This study presents a comparative analysis of two image enhancement techniques, Continuous Wavelet Transform (CWT) and Fast Fourier Transform (FFT), in the context of improving the clarity of high-quality 3D seismic d...This study presents a comparative analysis of two image enhancement techniques, Continuous Wavelet Transform (CWT) and Fast Fourier Transform (FFT), in the context of improving the clarity of high-quality 3D seismic data obtained from the Tano Basin in West Africa, Ghana. The research focuses on a comparative analysis of image clarity in seismic attribute analysis to facilitate the identification of reservoir features within the subsurface structures. The findings of the study indicate that CWT has a significant advantage over FFT in terms of image quality and identifying subsurface structures. The results demonstrate the superior performance of CWT in providing a better representation, making it more effective for seismic attribute analysis. The study highlights the importance of choosing the appropriate image enhancement technique based on the specific application needs and the broader context of the study. While CWT provides high-quality images and superior performance in identifying subsurface structures, the selection between these methods should be made judiciously, taking into account the objectives of the study and the characteristics of the signals being analyzed. The research provides valuable insights into the decision-making process for selecting image enhancement techniques in seismic data analysis, helping researchers and practitioners make informed choices that cater to the unique requirements of their studies. Ultimately, this study contributes to the advancement of the field of subsurface imaging and geological feature identification.展开更多
This study examines the turbidite dynamics and hydrocarbon reservoir formation in Ghana’s Tano Basin, which is located in coastal West Africa. Through an exploration of geological processes spanning millions of years...This study examines the turbidite dynamics and hydrocarbon reservoir formation in Ghana’s Tano Basin, which is located in coastal West Africa. Through an exploration of geological processes spanning millions of years, we uncover key factors shaping hydrocarbon accumulation, including source rock richness, temperature, pressure, and geological structures. The research offers valuable insights applicable to exploration, management, and sustainable resource exploitation in coastal West Africa. It facilitates the identification of exploration targets with higher hydrocarbon potential, enables the anticipation of reservoir potential within the Tano Basin, and assists in tailoring exploration and management strategies to specific geological conditions of the Tano Basin. Analysis of fluvial channels sheds light on their impact on landscape formation and hydrocarbon exploration. The investigation into turbidite systems unveils intricate interactions involving tectonics, sea-level fluctuations, and sedimentation patterns, influencing the development of reservoirs. An understanding of sediment transport and depositional settings is essential for efficient reservoir management. Geomorphological features, such as channels, submarine canyons, and distinct channel types, are essential in this situation. A detailed examination of turbidite channel structures, encompassing canyons, channel complexes, convex channels, and U-shaped channels, provides valuable insights and aids in identifying exploration targets like basal lag, channel levees, and lobes. These findings underscore the enduring significance of turbidite systems as conduits for sediment transport, contributing to enhanced reservoir management and efficient hydrocarbon production. The study also highlights how important it is to examine the configuration of sedimentary layers, stacking patterns, and angular laminated facies to identify turbidites, understand reservoir distribution, and improve well design. The dynamic nature of turbidite systems, influenced by basin characteristics such as shape and slope, is highlighted. The research provides valuable insights essential for successful hydrocarbon exploration, reservoir management, and sustainable resource exploitation in coastal West Africa.展开更多
Cracks resulting from cyclic wetting and drying of expansive soils create discontinuities and anisotropy in the soil.The representative elementary volume(REV)defined by the continuous-media theory cannot be applied to...Cracks resulting from cyclic wetting and drying of expansive soils create discontinuities and anisotropy in the soil.The representative elementary volume(REV)defined by the continuous-media theory cannot be applied to cracked expansive soils that are considered discontinuous media.In this study,direct shear tests of three different scales(30 cm^(2),900 cm^(2),1963 cm^(2))and crack image analysis were carried out on undisturbed soil samples subjected to drying-wetting cycles in-situ.The REV size of expansive soil was investigated using the crack intensity factor(CIF)and soil cohesion.The results show that soil cohesion decreased with increasing sample area,and the development of secondary cracks further exacerbated the size effect of sample on cohesion of the soil.As shrinkage cracks developed,the REV size of the soil gradually increased and plateaued after 3−5 cycles.Under the same drying-wetting cycle conditions,the REV size determined using soil cohesion(REV-C)is 1.75 to 2.97 times the REV size determined using CIF(REV-CIF).Under the influence of shrinkage cracks,the average CIF is positively correlated with the REV size determined using different maximum permissible errors,with the coefficient of correlation greater than 0.9.A method for determining the REV-C based on crack image analysis is proposed,and the REV-C of expansive soil in the study area under different exposure times is given.展开更多
Health and Safety issues in the construction industry are of much concern to stakeholders, particularly because of their impact on the industry. This paper explored the roles and responsibilities of stakeholders in en...Health and Safety issues in the construction industry are of much concern to stakeholders, particularly because of their impact on the industry. This paper explored the roles and responsibilities of stakeholders in ensuring health and safety at the construction site. A well-structured interview guide was adopted for the qualitative study. Content analysis was adopted for the analysis of the results. The study revealed that the twelve roles identified by the stakeholders are only limited to the few laws and regulations they are aware of. Whereas the Contractors identified provision of welfare facilities, provision of health and safety policy, and health and safety plan as their key roles, the Consultants’ role was mainly limited to provision of competent site agent and provision of site layout. Abiding by the contractors’ instruction was identified by the Construction Workers as their key responsibilities. The local government officials also identified enforcement of CHS laws and regulations and reporting of incidents to the appropriate authorities, whereas the traditional authorities identified the enforcement of CHS laws and regulations including bye laws and enforcement of customs as their key roles. The findings further show that the stakeholders failed to appreciate some key roles and responsibilities enshrined in CHS laws and regulations in Ghana. The findings contribute to knowledge on stakeholders’ responsibilities in ensuring CHS, and provide valuable reference and insight to practitioners on the roles and responsibilities of the various stakeholders. It is recommended to train and educate stakeholders on all the relevant laws and regulations on CHS in order to improve health and safety at the construction site. The government should also set up a body such as Construction Authority to educate, coordinate, monitor and audit the activities of stakeholders to improve CHS at construction sites.展开更多
Although Ghana produces natural gas and has several gas reserves, the country still depends on supplies from neighbouring countries for power generation due to challenges like fuel suppl</span><span style=&qu...Although Ghana produces natural gas and has several gas reserves, the country still depends on supplies from neighbouring countries for power generation due to challenges like fuel suppl</span><span style="font-family:Verdana;">y</span><span style="font-family:Verdana;"> inefficiencies and increasing cost of gas production. Gas supply is thus a limiting factor for power generation. This study explores strategies to improve gas supplies for sustainable power generation in Ghana. The study examined the underlying factors inhibiting gas supplies in Ghana, investigated the risks in the gas supply industry, and explored strategies for improving gas supplies in Ghana. The study adopted an inductive approach that utilises both qualitative and quantitative research methods. With the use of questionnaires, data were collected from 151 respondents who were selected by purposive and snowball sampling procedures. The collected data were descriptively and inferentially analysed with analytical tools in the SPSS. The study</span><span style="font-family:Verdana;">’</span><span style="font-family:Verdana;">s findings conclude that factors that inhibit gas supply in Ghana include the lack of growth and supply investment in the gas supply industry, power sector debt on the gas market, and the lack of an extensive distribution infrastructure/network. Also, the gas industry in Ghana lacks the requisite investment drive which culminates into inefficiency and ultimately undermines efforts to achieve sustainable power generation. Politics influence in issues relating to gas supplies in Ghana inhibits long-term supply relationships and permanent infrastructure in gas supply, both locally and on the world market.展开更多
