Missing value problem is common when analysing quantitative data. With the rapid growth of computing capabilities, advanced methods in particular those based on maximum likelihood estimation has been suggested to best handle the missing values problem. In this paper, two modern imputing approaches namely expectation-maximization (EM) and expectation-maximization with bootstrapping (EMB) are proposed in this paper for two kinds of linear functional relationship (LFRM) models, namely LFRM1 for full model and LFRM2 for linear functional relationship model when slope parameter is estimated using a nonparametric approach. The performance of EM and EMB are measured using mean absolute error, root-mean-square error and estimated bias. The results of the simulation study suggested that both EM and EMB methods are applicable to the LFRM with EMB algorithm outperforms the standard EM algorithm. Illustration using a practical example and a real data set is provided.
Leaves extracts of three different citrus species namely Citrus sinensis (Malta), Citrus paradisi (Grape fruit) and Citrus jambhiri (Khatti) were evaluated for their antioxidant, cytotoxic, antitumor, antimicrobial activities and finally the mineral contents were determined. Four types of extraction solvents (100, 80 and 50% methanol and distilled water heated at 50oC) were used for extraction of antioxidant compounds. Extracts yield increased with the elevated levels of aqueous component of organic solvent and our data showed the highest yield in aqueous extracts. All extraction regimes showed in vitro antioxidant activity. Citrus paradisi showed the highest total flavonoid content (TFC), total phenolic content (TPC), reducing power and 1,1-Diphenyl-2- picrylhydrazil free radical scavenging activity in all combinations of solvents followed by Citrus sinensis and Citrus jambhiri. Antioxidant activity was also increased with higher aqueous component of organic solvents in each case. While Citrus sinensis (in 100% methanolic solvent) and Citrus paradisi (in 50% methanolic extract) showed significant cytotoxicity (LD50 values <1000). Antitumor activity was observed in all extracts, however Citrus sinensis and Citrus paradisi (in 50% aqueous methanolic) extracts had the highest antitumor activity from the selected citrus species whereas no antimicrobial activity was observed at higher concentrations (4000 μgmL-1) against specified strains. We found high calcium contents in all three citrus species tested by atomic absorption method. The results showed that the leaves of selected Citrus species possess significant antioxidant, antitumor and cytotoxic activities. Citrus leaves extracts can be potentially helpful in antioxidant protection in food as well as in human body against lipid peroxidation and free radicals damage. It can further be evaluated after in vivo studies using animal models or identifications of high throughput methods for enhanced biological activities.
We consider the problem of outlier detection in bivariate exponential data fitted using the generalized linear model via Bayesian approach. We follow closely the work outlined by Unnikrishnan (2010) and present every step of the detection procedure in details. Due to the complexity of the resulting joint posterior distribution, we obtain the information on the posterior distribution from samples generated by Markov Chain Monte Carlo sampling, in particular, using either the Gibbs sampler or the Metropolis-Hastings algorithm. We use local breast cancer patients’ data to illustrate the implementation of the method.
Recently, there is strong interest on the subject of outlier problem in circular data. In this paper, we focus on detecting outliers in a circular regression model proposed by Down and Mardia. The basic properties of the model are available including the exact form of covariance matrix of the parameters. Hence, we intend to identify outliers in the model by looking at the effect of the outliers on the covariance matrix. The method resembles closely the COVRATIO statistic for the case of linear regression problem. The corresponding critical values and the performance of the outlier detection procedure are studied via simulations. For illustration, we apply the procedure on the wind data set.
This paper focuses on detecting outliers in the circular data which follow the wrapped normal distribution. We considered four discordance tests based on M, C, D and A statistics. The cut-off points of the four tests were obtained and the performance of the detection procedures was studied via simulations. In general, we showed that the discordance test based on the A statistic outperforms the other tests in all cases. For illustration, the city of Kuantan wind direction data set was considered.
