69 research outputs found
New History Matching Methodology for Two Phase Reservoir Using Expectation-Maximization (EM) Algorithm
The Expectation-Maximization (EM) Algorithm is a well-known method for estimating maximum likelihood and can be used to find missing numbers in an array. The EM Algorithm has been used extensively in Electrical and Electronics Engineering as well as in the Biometrics industries for image processing but very little use of the EM Algorithm has been seen in the Oil and Gas industry, especially for History Matching. History matching is a non-unique matching of oil rate, water rate, gas rate and bottom hole pressure data of a producing well (known as Producer) as well as the bottom hole pressure and liquid injection of an injecting well (known as Injector) by adjusting reservoir parameters such as permeability, porosity, Corey exponents, compressibility factor, and other pertinent reservoir parameters. EM Algorithm is a statistical method that guarantees convergence and is particularly useful when the likelihood function is a member of the exponential family. On the other hand, EM algorithm can be slow to converge, and may converge to a local optimum of the observed data log likelihood function, depending on the starting values.
In this research, our objective is to develop an algorithm that can be used to successfully match the historical production data given sparse field data. Our approach will be to update the permeability multiplier, thereby updating the permeability of each unobserved grid cell that contributes to the production at one or more producing wells. The EM algorithm will be utilized to optimize the permeability multiplier of each contributing unobserved grid cell
The Comparison of the Performance of ARIMA and MA Model Selection on Road Accident Data in Nigeria
In this research work, time series model selection was performed by given consideration for a number of models that most suitable for the incidence of accident cases in Nigeria. Among the candidate models considered are the Autoregressive Integrated Moving Average (ARIMA) and Moving Average (MA) models each at various parameters specifications. Results from this work showed that the best models that are suitable to describe the accident cases in Nigeria are the ARIMA(3,1,1) and MA(0,1,2) according to the Mean Square Error (MSE) and Akaike Information Criteria (AIC). National data set on cases of accident in Nigeria
Determinants of Uptake of Periodic Medical Examination among Students of College of Health Sciences, Obafemi Awolowo University Ile-Ife, South-West Nigeria
Background: This research was conducted to assess the factors that determine the uptake of periodic medical examination (PME) amongundergraduate students in Ile‑Ife, Nigeria.
Methods: Asample size of 328 was calculated using the sample size formula for a single proportion. Hence, a total of 328 undergraduate students of the College of Health Sciences at the Obafemi Awolowo University, Ile‑Ife, were included in this descriptive, cross‑sectional study. A multistage sampling technique was adopted and the sampling was proportional to the size of the four undergraduate academic programs in the college. Data were collected using a self‑administered questionnaire. Chi‑square and t-tests were used to assess significant factors associated with its uptake. The determinants of PME uptake were identified using binary logistic regression.
Results: The majority of the respondents, 299 (91.2%), were aware of PME. The uptake was however poor, 93 (28.4%). The most commonbarrier to the uptake was “inadequate time” due to the students’ perceived busy schedule. Others were religion, years spent in school, perceived susceptibility to diseases, cost of service, fear of the results, and lack of interest. The odd of uptake of PME was 18.3 times higher among people that express willingness relative to the participants without intention to uptake PME, P < 0.001.
Conclusion: The uptake of PME was poor despite the high level of awareness probably due to the perceived low disease susceptibility among the students and poor access to PME services. There is, therefore, a need for creating an enabling environment through policy formulation by the university’s management to address the barriers against the uptake of PME. Sensitization on the risk factors of chronic non-communicable diseases is also necessary to address the poor perception of susceptibility.
