Pub Date : 2024-09-21DOI: 10.1016/j.sciaf.2024.e02406
Kingstone Nyakurukwa, Yudhvir Seetharam
The purpose of this study is to investigate the return spillovers among the five systemically important banks in South Africa. The study employs a time-varying parameter vector autoregression (TVP-VAR) framework utilising daily data between 2000 and 2024. A minimum return connectedness portfolio is constructed from the spillover indexes and compared with traditional portfolio optimisation methods in terms of risk reduction and reward-to-risk ratios. The research findings reveal that Capitec, the smallest bank in terms of assets, has weaker return connectedness with other banks while ABSA, FirstRand, Nedbank and Standard Bank are moderately connected. Moreover, the two largest banks in terms of assets, Standard and FirstRand, are more connected than any other pairwise connection in the network. During significant events such as national elections, the global financial crisis and the COVID-19 pandemic, system-wide connectedness increases.
{"title":"On bank stock return spillovers in South Africa: Implications for portfolio hedging","authors":"Kingstone Nyakurukwa, Yudhvir Seetharam","doi":"10.1016/j.sciaf.2024.e02406","DOIUrl":"10.1016/j.sciaf.2024.e02406","url":null,"abstract":"<div><div>The purpose of this study is to investigate the return spillovers among the five systemically important banks in South Africa. The study employs a time-varying parameter vector autoregression (TVP-VAR) framework utilising daily data between 2000 and 2024. A minimum return connectedness portfolio is constructed from the spillover indexes and compared with traditional portfolio optimisation methods in terms of risk reduction and reward-to-risk ratios. The research findings reveal that Capitec, the smallest bank in terms of assets, has weaker return connectedness with other banks while ABSA, FirstRand, Nedbank and Standard Bank are moderately connected. Moreover, the two largest banks in terms of assets, Standard and FirstRand, are more connected than any other pairwise connection in the network. During significant events such as national elections, the global financial crisis and the COVID-19 pandemic, system-wide connectedness increases.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"26 ","pages":"Article e02406"},"PeriodicalIF":2.7,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142323094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-21DOI: 10.1016/j.sciaf.2024.e02390
Abate Feyissa Senbeta , Walelign Worku , Sebastian Gayler
Studies focusing on the spatiotemporal distribution of climatic parameters and meteorological drought are of paramount significance for countries like Ethiopia, where climate change and variability cause major losses to rain-dependent agriculture. In this study, the National Meteorology Institute of Ethiopia provided an Enhanced National Climate Services (ENACTS) dataset at a spatial resolution of approximately 4 km by 4 km over 38 years (1981–2018) was used to study climate trends, spatiotemporal variability, and meteorological drought in the Central Ethiopia Region. Coefficient of variation (CV), Standardized Rainfall Anomaly (SRA), Standardized Precipitation Index (SPI), Mann-Kendall trend test, and Sen's slope were used for the analysis. The findings suggest that Belg rainfall (also known as "small-rain") varied greatly in space and time over the study area, with area-averaged CV of 29 % and pixel-level CVs ranging from 63 to 93 %. The average precipitation during Belg experienced a 15 % decrease from 2000 to 2019 compared to the preceding two decades, from 1981 to 1999. The maximum temperature has increased significantly during the Annual, Belg, and Bega seasons. The SPI and SRA showed that there have been multiple drought episodes with rising negative rainfall anomalies, with a drought occurring every 2.9 years during the Kiremt (also called "big rain", spanning from June to September) and Belg seasons. The growing negative rainfall anomaly, high CV, and highly significant increase in mean maximum temperature during the Belg season is concerning for food security and poverty eradication. The notable rise in rainfall during the June (sowing period) and November (harvesting period) also hurts crop production during the main cropping season. Thus, developing appropriate adaptation strategies and policies oriented toward climate-resilient agriculture is crucial to meet the global sustainable development goals (SDGs) and Africa Union's Agenda 2063.
