This paper presents an iterative technique based on homotopy analysis method for solving system of Volterra Integro-differential equations. The technique provides us series solutions to the problems which are combined with the diagonal Pad\'e approximants and Laplace transform to obtain closed-form solutions. The technique is effectively applied on system of linear and nonlinear Volterra Integro-differential equations which eventually yield closed-form solutions of the problems and this technique is also extended to boundary value problem for the Integro-differential equation related to Blasius problem. An interesting comparison of the present solution is made with solutions of other methods and it is observed that the results are in excellent agreement with other methods in the literature.

This study demonstrates successful synthesis of nanoflower-like birnessite δ-MnO2 materials through a simple and effective hydrothermal technique. Characterization of the flower-like materials grown at various dwell times were carried out by employing scanning electron microscopy (SEM), X-ray diffractometry (XRD), Brunauer-Emmett-Teller (BET) and Barrett–Joyner–Halenda (BJH) models, and electrochemical analysis to understand the effect of different growth time on their morphological, structural, surface area along with pore size distribution and electrochemical characteristics as electrodes for electrochemical capacitors. Attention is mainly based on electrochemical assessment of the as-synthesized materials with an insight into some neutral aqueous electrolytes, mainly lithium sulphate (1 M Li2SO4) and sodium sulphate (1 M Na2SO4) solutions as potential medium owing to their non-corrosive nature, cost-effectiveness, electrochemical stability and environmentally friendliness. Significant charge propagation, with a high specific capacitance of 387.1 F g⁻¹ was achieved for the half-cell electrode in 1 M Li2SO4 alongside excellent cycling stability for up to 5 000 cycles performed at 3 A g⁻¹ specific current. A comprehensive electrochemical assessment is performed to understanding the relationship between solvated and diffused ions of the neutral electrolytes that could result in fast charge storage kinetics as well as high specific capacitance.

A physiologically-based bio-kinetic (PBBK) model, capable of simulating the absorption, distribution, and elimination of cadmium in humans has been developed. The formulation of this model was based on human data cleaned from literature. The liver, kidney, lung, artery, vein, stomach, small intestine and remainder of the body (other tissues not modelled explicitly) were modelled as compartments. While transfer rate coefficients were used to describe the kinetics of cadmium in the gastrointestinal track, the model used blood flow rates and partition coefficients rather than the traditional transfer rate coefficients to describe the distribution and accumulation of the chemical into critical organs such as liver, kidney and remainder of the body. A perfusion rate-limited kinetics model was assumed for these critical organs, where each of these tissues was regarded as a well-stirred compartment, without any concentration gradient within the compartment. The partition coefficients for critical organs modelled, along with transfer rate coefficients describing oral ingestion and inhalation were estimated by fitting the simulated concentration of cadmium in the liver, kidney and urine to observed concentrations found in literature. The model was capable of simulating, to a good degree of success, the results of empirical observations and other simulations found in literature. Simulations by the model also indicate that the partition coefficient of cadmium for the kidney, liver and other critical organs was higher in smokers.

