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Kuala Selangor, Malaysia

The National University of Malaysia Pusat Perubatan Universiti Kebangsaan Malaysia is located in Cheras and also has a branch campus in Kuala Lumpur. There are 17,500 undergraduate students enrolled, and 5,105 postgraduate students of which 1368 are foreign students from 35 countries.Universiti Kebangsaan Malaysia is one of five research universities in the country. It was ranked number 259th in the world by QS World University Rankings in 2014. It is ranked 98th place in the 100 best new universities established within the last 50 years in the world. It is the only university from Malaysia that made it in the 2012 Quacquarelli Symonds Top 50 Universities Under 50 Years Old list ranked in the 31st place. It placed 53rd and 58th in the QS Top 500 Asian University Rankings in 2011 and 2012 respectively. Wikipedia.

Shabri A.B.,University of Technology Malaysia | Daud Z.M.,University of Technology Malaysia | Ariff N.M.,National University of Malaysia
Theoretical and Applied Climatology | Year: 2011

Information related to distributions of rainfall amounts are of great importance for designs of water-related structures. One of the concerns of hydrologists and engineers is the probability distribution for modeling of regional data. In this study, a novel approach to regional frequency analysis using L-moments is revisited. Subsequently, an alternative regional frequency analysis using the TL-moments method is employed. The results from both methods were then compared. The analysis was based on daily annual maximum rainfall data from 40 stations in Selangor Malaysia. TL-moments for the generalized extreme value (GEV) and generalized logistic (GLO) distributions were derived and used to develop the regional frequency analysis procedure. TL-moment ratio diagram and Z-test were employed in determining the best-fit distribution. Comparison between the two approaches showed that the L-moments and TL-moments produced equivalent results. GLO and GEV distributions were identified as the most suitable distributions for representing the statistical properties of extreme rainfall in Selangor. Monte Carlo simulation was used for performance evaluation, and it showed that the method of TL-moments was more efficient for lower quantile estimation compared with the L-moments. © 2011 Springer-Verlag.

Ab-Rahman M.S.,National University of Malaysia
Optica Applicata | Year: 2014

Optical amplifiers are realised in a wide range of applications, such as metro - dense wavelength division multiplexing and cable television networks. These applications require the amplifier to provide a maximum output power level by accepting an input power near the saturation level. To obtain an ideal amplifier according to several parameters, the erbium concentration in the composite core glass, the optimum length of the fibre, the pump saturation and the input signal signalto- noise ratio must be critically studied and addressed. In this paper, we will review the types of optical amplifiers used in communication systems today as well as the parameters that limit the performance of optical amplifiers in the network, such as the noise figure, the gain saturation, the polarisation dependence gain and inhomogeneous broadening effects. Based on the performance limitation factor, we model the amplifier gain profile and the effect of the gain value on the network performance. Finally, we propose various configurations of an optical amplifier, and the advantages of each amplification technique are highlighted. © Copyright 2007 T.Przerwa-Tetmajer All Rights Reserved 2007.

Tham L.,University of Malaysia, Kelantan | Nazar R.,National University of Malaysia | Pop I.,Babes - Bolyai University
Journal of Heat Transfer | Year: 2013

In this paper, the steady mixed convection boundary layer flow past a horizontal circular cylinder with a constant surface temperature embedded in a porous medium saturated by a nanofluid containing both nanoparticles and gyrotactic micro-organisms in a stream flowing vertically upwards for both cases of a heated and cooled cylinder is numerically studied. The resulting system of nonlinear partial differential equations is solved numerically using an implicit finite-difference scheme. By considering the governing parameters, namely, the mixed convection parameter λ, the bioconvection Lewis number Lb, the traditional Lewis number Le, the bioconvection Péclet number Pb, the buoyancy ratio Nr, the bioconvection Rayleigh number Rb, the Brownian motion Nb, and the thermophoresis Nt, the numerical results are obtained and discussed for the skin friction coefficient, the local Nusselt number, the local Sherwood number, the local density number of the motile micro-organisms as well as the velocity, temperature, nanoparticle volume fraction, and density motile micro-organisms profiles. Copyright © 2013 by ASME.

Yacob N.A.,University Technology of MARA | Ishak A.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca | Vajravelu K.,University of Central Florida
Nanoscale Research Letters | Year: 2011

The problem of a steady boundary layer shear flow over a stretching/shrinking sheet in a nanofluid is studied numerically. The governing partial differential equations are transformed into ordinary differential equations using a similarity transformation, before being solved numerically by a Runge-Kutta-Fehlberg method with shooting technique. Two types of nanofluids, namely, Cu-water and Ag-water are used. The effects of nanoparticle volume fraction, the type of nanoparticles, the convective parameter, and the thermal conductivity on the heat transfer characteristics are discussed. It is found that the heat transfer rate at the surface increases with increasing nanoparticle volume fraction while it decreases with the convective parameter. Moreover, the heat transfer rate at the surface of Cu-water nanofluid is higher than that at the surface of Ag-water nanofluid even though the thermal conductivity of Ag is higher than that of Cu. © 2011 Yacob et al.

Mandeep J.S.,National University of Malaysia
International Journal of Physical Sciences | Year: 2011

This paper compares predicted monthly scintillation means of nine scintillation prediction models to the monthly mean of the empirical data collected from the beacon receiver located at Universiti Sains Malaysia (USM). Tropospheric scintillation is a phenomenon where a rapid fluctuation of signal happens due to the turbulence at the atmosphere. The tropospheric scintillation models which use to compare to the actual scintillation data are Ortigies T, DPSP, MPSP and KVS. The ground station of the satellite system has a frequency of 12.255 GHz and elevation angle of 40.1° and the data is gathered from January 2002 till December 2007. The scintillation amplitude of each prediction model is plotted into graph and the percentage of error is calculated to analyze the different between the actual scintillation data and prediction model in Northern Malaysia. The findings show the Ortgies-T gives the best fit result among the others in Northern Malaysia. © 2011 Academic Journals.

Choudhury P.K.,National University of Malaysia | Soon W.K.,Multimedia University
Optik | Year: 2011

A three-layer liquid crystal tapered optical fiber (LCTF) is investigated with the emphasis on the power confinements by the low order TE and TM modes sustained in the different sections of LCTF. The outermost clad section is considered to be made of liquid crystal with radial anisotropy whereas the core and the inner clad are dielectric regions. Rigorous field expressions in the different LCTF sections are deduced, and the plots of power confinement factors (or the relative distributions) are ultimately made considering different fiber dimensions. The results reveal that the TE modes confine maximum amount of power in the outermost liquid crystal region, which is attributed to the radial anisotropy of the section. Such features of LCTFs attract their usefulness in the area of field coupling devices and optical sensing where evanescent field technique is primarily implemented. © 2010 Elsevier GmbH. All rights reserved.

Bachok N.,University Putra Malaysia | Ishak A.,National University of Malaysia | Ishak A.,University of Malaya | Pop I.,Technical University of Cluj Napoca
Physica B: Condensed Matter | Year: 2011

The steady flow of an incompressible viscous fluid due to a rotating disk in a nanofluid is studied. The transformed boundary layer equations are solved numerically by a finite difference scheme, namely the Keller-box method. Numerical results for the flow and heat transfer characteristics are obtained for various values of the nanoparticle volume fraction parameter φ and suction/injection parameter h0. Two models for the effective thermal conductivity of the nanofluid, namely the MaxwellGarnett model and the Patel model, are considered. It is found that for the Patel model, the heat transfer rate at the surface increases for both suction and injection, whereas different behaviors are observed for the MaxwellGarnett model, i.e. increasing the values of φ leads to a decrease in the heat transfer rate at the surface for suction, but increases for injection. The results of this study can be used in the design of an effective cooling system for electronic components to help ensure effective and safe operational conditions. © 2011 Elsevier B.V. All rights reserved.

Murray S.W.,Boston University | Campbell P.,University of Arizona | Kingston T.,Texas Tech University | Zubaid A.,National University of Malaysia | And 2 more authors.
Molecular Phylogenetics and Evolution | Year: 2012

Old World leaf-nosed bats (Hipposideridae) are among the most widespread and ecologically diverse groups of insectivorous bats in the Old World tropics. However, phylogenetic relationships in Hipposideridae are poorly resolved at both the generic and species levels, and deep genetic divergence within several Southeast Asian species suggests that current taxonomy underestimates hipposiderid diversity in this region. We used mitochondrial and nuclear sequence data to conduct the first extensive molecular phylogenetic analysis of Southeast Asian hipposiderid bats. Inclusion of multiple samples per taxon allowed testing for evidence of evolutionarily distinct lineages within taxa currently defined as single species. In contrast to earlier phylogenies based on morphometrics, molecular data support monophyly of Hipposideros, but are ambiguous regarding the monophyly of Hipposideridae. With a few exceptions, molecular data also support currently recognized species groups classified by qualitative morphological characters. Widespread paraphyly and polyphyly within many currently recognized species of Hipposideros indicates that evolutionary diversity in the genus is underrepresented by current nomenclature. Comparison of available morphological and echolocation data suggest that both geographic isolation and ecological selection have contributed to the diversification of Southeast Asian hipposiderid bats. © 2011 Elsevier Inc.

Moghadasi S.I.,University of Malaya | Ravana S.D.,University of Malaya | Raman S.N.,National University of Malaysia
Journal of Informetrics | Year: 2013

For a system-based information retrieval evaluation, test collection model still remains as a costly task. Producing relevance judgments is an expensive, time consuming task which has to be performed by human assessors. It is not viable to assess the relevancy of every single document in a corpus against each topic for a large collection. In an experimental-based environment, partial judgment on the basis of a pooling method is created to substitute a complete assessment of documents for relevancy. Due to the increasing number of documents, topics, and retrieval systems, the need to perform low-cost evaluations while obtaining reliable results is essential. Researchers are seeking techniques to reduce the costs of experimental IR evaluation process by the means of reducing the number of relevance judgments to be performed or even eliminating them while still obtaining reliable results. In this paper, various state-of-the-art approaches in performing low-cost retrieval evaluation are discussed under each of the following categories; selecting the best sets of documents to be judged; calculating evaluation measures, both, robust to incomplete judgments; statistical inference of evaluation metrics; inference of judgments on relevance, query selection; techniques to test the reliability of the evaluation and reusability of the constructed collections; and other alternative methods to pooling. This paper is intended to link the reader to the corpus of 'must read' papers in the area of low-cost evaluation of IR systems. © 2012 Elsevier Ltd.

Nabil S.,National University of Malaysia | Samman N.,University of Hong Kong
International Journal of Oral and Maxillofacial Surgery | Year: 2012

This review examines the effect of publishing case reports on journal impact factor and future research. All case reports published in the four major English language oral and maxillofacial surgery journals in the two year period, 2007-2008, were searched manually. The citation data of each case report were retrieved from the ISI online database. The number, percentage and mean citations received by case reports and their relation to the 2009 journal impact factor were analysed. Case reports which received more than 5 citations were also identified and all of the citing articles retrieved and analysed. Thirty-one percent of all articles published in major oral and maxillofacial journals in 2007-2008 were case reports. Case reports had a low citation rate with a mean citation of less than 1. There were 38 (7.2%) case reports with more than 5 citations and 30% of the citing articles were also case reports. The publication of case reports negatively affected journal impact factor which correlated directly with the percentage of case reports published within a journal. Case reports reporting recent topics, describing new treatment/diagnosis method and with a literature review were more likely to receive citations. © 2012 International Association of Oral and Maxillofacial Surgeons.

Bachok N.,University Putra Malaysia | Ishak A.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
Nanoscale Research Letters | Year: 2011

An analysis is carried out to study the steady two-dimensional stagnation-point flow of a nanofluid over a stretching/shrinking sheet in its own plane. The stretching/shrinking velocity and the ambient fluid velocity are assumed to vary linearly with the distance from the stagnation point. The similarity equations are solved numerically for three types of nanoparticles, namely copper, alumina, and titania in the water-based fluid with Prandtl number Pr = 6.2. The skin friction coefficient, Nusselt number, and the velocity and temperature profiles are presented graphically and discussed. Effects of the solid volume fraction ø on the fluid flow and heat transfer characteristics are thoroughly examined. Different from a stretching sheet, it is found that the solutions for a shrinking sheet are non-unique. © 2011 Bachok et al; licensee Springer.

Chowdhury R.H.,National University of Malaysia
Sensors (Basel, Switzerland) | Year: 2013

Electromyography (EMG) signals are becoming increasingly important in many applications, including clinical/biomedical, prosthesis or rehabilitation devices, human machine interactions, and more. However, noisy EMG signals are the major hurdles to be overcome in order to achieve improved performance in the above applications. Detection, processing and classification analysis in electromyography (EMG) is very desirable because it allows a more standardized and precise evaluation of the neurophysiological, rehabitational and assistive technological findings. This paper reviews two prominent areas; first: the pre-processing method for eliminating possible artifacts via appropriate preparation at the time of recording EMG signals, and second: a brief explanation of the different methods for processing and classifying EMG signals. This study then compares the numerous methods of analyzing EMG signals, in terms of their performance. The crux of this paper is to review the most recent developments and research studies related to the issues mentioned above.

Hassan N.,National University of Malaysia
International Journal of Mathematics and Computers in Simulation | Year: 2016

A mathematical programming model is built to optimize the allocation of students into academic programs of a department. The mathematical programming model takes into account the limits of space capacity, financial allocation, the number of instructors and affirmative action quotas as goal constraints that are required to be fulfilled. Each constraint has a priority level and a weight attached. This goal programming model is then applied to the School of Mathematical Sciences, Universiti Kebangsaan Malaysia. The results of the preemptive goal programming model are then compared to that of the weighted non-preemptive goal programming model and current allocation using the weighted mean absolute percentage error. The successful application demonstrates the ability of the mathematical programming model to comply with the student intake requirement and goal constraints of the academic programs. © 2016, North Atlantic University Union. All rights reserved.

Halim A.A.,National University of Malaysia | Aziz H.A.,Universiti Sains Malaysia | Johari M.A.M.,Universiti Sains Malaysia | Ariffin K.S.,Universiti Sains Malaysia
Desalination | Year: 2010

Chemical oxygen demand (COD) and ammoniacal nitrogen have always been the crucially problematic parameters in landfill leachate treatment. This study was conducted to investigate the adsorption properties of ammoniacal nitrogen and COD in semi-aerobic leachate from the Pulau Burung landfill site on zeolite, activated carbon and a new composite media in terms of adsorption isotherm and kinetic. The results show that all adsorbents fitted well with both Langmuir and Freundlich isotherms (R2N0.9) for ammonia adsorption. A comparison study indicated that the adsorption capacity of composite adsorbent towards ammoniacal nitrogen was higher than zeolite and activated carbon and comparable to activated carbon for COD. Findings from a kinetic study indicated that the adsorption of ammonia on new composite adsorbent and zeolite follow almost all kinetic models such as pseudo-first-order, pseudo-second-order, Elovich and intra-particle diffusion model, although pseudo-second-order was the most dominant. COD adsorption fitted well with the pseudo-second-order kinetic model, while activated carbon obeys the pseudo-first-order and intra-particle models. © 2010 Elsevier B.V. All rights reserved.

Ali F.,National University of Malaysia
Electronic Journal of Geotechnical Engineering | Year: 2011

Malaysia is located in a tropical region, known to have an extremely high annual rainfall which frequently triggered a landslide. If a landslide early warning system to be developed in Malaysia, it should be implemented based on empirical correlation of rainfall data and landslide cases. The proposed method is more economical compared to physically based approach. In this paper, two types of empirical rainfall thresholds are discussed i.e. (i) Intensity vs Duration (ID) and (ii) Intensity vs Working Rainfall. Three attempts to correlate rainfall and landslides empirically in Malaysia are presented and discussed. Intensity vs Duration (ID) method was used for Ampang / Hulu Kelang and Penang areas whereas Intensity vs Working Rainfall method was used for Cameron Highland area. © 2011 ejge.

Zin A.M.,National University of Malaysia
Asian Journal of Information Technology | Year: 2011

End-user programming refers to programming activities carried out by end users. These end-users can include teachers, accountants, scientists, engineers, parents and all other people who are not trained as programmers. End-user programming is now getting more popular. It was projected that the number of end-user programmers in the US is about 55 million compared to 2.75 million professional programmers. In order to support end-user programming, a number of programming systems have been developed which can be divided into the following categories: Application-specific languages, programming by example, visual programming and natural programming. This study discusses the concept of a new programming system to support end-user programming called the block-based programming system. In this programming environment, end-users can develop applications by integrated programming blocks that have been developed by block developers. © Medwell Journals, 2011.

Based on a consideration of the interrelationships between cooperation, institutions and governance, this article explores the governance of transboundary wetlands, or wetlands within transboundary basins, and the potential role of the Convention on Wetlands of International Importance, especially as Waterfowl Habitat (Ramsar Convention) in the promotion of transboundary water cooperation. © 2014, © 2014 International Water Resources Association.

Hatamlou A.,Islamic Azad University at Khoy | Hatamlou A.,National University of Malaysia
Information Sciences | Year: 2013

Nature has always been a source of inspiration. Over the last few decades, it has stimulated many successful algorithms and computational tools for dealing with complex and optimization problems. This paper proposes a new heuristic algorithm that is inspired by the black hole phenomenon. Similar to other population-based algorithms, the black hole algorithm (BH) starts with an initial population of candidate solutions to an optimization problem and an objective function that is calculated for them. At each iteration of the black hole algorithm, the best candidate is selected to be the black hole, which then starts pulling other candidates around it, called stars. If a star gets too close to the black hole, it will be swallowed by the black hole and is gone forever. In such a case, a new star (candidate solution) is randomly generated and placed in the search space and starts a new search. To evaluate the performance of the black hole algorithm, it is applied to solve the clustering problem, which is a NP-hard problem. The experimental results show that the proposed black hole algorithm outperforms other traditional heuristic algorithms for several benchmark datasets. © 2012 Elsevier Inc. All rights reserved.

Williamson F.,National University of Malaysia
British Journal for the History of Science | Year: 2015

This article explores meteorological interest and experimentation in the early history of the Straits Settlements. It centres on the establishment of an observatory in 1840s Singapore and examines the channels that linked the observatory to a global community of scientists, colonial officers and a reading public. It will argue that, although the value of overseas meteorological investigation was recognized by the British government, investment was piecemeal and progress in the field often relied on the commitment and enthusiasm of individuals. In the Straits Settlements, as elsewhere, these individuals were drawn from military or medical backgrounds, rather than trained as dedicated scientists. Despite this, meteorology was increasingly recognized as of fundamental importance to imperial interests. Thus this article connects meteorology with the history of science and empire more fully and examines how research undertaken in British dependencies is revealing of the operation of transnational networks in the exchange of scientific knowledge. Copyright © 2015 British Society for the History of Science.

Hussin A.,National University of Malaysia | Poole C.,University of Leeds
Construction and Building Materials | Year: 2011

Interfacial transition zone (ITZ) is one of the key factors that associated with concrete strength and durability and its characterization has been a crucial parameter in concrete technology. Many previous researchers have conducted various microstructure assessments to evaluate variations in the ITZ and consensually accept that this zone exhibits specific changes in mineralogy and microstructure. Although the previous studies had elaborated the nature of ITZ, but the role of aggregate variation in the development ITZ microstructure in normal strength concrete is still in conclusive. Consequently, in this paper, the ITZ in normal strength concrete has been examined more closely by using three different granitic aggregates and one limestone source. Collectively, this research provide some petrography evidence that in normal strength concrete with a water/cement (w/c) ratio of 0.5, the inclusion of different types of aggregate significantly affected the heterogeneity of the ITZ microstructure. Thus heterogeneity consequences are also verified by the semi-quantitative estimation such as the percentage fraction of porosity, hydrated/unhydrated cement grains, microhardness, orientation index of calcium hydroxide (CH) and thickness. © 2010 Elsevier Ltd. All rights reserved.

Zakaria M.N.,Universiti Sains Malaysia | Jalaei B.,Universiti Sains Malaysia | Abdul Wahab N.A.,National University of Malaysia
European Archives of Oto-Rhino-Laryngology | Year: 2016

For estimating behavioral hearing thresholds, auditory steady state response (ASSR) can be reliably evoked by stimuli at low and high modulation frequencies (MFs). In this regard, little is known regarding ASSR thresholds evoked by stimuli at different MFs in female and male participants. In fact, recent data suggest that 40-Hz ASSR is influenced by estrogen level in females. Hence, the aim of the present study was to determine the effect of gender and MF on ASSR thresholds in young adults. Twenty-eight normally hearing participants (14 males and 14 females) were enrolled in this study. For each subject, ASSR thresholds were recorded with narrow-band chirps at 500, 1,000, 2,000, and 4,000 Hz carrier frequencies (CFs) and at 40 and 90 Hz MFs. Two-way mixed ANOVA (with gender and MF as the factors) revealed no significant interaction effect between factors at all CFs (p > 0.05). The gender effect was only significant at 500 Hz CF (p < 0.05). At 500 and 1,000 Hz CFs, mean ASSR thresholds were significantly lower at 40 Hz MF than at 90 Hz MF (p < 0.05). Interestingly, at 2,000 and 4,000 Hz CFs, mean ASSR thresholds were significantly lower at 90 Hz MF than at 40 Hz MF (p < 0.05). The lower ASSR thresholds in females might be due to hormonal influence. When recording ASSR thresholds at low MF, we suggest the use of gender-specific normative data so that more valid comparisons can be made, particularly at 500 Hz CF. © 2015, Springer-Verlag Berlin Heidelberg.

Hasan M.,University of Adelaide | Reaz M.,National University of Malaysia
Measurement Science Review | Year: 2012

The aim of this paper is to model the algorithm for Fetal ECG (FECG) extraction from composite abdominal ECG (AECG) using VHDL (Very High Speed Integrated Circuit Hardware Description Language) for FPGA (Field Programmable Gate Array) implementation. Artificial Neural Network that provides efficient and effective ways of separating FECG signal from composite AECG signal has been designed. The proposed method gives an accuracy of 93.7% for R-peak detection in FHR monitoring. The designed VHDL model is synthesized and fitted into Altera's Stratix II EP2S15F484C3 using the Quartus II version 8.0 Web Edition for FPGA implementation.

Choudhury P.K.,National University of Malaysia
Progress in Electromagnetics Research | Year: 2012

The paper presents an analytical investigation of three-layer twisted clad liquid crystal fiber in respect of its power propagation characteristics. The fiber under consideration has dielectric non-magnetic materials in its core and inner clad sections, whereas the outermost clad is made of radially anisotropic liquid crystal material. Twist in the fiber is introduced in the form of superfine helical turns at the interface of the core and the inner clad regions with specified values of pitch angle. Results demonstrate large confinement of optical power in the outermost liquid crystal section. Further, the angle of twist is seen to have its pronounced effect on controlling the flow of power as it exhibits the ability of governing the propagation characteristics of the medium. The observed propagation feature is attributed to the radial anisotropy of the liquid crystal outer region as well as the amount of twist introduced, and attracts useful applications of such complex fiber structures in evanescent field optical sensing and other coupling devices primarily used in integrated optics.

Siow K.S.,National University of Malaysia
Journal of Electronic Materials | Year: 2014

Silver (Ag) has been under development for use as interconnect material for power electronics packaging since the late 1980s. Despite its long development history, high thermal and electrical conductivities, and lead-free composition, sintered Ag technology has limited market penetration. This review sets out to explore what is required to make this technology more viable. This review also covers the origin of sintered Ag, the different types and application methods of sintered Ag pastes and laminates, and the long-term reliability of sintered Ag joints. Sintered Ag pastes are classified according to whether pressure is required for sintering and further classified according to their filler sizes. This review discusses the main methods of applying Ag pastes/laminates as die-attach materials and the related processing conditions. The long-term reliability of sintered Ag joints depends on the density of the sintered joint, selection of metallization or plating schemes, types of substrates, substrate roughness, formulation of Ag pastes/laminates, joint configurations (i.e., joint thicknesses and die sizes), and testing conditions. This paper identifies four challenges that must be overcome for the proliferation of sintered Ag technology: changes in materials formulation, the successful navigation of the complex patent landscape, the availability of production and inspection equipment, and the health concerns of Ag nanoparticles. This paper is expected to be useful to materials suppliers and semiconductor companies that are considering this technology for their future packages. © 2014 TMS.

Thamburaja P.,National University of Malaysia | Liu J.,National University of Singapore
International Journal of Solids and Structures | Year: 2014

Although large-volume metallic glasses (MGs) are susceptible to shear localization due to their intrinsically strain-softening response, recent experiments and molecular dynamics simulations have shown that small-volume MGs samples are able to exhibit work hardening response. Here, we seek to address two issues regarding the mechanical response of small-volume MGs at low homologous temperatures from a continuum-based modeling perspective: (1) are MGs capable of exhibiting a work hardening response, and (2) what is the physical mechanism which causes its work hardening response? Along with implementing a recently-developed finite-deformation, strain gradient plasticity-based constitutive model for MGs into a self-developed finite-element code, we study the tensile response of small-volume MG samples of various sizes through finite-element simulations. Our simulations show that small-volume MG samples are capable of exhibiting a work hardening response provided the following conditions are met: (a) the sample size is small enough, and (b) the appropriate microscopic boundary conditions for the free volume are imposed on the sample. © 2014 Elsevier Ltd. All rights reserved.

Shamshirband S.,University of Malaya | Anuar N.B.,University of Malaya | Kiah M.L.M.,University of Malaya | Patel A.,National University of Malaysia | Patel A.,Kingston University
Engineering Applications of Artificial Intelligence | Year: 2013

The deployment of wireless sensor networks and mobile ad-hoc networks in applications such as emergency services, warfare and health monitoring poses the threat of various cyber hazards, intrusions and attacks as a consequence of these networks' openness. Among the most significant research difficulties in such networks safety is intrusion detection, whose target is to distinguish between misuse and abnormal behavior so as to ensure secure, reliable network operations and services. Intrusion detection is best delivered by multi-agent system technologies and advanced computing techniques. To date, diverse soft computing and machine learning techniques in terms of computational intelligence have been utilized to create Intrusion Detection and Prevention Systems (IDPS), yet the literature does not report any state-ofthe-art reviews investigating the performance and consequences of such techniques solving wireless environment intrusion recognition issues as they gain entry into cloud computing. The principal contribution of this paper is a review and categorization of existing IDPS schemes in terms of traditional artificial computational intelligence with a multi-agent support. The significance of the techniques and methodologies and their performance and limitations are additionally analyzed in this study, and the limitations are addressed as challenges to obtain a set of requirements for IDPS in establishing a collaborative-based wireless IDPS (Co-WIDPS) architectural design. It amalgamates a fuzzy reinforcement learning knowledge management by creating a far superior technological platform that is far more accurate in detecting attacks. In conclusion, we elaborate on several key future research topics with the potential to accelerate the progress and deployment of computational intelligence based Co-WIDPSs. © 2013 Elsevier Ltd. All rights reserved.

Jaafar M.H.,National University of Malaysia
Malaysian Journal of Public Health Medicine | Year: 2015

Dioxins are a most toxic compound ever studied by human until today. Their significant health effects involved all ranges of age, including infants due to exposure to contaminated breast milk. The objective of the study was to appraise the status of dioxin contamination in breast milk among postnatal mothers live in urban and suburban areas in Klang Valley. It was conducted as a cross sectional study involving 101 postnatal mothers who came for their infant second hepatitis B vaccination. The samples were analysed using High Resolution Gas Chromatography (HRGC) following the USEPA Method 8290. About 70.3% of the samples were found detected with dioxin congeners. More suburban mothers have positive breast milk dioxins compared to urban mothers, 100.0% and 67.0% respectively. Significant associated factors include high fat daily intake (p=0.013), high milk daily intake (p= 0.044), high meat daily intake (p=0.001), body mass index more than 30 kg/m2 (p=0.005), and body fat % of more than 26% (p=0.046). In conclusion, amount daily intake of fat diet, meat, milk, body mass index and body fat are significant associated factors for the present of dioxins in breast milk among postnatal mothers in Klang Valley. More suburban mothers contain dioxins in their breast milk, which poses higher risk of health problems among their infants. A comprehensive study need to be conducted and regular followup need to be established in monitoring the future severity of maternal breast milk contamination to ensure the health of the next generations.

Ahmad K.,National University of Malaysia
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2011

The eXtensible Markup Language (XML) has recently emerged as a standard for data representation and interchange on the web. Based on its popularity used in most application, the critical issues are to store and to query XML data to exploit the full power of this technology. Since relational database is widely used technology for storing and querying, therefore replacing it with pure XML database is not a good choice and very expensive process. It is thus crucial to map XML data into relational data and this process is one that occurs frequently. Many existing methods exist in the literature, and defining what the best mapping method is explicitly important. The intention of this paper is to the existing mapping methods in terms of generating good relational schema. At the end a new mapping method is developed to overcome the limitations the limitations and shows that it is efficient in terms of removing relation redundancy. © 2011 Springer Berlin Heidelberg.