The use of biodegradable material in membrane technology will be a great solution in reducing non-biodegradable
waste in the landfill. Membranes can often be useful as the recycle stream can usually be much cleaner than with other
techniques. This article describes the preparation of poly(l-lactic acid)-poly(ethylene glycol) (PLLA-PEG) free standing flat
sheet membranes with the presence of 5 wt. % activated carbon filler. PLLA-PEG crosslinked copolymer was synthesized
using PLLA with different molecular weight PEG prepolymers i.e. 4000, 6000 and 10000 g/mol; and excess hexamethylene
diisocyanate to form urethane linkages between the polymers. The reaction was carried out in a dichloromethane/
tetrahydrofuran dual-solvents system. The PLLA-PEG/AC membranes in the weight ratio of 7:3:0.5 were then fabricated
using solution casting and phase inversion techniques. The performance of the membranes was evaluated in terms of
permeation water flux (PWF), palm oil mill effluent (POME) permeation, flux decline and contact angle. It was found that
membrane containing 10000 g/mol PEG has the highest total mean in PWF, POME flux and hydraulic permeability with
values of 100.9 L/m2
.h, 51.45 L/m2
.h and 64.9º;62.9º, respectively, due to high porosity. All of the membranes were more
stable towards the flux decline of POME compared to water. At the same time, addition of AC to the copolymer considerably
enhances the texture and porosity of the fabricated membranes.
Periodontitis adalah penyakit kronik yang melibatkan kehilangan tulang dan inflamasi pada tisu periodontium. Interleukin-6 (IL-6) dan Tumor Necrosis Factor-α (TNF-α) merupakan penanda pro-inflamasi yang penting yang terlibat dalam periodontitis. Sebanyak 20 ekor tikus Sprague-Dawley dibahagikan kepada empat kumpulan iaitu: Kumpulan kawalan dengan salin normal (CS); kumpulan kawalan dengan madu Gelam 3 g/mL (CH); kumpulan ujian periodontitis dengan salin normal (TS); dan kumpulan ujian periodontitis dengan madu Gelam 3 g/mL (TH). Benang bersaiz 4/0 diikat pada molar pertama gigi tikus sebelah kiri bagi tujuan rangsangan penyakit periodontitis. Madu Gelam diberi secara paksa oral selama 15 hari. Selepas 15 hari, sampel plasma dan tisu dianalisis menggunakan kaedah Elisa dan pewarnaan histologi. Kehilangan tulang alveolar pada kumpulan TS adalah paling tinggi berbanding dengan kumpulan kawalan, CS dan CH namun, tiada perbezaan yang signifikan berbanding dengan kumpulan TH. Berdasarkan ujian imunohistokimia, ekspresi IL-6 dan TNF-α pada tisu periodontium adalah tinggi secara signifikan pada kumpulan TS berbanding dengan kumpulan lain. Namun, tiada perubahan aras IL-6 dan TNF-α yang signifikan pada plasma ke semua tikus kajian.
The otoliths of sea bass (Lates calcarifer) were sampled from 23 locations in Peninsular Malaysia in order to analyse the Sr/Ca, Mg/Ca and Ba/Ca ratios. This study found that these elements/Ca ratios in sea bass otoliths were correlated with the salinity zone (thalassic series) compared with elements/Ca ratios in ambient water. The contradictory pattern of Sr/ Ca ratios and Ba/Ca ratios in otoliths was found according to salinity zone variations. Thus, oligohaline waters showed the highest Ba/Ca ratios while the highest Sr/Ca ratios were recorded for saline waters. The terrigenous enrichment of Ba in water also affects the Ba content in otoliths. The presence of Mg in otoliths acts as a rival to Ba, thus affecting Mg and Ba deposition. Meanwhile, Ba is the tracer for salinity fluctuations based on the partition coefficient (D) and it shows significant changes. However, the elements in otoliths were found to originate indirectly from the water column. The sequence of the elements/Ca ratios in otoliths and ambient water was Sr/Ca>Mg/Ca>Ba/Ca and Sr/Ca>Ba/Ca>Mg/ Ca, respectively.
Differential cross sections for excitation to the n=2 states of atomic helium by electrons were computed for incident energies in the range from 30 to 50 eV. The n=2 states excitation cross sections are calculated with the use of closecoupling expansion with a non-orthogonal Laguerre-L2 basis function. The present status of agreement between theory and experiment for excitation of the ground-state was quite satisfactory.
By using sequences of linear maps on C*-algebras, we consider sets known as Korovkin sets, i.e. sets of the form
{a ε Asd/фn(a) → фo(a), фn(a2)→ фo (a2) = фo (a)2} In this paper we prove that if {фn} is a sequence of weak Kadison maps and '→' means norm, strong or weak convergence, then the Korovkin sets are JC-algebras. Furthermore if we assume that {фn} is a sequence of Schwarz maps or anti-Schwarz maps respectively, then the Korovkin sets become reversible JC-algebras.
