152 research outputs found
Genetic diversity and fungicide sensitivity of Rhizoctonia solani associated with soybean seedling disease
No full textRhizoctonia solani, a ubiquitous and genetically diverse fungus, is an important seedling pathogen of soybean in North America. With the dearth of commercial soybean varieties marketed for resistance to members of this species, seed treatment fungicides have become increasingly important as a management option. However, our knowledge of the groups associated with soybean seedlings, the genetic structure of the pathogenic groups, as well as their potential for adaptation to fungicide seed treatments, is very limited. To bridge this knowledge gap, we characterized, using conventional and molecular techniques, Rhizoctonia isolates collected from farmers’ fields in the U.S. and in Canada to identify the predominant and most aggressive groups. Three taxonomic groups were identified: R. solani, R. zeae, and the binucleate Rhizoctonia. The R. solani isolates comprised members of anastomosis groups (AG) 2-2IIIB, 3PT, 4 HGI, 4 HGIII, 7, and 11. Isolates of AG-2-2IIIB were the most frequently recovered and the most aggressive on soybean and corn. Using single nucleotide polymorphism markers identified from genotyping-by-sequencing approach, the genetic structure of the populations of AG-2-2IIIB from Illinois, Ohio, and Ontario was assessed for clues about the pathogen’s reproductive biology and to determine if the pattern of genetic variation within populations is consistent with that of a pathogen that is at a high risk of adapting to repeated fungicide applications. While the Illinois population was mostly clonal, the genetic structure of the AG-2-2IIIB populations from Ontario and Ohio revealed a mixed reproductive mode, suggesting the need for caution when applying fungicides. Our results also presented genotype flow as a predominant force shaping the population genetic structure of this AG. To determine if R. solani populations are becoming less sensitive to the fungicide classes commonly used to manage seedling disease, a fungicide resistance monitoring program was initiated to compare the sensitivities of historical isolates with no prior fungicide exposure to the sensitivities of isolates that have been exposed to fungicides over time. Results from fungicide sensitivity assays showed that sensitivity to the fungicide classes tested has decreased in comparison to the baseline R. solani population, but control of seedling disease caused by R. solani was still achieved regardless of in vitro sensitivity.
The appendix chapter of this dissertation presents the results of a separate study evaluating the potential of a three-gene pyramid for improved soybean aphid management . From greenhouse studies evaluating the differential reaction of soybean isolines with different combinations of aphid resistance genes, Rag1, Rag2, and Rag3 to four soybean aphid biotypes, the Rag1/2/3 pyramid was found to be the most effective.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2018-05-01The student, Olutoyosi Ajayi, accepted the attached license on 2016-04-15 at 13:35.The student, Olutoyosi Ajayi, submitted this Dissertation for approval on 2016-04-15 at 13:50.This Dissertation was approved for publication on 2016-04-20 at 15:05.DSpace SAF Submission Ingestion Package generated from Vireo submission #9247 on 2016-07-07 at 14:16:48Made available in DSpace on 2016-07-07T21:14:47Z (GMT). No. of bitstreams: 3
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Employee Performance Among Selected Tertiary Institutions: Evidence from Intrinsic Reward System
No full textThe study examined employee performance among selected tertiary institutions: evidence from intrinsic reward system. A descriptive survey research design was adopted for the study. The population of the study comprised the selected universities staff in Ado-Ekiti. A total of 360 structured questionnaires were administered to elicit information from the target respondents. Data gathered were analyzed using hierarchical regression models. The result showed that consultative participation significantly affect institutional stability as it was significant on institutional stability (t=-1.303, t=5.429, t=2.108, t=6.365 and t=3.078, p<0.05) Thus, in conclusion, it was shown that all the constructs of the explanatory variable were significantly and positively related to employee performance of selected university in Ado-Ekiti. Keywords: Intrinsic Reward, Employee, Performance. DOI: 10.7176/JESD/10-4-1
Board Effectiveness in Small Nonprofits: A Case Study of a Nonprofit with Three-Person Board
No full textSmall nonprofits face unique challenges that often make “best practices” and traditional governance models unrealistic for them to adopt. The governance practices adopted by most small nonprofits, in order to meet their unique challenges, therefore often fall outside of generally accepted best practice governance models. How then, does a small nonprofit judge or measure board effectiveness? The research undertaken for this study, and the study findings themselves, suggest there is a gap between accepted “best practices”, and actual practices in small nonprofits, and that the criteria for judging board effectiveness in small nonprofits also differs. The study concludes by offering recommendations on how small nonprofits with unique challenges and unconventional board models can enhance their governance practices and effectiveness
