Papers by charles ochieng
National Commission for Science, Technology and Innovation (NACOSTI) Kenya Medical Research Insti... more National Commission for Science, Technology and Innovation (NACOSTI) Kenya Medical Research Institute (KEMRI) Mr. Simon Mathenge
The main purpose of this study was to examine a polytomous IRT-based linking procedure that adjus... more The main purpose of this study was to examine a polytomous IRT-based linking procedure that adjusts for rater variations. Test scores from two administrations of a statewide reading assessment were used. An anchor set of Year 1 students’ constructed responses were rescored by Year 2 raters. To adjust for year-to-year rater variation in IRT linking, a two-step approach was used. First, the Year 1 item parameters for the constructed response items were reestimated using the ratings assigned by the Year 2 raters. Through this recalibration process, the Year 1 item parameters for the constructed response items were adjusted for rater variation. Second, the Stocking-Lord equating method was used to place the Year 2 form on the Year 1 scale using all the common items between forms. This method was compared with two alternative methods: traditional IRT linking study that links the test forms using a) all the common items without the rater adjustment and b) the common selected response item...
The study determined the effects of ICT personnel training on malware control and security implem... more The study determined the effects of ICT personnel training on malware control and security implementation within public Universities in Kenyan. Malware infestation and unauthorized practices in information systems have been in the rise in Kenyan universities, thereby compromising integrity of critical information therein. studies indicate that malware causes breaches of data integrity and availability. While universities and other institutions conduct employee security training in order to lessen the impact of such information systems' security breaches, the effectiveness of such trainings with respect to security elements have not been established. The desire to assess the real effects of such training on the intended purpose has led to a focused attention in ICT security Training and its effects on malware control and implementation of security policies within public Universities in Kenyan. The study objectives have been; to investigate the effects of ICT personnel training on...
Despite continued investment in information technology security systems within universities in Ke... more Despite continued investment in information technology security systems within universities in Kenya, there has been increased frequency of information systems' security breaches. Studies indicate that information technology security management could be enhanced by focusing resources on specific elements. However, continued breaches within the universities is attributed to haphazard investment on security controls without focus on specific elements. The objective of this study was to identify the major elements and investigate their application in management of information security within universities in Kenya. Secondary publications were reviewed to ascertain the major information technology security elements and questionnaire based survey conducted to seek the extent of application of the elements within the universities. 10% of universities was sampled randomly. Further, purposive sampling was used to collect data targeting IT personnel. Data was analysed using SPSS, where me...
Many measures found in educational research are ordered categorical response variables that are e... more Many measures found in educational research are ordered categorical response variables that are empirical realizations of an underlying normally distributed variate. These ordered categorical variables are commonly referred to as Likert or rating scale data. Regression models are commonly fit using these ordered categorical variables as the criterion (i.e., dependent or response) variable; however, a common recommendation in the methodological literature is that researchers make use of ordinal logistic regression when they have these ordered categorical response variables. An advantage of ordinal logistic regression is that it provides a pseudo R-squared measure of fit so that researchers may find this regression model familiar and hence appealing. This study investigated how the pseudo R-squared fit statistic in ordinal logistic regression operates under a variety of conditions over a varying number of Likert scale points and skewness of the Likert data. The study also demonstrates how the regular ordinary least-squares R-squared statistic operates in the same conditions as the Likert data. The pseudo R-squared fit statistic operates well in a majority of ccmditions, and so it is recommended that educational researchers begin to explore the use of ordinal logistic regression in their modeling practice with ordered categorical data. Using the pseudo R-squared index will ease the transition to ordinal logistic regression because it provides a sense of familiarity to the researcher. (Contains 4 figures, 11 tables, and 6 references.) (Author/SLD) Reproductions supplied by EDRS are the best that can be made from the original document.
