PhD Graduands

David Easter Syombua

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David Easter Syombua
Project Title
Targeted Genome Editing in Yam Using the CRISPR/Cas System
Degree Name
Doctor of Philosophy Degree in Biotechnology
Project Summary

 

Abstract:

Yam (Dioscorea spp.) is an economically important crop grown in the tropical and subtropical regions, producing tuberous roots that serve as a staple food, an income source, and an excellent source of various pharmaceutical precursors. Yam production is constrained by disease and pest infestations and a range of abiotic stresses. Genetic improvement can significantly mitigate these challenges, improve productivity, expand the yam markets, and increase economic gains. However, several intrinsic attributes of the crop have curtailed progress in yam breeding. Advanced genetic engineering such as genome editing by sequence-specific nucleases has emerged as complementary approaches to conventional breeding techniques. Mainly, the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein (CRISPR/Cas) system for genome editing has provided robust platforms for gene function analysis and crop improvement in the post-genomic era. Despite its significance, research towards improving the yam species remains under-represented compared to other staple tuber crops such as cassava and sweet potato. Thus, it is critical to explore avenues for increasing the genetic gains from this under-exploited crop. The present review focuses on the progress and prospects for applying the CRISPR/Cas technology for yam improvement. The study elaborates on the currently available CRISPR/Cas tool for yam genome engineering and explores the potential applications of this toolkit in mitigating the various challenges encountered in yam production and consumption. Furthermore, we have delved into the challenges associated with this technology and the improvements made to minimize these challenges. The insights presented herein provide a guide for yam improvement to increase genetic gains from this under-researched and under-utilized resource.

Ngaruiya Mary Njeri

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Ngaruiya Mary Njeri
Project Title
Psychosocial Heuristic Factors Of An Interactive Mobile Device For Geriatric Persons
Degree Name
Doctor of Philosophy Degree in Information Systems
Project Summary

Abstract: 

We aimed to identify and explore the priority psychosocial considerations for the gerontechnology design for Kenyan geriatrics. Our informants were a convenience sample of eight older adults (female = 4, age range 65 years to 78 years; and males = 4, age range 70 years to 78years) from an assisted living facility. We interviewed them on their regular mobile phone usage to better understand the factors affecting the usage of modern technology by older Kenyan persons. Thematic analysis of the data yielded two themes categorised as physical and psychosocial factors. Physical factors related to usability and user experience of older persons when using mobile phones. Psychosocial factors related to the emotional design experienced by older people when using mobile phones. These findings suggest a need to blend technology-centred and psychosocial factors for interactive mobile interfaces designed for developing country geriatrics.

Maingey Yvonne

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Maingey Yvonne
Project Title
A Multi-stakeholder Analysis of the Interaction Between water Availability and Access, Climate Change and Large-Scale infrastructural development in Lamu Kenya
Degree Name
Doctor of Philosophy Degree in Climate Change and Adaptation
Project Summary

Abstract:

Community adaptation to the negative impacts of climate change benefits from an analysis of both the trends in climate variables and people’s perception of climate change. This paper contends that members of the local community have observed changes in temperature and rainfall patterns and that these perceptions can be positively correlated with meteorological records. This is particularly useful for remote regions like Lamu whereby access to weather data is spatially and temporally challenged. Linear trend analysis is employed to describe the change in temperature and rainfall in Lamu using monthly data obtained from the Kenya Meteorological Department (KMD) for the period 1974–2014. To determine local perceptions and understanding of the trends, results from a household survey are presented. Significant warming trends have been observed in the study area over the period 1974–2014. This warming is attributed to a rise in maximum temperatures. In contrast to temperature, a clear picture of the rainfall trend has not emerged. Perceptions of the local community closely match the findings on temperature, with majority of the community identifying a rise in temperature over the same period. The findings suggest that the process of validating community perceptions of trends with historical meteorological data analysis can promote adaptation planning that is inclusive and responsive to local experiences

