Browse publications by year: 2009

  1. Abu Hassan Shaari Mohd Nor, Ahmad Shamiri, Zaidi Isa
    In this research we introduce an analyzing procedure using the Kullback-Leibler information criteria (KLIC) as a statistical tool to evaluate and compare the predictive abilities of possibly misspecified density forecast models. The main advantage of this statistical tool is that we use the censored likelihood functions to compute the tail minimum of the KLIC, to compare the performance of a density forecast models in the tails. Use of KLIC is practically attractive as well as convenient, given its equivalent of the widely used LR test. We include an illustrative simulation to compare a set of distributions, including symmetric and asymmetric distribution, and a family of GARCH volatility models. Our results on simulated data show that the choice of the conditional distribution appears to be a more dominant factor in determining the adequacy and accuracy (quality) of density forecasts than the choice of volatility model.
    MeSH terms: Biometry; Computers; Forecasting; Research; Volatilization; Likelihood Functions
  2. Ishak Hashim, Zailan Siri
    The linear stability theory is applied to investigate the effects of rotation and feedback control on the onset of steady and oscillatory thermocapillary convection in a horizontal fluid layer heated from below with a free-slip bottom. The thresholds and codimension-2 points for the onset of steady and oscillatory convection are determined. The effect of feedback control on the parameter space dividing the steady and oscillatory convection regions is demonstrated.
    MeSH terms: Feedback; Hot Temperature; Humans; Rotation; Convection; Physical Therapy Modalities
  3. Zaidi Che Cob, Aziz Arshad, Japar Sidik Bujang, Mazlan Abdul Ghaffar
    A total of 230 individuals of Strombus were sampled at various locations along the Johor Straits, Malaysia. There were four species of Strombus present in the study areas i.e. Strombus canarium Linnaeus, 1758; Strombus urceus Linnaeus, 1758; Strombus marginatus subspecies succinctus Linnaeus, 1767; Strombus marginatus subspecies robustus Sowerby, 1874; and Strombus vittatus subspecies vittatus Linnaeus, 1758. Strombus canarium was the most common, widely distributed and most abundant, followed by S. urceus, while the others were only rarely found. Among the species Strombus marginatus and Strombus vittatus were two new distribution records for the Johor Straits. Since all Strombus were traditionally harvested and consumed by the locals since long ago, further studies are needed particularly regarding the population dynamics and fishery of the harvested species.
    MeSH terms: Animals; Fisheries; Malaysia; Population Dynamics; Publications; Specimen Handling; Gastropoda
  4. Rosyidi S, Taha M, Ismail A, Chik Z
    Dalam hal yang berkaitan dengan pengurusan turapan jalan raya, keupayaan galas lapisan subgred banyak mempengaruhi keadaan struktur turapan secara keseluruhan. Oleh itu, penilaian kualiti subgred diperlukan dari masa ke masa bagi mengawal kualiti turapan supaya ianya boleh dilalui kenderaan tanpa mengalami kerosakan. Kaedah Analisis Spektrum Gelombang Permukaan (lebih dikenali dengan Spectral Analysis of Surface Wave-SASW) merupakan suatu teknik uji kaji seismos tanpa musnah di lapangan yang boleh digunakan untuk penilaian kekukuhan dan kedalaman struktur turapan jalan termasuk lapisan subgred turapan dengan cepat dan menjimatkan. Makalah ini bertujuan untuk menunjukkan keupayaan kaedah SASW bagi menilai kualiti lapisan subgred turapan. Kaedah SASW dilakukan berdasarkan kaedah perambatan gelombang R. Berasaskan data beza fasa gelombang R yang merambat di permukaan turapan, lengkung eksperimen serakan halaju fasa diperolehi. Selanjutnya melalui proses songsangan, parameter dinamik bahan seperti halaju ricih yang mewakili modulus elastik dan ricih dinamik bahan turapan jalan boleh ditentukan. Hasil kajian menunjukkan bahawa kaedah SASW berupaya menghasilkan parameter dinamik bahan lapisan subgred turapan yang boleh diguna pakai. Beberapa model empirik dengan korelasi yang baik berjaya diterbitkan daripada kajian ini yang boleh digunakan dengan mudah di lapangan untuk penilaian kekukuhan lapisan subgred secara tepat.
