Polarized infrared (IR) reflectance spectrum studies of bulk wurtzite ZnO are presented. The features of the polarized IR reflectance spectra and the optical characteristics of ZnO were investigated. Based on the anisotropic dielectric function model, the experimental IR reflectance spectra were numerically fitted by the theoretical IR reflectance spectra. The obtained transverse optical (TO) and longitudinal optical (LO) frequencies, i.e., ωTO⊥(ωTO||) and ωLO⊥(ωLO|| ) are 411 cm-1 (384 cm-1) and 589.8 cm-1 (572 cm-1), respectively. These results are compared with the reported values measured from the other techniques. Good agreement has been obtained.
Silicon nanomaterial was prepared using the peroxide/acid/salt technique in which an aqueous silicon-based salt solution was added to H2O2/HF etchants. In order to optimize the experimental conditions for silicon nanomaterial production, the amount of nanomaterial produced was studied as a function of the volume of the silicon salt solution used in the synthesis. A set of samples was prepared using: 0, 5, 10, 15, and 20 mL of an aqueous 1 mg/L metasilicate solution. The area under the corresponding peaks in the infrared (ir) absorption spectra was used as a qualitative indicator to the amount of the nanomaterial present. The results indicated that using 10 mL of the metasilicate solution produced the highest amount of nanomaterial. Furthermore, the results demonstrated that the peroxide/acid/salt technique results in the enhancement of the production yield of silicon nanomaterial at a reduced power demand and with a higher material to void ratio. A model in which the silicon salt forms a secondary source of silicon nanomaterial is proposed. The auxiliary nanomaterial is deposited into the porous network causing an increase in the amount of nanomaterial produced and a reduction in the voids present. Thus a reduction in the resistance of the porous layer, and consequently reduction in the power required, are expected.
The main aim of this paper was to validate the relative price monetary model (RPMM) of exchange rate determination for the Malaysian exchange rate (RM/USD) using monthly data set from 1986-2010. The Johansen multivariate cointegration test and vector error correction model were employed. Because the time period under consideration includes the South
East Asian financial crisis, the analysis is done using two time periods; the full time period as well as the period after the crisis. Two interesting results were observed from this empirical exercise. First, there is a long-run relationship between exchange rate and the selected macro variables only for the period after the crisis. Second, the forecasting performance of monetary approach based on the error correction model outperformed the Random Walk model.
The accuracy of financial time series forecasts often rely on the model precision and the availability of actual observations for forecast evaluations. This study aimed to tackle these issues in order to obtain a suitable asymmetric time-varying volatility model that outperformed in the forecast evaluations based on interday and intraday data. The model precision was examined based on the most appropriate time-varying volatility representation under the autoregressive conditional heteroscedascity framework. For forecast precision, the evaluations were conducted under three loss functions using the volatility proxies and realized volatility. The empirical studies were implemented on two major financial markets and the estimated results are applied in quantifying their market risks. Empirical results indicated that Zakoian model provided the best in-sample forecasts whereas DGE on the other hand indicated better out-of-sample forecasts. For the type of volatility proxy selection, the implementation of intraday data in the latent volatility indicated significant improvement in all the time horizon forecasts.
This study investigates the value-at-risk (VaR) using nonlinear time-varying volatility (ARCH model) and extreme-value-theory (EVT) methodologies. Similar VaR estimation and prediction are observes under the EVT and heavy-tailed long-memory ARCH approaches. The empirical results evidence the EVT-based VaR are more accurate but only at higher quantiles. It is also found that EVT approach is able to provide a convenient framework for asymmetric properties in both the lower and upper tails which implies that the risk and reward are not equally likely for the short- and long-trading positions in Malaysian stock market.
This article study the influences of structural break to the fractionally integrated time-varying volatility model in Malaysian stock markets from year 1996 to 2006. A fractionally integrated autoregressive conditional heteroscedastic (FIGARCH) model combines with sudden changes of volatility is develops to study the possibility of structural change in Asian financial crisis and currency crisis. Our empirical results evidence substantially reduction in long memory clustering volatility after the inclusion of sudden changes in the volatility. Finally, the estimation, diagnostic and model selection evaluations indicate that the fractionally integrated model with structural change is out-performed compared to the standard model.