Background: Cerebral oximetry is increasingly becoming a desirable form of monitoring inanaesthesia and critical care. Familiarity with normal values for each device is therefore important. We compared NIRO 300 and INVOS 5100 with the novel MASIMO O3 cerebral oximeter.
Methods: Regional cerebral oxygen saturations (rScO2) of nine healthy volunteers were
measured using NIRO 300, INVOS 5100, and MASIMO O3 under various conditions of hyperoxia, hypocapnia, and change in head position. Changes in vital signs and rScO2 were compared. Reliability analyses of the NIRS devices were performed using Intraclass Correlation Coefficients (ICC) estimates at 95% confidence interval based on 2-way mixed-effects model, multiple rater, and absolute-agreement and consistency selections. P <0.05 was considered statistically significant for this study.
Results: The mean (SD) baseline values from NIRO 300 and INVOS 5100 were comparable
[73.8% (4.2%) vs 73.4% (5.6%) respectively, (p = 0.84)]. The baseline from MASIMO O3 [66.8% (3.9%)] was significantly lower compared to NIRO 300 (p = 0.002), and INVOS 5100 (p = 0.011). Changes in head position were not associated with statistically significant changes in NIRS values (p > 0.05). Significant increases were recorded for each of the NIRS devices at FiO2 = 0.45 and FiO2 = 1 (p = 0.0001) and during supine hyperventilation (p = 0.0001). The Intraclass Correlation Coefficients (ICC) estimates based on 2-way mixed-effects model suggested poor absoluteagreement (0.63; 95% CI = 0.16 - 0.81), but good consistency (0.81; 95% CI = 0.77 - 0.85). Absolute-agreement and consistency tests for NIRO 300 and INVOS 5100 pairs were moderate (0.74; 95% CI = 0.68 - 0.79).
Conclusion: Findings of this study affirm that different NIRS devices give different estimates but similar trends during various interventions. Values from the novel MASIMO O3 were generally lower than NIRO 300 and INVOS 5100.

Prayer marks are asymptomatic nodular and cyst like swellings or callosities with or without chronic skin changes attributable to repeated, prolonged pressure and friction exerted on bony prominences when praying on hard surfaces. This study aimed to describe the clinical and pathological features of forehead prayer marks in Kano, Northwest Nigeria. A retrospective review of Muslims with regular praying habits who presented to the maxillofacial surgery clinic of Murtala Mohammed Specialist Hospital, Kano within a five year (January 2014-December 2018) period on account of central forehead nodular prayer marks was conducted. Biographic data, duration, size, consistency and histological diagnoses of forehead prayer marks were retrieved and analysed. Of the 26 patients with forehead prayer marks, there were 19 men (M: F = 2.7:1). The mean age was 42 ± 3 years and there ages ranged from 15 to 62 years. The mean duration and size of the swellings were 1 ± 5.4 years and 2.5 ± 3.1cm respectively. The consistency of the lesions was mostly soft to firm (n= 23). Seventeen of the lesions were histologically diagnosed as lipoma. Others were fibroma, soft tissue cysts, eosinophilic granuloma and osteoma. Forehead prayer marks are more common in men than women with highest occurrence in fifth decade of life. Lipoma was the commonest post-excision histological diagnosis of forehead prayer marks.

Purpose:To describe the relationship between renal artery resistance index (RARI) and liver function based on Child-Pugh system among patients with liver cirrhosis (LC) in Southwest Nigeria.
Methods:
About 50 patients with LC and 50 controls were consecutively recruited into this prospective comparative case control study. Each LC patient was classed based on Child-Turcotte-Pugh (CTP) system after relevant tests. Subjects underwent abdominal ultrasonography with triplex Doppler examination of the right kidney to obtain RARI.
Results:
About 50 cirrhotic and 50 controls completed the study. Age range of cirrhotic subjects was 19-69 years (mean ± SD = 47.5 ± 13.3) while that of controls was 18-69 years (46.9 ± 15.0). RARI was higher (P = <.001) in patients with LC (0.68) than in controls (0.57). RARI was also significantly higher (P = <.001) in cirrhotic subjects in CTP class C (0.72) than in those in classes B (0.66) and A (0.58). Additionally, RARI showed significant correlation with CTP total score (r = .662; P = <.001), serum bilirubin (r = .297; P = .036), serum albumin (r = -.494; P = <.001), serum sodium (r = -.369; P = .008), Model for End Stage Liver Disease (MELD) score (r = .316; P = .026) and MELD-Na score (r = .470; P = .001). RARI showed no significant relationship with serum creatinine (r = .110; P = .445) and blood urea nitrogen (r = .112; P = .437).
Conclusion:
Liver cirrhosis is associated with renovascular changes which manifest as increased resistance in the renal arteries. RARI is a useful noninvasive tool for the assessment of these changes and should be done routinely in the evaluation of patients with LC.

