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.
MeSH terms: Forecasting; Risk; Volatilization; Advance Directives; Empirical Research
Dalam makalah ini, masalah aliran genangan dalam bendalir mikrokutub terhadap permukaan mencancang yang telap dengan fluks haba boleh ubah dipertimbangkan. Dengan menggunakan penjelmaan keserupaan, persamaan asas yang menakluk aliran bendalir dan pemindahan haba dijelmakan kepada satu set persamaan perbezaan biasa. Persamaan yang dijelmakan tertakluk kepada syarat-syarat sempadan yang berkaitan kemudiannya diselesaikan secara berangka menggunakan kaedah tembakan. Kesan parameter sedutan/semburan fw ke atas profil halaju dan suhu serta pekali geseran kulit dan nombor Nusselt setempat diperoleh dan dibincangkan. Keputusan berangka menunjukkan bahawa penyelesaian dual wujud dalam kedua-dua aliran membantu dan aliran menentang.
Total polyphenol content and free radical scavenging activity of cornsilk (Zea mays hairs) extracts were determined. Our result showed the total polyphenol content of methanolic and water extracts were 272.81 mgGAE/100 g and 256.36 mgGAE/100 mg dry plant, respectively. The total flavanoid content of methanolic extract (38.01 mg catechin equivalent/100 g) was significantly higher (p<0.05) than the water extract (4.11 mg catechin equivalent/100 g). In radical scavenging activity, the activity of methanolic extract was significantly higher (p<0.05) than the water extract. The methanolic extract scavenged at 81.7% of free radicals at 1000 μg/mL while the water extract showed 63.5% of inhibition. In conclusion, cornsilk contained high polyphenol components with strong free radical scavenging activity thus could be considered as potential source of natural antioxidant.
Biosurfactants are microbially produced surface active agents that offer better biodegradability and lower toxicity than chemically synthesized surfactants because of their biogenetic origin. One of the most surface-active biosurfactants known is surfactin, a cyclic lipopeptide produced by various strains of Bacillus subtilis. In this study, the cleaning potential of surfactin on ultrafiltration (UF) membranes fouled with BSA was studied using centrifugal UF devices of 50 kDa and 100 kDa MWCO polyethersulfone (PES) membranes. Mechanisms of bovine serum albumin (BSA) displacement by surfactin on fouled UF membranes were studied using dynamic light scattering (DLS) technique and surface tension measurements. Hydrodynamic diameter and surface tension measurements of BSA-surfactin mixtures showed that the surfactin was efficient in displacing BSA fouled on UF membranes due to strong electrostatic repulsive interactions involved at pH8.5. This study demonstrated that surfactin can be used to effectively clean fouled UF membranes.
The steady laminar combined convective flow with heat and mass transfer of a Newtonian viscous incompressible fluid over a permeable flat plate with linear hydrodynamic and thermal slips has been investigated numerically. The velocity of the external flow, the suction/injection velocity and the temperature of the plate surface are assumed to vary nonlinearly following the power law with the distance along the plate from the origin. Lie group analysis is used to develop the similarity transformations and the governing momentum, the energy conservation and the mass conservation equations are converted to a system of coupled nonlinear ordinary differential equations with the associated boundary conditions. The resulting equations are solved numerically using the Runge-Kutta-Fehlberg fourth-fifth order numerical method. The effects of hydrodynamic slip parameter (a), thermal slip parameter (b), suction/injection parameter (fw), power law parameter (m), buoyancy ratio parameter (N), Prandtl number (Pr) and Schmidt number (Sc) on the fluid flow, heat transfer and mass transfer characteristics are investigated and presented graphically. We have also shown the effects of the Reynolds number (Re) and the power law parameter (m) on the velocity slip and the thermal slip factors. Good agreement is found between the numerical results of the present paper and published results.
Satu model matematik dibina bagi menilai pengurusan aktiviti pelancongan rekreasi di Wetland Putrajaya. Kajian ini menggunakan kaedah pengaturcaraan gol (PaG) dan perisian LINDO 6.1.untuk menyelesaikan masalah pelbagai objektif bagi memaksimumkan anggaran keuntungan aktiviti dan bilangan peserta yang terlibat. Tujuh aktiviti di Wetland Putrajaya yang terletak di bawah pengurusan Perbadanan Putrajaya telah dipilih sebagai kes kajian. Data dan maklumat rekod tahun 2008 dijadikan sebagai anggaran untuk kos dan bilangan peserta. Hasil kajian mendapati pihak Wetland Putrajaya boleh mencapai keuntungan lebih 40% daripada jumlah kos dan matlamat untuk memaksimumkan bilangan peserta bagi aktiviti yang terlibat juga tercapai.