Kalele Dorcas Nzasu

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Kalele Dorcas Nzasu
Project Title
Climate-Smart Agriculture Options for Enhanced Resilience and Food Security: A Case Study of Yatta, Machakos County, Kenya
Degree Name
Doctor of Philosophy Degree in Climate Change and Adaptation
Project Summary

Abstract: 

In the recent decades, extreme weather events have increased in frequency, intensity and magnitude threatening and increasing the vulnerability of rural livelihoods particularly in the arid and semi-arid lands. This study explored climate change events, the extent of their impacts on farmers’ livelihoods, farmers’ adaptation strategies and the extent of the strategies on improving farmers' ability to manage the climate change impacts in the Yatta region, Kenya. The study adopted a multi-method approach that integrated qualitative and quantitative data sources. Quantitative data were obtained from 354 household interviews while qualitative data were obtained from 8 focus group discussions. The interview data were analyzed using descriptive and inferential statistics while the discussion data were analyzed using qualitative content analysis. The most experienced climate events were drought (90.7%), crop diseases (79.1%) and floods (33.30%). Livelihoods aspects greatly impacted by the climate change events were food shortage (87.29%), increased food prices (76.27%) and decreased availability of water (72.43%). Although farmers had adopted several on-farm adaptation strategies, the adoption levels remained low. Water management strategies (water conservation and water harvesting) recorded higher adoption rates of 62.71% and 53.95% respectively. The adoption of on-farm adaptation strategies had proved some potential to improve farmers’ ability to deal with the experienced climate change impacts. The regression model showed that farmers were likely to adopt crop and water management practices which they perceived had a higher probability of improving their ability to cope with climate change impacts. The occurrence of climate change events in the study area has affected agriculture productivity, food security and socioeconomic status of the households. Effective integration of potential adaptation strategies into smallholder farming systems calls for measures to address adoption and implementation barriers while ensuring alignment of policies, programs and institutional support systems.

Kaua Caxton Gitonga

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Kaua Caxton Gitonga
Project Title
The Role of Informal Microfinance Institutions in Resilience of Rural Livelihoods to Climate Variability; A Case Study of Tharaka Sub County, Kenya
Degree Name
Doctor of Philosophy Degree in Environmental Governance and Management
Project Summary

Abstract:

Informal microfinance is the delivery of financial services mainly to low income people outside the

regulation of the monetary authority. Despite their importance in development, no studies have

undertaken a detailed analysis of structures and performance

in informal microfinance institutions.

This study aims to analyze structures and performance in informal microfinance institutions in

Tharaka South Sub County. It uses descriptive study design and multi stage sampling design. Data

analysis was done using thematic, descriptive and Kendall’s tau

-b correlation analysis. An informal microfinance performance index was developed using inductive and hierarchical approaches. The study found the informal microfinance institutions are marked by high performance which

isdetermined by their structures. Moreover, the study deduced that informal microfinance is a key

policy strategy for poverty alleviation, financial inclusion, gender equity and resilience building since

participants mainly include women and other vulnerable groups.

Munyao Joshua Sila

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Munyao Joshua Sila
Project Title
Development of a Novel Voltammetric Method for Determination of Phenoxymethylpenicillin and Benzylpenicillin in Animal products and Pharmaceutical Samples
Degree Name
Doctor of Philosophy Degree in Chemistry
Project Summary

Abstract: 

Penicillin residues in animal food products like milk and meat has attracted great concern by health

regulatory agencies due to their negative effects. Therefore, there is urgent need for reliable, low cost,

fast and simple analytical tools/methods to monitor these penicillin residues in animal products before

distribution to consumers. In our previous work, we developed a square wave voltammetric method

based on bare glassy carbon electrode in SDS/ABS media to determine penicillin V and G. In this work,

we apply this voltammetric method to detect penicillin G at trace levels in cow milk and selected

pharmaceutical samples. Using cyclic voltammetry, the electrochemical behavior of penicillin G in both

cow milk and pharmaceutical samples were obtained. The oxidation potentials were 1.65V in both

samples, same as that obtained in SDS/ABS media. The diffusion coefficients were 1.494x10-6cm2/sec

in cow milk, 2.358x10-7cm2/sec in pharmaceutical sample and 1.392x10-6cm2/sec in SDS/ABS media.

