Ibrahim Yusuf | Federal University Lokoja (original) (raw)

Papers by Ibrahim Yusuf

Studies on common cause failures are numerous. Little is done on the effect of common cause failu... more Studies on common cause failures are numerous. Little is done on the effect of common cause failure on measures of system effectiveness like mean time to system failure (MTSF). This paper deals with the modeling and evaluation of MTSF of 2-out-of-5 warm standby repairable system with replacement at the occurrence of each common cause failure. Using Kolmogorov's forward equations method, derivations for mean time to system failure, are presented in this paper. Also numerical illustrations for the mean time to system failure with replacement at each common cause failures and with replacement at system failure only are presented. Comparisons are made based on assumed numerical values for the two mean time to system failure. Mathematics Subject Classification: 90B25

In this paper, we study some reliability characteristics of a repairable linear consecutive 2-out... more In this paper, we study some reliability characteristics of a repairable linear consecutive 2-out-of-4 system. The system work when to two units in a row (consecutive) works. The system is attended by three repairmen. When an operating unit failed, a standby is switched on or an idle operating unit is exchange with the failed unit. The explicit expressions of the reliability characteristics such availability, busy period of the repairmen and profit function are derived. Some cases are analyzed graphically to investigate the impact of system parameters on availability and profit.

The paper presents the explicit expressions for measuring reliability parameter of systems, Graph... more The paper presents the explicit expressions for measuring reliability parameter of systems, Graphs were plotted to highlight important results. Results have shown that measures of system effectiveness such MTSF, system availability and profit increases with repair rates and decreases with failure rates.The developed model helps in determining the optimal maintenance strategies which ensure the maximum overall availability of the system. The optimum values of failure and repair rates for each subsystem were given. It is observed that the first subsystem is having the maximum availability with (97%). The optimum values of failure and repair rates for maximum availability level for each subsystem is also shown.

The Pearson’s correlation coefficients on the relationship between the aggressive behavior, depri... more The Pearson’s correlation coefficients on the relationship between the aggressive behavior, deprivation, well being and relationships between the Inmates of prisons and Waders. The results show that correlation coefficient (0.274 ** ) between aggressive behavior and deprivation is positive and statistically significant at 1% level. This means that deprivation suffered by inmates is one of the key factors that give rise to their aggressive behavior. The results also show that correlation coefficient (-0.096 * ) between aggressive behavior and Inmates’ well being is negative and statistically significant at 5% level. This means that Inmates’ well being is one of the major factors that reduce to their aggressive behavior. The results also reveal that correlation coefficient (-0.113 * ) between aggressive behavior and relationships between the Inmates of prisons and Waders is negative and statistically significant at 5% level. This means that existence of cordial relationship between th...

Clinical Medicine Insights: Cardiology

Background: Inflammatory bowel diseases (IBD) associated-chronic inflammation and autonomic dysre... more Background: Inflammatory bowel diseases (IBD) associated-chronic inflammation and autonomic dysregulation may predispose to arrhythmias. However, its exact prevalence is unknown. Thus, we aimed to ascertain the prevalence of arrhythmias in patients with IBD. Methods: We queried the Nationwide Inpatient Sample (the largest publicly available all-payer inpatient USA database) from 2012 to 2014. We used the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9 CM) discharge codes to identify adult patients (⩾18 years) with IBD and dysrhythmias (supraventricular tachycardia (SVT), atrial fibrillation, atrial flutter, ventricular tachycardia (VT), or ventricular fibrillation). Furthermore, we identified risk factors for cardiovascular disease. We divided patients into 2 cohorts, IBD cohorts, and non-IBD cohort. The independent effect of a diagnosis of IBD on the risk of dysrhythmias was examined using a multivariable logistic regression model controlling ...

Journal of Translational Genetics and Genomics

Stroke is an abrupt loss of brain function, which is caused by the interruption of blood flow to ... more Stroke is an abrupt loss of brain function, which is caused by the interruption of blood flow to the brain. Several blood biomarkers have been evaluated for the assessment of stroke severity and outcome. However, their roles remain limited in clinical practice. Circulating cell-free deoxyribonucleic acid (DNA) has emerged as a potential biomarker of stroke, as reported from several animal and human studies. In this study, we aim to review the prognostic values of cell-free DNA in stroke from all relevant cohort studies. The PubMed database was searched using keywords, "cell-free DNA" and "stroke" for relevant articles. Twelve studies (n = 946 patients) are included in the final analysis. While the prognostic values of cell-free DNA in predicting functional outcomes and hospital mortality after different types of stroke were highlighted in many studies, the inconsistency in methods hinders comparability between studies. Overall, the knowledge about the potential prognostic ability of cell-free DNA in stroke remains limited and conflicting. More robust studies with consistent methods are needed.