Dengan menggunakan beberapa jenis jujukan pemetaan linear {фn} atas aljabar-C*, kita pertimbangkan set yang dikenali sebagai set Korovkin, i.i. set berbentuk {a ε Asd/фn(a) → фo(a), фn(a2)→ фo (a2) = фo (a)2} Dalam kertas ini ditunjukkan bahawa jika {фn} adalah jujukan pemetaan Kadison lemah dan penumpuan '→' menandakan penumpuan norma, kuat atau lemah, maka set Korovkin adalah aljabar-JC. Dengan andaian yang lebih kuat, i.i. {фn} masing-masing jujukan Schwarz atau anti-Schwarz, ditunjukkan bahawa set Korovkin merupakan aljabar-JC berbalik.
A study on water quality and heavy metal concentration in sediment at selected sites of Sungai Kelantan was carried out. Ten water samples were collected along the river for physical and chemical analysis and twenty-six water and sediment samples were collected for heavy metal analysis. Water was sampled at three different dates throughout the study period whereas sediments were collected once. In addition to heavy metal analysis, sediment samples were also analysed for texture, pH and organic content. The physical and chemical water quality analyses were carried out according to the APHA procedures. Result of water quality analysis (physico-chemical) indicated that Sungai Kelantan is characterised by excellent water quality and comparable to pristine ecosystems such as the National Park and Kenyir Lake. This river was classified into class I – class III based on Malaysian interim water quality standard criteria (INWQS). Heavy metals Pb, Zn, Cu and Cd was detected at low concentration in sediment samples, except for Fe and Mn. The presence of Fe and Mn in sediment samples was though to be of natural origin from the soil. Anthropogenic metal concentrations in sediment were low indicating that Sungai Kelantan has not experienced extreme pollution.
Suatu kajian telah dijalankan untuk menentukan potensi makroinvertebrat bentik sebagai penunjuk biologi di hulu Sungai
Ikan, Terengganu. Sebanyak lima stesen pensampelan telah dipilih untuk pensampelan makroinvertebrat bentik dan
analisis kualiti air. Pensampelan makroinvertebrat bentik telah dilakukan menggunakan jaring Surber dan analisis
kualiti air dilakukan menurut kaedah APHA. Piawaian Kualiti Air Kebangsaan (NWQS) telah digunakan untuk menilai
parameter kualiti air di kawasan kajian dan hasil menunjukkan Sungai Ikan berada dalam keadaan baik iaitu kelas I
hingga II. Ujian ANOVA satu hala menunjukkan bahawa kesemua parameter air yang diuji adalah seragam di sepanjang
kawasan kajian (p>0.05, α=0.05). Sebanyak 2 filum, 3 kelas, 8 order, 39 famili dan 1353 individu telah dikenal pasti dan
didominasi oleh famili Baetidae, Siphlonuridae, Simuliidae, Chironomidae dan Elmidae. Famili dominan didapati hadir
pada hampir kesemua stesen pensampelan. Memandangkan kualiti air adalah baik dan tidak berubah sepanjang kawasan
kajian, ujian CCA dilakukan untuk memperlihatkan faktor persekitaran lain yang mempengaruhi sebaran makroinvertebrat
terutamanya famili dominan. Hasil ujian CCA menunjukkan pengaruh persekitaran yang khusus terhadap famili tertentu
dan mempunyai pengaruh yang kuat terhadap sebaran makroinvertebrat bentik. Ujian korelasi menunjukkan batuan
besar mempunyai pengaruh besar terhadap sebaran famili Baetidae, Siphlonuridae dan sub-famili Orthocladiinae,
manakala komposisi pasir pula mempunyai pengaruh terhadap famili Elmidae. Hasil kajian ini menunjukkan dalam
ekosistem yang bersih, faktor persekitaran habitat adalah kritikal untuk diambil kira dalam menentukan taksa tertentu
yang sesuai digunakan sebagai penunjuk biologi ekosistem sungai rekreasi.
A study on the chironomids (Diptera:Chironomidae) diversity at pristine ecosystem was carried out at upstream of Sungai Langat, Selangor. The study determines chironomids distribution and composition at 7 streams and river within the upstream site of Langat Catchment. Chironomid was sampled using Surber net and water quality was measured based on Malaysia WQI. The result indicated that Chironomidae was represented by three subfamilies namely Chironominae, Orthocladiinae and Tanypodinae, which comprises of 2502 individuals. Chironominae was the most dominant subfamily (1619 individuals) followed by Orthocladinae (629 individuals) and Tanypodinae (254 individuals). Polypedilum (subfamily: Chironominae) is the most dominant genus found followed by Rheocricotopus (subfamily: Orthocladiinae), Microtendipes and Cryptochironomus. Polypedilum was abundant in all stations except Sg. Langat 3 which was dominated by Rheocricotopus. Sungai Langat 3 has the highest number of individual (1113) which is (44.5%) from total chironomid individual and followed by Sg. Lolo with 468 individuals that were dominated by Polypedilum.
