This study is aimed to evaluate the accuracy of Demirjian method in estimating the chronological age of male and female Kelantanese Malay children between 6 and 16 years of age and to establish a new dental age (DA) curve if the Demirjian method was not found to be accurate. About 905 panoramic radiographs of healthy Malay children between 6 and 16 years of age were collected from the radiographic unit in the Hospital Universiti Sains Malaysia (HUSM) and the orthodontic clinic in Hospital Kota Bharu (HKB). Children who had any disease affecting the dental development, or have agenesis in the lower arch and poor quality radiographic images were excluded. The results showed that Demirjian method overestimated the chronological age (CA) by 1.23 years for boys and 1.20 years for girls and it was less accurate for the Kelantanese Malay children. Thus new standard curve were produced and tested on external samples. Results showed that the mean difference between the chronological age and DA is about 0.17 years for boys and 0.11 years for girls. DA was more advanced in the Kelantanese Malay boys and girls as compared to French-Canadian children in all age groups. It is concluded that the Demirjian method tends to be less accurate in estimating the chronological age in Malay children. The new curve that was produced is more applicable to the Kelantanese Malay children.
Soil properties are very crucial for civil engineers to differentiate one type of soil from another and to predict its mechanical behavior. However, it is not practical to measure soil properties at all the locations at a site. In this paper, an estimator is derived to estimate the unknown values for soil properties from locations where soil samples were not collected. The estimator is obtained by combining the concept of the ‘Inverse Distance Method’ into the technique of ‘Kriging’. The method of Lagrange Multipliers is applied in this paper. It is shown that the estimator derived in this paper is an unbiased estimator. The partiality of the estimator with respect to the true value is zero. Hence, the estimated value will be equal to the true value of the soil property. It is also shown that the variance between the estimator and the soil property is minimized. Hence, the distribution of this unbiased estimator with minimum variance spreads the least from the true value. With this characteristic of minimum variance unbiased estimator, a high accuracy estimation of soil property could be obtained.
OBJECTIVE: To assess the efficacy of oral palm vitamin E in reducing symptoms of patients with osteoarthritis (OA) of the knee compared to oral glucosamine sulphate.
METHODS: This open study was carried out at the Universiti Kebangsaan Malaysia Medical Center, Kuala Lumpur, Malaysia between March 2006 and November 2007. Seventy-nine patients were recruited to receive either 1.5 g oral glucosamine sulphate or 400 mg oral palm vitamin E for 6 months. Symptoms were assessed using the Western Ontario and McMaster Universities (WOMAC) osteoarthritis index and visual analogue scale (VAS).
RESULTS: Sixty-four patients completed the trial (vitamin E n=33, glucosamine sulfate n=31). After 6 months of treatment, both groups showed a significant improvement in WOMAC scale and significant reduction in the VAS score during standing and walking. There was no significant difference in WOMAC scale and VAS score between the 2 groups. Except for mild allergic reaction and abdominal discomfort in one patient, there were no other serious adverse effects reported. Serum malondialdehyde was significantly higher in the glucosamine group compared to palm vitamin E treated group at the end of the study. Serum of vitamin E was significantly higher in the palm vitamin E group compared to glucosamine.
CONCLUSION: The finding of this study suggests that oral palm vitamin E in a dose of 400 mg taken daily has a potential role in reducing symptoms of patients with OA of the knee. It may be just as effective as glucosamine sulphate in reducing the symptoms and free from serious side effects. Further study is required to ascertain the mechanism of action beside its antioxidant effect.
This study involves the adoption of the Geographic Information System (GIS) modeling approach to determine the quickest routes for fresh vegetable delivery. During transport, fresh vegetables mainly deteriorate on account of temperature and delivery time. Nonetheless, little attention has been directed to transportation issues in most areas within Kuala Lumpur. In addition, perishable food normally has a short shelf life, thus timely delivery significantly affects delivery costs. Therefore, selecting efficient routes would consequently reduce the total transportation costs. The regression model is applied in this study to determine the parameters that affect route selection with respect to the fastest delivery of fresh vegetables. For the purpose of this research, ArcGIS software with network analyst extension is adopted to solve the problem of complex networks. The final output of this research is a map of quickest routes with the best delivery times based on all variables. The variables tested from regression analysis are the most effective parameters to make the flow of road networks slower. The objective is to improve the delivery services by achieving the least drive time. The main findings of this research are that Land use such as residential area and population as variables are the effective parameters on drive time.
