Robust linear classifier for unequal cost ratios of misclassification

This paper focuses on the robust classification procedures when the assumption of equal cost of misclassification is violated. A normal distribution based data set is generated using the Statistical Analysis System (SAS) version 9.1. Using Barlett's approximation to chi-square, the data set was found to be homogenous and was subjected to three linear classifiers namely: Maximum Likelihood Discriminant Function (MLDF), Fisher's linear Discriminant Function and Distance Based Discriminant Function. To Judge the performances of these procedures, the Apparent Error Rates for each procedure is obtained for different cost ratios 1:1, 1:2, 1:3, 1:4 and 1:5 and sample sizes 5:5, 10:10, 20:20, 30:30, and 50:50. The results shows that the three procedures are insensitive to cost ratio exceeding ratio 1:2 and that MLDF was observed as robust discriminant function among classification functions considered

Error Rates Stability of The Homoscedastic Discriminant Function

In this study the stability of the observed error rates of the homoscedastic discriminant function relative to the number of parameters in the model using simulated data from multivariate normal populations was investigated.   Three models were considered, the four, six and eight variables models, each having four values of the separator function (). Equal and unequal prior probabilities were considered for the different number of parameter and separator function configurations. The asymptotic performance of the models was considered using the cross validation error rate estimation procedure. Results indicate the six variable models as being more stable (displaying less variability in the estimated error rates) than the other models under consideration. Less deterioration was observed for the six-variable model specification as was evident in the other models and this was more pronounced for smaller values of. &nbsp

Degradation of cyclohexane and cyclohexanone by Bacillus lentus strain LP32

A Gram-positive bacterium, Bacillus lentus LP32, originally isolated on the basis of its ability to utilise pyrene as sole source of carbon was found to be able to grow luxuriantly on alicyclic compounds as sole substrates. It showed poor growth on anthracene, naphthalene, 1-naphthol and phenanthrene. Growth rate on cyclohexane was 1.32 d-1, while doubling time was 0.76 d. The corresponding values for growth on cyclohexanone were 0.77 d-1 and 1.29 d, respectively. Within 10 days, the amount of cyclohexane in culture reduced from 317.62 to 102.55 mgl-1, then to 23.04 mgl-1 on day 18. On cyclohexanone, substrate concentration decreased from 287.56 mgl-1 to 101.66 mgl-1 in 10 days before declining to 24.21 mgl-1 on day 18. The rate of degradation when growing on cyclohexane was 23.50 mgl-1d-1 in the first 10 days and 9.93 mgl-1d-1 between day 10 and day 18, with 67.71% degradation in 10 days and overall percentage degradation of 92.43%. On cyclohexanone, the corresponding values were 18.59 and 9.68 mg l-1d-1 as well as 64.65 and 91.58%, respectively. This organism is a potential candidate for bioremediation purpose.Keywords: Degradation, cyclohexane, cyclohexanone, alicyclic compounds

The Impact of Socio-Demographic Factors on Domestic Tourism Consumption Expenditure in Ghana

This study applies quantile regression approach to analyse socio-demographic factors that affect domestic tourism consumption expenditure in Ghana. The approach uses household domestic tourism expenditure as a response variable. The internet access of the household, whether a household owns a mobile phone, and /or at least one car or not are represented as proxies for information and transport accessibility, respectively. Other variables included to constrain household domestic travel budgets are yearly household income and household loan. The rest are demographic characteristics such as age and educational level of household heads. The empirical results show that relatively older and well educated household heads with higher earnings are prepared and willing to expend more on domestic tourism in Ghana. The results further show that, in Ghana, household loans are one of the major constraints of domestic tourism spending for medium and heavy spenders, but positively and significantly influence light domestic tourism expenditure households. Internet access, ownership of a car and mobile phone have no relation with the amount of money spent on domestic tourism in Ghana. Keywords: domestic tourism, quantile regression, tourism consumption expenditure, socio-demographic variables, same-day visitors and overnight tourists. DOI: 10.7176/JTHS/41-05 Publication date:May 31st 201

