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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Climate change and ecological systems : a conceptual framework for the understanding of socio-hydrological dynamics

Woyessa, Y.E., Welderufael, W.A. January 2011 (has links)
Published Article / A functioning ecological system results in ecosystem goods and services which are of direct value to human beings. Ecosystem services are the conditions and processes which sustain and fulfill human life, and maintain biodiversity and the production of ecosystem goods. However, human actions affect ecological systems and the services they provide through various activities, such as land use, water use, pollution and climate change. Climate change is perhaps one of the most important sustainable development challenges that threaten to undo many of the development efforts being made to reach the targets set for the Millennium Development Goals. Understanding the provision of ecosystem services and how they change under different scenarios of climate and biophysical conditions could assist in bringing the issue of ecosystem services into decision making process. Similarly, the impacts of land use change on ecosystems and biodiversity have received considerable attention from ecologists and hydrologists alike. Land use change in a catchment can impact on water supply by altering hydrological processes, such as infiltration, groundwater recharge, base flow and direct runoff. In the past a variety of models were used for predicting land-use changes. Recently the focus has shifted away from using mathematically oriented models to agent-based modelling (ABM) approach to simulate land use scenarios. The agent-based perspective, with regard to land-use cover change, is centred on the general nature and rules of land-use decision making by individuals. A conceptual framework is being developed to investigate the possibility of incorporating the human dimension of land use decision and climate change model into a hydrological model in order to assess the impact of future land use scenario and climate change on the ecological system in general and water resources in particular.
2

The persistence of life measured by carbon cycling in closed ecological systems

Obenhuber, Donald C January 1986 (has links)
Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1986. / Bibliography: leaves 119-129. / Photocopy. / viii, 129 leaves, bound ill. 29 cm
3

An analysis of turnover times in a lake ecosystem and some implications for emergent properties

Watson, Vicki J., January 1976 (has links)
Thesis--Wisconsin. / Includes bibliographical references (leaves 105-110).
4

An investigation into the social factors that influence sport participation : a case of gymnastics in the Western Cape

Lucas, Warren Covelé January 2015 (has links)
Magister Artium (Sport, Recreation and Exercise Science) - MA(SRES) / Gymnastics is a sport code that develops basic motor skills, hand-eye coordination and provides participants with an opportunity to socialize and learn new skills. There are various social factors, such as a family’s socioeconomic status or accessibility to sports facilities that may play a role in affecting levels of participation. The aim of this study is to investigate the social factors that have an influence on gymnastics participation in the Western Cape. To this end, a qualitative approach is adopted to collect data. This study also adopts the ecological systems theory (Bronfenbrenner, 1995) as the theoretical framework, and is used to analyse and interpret current social factors that directly or indirectly influence participation in gymnastics. The study’s objectives were to ascertain which social factors hinder participation, and which social factors promote participation, thus, coaches, parents and gymnasts participated in focus group discussions. Key informant interviews took place with experts in the field of gymnastics in the Western Cape. A thematic analysis was conducted on transcriptions from the focus group discussions and key informant interviews. Social factors investigated in this study occurred in the chronosystem, macrosystem, exosystem, mesosystem, and microsystem, and had both a direct and indirect influence on the gymnast’s continued participation. These systems are defined by Bronfenbrenner (1995), as the environment of the individual, in which they grow and develop. The research findings of this thesis are used to draw conclusions and make specific recommendations for practice and further research. The information gathered in this study can assist all stakeholders within the field of gymnastics, such as parents, judges, coaches, gymnasts, and the supporting community which surround the participating gymnast.
5

Real time system design using personal computer

Srivastava, Sameer, 1959- January 1988 (has links)
This thesis dwells on the issue of using personal computers in real-time control and data acquisition applications. A data acquisition and control system is designed to acquire temperature, humidity, air volume and solar radiation data and control the inside temperature, air volume and maximizes solar radiation inside an ecologically closed test structure. The focus is on an Intel 8088 or 80286 based personal computer. A personal computer is used for development of the software and the final real-time system runs on a PC as well. This eliminates the need of expensive cross compilers and in-circuit emulators. A control and data acquisition task is selected and a solution using an IBM compatible personal computer is demonstrated. Various advantages and disadvantages for selecting the personal computer and development software and environment are discussed. Solutions to various problems encountered are discussed.
6