{"title":"Spatiotemporal climate variability and food security implications in the Central Ethiopia Region","authors":"Abate Feyissa Senbeta , Walelign Worku , Sebastian Gayler","doi":"10.1016/j.sciaf.2024.e02390","DOIUrl":"10.1016/j.sciaf.2024.e02390","url":null,"abstract":"<div><p>Studies focusing on the spatiotemporal distribution of climatic parameters and meteorological drought are of paramount significance for countries like Ethiopia, where climate change and variability cause major losses to rain-dependent agriculture. In this study, the National Meteorology Institute of Ethiopia provided an Enhanced National Climate Services (ENACTS) dataset at a spatial resolution of approximately 4 km by 4 km over 38 years (1981–2018) was used to study climate trends, spatiotemporal variability, and meteorological drought in the Central Ethiopia Region. Coefficient of variation (CV), Standardized Rainfall Anomaly (SRA), Standardized Precipitation Index (SPI), Mann-Kendall trend test, and Sen's slope were used for the analysis. The findings suggest that Belg rainfall (also known as \"small-rain\") varied greatly in space and time over the study area, with area-averaged CV of 29 % and pixel-level CVs ranging from 63 to 93 %. The average precipitation during Belg experienced a 15 % decrease from 2000 to 2019 compared to the preceding two decades, from 1981 to 1999. The maximum temperature has increased significantly during the Annual, Belg, and Bega seasons. The SPI and SRA showed that there have been multiple drought episodes with rising negative rainfall anomalies, with a drought occurring every 2.9 years during the Kiremt (also called \"big rain\", spanning from June to September) and Belg seasons. The growing negative rainfall anomaly, high CV, and highly significant increase in mean maximum temperature during the Belg season is concerning for food security and poverty eradication. The notable rise in rainfall during the June (sowing period) and November (harvesting period) also hurts crop production during the main cropping season. Thus, developing appropriate adaptation strategies and policies oriented toward climate-resilient agriculture is crucial to meet the global sustainable development goals (SDGs) and Africa Union's Agenda 2063.</p></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"26 ","pages":"Article e02390"},"PeriodicalIF":2.7,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2468227624003326/pdfft?md5=5be88ca2fee6d380eff1eee1d9c345a1&pid=1-s2.0-S2468227624003326-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142274642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article aims to analyze the factors that determine local employment in the mining sector and identify ways to improve the annual income of employed households in the Benishangul-Gumuz Regional State (BGR) of Ethiopia. The research design used for this study was cross-sectional. Quantitative data were collected from a sample of 162 households affected by mining operations, using systematic random sampling. Additionally, four focus group discussions (FGD) and eight key informant interviews (KII) were conducted to gather qualitative data. The quantitative data was analyzed using descriptive statistics and the Heckman two-stage model, while the qualitative data was analyzed using narrative analysis. The descriptive results indicate that most of the jobs created by the mining industries were temporary, and the small-scale mining sector employed more workers than the large-scale sector. Furthermore, migrant laborers benefited more from employment opportunities than indigenous households. The first result of the Heckman two-stage model reveals that the educational level of the household head, the size of the farmland, and membership in a farmer's organization have significant negative effects on local employment. On the other hand, the sex of the household head, the size of the nearest mining project, access to information, access to transport, and access to credit have significant positive effects on local employment. The second-stage results of the Heckman two-stage model show that the age of the household head, the dependency ratio, and membership in farmers' organizations have statistically significant negative effects on the annual income of employed households. Conversely, non-farm activities have statistically significant positive effects on the annual income of employed households. The findings of this study have implications for identifying the determinants and factors that need to be addressed to promote local employment. We suggest that both the Ethiopian and BGR regional governments should work towards increasing local employment opportunities for indigenous communities in the mining sector.
