Economic value of children and fertility preferences in a fishing community in Ghana

Although anecdotal evidence suggests that fertility levels in fishing communities, in Ghana, are very high, the influence of economic and cultural factors on fertility preferences in such communities has not been adequately explored. This article examines the fertility preferences of men and women living at Akplabanya, a fishing community in Ghana. Data were collected from a sample of 354 respondents. The findings of the study show that demand for labour, expectations of long term security, and gendered power relations have contributed to high fertility levels and preferences in the study area. It has been concluded that significant fertility decline in the area will only occur when fertility preferences of men have changed. Family planning programmes must therefore target both men and women. Improving economic status of women will also go a long way to bring about fertility transition in rural communities in Ghana.     

The difficult combination of renting and building a house in urban Ghana: analysing the perception of low and middle income earners in Accra

This study examines the experiences of low and middle income earners in urban Ghana in combining renting and self-building a house with their meagre income. Using a case study of 3 building sites in Accra, this study employs semi-structured interview guide to gather qualitative data from fifty respondents. The conclusion of this study is that improving housing career amidst other competing responsibilities in the life course pathways imposes stress and huge financial burden on households in a manner that they are compelled to forgo or cut down on non-housing consumption such as clothing, up-keep of in-laws, marriage, higher educational qualification and cars among others. This study recommends a revisit of the discussion on the enforcement of the provisions of the Rent Act, 1963 and consideration of the practice of rent deposit and monthly rent. Affordable housing finance options should be a priority of African governments and their development partners.     

Effects of fractures on seismic-wave velocity and attenuation

The effects of fractures on the seismic velocity and attenuation of a rock are investigated using theoretical results and experimental data. Fractures in a rock mass influence the traveltimes and amplitudes of seismic waves that have propagated through them. The displacement discontinuity model, recently employed in fracture investigations, is modified to describe the effect of fractures on seismic-wave velocity and attenuation. This new model, the modified displacement discontinuity model (MDD), is formulated in a way analogous to transmission-line analysis. The fractures are treated as transmission lines for the passage of seismic waves. The MDD takes into consideration realistic fracture parameters which include the fracture length, the fractional area of a fracture surface in contact, and the nature of the infilling material. A single fracture of varying geometric and material properties is shown to affect dramatically the transmission properties of a propagating waveform, and hence the seismic velocity and attenuation. These effects have been shown to result in a frequency-dependent velocity and attenuation. The sensitivity of the fracture parameters to seismic-wave velocity and attenuation was investigated and interesting results were obtained. Fracture parameters used in designing experimental models consisting of synthetically manufactured cracks were fed into the MDD and a well-known crack model, Hudson's model, for comparison. Velocities as a function of the incident-wave angle were obtained from both numerical models and were compared with the results from the experimental modelling. For P waves, the MDD model results show better agreement with those of the experimental model for all crack densities investigated than those from Hudson's model.     

Of silent maids,skilled gardeners and careful madams: gendered dynamics and strategies of migrant domestic workers in Accra,Ghana

Recent studies indicate that many migrants are engaged mainly in the informal sector in low-paid, short-term, and insecure occupations in cities. Using a qualitative research approach, this paper examines the gendered experiences, livelihood strategies and wellbeing of migrants engaged in domestic work in Accra, Ghana. Employing structure-agency theoretical perspectives, the paper also discusses how migrant domestic workers employ their own agency to counter exploitation. The findings show clear gendered patterns of employment in domestic work, with men having stronger agency to negotiate better conditions of work and remuneration. The paper argues that despite the heterogeneity and diversity of the work conditions and experiences of domestic workers in Accra, the importance of gender as a crucial factor mediating the experiences of both male and female domestic workers and their impacts on their wellbeing must be recognised in policies to address and regulate domestic work in Ghana.     

A stochastic differential equation model for assessing drought and flood risks

Droughts and floods are two opposite but related hydrological events. They both lie at the extremes of rainfall intensity when the period of that intensity is measured over long intervals. This paper presents a new concept based on stochastic calculus to assess the risk of both droughts and floods. An extended definition of rainfall intensity is applied to point rainfall to simultaneously deal with high intensity storms and dry spells. The mean-reverting Ornstein–Uhlenbeck process, which is a stochastic differential equation model, simulates the behavior of point rainfall evolving not over time, but instead with cumulative rainfall depth. Coefficients of the polynomial functions that approximate the model parameters are identified from observed raingauge data using the least squares method. The probability that neither drought nor flood occurs until the cumulative rainfall depth reaches a given value requires solving a Dirichlet problem for the backward Kolmogorov equation associated with the stochastic differential equation. A numerical model is developed to compute that probability, using the finite element method with an effective upwind discretization scheme. Applicability of the model is demonstrated at three raingauge sites located in Ghana, where rainfed subsistence farming is the dominant practice in a variety of tropical climates.     

