A Q-Learning Based Slice Admission Algorithm for Multi-Tier 5G Cellular Wireless Networks

Network slicing enables a 5G infrastructure provider (network infrastructure owner) to create multiple separate virtual networks, each tailored at a specific performance requirement, on a common physical network.  In this context, slice admission algorithms are required to process slice requests received by the infrastructure provider.  These algorithms are tailored to admit and allocate resources to network slices in a manner that results in the optimization of a given objective.  In this paper, a Q-learning slice admission algorithm, which maximizes the infrastructure provider’s revenue, is designed.  Results show that the designed algorithm learns from its environment, which enables it to acquire knowledge about the multi-tiered cellular network, thus allowing it make optimal slice admission decisions.  The results further show that the designed algorithm has superior performance in terms of revenue achieved when compared to algorithms that admit, a) to maximize immediate rewards and b) slices in a random manner.&nbsp

A Deep Reinforcement Learning Approach to Queue Management and Revenue Maximization in Multi-Tier 5G Wireless Networks

It is envisioned that 5G systems will increasingly leverage on the network slicing concept to meet the demand of diverse services, each tailored for specific user requirements.  In this context, slice admission algorithms that admit slices to the system, that optimize a given objective while ensuring the efficient allocation of resources, are required.  Reinforcement learning has been used successfully to implement optimal slice admission policies.  But as the 5G wireless network becomes more extensive and intricate, the state and action spaces become large.  The efficiency and convergence of reinforcement learning slice admission algorithms is negatively impacted in such a scenario.  To improve on this, deep reinforcement learning, a combination of reinforcement learning and deep learning, has been adopted.  In this paper, a Deep Q-Learning slice admission algorithm is designed; to this end a utility, was developed.  Results show that using the utility as a maximization objective enabled the designed algorithm to (i) optimize the infrastructure provider’s revenue while (ii) providing queue management, in terms of queue length and queue delay

Variations in household microclimate affect outdoor-biting behaviour of malaria vectors

Background: Mosquito behaviours including the degree to which they bite inside houses or outside is a crucial determinant of human exposure to malaria. Whilst seasonality in mosquito vector abundance is well documented, much less is known about the impact of climate on mosquito behaviour. We investigated how variations in household microclimate affect outdoor-biting by malaria vectors, Anopheles arabiensis and Anopheles funestus. Methods: Mosquitoes were sampled indoors and outdoors weekly using human landing catches at eight households in four villages in south-eastern Tanzania, resulting in 616 trap-nights over 12 months. Daily temperature, relative humidity and rainfall were recorded. Generalized additive mixed models (GAMMs) were used to test associations between mosquito abundance and the microclimatic conditions. Generalized linear mixed models (GLMMs) were used to investigate the influence of microclimatic conditions on the tendency of vectors to bite outdoors (proportion of outdoor biting). Results: An. arabiensis abundance peaked during high rainfall months (February-May), whilst An. funestus density remained stable into the dry season (May-August). Across the range of observed household temperatures, a rise of 1ºC marginally increased nightly An. arabiensis abundance (~11%), but more prominently increased An. funestus abundance (~66%). The abundance of An. arabiensis and An. funestus showed strong positive associations with time-lagged rainfall (2-3 and 3-4 weeks before sampling). The degree of outdoor biting in An. arabiensis was significantly associated with the relative temperature difference between indoor and outdoor environments, with exophily increasing as temperature inside houses became relatively warmer. The exophily of An. funestus did not vary with temperature differences. Conclusions: This study demonstrates that malaria vector An. arabiensis shifts the location of its biting from indoors to outdoors in association with relative differences in microclimatic conditions. These environmental impacts could give rise to seasonal variation in mosquito biting behaviour and degree of protection provided by indoor-based vector control strategies

Determination of Appropriate Mix Proportions for the Kenyan Blended Portland Cement Concrete Production

