34 research outputs found

    Characterization of Propagation Path Loss at Vhf/Uhf Bands for Ilorin City, Nigeria

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    Path loss exponent, standard deviation and building penetration loss are used in all distance path loss models. Once these data are known for an environment, coverage planning and propagation analysis could be done easily. Many countries across the world, such as Japan, United Kingdom, Germany, and the USA have already published their propagation data, mostly, the path loss exponent for their various cities. However in Nigeria, these data are not available. In this work, measurements were conducted at 203.25 MHz and 583.25 MHz frequencies along ten routes in Ilorin City in Kwara State of Nigeria. Least squares regression method is used to fit the measured data with log-normal propagation path loss model to characterize the path loss parameters. Results of the experiment indicate that the path loss exponent for Ilorin City varies from 1.4 to 4.94 with an average value of 2.80. The work further investigates the behaviour of the TV signals in the same environment in terms of standard deviation and building penetration loss across the routes, and some selected building structures

    Recent Trends on TV White Space Deployments in Africa

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    In this paper, we presented the effects of Television White Space (TVWS) on digital divide in Africa. The trends in digital divide are found to be wide in most African countries, which are characterized with low internet penetration. Perhaps this is expected because over 60 % of people in Africa reside in the rural area and these areas are characterized with low literacy, poverty level and limited telecommunication infrastructure supports. There have been research efforts and regulations towards the secondary use of TV frequencies. However, findings indicate that there are limited opportunities for such system in Europe: This is due to high internet penetration in Europe, but the situation may be quite different in other part of the world like in Africa. Therefore, the TVWS could be used to provide affordable universal access in rural Africa. The paper also presents some benefits developing countries in Africa will incur from utilizing the TVWS solution. Also, recent trend in the deployment of TVWS and experiences got from African countries that embrace the solution are presented.http://dx.doi.org/10.4314/njt.v34i3.1

    Melatonin and Vitamin C modulate cholinergic neurotransmission and oxidative stress in scopolamine-induced rat model of memory impairment

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    Background: Cognitive dysfunction which characterizes dementia is reportedly caused by multiple factors including oxidant-antioxidant imbalance, inflammation, alteration in synaptic neurotransmission. Despite the arrays of drugs available in managing dementia, it appears no single drug can effectively treat dementia. Since it is multifactorial, combining potential drugs may provide neuroprotective impact. As such, this study investigated the neuroprotective effects of melatonin and vitamin C on scopolamine model of cognitive impairment in rats and the possible mechanism of action. Methods: Thirty male Wistar rats were divided to receive either normal saline (5 ml/kg, p.o), scopolamine (1 mg/kg, i.p.), donepezil (2 mg/kg, p.o), melatonin (10 mg/kg, p.o), vitamin C (100 mg/kg. p.o) or melatonin plus vitamin C. Cognitive impairment was induced by daily injection of scopolamine (1 mg/kg, i.p.), after which different treatment regimen were administered for 15 days. Spatial memory was assessed using Morris Water Maze and modified light and dark box. The brain was processed for malondialdehyde (MDA), reduced glutathione (GSH) and acetylcholinesterase (AchE) activity. Results: Scopolamine-treated rats with no intervention showed impaired learning and memory as depicted by a significant (p<0.05) increase in escape latency, reduction in the frequency of visit to the escape aperture, increased MDA, decreased GSH and elevated acetylcholinesterase activity when compared to other groups. Interventions with melatonin or/and vitamin C reversed these responses respectively. The melatonin plus vitamin C treated group compared favorably with donepezil (reference group). Conclusion: Melatonin and vitamin C show neuroprotective effect in attenuating cognitive impairment in scopolamine-induced model by modulating oxidative stress pathway and enhancing cholinergic neurotransmission. Keywords: Dementia, Melatonin, Vitamin C, Memory, Scopolamine

    Evaluation of Methods for the Analysis of Untreated and Processed Lignocellulosic Biomasses

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    The overall efficiency of the transformation of lignocellulosic materials to usable products as chemicals and fuels must be governed by adequate analysis of products before and after treatments. Using some promising technologies, lignocelluloses which are biomasses from marine plant and trees, grains, food and non-food crops, and woodbased can give products as fuel alcohol and other chemicals. Various methods of transformation from feedstock to valuable end products are discussed in the scientific literature. Therefore, yields must justify methods used for biomass transformations. As a result, adequate compositional analysis of these processing stages is needed. In this chapter, standard common methods such as gravimetric, chromatography, spectroscopic and their variations for analysis on both untreated and treated lignocelluloses are highlighted. The ease of the use and challenges with recommendations to their applicability to quantifying lignocelluloses fractionations for reproducibility and to be representative are discussed. With biomass technology, virtually all and even more products that can be produced from fossil energy can also be produced from biomass energy. Adequate analysis is therefore necessary

    The unique resistance and resilience of the Nigerian West African Dwarf goat to gastrointestinal nematode infections

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    <p>Abstract</p> <p>Background</p> <p>West African Dwarf (WAD) goats serve an important role in the rural village economy of West Africa, especially among small-holder livestock owners. They have been shown to be trypanotolerant and to resist infections with <it>Haemonchus contortus </it>more effectively than any other known breed of goat.</p> <p>Methods</p> <p>In this paper we review what is known about the origins of this goat breed, explain its economic importance in rural West Africa and review the current status of our knowledge about its ability to resist parasitic infections.</p> <p>Conclusions</p> <p>We suggest that its unique capacity to show both trypanotolerance and resistance to gastrointestinal (GI) nematode infections is immunologically based and genetically endowed, and that knowledge of the underlying genes could be exploited to improve the capacity of more productive wool and milk producing, but GI nematode susceptible, breeds of goats to resist infection, without recourse to anthelmintics. Either conventional breeding allowing introgression of resistance alleles into susceptible breeds, or transgenesis could be exploited for this purpose. Appropriate legal protection of the resistance alleles of WAD goats might provide a much needed source of revenue for the countries in West Africa where the WAD goats exist and where currently living standards among rural populations are among the lowest in the world.</p

    Prevalence of femoroacetabular impingement and effect of training frequency on aetiology in paediatric football players

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    Purpose: The aim of this study was to determine the prevalence of asymptomatic radiographic findings of femoroacetabular impingement (FAI) in paediatric football players in different age groups and to investigate aetiological factors. Methods: Paediatric male athletes between 10 and 17 years of age from 8 soccer teams were recruited. In addition to an annual control check-up, anteroposterior pelvis and frog-leg radiographs as well as the curriculum vitae of the athletes, their injuries, and real-time complaints were recorded. The alpha angle, lateral centre-edge angle, Tonnis angle, and collodiaphyseal angle were measured and morphological abnormalities were noted. Results: There were 214 male football players with a mean age of 13.4 +/- 3.2 years included in the study. In the morphological analysis of hips, there was FAI in 30% of the athletes. In the analysis of FAI prevalence in 3 subgroups based on age (Group 1: 10-12 years [n = 25], Group 2: 13-15 years [n = 104], Group 3: 16-17 years [n = 85]), there was 0% FAI in Group 1, 19.1% in Group 2 and 60% in Group 3. In the analysis of aetiological factors, there was no significant difference between the right and left hips of players regarding alpha angles and FAI prevalence. However, the prevalence of FAI was higher in players who had been playing football for 3 years or more and who had been training for 12.5 hours/week or more. Conclusion: Training for 12.5 hours or more per week in paediatric football players doubled the risk development of FAI morphology
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