Modelling Domestic Tourism Demand for Ghana

The research analyses the demand for tourism goods and services in Ghana by domestic tourists. For this purpose, it uses the Linear Almost Ideal Demand System (LAIDS) model (static and dynamic) to estimate price and expenditure/income elasticities for the study. The tourism goods and services include: accommodation; food and drinks; transport; recreation, culture and sporting activities; shopping; and other services. The uncompensated and compensated price and expenditure/income elasticities were calculated from the estimated parameters of the LAIDS model, static and dynamic. The results show that all own-price elasticities are negative and significant for uncompensated and compensated elasticities, while expenditure/income elasticities are positive and significant. The findings show that, by short-run, the demand for tourism goods and services in Ghana is price inelastic and expenditure/income elastic, and are normal goods and services. KEY WORDS: Static, dynamic, uncompensated, compensated, AIDS, elasticity. DOI: 10.7176/JTHS/40-0

Duration of androgen deprivation therapy with postoperative radiotherapy for prostate cancer: a comparison of long-course versus short-course androgen deprivation therapy in the RADICALS-HD randomised trial

Background Previous evidence supports androgen deprivation therapy (ADT) with primary radiotherapy as initial treatment for intermediate-risk and high-risk localised prostate cancer. However, the use and optimal duration of ADT with postoperative radiotherapy after radical prostatectomy remains uncertain. Methods RADICALS-HD was a randomised controlled trial of ADT duration within the RADICALS protocol. Here, we report on the comparison of short-course versus long-course ADT. Key eligibility criteria were indication for radiotherapy after previous radical prostatectomy for prostate cancer, prostate-specific antigen less than 5 ng/mL, absence of metastatic disease, and written consent. Participants were randomly assigned (1:1) to add 6 months of ADT (short-course ADT) or 24 months of ADT (long-course ADT) to radiotherapy, using subcutaneous gonadotrophin-releasing hormone analogue (monthly in the short-course ADT group and 3-monthly in the long-course ADT group), daily oral bicalutamide monotherapy 150 mg, or monthly subcutaneous degarelix. Randomisation was done centrally through minimisation with a random element, stratified by Gleason score, positive margins, radiotherapy timing, planned radiotherapy schedule, and planned type of ADT, in a computerised system. The allocated treatment was not masked. The primary outcome measure was metastasis-free survival, defined as metastasis arising from prostate cancer or death from any cause. The comparison had more than 80% power with two-sided α of 5% to detect an absolute increase in 10-year metastasis-free survival from 75% to 81% (hazard ratio [HR] 0·72). Standard time-to-event analyses were used. Analyses followed intention-to-treat principle. The trial is registered with the ISRCTN registry, ISRCTN40814031, and ClinicalTrials.gov , NCT00541047 . Findings Between Jan 30, 2008, and July 7, 2015, 1523 patients (median age 65 years, IQR 60–69) were randomly assigned to receive short-course ADT (n=761) or long-course ADT (n=762) in addition to postoperative radiotherapy at 138 centres in Canada, Denmark, Ireland, and the UK. With a median follow-up of 8·9 years (7·0–10·0), 313 metastasis-free survival events were reported overall (174 in the short-course ADT group and 139 in the long-course ADT group; HR 0·773 [95% CI 0·612–0·975]; p=0·029). 10-year metastasis-free survival was 71·9% (95% CI 67·6–75·7) in the short-course ADT group and 78·1% (74·2–81·5) in the long-course ADT group. Toxicity of grade 3 or higher was reported for 105 (14%) of 753 participants in the short-course ADT group and 142 (19%) of 757 participants in the long-course ADT group (p=0·025), with no treatment-related deaths. Interpretation Compared with adding 6 months of ADT, adding 24 months of ADT improved metastasis-free survival in people receiving postoperative radiotherapy. For individuals who can accept the additional duration of adverse effects, long-course ADT should be offered with postoperative radiotherapy. Funding Cancer Research UK, UK Research and Innovation (formerly Medical Research Council), and Canadian Cancer Society

Adding 6 months of androgen deprivation therapy to postoperative radiotherapy for prostate cancer: a comparison of short-course versus no androgen deprivation therapy in the RADICALS-HD randomised controlled trial

