Ongoing climate change has emerged as a major scientific challenge in the current century. Grassland ecosystems are considered net carbon (C) sinks to mitigate climate change. However, they are in turn, influenced by climate change and management practices, providing feedback to climate change via soil microbial community and biogeochemical fluxes. In this thesis, I examined the impact of warming, altered precipitation, and defoliation on soil microbial composition and function, C and N dynamics, and fluxes in soil respiration (CO2), nitrous oxide (N2O) and methane (CH4), together with other belowground ecosystem functions, within two ecosites in a northern native temperate grassland in central Alberta, Canada, over a two-year period. Fungi-to-bacteria ratio was not affected by climatic parameters or defoliation, indicating a high degree of resistance in the below ground community to the treatments imposed. However, C substrate utilization was influenced by warming and defoliation, as was soil microbial biomass. In contrast, soil respiration (or C loss) was not. Soil respiration acclimatized rather quickly to warming, and N2O and CH4 effluxes showed minor responses to warming at both ecosites, regardless of defoliation. These results suggest warming is unlikely to lead to positive climate change feedback due to soil-based responses, regardless of ongoing land use. However, altered precipitation ( 50%) demonstrated greater impacts on C and N fluxes relative to warming and defoliation. Increased precipitation stimulated soil C loss to the atmosphere, potentially generating positive feedback for climatic warming in this northern temperate grassland. / Soil Science

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Thesis Ph.D. ((Applied Mathematics)) -- University of Limpopo, 2022 / The world is under threat from the devastating effects of the continued depletion of the Ozone layer. Increased global warming is causing catastrophic ecological damage and imbalance due to accelerated melting of glaciers, rampant runaway veld res, widespread floods and other extreme events. The delegates to the Cop26 Climate Change Summit were reminded that the continued burning of fossil fuels is releasing carbon into the atmosphere at an unprecedented pace and scale and that the world is already in trouble. Complete substitution of fossil fuels with clean energy sources is the only solution through which the world can be saved from the deleterious effects of global warming. However, total dependence on renewable energy sources can only be possible through novel technology that enables efficient energy utilization and conservation. For instance, the evolution of advanced techniques in manufacturing processes has led to the reduction in the size of various industrial and engineering designs that consume reduced amounts of energy. Efficient energy utilization in thermo-fluid flow systems can be achieved through entropy generation minimization. Entropy is a thermodynamic quantity that represents the unavailability of a system's thermal energy for conversion into mechanical work. In this study, thermodynamic analysis of reactive variable properties third-grade fluid flow in channels with varied geometries and subjected to different physical effects was investigated with the second law of thermodynamics as the area of focus. Entropy generation and inherent irreversibility analysis were the main focus of the study where the sensitivities of these quantities to the embedded parameters were numerically and graphically described and analysed. The semi-analytic Adomian decomposition method, the semi-implicit fi nite difference scheme and the spectral quasilinearisation method were employed to solve the nonlinear differential equations modelling the flow systems. The results reveal that the effects of the parameters on flow velocity, fluid temperature, entropy generation and inherent irreversibility cannot be neglected. In particular, conditions for entropy generation minimization were successfully established and documented. / University of Limpopo

