The structures of irradiation damage centres in diamond

Electron Paramagnetic Resonance (EPR) has been used to study radiation damage centres in type Ib diamonds which were either electron- or neutron irradiated. The isochronal annealing behaviour has been determined for a number of EPR centres up to 850 oC. The centres W11, W2, W13 and W14 as well as the interstitial centres R1 and R2 are produced under the irradiation beam and anneal out after about 450 oC. The centres W15, W29, R4/W6, W33, W37, W46 and W47 are observed following annealing at temperatures starting after about 400 oC. Of these centres only W33 and W15 are still growing in intensity after annealing at 850 oC - the temperature at which all the others are annealing out. The concentration measurements were determined for each annealing stage with the aid of a well-calibrated type Ib diamond as a standard. The central region or g=2 region of our spectra consists mainly of the a-line. This is a centre whose complex nature has been understood a bit better based on the annealing curves obtained in this work. The S1 or negative vacancy superimposes with the centre and hence made the concentration measurements of the cenre (S1) difficult. This was obtained indirectly using its 13C hyperfine lines. New work on four EPR centres namely W33, W37, W46 and W47 has been made. Their spin Hamiltonian parameters have been determined and have shown that their structural symmetries are very close to . Of the centres W33, W46 and W47 have effective spins S=1 whereas W37 has an unusually large effective spin S=2. From the annealing behaviour and the spin Hamiltonian parameters, their structural models have been proposed. The effective spin S=3/2 for the W11, W12, W13 and W14 EPR centres have been verified in this work by employing EPR 2 s Dm = transitions. The annealing curves for the centres suggest that the nitrogen may not be directly involved but donates electrons necessary for the formation of the centres. The W29 is an EPR centre that was found to have many similarities with R4/W6, the neutral divacancy centre in diamond. Their symmetries are both close to ; they have a large D-values and E-terms. In addition their g-tensors are isotropic and very close to free spin value. We have proposed that the W29 is a negative divacancy. The linewidths of the centres W29 and R4/W6 have been measured in the temperature range 6-300 K; large variations in this range were found i.e 2 - 7 G for W29 and 1.8 - 14 G for the R4/W6 centre. The spin lattice relaxation times T1 for the R4/W6 and the W29 centres in neutronirradiated type Ib diamond have been made using the CW saturation methods. The dominant relaxation mechanism at very low temperatures (below 50 K for R4/W6 and below 70 for W29 centre) is the direct process. The Orbach process is dominant in the higher temperature regions for both centres. The results suggest excited states 15.5 meV and 25.8 meV for W29 and R4/W6, respectively

Determinants of Completion Time of Projects Funded From Constituency Development Fund in Kenya: A Survey of Projects in Ainamoi Constituency

Projects are hardly completed as scheduled. The purpose of this study was to identify factors that influence projects completion time of CDF funded projects in Ainamoi Constituency, Kericho County. In the year 2012/13, a total of 74 community cent red projects were initiated to benefit the community. Out of these,only 22 (29.73%) had been completed as scheduled. This study intended to investigate factors that might have led to low completion rate with the intention of improving efficiency and effectiveness on projects management. The literature covered existing theoretical and empirical literature that relate CDF projects in relation to projects identification, scheduling, funding, good governance and rate of projects completion. There existed no comprehensive studies on the factors influencing completion rates of projects funded by the devolved CDF funds in Kenya. This was an attempt to provide a case study of factors influencing rate of project completion at the devolved level. The study adapted both qualitative and quantitative research approaches; and utilized descriptive survey to establish associations between variables. Questionnaires were used to collect data from the targeted population. The sampling frame used was the CDF projects management structure which constitutes 7 members representing each community center. Probability Proportion to Size (PPS) method was used to draw 5 respondents from the 14 community centers where every respondent had an equal selection opportunity. Data analysis resulted into a positive correlation between the dependent variable and independent variables. Community participation fully explained the rate of project completion. From the findings 70.26% of the projects had not been completed, thus only 29.73% have been completed. From the completed projects, 100% of the projects were not completed in time stipulated.. Funds should be disbursed as soon as the projects have been accepted.  CDF office should be able to adhere to the timely funding of projects. The study recommends a need for capacity building and recruitment of skilled PMC staff for effective governance of projects activities. Keywords: Projects Completion Time Factor

