Master's - Theses

Meerkat-Based Multi-Wavelength Study of Supernova Remnant SN386 (G7.7-3.7)

2026-06-09T13:49:24Z

Meerkat-Based Multi-Wavelength Study of Supernova Remnant SN386 (G7.7-3.7) ; Mwaniki, Patrick Njoroge Supernova remnant SN386(G7.7-3.7) presented captivating attention for multi-wavelength observation. In this study, we investigated the structural characteristics of G7.7-3.7 with higher resolution MeerKAT observation at 1284 MHz, revealing intricate details of its morphology and emission mechanisms. MeerKAT observations revealed G7.7-3.7 as an almost circular structure with filamentary features, manifesting in various blowouts. The western boundary exhibited a strong bright blowout, while the southern perimeter show cased extended bright filaments with feather-like structures, seemingly disconnected from the western blowout. Moreover, the eastern region presented a faint blowout with a cen tralized bright point source, while faint elongated filaments traversed the northwest, linked the eastern point source and western blowout and progressed outward uniformly. Spectral index analysis indicated a steep spectrum (𝛼 ranged ∼ 0 to ∼-3), suggesting a combination of synchrotron and few traces of thermal emissions at the edges of bright blowouts. Bright blowouts with a less steep spectrum ranging from ∼-0.5 to ∼-1.5 were dominated by shock-accelerated particles encountering irregularities and weakening in magnetic fields. Spectral index values close to 𝛼 = 0, showed the presence of traces of thermal emissions from shock-heated gases, especially at the edge of the bright blowout. However, the faint emissions along the filaments connecting the eastern and western blowouts with a very steep spectral index of ∼-3 comprised synchrotron emissions from aged particles that had dissipated energy due to turbulent re-acceleration. Analysis of MeerKAT and VLA data gave an expansion of Δ𝜃 = 9 ± 0.45 arcsec over a period of Δt = 31.907 yr corresponding to an expansion rate 𝜃 = 0.282 ± 0.014 arcsec yr−1 . The data recorded a shock speed of 5883 ± 294 km s−1 and an age of 1636 ± 115 years. The revised age fitted with the explo sion event of 386 CE and the observed data in 2023. Furthermore, our multi-wavelength investigation unveiled an intriguing structure within the southern radio blowout exhibiting a convergence of features such as the bright radio blowout, a prominent X-ray arc and two faint optical filaments aligned with the X-ray bright arc. We attributed the bright radio blowouts to the non-uniform mass outflow from the localized high-density population of the shock-accelerated particles and the weakening of magnetic fields along its perimeter. Thermal emissions traces along the edges of blowouts resulted from shock-heated gases intensifying in the south due to the presence of high-density ISM. Thus, we proposed that the supernova of G7.7-3.7 occurred in an environment of varying densities of interstellar medium (ISM). Consequently, this environment facilitated X-ray emissions and the forma tion of faint optical filaments due to collisions with the ISM and the circumstellar materials from the progenitor star respectively. Our findings shed light on the complex interplay of physical processes within G7.7-3.7, offering valuable insights into the dynamics and evo lution of supernova remnants

Influence of Social, Environmental and Technological Factors on Management of Faecal Matter in Arid and Semi-Arid Areas: A Case of Isiolo Sub-County, Kenya

2026-06-08T10:08:31Z

Influence of Social, Environmental and Technological Factors on Management of Faecal Matter in Arid and Semi-Arid Areas: A Case of Isiolo Sub-County, Kenya Muthuri, Julius Kirimi Access to safe and adequate sanitation remains a significant challenge in arid and semi-arid areas. To address this issue, onsite sanitation facilities have gained global acceptance, where financial constraints often hinder the installation of conventional centralized systems. However, studies have observed that faecal matter accumulating in these technologies is usually poorly managed, posing risks to public and environmental health and leading to adverse economic and social effects. The study investigated the influence of social, environmental, and technological factors on the management of faecal matter in Isiolo Sub County. A convergent mixed methods design was used to obtain quantitative data using structured questionnaires and qualitative data from two focus group discussions. Stratified and proportionate random sampling techniques were used to select households, while purposive sampling was applied for informants. Quantitative data were analyzed using Statistical Package for Social Science (SPSS) version 26.0 for descriptive statistics and logistic regression analysis. Logistic regression was computed in univariable and multivariable analysis to determine the relationship between predictors and dependent variables, and results were presented as an odds ratio with 95% Confidence Interval (CI). Qualitative data were analyzed thematically and presented in narratives. From the findings, the pit latrine was most commonly used at 77.1%, and about 46.5% of the resulting excreta was poorly managed. The study established social factors such as secondary education (AOR = 4.085, p < .001); gender roles (AOR = 0.518, p = 0.028), knowledge of safe disposal (AOR = 22.50, p < .001), and social norms (AOR = 0.347, p = .001) to have a significant influence on the management of faecal matter. Environmental factors such as rainfall (AOR= 0.825, p = 0.0315), space availability (AOR = 0.89, p = .036), and land use (AOR=1.012, p=0.013), along with technological aspects like sustainable toilet (AOR= 1.398, p=0.036); latrine accessibility (AOR= 0.783, p=0.05); local resources (AOR = 1.488, p = 0.009) were also statistically associated with effective faecal matter management. The study concludes that social, environmental, and technological interaction influences faecal matter management in arid and semi-arid areas. The study recommends that policy makers and sanitation stakeholders, such as the county Government, promote public education and community awareness, promote resilient and lined sanitation technology, strengthen local capabilities through intra-community skilled labour training, and incorporate land experimentation with usability into infrastructure development. To promote sustainable and inclusive faecal matter management, it is vital that sanitation policies across the affected realms can adapt accordingly to context, particularly in disadvantaged arid and semi-arid lands (ASAL)