Coronavirus (Covid-19) Pandemic and Performance of Small and Medium Scale Enterprises in Akure Metropolis, Ondo State, Nigeria
No full textThis study examined the effects of coronavirus on the performance of Small and Scale Enterprises (SMEs) in Akure North and Akure South in Ondo state, Nigeria. The specific objectives are to evaluate the direct impact of the coronavirus pandemic on the structure and system of SMEs; examine the downstream effects of the lockdown order due to coronavirus on SMEs; investigate the effect of social distancing and hand washing on the performance of small and medium scale enterprises. This research adopted a descriptive research design; the purposive sampling method was used to select the SMEs, with the sampling size of the study being 284 respondents in both Akure North and Akure South. Data was collected using a structured questionnaire and analyzed using simple linear regression. The study found that direct impact, downstream effect, and social distancing had significant effects on the performance of SMEs. The study thus concludes that the coronavirus influences the performance of SMEs. It was recommended that SMEs emphasise more resources towards building customer protection guides and personal selling to improve the enterprise’s profit level.
 
The total synthesis of mycothiol and new inhibitors of carbohydrate processing enzymes
No full textThe work described in this dissertation covers a wide range of disciplines within organic chemistry, with the common goal of obtaining more information about various carbohydrate-processing enzymes. Carbohydrate-processing enzymes are garnering an increasing amount of attention relative to their more well-studied protein-processing counterparts, as they are ubiquitous and implicated in various regulatory, signaling and metabolic processes in eukaryotic cells. Chapter 1 involves the synthesis of anomeric phosphothioates as possible O-GlcNAc transferase inhibitors, and a mechanistic study on the anomeric Pudovik rearrangement of thiophosphites to thiophosphonates is described. Chapter 2 is an account of the development of a facile method for functionalizing 2-methyl thiazoline rings, and several selective GlcNAc-thiazoline-based O-GlcNAcase inhibitors were synthesized by this method. Chapter 3 details the 16-step total synthesis of the M. tuberculosis antioxidant carbohydrate mycothiol by a new intramolecular glycosylation method. The method is amenable to glycosylations of 2-deoxy-2-aminoglyosides, a unique aspect among such reactions. The efficiency of the synthetic route to mycothiol makes it attractive as a template from which to design analogs as potential inhibitors of enzymes involved in the biosynthesis of mycothiol. An apparently unprecedented 1,9-hydride shift is also described in the third chapter. Chapter 4 describes a tripartate prolonged-release drug delivery system, in which the drug of interest (ethynyl estradiol in this study) is coupled, through a variable linker, to another carrier drug with a long half-life and a relatively high inhibitory concentration. The effect of steric bulk on the in vitro release of ethynyl estradiol was evaluated, showing a direct relationship between steric bulk around the ester linkage and ethynyl estradiol release time. In vivo data from pigs also seemed to point to an increase in drug bioavailability with the 3-part system. Finally, chapter 5 describes early efforts to synthesize boronic acid analogs of folic acid and antifolates.Ph.D.Includes abstractVitaIncludes bibliographical referencesby Kehinde Ajay
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Numerical simulation and interpretation of neutron-induced gamma-ray spectroscopy measurements
No full textNeutron-induced spectroscopy measurements are commonly used to quantify in-situ elemental and mineral compositions of rocks from the processing of measured gamma-ray energy spectra. However, geometrical effects on measured spectroscopy logs, such as thin beds, dipping beds, and deviated well trajectories, can cause shoulder-bed averaging that compromises the assessment of true layer elemental and mineral compositions. Traditional methods of interpreting neutron-induced gamma-ray spectroscopy measurements typically neglect such shoulder-bed averaging effects in the estimation of elemental and mineral compositions. Monte Carlo methods accurately reproduce borehole and formation geometrical effects on spectroscopy measurements but are extremely time consuming and impractical for use in routine interpretation. Reliable measurement interpretation must therefore begin with the development of a fast and accurate forward simulation method that explicitly incorporates measurement physics, borehole, tool, and formation geometry.
