http://localhost/xmlui/handle/123456789/3878 2026-07-25T07:28:00Z 2026-07-25T07:28:00Z Naryongo, Raphael http://localhost/xmlui/handle/123456789/7055 2026-07-21T12:07:56Z 2026-07-21T00:00:00Z

European Option Pricing Under Double Wishart Stochastic Volatility Model Naryongo, Raphael This study considered Wishart affine diffusion processes, which are stochastic processes de fined as matrix-valued square root processes or as matrix generalization of a squared Bessel process. The aim of the study was to develop a double Wishart stochastic volatility model to price European option: A multifactor Heston model whose volatility components follow Wishart affine processes for a single risky asset, with two dependence matrices describing the correlations between the asset dynamic and the Wishart processes, making it more flexible enough to price options or describe the market prices for short or long maturities. We con structed the double Wishart stochastic volatility model, through the generalization of Heston model into a multifactor nature of implied volatilities, together with the associated properties. The partial differential equation describing the behavior of prices associated to the dynamics of stock price under double Wishart volatility model was derived and solved through the ap plication of Fourier techniques, combined with perturbation methods to obtain European call option pricing formula to confirm the applicability of the model in financial derivatives. Then the log asset return price dynamic under double Wishart model was derived using Ito lemma and its integrals are solved using corrected Euler-Maruyama discretization technique in order to obtain the numerical solution for the log-asset return in order to illustrate the behavior of the log asset returns. The numerical examples show that the call price predictions under double Wishart model exhibits similar pricing behavior with respect to the market price in short and long maturities due to the flexibility in the model. Additionally, the numerical illustrations on the log-asset price return shows the effect of model parameters more so the correlation matrices on the log-asset price return behavior under double Wishart volatility model in trading, which is of importance for investors to analyze the stock prices over time PhD in Mathematics (Financial Option)

2026-07-21T00:00:00Z Kpordze, Stephen Wilson http://localhost/xmlui/handle/123456789/6605 2025-03-04T11:40:07Z 2025-03-04T00:00:00Z

GENERATION AND FUNCTIONAL CHARACTERIZATION OF CHICKEN-BASED IgY POLYCLONAL ANTIBODIES AGAINST BLACK MAMBA (Dendroaspis polylepis) SNAKE VENOM Kpordze, Stephen Wilson The life-threatening medical issues associated with snakebites have been a public health concern for decades at the global level. The Black mamba, D. polylepis, is one of the many venomous snakes found in Kenya. According to the Kenyan Ministry of Health data, 15,000 snakebites occur annually. For snakebites, antivenom immunotherapy is still the preferred course of action and different antivenoms are needed to treat the venom of different snake species. Traditionally, antivenoms for treatment are produced from horse or sheep but have complicated and expensive production issues. Alternative production approaches, such as using immunoglobulin Y (IgY) antibodies derived from chicken egg yolks, may overcome disadvantages with traditional antivenom manufacturing techniques. In many tropical and subtropical nations such as Kenya, diagnosis of snakebite in the health facilities is imperative. For the purpose of determining which species caused the bite, it is critical to detect and measure snake venom in the blood of envenomed patients. The study presents the generation of IgY antibodies, and development of an enzyme-linked immunosorbent assay (ELISA) against D. polylepis. In this current study, D. polylepis specific IgY polyclonal antibodies were purified from the egg yolks of chickens immunized with D. polylepis venom. These antibodies were subsequently assessed for their in-vivo neutralizing capacity vis-à-vis commercial antivenoms, PANAF Premium and VINS. Additionally, the study sought to develop a sensitive ELISA prototype for detection of D. polylepis venom in Kenya using generated chicken-based IgY polyclonal antibodies. The IgY antibodies were purified by ammonium sulfate precipitation and affinity-chromatography, with quality and specificity determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and ELISA. Furthermore, serum samples containing specific chicken-based IgY antibodies previously raised against D. polylepis venom toxins were used in the assay development. ELISA parameters were optimized, and developed assay assessed for applicability. The LD50 of D. polylepis was 0.54 mg/kg in chicks (via intramuscular route), and 0.34 mg/kg in mice (via intraperitoneal route), respectively. Pool of extracted IgY yielded 2.8 mg/mL concentration. Purified IgY under non-reducing and reducing conditions on SDS-PAGE xv exhibited a single-protein band of about 183 kDa and two bands (67 kDa and 25 kDa), respectively. The minimum-edematogenic dose was 0.05 µg. Anti-D. polylepis IgY antibodies and two antivenoms demonstrated the capacity to neutralize the toxic activities of D. polylepis venom. The median effective dose (ED50) for lethality neutralization were 41.36, 35.41 and 46.60 µL/3LD50, and for edema were 80±11.55, 60±18.26, 90±8.16 µL/6MED, respectively for IgY antibodies, VINS and PANAF antivenoms. There was no statistical differences among their neutralizing efficacies (P value = 0.320-0.859) The limit of detection (LoD) of the ELISA for neurotoxic venoms was 0.01 µg/mL. The developed assay identified venoms in blood of BALB/c mice and, distinguished D. polylepis venom from that of other snake species, as well as neurotoxic and cytotoxic venoms. This developed assay would be useful in helping physicians to diagnose and manage snakebite cases. The development of an effective IgY antibodies with higher titer represents a significant step towards antivenom production against D. polylepis. Diversity of the IgY antibodies development to capture other medically important snake venoms, molecularly characterize IgY, and development of venom detection kits with quick turnaround times based on liquid or lateral flow tests approach are recommend PhD in Molecular Biology and Biotechnology

