Introduction: Water based Metalworking fluids (MWF) are commonly used in machining industries and are excellent media for microorganism growth. The study aimed at determining the relationship between the airway inflammation as indicated by fractional exhaled nitric oxide (FeNO) with the microbial contaminants of MWF in aerosol and bulk sample as well as the workers’ reported respiratory health symptoms. Methods: This cross sectional study was carried out on 138 machining workers. Their FeNO were measured using NIOX-MINO instrumentation. The microbial as- sessments of bacteria and fungus were carried out on the MWF bulk samples and the aerosol using a sampler DUO SAS SUPER 360TM. Results: Findings showed significant difference in the FeNO levels in workers from various job sections (p=0.01). Significant relationships found between high FeNO levels with their closeness to the machines (p=0.03), high number of machines in the workplaces (p=0.02), high environmental bacteria colonies (p=0.04), lon- ger employment years (p
Introduction: Noise was evident to reduce job satisfaction among workers which will negative impacts to workers including increase job turnover, decrease motivation and increased number of accidents. This study aims to explore job satisfaction and its risk factors among workers working in a noisy workplace. Method: The study design was cross-sectional study which involved 167 workers in a cable manufacturing factory selected by simple random sam- pling. MSQ was used to assess employee’s satisfaction with their job on seven facets and sound level meter was used to measure workplace noise level. Results: All respondents were exposed to noise above permissible exposure limit. Most workers (49%) were moderately satisfied with their work. Factors that were rated as lowest level of satisfaction were work itself (the ability to work alone) (40%) and the way company system policies are implemented (40%). Factors with the highest level of satisfaction were their freedom to implement their judgement (responsibility) (51%) and the supervision quality of their superiors (51%). The most dominant facet predicting total satisfaction level was recognition followed by advancement and company policy and administration. All variables in socio-demographical and job characteristics were not significantly associated with their level of job satisfaction except noise. Noise was significant in predicting one facet of job satisfaction which was physical work condition. Conclusion: Overall, the average level of job satisfaction among respondents were moderate and they were exposed to occupational noise which was the only significant study variable correlated with their job satisfaction.
MeSH terms: Accidents; Cross-Sectional Studies; Freedom; Humans; Job Description; Job Satisfaction; Judgment; Motivation; Noise, Occupational; Personal Satisfaction; Personnel Turnover; Surveys and Questionnaires; Risk Factors; Workplace; Manufacturing and Industrial Facilities
Introduction: Malaysian traffic police are always working on the public roads to alleviate traffic congestion and therefore exposed them to the polluted air every day. In particular, polluted air containing PM2.5 is dangerous to their respiratory health as they can penetrate deep into the lungs, leading to bronchitis, lung cancer and many more. Hence, this research examined the relationship of personal exposure level to PM2.5 with respiratory symptoms among traffic policemen in Kuala Lumpur and Johor Bahru. Methods: 134 participants among traffic policemen were agreed to participate in this study. They were requested to complete a questionnaire regarding the sociodemographic back- ground and respiratory health information. The questionnaire was adopted from International Union Against Tuber- culosis Lung Diseases (1986). Personal exposure level of PM2.5 was measured using an air pump with 5.0µm pore size PVC filter. Results: The mean exposure level of PM2.5 among traffic policemen was 28.69 µg/m3. It was found that some of them possess respiratory symptoms (Coughing 33.6%, Phlegm 25.4%, Wheezing 14.9% and Shortness of breath 32.1%). There was significant association detected at p-value < 0.05 in coughing. Despite, there was no significant association in other symptoms such as phlegm, wheezing and shortness of breath. Conclusions: Traffic police were exposed to a relatively high level of PM2.5 (12.4 µg/m3 to 55.3 µg/m3) and showed symptoms of respi- ratory effects. Therefore, recognition of the risks connected with occupational lung disease and exposure monitoring must be a high priority. This baseline data can serve as a reference to the top management of traffic police officers in order to develop an occupational safety and health guideline for police officers as required by Occupational Safety and Health Act (OSHA, Act 514 1994).