This dissertation introduces a new algorithm to rapidly simulate elemental and mineral compositions from neutron induced spectroscopy measurements. The algorithm utilizes neutron-gamma ray spatial sensitivity functions to account for environmental and three-dimensional (3D) effects of formation porosity, fluids, dipping beds, thin beds, and arbitrary well trajectories. Simulations assume a logging-while-drilling (LWD) spectroscopy tool furbished with a 14-MeV pulsed-neutron source in the interpretation of gamma ray spectra obtained from high energy inelastic neutron scattering and thermal neutron capture. Results obtained with the rapid simulation method are benchmarked against rigorous Monte Carlo spectroscopy calculations for synthetic conventional and unconventional thinly-bedded reservoirs penetrated by vertical and high angle/horizontal (HA/HZ) wells. The fast simulation method yields calculations in approximately 1e6 the time required by Monte Carlo simulations, with an average difference below 5% between Monte Carlo and fast simulated logs.
An inversion-based interpretation method is next introduced to accurately evaluate mineral concentrations from measured spectroscopy elemental logs based on the analytical relationship between elements and minerals through their chemical formulas. In the presence of geometrical effects, spectroscopy elemental and mineral logs are corrected for shoulder-bed averaging by the inclusion of spatial sensitivity maps, which account for such geometrical effects, in the inversion-based interpretation. Calculations are performed with both inelastic and capture gamma-ray spectroscopy measurements which arise from high-energy inelastic neutron scattering and low-energy thermal neutron capture, respectively. This strategy provides two sets of data that can ascertain chemical elements or minerals detectable in only one measurement mode and also independently validates estimated elemental and mineral compositions. In laminated formations, where layer thicknesses are below the vertical resolution of the tool, it is impossible to quantify layer properties with inversion methods. An additional interpretation method based on a new spectroscopy mixing law is therefore developed to estimate elemental and mineral compositions within individual laminae.