In this paper, asymptotic stability and global asymptotic stability of solutions to a deterministic and compartmental mathematical model of measles infection is considered using the ideas of the Jacobian determinant as well as the second method of Lyapunov, criteria/conditions that guaranteed asymptotic stability of disease free equilibrium and endemic equilibrium were established. Also the basic reproductive number $R_0$ was obtained. The results in this work compliments existing work and provided further information in controlling the disease in an open population.

Talinum triangulare and Celosia argentea are two common underutilized leafy vegetables in Nigeria. This work was carried out to determine the mineral, proximate, and antinutritional contents of the plants, which were estimated by standard methods. Antibacterial activity of the leaf aqueous and ethanolic extracts was also evaluated against some bacteria. Results obtained from the study have shown that the two plants had constituents that show them as a good source of nutritional and medicinal benefits.

Against the backdrop of measures adopted sequel to the outbreak of the pandemic, this research focuses on the impact of Covid-19 on the workplace. It highlights and interrogates the utility of responsive measures and also articulates recondite labour issues relating to changing work patterns, pay cuts, job losses culminating in growing unemployment rate, and occupational safety and health concerns within the context of extant labour standards. It also extends focus to the impact of Covid-19 on existing challenges revolving around working poverty, decent work deficit, unfair labour practices, and ineffective labour regimes. This research finds, inter alia, that impact of the Covid-19 pandemic on the workplace is colossal, disruptive, and unprecedented, and that extant labour standards, having proved mute on a wide range of contingent workplace issues, can only provide some sort of protection in a detached manner. The research concludes with an array of far-reaching recommendations on the adoption of protective and remedial legal norms that are transient, flexible, and proactive enough to accommodate diverse situations capable of undermining the prospects for labour laws, regulations, and policies in the Covid-19 era.

Hypertension is one of the most important risk factors for stroke and cardiovascular diseases (CVD) globally. Understanding risk factors for hypertension among individuals with matching characteristics with stroke patients may inform primordial/primary prevention of hypertension and stroke among them. This study identified the risk factors for hypertension among community-dwelling stroke-free population in Ghana and Nigeria. Data for 4267 community-dwelling stroke-free controls subjects in the Stroke Investigative Research and Education Network (SIREN) study in Nigeria and Ghana were used. Participants were comprehensively assessed for sociodemographic, lifestyle and metabolic factors using standard methods. Hypertension was defined as a previous diagnosis by a health professional or use of an anti-hypertensive drug or mean systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg. Logistic regression analysis was used to estimate adjusted odds ratios (aOR) of hypertension and their 95% confidence intervals (CI) at p <.05. Overall, 56.7% of the participants were hypertensive with a higher proportion among respondents aged ≥60 years (53.0%). Factors including physical inactivity (aOR: 9.09; 95% CI: 4.03 to 20.53, p <.0001), diabetes (aOR: 2.70; CI: 1.91 to 3.82, p <.0001), being ≥60 years (aOR: 2.22; 95% CI: 1.78 to 2.77, p <.0001), and family history of CVD (aOR 2.02; CI: 1.59 to 2.56, p <.0001) were associated with increased aOR of hypertension. Lifestyle factors were associated with hypertension in the current population of community-dwelling stroke-free controls in west Africa. Community-oriented interventions to address sedentary lifestyles may benefit this population and reduce/prevent hypertension and stroke among them.