The Kenya’s vision 2030 seeks to address the rising needs of its population through infrastructure development. Reinforced concrete being the most commonly used construction material forms an integral part of this development strategy. The direct substitution of the ordinary Portland cements with the cheaper, lower strength, locally available blended Portland cements could be responsible for the production of poor quality concrete and contribute to the failure of several concrete buildings in the country. This paper presents findings of an experimental investigation on the appropriate mix proportions for the Kenyan blended Portland cement concrete. Key variables used in this study included the water/ cement ratio (x1), the cement/ total aggregates ratio (x2) and the fine aggregates/ coarse aggregates ratio (x3). The response was measured in terms of slump, compressive strengths at 7days, 14days and 28 days and density. Minitab 17 software was used in the design of experiments and results analysis based on Central Composite Design method. The investigation revealed that for a workable concrete with slump of ≥ 30mm, the appropriate mix ratios for the Kenyan blended Portland cement concrete are: 1:2.2:3.4 (w/c 0.6) for strength class C15 and 1:1.3:2.2 (w/c 0.5) for strength class C20. It was further noted that the different brands of blended Portland cement in the country had varying properties and thus produced concrete with different wet and hardened properties. None of the brands achieved the target design strength for strength class C25 and above. Therefore, the blended Portland cements may not be suitable for producing structural concrete strength class C 25 and above

Production systems and contributions of grain legumes to soil health and sustainable agriculture: A review

Sustainable development of agriculture is essential, and there is unanimity that diversification of the cropping systems could support sustainable production. Grain legumes are essential in farming systems in terms of food and nutrition security and income generation. Under legume-based cropping systems, these crops are a potential remedy to pest and disease issues, low nutrient supply, biodiversity protection, and food and nutrition insecurity. In this chapter, we highlight the production systems of legumes and their use in sustainable agricultural production. Specifically, we have looked at the benefits of having a legume cropping system in the agroecosystem, production, and farming systems. The function of legumes in improving the potential of crop productivity is a promising approach to tackling the challenges of poor crop yields and improvement in sustainable production. Due to health and environmental benefits, the focus should shift to breeding grain legumes that can fully express their biological nitrogen fixation and other potentials under abiotic and biotic limitations

INFLUENCE OF MATHEMATICS BRAILLE PROFICIENCY ON MATHEMATICS PERFORMANCE AMONG LEARNERS WITH VISUAL IMPAIRMENT IN SELECTED SPECIAL SECONDARY SCHOOLS IN KENYA

The purpose of this paper is to report some of the findings of a study which investigated the influence of mathematics Braille proficiency on mathematics performance among learners with visual impairment in selected special secondary schools in Kenya. In this study, descriptive design was used with a sample size of 55 respondents comprising of head teachers, mathematics teachers and learners with visual impairment in two special secondary schools. The study respondents were purposively sampled. Findings on the level of mathematics braille proficiency possessed by learners with visual impairment; and the relationship between mathematics Braille skills and mathematics performance are reported. These findings demonstrate a very low level of mathematics Braille skills; and there was a significant positive relationship between mathematics braille proficiency and mathematics performance, particularly among touch readers. These findings confirmed that lack of mathematics braille proficiency contributed to poor mathematics performance. On the basis of these findings, some recommendations are provided. Article visualizations

Comparative Field Evaluation of Combinations of Long-Lasting Insecticide Treated Nets and Indoor Residual Spraying, Relative to Either Method Alone, for Malaria Prevention in an Area where the main Vector is Anopheles Arabiensis.

