Dynamics of co-behaviour of climate processes over Southern Africa

Large-scale climate processes such as El Niño-Southern Oscillation (ENSO), Antarctic Oscillation (AAO), and many others, play varying roles in regional climate variability across the world. While the role of singular processes have been explored in many studies, the combined influence of multiple large-scale processes has received far less attention. Key to this is the challenge of developing methodologies to support the analysis of multiple processes interacting in potentially non-linear ways (co-behaviour) in a particular region. This study details the development of such a methodology and demonstrates its utility in the analysis of the co-behaviour of largescale process interactions on regional precipitation and temperature variability over southern Africa. The study defines co-behaviour as the interaction of large-scale processes that may influence regional circulation leading to climate variability. A novel methodology which involves a combination of analysis techniques such as Self-Organizing Maps (SOM) and Principal Component Analysis (PCA) is developed to identify and quantify such co-behaviour which accommodates potentially non-linear interactions. This methodology is evaluated in the context of southern African regional climate using three key processes, namely ENSO, AAO and Inter-tropical Convergence Zone (ITCZ), and characterizations of regional circulation, and temperature and rainfall variability. Analysis of co-behaviour under observed conditions identifies results that concur with prior studies, in particular the dominant regional response to ENSO, but also establishes key examples of co-behaviour such as the role of the AAO in moderating and altering the regional response to ENSO which is important for understanding regional climate variability. Application of the approach to Global Climate Model (GCM) simulations of past climate reveals that while many GCMs are able to capture individual processes, in particular ENSO, they fail to adequately represent regional circulation variability and key observed co-behaviour. The study therefore clearly demonstrates the importance of co-behaviour in understanding regional climate variability as well as showing the usefulness of the new methodology in investigating co-behaviour. Finally, the new insights into evaluating model performance through the lens of core climate processes and their interaction provides a significant step forward in both model development and application for decision making

West African Summer Monsoon Precipitation Variability as Represented by Reanalysis Datasets

Focusing on West Africa, a region riddled with in situ data scarcity, we evaluate the summer monsoon monthly rainfall characteristics of five global reanalysis datasets: ERA5, ERA-Interim, JRA-55, MERRA2, and NCEP-R2. Their performance in reproducing the West African monsoon (WAM) climatology, interannual variability, and long-term trends for the main monsoon months are compared to gauge-only and satellite products. We further examine their ability to reproduce teleconnections between sea surface temperatures and monsoon rainfall. All reanalyses are able to represent the average rainfall patterns and seasonal cycle; however, regional biases can be marked. ERA5, ERA-Interim, and NCEP-R2 underestimate rainfall over areas of peak rainfall, with ERA5 showing the strongest underestimation, particularly over the Guinea Highlands. The meridional northward extent of the monsoon rainband is well captured by JRA-55 and MERRA2 but is too narrow in ERA-Interim, for which rainfall stays close to the Guinea Coast. Differences in rainband displacement become particularly evident when comparing strong El Niño Southern Oscillation (ENSO) years, where all reanalyses except ERA-Interim reproduce wetter Sahelian conditions for La Niña, while overestimating dry conditions at the coast except for NCEP-R2. Precipitation trends are not coherent across reanalyses and magnitudes are generally overestimated compared to observations, with only JRA-55 and NCEP-R2 displaying the expected positive trend in the Sahel. ERA5 generally outperforms ERA-Interim, highlighting clear improvements over its predecessor. Ultimately, we find the strengths of reanalyses to strongly vary across the region

Competitive interactions between copper(II) ions, thiomolybdates, and some biological ligands