Bachok N.,University Putra Malaysia | Ishak A.,National University of Malaysia | Pop I.,Babes - Bolyai University
International Journal of Heat and Mass Transfer | Year: 2012

The boundary layer of an unsteady two-dimensional stagnation-point flow of a nanofluid is further investigated. The similarity equations are solved numerically for three types of nanoparticles, namely copper (Cu), alumina (Al 2O 3), and titania (TiO 2) in the water based fluid with Prandtl number Pr = 6.2. The skin friction coefficient, the local Nusselt number, and the velocity and temperature profiles are presented and discussed. Effects of the solid volume fraction parameter φ on the fluid flow and heat transfer characteristics are thoroughly examined. Interesting observation is that there are dual solutions seen for negative values of the unsteadiness parameter A (decelerating flow with A < 0). © 2012 Elsevier Ltd. All rights reserved.

Bachok N.,University Putra Malaysia | Ishak A.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
International Journal of Heat and Mass Transfer | Year: 2012

The unsteady boundary layer flow of a nanofluid over a permeable stretching/shrinking sheet is theoretically studied. The governing partial differential equations are transformed into ordinary ones using a similarity transformation, before being solved numerically. The results are obtained for the skin friction coefficient, the local Nusselt number and the local Sherwood number as well as the velocity, temperature and the nanoparticle fraction profiles for some values of the governing parameters, namely, the unsteadiness parameter, the mass suction parameter, the Brownian motion parameter, the thermophoresis parameter, Prandtl number, Lewis number and the stretching/shrinking parameter. It is found that dual solutions exist for both stretching and shrinking cases. The results also indicate that both unsteadiness and mass suction widen the range of the stretching/shrinking parameter for which the solution exists. © 2011 Elsevier Ltd. All rights reserved.

Rosali H.,University Putra Malaysia | Ishak A.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
International Communications in Heat and Mass Transfer | Year: 2012

This paper presents a numerical analysis of a micropolar fluid flow towards a permeable stretching/shrinking sheet in a porous medium. The governing nonlinear partial differential equations are transformed into a system of ordinary differential equations by a similarity transformation, before being solved numerically by a finite-difference scheme known as the Keller-box method. The effects of the governing parameters on the fluid flow and heat transfer characteristics are illustrated graphically. It is found that dual solutions exist for the shrinking case, whereas for the stretching case, the solution is unique. © 2012 Elsevier Ltd.

Wan Mohtar W.H.M.,University of Nottingham | Wan Mohtar W.H.M.,National University of Malaysia | Munro R.J.,University of Nottingham
Physics of Fluids | Year: 2013

Here, we report laboratory experiments to investigate the threshold criteria for incipient sediment motion in the presence of oscillating-grid turbulence, with the bed slope inclined at angles between the horizontal and the repose limit for the sediment. A set of nine mono-disperse sediment types was used with size ranges normally associated with either the hydraulically-smooth or transitional regimes. Measurements of the (turbulent) fluid velocity field, in the region between the grid and bedform's surface, were obtained using two-dimensional particle imaging velocimetry. Statistical analysis of the velocity data showed that the turbulence had a anisotropic structure, due to the net transfer of energy from the normal to the tangential velocity components in the near-bed region, and that the fluctuations were dominant compared to the secondary mean flow. The sediment threshold criteria for horizontal bedforms were compared with, and found to be in good qualitative agreement with the standard Shields curve. For non-horizontal bedforms, the bed mobility was found to increase with increasing bed slope, and the threshold criteria were compared with previously-reported theoretical models, based on simple force-balance arguments. © 2013 American Institute of Physics.

Mushrifah I.,National University of Malaysia
Biological Trace Element Research | Year: 2010

This paper aims to compare the Cd, Cu, and Pb concentration in the bone, gills, and muscle of the seven fish species sampled during normal and dry seasons. Cadmium, Cu, and Pb concentrations varied significantly depending on the type of the tissue and season. Bone samples of the Osteochilus hasseltii showed the highest concentrations of Pb (6.08 μg/g dw) during September (the dry season), whereas bone samples of the Puntioplites bulu showed the lowest concentrations of Cd (0.08 μg/g dw) during September. Muscle samples of the P. bulu indicated the highest concentrations of Cu (2.58 μg/g dw) during March (the normal season). On the other hand, muscle samples of Channa straitus sowed the lowest concentrations of Cd (0.04 μg/g dw) during July (the dry season). Gills samples of the O. hasseltii showed the highest concentration of Pb (6.56 μg/g dw) during March (the normal season), while gills samples of C. straitus indicated the lowest concentration of Cd (0.06 μg/g dw) during July (the dry season). © 2010 Springer Science+Business Media, LLC.

Leong K.Y.,University of Malaya | Leong K.Y.,National University of Malaysia | Saidur R.,University of Malaya | Mahlia T.M.I.,University of Malaya | Yau Y.H.,University of Malaya
International Journal of Heat and Mass Transfer | Year: 2012

The emergence of several challenging issues such as climate change, fuel price hike and fuel security have become hot topics around the world. Therefore, introducing highly efficient devices and heat recovery systems are necessary to overcome these challenges. It is reported that a high portion of industrial energy is wasted as flue gas from heating plants, boilers, etc. This study has focused on the application of nanofluids as working fluids in shell and tube heat recovery exchangers in a biomass heating plant. Heat exchanger specification, nanofluid properties and mathematical formulations were taken from the literature to analyze thermal and energy performance of the heat recovery system. It was observed that the convective and overall heat transfer coefficient increased with the application of nanofluids compared to ethylene glycol or water based fluids. It addition, 7.8% of the heat transfer enhancement could be achieved with the addition of 1% copper nanoparticles in ethylene glycol based fluid at a mass flow rate of 26.3 and 116.0 kg/s for flue gas and coolant, respectively. © 2011 Elsevier Ltd. All rights reserved.

Ahmed M.J.,National University of Malaysia
Heat and Mass Transfer/Waerme- und Stoffuebertragung | Year: 2012

The kinetics of the catalytic hydrogenation of D-glucose to produce D-sorbitol was studied in a threephase laboratory scale reactor. The hydrogenation reactions were performed on activated charcoal supported platinum catalyst in the temperature range 25-65°C and in a constant pressure of 1 atm. The kinetic data were modeled by zero, first and second-order reaction equations. In the operating regimes studied, the results show that the hydrogenation reaction was of a first order with respect to D-glucose concentration. Also the activation energy of the reaction was determined, and found to be 12.33 kJ mole -1. A set of experiment was carried out to test the deactivation of the catalyst, and the results show that the deactivation is slow with the ability of using the catalyst for several times with a small decrease in product yield. © Springer-Verlag 2011.

Bachok N.,University Putra Malaysia | Ishak A.,National University of Malaysia | Pop I.,Babes - Bolyai University
International Journal of Heat and Mass Transfer | Year: 2012

An analysis is carried out to investigate the steady two-dimensional stagnation-point flow of a water based nanofluid over an exponentially stretching/shrinking sheet in its own plane. Using a similarity transformation, the governing mathematical equations are transformed into coupled, nonlinear ordinary differential equations which are then solved numerically for three types of nanoparticles, namely copper (Cu), alumina (Al 2O 3), and titania (TiO 2) in the water based fluid with Prandtl number Pr = 6.2. The skin friction coefficient, the local Nusselt number and the velocity and temperature profiles are presented graphically and discussed. Effects of the solid volume fraction and the stretching/shrinking parameter λ on the fluid flow and heat transfer characteristics are thoroughly examined. Different from a stretching sheet, it is found that the solutions for a shrinking sheet are non-unique. The range of the parameter λ where the similarity solution exists for the steady stagnation-point flow over an exponentially stretching/shrinking sheet is larger compared with the linear stretching/shrinking case. © 2012 Elsevier Ltd. All rights reserved.

Ahmad K.,International Islamic University Malaysia | Nazar R.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
International Communications in Heat and Mass Transfer | Year: 2012

In this paper, the steady mixed convection boundary layer in laminar film flow of a micropolar fluid is considered. The resulting nonlinear coupled ordinary differential equations are solved numerically using an efficient implicit finite-difference scheme. The numerical results obtained for the skin friction coefficient and the local Nusselt number, as well as the velocity, angular velocity or microrotation and temperature profiles are presented in tables and figures for different values of the material parameter K and the Richardson number Ri when the Prandtl number Pr= 0.7 and Pr= 1. © 2011 Elsevier Ltd.

Bachok N.,University Putra Malaysia | Ishak A.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
International Journal of Heat and Mass Transfer | Year: 2012

This paper considers the extended Blasius and Sakiadis problems in nanofluids, by considering a uniform free stream parallel to a fixed or moving flat plate, which has more practical significance. It is assumed that the plate moves in the same or opposite direction to the free stream. The resulting system of nonlinear ordinary differential equations is solved numerically for three types of nanoparticles, namely copper (Cu), alumina (Al2O 3), and titania (TiO2) in the water based fluid with Prandtl number Pr = 6.2. The effect of the solid volume fraction parameter of the nanofluids on the heat transfer characteristics is investigated. The results indicate that dual solutions exist when the plate and the free stream move in the opposite directions. © 2011 Elsevier Ltd. All rights reserved.

Sukor N.,National University of Malaysia
Postgraduate Medical Journal | Year: 2011

Hypertension is a chronic disorder which often entails debilitating cardiovascular and renal complications. Hypertension mostly arises as a complex quantitative trait that is affected by varying combinations of genetic and environmental factors. Secondary hypertension has been encountered with increasing frequency. The common causes of secondary hypertension include renal parenchymal disease, renal artery stenosis, primary aldosteronism, phaeochromocytoma, and Cushing's syndrome. The detection of a secondary cause is of the utmost importance because it provides an opportunity to convert an incurable disease into a potentially curable one. Early identification and treatment will provide a better opportunity for cure, prevent target organ damage, reduce socioeconomic burden and health expenditure associated with drug costs, and improve patients' quality of life. Hence, it is a condition not to be missed.

Leo C.P.,Universiti Sains Malaysia | Cathie Lee W.P.,University of Selangor | Ahmad A.L.,Universiti Sains Malaysia | Mohammad A.W.,National University of Malaysia
Separation and Purification Technology | Year: 2012

Polysulfone (PSf) membranes are undesirably hydrophobic, thus they are susceptible to the fouling by most organic components including fatty acids. In this work, ZnO nanoparticles were blended into PSf membranes to improve its properties in reduction of fouling by oleic acid. The casting solution was prepared by dispersing 1-4 wt.% of ZnO nanoparticles (21-23 nm), 1 wt.% of PVA and PSf into 1-methyl-2-pyrrolidinone at 75 °C, with a stirring speed of 400 rpm. The weight ratio of polymer to solvent is maintained at 1:4.84. The composite membranes were then prepared using phase inversion method. The mean pore size of the composite membranes is slightly larger than the mean pore size of pure PSf membrane. However, the water contact angle greatly reduces from 85° to 63° when 2 wt.% of ZnO is added into Pf-2 membranes. Thermal stability of PSf membranes has significantly improved with the addition of ZnO. Although absorption peaks of ZnO are absent in FT-IR patterns, EDX analysis shows that ZnO nanoparticles are well distributed in the dense layer of Pf-2 membrane. Hence, Pf-2 membranes show the highest permeability and the least fouling by oleic acid. © 2012 Elsevier B.V. All rights reserved.

Aziz N.A.,National University of Malaysia
Reviews in Clinical Gerontology | Year: 2010

Current guidelines in stroke management are divided on the issue of providing further rehabilitation to stroke patients who have had stroke six months ago and longer. Whilst consensus considers that long-term rehabilitation is neither practical nor beneficial, rehabilitation remains vital in the complex management of longer-term stroke care, as it provides continuity from the formal rehabilitation intervention in the hospital setting. Longer-term rehabilitation is principally a community-based intervention, as it aims to assist the survivors to become more independent through social and leisure-based interventions. Available evidence is limited, with available studies heterogeneous and small in sample size. This review aims to look into the existing evidence, and discusses the feasibility and challenges in providing longer-term rehabilitation to stroke survivors. Copyright © 2010 Cambridge University Press.

Ng Y.F.,National University of Malaysia
Zootaxa | Year: 2015

Amalothrips noorazlani sp. n. is described from Malaysia based on both sexes, and a key is provided to the species of this genus. This is the first record of Amalothrips species outside India, and the first description of a male Amalothrips. The male has a pair of drepanae, the tergal posteromargin bears a toothed craspedum, but there are no sternal pore plates. Copyright © 2015 Magnolia Press.

Wu T.Y.,University of Selangor | Hay J.X.W.,University of Selangor | Kong L.B.,University of Selangor | Juan J.C.,University of Selangor | Jahim J.M.,National University of Malaysia
Renewable and Sustainable Energy Reviews | Year: 2012

Hydrogen is the fuel of the future mainly due to its high conversion efficiency, recyclability and non-polluting nature. Biological hydrogen production processes, mostly mediated photosynthetic bacteria, are more favorable candidates for biological hydrogen production due to their high conversion efficiency and versatility in the substrates (including wastewater) they can utilize. The potential utilization of waste material is being investigated extensively with suitable bioprocess technologies for providing cheaper raw materials with simultaneous waste treatment and bioremediation. Thus, this review article summarizes the biohydrogen production metabolism of purple non-sulfur (PNS) bacteria and research works involving biohydrogen production using various wastes such as tofu wastewater, palm oil mill effluent, olive mill wastewater, brewery wastewater, etc. by photosynthetic PNS bacteria. Waste materials used, yields and rates are reviewed, together with a discussion of the economics and perspectives of biohydrogen production from waste materials. © 2012 Elsevier Ltd. All rights reserved.

Visualizing high pressure pulsed gas jet can be challenging due to its weak scattering of light which requires reliable flow tracer. Complex and costly laser source and high speed camera settings using shadowgraph, Schlieren and Laser Induced Fluorescent (LIF) techniques with seeding of flow tracers such as acetone have been used. In the spirit of simplification, this paper presents a technique to visualize high pressure pulsed gas jet in liquid ambient. It can be used as predictive tool to investigate the structure, dynamic and interaction of gas jet with the environment [1]. A gas injector with square-shaped nozzle was used. High pressure nitrogen gas at 5 and 6 MPa with 12 ms injection pulse exits the injector through a 1 mm2 square nozzle into quiescent water. The injector tip is immersed below water surface in an optically-accessed container and placed inside an extremely low illuminated square chamber. Two small windows on opposite walls of the chamber allow image capturing with injection-flash light synchronization. Images of the gas jets formed from nozzle at various time after the start of the injection (SOI) were captured by a digital camera. During exposure, the flash light was triggered for 1 ms at some times after SOI, thus images captured correspond to the flash timing. Results showed that the shape of the gas jet was in agreement with the vortex ball model but with difference in the magnitude of penetration with respect to previous works. Some similarities in the gas injection behavior are found in the liquid and gas ambient. The tip penetration and gas width in water environment are about half of the magnitude in the gas environment. A dimensionless gas dynamic analysis shows a good agreement in the trend of jet development between the gas environment using Planar Laser Induced Fluorescent (PLIF) imaging and in-water imaging techniques. Results indicate that both gas jet length and width are very sensitive to injection pressure. © 2015 Elsevier Ltd. All rights reserved.

Yusop R.M.,National University of Malaysia | Unciti-Broceta A.,University of Edinburgh | Bradley M.,University of Edinburgh
Bioorganic and Medicinal Chemistry Letters | Year: 2012

Variation at the 3' position of fluorescein via Suzuki-Miyaura cross-coupling with aryl and heteroaryl moieties gave a family of anthofluoresceins whose spectroscopic properties were studied. The 1-methylindole derivative gave the highest quantum yield and was observed to behave as a molecular rotor, displaying marked variations in fluorescent intensities with viscosity and offering possible application in cellular sensing and fluorescent polarisation assays. © 2012 Published by Elsevier Ltd.

Hainin M.R.,University of Technology Malaysia | Yusoff N.I.Md.,National University of Malaysia | Mohd Satar M.K.I.,University of Technology Malaysia | Brown E.R.,Auburn University
Construction and Building Materials | Year: 2013

This study investigates the effect of lift thickness on (i) permeability and (ii) the time available for compaction (TAC) of hot-mix asphalt (HMA) mixes under tropical climate condition. A total of 14 HMA mixes consisting of various types, gradations, and nominal maximum aggregate sizes (NMAS) were selected. The heights for thickness (t) to NMAS ratios of 2.0, 3.0, and 4.0 were determined with appropriate mass to produce 7.0 ± 1.0% air voids. The bulk specific gravity of the samples was determined using the vacuum sealing method. The laboratory permeability test and the relationships between permeability and lift thickness were evaluated. To achieve the second objective, seven field test sections with different HMA mixes were constructed; each was about 40 m long and 3.5 m wide. Each test section was paved with thickness (t) to a nominal maximum aggregate size (NMAS) ratio of 2.0 at the beginning of the section and gradually increased to a t/NMAS ratio of 5.0 at the end of the section with air temperatures during construction ranging from 26 to 35 C. It was found that HMA mixes with a lift thickness of 30 mm and less with coarse gradation have a greater chance of having a permeability problem, even though they are compacted at the right density. In addition, the thinner the mix layer, the faster the mix cools, thus reducing the TAC. The results also suggest that the TAC for a 25 mm lift is 13 min, 23 min for 32 mm, 32 min for 38 mm, and is expected to be more than 50 min for 44 mm and above. © 2013 Elsevier Ltd. All rights reserved.

Mahmud M.,National University of Malaysia
International Journal of Ecology and Development | Year: 2010

The present study investigates some of the physical properties of remotely sensed aerosols that were emitted from an intense biomass burning episode over equatorial Southeast Asia during August 2005. A total of 1245 active fire counts were detected in Sumatera, Indonesia by the MODIS Aqua satellite from 8 to 14 August 2005, and consequently, increased the amount of tropospheric oceanic aerosol mass concentrations and aerosol optical depth (AOD) to more than 23 _g cm-2 and 0.8, respectively over Peninsular Malaysia. This is in contrast to lower AOD values over the uninhabited neighbouring areas such as the Bay of Bengal or the equatorial Indian Ocean. Coarser and lower mass concentrations of aerosols were detected over the equatorial Indian Ocean, in contrast to the area east of Sumatera, including Peninsular Malaysia and the southern South China Sea, where the finer sized aerosols originated mainly from the biomass burning activities. Here, the effective radii of fine sized aerosols ranged from 0.1 to 0.4 μm compared to the effective radii of coarse aerosols that were typically of size 1 μm over the equatorial Indian Ocean. Forward air trajectories showed that the fine aerosols originated from the burned biomass in Sumatera were transported downstream to Peninsular Malaysia by the prevailing southwest monsoon. The near-stagnant low level conditions that occurred from 9 to 11 August 2005 exacerbated the poor dispersion of the aerosols as corroborated by the extremely high ground level PM10 concentrations recorded on the western coast of Peninsular Malaysia. Time series of the AOD showed that the elevated turbidity of the atmosphere associated with the suspended aerosols from the intense biomass burning activities were transient in nature, which lasted for approximately a few days before the aerosols were subsequently removed from the atmosphere. © 2010 IJED.

Yau Y.H.,University of Malaya | Hasbi S.,National University of Malaysia
Indoor and Built Environment | Year: 2015

Even though the green building concept is fairly new in Malaysia, the development of this industry has been growing in recent years prior to the launch of Malaysia's own standard, namely the Green Building Index (GBI). One of the criteria assessed in the GBI is the energy efficiency, which takes about 21% of the overall assessment. Considering this, the passive design has been included in the green building concept to reduce the energy usage without compromising occupant thermal comfort. This study attempts to assess the passive design effectiveness in terms of indoor air quality in green office buildings in the tropics. Two green office buildings that incorporated the radiant slab cooling and conventional cooling system have been selected as case studies. A detailed assessment in terms of thermal comfort parameters (temperature and relative humidity), indoor pollutants' concentration (carbon dioxide, carbon monoxide and formaldehyde) and air movement was carried out. The results showed that the thermal comfort parameters fall within the Malaysian Standard (MS1525:2007) and ASHRAE Standard-55 2010 except for the air movement in both buildings. Based on the results obtained, future buildings using the radiant slab cooling can have a better comfort level from the lesson learned from both buildings. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Aziz R.C.,University of Kuala Lumpur | Hashim I.,National University of Malaysia
Chinese Physics Letters | Year: 2010

We study the effects of viscous dissipation on flow and heat transfer in a thin liquid film on an unsteady stretching sheet. A general surface temperature is taken into consideration. The velocity and temperature fields are solved using the homotopy analysis method. The results show that the increasing values of the Eckert number can increase temperature distribution and the heat transfer rate. © 2010 Chinese Physical Society and IOP Publishing Ltd.

Abdullah S.A.,National University of Malaysia
Journal of Land Use Science | Year: 2014

Forest fragmentation has several phases; thus, the ecological significance of each phase during a particular period of time must be interpreted. To interpret, this study quantifies the magnitude of forest loss and the changes in the temporal pattern of fragmentation in the State of Selangor, peninsular Malaysia. Using the decision tree model of land transformation, five phases of forest fragmentation were identified: perforation, dissection, dissipation, shrinkage and attrition. This analysis showed that the magnitude of forest loss was the highest during the dissipation phase. The patchiness analysis showed that dissipation contributes to the highest environmental uncertainty found for the forest patches. This study can be considered a first step in the exploration of the properties and the behavioural pattern shown by the spatial process of forest fragmentation. © 2014 © 2014 Taylor & Francis.

Arifin N.M.,University Putra Malaysia | Nazar R.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
Meccanica | Year: 2011

In this paper, a non-isobaric Marangoni boundary layer flow that can be formed along the interface of immiscible nanofluids in surface driven flows due to an imposed temperature gradient, is considered. The solution is determined using a similarity solution for both the momentum and energy equations and assuming developing boundary layer flow along the interface of the immiscible nanofluids. The resulting system of nonlinear ordinary differential equations is solved numerically using the shooting method along with the Runge-Kutta-Fehlberg method. Numerical results are obtained for the interface velocity, the surface temperature gradient as well as the velocity and temperature profiles for some values of the governing parameters, namely the nanoparticle volume fraction ω (0 ≤ ω ≤ 0.2) and the constant exponent β. Three different types of nanoparticles, namely Cu, Al 2O3 and TiO2 are considered by using water-based fluid with Prandtl number Pr = 6.2. It was found that nanoparticles with low thermal conductivity, TiO2, have better enhancement on heat transfer compared to Al2O3 and Cu. The results also indicate that dual solutions exist when β <0.5. The paper complements also the work by Golia and Viviani (Meccanica 21:200-204, 1986) concerning the dual solutions in the case of adverse pressure gradient. © 2010 Springer Science+Business Media B.V.

Rashwan H.H.,University Technology of MARA | Saat N.Z.N.M.,National University of Malaysia | Manan D.N.A.,Ministry of Health
Asian Pacific Journal of Cancer Prevention | Year: 2012

Human Papillomavirus (HPV) infection is one of the most common sexually transmitted infections and oncogenic HPV is the main cause of cervical cancer. However, HPV vaccination is already available as the primary preventive method against cervical cancer. The objective of this study was to determine the level of knowledge, attitude and practice of HPV vaccination among Universiti Kebangsaan Malaysia (UKM) and Universiti Malaya (UM) students. This study was conducted from March until August 2009. Pre-tested and validated questionnaires were filled by the third year UKM (n=156) and UM (n=149) students from medical, dentistry and pharmacy faculties. The results showed that the overall level of knowledge on HPV infection, cervical cancer and its prevention among respondents was high and themajority of them had positive attitude towards HPV vaccination. Medical students had the highest level of knowledge (p<0.05). Very few students (3.6%) had already taken the vaccine with no significant difference between the two Universities (p=0.399). In conclusion, the knowledge and attitude of the respondents were high and positive, respectively. Only few students took HPV vaccination. Thus, more awareness campaigns and HPV vaccination services should be provided at universities' campuses with the price of the HPV vaccine reduced for the students.

Enshaei M.,University Putra Malaysia | Hanapi Z.M.,University of Strathclyde | Othman M.,National University of Malaysia
International Journal on Communications Antenna and Propagation | Year: 2014

One of the most attractive areas of research is Mobile Ad hoc Networks (MANET), which has a number of movable nodes with no infrastructure. Independent nodes are able to move freely inside or leave the network so mobile ad hoc networks are flexible and dynamic topology, MANETs are simply configurable by themselves, easy to deploy, no need for existing infrastructure, and these abilities make them one of the modern eras for industries. Most dangerous and powerful attacks in MANETs are wormhole attack and detection it is very difficult. This paper seeks to study and analyze challenges, security issues of MANETs and one of the severe attacks “wormhole attack,” and its detection and prevention methods, routing protocols used to identify and prevent this attack. These methods are able to identify and avoid the wormhole attacks; but they are not very efficient and have some weaknesses. There is no common algorithm that fits well against the wormhole attack. © 2014 Praise Worthy Prize S.r.l. - All rights reserved.

The nematode Caenorhabditis elegans is hypersusceptible to Burkholderia pseudomallei infection. However, the virulence mechanisms underlying rapid lethality of C. elegans upon B. pseudomallei infection remain poorly defined. To probe the host-pathogen interaction, we constructed GFP-tagged B. pseudomallei and followed bacterial accumulation within the C. elegans intestinal lumen. Contrary to slow-killing by most bacterial pathogens, B. pseudomallei caused fairly limited intestinal lumen colonization throughout the period of observation. Using grinder-defective mutant worms that allow the entry of intact bacteria also did not result in full intestinal lumen colonization. In addition, we observed a significant decline in C. elegans defecation and pharyngeal pumping rates upon B. pseudomallei infection. The decline in defecation rates ruled out the contribution of defecation to the limited B. pseudomallei colonization. We also demonstrated that the limited intestinal lumen colonization was not attributed to slowed host feeding as bacterial loads did not change significantly when feeding was stimulated by exogenous serotonin. Both these observations confirm that B. pseudomallei is a poor colonizer of the C. elegans intestine. To explore the possibility of toxin-mediated killing, we examined the transcription of the C. elegans ABC transporter gene, pgp-5, upon B. pseudomallei infection of the ppgp-5::gfp reporter strain. Expression of pgp-5 was highly induced, notably in the pharynx and intestine, compared with Escherichia coli-fed worms, suggesting that the host actively thwarted the pathogenic assaults during infection. Collectively, our findings propose that B. pseudomallei specifically and continuously secretes toxins to overcome C. elegans immune responses.

Hsiao M.-S.,University of Bristol | Hsiao M.-S.,Air Force Research Lab | Yusoff S.F.M.,University of Bristol | Yusoff S.F.M.,National University of Malaysia | And 2 more authors.
Macromolecules | Year: 2014

Three well-defined asymmetric crystalline-coil poly(ferrocenyldimethylsilane-block-2-vinylpyridine) (PFS-b-P2VP) diblock copolymers (PFS44-b-P2VP264, PFS75-b-P2VP 454, and PFS102-b-P2VP625) with similar block ratios (r = NP2VP/NPFS = ca. 6.0 ± 0.1) but different overall molar masses (Mn = 38-700, 65-800, and 90-400 g mol-1) were synthesized by sequential anionic polymerization, and their solution self-assembly behavior was explored as a function of (i) molar mass and (ii) the ratio of common to selective solvent. When self-assembly was performed in isopropanol (i-PrOH), a selective solvent for P2VP, a decrease in the rate of the crystallization-driven transition from the initially formed spheres (with amorphous PFS cores) into cylinders (with crystalline cores) was detected with an increase in molecular weight. This trend can be explained by a decrease in the rate of crystallization for the PFS core-forming block as the chain length increased. In contrast, when a mixture of i-PrOH with increasing amounts of THF, a common solvent for both blocks, was used, spheres, cylinders, and also narrow lenticular platelets consisting of crystallized PFS lamellae sandwiched by two glassy coronal P2VP layers were formed from the same PFS x-b-P2VP6x sample. The most likely explanation involves the plasticization of the PFS core-forming block which facilitates crystallization, possibly complemented by contraction of the coils of the P2VP coronal block which otherwise limit of the lateral growth of the crystalline PFS core as THF is a poorer solvent for P2VP than i-PrOH. Selected area electron diffraction studies indicated that the PFS cores of the spherical micelles were amorphous but were consistent with those of the cylindrical micelles existing in a state approximating to that of a monoclinic PFS single crystal. In contrast, in the platelets formed in THF/i-PrOH, the PFS cores were found to be polycrystalline. The formation of narrow lenticular polycrystalline platelets rather than a regular, rectangular single crystalline morphology was attributed to a poisoning effect whereby the interference of the long P2VP coronal blocks in the growth of a rectangular PFS single crystalline core introduces defects at the crystal growth fronts. © 2014 American Chemical Society.