MeSH terms: Air Pollution; Bronchitis; Dyspnea; Humans; Lung; Lung Neoplasms; Occupational Diseases; Polyvinyl Chloride; Surveys and Questionnaires; Respiratory Sounds; United States; United States Occupational Safety and Health Administration; Occupational Health; Police; Particulate Matter
Introduction: Exposure of PM2.5 and PM10 released from combustion of biomass activity caused respiratory health among children. Objective: This study aims to determine the association between exposure of PM2.5 and PM10 with DNA damage in primary school children living nearby palm oil combustion activity at Semenyih. Methods: A cross sectional comparative study were conducted among Malay primary school children in school A located 2.7km from palm oil activity (N=82) and school B located about 40km away from the palm oil area (N=85). A standardized ques- tionnaire were distributed to respondent’s parents. Concentrations of PM2.5 and PM10 were measured by using Dust Trak DRX Aerosol Monitor Model 8534 and Escort LC Personal Sampling Pump. Measurement of indoor and outdoor air pollutants were conducted in schools and home. Buccal cells were collected, which then followed by micronu- cleus assay. Results: Concentration of PM10 and PM2.5 at home of studied group were significantly higher compared to comparative group with p value (p=0.007) and (p=0.018) respectively. PM10 and PM2.5 of studied schools were significantly higher compared to comparative schools with p value (p=0.014) and (p=0.04) respectively. MN fre- quencies of studied group were significantly higher compared to comparative group (p=0.001). Significant difference of respiratory symptoms were found between two groups which are cough, phlegm, wheezing and chest tightness (p=0.001). There were significant correlation between PM10 with MN frequency of studied group and comparative group with r= 0.562; p=0.001. Conclusion: This study indicated that the exposure of PM10 and PM2.5 would increase the risk of having respiratory health symptoms and might induce the micronuclei formation among children who lived near palm oil activity area.
MeSH terms: Aerosols; Air Pollutants; Child; Cough; Cross-Sectional Studies; DNA Damage; Dust; Humans; Malaysia; Mouth Mucosa; Parents; Surveys and Questionnaires; Respiratory Sounds; Schools; Biomass
Introduction: The increased use of mobile phones has increased the mobile base stations (MBS) deployment. While understanding of radiation protection is growing among the public, questions regarding early-life exposure to ra- diofrequency radiation (RFR) from MBS in children are of importance as to whether it will raise the chances of developing chronic diseases during adulthood. Taking into account the sitting location of MBS, the purpose of this study is to evaluate the chromosomal DNA damage in buccal mucosal cells between school children exposed to RFR emitted from base station antennas. Method: This is a comparative cross-sectional study in which two group of school children were sampled i.e. exposed groups are children whose school located near MBS (200 meters); un- exposed groups are children whose school located distant far from the MBS (>200 meters). Digital RF Analyzer was used to measure RFR at the school surrounding. Buccal mucosa cells from the oral cavity were sampled to examine the level of micronuclei (MN) frequencies. Results: This study found that the densities of the RFR energy differed in range. Although all measurements showed the RFR reading below the acceptable exposure level, there were still sig- nificant variations at each location assessed. Statistically, the MN frequency is significantly different when compared to the exposed and non-exposed group. Conclusion: To understand the mechanism of health effects from exposure to low-level RFR emited from MBS, further study should consider environmental factors influencing MBS sitting on RFR emission, as well as examining the health effects into molecular levels.
Introduction: School environment represents an important microenvironment for students who spend 6-8 hours in classrooms. Indoor air quality is linked to several respiratory diseases in the school age group. This research aims to study indoor air quality of schools at different environmental characteristic and assess its health risks to students. Methods: This research measured air quality (PM2.5, PM10, CO2 , and HCHO) in three junior high schools and followed by health risk assessment. Results: This research found that the mean or median level of indoor PM2.5 and PM10 in all three schools exceeded the standard value with health risks (HQ> 1) for PM2.5 in all three schools and PM10 in two schools. Whereas carbon dioxide and formaldehyde concentrations were still safe and did not inflict health risks (HQ < 1). The scenario for managing the health risk of PM2.5 and PM10 exposure was to control the exposure at a safe threshold of PM2.5 0.035 mg/m3 ; 0.043 mg/m3 and PM10 0.144 mg/m3 for most of the population at normal school time. Conclusion: It was concluded that the level of indoor particulate matters indicates poor indoor air quality in all three schools at different environmental characteristic and inflicts health risk on students so that the health risk management is required.