    MeSH terms: Azepines; Methylglycosides; Peptides; Thiocarbamates
  5. Ismail E, Abdul Razak S, Selamat L, Gurusamy R, Zariman H, Shahrudin MS, et al.
    Sains Malaysiana, 2009 6;38:947-952.
    Dermatoglyphic traits are formed under genetic control during early gestation and do not change through the entire life. A few studies have shown that dermatoglyphic traits were conservative in their evolution and were different between and within population groups. The objective of this study was to compare the variability of palm dermatoglyphs in three main populations i.e. Malay, Chinese, Indian and five sub-ethnic population of Negritos’ Orang Asli i.e. Bateq, Jahai, Kintak, Kensiu and Lanoh. We utilised fingerprints and palms of 390 healthy adult individuals, counted the total ridge for ten fingers
    (TRC), a-b ridge counts (a-b RC) on palms, examined widening of the atd-angle, and classified the digital pattern configuration of arches, whorls, ulnar, and radial loops for all fingers. Variables obtained from both palm did not show any differences between males and females for all populations. TRC, a-b RC and atd-angle were the highest for Kensiu and were later on specially described to be in a group of its own by ANOVA and TUKEY test for TRC and a-b RC. The same test has put Chinese in a group of its own for atd-angle. Only a-b RC clearly separate Orang Asli populations from the three main races. Whorls and ulnar loops were the most predominant pattern in all groups. Malays and Chinese had similar distributional patterns for each ten fingers. Indian and Jahai similarly mimic each other, while Bateq has the reversal pattern distribution to them both. Kintak and Lanoh halfly mimics each other pattern and Kensiu had its own unique pattern. In conclusion, races, patterns, and pattern frequencies were related to each other and can be used to differentiate different races or Orang Asli
    sub-ethnics. This study documents for the first time the comparative dermatoglyphic traits between Malaysian main races with Orang Asli populations show a list of informative variables that can be used to identify them as well as suggesting it’s used as a tool in tracing the etnohistorical background of populations.
    MeSH terms: Adult; China/ethnology; Dermatoglyphics*; Humans; India/ethnology; Malaysia; Malaysia/ethnology; Continental Population Groups
  6. Nurul-Yuziana Mohd-Yusof, Hoh CC, Adura Mohd-Adnan, Wan KL
    The Asian seabass (Lates calcarifer) is one of the most economically important aquaculture fish species in South East Asia. While the biology of the Asian seabass is widely studied, relatively little information is available at the molecular level. This lack of molecular information represents one obstacle to rapid progress in the study of immune responses particularly under aquaculture conditions. In light of this situation, we have undertaken an expressed sequence tag (EST) project on the Asian seabass spleen, the secondary lymphoid organ, for the identification of immune-related genes. A
    total of 2932 ESTs were generated and grouped into 1063 unique transcripts (UTs), which consisted of 104 consensi and 959 singletons. Of these, 51.3% (545/1063) matched to previously identified genes, while 48.7% (518/1063) showed no match. Of the 545 homologous UTs, 102 (9.6%) can be putatively identified as immune-related genes. The identification of the putative immune-related genes provides a meaningful framework in the effort to comprehend the Asian seabass immune system that may lead to an increase in the understanding of the defense mechanisms of and our abilities to
    manage this fish species.