2025-03-04T00:00:00Z Muse, Abdisalam Hassan http://localhost/xmlui/handle/123456789/6270 2024-11-19T08:52:32Z 2024-04-17T00:00:00Z

Bayesian and Frequentist Approaches for Flexible Parametric Hazard-Based Regression Models with Generalized Log-logistic Baseline Distribution: An Application to Right-Censored Oncology Data Sets Muse, Abdisalam Hassan n general, parametric hazard-based regression models can be motivated by allow ing baseline distribution parameters to be affected by covariates. Furthermore, it is common practice to link covariates to a single parameter of interest; this method will be called a single parameter hazard-based regression (SPHBR) models. The role of the additional (covariate independent) parameters in these SPHBR models is frequently little more than to provide the model with enough generality to adjust to data. A more flexible technique is to regress these additional distributional pa rameters on covariates as well; this is referred to as multi-parameter hazard-based regression (MPHBR) models. The development of MPHBR models in the context of Bayesian survival analysis with particular interest towards application to right censored oncology data is the main focus of this thesis. Chapter 2 of this thesis examines the fundamentals of survival analysis as well as the methodologies employed to achieve the study’s objective; these are common and can be ignored by readers with familiarity with the field. A flexible generalized log logistic distribution that can incorporate both monotone and non-monotone hazard rates is developed in chapter 3 and examined using both Bayesian and classical in ference methods. Using the baseline distribution proposed in chapter 3, chapter 4 presents a flexible parametric proportional hazard (PH) model. The tractability of the PH model is shown, and the implications of the method are discussed, including how to interpret covariate effects (via the hazard ratio), how to perform proportion ality assumption checks on regression coefficients, and how to use Bayesian model selection techniques. To show how versatile the accelerated failure time (AFT) model is, chapter 5 presents an alternative parametric hazard-based regression model to the one presented in chapter 4. The parametric hazard-based regression mod els proposed in chapters 4 and 5 might not be accurate if crossovers exist in the xxxv hazard or survival functions. The accelerated hazard (AH) model, a novel flexi ble hazard-based regression model that can take into account survival data with crossover survival curves, is proposed in Chapter 6 of this thesis as a solution to this issue. The parameters of the proposed AH model are estimated using Bayesian and frequentist approaches. The need to enable parametric hazard-based regression models—and really any parametric survival regression model—more interpretable motivates the presentation of a general class of parametric hazard-based regression models in Chapter 7. Covariate effects on the baseline hazard are straightforward to interpret due to the proposed general class. The class also has the benefit of allowing for both proportional and time-independent effects of some covariates on baseline hazard and non-proportional and time-dependent effects of other covariates in the same model, unlike PH, AFT, or AH. For estimating the model parameters, both the Bayesian and frequentist approaches are applied. In chapter 8, the Amoud Class, a novel class of survival regression models that includes all hazard-based and odds-based models as special cases and is more flexible in modelling survival data, is introduced. The main advantage of the class is that it can provide users with a quantitative tool for selecting which of the seven often employed methods for hazard-based and odds-based regression models is more appropriate for a certain set of data. For each of the models proposed in chapters 3, 4, 5, 6, and 7, several simulations are run using a variety of parameter settings and data generation sce narios in order to evaluate the efficacy of the model’s estimators. To demonstrate the adaptability of the proposed survival regression models, applications of right censored oncology data sets are explored. Finally, in Chapter 9, we conclude the thesis with a discussion and mention of some future works. PhD in Mathematics

