Bemisia tabaci is the vector of cassava mosaic begomoviruses and cassava brown streak viruses which are main production constraints to cassava in sub-Saharan Africa. Current vector dynamics involved in the spread of both viruses in the region was established through comparison of the mitochondria cytochrome oxidase I DNA. Two distinct species were obtained: sub-Saharan Africa clade 1 (SSA1), comprising of two sub-clades (I & II), and a South West Indian Ocean Islands (SWIO) species. SSA1 sub-clade I whiteflies were widely distributed in East Africa. SSA1 sub-clade II whiteflies predominated the coast regions of Kenya, southern & coast regions of Tanzania and widespread in Uganda. SWIO whiteflies occurred in the coastal region of Kenya. This study also revealed that SSA1 sub-clade I haplotypes performed significantly better than SSA1 sub-clade II haplotypes with respect to mean number of eggs laid, developing instars and hatched adults on healthy, African cassava mosaic virus-[Tanzania:2001 ] and East African cassava mosaic Kenya virus-infected plants. There was no boost in whitefly numbers by the CMB-infected plants. The fecundity and development differences observed between SSA1 sub-clade I and II haplotypes have major epidemiology implications on the CMGs in the region

No description available.

This thesis examines the enduring problem of food insecurity in Africa, with a particular focus on Ethiopia and Kenya. It considers food insecurity both in acute terms - the occurrence of famine and chronic terms - famine vulnerability. More specifically it provides a new interpre~tion of the causes of food insecurity in East Africa, with respect to some of the causal factors and viable solutions. It does so by locating the occurrence of famine, and countries vulnerability to it, in the context of the global food system. The global food system is, as yet, an under-examined factor in contemporary famine analysis, particularly in East Africa and this thesis aims to explore it more comprehensively than hitherto. This thesis also makes a substantive contribution to understanding the concept of Food Sovereignty in an African context. Food Sovereignty deserves to be a more significant part of contemporary narratives that at present dominate the political and social dilemmas about food insecurity. However there are serious obstacles such as political relationships, land tenure and the industrial system of agriculture that hinder the development of Food Sovereignty as a viable option. Natural disasters, demographic pressures and ill conceived economic policies are an ongoing part of the story but in essence food insecurity is ultimately political. This thesis concludes that Food Sovereignty should be explored as a political . solution to a political problem.

This thesis tackles issues related to regional integration, trade costs and aid, with empirical work related to the East African Community (EAC). The common thread is the impact of various types of trade costs on the structure and functioning of the economies of EAC member states. The first chapter introduces the literature and chapters 2, 3 and 4 constitute the core of the thesis. Chapter 2 develops a three-good, two-country duality-based general equilibrium model to investigate the effects of different types of aid and preferential trade on welfare and relative prices. The model is innovative in two ways: (i) a regionally tradable good is introduced, the price of which is determined endogenously, (ii) a regional infrastructure good, bought with aid monies, is brought in which lowers trade costs within the region. Using comparative statics, the properties of the model are explored in terms of the effects of tariff and aid shocks on welfare and relative prices. Chapter 3 develops a Computable General Equilibrium (CGE) model calibrated on Uganda and Kenya to gauge the importance of chapter 2’s results. The regional spill-over is now modeled as regional public capital serving as an input in both countries’ production functions. The simulations show how Kenya effectively exports some of the standard aid-induced real exchange rate appreciation to Uganda through a regional trade channel. Distributionally, Kenya’s urban and Uganda’s rural households win—which corresponds to regional comparative advantage patterns. Abolishing the intra-regional tariff increases welfare in Uganda and reduces it in Kenya, showing the ambiguous welfare results of Customs Unions known since Viner. Chapter 4 gauges the importance of border effects in Eastern Africa by testing the law-ofone- price (LOP) hypothesis on a consumer price data-set covering 24 goods in 39 cities in 4 countries. Using level regressions a significant border effect is found, whilst distance also plays a big role, both between and within countries. Neither the nominal exchange rate, nor non-tariff barriers (NTBs) reduce the border effect very much, even though both variables are significant. Looking at specific goods, markets for staple foods are the most integrated. As for the impact of the Customs Union between Tanzania, Uganda and Kenya (since 2005), there is a positive integration effect for the Kenya-Uganda border. Finally, Kenya’s political crisis at the end of 2007 can be linked to higher departures from the LOP throughout the region and can thus be said to have had clear knock-on effects for the landlocked EAC countries that depend on it as a transit country.