Biomass production and nutrient （N, P, K, Ca and Mg） accumulation, distribution and cycling were quantified in young, mature and over-mature （10-, 22-, and 34-year old） Chinese fir [Cunninghamia lanceolate （Lamb....Biomass production and nutrient （N, P, K, Ca and Mg） accumulation, distribution and cycling were quantified in young, mature and over-mature （10-, 22-, and 34-year old） Chinese fir [Cunninghamia lanceolate （Lamb.） Hook] plantations in southern China. Total stand biomass of young, mature and over-mature stands was 38, 104 and 138 t ha-1 respectively. Biomass production increased significantly with age. Stem wood represented the highest percentage of stand biomass, accounting for 41, 55 and 63 % in the young, mature and over-mature plan- tations respectively. Nutrients concentration was highest in live needles and branches, and lowest in stem wood. The plantations accumulated more N, followed by K, Ca, Mg, and P. Nutrient return amount, nutrient utilization effi- ciency, nutrient turnover time, the ratio of nutrient return and uptake increased with stand age, which implies that young Chinese fir deplete soil nutrients to maintain growth, and efficiently utilize nutrients to decrease dependence on soil nutrients as they age. Harvesting young Chinese fir plantations would therefore lead to high nutrient loss, but prolonging the rotation length could improve soil recovery, and help sustain productivity in the long-term. Improved nutrient return through litterfall as stands get older may also be beneficial to nutrient pool recovery.展开更多
Negative Pressure pulmonary oedema (NPPO) is a medical emergency. It occurs when there is a strong inspiratory effort in obstructed upper airway. Laryngospasm is the main cause of postextubation negative pressure pulm...Negative Pressure pulmonary oedema (NPPO) is a medical emergency. It occurs when there is a strong inspiratory effort in obstructed upper airway. Laryngospasm is the main cause of postextubation negative pressure pulmonary oedema. Though it is life-threatening, early diagnosis and prompt treatment lead to rapid resolution with no residual respiratory complications. The mainstay management is to provide respiratory support, mostly in the intensive care unit. The recommended mode of respiratory support is to provide an invasive or non-invasive positive airway pressure. This requires the use of a ventilator. Most surgery centres in sub-Saharan Africa do not have intensive care unit or ventilators in their recovery wards. We report two cases of postextubation NPPO which occurred in a typical African hospital with no ventilator. All these two cases were successfully managed with a non-rebreather mask. The periods of resolution, both clinical and radiological, were 24 - 48 hrs. This is not significantly different from the resolution periods quoted in literature from cases managed in well-resourced centres with means of positive pressure ventilation. We therefore conclude that early detection and prompt initiation of management are important keys which can lead to good outcomes, even in low-resource centres.展开更多
The objective of this work was to determine the effect of transport time （up to 11 hours） on animal welfare. 540 animals （cows, bulls and calves）, three transport times of 2, 4 to 6, and 10 to 11 hours, and two sp...The objective of this work was to determine the effect of transport time （up to 11 hours） on animal welfare. 540 animals （cows, bulls and calves）, three transport times of 2, 4 to 6, and 10 to 11 hours, and two space allowances （2 m2 and 1.5 m2 per animal for cows and bulls; and 1.2 m2 and 0.8 m2 per animal for calves） were used for the experiment during transport from farms to the abattoir in Uppsala, Sweden. Measurements were made on five animals on each trip. Stress response parameters considered were cortisol, glucose, lactate, creatine kinase and heart rate. Blood samples were taken before and after transport. Heart rate sensors were mounted on the animals at least 30 minutes before loading and measurements were made continuously from farms to the abattoirs until stunning. The results of heart rate measurement indicated that loading, un-loading and forced movement in the stunning box were the most stressful events. However, the results of statistical analysis confirmed that transport time doesn＇t have significant effect （P 〈 0.05） on heart rate. Concentration level of cortisol increased by 10 folds during short transport. However, cortisol concentration decreased with an increase of transport times （P 〈 0.01）. Glucose concentrations increased with transport time in all animal categories （P ≤ 0.01）. Transport time has significant effect on concentration levels of glucose （P ≤ 0.01）, creatine kinase （P 〈 0.001） and lactate （P 〈 0.01） particularly after 6 hours journey time.展开更多
Allanblackia parviflora A. Chev. also called vegetable tallow tree provides a variety of non-timber forest products of great importance to rural households including shade, timber, medicine and seed oil but attempts h...Allanblackia parviflora A. Chev. also called vegetable tallow tree provides a variety of non-timber forest products of great importance to rural households including shade, timber, medicine and seed oil but attempts have not been made to improve the tree species and increase its production. Consequently, the species is being threatened due to unsustainable exploitation and poor regeneration and cultivation appears as the only viable option. In order to cultivate the species at meaningful scale, it is necessary to establish the optimum range of environmental factors that influence its propagation and growth. This study was therefore designed to investigate Allanblackia growth parameters and bio-accumulation under different growth media in a greenhouse study. The media were: 1) TS = top soil alone, 2) AB soil = Allanblackia soil alone, 3) TS + H = Top soil alone + humus, 4) AB + TS = Allanblackia soil alone + Top soil alone and 5) SAB = Sterilized Allanblackia soil alone. Each treatment was replicated three times in a complete randomized design. The experiment lasted for 18 months. Results showed that Fe was the micronutrient that accumulated greatest in the plant tissue. Among the treatments, Allanblackia soil showed the highest accumulation of Zn in the plant tissue with the top soil showing the least (7.67 mg·kg<sup>-l</sup>). Humus contributed largely to the bio-accumulation of Cu in the plant tissue. Bio-accumulation of manganese in the plant tissue ranged from 13.30 mg·kg<sup>-l</sup> to 207 mg·kg<sup>-l</sup> suggesting difference in manganese absorption by Allanblackia as influenced by the treatments. The growth parameters of Allanblackia parviflory were impacted differently by the growth media. The result was however controversial since no differences were found between growth of seedlings in sterilized Allanblackia soil and Allanblackia soil.展开更多
This study utilizes multiple regression analysis and the technique for computing economies of scale to evaluate the dynamics of NRW in the AER of GWCL. Data on monthly total production, billed consumption, total reven...This study utilizes multiple regression analysis and the technique for computing economies of scale to evaluate the dynamics of NRW in the AER of GWCL. Data on monthly total production, billed consumption, total revenue, total production cost and the volume of NRW spanning the period January 2015 to June 2019, was obtained from the headquarters of AER and used for the analysis. The study showed that NRW averaged 59.3% for the period under consideration, which far exceeds the 25% threshold set by the World Bank for developing economies. It was also established that a fairly inelastic relationship exists between NRW and total revenue. Results further show that resources are not optimally used in the AER as proof of diseconomies of scale was observed.展开更多
The enormity of the problem of construction accidents and hazards in the Ghanaian construction industry (GCI) calls for the need to engage in relevant research to equip stakeholders with the required knowledge to impr...The enormity of the problem of construction accidents and hazards in the Ghanaian construction industry (GCI) calls for the need to engage in relevant research to equip stakeholders with the required knowledge to improve construction health and safety (CHS) and reduce site accidents and hazards. The complexity of the problem of accident causation explains a large number of conceptual models developed to aid the understanding of the dynamics involved in CHS. This paper involved a qualitative study to identify causes of accidents and hazards in the GCI and underlying issues requiring remedying and also a desk study to review Health and Safety related theories and concepts from extant literature to explain and contribute to the improvement of CHS. The paper contributes to the use of theories to advance studies on improving health and safety at construction sites, especially in developing countries like Ghana, where such studies have so far attracted little attention. The framework may enable construction stakeholders to easily identify problem areas on site and apply required improvement measures to create a healthier and safer construction site. The findings may provide useful knowledge to improve CHS and reduce site accidents and hazards, and also provide a multi-theory approach for understanding the dynamics of the complexity of the problems involved in CHS.展开更多