Exploring power in the theory and practice of resilience

Lyon, Christopher January 2017 (has links)
This thesis explores the question of how social power is accounted for in the theory and practice of resilience. Beginning with a critical assessment of the social ecological systems (SES) perspective that underpins much of the theory and study of resilience, this thesis develops a framework, based on Gaventa’s powercube, for understanding power that also incorporates a much less hierarchical understanding of the dimensions of space and time. This revised ‘powerplane’ framework is applied to two empirical case studies of practices of resilience. Applying the powerplane to the case of government-led Scottish community emergency resilience planning finds that while the practices of resilience result in greater levels of engagement and interaction between local and regional levels of government, a gap exists between local government and the public it represents. Applying the powerplane to the grassroots case of Transition Town Peterborough, Canada, shows that intimate knowledge of local social and political institutions can allow a grassroots organisation to introduce resilience ideas into social and political community life. Together the two case studies reveal three key insights from resilience practices aimed at local contexts, rooted in: (1) institutionalising community engagement practices; (2) differences between formal and informal understandings of resilience; and (3) the scope of the risks resilience is aimed at mitigating. Critically exploring these issues in turn helps to illuminate questions about the efficacy, as well as the social and political implications of the resilience practice in question. For theory, the research shows that reconsidering hierarchical notions of scale and time in SES resilience can provoke new thinking about the role of power in resilience practices. In doing so, insights from this research offer novel challenges and complementarities to they way existing critiques of resilience approaches to account for social power issues.
7

An Analysis of Population Connectivity in Lotic Fauna: Constraints of Subdivision for Biotic Responses to Stream Habitat Restoration