Gold Mineralization in Banded Iron Formation in the Amalia Greenstone Belt,South Africa: A Mineralogical and Sulfur Isotope Study

The Blue Dot gold deposit, located in the Archean Amalia greenstone belt of South Africa, is hosted in an oxide (± carbonate) facies banded iron formation (BIF). It consists of three stratabound orebodies; Goudplaats, Abelskop, and Bothmasrust. The orebodies are flanked by quartz‐chlorite‐ferroan dolomite‐albite schist in the hanging wall and mafic (volcanic) schists in the footwall. Alteration minerals associated with the main hydrothermal stage in the BIF are dominated by quartz, ankerite‐dolomite series, siderite, chlorite, muscovite, sericite, hematite, pyrite, and minor amounts of chalcopyrite and arsenopyrite. This study investigates the characteristics of gold mineralization in the Amalia BIF based on ore textures, mineral‐chemical data and sulfur isotope analysis. Gold mineralization of the Blue Dot deposit is associated with quartz‐carbonate veins that crosscut the BIF layering. In contrast to previous works, petrographic evidence suggests that the gold mineralization is not solely attributed to replacement reactions between ore fluid and the magnetite or hematite in the host BIF because coarse hydrothermal pyrite grains do not show mutual replacement textures of the oxide minerals. Rather, the parallel‐bedded and generally chert‐hosted pyrites are in sharp contact with re‐crystallized euhedral to subhedral magnetite ± hematite grains, and the nature of their coexistence suggests that pyrite (and gold) precipitation was contemporaneous with magnetite–hematite re‐crystallization. The Fe/(Fe+Mg) ratio of the dolomite–ankerite series and chlorite decreased from veins through mineralized BIF and non‐mineralized BIF, in contrast to most Archean BIF‐hosted gold deposits. This is interpreted to be due to the effect of a high sulfur activity and increase in fO₂ in a H₂S‐dominant fluid during progressive fluid‐rock interaction. High sulfur activity of the hydrothermal fluid fixed pyrite in the BIF by consuming Fe²⁺ released into the chert layers and leaving the co‐precipitating carbonates and chlorites with less available ferrous iron content. Alternatively, the occurrence of hematite in the alteration assemblage of the host BIF caused a structural limitation in the assignment of Fe³⁺ in chlorite which favored the incorporation of magnesium (rather than ferric iron) in chlorite under increasing fO₂ conditions, and is consistent with deposits hosted in hematite‐bearing rocks. The combined effects of reduction in sulfur contents due to sulfide precipitation and increasing fO₂ during progressive fluid‐rock interactions are likely to be the principal factors to have caused gold deposition. Arsenopyrite–pyrite geothermometry indicated a temperature range of 300–350°C for the associated gold mineralization. The estimated δ³⁴S_ΣS (= +1.8 to +2.5‰) and low base metal contents of the sulfide ore mineralogy are consistent with sulfides that have been sourced from magma or derived by the dissolution of magmatic sulfides from volcanic rocks during fluid migration.     

Coastal environmental injustice in Ghana: the activities of coastal sediment miners in the Elmina,Cape Coast and Moree area

Human impact has increased stunningly during the last century with coastal problems being one manifestation of environmental injustice with ecological, economic, and social dimensions on coastal resources. The study sought to assess the residents’ perception of coastline changes in the milieu of the rampant sand mining activities along the Elmina, Cape Coast and Moree coastline of Ghana. The study employed the purposive sampling technique: 100 respondents were engaged from the selected study areas through simple random sampling method. Interviews, Focus group discussions, observations and questionnaire were the main instruments used. The study revealed that beach sand mining is widespread across the Elmina-Cape Coast-Moree coastline and takes place in several forms, with the magnitude of sand taken from the beach being dependent on the transportation medium and the purpose to which sand is to be put. It is considered that the 1995 National Environmental Policy has become outdated and the sections dedicated to the coastal zone are irrelevant due to new research data and trends in administration. The time is right for a concerted national policy dedicated to only the coastal zone that takes into consideration the multiplicity of use of the zone and adopts an integrated management approach.