Wenige Studien haben erste Hinweise darauf geliefert, dass die insektivore Fledermausart Mops condylurus ein natürliches Reservoir von Ebolaviren sein könnte. Im Rahmen dieser Doktorarbeit wurden weitere Hinweise gesucht, um die Bedeutung dieser Fledermausart als Reservoirwirt für Ebolaviren besser beurteilen zu können. Dafür wurden die Expressionslevel des Membranproteins Niemann-Pick C1 (NPC1), welches essentiell für den Eintritt von Ebolaviren in ihre Wirtszellen ist, in vitro durch konfokale Mikroskopie und Durchflusszytometrie charakterisiert. In dieser Arbeit generierte Primärzellkulturen aus 12 verschiedenen Organen von M. condylurus zeigten für die meisten Primärzellen deutlich niedrigere Expressionslevel als Kontrollzellen von Mensch, Affe oder einer europäischen Fledermaus. Die untersuchte Replikationskinetik von Ebola virus (EBOV) zeigte in allen Primärzellen von M. condylurus niedrigere Replikationsraten, die meistens mit den niedrigen NPC1 Rezeptor-Expressionsleveln korrelierten. Geringere Mengen von NPC1 könnten in vivo zur Virusreplikation auf niedrigerem Niveau beitragen. Desweiteren zeigten alle Primärzellen von M. condylurus eine hohe Toleranz gegenüber EBOV ohne Zelltot. Eine beobachtete Persistenz in Lungenprimärzellen könnte die intrinsische Fähigkeit widerspiegeln, dass Ebolaviren auch in vivo in dieser Fledermausart persistieren könnten. Mit den geringeren NPC1-Rezeptor-Expressionsleveln, der geringeren Virusreplikation, der hohen Toleranz gegenüber EBOV und der Etablierung von persistenten Infektionen in Primärzellen von M. condylurus wurden in vitro zusätzliche Hinweise gewonnen, die die Wahrscheinlichkeit dieser Fledermausspezies als ein mögliches natürliches Reservoir von Ebolaviren erhöht. Ergebnisse von zusätzlichen Temperaturversuchen lassen vermuten, dass die Heterothermie der Fledermäuse einen Schlüsselfaktor für die Toleranz von Ebolaviren in vivo darstellen und darüber hinaus an der Balance zwischen Viruskontrolle und Virusvermehrung beteiligt sein könnte. / Few studies provide first evidence that Mops condylurus, an insectivorous microbat, could be a natural reservoir for ebolaviruses. The aim of this thesis was to investigate indicators to determine the potential role of this bat species in the ecology of ebolaviruses. Therefore, the expression levels of the membrane protein Niemann-Pick C1 (NPC1), essential for the entry of ebolaviruses into their host cells, were characterized in vitro by confocal microscopy and flow cytometry. Our generated primary cell cultures from 12 different organs from M. condylurus showed significantly lower expression levels in most primary cells compared to control cells from human, monkey or a European bat. In most cases, lower Ebola virus (EBOV) replication rates in primary cells from M. condylurus, determined by RT-qPCR, correlated to lower NPC1 receptor expression levels. Low NPC1 receptor expression levels may contribute to decreased virus replication rates also in vivo. Additionally, all primary cells were highly tolerant to EBOV infections without cell death. The observed establishment of persistent EBOV infections in lung primary cells from M. condylurus may reflect the intrinsic ability to persist in vivo in this bat species. With lower NPC1 receptor expression levels, lower virus replication rates, high tolerance to EBOV infections and establishment of persistent infections in primary cells from M. condylurus, the in vitro experiments provided further evidence that this bat species is a potential reservoir of ebolaviruses. Results from additional temperature experiments suggest, that heterothermy of M. condylurus could be a key factor for tolerance to EBOV infections in vivo and be involved in balancing the level of virus replication.