Cook, Benjamin Douglas, n/a January 2007 (has links)
Connectivity in ecological systems is a broad concept that embodies the transmission of ecosystem components throughout landscapes at multiple spatial and temporal scales. Of relevance to the present study are the connections (or lack thereof) among local populations of stream fauna - population connectivity in lotic systems. Dispersal, recolonisation and migration are the demographic forms of population connectivity, and gene flow is the genetic aspect of population connectivity. Both forms of population connectivity have underpinned some of the classic theories and hypotheses in stream ecology, and have implications for pure and applied stream ecology, including ecosystem restoration. Conceptual models in ecology can facilitate understanding and predictability of the ecosystem processes they represent, and have potential applicability as management tools or 'rules of thumb' in conservation and restoration programs. Various theoretical models describe potential patterns of connectivity among local populations and in this thesis these models were used to evaluate population connectivity in a freshwater fish (southern pygmy perch, Nannoperca australis) and two reproductively isolated genetic lineages of freshwater shrimp (Paratya spp.) in small, geomorphically degraded streams in south eastern Australia. These streams (the Granite Creeks) have been the focus of a recent habitat restoration trial and several studies have examined fish and macroinvertebrate community responses to the experiment. It was the purpose of this study to contribute information about population connectivity in the selected species to complement these community ecology studies. Population connectivity was examined in these species using molecular data (mitochondrial and nuclear genetic data) and natural abundance isotopic signatures of nitrogen and carbon. At the landscape scale, results showed that populations of N. australis and the P. australiensis lineages were isolated among the streams and among sites within streams, and that there was no consistent pattern of isolation-by-distance in genetic data for any species. Thus, classic models of population connectivity, such as the Island Model and Stepping-Stone Model, were not supported by this study. Results indicated that population models that incorporated more complex aspects of stream structure may be more appropriate than these classic models for approximating observed patterns of population connectivity in lotic systems. The Stream Hierarchy Model (SHM) predicts that the hierarchical aspect of stream structure (i.e. stream confluences) have a dominant role in shaping patterns of population connectivity in lotic fauna, whereby populations among streams are more isolated than those within them. Although stream confluences were found to have an important role in population subdivision for the species examined in this study, the expectations of the SHM were met for only N. australis. For the P. australiensis lineages, the influence of topography (i.e. the longitudinal aspect of stream structure) was just as important as stream confluences in isolating local populations. Large-scale determinants of population isolation were thus found to be associated with both the hierarchical and longitudinal aspects of stream structure, and were not well represented by any single theoretical model of population connectivity. At within-stream scales, upland populations tended to be extremely isolated from other populations and had temporally stable genetic signatures. In contrast, lowland populations were connected to other lowland populations within the same stream to a greater degree, although the connections were patchy and a slight signature of temporal instability in the genetic data was evident for one of the P. australiensis lineages. Thus, metapopulation or patchy population models were found to represent connections among lowland populations within the same stream, although they were not appropriate for describing connectivity among upland populations. This finding highlights the importance of the longitudinal aspect of stream structure in shaping ecological patterns in lotic systems, and demonstrates that local patterns of population connectivity can vary over relatively small spatial scales. Overall, the results illustrate that both hierarchical and longitudinal aspects of stream structure can have important roles in isolating populations of stream fauna. They therefore also represent constraints for the ability of aquatic fauna to colonise restored habitat in streams. The corollary of this, however, is that such isolated populations of stream fauna represent appropriate population units at which to target habitat restoration. The hierarchical and longitudinal aspects of stream structure may thus represent 'rules of thumb' or 'landscape filters' that stream restoration ecologists could use to predict likely isolated populations of lotic fauna across the landscape. Such a 'rule of thumb' might be the inclusion of multiple isolated population units in restoration programs, as this strategy is likely to generate the greatest biological response to the restoration at the landscape scale, particularly with respect to intra-specific genetic diversity captured by restoration. At small spatial scales, such as for a single stream or tributary, the longitudinal aspect of stream structure can be an important factor to consider when designing stream habitat restoration programs. In this study, lowland sites were unstable and there were patchy connections among local lowland populations within the same stream, whereas upland populations were isolated at this scale. In contrast, other studies have found that upstream populations of some species can be connected in a patchy fashion in other systems. For such unstable sections of stream, where there are patchy patterns of local population connectivity, the inclusion of multiple restored patches, especially refugial habitat, is likely to produce the greatest biotic response at the patch scale, particularly with respect to demographic responses (such as local colonisation). Multiple restored refugial patches will enable species to persist throughout the stream section during adverse environmental conditions, will allow for variation in local movement patterns and distances between species and between years with contrasting environment conditions (e.g. stream flow), and may harbour different species assemblages and intraspecific genotypes due to stochastic processes (i.e. have functional heterogeneity). The hierarchical and longitudinal aspects of stream structure are thus important determinants of population connectivity at both large and small spatial scales, and have implications for how stream biota will respond to restoration at patch and landscape scales.
8

Implementation of the European network: Natura 2000 : Determined according to overarching EU directives or through compromising ecological aspects?