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Neste trabalho, desenvolve-se um método de fronteira imersa para o estudo de escoamento compressível modelado pelas equações de Euler bidimensionais. O método de discretização de diferenças finitas é empregado, usando o método de Steger-Warming de ordem dois para discretizar as variáveis espaciais e o esquema de Runge-Kutta de ordem quatro para discretizar as variáveis temporais. O método da fronteira imersa foi empregado para o estudo de aeroelasticidade computacional em uma seção típica de aerofólio bidimensional com dois movimentos prescritos: torsional e vertical, com o objetivo de se verifcar a eficiência do método e sua aplicabilidade para problemas em aeroelasticidade computacional. Neste estudo desenvolveu-se também um programa de computador para simular escoamentos compressíveis de fluido invíscido utilizando a metodologia proposta. A verificação do código gerado foi feita utilizando o método das soluções manufaturadas e o problema de reflexão de choque oblíquo. A validação foi realizada comparando-se os resultados obtidos para o escoamento ao redor de uma seção circular e de uma seção de aerofólio NACA 0012 com os resultados experimentais, para cada caso. / In this work, an immersed boundary method is developed to study compressible flow modeled by the two-dimensional Euler equations. The finite difference method is employed, using the second order Steger-Warming method to discretizate the space variables and the fourth order Runge-Kutta method to discretizate the time variables. The immersed boundary method was employed to study computational aeroelasticity on a typical two-dimensional airfoil section with two prescribed motion: pitching and plunging, in order to verify the efficiency of the numerical method and its applicability in computational aeroelasticity problems. In this work, a computer program was developed to simulate compressible flows for inviscid fluids using the methodology proposed. The verification of the computational code was performed using the method of manufactured solutions and the oblique shock wave reflection problem. The validation was performed comparing the obtained results for flows around a circular section and a NACA 0012 airfoil section with the experimental results, for each case.

Contrasting the day-night variation in thermal landscape, the higher local variation and irregularity on urban surface temperature pattern during daytime was observed and identified by landscape metrics compared with those of nighttime pattern. The diversity and fragmentation metrics had revealed the influence of urban development on the overall urban landscape pattern. Along with urban development, daytime pattern of urban thermal landscape presented more fragmentation, less diversity and uneven texture distribution within daytime observations. / During the process of worldwide urbanization along with high rise and high density housing development in large cities, urban warming has received growing concern among many environmental issues related to urban landscape change. Due to the complicated interplay between urban environment and local climate, it is far from certain about the urban effects on local warming. In this literature, a systematic monitoring and analysis of the spatial dependency and heterogeneity of urban thermal landscape at city scale remains inadequate. The goal of this doctoral research is to develop a research framework incorporating geospatial statistics, thermal infrared remote sensing and landscape ecology to study the urban effect on local surface thermal landscape regarding both the pattern and process. / GWR analysis offered an in-depth investigation of local effect on surface temperature variation which had been proven to be spatially varying and influenced by local weather condition with local environmental setting quantified with the referred site specific environmental factors. The local dominant factor accounted for most to the site specific surface temperature variation which varied significantly in space and time and prevented a general delineation of the relative association among environmental factors to surface temperature disparities. The effective adaptive measures could be devised locally with reference to day-night needs in the identification of this feature. / In summary, global regression analysis confirmed the relationship between environmental factors and surface temperature and gave a general overview of urban effect on local surface warming. The distinctive mechanism of dominating day-night surface warming was uncovered by regression analysis. Vegetation played the most important role which could be referred as surface cooling in average to local surface temperature variation as compared with other measures of local environment during both daytime and nighttime. Besides the dominant role of local solar radiation on surface warming, building square footage demonstrated the second important influence on local surface temperature elevation during daytime. During nighttime, population density played a dominant role on nighttime surface warming among different parameters, with the second important contribution of nighttime surface warming coming from road density. While elevation and distance from coast demonstrated obvious cooling effect on surface temperature within most nighttime models. / Located in a subtropical region, Hong Kong's development with high rise and high density housing made it a suitable site for studying urban effect on local warming. This research chose Hong Kong as the case study which hopes to enrich our knowledge regarding urban local thermal performance and add to our understanding of urban microclimate in hot-humid weather area. / Xue, Yucai. / Adviser: Tung Fung. / Source: Dissertation Abstracts International, Volume: 71-01, Section: B, page: 0185. / Thesis submitted in: September 2008. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 201-228). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese.

