Berlin, Freie University, Diss., 2004. / Dateiformat: zip, Dateien im PDF-Format.

Freiberg (Sachsen), Techn. Universiẗat, Diss., 2001.

Potsdam, University, Diss., 2004. / Erscheinungsjahr an der Haupttitelstelle: 2003.

No description available.

No description available.

A Thesis submitted to the Faculty of Science in ful lment of the requirements for the degree of Doctor of Philosophy, School of Computer Science and Applied Mathematics. Johannesburg, 2016. / In this thesis in order to study the complex dynamics of Rift Valley fever (RVF) we combine two modelling approaches: equation-based and simulation-based modelling. In the first approach we first formulate a deterministic model that includes two vector populations, Aedes and Culex mosquitoes with one host population (livestock), while considering both horizontal and vertical transmissions. An easy applicable expression of the basic reproduction number, R0 is derived for both periodic and non-periodic environment. Both time invariant and time varying uncertainty and sensitivity analysis of the model is carried out for quantifying the attribution of model output variations to input parameters over time and novel relationships between R0 and vertical transmission are determined providing important information useful for improving disease management. Then, we analytically derive conditions for stability of both disease-free and endemic equilibria. Using techniques of numerical simulations we perform bifurcation and chaos analysis of the model under periodic environment for evaluating the effects of climatic conditions on the characteristic pattern of disease outbreaks. Moreover, extending this model including vectors other than mosquitoes (such as ticks) we evaluate the possible role of ticks in the spread and persistence of the disease pointing out relevant model parameters that require further attention from experimental ecologists to further determine the actual role of ticks and other biting insects on the dynamics of RVF. Additionally, a novel host-vector stochastic model with vertical transmission is used to analytically determine the dominant period of disease outbreaks with respect to vertical transmission efficiency. Then, novel relationships among vertical transmission, invasion and extinction probabilities and R0 are determined. In the second approach a novel individual-based model (IBM) of complete mosquito life cycle built under daily temperature and rainfall data sets is designed and simulated. The model is applied for determining correlation between abundance of mosquito populations and rainfall regimes and is then used for studying disease inter-epidemic activities. We find that indeed rainfall is responsible for creating intra- and inter-annual variations observed in the abundance of adult mosquitoes and the length of gonotrophic cycle, number of eggs laid per blood meal, adults age-dependent survival and fight behaviour are among the most important features of the mosquito life cycle with great epidemiological impacts in the dynamics of RVF transmission. These indicators could be of great epidemiological significance by allowing disease control program managers to focus their e orts on specific features of vector life cycle including vertical transmission ability and diapause. We argue that our IBM model is an ideal extendible framework useful for further investigations of other relevant host-vector ecological and epidemiological questions for providing additional knowledge important for improving the length and quality of life of humans and domestic animals. / LG2017

Seismic data from 31 seismic stations, consisting of 16 SPREE (Superior Province Rifting Earthscope Experiment) and 15 TA (Transportable Array) instruments located from 80 - 97W and 41 – 55N were used to measure the lateral variation in the lithospheric fabric beneath the Superior Province and the Mid-Continent Rift (MCR). I made shear wave splitting measurements of SK(K)S phases by using the eigenvector minimization approach of Silver and Chan (1991). Error surfaces for multiple events were stacked in back-azimuthal swaths to examine directional variability. A single anisotropic layer model is sufficient to explain my data. My results show a high split time in the western Superior Province (WSP), very weak splits in the Nipigon Embayment and a moderate split in the eastern Superior. I observed low split times in the Penokean, Yavapai and Matzazal Provinces. A region of very low split is newly detected by this study immediately to the east of Lake Superior. The MCR shows moderate to low split times. There are subtle variations in the direction of the fast shear wave across the study region. The fast directions align with the direction of the absolute plate motion and the direction of tectonic boundaries in most regions. Lateral variation of anisotropy and lithospheric fabric is observed across the study area. The strong fabric observed in the western Superior is truncated to its east and to its south. I interpret southward truncation to be due to the Mid-Continent Rift. My result shows that lithospheric fabric in the Nipigon Embayment (NE) located just east of the WSP has been lost or seriously modified. The NE is interpreted to be an hotspot feature, which may have initiated the MCR. Moreover, the result of this study suggests that the lithosphere in the MCR may have been thinned or modified though not as much as the lithosphere of the NE. The newly discovered localized low split zone northeast of the MCR is similar in split time and extent to the feature in the NE. The relatively weak split in the eastern Superior Province may possibly be attributed to partial loss or modification of preexisting fabric resulting from the Great Meteor hotspot track.

Data used for the present study were recorded at the small aperture cross-linear array station which was installed at Kaptagat (in NW Kenya) by the University of Durham. The seismic array data from local earthquakes have been analysed by velocity/azimuth filtering technique. Apparent velocities and azimuths for first and later arrival phases were measured for local rift events from the immediate east, for local events from the south west and for more distant rift events to the north and south of Kaptagat. Data from local rift events originating from the immediate east of Kaptagat were used in the present analysis to study the structure of the lithosphere beneath the Gregory rift at about 0.5 N latitude. The first arrival data (apparent velocities and azimuths) were determined to a high degree of accuracy. The first and later arrival data have been interpreted in terms of a simple two layer model with a horizontal refracting interface at a depth of 13 + 5 km and having upper and lower layer uniform velocities of 5.8 + 0.2 km/ s and7.2 + 0,2 km/s respectively. The minimum lateral extent of the top surface of this refractor is estimated at about 30 km. A maximum dip of about 6 on the interface is allowed by the data. In the preferred three layer model, a 10 km thick top horizontal layer of velocity 5.8 km/s overlies a 10 km thick intermediate layer in which velocity increases uniformly from6.0 km/s at 10 km depth to 7.5 km/s at a depth of 20 km. The intermediate layer, in turn, overlies a 7.6 km/s refractor. The models derived from the present data are consistent with the theory that upward perturbation of the lithospher asthenosphere boundary giving rise to domal uplift, lithospheric tension and magmatic activity, is the primary causeof rifting.

No description available.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1961. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 183-189).