Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal. / Un des défis actuels en écologie du plancton est de déterminer la contribution relative des processus abiotiques et biotiques dans le contrôle environnemental des communautés planctoniques selon différentes échelles spatiales et suivant un continuum d'hétérogénéité environnementale. Cette thèse répond à ces attentes et vise deux principaux objectifs: (1) déterminer l'hétérogénéité spatiale de la biomasse et de la structure en taille des communautés planctoniques aux échelles intra- et inter-lacs; (2) évaluer la contribution relative des facteurs environnementaux ascendants "Bottom-Up" et/ou descendants "Top-Down" à l'origine de cette hétérogénéité. Afin de répondre à ces objectifs, quatre études ont été réalisées à différentes échelles spatiales intra-lac et inter-lacs. A l'échelle intra-lac, nous avons déterminé dans un lac de tourbière l'influence de la prédation par les invertébrés (Chaoboridae) et de la physico-chimie des eaux sur la distribution horizontale et verticale de la biomasse zooplanctonique et sur sa structure en taille (Chapitre 1). Dans le lac Geai, l'hétérogénéité du zooplancton était aussi importante sur l'axe horizontal que vertical. La prédation était le facteur le plus important influençant la répartition horizontale et verticale du zooplancton. La taille et la densité des Chaoboridae, ainsi que la conductivité des eaux influençaient la répartition horizontale du zooplancton dans le lac. Sur l'axe vertical, la biomasse zooplanctonique diminuait avec la profondeur. Le zooplancton évitait les eaux hypolimnétiques froides et anoxiques où se retrouvaient de fortes densités de gros prédateurs Chaoboridae. La seconde étude à l'échelle intra-lac avait pour objectif d'évaluer dans un lac subalpin les effets de la prédation par les juvéniles de perche (Perca fluviatilis) sur la distribution horizontale et verticale des daphnies et des copépodes cyclopoïdes au cours d'un cycle jour-nuit (Chapitre 2). La répartition horizontale et verticale du zooplancton était inverse à celle des poissons. Sur l'axe vertical, le zooplancton était situé de jour dans l'hypolimnion évitant ainsi la prédation par les juvéniles de perche situés dans les eaux épilimnétiques. Une forte opposition horizontale a été identifiée autant de jour que de nuit. La majorité de la densité zooplanctonique a été enregistrée en zone littorale, tandis que la biomasse de perche était principalement pélagique. Nous avons proposé l'hypothèse que la répartition inverse horizontale et verticale du zooplancton face à leur prédateur était due à la prédation des poissons, ainsi que par leur comportement d'anti-prédation (migrations horizontale et verticale). Au cours de la nuit, les cyclopoïdes qui constituaient le principal item du régime alimentaire des perches, étaient plus abondants dans les eaux métalimnétiques plus froides qui étaient évitées par les jeunes perches. A l'échelle inter-lacs, nous avons testé l'influence de la géologie sur la relation phosphore-chlorophylle a (Chapitre 3). Des modèles phosphore-chlorophylle a déterminant la réponse quantitative de la biomasse algale totale et pour 4 classes de taille (< 3 pin, 3 - 20 pm, < 20 pm, et> 20 pm) face aux gradients de TP ont été établis pour les lacs du sud du Québec. Nous avons finalement évalué l'influence d'autres paramètres physicochimiques sur ces relations. Les lacs étudiés reposait sur un socle granitique caractéristique du bouclier canadien. Ces lacs présentaient des concentrations en chlorophylle a plus faible par unité de phosphore que les lacs retrouvés sur des socles sédimentaires. Les lacs les plus productifs étaient dominés par des algues de grandes tailles (>20 pm), tandis que les algues de petites tailles (< 20 pm) étaient plus abondantes dans les lacs de type oligotrophe. L'identification de