Background The burden of stroke in Africa is high. Understanding how age associates with major modifiable stroke risk factors could inform tailored demographic stroke prevention strategies. Purpose To quantify the magnitude and direction of the effect sizes of key modifiable stroke risk factors according to three age groups: <50 years (young), 50–65 years (middle age) and > 65 years (elderly) in West Africa. Methods This was a case-control study involving 15 sites in Ghana and Nigeria. Cases included adults aged ≥18 years with CT/MRI scan-typed stroke. Controls were age-and gender-matched stroke-free adults. Detailed evaluations for vascular, lifestyle and psychosocial factors were performed. We estimated adjusted odds ratios (aOR) using conditional logistic regression and population attributable risk (PAR) with 95% Confidence Interval of vascular risk factors by age groups. Results Among 3553 stroke cases, 813 (22.9%) were young, 1441 (40.6%) were middle-aged and 1299 (36.6%) were elderly. Among the 5 co-shared risk factors, dyslipidemia with PAR and aOR (95%CI) of 62.20% (52.82–71.58) and 4.13 (2.64–6.46) was highest among the young age group; hypertension with PAR of 94.31% (91.82–96.80) and aOR of 28.93 (15.10–55.44) was highest among the middle-age group. Diabetes with PAR of 32.29%(27.52–37.05) and aOR of 3.49 (2.56–4.75); meat consumption with PAR of 42.34%(32.33–52.35) and aOR of 2.40 (1.76, 3.26); and non-consumption of green vegetables, PAR of 16.81%(12.02–21.60) and aOR of 2.23 (1.60–3.12) were highest among the elderly age group. However confidence intervals of risk estimates overlapped across age groups. Additionally, among the young age group cigarette smoking, psychosocial stress and cardiac disease were independently associated with stroke. Furthermore, education, stress, physical inactivity and salt intake were associated with stroke in the middle-age group while cardiac disease was associated with stroke in the elderly age group. Conclusion There is a differential influence of age on the associations of major risk factors with stroke in this West African cohort. Targeting modifiable factors predominant within an age group may be more effective as a stroke prevention strategy.

Background: Stroke risk can be quantified using risk factors whose effect sizes vary by geography and race. No stroke risk assessment tool exists to estimate aggregate stroke risk for indigenous African. Objectives: To develop Afrocentric risk-scoring models for stroke occurrence. Materials and Methods: We evaluated 3533 radiologically confirmed West African stroke cases paired 1:1 with age-, and sex-matched stroke-free controls in the SIREN study. The 7,066 subjects were randomly split into a training and testing set at the ratio of 85:15. Conditional logistic regression models were constructed by including 17 putative factors linked to stroke occurrence using the training set. Significant risk factors were assigned constant and standardized statistical weights based on regression coefficients (β) to develop an additive risk scoring system on a scale of 0–100%. Using the testing set, Receiver Operating Characteristics (ROC) curves were constructed to obtain a total score to serve as cut-off to discriminate between cases and controls. We calculated sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) at this cut-off. Results: For stroke occurrence, we identified 15 traditional vascular factors. Cohen's kappa for validity was maximal at a total risk score of 56% using both statistical weighting approaches to risk quantification and in both datasets. The risk score had a predictive accuracy of 76% (95%CI: 74–79%), sensitivity of 80.3%, specificity of 63.0%, PPV of 68.5% and NPV of 76.2% in the test dataset. For ischemic strokes, 12 risk factors had predictive accuracy of 78% (95%CI: 74–81%). For hemorrhagic strokes, 7 factors had a predictive accuracy of 79% (95%CI: 73–84%). Conclusions: The SIREN models quantify aggregate stroke risk in indigenous West Africans with good accuracy. Prospective studies are needed to validate this instrument for stroke prevention.

Interest in sleep and sleep disorders in Africa dates back thousands of years, influenced by various cultural and religious beliefs. However, the practice of sleep medicine as a specialty has been inadequate compared to other regions of the world. The objective of this study was to explore the current status of sleep medicine in Africa vis-à-vis education, professional societies, and facilities, and to identify challenges of the specialty in the region. A literature search of major electronic databases (PubMed, Google Scholar) was done. This revealed that there is a high prevalence of sleep disorders in Africa and a significant association with epilepsy, human African trypanosomiasis, human immunodeficiency virus, and other diseases. There are 6 sleep societies in Africa located in 4 countries. Forty-one sleep laboratories were identified located in 4 countries. The challenges hindering development of sleep medicine in Africa include lack of awareness, poor funding, lack of facilities, and inadequate training.