Singh D.,National University of Malaysia
Journal of Computer Science | Year: 2010

Problem statement: The rapid development of Driver Assistance System (DAS) provides drivers with radically enhanced information and functionality. The nature of the current DAS requires a complex human-machine interaction which is distracting and may increase the risk of road accidents. The interaction between the driver and DAS should aid the driving process without interfering with safety and ease of vehicle operation. Speech based interaction mechanisms employed are not sufficiently robust to deal with the distraction and noise present in the interior environment of the vehicle. Approach: Thus, suitable hybrid earcon/auditory icon design principles for DAS are developed. These interfaces are investigated in driving simulators in-order to test their durability and robustness. Several evaluation parameters will be applied. This will ensure the driving-related information from the DAS was delivered to the driver without affecting the overall driving process. Results: This study produces auditory design principles for information mapping (visual into non-speech based interaction) and presentation framework was produced. It outlines representation architecture that enables concurrent auditory driving related information to be transmitted from four different sources in the vehicle's interior environment. It outlines a set of hybrid design principles that integrates auditory icons with earcons to map and present real-time driving related data from a visual to a non-speech auditory interface. Conclusion/Recommendations: The major contribution of this research project takes a genuine approach by considering the entire DAS (safety, navigation and entertainment subsystem). It proposes hybrid representation strategy based on the cognitive availability of the driver and cognitive workload. It was a significant discovery that aid future DAS auditory interaction design. © 2010 Science Publications.

Ali Z.M.,National University of Malaysia
Journal of Computer Science | Year: 2010

Problem statement: Lucas function is a special form of second-order linear recurrence relation. It is used in LUC cryptosystems. The performance of LUC cryptosystem depends on the size of public key, messages and two relatively primes. The increasing of size of these parameters will increase the computation time need to perform the LUC Cryptosystem computation. The efficiency means the quality to avoid wasted time. Approach: Therefore, the main theme of this study was to design and implement an improve version of computation algorithm. The efficiency of computation can skip some computations time for a computerized calculation. Smaller computation time means the algorithm is better and more efficient than the other algorithm. In this study, the technique on reducing redundant number of computations steps in LUC Cryptosystem was investigated. The use of two variables w and t were proposed in order to reduce some computations steps in LUC Cryptosystem computation. Results: The new technique showed a better computation time compared to the existing algorithm. It also reduced some redundant multiplications without sacrificed the security of LUC Cryptosystem. At the same time, it increases the efficiency of computation algorithm. Conclusion: The proposed algorithm showed better speed and efficiency by reducing some redundant computation steps. It can reduce up to 20% of computation efforts compare to the existing one. © 2010 Science Publications.

Malek J.A.,National University of Malaysia
WSEAS Transactions on Information Science and Applications | Year: 2010

Informative Global Community Development Index (IGC) is an analysis method that looks at the development of the community currently residing in a intelligent city. From the understanding method, the development of intelligent cities based on a deontological ethics, the process of developing an intelligent city has to return maximum interest to the majority of the residing community in terms of hardware and software. The enhancement of IGC has become vital as the mile mark in developing Malaysia into a developed nation by the year 2020. In conjunction to that the method of cumulative index analysis IGC development has been used in this research as the main method in measuring the development of IGC. About 127 middle class families in Subang Jaya Smart City were chosen as research respondents in order to measure the IGC development index in Subang Jaya. All the variables are covered under ability component (humanware), management component and information supervision (infoware), components of ownership and communication and information technology usage (technoware), as well as the usage value of ICT and cyber ethics (valueware). The IGC development Index which was used utilized the Rogers scale which looked at levels of innovation, preacceptance, pre-majority, final majority and final scale. The analysis showed that most of the residents in Subang Jaya only achieved IGC development in the pre-acceptance, pre-majority and final majority scale. This meant that there weren't any of the residents in Subang Jaya which achieved the final scale.

Jamshidnezhad A.,Islamic Azad University at Mahshahr | Jan Nordin M.,National University of Malaysia
International Journal of Bio-Inspired Computation | Year: 2013

A major issue which divides the facial expressions from the other classification domains is complicated behaviour of human to express the emotions which should be recognised with the classifier model. Existing research recognise the emotions using a range of classification techniques. However, low accuracy rate, large training set, large extracted features or priority for sequence images are the main drawbacks of those works. One of the recent techniques to address the facial expressions problem is fuzzy rule-based system (FRBS) which is used as a successful method to model and solve the natural-based problems. However, FRBS is poor to adapt the existing knowledge with the diverse conditions. In this article a novel hybrid genetic-fuzzy rule-based model is proposed to optimise the performance of fuzzy classification while the limited raw input data as the features are used. In this model, the proposed genetic algorithm simulates the honey bees offspring generation process called bee royalty offspring algorithm (BROA) to improve the training process of classic genetic algorithm. The comparison results illustrated that the genetic-fuzzy classification model improves considerably the accuracy rate and performance of FRBS while the BROA modify the training process of genetic-based algorithms. Copyright © 2013 Inderscience Enterprises Ltd.

Ahmad S.,National University of Malaysia | Haber M.,Macquarie University | Bokor D.J.,Macquarie University
Journal of Shoulder and Elbow Surgery | Year: 2015

Background: The purpose of this study was to determine when cuff re-tear commonly occurs in the postoperative period and to investigate the clinical factors that might predispose to an early cuff re-tear. Methods: All patients with rotator cuff (supraspinatus±infraspinatus) tear that required arthroscopic repair during the period between June 1, 2010, and May 31, 2012, with completed serial ultrasound examinations at 6weeks, 12weeks, and 26weeks postoperatively were included. Intraoperative findings were noted. Functional clinical outcomes were assessed by Constant score, Western Ontario Rotator Cuff Index, and Oxford score. Compliance of patients with postoperative rehabilitation was established. Results: There were 127 cases; the mean age of patients was 60 years. Overall re-tear rate was 29.1%. The percentage of new re-tears was significantly higher in the first 12weeks than in the second 12weeks postoperatively (25.2% and 3.9%, respectively). The patient's postoperative compliance was a significant prognostic factor for re-tearing. Significant associations were also found between re-tear and primary tear size, tendon quality, repair tension, cuff retraction, and footprint coverage. Poor compliance of patients was highest (17.3%) during the second 6weeks postoperatively. Better functional outcomes were noted in patients who had re-torn their cuffs at the 12-week period (Oxford mean scores, P=.04). Conclusions: Understanding of the predisposing factors will assist in predicting the prognosis of the repaired rotator cuff. Despite the progress of patients' functions postoperatively, an early significant improvement of the clinical outcome should be a warning sign to a surgeon that the patient's compliance may be suboptimal, resulting in an increased risk of the cuff's re-tearing. © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees.

Ahmad K.,National University of Malaysia | Yan Y.,Santa Clara University | Bless D.,University of Wisconsin - Madison
Journal of Voice | Year: 2012

Objectives/Hypothesis: A high proportion of the geriatric population suffers from presbylaryngis and presbyphonia; however, our knowledge of vibratory patterns in this population is almost nonexistent. In this study, we investigate the vocal fold vibratory patterns of healthy elderly females to determine which features or combination of them could best describe the geriatric voices. Study Design: Cross-sectional study with 20 elderly healthy females with no history of voice problems. Methods: Hilbert transformed glottal area waveforms (GAWs) from serial high-speed digital imaging of sustained phonation are used to provide quantitative measures of glottal vibratory characteristics and perturbations; open quotient, jitter, and shimmer. Nyquist plots provide interpretable patterns to portray the vibratory characteristics as clear, pressed, breathy, and atypical patterns. Results: The GAW from most elderly speakers (50%) showed vibratory characteristics associated with a more pressed voice and higher glottal perturbation values: their Nyquist plot patterns show wide scatterings around the rim of the plot reflecting a much-reduced ability in sustaining vibratory oscillation; these were distinct differences from previously reported data on younger speakers. Qualitative examination revealed more anteriorly placed glottal gaps in the geriatric females. Conclusion: These findings have important implications in understanding voice production in the geriatric population and in helping to establish normal perturbation references among female speakers across age. © 2012 The Voice Foundation.

Lim P.S.,National University of Malaysia
Archives of gynecology and obstetrics | Year: 2011

Retained placenta is potentially life threatening due to possible complications associated with manual removal. Our aim was to determine whether umbilical vein injection of oxytocin in saline reduces the need for manual removal of placenta. This was a randomised controlled trial conducted at a tertiary hospital from December 2002 to March 2004. A total of 61 women delivering singletons, who had no sign of placental separation 20 min after vaginal delivery, were randomised to receive either intra-umbilical oxytocin 100 IU diluted in 30 ml of saline or controlled cord traction only. Manual removal was done if the placenta was not expelled in another 30 min in both arms. There was a significant reduction in the rate of subsequent manual removal of placenta (30 vs. 67.7%, p < 0.05), incidence of uterine atony (3.3 vs. 25.8%, p < 0.05) and the need for uterotonic agents (33.3 vs. 64.5%, p < 0.05) in the oxytocin group when compared with the control group. No significant differences were found in the need for blood transfusion, uterine curettage, incidence of postpartum haemorrhage and haemoglobin level reduction. Intra-umbilical vein oxytocin injection is clinically effective for the management of a retained placenta.

Abdullah S.,National University of Malaysia | Turabieh H.,Jordan University of Science and Technology
Information Sciences | Year: 2012

Finding a good university timetabling system is not a simple task for a higher educational organisation. As a result, many approaches to generating sufficiently good solutions have been introduced. This is mainly due to the high complexity within the search landscape; moreover, each educational organisation has its own rules and specifications. In this paper, a Tabu-based memetic algorithm that hybridises a genetic algorithm with a Tabu Search algorithm is proposed as an improved algorithm for university timetabling problems. This algorithm is employed on a set of neighbourhood structures during the search process with the aim of gaining significant improvements in solution quality. The sequence of neighbourhood structures has been considered to understand its effect on the search space. Random, best and general sequences of neighbourhood structures have been evaluated in this work. The concept of a Tabu list is embedded to control the selection of neighbourhood structures that are not dependent on the problem domains during the optimisation process after the crossover and mutation operators are applied to the selected solutions from the population pool. The algorithm will penalise neighbourhood structures that are unable to generate better solutions. The proposed algorithm has been applied and evaluated against the latest methodologies in the literature with respect to standard benchmark problems. We demonstrate that the proposed algorithm produces some of the best known results when tested on ITC2007 competition datasets. © 2012 Elsevier Inc. All rights reserved.

Sukor N.,National University of Malaysia
Endocrine | Year: 2012

Primary aldosteronism is now thought to be the commonest potentially curable and specifically treatable form of hypertension. The detection of primary aldosteronism is of utmost importance not only because it provides an opportunity for a targeted treatment, but also because it has been demonstrated that patients with primary aldosteronism are more prone to cardiovascular events and target organ damage than essential hypertensives. Normalization of blood pressure and hypokalemia should not be the only goal of treatment. Normalization of circulating aldosterone or mineralocorticoid blockade is necessary to prevent aldosterone-induced tissue damage that occurs independent of blood pressure. This review will focus on the current understanding and comprehensive management review of primary aldosteronism, highlighting the new evidence that has become recently available. © Springer Science+Business Media, LLC 2011.

Patel A.,National University of Malaysia
Journal of Computer Science | Year: 2010

Problem statement: The main goal of a Web crawler is to collect documents that are relevant to a given topic in which the search engine specializes. These topic specific search systems typically take the whole document's content in predicting the importance of an unvisited link. But current research had proven that the document's content pointed to by an unvisited link is mainly dependent on the anchor text, which is more accurate than predicting it on the contents of the whole page. Approach: Between these two extremes, it was proposed that Treasure Graph, called T-Graph is a more effective way to guide the Web crawler to fetch topic specific documents predicted by identifying the topic boundary around the unvisited link and comparing that text with all the nodes of the T-Graph to obtain the matching node(s) and calculating the distance in the form of documents to be downloaded to reach the target documents. Results: Web search systems based on this strategy allowed crawlers and robots to update their experiences more rapidly and intelligently that can also offer speed of access and presentation advantages. Conclusion/Recommendations: The consequences of visiting a link to update a robot's experiences based on the principles and usage of T-Graph can be deployed as intelligent-knowledge Web crawlers as shown by the proposed novel Web search system architecture. © 2010 Science Publications.

Dovers S.R.,Australian National University | Hezri A.A.,National University of Malaysia
Wiley Interdisciplinary Reviews: Climate Change | Year: 2010

Institutions and institutional change are mentioned often but rarely specified in discussions of climate adaptation. Policy change is proposed, but the detail of policy processes less often discussed. Adaptation to increased climate change and variability will require policy interventions to change behaviors across multiple sectors, requiring policy processes constrained or enabled by institutional settings. Detailed discussion of how to redesign policy processes and institutions are especially rare at the crucial jurisdictional scales of national and sub-national policy and planning. We review coverage of policy and institutions in the adaptation literature and clarify key issues by drawing on the domains of public policy, institutional change, and sustainable development. The distinction between, but close dependencies among, institutions, institutional systems, organizations, policy processes, policy instruments, and management are emphasized. We propose that the climate policy literature has rapidly become large enough that a tendency of self-referencing has developed, and that insights can be gained from other areas. Within existing parameters of law, politics, and governance, options are identified that could embed considerations of climate adaptation into policy processes and institutional systems, with focus on enabling cross-sectoral policy integration ('mainstreaming'), decision making under conditions of uncertainty, vertical ('cross-scale') policy coordination, issues of capacity and devolution, and policy evaluation and learning. The value of seeking lessons from past policyinterventions and from cognate policy sectors is explored. © 2010 John Wiley & Sons, Ltd.

Voigt C.C.,Leibniz Institute for Zoo and Wildlife Research | Zubaid A.,National University of Malaysia | Kunz T.H.,Boston University | Kingston T.,Texas Tech University
Biotropica | Year: 2011

Dietary proteins are considered crucial for growth and maintenance in mammals, but many fruit-eating mammals feed largely on a protein-poor diet. In the Chiroptera, frugivory has evolved twice, in the Old World Pteropodidae and in the New World Phyllostomidae, especially the Stenodermatinae. Recent studies based on the analysis of nitrogen isotope ratios (δ15N) suggest that phyllostomids feed to varying degrees on arthropods to meet their nitrogen (N) requirements. Arthropod feeding has rarely been observed in Pteropodidae. Thus, we asked whether pteropodids meet their N requirements by feeding exclusively on plant matter. We predicted that tissue from pteropodid wing membranes should be depleted in 15N relative to those of obligate insectivorous rhinolophoid, vespertilionid or emballonurid bats, if pteropodids acquire proteins exclusively from fruits, leaves or nectar. We found that δ15N in pteropodids were significantly lower than in obligate insectivorous bats. In addition, mean δ15N of Old World pteropodids was similar to that of obligate frugivorous stenodermatines of the New World tropics. We infer from these data that pteropodids are predominantly phytophagous bats. From a nutritional perspective, pteropodids and stenodermatines are very similar, suggesting that they share convergent physiological adaptations to compensate for the lack of dietary nitrogen. © 2010 The Author(s). Journal compilation © 2010 by The Association for Tropical Biology and Conservation.

Draman S.F.S.,University Technology of MARA | Daik R.,National University of Malaysia | Latif F.A.,University Technology of MARA | El-Sheikh S.M.,Central Metallurgical Research and Development Institute
BioResources | Year: 2014

Interest in using kapok (Ceiba pentandra L.)-based cellulose in composite preparation is growing due to its advantages, including cost- effectiveness, light weight, non-toxicity, and biodegradability. In this study, chloroform, sodium chlorite, and sodium hydroxide were used for wax removal, delignification, and hemicellulose removal, respectively. It was observed that the air entrapment inside kapok fiber disappeared after it was treated with alkali. The structure became completely flattened and similar to a flat ribbon-like shape when examined using a vapour pressure scanning electron microscope (VPSEM). Fourier transform infrared (FTIR) spectroscopy was used to characterize the untreated and treated kapok fibers. The peak at 898 cm-1, which is attributed to the glucose ring stretching in cellulose, was observed for the obtained cellulose samples. Peaks corresponding to lignin (1505 and 1597 cm-1) and hemicellulose (1737 and 1248 cm-1) disappeared. The results of differential scanning colorimetry (DSC) indicated that the degradation of cellulose appeared as an exothermic peak at about 300 to 350 °C. The activation energy for thermal decomposition of kapok cellulose and its hemicelluloses was 185 kJ/mol and 110 kJ/mol, respectively. The activation energy for thermal decomposition can be used as an alternative approach to determine the purity of cellulose.

Mandeep J.S.,National University of Malaysia
Advances in Space Research | Year: 2012

The performance of the existing rain attenuation models in tropical zones is still a debated issue due to the lack of measurements reported from these areas of the world to develop and validate prediction models. A three-year (2003-2005) campaign of rainfall rate and rain attenuation measurements was conducted on a satellite beacon link located in a tropical region of Thailand. The cumulative distributions of rain attenuation derived from the measured data are presented and compared with those obtained with existing prediction models. © 2011 COSPAR. Published by Elsevier Ltd. All rights reserved.

Yusoff M.F.M.,University of Aarhus | Yusoff M.F.M.,National University of Malaysia | Xu X.,University of Aarhus | Guo Z.,University of Aarhus
JAOCS, Journal of the American Oil Chemists' Society | Year: 2014

Fatty acid methyl esters (FAME) were the first fatty acid esters to be introduced for use as biodiesel. However, there is a growing interest in the use of fatty acid ethyl esters (FAEE) in biodiesel. Both FAME and FAEE have their own unique advantages and disadvantages. These differences are ultimately attributable to the structural differences imparted by the alcohols used in their production. Sources of reactants as well as their safety issues, are a focus of this review. Also reviewed are the comparative characteristics and properties of both biodiesel types in terms of physicochemical features and performance. Processing requirements, reaction times and molar ratios of alcohol to oil, together with problems and drawbacks, are discussed. Recent developments on improving the yield of biodiesel, include mixing methanol and ethanol in the same reaction with ethanol acting as a co-solvent, and enzymatic methanolysis and ethanolysis are also highlighted. © 2014 AOCS.

Ho C.C.,National University of Malaysia
Acta medica (Hradec Králové) / Universitas Carolina, Facultas Medica Hradec Králové | Year: 2011

Summary: Ventriculoperitoneal shunts are associated with multiple complications. Among them are disconnection and migration of the tubing into the peritoneal cavity. Here we describe a case of a fractured ventriculoperitoneal shunt which migrated and coiled in the scrotum, masquerading as a scrotal swelling. Removal of the shunt via a scrotal incision was performed concomitantly with repair of the hernia sac.

Chua K.B.,National University of Malaysia
Malaysian Journal of Pathology | Year: 2010

The outbreak of Nipah virus, affecting pigs and pig-farm workers, was first noted in September 1998 in the north-western part of peninsular Malaysia. By March 1999, the outbreak had spread to other pig-farming areas of the country, inclusive of the neighbouring country, Singapore. A total of 283 human cases of viral encephalitis with 109 deaths were recorded in Malaysia from 29 September 1998 to December 1999. During the outbreak period, a number of surveillances under three broad groups; Surveillance in Human Health Sector, Surveillance in Animal Health Sector, and Surveillance for the Reservoir Hosts, were carried out to determine the prevalence, risk of virus infections and transmission in human and swine populations as well as the source and reservoir hosts of Nipah virus. Surveillance data showed that the virus spread rapidly among pigs within infected farms and transmission was attributed to direct contact with infective excretions and secretions. The spread of the virus among pig farms within and between states of peninsular Malaysia was due to movement of pigs. The transmission of the virus to humans was through close contact with infected pigs. Human to human transmission was considered a rare event though the Nipah virus could be isolated from saliva, urine, nasal and pharyngeal secretions of patients. Field investigations identifi ed fruitbats of the Pteropid species as the natural reservoir hosts of the viruses. The outbreak was effectively brought under control following the discovery of the virus and institution of correct control measures through a combined effort of multi-ministerial and multidisciplinary teams working in close co-operation and collaboration with other international agencies.

Chua K.B.,National University of Malaysia
Malaysian Journal of Pathology | Year: 2010

An outbreak of acute febrile encephalitis affecting pig-farm workers and owners was recognized in peninsular Malaysia as early as September 1998. The outbreak was initially thought to be due to Japanese encephalitis (JE) virus and thus very intensive prevention, control and communication strategies directed at JE virus were undertaken by the Ministry of Health and Ministry of Agriculture of Malaysia. There was an immediate change in the prevention, control and communication strategies with focus and strategies on infected pigs as the source of infections for humans and other animals following the discovery of Nipah virus. Information and understanding the risks of Nipah virus infections and modes of transmission strengthened the directions of prevention, control and communication strategies. A number of epidemiological surveillances and fi eld investigations which were broadly divided into 3 groups covering human health sector, animal health sector and reservoir hosts were carried out as forms of risk assessment to determine and assess the factors and degree of risk of infections by the virus. Data showed that there was signifi cant association between Nipah virus infection and performing activities involving close contact with pigs, such as processing of piglets, administering injection or medication to pigs, assisting in the birth of piglets, assisting in pig breeding, and handling of dead pigs in the affected farms. A complex process of anthropogenic driven deforestation, climatic changes brought on by El Niño-related drought, forest fi re and severe haze, and ecological factors of mixed agro-pig farming practices and design of pig-sties led to the spillovers of the virus from its wildlife reservoir into pig population.

Choudhury P.K.,National University of Malaysia
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

Propagation characteristics of optical fibers are greatly dependent on materials, which the guides are comprised of. Varieties of materials have been developed and investigated for their usage in fabricating optical fibers for specific applications. Within the context, a liquid crystal medium is both inhomogeneous and optically anisotropic, and fibers made of such mediums are greatly useful. Also, liquid crystals exhibit strong electro-optic behavior, which allows alternation in their optical properties under the influence of external electric fields. These features make liquid crystal fibers greatly important for optical applications. The present communication is aimed at providing a glimpse of the efficacy of liquid crystals and/or fibers made of liquid crystals, followed by the analytical investigation of wave propagation through such guides. The sustainment of modes is explored in these fibers under varying fiber dimensions, and the novelty is discussed. The case of tapered liquid crystal fibers is also briefly discussed highlighting the usefulness. Control on the dispersion characteristics of such fibers may be imposed by making the guide even more complex; the possibility of devising such options is also touched upon. © 2013 Copyright SPIE.

Ali F.,National University of Malaysia
Electronic Journal of Geotechnical Engineering | Year: 2012

There are numerous soil stabilization techniques for improving the strength of the in-situ soil especially in road construction, and one of the techniques is using chemical additive. Chemical improvement is a time saving method that enables subgrade or sub-base layer and otherwise unsatisfactory materials in-situ to obtain higher density and strength, obviating the need for costly excavation and replacement with borrow material. This paper presents some results of the preliminary stages of research program carried out to explicate the mechanism and behavior between the liquid chemical and the engineering properties of three natural residual soils at laboratory scale. Liquid-formed chemical was selected in this research due to scarcity of such findings instead of the prevalent solid chemical additive such as lime, cement or fly ash. The focus on this research is on the improvement of engineering properties of three natural residual soils and mixed with different proportions of liquid chemical. Series of laboratory test on engineering properties, such as unconfined compressive strength (UCS), consistency limits, moisture-density relationship (compaction) was undertaken to evaluate the effectiveness and performances of this chemical as soil stabilizing agent. The results show that addition of the liquid stabilizer can reduce the shrinkage and plasticity of the soil as well as the optimum moisture content. Subsequently, the maximum dry density and the compressive strength are increased.

Suparta W.,National University of Malaysia
Meteorology and Atmospheric Physics | Year: 2012

A katabatic wind event which dramatically affects the polar climate has been detected using GPS meteorology measurements. GPS-derived precipitable water vapor (GPS PWV) variability and its relation to a katabatic event at Scott Base station, Antarctica was investigated. The investigations using the data gathered from 21 to 30 November of 2002. They showed that the water vapor profile exhibited an irregular pattern with a maximum PWV of 7.38 mm (~6 mm on average). This event was strongly influenced by relative humidity than by wind speed activity. The dominant wind flow during this period was from the North to Northeast (blowing from the Ross Sea) with a mean speed of 3.79 ms -1. The PWV increased when the temperature was between -15 and -11°C. During the katabatic event identified between 21:30 UT of 28 November and 18:40 UT on 29 November, the wind blew from the Southeast to South direction (from the Ross Ice Shelf) with a maximum speed of 10.92 ms -1. The PWV increased ~1.0 mm (23%) from the mean value accompanied by severe wind had pronounced effect on GPS observations. © 2012 Springer-Verlag.

Ho S.E.,National University of Malaysia
La Clinica terapeutica | Year: 2013

Nurses play a pivotal role in pain management. Unrelieved pain significantly interferes with patient's quality of life and is of great concern to nurses. The aim of this study was to determine the knowledge level and attitudes of nurses related to pain management. This descriptive study was conducted in an urban hospital. A total of 84 registered nurses were recruited using a modified version of questionnaire of Knowledge and Attitudes Survey Regarding Pain. The findings showed that respondents possessed good knowledge (99.12±14.810) and attitude (66.00 ±10.415) towards pain management. Fifty five respondents (66%) responded as positive to cultural beliefs affecting their pain management and 65 respondents (77%) viewed that their personal experiences had influenced their practice in pain management. Another 45 respondents (54%) reported they have attended pain course. There was no significant difference in pain management between respondents' year of service, cultural belief and personal experiences (p=>0.05). In terms of knowledge towards to pain management, respondents' age groups of more than 40 years were noted to possess better knowledge (p=0.046), unmarried respondents (p=0.018), and attended pain course (p=0.001) were significant. Attitude towards to pain management was not significant (p≤0.05). Nurses' knowledge and attitudes scores were impressive but there is room for further improvement to pain management. Continuing education organized by the hospital had significant impact on the nurses. However, this education course has to be reinforced from time to time in order to improve patients' pain experiences.

Togun H.,University of Malaya | Togun H.,University of Thi-Qar | Abdulrazzaq T.,University Putra Malaysia | Kazi S.N.,University of Malaya | And 3 more authors.
Renewable and Sustainable Energy Reviews | Year: 2014

The enhancement of the thermal performance of heat exchanging equipment transport energy at low financial cost by various techniques is presented in this review. Various annular passage configurations have been used in the reviewed studies, namely circular, ellipse, rectangular, square, triangular, and rhombic annular channels with different fluid and boundary conditions. The effect of eccentricity in both horizontal and vertical directions on heat transfer rate in most numerical and experimental investigations for horizontal and vertical annular passages is studied. The effects of heater length, as well as the Darcy, Prandtl, Reynolds, Grashof and Rayleigh numbers on heat transfer in concentric and eccentric annular passages are also investigated. In case of rotating the inner, outer or both cylinders of the annular cylinder arrangement, the generated secondary flow influences the heat transfer to fluid flow in an annular passage. The effect of nanofluid on the increased enhancement of heat transfer in an annular channel is presented. Related studies on curved, covered annular channels showed augmented heat transfer rate in comparison with straight annular channels. In this review, a good agreement is evident between experimental and numerical data, which could help researchers design thermal systems supported by annular passages with the goal of retarding energy consumption by equipment and machineries in applications that could ultimately contribute to appeasing the global energy crisis. © 2014 Elsevier Ltd.

Abbasbandy S.,Imam Khomeini International University | Roohani Ghehsareh H.,Imam Khomeini International University | Hashim I.,National University of Malaysia
Engineering Analysis with Boundary Elements | Year: 2013

In this paper, an efficient numerical technique is developed to approximate the solution of two-dimensional cubic nonlinear Schrödinger equations. The method is based on the nonsymmetric radial basis function collocation method (Kansa's method), within an operator Newton algorithm. In the proposed process, three-dimensional radial basis functions (especially, three-dimensional Multiquadrics (MQ) and Inverse multiquadrics (IMQ) functions) are used as the basis functions. For solving the resulting nonlinear system, an algorithm based on the Newton approach is constructed and applied. In the multilevel Newton algorithm, to overcome the instability of the standard methods for solving the resulting ill-conditioned system an interesting and efficient technique based on the Tikhonov regularization technique with GCV function method is used for solving the ill-conditioned system. Finally, the presented method is used for solving some examples of the governing problem. The comparison between the obtained numerical solutions and the exact solutions demonstrates the reliability, accuracy and efficiency of this method. © 2013 Elsevier Ltd.

Ishak A.,National University of Malaysia | Yacob N.A.,University Technology of MARA | Bachok N.,University Putra Malaysia
Meccanica | Year: 2011

The steady laminar boundary layer flow over a moving plate in a moving fluid with convective surface boundary condition and in the presence of thermal radiation is investigated in this paper. Under certain conditions, the present problem reduces to the classical Blasius and Sakiadis problems. The effects of radiation and convective parameters on the thermal field are thoroughly examined and discussed. Dual solutions are found to exist when the plate and the fluid move in the opposite directions. © 2010 Springer Science+Business Media B.V.