This study is an analysis of pedagogical practice and support of English language student teacher... more This study is an analysis of pedagogical practice and support of English language student teachers during a practicum (teaching practice) in Kenya with a view to discerning what they learnt and the issues that influenced such learning. The study was conducted against a background of calls for research that could provide information for reform of teacher education in general and English language teacher education (ELTE) in particular. The practicum is recognised as an important aspect of all professional learning and is part of most teacher education programmes all over the world. Yet, my literature review revealed that very little research exists in this area, more so in ELTE. Of the previous studies on teaching practice (TP), very few are from developing countries and certainly none (that I know of) in Kenya. This was an interpretive qualitative case study involving seventeen participants - six student teachers, six teacher educators and five cooperating teachers. Data was generate...
Fitoterapia, Jan 2, 2017
Gymnosporia heterophylla (Celastraceae) is an African medicinal plants used to treat painful and ... more Gymnosporia heterophylla (Celastraceae) is an African medicinal plants used to treat painful and inflammatory diseases with partial scientific validation. Solvent extractions followed by repeated chromatographic purification of the G. heterophylla aerial parts led to the isolation of one new β-dihydroagarofuran sesquiterpene alkaloid (1), and two triterpenes (2-3). In addition, eight known compounds including one β-dihydroagarofuran sesquiterpene alkaloid (4), and six triterpenes (5-10) were isolated. All structures were determined through extensive analysis of the NMR an MS data as well as by comparison with literature data. These compounds were evaluated for the anti-inflammatory activities against COX-1 and -2 inhibitory potentials. Most of the compound isolated showed non selective COX inhibitions except for 3-Acetoxy-1β-hydroxyLupe-20(29)-ene (5), Lup-20(29)-ene-1β,3β-diol (6) which showed COX-2 selective inhibition at 0.54 (1.85), and 0.45 (2.22) IC50, in mM (Selective Index),...
Natural Product Research, 2016
A new β-carboline alkaloid named sacleuximine A (1) together with known compounds palmatine (2), ... more A new β-carboline alkaloid named sacleuximine A (1) together with known compounds palmatine (2), isotetrandrine (3), trans-N-feruloyltyramine (4), trans-N-caffeoyltyramine (5), yangambin (6), syringaresinol (7), sesamin (8), (+) epi-quercitol (9), 4-hydroxybenzaldehyde (10), β-sitosterol (11), quercetin 3-O-rutinoside (12) and myricetin 3-O-β-glucose (1→6) α-rhamnoside (13) have been isolated from methanol extract of Triclisia sacleuxii aerial parts. Compounds 1-10 were evaluated for their cytotoxicity against human adenocarcinoma (HeLa), human hepatocarcinoma (Hep3B) and human breast carcinoma (MCF-7) cells lines and also for antibacterial activities against both Gram-positive and Gram-negative bacteria. The cytotoxicity (IC50) values ranged between 0.15 and 36.7 μM while the minimum inhibitory concentrations were found to be in the range of 3.9 and 125 μM, respectively. This is the first report of antibacterial compounds and the isolation of lignans together with a β-carboline alkaloid from T. sacleuxii.
Online Submission, 2005
Year-to-year rater variation may result in constructed response (CR) parameter changes, making CR... more Year-to-year rater variation may result in constructed response (CR) parameter changes, making CR items inappropriate to use in anchor sets for linking or equating. This study demonstrates how rater severity affected the writing and reading scores. Rater adjustments were made to statewide results using an item response theory (IRT) methodology based on the work of Tate (1999, 2000). The common item equating design was used to place the second year scores to the first year scores after a re-score of the first year test in order to adjust for rater effects. Two samples of data from contiguous years, designated as Year 1 (n ~ 1,200) and Year 2 (n ~ 2,000), from the writing and reading portions of a statewide assessment were examined. The writing test consisted of 32, 36, and 40 selected-response items for grade 4, 6, and 8 and a single writing prompt scored on a six-point scale (0-5) scored by two raters whose scores are added for a composite. The reading test consists of 75, 93, and 91 selected-response items and 12, 14, and 16 constructed response items for grade 4, 6, and 8, respectively. All the CR items in reading were scored on a three-point scale (0-2.) The resulting item parameters were compared between year one and two, with and without rater adjustment. For writing, there were significant shifts in the parameters after rater adjustment. The p-values and TCCs shifted across years when adjusted for rater effects. The impact of the parameter shifts and TCCs manifested in the changes in the proficiency classification before and after adjustment. The results of the study suggests that raters were not consistently more severe or more lenient between grades or content areas, but the resulting rater error (severity or leniency) affected the scores and thereby produced misleading results if not taken into account.
