PhD Graduands

Kumunga Eunice Muthoni

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Kumunga Eunice Muthoni
Project Title
Assessment of effects of sub-catchment governance on management of water resources: A case of Rwamuthambi Sub-catchment, Kenya
Degree Name
Doctor of Philosophy Degree in Environmental Governance and Management
Project Summary

Abstract: Many studies conducted in Kenya regarding water resource governance have focused on the mandate of Water Resource Users Associations (WRUAs) with less attention being accorded to their effectiveness in conservation of wetlands. This study assessed the effectiveness of WRUA committees, and challenges faced in conservation of Rwamuthambi Sub-catchment. The study employed exploratory descriptive research design. Data was collected through questionnaires, semi-structured interviews, observations and review of secondary data. Chi square and descriptive statistics was used to analyze the data. The survey results revealed that only 15% of WRUA committee understood water resources management while 35% were aware of relevant legislations. Factors of wetland degradation showed significant association with existence of WRUA (χ2 (4, N=180) = 20.46, p< .01) where (χ2- chi square (degrees of freedom, N = sample size) = chi-square statistic value, p = p value), although WRUA contributions were perceived differently per agro-ecological zone (χ2 (8, N=147) = 15.51, p>.05). Challenges unearthed were inadequate financial and human resources, lack of understanding, ineffective collaborative governance, poor support from county government and private ownership of riparian land reserve. There is need for WRUAs to embrace collaborative governance for effective conservation of wetlands. Integration of sub catchment management plan with county land use plans and policy review is also required.

 

Wanyoike John Ngaii

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Wanyoike John Ngaii
Project Title
Construction of a Sub-Class of Balanced Asymmetrical factorial Designs
Degree Name
Doctor of Philosophy in Mathematical Statistics
Project Summary

Abstract: 

With reference to a confounded asymmetrical design for an Image removed. factorial experiment, a very powerful tool for expressing factorial arrangements in a compact and convenient form has been given and also used in this paper in order to derive efficiency factors of the said designs. The concept of orthogonal factorial structure and balance has been explained and a characterization  for balance with orthogonal factorial structure has been given. An expression is derived for efficiency factors of linear contrasts. This expression involves Kronecker product matrices. An example is also given to show how efficiency factors of confounded asymmetrical factorial designs are calculated.

Keywords and phrases:

efficiency factors, Kronecker product matrices, linear contrasts, confounded asymmetrical factorial design, orthogonal factorial structure, balance.

Ombui Edward Osoro

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Ombui Edward Osoro
Project Title
A Model of Classifying Hate Speech Text from Social Media Leveraging on Psycho-social Features and Machine Learning
Degree Name
Doctor of Philosophy in Computer Science
Project Summary

Abstract: Presidential campaign periods are a major trigger event for hate speech on social media in almost every country. A systematic review of previous studies indicates inadequate publicly available annotated datasets and hardly any evidence of theoretical underpinning for the annotation schemes used for hate speech identification. This situation stifles the development of empirically useful data for research, especially in supervised machine learning. This paper describes the methodology that was used to develop a multidimensional hate speech framework based on the duplex theory of hate [1] components that include distance, passion, commitment to hate, and hate as a story. Subsequently, an annotation scheme based on the framework was used to annotate a random sample of ~51k tweets from ~400k tweets that were collected during the August and October 2017 presidential campaign period in Kenya. This resulted in a goldstandard codeswitched dataset that could be used for comparative and empirical studies in supervised machine learning. The resulting classifiers trained on this dataset could be used to provide real-time monitoring of hate speech spikes on social media and inform data-driven decision-making by relevant security agencies in government.

Oyoo David Odhiambo

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Oyoo David Odhiambo
Project Title
Ratio Estimation of Finite Population Total in Stratified Random Sampling Under Non Response
Degree Name
Doctor of Philosophy in Mathematical Statistics
Project Summary

Abstract: 

An unbiased ratio-type estimator has been considered by Oyoo et al. [8] in estimating finite population total under non-response in stratified random sampling. In their paper, Oyoo et al. [8] assumes that variation in the ratio Image removed. Image removed. is much higher than variation in the response variable, Y and in the auxiliary variable, X and therefore, while obtaining the expression for the variance, variations in Y and X are considered negligible. In this paper, however, we consider variations in RY and X and use the result by Hartley and Ross [3] and Goodman and Hartley [9] to obtain the expression for variance the estimator by Oyoo et al. [8]. We examine performance of this estimator using simulated data and the results show that this estimator performs better than the usual (biased) ratio estimator constructed in simple random sampling without replacement (SRSWOR) and under stratified random sampling.

Keywords and phrases:

unbiased ratio estimator, mean square error (MSE), non-response.