Kajian ini memfokuskan penggunaan model kabur baru untuk pemilihan sistem pelupusan sisa pepejal perbandaran (SPP) yang dewasa ini dilihat semakin menghambat terutamanya negeri-negeri di bahagian tengah Semenanjung Malaysia. Rekod menunjukkan negeri Selangor dan Wilayah Persekutuan Kuala Lumpur (WPKL) mencatatkan penghasilan SPP tertinggi melebihi 2.32 juta tan setahun pada tahun 2005. Lazimnya, proses untuk menentukan sistem pelupusan yang sesuai melibatkan pengenalpastian matlamat dan kriteria berdasarkan pilihan yang ada. Ia juga bersifat pertimbangan multi-kriteria yang melibatkan banyak pihak berkepentingan dalam membuat keputusan. Berdasarkan permasalahan tersebut, model multi-kriteria dwikabur konflik diusulkan menggunakan konsep penegasan linguistik (i.i., dilasi dan konsentrasi) dalam proses hierarki analitik (AHP). Model ini diubahsuai menggunakan teori set baru yang diberi nama ‘set dwikabur konflik’. Kajian kes di negeri Selangor dan WPKL dimanfaatkan sepenuhnya untuk menunjukkan kesesuaian model yang diusulkan. Berdasarkan pengiraan yang ditunjukkan, model yang diusulkan dapat menilai kesemua kriteria secara lebih menyeluruh disebabkan sifat ‘timbal balas’ yang dimilikinya. Di samping itu, ia mampu menangani masalah yang bersifat berketaktentuan secara berkesan disebabkan pembuat keputusan boleh menilai secara linguistik sepenuhnya sekaligus memudahkan mereka membuat keputusan dengan lebih cekap dan berkesan.
Pembinaan model geometri berbantukan komputer (CAGD) dengan titik data yang mempunyai ketakpastian adalah sukar dan mencabar. Dalam kertas ini, pembinaan model splin-B kabur sebagai perwakilan matematik bagi lengkung dengan data ketakpastian menggunakan titik kawalan kabur dan titik kawalan penyahkaburan dibincangkan. Lengkung splin-B kabur atau splin-B penyahkaburan kubik untuk masalah data ketakpastian akan diperihalkan dengan menggunakan kaedah penghampiran splin-B kubik yang ditakrif menerusi titik kawalan kabur dan titik kawalan penyahkaburan. Bagi menyelesaikan masalah mengenai titik data ketakpastian pula, kaedah pengkaburan dan penyahkaburan titik data berkomponen kabur (penyahkaburan) beserta modelnya diperkenalkan. Bagi menguji tahap keberkesanan model, beberapa contoh lengkung simulasi data tersebut juga dibincangkan.
The Green Zone of Emergency Department Hospital Universiti Sains Malaysia (EDHUSM) which provides treatment for
non-critical cases contributes partly to the hustle and bustle in the emergency department. The imbalance of doctors
and nurses with the patient ratio which forms the resources’ bottleneck further results to the long patients’ waiting time
especially after the office hours and during weekends and public holidays. Collectively, this disproportion and bottlenecks
roots up the current problem faced by Green Zone EDHUSM which constantly fails to achieve the KPIs set by the hospital.
Henceforth, this study focuses on the best resource allocation of doctors and nurses for shifts during the weekdays and
for shifts during weekends and public holidays. The hybrid method of Discrete Event Simulation, and Data Envelopment
Analysis models such as BCC-input oriented and Super-Efficiency, were deployed to obtain the best resource allocation
for the two groups of shift. The method produced a series of resources allocation alternatives for doctors and nurses
with a total of 64 alternatives for weekdays and 729 alternatives for weekends and public holidays. The results show that
the best allocation for doctors and nurses during weekdays are three doctors and three nurses serving for every shift,
while during weekends and public holidays, a combination of four doctors and four nurses for every shift are the best.
The proposed combinations have reduced the average waiting time, optimized the utilization of doctors and nurses, and
managed to increase the number of patients served during weekdays, weekends and public holidays.
The increase in the amount of extracted silicon nanostructures resulting from the incorporation of sodium metasilicon salt in the etching solution was investigated. Silicon nanostructures were prepared in the form of thin fluorescent films via anodisation etching of silicon wafers in aqueous HF/H2O2 solution in the presence of the silicon-based salt. The quality of the fluorescent films was assessed using several nondestructive analytical techniques. The nanostructures produced were then extracted. The harvested nanostuctures were examined for quantitative elemental analysis using atomic absorption spectrophotometry. This investigation was limited to silicon nanostructures with size ≤ 200 nm. The results indicate that the incorporation of the silicate increased the yield of silicon nanostructures production significantly.
Onychomycosis is the infection of nail apparatus by dermatophytes, yeasts or non-dermatophyte moulds and is responsible for 50% of all nail disorders. A five year retrospective study was conducted at Universiti Kebangsaan Malaysia to identify the common pathogens responsible for onychomycosis and to describe the epidemiology of the affected patients. A total of 278 abnormal nails were cultured, out of which 231 were positive for fungus. Females constituted 50.2% (n=116) while males 49.8% (n=115). The majority (51.9%, n=120) were between ages 50-69 years. The Malay ethnic group was most commonly affected (44.2%, n=102) followed by Chinese (33.8%, n=78), Indians (18.2%, n=42) and other ethnic groups (3.8%, n=9). The most common fungal element isolated was non-dermatophyte moulds (45.4%, n=105) followed by yeast (34.6%, n=80) and dermatophytes (1.3%, n=3). Aspergillus spp. was the commonest (59.8%,n=81) non-dermatophyte mould, while Candida spp. was the commonest yeast (74.3%, n=89) isolated. In this study, non-dermatophyte moulds are the most common microorganisms implicated to cause onychomysosis. Treatment for non-dermatophyte mould is challenging as the current available antifungal agents are more effective against dermatophytes and yeasts.