The Natural Products Journal, 2015
Agricultural production is constrained by insect pests, which cause serious post-harvest losses o... more Agricultural production is constrained by insect pests, which cause serious post-harvest losses of up to 43% in developing countries. Maize weevil (Sitophilus zeamais Motschulsky.) is one of the most destructive pests of maize. Synthetic chemicals have been used to protect stored grain from damage by insects. The increasing knowledge about the harm derived from the indiscriminate use of synthetic insecticides has prompted research aimed at finding safe methods of pest control. Efficacy of extractives and isolates from Warburgia ugandensis (Canellaceae) were evaluated for maize grain protection against S. zeamais. The oil extract was the most repellent (P<0.05) with repellence distance of 6.37 within 2-hour exposure duration followed by n-hexane extract (6.20 cm). The most repellent compounds were mukaadial (6) and polygodial (1) (5.43 and 4.83 cm, respectively). Essential oil was the most toxic (P<0.05) to the weevils and showed 100% mortality at 21 days. The toxicity levels of the organic extracts ranged from 18.3 to 78.0% with n-hexane exhibiting the highest toxicity followed by ethyl acetate extract. Polygodial (1) and warburganal (2) were the most toxic compounds (70.0 and 65.0% respectively). The oil extract was as active as the Actellic dust and completely inhibited the emergence of the insect adults. Polygodial (1), ugandensolide (3) and warbuganal (2) had the best growth inhibition activity. The results from the present study indicate that W. ugandensis could be a useful alternative in stored grain protection against maize weevil and the isolated compounds could be good candidates as phytoinsecticidal agents against insect pests.
Background: The root decoction of Cnestis ferruginea Vahl ex DC (Connaraceae) is used in traditio... more Background: The root decoction of Cnestis ferruginea Vahl ex DC (Connaraceae) is used in traditional African medicine (TAM) in the treatment of epilepsy. Objectives: This study sought to investigate the anticonvulsant effect of the methanolic root extract of Cnestis ferruginea (CF) in mice as well as isolation of its phytoconstituents responsible for the observed effect. Methods: Anticonvulsant activity of CF (50-400 mg/kg, p.o.) was assessed using maximal electroshock- (MES), strychnine- (STR) (4 mg/kg, i.p.), picrotoxin- (PTX) (7.5 mg/kg, i.p.), bicuculline- (BIC) (2.7 mg/kg, i.p.), isoniazid-(INH) (250 mg/kg, i.p.) and yohimbine (YHB) (45 mg/kg, s.c.)- induced seizure models in mice. Results: CF (50-400 mg/kg, p.o.) produced significant reduction in the duration of MES-induced seizure with peak effect 20% protection at 200 mg/kg. However, peak effect 60% protection of tonic seizure was obtained at 50 mg/kg following CF pretreatment in strychnine model. Clonazepam (0.5 mg/kg, p.o....