Journal of Applied Sciences

Journal of virus eradication, 2018

Ebola virus disease (EVD) in West Africa was an enormous public health challenge. Nigeria was abl... more Ebola virus disease (EVD) in West Africa was an enormous public health challenge. Nigeria was able to contain the spread of the virus with a concerted effort and an effective public health response in terms of identification of contacts, rapid laboratory diagnosis, quarantine and symptomatic treatment. We determined the knowledge, attitude and practice of medical laboratory practitioners (MLPs) in this post-Ebola epidemic era. This cross-sectional study was carried out in eight hospitals in Kano State for 6 months, between January and June 2016. It involved medical laboratory scientists (MLS), medical laboratory technicians (MLT) and medical laboratory assistants (MLA). Questionnaires were administered and analysed. Of the 75 participants, mean knowledge score was 5.54 (standard deviation [SD] ±1.44) while the mean attitude score was 13.72 ±2.80, and mean practice score was 3.10 ±0.80. Mean age of participants was 36.82 ± 8.07 years. There was full awareness of EVD among all 75 part...

Nigerian journal of surgery : official publication of the Nigerian Surgical Research Society

This study aims to audit analytic turnaround time (TAT) in a histopathology laboratory with a vie... more This study aims to audit analytic turnaround time (TAT) in a histopathology laboratory with a view to assessing the timeliness of its reports, identify causes of delay in its TAT, and compare this with client perception of its performance. Records of 1440 batches of specimens processed over a 5-year period in the histopathology laboratory of a teaching hospital were retrieved from archives. From these, median and mean TATs were calculated and causes of delay identified. Questionnaires were also deployed to assess physicians' perception of the laboratory's performance. Analytic TAT was 3.6 ± 2 days, with 86.7% of reports being ready within 5 working days. The delays in timeliness of report generation were due mainly to residency training-related factors; tissue processing-related factors, and inadequate clinical information among others. Client perception of TAT rated the laboratory below average by 18.4%; average by 57.5%; good by 20.7%, and excellent in its performance by 3...

International Journal of Applied Mathematical Research

The paper deals with modeling and performance evaluation of a series-parallel system using Markov... more The paper deals with modeling and performance evaluation of a series-parallel system using Markov Birth-Death process and probabilistic approach. The system consists of four subsystems arranged in series-parallel with three possible states, working with full capacity, reduced capacity and failed. Through the transition diagrams, systems of differential equations are developed and solved recursively via probabilistic approach. Explicit expressions for steady-state availability are de-rived. Availability matrices for each subsystem have been developed to provide various performance values for different combinations of failure and repair rates of all subsystems. The results from this paper will enhance the system performance and useful for timely execution of proper maintenance improvement, decision, planning and optimization.

The article examines the phase of aggressive behavior, deprivation, among the inmate's age gr... more The article examines the phase of aggressive behavior, deprivation, among the inmate's age group of Nigerian prison. However, the study elaborated the meaning of aggressive behavior; factors contributed to aggressive behavior, theory of aggressive behavior, literature review, method of information collection and data analysis. Therefore, prison setting can instigate aggressive behaviors, especially in Nigeria, where inmates are deprived of their particular right and are treated brutality in some instances studies shows, that Nigerian prisons are not adequately organized and made do as such, inmates are exposed to all kinds of atrocity. It should be noted that a condition of privation and lack of societal well-being especially among people being in an isolated environment as in the case with most prisons in Nigeria can degenerate to frustration and aggression which in turn can result in dangerous situations such as riots/ violence in the prisons. Aggression can lead to violence t...

Applied Mathematical Sciences, 2015

This paper considers an optimal replacement model for a system subject to two types of failure. I... more This paper considers an optimal replacement model for a system subject to two types of failure. If the failure is of type 1, the system is minimally repaired. In the case of type 2 failure, the system is minimally repaired with probability p and replaced with probability 1 qp . A modified random and age replacement model is considered in which the system is replaced at a planned time T, at a random working time Y, or at the first non repairable type 2 failure whichever occurs first. Explicit expression for the expected total cost and the optimal replacement time T, minimizing the expected total cost are derived analytically. Finally, numerical example is considered to highlight the characteristics of the policy.