Higher level of education is associated with better cognitive performance and lower risk of developing dementia. However, the effect of education on cognitive performance varies across different cognitive domains and in different populations. The aim of this study was to determine the relationship between education and performance of different cognitive domains among healthy Malay adults. A total of 53 individuals aged 29 to 77 years participated in a battery of neurophysiological tests consisting of Mini-Mental State Examination, Montreal Cognitive Assessment, digit span, visual reproduction and digit symbol speed test (DSST). Blood test was performed for each participant to obtain their biochemical profile. Educational level was divided into level 1 (PMR), level 2 (SPM), level 3 (STPM), level 4 (Diploma) and level 5 (Degree). Simple linear regression indicated that years of education was positively associated with scores of delayed visual reproduction (b=1.348, p=0.002) and DSST (b=3.257, p=0.012). However, scores of all the tests were not significantly different among different levels of education after controlling for age, gender and blood test profile by ANCOVA. Multiple linear regression analysis showed that MMSE score was associated with red cell distribution width (b=-0.628, p=0.005), age (b=-0.119, p<0.001) and there was interaction between high density lipoprotein (HDL) with age (b=0.047, p<001). MoCA score was associated with age (b=-0.121, p<0.001), gender (male compared to female, b=1.870, p=0.020) and HDL (b=1.681, p=0.047). Age was associated with backward digit span (b=-0098, p<0.001) and immediate visual reproduction (b=-0.348, p<0.001), resp. Delayed visual reproduction was associated with age (b=-0.323, p<0.001) and potassium level (b=-4.471, p=0.016). DSST was associated with age (b=-0.911, p<0.001) and alanine aminotransferase (b=-0.754, p=0.002). The lack of association between educational level and cognitive performance after adjusting for confounders in this study maybe due to multiple factors influencing cognitive performance and further studies with a larger sample size are needed to further identify the factors involved.
Keywords: Cognitive performance; education; healthy Malay adults
ABSTRAK
Tahap pendidikan yang tinggi telah dikaitkan dengan prestasi kognitif yang lebih baik dan risiko perkembangan dementia yang lebih rendah. Namun, kesan pendidikan terhadap prestasi kognitif berbeza antara domain kognitif dan populasi yang berlainan. Kajian ini bertujuan untuk menentukan hubungan antara pendidikan dengan prestasi pada domain kognitif yang berlainan pada individu dewasa Melayu yang sihat. Seramai 53 individu yang berumur antara 29 hingga 77 tahun telah menyertai ujian neuropsikologi yang terdiri daripada Pemeriksaan Keadaan Mental Mini, Penilaian Kognitif Montreal, digit span, penghasilan semula visual dan ujian kelajuan simbol digit (DSST). Tahap pendidikan dibahagikan kepada tahap 1 (PMR), tahap 2 (SPM), tahap 3 (STPM), tahap 4 (Diploma) dan tahap 5 (Ijazah Sarjana Muda). Regresi linear mudah menunjukkan bahawa tahap pendidikan berhubung kait secara positif dengan penghasilan semula visual tertunda (b=1.348, p=0.002) dan DSST (b=3.257, p=0.012). Namun, semua skor ujian menjadi tidak berbeza antara tahap pendidikan yang berbeza selepas mengambil kira kesan konpengasas dengan menggunakan ANCOVA. Regresi linear berganda menunjukkan bahawa skor MMSE berhubung kait dengan lebar taburan sel merah (b=-0.628, p=0.005), umur (b=-0.119, p<0.001) dan interaksi antara lipoprotein ketumpatan tinggi (HDL) dan umur (b=0.047, p<001). MoCA didapati berhubung kait dengan umur (b=-0.121, p<0.001), jantina (lelaki berbanding perempuan, b=1.870, p=0.020) dan HDL (b=1.681, p=0.047). Umur juga berhubung kait dengan digit span ke belakang (b=-0098, P<0.001) dan penghasilan semula visual segera (b=-0.348, p<0.001). Penghasilan semula visual tertunda berhubung kait dengan umur (b=-0.323, p<0.001) dan tahap kalium (b=-4.471, p=0.016). DSST berhubung kait dengan umur (b=-0.911, p<0.001) dan alanin aminotransferase (b=-0.754, p=0.002). Hubungan antara tahap pendidikan dan prestasi kognitif tidak dikesan selepas mengambil kira kesan konpengasas yang mencadangkan bahawa prestasi kognitif mungkin dipengaruhi oleh pelbagai faktor dan kajian lanjut dengan bilangan sampel yang lebih besar diperlukan untuk mengenal pasti faktor ini.