MeSH terms: Air Pollution; Carbon Dioxide; Formaldehyde; Humans; Schools; Students; Air Pollution, Indoor; Risk Assessment; Particulate Matter
Successful oil palm plantation should have high profit, clean and environmental friendly. Since oil palm trees have a long life and it takes years to be fully grown, controlling the felling rate of the oil palm trees is a fundamental challenge. It needs to be addressed in order to maximize oil production. However, a good arrangement of the felling of the oil palm trees may also affect the amount of carbon absorption. The objec- tive of this study is to develop an optimal felling model of the oil palm plantation system taking into account both oil production and carbon absorption. The model facilitates in providing the optimal control of felling rate that results in maximizing both oil produc- tion and carbon absorption. With this aim, the model is formulated considering oil palm biomass, carbon absorption rate, oil production rate and the average prices of carbon and oil palm. A set of real data is used to estimate the parameters of the model and numerical simulation is conducted to highlight the application of the proposed model. The resulting parameter estimation that leads to an optimal control of felling rate problem is solved.
Let G be a dihedral group and ??cl G its conjugacy class graph. The Laplacian energy of the graph, LE(??cl G) is defined as the sum of the absolute values of the difference between the Laplacian eigenvalues and the ratio of twice the edges number divided by the vertices number. In this research, the Laplacian matrices of the conjugacy class graph of some dihedral groups, generalized quaternion groups, quasidihedral groups and their eigenvalues are first computed. Then, the Laplacian energy of the graphs are determined.
Since rice is a staple food in Malaysia, its price fluctuations pose risks to the producers, suppliers and consumers. Hence, an accurate prediction of paddy price is essential to aid the planning and decision-making in related organizations. The artificial neural network (ANN) has been widely used as a promising method for time series forecasting. In this paper, the effectiveness of integrating empirical mode decomposition (EMD) into an ANN model to forecast paddy price is investigated. The hybrid method is applied on a series of monthly paddy prices from February 1999 up to May 2018 as recorded in the Malaysian Ringgit (MYR) per metric tons. The performance of the simple ANN model and the EMD-ANN model was measured and compared based on their root mean squared Error (RMSE), mean absolute error (MAE) and mean percentage error (MPE). This study finds that the integration of EMD into the neural network model improves the forecasting capabilities. The use of EMD in the ANN model made the forecast errors reduced significantly, and the RMSE was reduced by 0.012, MAE by 0.0002 and MPE by 0.0448.
The hydromagnetic mixed convection flow of Cassonnano fluid under the influence of chemical reaction,thermal radiation and heat generation or absorption is investigated. The flow is induced due to unsteady nonlinearly stretching sheet saturated in a porous medium. The governing nonlinear coupled partial differential equations are converted into the system of coupled ordinary differential equations using similarity transformations and then solved numerically via Keller box method. The effects of pertinent parameters on velocity, temperature and nanoparticles concentration as well as wall shear stress, heat and mass transfer rate are analyzed and displayed graphically. The results for skin friction coefficient and local Nusselt number are compared with previously published work and found to be in good agreement. Findings demonstrate that increase in Casson parameter enhanced the friction factor and heat transfer rate. It is noticed that the heat transfer rate is declined with increment in Brownian motion and thermophoresis parameters. The nanoparticles concentration is seen to be higher in generative chemical reaction and opposite effect is observed in destructive chemical reaction. Increase in unsteadiness parameter decreased the fluid velocity, temperature and nanoparticles concentration. The magnitude of wall shear stress is also reduced with increase in unsteadiness and porous medium parameters.