Many measures found in educational research are ordered categorical response variables that are e... more Many measures found in educational research are ordered categorical response variables that are empirical realizations of an underlying normally distributed variate. These ordered categorical variables are commonly referred to as Likert or rating scale data. Regression models are commonly fit using these ordered categorical variables as the criterion (i.e., dependent or response) variable; however, a common recommendation in the methodological literature is that researchers make use of ordinal logistic regression when they have these ordered categorical response variables. An advantage of ordinal logistic regression is that it provides a pseudo R-squared measure of fit so that researchers may find this regression model familiar and hence appealing. This study investigated how the pseudo R-squared fit statistic in ordinal logistic regression operates under a variety of conditions over a varying number of Likert scale points and skewness of the Likert data. The study also demonstrates how the regular ordinary least-squares R-squared statistic operates in the same conditions as the Likert data. The pseudo R-squared fit statistic operates well in a majority of ccmditions, and so it is recommended that educational researchers begin to explore the use of ordinal logistic regression in their modeling practice with ordered categorical data. Using the pseudo R-squared index will ease the transition to ordinal logistic regression because it provides a sense of familiarity to the researcher. (Contains 4 figures, 11 tables, and 6 references.) (Author/SLD) Reproductions supplied by EDRS are the best that can be made from the original document.
The Natural Products Journal, 2014
Journal of Medicinal Food, 2014
Unripe fruit of Annona muricata Linn. (Annonaceae) (soursop) is used in traditional African medic... more Unripe fruit of Annona muricata Linn. (Annonaceae) (soursop) is used in traditional African medicine for the treatment of neuralgia, rheumatism, and arthritic pain. This study sought to investigate the analgesic and antiinflammatory effects of lyophilized fruit extract of Annona muricata (AM) in rodents. The analgesic activity was evaluated using the mouse writhing, formalin, and hot-plate tests while the anti-inflammatory action was investigated using the carrageenan-induced rat paw edema and xylene-induced ear edema tests. Pretreatment with AM (50, 100, and 200 mg/kg, p.o.) produced dose-dependent (P < .001) inhibition of writhes and formalin-induced pain in the late phase. AM and morphine produced time-course increase in pain threshold in hot-plate test. However, the analgesic effect elicited by AM was reversed (P < .05) by naloxone pretreatment. Similarly, the time-dependent increase in paw circumference induced by carrageenan was inhibited by AM treatment with peak effect (0.23-0.10 cm; P < .001, 200 mg/kg; 6 h), which was comparatively similar to that of diclofenac treated. Further, the xylene-induced ear edema was significantly reduced by AM (50 or 100 mg/kg) pretreatment; however, the anti-inflammatory effect elicited by AM was prevented by pretreatment of mice with N G-nitro-l-arginine (20 mg/kg, i.p., nitric-oxide synthase inhibitor) 15 min before AM (200 mg/kg, p.o.). The in vitro cyclooxygenase assay also showed that AM produced concentration-dependent inhibition of both cyclooxygenase (COX)-1 and COX-2 activity by 39.44%-0.05% and 55.71%-0.12%, respectively, at 100 lg/mL. In conclusion, A. muricata possesses analgesic effect through interaction with opioidergic pathway and anti-inflammatory property through inhibition of chemical mediators of inflammation.
Research Journal of Pharmacology, 2010
Various parts of Gardenia ternifolia (leaves, roots and stem bark) have been reported by traditio... more Various parts of Gardenia ternifolia (leaves, roots and stem bark) have been reported by traditional healers as a remedy against malaria fever. The aerial parts are coated with shiny materials rich in flavonoid aglycones. The crude acetone wash of the aerial parts showed anti-plasmodial activity of IC 50 values 1.06 and 0.94 μg mL-1 against chloroquine-resistant (W2) and chloroquine-sensitive (D6) strains of Plasmodium falciparum, respectively. Bioassay guided chromatographic separation of the crude extracts afforded five flavonoids; (naringenin-7-O-methylether, quercetin-4, 7-O-dimethylether, kaempferol-7-O-methylether, 4, 5-Dihydroxy-6, 7-dimethoxyflavanone, naringenin-4, 7-O-dimethyl-ether) and two steroids; (stigmasterol, β-sitosterol). The same crude acetone surface extract as well as the pure isolates showed moderate larvicidal effects against 2nd instar Ae. aegypti larvae. Naringenin-7-O-methyl-ether was the most potent principle.
The Natural Products Journal, 2012
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Papers by charles ochieng