The offshore Sierra Leone basin is an exploration frontier area with commercial hydrocarbon potential. The basin is located at the northernmost end of the equatorial Atlantic margin in the South Atlantic; it is bound to the South by the Gulf of Guinea Petroleum province. The Sierra Leone margin has not had the exploration attention like most basins in the equatorial Atlantic, such lack of attention may be explained by the structural complexity of the basin. Despite the recent successful petroleum activities in the basin, very little geological information have been placed in the public domain by the operators. This research will be the first published detailed analysis of the offshore Sierra Leone basin. This work focuses on the broader aspects of basin structural evolution, seismic stratigraphy and reservoir development. The basin analysis is based on 2D seismic dataset, acquired in 2002 by TGS-NPEC. Seven megasequence boundaries have been identified in the offshore Sierra Leone basin. There is one megasequence boundary each in the pre-transform and syn-transform phases. The post-transform phase is composed of five megasequences. They have been dated using well data information and through correlation with the seismic surfaces of adjacent basins in the region. The Sierra Leone margin is structurally divided into three segments, which evolved through transtensional and/or extensional rifting. From a geological perspective, this basin straddles a major tectonic transition zone (the Sierra Leone Transform). The Mesozoic-Cenozoic tectonic evolution of the basin was partly controlled by basement heterogeneity and plate kinematics. This study also highlights the importance of N-S and ENE-WSW trending Archaean structural lineaments, which were vectors for the Sierra Leone margin segmentation. The structural division of the Sierra Leone margin into the Northern, Central andSouthern segments is based on varying structural geometries. The Northern and Central segments developed as rift-transform margins, while the Southern segment developed as a volcanic rifted margin. Syn-transform sequences (late Early Cretaceous) show the influence of normal fault related subsidence and uplift, modified by localised transpressional deformation. The basin bounding faults and half grabens are oriented at high angles to the ensuing passive margin slope strike. Post-transform sequences (Late Cretaceous to Present) are dominated by major phases of slope failure and the development of extensive lowstand submarine fan systems. Some models of slope failure and synchronous development of submarine channel and canyon systems have been developed for this basin. Extensional slope failure is controlled by pre-existing structural trends. Submarine canyons which developed in the hanging-walls of these fault-blocks, became the site of rapid head-ward expansion of turbidite filled channels. The temporal development of these systems are expected to have profoundly affected the distribution and quality of key play elements, such as reservoirs and stratigraphic traps in slope settings, and the distribution of sands in deeper water and base of slope plays.

Environmental management is plagued with uncertainty, despite this, little attention has until recently been given to the sensitivity of management decisions to uncertain environmental projections. Assuming that the future climate is stationary is no longer considered valid, nor is using a single or small number of potentially incorrect projections to inform decisions. Instead, it is recommended that decision makers make use of increasingly available probabilistic projections of future climate change, such as those from perturbed physics ensembles like United Kingdom Climate Projections 2009 (UKCP09), to gauge the severity and extent of future impacts and ultimately prepare more robust solutions. Two case studies focussing on contrasting aspects of local water management; namely irrigation demand and urban drainage management, were used to evaluate current approaches and develop recommendations and improved methods of using probabilistic projections to support decision making for climate change adaptation. A quantitative understanding of the impact of uncertainty to decision making for climate change adaptation was obtained from a literature review; followed by a comparison of using (1) the low medium and high emission scenarios, (2) 10,000 sample ensemble and 11 Spatially Coherent Projections (11SCP), (3) deterministic and probabilistic climate change projections, (4) the complete probabilistic dataset and sub-samples of it using different sampling techniques, (5) the change factor (or delta change) and stochastic (or UKCP09 weather generator) downscaling techniques and (6) different decision criteria using two contrasting case studies at three UK sites. This research provides an insight into the impact of different sources of uncertainty to real-world adaptation and explores whether having access to more data and a greater appreciation of uncertainty alters the way we make decisions. The impact of the “envelope of uncertainty” to decision making is explored in order to identify those factors and decisions that have the greatest impact on what we perceive to be the “best” solution. An improved novel decision criterion for use with probabilistic projections for adaptation planning is presented and tested using simplified real-world case studies to establish whether it provides a more attractive tool for decision makers compared to the current decision criteria which have been advocated for adaptation planning. This criterion explicitly incorporates the unique risk appetite of the individual into the decision making process, acknowledging that this source of uncertainty and not necessarily the climate change projections, had the greatest impact on the decisions considered by this research. This research found the differences between emission scenarios, projection datasets, sub-sampling approaches and downscaling techniques, each contributing a different source of uncertainty, tended to be small except where the decision maker already exhibited an extremely risk seeking or risk adverse appetite. This research raises a number of interesting questions about the “decision significance” of uncertainty through the systematic analysis of several different sources of uncertainty on two contrasting local water management case studies. Through this research, decision makers are encouraged to take a more active role in the climate change adaptation debate, undertaking their own analysis with the support of the scientific community in order to highlight those uncertainties that have significant implications for real world decisions and thereby help direct future efforts to characterise and reduce them. The findings of this research are of interest to planners, engineers, stakeholders and adaptation planning generally.

Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The investigation of reservoir sedimentation has become an important and valuable research topic in engineering practice. Sediment deposition in reservoirs can affect ood levels, drainage for agriculture land, pumpstation and hydropower operation and navigation. An extensive review of the technical literature pertaining to suspended sediment transports as well as deposited sediment ushing from reservoirs has shown that most studies on sediment are still based on empirical formulas and experimental work, despite the availability of sophisticated computers. This is because sediment transport and particularly sediment deposition and erosion are complex processes, that involve the interaction of many physical factors which are not easily modelled numerically. In addition, most of the existing three-dimensional numerical models are not coupled hydrodynamic and sediment transport models. They first simulate the velocity field and water depth and then the concentration and bed change are calculated. Furthermore, they are not fully three-dimensional models for using layer-averaged approaches in conjunction with Saint-Venant equations. The key objective of the present research was to develop a coupled fully three-dimensional (3D) numerical model based on Navier-Stokes equations which includes both the sediment transport component and hydrodynamic parameters. In this regard, a physical model was set up in a laboratory ume in order to investigate the bottom outlet sediment ushing under pressure in a controlled environment. The proposed coupled fully 3D numerical model was used to simulate the experimental tests. Results from these simulations were in good agreement with the measurements. The geometric features of the scour hole (temporal and spatial hole development) upstream of the bottom outlet were reasonably well predicted compared to the experimental data. Furthermore, the velocity field upstream of the bottom outlet was in good agreement with measurements. The proposed numerical model can be considered reliable provided that the model is correctly set up to reflect the condition of a particular case study. Finally, the coupled fully 3D numerical model for turbulent suspended sediment transport in reservoirs was validated against a range of typical reservoir sediment transport and deposition laboratory flume cases. The proposed suspended sediment transport model successfully predicted both sediment deposition and entrainment processes and therefore, it can be used for turbulent suspended sediment transport assessments in reservoirs. / AFRIKAANSE OPSOMMING: Die ondersoek van damtoeslikking het 'n belangrike navorsing onderwerp in ingenieurswese praktyk geword. Sedimentdeponering in damme kan vloed vlakke, dreinering van landbo grond sowel as pompstasie en hidrokrag werking en navigasie benvloed. 'n Omvattende ontleding van die tegniese literatuur met betrekking tot gesuspendeerde sedimentvervoer asook die spoel van gedeponeerde sediment uit reservoirs het getoon dat die meeste studies oor sediment steeds op empiriese formules en eksperimentele werk gebaseer is, ten spyte van die beskikbaarheid van gesofistikeerde rekenaars. Dit is omdat sedimentvervoer en veral sedimentafsetting en -erosie komplekse prosesse is, wat die interaksie van baie fisiese faktore behels en nie moeiteloos numeries gemodelleer kan word nie. Daarbenewens, in die meeste van die bestaande drie -dimensionele numeriese modelle is die hidrodinamika en sedimentvervoer modelle nie gekoppel nie. Die numeriese modelle simuleer eerstens die snelheid veld en waterdiepte en dan word die sedimentkonsentrasie en bedverandering bereken. Verder is die bestaande modelle nie ten volle driedimensioneel nie, en gebruik laag-gemiddelde benadering in samewerking met Saint- Venant vergelykings. Die hoofdoelwit van die huidige navorsing was om 'n gekoppelde volle drie -dimensionele (3D) numeriese model gebaseer op Navier -Stokes-vergelykings wat beide die sediment vervoer komponent en hidrodinamiese parameters insluit, te ontwikkel. In hierdie verband is 'n fisiese model opgestel in 'n laboratorium kanaal om die bodem uitlaat spoel van sediment onder druk in 'n beheerde omgewing te ondersoek. Die voorgestelde gekoppelde 3D numeriese model is gebruik om die eksperimentele toetse na te boots. Resultate van hierdie simulasies het goed ooreengestem met die metings. Die geometriese eienskappe van die erosie gat (tyd en ruimtelike gatontwikkeling) stroomop van die bodemuitlaat was redelik goed voorspel vergeleke met die eksperimentele data. Verder is die snelheid veld stroomop van die bodem uitlaat ook goed voorspel. Die voorgestelde numeriese model kan beskou word as betroubaar met die wete dat die model korrek opgestel is om die toestand van 'n bepaalde gevallestudie te weerspiel. Ten slotte, is n gekoppelde 3D numeriese model vir turbulente gesuspendeerde sediment vervoer in reservoirs ontwikkel en getoets teen 'n reeks laboratorium kanaal eksperimente. Die voorgestelde gesuspendeerde sediment vervoer model voorspel suksesvol beide die sediment afsetting- en erosieprosesse en daarom kan dit gebruik word vir die simulasie van turbulente gesuspendeerde sediment vervoer in damme.