IOSR Journal of Humanities and Social Science, 2016

The report examines differences in aggressive behaviour, deprivation, well being and frustration ... more The report examines differences in aggressive behaviour, deprivation, well being and frustration among the inmates in relation to their age and marital status in congested Nigerian prison. However, the work consists of an introduction, age and aggressive behaviour, race and aggressive behaviour, method of information collection and data analysis, and determination. Past studies have shown that males are socialized to believe they should not back down when they are provoked and, if they do, they accept a chance losing their identity, may in turn act upon them to involve in aggressive conduct. An interesting finding by the Benenson (2009) found that males intention to involve in aggressive behaviour is a substance to increase integrity and strength. Moreover, males are more likely than females to have intended to involve in aggressive behaviour negatively when there is conflict, and females intention to involve in aggressive behaviour is for power and influence over others through indirect and verbal aggressive behaviour. According to the 2015 International encyclopedia of the societal and behavioural skills, sex differences in aggression are one of the most rich and most previous findings in psychology. Post meta-analyses in the encyclopedia found males regardless of years engaged in more physical and verbal aggression while small effect for females engaging in more indirect aggression such as rumour spreading or gossiping indirect, tends to increase after age two while physical aggression decreases. At that place was no significant difference in aggression between males and females before two years of age. A possible explanation for this could be that young women make up language skills more quickly than male children, and then they take in more dependable ways of verbalizing their wants and needs. They are more probable to use communication when trying to recover a toy with the words. According to the journal of Aggressive Behaviour, analysis across 9 countries found boy reported more on the use of physical aggression. At the same time no consistent gender differences emerged within relational aggression. It has been found that young women are more likely than sons to use reactive aggression and then retract, but sons are more likely to increase rather than to pull back their aggression after their first response. Studies show girls' aggressive tactics included gossip, ostracism, breaking confidences, and criticism of a victim's clothing, visual aspect, or personality, whereas boys engage in aggression that involves a direct physical and/or verbal assault. This could be due to the fact that the girls' frontal lobes develop earlier than male children, allowing them to self-limit.

We evaluated the changes in blood profile of patients in a prospective 30 month observational fol... more We evaluated the changes in blood profile of patients in a prospective 30 month observational follow up study involving 145 antiretroviral naive acquired immune deficiency syndrome (AIDS) participants. Participants were divided into two groups at one year of highly active antiretroviral therapy (HAART), antiviral success (viral load < 2.60 log 10 copies/ml); and antiviral failure (viral load > 2.60 log 10 copies/ml. The mean ± standard deviation (SD) viral load in the antiviral success group (119 patients) was 5.25 ± 0.53 and 5.09 ± 0.71 log 10 copies/ml in antiviral failure group at baseline. Antiviral success cohort had significant reduction of viral load at 6 months, achieved viral suppression at one year and maintained undetectable viral load in the subsequent follow-up period. Antiviral failure participants on the other hand failed to achieve significant viral load suppression at six month and had fluctuation and persistence of viral load. In the antiviral success group, ...

In this paper, we studied a series system consisting of single unit. The system is subjected to t... more In this paper, we studied a series system consisting of single unit. The system is subjected to three types of failures. Type I failure is minor in which the system is imperfectly repaired. Type II failure is major in which the entire system is replaced. Type III failure is called a partial failure in which the system works in reduced capacity and is perfectly repaired. Failure and repair time are assumed exponential. We developed the explicit expressions for mean time to system failure (MTSF), steady-state availability, busy period and profit function using Kolmogorov forward equations method. Special cases are studied to determine the impact of various system parameters on MTSF, busy period, steady-state availability and profit function.

Applied Mathematical Sciences

This paper presents a study on reliability characteristics of two dissimilar systems. System I co... more This paper presents a study on reliability characteristics of two dissimilar systems. System I consist of two paths while system II consist of three paths. A signal flow from the source to the terminal through the paths. Failure times and service times of each system are assumed to be exponentially distributed. The failure and repair times assumed exponentially distributed. Using Kolmogorov’s forward equations method, derivations for availability, busy period and profit function are presented in this paper. Also numerical illustrations for the two systems are presented. Comparisons are made based on assumed numerical values for the two systems.

INTERNATIONAL JOURNAL OF RESEARCH – GRANTHAALAYAH

Technology will continue to develop and change how journalism is practice, it will bring with it ... more Technology will continue to develop and change how journalism is practice, it will bring with it new challenges and learning curves. What will not change is the public’s demand for news and information, the kind that helps them manage their personal lives and make decisions as educated citizens in the public realm. While much discussion focuses on how we read the news, technology is changing the way we report the news. The image of a reporter showing up to a scene with a pen and a pad is iconic but will soon lose to the vestiges of time. This paper argues that the Newspaper media will continue to satisfy this public demand using the new tools of technological innovation. They will expand their audiences and engage them in novel and exciting ways. Therefore, justice was done to the discussion by providing answers to the following guiding questions: In what form are social media projected / displayed in prints and electronic media? What use have they been put into? For what purpose ar...

Journal of Industrial Engineering International, 2014

American Journal of Applied Mathematics and Statistics, 2014

Open Journal of Applied Sciences, 2013

In this paper, we study the reliability and availability characteristics of a repairable system c... more In this paper, we study the reliability and availability characteristics of a repairable system consisting of two subsystems A and B in series. Subsystem A consists of two units A 1 and A 2 operating in active parallel while subsystem B is a single unit. Failure and repair times are assumed exponential. The explicit expressions of reliability and availability characteristics like mean time to system failure (MTSF), system availability, busy period and profit function are derived using Kolmogorov forward equations method. Various cases are analyzed graphically to investigate the impacts of system parameters on MTSF, availability, busy period and profit function.