http://41.89.164.27:8080/xmlui/handle/123456789/29 2026-05-14T07:39:06Z http://41.89.164.27:8080/xmlui/handle/123456789/2644 MODELLING TRAFFIC FLOW BEFORE AND AFTER ROUNDABOUT USING NAVIER-STOKES AND ADVECTION-DIFFUSION EQUATIONS MOMANYI, MOGIRE KRIFIX Traffic congestion remains a persistent challenge in urban areas, with roundabouts playing a pivotal role in enhancing road safety, improving traffic flow, and minimizing congestion. Understanding traffic dynamics before and after roundabout implementation is critical for optimizing urban infrastructure. Traditional traffic models lack the precision to account for the complex interactions and flow disruptions associated with roundabouts. These limitations hinder accurate predictions of traffic patterns, requiring more advanced mathematical approaches to model flow dynamics effectively. This study aims to model traffic flow around roundabouts using Navier-Stokes and advection-diffusion equations. Specific objectives include formulating mathematical models, analyzing the influence of roundabout geometry on traffic flow, evaluating disruption and diffusion effects, and identifying critical factors impacting flow stability. The study employed fluid mechanics principles, utilizing the Navier-Stokes and advection-diffusion equations to model traffic as a fluid-like system. Numerical simulations were conducted using the Finite Volume Method and Crank-Nicolson scheme, with Matlab R2023b facilitating sensitivity analyses to evaluate various scenarios. Findings indicate that roundabouts significantly improve traffic flow efficiency by reducing congestion and enhancing speed regulation. The geometric design of roundabouts and their capacity to handle disruptions were identified as key factors influencing performance. Sensitivity analysis revealed optimal configurations for minimizing delays and maximizing output. The integration of roundabouts enhances urban traffic dynamics by mitigating congestion and optimizing vehicle movement. Mathematical models provide a robust framework for analyzing these effects, ensuring informed urban planning. Policymakers should incorporate advanced mathematical modeling in roundabout designs, emphasizing scenario-specific analyses to address diverse traffic conditions. Future research should integrate behavioral and environmental factors to refine predictive capabilities and practical applications 2025-01-01T00:00:00Z http://41.89.164.27:8080/xmlui/handle/123456789/2643 MODELLING GEOMETRY INTERRUPTION, VASCULAR STRESS, AND PULSATILITY IN CAROTID ARTERY BLOOD FLOW USING POISEUILLE-BASED EQUATIONS NGETICH, LUCY JEROP The Poiseuille equations are instrumental in modeling blood flow, particularly within large and medium-sized arteries where laminar flow predominates. Derived under the assumption of steady, incompressible, Newtonian flow through cylindrical tubes, these equations effec- tively describe vascular dynamics in geometries approximating cylindrical shapes and at low Reynolds numbers. However, their applicability diminishes in regions characterized by tur- bulence, geometric irregularities, or pulsatile flow, such as those found in the carotid artery. This study identifies three key research gaps in the application of Poiseuille equations to carotid artery hemodynamics: (i) the influence of vascular shear stress under turbulent condi- tions, (ii) the deviation introduced by pulsatile flow from the steady-state assumption inherent in the Poiseuille model, and (iii) the geometric variability of the carotid artery and its under- explored role in altering flow characteristics. To address these gaps, the study introduces a novel formulation of the Poiseuille equation incorporating geometric drag and pulsatile flow through a Womersley function. Governing equations were formulated based on modified Poiseuille flow and solved numerically using the Finite Volume Method (FVM) implemented in MATLAB, with custom code developed to simulate time-dependent blood flow. The nu- merical scheme incorporated discretization of the Navier–Stokes equations and was executed using MATLAB’s built-in solvers and post-processing tools for velocity, pressure, and vascu- lar stress visualization. The simulation results revealed a significant reduction in flow rate and velocity in regions with geometric interruptions. For example, the peak simulated velocity reduced by approximately 28% in stenosed segments compared to normal arterial sections, demonstrating a nonlinear velocity profile consistent with observed clinical behavior. The simulations further indicated that geometric disturbances, such as stenosis and bifurcations, resulted in an increase in vascular stress and a pronounced decrease