Thiomolybdates formed in the rumen have been implicated in copper deficiency in ruminants. However, the chemical basis of the interaction between the individual thiomolybdates and both dietary and systemic copper is poorly understood. Which particular thiomolybdate(s) are formed in the rumen has also been an issue of contention. In part, these problems can be ascribed to lack of availability of synthesized thiomolybdates of known purity. The main objective of this study was to determine the chemical mechanism by which thiomolybdates render Cu(II) unavailable for utilization in ruminants, particularly cattle. In the thesis, facile methods are described for the preparation of ammonium dithiomolybdate and tetrathiomolybdate, and of cesium monothiomolybdate and trithiomolybdate. The methods involve successive replacement of the oxygen atoms in sodium molybdate by sulfur atoms using ammonium sulfide. This is the first time the cesium salt of the monothiomolybdate has been reported in pure form. Previous studies in the literature have assumed purity of the thiomolybdates based on elemental analysis; this is not sufficiently discriminating. A more thorough analysis, based on multi-wavelength analyses of the UV/visible spectra of the products, and of mixtures, was used to determine the actual purity of these samples. Discrepancies in previously published spectra for these materials can now be ascribed to unrecognized variations in purity. It is also possible to judge the performance of previously published purification methods of these materials. The relative proportions of the different thiomolybdates formed under conditions simulating those within the rumen fluid of ruminants prone to copper deficiency have been measured from UV/visible spectra data. Pure synthesized thiomolybdates have also been used to study spectrophotometrically the interactions between the thiomolybdates and Cu(II) in the presence and absence of some inorganic ligands, low molecular mass complexing agents and bovine serum albumin, in aqueous solutions. Some small peptides (His-Lys, Thr(Ac)-His-Lys and Asp-Thr(Ac)-His-Lys) were synthesized and characterized and employed as models to study the influence of bovine serum albumin, the main protein for transporting "exchangeable" copper in the blood plasma, on the Cu(II)-thiomolybdate interactions. 1H NMR was used to study the acid-base behaviour of these peptides and their complexation with Cu(II) in H20. Changes in the chemical shifts of these peptides were obtained as a function of pH and from these, reliable Ka values have been established. Probable binding sites of Cu(II) and the relative strengths of binding to these peptides are also discussed. To investigate the possible 3-way interaction between bovine serum albumin, Cu(II) and thiomolybdates, both 1H NMR and UV/visible spectroscopy were used to study the ternary complexation between the peptide models, Cu(II) and thiomolybdates. The results show clearly that ternary complexes, which are poorly soluble in water, are formed between these three species. It was not possible to come to a definite conclusion about the structure of the ternary complex. However, results seem to suggest a core unit where the peptide binds Cu in the +1 state via the terminal amino N, the imidazole N-3 nitrogen and two sulfur atoms from the thiomolybdate. Polymerization of this core unit seems to occur, especially for the interaction involving the tetrathiomolybdate. Throughout the studies it was noted that tetrathiomolybdate behaved differently from the other thiomolybdates in several respects: stability in aqueous solutions; the kinetics of the interactions with Cu(II); the stability of the resulting products from the interaction with copper(II); the formation of insoluble products and/or polymerization of the core units of the ternary complex initially formed

Containerisation, Portable Architecture and the Image of Ghanaian Cities

The gains of the urban development strategies have served as pull factors of rural dwellers to the urban centres with negative consequent effect on urban open spaces and corridors in most Ghanaian cities. Owing to the lack of formal employment opportunities, any available space in the cities of Ghana has been taken over by emigrants and residents who hawk around the urban spatial corridors and eventually build Container structures (container architecture) to carry out their commercial activities in more permanent manner. Through a mixed methods and strategies, seven major cities and eight other settlements were explored to better understand and appreciate the spatial and regulatory requirements for planning and design of Container  for use in a city/built environment and the design of Containers in Ghanaian socio-cultural and socio-economic milieu. Amongst the key findings is that Ghanaian city-authorities have commoditised the container structures through official registrations for daily collection of fees/taxes without making containerization processes as part of the overall regional/national planning and physical development strategies. Keywords: Architecture, Containerisation, Ephemeralization, Container structures, Commoditisation, Ghanaian cities

A Quantitative Assessment of Relationship between Urban Green Parks and Self-Esteem of Urban Children and Adolescents (Teenage Group) in Ghana

The importance of urban green parks in sustainable urban design development has gained currency in recent times, not only because urban parks do enhance the visual image of the city, or ameliorate its harsh climatic conditions, or purify its air, but they help develop high self-esteem of children and adolescents.  The study examines the correlation between the presence of green parks and self-esteem development among urban adolescents in Kumasi, the second largest city and Accra, the largest and the capital city of Ghana as case studies. The Children and adolescents used as respondents had their ages ranging from 13 to 19 years (teenage group). Using the Rosenberg Self-Esteem Scale as a measure, the study revealed that the lack of green parks at Tafo (Kumasi) has significantly impacted the self-esteem of Tafo adolescents; {t (59) =13.178, P=0.000 (two-tailed)}. And, Respondents who socialize in green parks at Cantonments (Accra had high self-esteem levels, whereas respondents who have no access to green parks at Tafo (Kumasi) had low self-esteem. Keywords: Green parks, Socialization, Self-esteem, Urban, Tennage Group, Kumasi and Accra

Interfacial morphology and descaling of reheated stainless steel

Please read the abstract in the section 00front of this documentDissertation (MEng (Metallurgical Engineering))--University of Pretoria, 2001.Materials Science and Metallurgical Engineeringunrestricte

