9 research outputs found

    Development of modified double-weight code and its implementation in multi-rate transmissions

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    This paper presents a new code structure and its ability in supporting multiple transmission rates in point to point Spectral Amplitude Coding- Optical Code Division Multiple Access (SAC-OCDMA) links. The Double-Weight (DW) code family that has a basic fixed weight of 2 was proposed. Modified Double Weight (MDW) Code is a DW code family variation that has variable weight of greater than two. The ability of MDW codes to support simultaneous transmissions at different bit rates is shown through simulated results of the bit error rate (BER) and the eye patterns. Four MDW encoded channels were used at the bit rates of 2.5Gbps and 10Gbps. MDW code shown here significantly performs better than Hadamard and Modified Frequency Hopping (MFH) codes

    Performance of radial point interpolation method in solving kinematic wave equation for hydrologic modelling

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    This paper presents the solution of the kinematic wave equation using a meshless radial point interpolation method (RPIM). The partial differential equation is discretized using a Galerkin weighted residual method employing RPIM shape functions. A forward difference scheme is used for temporal discretization, while the direct substitution method is employed to solve the nonlinear system at each time step. The formulation is validated against solutions from conventional numerical techniques and physical observation. In all cases, excellent agreements are achieved and hence the validation of the proposed formulation. Optimum values of the multi-quadrics shape parameters were then determined before the assessment of the performance of the method. Based on the convergence rate, it has been shown that the proposed method performs better than the finite difference method and equivalent to the finite element method. This highlights the potential of RPIM as an alternative method for hydrologic modeling

    Thermal comfort study for classroom in urban and rural schools in Selangor

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    Optimum comfort factors help in enhancing effective learning process in a classroom. The aim of this research is to study thermal comfort in school classroom for a more desirable learning process. Four schools consist of urban and rural schools in Selangor were selected for this study. Field measurement and questionnaires was used to measure the level of comfort and satisfaction of school teacher and student in classroom. Data was collected using Temperature data-loggers (SD500 Humidity/Temperature Data logger). The questionnaire was analysed based on Likert's scale rating. Result from both on-field measurement and questionnaire survey suggests that thermal comfort have greater importance to focus. All the schools tested higher temperature than the recommended value. This study also outlines several improvement suggestions actions for better comfort level such as better air ventilation system and smaller class size

    mTOR Controls Ovarian Follicle Growth by Regulating Granulosa Cell Proliferation

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    We have shown that inhibition of mTOR in granulosa cells and ovarian follicles results in compromised granulosa proliferation and reduced follicle growth. Further analysis here using spontaneously immortalized rat granulosa cells has revealed that mTOR pathway activity is enhanced during M-phase of the cell cycle. mTOR specific phosphorylation of p70S6 kinase and 4E-BP, and expression of Raptor are all enhanced during M-phase. The predominant effect of mTOR inhibition by the specific inhibitor Rapamycin (RAP) was a dose-responsive arrest in the G1 cell cycle stage. The fraction of granulosa cells that continued to divide in the presence of RAP exhibited a dose-dependent increase in aberrant mitotic figures known as anaphase bridges. Strikingly, estradiol consistently decreased the incidence of aberrant mitotic figures. In mice treated with RAP, the mitotic index was reduced compared to controls, and a similar increase in aberrant mitotic events was noted. RAP injected during a superovulation regime resulted in a dose-dependent reduction in the numbers of eggs ovulated. Implications for the real-time regulation of follicle growth and dominance, including the consequences of increased numbers of aneuploid granulosa cells, are discussed

    Use of vitamin supplements and risk of total cancer and cardiovascular disease among the Japanese general population: A population-based survey