l'alcalinité comme variable complémentaire à nos modèles de prédiction a permis de proposer l'hypothèse d'un contrôle algal par broutage par le gros zooplancton herbivore dans les lacs plus productifs et alcalins. Les sources de variations spatiales de la biomasse zooplanctonique ont été quantifiées aux échelles intra- (entre les strates) et inter-lacs (entre les lacs) (Chapitre 4). L'influence des facteurs environnementaux abiotiques et biotiques "Bottom-Up" et "TopDown" sur les variations de la biomasse et de la structure en taille du zooplancton (53-100 pm, 100-202 pm, 202-500 pm, > 500 pm) ont été évalués dans les 3 strates limnétiques des lacs du sud du Québec. La variation de la biomasse zooplanctonique était plus importante entre les lacs qu'entre les strates d'un même lac. Cependant, les variations entre les strates n'étaient pas constantes d'un lac à l'autre. Les facteurs "Bottorn-Up" ont été identifiés comme la plus importante source de variation épilimnétique de la biomasse zooplanctonique entre les lacs. Les facteurs "Top-Down", soit la présence ou l'absence de piscivore dans les lacs, expliquaient la structure en taille des communautés zooplanctoniques ainsi que leur variation verticale (entre les strates). Les lacs où les piscivores étaient absents (dominance des planctivores) présentaient des communautés zooplanctoniques dominées par des petits individus. L'ensemble de ces résultats permet de conclure que l'hétérogénéité des communautés planctoniques augmentent avec l'échelle d'observation. A petites échelles (intra-lac, inter-strates), les facteurs biotiques (prédation) exercent un contrôle sur les communautés planctoniques, tandis qu'à plus grandes échelles (inter-lacs), ce sont les facteurs abiotiques (physico-chimie et morphométrie) qui expliquent en premier lieu la variabilité du plancton. La complémentarité des facteurs abiotiques et biotiques "BottomUp" et biotiques "Top-Down" dans le contrôle des communautés planctoniques est omniprésente quel que soit l'échelle d'observation.

Master of Science / Mercury is the most mysterious planet in the inner Solar System, suggested by observations from the MESSENGER mission. These observations shine a light on potential processes occurring within Mercury as it evolved over time. Scientific instruments aboard MESSENGER indicate that Mercury has a very thin surface layer of broken rocks, a thin crustal layer covered by lavas erupted from a melt formed in a relatively thin, FeO poor mantle, and a large metal rich core made from Fe and some quantity of a light element. These conditions are different than those seen on Earth: a thick crust covered by a layer of varied thickness made up of loose unconsolidated rocks and dust, a large mantle with more FeO, and a smaller core to planet ratio. To understand how these non-Earth like conditions affect how the planet's interior changes with time, a modified evolution model was created to track the changes in heat and chemistry within Mercury. This model accounts for complications like a dynamic core density that changes with a growing inner core, the formation method of the inner core, and the FeO poor mantle composition. Using this model offers illumination on the conditions Mercury experienced after it formed. This model is limited, but results suggest that Mercury's mantle began at an initial mantle temperature of 1600 K, and a mantle reference viscosity of 1021–1022 Pa s, indicating the mantle was less likely to flow easily. Model results also suggest the core contained some sulfur from 0.05–8.9 wt.% S, derived from the MESSENGER data. BepiColombo, a new Mercury mission, will provide some perspectives on the interior of Mercury, leading to more detailed information about conditions present after planetary formation and the effect of non-Earth like conditions on a planet's interior as it cools.

