Geochemical Characteristics of Granitoids (Ho Gneiss) from the Pan – African Dahomeyide Belt, Southeastern, Ghana: Implications for Petrogenesis and Tectonic Setting

The Pan-African Dahomeyide belt exposed in Southeastern, Ghana, consist of granitoid gneisses locally known as Ho gneiss. These rocks are thought to be part of the West African Craton (WAC) which was reworked during the Pan-African Orogeny, and may be time equivalent with the Kara gneisses. Petrographical and whole rock geochemical analyses have been used to evaluate the characteristics, petrogenesis and mode of emplacement of the granitoids. The new data reasonably suggest that the Ho gneiss consist mainly of biotite augen gneisses of both mafic and felsic rock suites. Geochemically, these rocks show tonalitic to quartz monzonite but mainly granodiorites affinities. They are metaluminous to weakly peraluminous, I-type, magnesian to ferroan and calcic to alkali calcic. With these varying features, the granitoids mimic mantle derived magma source which mixed or mingled with crustally derived melt. The rocks display varying REEs and trace elements patterns but, their LREEs and LILE enrichment with  the noticeable enrichment in Rb, Ba, K and especially Pb and negative Ti, Ta, Nb observed among majority of the samples are typical signature of ‘‘arc rocks’’ or continental crustal materials. Their incompatible trace element ratios, such as Th/U (1.07 – 13.87), K/Rb (272 – 574.47), Th/Yb (0.79 – 15.09), Ta/Yb (0.25 -0.64 ), Ce/Pb (mainly 1.62 – 7.88 ) and high Ba/Nb (19.55 – 314.17, with TA = 1565.00), are similar to those of the continental crust. The rocks are characterised by subduction related Sr/Y content (< 100), except sample MA8 that shows high concentration of Sr/Y (227.71). The magnesian affinity reflects relatively hydrous, oxidizing source which is consistent with origins that are broadly subduction related. Their high – K nature also points to an important petrogenetic role of remelting and differentiation of arc – accretionary complex crust. These geochemical signatures are likely to be related to metasomatism of the sub – continental lithospheric mantle via crustal recycling. In conclusion, the granitoids may have from melting of igneous source in a subduction related environment. Keywords: Pan-African belt, Dahomeyide, Southeastern Ghana, Ho gneisses, Geochemistry, petrogenesi

Malaria elimination in Ghana:recommendations for reactive case detection strategy implementation in a low endemic area of Asutsuare, Ghana

Background: Progress toward malaria elimination is increasing as many countries near zero indigenous malaria cases. In settings nearing elimination, interventions will be most effective at interrupting transmission when targeted at the residual foci of transmission. These foci may be missed due to asymptomatic infections. To solve this problem, the World Health Organization recommends reactive case detection (RACD). This case study was conducted to identify individuals with asymptomatic malaria, their predisposing risk factors and recommend RACD in Asutsuare, Ghana based on literature review and a cross sectional study. Methods: The study involved a search on PubMed and Google Scholar of literature published between 1st January, 2009–14th August, 2023 using the search terms “malaria” in “Asutsuare”. Furthermore, structured questionnaires were administered to one hundred individuals without symptoms of malaria and screened using rapid diagnostic test (RDT) kits, microscopy and real-time polymerase chain reaction (rt-PCR). Malaria prevalence based on the three diagnostic techniques as well as potential malaria risk factors were assessed through questionnaires in a cross-sectional study. Results: Cumulatively, sixty-four (64) studies (Google Scholar, 57 and PubMed, 7) were reviewed and 22 studies included in the literature on malaria in Asutsuare, Ghana. Significant risk factors were occupation, distance from a house to a waterbody, age group and educational level. Out of the 100 samples, 3 (3%) were positive by RDT, 6 (6%) by microscopy and 9 (9%) by rt-PCR. Ages 5–14.9 years had the highest mean malaria parasite densities of 560 parasites/µl with Plasmodium falciparum as the dominant species in 4 participants. Moreover, in the age group ≥ 15, 2 participants (1 each) harboured P. falciparum and Plasmodium malariae parasites. RDT had a higher sensitivity (76.54%; CI95 66.82–85.54) than rt-PCR (33.33%; CI95 4.33–77.72), while both rt-PCR and RDT were observed to have a higher specificity (92.55; CI95 85.26–96.95) and (97.30; CI95 93.87–99.13), respectively in the diagnosis of malaria. Conclusion: In Asutsuare, Ghana, a low endemic area, the elimination of malaria may require finding individuals with asymptomatic infections. Given the low prevalence of asymptomatic individuals identified in this study and as repleted in the literature review, which favours RACD, Asutsuare is a possible setting receptive for RACD implementation.</p

A Proposed Methodology for Modelling the Solvency of a National Pension Scheme

The main aim of this study is to fit a model for predicting pension liability. The study proposed a stochastic population model to determine the status of a pension scheme. By categorizing the members of the Social Security and National Insurance Trust (SSNIT) pension scheme of Ghana into five groups, the birth and death process with emigration and the pure death process coupled with assumption of the Yule’s process, were combined to successfully formulate a model for forecasting the surplus of SSNIT to be used as a proxy for assessing the solvency status of the scheme. The reliability of the proposed model was corroborated by very high coverage probabilities of the estimates of expected surpluses produced.&nbsp; The study demonstrated how easy it is to use the proposed model to carry out sensitivity analysis which allows the exploration of various scenarios leading to formulation and implementation of policies to enhance the solvency of the scheme. One major advantage of the proposed model is that, it uses more information (variables) compared to others proposed elsewhere for the same purpose. This contributes to the precision of estimates from the model. A key finding of the study is that SSNIT would have still been solvent had she increased pension by 50%. &nbsp

Comparative analysis of stochastic seasonality, January effect and market efficiency between emerging and industrialized markets

This study investigates whether there are significant differences in investment returns between emerging markets and industrialized markets in terms of stochastic seasonality, January effect and market efficiency. Data on investments, and returns for nine emerging countries and eleven industrialized countries spanning January 1990 to December 2020, were obtained from the Organization for Economic Cooperation and Development (OECD). The spectral nonparametric test was used to determine the presence of stochastic seasonality for each market while the regression test was used to determine the presence of January effect. In the case of determining the efficiency status of the markets, the variance ratio test and the runs test were used. In cases where there appeared to be differences between the two types of market, Fisher's exact test was used to verify such differences. The results show no significant differences between the two types of markets in terms of seasonality, January effect and efficiency statuses. Apart from Brazil which recorded stochastic seasonality, all others are not stochastically seasonal. In the case of the January effect, it was a mixed bag; five emerging markets had January effect while two industrialized markets had January effect

Analysis of Investment Returns as Markov Chain Random Walk

The main objective of this paper is to analyse investment returns using a stochastic model and inform investors about the best stock market to invest in. To this effect, a Markov chain random walk model was successfully developed and implemented on 450 monthly market returns data spanning from January 1976 to December 2020 for Canada, India, Mexico, South Africa, and Switzerland obtained from the Federal Reserves of the Bank of St. Louis. The limiting state probabilities and six-month moving crush probabilities were estimated for each country, and these were used to assess the performance of the markets. The Mexican market was observed to have the least probabilities for all the negative states, while the Indian market recorded the largest limiting probabilities. In the case of positive states, the Mexican market recorded the highest limiting probabilities, while the Indian market recorded the lowest limiting probabilities. The results showed that the Mexican market performed better than the others over the study period, whilst India performed poorly. These findings provide crucial information for market regulators and investors in setting regulations and decision-making in investment