Primary cells have a limited proliferative capacity with a finite number of times as compared with cell line which can grow indefinitely. Therefore, this study was carried out to identify the proliferative capacity of primary mononucleated cells from mouse and human. The mononucleated cells were isolated from mouse and human peripheral blood by density gradient centrifugation using Ficoll-Paque™ Plus. The two types of cells i.e. suspension and adherent forms were obtained after culturing the isolated mononucleated cells for 4 days in the complete medium consists of Alpha Minimal Essential Medium, 10% newborn calf serum and 2% penicillin/streptomycin. The cells were then cultured for another 10 days to observe cell viability using trypan blue exclusion assay (suspension form) and MTT assay (adherent form). NSO and MC3T3-E1 cell lines were selected as control cell for suspension and adherent cells, respectively. Our results showed that the proliferation rate of mouse suspension mononucleated cells increased from 1.31 ± 0.24 cells/day (day 5) to 2.69 ± 0.42 cells/day (day 10) whilst, for human suspension cells, the proliferation rate slightly increased
from 0.56 ± 0.20 cells/day (day 5) to 0.76 ± 0.29 cells/day (day 10). However, the proliferation rate of mouse adherent mononucleated cells decreased from 0.23 ± 0.02 cells/day (day 5) to 0.17 ± 0.01 cells/day (day 10). Meanwhile, human adherent cells maintained proliferation rate at approximately 0.67 ± 0.18 cells/day. In conclusion, adherent primary mononucleated cells from both mouse and human have limited capacity to generate more cells in vitro as compared with suspension mononucleated cells.
entamoeba histolytica dan/atau entamoeba dispar merupakan protozoa usus yang mempunyai prevalens infeksi yang tinggi dalam kalangan masyarakat pedalaman terutamanya masyarakat Orang Asli. Ia tersebar secara meluas di kawasan tropika dan subtropika serta di negara membangun berbanding negara maju. Sebanyak 111 sampel feses kanak-kanak Orang Asli daripada suku kaum Jahai telah diterima dan disaring untuk entamoeba histolytica dan/atau entamoeba dispar menggunakan kaedah apusan langsung yang memberi hasil positif terhadap 43 sampel atau 38.7%. Oleh sebab amaun sampel yang diterima adalah sedikit, hanya 66 sampel feses sahaja yang dapat diperiksa menggunakan tiga jenis teknik diagnostik berbeza iaitu apusan langsung, kepekatan formalin-eter dan pewarnaan trikrom. Hasil kajian mendapati, prevalens yang tinggi bagi infeksi entamoeba histolytica dan/atau entamoeba dispar iaitu 50% menggunakan
ketiga-tiga teknik diagnosis. Prevalens infeksi yang tinggi juga turut ditunjukkan pada kanak-kanak perempuan iaitu 62.5% berbanding kanak-kanak lelaki 30.8% (p<0.05). Selain itu, daripada segi umur, kanak-kanak yang berumur 7-9 tahun adalah lebih terdedah kepada infeksi entamoeba histolytica dan/atau entamoeba dispar dengan prevalens 60.7% (p>0.05). Teknik pewarnaan trikrom menunjukkan pengesanan 100% ke atas infeksi entamoeba histolytica dan/atau entamoeba dispar, diikuti teknik kepekatan formalin-eter 78.8% dan apusan langsung 72.7%. Prevalens infeksi entamoeba histolytica dan/atau entamoeba dispar yang tinggi dalam kalangan kanak-kanak Orang Asli di Pos Sungai Rual ini berhubungkait dengan pelbagai faktor iaitu status sosioekonomi yang rendah, kekurangan pengetahuan tentang penjagaan kesihatan serta kebersihan diri yang rendah. Peningkatan prevalens infeksi dalam kajian ini juga menunjukkan pentingnya penggunaan teknik diagnostik yang lebih berkesan dalam pemeriksaan rutin bagi mendapatkan hasil diagnosis yang lebih tepat.