We investigated the central mass distribution of the luminous infrared galaxy NGC 3256 at a distance of 35 Mpc by using
CO(1-0) observations of the Atacama Large Millimeter and sub-millimeter Array (ALMA) and near-IR data of the Two
Micron Sky Survey (2MASS). We found that there is a huge amount of invisible dynamical mass (4.48 × 1010 ) in the
central region of the galaxy. The invisible mass is likely caused by some dark matter, which might have a cuspy dark
matter profile. We note that this dark matter is difficult to explain with the conventional Modified Newtonian Dynamics
(MOND) model, which is only applicable at a low acceleration regime, whereas the acceleration at the central region
of the galaxy is relatively strong. Therefore, this discovery might pose a challenge to the conventional MOND models.
Corrosion caused by sulphate-reducing bacteria (SRB) isolated from seawater nearby to Pasir Gudang has been studied. The test coupon was a AISI 304 stainless steel. Potential and corrosion rate measurements were carried out in various types of culturing solutions, with SRB1, SRB2, combination of SRB1 & SRB2 and without SRBs inoculated (sterilized). From Tafel plots a higher corrosion rate has been found in medium inoculated with SRBs than that of the sterilized medium (control). When SRBs were present in the medium, the Tafel plot shifted towards more negative values (Ecorr was shifted to much less anodic values) and increase in current density compared to that of the sterilized medium (control). Localized corrosion was observed on the metal surface, and it was associated to the SRB activity. X-ray analysis (EDAX) showed that the corrosion product has higher content of sulphur for medium containing SRBs than that of the sterilized medium. X-Ray Diffraction analysis carried out on corrosion products which showed the presence of iron sulphide. This indicates the influence of the presence of SRB in corrosion process.
The aim of this study was to determine the surface chemistry during biocorrosion process on growth and on the production of exopolymeric substances (EPS) in batch cultures of mix-strains of marine sulphate-reducing bacteria (SRB) isolated from Malaysian Shipyard and Engineering Harbours, Pasir Gudang. The EPS and precipitates were analyzed by x-ray photoelectron spectroscopy (XPS). The XPS results indicate that Fe(2p3/2) spectrum for iron sulphide can be fitted with Fe(II) and Fe(III) components, both corresponding to Fe-S bond types. The absence of oxide oxygen in the O(1s) spectrum and Fe(III)-O bond types in the Fe(2p3/2) spectrum supports the conclusion that iron sulphides are composed of both ferric and ferrous iron coordinated with monosulphide and disulphide.
The corrosion potential of AISI 304 stainless steel coupons influenced by sulphate-reducing bacteria (SRB) has been studied. Pure colony of SRB was isolated from the Malaysia Marine and Heavy Engineering, Pasir Gudang, Johor. Open circuit potential measurements were carried out in variable types of culturing solutions with SRB1, SRB2, combination of SRB1 & SRB2 and without SRBs inoculated. Results showed that the corrosion potential, Eoc increased in the presence of SRBs (in pure and mixed culture) compared to that of control. EDS analysis showed the strong peak of sulphur in coupon containing SRB cultures compared to the control. ESEM data showed that the high density cell of SRBs were associated with corroding sections of surface steel comparing with non-corroding sections for coupons immersed in VMNI medium containing SRBs.
A cylindrical data set consists of circular and linear variables. We focus on developing an outlier detection procedure
for cylindrical regression model proposed by Johnson and Wehrly (1978) based on the k-nearest neighbour approach.
The procedure is applied based on the residuals where the distance between two residuals is measured by the Euclidean
distance. This procedure can be used to detect single or multiple outliers. Cut-off points of the test statistic are generated
and its performance is then evaluated via simulation. For illustration, we apply the test on the wind data set obtained
from the Malaysian Meteorological Department.