The precision for the detection of the drug was also determined and recorded as relative standard

deviation (RSD). The RSD found were 4.22% and 5.51% for cow milk and pharmaceutical sample

respectively. The percent recoveries for accuracy determination were found to lie between 95.8% -

103.0% for the cow milk and 92.0% - 96.0% for the pharmaceutical samples. These recovery percentages

were within the recommended 90.0% - 110.0%. A detection limit of 2.5×103 ng/L penicillin G was

achieved in cow milk samples against a maximum residue limit of 4.0×103ng/L set by the European

Union. Overly, this method provides simple, precise and consistent results for detection and

quantification of penicillin G in cow milk, pharmaceuticals and possibly other environmental and clinical

samples.

Odumo Benjamin Okang’

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Odumo Benjamin Okang’
Project Title
Analysis and Multivariate Modelling of Heavy Metals and Associated Radiogenic Impact of Gold Mining in the Migori-Transmara Complex of South-western, Kenya
Degree Name
Doctor of Philosophy Degree in Physics
Project Summary

Abstract: Artisanal gold-mining (AGM) is one of the most important activities in the districts of Migori and Transmara (Kenya). Gold-mining, however, is known to release vast quantities of arsenic and metals (some of which are very toxic like As, Hg, Cd, or Pb), which poses a serious threat to not only miners but also to the ecosystem and local populations. We, herein, determine the concentrations of arsenic and some heavy metals in several sample types (i.e., ore, soil, river sediment, and mine tailing) collected from the districts of Migori and Transmara. We also employ lichens and mosses as pollution bioindicators. Geostatistical tools and canonical correlation analysis were used to identify the relevant factors that affected arsenic and metal concentrations in the analysed samples. The following concentration ranges were reported in topsoil: As (1–17,250 mg kg−1), Cd (0.01–15.10 mg kg−1), Cu (7–9,238 mg kg−1), Cr (1–214 mg kg−1), Ni (5–766 mg kg−1), Pb (3–1,149 mg kg−1), and Zn (22–1,271 mg kg−1). It was concluded that the ecosystem in both districts was highly polluted by heavy metals whereas the arsenic concentrations in topsoil were among the highest reported worldwide. The results of this study provide new evidence on the impact of AGM on the environment and may further contribute to the design of policy measures with the aim of reducing environmental and human health risks associated to AGM activities.

Mwangi Wanjiru Mary

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Mwangi Wanjiru Mary
Project Title
Designing an Innovation Systems approach towards enhanced farmer adoption of Climate Services within Dryland Agroecosystems in Kitui, Kenya.
Degree Name
Doctor of Philosophy Degree in Climate Change and Adaptation
Project Summary

Abstract: Community vulnerability to climate change can be conceptualized as an aggregate of three vulnerability components: exposure to climatic stress, sensitivity to climate stress and adaptive capacity. However, even within similar regions these vulnerability components are spatially differentiated necessitating the understanding of a regions vulnerability pattern before targeting adaptation assistance. This research sought to understand the differentiated vulnerability patterns of communities in Kitui County as well as the existing coping strategies to guide implementation of adaptation assistance. Indicator approach to vulnerability assessment and focus group discussions were used to understand the vulnerability pattern and coping strategies respectively. Results showed a differentiated vulnerability pattern with a west to east gradient across Kitui County. The pattern exhibited less vulnerability scores on the western and central parts and more vulnerability scores on the eastern and northern parts of the County. Existing coping strategies have become inadequate with increasing climate variability, severity and frequency of extreme climate events, which render the communities even more vulnerable. The patterns of vulnerability can guide appropriate targeting of adaptation assistance and in turn lead to improved climate change resilience and community livelihoods.