Kaedah pemarkahan dan penggredan sering dibincangkan dalam aspek penilaian pelajar. Kertas kerja ini bertujuan untuk membincangkan kaedah pemarkahan dan penggredan menggunakan persentil taburan markah. Kaedah pemarkahan dengan menggunakan min dan songsangan varians markah bagi setiap soalan dalam suatu peperiksaan sebagai pemberat kepada soalan berkenaan dibincangkan. Dalam membincangkan penggredan menggunakan persentil taburan markah, persentil boleh ditentukan dengan menganggar taburan bagi markah peperiksaan. Penganggaran dan penentuan persentil bagi dua taburan iaitu taburan normal dan taburan gamma digunakan. Perbandingan dilakukan terhadap keputusan bagi beberapa senario yang diperoleh. Keputusan menunjukkan bahawa kaedah pemarkahan berpemberat yang menggunakan pemberat yang berasaskan kepada tahap kesukaran soalan boleh digunakan untuk mernghasilkan peringkat gred yang lebih jelas dalam kalangan pelajar.
MeSH terms: Autonomic Nervous System Diseases; Diabetic Neuropathies; Gamma Rays
Atomic force microscopy (AFM) lithography was applied to produce nanoscale pattern for silicon nanowire transistor fabrication. This technique takes advantage of imaging facility of AFM and the ability of probe movement controlling over the sample surface to create nanopatterns. A conductive AFM tip was used to grow the silicon oxide nanopatterns on silicon on insulator (SOI) wafer. The applied tip-sample voltage and writing speed were well controlled in order to form pre-designed silicon oxide nanowire transistor structures. The effect of tetra methyl ammonium hydroxide (TMAH) etching duration on the oxide covered silicon nanowire transistor structure has been investigated. A completed silicon nanowire transistor was obtained by removing the oxide layer via hydrofluoric acid etching process. The fabricated silicon nanowire transistor consists of a silicon nanowire that acts as a channel with source and drain pads. A lateral gate pad with a nanowire head was fabricated very close to the channel in the formation of transistor structures.
A molecular dynamics (MD) modeling method was applied to investigate the properties of carbon nanotube-based gears (CNT gears). The Brenner’s reactive hydrocarbon potential was used in order to calculate the short range interatomic forces. The Lennard-Jones 6-12 (LJ) was used to calculate the long range van der Waals potential for intermolecular interactions between gears. One gear was powered by forcing the atoms near the end of the first CNT to rotate, and a second gear was allowed to rotate by keeping the atoms near the end of second CNT constrained to a cylinder. We used the hybrid minimization to simulate the CNT-gears by coupling the unconstraint conjugate gradient minimization with the one-dimensional minimization, Brent’s method. The hybrid minimization was successfully implemented by introducing two regions in CNT gear. The switch function will affect the smoothness of the gear rotation. The switch function also affects the minimization process where simulation time will be reduced.
This study was conducted to retrieve the land surface temperature (LST) from Landsat ETM+ data for Al Qassim, Saudi Arabia. The proposed technique employed a mono window LST algorithm for retrieving surface temperature from Landsat ETM+. The land surface emissivity and solar angle values were needed in order to apply these in the proposed algorithm. The surface emissivity values were computed based on the NDVI values. The LST values derived from ATCOR2_T in the PCI Geomatica image processing software was used for algorithm calibration. The results showed a high correlation
coefficient (R) and low root-mean-square error (RMS) between the LST values retrieved from the proposed algorithm and ATCOR2_T. This study indicated that the proposed algorithm is capable of retrieving accurate LST values and the derived information can be used in the environmental impact assessment for Al Qassim area.
Clinical education provides students with opportunities to integrate knowledge and skills at progressively higher levels of performance. This study determined the significant events that undergraduate physiotherapy student reflects on during their clinical experiences as they learn to become a physiotherapist. A qualitative study using reflective instruments of structured debriefing sessions and diary writing was carried out. This involves 25 fourth-year students from the Faculty
of Health Sciences, UKM during their 12 weeks of clinical placements in 3 different modules (first semester). They were required to describe an event, its value and their reaction to it, and to discuss the effect of the new learning experience and how it would influence their respond in the future. Our findings confirmed that the process of writing a diary makes a considerable impact to the student experience during clinical placement. The subjects begin to construct a personal identity of becoming a physiotherapist through the process of developing confidence, confirmation of practices and assimilating of knowledge. In conclusion, the main themes generated from a reflective diary included their reflection of personal growth, on how they learnt in a clinical setting, and on the ethical and professional behaviors of themselves and colleagues. This provides the clinical educators with valuable information to design meaningful clinical learning experiences that would assist students to become a good physiotherapist for the future.