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    <p>Abstract</p> <p>Background</p> <p>Despite the popular use of vitamin supplements and several prospective cohort studies investigating their effect on cancer incidence and cardiovascular disease (CVD), scientific data supporting their benefits remain controversial. Inconsistent results may be partly explained by the fact that use of supplements is an inconsistent behavior in individuals. We examined whether vitamin supplement use patterns affect cancer and CVD risk in a population-based cohort study in Japan.</p> <p>Methods</p> <p>A total of 28,903 men and 33,726 women in the Japan Public Health Center-based Prospective Study cohort, who answered questions about vitamin supplement use in the first survey from 1990-1994 and the second survey from 1995-1998, were categorized into four groups (never use, past use, recent use, and consistent use) and followed to the end of 2006 for cancer and 2005 for CVD. Sex-specific hazard ratios (HRs) and 95% confidence intervals (95% CIs) were used to describe the relative risks of cancer and CVD associated with vitamin supplement use.</p> <p>Results</p> <p>During follow-up, 4501 cancer and 1858 CVD cases were identified. Multivariate adjusted analysis revealed no association of any pattern of vitamin supplement use with the risk of cancer and CVD in men. In women, consistent use was associated with lower risk of CVD (HR 0.60, 95% CI 0.41-0.89), whereas past (HR 1.17, 95% CI 1.02-1.33) and recent use (HR 1.24, 95% CI 1.01-1.52) were associated with higher risk of cancer.</p> <p>Conclusions</p> <p>To our knowledge, this is the first prospective cohort study to examine simultaneously the associations between vitamin supplement use patterns and risk of cancer and CVD. This prospective cohort study demonstrated that vitamin supplement use has little effect on the risk of cancer or CVD in men. In women, however, consistent vitamin supplement use might reduce the risk of CVD. Elevated risk of cancer associated with past and recent use of vitamin supplements in women may be partly explained by preexisting diseases or unhealthy background, but we could not totally control for this in our study.</p

    Effect of sea level rise on oil spill model drift using TELEMAC-2D

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    Sea level rise (SLR) is a serious issue around the world that affects the hydrodynamic behaviour of river and coastal waters. This work presents the hydrodynamic pattern modelled for the region and prediction of oil spill spreading at Pulai River estuary and southwest Johor Strait before and after SLR phenomenon using TELEMAC-2D. The hydrodynamic calibration and validation were in good agreement between measured and modelled values. The mean absolute error (MAE) of water level is less than 3% and average difference in speed and direction of current is less than 10% and 30°, respectively. These values meet the impact evaluation assessment by the Department of Irrigation and Drainage (DID), which is less than 10% for water level and less than 30% and 45° for current speed and direction, respectively. Permanent service for mean sea level (PSMSL) analysis shows an increased water level of 0.35 m after SLR rise by year 2100. Currents also increase with the effect of SLR. At the Pulai River, the observed spill trajectory remains the same before and after SLR but in open seas, the affected oil spillage area at the anchorage zone is estimated to increase 28% after SLR compared to 2015. It is predicted that SLR increases water level, currents and oil spill spreading at open seas

    Meshless point interpolation formulation of kinematic wave equation for flood routing

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    This study presents the meshless Point Interpolation Method (PIM) formulation to solve kinematic wave equation for flood routing. It details on Galerkin residual method employing PIM shape functions in discretizing the unsteady partial differential equation. Two nonlinear solvers are considered; Picard and Newton-Raphson. The formulation are verified against both hypothetical data obtained from conventional numerical methods (finite difference and finite element method) and gauged data obtained from an actual river. Close agreements are obtained between the proposed PIM formulation and the conventional methods thus highlight the potential of PIM as an alternative numerical method in the field of hydrologic modelling

    Carbon dioxide storage potential in Malaysian sandstone aquifer: an overview

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    Carbon dioxide (CO2) emission rate from energy industries in Malaysia has increased exponentially in these few years. Based on this alarming increment of CO2 emission rate from previous data, carbon dioxide sequestration in deep saline aquifer has been identified as one of the way to reduce and overcome the increment of CO2 emission rate in Malaysian atmosphere. Malaysian geology consists of enormous amount of deep saline aquifer which most of the aquifer material is sandstone. Malay Basin has been identified as the most potential basin for CO2 sequestration in Malaysia by previous researchers. There are four sites in Malay Basin which has potential to be CO2 sequestration site such as Jerneh, Dulang, Tangga and Semangkok because they contain the formation of fine-grained sandstone, mudstone and coal properties. This paper aims to discuss CO2 storage potential in Malaysian sandstone aquifer particularly Malay Basin in terms of potential injection location, properties of Malaysian sandstone aquifer, available technologies of injection, injection parameter as well as issues and challenges of carbon sequestration implementation in Malaysia
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