in flow rate (Q), partic- ularly under turbulent conditions. This inverse relationship between vessel radius and flow dynamics corroborates findings from existing studies on stenotic arteries. Additionally, the analysis demonstrated that as artery radius (r) decreased, vascular stress W(r, t) increased substantially, in line with predictions from Hagen–Poiseuille’s law. Pulsatility during systolic phases further amplified wall shear stress (WSS), thus supporting the third objective of the study. The findings emphasize the limitations of the classical Poiseuille-based model in tur- bulent and pulsatile regimes and highlight the necessity for more robust modeling approaches to accurately capture the complex hemodynamics of carotid artery flow under pathological conditions. 2025-01-01T00:00:00Z http://41.89.164.27:8080/xmlui/handle/123456789/2637 CHARACTERIZATION OF SANDFLY POTENTIAL VECTORS AND RESERVOIR HOSTS OF CUTANEOUS LEISHMANIASIS AND THEIR HABITATS IN BUNGOMA COUNTY, KENYA MULONGA, WEKESA JOB Cutaneous leishmaniasis (CL), a neglected tropical disease caused by Leishmania parasites and transmitted by sandfly vectors, is a significant health concern in Bungoma County, and other Kenyan leishmaniasis-endemic counties. The present study aimed to characterize the distribution and ecological attributes of habitats of sandfly vectors and reservoir hosts of CL. The research objectives included: determining sandfly species diversity and abundance in identified sandfly habitats, evaluating the effects of temperature, relative humidity, and altitude on sandfly occurrence, analyzing soil characteristics in sandfly habitats for their physical and chemical properties, determining the association of sandfly populations and plant species populations in the study area, and evaluating the relationship between potential vertebrate reservoir hosts populations and sandfly populations in the study area. Sandflies were collected from their habitats using CDC light traps, dissected and identified morphologically between January 2021 and December 2022. Species diversity and evenness was analyzed using the Shannon-Weinner’s diversity index. A total of 6,156 sandflies were captured, with Phlebotomus pedifer accounting for 94%, P. elgonensis 0.5%, and Sergentomyia species 5.5%of the collections. Environmental factors, including temperature (21– 29°C), relative humidity (75-90%) and altitude (1,506–3,100 masl), were significant (P < 0.05) determinants of sandfly distribution. The correlation between soil properties and sandfly abundance was non-significant. Plant species diversity index (3.14 H’) and vertebrate diversity index (2.06 H’) indicated strong association with sandfly abundance, highlighting ecological drivers of the vector populations. The study concluded that Phlebotomus pedifer is the dominant sandfly vector species of CL in Bungoma County; while it is the people who go to the vector habitats (caves) who get bitten and become infected with CL. These findings underscore the need for habitat- specific interventions, such as environmental management to control sandfly populations in caves to reduce the transmission of CL in the study area and other similar regions. 2025-01-01T00:00:00Z http://41.89.164.27:8080/xmlui/handle/123456789/2626 Antibiotic sensitivity of bacterial isolates from farmed fish in Uasin Gishu County, Kenya Mutai, Edwin Kipyegon; Ngeiywa, Moses; Liti, Davi; Kosgei, Patricia Tarus The study was conducted with the aim of investigating the antibiotic sensitivity of bacterial isolates from farmed fish to commonly used antibiotics in Uasin Gishu County, Kenya, a region experiencing rapid aquaculture growth. Despite no direct antibiotic use in local fish farms, concerns over antimicrobial resistance (AMR) have emerged due to indirect exposure from integrated livestock-crop systems. A longitudinal study design was used to evaluate microbial infestations. Over a 12-month period, 468 fish samples from 13 ponds across five farms were examined, yielding 154 bacterial isolates representing 12 species, including Escherichia coli, Aeromonas species, Pseudomonas aeruginosa, Vibrio species and Flavobacterium columnare. Antibiotic susceptibility testing was conducted using six commonly used antibiotics: amoxicillin (AMX), erythromycin (ERY), cotrimoxazole (CT), doxycycline (DO), streptomycin (STR), and ciprofloxacin (CIP). Statistical analysis using Fisher’s exact test revealed significant interspecies resistance variation for AMX and ERY (p = 0.0005), while the other antibiotics showed consistent susceptibility across species. Principal Component Analysis (PCA) and heatmap analyses confirmed AMX and ERY as the primary drivers of resistance