Weakly Sign Symmetric P0 -Matrix Completion Problem for Patterns of Digraphs Oforder5with Up to 5 Arcs

2026-06-08T09:02:28Z

Weakly Sign Symmetric P0 -Matrix Completion Problem for Patterns of Digraphs Oforder5with Up to 5 Arcs Marro, Joseph Lmambarin Matrix completion problem involves determining whether or not a completion of a partial matrix exist for a certain class of matrices satisfying a number of prescribed properties or not. Research on completion of various classes of matrices, including P-matrices, P0-matrices, as well as Wss P0-matrices has been done. In particular, completion of Wss P0-matrixfor4×4 matrices have been explored using digraphs with 4 arcs. However, the case of digraphs of order 5 with up to 5 arcs has not been studied. In this study, therefore, the completions of non-isomorphic digraphs of order 5 with up to 5 arcs were determined. Digraphs were utilized to create partial Wss P0-matrix from which all principal minors were obtained. Partial matrices were extracted from non-isomorphic digraphs. Principal sub-matrices were extracted from each partial matrix thereby finding the determinant of each sub-matrix obtained. Zero completion was done to all partial matrices to ascertain the viability of completion for each partial matrix. Digraphs characteristics, which leads to completion or non-completion, were analyzed. These digraphs characteristics were derived from digraphs used to construct the partial Wss P0-matrix. This study established that all cyclic and acyclic digraphs of order 5 with up to 5 arcs were found to have zero completion into a Wss P0-matrix. Digraphs of order 5 with 2 arcs that have a positionally symmetric cycle were found to have completion. However, those digraphs of order 5 with 4 and 5 arcs that possess positionally symmetric cycles were discovered to have no completion. Insights gained from this class of matrix could be applied to fill gaps in data surveys, and business analytics, allocating resources, network modelling, and optimizing processes.

Impacts of Sand Dams On Biodiversity And Ecosystem Services: Case Study of Kikuu Sand River, Makueni County, Kenya

2026-06-08T07:44:45Z

Impacts of Sand Dams On Biodiversity And Ecosystem Services: Case Study of Kikuu Sand River, Makueni County, Kenya Kigorwe, Faith Gaceri This study investigates the environmental impacts of sand dams on biodiversity and ecosystem services along the Kikuu River in Makueni County, Kenya, an arid and semi arid region where water scarcity and food insecurity remain critical challenges. While sand dams are widely promoted as sustainable water management interventions, their ecological effects on biodiversity and ecosystem services are less documented compared to their hydrological benefits. Addressing this knowledge gap, the study aimed to evaluate how sand dam construction influences plant and animal diversity as well as the provision of ecosystem services in the Kikuu River system. The research was carried out between 2023 and 2024 and covered a 35 km stretch of the Kikuu River, where 21 sand dams were identified. A total of 306 households were sampled. Data collection involved mapping natural (e.g., Acacia species, xerophytic grasses) and human-made features (e.g., water pumps, roads), biodiversity surveys of plants and animals in both sand dam and control sites, and household interviews on ecosystem services. Sampling methods included perpendicular transects, spot checks, and sweep counts. Data were analyzed using Welch’s ANOVAwith Games-Howell post-hoc tests, Pearson Chi-square tests, and regression analyses. The results indicated that sand dam sites supported higher plant and animal biodiversity compared to control sites without dams (p < 0.001). For instance, the Kwa Moses and Mbukoni dams demonstrated rich vegetation cover and increased animal presence, while regression analysis revealed that sand dams had a positive and significant relationship with ecosystem service ratings, particularly in water provision, irrigation, and soil stability. However, variations in performance among dams highlight the influence of design, location, and maintenance. The study concludes that sand dams significantly enhance biodiversity and ecosystem services in semi-arid landscapes but require site-specific management strategies, continuous monitoring, and design improvements to maximize benefits and reduce ecological trade-offs. It recommends the strategic expansion of sand dams, coupled with community participation and post construction monitoring, to strengthen ecological resilience and sustainable development in water-scarce regions.