{"title":"Analysis of the factors influencing local employment in the mining sector in the Benishangul-Gumuz Regional state of Ethiopia","authors":"Netsanet Zeleke Haile , Admassu Tesso Huluka , Amsalu Bedemo Beyene","doi":"10.1016/j.sciaf.2024.e02364","DOIUrl":"10.1016/j.sciaf.2024.e02364","url":null,"abstract":"<div><div>This article aims to analyze the factors that determine local employment in the mining sector and identify ways to improve the annual income of employed households in the Benishangul-Gumuz Regional State (BGR) of Ethiopia. The research design used for this study was cross-sectional. Quantitative data were collected from a sample of 162 households affected by mining operations, using systematic random sampling. Additionally, four focus group discussions (FGD) and eight key informant interviews (KII) were conducted to gather qualitative data. The quantitative data was analyzed using descriptive statistics and the Heckman two-stage model, while the qualitative data was analyzed using narrative analysis. The descriptive results indicate that most of the jobs created by the mining industries were temporary, and the small-scale mining sector employed more workers than the large-scale sector. Furthermore, migrant laborers benefited more from employment opportunities than indigenous households. The first result of the Heckman two-stage model reveals that the educational level of the household head, the size of the farmland, and membership in a farmer's organization have significant negative effects on local employment. On the other hand, the sex of the household head, the size of the nearest mining project, access to information, access to transport, and access to credit have significant positive effects on local employment. The second-stage results of the Heckman two-stage model show that the age of the household head, the dependency ratio, and membership in farmers' organizations have statistically significant negative effects on the annual income of employed households. Conversely, non-farm activities have statistically significant positive effects on the annual income of employed households. The findings of this study have implications for identifying the determinants and factors that need to be addressed to promote local employment. We suggest that both the Ethiopian and BGR regional governments should work towards increasing local employment opportunities for indigenous communities in the mining sector.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"26 ","pages":"Article e02364"},"PeriodicalIF":2.7,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142420352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A functionally graded material is a class of composite materials characterized by gradual variations in composition and microstructure, which further induces the respective changes in the material properties. This study focuses on evaluating the vibration behavior of two directional functionally graded taper porous beams (FGTPB). This approach adopts a rectangular cross-section in order to deal with the challenges related to fluctuating material characteristics and geometric tapering in both thickness and width dimensions. The research employs a novel approach that merges Vogel's approximation technique with the Random Forest algorithm, an approach that has not been used in analyzing structural vibrations, establish boundary conditions and solve equations of motion. Comparative results of the suggested beam theory with the existing literature on FGTPB materials such as alumina and SUS304 at various taper, porosity, gradient and width ratios verified it. The material gradation and porosity developed a uniform pattern in the first three modes of fundamental frequencies. Higher gradient indices increased the rigidity and natural frequencies of the beams whereas the porosity index decreased the rigidity, resulting in lower natural frequencies. By combining Vogel's approximation method with machine learning techniques, the study improved vibration behavior analysis in FGTPB. The disciplines of materials and structural engineering are significantly impacted by this.
{"title":"The novel Vogel's approximation method integrated with a random forest algorithm in the vibration analysis of a two-directional functionally graded taper porous beam: Assessment","authors":"Ravikiran Chintalapudi , Geetha Narayanan Kannaiyan , Bridjesh Pappula , Seshibe Makgato","doi":"10.1016/j.sciaf.2024.e02397","DOIUrl":"10.1016/j.sciaf.2024.e02397","url":null,"abstract":"<div><div>A functionally graded material is a class of composite materials characterized by gradual variations in composition and microstructure, which further induces the respective changes in the material properties. This study focuses on evaluating the vibration behavior of two directional functionally graded taper porous beams (FGTPB). This approach adopts a rectangular cross-section in order to deal with the challenges related to fluctuating material characteristics and geometric tapering in both thickness and width dimensions. The research employs a novel approach that merges Vogel's approximation technique with the Random Forest algorithm, an approach that has not been used in analyzing structural vibrations, establish boundary conditions and solve equations of motion. Comparative results of the suggested beam theory with the existing literature on FGTPB materials such as alumina and SUS304 at various taper, porosity, gradient and width ratios verified it. The material gradation and porosity developed a uniform pattern in the first three modes of fundamental frequencies. Higher gradient indices increased the rigidity and natural frequencies of the beams whereas the porosity index decreased the rigidity, resulting in lower natural frequencies. By combining Vogel's approximation method with machine learning techniques, the study improved vibration behavior analysis in FGTPB. The disciplines of materials and structural engineering are significantly impacted by this.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"26 ","pages":"Article e02397"},"PeriodicalIF":2.7,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142356704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
By the end of December 2023, COVID-19 had infected 701,748,397 people worldwide, killing 6,968,845 of them. A total of 1,734,021 cases and 30,162 deaths were reported in the countries of East Africa, with the highest number of cases (501,117) coming from Ethiopia and the lowest number from Eritrea (10,189). Globally, the epidemic has resulted in an astounding death toll and presents an unmatched danger to public health, the workplace, and food systems. Although most people agree that vaccination has had the biggest positive impact on global health in reduction of COVID 19, safe and effective vaccines were desperately needed to protect vulnerable populations.