Coconut (Cocos nucifera L.) is an important oilseed and a multipurpose perennial plantation crop. It is mostly grown in humid and coastal areas of Ghana. In June 2019, leaf spot disease was observed on coconut seedlin...Coconut (Cocos nucifera L.) is an important oilseed and a multipurpose perennial plantation crop. It is mostly grown in humid and coastal areas of Ghana. In June 2019, leaf spot disease was observed on coconut seedlings in 10 coconut growing Districts in Ghana. The Initial symptoms appeared as elliptical, brown-dark-red lesions, 4 - 6 mm on affected leaves. Lesions reached 2.0 cm and gradually developed into spindly, dark brown spots with a light tan centre. A study including survey and laboratory work was carried out to assess disease prevalence and to identify the causal agent of the disease on coconut seedlings, in order to formulate effective management strategies against it. A total of 250 symptomatic leaves were picked from ten selected Districts for laboratory analysis. Additionally, the ribosomal internal transcribed spacer (ITS) region and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) of the isolated pathogen were amplified using ITS1 and ITS4, gpd1 and gpd2 primers respectively. The disease incidence peaked at 95%. Fungal colonies on PDA grew to 50 - 70 mm in diameter in one week at a temperature of 28°C ± 1°C with an even to undulating, immersed striated, mycelium;aerial mycelium being dark velvety green and sometime woolly-cottony. Acervuli formed on the aerial mycelium and contained black powderish conidial masses. Hyphae characteristics were similar to that of Curvularia pseudobrachyspora. Pathogenicity tests were done following Koch’s postulate. For molecular confirmation, the combined ITS (MT075719) and GAPDH (MT075720) sequences were compared with published sequences of 52 Curvularia isolates and eight Bipolaris isolates using phylogenetic analysis. This is the first report of C. pseudobrachyspora as a causal agent of leaf spot on coconut seedlings in Ghana and possibly Africa but the pathogen has been reported on other crops in China, Florida and India.展开更多
This paper explored stakeholders’ compliance with existing laws and regulations related to construction health and safety (CHS) in the Ghanaian construction industry (GCI). Qualitative research approach was adopted f...This paper explored stakeholders’ compliance with existing laws and regulations related to construction health and safety (CHS) in the Ghanaian construction industry (GCI). Qualitative research approach was adopted for the data collection, using semi-structured interview guide. An in-depth face-to-face interview based on the grounded theory approach was conducted with actors who play important roles in ensuring health and safety at the construction site as well as key officers and professionals who are the major stakeholders in the GCI. Content analysis was adopted for the analysis of the qualitative data. The findings of the study show customary laws, bye laws, Labour Act, 2003 (Act 651), Local Governance Act, 2016 (Act 936) and the contract document as the key existing CHS related laws and regulations that the stakeholders comply with. The stakeholders also identified the following construction health and safety related regulations in the GCI which have low compliance rate: Factories, Shops and Offices Act, 1974 (Act 323), Environmental Protection Act, 1994 (Act 490), among others. The findings of the research contribute to knowledge of stakeholders’ compliance with existing laws and regulations related to CHS, and underscore the need to ensure monitoring and enforce compliance in the GCI. The findings further identify areas for stakeholders to focus attention on ensuring good health and safety practices, and also expose critical training and education needs for stakeholders in the GCI. The findings provide valuable insights on stakeholders’ compliance with laws and regulations related to CHS in Ghana, which may be applicable to other developing countries with similar construction industry.展开更多
Background: Modelling aboveground biomass(AGB) in forest and woodland ecosystems is critical for accurate estimation of carbon stocks. However, scarcity of allometric models for predicting AGB remains an issue that ha...Background: Modelling aboveground biomass(AGB) in forest and woodland ecosystems is critical for accurate estimation of carbon stocks. However, scarcity of allometric models for predicting AGB remains an issue that has not been adequately addressed in Africa. In particular, locally developed models for estimating AGB in the tropical woodlands of Ghana have received little attention. In the absence of locally developed allometric models, Ghana will continue to use Tier 1 biomass data through the application of pantropic models. Without local allometric models it is not certain how Ghana would achieve Tier 2 and 3 levels under the United Nations programme for reducing emissions from deforestation and forest degradation. The objective of this study is to develop a mixedspecies allometric model for use in estimating AGB for the tropical woodlands in Ghana. Destructive sampling was carried out on 745 trees(as part of charcoal production) for the development of allometric equations. Diameter at breast height(dbh, i.e. 1.3 m above ground level), total tree height(H) and wood density(ρ) were used as predictors for the models. Seven models were compared and the best model selected based on model efficiency,bias(%) and corrected Akaike Information Criterion. The best model was validated by comparing its results with those of the pantropic model developed by Chave et al.(Glob Chang Biol 20:3177–3190, 2014) using equivalence test and conventional paired t-test.Results: The results revealed that the best model for estimating AGB in the tropical woodlands is AGB =0.0580ρ((dbh)2 H)0.999. The equivalence test showed that this model and the pantropic model developed by Chave et al.(Glob Chang Biol 20:3177–3190, 2014) were equivalent within ±10% of their mean predictions(p-values <0.0001 for one-tailed t-tests for both lower and upper bounds at 5% significant level), while the paired t-test revealed that the mean(181.44 ± 18.25 kg) of the model predictions of the best model of this study was significantly(n = 745, mean diff. = 16.50 ± 2.45 kg;S.E. = 1.25 kg;p < 0.001) greater than that(164.94 ± 15.82 kg) of the pantropic model of Chave et al.(Glob Chang Biol 20:3177–3190, 2014).Conclusion: The model developed in this study fills a critical gap in estimating AGB in tropical woodlands in Ghana and other West African countries with similar ecological conditions. Despite the equivalence with the pantropic model it remains superior to the model of Chave et al.(Glob Chang Biol 20:3177–3190, 2014) for the estimation of AGB in local tropical woodlands. It is a relevant tool for the attainment of Tier 2 and 3 levels for REDD+. The model is recommended for use in the tropical woodlands in Ghana and other West African countries in place of the use of pantropic models.展开更多
The performance of solar PV modules is significantly affected by temperature. This paper focuses on the determination of the effect of temperature on a commercial mono-crystalline silicon PV module whose temperature c...The performance of solar PV modules is significantly affected by temperature. This paper focuses on the determination of the effect of temperature on a commercial mono-crystalline silicon PV module whose temperature coefficients were not provided by the manufacturer for installation in Kumasi, <span style="font-family:Verdana;">Ghana,</span><span style="font-family:Verdana;"> Sub-Saharan Africa (SSA) ambient. In order to determine the effect of temperature on the output characteristics of the module, the temperature coefficients of current, voltage and power were determined. First of all, the module was cooled to a temperature between 10</span><span style="font-family:Verdana;">°</span><span style="font-family:Verdana;">C</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">-</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">15</span><span style="font-family:Verdana;">°</span><span style="font-family:Verdana;">C</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> in a cooling chamber, covered with cardboard paper before the outdoor electrical tests using Daystar I-V Curve tracer. The results show that as temperature increases, irradiance decreases significantly leading to a decrease in output power (<i></i></span><i><i><span style="font-family:Verdana;">P</span></i></i></span><span style="font-family:Verdana;"><sub>max</sub></span><span style="font-family:;" "=""><span style="font-family:Verdana;">). The