Latiff A.,National University of Malaysia
Malaysian Applied Biology | Year: 2016

Malaysia has initiated, produced and launched a National Policy on Biological Diversity in 1998 which contains policy statement, principles, objectives, rationales, strategies and above all action plans of programmes. The policy places great importance on taxonomy in realising the true dimension of biodiversity in the country and that taxonomy is a cornerstone of biodiversity has long been accepted and understood. Yet, many taxonomic institutions such as National Natural History Museum and National Herbarium are not within sight. Taxonomy is not prioritised within the R & D mechanism, capacity building is not undertaken with an accepted vigour, systematic research centres are not established, school and university curricula have not addressed taxonomic curricula, proper training of taxonomists and parataxonomists are not planned, and data management is not adequately placed either. Ironically the rate of ecosystem and habitat degradation and loss, species loss and genetic erosion are occurring at a rate unsur ssed in the past. Is there any crisis in Malaysian taxonomy and plant taxonomy in particular? The taxonomic community is small and aged. The reference collections are still small, the scientific productivity in term of publication of papers to report new species, new records, taxonomic revisions, phylogenetic relationships, variations, species loss and conservation efforts are still inadequate. The floristic treatments for the Tree Flora of Sabah and Sarawak and the Flora of Peninsular Malaysia are going-on. An attempt is made here to relate the richness of biodiversity to taxonomy so that the latter’s impediments could be properly addressed. There must be coordinated efforts to overcome the real taxonomic impediments in Malaysia. © 2016, Malaysian Society of Applied Biology. All rights reserved.

Farahani G.N.,Islamic Azad University | Ahmad I.,National University of Malaysia | Mosadeghzad Z.,Islamic Azad University
Polymer - Plastics Technology and Engineering | Year: 2012

Kenaf fibers were mixed with unsaturated polyester resin (UPR), which was prepared by recycling of polyethylene therephthalate (PET) waste bottles. Grinded PET waste bottles were subjected to recycle by glycolysis which was used to prepare unsaturated polyester resin. The resin was then mixed with kenaf fibers in two different lengths (2.5 and 5 mm) at different fiber loading (2.5 and 5 phr of kenaf in UPR resin). The effects of fiber content, fiber size and surface treatment on the mechanical properties, density and water absorption of the composite were studied. The SEM and FTIR analysis were used to analyse the influence of alkali treatment on fibers and interfacial interaction between fibers and matrix. The results show that the optimum values of the stiffness properties and impact strength is at 2.5 phr, whereas tensile strength decreases with increasing fiber content. The length of fiber played a significant role in some of the mechanical properties of the composites with 5 mm fiber length has higher mechanical properties than 2.5 mm length. The results also showed that alkali treatment causes a better adhesion between the fiber and UPR matrix and improves the mechanical properties of the composites. Furthermore, surface treatment reduced the water absorption of composites. © 2012 Copyright Taylor and Francis Group, LLC.

Aziz R.C.,University of Kuala Lumpur | Hashim I.,National University of Malaysia | Alomari A.K.,Jerash Private University
Meccanica | Year: 2011

This research studied the influence of internal heat generation on flow and heat transfer in a thin liquid film on an unsteady stretching sheet. The velocity and temperature fields were solved using the Homotopy Analysis Method (HAM), taking a general surface temperature into consideration. The analytical series solution are presented and the numerical results obtained are tabulated. The effects of unsteadiness parameter, Prandtl number and temperature-dependent parameter in this study are discussed and presented graphically via the velocity and temperature profiles. © Springer Science+Business Media B.V. 2010.

Yacob N.A.,University Technology of MARA | Ishak A.,National University of Malaysia | Ishak A.,University of Malaya | Pop I.,Technical University of Cluj Napoca
International Journal of Thermal Sciences | Year: 2011

The steady two-dimensional boundary layer flow past a static or a moving wedge immersed in nanofluids is investigated numerically. An implicit finite difference scheme known as the Keller-box method and the NAG routine DO2HAF are used to obtain the numerical solutions. Three different types of nanoparticles, namely copper Cu, alumina Al2O3 and titania TiO 2 with water as the base fluid are considered. The effects of the governing parameters on the fluid flow and heat transfer characteristics are analyzed and discussed. It is found that Cu-water has the highest skin friction coefficient and the heat transfer rate at the surface compared with the others. The effect of the solid volume fraction of nanoparticles on the fluid flow and heat transfer characteristics is found to be more pronounced compared to the type of the nanoparticles. © 2010 Elsevier Masson SAS. All rights reserved.

Choudhury P.K.,National University of Malaysia | Soon W.K.,PepperlFuchs Manufacturing Pte Ltd
Progress in Electromagnetics Research | Year: 2011

The paper presents an analytical investigation of a tapered core optical fiber of which the outermost section is loaded with radially anisotropic liquid crystal. The analyses are dealt with transverse modes supported in the fiber structure followed by the relative distribution of power in the different fiber sections. Preliminary dispersion characteristics of the guide are also illustrated. The results demonstrate that the TE modes transport very large amount of power in the outermost liquid crystal region - the criteria much useful for fiber optic sensing and field coupling devices.

Sukor N.,National University of Malaysia
European Journal of Internal Medicine | Year: 2011

Hypertension is a very common disease, leading to significant morbidity with reduction in quality of life. In addition to being a major cause of morbidity and mortality, hypertension places a heavy burden on health care systems, families, and society as a whole. In patients with hypertension, the ability to identify a contributing or secondary cause that is potentially curable or amenable to specific forms of management is of great importance. Endocrine hypertension has emerged as one of the common forms of secondary hypertension. Primary aldosteronism, pheochromocytoma and Cushing's syndrome are among the common causes of endocrine hypertension. The application of new clinical, biochemical, and radiologic approaches has significantly advanced our understanding of the pathophysiology and clinical spectrum of these diseases and improved the management strategies of these challenging conditions. © 2011 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

Mohmad A.R.,University of Sheffield | Mohmad A.R.,National University of Malaysia | Bastiman F.,University of Sheffield | Sweeney S.J.,University of Surrey | David J.P.R.,University of Sheffield
Applied Physics Letters | Year: 2011

Photoluminescence (PL) of GaAs0.97 Bi0.03 alloy was measured over a wide range of temperatures and excitation powers. Room temperature PL with peak wavelength of 1038 nm and full-width-half-maximum of 75 meV was observed which is relatively low for this composition. The improved quality is believed due to reduced alloy fluctuations by growing at relatively high temperature. The temperature dependence of PL peak energy indicated significant exciton localization at low temperatures. Furthermore, the band gap temperature dependence was found to be weaker than GaAs. An analysis of dominant carrier recombination mechanism(s) was also carried out indicating that radiative recombination is dominant at low temperature. © 2011 American Institute of Physics.

Hamidah A.,National University of Malaysia
Tropical medicine & international health : TM & IH | Year: 2014

To determine the behavioural impact of chemotherapy in survivors of acute lymphoblastic leukaemia (ALL) treated with chemotherapy only and to identify treatment-related or sociodemography-related factors that might be associated with behavioural outcome. We examined 57 survivors of childhood ALL, who were off treatment for at least 2 years and were in remission, aged 4-18 years, and 221 unrelated healthy controls. The Child Behaviour Checklist (CBCL) parent report was used either in English or in Bahasa Malaysia (the national language of Malaysia) to assess the behavioural outcome. Childhood ALL survivors had significantly higher scores on externalising behaviour on the CBCL parent report than did controls. Higher problem scores were found in ALL survivors with single parents on 'total problems' (P = 0.03) and subscales 'withdrawn' (P = 0.03), 'social problems' (P < 0.01) and 'delinquent behaviour' (P = 0.03) than in survivors with married parents. Significant associations were seen between a lower education level of the father and the variables representing internalising (withdrawn, anxious/depressed) and externalising (aggressive behaviour). We observed trends on higher scores in all scales in ALL survivors with single parents than in controls with single parents or with fathers with low education level, especially primary education only. Malaysian childhood ALL survivors had a significantly increased risk for externalising behavioural problems, and there was a trend towards increased risk of problems in many other behavioural scales. Understanding the sociocultural dimension of patients' health is important to be able to design the most appropriate remedy for problem behaviours detected in this multi-ethnic population. © 2014 John Wiley & Sons Ltd.

Md Jahim J.M.,National University of Malaysia
Advanced Materials Research | Year: 2011

Palm oil mill effluent (POME) contains approximately 6% fiber. The effectiveness of pre-treatment on POME can serve a very good feedstock for hydrogen production in fermentation process. In this research, the effectiveness of pre-treatment methods on POME treated using acid and base were analysed based total carbohydrate and reducing sugar content. By using 1M NaOH with heat treatment, 26.12% carbon source converted to reducing sugar while by using 1M H2SO4with heat treatment, over 32.09% carbon source converted to reducing sugar. The highest increment of total carbohydrate where from acid-heat treatment with 26.1% increment from initial concentration. At the initial pH (5.5) with fermentation temperature 37°C, the highest hydrogen production rate given by acid-heat treatment was 0.5mL H2/mL POME. Different for initial pH 7.0 with the same temperature, the highest hydrogen produced rate was given by base-heat treatment with 0.59 mL H2/mL POME. The production of hydrogen in 2L bioreactor given much higher hydrogen production compare to production in serum bottle. This fermentation was run in batch mode with initial pH 7 and control at 5.5. The maximum hydrogen produce was 4304 mL H2/ L POME from acid-heat treatment. © (2011) Trans Tech Publications.

Alias M.S.,Telekom Malaysia Research and Development | Shaari S.,National University of Malaysia
Journal of Lightwave Technology | Year: 2010

A new technique for analyzing the loss of high order modes in photonic crystal VCSEL is reported. The technique proposed is a semi-empirical approach that uses comparison to experimental data. For that purpose, photonic crystal VCSEL devices of single mode and multi mode are fabricated and measured for device characteristics comparison. The fabricated devices are modeled using finite difference frequency domain technique for the purpose of investigating the photonic crystal guided modes and loss analysis. In order to verify the findings, full three dimensional analyses are performed based on the fabricated single mode and multi mode devices structures using common finite difference time domain technique. The results show close agreement between the computed and experiment findings, justifying the used of the proposed semi-empirical technique for analyzing the loss of high order modes in photonic crystal VCSEL. Results for guided modes and near- and far-field are also presented for the photonic crystal VCSEL. © 2010 IEEE.

Abdul Kadir N.B.,National University of Malaysia | Bifulco A.,Middlesex University
Psychiatry Research | Year: 2013

The role of marital breakdown in women's mental health is of key concern in Malaysia and internationally. A cross-sectional questionnaire study of married and separated/divorced and widowed women examined insecure attachment style as an associated risk factor for depression among 1002 mothers in an urban community in Malaysia. A previous report replicated a UK-based vulnerability-provoking agent model of depression involving negative evaluation of self (NES) and negative elements in close relationships (NECRs) interacting with severe life events to model depression. This article reports on the additional contribution of insecure attachment style to the model using the Vulnerable Attachment Style Questionnaire (VASQ). The results showed that VASQ scores were highly correlated with NES, NECR and depression. A multiple regression analysis of depression with backward elimination found that VASQ scores had a significant additional effect. Group comparisons showed different risk patterns for single and married mothers. NES was the strongest risk factor for both groups, with the 'anxious style' subset of the VASQ being the best additional predictor for married mothers and the total VASQ score (general attachment insecurity) for single mothers. The findings indicate that attachment insecurity adds to a psychosocial vulnerability model of depression among mothers cross-culturally and is important in understanding and identifying risk. © 2013 Elsevier Ireland Ltd.

Latiff A.,National University of Malaysia
Pakistan Journal of Botany | Year: 2012

Ecosystem diversity in Malaysia is represented by various terrestrial and aquatic ecosystems from deep seas to montane forests. Species diversity is represented by about 15,000 plant species and more than 6000 animal species, excluding insects, the largest and most diverse group which is inadequately known. As the country is pursuing for industrialization conflicts may necessarily occur for biodiversity conservation and socio-economic development, unless strict sustainable development is adopted. Currently 1.39 million ha (about 7.6%) area under forests of all types has been set aside for biodiversity conservation including mangrove swamp forests. However, a framework for managing biodiversity in protected areas especially that of mangrove ecosystem is inadequate. The country is yet to define priorities for conservation and sustainable use of ecosystem diversity. The impacts of eco-tourism, agriculture and urbanization on mangrove forests are yet to be ascertained. In the absence of concrete data of mangrove biodiversity loss it is difficult to assess the vulnerability of this fragile ecosystem in the light of looming socio-economic development. Many factors contributing to mangrove loss include rapid socio-economic development of the country that has transformed vast mangrove forests for agriculture and resettlement and subsequently created semi-urban and industrial areas which are relatively poor in mangroves. These changing land-use patterns are affecting not only mangrove ecosystems but also the environment per se. Other factor such as pollution had also contributed in small part. These activities had led to significant mangrove loss, degradation and fragmentation. The strategies needed for mangrove biodiversity include assessment of land-use patterns, benefit sharing mechanism and some legal measures for sustainable use and protection of mangrove biodiversity.

Sakthiswary R.,National University of Malaysia | Suresh E.,Alexandra Hospital Jurong Health
Lupus | Year: 2014

Objective: The objective of this review is to evaluate the evidence for efficacy of methotrexate (MTX) in systemic lupus erythematosus (SLE). Methods: A comprehensive, computerized search was performed in MEDLINE (PubMed), EMBASE and the Cochrane Controlled Trials registry to screen for studies that examined the efficacy of MTX in adult SLE patients. The Jadad scoring system was used to assess study quality, and data were pooled using the random effects model. Results: Of the 53 articles that were identified, 44 were excluded. Nine studies (including three randomized controlled and six observational) were eligible for inclusion. All of the included studies predominantly involved patients with arthritis or mucocutaneous features. There was significant reduction of the SLE Disease Activity Index (SLEDAI) among MTX-treated patients when compared with controls (p=0.001, odds ratio (OR) 0.444, 95% confidence interval (CI) 0.279 to 0.707). There was also significant reduction in the average dose of corticosteroids among MTX-treated patients when compared with controls (p=0.001, OR 0.335, 95% CI 0.202 to 0.558). The effect of MTX on laboratory and serological markers, including erythrocyte sedimentation rate, anti-dsDNA and complement levels (C3 and C4), could not be determined because of the limited numbers of controlled trials. Conclusion: The use of MTX is associated with significant reductions in SLEDAI and the average dose of corticosteroids in adult patients with SLE. © The Author(s), 2013.

Samun M.A.-A.,National University of Malaysia
Research Journal of Applied Sciences | Year: 2012

A community service order is one that is viewed to be highly appropriate for juvenile offenders. However, there is still a void where extensive legalistic studies discussing this order should be, especially from the aspect of theoretical framework. In relation to this the purpose of this research is to debate the pros and cons of community service orders from the aspect of theoretical framework. This research finds that community service orders are based on rehabilitation theory and that they put the best interest of the child or juvenile first. The juvenile offenders will be integrated with society through community service orders and this process will simultaneously decrease the rate of recidivism and increase the potential for their rehabilitation.A community service order is one that is viewed to be highly appropriate for juvenile offenders. However, there is still a void where extensive legalistic studies discussin this order should be, especially from the aspect of theoretical framework. In relation to th the purpose of this research is to debate the pros and cons of community service orders from the aspect of theoretical framework. This research finds that community service orders are base on rehabilitation theory and that they put the best interest of the child or juvenile fir. Th juvenile offenders will be integrated with society through community service orders and this process will simultaneously decrease the rate of recidivism and increase the potential for their rehabilitation. © Medwell journals, 2012.

Vreeburg R.A.M.,Institute of Molecular Plant science | Airianah O.B.,Institute of Molecular Plant science | Airianah O.B.,National University of Malaysia | Fry S.C.,Institute of Molecular Plant science
Biochemical Journal | Year: 2014

Hydroxyl radicals (•OH) cause non-enzymic scission of polysaccharides in diverse biological systems. Such reactions can be detrimental (e.g. causing rheumatic and arthritic diseases in mammals) or beneficial (e.g. promoting the softening of ripening fruit, and biomass saccharification). Here we present a method for documenting •OH action, based on fluorescent labelling of the oxo groups that are introduced as glycosulose residues when •OH attacks polysaccharides. The method was tested on several polysaccharides, especially pectin, after treatment with Fenton reagents. 2-Aminoacridone plus cyanoborohydride reductively aminated the oxo groups in treated polysaccharides; the product was then reacted with acetone plus cyanoborohydride, forming a stable tertiary amine with the carbohydrate linked to N-isopropyl-2-aminoacridone (pAMAC). Digestion of labelled pectin with 'Driselase' yielded several fluorescent products which on electrophoresis and HPLC provided a useful 'fingerprint' indicating •OH attack. The most diagnostic product was a disaccharide conjugate of the type pAMAC·UA-GalA (UA = unspecified uronic acid), whose UA-GalA bond was Driselaseresistant (product 2A). 2Awas clearly distinguishable fromGalAGalA-pAMAC (disaccharide labelled at its reducing end), which was digestible to GalA-pAMAC. The methodology is applicable, with appropriate enzymes in place of Driselase, for detecting natural and artificial •OH attack in diverse plant, animal and microbial polysaccharides. © 2014 The Author(s).

Bhadauria B.S.,Babasaheb Bhimrao Ambedkar University | Hashim I.,National University of Malaysia | Siddheshwar P.G.,Bangalore University
Transport in Porous Media | Year: 2013

The effects of time-periodic boundary temperatures and internal heating on Nusselt number in the Bénard-Darcy convective problem has been considered. The amplitudes of temperature modulation at the lower and upper surfaces are considered to be very small. By performing a weakly non-linear stability analysis, the Nusselt number is obtained in terms of the amplitude of convection, which is governed by the non-autonomous Ginzburg-Landau equation, derived for the stationary mode of convection. The effects of internal Rayleigh number, amplitude and frequency of modulation, thermo-mechanical anisotropies, and Vadasz number on heat transport have been analyzed and depicted graphically. Increasing values of internal Rayleigh number results in the enhancement of heat transport in the system. Further, the study establishes that the heat transport can be controlled effectively by a mechanism that is external to the system. © 2013 Springer Science+Business Media Dordrecht.

Hassan C.H.,National University of Malaysia
Acta medica (Hradec Králové) / Universitas Carolina, Facultas Medica Hradec Králové | Year: 2011

Ruptured pregnancy in the rudimentary horn of women who have had a vaginal delivery is rare and unpredictable. However, when undiagnosed, this condition could lead to maternal morbidity and mortality. We report a pregnancy at 19 weeks gestation presented with acute abdomen and hypovolemic shock. She was initially thought to have an intrauterine pregnancy with the provisional diagnosis of a ruptured uterus. Intraoperatively, a ruptured non-communicating right rudimentary horn with ex utero pregnancy was discovered.

Chong S.K.,University of Malaya | Goh B.T.,University of Malaya | Dee C.F.,National University of Malaysia | Rahman S.A.,University of Malaya
Materials Chemistry and Physics | Year: 2012

Silicon nanowires (SiNWs) were synthesized from indium catalysts on the Si(111) substrate using the hot-wire chemical vapor deposition technique. A tungsten filament with purity of 99.95% was employed for both the evaporation of an indium wire as catalyst and the decomposition of the precursor gas silane diluted in hydrogen. In this study, we investigated the role of the filament temperature (T f) on the growth and structural properties of the SiNWs. A threshold T f for the successive growth of the SiNWs via a vapor-liquid-solid process was observed at T f between 1400 and 1500°C. For T f of 1400°C and below, only a layer of Si shell cladding was formed on the indium core. An increase in T f above the threshold resulted in a significant increase in the number density and the aspect ratio of the SiNWs. X-ray diffraction and micro-Raman measurements indicated an enhancement in crystallinity of the SiNWs with the increase in T f. Fourier transform infrared analysis showed an enhancement in the presence of Si-O and Si-H related bonds with the increase in T f. The Si-O bond is mostly originated from the native oxide layer of SiNWs, while Si-H bond suggests that Si-H x species were responsible for the growth. © 2012 Elsevier B.V. All rights reserved.

Othman M.R.,National University of Malaysia
International Journal of Electrochemical Science | Year: 2015

Cu(OH)2 have been synthesized by electrochemistry technique using Cu and Cu-PVC electrodes in alkaline solution. The electrolysis process was carried out in 0.1 M KOH supporting electrode at room temperature. Experiments were performed in a three electrodes system using Cu and Cu-PVC as a working electrode, SCE as reference electrode and platinum wire as the counter electrode. The electrolysis of was performed using potential constant (1050 mV) in 50 mL capacity glass electrochemical cell. Universal Pulsa Dynamic EIS, Cyclic Voltammetry, Voltalab potentiostat (Model PGZ 402) was used for electrochemical behavior measurements. XRD and XPS have been used to characterize the morphology, structure, and composition of the compounds at electrode surface. The results of this experiment shown the Cu(OH)2 is main product and higher purity. The advantages of our method for the Cu(OH)2 synthesis are low temperature, simple, inexpensive, non-toxic raw materials and environmentally friendly. © 2015 The Authors.

Ng K.M.,University Technology of MARA | Reaz M.B.I.,National University of Malaysia
PLoS ONE | Year: 2016

Platoon based traffic flow models form the underlying theoretical framework in traffic simulation tools. They are essentially important in facilitating efficient performance calculation and evaluation in urban traffic networks. For this purpose, a new platoon-based macroscopic model called the LWR-IM has been developed in [1]. Preliminary analytical validation conducted previously has proven the feasibility of the model. In this paper, the LWR-IM is further enhanced with algorithms that describe platoon interactions in urban arterials. The LWR-IM and the proposed platoon interaction algorithms are implemented in the real-world class I and class II urban arterials. Another purpose of the work is to perform quantitative validation to investigate the validity and ability of the LWR-IM and its underlying algorithms to describe platoon interactions and simulate performance indices that closely resemble the real traffic situations. The quantitative validation of the LWR-IM is achieved by performing a two-sampled t-test on queues simulated by the LWR-IM and real queues observed at these real-world locations. The results reveal insignificant differences of simulated queues with real queues where the p-values produced concluded that the null hypothesis cannot be rejected. Thus, the quantitative validation further proved the validity of the LWR-IM and the embedded platoon interactions algorithm for the intended purpose. © 2016 Ng, Reaz.This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Salleh M.Z.,Universiti Malaysia Pahang | Nazar R.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
Journal of the Taiwan Institute of Chemical Engineers | Year: 2010

The steady boundary layer flow and heat transfer over a stretching sheet with Newtonian heating in which the heat transfer from the surface is proportional to the local surface temperature, is considered in this study. The transformed governing nonlinear boundary layer equations are solved numerically by a finite-difference method. Numerical solutions are obtained for the heat transfer from the stretching sheet and the wall temperature for a large range of values of the Prandtl number Pr. The Newtonian heating is controlled by a dimensionless conjugate parameter, which varies between zero (insulated wall) and infinity (wall temperature remains constant). The important findings in this study are the variation of the surface temperature and heat flux from the stretching surface with the conjugate parameter and Prandtl number. It is found that these parameters have essential effects on the heat transfer characteristics. © 2010 Taiwan Institute of Chemical Engineers.

El-Shafie A.,National University of Malaysia | Noureldin A.,Royal Military College of Canada
Hydrology and Earth System Sciences | Year: 2011

Artificial neural networks (ANN) have been found efficient, particularly in problems where characteristics of the processes are stochastic and difficult to describe using explicit mathematical models. However, time series prediction based on ANN algorithms is fundamentally difficult and faces problems. One of the major shortcomings is the search for the optimal input pattern in order to enhance the forecasting capabilities for the output. The second challenge is the over-fitting problem during the training procedure and this occurs when ANN loses its generalization. In this research, autocorrelation and cross correlation analyses are suggested as a method for searching the optimal input pattern. On the other hand, two generalized methods namely, Regularized Neural Network (RNN) and Ensemble Neural Network (ENN) models are developed to overcome the drawbacks of classical ANN models. Using Generalized Neural Network (GNN) helped avoid over-fitting of training data which was observed as a limitation of classical ANN models. Real inflow data collected over the last 130 years at Lake Nasser was used to train, test and validate the proposed model. Results show that the proposed GNN model outperforms non-generalized neural network and conventional auto-regressive models and it could provide accurate inflow forecasting. © 2011 Author(s).

Siow K.S.,University of South Australia | Siow K.S.,National University of Malaysia | Kumar S.,University of South Australia | Griesser H.J.,University of South Australia
Plasma Processes and Polymers | Year: 2015

This review surveys low-pressure plasma-based methods for producing hydrophilic and hydrogel-like bio-interface coatings without reactive functional groups in aqueous media. The main focus of the review is one-step plasma polymerization; other plasma-based methods such as plasma with grafting are also discussed within the context of monomers used, process development, ageing properties, and interaction of these coatings with proteins and cells. Coatings containing polyethylene glycol (PEG) or polyethylene oxide (PEO), acrylamides such as N-isopropylacrylamide (NIPAM), and sulfonate (SO3) or sulfate (SO4) moieties are reviewed here. © 2014 Wiley-VCH Verlag GmbH & Co. KGaA.

Chili hotness is very much dependent on the concentration of capsaicin present in the chili fruit. A new biosensor based on a horseradish peroxidase enzyme-capsaicin reaction mediated by ferrocene has been successfully developed for the amperometric determination of chili hotness. The amperometric biosensor is fabricated based on a single-step immobilization of both ferrocene and horseradish peroxidase in a photocurable hydrogel membrane, poly(2-hydroxyethyl methacrylate). With mediation by ferrocene, the biosensor could measure capsaicin concentrations at a potential 0.22 V (vs. Ag/AgCl), which prevented potential interference from other electroactive species in the sample. Thus a good selectivity towards capsaicin was demonstrated. The linear response range of the biosensor towards capsaicin was from 2.5-99.0 μM with detection limit of 1.94 μM. A good relative standard deviation (RSD) for reproducibility of 6.4%-9.9% was obtained. The capsaicin biosensor demonstrated long-term stability for up to seven months. The performance of the biosensor has been validated using a standard method for the analysis of capsaicin based on HPLC.

Suparta W.,National University of Malaysia
Journal of Physics: Conference Series | Year: 2014

We have developed an efficient tool to process dual-frequency Global Positioning System (GPS) signals and the surface meteorological data, called the Tropospheric Water Vapor (TroWav) program. TroWav is a stand-alone program to compute atmospheric precipitable water vapor (PWV). The source of the program is developed using MatlabTM and the graphical user interface for the system was developed using a Visual Basic. The algorithms of the program capable to compute satellite elevation angle, Zenith Tropospheric Delay (ZTD), Zenith Hydrostatic Delay (ZHD), Zenith Wet Delay (ZWD) and mapping function. The tool is very practical and useful for sustainable atmospheric management.

Yazid H.,University Malaysia Perlis | Arof H.,University of Malaya | Mohd Isa H.,National University of Malaysia
Measurement: Journal of the International Measurement Confederation | Year: 2012

This paper presents a new approach to detect exudates and optic disc from color fundus images based on inverse surface thresholding. The strategy involves the applications of fuzzy c-means clustering, edge detection, otsu thresholding and inverse surface thresholding. The main advantage of the proposed approach is that it does not depend on manually selected parameters that are normally chosen to suit the tested databases. When applied to two sets of databases the proposed method outperforms methods based on watershed segmentation and morphological reconstruction. The proposed method obtained 98.2 and 90.4 in terms of sensitivity for Standard Diabetic Retinopathy Database - Calibration Level 1 (DIARETDB1) and a local dataset provided by National University Hospital of Malaysia (NUHM), respectively. © 2012 Elsevier Ltd. All rights reserved.

Mandeep J.S.,National University of Malaysia
Mapan - Journal of Metrology Society of India | Year: 2013

Attenuation due to rain plays an important part in satellite industries. These attenuation could be measured directly via satellite beacon at frequency 12.255 GHz (Ku-band). Therefore, measurements of 3 years signal attenuation due to rain data at Tronoh are presented. The measured data are compared with four prediction signal attenuation due to rain models such as Ramachandran Kumar, Garcia Lopez, International Telecommunication Union-Region and Goddard Thurai model. The Ramachandran Kumar model performed the best with the lowest percentage error below 10 % compared with the other two models. © 2013 Metrology Society of India.

Choudhury P.K.,National University of Malaysia
Advances in Materials Science and Engineering | Year: 2012

Using a fairly rigorous approach, gold-nanocoated dielectric optical fibers are treated to evaluate the propagation characteristics corresponding to the transverse electric (TE) and hybrid EH modes, as supported by the guides with small and large dimensions. Situations with varying nanocoating thickness are considered for two different operating wavelengths. The results demonstrate a profound effect of the gold nanocoating on the propagation-related features-the number of existing modes decreases with increasing nanolayer thickness. Furthermore, the gold nanolayer also has effects on the modal propagation constants, which become more prominent with the increase in the order of modes. It has been found that, in fiber with smaller dimension, the EH11 mode hardly exhibits any effect due to the variation in existing nanolayer coating corresponding to 850 nm wavelength. Almost similar situations are observed for the TE01 mode in large core fiber operating at 1550 nm wavelength. Copyright © 2012 P. K. Choudhury.

Jamaludin N.,University Putra Malaysia | Monsi M.,University Putra Malaysia | Hassan N.,National University of Malaysia | Suleiman M.,University Putra Malaysia
AIP Conference Proceedings | Year: 2013

The purpose of this paper is to establish a new modified method. This modified procedure is called the Interval Symmetric Single Step-5 Delta Procedure ISS-5δ. This research start with some disjoints intervals as the initial intervals which contain the polynomial zeros. The procedure of ISS-5δ will generate smaller bounded close intervals. The procedure is run on 5 test polynomials and the results obtained show that this procedure is more efficient than previous procedure. © 2013 AIP Publishing LLC.