Satu analisis penentuan parameter kualiti air yang penting untuk penilaian ekosistem cetek telah dilakukan menggunakan kaedah multivariat. Sebanyak 14 parameter kualiti air yang melibatkan komponen biologi, fizik dan kimia telah dikumpulkan setiap bulan selama satu tahun. Data dianalisis menggunakan ujian faktor yang melibatkan tiga proses iaitu mengenal pasti korelasi antara faktor, mengekstrak faktor dan seterusnya melihat kesan gabungan faktor-faktor tersebut. Proses pertama melibatkan pengelompokkan parameter yang berkorelasi kuat ke dalam faktor tersendiri dan mengeluarkan parameter yang mempunyai lebih daripada satu faktor. Analisis pengelasan agglomeratif hierarki (HACA) dan analisis diskriminan (DA) juga dilakukan untuk memperlihatkan kelompokan dan pengaruh faktor terhadap kualiti air tasik. Hasil analisis menunjukkan kualiti air Tasik Chini dipengaruhi oleh lebih daripada satu faktor. Hasil kajian menunjukkan komponen biologi dan kimia (nutrien) mempunyai pengaruh kuat dalam penentuan kualiti air tasik. Parameter berasaskan biologi iaitu BOD5, COD, klorofil a dan kimia (nitrat dan ortofosfat) adalah parameter yang
penting di Tasik Chini. Ketiga-tiga analisis yang dijalankan menunjukkan kepentingan penentuan komponen biologi dan kimia bagi menentukan kualiti air Tasik Chini.
Satu kajian penilaian kualiti ekosistem sungai di Sungai Kongkoi di Negeri Sembilan telah dijalankan dengan menggunakan makroinvetebrat bentik sebagai penunjuk biologi. Pensampelan telah dijalankan di 5 stesen yang telah dipilih dan tiga replikasi sampel air telah diambil untuk dianalisis. Makroinvertebrat bentik telah disampel dengan menggunakan jaring Surber pada tiga titik pensampelan yang berbeza. Pengukuran in situ telah dilakukan bagi parameter suhu, pH, oksigen terlarut (DO) dan kekonduksian dengan menggunakan meter YSI 556 MPS. Analisis makmal dilakukan
untuk parameter jumlah pepejal terampai (TSS), permintaan oksigen biokimia (BOD5), permintaan oksigen kimia (COD) dan ammoniakal-nitrogen (NH3-N). Berdasarkan kepada indeks kualiti air (WQI) dan pengkelasan sungai di Malaysia (NWQS), Sungai Kongkoi didapati mempunyai kualiti air yang baik dan berada dalam Kelas 1. Ujian ANOVA satu hala menunjukkan bahawa kebanyakan parameter kualiti air tidak berbeza dengan nyata di sepanjang stesen pensampelan (p>0.05, α=0.05). Sejumlah 2 filum, 3 kelas, 8 order, 32 famili dan 3228 individu makroinvertebrat bentik telah dikenal
pasti dan didominasi oleh famili Baetidae, Perlidae, Hydropsychidae dan Elmidae. Ujian faktor menunjukkan setiap famili di atas adalah paling sesuai digunakan sebagai penunjuk biologi di kawasan rekreasi.
The effect of different plasticizers on the properties of PAN–LiCF3SO3 polymer electrolytes has been studied. Propylene carbonate (PC) and ethylene carbonate (EC) having different values of donor numbers, dielectric constant and viscosity have been used as plasticizers. The highest room temperature conductivity for the film in the PAN–LiCF3SO3 system was 3.04 × 10-4 S cm-1. The highest room temperature conductivity for the films in the PAN–EC–LiCF3SO3 system and the PAN–PC–LiCF3SO3 system was 1.32 × 10-3 and 8.64 × 10-4 S cm-1. The addition of plasticizers has been found to enhance the conductivity of polymer electrolytes by increasing the amorphous content as well as by dissociating the ion aggregates present in polymer electrolyte. Conductivity temperature-dependence studies of these plasticized PAN-salt systems were carried out in the temperature range of 303 to 373 K. The conductivity versus temperature plots obeyed an Arrhenius type variation. The structural and complex formations were studied by X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy.