open circuit voltage (<i></i></span><i><i><span style="font-family:Verdana;">V<sub>oc</sub></span></i><span style="font-family:Verdana;"></span></i>) also decreases, whilst short circuit current (<i></i></span><i><i><span style="font-family:Verdana;">I<sub>sc</sub></span></i><span style="font-family:Verdana;"></span></i>) increases slightly. The temperature coefficients were obtained from the slopes of the plots of temperature against <i><i><span style="font-family:Verdana;">P</span></i></i><span style="font-family:;" "=""><span style="font-family:Verdana;"><sub>max</sub>, <i></i></span><i><i><span style="font-family:Verdana;">I<sub>sc</sub></span></i><span style="font-family:Verdana;"></span></i></span><i> </i><span style="font-family:Verdana;">and <i></i></span><i><i><span style="font-family:Verdana;">V<sub>oc</sub></span></i><span style="font-family:Verdana;"></span></i>. The slopes were used to determine how the respective output characteristics are affected as the module’s temperature rises. The temperature coefficients for power, voltage and current were obtained from the slopes of the graphs using the IVPC software and found to be <span style="font-family:Verdana;"><span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span></span></span><span style="font-family:Verdana;">0.313 W/°</span><span style="font-family:Verdana;">C</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;"><span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span></span></span><span style="font-family:Verdana;">0.11 V/<span style="white-space:nowrap;">°</span></span><span style="font-family:Verdana;">C</span><span style="font-family:Verdana;"> and 0.00</span><span style="font-family:Verdana;">4 A/°</span><span style="font-family:Verdana;">C</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> respectively. The results indicate that output power is a decreasing function of temperature (that is power decreases when temperature increases). This information will be useful to system developers, manufacturer</span><span style="font-family:Verdana;">s and investors seeking to procure PV modules for installation in Kumasi, Ghana. The temperature coefficients of commercial PV modules could be independently</span><span style="font-family:Verdana;"> verified using the technique employed in this study. Future work will focus on the long-term effect of temperature on the electrical performance characteristics.</span></span>展开更多
We studied the impacts of liana cutting as a forest management tool on liana diversity （species richness, Shannon diversity index） and community structure （diam- eter distribution, basal area, species dominance） i...We studied the impacts of liana cutting as a forest management tool on liana diversity （species richness, Shannon diversity index） and community structure （diam- eter distribution, basal area, species dominance） in the Asenanyo Forest Reserve, Ghana. Two types of silvicul- turally treated forests were studied： Logging treated （LT） and Tropical Shelterwood System （TSS） treated forests. An untreated primary forest was included as a control, result- ing in three forest management systems. Lianas with diameter 〉2 cm were identified in ten 40 × 40 m2 plots within each management system. Liana cutting signifi- cantly reduced liana species richness, Shannon diversity index, and basal area in the LT forest after two decades. However, liana species richness and basal area werecomparable in the TSS treated and untreated forests, indi- cating significant recovery in the former after over six decades. Sφrensen similarity index of liana species com- position between the untreated forest and each of the treated forests was moderate. Our findings suggest that liana cutting most likely influenced the dominance of some liana species. In view of the adverse impact of blanket liana cutting on liana diversity, selective liana cutting is rec- ommended as a means of controlling liana numbers while maintaining liana diversity.展开更多
Communication networks have undergone rapid developments in the past few decades in many Sub-Saharan African countries. The increasing number of subscribers and demand for greater variety of services in these countrie...Communication networks have undergone rapid developments in the past few decades in many Sub-Saharan African countries. The increasing number of subscribers and demand for greater variety of services in these countries make it difficult for network operators to provide the service varieties subscribers want while maintaining acceptable levels of quality of service. This paper analyzes the radio network of cellular networks in terms of traffic distribution over the existing number of communication channels using MATLAB/Simulink. A scale-free user network, which takes into account user behavior in a realistic physical network, has been used to model a more realistic cause for call blockings in a typical cellular network deployment under a Sub-Saharan environment. Peak recorded traffic distribution was observed to have overwhelmed the existing number of channels provided by the network operators for some cells eventually leading to increase in call drop rates. This high call blocking probability was attributed to poor network monitoring by the network operators to match the ever changing traffic intensities.展开更多
A comparative study was carried out to determine the most suitable substrate for breeding of midges (Forcipomyia spp.) and the implications for pollination and yield in a typical cocoa production system in the forest ...A comparative study was carried out to determine the most suitable substrate for breeding of midges (Forcipomyia spp.) and the implications for pollination and yield in a typical cocoa production system in the forest ecological zone of Ghana. For the field experiment, the typically available substrates in cocoa farms which were used as the treatments under cocoa trees were: 1) rotten cocoa leaf litter;2) rotten cocoa pod husks;and 3) rotten banana pseudostem. The untreated cocoa trees served as control. The experiment was set up in a randomized complete block design with three replications. For the laboratory experiment, the design was completely randomized design with four replications. The objective was to determine which substrate best supported breeding of the midges. The rotten banana pseudostem substrate recorded the highest population (7680) of Forcipomyia spp. after 56 days of observation. The cocoa pod husk and cocoa leaf litter recorded populations of 5226 and 1920, respectively. Similar observations were recorded in the level of pollination of the cocoa trees treated with rotten banana pseudostem (95.78%), cocoa pod husks (89.05%) and cocoa leaf litter (68.42%). Application of all substrates to the cocoa tree resulted in a 77% mean reduction in flower abortion as compared to the control. Fruit abortion, on the other hand, was significantly greater in trees treated with rotten banana pseudostem (73.7%) and rotten cocoa pod husks (71.3%) than in trees treated with rotten cocoa leaf litter (54.3%). Application of banana substrate explained 88% of the variation in cherelle production (fruit set) whereas cocoa pod husks and cocoa leaf litter accounted for 71% and 94%, respectively, of the variation in cherelle production. The study concluded that although cocoa leaf litter resulted in average increases in midges population and subsequently not too high levels of pollination, there was a significantly higher number of set fruits retained which implied high cocoa pod yields. Consequently, in accordance with the observed trend cocoa leaf litter should be considered as the most appropriate substrate for midges activity in cocoa for high yields.展开更多
Human orofacial clefts (OFCs) are congenital anomalies that result from the breakdown of normal mechanisms that regulate the formation of the human face. They could be syndromic or non-syndromic, with a global inciden...Human orofacial clefts (OFCs) are congenital anomalies that result from the breakdown of normal mechanisms that regulate the formation of the human face. They could be syndromic or non-syndromic, with a global incidence of 1:700 per live births. Environmental and genetic factors are thought to play various roles in the aetiology of OFCs. This study seeks to establish the diversity, distribution and pattern of inheritance of OFCs as well as environmental and other risk factors associated with OFCs in a Ghanaian population. A family-based, descriptive cross-sectional study that employed an interview-based survey questionnaire was used to obtain information from 467 families with history of OFCs. We employed chi-square statistics to analyse the data and used graphs to interpret the data. All previously reported subphenotypes of OFCs were observed by the present study. Clinically, about 12% of clefts in the study population were syndromic. The most common syndromic forms observed were Pierre Robin Sequence, cleft-with-club foot abnormalities and Van der Woude Syndrome. Only about 5% of clefts in the study cohort were familial. The study also established that lower level of education of parents, poverty, late antenatal care and dietary folate deficiency are major environmental factors associated with clefts in the Ghanaian population. In conclusion, OFCs are non-randomly distributed in Ghana and folate deficiency could likely be a source of genetic mutations and “epimutations” that cause OFCs, since folate is essential for DNA methylation, replication and repair as well as histone modification.展开更多