The South China Sea (SCS) circulation in its southern region in the area between Peninsular Malaysia and East Malaysia was studied from the OCCAM (Ocean Circulation and Climate Advanced Modelling). This research aimed to illustrate the general overview of the seasonal surface current circulation and the surface temperature profile which are lacking in the region. The current along the Malaysia coast flows northward in the southwest monsoon and move in opposite direction in northeast monsoon with the maximum speed of 0.4 m/s and 1 m/s, respectively. While the current flows southward, the cooler water is transported into the region which reduces the temperature at the central of the basins nearly 3 °C. The study manages to analyse the importance of the monsoonal system on the region circulation and temperature distribution.
Bukit Perangin Forest Reserve, Kedah Malaysia is a popular forest park well known for its clear rivers and streams, interesting sedimentary rock formations and a rich biodiversity in flora and fauna. However to date no report on the amphibians and reptiles of this forest has ever been published. Therefore, from January 2009 to May 2010, herpetofauna surveys were conducted at Bukit Wang Recreational Forest, which forms a part of the Bukit Perangin Forest Reserve. The results of the survey showed that a total of 15 species of amphibians belonging to 6 families and 15 species of reptiles
belonging to 7 families were found in the study area. These constitute the first records for the amphibians and reptiles in this forest. The herpetofauna checklist showed that the most abundant amphibians were from the family Ranidae while the most abundant reptiles were from the family Gekkonidae.
Biomonitor Multispesies Air Tawar (MFB™) digunakan bagi mengukur dan menganalisis pelbagai kelakuan daripada pelbagai jenis organisma akuatik untuk memantau kualiti air dalam ekosistem air tawar. Isyarat gerak balas udang air tawar (Macrobrachium lanchesteri) dan ikan gapi (Poecilia reticulata) dikaji di dalam makmal bagi menentukan respons yang spesifik terhadap pendedahan kepekatan air larut resap yang berbeza (1%, 3% dan 5%) bagi kedua-dua organisma. Perubahan perilaku organisma (pergerakan dan ventilasi) direkodkan dengan menggunakan Biomonitor Multispesies Air Tawar (MFB) selama 24 jam. Hasil yang diperoleh menunjukkan terdapat trend peningkatan respons pergerakan dan ventilasi yang jelas dengan peningkatan kepekatan pendedahan air larut resap bagi udang air tawar. Manakala respons yang ditunjukkan oleh ikan gapi adalah tidak begitu jelas walaupun terdapat trend pengurangan pergerakan dengan peningkatan kepekatan pendedahan air larut resap dan trend peningkatan ventilasi dengan peningkatan kepekatan pendedahan. Kajian ini menunjukkan M. lanchesteri memberikan respons yang lebih sensitif kepada air larut resap berbanding P. reticulata dan organisma ini lebih sesuai digunakan sebagai organisma penunjuk untuk MFB.
Sembilan aktinomiset endofit telah berjaya dipencilkan daripada pokok yang mempunyai nilai ubatan dari beberapa tempat di Semenanjung Malaysia. Pencilan tersebut telah dikenalpasti melalui pemerhatian morfologi, amplifikasi gen 16S rRNA dan analisis penjujukan 16S rRNA. Saringan awal terhadap aktiviti antimikrob telah dilakukan dengan menggunakan teknik calitan plat. Pembentukan miselium substrat dan aerial, warna jisim spora, pigmen larut dan morfologi rantai spora pada semua pencilan menyerupai Streptomyces sp. dan Microbispora sp. Analisis filogenetik jujukan separa 16S rRNA mendapati pencilan SUK 08, SUK 10 dan SUK 15 saling berkaitan dengan Streptomyceseurythermus ATCC 14975T. Walau bagaimanapun pencilan ini telah dipencilkan dari tumbuhan yang berbeza. Pencilan ini didapati mempunyai aktiviti antimikrob terhadap bakteria dan kulat kajian. Empat pencilan aktif iaitu SUK 08, SUK10, SUK 12 dan SUK 15 berupaya untuk membunuh dan merencat sehingga 100% satu atau lebih organisma patogen seperti Bacillus subtilis, Aspergillus fumigatus, Aspergillus niger, Fusarium solani, Rhizoctonia solani dan Trichoderma viride. Kajian ini mengesahkan bahawa tumbuhan etnoperubatan adalah sumber pencarian aktinomiset endofit bioaktif yang berupaya menjadi sumber novel dalam pencarian agen antibakteria dan antimikotik.