Research released in English between January 1, 2021, and January 14, 2024 was thoroughly searched through PubMed, Medline, EMBASE, CINAHL, and other pertinent sources. Data extraction and quality assessment were conducted using the Newcastle-Ottawa Scale (NOS) and the Preferred Reporting Items for Systematic Review and Meta-Analyses. STATA 17MP was used for the data analysis. The I2 test statistic and Egger's test of significance were used to evaluate heterogeneity and publication bias. The odds ratio (OR) and 95 % confidence interval (CI) were displayed using forest plots. This review and meta-analysis comprised a total of 23 articles, or a total sample size of 170,853. The pooled prevalence of post-COVID-19 vaccination side effects showed that 55 % (95 %CI 40–69 %) of population in East African nations experienced at least one side effect after receiving vaccination. The pooled odds ratio showed that a significant association was found between post-COVID-19 vaccination and gender (OR = 1.70; 95 %CI: 1.26–2.14), safety concern (OR: 2.79; 95 % CI: 0.51, 5.0), age (OR = 0.97; 95 %CI: 0.95–0.98), comorbidity (OR = 2.72; 95 %CI: 1.08–4.35). This review highlighted a significant number of adverse reactions to COVID-19 vaccinations. It is crucial to begin educating the public about these vaccines to enhance their understanding that the pandemic can be managed and that side effects are rare, temporary, and reversible.
{"title":"Post COVID-19 vaccination side effects and associated factors among vaccinated clients in East Africa region: A systematic review and meta-analysis","authors":"Dagne Deresa Dinagde , Gizu Tola Feyisa , Begetayinoral Kussia Lahole , Habtamu Wana Wada , Meserat Workiye Negash , Shambel Negese Marami","doi":"10.1016/j.sciaf.2024.e02399","DOIUrl":"10.1016/j.sciaf.2024.e02399","url":null,"abstract":"<div><div>By the end of December 2023, COVID-19 had infected 701,748,397 people worldwide, killing 6,968,845 of them. A total of 1,734,021 cases and 30,162 deaths were reported in the countries of East Africa, with the highest number of cases (501,117) coming from Ethiopia and the lowest number from Eritrea (10,189). Globally, the epidemic has resulted in an astounding death toll and presents an unmatched danger to public health, the workplace, and food systems. Although most people agree that vaccination has had the biggest positive impact on global health in reduction of COVID 19, safe and effective vaccines were desperately needed to protect vulnerable populations.</div><div>Research released in English between January 1, 2021, and January 14, 2024 was thoroughly searched through PubMed, Medline, EMBASE, CINAHL, and other pertinent sources. Data extraction and quality assessment were conducted using the Newcastle-Ottawa Scale (NOS) and the Preferred Reporting Items for Systematic Review and Meta-Analyses. STATA 17MP was used for the data analysis. The <em>I</em><sup>2</sup> test statistic and Egger's test of significance were used to evaluate heterogeneity and publication bias. The odds ratio (OR) and 95 % confidence interval (CI) were displayed using forest plots. This review and meta-analysis comprised a total of 23 articles, or a total sample size of 170,853. The pooled prevalence of post-COVID-19 vaccination side effects showed that 55 % (95 %CI 40–69 %) of population in East African nations experienced at least one side effect after receiving vaccination. The pooled odds ratio showed that a significant association was found between post-COVID-19 vaccination and gender (OR = 1.70; 95 %CI: 1.26–2.14), safety concern (OR: 2.79; 95 % CI: 0.51, 5.0), age (OR = 0.97; 95 %CI: 0.95–0.98), comorbidity (OR = 2.72; 95 %CI: 1.08–4.35). This review highlighted a significant number of adverse reactions to COVID-19 vaccinations. It is crucial to begin educating the public about these vaccines to enhance their understanding that the pandemic can be managed and that side effects are rare, temporary, and reversible.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"26 ","pages":"Article e02399"},"PeriodicalIF":2.7,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142420350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-19DOI: 10.1016/j.sciaf.2024.e02401
Soukaina Ed-Dakiri, Issam Etebaai, Said El Moussaoui, Abdelhamid Tawfik, Mustapha Lamgharbaj, Hajar El Talibi, Hinde Cherkaoui Dekkaki, Morad Taher