    MeSH terms: Animals; Asia; Fishes; Perciformes; Spleen; Aquaculture; Expressed Sequence Tags
  7. Norazmir Md Nor, Ayub Mohd Yatim, Mamot Said
    Kajian ini dijalankan untuk menentukan kesan pemberian suplemen puri jambu batu merah (Psidium guajava) ke atas profil darah dan urin tikus teraruh hipertensi. Sebanyak 24 ekor tikus dibahagi 4 kumpulan (kawalan, CG (air suling); dos rendah, LDG (0.5 g/kg berat badan); dos sederhana, MDG (1.0 g/kg berat badan); dos tinggi, HDG (2.0 g/ kg berat badan). Tikus diberi puri jambu batu merah secara suap-paksa selama 28 hari dan diletakkan dalam sangkar individu. Berat organ dan profil lipid serum tidak berbeza secara signifikan antara kumpulan rawatan. Nilai glukosa darah (mmol/l) MDG (5.53±0.69) lebih tinggi secara signifikan berbanding CG (4.53±0.39) dan LDG (4.80±0.54). Tiada
    perbezaan signifikan pada status antioksida total, urea, fosfat alkali dan globulin antara kumpulan rawatan. Terdapat perbezaan signifikan pada hematologi darah, bilirubin total, gama-glutamil transpeptidase (GGT), protein total, albumin dan nisbah albumin:globulin antara CG dan kumpulan rawatan. Sel darah merah dan platlet bagi LDG (10.95±0.57×1012/l; 941.17±139.0 ×109/l) lebih tinggi berbanding CG (10.05±0.63 ×1012/l; 858.83±163.4 ×109/l) masing-masing. LDG (3.51 umol/l) mempunyai kepekatan bilirubin total lebih rendah berbanding CG (4.25 umol/l). Tahap GGT pula lebih
    tinggi pada HDG (8.67 U/l) berbanding CG dan MDG (7.00 U/l). Nisbah albumin:globulin lebih rendah pada CG (1.50) berbanding MDG (1.36) dan HDG (1.37). Julat pH urin dan kandungan urobilinogen dalam darah antara 7.3-8.0 dan 2.8-3.2 μmol/l masing-masing. Tiada kehadiran glukosa dan bilirubin pada semua urin kumpulan rawatan. Suplemen puri jambu batu merah (Psidium guajava) ke atas tikus SHR menunjukkan tiada kesan signifikan terhadap profil lipid serum, urin, berat organ dan tahap glukosa darah.
  8. Muhammad Marsudi, Dzuraidah Abdul Wahab, Lily Amelia, Che Hassan Che Haron
    Kertas ini membincangkan pembangunan suatu alat sokongan pembuat keputusan dalam mereka bentuk produk berasaskan teori baris-gilir yang dikaitkan dengan maklumat masa kitar pembuatan. Dengan penggunaan alat sokongan ini, kesan reka bentuk sesuatu produk terhadap parameter kapasiti dan masa kitar pembuatan sesuatu sistem pembuatan sedia ada dapat ditentukan. Aplikasi alat sokongan ini membolehkan kumpulan pembangunan produk membangunkan produk sebenar pada masa yang singkat, meminimumkan kos pembangunan serta mengurangkan keperluan untuk mereka
    bentuk semula produk. Alat sokongan ini telah diaplikasikan pada sebuah industri automotif tempatan dan hasil kajian menunjukkan bahawa alat sokongan tersebut telah berjaya melakukan analisis masa kitar dan tahap penggunaan pada sistem pembuatan sedia ada. Pada jumlah keluaran 44 komponen/jam dan saiz sesekumpul 80, hasil analisis menunjukkan tahap penggunaan pada 98% dengan masa kitar 17.8 jam bagi pemprosesan gabungan produk yang terdiri daripada komponen dengan reka bentuk baru dan reka bentuk sedia ada.
    MeSH terms: Methylglycosides; Tetrahydroisoquinolines
  9. Zulkifli Mohamed, Omar Samat, Daud Mohamad
    Stock market investing is undoubtedly challenging. Investors have to deal with random, vague and ambiguity stock price volatility before embarking on investment decision. Due to these weaknesses, the conventional model has several limitations; as a result investors are demanding for a new robust model which is able to represent their real situation to solve the uncertainty issues. In this study we developed a new fuzzy portfolio selection model using semi-variance as a risk measure integrates with investor’s judgment on assets’ future performance. Linear programming approach was used to optimize the portfolio risk and return. Empirical data showed that the model were able to derive a resourceful portfolio compared to the naïve portfolio selection.
