined Paulo Freire's concept of the culture circle. It compares these characteristics with the structure and practice of interaction within the IWW. It unpacks some of Freire's ideas about dialogue as a means of achieving critical consciousness, and compares them to current learning theory and the ways in which dialogue takes place within the IWW community. The exegesis also examines some of the political axioms behind Freire's pedagogy, and examines ways in which the IWW community might be viewed as emancipatory or liberatory. I examine these areas in light of the development of a novel, Suicide Girls. The second draft of this novel was influenced and informed by my participant-observation of the IWW. This working draft of the novel is provided as a process document to demonstrate findings made in the exegesis and is annotated to reflect relevant process and development issues.

Clusters de alta tecnologia são vistos como importantes centros de inovação e produção em uma economia atual global e interconectada. Observa-se um maior interesse da comunidade acadêmica pela relação entre o desenvolvimento de clusters de alta tecnologia em economias emergentes e suas conexões globais através da ‘circulação de talentos entre os clusters’ (em inglês, IBC). IBC representa, tipicamente, a difusão e transferência de tecnologias, conhecimentos e práticas através de redes individuais entre clusters emergentes e clusters já estabelecidos, os quais estão globalmente interconectados através dos laços destas redes. O foco deste estudo está no papel controverso da IBC no estímulo ao crescimento e melhoria de clusters maiores/em crescimento versus clusters menores/nascentes. Este estudo tem como objetivo propor formas de governança da IBC para conduzir estes processos nos seus diferentes estágios de desenvolvimento. O contexto empírico investigado está baseado em (a) dois casos consolidados da literatura: as conexões de Bangalore (IN) - Vale do Silício e Hsinchu (TW) - Vale do Silício; e, (b) dois casos originais: as conexões de Daedeok Innopolis (KR) – EUA e Vale dos Sinos (BR) – Coreia. O método de pesquisa utilizado é qualitativo com a aplicação de 26 entrevistas em profundidade como fonte principal de evidência. Com base nos casos estudados, é possível argumentar que os clusters maiores/em crescimento se beneficiam de uma IBC orgânica, estimulada pelas dinâmicas e forças do mercado, enquanto os clusters menores/nascentes dependem de um esforço coordenado devido à falta de atratividade inicial para empresas e indivíduos. Além disto, com vistas à eficácia da IBC no estimulo ao crescimento e melhoria de clusters, também se pode argumentar que a intervenção nas dinâmicas da IBC se reduz ao longo da evolução dos clusters, passando de um esforço coordenado nos estágios iniciais de desenvolvimento do cluster para um processo orgânico da IBC guiado pelo mercado em estágios mais avançados de desenvolvimento. Este estudo tem implicações importantes no entendimento da conectividade de clusters, do papel da governança para o crescimento e melhoria de clusters e das estratégias efetivas de catch-up para economias emergentes. / High-tech clusters are important hubs of innovation and production in an increasingly interconnected global economy. There has been an increasing interest from scholars in the embeddedness of local cluster development, in particular of high-tech industries in emergent economies, and global connectivity, in particular in the dynamics and role of inter-cluster brain circulation (IBC). IBC denotes knowledge, technology and practice diffusion and translation through individual networks between emergent and typically more established clusters that are globally interconnected through these network ties. Of particular interest to this study is the controversial role of IBC in stimulating the growth and upgrading of larger/growing versus smaller/nascent clusters. Using the lens of network governance, this study aims to propose forms of IBC governance for steering these processes. The empirical context of investigation is composed of (a) two prior studies of IBC in the cases of Bangalore (IN) - Silicon Valley and Hsinchu (TW) - Silicon Valley connections and (b) two original empirical cases examining the Sinos Valley (BR) - Korea connection and Daedeok Innopolis (KR) - US connection. A qualitative research method strategy is employed in these two original cases using 26 in-depth interviews across both cases as a source of evidence. Based on the studied cases, it is possible to argue that for larger-scale growing clusters, IBC-growth dynamics may unfold as an ‘organic process’ through self-reinforcing market forces, whereas small-scale embryonic clusters depend on a ‘coordinated effort’ of this process because they lack initial market attractiveness for both individuals and firms. Further, focusing on the effectiveness of IBC in steering the growth and upgrading of clusters, it can also be argued that IBC governance changes through a gradual decreasing in the intervention to stimulate IBC, from a ‘coordinated effort’ in the early stage to a spontaneous increase in the marketdriven process of IBC as an ‘organic process’ in the mature stage of cluster development. This study has important implications for understanding cluster connectivity, the role of governance in cluster growth and upgrading, and the effective catch-up strategies of emerging economies.