Invadopodia are finger-like protrusions located at subcellular membrane which can lead to cancer cell invasion. The formation of invadopodia involves several steps such as actin polymerizations, degradation of extracellular matrix which produce ligand and signal stimulation that is occurred from the binding of ligand with epidermal growth factor receptor. In this paper, a mathematical model of signal transduction is investigated. Both signal and ligand are represented by Laplace equation with Dirichlet boundary condition for each region. The cell membrane is treated as free boundary surface to separate any activity that occurred in intracellular and extracellular regions. The motion of the interface is taken as gradient of interior signal and the cell membrane is set as zero level set function. The problem is solved numerically using finite difference scheme of upwind, interpolation and extrapolation methods. The results showed that the formation of invadopodia is formed when protrusions exist on the cell membrane.
In this paper, the problem of forced convection flow of micropolar fluid of
lighter density impinging orthogonally on another heavier density of micropolar fluid
on a stretching surface is investigated. The boundary layer governing equations are
transformed from partial differential equations into a system of nonlinear ordinary
differential equations using similarity transformation and solved numerically using dsolve
function in maple software version 2016. The velocity, microrotation and temperature of
micropolar fluid are analyzed. It is found that both upper fluid and lower fluid display
opposite behaviour when micropolar parameter k various with strong concentration
n = 0, pr = 7 and stretching parameter = 0.5. The results also show that stretching
surface exert the force that increasing the velocity of micropolar fluid.
Subsea cable laying is a risky and challenging operation faced by engineers, due to many uncertainties arise during the operation. In order to ensure that subsea cables are laid out diligently, the analysis of subsea cable tension during the laying operation is crucial. This study focuses on the fatigue failure of cables that will cause large hang-off loads based on catenary configuration after laying operation. The presented problem was addressed using mathematical modelling with consideration for a number of defining parameters, which include external forces such as current velocity and design parameters such as cable diameter. There were two types of subsea cable tension analyses studied: tensional analysis of catenary configurations and tensional analysis of lazy wave configurations. The latter involved a buoyancy module that was incorporated in the current catenary configuration that reduced subsea cable tension and enhanced subsea cable lifespan. Both analyses were solved using minimization through the gradient- based approach concerning on the tensional analysis of the subsea cable in different configurations. Lazy wave configurations were shown to successfully reduce cable tension, especially at the hang-off section.
In numerical methods, boundary element method has been widely used to solve
acoustic problems. However, it suffers from certain drawbacks in terms of computational
efficiency. This prevents the boundary element method from being applied to large-scale
problems. This paper presents proposal of a new multiscale technique, coupled with
boundary element method to speed up numerical calculations. Numerical example is
given to illustrate the efficiency of the proposed method. The solution of the proposed
method has been validated with conventional boundary element method and the proposed
method is indeed faster in computation.
Let g be a finite group and s be a subset of g, where s does not include
the identity of g and is inverse closed. A cayley graph of a group g with respect to the
subset s is a graph, where its vertices are the elements of g and two vertices a and b
are connected if ab-1 is in the subset s. The energy of a cayley graph is the sum of all
absolute values of the eigenvalues of its adjacency matrix. In this paper, we consider a
specific subset s = {b, ab, . . . , An-1b} for dihedral groups of order 2n, where n 3 and find
the cayley graph with respect to the set. We also calculate the eigenvalues and compute
the energy of the respected cayley graphs. Finally, the generalization of the energy of the
respected cayley graphs is found.
This study presents a two-strain deterministic model which incorporates Dengvaxia vaccine and insecticide (adulticide) control strategies to forecast the dynamics of transmission and control of dengue in Madeira Island if there is a new outbreak with a different virus serotypes after the first outbreak in 2012. We construct suitable Lyapunov functions to investigate the global stability of the disease-free and boundary equilibrium points. Qualitative analysis of the model which incorporates time-varying controls with the specific goal of minimizing dengue disease transmission and the costs related to the control implementation by employing the optimal control theory is carried out. Three strategies, namely the use of Dengvaxia vaccine only, application of adulticide only, and the combination of Dengvaxia vaccine and adulticide are considered for the controls implementation. The necessary conditions are derived for the optimal control of dengue. We examine the impacts of the control strategies on the dynamics of infected humans and mosquito population by simulating the optimality system. The disease-free equilibrium is found to be globally asymptotically stable whenever the basic reproduction numbers associated with virus serotypes 1 and j (j ∈ {2,3,4}), respectively, satisfy R01,R0j ≤ 1, and the boundary equilibrium is globally asymptotically stable when the related R0i (i = 1,j) is above one. It is shown that the strategy based on the combination of Dengvaxia vaccine and adulticide helps in an effective control of dengue spread in the Island.