This paper studies the history of circumcision amongst religious and traditional societies and the arguments on the medical or non-medical essence of the practice. The paper further highlights amongst the Asante peopl...This paper studies the history of circumcision amongst religious and traditional societies and the arguments on the medical or non-medical essence of the practice. The paper further highlights amongst the Asante people of Ghana, a practice argued to have been introduced by Islamic Wanzams who are severally referred to as Muslim Circumcision Surgeons. Often circumcision amongst communities in West, Southern Africa, Asia and other Aboriginal groups has been spurred on by customs and traditions [1]. Yet the case of Asante was different. Hence attention has been paid to the history of circumcision amongst the people of Asante. More significantly, the health implications associated with circumcision surgery in Asante have been highlighted. Possible benefits from the practice of circumcision and the potential dangers associated with it, especially the operations of the Asante circumcision surgeons (Wanzams) have been amply scrutinised in the narrative. In the conclusion, attention is paid to some of the scientific arguments for male circumcision. The study is purely qualitative relying on documentary and non-documentary sources. Some of the documentary sources have been gleaned from journal articles, news papers and books etc. The non-documentary data have been sourced from interviews. Both the documentary and non-documentary sources have been thematically pieced together to form a social history of medicine narrative which has potential ramifications on the essence of male circumcision by Wanzams, as well as the need for further research, training and dialogue in the practice in Ghana and Asante in particular.展开更多
文摘This study presents a comparative analysis of two image enhancement techniques, Continuous Wavelet Transform (CWT) and Fast Fourier Transform (FFT), in the context of improving the clarity of high-quality 3D seismic data obtained from the Tano Basin in West Africa, Ghana. The research focuses on a comparative analysis of image clarity in seismic attribute analysis to facilitate the identification of reservoir features within the subsurface structures. The findings of the study indicate that CWT has a significant advantage over FFT in terms of image quality and identifying subsurface structures. The results demonstrate the superior performance of CWT in providing a better representation, making it more effective for seismic attribute analysis. The study highlights the importance of choosing the appropriate image enhancement technique based on the specific application needs and the broader context of the study. While CWT provides high-quality images and superior performance in identifying subsurface structures, the selection between these methods should be made judiciously, taking into account the objectives of the study and the characteristics of the signals being analyzed. The research provides valuable insights into the decision-making process for selecting image enhancement techniques in seismic data analysis, helping researchers and practitioners make informed choices that cater to the unique requirements of their studies. Ultimately, this study contributes to the advancement of the field of subsurface imaging and geological feature identification.
文摘This study examines the turbidite dynamics and hydrocarbon reservoir formation in Ghana’s Tano Basin, which is located in coastal West Africa. Through an exploration of geological processes spanning millions of years, we uncover key factors shaping hydrocarbon accumulation, including source rock richness, temperature, pressure, and geological structures. The research offers valuable insights applicable to exploration, management, and sustainable resource exploitation in coastal West Africa. It facilitates the identification of exploration targets with higher hydrocarbon potential, enables the anticipation of reservoir potential within the Tano Basin, and assists in tailoring exploration and management strategies to specific geological conditions of the Tano Basin. Analysis of fluvial channels sheds light on their impact on landscape formation and hydrocarbon exploration. The investigation into turbidite systems unveils intricate interactions involving tectonics, sea-level fluctuations, and sedimentation patterns, influencing the development of reservoirs. An understanding of sediment transport and depositional settings is essential for efficient reservoir management. Geomorphological features, such as channels, submarine canyons, and distinct channel types, are essential in this situation. A detailed examination of turbidite channel structures, encompassing canyons, channel complexes, convex channels, and U-shaped channels, provides valuable insights and aids in identifying exploration targets like basal lag, channel levees, and lobes. These findings underscore the enduring significance of turbidite systems as conduits for sediment transport, contributing to enhanced reservoir management and efficient hydrocarbon production. The study also highlights how important it is to examine the configuration of sedimentary layers, stacking patterns, and angular laminated facies to identify turbidites, understand reservoir distribution, and improve well design. The dynamic nature of turbidite systems, influenced by basin characteristics such as shape and slope, is highlighted. The research provides valuable insights essential for successful hydrocarbon exploration, reservoir management, and sustainable resource exploitation in coastal West Africa.
基金Project(41472240)supported by the National Natural Science Foundation of ChinaProjects(2015B25514,2015B17214)supported by the Fundamental Research Funds for the Central Universities,China。
文摘Cracks resulting from cyclic wetting and drying of expansive soils create discontinuities and anisotropy in the soil.The representative elementary volume(REV)defined by the continuous-media theory cannot be applied to cracked expansive soils that are considered discontinuous media.In this study,direct shear tests of three different scales(30 cm^(2),900 cm^(2),1963 cm^(2))and crack image analysis were carried out on undisturbed soil samples subjected to drying-wetting cycles in-situ.The REV size of expansive soil was investigated using the crack intensity factor(CIF)and soil cohesion.The results show that soil cohesion decreased with increasing sample area,and the development of secondary cracks further exacerbated the size effect of sample on cohesion of the soil.As shrinkage cracks developed,the REV size of the soil gradually increased and plateaued after 3−5 cycles.Under the same drying-wetting cycle conditions,the REV size determined using soil cohesion(REV-C)is 1.75 to 2.97 times the REV size determined using CIF(REV-CIF).Under the influence of shrinkage cracks,the average CIF is positively correlated with the REV size determined using different maximum permissible errors,with the coefficient of correlation greater than 0.9.A method for determining the REV-C based on crack image analysis is proposed,and the REV-C of expansive soil in the study area under different exposure times is given.
文摘Health and Safety issues in the construction industry are of much concern to stakeholders, particularly because of their impact on the industry. This paper explored the roles and responsibilities of stakeholders in ensuring health and safety at the construction site. A well-structured interview guide was adopted for the qualitative study. Content analysis was adopted for the analysis of the results. The study revealed that the twelve roles identified by the stakeholders are only limited to the few laws and regulations they are aware of. Whereas the Contractors identified provision of welfare facilities, provision of health and safety policy, and health and safety plan as their key roles, the Consultants’ role was mainly limited to provision of competent site agent and provision of site layout. Abiding by the contractors’ instruction was identified by the Construction Workers as their key responsibilities. The local government officials also identified enforcement of CHS laws and regulations and reporting of incidents to the appropriate authorities, whereas the traditional authorities identified the enforcement of CHS laws and regulations including bye laws and enforcement of customs as their key roles. The findings further show that the stakeholders failed to appreciate some key roles and responsibilities enshrined in CHS laws and regulations in Ghana. The findings contribute to knowledge on stakeholders’ responsibilities in ensuring CHS, and provide valuable reference and insight to practitioners on the roles and responsibilities of the various stakeholders. It is recommended to train and educate stakeholders on all the relevant laws and regulations on CHS in order to improve health and safety at the construction site. The government should also set up a body such as Construction Authority to educate, coordinate, monitor and audit the activities of stakeholders to improve CHS at construction sites.