In recent years, Malaysia has experienced quite a few number of chronic air pollution problems and it has become a
major contributor to the deterioration of human health and ecosystems. This study aimed to assess the air quality data
and identify the pattern of air pollution sources using chemometric analysis through hierarchical cluster analysis (HCA),
discriminant analysis (DA), principal component analysis (PCA) and multiple linear regression analysis (MLR). The air
quality data from January 2016 until December 2016 was obtained from the Department of Environment Malaysia. Air
quality data from eight sampling stations in Selangor include the selected variables of nitrogen dioxide (NO2
), ozone (O3
),
sulfur dioxide (SO2
), carbon monoxide (CO) and particulate matter (PM10). The HCA resulted in three clusters, namely low
pollution source (LPS), moderate pollution source (MPS) and slightly high pollution source (SHPS). Meanwhile, DA resulted
in two and four variables for the forward stepwise mode and the backward stepwise mode, respectively. Through PCA,
it was identified that the main pollutants of LPS, MPS and SHPS came from industrial and vehicle emissions, agricultural
systems, residential factors and natural emission sources. Among the three models yielded from the MLR analysis, it was
found that SHPS is the most suitable model to be used for the prediction of Air Pollution Index. This study concluded that
a clearer review and practical design of air quality monitoring network would be beneficial for better management of
air pollution. The study also suggested that chemometric techniques have the ability to show significant information on
spatial variability for large and complex air quality data.
This study aimed to evaluate the level of knowledge, attitude and practice (KAP) amongst food handlers in food utensils
hygiene and presence of bacterial contamination on food utensils. There were two approaches used in this study. In the
first approach, 134 of food handlers from 75 food premises were interviewed via questionnaires to assess their knowledge,
attitude and practice. In the second approach, the presence of Staphylococcus aureus, Escherichia coli and total coliform
of 225 utensils (knives (75), chopping boards (75) and dish plates (75)) was examined. The result showed that the food
handlers had sufficient level of knowledge (80.5%), attitude (87.4%) and practice (90.1%). Highest contamination was
found on the chopping boards for the presence of S. aureus (82.8%), E. coli (9.7%) and total coliform (73.9%). Logistic
regression analysis showed that knowledge contributes to the presence of E. coli on the dish plates; and total coliform
on the knives. Thus, ongoing training that focused on food utensils hygiene must be emphasized to improve knowledge,
attitude and practice amongst the food handlers.
Multicollinearity that may exist among explanatory variables in a regression model can make the regression coefficients insignificant and difficult to interpret. Principal component regression (PCR) is an effective way for solving multicollinearity in regression analysis. The existence of multicollinearity mayor may not be induced by the presence of influential observations. This paper discusses some diagnostic methods for identifying influential observations in the PCR. A data set on water quality of New York Rivers was considered to illustrate the methods.
Multikolinearan yang wujud di kalangan pembolehubah penerang dalam model regresi boleh menyebabkan pekali regresi tidak bererti dan sukar untuk ditafsirkan. Regresi komponen utama (PCR) merupakan cara yang berkesan bagi menyelesaikan masalah multikolinearan dalam analisis regresi. Kewujudan multikolinearan mungkin disebabkan oleh data terpencil yang berpengaruh. Kertas ini membincangkan beberapa kaedah pengecaman bagi mengenalpasti data berpengaruh dalam PCR. Data tentang kualiti air di beberapa batang sungai di New York digunakan untuk memperihalkan kaedah pengecaman yang disarankan.