A preliminary study was conducted to determine the presence and abundance of aquatic worms in Lake Chini ecosystem, Pahang (Gumum Sea). Samplings were conducted twice in 2000. Water quality analysis was conducted to determine the water quality of the lake at the sampling locations. Results showed that nutrient levels in the water body was low and values for other physical parameters such as temperature, pH and conductivity suggested that Gumum Sea in Lake Chini is free from pollution. According to Malaysian interim river classification (Department of Environment, Malaysia), Lake Chini falls within class I to III which indicates good water quality. Annelida was the most dominant phylum found in the study area, which comprise of two major families namely Naididae and Tubificidae. This phylum contributed about 59% of the total individuals sampled and the rests were Arthropoda and Plathyhelmintes. Naididae was the most dominat family and contributed over 98% of the toal population of aquatic worms present. Dero, Aulophorus, Pristina, Branchiodrilus and Ripistes were amongst the dominant genera and showed good adaptations to the pollution free ecosystem of Lake Chini.
Kajian kepelbagaian dan penyebaran ikan di Tasik Chini telah dijalankan menggunakan jaring insang sebagai alat penangkapan. Sebanyak lapan stesen pensampelan telah dipilih (habitat berbeza) di seluruh tasik dan pensampelan telah dilakukan secara rawak di kawasan yang terpilih. Sejumlah 24 spesies ikan telah direkodkan yang terdiri daripada 944 ekor ikan. Kebanyakan ikan yang direkodkan adalah terdiri daripada famili Cyprinidae. Spesies dominan yang ditemui di Tasik Chini ialah loma (Thynnichthys thynnoides), cemperas (Cyclocheilichythys apogon) dan potok (Notopterus notopterus). Hasil ujian t-berpasangan menunjukkan terdapat perbezaan bermakna kepadatan ikan yang ditangkap di antara waktu siang dan waktu malam (p = 0.01, α = 0.05) dan spesies pemangsa didapati paling dominan pada waktu malam. Kepelbagaian dan kepadatan ikan didapati lebih tinggi semasa pensampelan musim monsun yang dipercayai kesan daripada kemasukan ikan-ikan dari Sungai Pahang melalui Sungai Chini.
Microbial production of natural products using metabolic engineering and synthetic biology approaches often involves
the assembly of multiple gene fragments including regulatory elements, especially when using eukaryotes as hosts.
Traditional cloning strategy using restriction enzyme digestion and ligation are laborious and inflexible owing to the
high number of sequential cloning steps, limited cutting sites and generation of undesired ‘scar’ sequences. In this study,
a homology-based isothermal DNA assembly method was carried out for one-step simultaneous assembly of multiple DNA
fragments to engineer plant phenylpropanoid biosynthesis in Saccharomyces cerevisiae. Rapid construction of yeast
plasmid harboring dual gene expression cassettes was achieved via isothermal assembly of four DNA fragments designed
with 20 bp overlapping sequences. The rate-limiting enzyme of phenylpropanoid pathway, cinnamate 4-hydroxylase
encoded by C4H gene from Polygonum minus was cloned in tandem with yeast promoter and terminator elements of S.
cerevisiae for efficient construction of phenylpropanoid biosynthetic pathway in recombinant yeast. The assembled pAGCAT (C4H-ADH1t-TEF1p) shuttle plasmid and transformation of S. cerevisiae with the plant C4H gene were confirmed
via PCR analysis. Based on these findings, the yeast shuttle plasmid harboring P. minus phenylpropanoid biosynthesis
gene was efficiently constructed to be the starting platform for the production of plant natural products in geneticallyengineered S. cerevisiae.
Copolymers from different feed compositions of glycidyl methacrylate (GMA) and tetrahydrofurfuryl acrylate (THFA) were synthesized using free radical polymerization in toluene solution at 70±1°C using benzoyl peroxide (BPO) as initiator. The polymers were characterized by 1 H NMR,13C NMR and DEPT spectroscopic techniques. The copolymer compositions were determined using 1H NMR analysis. Reactivity ratios for GMA and THFA were determined by the Kelen-Tudos, TidwellMortimer and error-in-variables model methods. The results showed that all these copolymerizations were strictly linear systems describable by the Mayo-Lewis equation based on the terminal model and that accurate reactivity ratio data can be obtained.