The new inversion-based interpretation methods are successfully implemented in diverse synthetic and field cases with varying lithology types and well trajectories including vertical and HA/HZ wells. Results show that the developed methods reduce shoulder-bed averaging effects on measured spectroscopy logs by as much as 0.4 yield fraction, 0.17 weight fraction, and 0.34 mineral volume fraction. Finally, a new spectroscopy-based petrophysical interpretation method is introduced that utilizes estimated mineralogy to overcome the common assumption of homogeneous lithology in measured porosity logs, thereby improving the estimation of porosity and water saturation. Inclusion of shoulder-bed averaging effects on spectroscopy mineral logs also increases the accuracy of spectroscopy-based petrophysical interpretation.Petroleum and Geosystems Engineerin
Influence of Gender and Age on Organisational Commitment Among Civil Servants in South-West, Nigeria
No full textThe paper examines the influence of demographic variables of gender and age on the commitment of employees in the Nigerian civil service. Data for the study were obtained through 567 valid questionnaire containing information on gender and age, and work related issues from civil servants purposively selected from six states in the South-West, Nigeria. The Analysis of Variance (ANOVA) was used for the data. Findings indicate that the age groups of the civil servants are critical to their commitment in the organisation. The findings indicated that commitments in the civil service organisation are higher for the younger and older civil servants than those within the middle age groups. The government is provided with information on what can be done to enhance employees’ commitment to the Nigerian civil service through adequate remuneration and motivation for the different age groups. The paper concludes that civil servants should be motivated according to the needs of the age groups in order to enhance their commitment levels
Gender Analysis of Social Capital Status of Entrepreneurs in Akure Metropolis, Ondo State
No full textThis study examined the social capital status of male and female entrepreneurs in Akure metropolis, Ondo State, Nigeria. Social capital has become a pivotal tool for poverty alleviation in Nigeria, which is due to the fact that it is the coming together of people with common interest, values, norms, cultural practices and with a goal to meet certain basic needs, enjoy inherent benefits in participating or joining associations to achieve pre-determined goals and objectives which in turn is expected to improve the living standard of individuals, enterprises, and the economy in general. The study administered structured questionnaire to collect data from the respondents. Multi-stage sampling technique was used in selecting 201 micro scale entrepreneurs from six male and female dominated enterprises (barbing, printing press, mechanics, catering, hairdressing, tailoring) and the data were analysed using descriptive statistics. The result of the descriptive characteristics revealed that respondents were in one association or the other which include: occupational groups (39.22%), cooperative society (28.45%), trader association (13.79%), religious group (6.89%) and family group (7.76%). In the same vein, the social capital profile of both male and female entrepreneurs were, meeting index (100%, 96%), homogeneity index (39.26%, 44.77%), membership index (36.74%, 43.36%), labour index (25.18%, 29.38%) and trust index (24.70%, 24.70%) respectively. The study concluded that entrepreneurs (male and female) in Akure metropolis did not take advantage of their social capital and as such this has placed a bottleneck on their inability to maximize their business performance. The study recommends that entrepreneurs should appreciate gender balance in entrepreneurship, recognise their social capital status, and be actively involved in groups and deploy proper education and enlightenment on their social capital benefits through their various groups.
 
Isolation of Affimers against biomarkers of Clostridium difficile infection for use as diagnostic tools
No full textClostridium difficile is one of the leading causal agents of hospital acquired infection and antibiotic-associated diarrhoea. The treatment and control of Clostridium difficile infection (CDI) is critically dependent on accurate laboratory diagnosis. However, current diagnostic methods have limitations including cost, potential over-sensitivity, lack of detection of toxin protein associated with nucleic acid amplification techniques, and long turnaround time for toxigenic cultures. Detection of toxins in faecal samples of patients suffering from CDI is a highly significant and necessary criterion for the diagnosis of CDI. Rapid enzyme immunoassays are used for toxin detection and can be completed in less than an hour, however, their low sensitivities make them unacceptable for use as a stand-alone test. To date, no one-step diagnostic that is low cost, sensitive and specific is available for CDI diagnosis. Leeds has developed a non-antibody binding protein called Affimer type II (Affimer). From phage display libraries, Affimer binders against >350 targets have been identified.
This thesis investigates the isolation of Affimers against biomarkers of Clostridium difficile infection for use as diagnostic tools. Phage display screening yielded high affinity Affimers against the three well-established biomarkers of CDI (toxin A, toxin B and glutamate dehydrogenase). Characterisation of the Affimer binders show that they bind to their target with low nanomolar affinity. Through sandwich phage ELISA, two toxin B Affimers have been established for use as a pair in sandwich assay format. This thesis has also explored the ability of Affimers to function as novel reagents for the potential development of a point-of-care diagnostic tool for C. difficile infection. The most exciting result include the development of a toxin B hybrid assay which shows improved sensitivity and specificity by switching one of the molecular recognition elements of a clinically used C. difficile detection kit from antibodies to Affimers
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