Keywords: Determinants, Ile‑Ife, periodic medical examination, Southwest Nigeria, undergraduate
Quantitative pupillometry and radiographic markers of intracranial midline shift: A pilot study
BackgroundAsymmetric pupil reactivity or size can be early clinical indicators of midbrain compression due to supratentorial ischemic stroke or primary intraparenchymal hemorrhage (IPH). Radiographic midline shift is associated with worse functional outcomes and life-saving interventions. Better understanding of quantitative pupil characteristics would be a non–invasive, safe, and cost-effective way to improve identification of life-threatening mass effect and resource utilization of emergent radiographic imaging. We aimed to better characterize the association between midline shift at various anatomic levels and quantitative pupil characteristics.MethodsWe conducted a multicenter retrospective study of brain CT images within 75 min of a quantitative pupil observation from patients admitted to Neuro-ICUs between 2016 and 2020 with large (>1/3 of the middle cerebral artery territory) acute supratentorial ischemic stroke or primary IPH > 30 mm3. For each image, we measured midline shift at the septum pellucidum (MLS-SP), pineal gland shift (PGS), the ratio of the ipsilateral to contralateral midbrain width (IMW/CMW), and other exploratory markers of radiographic shift/compression. Pupil reactivity was measured using an automated infrared pupillometer (NeurOptics®, Inc.), specifically the proprietary algorithm for Neurological Pupil Index® (NPi). We used rank-normalization and linear mixed-effects models, stratified by diagnosis and hemorrhagic conversion, to test associations of radiographic markers of shift and asymmetric pupil reactivity (Diff NPi), adjusting for age, lesion volume, Glasgow Coma Scale, and osmotic medications.ResultsOf 53 patients with 74 CT images, 26 (49.1%) were female, and median age was 67 years. MLS-SP and PGS were greater in patients with IPH, compared to patients with ischemic stroke (6.2 v. 4.0 mm, 5.6 v. 3.4 mm, respectively). We found no significant associations between pupil reactivity and the radiographic markers of shift when adjusting for confounders. However, we found potentially relevant relationships between MLS-SP and Diff NPi in our IPH cohort (β = 0.11, SE 0.04, P = 0.01), and PGS and Diff NPi in the ischemic stroke cohort (β = 0.16, SE 0.09, P = 0.07).ConclusionWe found the relationship between midline shift and asymmetric pupil reactivity may differ between IPH and ischemic stroke. Our study may serve as necessary preliminary data to guide further prospective investigation into how clinical manifestations of radiographic midline shift differ by diagnosis and proximity to the midbrain
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Global age-sex-specific mortality, life expectancy, and population estimates in 204 countries and territories and 811 subnational locations, 1950–2021, and the impact of the COVID-19 pandemic: a comprehensive demographic analysis for the Global Burden of Disease Study 2021
Background
Estimates of demographic metrics are crucial to assess levels and trends of population health outcomes. The profound impact of the COVID-19 pandemic on populations worldwide has underscored the need for timely estimates to understand this unprecedented event within the context of long-term population health trends. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 provides new demographic estimates for 204 countries and territories and 811 additional subnational locations from 1950 to 2021, with a particular emphasis on changes in mortality and life expectancy that occurred during the 2020–21 COVID-19 pandemic period.
Methods
22 223 data sources from vital registration, sample registration, surveys, censuses, and other sources were used to estimate mortality, with a subset of these sources used exclusively to estimate excess mortality due to the COVID-19 pandemic. 2026 data sources were used for population estimation. Additional sources were used to estimate migration; the effects of the HIV epidemic; and demographic discontinuities due to conflicts, famines, natural disasters, and pandemics, which are used as inputs for estimating mortality and population. Spatiotemporal Gaussian process regression (ST-GPR) was used to generate under-5 mortality rates, which synthesised 30 763 location-years of vital registration and sample registration data, 1365 surveys and censuses, and 80 other sources. ST-GPR was also used to estimate adult mortality (between ages 15 and 59 years) based on information from 31 642 location-years of vital registration and sample registration data, 355 surveys and censuses, and 24 other sources. Estimates of child and adult mortality rates were then used to generate life tables with a relational model life table system. For countries with large HIV epidemics, life tables were adjusted using independent estimates of HIV-specific mortality generated via an epidemiological analysis of HIV prevalence surveys, antenatal clinic serosurveillance, and other data sources. Excess mortality due to the COVID-19 pandemic in 2020 and 2021 was determined by subtracting observed all-cause mortality (adjusted for late registration and mortality anomalies) from the mortality expected in the absence of the pandemic. Expected mortality was calculated based on historical trends using an ensemble of models. In location-years where all-cause mortality data were unavailable, we estimated excess mortality rates using a regression model with covariates pertaining to the pandemic. Population size was computed using a Bayesian hierarchical cohort component model. Life expectancy was calculated using age-specific mortality rates and standard demographic methods. Uncertainty intervals (UIs) were calculated for every metric using the 25th and 975th ordered values from a 1000-draw posterior distribution.
Findings
Global all-cause mortality followed two distinct patterns over the study period: age-standardised mortality rates declined between 1950 and 2019 (a 62·8% [95% UI 60·5–65·1] decline), and increased during the COVID-19 pandemic period (2020–21; 5·1% [0·9–9·6] increase). In contrast with the overall reverse in mortality trends during the pandemic period, child mortality continued to decline, with 4·66 million (3·98–5·50) global deaths in children younger than 5 years in 2021 compared with 5·21 million (4·50–6·01) in 2019. An estimated 131 million (126–137) people died globally from all causes in 2020 and 2021 combined, of which 15·9 million (14·7–17·2) were due to the COVID-19 pandemic (measured by excess mortality, which includes deaths directly due to SARS-CoV-2 infection and those indirectly due to other social, economic, or behavioural changes associated with the pandemic). Excess mortality rates exceeded 150 deaths per 100 000 population during at least one year of the pandemic in 80 countries and territories, whereas 20 nations had a negative excess mortality rate in 2020 or 2021, indicating that all-cause mortality in these countries was lower during the pandemic than expected based on historical trends. Between 1950 and 2021, global life expectancy at birth increased by 22·7 years (20·8–24·8), from 49·0 years (46·7–51·3) to 71·7 years (70·9–72·5). Global life expectancy at birth declined by 1·6 years (1·0–2·2) between 2019 and 2021, reversing historical trends. An increase in life expectancy was only observed in 32 (15·7%) of 204 countries and territories between 2019 and 2021. The global population reached 7·89 billion (7·67–8·13) people in 2021, by which time 56 of 204 countries and territories had peaked and subsequently populations have declined. The largest proportion of population growth between 2020 and 2021 was in sub-Saharan Africa (39·5% [28·4–52·7]) and south Asia (26·3% [9·0–44·7]). From 2000 to 2021, the ratio of the population aged 65 years and older to the population aged younger than 15 years increased in 188 (92·2%) of 204 nations.