variation, particularly in E. coli, Aeromonas hydrophila and Streptococcus species, which showed resistance rates above 35 to 50%. Conversely, CIP, DO, and STR exhibited high effectiveness, with over 80% susceptibility in most isolates. The results suggest that indirect exposure through runoff, manure application, and effluent from livestock farming is likely promoting resistance. The findings of this study reveal that antibiotic use in surrounding agricultural systems, although not directly applied to fish, may be contributing to the development of resistant bacterial populations within aquaculture environments. This highlights a critical link between terrestrial and aquatic ecosystems, reinforcing the need for a One Health approach to antimicrobial stewardship. The results emphasize the importance of regular monitoring of antibiotic resistance patterns and adopting tailored antibiotic selection based on local data. Furthermore, the study underscores the necessity of improved waste management, enhanced farmer education, and strengthened biosecurity practices to curb the spread of resistant bacteria. Continued surveillance of antibiotic resistance in aquaculture is essential to ensure food safety, safeguard public health, and promote the sustainability of fish farming systems. 2025-01-01T00:00:00Z http://41.89.164.27:8080/xmlui/handle/123456789/2625 Improving aquaculture productivity in Uasin Gishu County, Kenya: Addressing pathogens, water quality, and management challenges Mutai, E. Kipyegon; Ngeiywa, M.M.Moses; Liti, D. Aquaculture in Uasin Gishu County, Kenya, has grown significantly due to government support, favorable climatic conditions, and an increasing demand for fish as a protein source. However, fish farming in the region faces severe challenges from pathogenic parasites and microbes, which significantly impact fish health and aquaculture productivity. Poor water quality, overcrowded ponds, and agricultural runoff exacerbate the proliferation of pathogens, including protozoan parasites (Ichthyophthirius multifiliis), monogeneans (Gyrodactylus species), bacterial pathogens (Aeromonas hydrophila, Edwardsiella tarda), and fungal infections (Saprolegnia species). These pathogens cause diseases that lead to high mortality rates, reduced productivity, and economic losses. This review synthesizes current research on fish pathogens in Uasin Gishu, contextualizing the findings within regional and global frameworks, and identifies critical gaps in disease management. It also proposes strategies to mitigate disease prevalence, improve water quality, and enhance aquaculture sustainability. 2025-03-01T00:00:00Z http://41.89.164.27:8080/xmlui/handle/123456789/2622 PHYTOCHEMICAL ANALYSIS AND ANTIBACTERIAL ACTIVITY OF Guizotia scabra LEAF, STEM BARK AND ROOT EXTRACTS FOR DENTAL CARIES CONTROL PAUL, ANJELINE JEPCHUMBA Medicinal plants offer promising alternatives for treating oral infections. This study investigated the phytochemical composition and antibacterial activity of Guizotia scabra tender leaf, stem bark, and root extracts against Streptococcus mutans and Streptococcus sobrinus, key pathogens in dental caries. Ethanol and acetone extracts were subjected to Standard laboratory tests for phytochemicals analysis, High- performance liquid chromatography (HPLC) for quantification of flavanoids, Fourier- transform infrared spectroscopy (FTIR) for determination of functional groups and antibacterial bioassays to assess antibacterial activity. Phytochemical tests revealed the presence of anthraquinones, alkaloids, terpenoids, flavonoids, steroids, saponins, and quinones. HPLC analysis confirmed the presence of myricetin and quercetin, with leaf extracts showing the highest concentrations (myricetin: 7.0013 ppm; quercetin: 0.901 ppm). Stem bark lacked myricetin but contained quercetin (2.4991 ppm), while root extracts had moderate levels of both (myricetin (2.0627 ppm) and quercetin (0.7027 ppm). FTIR spectra identified key functional groups, including O-H/N-H (3441 cm−1)1 linked to alkanoids (Quercetin ) (N-H /O-H group), C=O (1643 cm−1) which correlate to terpenoids, C-H/C-O (1396 cm−1) linked to alkaloids structure having N /O-H bond,2000 cm−1 to terpenoids /flavanoids and possible metal-ligand vibrations (538 cm−1). There is also a distinct C-N stretch (1250 cm−1) likely due to C-N stretching in alkaloids showed by leaf and root extracts. Antibacterial evaluation demonstrated that ethanol leaf extract had the highest inhibition against Streptococcus mutans (5.0 mm, 62.5%) and Streptococcus sobrinus (4.0 mm, 50%), followed by root extracts (3.0 mm, (37.5%) and 2.5 mm , (31.25%) respectively. Acetone extracts showed similar trends with the leaf extract at 4.6 mm, (57.5%) and 4.3 mm, (53.75%). However, commercial toothpastes showed superior inhibition (up to 7.0 mm, 87.5%) likely due to fluoride content and other additives. These findings suggest that Guizotia scabra possesses bioactive compounds with potential for natural oral healthcare applications. Further studies should optimize extraction; evaluate compound synergy, ensuring safety and efficacy for possible formulation of dental products. 