Shopping malls as catalyst for sub-urban development in Ghana

The concentration of population in major cities is usually the consequence of the concentration of employment opportunities, goods and services in such cities. These goods and services act as pull factors to the regional population, especially from the suburban or rural areas, to densely populated cities. The resulting migration creates congestion of all kinds in the cities. Suburban communities are, thus, rendered unattractive for living. This situation is prevalent in Ghana where 75% of migrants into major cities are from suburban areas and the rate of urbanization is 4.1%. Decentralizing amenities to suburban areas would initiate re-distribution of population and thus development. This study investigated the possibility of using the Shopping Mall concept as catalyst to both help develop the suburbia and decongest cities in Ghana. The West Hills Mall at Dunkonah, a suburb near Accra was selected for the study. A mixed research method including  questionnaires, interviews, and observations was used for data collection. Out of a total of 1,642 house owners 328 were sampled and interviewed with questionnaire that delved into their origins, whether they are migrants, and the reasons behind their movement. The study concluded that shopping malls could act as catalysts for development.Keywords: Shopping Malls, Catalyst, Decongestion, Suburbanization, Amenitie

Assessment of the resettlement compensation satisfaction of wood workers at Sokoban, Kumasi

Resettlement has been one of the strategies used to pave way for development and redevelopment of infrastructure in major cities of Ghana in the past few decades. Resettlement is usually characterized by displacement of people and their livelihoods. In Kumasi, resettlement has physicallydisplaced over 10,000 people mostly traders, in and around the Central Business District. Kumasi has undergone significant development in the past two decades in the areas of road and housing construction, resulting in the resettlement of some commercial neighborhoods including the wood merchants from Anloga to allow for the construction of the south-eastern section of the ring road from Oforikrom (Anloga) to Nhyiaeso. This study assessed the outcome of involuntary resettlement of wood merchants from Anloga to Sokoban Wood Village in terms of compensation, improvement in working space and the impact on the timber trade. The study used mixedmethods: it relied on the administration of questionnaires and interviews to gather data from respondents for analysis as well as the use of dependent sample T-test for hypothesis testing to evaluate the change in livelihood that resulted from the resettlement programme. The study revealeda significant improvement in the livelihood of the displaced workers after the resettlement.Keywords: Resettlement, Infrastructure, Compensation, Satisfaction, Livelihood

Farmer’s observation on climate change impacts on maize (Zea mays) production in a selected agro-ecological zone in Ghana

Although maize farmers may not have a clear understanding of climate change, they live close to natural resources and are among the first in perceiving and reacting to environmental changes. They have observed and felt the effects of decreasing rainfall, emphasizing changes in the regularity, length, intensity and timing of rainfall; increasing air temperature, increasing sunshine intensity and seasonal changes in rainfall pattern which is affecting their farming practices. Moreover, farmers are also aware of the interacting effect between bad management practices and changes in climate. For instance, deforestation and clearing of riparian vegetation is considered a major factor increasing soil erosion; the use of agricultural chemicals close to the rivers and streams create hazards for the environment. The study indicates that changes in the onset and cessation of rain have negative impact on maize production and this pose a serious threat to household food security since maize is the staple food of most Ghanaians. Consequently, effective and efficient adaptation and mitigation measures should be promoted to prepare stakeholders in maize production systems to enhance their resilience and flexibility

Biodegradation of alkyl branched aromatic alkanoic naphthenic acids by Pseudomonas putida KT2440

The majority of the world's crude oil reserves consist of highly biodegraded heavy and super heavy crude oils and oil sands that have not yet been fully exploited. These vast resources contain complex mixtures of carboxylic acids known as naphthenic acids (NAs). NAs cause major environmental and economic problems, as they are recalcitrant, corrosive and toxic. Although aromatic acids make up a small proportion of most NA mixtures, they have demonstrable toxicities to some organisms (e.g. some bacteria and algae) and ideally need to be removed or reduced by remediation. The present study analysed the ability of Pseudomonas putida KT2440 to degrade highly recalcitrant aromatic acids, as exemplified by the alkyl phenylalkanoic acid (4'-t-butylphenyl)-4-butanoic acid (t-BPBA) and the more degradable (4'-n-butylphenyl)-4-butanoic acid (n-BPBA). n-BPBA was completely metabolized after 14 days, with the production of a persistent metabolite identified as (4'-n-butylphenyl)ethanoic acid (BPEA) which resulted from removal of two carbon atoms from the carboxyl side chain (beta-oxidation) as observed previously with a mixed consortium. However, when n-BPBA concentration was increased two-fold, degradation decreased by 56% with a concomitant six-fold decrease in cell numbers, suggesting that at greater concentrations, n-BPBA may be toxic to P. putida KT2440. In contrast, P. putida KT2440 was unable to degrade the highly recalcitrant t-BPBA even after 49 days. These findings have implications for NA bioremediation in the environment. © 2011