Large-scale radio propagation path loss measurements and predictions in the VHF and UHF bands.

For decades now, a lot of radio wave path loss propagation models have been developed for predictions across different environmental terrains. Amongst these models, empirical models are practically the most popular due to their ease of application. However, their prediction accuracies are not as high as required. Therefore, extensive path loss measurement data are needed to develop novel measurement-oriented path loss models with suitable correction factors for varied frequency, capturing both local terrain and clutter information, this have been found to be relatively expensive. In this paper, a large-scale radio propagation path loss measurement campaign was conducted across the VHF and UHF frequencies. A multi-transmitter propagation set-up was employed to measure the strengths of radio signals from seven broadcasting transmitters (operating at 89.30, 103.5, 203.25, 479.25, 615.25, 559.25 and 695.25 MHz respectively) at various locations covering a distance of 145.5 km within Nigerian urban environments. The measurement procedure deployed ensured that the data obtained strictly reflect the shadowing effects on radio signal propagation by filtering out the small-scale fading components. The paper also, examines the feasibilities of applying Kriging method to predict distanced-based path losses in the VHF and UHF bands. This method was introduced to minimize the cost of measurements, analysis and predictions of path losses in built-up propagation environments.

Multimedia tools in the teaching and learning processes: A systematic review.

Access to quality education is still a major bottleneck in developing countries. Efforts at opening the access to a large majority of citizens in developing nations have explored different strategies including the use of multimedia technology. This paper provides a systematic review of different multimedia tools in the teaching and learning processes with a view to examining how multimedia technologies have proven to be a veritable strategy for bridging the gap in the provision of unrestricted access to quality education and improved learners' performance. The review process includes conducting an extensive search of relevant scientific literature, selection of relevant studies using a pre-determined inclusion criteria, literature analysis, and synthesis of the findings of the various studies that have investigated how multimedia have been used for learning and teaching processes. The review examines various case study reports of multimedia tools, their success and limiting factors, application areas, evaluation methodologies, technology components, and age groups targeted by the tools. Future research directions are also provided. Apart from text and images, existing tools were found to have multimedia components such as audio, video, animation and 3-D. The study concluded that the majority of the multimedia solutions deployed for teaching and learning target the solution to the pedagogical content of the subject of interest and the user audience of the solution while the success of the different multimedia tools that have been used on the various target groups and subjects can be attributed to the technologies and components embedded in their development.

Prevalence and Awareness about Chlamydial Infection in Women Undergoing Infertility Evaluation in Lagos; Nigeria

Purpose: To determine the prevalence and level of awareness of genital Chlamydia trachomatis infection and possible correlative factors among women undergoing infertility evaluation. Methods: The study involved analysis of demographics and results of chlamydia screening in 77 infertile women undergoing evaluation over a six month period in Lagos; Nigeria. Results: The mean age was 32 + 6.4 yr (range 20-39 yr). Chlamydia screening was positive in 14 (18.2). Awareness about the existence; symptomatology; mode of infection and complications was poor. Statistically significant correlation existed between prevalence of chlamydia infection and age; previous history of sexual infection and minimum of one sexual partner in the last one year (p 0.05). The prevalence also increased in secondarily infertile and married women. Conclusion: Chlamydia prevalence was relatively high in women undergoing infertility evaluation in Lagos; with positive correlative factors being increasing age of women; previous sexual infection and one or more sexual partners