In northern Morocco, water erosion presents a critical risk for soil degradation and dam sedimentation, attributable to extreme climatic conditions, variegated topography, lithological vulnerabilities, and anthropogenic pressures. This study quantitatively and spatially evaluates soil erosion susceptibility within the catchment area of the Oued Ghiss dam in Central Rif, Morocco. Utilizing the Revised Universal Soil Loss Equation (RUSLE) integrated with Geographic Information Systems (GIS) and calibrated through magnetic susceptibility metrics, the study provides a detailed analysis of erosion factors. The model was applied using GIS to spatially analyze data on rainfall, soil type, topography, land cover, and management practices, with magnetic susceptibility measurements used to calibrate the model by identifying stable and erosion-prone areas. The resultant soil loss map reveals a mean erosion rate of 24 t/ha/year. Specifically, 37.28 % of the catchment area exhibits an erosion rate under 5 t/ha/year, 40.16 % between 5 and 10 t/ha/year, 22.77 % between 10 and 20 t/ha/year, and 0.86 % surpasses 20 t/ha/year. Magnetic susceptibility measurements across various soil profiles indicated that stable soils showed increased susceptibility towards the surface, while eroded soils displayed decreased susceptibility, with significant correlations found between magnetic susceptibility variations and the final risk map. This innovative calibration of the RUSLE model through magnetic susceptibility improves erosion vulnerability assessments and results in a more detailed soil loss map. The findings provide critical information for policymakers to develop targeted management plans for erosion-prone areas, particularly benefiting the Ghiss dam watershed, where these insights will aid in preventing dam siltation and enhancing water resource management. This confirms magnetic susceptibility's reliability in assessing soil erosion vulnerability and improving numerical models.
{"title":"Assessing soil erosion risk through geospatial analysis and magnetic susceptibility: A study in the Oued Ghiss dam watershed, Central Rif, Morocco","authors":"Soukaina Ed-Dakiri, Issam Etebaai, Said El Moussaoui, Abdelhamid Tawfik, Mustapha Lamgharbaj, Hajar El Talibi, Hinde Cherkaoui Dekkaki, Morad Taher","doi":"10.1016/j.sciaf.2024.e02401","DOIUrl":"10.1016/j.sciaf.2024.e02401","url":null,"abstract":"<div><div>In northern Morocco, water erosion presents a critical risk for soil degradation and dam sedimentation, attributable to extreme climatic conditions, variegated topography, lithological vulnerabilities, and anthropogenic pressures. This study quantitatively and spatially evaluates soil erosion susceptibility within the catchment area of the Oued Ghiss dam in Central Rif, Morocco. Utilizing the Revised Universal Soil Loss Equation (RUSLE) integrated with Geographic Information Systems (GIS) and calibrated through magnetic susceptibility metrics, the study provides a detailed analysis of erosion factors. The model was applied using GIS to spatially analyze data on rainfall, soil type, topography, land cover, and management practices, with magnetic susceptibility measurements used to calibrate the model by identifying stable and erosion-prone areas. The resultant soil loss map reveals a mean erosion rate of 24 t/ha/year. Specifically, 37.28 % of the catchment area exhibits an erosion rate under 5 t/ha/year, 40.16 % between 5 and 10 t/ha/year, 22.77 % between 10 and 20 t/ha/year, and 0.86 % surpasses 20 t/ha/year. Magnetic susceptibility measurements across various soil profiles indicated that stable soils showed increased susceptibility towards the surface, while eroded soils displayed decreased susceptibility, with significant correlations found between magnetic susceptibility variations and the final risk map. This innovative calibration of the RUSLE model through magnetic susceptibility improves erosion vulnerability assessments and results in a more detailed soil loss map. The findings provide critical information for policymakers to develop targeted management plans for erosion-prone areas, particularly benefiting the Ghiss dam watershed, where these insights will aid in preventing dam siltation and enhancing water resource management. This confirms magnetic susceptibility's reliability in assessing soil erosion vulnerability and improving numerical models.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"26 ","pages":"Article e02401"},"PeriodicalIF":2.7,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2468227624003430/pdfft?md5=e7e2c0adfa480f7c8f7bc331328a9b75&pid=1-s2.0-S2468227624003430-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-19DOI: 10.1016/j.sciaf.2024.e02403
Raphael Shadai Oguike , Hamza Yusuf Adam