Neste trabalho, desenvolve-se um método de fronteira imersa para o estudo de escoamento compressível modelado pelas equações de Euler bidimensionais. O método de discretização de diferenças finitas é empregado, usando o método de Steger-Warming de ordem dois para discretizar as variáveis espaciais e o esquema de Runge-Kutta de ordem quatro para discretizar as variáveis temporais. O método da fronteira imersa foi empregado para o estudo de aeroelasticidade computacional em uma seção típica de aerofólio bidimensional com dois movimentos prescritos: torsional e vertical, com o objetivo de se verifcar a eficiência do método e sua aplicabilidade para problemas em aeroelasticidade computacional. Neste estudo desenvolveu-se também um programa de computador para simular escoamentos compressíveis de fluido invíscido utilizando a metodologia proposta. A verificação do código gerado foi feita utilizando o método das soluções manufaturadas e o problema de reflexão de choque oblíquo. A validação foi realizada comparando-se os resultados obtidos para o escoamento ao redor de uma seção circular e de uma seção de aerofólio NACA 0012 com os resultados experimentais, para cada caso. / In this work, an immersed boundary method is developed to study compressible flow modeled by the two-dimensional Euler equations. The finite difference method is employed, using the second order Steger-Warming method to discretizate the space variables and the fourth order Runge-Kutta method to discretizate the time variables. The immersed boundary method was employed to study computational aeroelasticity on a typical two-dimensional airfoil section with two prescribed motion: pitching and plunging, in order to verify the efficiency of the numerical method and its applicability in computational aeroelasticity problems. In this work, a computer program was developed to simulate compressible flows for inviscid fluids using the methodology proposed. The verification of the computational code was performed using the method of manufactured solutions and the oblique shock wave reflection problem. The validation was performed comparing the obtained results for flows around a circular section and a NACA 0012 airfoil section with the experimental results, for each case.

Bakgrund: Hypotermi innebär en kärntemperatur under 36 °C och är en vanlig komplikation under perioperativa förloppet. Vid anestesi störs kroppens normala fysiologiska temperatureglering. Hypotermi kan leda till flertalet allvarliga komplikationer som kan orsaka ett lidande för patienten samt en ökad kostnad för samhället. Trots att forskning länge visat att preventiva åtgärder minskar risken för hypotermi kvarstår problemet. Syfte: Syftet är att identifiera preoperativa aktiva värmebevarande metoder och vilken effekt dessa har på att minska risken för perioperativ hypotermi hos den vuxna patienten. Metod: En systematisk litteraturstudie valdes som metod för att besvara syftet. Sökningar genomfördes i CINAHL, PubMed och Web of Science. Totalt 19 kvantitativa artiklar inkluderades och data extraherades genom en extraktionsmall. Resultat: Resultatet är sammanfattat i två huvudkategorier, preoperativa aktiva värmebevarande metoder och effekten av preoperativ aktiv värmning på patientens perioperativa temperatur. Fem olika värmebevarande metoder identifierades. Resultatet visar att preoperativa aktiva värmemetoder har en positiv effekt på att minska uppkomst av hypotermi under det perioperativa förloppet. Slutsats: Perioperativ hypotermi kan förebyggas genom ökad medvetenhet hos vårdpersonal kring problemet och genom aktiva värmebevarande metoder under det perioperativa förloppet. / Background: Hypothermia means a core temperature below 36 ° C and is a common complication during the perioperative process. In the event of anesthesia, the body's normal physiological temperature control is disturbed. Hypothermia can lead to a number of serious complications that can cause a patient suffering and an increased cost for society. Although research has long shown that preventive efforts reduce the risk of hypothermia, the problem persists. Aim: The aim is to identify preoperative active heat-saving methods and the effect they have on reducing the risk of perioperative hypothermia in the adult patient. Method: A systematic literature study was chosen as a method of answering the purpose. Searches were conducted in CINAHL, PubMed and Web of Science. A total of 19 quantitative scientific articles were included and data extracted by an extraction template. Result: The result is summarized in two main categories, preoperative active heat-saving methods and the effect of preoperative active warming at the patient's perioperative temperature. Five different heat-saving methods were identified. The result shows that preoperative active heat methods have a positive effect on reducing the appearance of hypothermia during the perioperative process. Conclusion: Perioperative hypothermia can be prevented through increased awareness of healthcare professionals around the problem and through active heat-saving methods during the perioperative process.