In this paper, I discuss early complexity in the southern Lake Titicaca Basin of the Bolivian Andes. I examine a regional landscape of multi-community formations that emerged during the Late Formative Period (100 BC-AD 500). I suggest that during the Late Formative in the southern Lake Titicaca basin, the establishment of Khonkho Wankane and other disembedded centers, played an important role in the social transformations that ultimately gave rise to centralized political systems. Political activity was undoubtedly an important element of social interaction, but it was enmeshed with ritual and other activities, such as mound construction, and formed an embedded part of more encompassing, large-scale ceremonial encounters. More than they were aggrandizers, those who resided at Khonkho were social and ideological mediators. This case suggests that non-state complexity may be far more variable than most current archaeological models propose. / En este artículo se discute la complejidad temprana en la cuenca sur del lago Titicaca, en los Andes bolivianos. Se estudia un paisaje regional con formaciones de carácter multicomunal que surgieron durante el Periodo Formativo Tardío (100 a.C.-500 d.C.). Se sugiere que, en esta etapa, el establecimiento de Khonkho Wankane, junto con el de los disembedded centers, es decir, centros con poca población residente, pero a los que llegaban gente en número nutrido para la realización de ceremonias, festines u otras prácticas rituales, tuvo un papel importante en la transformación social que dio origen, por último, a los sistemas políticos centralizados. Sin duda, la actividad política fue un elemento importante de interacción social, pero estuvo involucrada con rituales y otras actividades —tales como la construcción de montículos— que constituyeron una parte primordial de los más influyentes encuentros ceremoniales a gran escala. Más que un conjunto de individuos que deseaban diferenciarse o acumular más poder que los demás (aggrandizers), aquellos que residieron en Khonkho Wankane fueron mediadores sociales e ideológicos. Este caso sugiere que la complejidad no estatal pudo ser mucho más variable de lo que diversos modelos arqueológicos proponen en la actualidad.

Summaries in Afrikaans and English / Ontluikende geletterdheid is waarskynlik die belangrik:ste tema wat in hierdie proefskrif behandel word. Die doelbewuste skepping van ouderdomsrelevante geleenthede vir die kleuter om op 'n informele wyse blootstelling en deelname aan luister- praat-, lees- en skryfvaardighede te ervaar, dien as vertrekpunt. Vroee ontwikkeling van geletterdheidsvaardigbede, as komponent van kognitiewe ontwikkeling by die kleuter, bet geblyk noodsaaklik te wees- nie net ten aansien van skoolgereedheid nie, maar ook ten opsigte van sy uiteindelike selfverwesenliking. Die oogmerk strek dus verder as die afiigting van die kleuter tot 'n toereikende vaardigbeidsvlak ten einde skoolgereed te kan wees. In teenstelling met die lank bestaande beleid in Suid-Afiika, wat bepaal bet dat voorskoolse onderwys byna uitsluitlik die onderrig van perseptuele vaardigbede moes bebels, word 'n alternatiewe benadering m hierdie proefskrif aangedui. Hulpverlening met geletterdheidsontwikkeling as doelwit behels waarskynlik 'n meer omvattende scenario ten einde die beboeftes van die affektief-, kognitief-, sosiaalwordende kind aan te spreek. Ontsluiting van 'n nuwe wereld van kennis waardeur nonne, boudings en vaardighede aangeleer word, bet 'n direkte invloed op die kwaliteit van sy totale lewe. By uitnemendbeid skep uitkomsgerigte onderwys die geleentbeid om reeds op voorskoolse vlak, geletterdbeidsvaardigbede op 'n informele wyse aan te leer. Die mite dat primere skole aileen die voorreg beskore is om leerders te leer lees en skryf, word krities in hierdie studie bevraagteken. Die klemverskuiwing is reeds sigbaar in die nuut-aangekondigde onderwysbeleid naamlik dat die leerprogram Geletterdheid minstens sowat 40% van die daaglikse onderrigprogram in die grondslagfase moet geniet. Die wyse waarop geletterdheidsvaardighede aangeleer kan word, word indiepte bespreek. Eweneens word belangrike prosesse waardeur die ontwikkeling van 'n fonologiese-, semantiese- en sintaktiese bewussyn, aan die orde gestel. Die aanleer van geletterdheidsvaardighede blyk nie alleen noodsaaklik te wees vir die ontwikkeling van lewensvaardighede nie dit bewerkstellig toegang tot en die begryping en belewing van die werklikheid wat die mens omring. / Emergent literacy is probably the most important theme addressed in this thesis. The purpose is to create age related opportunities for the pre-school child to experience exposure and participation in listening-, vocal-, reading- and writing abilities on an informal basis which serves as a point of departure. Early awareness of literacy abilities as a component of cognitive development of the pre-school child has proved to be essential - not only in respect of school readiness, but also with regard to ultimate selfactualisation. The aim therefore goes beyond the mere training of the pre-school child to an adequate level of competence to be well prepared for formal schooling. Contrary to the well established policy in South Africa which determined that pre-school education should be limited to the exclusive teaching of perceptual abilities, an alternative approach has been considered in this thesis. Assistance with a view to literacy development probably encompasses a more inclusive scenario in order to address the requirements of the emotional, cognitive and social developing pre-school child. Exposure to a new world of knowledge through which norms, attitudes and abilities are acquired, has a direct influence on the quality of his total life. Outcomes based education provides an excellent opportunity to acquire already at pre-school level, literacy skills on an informal basis. The myth that only primary schools have been allotted the privilege to teach learners to read and write, is being critically questioned in this study. The change in emphasis is already evident in the recently announced education policy, namely that the daily learning programme Literacy must include at least 400/o of the foundation programme phase. The manner in which literacy skills can be acquired are discussed in depth. Simultaneously Literacy must include at least 400/o of the foundation programme phase. The manner in which literacy skills can be acquired are discussed in depth. Simultaneously important processes affecting the development of a phonological, semantic and syntactic cognition are discussed. The acquisition of literacy skills appears not only to be important to the development of life skills - it accomplishes access to and the comprehension of as well as the perception of the reality surrounding man. / Psychology of Education / D. Ed. (Sielkundige Opvoedkunde)