Water resources occupies vital position regarding the lifespan and general wellbeing humans while significant shortfalls on its reserves hinders almost all sustainable development globally. Most host communities to quarry companies without a water treatment plant are greatly affected by the use of water resources within its area. The present study highlights statistical evaluation and quality analysis of water resources around a quarry site in FCT Nigeria. The research engaged biological assay, physiological and chemical analysis to quantify contamination level of the water resources from obtained data which were also subjected to statistical analysis. The statistical tools employed are Pearson's Correlation, descriptive statistics, Levene's test for homogeneity and one–way analysis. The physiochemical analysis revealed the water resources to have high turbidity value in 58.3 % of sampled population while nitrate concentration and electrical conductivity value were very low. The bioassay revealed presence of coliform bacteria in 100 % of sampled population while thermotolerance count discovered disease-causing-pathogens in 41.7 % of sampled population. Chemical analysis revealed that Pb, Cr, Ni and As were 91.7 %, 83.3 % 100 % and 100 % above recommended permissible limits for sampled population. These results suggests that water resources in this study is unsafe and holds a health-treat with regards to the contaminations inherent in them. Statistical evaluation revealed average positive linear relationship between heavy metal concentration suggesting close relationship of contamination source. Observed strong positive linear relationship between lead and copper, nickel and chromium as well as nickel and arsenic in the scatterplot depicts same source of contamination.
{"title":"Statistical evaluation and quality analysis of water resources around quarry site in Abuja Suburban Nigeria","authors":"Raphael Shadai Oguike , Hamza Yusuf Adam","doi":"10.1016/j.sciaf.2024.e02403","DOIUrl":"10.1016/j.sciaf.2024.e02403","url":null,"abstract":"<div><div>Water resources occupies vital position regarding the lifespan and general wellbeing humans while significant shortfalls on its reserves hinders almost all sustainable development globally. Most host communities to quarry companies without a water treatment plant are greatly affected by the use of water resources within its area. The present study highlights statistical evaluation and quality analysis of water resources around a quarry site in FCT Nigeria. The research engaged biological assay, physiological and chemical analysis to quantify contamination level of the water resources from obtained data which were also subjected to statistical analysis. The statistical tools employed are Pearson's Correlation, descriptive statistics, Levene's test for homogeneity and one–way analysis. The physiochemical analysis revealed the water resources to have high turbidity value in 58.3 % of sampled population while nitrate concentration and electrical conductivity value were very low. The bioassay revealed presence of coliform bacteria in 100 % of sampled population while thermotolerance count discovered disease-causing-pathogens in 41.7 % of sampled population. Chemical analysis revealed that Pb, Cr, Ni and As were 91.7 %, 83.3 % 100 % and 100 % above recommended permissible limits for sampled population. These results suggests that water resources in this study is unsafe and holds a health-treat with regards to the contaminations inherent in them. Statistical evaluation revealed average positive linear relationship between heavy metal concentration suggesting close relationship of contamination source. Observed strong positive linear relationship between lead and copper, nickel and chromium as well as nickel and arsenic in the scatterplot depicts same source of contamination.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"26 ","pages":"Article e02403"},"PeriodicalIF":2.7,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142438249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-19DOI: 10.1016/j.sciaf.2024.e02374
John Kamwele Mutinda, Amos Kipkorir Langat
The non-linear and non-stationary nature of financial time series data poses significant challenges for standalone statistical and neural network methods. While predictive modeling in finance often focuses on volatility, there is a notable lack of research on predicting actual stock prices, particularly in the African market. This study addresses this gap by utilizing Airtel stock data from Yahoo Finance, spanning June 28, 2019, to May 8, 2024. The research employs the GARCH model to extract statistical properties, which are then combined with historical prices and fed into LSTM, GRU, and Transformer models leading to GARCH-LSTM, GARCH-GRU, GARCH-Transfomer hybrid models. These hybrid models are benchmarked against standalone LSTM, GRU and Transfomer models using RMSE, MAE, MAPE, and R-squared metrics. Results indicate that hybrid models, especially GARCH-LSTM, significantly outperform standalone models. This integration of GARCH with advanced AI models offers a more robust framework for stock price prediction, enhancing accuracy and reliability in forecasting future prices.