  10. Ganji BA, Burhanuddin Yeop Majlis
    In this paper, a deep-reactive ion etching (DRIE) process for fabricating microelectromechanical system (MEMS) silicon trenches with a depth of more than 250 μm is described. The DRIE was produced in oxygen-added sulfur hexafluoride (SF6) plasma, with sample cooling to cryogenic temperature using a Plasmalab System 100 ICP 180 at different RF powers. A series of experiments were performed to determine the etch rate and selectivity of some masking materials such as resists
    and metal (Al). Experiments showed that different materials have different etch rates, but for the Al mask, an etch rate of 5.44 × 10-3 nm/min was achieved, that exhibited stronger resistance against RIE than photo resists. By controlling the major parameters for plasma etch, an etch rate of 2.85 microns per minute for silicon and a high selectivity of 5.24 × 105 to the Al etch mask have been obtained. A 90 min etching experiments using etching gas SF6 of 60 standard cubic centimeters per minutes (sccm) with oxygen (13 sccm) were performed by supplying RF power of 5 W to an ICP of 600 watts, and silicon etching process with a depth of 257 μm was demonstrated. Our experiments showed that Al is the best mask material for very deep trenches in silicon.
  11. Khairul Rijal Jamaludin, Norhamidi Muhammad, Mohd Nizam Ab. Rahman, Murtadhahadi, Sri Yulis M. Amin, Sufizar Ahmad, et al.
    Proses penyahikatan pelarut telah diterima dengan meluas dalam proses pengacuanan suntikan logam (MIM) berdasarkan kemampuannya meningkatkan proses penyahikatan. Bahan pengikat boleh larut yang dikeluarkan dari jasad anum akan menghasilkan liang-liang yang akan membantu meningkatkan kadar penyahikatan terma. Kertas ini membentangkan pengoptimuman proses penyahikatan pelarut dengan menggunakan kaedah Taguchi. Pengaruh pembolehubah penyahikatan pelarut seperti suhu pelarut, taburan saiz partikel, beban serbuk dan tekanan penyuntikan juga dibincangkan. Dua jenis serbuk SS316L digunakan dalam kajian ini iaitu serbuk pengatoman gas dan pengatoman air. Kajian ini mendapati bahawa suhu pelarut memainkan peranan yang sangat penting dalam proses penyahikatan
    pelarut dan menyumbang sebanyak 91.602% (bagi serbuk pengatoman gas) dan 84.978% (bagi serbuk pengatoman air) terhadap kadar pengeluaran bahan pengikat. Bagaimanapun, taburan saiz partikel serbuk hanya menyumbangkan sebanyak 6.638% dan 12.228% bagi serbuk pengatoman gas dan pengatoman air masing-masing terhadap kadar pengeluaran bahan pengikat. Suhu pelarut menunjukkan tahap signifikan yang sangat tinggi iaitu α = 0.005 bagi kedua-dua jenis serbuk tersebut. Walau bagaimanapun, taburan saiz partikel serbuk SS316L menunjukkan tahap signifikan yang sederhana iaitu α = 0.025 dan α = 0.01 bagi kedua-dua padatan serbuk tersebut.
  12. Ali Ahmadzadeh, Sarani Zakaria, Maisarah Yusoff
    The liquefaction of oil palm empty fruit bunch (EFB) in phenol was carried out in the presence of sulfuric acid as a catalyst in the reflux condenser system. The effect of initial phenol input and EFB on liquefaction reaction was investigated by measuring the reaction yield, EFB residue and combined phenol. The initial ratio of phenol to EFB has the greatest influence on the residue and reaction yield. The liquefaction products consist of some liquid by products with high amount of OH groups. The amount of this byproduct is 0.5 time of the solid product (phenolic resin).
    MeSH terms: Formaldehyde; Fruit; Phenols; Polymers; Sulfuric Acids; Phenol
  13. Amirah Ahmad, Mohamed Rozali Othman
    The electrooxidation of propionaldehyde and butyraldehyde on a gold electrode was studied by cyclic voltammetry in alkaline media. Electrooxidation of both aldehydes showed the appearance of two anodic peaks. Another oxidation peak on a newly generated electrode surface was observed after the corresponding reduction peak for both aldehydes.
