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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.
11

The impact of habitat loss and habitat fragmentation on the survival of the herpetofauna in the southern Mount Lofty Ranges, South Australia /

Sacchi, Marco P. Unknown Date (has links)
Over the relatively short period since European settlement in the 1830’s, the Mount Lofty Ranges (MLR) in South Australia have suffered a precipitous decline of natural habitat. The effects of habitat fragmentation on the herpetofauna of the southern MLR were investigated in a series of forest remnants and provide the thematic background of this thesis which focuses on five separate but thematically interconnected aspects of habitat fragmentation that are presented in separate, semi-autonomous chapters (3-7). / The study confirmed that the original herpetofauna still persists in the southern MLR. Habitat fragmentation apparently did not affect the species richness of the region. However, there are important differences in the occurrences of individual species across the archipelago of forest remnants. The distribution patterns of the herpetofauna in forest remnants of the southern MLR are not random but highly nested. As a consequence of a significant association of species richness with the area, it appears that the proportion of the original forest-dependent reptiles of the MLR that can be preserved in habitat fragments is a direct function of the remnant size. The processes responsible for the observed deterministic extinction patterns appear to be habitat loss and habitat fragmentation. Contrary to many forest-dependent reptiles, most amphibian species are still widespread at the investigated scale and generally appear to be less affected by the effects of forest loss and forest fragmentation in the MLR. / Actual habitat remnancy in the southern MLR is below 13% and with 97.6% of all forest fragments smaller than 100ha, many of the most area-sensitive f orest-dependent reptiles survive in just a handful of remnants that are large enough to support viable populations. Although smaller remnants still support some forest- dependent reptiles, their herpetofauna is generally greatly impoverished. While abundances of most species were too low to estimate expected recapture values in dispersal experiments, crossings of common anthropogenic boundaries by local reptiles appear to be rare events. Where expected recapture values could be estimated, such as for L. guichenoti in a case study, most boundaries did appear to show a filter effect. Differences existed among species and communities in regard to boundary permeability. The results suggest that the extensive road network in the southern MLR, through filter effects (i.e. road mortality) and barrier effects (i.e. edge avoidance), is likely to decrease landscape connectivity. The study further demonstrated the existence of significant edge effects on reptiles. Such edge effects are expected to have a particularly large impact on populations of smaller forest fragments that are mostly or completely ecotonal and, consequently, harbour mostly edge-tolerant forest species and habitat generalists. / The above-mentioned case study of Lampropholis guichenoti demonstrated that this ubiquitous species is naturally abundant not only under relatively pristine conditions, but also in disturbed habitat. The species apparently possesses a variety of biological, ecological and behavioural traits, such as a high degree of ecological plasticity, non-territoriality and klepto-parasitic behaviour that may explain its relatively successful survival in the face of extensive habitat fragmentation in the southern Mount Lofty Ranges. / Findings of this study have clear implications for conservation and restoration planning. Nested subset analysis emerged as a useful analytical tool to identify potential focal species that could serve in the development of a taxon-based surrogate scheme. This multi-species approach could be a simple and cost-effective way to address regional conservation problems when time and resources are limited. A focal-species approach using forest dependent reptiles in a surrogate scheme appears particularly useful for herpetofaunal diversity conservation in forest remnants of the MLR. / Thesis (PhD)--University of South Australia, 2004.
12

Brush cutting and brush fencing : sustainable resource use or environmental impoverishment?

Newland, Nicholas. January 1991 (has links) (PDF)
Includes bibliographical references.
13

Developing an electronic clearing and settlement system for the securities industry of Hong Kong.