文摘Although Ghana produces natural gas and has several gas reserves, the country still depends on supplies from neighbouring countries for power generation due to challenges like fuel suppl</span><span style="font-family:Verdana;">y</span><span style="font-family:Verdana;"> inefficiencies and increasing cost of gas production. Gas supply is thus a limiting factor for power generation. This study explores strategies to improve gas supplies for sustainable power generation in Ghana. The study examined the underlying factors inhibiting gas supplies in Ghana, investigated the risks in the gas supply industry, and explored strategies for improving gas supplies in Ghana. The study adopted an inductive approach that utilises both qualitative and quantitative research methods. With the use of questionnaires, data were collected from 151 respondents who were selected by purposive and snowball sampling procedures. The collected data were descriptively and inferentially analysed with analytical tools in the SPSS. The study</span><span style="font-family:Verdana;">’</span><span style="font-family:Verdana;">s findings conclude that factors that inhibit gas supply in Ghana include the lack of growth and supply investment in the gas supply industry, power sector debt on the gas market, and the lack of an extensive distribution infrastructure/network. Also, the gas industry in Ghana lacks the requisite investment drive which culminates into inefficiency and ultimately undermines efforts to achieve sustainable power generation. Politics influence in issues relating to gas supplies in Ghana inhibits long-term supply relationships and permanent infrastructure in gas supply, both locally and on the world market.
基金supported by the Forestry Public Benefit Research Projects of National Forestry Administration under Grant No.201304303National Natural Science Foundation of China under Grant No.31370619+1 种基金Science and Technology Project of the Fujian Province under Grant No.2014N0002China Postdoctoral Science Foundation under Grant No.132300148
文摘Biomass production and nutrient （N, P, K, Ca and Mg） accumulation, distribution and cycling were quantified in young, mature and over-mature （10-, 22-, and 34-year old） Chinese fir [Cunninghamia lanceolate （Lamb.） Hook] plantations in southern China. Total stand biomass of young, mature and over-mature stands was 38, 104 and 138 t ha-1 respectively. Biomass production increased significantly with age. Stem wood represented the highest percentage of stand biomass, accounting for 41, 55 and 63 % in the young, mature and over-mature plan- tations respectively. Nutrients concentration was highest in live needles and branches, and lowest in stem wood. The plantations accumulated more N, followed by K, Ca, Mg, and P. Nutrient return amount, nutrient utilization effi- ciency, nutrient turnover time, the ratio of nutrient return and uptake increased with stand age, which implies that young Chinese fir deplete soil nutrients to maintain growth, and efficiently utilize nutrients to decrease dependence on soil nutrients as they age. Harvesting young Chinese fir plantations would therefore lead to high nutrient loss, but prolonging the rotation length could improve soil recovery, and help sustain productivity in the long-term. Improved nutrient return through litterfall as stands get older may also be beneficial to nutrient pool recovery.
文摘Negative Pressure pulmonary oedema (NPPO) is a medical emergency. It occurs when there is a strong inspiratory effort in obstructed upper airway. Laryngospasm is the main cause of postextubation negative pressure pulmonary oedema. Though it is life-threatening, early diagnosis and prompt treatment lead to rapid resolution with no residual respiratory complications. The mainstay management is to provide respiratory support, mostly in the intensive care unit. The recommended mode of respiratory support is to provide an invasive or non-invasive positive airway pressure. This requires the use of a ventilator. Most surgery centres in sub-Saharan Africa do not have intensive care unit or ventilators in their recovery wards. We report two cases of postextubation NPPO which occurred in a typical African hospital with no ventilator. All these two cases were successfully managed with a non-rebreather mask. The periods of resolution, both clinical and radiological, were 24 - 48 hrs. This is not significantly different from the resolution periods quoted in literature from cases managed in well-resourced centres with means of positive pressure ventilation. We therefore conclude that early detection and prompt initiation of management are important keys which can lead to good outcomes, even in low-resource centres.
文摘The objective of this work was to determine the effect of transport time （up to 11 hours） on animal welfare. 540 animals （cows, bulls and calves）, three transport times of 2, 4 to 6, and 10 to 11 hours, and two space allowances （2 m2 and 1.5 m2 per animal for cows and bulls; and 1.2 m2 and 0.8 m2 per animal for calves） were used for the experiment during transport from farms to the abattoir in Uppsala, Sweden. Measurements were made on five animals on each trip. Stress response parameters considered were cortisol, glucose, lactate, creatine kinase and heart rate. Blood samples were taken before and after transport. Heart rate sensors were mounted on the animals at least 30 minutes before loading and measurements were made continuously from farms to the abattoirs until stunning. The results of heart rate measurement indicated that loading, un-loading and forced movement in the stunning box were the most stressful events. However, the results of statistical analysis confirmed that transport time doesn＇t have significant effect （P 〈 0.05） on heart rate. Concentration level of cortisol increased by 10 folds during short transport. However, cortisol concentration decreased with an increase of transport times （P 〈 0.01）. Glucose concentrations increased with transport time in all animal categories （P ≤ 0.01）. Transport time has significant effect on concentration levels of glucose （P ≤ 0.01）, creatine kinase （P 〈 0.001） and lactate （P 〈 0.01） particularly after 6 hours journey time.
文摘Allanblackia parviflora A. Chev. also called vegetable tallow tree provides a variety of non-timber forest products of great importance to rural households including shade, timber, medicine and seed oil but attempts have not been made to improve the tree species and increase its production. Consequently, the species is being threatened due to unsustainable exploitation and poor regeneration and cultivation appears as the only viable option. In order to cultivate the species at meaningful scale, it is necessary to establish the optimum range of environmental factors that influence its propagation and growth. This study was therefore designed to investigate Allanblackia growth parameters and bio-accumulation under different growth media in a greenhouse study. The media were: 1) TS = top soil alone, 2) AB soil = Allanblackia soil alone, 3) TS + H = Top soil alone + humus, 4) AB + TS = Allanblackia soil alone + Top soil alone and 5) SAB = Sterilized Allanblackia soil alone. Each treatment was replicated three times in a complete randomized design. The experiment lasted for 18 months. Results showed that Fe was the micronutrient that accumulated greatest in the plant tissue. Among the treatments, Allanblackia soil showed the highest accumulation of Zn in the plant tissue with the top soil showing the least (7.67 mg·kg<sup>-l</sup>). Humus contributed largely to the bio-accumulation of Cu in the plant tissue. Bio-accumulation of manganese in the plant tissue ranged from 13.30 mg·kg<sup>-l</sup> to 207 mg·kg<sup>-l</sup> suggesting difference in manganese absorption by Allanblackia as influenced by the treatments. The growth parameters of Allanblackia parviflory were impacted differently by the growth media. The result was however controversial since no differences were found between growth of seedlings in sterilized Allanblackia soil and Allanblackia soil.
文摘This study utilizes multiple regression analysis and the technique for computing economies of scale to evaluate the dynamics of NRW in the AER of GWCL. Data on monthly total production, billed consumption, total revenue, total production cost and the volume of NRW spanning the period January 2015 to June 2019, was obtained from the headquarters of AER and used for the analysis. The study showed that NRW averaged 59.3% for the period under consideration, which far exceeds the 25% threshold set by the World Bank for developing economies. It was also established that a fairly inelastic relationship exists between NRW and total revenue. Results further show that resources are not optimally used in the AER as proof of diseconomies of scale was observed.
文摘The enormity of the problem of construction accidents and hazards in the Ghanaian construction industry (GCI) calls for the need to engage in relevant research to equip stakeholders with the required knowledge to improve construction health and safety (CHS) and reduce site accidents and hazards. The complexity of the problem of accident causation explains a large number of conceptual models developed to aid the understanding of the dynamics involved in CHS. This paper involved a qualitative study to identify causes of accidents and hazards in the GCI and underlying issues requiring remedying and also a desk study to review Health and Safety related theories and concepts from extant literature to explain and contribute to the improvement of CHS. The paper contributes to the use of theories to advance studies on improving health and safety at construction sites, especially in developing countries like Ghana, where such studies have so far attracted little attention. The framework may enable construction stakeholders to easily identify problem areas on site and apply required improvement measures to create a healthier and safer construction site. The findings may provide useful knowledge to improve CHS and reduce site accidents and hazards, and also provide a multi-theory approach for understanding the dynamics of the complexity of the problems involved in CHS.