An inventory of orchid species diversity was carried out in cloud forest of Genting Highlands, which is one of the most developed highland areas in Peninsular Malaysia. Since 1967, construction of roads and hotel complexes has had a serious impact on its physical environment and vegetation. Habitat destructions together with climate change might have caused some orchid species to be extirpated locally or extinct. The cloud forest of Genting Highlands consists of four major peaks, Gunung Ulu Kali, Gunung Chin Chin, Gunung Lari Tembakau and Gunung Mengkuang. However, not much study on orchid diversity was conducted in these areas, therefore, this study is timely and essential to evaluate the current orchid diversity after a gap of three decades. Combined findings from the current study, previous published works and specimens deposited in local herbaria, including those at the Universiti Malaya, Universiti Kebangsaan Malaysia, Forest Researh Institute of Malaysia and Biology Department, Faculty of Science, Universiti Putra Malaysia and Singapore Botanic Gardens, an updated list of orchid species found in the cloud forests of Genting Highlands is presented. A total of 134 orchid taxa were recorded, comprised of 51 genera, 132 species, 1 subspecies and 2 varieties, of which 46 are new records to Genting Highlands. Hymenorchis javanica, a species previously reported as endemic to West Jawa was recently discovered in Gunung Ulu Kali. Thirty-three species discovered during this study are currently classified as endemic to Peninsular Malaysia, of which 20 are endemic to Pahang, Perak and Selangor and a very narrowly endemic species; Corybas villosus to Gunung Ulu Kali. Through our observations, most of the orchid species in Gunung Ulu Kali are very susceptible to disappearance due to loss of habitat and local climate change. An assessment of conservation status according to IUCN criterion revealed that 47 orchid taxa from Gunung Ulu Kali were threatened with extinction. Conservation actions were suggested to conserve the orchid diversity in the cloud forest areas of Genting Highlands.
The use of conventional fingerprint powder is the easiest and fastest method for fingerprint development. It is also the workhorse at the crime scene and an important method used in the laboratory. The objective of this study was to examine the difference in physical characteristics of the fingerprint after development using different fingerprint powders within a six-week period. The study compared the number of positives identifications of each ‘minutiae’ after application of black fingerprint powder and black magnetic fingerprint powder. The latent fingerprints from the donor were deposited on clean microscope slides. The following prints were applied after thirty minutes. Similar rules of pressure and length of deposition were made as much as possible. The slides were analyzed every week at similar intervals for six continuous weeks with black fingerprint powder and black magnetic fingerprint powder with specific indicator. The black fingerprint powder can be used for three weeks while black magnetic powder can up to fourth weeks. The results gave information on an effective time frame using both fingerprint powders for fingerprint development.
Ferit NiZn dan nanotiub karbon diadunkan ke dalam getah asli termoplastik mengikut nisbah campuran 1:1. Kesan penambahan pengisi ke atas sifat magnet, struktur dan morfologi nanokomposit dikaji. Dua parameter magnet, iaitu pemagnetan tepuan dan daya koersif nanokomposit didapati bergantung kepada penambahan pengisi dalam matriks. Interaksi antara kedua-dua pengisi dalam matriks TPNR juga mempengaruh sifat magnet. Pengisi hibrid (ferit NiZn dan nanotiub karbon) bertabur sekata dalam matriks termoplastik getah asli. Kehabluran semi-amorfus fasa polipropilena didapati berlawanan dengan peningkatan kehabluran pengisi apabila kandungan pengisi bertambah.
MeSH terms: Ataxia Telangiectasia; Autonomic Nervous System Diseases; Fenofibrate; Magnets