{"title":"Stock price prediction using combined GARCH-AI models","authors":"John Kamwele Mutinda, Amos Kipkorir Langat","doi":"10.1016/j.sciaf.2024.e02374","DOIUrl":"10.1016/j.sciaf.2024.e02374","url":null,"abstract":"<div><div>The non-linear and non-stationary nature of financial time series data poses significant challenges for standalone statistical and neural network methods. While predictive modeling in finance often focuses on volatility, there is a notable lack of research on predicting actual stock prices, particularly in the African market. This study addresses this gap by utilizing Airtel stock data from Yahoo Finance, spanning June 28, 2019, to May 8, 2024. The research employs the GARCH model to extract statistical properties, which are then combined with historical prices and fed into LSTM, GRU, and Transformer models leading to GARCH-LSTM, GARCH-GRU, GARCH-Transfomer hybrid models. These hybrid models are benchmarked against standalone LSTM, GRU and Transfomer models using RMSE, MAE, MAPE, and R-squared metrics. Results indicate that hybrid models, especially GARCH-LSTM, significantly outperform standalone models. This integration of GARCH with advanced AI models offers a more robust framework for stock price prediction, enhancing accuracy and reliability in forecasting future prices.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"26 ","pages":"Article e02374"},"PeriodicalIF":2.7,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142319025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-19DOI: 10.1016/j.sciaf.2024.e02404
Koupamba G. Sinasson S , Charlie M. Shackleton , Sheunesu Ruwanza , Gladman Thondhlana
Peoples’ experiences of Ecosystem Disservices (EDS) are influenced by socio-economic and environmental characteristics, and this needs better understanding for informed planning and management of urban green infrastructure. The paper investigated the understudied area of how socio-economic and environmental factors influence people's experiences of EDS in urban green spaces, in four towns in South Africa. Employing a questionnaire survey, in 303 randomly selected households in three neighborhoods of different economic standing, alongside statistical analysis provided quantitative data on experiences and vulnerability to EDS. A list of reported EDS was compiled and the number of EDS/respondent was compared between towns, neighborhoods and places of experience, using Kruskal-Wallis test and nested ANOVAs. Respondents’ vulnerability to EDS was assessed by analyzing the magnitudes of experience and coping abilities. The influences of socio-economic and environmental characteristics on experiences of and vulnerability to EDS were assessed using PCAs. Twenty-three EDS were reported in total, with the highest numbers recorded in affluent areas and the lowest in the poorest areas. Irrespective of town and neighborhood, the reported EDS were mainly experienced in domestic gardens and surrounding streets. Consequently, only one EDS seems of high concern, while the others are of lower concern or well manageable by the respondents. Significant influences of socio-economic (education and income levels, source of income, upbringing, frequency of visits to green spaces (GS), length of residence in neighborhoods) and environmental (environmental worldview, garden ownership, membership to environmental NGO) characteristics were observed on the experiences and vulnerability to EDS. Therefore, such variations in and influences on peoples’ experiences and vulnerability to EDS should be considered for sustainable management of urban GS. Also, the creation of GS should be accompanied by actions to improve people relationships to nature as well as to ensure their maintenance and security, particularly public GS and commonages.