The application of solar disinfection for treating stored rainwater was investigated by the authors using indicator organisms. The multiple tube fermentation technique and pour plate method were used for the detection of microbial quality indicators like total and fecal coliforms, E. coli and heterotrophic plate count. These techniques have disadvantages mainly that these are laborious and time consuming. The correlation of total coliform with that of exposure time is proposed under different factors of weather, pH and turbidity. Statistical tools like root mean square error and coefficient of determination were used to validate these proposed equations. The correlation equations of fecal coliform, E. coli and heterotrophic plate count with total coliform are suggested by using four regression analysis including Reciprocal Quadratic, Polynomial Regression (2 degree), Gaussian Model and Linear Regression in order to reduce the tedious experimental work in similar types of experiments and treatment systems.
The objective of this study was to identify the exogenous variables of risk and investment management efficiency by using a two-stage data envelopment analysis (DEA) method. The first stage involves obtaining the efficiency scores of risk and investment management via DEA that requires only the traditional inputs and outputs. In the second stage, the Tobit regression analysis is conducted in which the efficiency score obtained from the first stage is treated as a dependent variable, while the exogenous factors are considered to be independent variables. The exogenous factors consist of operating systems, organizational form, consumer preference and size. The results showed that the mutual company as well as the takaful system demonstrate better risk management performance than their stock and conventional system counterparts. In addition, size is also a significant indicator for risk management efficiency in which the larger insurer/takaful operator exhibits better risk management performance than the smaller one. However, consumer preference is found to be insignificantly correlated with the efficiency of risk management. In contrast, with risk management, organizational form, operating system and size are not indicators of the investment management efficiency, but consumer preference is significantly and positively associated with investment management efficiency.
In this paper we investigated the concentrations of Pb in seven different soft tissues (foot, cephalic tentacles, mantle muscle, gill, digestive caecum and remaining soft tissues) of 17 geographical populations of Telescopium telescopium collected from the intertidal area of Peninsular Malaysia. Two points can be presented based on the present study. First, as expected, different concentrations of Pb were found in the different soft tissues, indicating different mechanisms of bioaccumulation and regulations of Pb in these different tissues. By comparing the Pb concentrations in the similar tissues, spatial variation of Pb was found in the different sampling sites although there is no consistent pattern of Pb contamination in these sampling sites. Second, based on the correlation coefficients and multiple linear stepwise regression analysis between Pb concentrations in the different soft tissues and Pb concentrations in geochemical factions in the surface sediments, it is found that gill and digestive caecum can truly reflect Pb contamination and Pb bioavailabilities in the tropical intertidal mudflats. To our knowledge, this is the most comprehensive study on Pb in the different soft tissues of T. telescopium, in relation to the habitat sediments of the snails.
Dwarf bamboo is recognized as a significant determinant of the structure and dynamics in temperate forests. Quantitative relationships between the abundance (density and coverage) of dwarf bamboo, Fargesia nitida, and micro-environments, species diversity on the floor were estimated in an Abies faxoniana pure forest in southwest China. Understory microenvironmental conditions (daily differences temperature and moisture, RPPFD under bamboo layer and ground cover) changed dramatically with the bamboo density. Stepwise multiple regression analyses indicated that abundance of F. nitida was mainly correlated with canopy characteristics and disturbance factors in the A. faxoniana pure forest. All richness indices decreased significantly with the bamboo density and RPPFD under bamboo layer. Importance values (IV) of understory species in different bamboo densities and Detrended canonical correspondence analysis (DCCA) indicated three understory plant groups, resistant to high bamboo abundance (Group A), resistant to intermediate bamboo abundance (Group B) and sensitive to bamboo abundance (Group C). These groups mainly responded to abundance of bamboo and RPPFD under bamboo layer, resulted from the integration of characteristics of bamboo, canopy and topography factors. Different bamboo abundance had different influences on understory species diversity and groups. Dense F. nitida condition (> 10 culms/m2) had significant negative effect and 0-5 bamboo condition had not significant negative effect on understory species diversity in A. faxoniana forest. We suggest the fine-scale analysis on effects of bamboo abundance should be taken account into considering in heterogeneous patches in process of the succession and regeneration of natural forests.
