Multimedia University of Kenya

In this paper, we compute the norm and spectrum of the Hilbert matrix operator on Hardy and weighted Bergman spaces of the upper half-plane.

Ordinary Portland cement (OPC) remains the most common binder used in construction and accounts for nearly 7%‐8% of the world’s CO 2 emissions due to calcination of limestone and high energy use during clinker production. Reducing OPC content using SCMs is one of the major strategies to achieve sustainable construction. Stone‐cutting dust, coming from quarrying activities and having a very fine particle size with oxide composition, has come out recently as a prospective SCM. Its chemical and mineralogical composition may vary widely depending on the type of parent rock: granite and basalt dusts, rich in silica and alumina, in contrast with marble and limestone dusts, which are mainly composed of crystalline calcium carbonate with low pozzolanic activity. This review aims to compile and discuss the published works concerning the use of SCD as a partial replacement of OPC, providing detailed information about its physicochemical, mechanical, and durability performance. Studies showed that 10%–25% replacement of OPC with SCD results in improvement in compressive strength (10%–20%), reduction of water absorption, and refinement of the pore structure due to the filler effect and limited pozzolanic reactivity. However, the obtained results are still inconsistent because of varying stone type, mix design, and curing conditions. Moreover, some reports show losses of strength or reduced workability when higher replacement levels were applied or in the case of using SCD enriched in carbonates. SEM, XRD, and FTIR studies demonstrated microstructural densification and secondary C–S–H in silica‐rich systems, while calorimetric and long‐term durability studies remain limited. Overall, SCD has the potential to be a promising sustainable supplementary cementitious material; however, its performance is strongly dependent on mineralogy and processing conditions. It is recommended that a standardized testing framework should be developed in order to allow better comparability between the various published studies and to guide safe and effective application in low‐carbon cementitious systems.

Micropolar fluids are polarized fluids hence have better thermal conductivity properties. The incorporation of nanoparticles into micropolar fluids further enhances their thermal conductivity performance. The gyration characteristic of these fluids is significant in fields such as astrophysics, stellar dynamics, and dynamic theory. Flow along wedge structures has important application in aerodynamics, hydrodynamics heat transfer and industrial processes. The main aim of the study is to investigate the steady micropolar nanofluid flows along a wedge and determine the effect of microparameter, wedge parameter, concentration and unsteadiness, magnetic field on the fluid flow. In this study, a two-dimensional steady flow of a micropolar nanofluid along the surface of a wedge with a uniform surface temperature, a uniform upstream velocity, pressure, temperature with a perpendicularly applied magnetic field was considered. By incorporating gyration and inertial effects into the Navier-Stokes equations, the flow is modeled and converted to ordinary differential equations through similarity transformation. Then solved numerically by Fourth-Order Runge-Kutta method, in combination with the shooting technique and the bvp5c solver in MATLAB. Results reveal that increase in magnetic and micropolar parameters reduces the fluid velocity due to higher rotational viscosity, however, micropolar effects increases the temperature, solute concentration, energy and mass transfer. Additionally, skin friction is highest at the least wedge parameter and magnetic parameter, fluid velocity and enhances mass heat and mass transfer regardless of the magnetic field strength. Higher values of the micropolar parameter led to reduced velocities in both primary and secondary directions. An increased micropolar effects raised the temperature and solute concentration. Heat and mass transfer is highest at the highest wedge parameter irrespective to the strength of the magnetic field. Skin friction increases with an increase in wedge parameter. Sherwood numbers resulted in decreased solute concentration and elevated temperatures. The reduced solute dispersion and enhanced temperature retention.

This study sought to determine the influence of Information, Education, and Communication on road safety among Boda-boda motorcyclists in Kenyan cities. With over 1.3 million global and 4,000 Kenyan road fatalities annually, road safety has become a critical concern. This study was grounded in the Social Cognitive Theory, Safety Culture Theory, and Uses and Gratification Theory, which guide the understanding of behavioural change, safety practices, and communication effectiveness among motorcyclists. The study employed a pragmatic philosophical paradigm with a convergent parallel design, utilising a mixed-methods research approach. The researcher employed Yamane's (1967) formula to determine the target population of 399 Boda-boda motorcyclists from four cities in Kenya—Nairobi, Mombasa, Kisumu, and Nakuru—leading to a final sample of 387 respondents. Stratified sampling and simple random sampling were used to draw the sample. Interviews were conducted with nine key informants, purposively sampled from each city, drawn from the NTSA office, the Boda-boda association, and senior traffic police officers. Quantitative data was collected from the motorcyclists by use of semi-structured questionnaires, while qualitative data was gathered through key informant interviews. Descriptive and inferential statistics were used to analyse the quantitative data, while qualitative data was analysed thematically. The results were as follows: information, education, and communication, R² = 0.586, p-value = 0.000 < 0.05. The study contributes to academic discourse by emphasising the importance of integrating BCC theories into practical applications in road safety programs. The study suggests that there is a need for innovative, diverse communication strategies to improve safety and encourage responsible behaviour among Boda-boda motorcyclists in Kenyan cities.