    MeSH terms: Aldehydes; Electrodes; Gold; Oxidation-Reduction
  14. Asnuzilawati Asari, Hayes CJ
    A synthetic route towards the synthesis of TAN1251B was developed utilizing an alkylidene carbene insertion reaction as a key step to construct the quartenary centre. The α-hydroxylation of the 5,6-spirocyclic enone with iodosobenzene was successful to give a mixture of diastereomer compounds 20 and 21 in 1:1.2 ratios.
  15. Huang N, Radiman S, Chia C, Lim H, Khiew P, Chiu W, et al.
    Kobalt sulfida telah dihasilkan dengan kaedah pemendakan kimia di dalam kehadiran 0.1% ester sukrosa S1670s. Corak pembelauan sinar-x (XRD) menunjukkan kobalt sulfida yang dihasilkan mempunyai sifat amofos dan analisis sinar-x (EDX) menunjukkan kobalt sulfida yang terbentuk mempunyai nisbah atom Co: S dalam 1:1.08 iaitu CoS. CoS yang terbentuk mempunyai struktur liang bersaiz nano (~10 nm) apabila diperhatikan di bawah elektron mikroskop transmisi (TEM) dan disahkan oleh ujian penjerapan gas nitrogen (BET). Pembentukan struktur liang adalah disebabkan oleh struktur misel ester sukrosa yang mempunyai saiz misel dalam lingkungan 10 nm. CoS yang dihasilkan diuji keupayaan penjerapan dengan metilena biru sebagai sampel pewarna. Didapati keupayaan penjerapan optimum CoS ialah 110 mg/g dan pH yang paling sesuai untuk penjerapan berlaku adalah lebih daripada 6.
    MeSH terms: Anesthetics; Color; Esters; Nitrogen; Pallor
  16. Noorashrina A. Hamid, Andanastuti Muchtar, Wan Ramli Wan Daud, Norhamidi Muhamad
    Oksida perovskit La1-xSrxCo0.2Fe0.8O3-δ (LSCF) dengan x = 0.3-0.5 telah dihasilkan melalui kaedah sol-gel. Ia merupakan pengalir berion campuran yang sangat baik sebagai bahan katod untuk sel fuel oksida pepejal bersuhu sederhana (IT-SOFC). Serbuk yang terhasil dicirikan dengan menggunakan teknik pembelauan sinar-X (XRD) dan keputusannya menunjukkan bahawa hablur perovskit yang tulen terhasil sepenuhnya setelah dikalsin pada suhu 900°C. Kesan suhu pensinteran ke atas pelet LSCF dikenal pasti dengan menggunakan Mikroskop Elektron Imbasan (SEM). Keputusan menunjukkan
    bahawa perovskit LSCF mempunyai keliangan yang optimum sebanyak 30% setelah disinter pada suhu 900°C. Keliangan optimum ini membolehkan tindak balas penurunan oksigen berlaku dengan lebih mudah. Analisis FTIR yang dijalankan menunjukkan kehadiran ikatan Fe-O dalam serbuk LSCF dan tiada bendasing yang wujud dalam serbuk LSCF.
  17. Mohamed M. GahGah, Juhari Mat Akhir, Abdul Ghani M. Rafek, Ibrahim Abdullah
    Sains Malaysiana, 2009;38(6):827-833.
    The aim of this study is to investigate the factors that cause landslides in the area along the new road between Cameron Highlands and Gua Musang. Landslide factors such as lineaments have been extracted from remote sensing data (Landsat TM image) using ERDAS software. A soil map has been produced using field work and laboratory analysis, and the lithology, roads, drainage pattern and rainfall have been digitized using ILWIS software together with the slope angle and elevation from the Digital Elevation Model (DEM). All these parameters, which are vital for landslide hazard assessment, have been integrated into the geographical information system (GIS) for further data processing. Weightage for these landslide relevant factors related to their influence in landslide occurrence using the heuristic method has been carried out. The results from this combination through a modified ‘index overlay with multi class maps’ model was used to produce a landslide hazard zonation map. Five classes of potential landslide hazard have been derived as the following: very low hazard zone 17.27%, low hazard zone 39.35%, medium hazard zone 25.1%, high hazard zone 15.35% and very high hazard zone 2.93%. The results from this work have been checked through the landslide inventory using available aerial photos interpretation and field work, and show that the slope and elevation have the most direct affect on landslide occurrence.