Christian Spirituality, Church History & Missiology

Electrochemical synthesis of straight, separable, cylindrical nanowires for use as cantilevered mechanical resonators is the main focus of this dissertation. These types of nanowires are significant for many applications, but particularly so for chip-based sensor arrays made for ultrasensitive mass detection. Directed-assembly of nanowire-based devices has enabled the development of large-area fabrication of sensor devices with new functions such as cancer detection at early stage. Chemically stable noble metals gold and rhodium are interesting materials for making nanowire resonators. Gold makes a well-known, stable and strong bond with the thiol group, which enables a range of surface functionalization chemistries. Rhodium nanowires have desirable mechanical properties for resonant mass sensing as they can retain high quality factor (Q-factor) from high vacuum to near atmospheric pressures. As a versatile and inexpensive tool, electrodeposition provides the most suitable synthesis path for gold and rhodium resonator-grade nanowires in nanoporous templates. In this work, the structural characteristics of nanoporous membranes anodized aluminium oxide and track-etched polycarbonate was explored for use as electrodeposition template. New chemistries for making gold and rhodium nanowires are introduced. Although gold cyanide-based solutions work well for the electrochemical synthesis of separable nanowires, the toxicity of cyanide solutions makes non-cyanide alternatives desirable. However, electrochemical synthesis of gold nanowires in templates from non-cyanide solutions suffers from serious drawbacks. These include growth-arresting pellet formation, poor length control and defects such as inclusions. In this dissertation, the first electrochemical synthesis of straight, cylindrical, separable gold nanowires from a sulfite-based solution is presented. This work demonstrates a scheme that suppresses electroless particle growth in the weakly-complexed gold in solution by proper use of additives. The electrochemical nucleation and growth of rhodium nanowires from a sulphate-based solution is also discussed. The effect of pH on the length uniformity as well as the effect of EDTA and polyethylenimine as additives on the development of the wire nanostructure was studied. This study has shown that the control over hydrogen co-reduction on the electrode surface and its bubble transport rate allowed for tailoring the nanostructure of the grown nanowires. The control over electrochemical nucleation and growth of noble metal films for nanowire clamping has also been investigated in this work for making reliable defect-free clamps for nanoresonator measurements. Silver was introduced as a reliable replacement for gold for nanowire clamping. Resonance measurements of rhodium nanowires clamped with silver, confirmed a reliable and repeatable clamp with very small scatter in the plot of resonance frequency variation with appropriate geometric terms. In addition, we found that the elastic modulus of a set of rhodium nanowires synthesized and measured in this work, was 14% larger than in previous studies. / Graduate / 0794 / 0548 / mascotella@gmail.com

Thesis (MBA (Business Management))--University of Stellenbosch, 2010.

Humans affect ecosystems by changing species compositions, landscape and climate. This thesis aims to increase our understanding of anthropogenic effects on mesopredator abundance due to changes in apex predator status, landscape and climate. I show that in Eurasia the abundance of a mesopredator, the red fox (Vulpes vulpes), is limited top-down by the Eurasian lynx (Lynx lynx) and bottom-up by winter severity. However, where lynx has been eradicated, fox abundance is instead related to bottom-factors such as cropland (paper I, II). Fox abundance was highest when croplands constituted 25% of the landscape (paper II). I also project red fox abundance in Sweden over the past 200 years and in future scenarios in relation to lynx density, land use and climate change. The projected fox abundance was highest in 1920, when lynx was eradicated and the proportion of cropland was 22%. In 2010, when lynx had recolonised, the projected fox abundance was lower than in 1920, but higher than in 1830. Future scenarios indicated that lynx abundance must increase in respond to climate change to keep fox at the same density as today. The results suggest a mesopredator release when lynx was eradicated, boosted by land use and climate change, and that changes in bottom-up factors can modify the relative strength of top-down factors (paper IV). From 1846-1922, lynx, wolverine (Gulo gulo) and grey wolf (Canis lupus) declined in Scandinavia due to persecution; however I show that the change in wolverine abundance was positively related to the changes in lynx and wolf abundance. This indicates that wolverine is subsidized by carrions from lynx and wolf kills rather than limited top-down by them (paper III). This thesis illustrates how mesopredator abundance is determined by a combination of top-down and bottom-up processes, and how anthropogenic impacts not only can change the structures of predator guilds, but also may modify top-down processes through changes in bottom-up factors. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 3: Submitted. Paper 4: Manuscript.</p><p> </p>