Westfahl Backlund, Martina January 2008 (has links)
<p>Global biodiversity is currently being lost at an unprecedented rate, posing a threat to vital ecosystems and hence the generation of ecosystem services that human society is entirely reliant upon. Within the European Community, the EU has set a target of halting biodiversity loss within the territory by 2010. This goal is intended to be operationalized by the implementation of the Habitats Directive and the Birds Directive. These directives constitute the framework for the establishment of a coherent ecological network, referred to as the Natura 2000 network.</p><p>This study examines and analyses the socio-ecological complexities surrounding the designation of Natura 2000 sites in Östhammar municipality, Sweden. The use of a case study-approach to focus on this area is applied in pursuit of identifying and explaining the inherent intricacies in the designation processes and linking them to the broader global context. Throughout Europe, biodiversity exists in a rich variety of grasslands, but only a few studies have been performed to establish appropriate conservation management strategiesrequired for each habitat. This study makes a significant contribution towards shedding light on the Natura 2000 designation process, a phenomenon which has previously been only modestly documented, especially in Sweden. Ecosystem management is discussed and utilized as the theoretical basis for managing ecosystems sustainably, and an important aspect of note is the recognition that the distinction between man and nature needs to be understood as artificial and arbitrary.</p><p>The study explains how social-ecological factors have had a prominent effect on the designation process of Natura 2000 sites. The main determining factor behind the designation process has been the time-constraints, which have affected the designation of SCIs as well as the interaction between the Uppsala CAD and local stakeholders. The lack of adequate participatory approaches used during this process has heightened the risk of compromising the aim of the network: to achieve Favourable Conservation Status (FCS) for natural habitat types as well as species.</p> / <p>Biodiversiteten världen över minskar i en tidigare aldrig skådad hastighet vilket resulterar i ett hot mot fundamentala ekosystem, samt dess produktion av de ekosystemtjänster som det mänskliga samhället är beroende av. På grund av detta har EU satt upp målet att stoppa förlusten av biodiversitet inom unionens gränser tills 2010. Detta mål skall uppnås genom implementeringen av Habitat- och Fågeldirektivet. Dessa direktiv utgör ramen för etableringen av ett sammanhängande ekologiskt nätverk, det så kallade Natura 2000 nätverket.</p><p>Denna studie utreder samt analyserar de socio-ekologiska aspekter som omger utpekandet av Natura 2000 områden i Östhammars kommun, i Uppsala län i Sverige. Genom appliceringen av en fallstudie av området söker denna uppsats att identifiera samt förklara inneboende svårigheter i processen av dessa utpekanden, samt att sätta dem i ett globalt sammanhang. Inom Europa existerar biodiversitet bland annat i olika typer av ängar, dock har endast ett fåtal studier tagit sig an uppgiften att formulera anpassade förvaltningsstrategier för dessa habitat. Denna studie bidrar till att sprida ljus över implementeringen av Natura 2000, ett fenomen som tidigare endast studerats i blygsam utsträckning, speciellt i Sverige. Den teoretiska grunden utgörs ekosystemansatsen, som appliceras för att utvärdera ett uthålligtförvaltande av ekosystem. Vidare understryks vikten av att betrakta ekosystem och mänsklig aktivitet som ett och samma system, och att synen på dem som skilda system bör anses artificiell och motsägelsefull.</p><p>Denna uppsats förklarar hur socio-ekologiska aspekter har påverkat utpekandeprocessen av Natura 2000-områden i Östhammars kommun. De avgörande faktorerna bakom detta är en identifierad tidsbrist, vilket har influerat utpekandet av områden av gemenskapsintresse samt interaktionen mellan Länsstyrelsen i Uppsala och lokala markägare. Bristen på samverkan och information har resulterat i en förhöjd risk av att målet med nätverket inte kommer att nås: att åstadkomma gynnsam bevarandestatus för arter och habitat.</p>
9

Implementation of the European network: Natura 2000 : Determined according to overarching EU directives or through compromising ecological aspects?