Background Previous evidence indicates that adjuvant, short-course androgen deprivation therapy (ADT) improves metastasis-free survival when given with primary radiotherapy for intermediate-risk and high-risk localised prostate cancer. However, the value of ADT with postoperative radiotherapy after radical prostatectomy is unclear. Methods RADICALS-HD was an international randomised controlled trial to test the efficacy of ADT used in combination with postoperative radiotherapy for prostate cancer. Key eligibility criteria were indication for radiotherapy after radical prostatectomy for prostate cancer, prostate-specific antigen less than 5 ng/mL, absence of metastatic disease, and written consent. Participants were randomly assigned (1:1) to radiotherapy alone (no ADT) or radiotherapy with 6 months of ADT (short-course ADT), using monthly subcutaneous gonadotropin-releasing hormone analogue injections, daily oral bicalutamide monotherapy 150 mg, or monthly subcutaneous degarelix. Randomisation was done centrally through minimisation with a random element, stratified by Gleason score, positive margins, radiotherapy timing, planned radiotherapy schedule, and planned type of ADT, in a computerised system. The allocated treatment was not masked. The primary outcome measure was metastasis-free survival, defined as distant metastasis arising from prostate cancer or death from any cause. Standard survival analysis methods were used, accounting for randomisation stratification factors. The trial had 80% power with two-sided α of 5% to detect an absolute increase in 10-year metastasis-free survival from 80% to 86% (hazard ratio [HR] 0·67). Analyses followed the intention-to-treat principle. The trial is registered with the ISRCTN registry, ISRCTN40814031, and ClinicalTrials.gov, NCT00541047. Findings Between Nov 22, 2007, and June 29, 2015, 1480 patients (median age 66 years [IQR 61–69]) were randomly assigned to receive no ADT (n=737) or short-course ADT (n=743) in addition to postoperative radiotherapy at 121 centres in Canada, Denmark, Ireland, and the UK. With a median follow-up of 9·0 years (IQR 7·1–10·1), metastasis-free survival events were reported for 268 participants (142 in the no ADT group and 126 in the short-course ADT group; HR 0·886 [95% CI 0·688–1·140], p=0·35). 10-year metastasis-free survival was 79·2% (95% CI 75·4–82·5) in the no ADT group and 80·4% (76·6–83·6) in the short-course ADT group. Toxicity of grade 3 or higher was reported for 121 (17%) of 737 participants in the no ADT group and 100 (14%) of 743 in the short-course ADT group (p=0·15), with no treatment-related deaths. Interpretation Metastatic disease is uncommon following postoperative bed radiotherapy after radical prostatectomy. Adding 6 months of ADT to this radiotherapy did not improve metastasis-free survival compared with no ADT. These findings do not support the use of short-course ADT with postoperative radiotherapy in this patient population

Engineering properties of tropical clay and bentonite modified with sawdust

Construction engineers typically avoid the use of expansive soils as construction materials because they are usually difficult to work on and can cause structural failure. This research work investigates how the application of sawdust to tropical clay and bentonite influences their geotechnical properties in order to determine their suitability for use as landfill-liner materials for the effective containment of toxic substances from landfills. X-ray diffractometry, X-ray fluorescence spectroscopy and scanning electron microscopy were used to determine the mineralogical composition, oxide composition and microstructure, respectively, of the clay and the bentonite. A series of laboratory tests were conducted to determine the specific gravity, Atterberg limits, compaction, unconfined compressive strength and permeability characteristics of the clay and the bentonite for varying proportions of sawdust application. Generally, increasing the percentage of sawdust caused a reduction in its specific gravity, maximum dry unit weight and unconfined compressive strength, while it caused an increase in the optimum moisture content and permeability of the modified clay and bentonite. The clay and bentonite both have a sufficiently low permeability that satisfies the hydraulic conductivity requirement for use as clay liners. Eight percent sawdust application to a clay having similar properties as that in this study is recommended as an economic way of modifying it – with the potential of improving its adsorbent property – for use in landfill-liner systems in order to prevent the toxic substances leaching from the landfills, thereby protecting the environment and public health

Incidence of Ascaris infection among primary school children in Ogun State, Nigeria: A generalised linear model approach

To estimate the effect of community soil (location) on the incidence and prevalence of Ascaris infection in school children, the model assumptions of the Generalised Linear Model (GLM) in a linear relationship between independent (Xis) and dependent variable (Y), where (Yi)=i = &#9461Xi1 + &#9462Xi2, + + &#946pXipwas adopted. Of the 1,519 pupils, 30% (225/759) male and 28% (210/760) female pupils were infected with Ascaris lumbricoides but it was not sex-specific (p>0.05). Male pupils voided higher number of worms (1,090, X = 2.2) than female pupils (879, X = 1.7). Intensity of infection rates was inversely related to body weight of pupils. The model observed a significant probability of Keywords: general linear nodel, ascaris, school children, Ogun State, Nigeria.Nigerian Journal of Parasitology Vol. 29 (1) 2008 pp. 32-3