Long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are commonly used together in the same households to improve malaria control despite inconsistent evidence on whether such combinations actually offer better protection than nets alone or IRS alone. Comparative tests were conducted using experimental huts fitted with LLINs, untreated nets, IRS plus untreated nets, or combinations of LLINs and IRS, in an area where Anopheles arabiensis is the predominant malaria vector species. Three LLIN types, Olyset®, PermaNet 2.0® and Icon Life® nets and three IRS treatments, pirimiphos-methyl, DDT, and lambda cyhalothrin, were used singly or in combinations. We compared, number of mosquitoes entering huts, proportion and number killed, proportions prevented from blood-feeding, time when mosquitoes exited the huts, and proportions caught exiting. The tests were done for four months in dry season and another six months in wet season, each time using new intact nets. All the net types, used with or without IRS, prevented >99% of indoor mosquito bites. Adding PermaNet 2.0® and Icon Life®, but not Olyset® nets into huts with any IRS increased mortality of malaria vectors relative to IRS alone. However, of all IRS treatments, only pirimiphos-methyl significantly increased vector mortality relative to LLINs alone, though this increase was modest. Overall, median mortality of An. arabiensis caught in huts with any of the treatments did not exceed 29%. No treatment reduced entry of the vectors into huts, except for marginal reductions due to PermaNet 2.0® nets and DDT. More than 95% of all mosquitoes were caught in exit traps rather than inside huts. Where the main malaria vector is An. arabiensis, adding IRS into houses with intact pyrethroid LLINs does not enhance house-hold level protection except where the IRS employs non-pyrethroid insecticides such as pirimiphos-methyl, which can confer modest enhancements. In contrast, adding intact bednets onto IRS enhances protection by preventing mosquito blood-feeding (even if the nets are non-insecticidal) and by slightly increasing mosquito mortality (in case of LLINs). The primary mode of action of intact LLINs against An. arabiensis is clearly bite prevention rather than insecticidal activity. Therefore, where resources are limited, priority should be to ensure that everyone at risk consistently uses LLINs and that the nets are regularly replaced before being excessively torn. Measures that maximize bite prevention (e.g. proper net sizes to effectively cover sleeping spaces, stronger net fibres that resist tears and burns and net use practices that preserve net longevity), should be emphasized

Acute toxicity of the aqueous-methanolic Moringa oleifera (Lam) leaf extract on female Wistar albino rats

Background: Herbal preparations are widely assumed to be safe on oral administration and therefore the documentation of the toxic potential of some herbal concoctions used as medicine and nutrients is limited. Moringa oleifera (MO) is a plant that is gaining tremendous popularity in rural communities in Kenya as a means of offsetting nutritional and medicinal needs. However, very little is known about the safety of the plant on oral administration. Thus, the aim of the current study was to assess the biochemical and histological changes in the liver following the administration of an aqueous-methanolic (AQ-ME) MO leaf extract in female Wistar albino rats.Methods: Acute oral toxicity study on the AQ-ME MO leaf extract was conducted by the use of the limit test dose of the up and down procedure (OECD guideline number 425) with slight modifications. Briefly, ten (10) healthy, nulliparous, non-pregnant female Wistar strain albino rats aged               8-12 weeks and weighing 180±20 grams were used for the study. These animals were randomly selected into two groups; control and treatment group each having five (5) animals. They were then labelled to enable identification and control group animals were orally administered with physiological buffer saline once daily over a 48-hour period. The five (5) rats in the treatment group were dosed orally one at a time and once daily with a 2000 mg/kg dose of the AQ-ME MO leaf extract to determine the median lethal dose over a 48 hour period. Blood was then collected and used to prepare serum for biochemical analysis of aspartate amino transferase (AST), alanine amino transferase (ALT) and total bilirubin (TB) which are important biomarkers of liver dysfunction. Biochemical assays of these enzymes were performed using the method of the International Federation of Clinical Chemists (IFCC). Death was used as an endpoint, livers harvested and used to prepare transverse sections for histopathological examination. These sections were stained using the haematoxylin and eosin (H&E) method and observed for pathological changes using an optical microscope.Results: A 2000 mg/kg oral dose of AQ-ME MO leaf extract caused a significant (p0.05) increase in the mean levels of total bilirubin in the treatment group relative to the control group. On the other hand, the extract caused a non-significant (p>0.05) decrease in the mean levels of ALT in the treatment group relative to the control. The post mortem analysis of the hepatic index (liver to body weight ratio) revealed that there was a non-significant increase (p>0.05) in the hepatic index of the treatment group relative to the control. However, the transverse liver sections of treatment group animals showed mild distortions in the architecture of liver cells.Conclusions: Based on these results, the LD50 of the AQ-ME MO leaf extract was found to be >2000 mg/kg in female wistar albino rats

Osteosarcoma to the left Heart

Primary and secondary tumors of the heart are rare. Myxoma is the commonest benign tumor. Of the malignant lesions metastatic heart tumors are more common although these have received little clinical attention. The right side of the heart is more commonly involved while the pericardium and/or myocardium more frequently involved than the endocardium. We present a case of metastatic osteosarcoma into the endocardium of the left atrium. The Annals of African Surgery, Volume 6, 201