{"title":"Contextual and socio-economic factors affected urban dwellers experiences of and vulnerability to ecosystem disservices","authors":"Koupamba G. Sinasson S , Charlie M. Shackleton , Sheunesu Ruwanza , Gladman Thondhlana","doi":"10.1016/j.sciaf.2024.e02404","DOIUrl":"10.1016/j.sciaf.2024.e02404","url":null,"abstract":"<div><div>Peoples’ experiences of Ecosystem Disservices (EDS) are influenced by socio-economic and environmental characteristics, and this needs better understanding for informed planning and management of urban green infrastructure. The paper investigated the understudied area of how socio-economic and environmental factors influence people's experiences of EDS in urban green spaces, in four towns in South Africa. Employing a questionnaire survey, in 303 randomly selected households in three neighborhoods of different economic standing, alongside statistical analysis provided quantitative data on experiences and vulnerability to EDS. A list of reported EDS was compiled and the number of EDS/respondent was compared between towns, neighborhoods and places of experience, using Kruskal-Wallis test and nested ANOVAs. Respondents’ vulnerability to EDS was assessed by analyzing the magnitudes of experience and coping abilities. The influences of socio-economic and environmental characteristics on experiences of and vulnerability to EDS were assessed using PCAs. Twenty-three EDS were reported in total, with the highest numbers recorded in affluent areas and the lowest in the poorest areas. Irrespective of town and neighborhood, the reported EDS were mainly experienced in domestic gardens and surrounding streets. Consequently, only one EDS seems of high concern, while the others are of lower concern or well manageable by the respondents. Significant influences of socio-economic (education and income levels, source of income, upbringing, frequency of visits to green spaces (GS), length of residence in neighborhoods) and environmental (environmental worldview, garden ownership, membership to environmental NGO) characteristics were observed on the experiences and vulnerability to EDS. Therefore, such variations in and influences on peoples’ experiences and vulnerability to EDS should be considered for sustainable management of urban GS. Also, the creation of GS should be accompanied by actions to improve people relationships to nature as well as to ensure their maintenance and security, particularly public GS and commonages.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"26 ","pages":"Article e02404"},"PeriodicalIF":2.7,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142319024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study examines the relationship between environmental quality and unemployment in Ghana using annual data spanning the period from 1990 to 2019. It also assesses the impact of gender-segregated unemployment rate on environmental quality. The study employed the Autoregressive Distributive Lag (ARDL) error correction model to estimate the relationship among the variables. In addition, the Fully Modified Ordinary Least Squares (FMOLS) and the Dynamic Ordinary Least Squares (DOLS) estimation procedures were employed to check for robustness of the ARDL results. Findings indicate a positive effect of total unemployment rate on environmental quality in Ghana in the long-run and also in the short-run. In the case of the gender-segregated unemployment, the findings reveal that in both short-run and long-run, a rise in female unemployment causes a deterioration in environmental quality in Ghana. The results also validated the Environmental Phillips Curve (EPC) hypothesis in the case of male unemployment. Thus, given that there is no general pattern in the findings, the study concludes that the Environmental Phillips Curve (EPC) hypothesis does not hold within the Ghanaian context.
{"title":"Does the environmental Phillips curve hypothesis hold within the Ghanaian context?","authors":"Richmond Addison , Emmanuel Akutcha , Godwin Debrah","doi":"10.1016/j.sciaf.2024.e02400","DOIUrl":"10.1016/j.sciaf.2024.e02400","url":null,"abstract":"<div><div>This study examines the relationship between environmental quality and unemployment in Ghana using annual data spanning the period from 1990 to 2019. It also assesses the impact of gender-segregated unemployment rate on environmental quality. The study employed the Autoregressive Distributive Lag (ARDL) error correction model to estimate the relationship among the variables. In addition, the Fully Modified Ordinary Least Squares (FMOLS) and the Dynamic Ordinary Least Squares (DOLS) estimation procedures were employed to check for robustness of the ARDL results. Findings indicate a positive effect of total unemployment rate on environmental quality in Ghana in the long-run and also in the short-run. In the case of the gender-segregated unemployment, the findings reveal that in both short-run and long-run, a rise in female unemployment causes a deterioration in environmental quality in Ghana. The results also validated the Environmental Phillips Curve (EPC) hypothesis in the case of male unemployment. Thus, given that there is no general pattern in the findings, the study concludes that the Environmental Phillips Curve (EPC) hypothesis does not hold within the Ghanaian context.</div></div>","PeriodicalId":21690,"journal":{"name":"Scientific African","volume":"26 ","pages":"Article e02400"},"PeriodicalIF":2.7,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142326750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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