School of Pure and Applied Sciences

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

2026-04-23T09:41:42Z

Impacts of Sand Dams On Biodiversity And Ecosystem Services: Case Study of Kikuus And 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

Vaginal Bacterial Microbiome Profiles Associated with High-Risk HPV in Women Infected With HIV in Meru, Kenya

2026-04-23T07:24:09Z

Vaginal Bacterial Microbiome Profiles Associated with High-Risk HPV in Women Infected With HIV in Meru, Kenya Mutoro, Thomas Atenya Cervical cancer, caused by Human Papillomavirus (HPV), is a global burden affecting women. The vaginal microbiome is associated with female reproductive health. Immuno-compromised HIV infected women are susceptible to persistent HPV infections. This study sought to characterize the vaginal bacterial communities in HIV-infected women using 16S rRNA sequencing and to investigate their association with HPV status. A cross-sectional study was conducted involving 38 HIV-infected women. The study was carried out at the Meru Teaching and Referral Hospital. Dry Evelyn brush self-sampling kit was used forvaginal swab collection. Genomic DNA extraction and amplification were carried out at the Centre for Molecular Biosciences and Genomics (CMB). Bacterial populations were characterized using the 16S rRNA sequencing on an MGI platform. We identified 15,774 reads. Lactobacillus and Gardnerella were the most abundant genera in the study population. Vaginal dysbiosis-associated taxa such as Shuttleworthia and Prevotella were identified among hr-HPV-positive women. Differential abundance analysis revealed an over-representation of the Lactobacillus genus in the hr-HPV positive group. High microbial diversity was observed in both hr-HPV-positive and hr-HPV-negative women. In conclusion, this study highlights the bacterial taxa in the vaginal microbiota and the complex relationship between vaginal microbiome and hr-HPV infections in Kenyan women living with HIV. HIV infection is associated with a more diverse vaginal microbiota; however, the overall composition between the hr-HPV-positive and the hr-HPV-negative women is similar. This could be attributed to HIV infection having already distorted the diversity of the bacterial populations.

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

2026-04-23T07:13:11Z

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 showed extended bright filaments with feather-like structures, seemingly disconnected from the western blowout. Moreover, the eastern region presented a faint blowout with a centralized 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 a 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 explosion 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 formation 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 evolution of supernova remnants.

A Relativistic Approach to Structure Formation and Evolution in a Friedmann Universe

2026-04-22T13:08:16Z

A Relativistic Approach to Structure Formation and Evolution in a Friedmann Universe Konga, Kennedy Kamuren The advent of modern satellite technology has transformed observational astronomy and astrophysics, offering unprecedented insights into the large-scale behavior of gravitation and challenging established cosmological models. This technological progress has reinvigorated the study of relativistic cosmology, leading to a critical reassessment of foundational assumptions, particularly the cosmological principle, which posits that the universe is homogeneous and isotropic on large scales. While this principle underpins the Standard Cosmological Model (SCM) and the Friedmann-Lemaitre-Robertson-Walker (FLRW) metric, emerging data has increasingly been challenging its validity. Central to this investigation are the redshift-distance and light intensity-distance relations, essential for testing cosmological models. The integration of both parametric and nonparametric redshift models provides a more comprehensive analysis, addressing discrepancies in our understanding of the universe's structure and evolution. However, unresolved mysteries, particularly concerning dark matter and dark energy, complicate these models. This research critically examines the cosmological principle using the latest observational data and scrutinizes the Friedmann model's assumptions. The study reveals that galaxy formation occurred most rapidly in the early universe, particularly within the redshift range of 0 < 𝑧 < 0.4, peaking around 𝑧 ≈ 0.8. It also highlights that dark matter plays a significantly more critical role than dark energy in this process. While dark energy primarily affects the large-scale expansion of the universe, dark matter seems to dominate local galaxy formation and the evolution of cosmic structures. These findings underscore the limitations of current models and contribute to the ongoing refinement of cosmological theories, offering a clearer understanding of the universe’s evolution.