January 1992 (has links)
by Bernardette Sau-Mui Loo. / Thesis (M.B.A.)--Chinese University of Hong Kong, 1992. / Includes bibliographical references. / ACKNOWLEDGEMENT --- p.i / PREFACE --- p.ii / TABLE OF CONTENTS --- p.iii / LIST OF FIGURES --- p.v / LIST OF TABLES --- p.vi / Chapter 1 --- EXECUTIVE SUMMARY --- p.1-0 / Chapter 1.1 --- Objectives Of The Study --- p.1-1 / Chapter 1.2 --- Results Of The Study --- p.1-1 / Chapter 1.3 --- Conclusions --- p.1-2 / Chapter 2 --- INTRODUCTION --- p.2-0 / Chapter 2.1 --- Development Of The Hong Kong Securities Industry --- p.2-2 / Chapter 2.2 --- Statement Of Problem And Research Objectives --- p.2-10 / Chapter 2.3 --- Assumptions And Limitations --- p.2-11 / Chapter 2.4 --- Scope Of The Research --- p.2-12 / Chapter 3 --- RESEARCH METHODOLOGY --- p.3-0 / Chapter 3.1 --- Research Strategy --- p.3-2 / Chapter 3.2 --- Data Collection --- p.3-3 / Chapter 4 --- EXISTING SECURITIES CLEARING AND SETTLEMENT SYSTEM____ --- p.4-0 / Chapter 4.1 --- Securities Market Participants --- p.4-2 / Chapter 4.2 --- Physical Delivery Settlement System Overview --- p.4-8 / Chapter 4.3 --- Cost Structure --- p.4-13 / Chapter 4.4 --- Limitations And Drawbacks --- p.4-14 / Chapter 5 --- SECURITIES CLEARING SYSTEM IN OTHER PARTS OF THE WORLD --- p.5-0 / Chapter 5.1 --- Euro-Clear and CEDEL --- p.5-2 / Chapter 5.2 --- Asian Pacific Basin --- p.5-3 / Chapter 6 --- HONG KONG SECURITIES CLEARING COMPANY (HKSCC) --- p.6-0 / Chapter 6.1 --- Company Formation --- p.6-2 / Chapter 6.2 --- Organization Structure --- p.6-3 / Chapter 6.3 --- Top Management Of HKSCC --- p.6-6 / Chapter 7 --- OVERVIEW OF THE PROPOSED CENTRAL CLEARING AND SETTLEMENT SYSTEM --- p.7-0 / Chapter 7.1 --- CCASS Participants --- p.7-2 / Chapter 7.2 --- CCASS Accounts --- p.7-3 / Chapter 7.3 --- Central Securities Depository --- p.7-5 / Chapter 7.4 --- Trade Interface --- p.7-6 / Chapter 7.5 --- Clearing --- p.7-7 / Chapter 7.6 --- Settlement --- p.7-10 / Chapter 7.7 --- Electronic Money Settlement --- p.7-14 / Chapter 7.8 --- Fails Management --- p.7-15 / Chapter 7.9 --- Risk Management and Guarantee Fund --- p.7-16 / Chapter 7.10 --- Common Nominee Registration --- p.7-19 / Chapter 8 --- CCASS OPERATIONS --- p.8-0 / Chapter 8.1 --- Technical Environment --- p.8-2 / Chapter 8.2 --- Work Flow --- p.8-5 / Chapter 8.3 --- Tariff Structure --- p.8-13 / Chapter 8.4 --- Impacts To Participants --- p.8-17 / Chapter 9 --- RISK MANAGEMENT AND GUARANTEE SYSTEM (RMGS) UNDER CCASS --- p.9-0 / Chapter 9.1 --- Principles and Measures --- p.9-3 / Chapter 9.2 --- HKSCC's Guarantee --- p.9-5 / Chapter 93 --- Guarantee Fund --- p.9-6 / Chapter 9.4 --- Settlement Cap --- p.9-8 / Chapter 9.5 --- Securities-on-hold and Money Settlement --- p.9-10 / Chapter 9.6 --- Continuous Surveillance of Brokers --- p.9-12 / Chapter 9.7 --- Recommendations for Improvement on RMGS --- p.9-13 / Chapter 10 --- SHARE REGISTRATION SYSTEM (SRS) UNDER CCASS --- p.10-0 / Chapter 10.1 --- Certificated and Uncertificated Shares --- p.10-2 / Chapter 10.2 --- Mechanics of CCASS --- p.10-3 / Chapter 10.3 --- Registration at Participant-Participant Level --- p.10-4 / Chapter 10.4 --- Registration at Participant-Client Level --- p.10-5 / Chapter 10.5 --- Potential Problems of ccass Share Registration --- p.10-6 / Chapter 11 --- CCASS PROJECT DEVELOPMENT --- p.11-0 / Chapter 11.1 --- Project Cycle --- p.11-2 / Chapter 11.2 --- Financing --- p.11-5 / Chapter 12 --- FUTURE DEVELOPMENT --- p.12-0 / Chapter 12.1 --- Uncertification Of Shares --- p.12-2 / Chapter 12.2 --- Interface In National Language --- p.12-2 / Chapter 123 --- Delivery Versus Payment System --- p.12-3 / Chapter 12.4 --- Extension Of CCASS Services --- p.12-3 / Chapter 13 --- CONCLUSIONS --- p.13-0 / Chapter 13.1 --- Conclusions --- p.13-1 / Chapter 14 --- APPENDICES --- p.14-0 / Chapter 14.1 --- Glossary Of Terms --- p.14-1 / Chapter 14.2 --- Settlement Systems in Asian Pacific Region --- p.14-11 / Chapter 14.3 --- Bibliography --- p.14-12
14