This study sought to determine the moderating influence of attitude on the relationship between behaviour change communication and road safety among Boda-boda motorcyclists in Kenyan cities. The study was anchored on the Social Cognitive Theory and Safety Culture Theory. The study used a pragmatic philosophical paradigm with a convergent parallel design of mixed-method research. There was an initial population of 280,000 riders, whereby the Yamane (1967) formula was employed to determine the target population of 399 Boda-boda motorcyclists from four cities in Kenya—Nairobi, Mombasa, Kisumu, and Nakuru—leading to a final sample of 387 respondents. Stratified sampling and simple random sampling were used to draw the sample. Interviews were conducted with nine key informants, purposively sampled from each city, two drawn from the NTSA office, three from the Boda-boda association, and four senior traffic police officers. Quantitative data was collected from the motorcyclists using semi-structured questionnaires, while qualitative data was gathered through key informant interviews. Descriptive and inferential statistics were used to analyse the quantitative data, while qualitative data was analysed thematically. The findings showed a positive relationship between behaviour change communication and road safety. Attitude as a moderator demonstrated R² = 0.801, p-value = 0.000 < 0.05, indicating a significant impact on predicting road safety and showing a potential synergistic effect between the two factors. BCC interventions aimed at Boda-boda motorcyclists significantly contribute to road safety. The findings will aid road safety stakeholders in crafting BCC interventions that elicit positive behaviour among motorcyclists.

In this paper, we investigate the spectral properties of a composition operator Cα: ℓp → ℓp, where 1 ≤ p < ∞ and a null sequence α = (αk)k ∈ ℕ, defined by Cαx = (0, α1x1, α2x2, …). In particular, we prove that the point spectrum, the approximate point spectrum, as well as the spectrum of Cα all coincide and form the singleton set containing 0. However, the extended spectrum of Cα turns out to be the complement of the closed unit disc of the complex plane.

In this paper, the study focused on carrying out a stability analysis on the SIR model for the COVID-19 pandemic for the period before the vaccination roll out in Kenya. Earlier, in a related study using a modified SIVR that focused on the period after the vaccination roll out, has heavily been relied on by this current study. This study therefore aimed at drawing a comparison between the pre and post-vaccination stability analyses The eventual intention is to show that whereas there existed a form of herd immunity amongst the Kenyan people attributed to the people’s way of life, transmission dynamics during the pre-vaccination period show that the disease spread was largely uncontrolled. In contrast, the earlier study on post vaccination analysis by Mocheche GM, (Mocheche, 2024) revealed that the infections drastically reduced to near zero after vaccination except for a few isolated cases that were and still continue to exhibit mild symptoms to none at all. Accordingly, this was attributed to the development of the vaccine which upon a massive campaign by the Kenyan government, led into a significant portion of the population being vaccinated. It is believed this vaccination drive enhanced herd immunity amongst the population. This development has had a significant effect in the control of more recent COVID-19 variants like JN-1 that have remained largely mild and undetected in the country. Arising from this revelation and from the cultural beliefs that discourage the populace against conventional vaccinations, results from this comparative analysis will inform policy makers that there is considerable need for deliberate civic education for the Kenyan people to embrace vaccination as a means to protecting themselves against future COVID-19 and other infectious diseases of a similar nature.

This study explored the role of stakeholder engagement in enhancing Corporate Social Responsibility (CSR) within private universities in Kenya, focusing on Instagram as a strategic communication tool. This research investigated how stakeholder engagement through Instagram can enhance CSR efforts in Kenyan private universities, providing insights into effective strategies for leveraging Instagram to drive positive social impact and promote responsible practices. A qualitative research design was employed by stakeholder theory, focusing on five prominent private universities in Kenya: Management University of Africa, KCA University, Kabarak University, and St. Paul's University. Semi-structured interviews with corporate communication experts provided in-depth insights into their CSR strategies. Additionally, a qualitative content analysis of Instagram posts identified patterns and trends in stakeholder engagement. The findings highlight that Instagram plays a key role in building a sense of community among stakeholders, including students, staff, alumni, and the community. Through transparent communication and interactive content, universities can foster trust and collaboration, essential for successful CSR initiatives. The study emphasizes understanding stakeholders' motivations and expectations to create effective engagement strategies. By utilizing Instagram's interactive features, private universities can enhance their CSR efforts, promoting social responsibility and sustainable development.

Carbon nanofibers (CNFs) are kwidely used to fabricate nanocomposites with enhanced properties. The emergent properties of the nanocomposites depend on the initial properties of the CNFs and how the fibers have been dispersed within the polymer matrix. This study looks at the fabrication of nanocomposites using dodecyl, butyl, and acetyl functionalized CNFs with cellulose acetate as the polymer matrix. The CNFs were prepared by electro-spinning, and functionalization was achieved using alkyl halides in the presence of lithium. Scanning Electron Microscopy (SEM) showed that the fibers were well embedded in the polymer Matrix, Thermal Gravimetric Analysis (TGA) of the nanocomposite revealed a slight increase in the degradation temperatures of the nanocomposites as compared to the blank sample, the aggregate loss of weight of the samples was about 80%. Dynamic Mechanical Analysis (DMA) of the nanocomposites showed increased stiffness and modulus storage by an average of 450MPa for butyl and dodecyl-functionalized CNFs, however, the storage modulus values of the nanocomposites generally decreased with an increase in temperature. The glass transition temperature of the nanocomposites was higher than that of the reference sample by an average of +36°C. Conductivity measurements of the nanocomposites showed no changes at lower frequencies of 1x10<sup>2</sup> - 4x10<sup>4</sup>Hz. However, the values started increasing at peaked at 5x10<sup>7</sup>Hz. The conductivity measurements revealed that the nanocomposites exhibited higher conductivity peaks at specific frequencies compared to the reference sample, indicating an enhanced electrical property of the nanocomposite. The study successfully fabricated nanocomposites with enhanced mechanical, thermal, and dielectric properties using functionalized CNFs.