2025-01-01T00:00:00Z http://41.89.164.27:8080/xmlui/handle/123456789/2621 ANTIBIOTIC SUSCEPTIBILITY AND PREVALENCE OF Staphylococcus aureus IN DIABETIC WOUNDS AMONG PATIENTS AT MOI TEACHING AND REFFERAL HOSPITAL, KENYA OGUDA, OWUOR DOMNIC The frequent source of deferred healing processes in wounds is Staphylococcus aureus worldwide. Diabetic wounds in diabetic patients contribute to delayed healing due to antibacterial resistance, which has caused a lot of suffering and a low quality of life for patients. This study investigated the prevalence, possible risk factors, and antimicrobial susceptibility profile of S. aureus isolated from diabetic wounds of patients attending Moi Teaching and Referral Hospital (MTRH). It involved purposive sampling; patients with diabetic wound infections who were willing to participate in the study were selected. The study included Type 2 Diabetes patients aged 13 years and above, who presented at the MTRH diabetic clinic during the study, and had not used antibiotics for any reason. The study targeted 156 diabetic patients attending MTRH. A questionnaire was administered to collect socio-demographic data. Wound swabs were aseptically collected and cultured on blood agar, then sub-cultured on Mannitol Salt Agar to isolate S. aureus. It was further identified by catalase and coagulase tests. Determination of antimicrobial susceptibility was by the Agar disk diffusion method. The occurrence of S. aureus in diabetic wounds was significantly (p=0.025) influenced by the sex of patients attending the diabetic clinic at MTRH. However, age (p=0.6503), underlying conditions (p=0.8437), previous hospitalization (p=0.808), previous antibiotic use (p=0.6874), marital status (p=0.118), and the level of education (p=0.192) do not significantly predispose the wounds of diabetic patients attending an outpatient diabetic clinic at MTRH to S. aureus. 31 samples were positive for S. aureus. An instance of intermediate sensitivity 26 (10.48%) was shown by S. aureus isolated in this study, with 72 (29.03%) resistance to antibiotics. However, most of the isolates were vulnerable to the test antibiotics. A higher number of S. aureus isolates were susceptible to Cefoxitin (96.77%) and Clindamycin (80.65%), with lesser susceptibility to Ampicillin (25.81%). A prevalence of 19.87%, Cefoxitin being effective against most of the S. aureus isolates, and a significant relation between sex and occurrence of S. aureus in diabetic wounds were established. Early surveillance and screening to detect any presence of MRSA in diabetic wounds and the susceptibility profile of S. aureus in diabetic wounds of patients attending the diabetic clinic at MTRH is recommended. Re- evaluation of the use of Ampicillin should also be taken into consideration to prevent widespread antibiotic resistance. Female diabetic patients should take more precautions to prevent any traumatic injury, which could lead to diabetic wound infections. 2025-01-01T00:00:00Z http://41.89.164.27:8080/xmlui/handle/123456789/2620 PLASMID-MEDIATED ANTIBIOTIC RESISTANCE IN GRAM-NEGATIVE PATHOGENIC BACTERIA ISOLATED FROM RIVER SOSIANI AND WASTE WATER SYSTEMS IN UASIN GISHU COUNTY, KENYA AUMA, SHARON The widespread of bacteria resistance to antibiotics poses an immense threat to the public health. Aquatic ecosystems receive waste water which invariably contain different bacteria, chemicals and antibiotic residues that induces bacterial resistance to antibiotics, resulting into several treatments failures and deaths. Plasmid-mediated antibiotic resistance of bacteria through horizontal gene transfer has been reported to significantly cause resistance in susceptible bacteria. The current study identified antibiotic resistance genes present in gram-negative bacterial plasmids, isolated from River Sosiani and wastewater systems in Uasin Gishu County, Kenya. The sampling sites included Outspan-Nairobi bridge, Pioneer bridge, Moi Teaching and Referral Hospital, Eldoret prison, Kipkaren bridge, Huruma quarry influent, Huruma quarry effluent, Kipkenyo boundary influent and Kipkenyo boundary effluent. The study entailed bacteria isolation, identification, antibiotic susceptibility testing, plasmid DNA extraction and polymerase chain