Islanding Operation Strategy of Micro-Grid Systems with Wind Power Generator

Ju, Yi-Jyh 08 July 2009 (has links)
To increase the allowable capacity of wind generation and system reliability of distribution system for islanding operation, an actual Taipower feeder has been selected for computer simulation. The voltage enhancement of distribution feeders with fixed speed wind generator has been obtained by using the static synchronous compensator(STATCOM). The model of Doubly-Fed induction generator(DFIG) in Matlab/Simulink has also been applied in the feasibility study of islanding operation for Taipower feeder. The critical clearing time of fault contingency is solved by considering the low voltage ride through (LVRT) capability of wind generators (WG) and the CBEMA curve of sensitive loads. In this way, feeder circuit breaker(CB) can be tripped in time to achieve islanding operation of distribution feeders without causing the tripping of WG due to voltage disturbance for the system fault contingency. To restore the stable operation of distribution feeders after being isolated from the rest of the power system, an adaptive load shedding scheme has been presented to disconnect the proper amount of system loading to achieve the balance of wind power generation and load demand according to the variations of feeder load profile and wind speed. It is found that system voltage sag problem due to severe fault contingency can be mitigated effectively by using the STATCOM for the support of low voltage ride through capability of WG. With the proper design of protection relay settings for feeder CB tripping and load shedding scheme, the WG and critical loads can be prevented from tripping during transient disturbance to ensure the successful islanding operation of distribution system.
15

Skeletal ontogeny of Monodelphis domestica (Mammalia: Didelphidae) : quantifying variation, variability, and technique bias in ossification sequence reconstruction

Morris, Zachary Stephen 18 February 2014 (has links)
The field of evolutionary developmental biology (evo-devo) focuses on understanding the evolution of ontogeny and mechanisms of evolutionary change. Recently, taxonomic comparisons of the sequence of skeletal ossification have become prominent in evo-devo. However, most of these studies fail to consider two major issues: how the technique used to assay ossification and ontogenetic variation and variability may affect comparisons among taxa. This study focuses on the onset of ossification in the skeleton of Monodelphis domestica and quantifies the affects of variation, variability, and technique bias on reconstructions of ontogeny. Previous comparisons among mammalian taxa have used both computed tomography (CT) and clearing-and-staining (CS) to assess the presence or absence of skeletal elements (i.e., skeletal maturity). In this study, CT and CS were used on the same specimen to compare how these methods assess skeletal maturity. The comparisons of the same individual under reveal significant differences in how skeletal maturity is assessed by CT and CS techniques. Further, significant biases were recovered between techniques. CT is more likely to reveal cranial elements that CS does not, whereas CS is more likely to reveal appendicular elements that CT does not. To assess levels of variation and variability, Ontogenetic Sequence Analysis (OSA) was used to characterize the ontogeny of Monodelphis domestica. This revealed significant levels of variation with over 800 different ontogenetic pathways recovered for the onset of ossification of all skeletal elements studied. Additionally, high levels of variability were also reconstructed because the majority of specimens were found to exhibit non-modal ontogenetic sequences. This variability is more highly concentrated in the sequence of cranial ossification, suggesting potential modularity in ontogenetic variation and variability. Finally, OSA revealed that technique bias could importantly affect reconstructions of skeletal ossification sequences because no identical sequences were recovered by the CT and CS datasets. The results of this study demonstrate the importance of considering the primary nature of developmental studies, the specimen. Only by recognizing and quantifying the complexities of evo-devo research, especially natural variation and methodological biases, can more complete understandings of the evolution of ontogeny be had. / text
16