Sarmani A.R.,University Putra Malaysia | Abu Bakar M.H.,University Putra Malaysia | Bakar A.A.A.,National University of Malaysia | Mahamd Adikan F.R.,University of Malaya | Mahdi M.A.,University Putra Malaysia
Optics Express | Year: 2011

We report an ultra-long Raman laser that implemented a variable pumping scheme in backward and forward configurations. Rayleigh backscattering effects were realized in the 51 km fiber length that functioned as a virtual mirror at one fiber end. With the employment of a fiber Bragg grating that has a peak reflection wavelength at 1553.3 nm, spectral broadening effects were observed. These occurred as the pump power level was diverted more to the forward direction. Owing to this fact, a maximum width of 0.9 nm was measured at 100% forward pumping. The obtained results show that the efficient exploitation of four-wave mixing interactions as well as strong Rayleigh backscattering are beneficial to influence the lasing performances. Both of these nonlinear responses can be adjusted by varying pumping distributions along the fiber longitudinal dimension. © 2011 Optical Society of America.

Cheah Y.K.,Northern University of Malaysia | Poh B.K.,National University of Malaysia
Osong Public Health and Research Perspectives | Year: 2014

Objectives: In light of the importance of physical activity, the aim of the present study is to examine the factors affecting participation in physical activity among adults in Malaysia. Methods: A logistic regression model and the Third National Health and Morbidity Survey consisting of 30,992 respondents were used. Results: Age, income, gender, education, marital status, region, house locality, job characteristics, and medical conditions are significantly associated with participation in physical activity. In particular, old individuals, high income earners, females, the well-educated, widowed or divorced individuals, East Malaysians, urban dwellers, the unemployed, and individuals who are not diagnosed with hypercholesterolemia are less likely to be physically active than others. Conclusion: Because sociodemographic and health factors play an important role in determining physical activity, the government should take them into account when formulating policy. © 2014.

Ahmed M.J.,National University of Malaysia | Ahmed M.J.,University of Baghdad | Theydan S.K.,University of Baghdad
Ecotoxicology and Environmental Safety | Year: 2012

Adsorption capacity of an agricultural waste, palm-tree fruit stones (date stones), for phenolic compounds such as phenol (Ph) and p-nitro phenol (PNPh) at different temperatures was investigated. The characteristics of such waste biomass were determined and found to have a surface area and iodine number of 495.71m2/g and 475.88mg/g, respectively. The effects of pH (2-12), adsorbent dose (0.6-0.8g/L) and contact time (0-150min) on the adsorptive removal process were studied. Maximum removal percentages of 89.95% and 92.11% were achieved for Ph and PNPh, respectively. Experimental equilibrium data for adsorption of both components were analyzed by the Langmuir, Freundlich and Tempkin isotherm models. The results show that the best fit was achieved with the Langmuir isotherm equation with maximum adsorption capacities of 132.37 and 161.44mg/g for Ph and PNPh, respectively. The kinetic data were fitted to pseudo-first order, pseudo-second order and intraparticle diffusion models, and was found to follow closely the pseudo-second order model for both components. The calculated thermodynamic parameters, namely ΔG, ΔH, and ΔS showed that adsorption of Ph and PNPh was spontaneous and endothermic under examined conditions. © 2012 Elsevier Inc.

Said F.F.,National University of Malaysia
Computational Economics | Year: 2016

This article is particularly concentrated on measuring systemic risk based on network topology of bilateral exposures and obligations specifically for the sectoral level of global banking systems in 2010. Financial network models based on financial exposures are models that aim to depict causal chains of exposures and obligations of counterparties rather than rely solely on statistical correlations on market price-based data for financial institutions. Our starting point is the bilateral claims of the ultimate risk of the main institutional sectors that include banks, non-bank private sectors and non-allocated sectors of the 10 reporting countries that consist of Belgium, France, Germany, Italy, Japan, Spain, Switzerland, Turkey, the United Kingdom and the United States of America. The other non-reporting countries will be merged into one group. The results show that banking systems in countries such as the United States and the United Kingdom in particular are making vast amounts of foreign investments, implying that they constitute a central hub in the core. The results in the contagion effect show that all of the other countries are collapsed after a shock from a core country such as the United Kingdom in both rates of loss given defaults of 100 and 60 %. © 2016 Springer Science+Business Media New York

Yau Y.H.,University of Malaya | Hasbi S.,National University of Malaysia
Renewable and Sustainable Energy Reviews | Year: 2013

Climate observations in recent years indicate that the effects of climate change events are apparently having an increasing impact on society. These impacts will likely also affect the building sector. Numerous studies have been conducted to assess future building energy consumption rates. However, these studies often do not take into account climatic variability and consumer reactions towards a temperature shift. A literature review on climate change impacts for commercial buildings and their technical services in the tropics was carried out. This review focuses on the buildings' contributions towards climate change as well as climate change impacts on building structures, changing patterns of energy use and peak demands, building heating and cooling requirements, thermal comfort and emissions impacts. In general, buildings in regions with a predicted increase in temperature will need more cooling and less heating loads. Thus, building energy consumption and carbon emissions are projected to rise during its operational phase. In addition, the erratic weather trends will also affect the building efficiency and sustainability, indoor air quality and thermal comfort. Even though the existing literature on this issue has increased substantially in recent years, there is still a need for further research in tropical climates as the climate change impacts vary with the different seasons, periods and regions. © 2012 Elsevier Ltd. All rights reserved.

Sabarudin A.,National University of Malaysia
Radiation protection dosimetry | Year: 2013

This study was conducted to investigate the effectiveness of dose-saving protocols in dual-source computed tomography (CT) coronary angiography compared with invasive coronary angiography (ICA). On 50 patients who underwent coronary CT angiography was performed dual-source CT (DSCT) and compared with ICA procedures. Entrance skin dose (ESD), which was measured at the thyroid gland, and effective dose (E) were assessed for both imaging modalities. The mean ESD measured at the thyroid gland was the highest at 120 kVp, followed by the 100 kVp DSCT and the ICA protocols with 4.0±1.8, 2.7±1.0 and 1.1±1.2 mGy, respectively. The mean E was estimated to be 10.3±2.1, 6.2±2.3 and 5.3±3.4 mSv corresponding to the 120-kVp, 100-kVp DSCT and ICA protocols, respectively. The application of 100 kVp in DSCT coronary angiography is feasible only in patients with a low body mass index of <25 kg m(-2), which leads to a significant dose reduction with the radiation dose being equivalent to that of ICA.

Jamshidian M.,Isfahan University of Technology | Thamburaja P.,National University of Malaysia | Rabczuk T.,Bauhaus University Weimar
Physical Chemistry Chemical Physics | Year: 2015

We propose a continuum-based state variable theory to quantify the excess surface free energy density throughout a nanostructure. The size-dependent effect exhibited by nanoplates and spherical nanoparticles i.e. the reduction of surface energy with reducing nanostructure size is well-captured by our continuum state variable theory. Our constitutive theory is also able to predict the reducing energetic difference between the surface and interior (bulk) portions of a nanostructure with decreasing nanostructure size. This journal is © the Owner Societies 2015.

Kumar S.,National University of Malaysia
BMC Research Notes | Year: 2015

Background: Cytochrome P450s (CYPs) are important heme-containing proteins, well known for their monooxygenase reaction. The human cytochrome P450 4X1 (CYP4X1) is categorized as "orphan" CYP because of its unknown function. In recent studies it is found that this enzyme is expressed in neurovascular functions of the brain. Also, various studies have found the expression and activity of orphan human cytochrome P450 4X1 in cancer. It is found to be a potential drug target for cancer therapy. However, three-dimensional structure, the active site topology and substrate specificity of CYP4X1 remain unclear. Methods: In the present study, the three-dimensional structure of orphan human cytochrome P450 4X1 was generated by homology modeling using Modeller 9v8. The generated structure was accessed for geometrical errors and energy stability using PROCHECK, VERFIY 3D and PROSA. A molecular docking analysis was carried out against substrates arachidonic acid and anandamide and the docked substrates were predicted for drug-likeness, ADME-Tox parameters and biological spectrum activity. Results: The three-dimensional model of orphan human cytochrome P450 4X1 was generated and assessed with various structural validation programmes. Docking of orphan human cytochrome P450 4X1 with arachidonic acid revealed that TYR 112, ALA 126, ILE 222, ILE 223, THR 312, LEU 315, ALA 316, ASP 319, THR 320, PHE 491 and ILE 492 residues were actively participating in the interaction, while docking of CYP4X1 with anandamide showed that TYR 112, GLN 114, PRO 118, ALA 126, ILE 222, ILE 223, SER 251, LEU 315, ALA 316 and PHE 491 key residues were involved in strong interaction. Conclusion: From this study, several key residues were identified to be responsible for the binding of arachidonic acid and anandamide with orphan human cytochrome P450 4X1. Both substrates obeyed Lipinski rule of five in drug-likeness test and biological spectrum prediction showed anticarcinogenic activity. Compared to anandamide, arachidonic acid showed strong interaction with cytochrome P450 4X1 and also less health effect in certain human system in ADME-Tox prediction. These findings provide useful information on the biological role and structure-based drug design of orphan human cytochrome P450 4X1. © 2015 Kumar; licensee BioMed Central.

Singh D.K.A.,National University of Malaysia | Bailey M.,University of Brighton | Lee R.,Roehampton University
Muscle and Nerve | Year: 2011

Introduction: Loss of lumbar extensor muscle strength and fatigue resistance may contribute to functional disability. Methods: Two groups of subjects were recruited: young (n = 26, 20-35 years of age) and old (n = 26, ≥65 years of age) adults. Lumbar extensor muscle strength was measured with a load cell, and electromyographic activities were recorded to study muscle fatigue at 60% of maximum voluntary contraction. Results: We found that the muscle moments generated by the extensor muscles decreased with age (P < 0.05). Aging was associated with a significant increase in the power of the lower frequency band (101-200 Hz) of the electromyographic signals (P < 0.05), but the spectral characteristics did not appear to change with sustained contraction (P > 0.05). Conclusions: The changes in strength and spectral properties of the electromyographic signals of lumbar extensor muscles may be related to age-related alterations in muscle fiber composition and recruitment. These changes should be considered in clinical functional task evaluation. © 2011 Wiley Periodicals, Inc.

Ibrahim A.M.A.,University Technology of MARA | Choudhury P.K.,National University of Malaysia
IEEE Photonics Journal | Year: 2013

This paper deals with the conceptualization of Maxwell-Duffing theory to model photonic deflection sensor along with functionality, which is based on the phenomena of optical bi-and multistabilities. The sensing system is considered to be consisting of Kerr nonlinear material along with suitably positioned mirrors. The efficacy of the approach is emphasized through a series of numerical simulations, and the reliability of the system is discussed. Effects due to system memory and periodicity in the optical bistability threshold have been demonstrated. It has been found that the approach provides a powerful tool to study optical bistability in resonating structures, particularly for materials with large third-order nonlinearity and for operating frequencies near the natural resonance of the material. © 2013 IEEE.

Yusop R.M.,University of Edinburgh | Yusop R.M.,National University of Malaysia | Unciti-Broceta A.,University of Edinburgh | Johansson E.M.V.,University of Edinburgh | And 2 more authors.
Nature Chemistry | Year: 2011

Many important intracellular biochemical reactions are modulated by transition metals, typically in the form of metalloproteins. The ability to carry out selective transformations inside a cell would allow researchers to manipulate or interrogate innumerable biological processes. Here, we show that palladium nanoparticles trapped within polystyrene microspheres can enter cells and mediate a variety of Pd0-catalysed reactions, such as allylcarbamate cleavage and Suzuki-Miyaura cross-coupling. The work provides the basis for the customization of heterogeneous unnatural catalysts as tools to carry out artificial chemistries within cells. Such in cellulo synthesis has potential for a plethora of applications ranging from cellular labelling to synthesis of modulators or inhibitors of cell function. © 2011 Macmillan Publishers Limited. All rights reserved.

Bhadauria B.S.,Babasaheb Bhimrao Ambedkar University | Hashim I.,National University of Malaysia | Siddheshwar P.G.,Bangalore University
Transport in Porous Media | Year: 2013

In this article we study the combined effect of internal heating and time-periodic gravity modulation on thermal instability in a closely packed anisotropic porous medium, heated from below and cooled from above. The time-periodic gravity modulation, considered in this problem can be realized by vertically oscillating the porous medium. A weak non-linear stability analysis has been performed by using power series expansion in terms of the amplitude of gravity modulation, which is assumed to be small. The Nusselt number has been obtained in terms of the amplitude of convection which is governed by the non-autonomous Ginzburg-Landau equation derived for the stationary mode of convection. The effects of various parameters such as; internal Rayleigh number, amplitude and frequency of gravity modulation, thermo-mechanical anisotropies, and Vadász number on heat transport has been analyzed. It is found that the response of the convective system to the internal Rayleigh number is destabilizing. Further it is found that the heat transport can also be controlled by suitably adjusting the external parameters of the system. © 2012 Springer Science+Business Media B.V.

Ong L.C.,National University of Malaysia
Developmental neurorehabilitation | Year: 2011

To compare parenting stress between mothers of children with spina bifida (SB) and able bodied controls. Sixty-six mothers of children with SB and controls (matched for age, sex and ethnicity) completed the Parenting Stress Index Short Form (PSI/SF) and General Health Questionnaire-12 (GHQ-12). Each child's adaptive skills was assessed using the Vineland Adaptive Behaviour Scales (VABS). Mothers of children with SB had significantly higher scores for GHQ-12 and the Parental Distress (PD), Parent-Child Dysfunctional Interaction (P-CDI) and Difficult Child (DC) sub-scales of the PSI/SF, even after adjusting for socioeconomic and caregiver status. Single parent status, having a child with SB and higher Life Stress scores were associated with higher PD and DC scores. Lower VABS scores were associated with higher P-CDI scores. Factors such as recent life change events, single parent status and the child's adaptive skills modify the impact of spina bifida on parenting stress.

Khatib T.,Sohar University | Sopian K.,National University of Malaysia | Kazem H.A.,Sohar University
Energy Conversion and Management | Year: 2013

This paper presents a field operation experience for a grid connected PV system under tropical climate. The system is consisted of a 5 kWp photovoltaic (PV) array and a 6 kW DC/AC inverter. The operation performance data are recorded in order to develop accurate mathematical models for the system as well as to evaluate the productivity of the system. The experiment results show that, the average PV performance (the ratio of the theoretical performance to the actual performance) is 73.12% while the average inverter performance (the ratio of the theoretical inverter efficiency to the actual inverter efficiency) is 98.56%. Moreover, it is found that the daily yield factor of the PV system is 2.51 kW h/kWp day while, the capacity factor is 10.47%. However, it is concluded that the productivity of the system is below the prospected rate and thus, an inspection of the system must be done in order to diagnose the problem of the system's low productivity. This paper presents worthwhile information for those who are interested in PV system installation in Malaysia and nearby country.

Aziz A.F.A.,University of Technology Malaysia | Khalid S.N.,University of Technology Malaysia | Mustafa M.W.,University of Technology Malaysia | Shareef H.,National University of Malaysia | Aliyu G.,University of Technology Malaysia
Renewable and Sustainable Energy Reviews | Year: 2013

Smart meter is an advanced energy meter that measures energy consumption in residential, commercial and industrial facilities with additional information related to the power system. This paper aims to review system functions of the latest smart meter technology which incorporates Advanced Metering Infrastructure (AMI). The paper also proposes future smart meter with some modification and improvement of AMI technology by introducing Artificial Intelligence Metering (AIM) techniques where the energy consumed by consumers' appliances is fully supervised by AIM. The AIM function is almost the same as AMI technology, but with some enhancement including schedule of various appliance usage by customers, PV integration and power quality monitoring. These modifications can facilitate consumers to manage their energy usage wisely, meanwhile promoting green technology to the community. © 2013 Elsevier Ltd.

Abas A.,National University of Malaysia
Biologicals | Year: 2011

The biosimilars sector continues to attract huge interest and controversy. Biosimilars are new biopharmaceuticals that are " similar" but not identical to the innovator product. Characteristics of biopharmaceuticals are closely related to the manufacturing process, which implies that the products cannot be exactly duplicated. Minuscule differences in the product's structure and manufacturing process can result in different clinical outcome. This raises concerns over the safety, efficacy and even pharmacovigilance of biosimilars. Thus, biosimilars are unique - they are not a true chemical generic and are regulated via a distinct regulatory framework. This report discusses the features of Malaysian regulatory oversight of biosimilars and experience acquired in the evaluation of some products from various countries. Ensuring regulatory position adequately reflects scientific advancement, expertise/resources is key. The regulatory situation is an evolving process. Various guidance documents are being prepared with the aim of developing a uniform global framework towards assuring the dual goal of lower costs and patient safety while expediting the availability of important biosimilar products. © 2011.

Leong K.Y.,University of Malaya | Leong K.Y.,National University of Malaysia | Saidur R.,University of Malaya | Kazi S.N.,University of Malaya | Mamun A.H.,Bangladesh University of Engineering and Technology
Applied Thermal Engineering | Year: 2010

Water and ethylene glycol as conventional coolants have been widely used in an automotive car radiator for many years. These heat transfer fluids offer low thermal conductivity. With the advancement of nanotechnology, the new generation of heat transfer fluids called, "nanofluids" have been developed and researchers found that these fluids offer higher thermal conductivity compared to that of conventional coolants. This study focused on the application of ethylene glycol based copper nanofluids in an automotive cooling system. Relevant input data, nanofluid properties and empirical correlations were obtained from literatures to investigate the heat transfer enhancement of an automotive car radiator operated with nanofluid-based coolants. It was observed that, overall heat transfer coefficient and heat transfer rate in engine cooling system increased with the usage of nanofluids (with ethylene glycol the basefluid) compared to ethylene glycol (i.e. basefluid) alone. It is observed that, about 3.8% of heat transfer enhancement could be achieved with the addition of 2% copper particles in a basefluid at the Reynolds number of 6000 and 5000 for air and coolant respectively. In addition, the reduction of air frontal area was estimated. © 2010 Elsevier Ltd. All rights reserved.

Sulong A.B.,National University of Malaysia | Park J.,Sejong University
Journal of Composite Materials | Year: 2011

This article discusses the effect of shear rates on the alignment of Multi-walled Carbon Nanotubes (MWCNTs) in a polyethylene (PE) matrix. Shear forces were applied with a self-constructed controllable shear extrusion system, and the degree of orientation of the MWCNTs was analyzed through image analysis of the microtome sectioned surfaces. Partially aligned MWCNTs in a PE matrix are successful fabricated in this study. It was found that the degree of alignment was increased by increasing shear rates, and an optimal shear rate was discovered. Tensile test results indicate that the mechanical properties of composites increase with an increasing degree of CNTs alignment. A partially aligned MWCNTs PE composite exhibited greater mechanical properties than randomly oriented MWCNTs. Differential scanning calorimetry analysis revealed that MWCNTs alignment by shear flow extrusion played a major role in mechanical property enhancement as compared to the crystallization effect of the polymer. © 2010 The Author(s).

Zulkifley M.A.,National University of Malaysia | Moran B.,University of Melbourne
Expert Systems with Applications | Year: 2012

Multiple object tracking is a fundamental subsystem of many higher level applications such as traffic monitoring, people counting, robotic vision and many more. This paper explains in details the methodology of building a robust hierarchical multiple hypothesis tracker for tracking multiple objects in the videos. The main novelties of our approach are anchor-based track initialization, prediction assistance for unconfirmed track and two virtual measurements for confirmed track. The system is built mainly to deal with the problems of merge, split, fragments and occlusion. The system is divided into two levels where the first level obtains the measurement input from foreground segmentation and clustered optical flow. Only K-best hypothesis and one-to-one association are considered. Two more virtual measurements are constructed to help track retention rate for the second level, which are based on predicted state and division of occluded foreground segments. Track based K-best hypothesis with multiple associations are considered for more comprehensive observation assignment. Histogram intersection testing is performed to limit the tracker bounding box expansion. Simulation results show that all our algorithms perform well in the surroundings mentioned above. Two performance metrics are used; multiple-object tracking accuracy (MOTA) and multiple-object tracking precision (MOTP). Our tracker have performed the best compared to the benchmark trackers in both performance evaluation metrics. The main weakness of our algorithms is the heavy processing requirement. © 2012 Elsevier Ltd. All rights reserved.

Ali E.S.,Universiti Sains Islam Malaysia | Ahmad S.,National University of Malaysia
Composites Part B: Engineering | Year: 2012

Bionanocomposite hybrid polyurethane (BHPU) foams that exploit the tribute of natural fibers and nanoclay in green PU foam can lead to the new imminent in engaging the nanoclay and natural fibers. PU filled empty fruit bunch (EFB), PU filled silane treated EFB (sEFB) and PU filled organo montmorillonite (oMMT) have been prepared as control, and the hybridization has carried out for , and ratios between EFB/oMMT and sEFB/oMMT. The hybridization of these natural fibers and oMMT permit to retain the strength without compromise the stiffness of BHPU. The hybridization also improves the barrier and thermal properties of these BHPU. Microscopic studies shows that the hybridization of these natural fibers and nanoclay provide initial evidence of the possibilities on the insertion of nanoclay into the natural fibers, thus open the opportunities to exploit this behavior to another hybrid system. © 2012 Elsevier Ltd. All rights reserved.

Reis A.,Aston University | Rudnitskaya A.,University of Aveiro | Blackburn G.J.,University of Strathclyde | Fauzi N.M.,National University of Malaysia | And 2 more authors.
Journal of Lipid Research | Year: 2013

Lipidome profile of fluids and tissues is a growing field as the role of lipids as signaling molecules is increasingly understood, relying on an effective and representative extraction of the lipids present. A number of solvent systems suitable for lipid extraction are commonly in use, though no comprehensive investigation of their effectiveness across multiple lipid classes has been carried out. To address this, human LDL from normolipidemic volunteers was used to evaluate five different solvent extraction protocols [Folch, Bligh and Dyer, acidified Bligh and Dyer, methanol (MeOH)-tert-butyl methyl ether (TBME), and hexane-isopropanol] and the extracted lipids were analyzed by LC-MS in a high-resolution instrument equipped with polarity switching. Overall, more than 350 different lipid species from 19 lipid subclasses were identified. Solvent composition had a small effect on the extraction of predominant lipid classes (triacylglycerides, cholesterol esters, and phosphatidylcholines). In contrast, extraction of less abundant lipids (phosphatidylinositols, lyso-lipids, ceramides, and cholesterol sulfates) was greatly influenced by the solvent system used. Overall, the Folch method was most effective for the extraction of a broad range of lipid classes in LDL, although the hexane-isopropanol method was best for apolar lipids and the MeOH-TBME method was suitable for lactosyl ceramides. Copyright © 2013 by the American Society for Biochemistry and Molecular Biology, Inc.

Lurie S.,RAS Institute of Applied Mechanics | Minhat M.,National University of Malaysia
Composites Part B: Engineering | Year: 2014

A self-consistent Eshelby method based on the three-phase model is developed to examine the behavior of bristled fiber composite material where the fibers are radially coated with micro/nanostructures such as microwhiskers, nanowires or carbon nanotubes (fuzzy fiber). The effective mechanical properties are determined by taking into account the additional bristled interphase layer that is formed between fiber and matrix due to the presence of these micro/nanofibers. The features of the proposed method are emphasized and comparative study with other methods is conducted. In addition, several parameters of the micro/nanofibers such as length, density, diameter and material affecting the effective properties of composites are examined. In general, the presence of bristled fibers can significantly improve the shear and transverse characteristics of composite materials. © 2014 Elsevier Ltd. All rights reserved.

Al-Sawalha M.M.,Hail University | Noorani M.S.M.,National University of Malaysia
Chinese Physics Letters | Year: 2011

We elaborate the concept of increasing-order synchronization and anti-synchronization of chaotic systems via an adaptive control scheme and modulation parameters. It is shown that the dynamical evolution of a third-order chaotic system can be synchronized and anti-synchronized with a fourth-order chaotic system even though their parameters are unknown. Theoretical analysis and numerical simulations are carried out to verify the results. © 2011 Chinese Physical Society and IOP Publishing Ltd.

Previous studies in systemic lupus erythematosus (SLE) patients have produced conflicting results regarding the diagnostic utility of procalcitonin (PCT). The aim of this study was to determine predictive values of PCT and C-reactive protein (CRP) for bacterial infection in SLE patients. This was a cross-sectional study of clinic and hospitalized SLE patients with and without bacterial infection recruited over 18 months. Bacterial infection was defined as positive culture results. SLE disease activity was measured using SLEDAI. PCT and CRP were measured by automated immunoassays. Sixty-eight patients (57 females) were studied. Ten patients (15%) had infection. The areas under the receiver operating characteristic curves for PCT and CRP were not significantly different [0.797 (CI 0.614-0.979) versus 0.755 (CI 0.600-0.910)]. In lupus flare patients, PCT but not CRP was higher with infection (p = 0.019 versus 0.195). A PCT of <0.17 ng/ml ruled out infection with 94% negative predictive value (NPV). In remission patients, CRP but not PCT was elevated with infection (p = 0.036 versus 0.103). CRP < 0.57 mg/dl had 96% NPV. PCT may be a better marker to rule out bacterial infection in lupus flare but not in remission or general screening.

Ahmed M.J.,National University of Malaysia | Ahmed M.J.,University of Baghdad | Theydan S.K.,University of Baghdad
Journal of Analytical and Applied Pyrolysis | Year: 2013

Agricultural wastes, Albizia lebbeck seed pods, have been utilized as precursors for production of a microporous activated carbon using one step microwave assisted K2CO3 activation. The sorption performance of prepared carbon for p-chlorophenol (PCPh) was investigated by batch adsorption technique. Effects of radiation time, radiation power, and impregnation ratio on the sorption performance were studied to determine the best preparation conditions. Carbon with 26.2% yield and 247.9 mg/g PCPh uptake has been obtained at conditions of 8 min radiation time, 540 W radiation power and 1.5 g/g impregnation ratio. The surface area, micropore volume, and mesopore volume of prepared carbon at best conditions were 1676.6 m2/g, 0.527 cm3/g, and 0.181 cm3/g, respectively. The best fitting for PCPh equilibrium isotherm data was achieved by the three-parameter Sips isotherm with a maximum adsorption capacity of 300.6 mg/g. The experimental kinetic data were well represented by the pseudo-second order model. © 2013 Elsevier B.V.

Su Y.-F.,National Science and Technology Center for Disaster Reduction | Foody G.M.,University of Nottingham | Muad A.M.,National University of Malaysia | Cheng K.-S.,National Taiwan University
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing | Year: 2012

The mixed pixel problem may be reduced through the use of a soft image classification and super-resolution mapping analyses. Here, the positive attributes of two popular super-resolution mapping methods, based on contouring and the Hopfield neural network, are combined. For a binary classification scenario, the method is based on fitting a contour of equal class membership to a pre-final output of a standard Hopfield neural network. Analyses of simulated and real image data sets show that the proposed method is more accurate than the standard contouring and Hopfield neural network based methods, with error typically reduced by a factor of two or more. The sensitivity of the Hopfield neural network based approaches to the setting of a gain function is also explored. © 2008-2012 IEEE.

Dominick D.,University Putra Malaysia | Juahir H.,University Putra Malaysia | Latif M.T.,National University of Malaysia | Zain S.M.,University of Malaya | Aris A.Z.,University Putra Malaysia
Atmospheric Environment | Year: 2012

This study aims to investigate possible sources of air pollutants and the spatial patterns within the eight selected Malaysian air monitoring stations based on a two-year database (2008-2009). The multivariate analysis was applied on the dataset. It incorporated Hierarchical Agglomerative Cluster Analysis (HACA) to access the spatial patterns, Principal Component Analysis (PCA) to determine the major sources of the air pollution and Multiple Linear Regression (MLR) to assess the percentage contribution of each air pollutant. The HACA results grouped the eight monitoring stations into three different clusters, based on the characteristics of the air pollutants and meteorological parameters. The PCA analysis showed that the major sources of air pollution were emissions from motor vehicles, aircraft, industries and areas of high population density. The MLR analysis demonstrated that the main pollutant contributing to variability in the Air Pollutant Index (API) at all stations was particulate matter with a diameter of less than 10 μm (PM 10). Further MLR analysis showed that the main air pollutant influencing the high concentration of PM 10 was carbon monoxide (CO). This was due to combustion processes, particularly originating from motor vehicles. Meteorological factors such as ambient temperature, wind speed and humidity were also noted to influence the concentration of PM 10. © 2012 Elsevier Ltd.