文摘Coconut (Cocos nucifera L.) is an important oilseed and a multipurpose perennial plantation crop. It is mostly grown in humid and coastal areas of Ghana. In June 2019, leaf spot disease was observed on coconut seedlings in 10 coconut growing Districts in Ghana. The Initial symptoms appeared as elliptical, brown-dark-red lesions, 4 - 6 mm on affected leaves. Lesions reached 2.0 cm and gradually developed into spindly, dark brown spots with a light tan centre. A study including survey and laboratory work was carried out to assess disease prevalence and to identify the causal agent of the disease on coconut seedlings, in order to formulate effective management strategies against it. A total of 250 symptomatic leaves were picked from ten selected Districts for laboratory analysis. Additionally, the ribosomal internal transcribed spacer (ITS) region and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) of the isolated pathogen were amplified using ITS1 and ITS4, gpd1 and gpd2 primers respectively. The disease incidence peaked at 95%. Fungal colonies on PDA grew to 50 - 70 mm in diameter in one week at a temperature of 28°C ± 1°C with an even to undulating, immersed striated, mycelium;aerial mycelium being dark velvety green and sometime woolly-cottony. Acervuli formed on the aerial mycelium and contained black powderish conidial masses. Hyphae characteristics were similar to that of Curvularia pseudobrachyspora. Pathogenicity tests were done following Koch’s postulate. For molecular confirmation, the combined ITS (MT075719) and GAPDH (MT075720) sequences were compared with published sequences of 52 Curvularia isolates and eight Bipolaris isolates using phylogenetic analysis. This is the first report of C. pseudobrachyspora as a causal agent of leaf spot on coconut seedlings in Ghana and possibly Africa but the pathogen has been reported on other crops in China, Florida and India.
文摘This paper explored stakeholders’ compliance with existing laws and regulations related to construction health and safety (CHS) in the Ghanaian construction industry (GCI). Qualitative research approach was adopted for the data collection, using semi-structured interview guide. An in-depth face-to-face interview based on the grounded theory approach was conducted with actors who play important roles in ensuring health and safety at the construction site as well as key officers and professionals who are the major stakeholders in the GCI. Content analysis was adopted for the analysis of the qualitative data. The findings of the study show customary laws, bye laws, Labour Act, 2003 (Act 651), Local Governance Act, 2016 (Act 936) and the contract document as the key existing CHS related laws and regulations that the stakeholders comply with. The stakeholders also identified the following construction health and safety related regulations in the GCI which have low compliance rate: Factories, Shops and Offices Act, 1974 (Act 323), Environmental Protection Act, 1994 (Act 490), among others. The findings of the research contribute to knowledge of stakeholders’ compliance with existing laws and regulations related to CHS, and underscore the need to ensure monitoring and enforce compliance in the GCI. The findings further identify areas for stakeholders to focus attention on ensuring good health and safety practices, and also expose critical training and education needs for stakeholders in the GCI. The findings provide valuable insights on stakeholders’ compliance with laws and regulations related to CHS in Ghana, which may be applicable to other developing countries with similar construction industry.
基金Federal Ministry of Education and Research (BMBF) of Germany,funded the PhD programme of the lead author through the West African Science Service Centre for Climate Change and Adapted Land use (WASCAL)。
文摘Background: Modelling aboveground biomass(AGB) in forest and woodland ecosystems is critical for accurate estimation of carbon stocks. However, scarcity of allometric models for predicting AGB remains an issue that has not been adequately addressed in Africa. In particular, locally developed models for estimating AGB in the tropical woodlands of Ghana have received little attention. In the absence of locally developed allometric models, Ghana will continue to use Tier 1 biomass data through the application of pantropic models. Without local allometric models it is not certain how Ghana would achieve Tier 2 and 3 levels under the United Nations programme for reducing emissions from deforestation and forest degradation. The objective of this study is to develop a mixedspecies allometric model for use in estimating AGB for the tropical woodlands in Ghana. Destructive sampling was carried out on 745 trees(as part of charcoal production) for the development of allometric equations. Diameter at breast height(dbh, i.e. 1.3 m above ground level), total tree height(H) and wood density(ρ) were used as predictors for the models. Seven models were compared and the best model selected based on model efficiency,bias(%) and corrected Akaike Information Criterion. The best model was validated by comparing its results with those of the pantropic model developed by Chave et al.(Glob Chang Biol 20:3177–3190, 2014) using equivalence test and conventional paired t-test.Results: The results revealed that the best model for estimating AGB in the tropical woodlands is AGB =0.0580ρ((dbh)2 H)0.999. The equivalence test showed that this model and the pantropic model developed by Chave et al.(Glob Chang Biol 20:3177–3190, 2014) were equivalent within ±10% of their mean predictions(p-values <0.0001 for one-tailed t-tests for both lower and upper bounds at 5% significant level), while the paired t-test revealed that the mean(181.44 ± 18.25 kg) of the model predictions of the best model of this study was significantly(n = 745, mean diff. = 16.50 ± 2.45 kg;S.E. = 1.25 kg;p < 0.001) greater than that(164.94 ± 15.82 kg) of the pantropic model of Chave et al.(Glob Chang Biol 20:3177–3190, 2014).Conclusion: The model developed in this study fills a critical gap in estimating AGB in tropical woodlands in Ghana and other West African countries with similar ecological conditions. Despite the equivalence with the pantropic model it remains superior to the model of Chave et al.(Glob Chang Biol 20:3177–3190, 2014) for the estimation of AGB in local tropical woodlands. It is a relevant tool for the attainment of Tier 2 and 3 levels for REDD+. The model is recommended for use in the tropical woodlands in Ghana and other West African countries in place of the use of pantropic models.