In the screening and concept selection stages of gas storage projects, many estimates are required to value competing projects and development concepts. These estimates are important because they influence which projects are selected and which concept proceeds into detailed engineering. In most cases, there is uncertainty in all of the estimates. As a result, operators are faced with the complex problem of determining the optimal design. A systematic uncertainty analysis can help operators solve this problem and make better decisions. Ideally, the uncertainty analysis is comprehensive and includes all uncertain variables, and simultaneously accounts for reservoir behavior, facility options, and economic objectives. This thesis proposes and demonstrates a workflow and an integrated optimization model for uncertainty analysis in gas storage. The optimization model is fast-solving and eliminates most constraints on the scope of the uncertainty analysis. Using this or similar workflows and models should facilitate analysis and communication of results within the project team and with other stakeholders. / text

Petroleum and Geosystems Engineering / Production from unconventional reservoirs became popular in the last decade in the U.S. Promising production results and predictions, as well as improvements in hydraulic fracturing and horizontal drilling technology made unconventional reservoirs economically feasible. Therefore, an effective and efficient reservoir model for unconventional resources became a must. In order to model production from such resources, analytical, semi-analytical, and numerical models have been developed, but analytical models are frequently used due to their practicality, relative simplicity, and also due to limited availability of field data. This research project has been accomplished in two main parts. In the first part, two analytical models for unconventional reservoirs, one with infinite hydraulic fracture conductivity assumption proposed by Patzek et al. (2013), while the other one with finite hydraulic fracture conductivity assumption developed by Ozkan et al. (2011) are compared. Additionally, a commercial reservoir simulator (CMG, IMEX, 2012) is employed to compare the results with the analytical models. Sensitivity study is then performed to identify the critical parameters controlling the production performance of unconventional reservoirs. In the second part, naturally and hydraulically fractured unconventional reservoir is considered. In addition, geomechanical effects on natural and hydraulic fractures are examined. A simple analytical dual porosity model, which represents the natural fractures in unconventional reservoirs, is improved to handle the constant bottom-hole pressure production scenario to identify the production performance differences between the cases with and without geomechanical effects. Finally, geomechanical effects are considered for combined natural and hydraulic fractures, and an evaluation of the circumstances in which the geomechanical effects cause a significant production loss is carried out. / text