Su Y.-F.,National Science and Technology Center for Disaster Reduction | Foody G.M.,University of Nottingham | Muad A.M.,National University of Malaysia | Cheng K.-S.,National Taiwan University
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing | Year: 2012

Combining super-resolution techniques can increase the accuracy with which the shape of objects may be characterised from imagery. This is illustrated with two approaches to combining the contouring and pixel swapping methods of super-resolution mapping for binary classification applications. In both approaches, the output of the pixel swapping method is softened to allow a contour of equal class membership to be fitted to it to represent the inter-class boundary. The accuracy of super-resolution mapping with the individual and combined techniques is explored, including an assessment of the effect of variation in the number of neighbors and zoom factor on pixel swapping based analyses. When combined, the error with which objects of varying shape were represented was typically greatly reduced relative to that observed from the application of the methods individually. For example, the root mean square error in mapping the boundary of an aeroplane represented in relatively fine spatial resolution imagery decreased from 14.41 m with contouring and 4.35 m with pixel swapping to 3.07 m when the approaches were combined. © 2008-2012 IEEE.

Bachok N.,University Putra Malaysia | Ishak A.,National University of Malaysia | Pop I.,Babes - Bolyai University
PLoS ONE | Year: 2013

The steady boundary layer flow of a viscous and incompressible fluid over a moving vertical flat plate in an external moving fluid with viscous dissipation is theoretically investigated. Using appropriate similarity variables, the governing system of partial differential equations is transformed into a system of ordinary (similarity) differential equations, which is then solved numerically using a Maple software. Results for the skin friction or shear stress coefficient, local Nusselt number, velocity and temperature profiles are presented for different values of the governing parameters. It is found that the set of the similarity equations has unique solutions, dual solutions or no solutions, depending on the values of the mixed convection parameter, the velocity ratio parameter and the Eckert number. The Eckert number significantly affects the surface shear stress as well as the heat transfer rate at the surface. © 2013 Bachok et al.

Hatamlou A.,Islamic Azad University at Khoy | Hatamlou A.,National University of Malaysia
Pattern Recognition Letters | Year: 2012

Data clustering is an important technique in data mining. It is a method of partitioning data into clusters, in which each cluster must have data of great similarity and different clusters must have data of high dissimilarity. A lot of clustering algorithms are found in the literature. In general, there is no single algorithm that is suitable for all types of data, conditions and applications. Each algorithm has its own advantages, limitations and shortcomings. Therefore, introducing novel and effective approaches for data clustering is an open and active research area. This paper presents a novel binary search algorithm for data clustering that not only finds high quality clusters but also converges to the same solution in different runs. In the proposed algorithm a set of initial centroids are chosen from different parts of the test dataset and then optimal locations for the centroids are found by thoroughly exploring around of the initial centroids. The simulation results using six benchmark datasets from the UCI Machine Learning Repository indicate that proposed algorithm can efficiently be used for data clustering. © 2012 Elsevier B.V. All rights reserved.

Budiman P.M.,University of Selangor | Wu T.Y.,University of Selangor | Ramanan R.N.,University of Selangor | Md. Jahim J.,National University of Malaysia
Energy and Fuels | Year: 2015

Rhodobacter sphaeroides NCIMB8253 and palm oil mill effluent (POME) were applied as the purple nonsulfur bacteria and substrate, respectively, to produce biohydrogen in the photofermentation process. Due to the dark color of POME, pulp and paper mill effluent (PPME) was used as a diluting agent to reduce the turbidity of substrate and, thus, improve light penetration. Anaerobic batch experiments were performed by varying the concentration of POME from 12.5% to 100% (v/v) with 10% (v/v) inoculum in a total of 100 mL of substrate. The highest biohydrogen yield of 4.670 mL H2/mL medium was obtained using NS4 treatment containing 25% and 75% (v/v) of POME and PPME, respectively. A maximum production rate of 0.496 mL H2/mL medium·h and light efficiency of 2.40% were also achieved in NS4. Furthermore, a simultaneous 28.8% of total chemical oxygen demand (CODtotal) removal was obtained after 3 days of photofermentation. An additional increase of POME concentration (>25%, v/v) did not support higher production of biohydrogen due to the increase of turbidity (>16 450 NTU) which resulted in a hindrance of light penetration. This study showed the potential of reusing and combining two different effluents together, in which case one had lower turbidity than the other wastewater, for improving light penetration and, thus, photobiohydrogen production. © 2015 American Chemical Society.

Wahid S.F.A.,National University of Malaysia
International Journal of Hematology | Year: 2013

Hematopoietic stem cell transplantation (HCT) utilizing non-myeloablative (NMA) and reduced-intensity conditioning (RIC) regimens (collectively referred to as reduced-toxicity HCT, RT-HCT) has become a viable therapeutic option for patients with hematological malignancies who are ineligible for standard myeloablative conditioning transplantation (MA-HCT). RT-HCT has been shown to induce stable engraftment with low toxicity, and to produce similar overall and progression-free survival (PFS) when compared to MA-HCT in acute myeloid leukemia and myelodysplastic syndrome. The best results for RT-HCT have been reported for patients with disease that is in remission, indolent and chemosensitive, and with a strong graft-versus-malignancy effect. Chronic graft-versus-host disease seems to correlate with a lower relapse rate and better PFS. RT-HCT is inferior when performed in poor risk or advanced disease, due to high relapse rates. A search for novel strategies that includes the most appropriate conditioning regimens and post-transplant immunomodulation protocols with more intensive anti-malignancy activity but limited toxicity is in progress. This review provides an update on the results of clinical studies of RT-HCT, and discusses possible indications and investigative strategies for improving the clinical outcomes of RT-HCT for the major hematological malignancies. © 2013 The Japanese Society of Hematology.

Azmi F.,University of Queensland | Azmi F.,National University of Malaysia | Fuaad A.A.H.A.,University of Queensland | Skwarczynski M.,University of Queensland | Toth I.,University of Queensland
Human Vaccines and Immunotherapeutics | Year: 2014

Peptide-based subunit vaccines are of great interest in modern immunotherapy as they are safe, easy to produce and well defined. However, peptide antigens produce a relatively weak immune response, and thus require the use of immunostimulants (adjuvants) for optimal efficacy. Developing a safe and effective adjuvant remains a challenge for peptide-based vaccine design. Recent advances in immunology have allowed researchers to have a better understanding of the immunological implication of related diseases, which facilitates more rational design of adjuvant systems. Understanding the molecular structure of the adjuvants allows the establishment of their structure-activity relationships which is useful for the development of next-generation adjuvants. This review summarizes the current state of adjuvants development in the field of synthetic peptide-based vaccines. The structural, chemical and biological properties of adjuvants associated with their immunomodulatory effects are discussed. © 2014 Landes Bioscience.

Goh H.-H.,University of Sheffield | Sloan J.,National University of Malaysia | Dorca-Fornell C.,University of Sheffield | Fleming A.,University of Sheffield
Plant Physiology | Year: 2012

Expansins are cell wall proteins implicated in the control of plant growth via loosening of the extracellular matrix. They are encoded by a large gene family, and data linked to loss of single gene function to support a role of expansins in leaf growth remain limited. Here, we provide a quantitative growth analysis of transgenics containing an inducible artificial microRNA construct designed to down-regulate the expression of a number of expansin genes that an expression analysis indicated are expressed during the development of Arabidopsis (Arabidopsis thaliana) leaf 6. The results support the hypothesis that expansins are required for leaf growth and show that decreased expansin gene expression leads to a more marked repression of growth during the later stage of leaf development. In addition, a histological analysis of leaves in which expansin gene expression was suppressed indicates that, despite smaller leaves, mean cell size was increased. These data provide functional evidence for a role of expansins in leaf growth, indicate the importance of tissue/organ developmental context for the outcome of altered expansin gene expression, and highlight the separation of the outcome of expansin gene expression at the cellular and organ levels. © 2012 American Society of Plant Biologists. All Rights Reserved.

Cheong J.Y.,National University of Malaysia
South African medical journal = Suid-Afrikaanse tydskrif vir geneeskunde | Year: 2012

The incidence of methicillin-resistant Staphylococcus aureus (MRSA) infections in intensive care units in Malaysia is significant. Invasive MRSA infections are commonly treated with vancomycin. In clinical practice, the serum vancomycin trough concentration is used as a surrogate marker of vancomycin efficacy. A low concentration of vancomycin may result in less effective therapy and increase the risk of bacterial resistance. We evaluated the relationship between the resolution of MRSA infections and trough concentrations of vancomycin. A total of 76 patients admitted between January 2005 and February 2011 were included in the study. Serum vancomycin trough concentration data were collected from the microbiology records. The clinical response was evaluated on the basis of clinical notes and culture test results. A total of 262 appropriate trough concentration data were included, with a median of 3 trough concentrations per patient. Fifty-four patients responded to vancomycin therapy. The initial trough concentration did not differ between responders and non-responders (p=0.135) but the corrected trough concentration was higher among responders than among non-responders (11.64±1.50 mg/l and 9.25±1.59 mg/l, respectively; p=0.036). The average total daily dose of vancomycin was significantly higher among the responders (p=0.008). In this critically ill population, a vancomycin dose of 15 mg/kg/day was found sufficient to produce optimal trough concentrations to eradicate the MRSA infection. This study demonstrated the significant relationship between response to treatment of MRSA infection and serum vancomycin trough concentrations.

El-Shafie A.,National University of Malaysia
Neural Computing and Applications | Year: 2014

The potential of utilizing artificial neural network (ANN) model approach for simulate and predict the hydrogen yield in batch model using Clostridium saccharoperbutylacetonicum N1-4 (ATCC 13564) was investigated. A unique architecture has been introduced in this research to mimic the inter-relationship between three input parameters initial substrate, initial medium pH and reaction temperature (37 °C, 6.0 ± 0.2, 10), respectively, to predict hydrogen yield. Sixty data records from the experiment have been utilized to develop the ANN model. The results showed that the proposed ANN model provided significant level of accuracy for prediction with maximum error (10 %). Furthermore, a comparative analysis with a traditional approach Box-Wilson design (BWD) has proved that the ANN model output significantly outperformed the BWD. ANN model overcomes the limitation of the BWD approach with respect to the number of records, which is merely considering limited length of stochastic pattern for hydrogen yield (15 records). © 2012 Springer-Verlag London.

Somalu M.R.,Imperial College London | Somalu M.R.,National University of Malaysia | Yufit V.,Imperial College London | Brandon N.P.,Imperial College London
International Journal of Hydrogen Energy | Year: 2013

Screen-printing is a commonly used technique to fabricate thick film solid oxide fuel cell (SOFC) electrodes, followed by drying and high temperature sintering, and this study focuses on the rheology of such screen-printing inks for SOFC anode fabrication, and in particular on the effect of solids content. Commercially available powders of NiO and scandia stabilized zirconia were used, with average particle sizes of 0.714 and 2.151 μm, respectively. The thixotropy and viscosity of inks increased with increasing solid content. The particle network strength, important to the production of films with good particle connectivity and mechanical strength, also increased as the solids content increased. The complex modulus, G*, (indicative of the overall elasticity and tackiness of the inks) ranged from 500 to 4000 Pa, a range found acceptable for screen-printing. The minimum and maximum acceptable solids content were determined to be 25 and 30 vol% respectively. Inks having solids content outside this range were too liquid like and tacky, respectively, for effective screen-printing. The percentage of ink recovery, indicative of the print quality of the resultant films, also increased with solid content. The relevant properties of the anode films, including mechanical strength, electronic conductivity and electrochemical performance, all improved with increasing solids content as a result of improved particle connectivity, consistent with the conclusions drawn from the rheological study. In summary, from the perspective of ink rheology, screen-printability and performance, inks having 28-30 vol% solids were determined as the most suitable for the production of high quality SOFC anode films with a thickness of around 10 μm. Copyright © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Singh D.K.A.,National University of Malaysia | Bailey M.,University of Brighton | Lee R.Y.W.,Roehampton University
Clinical Biomechanics | Year: 2011

Background: Ageing is associated with geometrical changes in muscle fascicles that may lead to deteriorations in physical functions. The purpose of this study was to study the effects of ageing on fibre orientation and strength of the lumbar extensor muscles. Methods: Fifty two healthy, 26 younger (10 males and 16 females, aged from 20 to 35) and 26 older (10 males and 16 females, aged from 65 to 90) volunteers participated in this study. Ultrasound images of the lumbar extensor muscles were obtained with the participants in relaxed standing and half flexion (50% of the range of trunk flexion). The fibre angles at the mid-substance of the muscle were recorded. Lumbar extensor muscle strength was measured in the upright posture with a load cell. Findings: The mean lumbar extensor fibre angles were found to significantly decrease in the half flexion posture when compared to upright stance (P < 0.01). Both the fibre angle and the moment generation capability of the muscles decreased with ageing (P < 0.01). There was a moderate correlation between the fibre angles in the upright posture and the muscle strength measured in this posture (r = 0.40, P < 0.01). Interpretation: Age-related changes in muscle geometry and posture may partly account for the deterioration in muscle function in the elderly. © 2011 Elsevier Ltd. All rights reserved.

Jie Y.,National University of Malaysia
Reviews of environmental contamination and toxicology | Year: 2013

In this review, our aim was to examine the influence of geographic variations on asthma prevalence and morbidity among adults, which is important for improving our understanding, identifying the burden, and for developing and implementing interventions aimed at reducing asthma morbidity. Asthma is a complex inflammatory disease of multifactorial origin, and is influenced by both environmental and genetic factors. The disparities in asthma prevalence and morbidity among the world's geographic locations are more likely to be associated with environmental exposures than genetic differences. In writing this article, we found that the indoor factors most consistently associated with asthma and asthma-related symptoms in adults included fuel combustion, mold growth, and environmental tobacco smoke in both urban and rural areas. Asthma and asthma-related symptoms occurred more frequently in urban than in rural areas, and that difference correlated with environmental risk exposures, SES, and healthcare access. Environmental risk factors to which urban adults were more frequently exposed than rural adults were dust mites,high levels of vehicle emissions, and a westernized lifestyle.Exposure to indoor biological contaminants in the urban environment is common.The main risk factors for developing asthma in urban areas are atopy and allergy to house dust mites, followed by allergens from animal dander. House dust mite exposure may potentially explain differences in diagnosis of asthma prevalence and morbidity among adults in urban vs. rural areas. In addition, the prevalence of asthma morbidity increases with urbanization. High levels of vehicle emissions,Western lifestyles and degree of urbanization itself, may affect outdoor and thereby indoor air quality. In urban areas, biomass fuels have been widely replaced by cleaner energy sources at home, such as gas and electricity, but in most developing countries, coal is still a major source of fuel for cooking and heating, particularly in winter. Moreover, exposure to ETS is common at home or at work in urban areas.There is evidence that asthma prevalence and morbidity is less common in rural than in urban areas. The possible reasons are that rural residents are exposed early in life to stables and to farm milk production, and such exposures are protective against developing asthma morbidity. Even so, asthma morbidity is disproportionately high among poor inner-city residents and in rural populations. A higher proportion of adult residents of nonmetropolitan areas were characterized as follows:aged 55 years or older, no previous college admission, low household income, no health insurance coverage, and could not see a doctor due to healthcare service availability, etc. In rural areas, biomass fuels meet more than 70% of the rural energy needs. Progress in adopting modern energy sources in rural areas has been slow. The most direct health impact comes from household energy use among the poor, who depend almost entirely on burning biomass fuels in simple cooking devices that are placed in inadequately ventilated spaces. Prospective studies are needed to assess the long-term effects of biomass smoke on lung health among adults in rural areas.Geographic differences in asthma susceptibility exist around the world. The reason for the differences in asthma prevalence in rural and urban areas may be due to the fact that populations have different lifestyles and cultures, as well as different environmental exposures and different genetic backgrounds. Identifying geographic disparities in asthma hospitalizations is critical to implementing prevention strategies,reducing morbidity, and improving healthcare financing for clinical asthma treatment. Although evidence shows that differences in the prevalence of asthma do exist between urban and rural dwellers in many parts of the world, including in developed countries, data are inadequate to evaluate the extent to which different pollutant exposures contribute to asthma morbidity and severity of asthma between urban and rural areas.

Ahmad M.Z.,University Malaysia Perlis | Hasan M.K.,National University of Malaysia | De Baets B.,Ghent University
Information Sciences | Year: 2013

In this paper, we study analytical and numerical solutions of fuzzy differential equations based on the extension principle. For linear fuzzy differential equations, we state some results on the behaviour of the solutions and study their relationship with the generalised Hukuhara derivative. In order to approximate the solutions of linear and non-linear fuzzy differential equations, we propose a new fuzzification of the classical Euler method and then incorporate an unconstrained optimisation technique. This combination offers a powerful tool to tackle uncertainty in any numerical method. An efficient computational algorithm is also provided to guarantee the convexity of fuzzy solutions on the time domain. Several illustrative examples are given. © 2013 Elsevier Inc. All rights reserved.

Nayan N.A.,National University of Malaysia | Takahashi Y.,Gifu University | Sekine T.,Gifu University
Microelectronics Journal | Year: 2012

As the density and operating speed of complementary metal oxide semiconductor (CMOS) circuits increases, dynamic power dissipation has become a critical concern in the design and development - of personal information systems and large computers. The reduction of supply voltage, node capacitance, and switching activity are common approaches used in conventional CMOS. In adiabatic switching circuits, the current flow through transistors can be significantly reduced by ensuring uniform charge transfer over the entire available time. This paper presents the simulation of this current in two-phase clocked adiabatic static CMOS logic (2PASCL) and conventional CMOS. From the SPICE simulations, at transition frequencies from 1 to 12 MHz, a 4×4-bit array 2PASCL multiplier shows a maximum reduction in power dissipation of 77% relative to that of a static CMOS. The measurement results of a 4×4-bit array 2PASCL multiplier demonstrate a 57% reduction compared to a 4×4-bit array two-phase clocked adiabatic dynamic CMOS logic (2PADCL). These results indicate that 2PASCL technology can be advantageous when applied to low-power digital devices operated at low frequencies, such as radio-frequency identification (RFID) tags, smart cards, and sensors. © 2012 Elsevier Ltd. All rights reserved.

Moorthy R.,National University of Malaysia | eyabalan G.,Ministry of Science
American Journal of Applied Sciences | Year: 2012

Problem statement: This is a review paper that examines the extent aspects such as ethics, sustainability and the environment manifest in the water policy and water management in Malaysia. The study examines two aspects of this topic; firstly it examines the various objectives and considerations in the National Water Policy and secondly it discusses the issues that arise regarding water policy and management, especially with regard to federal-states jurisdiction issues, legislations in water management and the problems related to inter-agency coordination, especially among agencies involved in the management of rivers. Approach: A qualitative approach is employed in this study. It provides a comprehensive review of the stated problem based on document analysis and interviews with individuals involved in policy formulation and from agencies involved in water management. Results: The study reveals two major findings; the first shows that the National Water Policy provide a holistic approach in dealing with water-by providing safe, adequate and affordable water supply to people; providing sufficient water that will ensure national and food security and promote rural development; sufficient water to spur and sustain economic growth; and protection of the water environment to preserve water resources. Second, it examines issues regarding water management such as the jurisdiction between federal and state governments, legislations and enforcement and inefficiency in inter-agency coordination that hinder the realization of this policy's objectives. Conclusion: The study concludes that despite the holistic coverage of the national water policy, there are apparent problems with regard to the jurisdiction, legislation and coordination initiatives that have resulted in the poor management of water resources. The study postulates that, in addition to better coordination between water related agencies and more cohesive water legislations structure, it is fundamental to infuse the knowledge of 'water ethics' among water managers, institutions, the general public and into water policy formulation and implementation initiatives. © 2012 Science Publications.

Suhaila J.,University of Technology Malaysia | Jemain A.A.,National University of Malaysia
Theoretical and Applied Climatology | Year: 2012

This study presents the spatial analysis of daily rainfall intensity and concentration index over Peninsular Malaysia. Daily rainfall data from 50 rainfall stations are used in this study. Due to the limited number of stations, the geostatistical method of ordinary kriging is used to compute the values of daily rainfall concentration and intensity and to map their spatial distribution. The resultant analysis of rainfall concentration indicated that the distribution of daily rainfall is more regular over the west, northwest and southwest regions compared to the east. Large areas of the eastern Peninsula display an irregularity in distribution of daily rainfall. In terms of number of rainy days, analysis of daily rainfall confirms that a large number of rainy days across the Peninsula arise from low-intensity events but only contribute a small percentage of total rain. On the other hand, a low frequency of rainy days with high-intensity events contributes the largest percentage of total rain. The results indicated that the total rain in eastern areas is mainly contributed by the high-intensity events. This finding explains the occurrence of a large number of floods and soil erosions in these areas. Therefore, precautionary measures should be taken earlier to prevent any massive destruction of property and loss of life due to the hazards. These research findings are of considerable importance in providing enough information to water resource management, climatologists and agriculturists as well as hydrologists for planning their activities and modelling processes. © 2011 Springer-Verlag.

Abdul Karim R.,National University of Malaysia
Biomedical engineering online | Year: 2013

Telepointer is a powerful tool in the telemedicine system that enhances the effectiveness of long-distance communication. Telepointer has been tested in telemedicine, and has potential to a big influence in improving quality of health care, especially in the rural area. A telepointer system works by sending additional information in the form of gesture that can convey more accurate instruction or information. It leads to more effective communication, precise diagnosis, and better decision by means of discussion and consultation between the expert and the junior clinicians. However, there is no review paper yet on the state of the art of the telepointer in telemedicine. This paper is intended to give the readers an overview of recent advancement of telepointer technology as a support tool in telemedicine. There are four most popular modes of telepointer system, namely cursor, hand, laser and sketching pointer. The result shows that telepointer technology has a huge potential for wider acceptance in real life applications, there are needs for more improvement in the real time positioning accuracy. More results from actual test (real patient) need to be reported. We believe that by addressing these two issues, telepointer technology will be embraced widely by researchers and practitioners.

Hussain M.S.,University of Sydney | Mamun Md.,National University of Malaysia
Measurement Science Review | Year: 2012

Muscle fatigue is the decline in ability of a muscle to create force. Electromyography (EMG) is a medical technique for measuring muscle response to nervous stimulation. During a sustained muscle contraction, the power spectrum of the EMG shifts towards lower frequencies. These effects are due to muscle fatigue. Muscle fatigue is often a result of unhealthy work practice. In this research, the effectiveness of the wavelet transform applied to the surface EMG (SEMG) signal as a means of understanding muscle fatigue during walk is presented. Power spectrum and bispectrum analysis on the EMG signal getting from right rectus femoris muscle is executed utilizing various wavelet functions (WFs). It is possible to recognize muscle fatigue appreciably with the proper choice of the WF. The outcome proves that the most momentous changes in the EMG power spectrum are symbolized by WF Daubechies45. Moreover, this research has compared bispectrum properties to the other WFs. To determine muscle fatigue during gait, Daubechies45 is used in this research to analyze the SEMG signal.

Mousavi S.M.,University of Malaya | Hajipour V.,Islamic Azad University at Qazvin | Niaki S.T.A.,Sharif University of Technology | Aalikar N.,National University of Malaysia
International Journal of Advanced Manufacturing Technology | Year: 2014

In this paper, a seasonal multi-product multi-period inventory control problem is modeled in which the inventory costs are obtained under inflation and all-unit discount policy. Furthermore, the products are delivered in boxes of known number of items, and in case of shortage, a fraction of demand is considered backorder and a fraction lost sale. Besides, the total storage space and total available budget are limited. The objective is to find the optimal number of boxes of the products in different periods to minimize the total inventory cost (including ordering, holding, shortage, and purchasing costs). Since the integer nonlinear model of the problem is hard to solve using exact methods, a particle swarm optimization (PSO) algorithm is proposed to find a near-optimal solution. Since there is no bench mark available in the literature to justify and validate the results, a genetic algorithm is presented as well. In order to compare the performances of the two algorithms in terms of the fitness function and the required CPU time, they are first tuned using the Taguchi approach, in which a metric called "smaller is better" is used to model the response variable. Then, some numerical examples are provided to demonstrate the application and to validate the results obtained. The results show that, while both algorithms have statistically similar performances, PSO tends to be the better algorithm in almost all problems. © 2013 Springer-Verlag London.

Trihaminto H.H.,National University of Malaysia | Prabuwono A.S.,Gadjah Mada University
Advanced Science Letters | Year: 2014

Simultaneous Localization and Mapping (SLAM) for UAV is one of the abilities for establishing autonomous UAV. Many approaches have solved SLAM problem, but the problem on data association is yet to be solved. On one hand, high data ambiguous occurs from noise measurement and unknown data collection leads to failure hypothesis. On the other hand, computational complexity still becomes challenging research in SLAM. This paper deliveres a conceptual framework to solve data association problem with low computational complexity. The framework proposes dynamic path planning using L+Dumo algorithm to solve problem in SLAM. It is expected that the develop algorithm can solve data association problem with low computational complexity. © 2014 American Scientific Publishers All rights reserved.

Nabil S.,National University of Malaysia | Samman N.,University of Hong Kong
Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology | Year: 2012

Objective. This systematic review aimed to answer the clinical question, "What is the current risk of developing osteoradionecrosis of the jaws among irradiated head and neck cancer patients?" Study Design. A systematic review of published English-language randomized controlled trials on the outcome of radiation therapy was performed via Medline and Embase databases. Data on osteoradionecrosis/bone toxicity were collected and analyzed. Results. Twenty-two articles reporting on a total of 5,742 patients were selected for final review based on strict eligibility criteria. An estimated 2% of the head and neck-irradiated patients are at risk of developing osteoradionecrosis. Patients receiving adjunctive radiotherapy, accelerated fractionation without dose reduction, and chemoradiotherapy show no increase in osteoradionecrosis risk. Accelerated fractionation with dose reduction is associated with a reduced risk, whereas hyperfractionation shows elevated risk of developing osteoradionecrosis. Conclusions. The risk of developing osteoradionecrosis among the irradiated head and neck cancer patient has significantly declined in recent years. © 2012 Elsevier Inc. All rights reserved.

Hay J.X.W.,University of Selangor | Wu T.Y.,University of Selangor | Juan J.C.,University of Selangor | Md. Jahim J.,National University of Malaysia
Biofuels, Bioproducts and Biorefining | Year: 2013

Hydrogen has been introduced as a potential replacement for energy resource due to the depletion of fossil fuel and raising awareness about global climate change and health problems caused by the combustion of fossil fuel. One of the attractive options to produce hydrogen is through microbial fermentation which can be classified into biophotolysis, dark fermentation, photofermentation, and microbial electrolysis cell. Among these, dark fermentation and photofermentation technologies were processes that were being studied widely. One of the reasons is that organic waste could be reused as a substrate during biohydrogen production. Although the current biohydrogen yields are low, it is expected that with improvements technology and genetic engineering, the amount of generated biohydrogen could be enhanced tremendously, and provide a sustainable way of reutilizing waste as a substrate. Thus, this paper reviews the principles of photofermentation and dark fermentation by reusing various wastes as substrates. The resulting performances, limitations, as well as future prospects of hydrogen usage and hydrogen economy are also discussed. © 2013 Society of Chemical Industry and John Wiley & Sons, Ltd.

Ng S.-F.,University of New South Wales | Ng S.-F.,National University of Malaysia | Lin R.C.Y.,University of New South Wales | Maloney C.A.,University of New South Wales | And 3 more authors.
FASEB Journal | Year: 2014

We previously showed that paternal high-fat diet (HFD) consumption programs β-cell dysfunction in female rat offspring, together with transcriptome alterations in islets. Here we investigated the retroperitoneal white adipose tissue (RpWAT) transcriptome using gene and pathway enrichment and pathway analysis to determine whether commonly affected network topologies exist between these two metabolically related tissues. In RpWAT, 5108 genes were differentially expressed due to a paternal HFD; the top 5 significantly enriched networks identified by pathway analysis in offspring of HFD fathers compared with those of fathers fed control diet were: mitochondrial and cellular response to stress, telomerase signaling, cell death and survival, cell cycle, cellular growth and proliferation, and cancer. A total of 187 adipose olfactory receptor genes were down-regulated. Interrogation against the islet transcriptome identified specific gene networks and pathways, including olfactory receptor genes that were similarly affected in both tissues (411 common genes, P<0.05). In particular, we highlight a common molecular network, cell cycle and cancer, with the same hub gene, Myc, suggesting early onset developmental changes that persist, shared responses to programmed systemic factors, or crosstalk between tissues. Thus, paternal HFD consumption triggers unique gene signatures, consistent with premature aging and chronic degenerative disorders, in both RpWAT and pancreatic islets of daughters. © FASEB.