The contribution of heritage agreements to conservation in the Murray Mallee of South Australia /

Noack, Denise Helen. January 1991 (has links) (PDF)
Thesis (M. Env. St.)--University of Adelaide, Mawson Graduate Centre for Environmental Studies, 1992. / Includes bibliographical references (leaves 141-150).
17

The short-term impacts of burning and mowing on prairie ant communities of the Oak Openings Region

Friedrich, Russell L. January 2010 (has links)
Thesis (M.S.)--University of Toledo, 2010. / Typescript. "Submitted to the Graduate Faculty as partial fulfillment of the requirements for the degree of Master of Science in Biology (Ecology track)." "A thesis entitled"--at head of title. Title from title page of PDF document. Bibliography: p. 38-42 and 51.
18

Organisation und Bedeutung des bargeldlosen Zahlungsverkehrs in der Schweiz /

Krattiger, Jean-Rodolphe. January 1956 (has links)
Diss. Sc. pol. Bern, 1956. / Literaturverz.
19

Análise teórica e experimental sobre incandescência em espécimes de madeira

Rabelo, Elaine Reis de Carvalho [UNESP] January 2003 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:35:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2003Bitstream added on 2014-06-13T20:46:44Z : No. of bitstreams: 1 rabelo_erc_dr_guara.pdf: 6183140 bytes, checksum: d7bd9eecbf970b1f0de95902bb7fa5b8 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Este trabalho trata da combustão sem chama, denominada incandescência, em espécimes de madeira. O estágio de incandescência é muito comum em queimadas florestais, ocorrendo após o período de chamas, quando a biomassa de tamanho maior permanece fumegando por até vários dias. Este material, em estado de incandescência, é foco permanente de emissão de gases tóxicos bem como de re-ignição de biomassa não queimada. Os objetivos principais do trabalho são: verificar experimentalmente os parâmetros que favorecem o início e a continuidade do processo de incandescência e quantificar as concentrações de CO, CO2, O2 e HC durante a queima. Também serão determinadas temperaturas, em diferentes pontos dos corpos de prova, a velocidade da frente de incandescência e, finalmente, a taxa de queima. Os ensaios foram feitos em um forno de 1,80 m de comprimento por 0,60 m de diâmetro, conectado a um controlador de temperatura, com vazões de ar de combustão previamente estabelecidas. Além da vazão de ar, outros parâmetros também variaram, como a temperatura interna do forno, a espécie da madeira, o volume e a umidade da amostra. Para otimizar a execução dos testes foi aplicada a técnica de Projeto de Experimentos. Os ensaios de laboratório foram comparados com os resultados obtidos em uma queimada realizada no interior da floresta Amazônica, no norte do estado de Mato Grosso. / This work investigates non flaming combustion in biomass logs. The process is called smouldering combustion. The occurrence of smouldering is very common in forest fires, where the large sized biomass remains fuming for several days. The material in the state of is a source of toxic gases and of ignition for unburned biomass. The main goals of the work are experimentally check the parameters that favor initiation and permanence of the smouldering process and measure CO, CO2, O2 and HC concentrations during the burning. The velocity of the smouldering front was determined by thermocouples placed in different points of the biomass sample. The average burning rate was also determined. The tests were performed in a furnace of 1.80 m length by 0.60 m diameter. A temperature controller was used to set the desired furnace temperature. The mass flow rate of air was controlled by valves and measured with rotameters. Tests were conducted for different biomass species and sample volumes and moisture contents. To optimize the number of tests the technique Project of Experiments was applied. Results of the laboratory tests agreed well with those obtained in the Amazon forest, in the north of the state of Mato Grosso, Brazil.
20