Tanui Florence Jerotich

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Tanui Florence Jerotich
Project Title
The Hydrogeology of the Lodwar Alluvial aquifer system, Turkana County, Kenya
Degree Name
Doctor of Philosophy in Geology
Project Summary

Rock geochemistry influences groundwater quality and the aquifer processes of an area. The geology of the study area comprises quartzo-feldspathic gneiss and biotite gneiss of the Precambrian basement, sedimentary Turkana Grits and Holocene sediments, Tertiary volcanics comprising nepheline phonolites and augite basalts, alluvial deposits along the banks of major streams and laggas (ephemeral streams), and Quaternary sands that blanket much of the area. This paper evaluates the influence of rock chemistry on groundwater quality in Lodwar area. Conventional petrography and geochemistry techniques involving measurement of major elements using X-ray fluorescence (XRF) and trace elements using and X-ray diffraction (XRD) in 69 rock samples to evaluate their mineralogical compositions. The major rock-forming in rocks of the study area include pyroxenes, olivine, kaolinite, siderite, fluorite calcite and dolomite. These minerals release major ions to groundwater through weathering, leaching, oxidation, dissolution and precipitation, and ion exchange reactions during rock-water interactions. The rocks in study area have generally low amounts of Na and K with modal values < 2.00 wt%, suggesting other sources of Na+ and K+ ions in groundwater. In contrast, Ca, Mg, Al, Fe and Mn are released to groundwater from rocks, as shown by high modal compositions of individual elements and associated oxides. The higher concentrations of Na+, K+, Ca2+ and Mg2+ in the groundwater of the Turkana Grit aquifer relative to the grit rock samples suggest a long history of dissolution and recycling of the groundwater. The ratio SiO2:Al2O3 was found to be greater than 8.0 implying a high degree of maturity of the grits. The results presented by this study show that geological factors and processes have location-specific influence on groundwater quality and should be considered in aquifer water quality studies and supply development across Africa’s vast ASAL regions.

Ngure Mary Wangui

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Ngure Mary Wangui
Project Title
Enhancing food Security through Crop and livelihood diversification among Kimandi-Wanyaga Community in Muranga
Degree Name
Doctor of Philosophy Degree in Climate Change and Adaptation
Project Summary

Abstract: Climate change poses significant risks to food security globally with predictions of 10-20 % decline in rain-fed crop yields by 2050. Sub-Saharan Africa remains highly susceptible to food shortage since over 95 % of the region’s total cropland is rain-fed. Kenya’s over reliance on rain-fed agriculture predisposes the country to climate-induced food insecurity. Murang’a County in Kenya is experiencing climate change challenges manifested in prolonged droughts and floods. The consequences,are failed cropping seasons, soil erosion, landslides, altered crop suitability and a resurgence of human, livestock, crop pests,and diseases,culminating into food insecurity. This study was conducted with Kimandi-Wanyaga community in the Gatanga Sub-County in Murang’a County, Kenya. Residents are smallholder subsistence rain-fed farmers. The study explored the potential of up-scaling crop diversification under the Plantation Establishment and Livelihood Improvement Scheme (PELIS) for food security vis-à-vis climate change. The community’s climate change coping strategies were explored to account for the need to up-scale crop diversification under PELIS. A mixed methods research design was applied whereby a systematic sampling method was used to select 281 household-heads. Three key informants were purposively selected and primary data were collected through a household survey, in-depth key stakeholder interviews, focus group discussions and on-farm trials. Quantitative data were analysed using descriptive and inferential statistics while qualitative data were analysed using thematic and content analysis. The study established that 92.9 % of the community perceived climate change and its impacts. They had adopted a combination of coping strategies most of which,were found to be informed by short-term survival and hence,considered inadequate for long-term adaptation. The PELIS approach had been piloted in Murang’a County and was found to be a promising strategy for crop diversification and food security among forest-adjacent communities. However, only 11 % of the studied community participated in the scheme. Therefore, the study endeavoured to work with the community to promote cultivation of traditional vegetables under PELIS for crop diversification and food security in the face of climate change.The PELIS beneficiaries who adopted cultivation of Black nightshade, Amaranths and Cowpeas managed to produce enough for household consumption and sale of surplus for income. The PELIS,therefore, possesses the co-benefits of climate change adaptation through crop diversification for food security and climate change mitigation through afforestation for carbon sequestration.