Westfahl Backlund, Martina January 2008 (has links)
Global biodiversity is currently being lost at an unprecedented rate, posing a threat to vital ecosystems and hence the generation of ecosystem services that human society is entirely reliant upon. Within the European Community, the EU has set a target of halting biodiversity loss within the territory by 2010. This goal is intended to be operationalized by the implementation of the Habitats Directive and the Birds Directive. These directives constitute the framework for the establishment of a coherent ecological network, referred to as the Natura 2000 network. This study examines and analyses the socio-ecological complexities surrounding the designation of Natura 2000 sites in Östhammar municipality, Sweden. The use of a case study-approach to focus on this area is applied in pursuit of identifying and explaining the inherent intricacies in the designation processes and linking them to the broader global context. Throughout Europe, biodiversity exists in a rich variety of grasslands, but only a few studies have been performed to establish appropriate conservation management strategiesrequired for each habitat. This study makes a significant contribution towards shedding light on the Natura 2000 designation process, a phenomenon which has previously been only modestly documented, especially in Sweden. Ecosystem management is discussed and utilized as the theoretical basis for managing ecosystems sustainably, and an important aspect of note is the recognition that the distinction between man and nature needs to be understood as artificial and arbitrary. The study explains how social-ecological factors have had a prominent effect on the designation process of Natura 2000 sites. The main determining factor behind the designation process has been the time-constraints, which have affected the designation of SCIs as well as the interaction between the Uppsala CAD and local stakeholders. The lack of adequate participatory approaches used during this process has heightened the risk of compromising the aim of the network: to achieve Favourable Conservation Status (FCS) for natural habitat types as well as species. / Biodiversiteten världen över minskar i en tidigare aldrig skådad hastighet vilket resulterar i ett hot mot fundamentala ekosystem, samt dess produktion av de ekosystemtjänster som det mänskliga samhället är beroende av. På grund av detta har EU satt upp målet att stoppa förlusten av biodiversitet inom unionens gränser tills 2010. Detta mål skall uppnås genom implementeringen av Habitat- och Fågeldirektivet. Dessa direktiv utgör ramen för etableringen av ett sammanhängande ekologiskt nätverk, det så kallade Natura 2000 nätverket. Denna studie utreder samt analyserar de socio-ekologiska aspekter som omger utpekandet av Natura 2000 områden i Östhammars kommun, i Uppsala län i Sverige. Genom appliceringen av en fallstudie av området söker denna uppsats att identifiera samt förklara inneboende svårigheter i processen av dessa utpekanden, samt att sätta dem i ett globalt sammanhang. Inom Europa existerar biodiversitet bland annat i olika typer av ängar, dock har endast ett fåtal studier tagit sig an uppgiften att formulera anpassade förvaltningsstrategier för dessa habitat. Denna studie bidrar till att sprida ljus över implementeringen av Natura 2000, ett fenomen som tidigare endast studerats i blygsam utsträckning, speciellt i Sverige. Den teoretiska grunden utgörs ekosystemansatsen, som appliceras för att utvärdera ett uthålligtförvaltande av ekosystem. Vidare understryks vikten av att betrakta ekosystem och mänsklig aktivitet som ett och samma system, och att synen på dem som skilda system bör anses artificiell och motsägelsefull. Denna uppsats förklarar hur socio-ekologiska aspekter har påverkat utpekandeprocessen av Natura 2000-områden i Östhammars kommun. De avgörande faktorerna bakom detta är en identifierad tidsbrist, vilket har influerat utpekandet av områden av gemenskapsintresse samt interaktionen mellan Länsstyrelsen i Uppsala och lokala markägare. Bristen på samverkan och information har resulterat i en förhöjd risk av att målet med nätverket inte kommer att nås: att åstadkomma gynnsam bevarandestatus för arter och habitat.
10

How children create and use social capital : a test of an ecological-transactional model

Walker, Jessica Wolf Thornton 17 July 2012 (has links)
The aims of this study were to examine the relations among social capital, human capital, economic capital, and children’s socioemotional well-being during the transition from late childhood to early adolescence and to test an ecological-transactional model of children’s social capital. This work was informed by sociological and economic theory on social capital, human capital, and economic capital (e.g., Becker, 1993; Bourdieu, 1986; Coleman, 1988; Foster, 2002) and two principal frameworks in developmental psychology: ecological systems theory (Bronfenbrenner & Morris, 1998) and the transactional model of child development (Sameroff, 2009). Social capital was conceptualized as both a family-level and a community-level phenomenon, distinguishing between family social capital and community social capital. A major hypothesis was that family social capital and community social capital, alongside family-level human capital and economic capital, are associated with low levels of socioemotional problems. Family-level variables were considered to be nested within the more distal ecological context of community social capital, and the indirect relation of community social capital to socioemotional well-being through family social capital was also considered. Another postulation was that children’s socioemotional well-being and the social capital that inheres in family relationships (i.e., family social capital) are mutually influential, changing over time in a transactional manner. In this vein, children were regarded as agents of social capital, both “creating” and utilizing it to their developmental benefit (or detriment as the case may be). These family-level transactional processes were nested within the context of community social capital. Results indicated that community social capital had little association with family social capital and children’s socioemotional well-being as indexed by internalizing and externalizing problems. However, caregivers’ human capital and economic capital were significant predictors of family social capital. In turn, family social capital was strongly related to socioemotional problems. Notably, harsh parenting behavior, a measure indicative of the health of the caregiver-child relation and thus the potential for social capital to be realized in their interactions, was the strongest predictor of socioemotional well-being. / text

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