This research investigates eco-clusters as driver for greening regional economic policy and examines necessary incentive structures to foster eco-innovation as well as growth and employment in the eco-industry sector. Eco-clusters are seen in context with sustainability and environmental friendly behavior as means for a socio-ecological transition in the long run. The main hypothesis implies that eco-clusters have to be policy driven and established top-down and therefore differ from cluster structures in other industries. Possible reasons are uncertainty on a developing market as well as external effects of eco-innovations; the latter are seen as radical innovations. Based on theoretic findings for the establishment of clusters and general research findings for eco-clusters and eco-innovations, it is differentiated between a spontaneous cluster emergence from private initiatives through self-reinforcing forces of companies in a region (bottom-up), and the formation of a policy-driven network with primarily regional objectives to stimulate the competitive advantage of the regional industrial location (top-down). The hypothesis will be proofed by empirical results gained through personal interviews and complemented by findings in current research literature. Finally, implications for incentive structures to green economic policy are identified. It is shown that eco-clusters are different to other clusters and crucial for a long-term sustainable change and thus need political commitment and public incentives. For empirical observation, eco-clusters in Austria were selected. This research relates to the ongoing debate on green growth and develops policy incentives for establishment of eco-clusters and thus greening of economic policy. / Series: WWWforEurope

Esta dissertação desenvolveu duas análises de natureza diferente, mas complementares, uma vez que são unidas por uma mesma questão. Esta questão diz respeito à utilização do gás natural veicular em substituição ao óleo diesel em ônibus urbanos. O autor argumenta que, devido a suas características técnicas, o gás natural pode contribuir para a promoção de um transporte mais sustentável, mesmo que o gás natural seja um combustível igualmente não renovável, como o óleo diesel. Na primeira análise desenvolvida, utiliza-se uma metodologia bottom-up para demonstrar os ganhos ambientais que podem ser alcançados ao se substituir o óleo diesel por gás natural em ônibus urbanos. Adota-se a cidade de São Paulo como estudo de caso. Esses ganhos ambientais manifestam-se tanto na redução das emissões de poluentes locais, como material particulado, monóxido de carbono e óxidos de enxofre, conduzindo a melhoras importantes na qualidade de vida das pessoas que sofrem os efeitos nocivos dessas emissões (usuários ou não do transporte público urbano), como, também, no declínio das emissões de gases de efeito estufa, especialmente o dióxido de carbono, levando a benefícios ambientais globais. Os resultados amparam o uso do gás natural em ônibus como uma estratégia de maior sustentabilidade no plano ambiental. Já, na segunda análise desenvolvida, a pesquisa levanta as questões seguintes: Quais outros parâmetros influenciam a decisão de se promover a substituição de combustíveis em ônibus urbanos? Quais critérios explicam as escolhas por distintos combustíveis substitutos? As respostas a essas questões são obtidas através de uma Análise Qualitativa Comparativa (AQC). A pesquisa comparou 39 cidades em todo o mundo, que adotaram combustíveis substitutos ao óleo diesel em ônibus urbanos, incluindo o gás natural, biocombustíveis, eletricidade e hidrogênio. Os resultados atestam que as cidades de fato utilizam-se da substituição de combustíveis para tornar o transporte mais sustentável. Observa-se que a opção pelo gás natural é acolhida na maioria dos casos analisados como uma opção com vantagens ambientais e economicamente mais atrativa. A principal razão para sua eventual não adoção identifica-se com a insegurança energética. Algumas cidades receiam depender de um combustível que, assim como o petróleo (do qual o óleo diesel é um derivado), também está afeito a importantes suscetibilidades geopolíticas. A conclusão do trabalho reforça a importância do gás natural como um combustível ambientalmente mais amigável, e que pode contribuir na busca das cidades por sistemas de transporte público mais sustentáveis, especialmente em grandes áreas metropolitanas. Olhando, especificamente, o caso da cidade de São Paulo, com desdobramentos para o Brasil como um todo, a pesquisa enfatiza a necessidade de se superar barreiras regulatórias, e de se comprovar vantagens econômicas e de segurança de suprimento energético, para que o gás natural possa confirmar-se atrativo e mais sustentável aos olhares dos gestores dos sistemas de transporte público urbanos. Esses temas não podem ser deslembrados