Let g be a finite group. The probability of a random pair of elements in g are
said to be co-prime when the greatest common divisor of order x and y where x and y in
g, is equal to one. Meanwhile the co-prime graph of a group is defined as a graph whose
vertices are elements of g and two distinct vertices are adjacent if and only if the greatest
common divisor of order x and y is equal to one. In this paper, the co-prime probability
and its graphs such as the types and the properties of the graph are determined.
Price stability is one of the main policy objectives that is targeted by policymakers in many countries. Price uncertainty occurs due to the changes in market structure and consumer preference and expectation, which may affect price stability. In this study, the researchers aimed to examine the effects of price uncertainty of consumer price disaggregation in Malaysian sectors. To be specific, the researchers were seeking to discover on how domestic and global commodity prices can affect sectoral Consumer Price Index (CPI) on price inflation in Malaysia and most importantly, whether the effect is different for economic sectors in Malaysia. In addition, the effects of other factors (i.e., internal and external factors) on Malaysian sectoral CPI inflation were also studied. The threshold generalized autoregressive conditional heteroscedasticity (TGARCH) model was used to generate the price uncertainties. For the purpose of analysis, the threshold regression approach was applied based on time series of each single sector, followed by a combination of panel data of all sectors. The results differed across sectors, revealing that the impact of price uncertainties was determined by the sensitivity of each sector towards the price uncertainties. The effect of price increase is larger than the effect of price decrease. Price fluctuations were obvious in sectors that were dependent on consumer price or commodity price. Exchange rate and oil price inflation had also greatly influenced the CPI inflation.
The effect of oil shock on the global economy is evident through many studies. However, the effect is heterogeneous over time. One of the reasons that lead to such different impacts is due to the oil source that is either the oil shock is demand or supply- driven. Applying the structural vector autoregressive (SVAR) model to generate the three oil shocks based on the three oil sources (oil supply, oil demand and oil specific- demand), we extended the examination on the effect of oil shock on the global economy using the threshold regression. Our results reveal the threshold effects of oil directly and indirectly on the global economy. The impacts of oil shocks differ across sectors, implying oil intensity, as well as oil sources, are the factors that determine the impact of oil shocks on the global economy. Overall, the oil specific-demand shock is more influential among the three oil shocks. Hence, the global economy is oil demand-driven. Besides that, the impact of oil is relatively large in the energy sector when compared to the non-energy sector and precious metals industry. Despite that, the impact of oil shocks is small if compared to the non-oil shocks such as exchange rate changes and global consumer price inflation shock. Consequently, non-oil shocks are the main determinants of the global economic fluctuation. The study leads to a better understanding of the transmission of oil shock and its sources, the interaction between oil and economic indicators and the policy implication due to oil dependency/ intensity.
Abstract Demographers and actuaries are very much conscious of the trend of mortality in their own country or in the world in general. This is because mortality is the basis for longevity risk evaluation. Mortality is showing a declining trend and it is expected to further decline in the future. This will lead to continuous increase in life expectancy. Several stochastic models have been developed throughout the years to capture mortality and its variability. This includes Lee Carter (LC) model which has been extended by various researchers. This paper will be focusing on comparing LC model and another mortality model proposed by Cairns, Blake and Dowd (CBD). The LC uses the log of central rate of mortality and CBD uses logit of the mortality odds as dependent variable. Analysis of comparison is done using a few techniques including Akaike information criteria (AIC) and Bayesian information criterion (BIC). From the overall results, there is no model better than the other in every aspect tested. We illustrate this via visual inspection and in sample and outof sample analysis using Malaysian mortality data from 1980 to 2017.