Tissue clearing and imaging of post mortem human brain - Investigating myelinated and astrocytic fiber pathways in white and grey matter regions of the human brain

Rusch, Henriette 21 June 2024 (has links)
All neuronal circuits of the human brain make up the so-called connectome. Within, three spatial dimensions have been identified, ranging from the microscopic to the mesoscopic to the macroscopic scale. Most studies on connectivity focus on the macroscopic scale by performing magnetic resonance imaging (MRI) in and ex vivo. The bottleneck of this method is the limited resolution accompanied by limited accuracy and validity of 3D MRI data. Thereby, the challenge arises to provide anatomical ground-truth information and create microstructure-informed MRI measurements. One way to overcome these resolution differences between macroscopic and microscopic imaging methods is to generate (sub)cellularly resolved (< 100 nm), mesoscopic tissue blocks (mm-sized). This can be reached, by pairing novel tissue clearing techniques with high-end, large-scale microscopic imaging and is the first goal of the presented thesis. In combining different processing and imaging techniques, that are sensitive to different spatial scales and microstructural properties, a comprehensive understanding of the wiring of the human brain can be generated. Transparency of biological tissue is reached by matching heterogeneous refractive indices (RI) of intra- and extracellular compartments, divided by lipid membranes, to each other and to the RI of their surrounding medium. In doing so, scattering and absorption of light traveling through the sample is reduced. Tissue clearing methods use different approaches to homogenize RI. While hydrophilic and hydrogel-based methods wash out lipids by using strong detergents (e.g., sodium dodecyl sulfate or urea), hydrophobic methods use organic solvents (dibenzylether or ethylcinnamate) to dissolve tissue lipids. The clearing of human brain tissue is particularly challenging as it is densely packed, highly myelinated, and usually aged (i.e., by donors of high age). Initially seven tissue clearing techniques were tested to determine the most efficient one. Efficiency was defined in a high degree of tissue transparency, preserved ability for immunohistochemical staining before or after clearing to obtain highly resolved microscopic imaging results, and short experimental processes. All methods were tested on mm-sized, fixed post mortem brain tissue samples and included the CLARITY, CUBIC, iDISCO, MASH, ECi, Visikol and Ce3D protocol. The CLARITY, CUBIC, iDISCO, and MASH techniques were able to clear aged human brain tissue, whereas the ECi, Visikol and Ce3D techniques were not. Generally, water-based CLARITY and CUBIC methods are gentler than solvent-based iDISCO and MASH techniques. The expansion of CLARITY-treated samples appears to be advantageous as well. However, all technical aspects (i.e., hydrogel pre-treatment, electrophoretic chamber acquisition) of the CLARITY method are time and cost consuming. Here, the iDISCO, MASH, and ECi protocols are more efficient. Their material costs are lower and, if successful, the processing duration is short compared to the CLARITY technique. Although, the Visikol (commercial clearing kit) and Ce3D technique claim to be quickly applied and to clear tissue fast, they are less affordable and more complex to perform as well. After attaining transparency, optical properties of the tissue samples are altered. Hence, the application of immunohistochemistry remains crucial. Microscopic imaging of cleared, immunohistochemically labelled human brain tissue samples revealed that the CLARITY and iDISCO techniques are most suitable. Here, immunohistochemical reagents as well as light penetrated sufficiently deep into the tissue. In addition to the evaluation of different clearing techniques, three microscopic setups, specifically built or equipped for imaging large-scale specimen, were tested to identify suitability, benefits, and downfalls. The results showed that the most suitable and efficient approaches are the combination of i) the CLARITY method coupled with imaging at the Zeiss LSM 880 Airyscan and ii) the iDISCO method coupled with the Miltenyi Biotec Ultramicroscope ll. Both combinations enable three-dimensional histology of aged human brain tissue. There is growing demand for visualizing and examining human cyto- and myeloarchitecture in 3D. Successfully clearing aged human brain tissue whilst preserving its microstructure and ability for immunohistochemical staining will bridge standard histological thin-sectioning (2D) and non-invasive imaging techniques, such as MRI. Once mastered in post mortem human brain blocks in 3D, tools such as fiber tracking and