    MeSH terms: Heuristics; Body Fluids; City Planning; Drainage; Laboratories; Software; Soil; Geographic Information Systems; Landslides; Remote Sensing Technology
  18. Zaidi Che Cob, Mazlan Abd. Ghaffar, Aziz Arshad, Japar Sidik Bujang
    The study was conducted at Merambong Shoal (01°19.979’N, 103°35.965’E) in the Sungai Pulai estuary, Johor Straits, Malaysia from January to December 2005. Standing biomass of male and female Strombus canarium sub populations was calculated monthly based on the abundance value of each cohort and on the length-weight relationship. Secondary production was estimated using increment summation method, upon recognition of cohorts following the size-frequency distribution analysis using Bhattacharya and Hasselblad’s NORMSEP methods. Monthly variations in standing biomass
    (B) and production (P) showed higher values during the wet season compared to dry season, which indicate seasonal variations. Total production (P) was estimated at 0.14 gAFDWm-2yr-1 and 0.45 gAFDWm-2yr-1, while the annual mean population biomass was estimated at 0.13 gAFDWm-2 and 0.26 gAFDWm-2, for males and females, respectively. The P/ ratio was therefore calculated at 1.08 yr-1 for male and 1.73 yr-1 for female, which was within the values reported for other gastropod species. Estimates using empirical methods commonly used in secondary production studies found
    that none could be applied to the species. Considering the large amount of time, effort and resources involved in the conventional production estimation method, more studies are needed to establish a reliable production estimates for S. canarium, and possibly other gastropod species within the tropical region.
  19. Idris A, Ismail S, Haron Y, Suhana Y
    A preliminary study on selected insect communities of Tasik Chini was conducted from 27th May to 2nd June 2004 along three trails namely trail to Sg. Gumum, trail to Kampung Melai and trail to old tin mining area. A total of eight Malaise traps were installed along the trail to Sg. Gumum while sweeping net and 10 yellow pan traps per trail were used to sample insects along the other two trails. A total of 502 insect individuals consisting of eight orders and 46 families were successfully collected. Of these, the hymenopterans (ants and wasps) had the most number (298 individuals and 11 families) while the Blattaria was the least number (six individuals and two families). Of the hymenopterans, the ichneumonids had the most individuals collected (52) followed by evaniid (50) and vespid wasps (41). For the Coleopterans, Cleridae were the most collected (26) during this short study followed by Anthribidae (13). There were 62 of individuals Odonata consisting of 9 species identified.
    MeSH terms: Animals; Ants; Cockroaches; Mining; Quinolines; Tin; Wasps; Odonata
  20. Ahmad Zaharin Aris, Mohd Harun Abdullah, Praveena SM
    Groundwater is the prime source of freshwater in most small islands. A detailed groundwater and seawater chemistry study was undertaken from March 2006 to January 2007 to examine the evolution of groundwater in the shallow aquifer of Manukan Island, Sabah, Malaysia. Coastal groundwater aquifers especially for small islands are often exposed to heavy pumping and consequently to risks of seawater intrusion. Major ion chemistry analysis showed that the groundwater quality of the island experienced changes attributed to seawater intrusion. The groundwater has undergone a compositional change from Ca-rich to Na-rich which can be explained mostly by simple mixing process and cation exchange process. From the PHREEQC simulation model, calcite, dolomite and aragonite solubility showed positive mean values (0.65; 1.11; 0.51, respectively) of the saturation indices (SI) indicating supersaturation which attributed from the simple mixing and eventually cation exchange process. This information is important in protecting and remediating the disturbed aquifer situation.
    MeSH terms: Calcium Carbonate; Cations; Fresh Water; Magnesium; Malaysia; Seawater; Solubility; Groundwater; Islands
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