No description available.

Lakes Magadi (Kenya) and Manyara (Tanzania) occupy closed basins in the southern Gregory Rift valley. Water in these lakes is presently shallow and saline, testifying to the dominance of evaporation (E) over precipitation (P). Past changes in the P: E ratio, and hence in palaeoclimate, can be reconstructed from evidence of the former extent of these lakes. Lake-level fluctuations engender marked variation in water chemistry, and consequently on the composition of the limnological biota. One approach is to examine the sedimentary record of diatoms (unicellular algae), which are excellent indicators of water chemistry and relative water depth, and whose modem distribution is sufficiently well known to allow the quantitative reconstruction of chemical parameters. Diatom analysis of 116 samples from a series of radiometrically dated (14C and U/Ib) sediment cores has revealed significant changes amongst the diatom assemblages during the Late Quaternary. Conductivity and pH have been estimated from the fossil samples by transfer functions (Gasse unpublished, Gasse 1986b). However, the interpretation of fossil diatom assemblages is often problematical in hypersaline environments. Difficulties arise as a result of the operation of taphonomic and diagenetic processes which can severely alter the composition of the diatom assemblagesfr om the ambient population at the time of deposition. Probably the most important factor responsible for assemblage diagenesis in saline lakes is silica dissolution, and this is explored further by a series of laboratory experiments. Results indicate that silica dissolution acts differentially between species, by removing the smaller, more delicate taxa first, and causing the relative enrichment of large robust forms in the fossil samples. A similar dissolution gradient may be reflected in modem samples studied near hot springs at Magadi. Differential dissolution is potentially an important source of error in palaeoenvironmental reconstructions, but, with the outcome of these experiments, it has been possible to assess the extent to which the dissolution process may have shaped the diatom records from Magadi and Manyara. The bulk of the palaeolimnological evidence is focussed upon two periods, 30,000-20,000 BP and 12,700-9,500 BP. The earlier period is most clearly dated in the core from Manyara, where the diatom record suggests the development of an intermediate level lake between c. 27,500 BP and c. 26,000 BP. This is a more complete representation of the same lake phase found in earlier studies from Manyara by Holdship (1976) based on diatoms, and by Casanova (1986a) on stromatolites 20M above the present lake. This time interval may also be represented by the central portion of the Magadi cores NF1 and NF2 but here dating is more problematical. The period 12,700-9,500 BP was one of major lacustrine transgression across Africa although the fine-structure of this event is less well known. Cores NF1 and NF2 from Magadi provide a detailed register of this phase indicating a major highstand from c. 12,700-11,000 BP when the lake became deep enough to stratify and deposit laminated couplets. At c. 11,000 BP the diatoms show that salinity increased greatly from fresh-oligosaline to meso-hypersaline which was probably a consequence of lake level falling.

My thesis examines dynamics of inclusion and exclusion within Somali social networks in East Africa. It focuses on Somali mobility patterns and financial practices to draw insights on the maintenance, reproduction, and transformation of both solidarity ties and inequalities. By examining Somali communities in Kenya, host of the largest Somali refugee population outside of Somalia, and Uganda, an increasingly important recipient of Somali refugees and migrants, this thesis seeks to understand how mechanisms of social stratification rooted in Somali socio-cultural structures are reproduced in mixed migration flows encompassing both forced and voluntary migrants. It analyses sets of relationships whose continuity and changes are regulated by the interaction of structure, agency, and institutions, and argues, on the one hand, that networks are dominated by groups who hold sway over economic and political resources, precluding others from accessing key assets that may help challenge relations of subordination. On the other, that pre-existing inequalities hinder on the capability to move across both physical and institutional categories. These inequalities can be traced back to asymmetric clan relationships shaped by Somali historical trajectories before and after the implosion of the state. However, this thesis suggests also that kin relationships only partially explain why and how bonds are sustained and forged. Instead, by observing the mechanisms that animate networks, reproducing both solidarity and marginalisation, this thesis teases out how new linkages are created and how Somalis communities accommodate to specific institutional settings, either adapting to narrowing windows of opportunity or maximising the benefits that may be yielded from their widening. The thread running throughout this thesis is the argument that mobility contributes not only to accessing and mobilising strategic resources but also to shaping processes of social stratification. By using ethnographic methods of data collection, this thesis seeks to shed light on rifts in Somali social networks often masked by the veneer of trust.