Opening-mode fractures—joints and veins—are widespread structures in sedimentary rocks even in slightly deformed and flat-lying sequences. Understanding the growth and connectivity of fractures in low permeability sandstone reservoirs is essential for optimal hydrocarbon exploitation. In a linear elastic fracture mechanics framework, it is generally assumed that fractures widen in aperture while they propagate in length or height. However, it is also conceivable that a phase of proportional aperture to length or height growth is followed by a phase of aperture growth with relatively slow or arrested tip propagation. Slow propagation relative to aperture opening can occur by non-elastic deformation processes or if the material elastic properties change over time. Fracture propagation in length or height can be halted by material strength heterogeneities. To test for concurrent length versus aperture growth of these fractures, I reconstructed the crack-seal opening history for multiple cement bridges sampled at different distances from the tip of three opening-mode fractures in Travis Peak Sandstone of the SFOT-1 well, East Texas. Crack-seal cement bridges have been interpreted to form by repeated incremental fracture opening and subsequent precipitation of quartz cement that bridges the fractures. Crack-seal cement textures were imaged using a scanning electron microscope with a cathodoluminescence detector, and the number and thickness of crack-seal cement increments determined. Trends in crack-seal increments number and thickness are consistent with fast initial fracture propagation relative to aperture growth, followed by a stage of slow propagation and pronounced aperture growth. Cumulative fracture opening displacement based on palinspastic reconstruction of two cement bridges was compared to analytical solutions for a stationary and a propagating fracture aperture as a function of position relative to the fracture tip in an elastic medium. Based on this comparison, I conclude that the crack-seal cement record reflects largely the phase of dominant aperture growth and subcritical fracture propagation under constant loading stress. / text

The main objective of this study is an assessment of the potential of applying land use optimization methods for minimizing the sediment yield from catchments. The study area is the Siran watershed, a subwatershed of the Tarbela watershed in Pakistan which drains directly into the Tarbela reservoir. It has an area of 4Ub sq. miles and receives 47.82 inches annual average precipitation. The main land use practices on the Siran Watershed are agriculture, rangeland grazing and forestry. A stochastic model for simulating daily precipitation and another for simulating daily maximum temperatures are developed for the area. The synthetic daily precipitation events are transformed into daily streamflows by the soil moisture counting streamflow model using the synthetic daily maximum temperatures as input. The streamtlow model, called the Generalized Streamflow Simulation System, is modified and used for simulating baseflow recessions. The stochastic precipitation model, the stochastic temperature model and the deterministic streamflow models were combined with the deterministic sediment yield model for simulating sediment yield from the watershed. The modified Universal Soil Loss Equation was used for simulating sediment yield. Parameters at these models were determined from data taken on the Siran Watershed. A linear program was used for land use optimization to minimize sediment yield and maximize watershed production. Both optimization processes ended up with the same land use areas allocating the Maximum area for forests. The expected sediment yield was reduced by 2.5 times and production of watershed was doubled. Optimization of crops was accomplished by maximizing the production of agriculture lands. This resulted in the allocation of major agriculture land areas for apple orchards. By adopting the final optimized land use practices, the sediment yield can be reduced to half and watershed production can be increased six times. The results of the present study are encouraging and indicate that application of land use optimization methods for reducing sediment yields nave great potential on the study area and on other subwatersheds of the Tarbela and Manyla Watersheds. The methodology developed in this study can provide a useful tool for watershed managers to reduce sediment yields and increase the income of the local inhabitants by maximizing the agriculture production in other parts of the country.

On average, one percent of reservoir storage capacity is lost annually to sediment deposition in reservoirs. Several methods for sediment removal do exist, but most are inefficient and costly in terms of money or water usage. One method known as siphoning has been shown to adequately remove sediment, but present knowledge is lacking to optimize this method for removal. Three relationships for sediment transport in a pipe were compared against data collected from a physical model resembling a reservoir siphoning system. None of the three accurately predicted the physical model results. However, some trends among the relationships were observed, indicating that with additional modification to the relationships, parameters could possibly be developed to design a prototype system.

This thesis embraces four major topics coinciding with the four considerations designated in President John F. Kennedy's letter to President Basil Williams of the Seneca Nation and the reactions to those items generated during numerous hearings of the House Subcommittee on Indian Affairs. The four topics covered in the President's letter include the possibility of acquiring adjacent property, commonly referred to as "in lieu of" lands, to replace the Indian real estate taken for the Allegheny Reservoir; a review of the reservoir's recreational potential for the benefit of the Seneca Nation; special damages accruing to the Senecas for the loss of their land; and relocation and resettlement.