Socio-Economic Effects of Liberalization of Small Scale Tea Sector in Kenya: Evidence from Tea Farmers in Konoin District

Liberalization in Kenya started in 1990’s and continued ro date with far reaching effects on various sectors of Kenyan economy. The aim of this study was to investigate socio-economic effect of liberalization of small scale tea sector. The study sought to: Determine how liberalization has affected the living standard of the farmers, to investigate the impact of liberalization of tea sector on the competitiveness of small scale tea farmers and analyze the effect of liberalization on the performances of KTDA managed tea factories. A case study design was used in the study. The target population was 380 from which a sample of 38 was selected. In collecting data , a questionnaires was used. Descriptive statistics were computed. The findings revealed that Liberalization has exposed the smallholder and factories stiff competition due to entrants of new firms into the tea business. Factories have been ‘forced’ to streamline their operations to cope with completion. Effects of liberalization to farmers is mixed: On the positive farmers have been relieved of monopolistic tendencies of KTDA such as unilateral price determination and farmers have had a much bigger say in the management of tea factories. Negative effects include: Declining bonuses that farmers used to earn. Keywords: Liberalistaion, Tea secor, small-scale tea farmer

Working Capital Management and Corporate Financial Performance: Evidence from Panel Data Analysis of Selected Quoted Tea Companies in Kenya

This study aimed to provide empirical evidence about the impact of Working Capital Management on corporate financial Performance of tea firms in Kenya for the period 2005 to 2012. The study utilized panel data econometrics of 6 tea firms which are listed on Nairobi Securities Exchange. The results indicate that the cash conversion cycle, net trade cycle and inventory turnover in days are significantly affecting the financial performance of the firms. The tea firms are in general facing problems with their collection and payment policies. Similarly, the financial leverage, sales growth and firm size also have significant effect on the firm’s profitability. The study also concludes that tea firms in Kenya are following conservative working capital management policy and the firms are needed to concentrate and improve their collection and payment policy. The effective policies must be formulated for the individual components of working capital. In addition, efficient Management and financing of working capital (current assets and current liabilities) can increase the operating profitability of tea firms. For efficient working capital management, specialized persons in the fields of finance should be hired by the firms for expert advice on working capital management in the tea firms. Keywords: Working Capital Management, Cash Conversion Cycle, Net Trade Cycle, Average Collection Period, Average Payment Period, Tea sector, Fixed Effect Model

Impact of Corporate Governance on Effective Corporate Tax Rates Among Listed Firms in Kenya

Corporate tax is not only an important source of revenue to governments around the world but is also used to achieve a number of fiscal objectives. On the other hand, Corporation tax represents a significant expense to companies thereby impacting on major corporate decisions. Understanding factors that affect the effective corporate tax rates is therefore important not only to corporations but also to governments and other policy makers. Despite the well documented corporate tax leakages across the world, widening budget deficits and ballooning public debt in Kenya, limited studies have been conducted to investigate the impact of corporate governance on effective tax rates among the NSE listed firms. The purpose of this study was therefore to investigate the impact of board size, board independence, board gender diversity and corporate ownership structure on effective corporate tax rates among listed firms in Kenya between 2011 and 2017. The study employed longitudinal research design. A sample of 40 firms were purposively selected from the 67 listed firms in Kenya as at 31st December, 2017.Data was extracted from the published financial statements of the sampled firms. Data was analyzed with the aid of STATA software. The findings of the study show that board size, board independence and board gender diversity has a positive and significant effect on effective tax rates. On the other hand, ownership structure has a negative and significant effect on effective tax rates. The study therefore concludes that corporate governance has a significant impact on effective tax rates among listed firms in Kenya and recommends that policy makers, investors and corporate executives consider this fact when making their tax policies and decisions. Keywords: Corporate governance, Effective tax rate, listed firms, Kenya. DOI: 10.7176/RJFA/10-18-04 Publication date:September 30th 201