Rajab N.F.,National University of Malaysia
BMC complementary and alternative medicine | Year: 2014

Selective Alzheimer Disease Indicator-1 (or Seladin-1) is a multifunctional protein first discovered by downregulation of its expression in Alzheimer's disease. Interestingly, the expression of this protein is upregulated in several cancers, including primary bladder cancer. However, its role in cancer formation has yet to be discovered. Goniothalamin is a natural product that has been demonstrated to induce apoptosis in various cancer cell lines. In this study, we have elucidated the role of Seladin-1 in goniothalamin-induced cytotoxicity towards human urinary bladder cancer cell line RT4. The cytotoxicity of goniothalamin in human urinary bladder cancer cell line RT4 was assessed using MTT assay and the mode of cell death was determined by Annexin V-FITC/PI labeling assay. Finally, the expression of Seladin-1 protein in goniothalamin-treated RT4 cells was determined by Western blot. MTT assay showed that the cytotoxicity of goniothalamin on RT4 cells was concentration and time dependent with IC50 values of 61 μM (24 hr), 38 μM (48 hr) and 31 μM for 72 hr, respectively. Cell death induced was confirmed through apoptosis; as assessed using the Annexin V-FITC/PI labeling assay. Furthermore, the involvement of Seladin-1 in goniothalamin-induced apoptosis was evidenced through the cleavage of 60 kDa protein to 40 kDa and 20 kDa. This was followed by a gradual increase of 20 kDa fragment suggesting the involvement of Seladin-1 in goniothalamin-induced apoptosis on RT4 cells. This study demonstrates that goniothalamin induce cytotoxicity and apoptosis on RT4 cells. The involvement of Seladin-1 in goniothalamin-induced apoptosis further suggested that Seladin-1 may play a role in the formation of primary bladder cancer.

Rafiza S.,Institute for Medical Research | Rampal K.G.,National University of Malaysia | Tahir A.,Institute for Public Health
BMC Infectious Diseases | Year: 2011

Background: Health care workers are exposed to patients with tuberculosis and are at risk of nosocomial infection. The aim of this study was to determine the prevalence and factors associated with latent tuberculosis infection among health care workers in Malaysia and also to evaluate the agreement between Quantiferon TB Gold in tube test with Tuberculin Skin Test.Methods: A cross sectional study was conducted at four randomly selected hospitals in the Klang Valley from December 2008 to May 2009. Self administered questionnaire was used to obtain information on health care workers and possible risk factors. The response rate for this study was 90.8% with 954 respondents completed the questionnaire and were tested with Quantiferon TB Gold in tube for latent tuberculosis infection. Agreement between Quantiferon TB Gold in tube and Tuberculin Skin Test was assessed among 95 health care workers who consented to undergo both tests.Results: The overall prevalence of latent tuberculosis infection among health care workers was 10.6% (CI: 8.6%; 12.6%). Factors significantly associated with latent tuberculosis infection were aged 35 years and older [9.49 (CI: 2.22; 40.50)], history of living in the same house with close family members or friends who had active tuberculosis [8.69 (CI: 3.00; 25.18)], worked as a nurse [4.65 (CI: 1.10; 19.65)] and being male [3.70 (CI: 1.36; 10.02)]. Agreement between Quantiferon TB Gold in tube test and tuberculin skin test at cut-off points of 10 mm and 15 mm was 50.5% and 82.1% respectively. However, Kappa-agreement was poor for both cut-off points.Conclusion: The prevalence of latent tuberculosis infection in Malaysia was relatively low for an intermediate TB burden country. We could not comment on the occupational risk of latent tuberculosis infection among health care worker compared to the general population as there were no prevalence data available for latent tuberculosis infection in the general population. Kappa agreement between Quantiferon TB gold in-tube and tuberculin skin test was poor. © 2011 Rafiza et al; licensee BioMed Central Ltd.

Drack M.,University of Vienna | Gebeshuber I.C.,National University of Malaysia | Gebeshuber I.C.,Vienna University of Technology
Soft Matter | Year: 2013

We try to clarify some issues that were raised by an article that appeared in Soft Matter, 2012, 8, 6675. The main question was how to distinguish biomimetic, bioinspired and biokleptic research. We put forward a "continental" perspective that can help to avoid some of the confusion that might have been evoked. This journal is © 2013 The Royal Society of Chemistry.

Chow M.F.,University of Technology Malaysia | Yusop Z.,University of Technology Malaysia | Toriman M.E.,National University of Malaysia
International Journal of Environmental Science and Technology | Year: 2012

Due to differences in rainfall regimes and management practices, tropical urban catchments are expected to behave differently from temperate catchments in terms of pollutant sources and their transport mechanism. Storm Water Management Model (SWMM) was applied to simulate runoff quantity (peakflow and runoff depth) and quality (total suspended solids and total phosphorous) in residential, commercial and industrial catchments. For each catchment, the model was calibrated using 8-10 storm events and validated using seven new events. The model performance was evaluated based on the relative error, normalized objective function, Nash-Sutcliffe coefficient and 1:1 plots between the simulated and observed values. The calibration and validation results showed good agreement between simulated and measured data. Application of Storm Water Management Model for predicting runoff quantity has been improved by taking into account catchment's antecedent moisture condition. The impervious depression storages obtained for dry and wet conditions were 0. 8 and 0. 2 mm, respectively. The locally derived build-up and wash-off parameters were used for modelling runoff quality. © 2012 CEERS, IAU.

Hanita O.,National University of Malaysia
The Malaysian journal of pathology | Year: 2012

Threatened miscarriage is a common complication of pregnancy. Despite initial viability confirmation by ultrasound scan, some of these patients had further spontaneous abortion. A highly sensitive and specific biomarker would be useful to determine the outcome of pregnancy and to prevent emotional impact to these women. A prospective 14-month cohort study was conducted in the Obstetrics and Gynaecology Department of Universiti Kebangsaan Malaysia Medical Centre to determine whether low serum levels of pregnancy-associated plasma protein A (PAPP-A) measured in early pregnancy can predict the outcome of threatened abortion. 42 pregnant women between 6 to 22 weeks of gestation with threatened abortion and 40 controls were enrolled. Serum samples were collected at presentation and PAPP-A was assayed by electrochemiluminescent immunoassay technique. Pregnancies were followed-up until 22 weeks of gestations and the outcome documented. Nine patients (11%) developed spontaneous abortion and 73 patients (89%) had successful pregnancy. The median PAPP-A level was significantly lower in patients with spontaneous abortion compared to those who had successful pregnancies in the threatened abortion group: 0.78 MoM (0.41-1.00 MoM) vs 1.00 MoM (1.00-2.0 MoM) respectively (p < 0.05). The best sensitivity of 44% and specificity of 93% were obtained at the cut of value of 0.66 MoM (95% CI, 0.561-0.773). In conclusion, low PAPP-A value in threatened abortion women is associated with pregnancy failure, although the use of PAPP-A as a one-time single marker has limited value.

Muad A.M.,National University of Malaysia | Foody G.M.,University of Nottingham
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing | Year: 2012

Mixed pixels are one of the largest sources of error and uncertainty in mapping from remotely sensed data. A Hopfield neural network based approach to super-resolution mapping has become popular for mapping at a sub-pixel scale, partly because it seeks to maintain the class proportional information indicated by a soft classification analysis. The use of the approach is, however, handicapped by a lack of guidance on the parameter setting values and of the impacts of different landscape patterns on the analysis. Here, the sensitivity of the Hopfield neural network for super-resolution mapping is investigated with a focus on the effect of different landscape types and parameter settings using simulated and real data sets. It is shown that the method's suitability varies between landscapes, being most suited to situations in which landscape patches are large (> 1 pixel). Additionally, for such landscapes the widely used scenario in which the weighting parameters are set at equal values is successful but the approach is less effective for the mapping of small isolated land cover patches. With the latter, it is shown to be important to weight the area constraint highly and undertake a large number of iterations. Critically, it is shown that equal weighted parameter settings and imbalanced settings to emphasize the area constraint are most suitable for landscapes comprising large and small patches respectively. Moreover, the positive attributes of these two sets of parameter settings may be combined to yield an enhanced mapping method for landscapes that comprise a mixture of patch sizes. © 2008-2012 IEEE.

Yusoff S.F.M.,University of Bristol | Yusoff S.F.M.,National University of Malaysia | Hsiao M.-S.,University of Bristol | Schacher F.H.,University of Bristol | And 3 more authors.
Macromolecules | Year: 2012

The influence of solvent composition on micelle morphology has been investigated for two crystalline-coil poly(ferrocenyldimethylsilane-block-2- vinylpyridine) (PFS-b-P2VP) diblock copolymers with different block ratios (5:1 and 1:1). The solution self-assembly of these materials was explored in solvent mixtures containing different ratios of a good solvent for both blocks (THF) and a selective solvent for the P2VP block (isopropanol). Various micellar morphologies such as spheres and platelets were characterized using transmission electron microscopy (TEM), selected area electron diffraction (SAED), dynamic light scattering (DLS), wide-angle X-ray scattering (WAXS), and atomic force microscopy (AFM). The results showed that the solution self-assembly of PFS-b-P2VP block copolymers (5:1, 1:1) gave spherical micelles with an amorphous PFS core at low THF content (10 vol %). Subsequently, the amorphous spheres were slowly transformed into platelet micelles with a lenticular shape that consisted of a crystalline PFS core sandwiched by two coronal P2VP layers. This indicated that the amorphous spherical micelles were in a metastable state. The transformation of spheres into platelets was significantly slower for the 5:1 block copolymer with the longer PFS core-forming segment presumably due to a lower rate of crystallization of the metalloblock. Platelets were found to be dominant for both block copolymers at higher THF content (THF ≥ 30 vol %). The formation of lenticular rather than regular platelets was attributed to a poisoning effect whereby interference of the P2VP corona-forming blocks in the growth of the crystalline PFS core leads to the creation of defects in the crystal growth fronts. © 2012 American Chemical Society.

Hanita O.,National University of Malaysia | Hanisah A.H.,Hospital Tengku Ampuan Rahimah
Malaysian Journal of Pathology | Year: 2012

Early pregnancy failure is a common pregnancy complication. In clinical practice, the time delay to distinguish viable from nonviable pregnancy is often distressing to patients and doctors. A highly sensitive and specific biomarker that accurately discriminates between viable and nonviable pregnancy would be useful for early intervention. Progesterone has been shown as a biomarker of early pregnancy failure. However the usefulness is still questionable due to the different cut-off values used. A study was conducted to determine the role of progesterone as a marker of early pregnancy failure and to establish the cut-off value in discriminating between viable and nonviable pregnancy. The study was carried out in the Obstetric and Gynecology Patient Admission Centre (OBPAC), Universiti Kebangsaan Malaysia Medical Centre (UKMMC) for a period of twelve months. Ninety-five pregnant women of 13 weeks or less period of amenorrhoea (POA) were recruited. Fourteen normal pregnant women were controls. The patients with early pregnancy failure were classified according to types of abortion. Single measurement of serum progesterone was carried out during admission. The outcome of pregnancy was followed up until 22 weeks of POA to ascertain viability of the fetus. Median progesterone levels were significantly lower in women with nonviable pregnancies compared with viable pregnancy [10.7ng/ml (0.60-49.80) vs. 45.9ng/ml (15.40-127.20) respectively, p<0.001]. Progesterone levels were also significantly lower in threatened abortion patients with outcomes of nonviable pregnancy compared with pregnancies that progressed on to the viability period [23.3 ± 12.0 vs. 89.7 ± 33.2 respectively, p<0.001]. At cut-off value of 32.7ng/ ml, progesterone had 90% sensitivity with 75% negative predictive value and 92% specificity with 97% positive predictive value. The area under curve for progesterone was 0.95 (95% Confidence Interval, 0.903-0.990). In conclusion, these findings indicate that serum progesterone can be used as a marker for early pregnancy failure.

Kiah M.L.M.,University of Malaya | Haiqi A.,National University of Malaysia | Zaidan B.B.,University of Malaya | Zaidan A.A.,Sultan Idris University of Education
Computer Methods and Programs in Biomedicine | Year: 2014

Background: The use of open source software in health informatics is increasingly advocated by authors in the literature. Although there is no clear evidence of the superiority of the current open source applications in the healthcare field, the number of available open source applications online is growing and they are gaining greater prominence. This repertoire of open source options is of a great value for any future-planner interested in adopting an electronic medical/health record system, whether selecting an existent application or building a new one. The following questions arise. How do the available open source options compare to each other with respect to functionality, usability and security? Can an implementer of an open source application find sufficient support both as a user and as a developer, and to what extent? Does the available literature provide adequate answers to such questions? This review attempts to shed some light on these aspects. Objective: The objective of this study is to provide more comprehensive guidance from an implementer perspective toward the available alternatives of open source healthcare software, particularly in the field of electronic medical/health records. Methods: The design of this study is twofold. In the first part, we profile the published literature on a sample of existent and active open source software in the healthcare area. The purpose of this part is to provide a summary of the available guides and studies relative to the sampled systems, and to identify any gaps in the published literature with respect to our research questions. In the second part, we investigate those alternative systems relative to a set of metrics, by actually installing the software and reporting a hands-on experience of the installation process, usability, as well as other factors. Results: The literature covers many aspects of open source software implementation and utilization in healthcare practice. Roughly, those aspects could be distilled into a basic taxonomy, making the literature landscape more perceivable. Nevertheless, the surveyed articles fall short of fulfilling the targeted objective of providing clear reference to potential implementers. The hands-on study contributed a more detailed comparative guide relative to our set of assessment measures. Overall, no system seems to satisfy an industry-standard measure, particularly in security and interoperability. The systems, as software applications, feel similar from a usability perspective and share a common set of functionality, though they vary considerably in community support and activity. Conclusion: More detailed analysis of popular open source software can benefit the potential implementers of electronic health/medical records systems. The number of examined systems and the measures by which to compare them vary across studies, but still rewarding insights start to emerge. Our work is one step toward that goal. Our overall conclusion is that open source options in the medical field are still far behind the highly acknowledged open source products in other domains, e.g. operating systems market share. © 2014 Elsevier Ireland Ltd.

Amir A.A.,National University of Malaysia
Forest Ecology and Management | Year: 2012

Canopy opening or gap creation by lightning strike is an important form of exogenous disturbance in the mangroves of Matang in Malaysia. The almost circular shaped canopy gaps consist of a group of standing dead trees which decay simultaneously with the growth of new trees. This characteristic is chiefly different with terrestrial forests where canopy gaps are normally created by tree-falls. Lightning strike disturbance in mangroves has created a means for natural regeneration whereby dormant seedlings growing underneath the canopies have had the opportunity to progress and ultimately replacing the canopies of the dead trees. Historical and recent aerial photographs of the Virgin Jungle Reserve of Pulau Kecil in Matang were analysed to measure gap turnover rate and to calculate canopy turnover. The average (±SD) canopy turnover is 25.5 ± 6.9. years. This finding shows that the continuous dynamics of gap creation and closure have sustainably maintained the condition of the forest. The finding also supports the hypothesis that this disturbance prevents mangroves from reaching more senescent stage, thus, canopy gap creations are justified to be the key driver in the natural regeneration of the tropical Rhizophora-dominated mangroves. Curiously compared, the average turnover is almost similar to the existing 30-year rotation cycle system adopted by the Forestry Department for the management of forest compartments in Matang. © 2011 Elsevier B.V.

Ishak A.,National University of Malaysia | Lok Y.Y.,University Technical Malaysia Melaka | Pop I.,Technical University of Cluj Napoca
Chemical Engineering Communications | Year: 2010

An analysis is carried out to study the steady two-dimensional stagnation-point flow of a micropolar fluid over a shrinking sheet in its own plane. The shrinking velocity and the ambient fluid velocity are assumed to vary linearly with the distance from the stagnation point. The features of the flow characteristics are analyzed and discussed. Different from a stretching sheet, it is found that the solutions for a shrinking sheet are nonunique. © Taylor & Francis Group, LLC.

Bachok N.,University Putra Malaysia | Ishak A.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2010

An analysis is carried out to study the steady two-dimensional stagnation-point flow and heat transfer from a warm, laminar liquid flow to a melting stretching/shrinking sheet. The governing partial differential equations are converted into ordinary differential equations by similarity transformation, before being solved numerically using the Runge-Kutta-Fehlberg method. Results for the skin friction coefficient, local Nusselt number, velocity profiles as well as temperature profiles are presented for different values of the governing parameters. Effects of the melting parameter, stretching/shrinking parameter and Prandtl number on the flow and heat transfer characteristics are thoroughly examined. Different from a stretching sheet, it is found that the solutions for a shrinking sheet are non-unique. © 2010 Elsevier B.V.

Amara A.H.,Charite - Medical University of Berlin | Aljunid S.M.,University of Kuala Lumpur | Aljunid S.M.,National University of Malaysia
Globalization and Health | Year: 2014

With the increasing trend in refugee urbanisation, growing numbers of refugees are diagnosed with chronic noncommunicable diseases (NCDs). However, with few exceptions, the local and international communities prioritise communicable diseases. The aim of this study is to review the literature to determine the prevalence and distribution of chronic NCDs among urban refugees living in developing countries, to report refugee access to health care for NCDs and to compare the prevalence of NCDs among urban refugees with the prevalence in their home countries. Major search engines and refugee agency websites were systematically searched between June and July 2012 for articles and reports on NCD prevalence among urban refugees. Most studies were conducted in the Middle East and indicated a high prevalence of NCDs among urban refugees in this region, but in general, the prevalence varied by refugees' region or country of origin. Hypertension, musculoskeletal disease, diabetes and chronic respiratory disease were the major diseases observed. In general, most urban refugees in developing countries have adequate access to primary health care services. Further investigations are needed to document the burden of NCDs among urban refugees and to identify their need for health care in developing countries. © 2014 Amara and Aljunid; licensee BioMed Central Ltd.

Ramli A.,Ministry of Health | Ahmad N.S.,Ministry of Health | Paraidathathu T.,National University of Malaysia
Patient Preference and Adherence | Year: 2012

Purpose: Poor adherence to prescribed medications is a major cause for treatment failure, particularly in chronic diseases such as hypertension. This study was conducted to assess adherence to medications in patients undergoing hypertensive treatment in the Primary Health Clinics of the Ministry of Health in Malaysia. Factors affecting adherence to medications were studied, and the effect of nonadherence to blood pressure control was assessed. Patients and methods: This was a cross-sectional study to assess adherence to medications by adult patients undergoing hypertensive treatment in primary care. Adherence was measured using a validated survey form for medication adherence consisting of seven questions. A retrospective medication record review was conducted to collect and confirm data on patients' demographics, diagnosis, treatments, and outcomes. Results: Good adherence was observed in 53.4% of the 653 patients sampled. Female patients were found to be more likely to adhere to their medication regime, compared to their male counterparts (odds ratio 1.46 [95% confidence intervals [CI]: 1.05-2.04; P < 0.05]). Patients in the ethnic Chinese were twice as likely (95% CI: 1.14-3.6; P < 0.05) to adhere, compared to those in the Indian ethnic group. An increase in the score for medicine knowledge was also found to increase the odds of adherence. On the other hand, increasing the number of drugs the patient was taking and the daily dose frequencies of the medications prescribed were found to negatively affect adherence. Blood pressure control was also found to be worse in noncompliers. Conclusion: The medication adherence rate was found to be low among primary care hypertensive patients. A poor adherence rate was found to negatively affect blood pressure control. Developing multidisciplinary intervention programs to address the factors identified is necessary to improve adherence and, in turn, to improve blood pressure control. © 2012 Ramli et al, publisher and licensee Dove Medical Press Ltd.

Sharif R.,CSIRO | Sharif R.,University of Adelaide | Sharif R.,National University of Malaysia | Thomas P.,CSIRO | And 2 more authors.
Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis | Year: 2012

Zinc (Zn) is an essential trace element required for maintaining both optimal human health and genomic stability. Zn plays a critical role in the regulation of DNA repair mechanisms, cell proliferation, differentiation and apoptosis involving the action of various transcriptional factors and DNA or RNA polymerases. Zn is an essential cofactor or structural component for important antioxidant defence proteins and DNA repair enzymes such as Cu/Zn SOD, OGG1, APE and PARP and may also affect activities of enzymes such as BHMT and MTR involved in methylation reactions in the folate-methionine cycle. This review focuses on the role of Zn in the maintenance of genome integrity and the effects of deficiency or excess on genomic stability events and cell death. © 2011 Elsevier B.V.

Rosli M.K.,National University of Malaysia
Genetics and molecular research : GMR | Year: 2011

The Malayan gaur (Bos gaurus hubbacki) is one of the three subspecies of gaurs that can be found in Malaysia. We examined the phylogenetic relationships of this subspecies with other species of the genus Bos (B. javanicus, B. indicus, B. taurus, and B. grunniens). The sequence of a key gene, cytochrome b, was compared among 20 Bos species and the bongo antelope, used as an outgroup. Phylogenetic reconstruction was employed using neighbor joining and maximum parsimony in PAUP and Bayesian inference in MrBayes 3.1. All tree topologies indicated that the Malayan gaur is in its own monophyletic clade, distinct from other species of the genus Bos. We also found significant branching differences in the tree topologies between wild and domestic cattle.

Hassan K.H.,National University of Malaysia
American Journal of Animal and Veterinary Sciences | Year: 2014

This article examines the legal position of human and animal safety in zoos. The risk of injury or even death is high in zoos. Such risk can occur either to the people in charge of zoos, visitors or even to the animals themselves. As such, there are regulations enacted to safeguard people and animals from such risk. Tort is the primary law that governs liability of owner or management of a premise such as a zoo. Negligence and occupier's liability is the main branch of tort law which is the most relevant to accidents in zoos. Preventive law such as the Occupational Safety and Health Act and the Factories and Machinery Act are also used in ensuring safety at the work place (zoos). For the welfare and safety of animals captivated in zoos, the Wildlife Conservation legislation is enacted to ensure that animals or wildlife are treated well. Such is the scope of the article. The hypothesis of the study is that an effective law will ensure safety to human employed in and people visiting zoos and animals captivated in the zoos. The management of zoo differs from the management of other organizations. The methodology adopted is legal narrative and analysis with reference to legal instrument such as statutes passed by Parliament (legislative body). This article uses Malaysian law as a point of reference. The study finds that Malaysian law governing safety management in zoos is still inadequate. © 2014 Science Publication.

Masdi H.,University Putra Malaysia | Mariun N.,National University of Malaysia
International Review of Electrical Engineering | Year: 2010

The study reported in this paper was aimed to investigate transient response of power transformer when lightning current pass through its winding. Analysis of distribution voltage at the winding taps was done, both by experimental and numerical simulation, by applying IEC-71 standard current surge (8/20 μs impulse current and 1.2/50 μs impulse voltage). Transformer's constants as: R, L, C were derived from the transformer construction, which consists of 9 winding layers at HV-side. The wave-shapes of the voltage across the winding sections were recorded. The response of the windings was then compared with results of a simulation using EMTDC/PSCAD. The simulation based on an RLC network model resulted in wave-shapes that are in good agreement to those of the experiment. Both results of the simulation and experiment show that the distribution of the impulse voltage across the windings is non linear, especially during the period of fraction of microseconds. Furthermore, results of the investigation show that a simple capacitance network model is sufficient for study of the impulse voltage distribution across transformer windings. © 2010 Praise Worthy Prize S.r.l.

Selvachandran G.,UCSI University | Salleh A.R.,National University of Malaysia
Advances in Fuzzy Systems | Year: 2014

We introduce and develop the initial theory of vague soft hyperalgebra by introducing the novel concept of vague soft hypergroups, vague soft subhypergroups, and vague soft hypergroup homomorphism. The properties and structural characteristics of these concepts are also studied and discussed. © 2014 Ganeshsree Selvachandran and Abdul Razak Salleh.

Samimi P.,National University of Malaysia | Patel A.,Kingston University
ISCI 2011 - 2011 IEEE Symposium on Computers and Informatics | Year: 2011

Distributed system resources have become prevalent in ICT departments to lessen the burden of huge expenses incurred by very expensive storage computer systems. Add to this the continuous introduction and ever-growing evolution of simple to complex applications, the demand to access huge quantities of data, intensive computations, powerful simulations, maintaining and offering system resources and middleware infrastructure services the need to do all of this at an affordable and reasonable price is crucial. Distributed grid and cloud computing resources are currently considered to be one of the best technology options to provide this. They have many similar features and functions, and both of them are classed as distributed systems. They are capable of offering unaffordable resources and services at a reasonable price in a mass marketplace. The big question is: what is a reasonable price? How is pricing modeled and on what kind of economic principles is it based? Much of the issues surrounding these questions are very complex in themselves. This paper provides a comparative review of grid and cloud computing economic and pricing models from which appropriate tariffs and charging models can be chosen to meet particular business objectives. The actual choice depends on many other factors like enterprise regulations, tax laws, service level agreements and return on investments, are very important but outside the scope of this paper. In this paper we give the basic core principles and a comparative review of the latest and most appropriate economic and pricing models applicable to grid and cloud computing in order to propose better models for the future. © 2011 IEEE.

Chan H.-Y.,National University of Malaysia | Zhu J.,University of Nottingham | Riffat S.,University of Nottingham
Energy and Buildings | Year: 2012

A building integrated cooling facade is proposed in this paper. It is a fan-assisted system that consists of two vertical plenums. The first plenum was made of black aluminium transpired plate and a sandtile wall, while the second plenum is formed by the sandtile wall and the building wall. The aluminium plate served as a solar collector and the sandtile wall was an evaporative pad. The reverse side of the sandtile wall that contacted with the air in the second plenum was coated with a water-resistant layer, hence the air was cooled without adding any moisture into it. The facade cooling performance under various operating conditions is investigated through experiment and theoretical analyses. It is found that inlet water temperature is the key factor affecting the cooling performance. In terms of cooling efficiency, the energy consumption to generate 1 kW of cooling that cooling the air to 293 K is only 0.52 W, which is similar to the amount of energy required by some of the solar indirect evaporative cooling and desiccant cooling systems. © 2012 Elsevier B.V. All rights reserved.

Chongsuvivatwong V.,Prince of Songkla University | Phua K.H.,National University of Singapore | Yap M.T.,Institute of Policy Studies | Pocock N.S.,National University of Singapore | And 4 more authors.
The Lancet | Year: 2011

Southeast Asia is a region of enormous social, economic, and political diversity, both across and within countries, shaped by its history, geography, and position as a major crossroad of trade and the movement of goods and services. These factors have not only contributed to the disparate health status of the region's diverse populations, but also to the diverse nature of its health systems, which are at varying stages of evolution. Rapid but inequitable socioeconomic development, coupled with differing rates of demographic and epidemiological transitions, have accentuated health disparities and posed great public health challenges for national health systems, particularly the control of emerging infectious diseases and the rise of non-communicable diseases within ageing populations. While novel forms of health care are evolving in the region, such as corporatised public health-care systems (government owned, but operating according to corporate principles and with private-sector participation) and financing mechanisms to achieve universal coverage, there are key lessons for health reforms and decentralisation. New challenges have emerged with rising trade in health services, migration of the health workforce, and medical tourism. Juxtaposed between the emerging giant economies of China and India, countries of the region are attempting to forge a common regional identity, despite their diversity, to seek mutually acceptable and effective solutions to key regional health challenges. In this first paper in the Lancet Series on health in southeast Asia, we present an overview of key demographic and epidemiological changes in the region, explore challenges facing health systems, and draw attention to the potential for regional collaboration in health. © 2011 Elsevier Ltd.

Tham L.,University of Malaysia, Kelantan | Nazar R.,National University of Malaysia | Pop I.,Babes - Bolyai University
International Journal of Thermal Sciences | Year: 2014

Steady mixed convection boundary layer flow from an isothermal horizontal circular cylinder embedded in a porous medium filled with a nanofluid has been studied for both cases of a heated and cooled cylinder using the Buongiorno-Darcy mathematical nanofluid model. The resulting system of nonlinear partial differential equations is solved numerically using an implicit finite-difference scheme. The solutions for the flow and heat transfer characteristics are evaluated numerically for various values of the governing parameters, namely the constant mixed convection parameter λ, the traditional Lewis number Le, the buoyancy ratio parameter Nr, the Brownian motion parameter Nb and the thermophoresis parameter Nt. It is found that in the present case of the porous medium flow, the separation is always suppressed at negative values of λ. When λ changes from -2.1 to 0, one has a "heating" of the cylinder, but a heating in the negative range of λ (λ < 0). However, for a clear (Newtonian) fluid, Merkin (1977) found that heating the cylinder (λ > 0) delays the separation of the boundary layer and if the cylinder is hot enough (large values of λ > 0), then it is suppressed completely at a positive value of λ, somewhere between 0.88 and 0.89. On the other hand, cooling the cylinder (λ < 0) brings the boundary layer separation point nearer to the lower stagnation point and for a sufficiently cold cylinder (large values of λ < 0) there will not be a boundary layer on the cylinder. © 2014 Elsevier B.V. All rights reserved.