ao se propor uma política mais racional de combustíveis para o transporte público das grandes cidades brasileiras. / This work has developed two analyzes of different kinds, but complementary, since they are united by the same issue. This issue relates to the use of compressed natural gas to replace diesel fuel in city buses. The author argues that, due to its technical characteristics, natural gas can contribute to the promotion of more sustainable transport, even though the gas is a non-renewable fuel, such as diesel oil. In the first in-depth analysis, a bottom-up methodology is used in order to demonstrate the environmental benefits that can be achieved by replacing the diesel oil with natural gas in urban buses. The city of São Paulo is adopted as a case study. These environmental gains are manifested both in reducing emissions of local pollutants such as particulate matter, carbon monoxide and sulfur oxides, leading to significant improvements in quality of life of people suffering the harmful effects of the emissions (both public urban transport users and non-users), and also in the decline of emissions of greenhouse gases, especially carbon dioxide, leading to global environmental benefits. The results bolster the use of natural gas buses as a more sustainable strategy in environmental terms. In the second developed analysis, the research raises the following questions: What other parameters influence the decision to encourage the substitution of urban buses in fuels? What criteria explain the choices for different substitute fuels? The answers to these questions are obtained from a Qualitative Comparative Analysis (QCA). The study compared 39 cities across the world that have adopted fuel substitutes to diesel fuel in urban buses, including natural gas, biofuels, electricity and hydrogen. The results show that in fact, cities are use fuel shifting as a way to turn its transport system more sustainable. It is observed that the option for natural gas is considered, in most analyzed cases, as an option with environmental advantages and economically more attractive. The main reason for natural gas non-adoption was identified as energy insecurity. Some cities fear depending on a fuel that, like petroleum (of which diesel oil is a derivative), is also sensitive to relevant geopolitical issues. The conclusion of the work reinforces the importance of natural gas as a more environmentally friendly fuel, and can contribute to the promotion more sustainable public transport systems in cities, especially in large metropolitan areas. Looking specifically at the case of the city of São Paulo, as well as considering Brazil as a whole, the research emphasizes the need to overcome regulatory barriers, and to prove economic benefits and energy supply security, so that the natural gas can confirm is attractive and more sustainable to the eyes of managers of urban public transport systems. These issues cannot be forgotten in order to propose a more rational policy of fuel for public transport in large Brazilian cities.

In a changing climate, it is increasingly important to be able to model environmental effects on food webs, and to do that, one must have appropriate dynamic models. I present a shallow lake ecosystem model where producers, grazers, carnivores, piscivores, and detritivores are coupled through resource (light, nutrients and detritus) fluxes between the benthic and pelagic habitats and through carnivore life history events (ontogenetic habitat and diet shifts). The two habitats each contain primary producers, grazers, carnivores and detritivores. Within the habitats, there is strong top-down regulation, but across habitat boundaries, bottom-up interactions drive production. In the absence of piscivores, stage-structured carnivores cause intriguing patters of alternative stable states. Notably, the model predicts a lesser dependence on benthic production with detritus presence. Model predictions are largely in agreement with empirical studies. The results have implications for management of freshwater, and for the interpretation of previous models.

Esta dissertação desenvolveu duas análises de natureza diferente, mas complementares, uma vez que são unidas por uma mesma questão. Esta questão diz respeito à utilização do gás natural veicular em substituição ao óleo diesel em ônibus urbanos. O autor argumenta que, devido a suas características técnicas, o gás natural pode contribuir para a promoção de um transporte mais sustentável, mesmo que o gás natural seja um combustível igualmente não renovável, como o óleo diesel. Na primeira análise desenvolvida, utiliza-se uma metodologia bottom-up para demonstrar os ganhos ambientais que podem ser alcançados ao se substituir o óleo diesel por gás natural em ônibus urbanos. Adota-se a cidade de São Paulo como estudo de caso. Esses ganhos ambientais manifestam-se tanto na redução das emissões de poluentes locais, como material particulado, monóxido de carbono e óxidos de enxofre, conduzindo a melhoras importantes na qualidade de vida das pessoas que sofrem os efeitos nocivos dessas emissões (usuários ou não do