Global warming is currently a major challenge facing the world. There are widespread ongoing efforts in the form of summits, conferences, etc., to find satisfactory ways of surmounting this challenge. The basic objective of all such efforts can be summarized as conception and formation of protocols to reduce the pace of global carbon levels. Game theory and mechanism design provide a natural modeling tool for capturing the strategic dynamics involved in global warming related problems. This dissertation explores for the first time the use of voting mechanisms in the context of solving the central problems, namely, allocation of emission caps and reduction quotas to strategic emitting agents (countries). The contribution of this dissertation is two-fold. The first contribution is to develop an elegant game theoretic model that accurately captures the strategic interactions among different emitting agents in a global warming setting. This model facilitates a convenient way of exploring a mechanism design approach for solving important allocation problems in the global warming context. The second contribution is to propose and explore a novel approach, based on voting mechanisms, to solve two problems: (1) allocating emission caps and (2) allocating reduction quotas to strategic agents. Our work investigates the use of voting mechanisms that satisfy four desirable properties: (1) non-dictatorship, (2) strategy-proofness, (3) efficiency, and (4) anonymity. In particular, we explore the median selection, maximum order statistic selection, and general Kth order statistic selection voting mechanisms. Our results clearly show that only trivial allocations satisfy all the above properties simultaneously. We next investigate the use of voting mechanisms for the dual problem, namely, allocation of emission reductions to emitting agents. Here, we show that non-trivial allocations are possible, however an important property, individual rationality, might be compromised. The investigations in the thesis bring out certain limitations in applying voting mechanisms that satisfy all the four properties above. Nevertheless, the insights obtained provide valuable guidelines for solving emission allocation related problems in a principled and informed way.

Northern bobwhite populations have declined concurrent with global warming. The focal period of this study was the 12-d pre-incubation period, when bobwhite eggs remain in the nest without the thermal protection of the incubating parent. This study first established the storage and thermal limits of bobwhite eggs, then investigated how global warming may impact oviparous embryos and how bobwhite embryos react to acute and chronic doses of simulated drought temperatures during pre-incubation. First, the maximum storage limit of bobwhite eggs was determined by storing eggs ≤21 d and measuring hatching success and pH of egg albumen and yolk. Hatching success of stored eggs declined after 14 d, when yolk and albumen pH reached levels detrimental to embryonic development. Secondly, thermal limits were determined by exposing bobwhite eggs to hyperthermic temperatures (38-52 °C). Bobwhite embryos survived 50 °C for 1 h, 49 °C for 3 h and 46 °C for 6 h. Results indicate an adaptation to the naturally occurring temperature extremes that can occur in the bobwhite's southern range during pre-incubation. Subsequently, bobwhite eggs were exposed to either low constant (LC), low fluctuating (LF), high constant (HC), or high fluctuating (HF) temperatures during pre-incubation to determine if the nature of temperatures differentially affected development. Although eggs exposed to high heat loads (HC and HF), and low heat loads (LF and LC) had equal heating degree-hours within groups, they exhibited differential growth during pre-incubation. Oxygen consumption, hatch timing, and hatching success were also affected by the thermal regimes. Eggs in simulated drought (HF) had a 47% lower hatch rate than eggs in simulated non-drought (LF) indicating that thermal stress during pre-incubation may contribute to population declines during drought. Finally, northern bobwhite eggs were exposed to acute or chronic doses of simulated drought temperatures, which tested for critical periods of development during pre-incubation. Collectively, data indicated that the earliest stages of bobwhite development were more affected by hyperthermic temperatures. Indeed, a critical period of development exists during the first 2/3 of pre-incubation during which exposure to hyperthermic temperatures results in aberrant development, hatching plasticity, and reduced hatch rates.