 

Osoro Enock Moseti

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Osoro Enock Moseti
Project Title
Assessment of Selected Polybrominated diphenyl Ethers in Nairobi River Drainage Basin Kenya and Study of their Photocatalytic degradation
Degree Name
Doctor of Philosophy in Chemistry
Project Summary

Abstract:

Air samples were collected from three urban and one rural sites in Kenya with the aim of establishing pollution levels of Polybrominated Diphenyl Ethers. Forty-eight air Samples were collected by passive air sampling, Soxhlet extracted and analysed for brominated diphenyl ethers using gas chromatography coupled with mass spectrometer. The mean concentration of polybrominated diphenyl ethers residue in air ranged from ≤0.9 to 152.72±3.19 pgm−3. The predominant congener was 2,2′,4,4′-tetra-bromodiphenyl ether with mean concentration range of 1.94±0.03 to 152.72±3.19 pgm−3 followed by 2,2′,4,4′,5-penta- bromodiphenyl ether with mean concentration range of 1.32±0.06 to 66.83±1.19 pgm−3. Seasonal variations of the pollutants showed a high level of Polybrominated Diphenyl Ethers in hot dry season in range of 1.94±0.03 to 152.72±3.19 pgm−3. Air samples from Dandora and Industrial area both from urban location recorded high concentrations of the analysed polybrominated diphenyl ethers compared with the air samples from the rural location.

Aduma Mildred Mwigali

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Aduma Mildred Mwigali
Project Title
Modeling of the impact of Climate Change on Herbivores Distribution in the Savanna Ecosystems, A Case Study of Amboseli Ecosystem, Kajiado County, Kenya
Degree Name
Doctor of Philosophy Degree in Climate Change and Adaptation
Project Summary

Abstract: 

This study investigated spatial and temporal trends of rainfall and temperature in the Amboseli ecosystem of

Kenya. The analysis were based on historical Climate Hazards group InfraRed Precipitation with Station (CHIRPs) and Climate Hazards group InfraRed Temperature with Station (CHIRTs) data for the period 1960-2014 and the period 2006-2100 for the projections. This data was used due to limitations in the observed station data. Projections of rainfall and temperature were based on Regional Climate Models (RCM) from Coordinated Regional Downscaling Experiment (CORDEX) over the Amboseli ecosystem. The long-term annual and seasonal trends of rainfall and temperature were analyzed via Mann– Kendall’s statistical test and linear trend analysis. The annual and seasonal rainfall declined slightly between 1960 and 2014 though not significant. However the temperatures increased more in the annual minimum (1.23 °C) compared to the annual maximum (0.79 °C). The maximum temperatures for the October-November-December (OND) season had highest increases of 0.88 °C while the March-April-May (MAM) season showed an increase of 0.69 °C. The highest increase in minimum temperatures of 1.35 °C was recorded for the June-July-August-September season (JJAS), while the least increase was in MAM (1.04°C). Projected rainfall based on Representative Concentration Pathways (RCPs) for the periods 2006-2100 varied with RCP 2.6 showing a decline for the four seasons. RCP 4.5 and 8.5 project marginal increase in annual and OND with declines in the MAM and JJAS. Projected maximum and minimum temperature for RCP 2.6 indicate increments of less than 1 °C while for RCP 4.5 the maximum range is between 0.57 °C and 1.85 °Cand minimum is between 0.51 °C to 1.98 °C. RCP 8.5 projected maximum increase are the highest between 1.11°C and 4.34 °C and minimum is between 1.34 °C and 5.26 °C based on period – 2030, 2050 and 2070. The increase of temperatures and changes in rainfall can have large impacts on the resources in the savanna dry lands of East Africa especially on its livestock, agriculture, wildlife and pastoral and agro-pastoral communities.

Index Terms— Climate change, dry lands, mitigation,Representative Concentration Pathways, temperature and

rainfall

Ngugi Ceciliah Njoki

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Ngugi Ceciliah Njoki
Project Title
Characterization and evaluation of Entomopathogenic Nematodes for the management of tomato leafminer, Tuta Aboluta
Degree Name
Doctor of Philosophy in Microbiology
Project Summary

Abstract

Entomopathogenic nematodes (EPNs) are worldwide soil-dwelling insect parasitic nematodes. They are potential pest bio-control agents a key component of Integrated Pest Management (IPM) programs. This study aimed to characterize and evaluate the pathogenicity of an EPN isolate from Kenya. The nematode was isolated from soils using insect bait technique and both morphological and molecular identification was performed. Efficacy of the isolate was evaluated against Tomato leafminer larvae (Tuta absoluta Meyrick.) using dose-based treatments of 0-control, 100, 150, 200, and 250 infective juveniles (IJs/ml). Morphological analysis revealed body length (L) of 835(659-987) µm and 1781 (1297-2097) µm from fresh IJs and males respectively. Males lacked a mucron. The isolate was characterized by the partial sequence length of 877 bp of the ITS region. Blastn results indicated the EPN isolate had a similarity match of 81-92% with Afro-tropical Steinernema species. It matched with Steinernema sp. (AY230186.1) from Kenya at 92% and Sri Lanka (AY230184.1). Phylogenetic analysis placed the isolate together with Steinernema sp. (AY230186.1) and (AY230184.1) with a bootstrap value of 100%. Maximum mean larval mortality (80%; 96%) was achieved 24 and 48 h post-treatment at concentration 150 IJs/ml. All nematode concentrations achieved over 50% mean mortality after 24 h period. There was a significant difference (P = 0.001) between doses 150 and 200 IJs/ml. From the study, it was concluded that the nematode isolate was Steinernema sp now referred to as Steinernema sp. Kalro (Genebank Accession MW151701). The EPN has the potential for development as a biological control agent against T. absoluta.

Odumo Benjamin Okang’

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Project Title
Analysis and Multivarianate Modeling of Heavy Metals and Associated Radiogenic Impact of Gold Mining in the Migori- Transmara Complex of Southwestern, Kenya