ESR study of DMTM(TCNQ)₂

The ESR g-value and susceptibility measurements for DMTM(TCNQ)₂ have been studied as a function of angle made by crystal with magnetic field and temperature. The angular dependence of g-value is fitted to g² = α+βcos2θ - γsin2θ for three orthogonal directions of crystal rotation. The principal g-values are close to those expected for TCNQ compounds: g₁ = 2.0034, g₂ = 2.0030, g₃ = 2.0024. The susceptibility as a function of temperature agrees with bulk susceptibility measurements except that the maximum position occurs at about 30 K. The results of Oostra et al. for bulk susceptibility showed a maximum at around 50 K. The phase transition reported by Visser et al. at 272 K is observed in the ESR data as a 15% decrease in susceptibility. The linewidth is remarkably anisotropic typical of TCNQ salts. The phase transition study is done for two orientations of the crystal with the magnet field. In one of the orientations the linewidth narrows from 0.15 to 0.11 gauss and in the other it narrows from 0.24 to 0.18 gauss. In the former case there is a growth of a second line due to the twinned stack; transformation twinning takes place at the phase transition. A small level-crossing interaction is inferred from the change in relative intensities of the lines near the crossover.Science, Faculty ofPhysics and Astronomy, Department ofGraduat

Nowcasting Hourly-Averaged Tilt Angles of Acceptance for Solar Collector Applications Using Machine Learning Models

Challenges in utilising fossil fuels for generating energy call for the adoption of renewable energy sources. This study focuses on modelling and nowcasting optimal tilt angle(s) of solar energy harnessing using historical time series data collected from one of South Africa’s radiometric stations, USAid Venda station in Limpopo Province. In the study, we compared random forest (RF), K-nearest neighbours (KNN), and long short-term memory (LSTM) in nowcasting of optimum tilt angle. Gradient boosting (GB) is used as the benchmark model to compare the model’s predictive accuracy. The performance measures of mean absolute error (MAE), mean square error (MSE), root mean square error (RMSE) and R2 were used, and the results showed LSTM to have the best performance in nowcasting optimum tilt angle compared to other models, followed by the RF and GB, whereas KNN was the worst-performing model

Relationship between ISO 9001 Certification and the Number of Non-Conformities Identified during System Audits in Selected Public Universities in Kenya

The quest for International Standard Organization (ISO) 9001 certification as an international quality tool has been embraced for process improvement and positive perception by customers. With ISO 9001 certification, an institution is anticipated to offer exemplary goods or services that meet client prerequisites, needs and expectations thus enhance organizational performance. As evident in previous studies, despite ISO 9001 certification, cases on wastages, missing student marks and time wastage were indicators of non-conformance. There was no clear evidence of past studies on the relationship between ISO 9001 certification and organizational performance with special interest on number of non-conformities identified during systems audit being a component of organizational performance. The purpose of the study was therefore to establish the relationship between ISO 9001 certification and the number of non-conformities identified during system audits in selected public Universities in Kenya. Explanatory research design was used in the study. The research targeted a population of 433 respondents from which a sample size of 205 respondents was selected using purposive and simple random sampling designs. A questionnaire was used to collect data. To answer the objectives of the study, simple linear regression analysis was performed. From the model, (R2 = .600) shows that ISO 9001 certification account for 60% variation in number of non-conformities identified during system audits. There was a positive significant relationship between ISO 9001 certification and number of non-conformities identified during system audits (β=0.611 and p <0.05). Therefore, a unit increase in ISO 9001 certification led to reduced number of non-conformities identified during system audits. The ISO 9001 certification had a significant influence on the number of non-conformities identified during system audits. For every adoption of the ISO 9001 certification in public universities the number of non-conformities identified during system audits reduced. The study concludes that ISO 9001 certification had a significant positive influence on the number of non-conformities identified during system audits. Thus, for every adoption of the ISO 9001 certification in public universities the number of non-conformities identified reduced. The study recommends that there is need for management of public universities through the department of quality management to address the non-conformities raised during system audits, need for university management to raise awareness on the importance of standardization and conformity assessment and to entrench the culture of quality in the Kenyan society by promoting practical usage of standards and development of quality related curricula in public universities