The lysosomal aspartic proteinase cathepsin D is an acute phase protein involved in various physiological processes, including vitellogenesis, yolk processing and immune responses. In this study, we characterised the cathepsin D from the Asian seabass Lates calcarifer and examined its expression profile during infection. The complete coding sequence of L. calcarifer cathepsin D consists of 1191 nucleotides, encoding a 396 amino acid protein molecule that is made up of a putative signal peptide, a leader peptide and a mature peptide. Phylogenetic analyses showed that two types of cathepsin D are present in the teleost lineage i.e. cathepsin D1 and D2, whereas higher vertebrates possess only one type of cathepsin D. L. calcarifer cathepsin D was clustered together with cathepsin D1 from other teleosts. Compared to mammalian sequences, L. calcarifer cathepsin D lacks the β-hairpin loop that forms the double chain and is present as a single chain peptide with conserved aspartic active sites like other fish. Both multiple sequence alignment and phylogenetic analysis indicated that the L. calcarifer cathepsin D sequence codes for cathepsin D1 and suggested that it shares the same functions with cathepsin D from other fish. Expression profiling analysis of cathepsin D in L. calcarifer infected with Aeromonas hydrophila showed that it is up-regulated in immune-related tissues such as gills, spleen and liver, suggesting that cathepsin D plays an important role in the innate immune response of L. calcarifer against pathogens.
In recent years, there has been considerable interest in simple sequence repeats (SSRs) particularly as molecular markers with applications in many different fields. We have carried out an effort to identify and analyse SSRs in the genome of the Asian seabass, Lates calcarifer by random sequencing. Genomic DNA was isolated from the muscle tissue of L. calcarifer, sheared by nebulisation and ligated into plasmid vector. Recombinant clones were selected randomly from the genomic libraries constructed. Subsequently, plasmid DNA was extracted and subjected to one-pass sequencing. A total of 4175 random sequences, also known as genome survey sequences (GSSs), with a total length of 1.7 Mb was generated. Screening of the whole L. calcarifer GSS data set allowed for the identification of a total of 151 perfect (100% similarity) SSRs. These SSR consensus patterns spread over a wide range of size (1 to 226 bp). The most frequent consensus pattern is dinucleotide, which represents 60% of all SSRs identified. The dinucleotides (AC)n, (AT)n and (AG)n were also found to occur frequently in the L. calcarifer genome. Sequence comparison between L. calcarifer and other fish species showed variation in repeat content, indicating the different ways in which repeats may evolve in the genome of these species. Data generated from this random sequencing of the L. calcarifer genome should serve as a valuable resource for further studies of this organism.
The existence of outliers in any type of data affects the estimation of models’ parameters. To date there are very few literatures on outlier detection tests in circular regression and it motivated us to propose simple techniques to detect any outliers. This paper considered the complex linear regression model to fit circular data. The complex residuals of complex linear regression model were expressed in two different ways in order to detect possible outliers. Numerical example of the wind direction data was used to illustrate the efficiency of proposed procedures. The results were very much in agreement with the results obtained by using the circular residuals of the simple regression model for circular variables.
Gentian optik polimer (P0F) mempunyai banyak kelebihan dan banyak digunakan untuk komunikasi terutamanya dalam industri automotif. Komunikasi ini memerlukan maklumat yang banyak dihantar pada satu masa dengan kos yang rendah. Untuk itu pencerai 3x3 POF yang berkonsepkan pemultipleks bahagi jarak gelombang (wDM) yang berkos rendah dan berteknologi hijau difabrikasikan. Pencerai POF ini difabrikasikan dengan menggunakan alat yang murah dan mudah didapati, iaitu tiub besi dan lilM. Teknik fabrikasi yang digunakan adalah dengan memanaskan tiga lembar POF sehingga bahagian tengahnya mencair dan melakur sehingga mengecil dan memanjang berdiameter 1 mm. Pencerai 3x3 POF yang berjaya difabrikasi dicirikan dengan mengukur kehilangan POF sebelum dan selepas hujungnya diratakan dan digilap dengan dua jenis kertas pasir yang berlainan darjah kekasaran. Ini untuk melihat kesan gilapan pada kehilangan isyarat optik. Kehilangan pencerai PoF juga diukur pada suhu yang berbeza bagi melihat kesannya pada prestasi pencerai POF. Berdasarkan keputusan yang diperoleh, dapat dilihat bahawa kebersihan dan kerataan hujung POF memberi kesan kepada kehilangan dengan penurunan antara 0.3 hingga 5.0 dB. Suhu juga memberi kesan kepada kehilangan isyarat POF, walaupun tidak begitu ketara, dengan purata peningkatan kehilangan sebanyak 0.3 dB. Walaupun secara keseluruhannya nilai kehilangan dalam pencerai POF yang difabrikasi ini masih tinggi, prestasi ini dapat diperbaiki dengan penambahbaikan pada teknik pelakuran dan penggunaan alat yang lebih berkualiti. Teknik pemfabrikasi berkos rendah ini dipercayai boleh menghasilkan pencerai POF yang murah secara komersil, tetapi dengan kajian yang lebih mendalam pada teknik pelakuran, punca kehilangan dan cara meminimumkan kehilangan boleh diperoleh dan meningkatkan isyarat optik keluaran.