Mohd-Shaharuddin N.,National University of Malaysia
Fish & shellfish immunology | Year: 2013

Cryptocaryon irritans causes Cyptocaryonosis or white spot disease in a wide range of marine fish including Lates calcarifer (Asian seabass). However, the immune response of this fish to the parasite is still poorly understood. In this study, quantitative polymerase chain reaction (qPCR) was performed to assess the expression profile of immune-related genes in L. calcarifer infected by C. irritans. A total of 21 immune-related genes encoding various functions in the fish immune system were utilized for the qPCR analysis. The experiment was initiated with the infection of juvenile fish by exposure to theronts from 200 C. irritans cysts, and non-infected juvenile fish were used as controls. Spleen, liver, gills and kidney tissues were harvested at three days post-infection from control and infected fish. In addition, organs were also harvested on day-10 post-infection from fish that had been allowed to recover from day-4 up to day-10 post-infection. L. calcarifer exhibited pathological changes on day-3 post-infection with the characteristic presence of white spots on the entire fish body, excessive mucus production and formation of a flap over the fish eye. High quality total RNA was extracted from all tissues and qPCR was performed. The qPCR analysis on the cohort of 21 immune-related genes of the various organs harvested on day-3 post-infection demonstrated that most genes were induced significantly (p < 0.05) in all tissues, particularly liver (11/21 genes) and kidney (11/21). The expression profile demonstrated that induction of the MHC Class IIα gene was the highest compared to the other genes followed by serum amyloid A, CC chemokine and hepcidin-2 precursor genes. In fish that were allowed to recover from the C. irritans infection (10 days post-infection), expression of the immune-related genes was down-regulated to levels similar to the control fish. These results provide insights into the interaction between C. irritans and L. calcarifer and suggest that the innate immune system plays an important role in early defence against parasite infection allowing the fish to eventually recover from the infection. Copyright © 2012 Elsevier Ltd. All rights reserved.

Bradley M.,University of Bristol | Lazim A.M.,National University of Malaysia | Eastoe J.,University of Bristol
Polymers | Year: 2011

Heteroaggregation is the aggregation of mixed particle systems where the colloidal particles may differ in charge, size and chemical composition. The phenomenon of heteroaggregation is of great relevance in industrial processes and the natural environment. This review will focus on binary heteroaggregation where at least one of the particles is a stimulus-responsive smart particle. Aggregation under various conditions of pH, temperature, light and relative concentration can be induced by the careful manipulation of any one or more of these environmental conditions during the heteroaggregation of smart particles. Stimulus response provides the potential for reversibility from an aggregated to a stable system and exceptional control over inter-particle interactions. The significant fundamental and applied studies that have made an impact in this area will be discussed.

Mossa Al-sawalha M.,Hail University | Noorani M.S.M.,National University of Malaysia | Al-dlalah M.M.,Hail University
Computers and Mathematics with Applications | Year: 2010

This paper centers on the chaos anti-synchronization between two identical or different chaotic systems using adaptive control. The sufficient conditions for achieving the anti-synchronization of two chaotic systems are derived based on Lyapunov stability theory. An adaptive control law and a parameter update rule for unknown parameters are introduced such that the Chen system is controlled to be the Lorenz system. Theoretical analysis and numerical simulations are shown to verify the results. © 2010 Elsevier Ltd. All rights reserved.

Ng Y.F.,National University of Malaysia | Mound L.A.,CSIRO
Zootaxa | Year: 2012

Four species of Stenchaetothrips are here recorded from Peninsular Malaysia. These are S. biformis, the widespread rice thrips, S. hullikali, known only from Karnataka in Southwest India, S. indicus, a widespread species on grasses, and S. langkawiensis sp. nov., described here from Langkawi Island, West Malaysia. Species descriptions, photographs and an identification key are provided. Copyright © 2012 · Magnolia Press.

Misran H.,University of Tenaga Nasional | Yarmo M.A.,National University of Malaysia | Ramesh S.,University of Malaya
Ceramics International | Year: 2013

In the present work monodispersed silica spheres were successfully synthesized using nonsurfactant approach of neutral palm oil derived fatty alcohols based microemulsions. The resulting silica spheres have diameter in two size clusters; ca. 560 nm and ca. 700 nm, respectively. The synthesis was acomplished by using straight chain fatty alcohols in a combined approach of sol-gel and Stöber method without extensive washing. Translucent nonsurfactant microemulsions containing straight chain fatty alcohols namely octyl alcohol (C8), decyl alcohol (C10) and dodecyl alcohol (C12) were successfully obtained. Short chain alcohols such as ethanol and methanol were used as co-solvent in the formation of silica spheres. Tetraethylorthosilicate were used as silica source as well as co-structure directing agent. The resulting silica spheres were successfully functionalized with octyl-4-methoxy cinnamate (OMC) as UV-absorbing compounds in a direct nonsurfactant co-condensation during the synthesis process. The technique employed was found to be most viable in producing silica spheres for applications as meta-atom in the fabrication of metamaterials. © 2012 Elsevier Ltd and Techna Group S.r.l.

Zulkifley M.A.,National University of Malaysia
Optik | Year: 2016

One of the weaknesses of the mean-shift tracker is its limited ability to track a fast-moving object. Not only does the captured image look blurred but the object will often be out of the search window. Moreover, blur issue is a normal occurrence for a fast-moving object by using a commercially available camera due to a low frame rate. This paper aims to develop a robust observation detector for a single object tracker, especially for blurred image, fast-moving and non-rigid object. We propose a fusion of a kernel-based histogram and feature detector based approach. The measurement input is selected from candidate patches that will be generated by matching the vector descriptor. These vectors are built based on the detected points of interest. Two colour spaces are considered where all three channels of RGB are used, while only the hue channel of the HSV space is utilized. The kernel method is employed for better histogram accumulation. The output patch of the previous frame will be the target model where histogram similarity is measured based on Gaussian distribution. The selected output of the patch matching will undergo position smoothing for better precision. Maximum likelihood approach is used to iterate the patch position until the best match is found. The results indicate that our algorithm has a good detection for challenging surroundings and environments. In some cases, our algorithm may have less accuracy but in no case did it failed to detect. © 2015 Elsevier GmbH. All rights reserved.

Nimir A.R.,National University of Malaysia
Acta medica (Hradec Králové) / Universitas Carolina, Facultas Medica Hradec Králové | Year: 2011

The local Chow Kit market is the largest wet market in the city of Kuala Lumpur. It is very close to the biggest government hospital in the city centre. However, the level of cleanliness in this area is always questionable and a matter of concern. The aim of this study was to identify the prevalence of T. gondii oocyst in water samples used by hawkers in that market and tissue cysts in rats' brains captured from the same area. Water samples were taken to the parasitology laboratory at the National Universtiy of MalaysiaUniversity and a sugar flotation concentration method was used. Supernatant microscopical examination was then performed. A total of 752 slides were screened for the presence of T. gondii oocyst. A hundred rats wandering in the same area were also captured by the hawkers using mousetraps. After each animal was sacrificed, and an electric microtome was used to cut out serial sections 5 microm thick from the rat brains. The de-waxed tissue sections were stained by the progressive Haematoxylin and Eosin (H&E) stain for microscopical examination. A total of 1000 slides were screened under a light microscope to detect the presence of T. gondii brain cysts. All the water samples were found to be negative for T. gondii oocyst. Out of the 100 rats captured, three rats were found to possess T. gondii cysts in their brains. Water samples reflect minimal or no solid food contamination, while the 3% of positive brain cysts influence the researchers to broaden their investigations for future projects.

Buang N.A.,National University of Malaysia
Research Journal of Applied Sciences | Year: 2011

The purpose of this study was to explore the entrepreneurship career paths of Malaysian graduate entrepreneurs who graduated from local and overseas higher learning institutions between the years of 1988 to 2003. The paths explored in this study include career-changing phases starting from early career intentions up to business start-ups. This study also find out which entrepreneurship career paths mostly taken and least taken by the graduate entrepreneurs such as incremental path intuitive path, methodical path and accidental path based on their level of education, their field of studies (program majors) and whether local or overseas higher learning institutions attended. A set of questionnaire was constructed and a total of both 399 local and overseas graduate entrepreneurs were randomly selected from the total population of the graduate entrepreneurs. Descriptive statistics such as the frequency and percentage were used to present the graduate entrepreneurs' profile, their career-intentions changing phases and entrepreneurial career paths taken. The findings show that accidental path was the most taken entrepreneurial career path followed by methodical intuitive and incremental paths regardless of their level of education, field of studies and local or overseas higher learning institutions. The implications of the findings suggest that universities in the country should evaluate the effectiveness of their entrepreneurship programs's curriculum in terms of increasing the number of graduates choosing the intuitive and incremental paths to entrepreneurs. © 2011 Medwell Journals.

Nordin R.,National University of Malaysia
Global Journal of Engineering Education | Year: 2013

A study involving recent graduates of the Department of Electrical, Electronic and Systems Engineering (EESE) at Universiti Kebangsaan Malaysia has been carried out to evaluate the impact of technical communication skills they acquired. The graduates are currently working in six different job categories with different work experience (between one to three years). The objectives of this study are to evaluate the impact and effectiveness of the technical communication courses offered in the Department towards the graduates in their workplace and engineering experiences. In addition, the study aimed to enhance the current technical courses implementation based on the graduates' suggestions as part of the Department's continuous quality improvement activities. Survey results reveal the need for technical communication skills in order to allow engineering graduates to adjust to their employer's demand and achieve their future career goals. The results from this study suggest that there is a direct relationship between the skills acquired from the technical communication skills courses and their day-to-day communication in the workplace. © WIETE 2013.

Kadir N.B.A.,National University of Malaysia | Bifulco A.,Royal Holloway, University of London
Culture, Medicine and Psychiatry | Year: 2010

Standard psychiatric criteria for depression developed in the United States and United Kingdom are increasingly used worldwide to establish the prevalence of clinical disorders and to help develop services. However, these approaches are rarely sensitive to local and cultural expressions of symptoms or beliefs about treatment. Mismatch between diagnostic criteria and local understanding may result in underreporting of depression and underutilization of services. Little such research has been conducted in Malaysia, despite the acknowledged high rate of depression and low access to services. This study examines depression in Moslem Malay women living in Johor Bahru, Southern Peninsular Malaysia, to explore depression symptoms using the Structured Clinical Interview for DSM-IV. The 61 women interviewed were selected on the basis of high General Health Questionnaire scores from a large questionnaire survey of 1,002 mothers. The illustrative analysis looks at descriptions of depressed mood, self-depreciation and suicidal ideation, as well as attitudes toward service use. The women gave full and open descriptions of their emotional symptoms, easily recognizable by standard symptom categories, although somatic symptoms were commonly included, and the spiritual context to understanding depression was also prevalent. However, few women had knowledge about treatment or sought medical services, although some sought help from local spiritual healers. Attending to such views of depression can help develop services in Malaysia. © 2010 Springer Science+Business Media, LLC.

Taha M.R.,National University of Malaysia | Ibrahim A.H.,University Malaysia Perlis
Journal of Water Process Engineering | Year: 2014

Due to the extremely high content of organic pollutants, palm oil mill effluent (POME) requires multiple stages of treatment. At the primary stage, because of the high loading of organics, anaerobic treatment method was found to be the best practice nowadays. However, at the later stages, the treatment methods vary. As an option to available secondary and tertiary treatment method, we used an aerated heterogeneous Fenton process to remove chemical oxygen demand (COD) from anaerobically treated palm oil mill effluent (AT-POME). The Box-Behnken design (BBD) and response surface method (RSM) were used to design and optimize the performance of the process. Furthermore, the regression quadratic model representing the COD removal efficiency of aerated heterogeneous Fenton was developed and validated by the analysis of variances (ANOVA). The optimum parameters were determined as 3.91g/l of nZVI dosage, 1.84g/l of H2O2 dosage, and 23.84l/h of aeration and 240min of reaction time. As 75% of COD was predicted to be removed at the optimum condition, the aerated heterogeneous Fenton process is a promising treatment method for AT-POME. © 2014 Elsevier Ltd.

Tohit N.,National University of Malaysia | Browning C.J.,Monash University | Radermacher H.,Monash University
Ageing and Society | Year: 2012

Healthy ageing concepts have been extensively studied in Western societies but few studies have explored the perceptions of older people from other cultural backgrounds. The aim of the study was to explore the conceptualisations of healthy ageing and perceived influences on ageing well amongst relatively healthy older Malays, a major ethnic group in Malaysia. Eight focus groups were conducted, with 38 participants recruited via community groups and leaders. Six themes were identified: spirituality, physical health and function, peace of mind, financial independence, family, and living environment. In this paper, we focus on the role of spirituality in healthy ageing which was a core resource in participants' lives. Participants reported that good physical health was an important resource that facilitated commitment to their spiritual activities. Furthermore, deteriorating functional ability appeared to provide an opportunity to optimise their spirituality, rather than hinder it. Participants wished for a 'peaceful life' and experienced this by enhancing their spirituality. Other ingredients for a peaceful life were financial independence, living in a place they love and having family members who live in harmony. In this community where religious affiliation is a tradition, spirituality can be fundamental for healthy ageing and its inclusion in aged care policy is imperative. However, further exploration on the diversity of individual expression of spirituality is important. © 2011 Cambridge University Press.

Bhadauria B.S.,Babasaheb Bhimrao Ambedkar University | Hashim I.,National University of Malaysia | Siddheshwar P.G.,Bangalore University
International Journal of Non-Linear Mechanics | Year: 2013

In this paper, we study the combined effect of internal-heating and time-periodic gravity modulation on thermal instability in a viscous fluid layer, heated from below. The time-periodic gravity modulation, considered in this problem can be realized by vertically oscillating the fluid layer. A weak non-linear stability analysis has been performed by using power series expansion in terms of the amplitude of gravity modulation, which is assumed to be small. The Nusselt number has been obtained in terms of the amplitude of convection which is governed by the non-autonomous Ginzburg-Landau equation derived for the stationary mode of convection. Effects of various parameters such as internal Rayleigh number, Prandtl number, and amplitude and frequency of gravity modulation have been analysed on heat transport. It is found that the response of the convective system to the internal Rayleigh number is destabilizing. Further, it is found that the heat transport can be controlled by suitably adjusting the external parameters of the system. © 2013 Elsevier B.V. All rights reserved.

The sRNAs of bacterial pathogens are known to be involved in various cellular roles including environmental adaptation as well as regulation of virulence and pathogenicity. It is expected that sRNAs may also have similar functions for Burkholderia pseudomallei, a soil bacterium that can adapt to diverse environmental conditions, which causes the disease melioidosis and is also able to infect a wide variety of hosts. By integrating several proven sRNA prediction programs into a computational pipeline, available Burkholderia spp. genomes were screened to identify sRNA gene candidates. Orthologous sRNA candidates were then identified via comparative analysis. From the total prediction, 21 candidates were found to have Rfam homologs. RT-PCR and sequencing of candidate sRNA genes of unknown functions revealed six putative sRNAs which were highly conserved in Burkholderia spp. and two that were unique to B. pseudomallei present in a normal culture conditions transcriptome. The validated sRNAs include potential cis-acting elements associated with the modulation of methionine metabolism and one B. pseudomallei-specific sRNA that is expected to bind to the Hfq protein. The use of the pipeline developed in this study and subsequent comparative analysis have successfully aided in the discovery and shortlisting of sRNA gene candidates for validation. This integrated approach identified 29 B. pseudomallei sRNA genes - of which 21 have Rfam homologs and 8 are novel.

Zakaria S.Z.S.,National University of Malaysia
Research Journal of Applied Sciences | Year: 2011

Science education has become one of the core subjects in Malaysia primary schools and since 2003 it has been taught to students as early as year 1 (7 years old). The contents of science curriculum in the primary schools, consists the knowledge and facts of environmental education related factors. The objectives of this study is to find out the elements of environmentally related subject that is taught in science classes which concurrent towards environmental sustainability. To be able to become a developed country by year 2020, Malaysia must not only have a scientifically and technologically literate citizens but they must know and be aware of how to sustain the development. This can be accomplish if the children in schools today are prepared and geared towards an education that taught and shaped their thinking and behavior towards the important of a sustainable development So, the knowledge of science must not only able to make them good inventors or creative innovators that can contribute to the development of science and technology but also must be able to make them aware and conscious of their actions that might give bad or negative influence to the environment. © Medwell Journals, 2011.

Noor N.F.M.,University of Selangor | Abdulaziz O.,Sanaa University | Hashim I.,National University of Malaysia
International Journal for Numerical Methods in Fluids | Year: 2010

The magnetohydrodynamics flow and heat transfer in a thin liquid film over an unsteady elastic stretching surface are analyzed by the homotopy analysis method. A more general surface temperature is taken into consideration. The effects of various parameters in this study are discussed and presented graphically. The good agreement between the analytic series solutions and the previous numerical results shows the effectiveness of HAM to this problem. Copyright © 2009 John Wiley & Sons, Ltd.

Nordin R.,National University of Malaysia
Journal of Computer Networks and Communications | Year: 2012

One of the efficient ways to transmit high data rate is by employing a multiple-input multiple-output (MIMO) transmission. One of the MIMO schemes, known as spatial multiplexing (SM), relies on the linear independence data streams from different transmit antennas to exploit the capacity from the fading channels. Consequently, SM suffers from the effect of spatial correlation which is the limiting factor in achieving the capacity benefit that SM can offer. In an attempt to increase the robustness of the SM transmission in a wide range of correlated channels, the use of dynamic subcarrier allocation (DSA) is investigated. The effective signal-to-interference-and-noise ratio (SINR) metric is used as the performance metric to determine the subcarrier quality which can then be utilised in the allocation. Two novel variants of the subcarrier allocation scheme are proposed. It is shown that the DSA-SINR approach improves the BER performance of SM transmission in highly correlated channels environment. © Copyright 2012 Rosdiadee Nordin.

Al-Kadi M.I.,National University of Malaysia
Sensors (Basel, Switzerland) | Year: 2013

Biosignal analysis is one of the most important topics that researchers have tried to develop during the last century to understand numerous human diseases. Electroencephalograms (EEGs) are one of the techniques which provides an electrical representation of biosignals that reflect changes in the activity of the human brain. Monitoring the levels of anesthesia is a very important subject, which has been proposed to avoid both patient awareness caused by inadequate dosage of anesthetic drugs and excessive use of anesthesia during surgery. This article reviews the bases of these techniques and their development within the last decades and provides a synopsis of the relevant methodologies and algorithms that are used to analyze EEG signals. In addition, it aims to present some of the physiological background of the EEG signal, developments in EEG signal processing, and the effective methods used to remove various types of noise. This review will hopefully increase efforts to develop methods that use EEG signals for determining and classifying the depth of anesthesia with a high data rate to produce a flexible and reliable detection device.

Bachok N.,University Putra Malaysia | Ishak A.,National University of Malaysia | Pop I.,Technical University of Cluj Napoca
Transport in Porous Media | Year: 2010

The steady boundary-layer flow near the stagnation point on a vertical flat plate embedded in a fluid-saturated porous medium characterized by an anisotropic permeability is investigated. Using appropriate similarity transformation, the governing system of partial differential equations is transformed into a system of ordinary differential equations. This system is then solved numerically. The features of the flow and the heat transfer characteristics for different values of the governing parameters, namely, the modified mixed convection parameter Λ, and the anisotropy parameter A are analyzed and discussed. It is found that dual solutions exist for both assisting and opposing flows. Moreover, the range of Λ for which the solution exists increases with A. © Springer Science+Business Media B.V.2009.

Mahmud M.N.,University of Kuala Lumpur | Hashim I.,National University of Malaysia
Transport in Porous Media | Year: 2010

Feedback control on thermal convection in a fluid-saturated porous medium is investigated based on the dynamical systems approach. A low dimensional Lorenz-like model was obtained using the Galerkin-truncated approximation. The possible suppression or enhancement of chaotic convection is demonstrated when the fluid layer is subjected to feedback control in a low-dimensional framework. © 2009 Springer Science+Business Media B.V.

Abd. Majid N.A.,National University of Malaysia
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2013

Engaging learning environment for learning complex materials in higher education is difficult to perform because the contents are mostly theoretical and hard to visualize. This problem motivates the use of mobile augmented reality in this research. The objective of this research is to design and develop a mobile augmented reality application that can enhance the student's perception of the selected materials in computer organization and operating system course. The application was developed using three levels of knowledge (understand, apply, analyze) and involved the integration of video, audio, graphic and text information. The evaluation of the application using responses from 13 second year university students shows that this application can be used to enhance the students understanding and engage them in a group discussion for solving the given exercises. This application is expected to be a good start for learning complex materials in the selected course and can be extended to cover different levels of knowledge and subjects. © 2013 Springer International Publishing.

Chamhuri N.,National University of Malaysia | Batt P.J.,Curtin University Australia
Journal of Retailing and Consumer Services | Year: 2013

Differences in retail store choice behaviour are examined for the purchase of fresh meat and fresh fruit and vegetables in Malaysia. In purchasing fresh meat, cluster analysis identified two groups of respondents who purchased the majority of the fresh meat they consumed from either modern retail stores or the traditional market. However, with regard to the purchase of fresh fruit and vegetables, cluster analysis identified three groups of respondents (modern retail shoppers, transient shoppers and traditional market shoppers). Although the clusters were labelled using similar terms, several similarities and differences were identified in the respective clusters for each food item. The findings indicate that store choice preference was based on the food product that the consumer intended to purchase. © 2013 Elsevier Ltd.

Er A.C.,National University of Malaysia
Asian Social Science | Year: 2011

The aim of this paper is to carry out a comparative analysis of the Brazilian bioethanol sector and the Malaysian palm biofuel sector. The major findings for the Brazilian experience are economic nationalism, mandatory policy with initial focus on the domestic market, a nationwide biofuel infrastructure, incentivized mill construction and the adoption of flex-fuel vehicles are the cornerstone of its success. Production factors like abundant sugar cane feedstock and evolving production technologies have made immense contribution. The Malaysian experience however differs from that of Brazil's. The minuscule domestic market, a lack of biofuel infrastructure on a nationwide basis and a small number of diesel passenger vehicles force the Malaysian biofuel producers to be reliant on the international market. The viability of palm biofuel is very much dependent on petroleum prices. If food value is higher than fuel value, palm oil would be diverted towards food production and vice versa.

Grismer L.L.,La Sierra University | Onn C.K.,National University of Malaysia
Zootaxa | Year: 2010

A new species of forest dwelling Rock Gecko, Cnemaspis roticanai sp. nov., is described from the upper elevations of Gunung Raya, Pulau Langkawi, Kedah, Peninsular Malaysia. Cnemaspis roticanai is the second species of Cnemaspis described from Pulau Langkawi and is differentiated from all other Southeast Asian Cnemaspis in having a unique combination of color pattern and scale characteristics including keeled subtibials, ventrals, subcaudals, dorsal tubercles, and forearm scales; 25-27 paravertebral tubercles; a median row of enlarged, keeled subcaudals; five or six precloacal, pore-bearing scales in males separated medially by one or two non-pore-bearing scales; 26-29 subdigital lamellae on the fourth toe; no dark, longitudinal gular markings or blotches; no dark shoulder patch enclosing a white to yellow ocellus; and having a yellow to white, prescapular crescent. Cnemaspis roticanai is the latest species in a growing list of new taxa being discovered from the Langkawi Archipelago. Copyright © 2010 Magnolia Press.

Alam S.S.,National University of Malaysia | Sayuti N.M.,University Technology of MARA
International Journal of Commerce and Management | Year: 2011

Purpose-In this study, Ajzen’s Theory of Planned Behavior is used as a theoretical framework with the aim of extending prior research examining halal food purchasing behavior in Malaysia. Design/methodology/approach-Data are collected through self-administered questionnaires. This paper uses multiple regression analysis to identify the factors affecting halal food purchasing behavior of Malaysian consumers. Findings-The multiple regression analysis results indicate that all factors have positive and significant influence on halal food purchasing intention. Research limitations/implications-Like other empirical studies, this study is not without its limitations. The sample size itself is relatively small. The study can be strengthened by increasing the sample size and including participants in other geographical areas. This study also considered only three antecedents of halal food purchasing among consumers in Malaysia. As Malaysia is actually trying to play for a bigger role in the halal industry, more research is needed to identify and address problematic aspects of consumption of halal food. Potential correlations between some of the independent variables (e.g. trust, moral obligation, habit, and self-identity) need to be reported in a future study. Originality/value-This study contributes to and extends our understanding of the halal food purchasing behavior, identifying the rationales for purchasing of halal foods. From a managerial viewpoint, the findings provide support for investment decisions and for decisions relating to the establishment of Malaysia as a halal hub that address and take the concerns and needs of businesses and Malaysian Government agencies into consideration. © Emerald Group Publishing Limited.

Hatah E.,University of Otago | Hatah E.,National University of Malaysia | Braund R.,University of Otago | Tordoff J.,University of Otago | Duffull S.B.,University of Otago
British Journal of Clinical Pharmacology | Year: 2014

Aim The aim was to examine the impact of fee-for-service pharmacist-led medication review on patient outcomes and quantify this according to the type of review undertaken, e.g. adherence support and clinical medication review. Methods Relevant published studies were identified from Medline, Embase and International Pharmaceutical Abstract databases (from inception to February 2011). Study inclusion criteria were fee-for-service medication review, presence of a control group and pre-specified patient outcomes. Outcomes were grouped into primary (changes in biomarkers, hospitalization, and mortality) and secondary outcomes (medication adherence, economic implications and quality of life). Meta-analyses for primary outcomes were conducted using random effects models and secondary outcomes were summarized using descriptive statistics. Results Of the 135 relevant articles located, 21 studies met the inclusion criteria for primary outcomes and 32 for secondary outcomes. Significant results favouring pharmacists' intervention were found for blood pressure (OR 3.50, 95% CI 1.58, 7.75, P = 0.002) and low density lipoprotein (OR 2.35, 95% CI 1.17, 4.72, P = 0.02). Outcomes on hospitalization (OR 0.69, 95% CI 0.39, 1.21, P = 0.19) and mortality (OR 1.50, 95% CI 0.65 to 3.46, P = 0.34) indicated no differences between the groups. On subgroup analysis, clinical medication review (OR 0.46, 95% CI 0.26, 0.83, P = 0.01) but not adherence support review (OR 0.88, 95% CI 0.59, 1.32, P = 0.54) reduced hospitalization. Conclusions The majority of the studies (57.9%) showed improvement in medication adherence. Fee-for-service pharmacist-led medication reviews showed positive benefits on patient outcomes. Interventions that include a clinical review had a significant impact on patient outcomes by attainment of target clinical biomarkers and reduced hospitalization. © 2013 The British Pharmacological Society.

Ismail N.A.S.,National University of Malaysia
Malaysian Journal of Medical Sciences | Year: 2016

This study explores the experience of both learners and a teacher during a team-based learning (TBL) session. TBL involves active learning that allows medical students to utilise their visual, auditory, writing and kinetic learning styles in order to strengthen their knowledge and retain it for longer, which is important with regard to applying basic sciences in clinical settings. This pilot study explored the effectiveness of TBL in learning medical genetics, and its potential to replace conventional lectures. First-year medical students (n = 194) studying at Universiti Kebangsaan, Malaysia, during 2014/2015 were selected to participate in this study. The topic of ‘Mutation and Mutation Analysis’ was selected, and the principles of TBL were adhered to during the study. It was found that the students' performance in a group readiness test was better than in individual readiness tests. The effectiveness of TBL was further shown in the examination, during which the marks obtained were tremendously improved. Collective commentaries from both the learners and the teacher recommended TBL as another useful tool in learning medical genetics. Implementation strategies should be advanced for the benefit of future learners and teachers. © Penerbit Universiti Sains Malaysia, 2016.

In this article, we report on the synthesis and characterisation of novel mesoporous α-Mn2O3 microspheres obtained by the thermal decomposition of hydrothermally grown MnCO3. The porous, hierarchical Mn2O3 microspheres were obtained without the use of any structural directing agents or templates. The self-sacrificing template character of the hydrothermally grown MnCO3 is clearly presented here. Body centred cubic phase pure crystalline structure of Mn 2O3 was acquired at 600 °C, whereas a minor Mn 3O4 phase was detected at 500 °C. The microsphere-like morphology of the intermediate precursor and the final products was clearly observed in the field emission scanning electron microscopy (FESEM) images, which depicted the morphology conserved thermal decomposition process. Roughly spherical and elongated Mn2O3 sub-nanoparticles were hierarchically gathered inside the microspheres, which points to the development of a mesoporous texture, as confirmed by the transmission electron microscopy (TEM) and porosity studies. The optical properties studied using photoluminescence spectroscopy indicated its applications under UV-light. © 2014 Elsevier B.V.

Kazem H.A.,Sohar University | Khatib T.,Klagenfurt University | Sopian K.,National University of Malaysia | Elmenreich W.,Klagenfurt University
Energy and Buildings | Year: 2014

This paper presents a design and evaluation practice of a grid-connected photovoltaic system installed in Sohar, Oman. Hourly solar radiation and ambient temperature data for one year time are utilized. The designed system is implemented practically and tested for six months to check its productivity and feasibility. The system is evaluated using three technical criteria which are capacity, yield and performance factors. In addition, system's feasibility is evaluated in terms of cost of energy and payback period. The results show that the capacity and the yield factors for the proposed system are 21% and 1875 kW h/kW p/year respectively. In addition, the performance factor of the proposed system is 84.6%. In the meanwhile, the cost of the energy generated and the payback period of the proposed system are 0.045 USD/kW h and 11 years, respectively. This study contains valuable experiment data for those who are interested in photovoltaic system in Oman and nearby desertic zones. © 2014 Elsevier B.V.

Yacob N.A.,University Technology of MARA | Ishak A.,National University of Malaysia | Ishak A.,University of Malaya | Pop I.,Technical University of Cluj Napoca