Outliers in the X-direction or high leverage points are the latest known source of multicollinearity. Multicollinearity is a nonorthogonality of two or more explanatory variables in multiple regression models, which may have important influential impacts on interpreting a fitted regression model. In this paper, we performed Monte Carlo simulation studies to achieve two main objectives. The first objective was to study the effect of certain magnitude and percentage of high leverage points, which are two important issues in tending the high leverage points to be collinearity-enhancing observations, on the multicollinarity pattern of the data. The second objective was to investigate in which situations these points do make different degrees of multicollinearity, such as moderate or severe. According to the simulation results, high leverage points should be in large magnitude for at least two explanatory variables to guarantee that they are the cause of multicollinearity problems. We also proposed some practical Lower Bound (LB) and Upper Bound (UB) for High Leverage Collinearity Influential Measure (HLCIM) which is an essential measure in detecting the degree of multicollinearity. A well-known example is used to confirm the simulation results.
Ovarian cancer is one of the highest causes of death among female population in Malaysia. A retrospective cohort study among 127 ovarian cancer patients registered in one of the teaching hospital in Malaysia was conducted from 1st January 2002 until 31st December 2011. The objective of this study was to determine the median survival time, five year survival probability and prognostic factors of ovarian cancer patients. Only ovarian cancer patients were selected with strict inclusion and exclusion criteria. Data was analyzed using Kaplan-Meier Survival analysis and Cox proportional hazard regression analysis. The results showed that the overall five-year survival probability of ovarian cancer was 35.2% (95%CI: 26.3, 44.3) with 38 month (95%CI: 25.7, 50.1) median survival time. After adjustment for potential cofounder, significant prognostic factors of ovarian cancer were observed in FIGO stage (HR: 2.53; 1.44, 4.45), loss of appetite (HR: 1.95; 1.23, 3.11) and presence of pleural effusion (HR: 1.98; 1.19, 3.30). Overall, the survival probabilities of ovarian cancer were low and further actions must be taken to improve the survival among advanced cancer patients
An improved binary differential search (improved BDS) algorithm is proposed for QSAR classification of diverse series of antimicrobial compounds against Candida albicans inhibitors. The transfer functions is the most important component of the BDS algorithm, and converts continuous values of the donor into discrete values. In this paper, the eight types of transfer functions are investigated to verify their efficiency in improving BDS algorithm performance in QSAR classification. The performance was evaluated using three metrics: classification accuracy (CA), geometric mean of sensitivity and specificity (G-mean), and area under the curve. The Kruskal-Wallis test was also applied to show the statistical differences between the functions. Two functions, S1 and V4, show the best classification achievement, with a slightly better performance of V4 than S1. The V4 function takes the lowest iterations and selects the fewest descriptors. In addition, the V4 function yields the best CA and G-mean of 98.07% and 0.977%, respectively. The results prove that the V4 transfer function significantly improves the performance of the original BDS.
OBJECTIVE: Exercise-induced bronchoconstriction (EIB) may be demonstrated in 60-70% of asthmatic children in temperate climates. In areas of high humidity it is postulated to be low. The aim of the study was to determine the prevalence of EIB in a population of schoolchildren with wheezing, living in the humid tropical climate of Kuala Lumpur, Malaysia.
METHOD: We performed a cross-sectional study using the International Study of Asthma and Allergies in Childhood questionnaire to identify 7-12-year-old Malay children with asthma symptoms from a primary school in central Kuala Lumpur. Sixty-five of 76 children with 'ever wheeze' performed an exercise challenge test successfully in an uncontrolled environment. A random sample of 80 schoolchildren with no history of wheeze were similarly tested as controls. The relative humidity and temperature were recorded. A fall of > 15% was considered as clinically important.
RESULTS: The prevalence of EIB in schoolchildren with 'ever wheeze' was 47.7%. The prevalence of EIB in children with 'current wheeze' was 51.6%. The prevalence of EIB in controls was 7.5%. The relative humidity during the study ranged from 41 to 90%. There was no significant relationship between different humidity levels and EIB (P = 0.58, regression analysis).
CONCLUSION: This study demonstrates that EIB is present in asthmatic children despite the highly humid tropical environment.
