Asymptotic stability results for retarded differential systems

The transcendental character of the polynomial equation of the retarded differential system makes it difficult to express its solution explicitly. This has cause a set back in the asymptotic stability analysis of the system solutions. Various acceptable mathematical techniques have been used to address the issue. In this paper, the integral-differential equation and the positive symmetric properties of given matrices are used in formulating a Lyapunov functional. The introduction of convex set segment of a symmetric matrix is explored to establish boundedness of the first derivative of the formulated functional. The integral-differential equation is utilized in computing the maximum delay interval for the system to attain stability. Its application to numerical problems confirms the suitability of the test

Asymptotic stability results for retarded differential systems

The transcendental character of the polynomial equation of the retarded differential system makes it difficult to express its solution explicitly. This has cause a set back in the asymptotic stability analysis of the system solutions. Various acceptable mathematical techniques have been used to address the issue. In this paper, the integral-differential equation and the positive symmetric properties of given matrices are used in formulating a Lyapunov functional. The introduction of convex set segment of a symmetric matrix is explored to establish boundedness of the first derivative of the formulated functional. The integral-differential equation is utilized in computing the maximum delay interval for the system to attain stability. Its application to numerical problems confirms the suitability of the test

Stability results of a mathematical model for the control of HIV/AIDS with the use of male and female condoms in heterosexual populations

A compartmentalized deterministic mathematical model for the dynamics of HIV/AIDS under the use of male and female condoms has been formulated and studied qualitatively. Disease-free equilibria of the sub-models have been found to be locally and asymptotically stable. Stability results revealed threshold values for the proportions of susceptible and infected subpopulations that must use condom in order to achieve control, and possibly, eradication of HIV/AIDS in heterosexual populations. Condom use rate for the susceptible subpopulations has been found to be bounded above by the population’s birth rate, while that of the infected subpopulations is bounded below by a given threshold.KEYWORDS: Locally and asymptotically stable, disease-free equilibrium, HIVAIDS contro

Financial Structure and Financial Performance of Listed Firms in Nigeria

The instability and fluctuations in the financial performance of firms listed on the floor of the Nigerian Stock Exchange has continued to trigger researchers mind on the factors influencing it. In view of this, the study examined the impact of financial structure on financial performance of listed firms in Nigeria Stock Exchange. Data for the study were obtained from the audited annual report of the seventy-one sampled firms for a period of 10 years covering 2009 to 2018. Return on asset (ROA) was used as a measure of financial performance while long term debt to equity, long term debt and short term debt to total asset were used as financial structure variables. The study employed dynamic system generalized method moment (GMM) as technique of analysis and testing of hypotheses. The result shows that long term debt to equity ratio has positive and insignificant impact on ROA while short term debt to total assets ratio have negative and significant impact on return on assets. The study concludes that higher long term and short term debt in the financial structure influences the financial performance of listed firms in Nigeria Stock Exchange. The study recommends among others, managers of firms listed in the Nigeria Stock Exchanges in determination of optimal financial structure should seek for debt with less cost to the firms. Keywords: financial structure, financial performance, long term debt, short term debt, Nigeria Stock Exchange. DOI: 10.7176/RJFA/11-14-15 Publication date:July 31st 202

Soil pests of groundnut in West Africa - species diversity, damage and estimation of yield losses

Among the major arthropods in soil and plant samples taken from groundnut farms during the 1996 cropping season in Mali, Burkina-Faso, Niger, and Nigeria, termites in the genus Microtermes (Isoptera: Termitidae) were the most abundant and widely distributed species of economic importance. None of the termite species identified on trees in the surveyed farms attacked groundnuts. At plant maturity, termites were less frequently observed in soils taken from bare ground but were predominantly found on plants. Residues of previous cereal crops in the fields contributed to termite spread. Most of the whitegrub (Coleoptera: Scarabaeidae) and millipede (Myriapoda: Odontopygidae) species identified belonged to the genera of Schyzonycha and Peridontopyge, respectively. There was a general decrease in both their population densities and the percentages of farms they infested at plant maturity compared to the early stages of the crop. Mean percentages of plants attacked by termites, whitegrubs and millipedes in the surveyed groundnut fields were 39.4, 10.9, and 9.3%, respectively. Yield loss due to termites, which predominantly damaged harvested kernels, was estimated at 9.6-30.4%, and was significantly correlated with percentage of plants damaged by termites (r²=0.73

Insecticidal Evaluation of Some Botanical Leaf Powders On Cowpea Beetle Callosobruchus maculatus (F.) On Stored Bambara Groundnut (Vigna subterranea

Abstract Two Laboratory trials were conducted at the Department of Crop Protection, Faculty o

Using visual documents in distance language learning: Questions raised by an e-learning Business English course

This article presents a pedagogical experience in viewing comprehension in two Master of Management classes, one off-campus and the other on-campus. The objective was to get learners to view an authentic CNN video document on two chief executives at work and to make inferences about their respective management styles. The experience underlines the ease with which on-campus learners are better able to decode the visual cues together without direct teacher input and to read the necessary meaning into such cues while direct teacher mentoring seemed indispensable for the off-campus class. Some questions are raised concerning learner-autonomy and teacher-learner relations in supposedly learner-managed self-directed learning situations.Cet article rend compte d’une expérience en compréhension visuelle menée dans deux classes de Master en Management, l’une en présentiel, l’autre à distance. Nous avons présenté aux étudiants un document vidéo authentique de la chaîne CNN sur deux chefs d’entreprise pour leur faire déduire les styles de management en jeu. Les résultats montrent la facilité relative avec laquelle les étudiants en présentiel sont arrivés à s’approprier les documents et à décoder ensuite les images pratiquement sans aide de l’enseignant, alors que les étudiants à distance ont eu besoin d’aide pour parvenir au même niveau d’appropriation. Parmi les interrogations soulevées, il y a celle qui concerne l’autonomie de l’apprenant et le type de rapports que celui-ci entretient avec l’enseignant dans un cadre d’auto-formation

On the stability of evolution equations

A Quasi-Linear Hyperbolic Evolution problem in a Banach space with m-accretive operator is considered and conditions which guarantee asymptotic stability of its solution in a dense subset of the space are given.Global Jouranl of Mathematical Sciences Vol. 6 (1) 2007: pp. 27-3

A comparative study of roadblend and GB cement stabilizers

GB Cement additive is extensively used in the stabilisation of reconstruction projects throughout Queensland roads. Due to the nature/location of some projects the Department of Transport and Main Roads are currently investigating alternative binders which provide an extended working time. This project was undertaken on behalf of DTMR to research and compare GB Cement additive against a Sunstate Cement product ‘Roadblend’. The principal objective of this study is to provide the best data possible for determining the allowable working time of each binder from testing the effect of varying curing period at 0.75, 2, 3, 4, 6 and 24 hours on Maximum Dry Density (MDD). To maintain consistency in the results a UCS design was performed and only Nerimbra Quarry type 2.1 material (mixed thoroughly) was used for the project testing. The analysis of experimental results indicate that the amount of Roadblend additive required to obtain the desired unconfined compressive strength is nearly 50% less than the required amount of GB Cement. In the other hand, the allowable working time testing results were inconclusive and further testing is required to examine the possible extended working time of the Roadblend additive

On the stability of evolution equations

A Quasi-Linear Hyperbolic Evolution problem in a Banach space with m-accretive operator is considered and conditions which guarantee asymptotic stability of its solution in a dense subset of the space are given.Global Jouranl of Mathematical Sciences Vol. 6 (1) 2007: pp. 27-3