文摘The performance of solar PV modules is significantly affected by temperature. This paper focuses on the determination of the effect of temperature on a commercial mono-crystalline silicon PV module whose temperature coefficients were not provided by the manufacturer for installation in Kumasi, <span style="font-family:Verdana;">Ghana,</span><span style="font-family:Verdana;"> Sub-Saharan Africa (SSA) ambient. In order to determine the effect of temperature on the output characteristics of the module, the temperature coefficients of current, voltage and power were determined. First of all, the module was cooled to a temperature between 10</span><span style="font-family:Verdana;">°</span><span style="font-family:Verdana;">C</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">-</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">15</span><span style="font-family:Verdana;">°</span><span style="font-family:Verdana;">C</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> in a cooling chamber, covered with cardboard paper before the outdoor electrical tests using Daystar I-V Curve tracer. The results show that as temperature increases, irradiance decreases significantly leading to a decrease in output power (<i></i></span><i><i><span style="font-family:Verdana;">P</span></i></i></span><span style="font-family:Verdana;"><sub>max</sub></span><span style="font-family:;" "=""><span style="font-family:Verdana;">). The open circuit voltage (<i></i></span><i><i><span style="font-family:Verdana;">V<sub>oc</sub></span></i><span style="font-family:Verdana;"></span></i>) also decreases, whilst short circuit current (<i></i></span><i><i><span style="font-family:Verdana;">I<sub>sc</sub></span></i><span style="font-family:Verdana;"></span></i>) increases slightly. The temperature coefficients were obtained from the slopes of the plots of temperature against <i><i><span style="font-family:Verdana;">P</span></i></i><span style="font-family:;" "=""><span style="font-family:Verdana;"><sub>max</sub>, <i></i></span><i><i><span style="font-family:Verdana;">I<sub>sc</sub></span></i><span style="font-family:Verdana;"></span></i></span><i> </i><span style="font-family:Verdana;">and <i></i></span><i><i><span style="font-family:Verdana;">V<sub>oc</sub></span></i><span style="font-family:Verdana;"></span></i>. The slopes were used to determine how the respective output characteristics are affected as the module’s temperature rises. The temperature coefficients for power, voltage and current were obtained from the slopes of the graphs using the IVPC software and found to be <span style="font-family:Verdana;"><span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span></span></span><span style="font-family:Verdana;">0.313 W/°</span><span style="font-family:Verdana;">C</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;"><span style="white-space:nowrap;"><span style="white-space:nowrap;"><span style="white-space:nowrap;">−</span></span></span></span><span style="font-family:Verdana;">0.11 V/<span style="white-space:nowrap;">°</span></span><span style="font-family:Verdana;">C</span><span style="font-family:Verdana;"> and 0.00</span><span style="font-family:Verdana;">4 A/°</span><span style="font-family:Verdana;">C</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> respectively. The results indicate that output power is a decreasing function of temperature (that is power decreases when temperature increases). This information will be useful to system developers, manufacturer</span><span style="font-family:Verdana;">s and investors seeking to procure PV modules for installation in Kumasi, Ghana. The temperature coefficients of commercial PV modules could be independently</span><span style="font-family:Verdana;"> verified using the technique employed in this study. Future work will focus on the long-term effect of temperature on the electrical performance characteristics.</span></span>
基金supported by TWAS-USM Postgraduate Fellowship and Research University Grant(RU)(1001/PBIOLOGI/815086)
文摘We studied the impacts of liana cutting as a forest management tool on liana diversity （species richness, Shannon diversity index） and community structure （diam- eter distribution, basal area, species dominance） in the Asenanyo Forest Reserve, Ghana. Two types of silvicul- turally treated forests were studied： Logging treated （LT） and Tropical Shelterwood System （TSS） treated forests. An untreated primary forest was included as a control, result- ing in three forest management systems. Lianas with diameter 〉2 cm were identified in ten 40 × 40 m2 plots within each management system. Liana cutting signifi- cantly reduced liana species richness, Shannon diversity index, and basal area in the LT forest after two decades. However, liana species richness and basal area werecomparable in the TSS treated and untreated forests, indi- cating significant recovery in the former after over six decades. Sφrensen similarity index of liana species com- position between the untreated forest and each of the treated forests was moderate. Our findings suggest that liana cutting most likely influenced the dominance of some liana species. In view of the adverse impact of blanket liana cutting on liana diversity, selective liana cutting is rec- ommended as a means of controlling liana numbers while maintaining liana diversity.
文摘Communication networks have undergone rapid developments in the past few decades in many Sub-Saharan African countries. The increasing number of subscribers and demand for greater variety of services in these countries make it difficult for network operators to provide the service varieties subscribers want while maintaining acceptable levels of quality of service. This paper analyzes the radio network of cellular networks in terms of traffic distribution over the existing number of communication channels using MATLAB/Simulink. A scale-free user network, which takes into account user behavior in a realistic physical network, has been used to model a more realistic cause for call blockings in a typical cellular network deployment under a Sub-Saharan environment. Peak recorded traffic distribution was observed to have overwhelmed the existing number of channels provided by the network operators for some cells eventually leading to increase in call drop rates. This high call blocking probability was attributed to poor network monitoring by the network operators to match the ever changing traffic intensities.
文摘A comparative study was carried out to determine the most suitable substrate for breeding of midges (Forcipomyia spp.) and the implications for pollination and yield in a typical cocoa production system in the forest ecological zone of Ghana. For the field experiment, the typically available substrates in cocoa farms which were used as the treatments under cocoa trees were: 1) rotten cocoa leaf litter;2) rotten cocoa pod husks;and 3) rotten banana pseudostem. The untreated cocoa trees served as control. The experiment was set up in a randomized complete block design with three replications. For the laboratory experiment, the design was completely randomized design with four replications. The objective was to determine which substrate best supported breeding of the midges. The rotten banana pseudostem substrate recorded the highest population (7680) of Forcipomyia spp. after 56 days of observation. The cocoa pod husk and cocoa leaf litter recorded populations of 5226 and 1920, respectively. Similar observations were recorded in the level of pollination of the cocoa trees treated with rotten banana pseudostem (95.78%), cocoa pod husks (89.05%) and cocoa leaf litter (68.42%). Application of all substrates to the cocoa tree resulted in a 77% mean reduction in flower abortion as compared to the control. Fruit abortion, on the other hand, was significantly greater in trees treated with rotten banana pseudostem (73.7%) and rotten cocoa pod husks (71.3%) than in trees treated with rotten cocoa leaf litter (54.3%). Application of banana substrate explained 88% of the variation in cherelle production (fruit set) whereas cocoa pod husks and cocoa leaf litter accounted for 71% and 94%, respectively, of the variation in cherelle production. The study concluded that although cocoa leaf litter resulted in average increases in midges population and subsequently not too high levels of pollination, there was a significantly higher number of set fruits retained which implied high cocoa pod yields. Consequently, in accordance with the observed trend cocoa leaf litter should be considered as the most appropriate substrate for midges activity in cocoa for high yields.
文摘Human orofacial clefts (OFCs) are congenital anomalies that result from the breakdown of normal mechanisms that regulate the formation of the human face. They could be syndromic or non-syndromic, with a global incidence of 1:700 per live births. Environmental and genetic factors are thought to play various roles in the aetiology of OFCs. This study seeks to establish the diversity, distribution and pattern of inheritance of OFCs as well as environmental and other risk factors associated with OFCs in a Ghanaian population. A family-based, descriptive cross-sectional study that employed an interview-based survey questionnaire was used to obtain information from 467 families with history of OFCs. We employed chi-square statistics to analyse the data and used graphs to interpret the data. All previously reported subphenotypes of OFCs were observed by the present study. Clinically, about 12% of clefts in the study population were syndromic. The most common syndromic forms observed were Pierre Robin Sequence, cleft-with-club foot abnormalities and Van der Woude Syndrome. Only about 5% of clefts in the study cohort were familial. The study also established that lower level of education of parents, poverty, late antenatal care and dietary folate deficiency are major environmental factors associated with clefts in the Ghanaian population. In conclusion, OFCs are non-randomly distributed in Ghana and folate deficiency could likely be a source of genetic mutations and “epimutations” that cause OFCs, since folate is essential for DNA methylation, replication and repair as well as histone modification.
文摘This paper studies the history of circumcision amongst religious and traditional societies and the arguments on the medical or non-medical essence of the practice. The paper further highlights amongst the Asante people of Ghana, a practice argued to have been introduced by Islamic Wanzams who are severally referred to as Muslim Circumcision Surgeons. Often circumcision amongst communities in West, Southern Africa, Asia and other Aboriginal groups has been spurred on by customs and traditions [1]. Yet the case of Asante was different. Hence attention has been paid to the history of circumcision amongst the people of Asante. More significantly, the health implications associated with circumcision surgery in Asante have been highlighted. Possible benefits from the practice of circumcision and the potential dangers associated with it, especially the operations of the Asante circumcision surgeons (Wanzams) have been amply scrutinised in the narrative. In the conclusion, attention is paid to some of the scientific arguments for male circumcision. The study is purely qualitative relying on documentary and non-documentary sources. Some of the documentary sources have been gleaned from journal articles, news papers and books etc. The non-documentary data have been sourced from interviews. Both the documentary and non-documentary sources have been thematically pieced together to form a social history of medicine narrative which has potential ramifications on the essence of male circumcision by Wanzams, as well as the need for further research, training and dialogue in the practice in Ghana and Asante in particular.