Interpretation
Global adult mortality rates markedly increased during the COVID-19 pandemic in 2020 and 2021, reversing past decreasing trends, while child mortality rates continued to decline, albeit more slowly than in earlier years. Although COVID-19 had a substantial impact on many demographic indicators during the first 2 years of the pandemic, overall global health progress over the 72 years evaluated has been profound, with considerable improvements in mortality and life expectancy. Additionally, we observed a deceleration of global population growth since 2017, despite steady or increasing growth in lower-income countries, combined with a continued global shift of population age structures towards older ages. These demographic changes will likely present future challenges to health systems, economies, and societies. The comprehensive demographic estimates reported here will enable researchers, policy makers, health practitioners, and other key stakeholders to better understand and address the profound changes that have occurred in the global health landscape following the first 2 years of the COVID-19 pandemic, and longer-term trends beyond the pandemic
Predicting Commitment Forms From Psychological Contract Breach And Violation Among Survivors Of Merged Banks In Nigeria
In this study three forms of commitment were assumed to be predicted by the different dimensions of psychological contract breach and Psychological contract violation measures from employees who survived mergers and acquisition in some selected banks in Lagos metropolis, Nigeria. Using an ex post facto design, a sample of 280employees comprising of 174(62.7%) males, with age ranging between 22 and 51 years, mean age of 33.2 years and a S.D of 6.182 from eight (4 merged and 4 acquiring) banks in Lagos metropolis completed the questionnaire designed for the purpose. It was hypothesised that dimensions of psychological contract breach will significantly predict different forms of employee commitment, and that psychological contract violation will significantly negatively predict commitment. The results of the multiple regression analysis reveal that psychological contract breach and psychological contract violation resulting from mergers and acquisition contributed least to continuance, and affective commitments. A significant joint and independent influence of psychological contract breach and psychological contract violation on affective (R2 = .17 = F( 8, 272) = 6.76
Statistical Analysis on Students’ Performance
This research uses Cohen’s Kappa to examine the performance of students in the Faculty of Science, University of Ilorin. The data was collected from eight departments in the faculty and it covers the performance of students measured by their Grade Point Average (GPA) and Cumulative Grade Point Average (CGPA) in both their first and final year between 2000-2006 academic sessions. It is of interest to determine the proportion of students that improved on their performance, dropped from the class of grade point which they started with and those that maintained their performance using psychometrics approach. Also, the strength of agreement that exist between the first and the final year was examined
Demystifying Mobile Banking App Security Through Gender, Education, Privacy, and Trust Intervention
The escalating of mobile banking apps has decongested the banking hall, especially in developing countries, and the penetration of mobile banking apps is crucial for both financial institutions and customers. This study reviewed existing relevant literature from the Web of Science to position this study well and dwelled on a theoretical foundation for the exposition of the interrelation of trust and privacy as an antecedent of mobile banking app security. The quantitative method was employed and banking customers data using SmartPLS 3.0 version with different data analysis techniques such as structural equation modelling, multigroup data analysis, interaction effects, and importance-performance analysis. This study results show the intervention of gender and education. It also indicates that the orientation and persuasion of banking customers to the point of higher trust is a determinant of security assurance of using mobile banking apps. This study discusses the theoretical and managerial impacts with the limitation of the study and projects into the future
Bibliometric structured review of tuberculosis in Nigeria
The tuberculosis burden is growing in Nigeria along with its population. For example, Nigeria has the sixth highest TB burden globally, with an estimated 4.3 per cent multi-drug resistance in new cases. This study builds on the existing study that examined academic involvement in tuberculosis research. The study in question focused on global medical literature related to tuberculosis, but the non-visibility of some low and middle-income countries in the bigger global picture motivated this present study. Every year, over 245,000 Nigerians succumb to tuberculosis (TB), with approximately 590,000 new cases reported (of these, around 140,000 are also HIV-positive). This study carried out an academic publication evaluation with the VOS viewer tool to map bibliometric data for scholarly articles published between 1991 and 2021 on tuberculosis research and used the Biblioshiny app for analytics and plots of authors, sources, and documents to explore the descriptive statistics of tuberculosis literature. The present study delineates that England has the highest collaborating country with Nigeria in the study of tuberculosis over the years and according to the report, the University of Nigeria, the University of Ibadan, and Nnamdi Azikwe University are Nigerian institutions with extensive collaborations. This study concludes with managerial implications for future actions
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