In this thesis we investigate the supply side of farm households in the Tanzanian region of Kagera and incorporate the results into a welfare analysis of price shocks and trade policy options. The first chapter discusses the relevance of agriculture as an engine of growth and poverty reduction and introduces the context and the data used for the empirical analysis. The second chapter tests for separability of the households demand and supply sides and then estimates supply functions for the main crops. We find that separability cannot be rejected for this sample and that farmers are only partially responsive to price incentives. The third chapter analyses the role of market participation decisions and transaction costs for food supply. We find that transaction costs play an important role in households supply decisions. Moreover, we show that there is a positive although small supply response to prices once controlling for the unresponsiveness of self-sufficient households. The fourth chapter extends the standard welfare impact analysis of price shocks to incorporate supply and demand responses as well as the role of market participation and transaction costs. We find that the results are sensitive to the introduction of households' output, wage and consumption responses.

ABSTRACT TRANSITIONING FROM A THEOLOGICAL COLLEGE TO A CHRISITIAN UNIVERSITY IN EAST AFRICAN CONTEXT: A MULTI-CASE STUDY Semeon Mulatu, Ph.D. The Southern Baptist Theological Seminary, 2012 Chair: Dr. Hal K. Pettegrew This dissertation analyzed and described transitions from a theological or Bible college to a Christian liberal arts college or university in East African context. The research was specially driven by the desire to find out the reasons for such transitions, the challenges of the transition process and how such transitions affect the mission of the institutions, the theological training programs, and the relationship of the institutions with their founding or sponsoring churches. The methodology employed in this study was qualitative, multi-case study research method. The institutes that were selected for this study were five Protestant evangelical higher educational institutions in Ethiopia, Kenya, Uganda, and Democratic Republic of Congo that have transitioned or are transitioning from a theological college to Christian university. The researcher traveled to each of the five institutions included in this study and did interviews with the leaders on-site in one-to-one interviews. The data for this research was collected from multiple sources. These resources include the interviews, documents, reports, printed materials, and field notes of the researcher. This helped the researcher to provide a thick description of each institution's transition. The findings of this researcher display the reasons the selected institutions transitioned to Christian universities, the challenges they faced, and how such transitions affected the mission of the institutions, their theology programs and their relationship to the sponsoring churches. The research then offered a summary and analysis of the data according to the research questions of this study. The implications of this research could help leaders of theological colleges or seminaries that are transitioning or considering to transition to universities to understand the potential challenges they may face due to the transition, the possible impacts of the transition on their overall mission, their relationship with churches, and their theology program. Key Words: Education, Christian Education, Higher Education, Theology, Transitions

Environmental satellites represent an economic and easily accessible monitoring means for a plethora of environmental variables, the most important of which is arguably precipitation. While precipitation can also be measured by conventional rain gages and radar, in most world regions, satellites provide the only reliable and sustainable monitoring system. This thesis presents a methodology for estimating precipitation using information from the satellite-borne precipitation radar of the Tropical Rainfall Measurement Mission (TRMM). The methodology combines the precise, but infrequent, TRMM data with the infrared (IR) and visible (VIS) images continuously produced by geostationary satellites to provide precipitation estimates at a variety of temporal and spatial scales. The method is based on detecting IR patterns associated with convective storms and characterizing their evolution phases. Precipitation rates are then estimated for each phase based on IR, VIS, and terrain information. This approach improves the integration of TRMM precipitation rates and IR/VIS data by differentiating major storms from smaller events and noise, and by separating the distinct precipitation regimes associated with each storm phase. Further, the methodology explicitly quantifies the uncertainty of the precipitation estimates by computing their full probability distributions instead of just single optimal values. Temporal and spatial autocorrelation of precipitation are fully accounted for by using spatially optimal estimator methods (kriging), allowing to correctly assess precipitation uncertainty over different spatial and temporal scales. This approach is tested in the Lake Victoria basin over the period 1996-1998 against precipitation data from more than one hundred rain gages representing a variety of precipitation regimes. The precipitation estimates were shown to exhibit much lower bias and better correlation with ground data than commonly used methods. Furthermore, the approach reliably reproduced the variability of precipitation over a range of temporal and spatial scales.