reaction of the antibiotic-resistant genes. Mean and standard deviations were analyzed using Microsoft Excel while Chi square was used to determine significant relationship existing between the phenotypic and genotypic resistance in bacteria. Most of the bacteria coliforms obtained were too numerous to count. A total of 10 gram-negative pathogenic bacteria species were detected, including Escherichia coli, Enterobacter aerogenes, Citrobacter freundii, Klebsiella pneumoniae, Klebsiella oxytoca, Proteus vulgaris, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella enteriditis and Yersinia enterocolitica. All the 10 bacteria conferred resistance to penicillin, ampicillin, amoxicillin-clavulanic acid, ceftazidime, tetracycline, streptomycin and sulfamethoxazole-trimethoprim. Multi antibiotic resistance index was higher in E. aerogenes (0.83) but lower in Y. enterocolitica (0.58). Out of the nine antibiotic-resistant genes investigated, qepA and qnrA genes were present in the plasmids of all the 10 bacteria species, 70% of the total bacteria species had dfrA5, 70% had aadA1, 50% had blaKPC, 40% had mphA, 30% of the bacteria species had blaSHV and sul 1 genes (P≥1) while none of the bacterial plasmid DNA had AmpC gene. The study findings suggested that River Sosiani and the sampled wastewater systems contained different pathogenic bacteria and their plasmid-mediated antibiotic resistance genes which confer resistance to commonly used antibiotics. Therefore, effective waste disposal, continuous monitoring and proper pretreatments of water from River Sosiani and the sampled wastewater systems may reduce bacteria contamination and antibiotic resistance inducers, addressing challenges associated with antibiotic resistance in bacteria. 2025-01-01T00:00:00Z http://41.89.164.27:8080/xmlui/handle/123456789/2586 Enhancing fisheries productivity through improved fish pond management in Uasin Gishu County, Kenya: A comprehensive review Kosgei, J. Patricia; Liti, David M; Chemoiwa, Emily J.; Mutai, Edwin K. Aquaculture is increasingly recognized as a cornerstone of global food security and economic development. However, its potential remains underexploited in many developing regions, including Uasin Gishu County in Kenya. This review synthesizes local and global research on the challenges and opportunities for enhancing fisheries productivity in the county through improved pond management practices. By examining production systems, water quality variables, and nutritional management, this review presents practical strategies for sustainable intensification of aquaculture in the region. The findings underscore the need for coordinated efforts among stakeholders to unlock the full potential of aquaculture in Uasin Gishu County, positioning it as a viable pathway toward rural development and long-term food security. The recommendations focus on capacity building, resource access, policy support, and integrated farming approaches aimed at improving productivity, profitability, and environmental sustainability. 2025-07-01T00:00:00Z http://41.89.164.27:8080/xmlui/handle/123456789/2585 Influence of Water Quality on Growth Dynamics of Nile Tilapia (Oreochromis niloticus) in Uasin Gishu Aquaculture Systems Kosgei, J. Patricia; Liti, M. David,; Mutai, K. Edwin; Chemoiwa, J. Emily Aquaculture in Uasin Gishu County, Kenya, supports food security and livelihoods but faces challenges from unstable water quality affecting Nile tilapia (Oreochromis niloticus) growth. This study examined the relationship between water quality and fish growth across five farms representing earthen, tank, and raised liner systems from May 2023 to April 2024. Physico-chemical parameters—dissolved oxygen (DO), temperature, pH, chemical oxygen demand (COD), and biological oxygen demand (BOD)—were measured at three-hour intervals, while fish growth was monitored monthly. Data were analyzed using ANOVA, Tukey’s HSD, and multiple regression to assess water quality effects on growth. Temperature (21–23 °C) was below the optimal 25–30 °C range; pH (8–9) was acceptable; DO occasionally dropped below 3 mg/L; and COD (32–95 mg/L) and BOD (33–103 mg/L) indicated organic loading. Significant differences occurred among farms for temperature, DO, COD, and BOD. Growth parameters derived from the von Bertalanffy Growth Function showed the best performance in raised liner systems, with Cheplaskei Farm A recording the highest growth (L∞ = 36.78 cm; W∞ = 630.02 g). COD and BOD were the strongest predictors of maximum growth rate. The findings emphasize the need for stable water quality management to enhance O. niloticus productivity and ensure sustainable aquaculture in the region. 2025-12-01T00:00:00Z