co-localisation are going to provide a powerful tool for multi-modal validation of in vivo microstructure-informed MRI, unraveling the human connectome. Next to unraveling the human connectome based on myelinated axonal fiber pathways, the second goal of this thesis is to investigate the distribution patterns of astrocytes. As they support oligodendrocytes during myelination processes, astrocytes are proposed to be co-localised with myelinated fibers. Revealing their spatial organization offers another great approach to study the wiring of the human brain. Astrocytes are the most common subtype of glia cells in the central nervous system and can serve many functions depending on their interaction partner and surroundings. Those include but are not limited to the regulation of synaptic plasticity, ion and pH homeostasis of neurons and the vasculature. Moreover, astrocytes can adapt morphologically, physiologically, and molecularly during their response to neurodegeneration or demyelination. This remodelling is facilitated, amongst others, by the glial fibrillary acidic protein (GFAP), a cytoskeletal protein and the primary intermediate filament of mature astrocytes. Hence, antibodies against GFAP are commonly and validly used. Furthermore, great heterogeneity occurs among astrocytes with distinguishable morphologies in white matter (fibrous astrocytes) and grey matter areas (protoplasmic astrocytes). Accordingly, GFAP is expressed differently depending on the brain region. Focusing on the co-localisation of myelinated fibers and astrocytes, immunohistochemical analyses were performed to identify myelin- and GFAP-positive structures in aged human cerebral and brainstem areas. Up to three different regions of interest of four different human brains were examined to analyse myelinated fiber and astrocyte content in white and grey matter areas. Subsequently, two image processing approaches were deployed to extract fluorescence intensity values. The first, semi-manual approach, performed with the Zeiss ZEN blue software, generated distribution patterns within a wider range. Hereby, each channel underwent linear unmixing to co-localize the detected fluorescent signals to each other. The second, semi-automated approach, performed with the Segmensation application software, generated distribution patterns within a narrower range. As GFAP dominates in fibrillary astrocytes of white matter regions consistent results were obtained with both image analysis tools. As GFAP expression in grey matter astrocytes is limited, less consistent results were obtained. Therefore, immunohistochemical analyses of different white and grey matter regions of the human brain align with regional distribution patterns of GFAP-positive astrocytes. Remarkably, as proposed in white matter regions, astrocytes and myelinated axons share a similar spatial organization across all investigated regions of interest. In 1992, Suzuki and Raisman first observed this intertwined organization of axons and glial processes in the rat’s brain, coining the term glial framework. The presented thesis confirms this spatial organization of myelinated fibers and astrocytic branches in the human brain. Although this phenomenon was known as well, it was unclear whether this is a global feature. Moreover, the scarcity of studies on the human glial framework, especially in brainstem areas, needs to be acknowledged. This thesis starts to fill the gap, providing evidence for the presence of the glial framework, created by GFAP-positive astrocytes, within white matter regions of cerebral and brainstem areas of the aged human brain. Additionally, the application of immunohistochemistry in cleared, mesoscopic-sized brain tissue samples adds another promising perspective to successfully unraveling the human glial framework globally. As there is growing demand for sensitizing non-invasive imaging techniques to the heterogeneity of astrocytes, studying the spatial organization of myelinated fibers in correlation with astrocytes will provide deeper insights into the impact astrocytes have on neurological integrity and degeneration. Both points of focus of the presented thesis aim to untangle and give a clearer understanding of the human connectome. Myelin, as the primary component of structural and functional integrity of all neuronal fiber pathways, needs to remain the centre of investigations. However, expanding these investigations by studying the glial framework is going to propel our understanding of the human myeloarchitecture forward. Using the coherent approach as is tissue clearing, is a great way to examine structural and functional correlations in 3D and needs to remain a central element of future studies.

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