2024-04-17T00:00:00Z Kyekyere, Ernest http://localhost/xmlui/handle/123456789/5588 2021-07-12T08:19:53Z 2021-07-12T00:00:00Z

Optimization of Thermal Performance of Water in Glass Evacuated Tube Solar Heater Kyekyere, Ernest Solar water heaters provide a cost-e cient, unlimited, and environmentally friendly approach to hot water generation. Water in glass evacuated tube solar water heater (WG-ETSWH) is one of the commonly used solar water heaters (SWHs) available in the market. Despite its widespread use, WG-ETSWH has a low thermal performance and its installation cost is very high. As a result, hot water generation in homes and industries is highly dependent on electricity, fossil fuels, and traditional biomass despite the high solar potential in Africa. That has resulted in environmental pollution, various health problems and the high cost of conventional fuels. Several research studies have been conducted to help improve the performance of water in glass evacuated tube solar collectors (WG-ETSC). The performance of WG-ETSWH is dependent on the geographic location. Additionally, for collectors with identical parameters, tilt-type collectors absorb slightly more solar irradiation than horizontal-type collectors. The optimum thickness of the polyurethane insulation to reduce heat loss from the storage tank is 50 mm. However, the e ect of collector tube length, diameter and tilt angle on the performance of WG-ETSWH has not been fully studied. This research work is focused on optimizing the performance of WG-ETSWH for water heating applications using both experimental and numerical methods under the climatic conditions in Kenya. An experimental study on the performance of WG-ETSWH was conducted under the climatic conditions in Kenya. A CFD model was developed according to the speci cations of the experimental setup and its performance was then validated against the experimental data. The validated CFD model was then used to study the in uence of geometric variables such as the collector tilt angle, collector tube diameter and the collector tube length on the performance of the system. From the experimental study, the outlet temperature of the water in glass evacuated tube solar water heater was found to be ranged from 55 oC to 69 oC given an initial temperature of 25 oC for a whole day heat collection. The daily e ciency of the water in glass evacuated tube solar water heater under the climatic conditions in Kenya ranges from 58 % to 65 %. The collector tube length, diameter and tilt angle had a signi cant in uence on the xvii performance of WG-ETSWH. The optimum collector tube length, diameter and tilt angle were found to 2000 mm, 50 mm and 28 degrees respectively. The optimized design of the WG-ETSWH enhanced the outlet temperature of the water in the storage tank by 6.0 % and the average ow velocity of water in the system by 11.8 %. The results from this research will give insight into the design of improved products of water in glass evacuated tube solar water heater for the extraction of maximum heat energy from the sun. Master of Science in Mechanical Engineering

2021-07-12T00:00:00Z