BACKGROUND AND OBJECTIVE: There is increased use of the 2-min walk test (2MWT) to assess functional exercise capacity. However, the distance achieved during this test may be difficult to interpret in the absence of reference values from a local population. Regression equations to estimate the 2-min walk distance (2MWD) only exist for American and Brazilian populations. The objective of this study was to develop regression equations to estimate the 2MWD in Malaysian adults who were free from major health problems.
METHODS: Eighty-seven adults (43 males; mean ± SD age: 57.1 ± 9.6 years) performed two 2MWT using a standardized protocol. Heart rate (HR) was recorded every 30 s during the test. Stepwise multiple regression analysis was performed using age, gender, height, weight and change in HR (ΔHR) as independent variables, and better of the two 2MWD as the dependent variable. A second regression equation, without ΔHR, was planned if ΔHR was retained as one of the predictors of the 2MWD in the first equation.
RESULTS: The better of the two 2MWD was 200 ± 34 m. Males walked 33 ± 6 m further than females (P < 0.001). The two regression equations were 196 - 1.1 × age, years + 1.0 × ΔHR, bpm + 31.2 × gender (R2 = 0.73) and 279 - 1.7 × age, years + 35.9 × gender (R2 = 0.47) with females = 0 and males = 1.
CONCLUSION: The equations derived in this study may facilitate the interpretation of the 2MWD in clinical populations in Malaysia, as well as in countries with similar cultural backgrounds to Malaysia.
Study site: volunteers from four villages in the Batu sub-district, Gombak, Malaysia
Schizophrenia is one of the most expensive psychiatric illnesses. This study compared retrospectively health-care resources consumed 12 months before and 24 months after risperidone long-acting injection (RLAI) treatment in Hong Kong. A mirror-image analysis was conducted using data (N=191) from three public hospitals in Hong Kong from 2003 to 2007. The main outcome measure was hospitalisation cost. Other secondary outcomes such as hospitalisation episodes, outpatient visits and adverse events were also compared. A predictive model was established using linear regression based on generalised estimating equations. Analysis showed that RLAI was associated with a reduction in hospitalisation cost by HK$10,001,390 (24.7%) (HK$40,418,694 vs. HK$30,417,303; P-value <0.05). Days of hospitalisation were reduced by 1538 days (10.1%) (15,271 vs. 13,733; P-value <0.05). The predictive model estimated that the hospitalisation cost of patients using RLAI was only 11.1% (3.1-3.93%, 95% confidence interval (CI)) compared to those receiving conventional antipsychotics combined with oral risperidone. Cost of hospitalisation was significantly reduced after RLAI therapy. However, results should be considered as indicative or suggestive only, due to potential channelling bias where certain drug regimens are preferentially prescribed to patients with particular conditions. The findings from our study may be useful in health-care decision making considering treatment options for schizophrenia in resource-limited settings.
The responses of tropical forests to global anthropogenic disturbances remain poorly understood. Above-ground woody biomass in some tropical forest plots has increased over the past several decades, potentially reflecting a widespread response to increased resource availability, for example, due to elevated atmospheric CO2 and/or nutrient deposition. However, previous studies of biomass dynamics have not accounted for natural patterns of disturbance and gap phase regeneration, making it difficult to quantify the importance of environmental changes. Using spatially explicit census data from large (50 ha) inventory plots, we investigated the influence of gap phase processes on the biomass dynamics of four 'old-growth' tropical forests (Barro Colorado Island (BCI), Panama; Pasoh and Lambir, Malaysia; and Huai Kha Khaeng (HKK), Thailand). We show that biomass increases were gradual and concentrated in earlier-phase forest patches, while biomass losses were generally of greater magnitude but concentrated in rarer later-phase patches. We then estimate the rate of biomass change at each site independent of gap phase dynamics using reduced major axis regressions and ANCOVA tests. Above-ground woody biomass increased significantly at Pasoh (+0.72% yr(-1)) and decreased at HKK (-0.56% yr(-1)) independent of changes in gap phase but remained stable at both BCI and Lambir. We conclude that gap phase processes play an important role in the biomass dynamics of tropical forests, and that quantifying the role of gap phase processes will help improve our understanding of the factors driving changes in forest biomass as well as their place in the global carbon budget.