transporte público urbano), como, também, no declínio das emissões de gases de efeito estufa, especialmente o dióxido de carbono, levando a benefícios ambientais globais. Os resultados amparam o uso do gás natural em ônibus como uma estratégia de maior sustentabilidade no plano ambiental. Já, na segunda análise desenvolvida, a pesquisa levanta as questões seguintes: Quais outros parâmetros influenciam a decisão de se promover a substituição de combustíveis em ônibus urbanos? Quais critérios explicam as escolhas por distintos combustíveis substitutos? As respostas a essas questões são obtidas através de uma Análise Qualitativa Comparativa (AQC). A pesquisa comparou 39 cidades em todo o mundo, que adotaram combustíveis substitutos ao óleo diesel em ônibus urbanos, incluindo o gás natural, biocombustíveis, eletricidade e hidrogênio. Os resultados atestam que as cidades de fato utilizam-se da substituição de combustíveis para tornar o transporte mais sustentável. Observa-se que a opção pelo gás natural é acolhida na maioria dos casos analisados como uma opção com vantagens ambientais e economicamente mais atrativa. A principal razão para sua eventual não adoção identifica-se com a insegurança energética. Algumas cidades receiam depender de um combustível que, assim como o petróleo (do qual o óleo diesel é um derivado), também está afeito a importantes suscetibilidades geopolíticas. A conclusão do trabalho reforça a importância do gás natural como um combustível ambientalmente mais amigável, e que pode contribuir na busca das cidades por sistemas de transporte público mais sustentáveis, especialmente em grandes áreas metropolitanas. Olhando, especificamente, o caso da cidade de São Paulo, com desdobramentos para o Brasil como um todo, a pesquisa enfatiza a necessidade de se superar barreiras regulatórias, e de se comprovar vantagens econômicas e de segurança de suprimento energético, para que o gás natural possa confirmar-se atrativo e mais sustentável aos olhares dos gestores dos sistemas de transporte público urbanos. Esses temas não podem ser deslembrados ao se propor uma política mais racional de combustíveis para o transporte público das grandes cidades brasileiras. / This work has developed two analyzes of different kinds, but complementary, since they are united by the same issue. This issue relates to the use of compressed natural gas to replace diesel fuel in city buses. The author argues that, due to its technical characteristics, natural gas can contribute to the promotion of more sustainable transport, even though the gas is a non-renewable fuel, such as diesel oil. In the first in-depth analysis, a bottom-up methodology is used in order to demonstrate the environmental benefits that can be achieved by replacing the diesel oil with natural gas in urban buses. The city of São Paulo is adopted as a case study. These environmental gains are manifested both in reducing emissions of local pollutants such as particulate matter, carbon monoxide and sulfur oxides, leading to significant improvements in quality of life of people suffering the harmful effects of the emissions (both public urban transport users and non-users), and also in the decline of emissions of greenhouse gases, especially carbon dioxide, leading to global environmental benefits. The results bolster the use of natural gas buses as a more sustainable strategy in environmental terms. In the second developed analysis, the research raises the following questions: What other parameters influence the decision to encourage the substitution of urban buses in fuels? What criteria explain the choices for different substitute fuels? The answers to these questions are obtained from a Qualitative Comparative Analysis (QCA). The study compared 39 cities across the world that have adopted fuel substitutes to diesel fuel in urban buses, including natural gas, biofuels, electricity and hydrogen. The results show that in fact, cities are use fuel shifting as a way to turn its transport system more sustainable. It is observed that the option for natural gas is considered, in most analyzed cases, as an option with environmental advantages and economically more attractive. The main reason for natural gas non-adoption was identified as energy insecurity. Some cities fear depending on a fuel that, like petroleum (of which diesel oil is a derivative), is also sensitive to relevant geopolitical issues. The conclusion of the work reinforces the importance of natural gas as a more environmentally friendly fuel, and can contribute to the promotion more sustainable public transport systems in cities, especially in large metropolitan areas. Looking specifically at the case of the city of São Paulo, as well as considering Brazil as a whole, the research emphasizes the need to overcome regulatory barriers, and to prove economic benefits and energy supply security, so that the natural gas can confirm is attractive and more sustainable to the eyes of managers of urban public transport systems. These issues cannot be forgotten in order to propose a more rational policy of fuel for public transport in large Brazilian cities.